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Sample records for walks estimate land

  1. Random Walks Estimate Land Value

    CERN Document Server

    Blanchard, Ph

    2010-01-01

    Expected urban population doubling calls for a compelling theory of the city. Random walks and diffusions defined on spatial city graphs spot hidden areas of geographical isolation in the urban landscape going downhill. First--passage time to a place correlates with assessed value of land in that. The method accounting the average number of random turns at junctions on the way to reach any particular place in the city from various starting points could be used to identify isolated neighborhoods in big cities with a complex web of roads, walkways and public transport systems.

  2. Disaggregate land uses and walking.

    Science.gov (United States)

    McConville, Megan E; Rodríguez, Daniel A; Clifton, Kelly; Cho, Gihyoug; Fleischhacker, Sheila

    2011-01-01

    Although researchers have explored associations between mixed-use development and physical activity, few have examined the influence of specific land uses. This study analyzes how the accessibility, intensity, and diversity of nonresidential land uses are related to walking for transportation. Multinomial logistic regression was used to investigate associations between walking for transportation and neighborhood land uses in a choice-based sample of individuals (n=260) in Montgomery County MD. Land uses examined included banks, bus stops, fast-food restaurants, grocery stores, libraries, rail stations, offices, parks, recreation centers, non-fast-food restaurants, retail, schools, sports facilities, night uses, physical activity uses, and social uses. Exposure to these uses was measured as the street distance from participants' homes to the closest instance of each land use (accessibility); the number of instances of each land use (intensity); and the number of different land uses (diversity). Data were collected from 2004-2006 and analyzed in 2009-2010. After adjusting for individual-level characteristics, the distances to banks, bus stops, fast-food restaurants, grocery stores, rail stations, physical activity uses, recreational facilities, restaurants, social uses and sports facilities were associated negatively with transportation walking (ORs [95% CI] range from 0.01 [0.001, 0.11] to 0.91 [0.85, 0.97]). The intensities of bus stops, grocery stores, offices, and retail stores in participants' neighborhoods were associated positively with transportation walking (ORs [95% CI] range from 1.05 [1.01, 1.08] to 5.42 [1.73, 17.01]). Land-use diversity also was associated positively with walking for transportation (ORs [95% CI] range from 1.39 [1.20, 1.59] to 1.69 [1.30, 2.20]). The accessibility and intensity of certain nonresidential land uses, along with land-use diversity, are positively associated with walking for transportation. A careful mix of land uses in a

  3. Walking pattern classification and walking distance estimation algorithms using gait phase information.

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    Wang, Jeen-Shing; Lin, Che-Wei; Yang, Ya-Ting C; Ho, Yu-Jen

    2012-10-01

    This paper presents a walking pattern classification and a walking distance estimation algorithm using gait phase information. A gait phase information retrieval algorithm was developed to analyze the duration of the phases in a gait cycle (i.e., stance, push-off, swing, and heel-strike phases). Based on the gait phase information, a decision tree based on the relations between gait phases was constructed for classifying three different walking patterns (level walking, walking upstairs, and walking downstairs). Gait phase information was also used for developing a walking distance estimation algorithm. The walking distance estimation algorithm consists of the processes of step count and step length estimation. The proposed walking pattern classification and walking distance estimation algorithm have been validated by a series of experiments. The accuracy of the proposed walking pattern classification was 98.87%, 95.45%, and 95.00% for level walking, walking upstairs, and walking downstairs, respectively. The accuracy of the proposed walking distance estimation algorithm was 96.42% over a walking distance.

  4. Discriminative Parameter Estimation for Random Walks Segmentation

    OpenAIRE

    Baudin, Pierre-Yves; Goodman, Danny; Kumar, Puneet; Azzabou, Noura; Carlier, Pierre G.; Paragios, Nikos; Pawan Kumar, M.

    2013-01-01

    International audience; The Random Walks (RW) algorithm is one of the most e - cient and easy-to-use probabilistic segmentation methods. By combining contrast terms with prior terms, it provides accurate segmentations of medical images in a fully automated manner. However, one of the main drawbacks of using the RW algorithm is that its parameters have to be hand-tuned. we propose a novel discriminative learning framework that estimates the parameters using a training dataset. The main challen...

  5. Discriminative parameter estimation for random walks segmentation.

    Science.gov (United States)

    Baudin, Pierre-Yves; Goodman, Danny; Kumrnar, Puneet; Azzabou, Noura; Carlier, Pierre G; Paragios, Nikos; Kumar, M Pawan

    2013-01-01

    The Random Walks (RW) algorithm is one of the most efficient and easy-to-use probabilistic segmentation methods. By combining contrast terms with prior terms, it provides accurate segmentations of medical images in a fully automated manner. However, one of the main drawbacks of using the RW algorithm is that its parameters have to be hand-tuned. we propose a novel discriminative learning framework that estimates the parameters using a training dataset. The main challenge we face is that the training samples are not fully supervised. Specifically, they provide a hard segmentation of the images, instead of a probabilistic segmentation. We overcome this challenge by treating the optimal probabilistic segmentation that is compatible with the given hard segmentation as a latent variable. This allows us to employ the latent support vector machine formulation for parameter estimation. We show that our approach significantly outperforms the baseline methods on a challenging dataset consisting of real clinical 3D MRI volumes of skeletal muscles.

  6. IMU-based ambulatory walking speed estimation in constrained treadmill and overground walking.

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    Yang, Shuozhi; Li, Qingguo

    2012-01-01

    This study evaluated the performance of a walking speed estimation system based on using an inertial measurement unit (IMU), a combination of accelerometers and gyroscopes. The walking speed estimation algorithm segments the walking sequence into individual stride cycles (two steps) based on the inverted pendulum-like behaviour of the stance leg during walking and it integrates the angular velocity and linear accelerations of the shank to determine the displacement of each stride. The evaluation was performed in both treadmill and overground walking experiments with various constraints on walking speed, step length and step frequency to provide a relatively comprehensive assessment of the system. Promising results were obtained in providing accurate and consistent walking speed/step length estimation in different walking conditions. An overall percentage root mean squared error (%RMSE) of 4.2 and 4.0% was achieved in treadmill and overground walking experiments, respectively. With an increasing interest in understanding human walking biomechanics, the IMU-based ambulatory system could provide a useful walking speed/step length measurement/control tool for constrained walking studies.

  7. Walking Algorithm of Humanoid Robot on Uneven Terrain with Terrain Estimation

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    Jiang Yi

    2016-02-01

    Full Text Available Humanoid robots are expected to achieve stable walking on uneven terrains. In this paper, a control algorithm for humanoid robots walking on previously unknown terrains with terrain estimation is proposed, which requires only minimum modification to the original walking gait. The swing foot trajectory is redesigned to ensure that the foot lands at the desired horizontal positions under various terrain height. A compliant terrain adaptation method is applied to the landing foot to achieve a firm contact with the ground. Then a terrain estimation method that takes into account the deformations of the linkages is applied, providing the target for the following correction and adjustment. The algorithm was validated through walking experiments on uneven terrains with the full-size humanoid robot Kong.

  8. Validation of Walk Score for estimating access to walkable amenities.

    Science.gov (United States)

    Carr, Lucas J; Dunsiger, Shira I; Marcus, Bess H

    2011-11-01

    Proximity to walkable destinations or amenities is thought to influence physical activity behaviour. Previous efforts attempting to calculate neighbourhood walkability have relied on self-report or time-intensive and costly measures. Walk Score is a novel and publicly available website that estimates neighbourhood walkability based on proximity to 13 amenity categories (eg, grocery stores, coffee shops, restaurants, bars, movie theatres, schools, parks, libraries, book stores, fitness centres, drug stores, hardware stores, clothing/music stores). The purpose of this study is to test the validity and reliability of Walk Score for estimating access to objectively measured walkable amenities. Walk Scores of 379 residential/non-residential addresses in Rhode Island were manually calculated. Geographic information systems (GIS) was used to objectively measure 4194 walkable amenities in the 13 Walk Score categories. GIS data were aggregated from publicly available data sources. Sums of amenities within each category were matched to address data, and Pearson correlations were calculated between the category sums and address Walk Scores. Significant correlations were identified between Walk Score and all categories of aggregated walkable destinations within a 1-mile buffer of the 379 residential and non-residential addresses. Test-retest reliability correlation coefficients for a subsample of 100 addresses were 1.0. These results support Walk Score as a reliable and valid measure of estimating access to walkable amenities. Walk Score may be a convenient and inexpensive option for researchers interested in exploring the relationship between access to walkable amenities and health behaviours such as physical activity.

  9. Stride Counting in Human Walking and Walking Distance Estimation Using Insole Sensors

    Science.gov (United States)

    Truong, Phuc Huu; Lee, Jinwook; Kwon, Ae-Ran; Jeong, Gu-Min

    2016-01-01

    This paper proposes a novel method of estimating walking distance based on a precise counting of walking strides using insole sensors. We use an inertial triaxial accelerometer and eight pressure sensors installed in the insole of a shoe to record walkers’ movement data. The data is then transmitted to a smartphone to filter out noise and determine stance and swing phases. Based on phase information, we count the number of strides traveled and estimate the movement distance. To evaluate the accuracy of the proposed method, we created two walking databases on seven healthy participants and tested the proposed method. The first database, which is called the short distance database, consists of collected data from all seven healthy subjects walking on a 16 m distance. The second one, named the long distance database, is constructed from walking data of three healthy subjects who have participated in the short database for an 89 m distance. The experimental results show that the proposed method performs walking distance estimation accurately with the mean error rates of 4.8% and 3.1% for the short and long distance databases, respectively. Moreover, the maximum difference of the swing phase determination with respect to time is 0.08 s and 0.06 s for starting and stopping points of swing phases, respectively. Therefore, the stride counting method provides a highly precise result when subjects walk. PMID:27271634

  10. Stride Counting in Human Walking and Walking Distance Estimation Using Insole Sensors

    Directory of Open Access Journals (Sweden)

    Phuc Huu Truong

    2016-06-01

    Full Text Available This paper proposes a novel method of estimating walking distance based on a precise counting of walking strides using insole sensors. We use an inertial triaxial accelerometer and eight pressure sensors installed in the insole of a shoe to record walkers’ movement data. The data is then transmitted to a smartphone to filter out noise and determine stance and swing phases. Based on phase information, we count the number of strides traveled and estimate the movement distance. To evaluate the accuracy of the proposed method, we created two walking databases on seven healthy participants and tested the proposed method. The first database, which is called the short distance database, consists of collected data from all seven healthy subjects walking on a 16 m distance. The second one, named the long distance database, is constructed from walking data of three healthy subjects who have participated in the short database for an 89 m distance. The experimental results show that the proposed method performs walking distance estimation accurately with the mean error rates of 4.8% and 3.1% for the short and long distance databases, respectively. Moreover, the maximum difference of the swing phase determination with respect to time is 0.08 s and 0.06 s for starting and stopping points of swing phases, respectively. Therefore, the stride counting method provides a highly precise result when subjects walk.

  11. Treadmill motor current value based walk phase estimation.

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    Ohki, Eiichi; Nakashima, Yasutaka; Ando, Takeshi; Fujie, Masakatsu G

    2009-01-01

    We have developed a gait rehabilitation robot for hemiplegic patients using the treadmill. A walk phase, which includes time balance of stance and swing legs, is one of the most basic indexes to evaluate patients' gait. In addition, the walking phase is one of the indexes to control our robotic rehabilitation system. However, conventional methods to measure the walk phase require another system such as the foot switch and force plate. In this paper, an original algorithm to estimate the walk phase of a person on a treadmill using only the current value of DC motor to control the treadmill velocity is proposed. This algorithm was verified by experiments on five healthy subjects, and the walk phase of four subjects could be estimated in 0.2 (s) errors. However, the algorithm had erroneously identified a period of time in the stance phase as swing phase time when little body weight loaded on the subject's leg. Because a period of time with little body weight to affected leg is often observed in a hemiplegic walk, the proposed algorithm might fail to properly estimate the walk phase of hemiplegic patients. However, this algorithm could be used to estimate the time when body weight is loaded on patient legs, and thus could be used as a new quantitative evaluation index.

  12. Comparison of Estimated and Measured Muscle Activity During Inclined Walking.

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    Alexander, Nathalie; Schwameder, Hermann

    2016-04-01

    While inclined walking is a frequent daily activity, muscle forces during this activity have rarely been examined. Musculoskeletal models are commonly used to estimate internal forces in healthy populations, but these require a priori validation. The aim of this study was to compare estimated muscle activity using a musculoskeletal model with measured EMG data during inclined walking. Ten healthy male participants walked at different inclinations of 0°, ± 6°, ± 12°, and ± 18° on a ramp equipped with 2 force plates. Kinematics, kinetics, and muscle activity of the musculus (m.) biceps femoris, m. rectus femoris, m. vastus lateralis, m. tibialis anterior, and m. gastrocnemius lateralis were recorded. Agreement between estimated and measured muscle activity was determined via correlation coefficients, mean absolute errors, and trend analysis. Correlation coefficients between estimated and measured muscle activity for approximately 69% of the conditions were above 0.7. Mean absolute errors were rather high with only approximately 38% being ≤ 30%. Trend analysis revealed similar estimated and measured muscle activities for all muscles and tasks (uphill and downhill walking), except m. tibialis anterior during uphill walking. This model can be used for further analysis in similar groups of participants.

  13. Ant-inspired density estimation via random walks.

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    Musco, Cameron; Su, Hsin-Hao; Lynch, Nancy A

    2017-09-19

    Many ant species use distributed population density estimation in applications ranging from quorum sensing, to task allocation, to appraisal of enemy colony strength. It has been shown that ants estimate local population density by tracking encounter rates: The higher the density, the more often the ants bump into each other. We study distributed density estimation from a theoretical perspective. We prove that a group of anonymous agents randomly walking on a grid are able to estimate their density within a small multiplicative error in few steps by measuring their rates of encounter with other agents. Despite dependencies inherent in the fact that nearby agents may collide repeatedly (and, worse, cannot recognize when this happens), our bound nearly matches what would be required to estimate density by independently sampling grid locations. From a biological perspective, our work helps shed light on how ants and other social insects can obtain relatively accurate density estimates via encounter rates. From a technical perspective, our analysis provides tools for understanding complex dependencies in the collision probabilities of multiple random walks. We bound the strength of these dependencies using local mixing properties of the underlying graph. Our results extend beyond the grid to more general graphs, and we discuss applications to size estimation for social networks, density estimation for robot swarms, and random walk-based sampling for sensor networks.

  14. Kinematic Adaptations of Forward and Backward Walking on Land and in Water

    Directory of Open Access Journals (Sweden)

    Cadenas-Sanchez Cristina

    2015-12-01

    Full Text Available The aim of this study was to compare sagittal plane lower limb kinematics during walking on land and submerged to the hip in water. Eight healthy adults (age 22.1 ± 1.1 years, body height 174.8 ± 7.1 cm, body mass 63.4 ± 6.2 kg were asked to cover a distance of 10 m at comfortable speed with controlled step frequency, walking forward or backward. Sagittal plane lower limb kinematics were obtained from three dimensional video analysis to compare spatiotemporal gait parameters and joint angles at selected events using two-way repeated measures ANOVA. Key findings were a reduced walking speed, stride length, step length and a support phase in water, and step length asymmetry was higher compared to the land condition (p<0.05. At initial contact, knees and hips were more flexed during walking forward in water, whilst, ankles were more dorsiflexed during walking backward in water. At final stance, knees and ankles were more flexed during forward walking, whilst the hip was more flexed during backward walking. These results show how walking in water differs from walking on land, and provide valuable insights into the development and prescription of rehabilitation and training programs.

  15. Kinematic Adaptations of Forward And Backward Walking on Land and in Water

    Science.gov (United States)

    Cadenas-Sanchez, Cristina; Arellano, Raúl; Vanrenterghem, Jos; López-Contreras, Gracia

    2015-01-01

    The aim of this study was to compare sagittal plane lower limb kinematics during walking on land and submerged to the hip in water. Eight healthy adults (age 22.1 ± 1.1 years, body height 174.8 ± 7.1 cm, body mass 63.4 ± 6.2 kg) were asked to cover a distance of 10 m at comfortable speed with controlled step frequency, walking forward or backward. Sagittal plane lower limb kinematics were obtained from three dimensional video analysis to compare spatiotemporal gait parameters and joint angles at selected events using two-way repeated measures ANOVA. Key findings were a reduced walking speed, stride length, step length and a support phase in water, and step length asymmetry was higher compared to the land condition (p<0.05). At initial contact, knees and hips were more flexed during walking forward in water, whilst, ankles were more dorsiflexed during walking backward in water. At final stance, knees and ankles were more flexed during forward walking, whilst the hip was more flexed during backward walking. These results show how walking in water differs from walking on land, and provide valuable insights into the development and prescription of rehabilitation and training programs. PMID:26839602

  16. Estimation of passive ankle joint moment during standing and walking.

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    Muraoka, Tetsuro; Muramatsu, Tadashi; Takeshita, Daisuke; Kanehisa, Hiroaki; Fukunaga, Tetsuo

    2005-02-01

    This study estimated the passive ankle joint moment during standing and walking initiation and its contribution to total ankle joint moment during that time. The decrement of passive joint moment due to muscle fascicle shortening upon contraction was taken into account. Muscle fascicle length in the medial gastrocnemius, which was assumed to represent muscle fascicle length in plantarflexors, was measured using ultrasonography during standing, walking initiation, and cyclical slow passive ankle joint motion. Total ankle joint moment during standing and walking initiation was calculated from ground reaction forces and joint kinematics. Passive ankle joint moment during the cyclical ankle joint motion was measured via a dynamometer. Passive ankle joint moment during standing and at the time (Tp) when the MG muscle-tendon complex length was longest in the stance phase during walking initiation were 2.3 and 5.4 Nm, respectively. The muscle fascicle shortened by 2.9 mm during standing compared with the length at rest, which decreased the contribution of passive joint moment from 19.9% to 17.4%. The muscle fascicle shortened by 4.3 mm at Tp compared with the length at rest, which decreased the contribution of passive joint moment from 8.0% to 5.8%. These findings suggest that (a) passive ankle joint moment plays an important role during standing and walking initiation even in view of the decrement of passive joint moment due to muscle fascicle shortening upon muscle contraction, and (b) muscle fascicle shortening upon muscle contraction must be taken into account when estimating passive joint moment during movements.

  17. Estimating mood variation from MPF of EMG during walking.

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    Kinase, Yuta; Venture, Gentiane

    2013-01-01

    The information on the mood included in behavior is classified into nonverbal information, and is included in behavior without necessarily being based on the intention of an agent. Consequently, it is considered that we can estimate the mood from the measurement of the behavior. In this work, we estimate the mood from the surface electromyogram (EMG) information of the muscles of the upper limb during walking. Identification of emotion and mood using EMG information has been done with a variety of methods until now. In addition, it is known that human walking includes information that is specific to the individual and be affected by mood. Therefore, it is thought that the EMG analysis of walking is effective in the identification of human mood. In this work, we made a subject walk in the various mood states and answer psychological tests that measure the mood. We use two types of tasks (music listening and numerical calculation) for evoking different moods. Statistical features of EMG signals are calculated using Fast Fourier Transform (FFT) and Principal Component Analysis (PCA). These statistical features are related with psychological test scores, using regression analysis. In this paper, we have shown the statistical significance of the linear model to predict the variation of mood based on the information on the variation in MPF of EMG data of the muscles of the upper limb during walking with different moods. This shows the validity of such a mapping. However, since the interpretability of the model is still low, it cannot be said that the model is able to accurately represent the mood variation. Creating a model with high accuracy is a key issue in the future.

  18. Hypotensive response after water-walking and land-walking exercise sessions in healthy trained and untrained women

    Directory of Open Access Journals (Sweden)

    Bocalini DS

    2011-08-01

    Full Text Available Daniel Rodriguez1, Valter Silva2, Jonato Prestes3, Roberta Luksevicius Rica4, Andrey Jorge Serra5, Danilo Sales Bocalini6, Francisco Luciano Pontes Junior71São Judas Tadeu University, São Paulo, SP, Brazil; 2College of Physical Education of Sorocaba, Sorocaba, SP, Brazil; 3Graduation Program in Physical Education, Catholic University of Brasilia, Brasilia-DF, Brazil; 4Department of Physical Education, Arbos College, São Bernardo do Campo, SP, Brazil; 5Department of Physical Education and Laboratory of Rehabilitation Science, Nove de Julho University, São Paulo, SP, Brazil; 6Department of Medicine, Federal University of São Paulo – Escola Paulista de Medicina, São Paulo, SP, Brazil; 7School of Arts, Sciences and Humanities, University of São Paulo, São Paulo, SP, BrazilBackground: The aim of this study was to compare post-exercise hypotension after acute sessions of water-walking and land-walking in healthy trained and untrained women.Methods: Twenty-three untrained (n = 12 and trained (n = 11 normotensive women performed two walking sessions in water and on land at 40% of peak VO2 for 45 minutes. Systolic and diastolic blood pressure and mean arterial pressure were measured 15, 30, 45, and 60 minutes after the exercise sessions.Results: No differences were found between the groups for age and anthropometric parameters, but peak VO2 for the trained women (45 ± 8 mL/kg/minute was higher than for the untrained women (31 ± 3 mL/kg/minute. No differences were found between the groups with regard to systolic and diastolic blood pressure and mean arterial pressure after water immersion. The heart rate in the trained group (62 ± 3 beats per minute [bpm] was significantly lower (P < 0.05 than in the untrained group (72 ± 4 bpm on land, and after water immersion, this difference disappeared (58 ± 5 bpm in the trained women and 66 ± 5 bpm in the untrained women. Sixty minutes after water-walking, systolic blood pressure (108 ± 8 mmHg vs

  19. Estimation of detection thresholds for redirected walking techniques.

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    Steinicke, Frank; Bruder, Gerd; Jerald, Jason; Frenz, Harald; Lappe, Markus

    2010-01-01

    In immersive virtual environments (IVEs), users can control their virtual viewpoint by moving their tracked head and walking through the real world. Usually, movements in the real world are mapped one-to-one to virtual camera motions. With redirection techniques, the virtual camera is manipulated by applying gains to user motion so that the virtual world moves differently than the real world. Thus, users can walk through large-scale IVEs while physically remaining in a reasonably small workspace. In psychophysical experiments with a two-alternative forced-choice task, we have quantified how much humans can unknowingly be redirected on physical paths that are different from the visually perceived paths. We tested 12 subjects in three different experiments: (E1) discrimination between virtual and physical rotations, (E2) discrimination between virtual and physical straightforward movements, and (E3) discrimination of path curvature. In experiment E1, subjects performed rotations with different gains, and then had to choose whether the visually perceived rotation was smaller or greater than the physical rotation. In experiment E2, subjects chose whether the physical walk was shorter or longer than the visually perceived scaled travel distance. In experiment E3, subjects estimate the path curvature when walking a curved path in the real world while the visual display shows a straight path in the virtual world. Our results show that users can be turned physically about 49 percent more or 20 percent less than the perceived virtual rotation, distances can be downscaled by 14 percent and upscaled by 26 percent, and users can be redirected on a circular arc with a radius greater than 22 m while they believe that they are walking straight.

  20. Checklist and "Pollard Walk" butterfly survey methods on public lands

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    Royer, Ronald A.; Austin, Jane E.; Newton, Wesley E.

    1998-01-01

    Checklist and “Pollard Walk” butterfly survey methods were contemporaneously applied to seven public sites in North Dakota during the summer of 1995. Results were compared for effect of method and site on total number of butterflies and total number of species detected per hour. Checklist searching produced significantly more butterfly detections per hour than Pollard Walks at all sites. Number of species detected per hour did not differ significantly either among sites or between methods. Many species were detected by only one method, and at most sites generalist and invader species were more likely to be observed during checklist searches than during Pollard Walks. Results indicate that checklist surveys are a more efficient means for initial determination of a species list for a site, whereas for long-term monitoring the Pollard Walk is more practical and statistically manageable. Pollard Walk transects are thus recommended once a prairie butterfly fauna has been defined for a site by checklist surveys.

  1. Approximated maximum likelihood estimation in multifractal random walks

    CERN Document Server

    Løvsletten, Ola

    2011-01-01

    We present an approximated maximum likelihood method for the multifractal random walk processes of [E. Bacry et al., Phys. Rev. E 64, 026103 (2001)]. The likelihood is computed using a Laplace approximation and a truncation in the dependency structure for the latent volatility. The procedure is implemented as a package in the R computer language. Its performance is tested on synthetic data and compared to an inference approach based on the generalized method of moments. The method is applied to estimate parameters for various financial stock indices.

  2. Biomechanical characteristics of adults walking in shallow water and on land.

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    Barela, Ana M F; Stolf, Sandro F; Duarte, Marcos

    2006-06-01

    Although water environment has been employed for different physical activities, there is little available information regarding the biomechanical characteristics of walking in shallow water. In the present study, we investigated the kinematics, ground reaction forces (GRF), and electromyographic (EMG) activation patterns of eight selected muscles of adults walking in shallow water and on land. Ten healthy adults were videotaped while walking at self-selected comfortable speeds on land and in water (at the Xiphoid process level). In both conditions there was a force plate embedded in the middle of each walkway to register the GRF components. Reflective markers were placed over main anatomical landmarks and they were digitalized later to obtain stride characteristics and joint angle information. In general, walking in water was different to walking on land in many aspects and these differences were attributed to the drag force, the apparent body weight reduction, and the lower comfortable speed during walking in shallow water. The joint range of motions (ROM) were not different, the segment ROM, magnitudes of GRF components, impact force, and impulse were different between the two conditions. The present results will contribute to a better understanding of this activity in the context of training and rehabilitation.

  3. Slope Estimation during Normal Walking Using a Shank-Mounted Inertial Sensor

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    Juan C. Álvarez

    2012-08-01

    Full Text Available In this paper we propose an approach for the estimation of the slope of the walking surface during normal walking using a body-worn sensor composed of a biaxial accelerometer and a uniaxial gyroscope attached to the shank. It builds upon a state of the art technique that was successfully used to estimate the walking velocity from walking stride data, but did not work when used to estimate the slope of the walking surface. As claimed by the authors, the reason was that it did not take into account the actual inclination of the shank of the stance leg at the beginning of the stride (mid stance. In this paper, inspired by the biomechanical characteristics of human walking, we propose to solve this issue by using the accelerometer as a tilt sensor, assuming that at mid stance it is only measuring the gravity acceleration. Results from a set of experiments involving several users walking at different inclinations on a treadmill confirm the feasibility of our approach. A statistical analysis of slope estimations shows in first instance that the technique is capable of distinguishing the different slopes of the walking surface for every subject. It reports a global RMS error (per-unit difference between actual and estimated inclination of the walking surface for each stride identified in the experiments of 0.05 and this can be reduced to 0.03 with subject-specific calibration and post processing procedures by means of averaging techniques.

  4. Retrofitting the suburbs to increase walking: evidence from a land-use-travel study.

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    Boarnet, Marlon G; Joh, Kenneth; Siembab, Walter; Fulton, William; Nguyen, Mai Thi

    2011-01-01

    This paper reports results from a detailed travel diary survey of 2125 residents in the South Bay area of Los Angeles County - a mature, auto-oriented suburban region. Study areas were divided into four centres, typical of compact development or smart growth, and four linear, auto-oriented corridors. Results show substantial variation in the amount of walking across study areas. Trips are shorter and more likely to be via walking in centres. A key to the centres' increased walking travel is the concentration of local shopping and service destinations in a commercial core. Yet the amount of business concentration that is associated with highly pedestrian-oriented neighbourhoods is from three to four times as large as what can be supported by the local resident base, suggesting that pedestrian-oriented neighbourhoods necessarily import shopping trips, and hence driving trips, from larger surrounding catchment areas. The results suggest both land use and mobility strategies that can be appropriate for suburban regions.

  5. How important is the land use mix measure in understanding walking behaviour? Results from the RESIDE study

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    Hooper Paula

    2011-06-01

    Full Text Available Abstract Background Understanding the relationship between urban design and physical activity is a high priority. Different representations of land use diversity may impact the association between neighbourhood design and specific walking behaviours. This study examined different entropy based computations of land use mix (LUM used in the development of walkability indices (WIs and their association with walking behaviour. Methods Participants in the RESIDential Environments project (RESIDE self-reported mins/week of recreational, transport and total walking using the Neighbourhood Physical Activity Questionnaire (n = 1798. Land use categories were incrementally added to test five different LUM models to identify the strongest associations with recreational, transport and total walking. Logistic regression was used to analyse associations between WIs and walking behaviour using three cut points: any (> 0 mins, ≥ 60 mins and ≥ 150 mins walking/week. Results Participants in high (vs. low walkable neighbourhoods reported up to almost twice the amount of walking, irrespective of the LUM measure used. However, different computations of LUM were found to be relevant for different types and amounts of walking (i.e., > 0, ≥ 60 or ≥ 150 mins/week. Transport walking (≥ 60 mins/week had the strongest and most significant association (OR = 2.24; 95% CI:1.58-3.18 with the WI when the LUM included 'residential', 'retail', 'office', 'health, welfare and community', and 'entertainment, culture and recreation'. However, any (> 0 mins/week recreational walking was more strongly associated with the WI (OR = 1.36; 95% CI:1.04-1.78 when land use categories included 'public open space', 'sporting infrastructure' and 'primary and rural' land uses. The observed associations were generally stronger for ≥ 60 mins/week compared with > 0 mins/week of transport walking and total walking but this relationship was not seen for recreational walking. Conclusions

  6. Determination of optimal placements of markers on the thigh during walking and landing

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    Pain M.T.G.

    2010-06-01

    Full Text Available Kinematics of skin markers are affected by skin tissue artefact with respect to the bone during sports activities or locomotion. The purpose of this study is to determine the less disturbed marker’s location for walking and landing. Twenty-six markers were put on the thigh of nine male subjects. Each subject performed a static trial, a setup movement for determining a functional hip joint centre and five walking and landing trials. The marker displacements were obtained by comparing recorded marker positions and solidified marker positions based on the geometry of the static acquisition. The markers were subsequently ranked from the worst to the least deformed. The ranking of each trial for each subject was analyzed with the concordance coefficient of Kendall and descriptive statistics were used to determine the most and the least disturbed markers. The results show reproducibility between trials for each subject for the two movements. Statistical analysis shows that the most deformed markers during walking were located close to the hip and knee joints whereas the least disturbed were on the mid-thigh. The landing analysis does not permit to determine the best markers from the worst.

  7. Determination of optimal placements of markers on the thigh during walking and landing

    Science.gov (United States)

    Thouzé, A.; Monnet, T.; Begon, M.; Pain, M. T. G.

    2010-06-01

    Kinematics of skin markers are affected by skin tissue artefact with respect to the bone during sports activities or locomotion. The purpose of this study is to determine the less disturbed marker’s location for walking and landing. Twenty-six markers were put on the thigh of nine male subjects. Each subject performed a static trial, a setup movement for determining a functional hip joint centre and five walking and landing trials. The marker displacements were obtained by comparing recorded marker positions and solidified marker positions based on the geometry of the static acquisition. The markers were subsequently ranked from the worst to the least deformed. The ranking of each trial for each subject was analyzed with the concordance coefficient of Kendall and descriptive statistics were used to determine the most and the least disturbed markers. The results show reproducibility between trials for each subject for the two movements. Statistical analysis shows that the most deformed markers during walking were located close to the hip and knee joints whereas the least disturbed were on the mid-thigh. The landing analysis does not permit to determine the best markers from the worst.

  8. Inertial Sensor-Based Methods in Walking Speed Estimation: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Qingguo Li

    2012-05-01

    Full Text Available Self-selected walking speed is an important measure of ambulation ability used in various clinical gait experiments. Inertial sensors, i.e., accelerometers and gyroscopes, have been gradually introduced to estimate walking speed. This research area has attracted a lot of attention for the past two decades, and the trend is continuing due to the improvement of performance and decrease in cost of the miniature inertial sensors. With the intention of understanding the state of the art of current development in this area, a systematic review on the exiting methods was done in the following electronic engines/databases: PubMed, ISI Web of Knowledge, SportDiscus and IEEE Xplore. Sixteen journal articles and papers in proceedings focusing on inertial sensor based walking speed estimation were fully reviewed. The existing methods were categorized by sensor specification, sensor attachment location, experimental design, and walking speed estimation algorithm.

  9. Inertial sensor-based methods in walking speed estimation: a systematic review.

    Science.gov (United States)

    Yang, Shuozhi; Li, Qingguo

    2012-01-01

    Self-selected walking speed is an important measure of ambulation ability used in various clinical gait experiments. Inertial sensors, i.e., accelerometers and gyroscopes, have been gradually introduced to estimate walking speed. This research area has attracted a lot of attention for the past two decades, and the trend is continuing due to the improvement of performance and decrease in cost of the miniature inertial sensors. With the intention of understanding the state of the art of current development in this area, a systematic review on the exiting methods was done in the following electronic engines/databases: PubMed, ISI Web of Knowledge, SportDiscus and IEEE Xplore. Sixteen journal articles and papers in proceedings focusing on inertial sensor based walking speed estimation were fully reviewed. The existing methods were categorized by sensor specification, sensor attachment location, experimental design, and walking speed estimation algorithm.

  10. Regression Model-Based Walking Speed Estimation Using Wrist-Worn Inertial Sensor

    Science.gov (United States)

    Park, Edward J.

    2016-01-01

    Walking speed is widely used to study human health status. Wearable inertial measurement units (IMU) are promising tools for the ambulatory measurement of walking speed. Among wearable inertial sensors, the ones worn on the wrist, such as a watch or band, have relatively higher potential to be easily incorporated into daily lifestyle. Using the arm swing motion in walking, this paper proposes a regression model-based method for longitudinal walking speed estimation using a wrist-worn IMU. A novel kinematic variable is proposed, which finds the wrist acceleration in the principal axis (i.e. the direction of the arm swing). This variable (called pca-acc) is obtained by applying sensor fusion on IMU data to find the orientation followed by the use of principal component analysis. An experimental evaluation was performed on 15 healthy young subjects during free walking trials. The experimental results show that the use of the proposed pca-acc variable can significantly improve the walking speed estimation accuracy when compared to the use of raw acceleration information (p<0.01). When Gaussian process regression is used, the resulting walking speed estimation accuracy and precision is about 5.9% and 4.7%, respectively. PMID:27764231

  11. Land use, transport, and population health: estimating the health benefits of compact cities.

    Science.gov (United States)

    Stevenson, Mark; Thompson, Jason; de Sá, Thiago Hérick; Ewing, Reid; Mohan, Dinesh; McClure, Rod; Roberts, Ian; Tiwari, Geetam; Giles-Corti, Billie; Sun, Xiaoduan; Wallace, Mark; Woodcock, James

    2016-12-10

    Using a health impact assessment framework, we estimated the population health effects arising from alternative land-use and transport policy initiatives in six cities. Land-use changes were modelled to reflect a compact city in which land-use density and diversity were increased and distances to public transport were reduced to produce low motorised mobility, namely a modal shift from private motor vehicles to walking, cycling, and public transport. The modelled compact city scenario resulted in health gains for all cities (for diabetes, cardiovascular disease, and respiratory disease) with overall health gains of 420-826 disability-adjusted life-years (DALYs) per 100 000 population. However, for moderate to highly motorised cities, such as Melbourne, London, and Boston, the compact city scenario predicted a small increase in road trauma for cyclists and pedestrians (health loss of between 34 and 41 DALYs per 100 000 population). The findings suggest that government policies need to actively pursue land-use elements-particularly a focus towards compact cities-that support a modal shift away from private motor vehicles towards walking, cycling, and low-emission public transport. At the same time, these policies need to ensure the provision of safe walking and cycling infrastructure. The findings highlight the opportunities for policy makers to positively influence the overall health of city populations.

  12. Sensitivity of land use change emission estimates to historical land use and land cover mapping

    Science.gov (United States)

    Peng, Shushi; Ciais, Philippe; Maignan, Fabienne; Li, Wei; Chang, Jinfeng; Wang, Tao; Yue, Chao

    2017-04-01

    The carbon emissions from land use and land cover change (ELUC) are an important anthropogenic component of the global carbon budget. Yet these emissions have a large uncertainty. Uncertainty in historical land use and land cover change (LULCC) maps and their implementation in global vegetation models is one of the key sources of the spread of ELUC calculated by global vegetation models. In this study, we used the Organizing Carbon and Hydrology in Dynamic Ecosystems terrestrial biosphere model to investigate how the different transition rules to define the priority of conversion from natural vegetation to agricultural land affect the historical reconstruction of plant functional types (PFTs) and ELUC. First, we reconstructed 10 sets of historical PFT maps using different transition rules and two methods. Then, we calculated ELUC from these 10 different historical PFT maps and an additional published PFT reconstruction, using the difference between two sets of simulations (with and without LULCC). The total area of forest loss is highly correlated with the total simulated ELUC (R2 = 0.83, P < 0.001) across the reconstructed PFT maps, which indicates that the choice of transition rules is a critical (and often overlooked) decision affecting the simulated ELUC. In addition to the choice of a transition rule, the initial land cover map and the reconstruction method for the reconstruction of historical PFT maps have an important impact on the resultant estimates of ELUC.

  13. Estimating land use / land cover changes in Denmark from 1990 - 2012

    DEFF Research Database (Denmark)

    Levin, Gregor; Kastrup Blemmer, Morten; Gyldenkærne, Steen

    According to the article 3(4) of the Kyoto Protocol, Denmark is obliged to document sequestration and emission of carbon dioxide from land use and land cover and changes in these. This report documents and describes applied data end developed methods aiming at estimating amounts and changes in land...... use and land cover for Denmark for since 1990. Estimation of land use and land cover categories and changes in these is predominantly based on existing categorical (i.e. pre-classified) geographical information. Estimations are elaborated for the period from 1990 to 2005, from 2005 to 2011 and from...... 2011 to 2012. Due to limited availability of historical spatially explicit information, estimations of change in land use and land cover from 1990 up to 2011 do, to some degree, involve decisions based on expert knowledge. Due to a significant increase in the availability of detailed spatially specific...

  14. Estimating land use / land cover changes in Denmark from 1990 - 2012

    DEFF Research Database (Denmark)

    Levin, Gregor; Kastrup Blemmer, Morten; Gyldenkærne, Steen

    According to the article 3(4) of the Kyoto Protocol, Denmark is obliged to document sequestration and emission of carbon dioxide from land use and land cover and changes in these. This report documents and describes applied data end developed methods aiming at estimating amounts and changes in land...... use and land cover for Denmark for since 1990. Estimation of land use and land cover categories and changes in these is predominantly based on existing categorical (i.e. pre-classified) geographical information. Estimations are elaborated for the period from 1990 to 2005, from 2005 to 2011 and from...... 2011 to 2012. Due to limited availability of historical spatially explicit information, estimations of change in land use and land cover from 1990 up to 2011 do, to some degree, involve decisions based on expert knowledge. Due to a significant increase in the availability of detailed spatially specific...

  15. A novel walking speed estimation scheme and its application to treadmill control for gait rehabilitation

    Directory of Open Access Journals (Sweden)

    Yoon Jungwon

    2012-08-01

    Full Text Available Abstract Background Virtual reality (VR technology along with treadmill training (TT can effectively provide goal-oriented practice and promote improved motor learning in patients with neurological disorders. Moreover, the VR + TT scheme may enhance cognitive engagement for more effective gait rehabilitation and greater transfer to over ground walking. For this purpose, we developed an individualized treadmill controller with a novel speed estimation scheme using swing foot velocity, which can enable user-driven treadmill walking (UDW to more closely simulate over ground walking (OGW during treadmill training. OGW involves a cyclic acceleration-deceleration profile of pelvic velocity that contrasts with typical treadmill-driven walking (TDW, which constrains a person to walk at a preset constant speed. In this study, we investigated the effects of the proposed speed adaptation controller by analyzing the gait kinematics of UDW and TDW, which were compared to those of OGW at three pre-determined velocities. Methods Ten healthy subjects were asked to walk in each mode (TDW, UDW, and OGW at three pre-determined speeds (0.5 m/s, 1.0 m/s, and 1.5 m/s with real time feedback provided through visual displays. Temporal-spatial gait data and 3D pelvic kinematics were analyzed and comparisons were made between UDW on a treadmill, TDW, and OGW. Results The observed step length, cadence, and walk ratio defined as the ratio of stride length to cadence were not significantly different between UDW and TDW. Additionally, the average magnitude of pelvic acceleration peak values along the anterior-posterior direction for each step and the associated standard deviations (variability were not significantly different between the two modalities. The differences between OGW and UDW and TDW were mainly in swing time and cadence, as have been reported previously. Also, step lengths between OGW and TDW were different for 0.5 m/s and 1.5 m/s gait velocities

  16. Southeast Region Headboat Survey-Landings Estimates

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A correction factor is calculated by month and vessel to adjust for misreporting as described above. These correction factors are applied to the reported landings by...

  17. Downgrading recent estimates of land available for biofuel production.

    Science.gov (United States)

    Fritz, Steffen; See, Linda; van der Velde, Marijn; Nalepa, Rachel A; Perger, Christoph; Schill, Christian; McCallum, Ian; Schepaschenko, Dmitry; Kraxner, Florian; Cai, Ximing; Zhang, Xiao; Ortner, Simone; Hazarika, Rubul; Cipriani, Anna; Di Bella, Carlos; Rabia, Ahmed H; Garcia, Alfredo; Vakolyuk, Mar'yana; Singha, Kuleswar; Beget, Maria E; Erasmi, Stefan; Albrecht, Franziska; Shaw, Brian; Obersteiner, Michael

    2013-02-05

    Recent estimates of additional land available for bioenergy production range from 320 to 1411 million ha. These estimates were generated from four scenarios regarding the types of land suitable for bioenergy production using coarse-resolution inputs of soil productivity, slope, climate, and land cover. In this paper, these maps of land availability were assessed using high-resolution satellite imagery. Samples from these maps were selected and crowdsourcing of Google Earth images was used to determine the type of land cover and the degree of human impact. Based on this sample, a set of rules was formulated to downward adjust the original estimates for each of the four scenarios that were previously used to generate the maps of land availability for bioenergy production. The adjusted land availability estimates range from 56 to 1035 million ha depending upon the scenario and the ruleset used when the sample is corrected for bias. Large forest areas not intended for biofuel production purposes were present in all scenarios. However, these numbers should not be considered as definitive estimates but should be used to highlight the uncertainty in attempting to quantify land availability for biofuel production when using coarse-resolution inputs with implications for further policy development.

  18. Position Estimation by Wearable Walking Navigation System for Visually Impaired with Sensor Fusion

    Science.gov (United States)

    Watanabe, Hiromi; Yamamoto, Yoshihiko; Tanzawa, Tsutomu; Kotani, Shinji

    A wearable walking navigation system without any special infrastructures has been developed to guide visually impaired. It is important to estimate a position correctly so that safe navigation can be realized. In our system, different sensor data are fused to estimate a pedestrian's position. An image processing system and a laser range finder were used to estimate the positions indoors. In this paper, we introduce the concept of “similarity” between map information and sensor data. This similarity is used to estimate the positions. Experimental results show that highly accurate position estimation can be achieved by sensor fusion. The positions in a linear passage were estimated using image processing data, and when the passage turns, the positions were estimated using LRF data.

  19. Models for estimation of land remote sensing satellites operational efficiency

    Science.gov (United States)

    Kurenkov, Vladimir I.; Kucherov, Alexander S.

    2017-01-01

    The paper deals with the problem of estimation of land remote sensing satellites operational efficiency. Appropriate mathematical models have been developed. Some results obtained with the help of the software worked out in Delphi programming support environment are presented.

  20. Estimating mean first passage time of biased random walks with short relaxation time on complex networks.

    Directory of Open Access Journals (Sweden)

    Zhuo Qi Lee

    Full Text Available Biased random walk has been studied extensively over the past decade especially in the transport and communication networks communities. The mean first passage time (MFPT of a biased random walk is an important performance indicator in those domains. While the fundamental matrix approach gives precise solution to MFPT, the computation is expensive and the solution lacks interpretability. Other approaches based on the Mean Field Theory relate MFPT to the node degree alone. However, nodes with the same degree may have very different local weight distribution, which may result in vastly different MFPT. We derive an approximate bound to the MFPT of biased random walk with short relaxation time on complex network where the biases are controlled by arbitrarily assigned node weights. We show that the MFPT of a node in this general case is closely related to not only its node degree, but also its local weight distribution. The MFPTs obtained from computer simulations also agree with the new theoretical analysis. Our result enables fast estimation of MFPT, which is useful especially to differentiate between nodes that have very different local node weight distribution even though they share the same node degrees.

  1. Estimation of quasi-stiffness of the human hip in the stance phase of walking.

    Directory of Open Access Journals (Sweden)

    Kamran Shamaei

    Full Text Available This work presents a framework for selection of subject-specific quasi-stiffness of hip orthoses and exoskeletons, and other devices that are intended to emulate the biological performance of this joint during walking. The hip joint exhibits linear moment-angular excursion behavior in both the extension and flexion stages of the resilient loading-unloading phase that consists of terminal stance and initial swing phases. Here, we establish statistical models that can closely estimate the slope of linear fits to the moment-angle graph of the hip in this phase, termed as the quasi-stiffness of the hip. Employing an inverse dynamics analysis, we identify a series of parameters that can capture the nearly linear hip quasi-stiffnesses in the resilient loading phase. We then employ regression analysis on experimental moment-angle data of 216 gait trials across 26 human adults walking over a wide range of gait speeds (0.75-2.63 m/s to obtain a set of general-form statistical models that estimate the hip quasi-stiffnesses using body weight and height, gait speed, and hip excursion. We show that the general-form models can closely estimate the hip quasi-stiffness in the extension (R(2 = 92% and flexion portions (R(2 = 89% of the resilient loading phase of the gait. We further simplify the general-form models and present a set of stature-based models that can estimate the hip quasi-stiffness for the preferred gait speed using only body weight and height with an average error of 27% for the extension stage and 37% for the flexion stage.

  2. Tropical Africa: Land use, biomass, and carbon estimates for 1980

    Energy Technology Data Exchange (ETDEWEB)

    Brown, S. [Environmental Protection Agency, Corvallis, OR (United States). Western Ecology Division; Gaston, G. [Environmental Protection Agency, Corvallis, OR (United States). National Research Council; Daniels, R.C. [ed.] [Oak Ridge National Lab., TN (United States)

    1996-06-01

    This document describes the contents of a digital database containing maximum potential aboveground biomass, land use, and estimated biomass and carbon data for 1980 and describes a methodology that may be used to extend this data set to 1990 and beyond based on population and land cover data. The biomass data and carbon estimates are for woody vegetation in Tropical Africa. These data were collected to reduce the uncertainty associated with the possible magnitude of historical releases of carbon from land use change. Tropical Africa is defined here as encompassing 22.7 x 10{sup 6} km{sup 2} of the earth`s land surface and includes those countries that for the most part are located in Tropical Africa. Countries bordering the Mediterranean Sea and in southern Africa (i.e., Egypt, Libya, Tunisia, Algeria, Morocco, South Africa, Lesotho, Swaziland, and Western Sahara) have maximum potential biomass and land cover information but do not have biomass or carbon estimate. The database was developed using the GRID module in the ARC/INFO{sup TM} geographic information system. Source data were obtained from the Food and Agriculture Organization (FAO), the U.S. National Geophysical Data Center, and a limited number of biomass-carbon density case studies. These data were used to derive the maximum potential and actual (ca. 1980) aboveground biomass-carbon values at regional and country levels. The land-use data provided were derived from a vegetation map originally produced for the FAO by the International Institute of Vegetation Mapping, Toulouse, France.

  3. Pilot Field Test: The Ability to Ambulate Following Landing as Assessed with Seat Egress, Walk and Obstacle Testing

    Science.gov (United States)

    Fisher, E. A.; Fomina, E. V; Reschke, M. F.; Cerisano, J. M.; Kofman, I. S.; Gadd, N. E.; Phillips, T. R.; Lee, S. M. C.; Laurie, S. S.; Stenger, M. B.; Bloomberg, J. J.; Mulavara, A. P.; Kozlovskaya, I. B.; Tomilovskaya, E. S.

    2016-01-01

    To date, changes in functional performance have been systematically studied after short-duration space flight. As important as the postflight functional changes have been, full functional recovery has never been investigated or established for long-duration flights. The Pilot Field Test (PFT) experiment, conducted with participation of ISS crewmembers traveling on Soyuz expeditions 34S - 41S, is comprised of several tasks designed to study the recovery of sensorimotor abilities of astronauts during the first 24 hours after landing and beyond. The objective of the Seat Egress - Walk and Obstacle Test, developed by NASA's Russian collaborators at the Institute for Biomedical Problems, is to address this gap in knowledge. This will allow us to characterize the ability of crewmembers to perform critical mission requirements that they will be expected to perform after an unassisted landing following 6 to 12 months in microgravity.

  4. Estimating a Random Walk First-Passage Time from Noisy or Delayed Observations

    CERN Document Server

    Burnashev, Marat V

    2012-01-01

    A random walk (or a Wiener process), possibly with drift, is observed in a noisy or delayed fashion. The problem considered in this paper is to estimate the first time \\tau the random walk reaches a given level. Specifically, the p-moment (p\\geq 1) optimization problem \\inf_\\eta \\ex|\\eta-\\tau|^p is investigated where the infimum is taken over the set of stopping times that are defined on the observation process. When there is no drift, optimal stopping rules are characterized for both types of observations. When there is a drift, upper and lower bounds on \\inf_\\eta \\ex|\\eta-\\tau|^p are established for both types of observations. The bounds are tight in the large-level regime for noisy observations and in the large-level-large-delay regime for delayed observations. Noteworthy, for noisy observations there exists an asymptotically optimal stopping rule that is a function of a single observation. Simulation results are provided that corroborate the validity of the results for non-asymptotic settings.

  5. Three distinct global estimates of historical land-cover change and land-use conversions for over 200 years

    Institute of Scientific and Technical Information of China (English)

    Prasanth MEIYAPPAN; Atul K.JAIN

    2012-01-01

    Earth's land cover has been extensively transformed over time due to both human activities and natural causes.Previous global studies have focused on developing spatial and temporal pattems of dominant human land-use activities (e.g.,cropland,pastureland,urban land,wood harvest).Process-based modeling studies adopt different strategies to estimate the changes in land cover by using these land-use data sets in combination with a potential vegetation map,and subsequently use this information for impact assessments.However,due to unaccounted changes in land cover (resulting from both indirect anthropogenic and natural causes),heterogeneity in land-use/cover (LUC) conversions among grid cells,even for the same land use activity,and uncertainty associated with potential vegetation mapping and historical estimates of human land use result in land cover estimates that are substantially different compared to results acquired from remote sensing observations.Here,we present a method to implicitly account for the differences arising from these uncertainties in order to provide historical estimates of land cover that are consistent with satellite estimates for recent years.Due to uncertainty in historical agricultural land use,we use three widely accepted global estimates of cropland and pastureland in combination with common wood harvest and urban land data sets to generate three distinct estimates of historical land-cover change and underlying LUC conversions.Hence,these distinct historical reconstructions offer a wide range of plausible regional estimates of uncertainty and the extent to which different ecosystems have undergone changes.The annual land cover maps and LUC conversion maps are reported at 0.5°×0.5° resolution and describe the area of 28 landcover types and respective underlying land-use transitions.The reconstructed data sets are relevant for studies addressing the impact of land-cover change on biogeophysics,biogeochemistry,water cycle,and global climate.

  6. A blended land emissivity product from the Inter-Comparison of different Land Surface Emissivity Estimates

    Science.gov (United States)

    Norouzi, H.; Temimi, M.; Khanbilvardi, R.

    2012-12-01

    Passive microwave observations are routinely used to estimate rain rate, cloud liquid water, and total precipitable water. In order to have accurate estimations from microwave, the contribution of the surface should be accounted for. Over land, due to the complex interaction between the microwave signal and the soil surface, retrieval of land surface emissivity and other surface and subsurface parameters is not straightforward. Several microwave emissivity products from various microwave sensors have been proposed. However, lack of ground truth measurements makes the validation of these products difficult. This study aims to inter-compare several available emissivity products over land and ultimately proposes a unique blended product that overcomes the flaws of each individual product. The selected products are based on observations from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E), the Special Sensor Microwave Imager (SSM/I), the Advanced Microwave Sounding unit (AMSU), and the Special Sensor Microwave Imager/Sounder (SSMIS). In retrieval of emissivities from these sensors different methods and ancillary data have been used. Some inherent discrepancies between the selected products can be introduced by as the difference in geometry in terms of incident angle, spectral response, and the foot print size which can affect the estimations. Moreover, ancillary data especially skin temperature and cloud mask cover can cause significant discrepancies between various estimations. The time series and correlation between emissivity maps are explored to assess the consistency of emissivity variations with geophysical variable such as snow, precipitation and drought. Preliminary results reveal that inconsistency between products varies based on land cover type due to penetration depth effect and ancillary data. Six years of estimations are employed in this research study, and a global blended emissivity estimations based on all product with minimal discrepancies

  7. An optimized Kalman filter for the estimate of trunk orientation from inertial sensors data during treadmill walking.

    Science.gov (United States)

    Mazzà, Claudia; Donati, Marco; McCamley, John; Picerno, Pietro; Cappozzo, Aurelio

    2012-01-01

    The aim of this study was the fine tuning of a Kalman filter with the intent to provide optimal estimates of lower trunk orientation in the frontal and sagittal planes during treadmill walking at different speeds using measured linear acceleration and angular velocity components represented in a local system of reference. Data were simultaneously collected using both an inertial measurement unit (IMU) and a stereophotogrammetric system from three healthy subjects walking on a treadmill at natural, slow and fast speeds. These data were used to estimate the parameters of the Kalman filter that minimized the difference between the trunk orientations provided by the filter and those obtained through stereophotogrammetry. The optimized parameters were then used to process the data collected from a further 15 healthy subjects of both genders and different anthropometry performing the same walking tasks with the aim of determining the robustness of the filter set up. The filter proved to be very robust. The root mean square values of the differences between the angles estimated through the IMU and through stereophotogrammetry were lower than 1.0° and the correlation coefficients between the corresponding curves were greater than 0.91. The proposed filter design can be used to reliably estimate trunk lateral and frontal bending during walking from inertial sensor data. Further studies are needed to determine the filter parameters that are most suitable for other motor tasks.

  8. Tail estimates for one-dimensional non-nearest-neighbor random walk in random environment

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Suppose that the integers are assigned i.i.d. random variables {(β gx , . . . , β 1x , α x )} (each taking values in the unit interval and the sum of them being 1), which serve as an environment. This environment defines a random walk {X n } (called RWRE) which, when at x, moves one step of length 1 to the right with probability α x and one step of length k to the left with probability β kx for 1≤ k≤ g. For certain environment distributions, we determine the almost-sure asymptotic speed of the RWRE and show that the chance of the RWRE deviating below this speed has a polynomial rate of decay. This is the generalization of the results by Dembo, Peres and Zeitouni in 1996. In the proof we use a large deviation result for the product of random matrices and some tail estimates and moment estimates for the total population size in a multi-type branching process with random environment.

  9. A New Estimate of the Earth's Land Surface Temperature History

    Science.gov (United States)

    Muller, R. A.; Curry, J. A.; Groom, D.; Jacobsen, B.; Perlmutter, S.; Rohde, R. A.; Rosenfeld, A.; Wickham, C.; Wurtele, J.

    2011-12-01

    The Berkeley Earth Surface Temperature team has re-evaluated the world's atmospheric land surface temperature record using a linear least-squares method that allow the use of all the digitized records back to 1800, including short records that had been excluded by prior groups. We use the Kriging method to estimate an optimal weighting of stations to give a world average based on uniform weighting of the land surface. We have assembled a record of the available data by merging 1.6 billion temperature reports from 16 pre-existing data archives; this data base will be made available for public use. The former Global Historic Climatology Network (GHCN) monthly data base shows a sudden drop in the number of stations reporting monthly records from 1980 to the present; we avoid this drop by calculating monthly averages from the daily records. By using all the data, we reduce the effects of potential data selection bias. We make an independent estimate of the urban heat island effect by calculating the world land temperature trends based on stations chosen to be far from urban sites. We calculate the effect of poor station quality, as documented in the US by the team led by Anthony Watts by estimating the temperature trends based solely on the stations ranked good (1,2 or 1,2,3 in the NOAA ranking scheme). We avoid issues of homogenization bias by using raw data; at times when the records are discontinuous (e.g. due to station moves) we break the record into smaller segments and analyze those, rather than attempt to correct the discontinuity. We estimate the uncertainties in the final results using the jackknife procedure developed by J. Tukey. We calculate spatial uncertainties by measuring the effects of geographical exclusion on recent data that have good world coverage. The results we obtain are compared to those published by the groups at NOAA, NASA-GISS, and Hadley-CRU in the UK.

  10. Multi-Scale Hydrometeorological Modeling, Land Data Assimilation and Parameter Estimation with the Land Information System

    Science.gov (United States)

    Peters-Lidard, Christa D.

    2011-01-01

    Center (EMC) for their land data assimilation systems to support weather and climate modeling. LIS not only consolidates the capabilities of these two systems, but also enables a much larger variety of configurations with respect to horizontal spatial resolution, input datasets and choice of land surface model through "plugins". LIS has been coupled to the Weather Research and Forecasting (WRF) model to support studies of land-atmosphere coupling be enabling ensembles of land surface states to be tested against multiple representations of the atmospheric boundary layer. LIS has also been demonstrated for parameter estimation, who showed that the use of sequential remotely sensed soil moisture products can be used to derive soil hydraulic and texture properties given a sufficient dynamic range in the soil moisture retrievals and accurate precipitation inputs.LIS has also recently been demonstrated for multi-model data assimilation using an Ensemble Kalman Filter for sequential assimilation of soil moisture, snow, and temperature.Ongoing work has demonstrated the value of bias correction as part of the filter, and also that of joint calibration and assimilation.Examples and case studies demonstrating the capabilities and impacts of LIS for hydrometeorological modeling, assimilation and parameter estimation will be presented as advancements towards the next generation of integrated observation and modeling systems

  11. Estimation of evapotranspiration rate in irrigated lands using stable isotopes

    Science.gov (United States)

    Umirzakov, Gulomjon; Windhorst, David; Forkutsa, Irina; Brauer, Lutz; Frede, Hans-Georg

    2013-04-01

    Agriculture in the Aral Sea basin is the main consumer of water resources and due to the current agricultural management practices inefficient water usage causes huge losses of freshwater resources. There is huge potential to save water resources in order to reach a more efficient water use in irrigated areas. Therefore, research is required to reveal the mechanisms of hydrological fluxes in irrigated areas. This paper focuses on estimation of evapotranspiration which is one of the crucial components in the water balance of irrigated lands. Our main objective is to estimate the rate of evapotranspiration on irrigated lands and partitioning of evaporation into transpiration using stable isotopes measurements. Experiments has done in 2 different soil types (sandy and sandy loam) irrigated areas in Ferghana Valley (Uzbekistan). Soil samples were collected during the vegetation period. The soil water from these samples was extracted via a cryogenic extraction method and analyzed for the isotopic ratio of the water isotopes (2H and 18O) based on a laser spectroscopy method (DLT 100, Los Gatos USA). Evapotranspiration rates were estimated with Isotope Mass Balance method. The results of evapotranspiration obtained using isotope mass balance method is compared with the results of Catchment Modeling Framework -1D model results which has done in the same area and the same time.

  12. Systematic Angle Random Walk Estimation of the Constant Rate Biased Ring Laser Gyro

    Directory of Open Access Journals (Sweden)

    Guohu Feng

    2013-02-01

    Full Text Available An actual account of the angle random walk (ARW coefficients of gyros in the constant rate biased rate ring laser gyro (RLG inertial navigation system (INS is very important in practical engineering applications. However, no reported experimental work has dealt with the issue of characterizing the ARW of the constant rate biased RLG in the INS. To avoid the need for high cost precise calibration tables and complex measuring set-ups, the objective of this study is to present a cost-effective experimental approach to characterize the ARW of the gyros in the constant rate biased RLG INS. In the system, turntable dynamics and other external noises would inevitably contaminate the measured RLG data, leading to the question of isolation of such disturbances. A practical observation model of the gyros in the constant rate biased RLG INS was discussed, and an experimental method based on the fast orthogonal search (FOS for the practical observation model to separate ARW error from the RLG measured data was proposed. Validity of the FOS-based method was checked by estimating the ARW coefficients of the mechanically dithered RLG under stationary and turntable rotation conditions. By utilizing the FOS-based method, the average ARW coefficient of the constant rate biased RLG in the postulate system is estimated. The experimental results show that the FOS-based method can achieve high denoising ability. This method estimate the ARW coefficients of the constant rate biased RLG in the postulate system accurately. The FOS-based method does not need precise calibration table with high cost and complex measuring set-up, and Statistical results of the tests will provide us references in engineering application of the constant rate biased RLG INS.

  13. [Estimation of energy expenditure and the validity of pitch counting during walking and jogging by piezoelectric materials].

    Science.gov (United States)

    Yoshida, T; Udo, M; Mizuno, C; Yamanaka, H; Tasaka, I

    1992-09-01

    The purpose of the present study was to assess the validity of Piezo-electric accelerometer for estimating energy expenditure in walking and jogging. Energy consumption by oxygen uptake was determined during steady state level of treadmill walking at the speed of 60, 80 and 100 m/min and jogging at the speed of 100, 120, 140, and 160 m/min for 10 subjects. There was a highly significant correlation between the energy consumption and the estimated energy expenditure by an accelerometer despite the attached position (r = 0.912 at the waist, r = 0.915 at the chest, P < 0.001), which suggests accurate estimating energy expenditure in the field.

  14. Integrated human-clothing system model for estimating the effect of walking on clothing insulation

    Energy Technology Data Exchange (ETDEWEB)

    Ghaddar, Nesreen [American University of Beirut, Faculty of Engineering and Architecture, P.O. Box 11-236, Riad ElSolh, 1107 2020, Beirut (Lebanon); Ghali, Kamel [Beirut Arab University, Faculty of Engineering, Beirut (Lebanon); Jones, Byron [Kansas State University, College of Engineering, 148 Rathbone Hall, 66506-5202, Manhattan, KS (United States)

    2003-06-01

    The objective of this work is to develop a 1-D transient heat and mass transfer model of a walking clothed human to predict the dynamic clothing dry heat insulation values and vapor resistances. Developing an integrated model of human and clothing system under periodic ventilation requires estimation of the heat and mass transfer film coefficients at the skin to the air layer subject to oscillating normal flow. Experiments were conducted in an environmental chamber under controlled conditions of 25 C and 50% relative humidity to measure the mass transfer coefficient at the skin to the air layer separating the wet skin and the fabric. A 1-D mathematical model is developed to simulate the dynamic thermal behavior of clothing and its interaction with the human thermoregulation system under walking conditions. A modification of Gagge's two-node model is used to simulate the human physiological regulatory responses. The human model is coupled to a clothing three-node model of the fabric that takes into consideration the adsorption of water vapor in the fibers during the periodic ventilation of the fabric by the air motion in from ambient environment and out from the air layer adjacent to the moist skin. When physical activity and ambient conditions are specified, the integrated model of human-clothing can predict the thermo-regulatory responses of the body together with the temperature and insulation values of the fabric. The developed model is used to predict the periodic ventilation flow rate in and out of the fabric, the periodic fabric regain, the fabric temperature, the air layer temperature, the heat loss or gain from the skin, and dry and vapor resistances of the clothing. The heat loss from the skin increases with the increase of the frequency of ventilation and with the increased metabolic rate of the body. In addition, the dry resistance of the clothing fabrics, predicted by the current model, IS compared with published experimental data. The current

  15. Pilot Field Test: The Ability to Ambulate After Landing as Assessed with Seat Egress, Walk, and Obstacle Test

    Science.gov (United States)

    Fisher, E. A.; Fomina, E. V.; Reschke, M. F.; Cerisano, J. M.; Kofman, I. S.; Gadd, N. E.; Phillips, T. R.; Lee, S. M. C.; Laurie, S. S.; Stenger, M. B.; Bloomberg, J. J.; Mulavara, A. P.; Kozlovskaya, I. B.; Tomilovskaya, E. S.

    2016-01-01

    Astronauts experience alterations in multiple physiological systems due to exposure to the microgravity conditions of space flight. These changes lead to disruption in the ability to ambulate and perform functional tasks during the initial reintroduction to a gravitational environment. Figure 1 shows a schematic representation of the components involved in postflight ataxia. Full functional recovery has not been sufficiently investigated for long-duration crewmembers. The joint U.S./Russian Pilot Field Test (PFT) experiment (a pre-cursor to Field Test (FT)) was developed to address this gap in knowledge. The PFT was conducted on crewmembers traveling on Soyuz expeditions 34S - 41S and was comprised of several tasks designed to study the recovery of sensorimotor abilities of crewmembers during the first 24 hours after landing and for several days thereafter. Closing this gap will allow us to characterize the ability of crewmembers to perform critical mission tasks that they will be expected to perform after an unassisted landing following 6 to 12 months in microgravity. The Seat Egress, Walk and Obstacle (SEWO) Test will be discussed in this poster.

  16. A TRMM Rainfall Estimation Method Applicable to Land Areas

    Science.gov (United States)

    Prabhakara, C.; Iacovazzi, R.; Weinman, J.; Dalu, G.

    1999-01-01

    Methods developed to estimate rain rate on a footprint scale over land with the satellite-borne multispectral dual-polarization Special Sensor Microwave Imager (SSM/1) radiometer have met with limited success. Variability of surface emissivity on land and beam filling are commonly cited as the weaknesses of these methods. On the contrary, we contend a more significant reason for this lack of success is that the information content of spectral and polarization measurements of the SSM/I is limited. because of significant redundancy. As a result, the complex nature and vertical distribution C, of frozen and melting ice particles of different densities, sizes, and shapes cannot resolved satisfactorily. Extinction in the microwave region due to these complex particles can mask the extinction due to rain drops. Because of these reasons, theoretical models that attempt to retrieve rain rate do not succeed on a footprint scale. To illustrate the weakness of these models, as an example we can consider the brightness temperature measurement made by the radiometer in the 85 GHz channel (T85). Models indicate that T85 should be inversely related to the rain rate, because of scattering. However, rain rate derived from 15-minute rain gauges on land indicate that this is not true in a majority of footprints. This is also supported by the ship-borne radar observations of rain in the Tropical Oceans and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA-COARE) region over the ocean. Based on these observations. we infer that theoretical models that attempt to retrieve rain rate do not succeed on a footprint scale. We do not follow the above path of rain retrieval on a footprint scale. Instead, we depend on the limited ability of the microwave radiometer to detect the presence of rain. This capability is useful to determine the rain area in a mesoscale region. We find in a given rain event that this rain area is closely related to the mesoscale-average rain rate

  17. Estimates for the Tail Probability of the Supremum of a Random Walk with Independent Increments

    Institute of Scientific and Technical Information of China (English)

    Yang YANG; Kaiyong WANG

    2011-01-01

    The authors investigate the tail probability of the supremum of a random walk with independent increments and obtain some equivalent assertions in the case that the increments are independent and identically distributed random variables with Osubexponential integrated distributions.A uniform upper bound is derived for the distribution of the supremum of a random walk with independent but non-identically distributed increments,whose tail distributions are dominated by a common tail distribution with an O-subexponential integrated distribution.

  18. The Use of Kernel Density Estimation to Examine Associations between Neighborhood Destination Intensity and Walking and Physical Activity.

    Directory of Open Access Journals (Sweden)

    Tania L King

    Full Text Available Local destinations have previously been shown to be associated with higher levels of both physical activity and walking, but little is known about how the distribution of destinations is related to activity. Kernel density estimation is a spatial analysis technique that accounts for the location of features relative to each other. Using kernel density estimation, this study sought to investigate whether individuals who live near destinations (shops and service facilities that are more intensely distributed rather than dispersed: 1 have higher odds of being sufficiently active; 2 engage in more frequent walking for transport and recreation.The sample consisted of 2349 residents of 50 urban areas in metropolitan Melbourne, Australia. Destinations within these areas were geocoded and kernel density estimates of destination intensity were created using kernels of 400m (meters, 800m and 1200m. Using multilevel logistic regression, the association between destination intensity (classified in quintiles Q1(least-Q5(most and likelihood of: 1 being sufficiently active (compared to insufficiently active; 2 walking≥4/week (at least 4 times per week, compared to walking less, was estimated in models that were adjusted for potential confounders.For all kernel distances, there was a significantly greater likelihood of walking≥4/week, among respondents living in areas of greatest destinations intensity compared to areas with least destination intensity: 400m (Q4 OR 1.41 95%CI 1.02-1.96; Q5 OR 1.49 95%CI 1.06-2.09, 800m (Q4 OR 1.55, 95%CI 1.09-2.21; Q5, OR 1.71, 95%CI 1.18-2.48 and 1200m (Q4, OR 1.7, 95%CI 1.18-2.45; Q5, OR 1.86 95%CI 1.28-2.71. There was also evidence of associations between destination intensity and sufficient physical activity, however these associations were markedly attenuated when walking was included in the models.This study, conducted within urban Melbourne, found that those who lived in areas of greater destination intensity walked

  19. Splitting Travel Time Based on AFC Data: Estimating Walking, Waiting, Transfer, and In-Vehicle Travel Times in Metro System

    Directory of Open Access Journals (Sweden)

    Yong-Sheng Zhang

    2015-01-01

    Full Text Available The walking, waiting, transfer, and delayed in-vehicle travel times mainly contribute to route’s travel time reliability in the metro system. The automatic fare collection (AFC system provides huge amounts of smart card records which can be used to estimate all these times distributions. A new estimation model based on Bayesian inference formulation is proposed in this paper by integrating the probability measurement of the OD pair with only one effective route, in which all kinds of times follow the truncated normal distributions. Then, Markov Chain Monte Carlo method is designed to estimate all parameters endogenously. Finally, based on AFC data in Guangzhou Metro, the estimations show that all parameters can be estimated endogenously and identifiably. Meanwhile, the truncated property of the travel time is significant and the threshold tested by the surveyed data is reliable. Furthermore, the superiority of the proposed model over the existing model in estimation and forecasting accuracy is also demonstrated.

  20. Step-Detection and Adaptive Step-Length Estimation for Pedestrian Dead-Reckoning at Various Walking Speeds Using a Smartphone.

    Science.gov (United States)

    Ho, Ngoc-Huynh; Truong, Phuc Huu; Jeong, Gu-Min

    2016-09-02

    We propose a walking distance estimation method based on an adaptive step-length estimator at various walking speeds using a smartphone. First, we apply a fast Fourier transform (FFT)-based smoother on the acceleration data collected by the smartphone to remove the interference signals. Then, we analyze these data using a set of step-detection rules in order to detect walking steps. Using an adaptive estimator, which is based on a model of average step speed, we accurately obtain the walking step length. To evaluate the accuracy of the proposed method, we examine the distance estimation for four different distances and three speed levels. The experimental results show that the proposed method significantly outperforms conventional estimation methods in terms of accuracy.

  1. Step-Detection and Adaptive Step-Length Estimation for Pedestrian Dead-Reckoning at Various Walking Speeds Using a Smartphone

    Directory of Open Access Journals (Sweden)

    Ngoc-Huynh Ho

    2016-09-01

    Full Text Available We propose a walking distance estimation method based on an adaptive step-length estimator at various walking speeds using a smartphone. First, we apply a fast Fourier transform (FFT-based smoother on the acceleration data collected by the smartphone to remove the interference signals. Then, we analyze these data using a set of step-detection rules in order to detect walking steps. Using an adaptive estimator, which is based on a model of average step speed, we accurately obtain the walking step length. To evaluate the accuracy of the proposed method, we examine the distance estimation for four different distances and three speed levels. The experimental results show that the proposed method significantly outperforms conventional estimation methods in terms of accuracy.

  2. The Walking Renaissance: A Longitudinal Analysis of Walking Travel in the Greater Los Angeles Area, USA

    Directory of Open Access Journals (Sweden)

    Kenneth Joh

    2015-07-01

    Full Text Available Promoting walking travel is considered important for reducing automobile use and improving public health. Recent U.S. transportation policy has incentivized investments in alternative, more sustainable transportation modes such as walking, bicycling and transit in auto-oriented cities such as Los Angeles. Although many past studies have analyzed changes in walking travel across the U.S., there is little clarity on the drivers of change. We address this gap by conducting a longitudinal analysis of walking travel in the greater Los Angeles area from 2001 to 2009. We use travel diary and household data from regional and national surveys to analyze changes in walking trip shares and rates across our study area. Results show that walking has significantly increased across most of Los Angeles, and that increases in walking trips generally correspond with increases in population, employment, and transit service densities. Estimates from fixed-effects regression analysis generally suggest a positive association between population density and walking, and that higher increases in transit stop density are correlated with increased walking trips to and from transit stops. These findings illustrate how regional planning efforts to pursue a coordinated land use-transit planning strategy can help promote walking in auto-oriented or vehicle adopting cities.

  3. [A new procedure for the estimation of physical fitness of patients during clinical rehabilitation using the 6-minutes walk test].

    Science.gov (United States)

    Marek, W; Marek, E; Friz, Y; Vogel, P; Mückenhoff, K; Kotschy-Lang, N

    2010-03-01

    /beat, respectively). The difference in efficiency, when repeating the tests at the beginning, was: 0.053 +/- 0.062 m/beat; at the end of the rehabilitation: 0.042 +/- 0.047 m/beat. They are found to be similar. The distances the patients walked in the repeated tests at the entrance and at the end of their clinical rehabilitation were, besides the calculated efficiency, E, significantly increased. However, the increases in distance and efficiency are identical on both occasions, therefore the repetition delivers no further information. The test should be performed without repetitions in clinical routine investigations. The patient's performance in the second walk test with an unchanged distance at a lower heart rate reveals an improved physical fitness. This is solely described by an increase of efficiency, E. Therefore the introduction of E is a suitable measure of the quantified effect of exercise training, even if the patient is not cooperative during the tests. E is proved to be a suitable estimation for the assessment of physical fitness as a benefit of clinical rehabilitation. Georg Thieme Verlag KG Stuttgart, New York.

  4. Estimation of quasi-stiffness of the human knee in the stance phase of walking.

    Directory of Open Access Journals (Sweden)

    Kamran Shamaei

    Full Text Available Biomechanical data characterizing the quasi-stiffness of lower-limb joints during human locomotion is limited. Understanding joint stiffness is critical for evaluating gait function and designing devices such as prostheses and orthoses intended to emulate biological properties of human legs. The knee joint moment-angle relationship is approximately linear in the flexion and extension stages of stance, exhibiting nearly constant stiffnesses, known as the quasi-stiffnesses of each stage. Using a generalized inverse dynamics analysis approach, we identify the key independent variables needed to predict knee quasi-stiffness during walking, including gait speed, knee excursion, and subject height and weight. Then, based on the identified key variables, we used experimental walking data for 136 conditions (speeds of 0.75-2.63 m/s across 14 subjects to obtain best fit linear regressions for a set of general models, which were further simplified for the optimal gait speed. We found R(2 > 86% for the most general models of knee quasi-stiffnesses for the flexion and extension stages of stance. With only subject height and weight, we could predict knee quasi-stiffness for preferred walking speed with average error of 9% with only one outlier. These results provide a useful framework and foundation for selecting subject-specific stiffness for prosthetic and exoskeletal devices designed to emulate biological knee function during walking.

  5. Optic-flow based slope estimation for autonomous landing

    NARCIS (Netherlands)

    De Croon, G.C.H.E.; Ho, H.W.; De Wagter, C.; Van Kampen, E.; Remes, B.; Chu, Q.P.

    2013-01-01

    Micro Air Vehicles need to have a robust landing capability, especially when they operate outside line-of-sight. Autonomous landing requires the identification of a relatively flat landing surface that does not have too large an inclination. In this article, a vision algorithm is introduced that fit

  6. Walk on the wild side: estimating the global magnitude of visits to protected areas.

    Science.gov (United States)

    Balmford, Andrew; Green, Jonathan M H; Anderson, Michael; Beresford, James; Huang, Charles; Naidoo, Robin; Walpole, Matt; Manica, Andrea

    2015-02-01

    How often do people visit the world's protected areas (PAs)? Despite PAs covering one-eighth of the land and being a major focus of nature-based recreation and tourism, we don't know. To address this, we compiled a globally-representative database of visits to PAs and built region-specific models predicting visit rates from PA size, local population size, remoteness, natural attractiveness, and national income. Applying these models to all but the very smallest of the world's terrestrial PAs suggests that together they receive roughly 8 billion (8 x 109) visits/y-of which more than 80% are in Europe and North America. Linking our region-specific visit estimates to valuation studies indicates that these visits generate approximately US $600 billion/y in direct in-country expenditure and US $250 billion/y in consumer surplus. These figures dwarf current, typically inadequate spending on conserving PAs. Thus, even without considering the many other ecosystem services that PAs provide to people, our findings underscore calls for greatly increased investment in their conservation.

  7. On the sensitivity of Land Surface Temperature estimates in arid irrigated lands using MODTRAN

    KAUST Repository

    Rosas, Jorge

    2015-11-29

    Land surface temperature (LST) derived from thermal infrared (TIR) satellite data has been reliably used as a remote indicator of evapotranspiration (ET) and surface moisture status. However, in order to retrieve the ET with an accuracy approaching 10%, LST should be retrieved to within 1 ◦C or better, disregarding other elements of uncertainty. The removal of atmospheric effects is key towards achieving a precise estimation of LST and it requires detailed information on water vapor. The Thermal Infrared Sensor (TIRS) onboard Landsat 8 captures data in two long wave thermal bands with 100-meter resolution. However, the US Geological Survey has reported a calibration problem of TIRS bands caused by stray light, resulting in a higher bias in one of its two bands (4% in band 11, 2% in band 10). Therefore, split-window algorithms for the estimation of LST might not be reliable. Our work will focus on the impact of using different atmospheric profiles (e.g. weather prediction models, satellite) for the estimation of LST derived from MODTRAN by using one of the TIRS bands onboard Landsat 8 (band 10). Sites with in-situ measurements of LST are used as evaluation sources. Comparisons between the measured LST and LST derived based on different atmospheric profile inputs to MODTRAN are carried out from 2 Landsat-overpass days (DOY 153 and 160 2015). Preliminary results show a mean absolute error of around 3 ◦C between in-situ and estimated LST over two different crops (alfalfa and carrot) and bare soil.

  8. Modelling Pasture-based Automatic Milking System Herds: System Fitness of Grazeable Home-grown Forages, Land Areas and Walking Distances

    Directory of Open Access Journals (Sweden)

    M. R. Islam

    2015-06-01

    Full Text Available To maintain a predominantly pasture-based system, the large herd milked by automatic milking rotary would be required to walk significant distances. Walking distances of greater than 1-km are associated with an increased incidence of undesirably long milking intervals and reduced milk yield. Complementary forages can be incorporated into pasture-based systems to lift total home grown feed in a given area, thus potentially ‘concentrating’ feed closer to the dairy. The aim of this modelling study was to investigate the total land area required and associated walking distance for large automatic milking system (AMS herds when incorporating complementary forage rotations (CFR into the system. Thirty-six scenarios consisting of 3 AMS herds (400, 600, 800 cows, 2 levels of pasture utilisation (current AMS utilisation of 15.0 t dry matter [DM]/ha, termed as moderate; optimum pasture utilisation of 19.7 t DM/ha, termed as high and 6 rates of replacement of each of these pastures by grazeable CFR (0%, 10%, 20%, 30%, 40%, 50% were investigated. Results showed that AMS cows were required to walk greater than 1-km when the farm area was greater than 86 ha. Insufficient pasture could be produced within a 1 km distance (i.e. 86 ha land with home-grown feed (HGF providing 43%, 29%, and 22% of the metabolisable energy (ME required by 400, 600, and 800 cows, respectively from pastures. Introduction of pasture (moderate: CFR in AMS at a ratio of 80:20 can feed a 400 cow AMS herd, and can supply 42% and 31% of the ME requirements for 600 and 800 cows, respectively with pasture (moderate: CFR at 50:50 levels. In contrast to moderate pasture, 400 cows can be managed on high pasture utilisation (provided 57% of the total ME requirements. However, similar to the scenarios conducted with moderate pasture, there was insufficient feed produced within 1-km distance of the dairy for 600 or 800 cows. An 800 cow herd required 140 and 130 ha on moderate and high pasture

  9. Historical land-use induced evapotranspiration changes estimated from present-day observations and reconstructed land-cover maps

    Directory of Open Access Journals (Sweden)

    J. P. Boisier

    2014-02-01

    Full Text Available Recent model intercomparison studies, within the framework of the LUCID project, have revealed large discrepancies in the evapotranspiration (ET changes simulated between the preindustrial period and the present in response to the historical change in land use. Distinct land-surface parameterizations are behind those discrepancies, but understanding those differences and attributing them to specific causes rely on evaluations using still very limited measurements. Model benchmarking studies with observed global-scale ET are required in order to reduce the current uncertainties in the impacts of land use in terrestrial water flows. Here we present a new estimate of historical land-use induced changes in ET based on three different state-of-the-art observation-based ET products. These products are used to derive regression models of ET as a function of land-cover partitioning, leaf area index and environmental variables. We then reconstruct past ET changes based on the set of land-cover maps of 1870 and 1992 used in LUCID. Our results show an average decrease in global terrestrial ET of 1260 ± 850 km3 yr−1 between the preindustrial period and the present-day. This estimate is of the same order but larger in magnitude than the model-mean change in ET simulated within LUCID, and substantially weaker in magnitude than other estimates based on observations. Although decreases in ET dominate in deforested regions, large summertime increases in ET are diagnosed over areas of large cropland expansion. The multiple ET reconstructions carried out here show a large spread that we attribute principally to the different land-cover maps adopted and to the crops' ET rates that are derived from the various products assessed. We therefore conclude that the current uncertainties of past ET changes could be reduced efficiently with improved historical land-cover reconstructions and better estimates of cropland ET.

  10. An Estimation of Land Surface Temperatures from Landsat ETM+ ...

    African Journals Online (AJOL)

    Dr-Adeline

    2 National Authority for Remote Sensing and Space Sciences, Cairo, Egypt. 3University of ... Keywords: Urban growth, urban heat Island, land surface temperatures, satellite remote sensing .... observed target includes green vegetation or not.

  11. Roles of eyes, leg proprioceptors and statocysts in the compensatory eye movements of freely walking land crabs (Cardisoma guanhumi)

    Science.gov (United States)

    Paul; Barnes; Varju

    1998-12-01

    The compound eyes, the canal organs of the statocysts and proprioceptors in the legs all generate compensatory eye movements in the horizontal plane in the land crab Cardisoma guanhumi. Frequency analyses of the compensatory eye reflexes elicited by each of these inputs show that visual (V) and proprioceptive (P) reflexes respond best below 0.1 Hz, while statocyst (S) reflexes only achieve a high gain above this frequency. They thus increase the range of frequencies over which compensation can occur. Eye and body movements were recorded in an arena under all possible combinations of crabs seeing or blind (V+ or V-), with or without statocysts (S+ or S-) and freely walking or passively transported on a trolley (P+ or P-). Intact crabs (V+S+P+) show good stabilisation of the eyes in space, the only movements with respect to external coordinates being saccadic resetting movements (fast phases of nystagmus). The eyes thus compensate well for body turns, but are unaffected by translatory movements of the body and turns that are not accompanied by a change in the orientation of the long axis of the body in space. In the absence of any one sense, compensation for rotation is significantly impaired, whether measured by the increase in the width of the histograms of changes in the angular positions of the eyes in space ( capdelta &phgr; E), by the mean angular velocity of the eyes (slope of regression line, mE) with respect to the angular velocity of the body (mB) or by response gain plotted against angular acceleration of body turn (a). The absence of two senses reduces the crab's ability to compensate still further, with the statocyst-only condition (V-S+P-) being little better than the condition when all three senses are absent (V-S-P-).Such multisensory control of eye compensation for body rotation is discussed both in terms of making use of every available cue for reducing retinal slip and in making available the information content of the optic flow field.

  12. Most likely paths to error when estimating the mean of a reflected random walk

    CERN Document Server

    Duffy, Ken R

    2009-01-01

    It is known that simulation of the mean position of a reflected random walk $\\{W_n\\}$ exhibits non-standard behavior, even for light-tailed increment distributions with negative drift. The Large Deviation Principle (LDP) holds for deviations below the mean, but for deviations at the usual speed above the mean the rate function is null. This paper takes a deeper look at this phenomenon. Conditional on a large sample mean, a complete sample path LDP analysis is obtained. Let $I$ denote the rate function for the one dimensional increment process. If $I$ is coercive, then given a large simulated mean position, under general conditions our results imply that the most likely asymptotic behavior, $\\psi$, of the paths $n^{-1} W_{\\lfloor tn\\rfloor}$ is to be zero apart from on an interval $[T_0,T_1]\\subset[0,1]$ and to satisfy the functional equation \

  13. Three-dimensional hip and knee kinematics during walking, running, and single-limb drop landing in females with and without genu valgum.

    Science.gov (United States)

    Barrios, Joaquin A; Heitkamp, Cera A; Smith, Barbara P; Sturgeon, Morgan M; Suckow, Daniel W; Sutton, Chelsea R

    2016-01-01

    Dynamic knee valgus in females has been associated with various knee pathologies. Abnormal 3D hip and knee kinematics contribute prominently to this presentation, and these may become more aberrant with more demanding tasks. Underlying genu valgus may also accentuate such kinematics, but this effect has never been tested. Therefore, the purpose of this study was to compare 3D hip and knee kinematics during walking, running, and single-limb drop landing in females with and without genu valgus malalignment. We expected abnormal kinematics to become more evident in the valgus subjects as task demands increased. Eighteen healthy females with genu valgum and 18 female controls with normal alignment underwent 3D motion analysis while performing walking, running, and single-limb drop-landing trials. Sagittal, frontal, and transverse plane hip and knee kinematics were compared between groups across tasks using analyses of variance and between-group effect sizes. Group differences did not generally increase with higher forces. The valgus females demonstrated decreased hip flexion (ES=0.72-0.88) and increased knee abduction (ES=0.87-1.47) across the tasks. During running and single-limb drop landing, they showed increased knee external rotation (ES=0.69-0.73). Finally, during walking, the valgus females showed increased hip adduction (ES=0.69). These results suggest that females with genu valgus alignment utilize aberrant hip and knee mechanics previously associated with dynamic valgus in the literature, but that these pathomechanics do not generally worsen with rising task demands. Healthy females that present with genu valgus may be natively at elevated risk for knee pathology. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. estimation of land surface temperature of kaduna metropolis, nigeria

    African Journals Online (AJOL)

    Zaharaddeen et. al

    Understanding the spatial variation of Land Surface Temperature. (LST), will be ... positive correlation between mean of surface emissivity with date and ... deviation of 1.92 of LST and coefficient determinant R2 (0.46) show a ... (LST), as the prime and basic physical parameter of the earth's ..... thorough review of the paper.

  15. Joint forces and torques when walking in shallow water.

    Science.gov (United States)

    Orselli, Maria Isabel Veras; Duarte, Marcos

    2011-04-01

    This study reports for the first time an estimation of the internal net joint forces and torques on adults' lower limbs and pelvis when walking in shallow water, taking into account the drag forces generated by the movement of their bodies in the water and the equivalent data when they walk on land. A force plate and a video camera were used to perform a two-dimensional gait analysis at the sagittal plane of 10 healthy young adults walking at comfortable speeds on land and in water at a chest-high level. We estimated the drag force on each body segment and the joint forces and torques at the ankle, knee, and hip of the right side of their bodies using inverse dynamics. The observed subjects' apparent weight in water was about 35% of their weight on land and they were about 2.7 times slower when walking in water. When the subjects walked in water compared with walking on land, there were no differences in the angular displacements but there was a significant reduction in the joint torques which was related to the water's depth. The greatest reduction was observed for the ankle and then the knee and no reduction was observed for the hip. All joint powers were significantly reduced in water. The compressive and shear joint forces were on average about three times lower during walking in water than on land. These quantitative results substantiate the use of water as a safe environment for practicing low-impact exercises, particularly walking.

  16. Estimation of late twentieth century land-cover change in California

    Science.gov (United States)

    Sleeter, Benjamin M.; Wilson, Tamara S.; Soulard, Christopher E.; Liu, Jinxun

    2011-01-01

    We present the first comprehensive multi-temporal analysis of land-cover change for California across its major ecological regions and primary land-cover types. Recently completed satellite-based estimates of land-cover and land-use change information for large portions of the United States allow for consistent measurement and comparison across heterogeneous landscapes. Landsat data were employed within a pure-panel stratified one-stage cluster sample to estimate and characterize land-cover change for 1973-2000. Results indicate anthropogenic and natural disturbances, such as forest cutting and fire, were the dominant changes, followed by large fluctuations between agriculture and rangelands. Contrary to common perception, agriculture remained relatively stable over the 27-year period with an estimated loss of 1.0% of agricultural land. The largest net declines occurred in the grasslands/shrubs class at 5,131 km2 and forest class at 4,722 km2. Developed lands increased by 37.6%, composing an estimated 4.2% of the state?s land cover by 2000.

  17. Estimation of Individual Muscular Forces of the Lower Limb during Walking Using a Wearable Sensor System

    National Research Council Canada - National Science Library

    Suin Kim; Kyongkwan Ro; Joonbum Bae

    2017-01-01

      Although various kinds of methodologies have been suggested to estimate individual muscular forces, many of them require a costly measurement system accompanied by complex preprocessing and postprocessing procedures...

  18. An Inertial Dual-State State Estimator for Precision Planetary Landing with Hazard Detection and Avoidance

    Science.gov (United States)

    Bishop, Robert H.; DeMars, Kyle; Trawny, Nikolas; Crain, Tim; Hanak, Chad; Carson, John M.; Christian, John

    2016-01-01

    The navigation filter architecture successfully deployed on the Morpheus flight vehicle is presented. The filter was developed as a key element of the NASA Autonomous Landing and Hazard Avoidance Technology (ALHAT) project and over the course of 15 free fights was integrated into the Morpheus vehicle, operations, and flight control loop. Flight testing completed by demonstrating autonomous hazard detection and avoidance, integration of an altimeter, surface relative velocity (velocimeter) and hazard relative navigation (HRN) measurements into the onboard dual-state inertial estimator Kalman flter software, and landing within 2 meters of the vertical testbed GPS-based navigation solution at the safe landing site target. Morpheus followed a trajectory that included an ascent phase followed by a partial descent-to-landing, although the proposed filter architecture is applicable to more general planetary precision entry, descent, and landings. The main new contribution is the incorporation of a sophisticated hazard relative navigation sensor-originally intended to locate safe landing sites-into the navigation system and employed as a navigation sensor. The formulation of a dual-state inertial extended Kalman filter was designed to address the precision planetary landing problem when viewed as a rendezvous problem with an intended landing site. For the required precision navigation system that is capable of navigating along a descent-to-landing trajectory to a precise landing, the impact of attitude errors on the translational state estimation are included in a fully integrated navigation structure in which translation state estimation is combined with attitude state estimation. The map tie errors are estimated as part of the process, thereby creating a dual-state filter implementation. Also, the filter is implemented using inertial states rather than states relative to the target. External measurements include altimeter, velocimeter, star camera, terrain relative

  19. Sensor data fusion for body state estimation in a bipedal robot and its feedback control application for stable walking.

    Science.gov (United States)

    Chen, Ching-Pei; Chen, Jing-Yi; Huang, Chun-Kai; Lu, Jau-Ching; Lin, Pei-Chun

    2015-02-27

    We report on a sensor data fusion algorithm via an extended Kalman filter for estimating the spatial motion of a bipedal robot. Through fusing the sensory information from joint encoders, a 6-axis inertial measurement unit and a 2-axis inclinometer, the robot's body state at a specific fixed position can be yielded. This position is also equal to the CoM when the robot is in the standing posture suggested by the detailed CAD model of the robot. In addition, this body state is further utilized to provide sensory information for feedback control on a bipedal robot with walking gait. The overall control strategy includes the proposed body state estimator as well as the damping controller, which regulates the body position state of the robot in real-time based on instant and historical position tracking errors. Moreover, a posture corrector for reducing unwanted torque during motion is addressed. The body state estimator and the feedback control structure are implemented in a child-size bipedal robot and the performance is experimentally evaluated.

  20. Sensor Data Fusion for Body State Estimation in a Bipedal Robot and Its Feedback Control Application for Stable Walking

    Directory of Open Access Journals (Sweden)

    Ching-Pei Chen

    2015-02-01

    Full Text Available We report on a sensor data fusion algorithm via an extended Kalman filter for estimating the spatial motion of a bipedal robot. Through fusing the sensory information from joint encoders, a 6-axis inertial measurement unit and a 2-axis inclinometer, the robot’s body state at a specific fixed position can be yielded. This position is also equal to the CoM when the robot is in the standing posture suggested by the detailed CAD model of the robot. In addition, this body state is further utilized to provide sensory information for feedback control on a bipedal robot with walking gait. The overall control strategy includes the proposed body state estimator as well as the damping controller, which regulates the body position state of the robot in real-time based on instant and historical position tracking errors. Moreover, a posture corrector for reducing unwanted torque during motion is addressed. The body state estimator and the feedback control structure are implemented in a child-size bipedal robot and the performance is experimentally evaluated.

  1. Estimate of the lower-limb-specific muscle parameters during bipedal walking for humans, apes and early hominids with the implications for the evolution of body proportion

    Institute of Scientific and Technical Information of China (English)

    Wang Weijie

    2007-01-01

    Modern human has different body proportion from early hominids and great apes. Comparing with others, in general, modern human adults have relatively long lower limb and heavier body weight. Since the lower limbs provide support to the whole body and play an important role in walking, it is proposed that the ratio of the lower limb to the whole body for modern human could be beneficial to bipedal walking. This study tried to estimate the muscle parameters of the lower limb in walking for the subjects with various body proportions. Using a simplified musculoskeletal model, some muscle parameters of the lower limb, e.g. muscle force, stress, work and power, were estimated for modern human adult, child, AL 288-1 (the fossil specimens of Australopithecus afarensis, 3.18 million years old) and apes. The results show that with the body proportion modern human adult spends less muscle work and power in walking than other subjects. The results imply that using the cost of transport (i.e. the muscle work of the lower limb per unit of displacement) as the criteria, the early hominids, if their body proportions were structurally similar to AL 288-1, could evolve towards what modern human adult looks like, in order to save energy during bipedal walking.

  2. [A new procedure for the estimation of physical fitness of patients during clinical rehabilitation using the 6-minute-walk-test].

    Science.gov (United States)

    Marek, W; Marek, E; Vogel, P; Mückenhoff, K; Kotschy-Lang, N

    2008-11-01

    lower heart rates in the final test, using the numerical procedure described above. The patient's performance of the second walk test with an unchanged distance at a lower heart rate reveals an improved physical fitness. This is solely described by an increase by the parameter of efficiency, E. The calculation of the parameter, Sz, theoretical difference in walking distance (i. e., theoretical increase in almost all tests) provides a quantification of the effect of exercise training, even if the patient is not cooperative during the tests. Both parameters have proved to be suitable estimations for the assessment of physical fitness as a beneficial effect of clinical rehabilitation.

  3. Estimating adhesive seed-dispersal distances : field experiments and correlated random walks

    NARCIS (Netherlands)

    Mouissie, AM; Lengkeek, W; van Diggelen, R

    1. In this study we aimed to estimate distance distributions of adhesively dispersed seeds and the factors that determine them. 2. Seed attachment and detachment were studied using field experiments with a real sheep, a sheep dummy and a cattle dummy. Seed-retention data were used in correlated

  4. SECPOP90: Sector population, land fraction, and economic estimation program

    Energy Technology Data Exchange (ETDEWEB)

    Humphreys, S.L.; Rollstin, J.A.; Ridgely, J.N.

    1997-09-01

    In 1973 Mr. W. Athey of the Environmental Protection Agency wrote a computer program called SECPOP which calculated population estimates. Since that time, two things have changed which suggested the need for updating the original program - more recent population censuses and the widespread use of personal computers (PCs). The revised computer program uses the 1990 and 1992 Population Census information and runs on current PCs as {open_quotes}SECPOP90.{close_quotes} SECPOP90 consists of two parts: site and regional. The site provides population and economic data estimates for any location within the continental United States. Siting analysis is relatively fast running. The regional portion assesses site availability for different siting policy decisions; i.e., the impact of available sites given specific population density criteria within the continental United States. Regional analysis is slow. This report compares the SECPOP90 population estimates and the nuclear power reactor licensee-provided information. Although the source, and therefore the accuracy, of the licensee information is unknown, this comparison suggests SECPOP90 makes reasonable estimates. Given the total uncertainty in any current calculation of severe accidents, including the potential offsite consequences, the uncertainty within SECPOP90 population estimates is expected to be insignificant. 12 refs., 55 figs., 7 tabs.

  5. Bootstrap-estimated land-to-water coefficients from the CBTN_v4 SPARROW model

    Science.gov (United States)

    Ator, Scott; Brakebill, John W.; Blomquist, Joel D.

    2017-01-01

    This file contains 200 sets of bootstrap-estimated land-to-water coefficients from the CBTN_v4 SPARROW model, which is documented in USGS Scientific Investigations Report 2011-5167. The coefficients were produced as part of CBTN_v4 model calibration to provide information about the uncertainty in model estimates.

  6. Regional Cost Estimates for Reclamation Practices on Arid and Semiarid Lands

    Energy Technology Data Exchange (ETDEWEB)

    W. K. Ostler

    2002-02-01

    The U.S. Army uses the Integrated Training Area Management program for managing training land. One of the major objectives of the Integrated Training Area Management program has been to develop a method for estimating training land carrying capacity in a sustainable manner. The Army Training and Testing Area Carrying Capacity methodology measures training load in terms of Maneuver Impact Miles. One Maneuver Impact Mile is the equivalent impact of an M1A2 tank traveling one mile while participating in an armor battalion field training exercise. The Army Training and Testing Area Carrying Capacity methodology is also designed to predict land maintenance costs in terms of dollars per Maneuver Impact Mile. The overall cost factor is calculated using the historical cost of land maintenance practices and the effectiveness of controlling erosion. Because land maintenance costs and effectiveness are influenced by the characteristics of the land, Army Training and Testing Area Carrying Capacity cost factors must be developed for each ecological region of the country. Costs for land maintenance activities are presented here for the semiarid and arid regions of the United States. Five ecoregions are recognized, and average values for reclamation activities are presented. Because there are many variables that can influence costs, ranges for reclamation activities are also presented. Costs are broken down into six major categories: seedbed preparation, fertilization, seeding, planting, mulching, and supplemental erosion control. Costs for most land reclamation practices and materials varied widely within and between ecological provinces. Although regional cost patterns were evident for some practices, the patterns were not consistent between practices. For the purpose of estimating land reclamation costs for the Army Training and Testing Area Carrying Capacity methodology, it may be desirable to use the ''Combined Average'' of all provinces found in the last

  7. Results from Assimilating AMSR-E Soil Moisture Estimates into a Land Surface Model Using an Ensemble Kalman Filter in the Land Information System

    Science.gov (United States)

    Blankenship, Clay B.; Crosson, William L.; Case, Jonathan L.; Hale, Robert

    2010-01-01

    Improve simulations of soil moisture/temperature, and consequently boundary layer states and processes, by assimilating AMSR-E soil moisture estimates into a coupled land surface-mesoscale model Provide a new land surface model as an option in the Land Information System (LIS)

  8. Estimation of agricultural pesticide use in drainage basins using land cover maps and county pesticide data

    Science.gov (United States)

    Nakagaki, Naomi; Wolock, David M.

    2005-01-01

    A geographic information system (GIS) was used to estimate agricultural pesticide use in the drainage basins of streams that are studied as part of the U.S. Geological Survey?s National Water-Quality Assessment (NAWQA) Program. Drainage basin pesticide use estimates were computed by intersecting digital maps of drainage basin boundaries with an enhanced version of the National Land Cover Data 1992 combined with estimates of 1992 agricultural pesticide use in each United States county. This report presents the methods used to quantify agricultural pesticide use in drainage basins using a GIS and includes the estimates of atrazine use applied to row crops, small-grain crops, and fallow lands in 150 watersheds in the conterminous United States. Basin atrazine use estimates are presented to compare and analyze the results that were derived from 30-meter and 1-kilometer resolution land cover and county pesticide use data, and drainage basin boundaries at various grid cell resolutions. Comparisons of the basin atrazine use estimates derived from watershed boundaries, county pesticide use, and land cover data sets at different resolutions, indicated that overall differences were minor. The largest potential for differences in basin pesticide use estimates between those derived from the 30-meter and 1-kilometer resolution enhanced National Land Cover Data 1992 exists wherever there are abrupt agricultural land cover changes along the basin divide. Despite the limitations of the drainage basin pesticide use data described in this report, the basin estimates provide consistent and comparable indicators of agricultural pesticide application in surface-water drainage basins studied in the NAWQA Program.

  9. RESOLUTION AND ERROR IN MEASURING LAND-COVER CHANGE: EFFECTS ON ESTIMATING NET CARBON RELEASE FROM MEXICAN TERRESTRIAL ECOSYSTEMS

    Science.gov (United States)

    Reliable estimates of carbon exchange between terrestrial ecosystems and the atmosphere due to land-use change have become increasingly important. One source of land-use changes estimates comes from comparing multi-date remote sensing imagery, though the effect of land-cover clas...

  10. Land-use change and carbon sinks: Econometric estimation of the carbon sequestration supply function

    Energy Technology Data Exchange (ETDEWEB)

    Lubowski, Ruben N.; Plantinga, Andrew J.; Stavins, Robert N.

    2001-01-01

    Increased attention by policy makers to the threat of global climate change has brought with it considerable interest in the possibility of encouraging the expansion of forest area as a means of sequestering carbon dioxide. The marginal costs of carbon sequestration or, equivalently, the carbon sequestration supply function will determine the ultimate effects and desirability of policies aimed at enhancing carbon uptake. In particular, marginal sequestration costs are the critical statistic for identifying a cost-effective policy mix to mitigate net carbon dioxide emissions. We develop a framework for conducting an econometric analysis of land use for the forty-eight contiguous United States and employing it to estimate the carbon sequestration supply function. By estimating the opportunity costs of land on the basis of econometric evidence of landowners' actual behavior, we aim to circumvent many of the shortcomings of previous sequestration cost assessments. By conducting the first nationwide econometric estimation of sequestration costs, endogenizing prices for land-based commodities, and estimating land-use transition probabilities in a framework that explicitly considers the range of land-use alternatives, we hope to provide better estimates eventually of the true costs of large-scale carbon sequestration efforts. In this way, we seek to add to understanding of the costs and potential of this strategy for addressing the threat of global climate change.

  11. Estimating ground water recharge from topography, hydrogeology, and land cover.

    Science.gov (United States)

    Cherkauer, Douglas S; Ansari, Sajjad A

    2005-01-01

    Proper management of ground water resources requires knowledge of the rates and spatial distribution of recharge to aquifers. This information is needed at scales ranging from that of individual communities to regional. This paper presents a methodology to calculate recharge from readily available ground surface information without long-term monitoring. The method is viewed as providing a reasonable, but conservative, first approximation of recharge, which can then be fine-tuned with other methods as time permits. Stream baseflow was measured as a surrogate for recharge in small watersheds in southeastern Wisconsin. It is equated to recharge (R) and then normalized to observed annual precipitation (P). Regression analysis was constrained by requiring that the independent and dependent variables be dimensionally consistent. It shows that R/P is controlled by three dimensionless ratios: (1) infiltrating to overland water flux, (2) vertical to lateral distance water must travel, and (3) percentage of land cover in the natural state. The individual watershed properties that comprise these ratios are now commonly available in GIS data bases. The empirical relationship for predicting R/P developed for the study watersheds is shown to be statistically viable and is then tested outside the study area and against other methods of calculating recharge. The method produces values that agree with baseflow separation from streamflow hydrographs (to within 15% to 20%), ground water budget analysis (4%), well hydrograph analysis (12%), and a distributed-parameter watershed model calibrated to total streamflow (18%). It has also reproduced the temporal variation over 5 yr observed at a well site with an average error < 12%.

  12. Estimation of Land Surface Temperature from 1-km AVHRR data

    Science.gov (United States)

    Frey, Corinne

    2016-04-01

    In order to re-process DLRs 1km AVHRR data archive to different geophysical and descriptive parameters of the land surface and the atmosphere, a series of scientific data processors are being developed in the framework of the TIMELINE project. The archive of DLR ranges back to the 80ies. One of the data processors is SurfTemp, which processes L2 LST and emissivity datasets from AVHRR L1b data. The development of the data processor included the selection of statistical procedures suitable for time series processing, including four mono-window and six split window algorithms. For almost all of these algorithms, new constants were generated, which better account for different atmospheric and geometric acquisition situations. The selection of optimal algorithms for SurfTemp is based on a round robin approach, in which the selected mono-window and split window algorithms are tested on the basis of a large number of TOA radiance/LST pairs, which were generated using a radiative transfer model and the SeeBorV5 profile database. The original LSTs are thereby compared to the LSTs derived from the TOA radiances using the mono- and split window algorithms. The algorithm comparison includes measures of precision, as well as the sensitivity of a method to the accuracy of its input data. The results of the round robin are presented, as well as the implementation of selected algorithms into SurfTemp. Further, first cross-validation results between the AVHRR LST and MODIS LST are shown.

  13. Continuous and consistent land use/cover change estimates using socio-ecological data

    Science.gov (United States)

    Marshall, Michael; Norton-Griffiths, Michael; Herr, Harvey; Lamprey, Richard; Sheffield, Justin; Vagen, Tor; Okotto-Okotto, Joseph

    2017-02-01

    A growing body of research shows the importance of land use/cover change (LULCC) on modifying the Earth system. Land surface models are used to stimulate land-atmosphere dynamics at the macroscale, but model bias and uncertainty remain that need to be addressed before the importance of LULCC is fully realized. In this study, we propose a method of improving LULCC estimates for land surface modeling exercises. The method is driven by projectable socio-ecological geospatial predictors available seamlessly across sub-Saharan Africa and yielded continuous (annual) estimates of LULCC at 5 km × 5 km spatial resolution. The method was developed with 2252 sample area frames of 5 km × 5 km consisting of the proportion of several land cover types in Kenya over multiple years. Forty-three socio-ecological predictors were evaluated for model development. Machine learning was used for data reduction, and simple (functional) relationships defined by generalized additive models were constructed on a subset of the highest-ranked predictors (p ≤ 10) to estimate LULCC. The predictors explained 62 and 65 % of the variance in the proportion of agriculture and natural vegetation, respectively, but were less successful at estimating more descriptive land cover types. In each case, population density on an annual basis was the highest-ranked predictor. The approach was compared to a commonly used remote sensing classification procedure, given the wide use of such techniques for macroscale LULCC detection, and outperformed it for each land cover type. The approach was used to demonstrate significant trends in expanding (declining) agricultural (natural vegetation) land cover in Kenya from 1983 to 2012, with the largest increases (declines) occurring in densely populated high agricultural production zones. Future work should address the improvement (development) of existing (new) geospatial predictors and issues of model scalability and transferability.

  14. A comparison of energy expenditure estimates from the Actiheart and Actical physical activity monitors during low intensity activities, walking, and jogging.

    Science.gov (United States)

    Spierer, David K; Hagins, Marshall; Rundle, Andrew; Pappas, Evangelos

    2011-04-01

    Combining accelerometry with heart rate monitoring has been suggested to improve energy estimates, however, it remains unclear whether the single, currently existing commercially available device combining these data streams (Actiheart) provides improved energy estimates compared to simpler and less expensive accelerometry-only devices. The purpose of this study was to compare the validity of the heart rate (HR), accelerometry (ACC), and combined ACC/HR estimates of the Actiheart to the ACC estimates of the Actical during low and moderate intensity activities. Twenty-seven participants (mean age 26.3 ± 7.3) wore an Actical, Actiheart and indirect calorimeter (K4b(2)) while performing card playing, sweeping, lifting weights, walking and jogging activities. All estimates tended to underestimate energy, sometimes by substantial amounts. Viewed across all activities studied, there was no significant difference in the ability of the waist-mounted Actical and torso-mounted Actiheart (ACC, HR, ACC/HR) estimates to predict energy expenditure. However, the Actiheart provided significantly better estimates than the Actical for the activities in which acceleration of the pelvis is not closely related to energy expenditure (card playing, sweeping, lifting weights) and the Actical provided significantly better estimates for level walking and level jogging. Similar to a previous study, the ACC component of the Actiheart was found to be the weakest predictor of energy suggesting it may be responsible for the failure of the combined ACC/HR estimate to equal or better the estimates derived solely from a waist mounted ACC device.

  15. Consistent estimate of ocean warming, land ice melt and sea level rise from Observations

    Science.gov (United States)

    Blazquez, Alejandro; Meyssignac, Benoît; Lemoine, Jean Michel

    2016-04-01

    Based on the sea level budget closure approach, this study investigates the consistency of observed Global Mean Sea Level (GMSL) estimates from satellite altimetry, observed Ocean Thermal Expansion (OTE) estimates from in-situ hydrographic data (based on Argo for depth above 2000m and oceanic cruises below) and GRACE observations of land water storage and land ice melt for the period January 2004 to December 2014. The consistency between these datasets is a key issue if we want to constrain missing contributions to sea level rise such as the deep ocean contribution. Numerous previous studies have addressed this question by summing up the different contributions to sea level rise and comparing it to satellite altimetry observations (see for example Llovel et al. 2015, Dieng et al. 2015). Here we propose a novel approach which consists in correcting GRACE solutions over the ocean (essentially corrections of stripes and leakage from ice caps) with mass observations deduced from the difference between satellite altimetry GMSL and in-situ hydrographic data OTE estimates. We check that the resulting GRACE corrected solutions are consistent with original GRACE estimates of the geoid spherical harmonic coefficients within error bars and we compare the resulting GRACE estimates of land water storage and land ice melt with independent results from the literature. This method provides a new mass redistribution from GRACE consistent with observations from Altimetry and OTE. We test the sensibility of this method to the deep ocean contribution and the GIA models and propose best estimates.

  16. Improving estimates of oil pollution to the sea from land-based sources.

    Science.gov (United States)

    Saito, Laurel; Rosen, Michael R; Roesner, Larry; Howard, Nalin

    2010-07-01

    This paper presents improvements to calculation methods used in the National Research Council's (NRC) Oil in the Sea reports from 2003 and 1985 to estimate land-based contributions of petroleum hydrocarbons to the sea from North America. Using procedures similar to the 2003 report, but with more robust methods for handling non-detections, estimated land-based contributions for 1977 and 2000 were over 50% lower than the best 1996 estimate in the NRC report. The largest loads were from the northeastern United States and the Gulf of Mexico region for both the 2003 report and updated calculations. Calculations involved many sources of uncertainty, including lack of available data, variable methods of measuring and reporting data, and variable methods of reporting values below detection limits. This updated analysis of land-based loads of petroleum hydrocarbons to the sea highlights the continued need for more monitoring and research on inputs, fates and effects of these sources. Published by Elsevier Ltd.

  17. Minnesota Walk-In Access Sites

    Data.gov (United States)

    Minnesota Department of Natural Resources — The Minnesota Walk-In Access site (WIA) GIS data represents areas of private land that have been made open to the public for the purpose of walk-in (foot travel)...

  18. Estimating Agricultural Land Use Change in Karamoja, NE. Uganda Using Very High Resolution Satellite Data

    Science.gov (United States)

    Nakalembe, C. L.

    2013-12-01

    Land use information is useful for deriving biophysical variables for effective planning and management of natural resources. Land use information is also needed to understand negative environmental impacts of land use while maintaining economic and social benefits. Recent maps of land cover and land use have been generated for Africa at the continental scale from coarse resolution data (e.g. MODIS, Spot Vegetation, MERIS, and Landsat). In these map products, croplands and rangelands are generally poorly represented, particularly in semi-arid regions like Karamoja. Products derived from coarse resolution data also fail at mapping subsistence croplands and are limited in their use for extraction of land-cover specific temporal profiles for agricultural monitoring in the study area (Fritz, See, & Rembold, 2010). Given the subsistence nature of agriculture, most fields in Karamoja are very small that care not discernible from other land uses in coarse resolution data and data products such as FAO Africover2000. product derived from 30m Landsat data is one such product. There is a high level of disagreement and large errors of omission and omission due to the coarse resolution of the data used to derive the product. In addition population growth and policy changes in the region have resulted in a shift to agro-pastoralism and systematic expansion of cropland area since 2000. This research will produce an updated agricultural land use map for Karamoja. The land cover map will be used to estimate agricultural land use change in the region and as a filter to extract agricultural land use specific temporal profiles specific to agriculture to compare to crop statistics.

  19. Evaluating the use of sharpened land surface temperature for daily evapotranspiration estimation over irrigated crops in arid lands

    KAUST Repository

    Rosas, Jorge

    2014-12-01

    Satellite remote sensing provides data on land surface characteristics, useful for mapping land surface energy fluxes and evapotranspiration (ET). Land-surface temperature (LST) derived from thermal infrared (TIR) satellite data has been reliably used as a remote indicator of ET and surface moisture status. However, TIR imagery usually operates at a coarser resolution than that of shortwave sensors on the same satellite platform, making it sometimes unsuitable for monitoring of field-scale crop conditions. This study applies the data mining sharpener (DMS; Gao et al., 2012) technique to data from the Moderate Resolution Imaging Spectroradiometer (MODIS), which sharpens the 1 km thermal data down to the resolution of the optical data (250-500 m) based on functional LST and reflectance relationships established using a flexible regression tree approach. The DMS approach adopted here has been enhanced/refined for application over irrigated farming areas located in harsh desert environments in Saudi Arabia. The sharpened LST data is input to an integrated modeling system that uses the Atmosphere-Land Exchange Inverse (ALEXI) model and associated flux disaggregation scheme (DisALEXI) in conjunction with model reanalysis data and remotely sensed data from polar orbiting (MODIS) and geostationary (MSG; Meteosat Second Generation) satellite platforms to facilitate daily estimates of evapotranspiration. Results are evaluated against available flux tower observations over irrigated maize near Riyadh in Saudi Arabia. Successful monitoring of field-scale changes in surface fluxes are of importance towards an efficient water use in areas where fresh water resources are scarce and poorly monitored. Gao, F.; Kustas, W.P.; Anderson, M.C. A Data Mining Approach for Sharpening Thermal Satellite Imagery over Land. Remote Sens. 2012, 4, 3287-3319.

  20. Estimating impacts of climate change policy on land use: an agent-based modelling approach.

    Science.gov (United States)

    Morgan, Fraser J; Daigneault, Adam J

    2015-01-01

    Agriculture is important to New Zealand's economy. Like other primary producers, New Zealand strives to increase agricultural output while maintaining environmental integrity. Utilising modelling to explore the economic, environmental and land use impacts of policy is critical to understand the likely effects on the sector. Key deficiencies within existing land use and land cover change models are the lack of heterogeneity in farmers and their behaviour, the role that social networks play in information transfer, and the abstraction of the global and regional economic aspects within local-scale approaches. To resolve these issues we developed the Agent-based Rural Land Use New Zealand model. The model utilises a partial equilibrium economic model and an agent-based decision-making framework to explore how the cumulative effects of individual farmer's decisions affect farm conversion and the resulting land use at a catchment scale. The model is intended to assist in the development of policy to shape agricultural land use intensification in New Zealand. We illustrate the model, by modelling the impact of a greenhouse gas price on farm-level land use, net revenue, and environmental indicators such as nutrient losses and soil erosion for key enterprises in the Hurunui and Waiau catchments of North Canterbury in New Zealand. Key results from the model show that farm net revenue is estimated to increase over time regardless of the greenhouse gas price. Net greenhouse gas emissions are estimated to decline over time, even under a no GHG price baseline, due to an expansion of forestry on low productivity land. Higher GHG prices provide a greater net reduction of emissions. While social and geographic network effects have minimal impact on net revenue and environmental outputs for the catchment, they do have an effect on the spatial arrangement of land use and in particular the clustering of enterprises.

  1. Estimating impacts of climate change policy on land use: an agent-based modelling approach.

    Directory of Open Access Journals (Sweden)

    Fraser J Morgan

    Full Text Available Agriculture is important to New Zealand's economy. Like other primary producers, New Zealand strives to increase agricultural output while maintaining environmental integrity. Utilising modelling to explore the economic, environmental and land use impacts of policy is critical to understand the likely effects on the sector. Key deficiencies within existing land use and land cover change models are the lack of heterogeneity in farmers and their behaviour, the role that social networks play in information transfer, and the abstraction of the global and regional economic aspects within local-scale approaches. To resolve these issues we developed the Agent-based Rural Land Use New Zealand model. The model utilises a partial equilibrium economic model and an agent-based decision-making framework to explore how the cumulative effects of individual farmer's decisions affect farm conversion and the resulting land use at a catchment scale. The model is intended to assist in the development of policy to shape agricultural land use intensification in New Zealand. We illustrate the model, by modelling the impact of a greenhouse gas price on farm-level land use, net revenue, and environmental indicators such as nutrient losses and soil erosion for key enterprises in the Hurunui and Waiau catchments of North Canterbury in New Zealand. Key results from the model show that farm net revenue is estimated to increase over time regardless of the greenhouse gas price. Net greenhouse gas emissions are estimated to decline over time, even under a no GHG price baseline, due to an expansion of forestry on low productivity land. Higher GHG prices provide a greater net reduction of emissions. While social and geographic network effects have minimal impact on net revenue and environmental outputs for the catchment, they do have an effect on the spatial arrangement of land use and in particular the clustering of enterprises.

  2. Improving winter leaf area index estimation in coniferous forests and its significance in estimating the land surface albedo

    Science.gov (United States)

    Wang, Rong; Chen, Jing M.; Pavlic, Goran; Arain, Altaf

    2016-09-01

    Winter leaf area index (LAI) of evergreen coniferous forests exerts strong control on the interception of snow, snowmelt and energy balance. Simulation of winter LAI and associated winter processes in land surface models is challenging. Retrieving winter LAI from remote sensing data is difficult due to cloud contamination, poor illumination, lower solar elevation and higher radiation reflection by snow background. Underestimated winter LAI in evergreen coniferous forests is one of the major issues limiting the application of current remote sensing LAI products. It has not been fully addressed in past studies in the literature. In this study, we used needle lifespan to correct winter LAI in a remote sensing product developed by the University of Toronto. For the validation purpose, the corrected winter LAI was then used to calculate land surface albedo at five FLUXNET coniferous forests in Canada. The RMSE and bias values for estimated albedo were 0.05 and 0.011, respectively, for all sites. The albedo map over coniferous forests across Canada produced with corrected winter LAI showed much better agreement with the GLASS (Global LAnd Surface Satellites) albedo product than the one produced with uncorrected winter LAI. The results revealed that the corrected winter LAI yielded much greater accuracy in simulating land surface albedo, making the new LAI product an improvement over the original one. Our study will help to increase the usability of remote sensing LAI products in land surface energy budget modeling.

  3. A One-Source Approach for Estimating Land Surface Heat Fluxes Using Remotely Sensed Land Surface Temperature

    Directory of Open Access Journals (Sweden)

    Yongmin Yang

    2017-01-01

    Full Text Available The partitioning of available energy between sensible heat and latent heat is important for precise water resources planning and management in the context of global climate change. Land surface temperature (LST is a key variable in energy balance process and remotely sensed LST is widely used for estimating surface heat fluxes at regional scale. However, the inequality between LST and aerodynamic surface temperature (Taero poses a great challenge for regional heat fluxes estimation in one-source energy balance models. To address this issue, we proposed a One-Source Model for Land (OSML to estimate regional surface heat fluxes without requirements for empirical extra resistance, roughness parameterization and wind velocity. The proposed OSML employs both conceptual VFC/LST trapezoid model and the electrical analog formula of sensible heat flux (H to analytically estimate the radiometric-convective resistance (rae via a quartic equation. To evaluate the performance of OSML, the model was applied to the Soil Moisture-Atmosphere Coupling Experiment (SMACEX in United States and the Multi-Scale Observation Experiment on Evapotranspiration (MUSOEXE in China, using remotely sensed retrievals as auxiliary data sets at regional scale. Validated against tower-based surface fluxes observations, the root mean square deviation (RMSD of H and latent heat flux (LE from OSML are 34.5 W/m2 and 46.5 W/m2 at SMACEX site and 50.1 W/m2 and 67.0 W/m2 at MUSOEXE site. The performance of OSML is very comparable to other published studies. In addition, the proposed OSML model demonstrates similar skills of predicting surface heat fluxes in comparison to SEBS (Surface Energy Balance System. Since OSML does not require specification of aerodynamic surface characteristics, roughness parameterization and meteorological conditions with high spatial variation such as wind speed, this proposed method shows high potential for routinely acquisition of latent heat flux estimation

  4. Using the Community Land Model to Assess Uncertainty in Basin Scale GRACE-Based Groundwater Estimates

    Science.gov (United States)

    Swenson, S. C.; Lawrence, D. M.

    2015-12-01

    One method for interpreting the variability in total water storage observed by GRACE is to partition the integrated GRACE measurement into its component storage reservoirs based on information provided by hydrological models. Such models, often designed to be used in couple Earth System models, simulate the stocks and fluxes of moisture through the land surface and subsurface. One application of this method attempts to isolate groundwater changes by removing modeled surface water, snow, and soil moisture changes from GRACE total water storage estimates. Human impacts on groundwater variability can be estimated by further removing model estimates of climate-driven groundwater changes. Errors in modeled water storage components directly affect the residual groundwater estimates. Here we examine the influence of model structure and process representation on soil moisture and groundwater uncertainty using the Community Land Model, with a particular focus on basins in the western U.S.

  5. Estimating Hydrologic Fluxes, Crop Water Use, and Agricultural Land Area in China using Data Assimilation

    Science.gov (United States)

    Smith, Tiziana; McLaughlin, Dennis B.; Hoisungwan, Piyatida

    2016-04-01

    Crop production has significantly altered the terrestrial environment by changing land use and by altering the water cycle through both co-opted rainfall and surface water withdrawals. As the world's population continues to grow and individual diets become more resource-intensive, the demand for food - and the land and water necessary to produce it - will continue to increase. High-resolution quantitative data about water availability, water use, and agricultural land use are needed to develop sustainable water and agricultural planning and policies. However, existing data covering large areas with high resolution are susceptible to errors and can be physically inconsistent. China is an example of a large area where food demand is expected to increase and a lack of data clouds the resource management dialogue. Some assert that China will have insufficient land and water resources to feed itself, posing a threat to global food security if they seek to increase food imports. Others believe resources are plentiful. Without quantitative data, it is difficult to discern if these concerns are realistic or overly dramatized. This research presents a quantitative approach using data assimilation techniques to characterize hydrologic fluxes, crop water use (defined as crop evapotranspiration), and agricultural land use at 0.5 by 0.5 degree resolution and applies the methodology in China using data from around the year 2000. The approach uses the principles of water balance and of crop water requirements to assimilate existing data with a least-squares estimation technique, producing new estimates of water and land use variables that are physically consistent while minimizing differences from measured data. We argue that this technique for estimating water fluxes and agricultural land use can provide a useful basis for resource management modeling and policy, both in China and around the world.

  6. Moving human full body and body parts detection, tracking, and applications on human activity estimation, walking pattern and face recognition

    Science.gov (United States)

    Chen, Hai-Wen; McGurr, Mike

    2016-05-01

    We have developed a new way for detection and tracking of human full-body and body-parts with color (intensity) patch morphological segmentation and adaptive thresholding for security surveillance cameras. An adaptive threshold scheme has been developed for dealing with body size changes, illumination condition changes, and cross camera parameter changes. Tests with the PETS 2009 and 2014 datasets show that we can obtain high probability of detection and low probability of false alarm for full-body. Test results indicate that our human full-body detection method can considerably outperform the current state-of-the-art methods in both detection performance and computational complexity. Furthermore, in this paper, we have developed several methods using color features for detection and tracking of human body-parts (arms, legs, torso, and head, etc.). For example, we have developed a human skin color sub-patch segmentation algorithm by first conducting a RGB to YIQ transformation and then applying a Subtractive I/Q image Fusion with morphological operations. With this method, we can reliably detect and track human skin color related body-parts such as face, neck, arms, and legs. Reliable body-parts (e.g. head) detection allows us to continuously track the individual person even in the case that multiple closely spaced persons are merged. Accordingly, we have developed a new algorithm to split a merged detection blob back to individual detections based on the detected head positions. Detected body-parts also allow us to extract important local constellation features of the body-parts positions and angles related to the full-body. These features are useful for human walking gait pattern recognition and human pose (e.g. standing or falling down) estimation for potential abnormal behavior and accidental event detection, as evidenced with our experimental tests. Furthermore, based on the reliable head (face) tacking, we have applied a super-resolution algorithm to enhance

  7. Estimation of land remote sensing satellites productivity based on the simulation technique

    Science.gov (United States)

    Kurenkov, Vladimir I.; Kucherov, Alexander S.; Yakischik, Artem A.

    2017-01-01

    The problem of estimating land remote sensing satellites productivity is considered. Here, productivity is treated as a number of separate survey objects taken in a definite time. Appropriate mathematical models have been developed. Some results obtained with the help of the software worked out in Delphi programming support environment are presented.

  8. Estimating the ratio of pond size to irrigated soybeans land in Mississippi: A case study

    Science.gov (United States)

    Although more on-farm storage ponds have been constructed in recent years to mitigate groundwater resources depletion in Mississippi, little effort has been devoted to estimating the ratio of pond size to irrigated crop land based on pond matric and its hydrological conditions. Knowledge of this ra...

  9. Estimating the ratio of pond size to irrigated soybean land in Mississippi: a case study

    Science.gov (United States)

    Ying Ouyang; G. Feng; J. Read; T. D. Leininger; J. N. Jenkins

    2016-01-01

    Although more on-farm storage ponds have been constructed in recent years to mitigate groundwater resources depletion in Mississippi, little effort has been devoted to estimating the ratio of on-farm water storage pond size to irrigated crop land based on pond metric and its hydrogeological conditions.  In this study, two simulation scenarios were chosen to...

  10. Assimilation of gridded GRACE terrestrial water storage estimates in the North American Land Data Assimilation System

    Science.gov (United States)

    The objective of the North American Land Data Assimilation System (NLDAS) is to provide best-available estimates of near surface meteorological conditions and soil hydrological status for the Continental United States. The first two phases of NLDAS, however, have not included the assimilation of rem...

  11. Artificial neural network estimation of soil erosion and nutrient concentrations in runoff from land application areas

    Science.gov (United States)

    The transport of sediment and nutrients from land application areas is an environmental concern. New methods are needed for estimating soil and nutrient concentrations of runoff from cropland areas on which manure is applied. Artificial Neural Networks (ANN) trained with a Backpropagation (BP) algor...

  12. Estimated occupational risk from bioaerosols generated during land application of Class B biosolids

    Science.gov (United States)

    It has been speculated that bioaerosols generated during land application of biosolids pose a serious occupational risk, but few scientific studies have been performed to assess levels of aerosolization of microorganisms from biosolids and to estimate the occupational risks of infection. This study ...

  13. Satellite detection of land-use change and effects on regional forest aboveground biomass estimates.

    Science.gov (United States)

    Zheng, Daolan; Heath, Linda S; Ducey, Mark J

    2008-09-01

    We used remote-sensing-driven models to detect land-cover change effects on forest aboveground biomass (AGB) density (Mg.ha(-1), dry weight) and total AGB (Tg) in Minnesota, Wisconsin, and Michigan USA, between the years 1992-2001, and conducted an evaluation of the approach. Inputs included remotely-sensed 1992 reflectance data and land-cover map (University of Maryland) from Advanced Very High Resolution Radiometer (AVHRR) and 2001 products from Moderate Resolution Imaging Spectroradiometer (MODIS) at 1-km resolution for the region; and 30-m resolution land-cover maps from the National Land Cover Data (NLCD) for a subarea to conduct nine simulations to address our questions. Sensitivity analysis showed that (1) AVHRR data tended to underestimate AGB density by 11%, on average, compared to that estimated using MODIS data; (2) regional mean AGB density increased slightly from 124 (1992) to 126 Mg ha(-1) (2001) by 1.6%; (3) a substantial decrease in total forest AGB across the region was detected, from 2,507 (1992) to 1,961 Tg (2001), an annual rate of -2.4%; and (4) in the subarea, while NLCD-based estimates suggested a 26% decrease in total AGB from 1992 to 2001, AVHRR/MODIS-based estimates indicated a 36% increase. The major source of uncertainty in change detection of total forest AGB over large areas was due to area differences from using land-cover maps produced by different sources. Scaling up 30-m land-cover map to 1-km resolution caused a mean difference of 8% (in absolute value) in forest area estimates at the county-level ranging from 0 to 17% within a 95% confidence interval.

  14. Bayesian Estimation for Land Surface Temperature Retrieval: The Nuisance of Emissivities

    CERN Document Server

    Morgan, J A

    2004-01-01

    An approach to the remote sensing of land surface temperature is developed using the methods of Bayesian inference. The starting point is the maximum entropy estimate for the posterior distribution of radiance in multiple bands. In order to convert this quantity to an estimator for surface temperature and emissivity with Bayes' theorem, it is necessary to obtain the joint prior probability for surface temperature and emissivity, given available prior knowledge. The requirement that any pair of distinct observers be able to relate their descriptions of radiance under arbitrary Lorentz transformations uniquely determines the prior probability. Perhaps surprisingly, surface temperature acts as a scale parameter, while emissivity acts as a location parameter, giving the prior probability P(T,emissivity|K)=const./T dT d(emissivity). Given this result, it is a simple matter to construct estimators for surface temperature and emssivity. Monte Carlo simulations of land surface temeprature retrieval in selected MODIS ...

  15. Tropical Africa: Land Use, Biomass, and Carbon Estimates for 1980 (NDP-055)

    Energy Technology Data Exchange (ETDEWEB)

    Brown, S.

    2002-04-16

    This document describes the contents of a digital database containing maximum potential aboveground biomass, land use, and estimated biomass and carbon data for 1980. The biomass data and carbon estimates are associated with woody vegetation in Tropical Africa. These data were collected to reduce the uncertainty associated with estimating historical releases of carbon from land use change. Tropical Africa is defined here as encompassing 22.7 x 10{sup 6} km{sup 2} of the earth's land surface and is comprised of countries that are located in tropical Africa (Angola, Botswana, Burundi, Cameroon, Cape Verde, Central African Republic, Chad, Congo, Benin, Equatorial Guinea, Ethiopia, Djibouti, Gabon, Gambia, Ghana, Guinea, Ivory Coast, Kenya, Liberia, Madagascar, Malawi, Mali, Mauritania, Mozambique, Namibia, Niger, Nigeria, Guinea-Bissau, Zimbabwe (Rhodesia), Rwanda, Senegal, Sierra Leone, Somalia, Sudan, Tanzania, Togo, Uganda, Burkina Faso (Upper Volta), Zaire, and Zambia). The database was developed using the GRID module in the ARC/INFO{trademark} geographic information system. Source data were obtained from the Food and Agriculture Organization (FAO), the U.S. National Geophysical Data Center, and a limited number of biomass-carbon density case studies. These data were used to derive the maximum potential and actual (ca. 1980) aboveground biomass values at regional and country levels. The land-use data provided were derived from a vegetation map originally produced for the FAO by the International Institute of Vegetation Mapping, Toulouse, France.

  16. Total Land Water Storage Change over 2003 - 2013 Estimated from a Global Mass Budget Approach

    Science.gov (United States)

    Dieng, H. B.; Champollion, N.; Cazenave, A.; Wada, Y.; Schrama, E.; Meyssignac, B.

    2015-01-01

    We estimate the total land water storage (LWS) change between 2003 and 2013 using a global water mass budget approach. Hereby we compare the ocean mass change (estimated from GRACE space gravimetry on the one hand, and from the satellite altimetry-based global mean sea level corrected for steric effects on the other hand) to the sum of the main water mass components of the climate system: glaciers, Greenland and Antarctica ice sheets, atmospheric water and LWS (the latter being the unknown quantity to be estimated). For glaciers and ice sheets, we use published estimates of ice mass trends based on various types of observations covering different time spans between 2003 and 2013. From the mass budget equation, we derive a net LWS trend over the study period. The mean trend amounts to +0.30 +/- 0.18 mm/yr in sea level equivalent. This corresponds to a net decrease of -108 +/- 64 cu km/yr in LWS over the 2003-2013 decade. We also estimate the rate of change in LWS and find no significant acceleration over the study period. The computed mean global LWS trend over the study period is shown to be explained mainly by direct anthropogenic effects on land hydrology, i.e. the net effect of groundwater depletion and impoundment of water in man-made reservoirs, and to a lesser extent the effect of naturally-forced land hydrology variability. Our results compare well with independent estimates of human-induced changes in global land hydrology.

  17. Walking abnormalities

    Science.gov (United States)

    ... safety reasons, especially on uneven ground. See a physical therapist for exercise therapy and walking retraining. For a ... the right position for standing and walking. A physical therapist can supply these and provide exercise therapy, if ...

  18. The validity of an accelerometer-based method for estimating fluidity in the sit-to-walk task in a community setting.

    Science.gov (United States)

    Asakura, Tomoyuki; Miyazawa, Yoshiyuki; Usuda, Shigeru

    2017-01-01

    [Purpose] Fluidity in the sit-to-walk task has been quantitatively measured with three-dimensional motion analysis system. The purpose of this study was to determine the validity of an accelerometer-based method for estimating fluidity in community-dwelling elderly individuals. [Subjects and Methods] Seventeen community-dwelling elderly females performed a sit-to-walk task. The motion was recorded by an accelerometer, a three-dimensional motion analysis system and a foot pressure sensor simultaneously. The timings of events determined from the acceleration waveform were compared to the timings determined from the three-dimensional motion analysis data (task onset, maximum trunk inclination) or foot pressure sensor data (first heel strike). Regression analysis was used to estimate the fluidity index from the duration between events. [Results] The characteristics of the acceleration waveform were similar to those previously reported in younger adults. Comparisons of event timings from accelerometer and motion analysis system data indicated no systematic bias. Regression analysis showed that the duration from maximum trunk inclination to the first heel strike was the best predictor of fluidity index. [Conclusion] An accelerometer-based method using the duration between characteristic events may be used to precisely and conveniently assess fluidity in a sit-to-walk task in a community setting.

  19. Estimating European soil organic carbon mitigation potential in a global integrated land use model

    Science.gov (United States)

    Frank, Stefan; Böttcher, Hannes; Schneider, Uwe; Schmid, Erwin; Havlík, Petr

    2013-04-01

    Several studies have shown the dynamic interaction between soil organic carbon (SOC) sequestration rates, soil management decisions and SOC levels. Management practices such as reduced and no-tillage, improved residue management and crop rotations as well as the conversion of marginal cropland to native vegetation or conversion of cultivated land to permanent grassland offer the potential to increase SOC content. Even though dynamic interactions are widely acknowledged in literature, they have not been implemented in most existing land use decision models. A major obstacle is the high data and computing requirements for an explicit representation of alternative land use sequences since a model has to be able to track all different management decision paths. To our knowledge no study accounted so far for SOC dynamics explicitly in a global integrated land use model. To overcome these conceptual difficulties described above we apply an approach capable of accounting for SOC dynamics in GLOBIOM (Global Biosphere Management Model), a global recursive dynamic partial equilibrium bottom-up model integrating the agricultural, bioenergy and forestry sectors. GLOBIOM represents all major land based sectors and therefore is able to account for direct and indirect effects of land use change as well as leakage effects (e.g. through trade) implicitly. Together with the detailed representation of technologies (e.g. tillage and fertilizer management systems), these characteristics make the model a highly valuable tool for assessing European SOC emissions and mitigation potential. Demand and international trade are represented in this version of the model at the level of 27 EU member states and 23 aggregated world regions outside Europe. Changes in the demand on the one side, and profitability of the different land based activities on the other side, are the major determinants of land use change in GLOBIOM. In this paper we estimate SOC emissions from cropland for the EU until

  20. Estimation of un-used land potential for biofuels development in China

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Yishui [Chinese Academy of Agricultural Engineering, Beijing 100026 (China); Maelardalen University, Vaesteraas SE-721 23 (Sweden); Zhao, Lixin; Meng, Haibo; Sun, Liying [Chinese Academy of Agricultural Engineering, Beijing 100026 (China); Yan, Jinyue [Maelardalen University, Vaesteraas SE-721 23 (Sweden); Royal Institute of Technology, SE-100 44 Stockholm (Sweden)

    2009-11-15

    This paper presents the current status of biofuel development and estimates the potential of un-used land for biofuel development. The potential of crops including cassava, sweet potato, sweet sorghum, sugarcane, sugar beet and Jerusalem artichoke were assessed and discussed for different regions considering the geographical conditions and features of agricultural production. If reserved land resources are explored together with substitute planting implemented and unit area yield improved, potential production of ethanol fuel will be 22 million ton in 2020. The study also recommends the use of winter idle lands for rapeseed plantation for biofuel production. The potential for production of biodiesel by rapeseed and cottonseed can reach to 3.59 million ton. (author)

  1. CATCH ESTIMATION AND SIZE DISTRIBUTION OF BILLFISHES LANDED IN PORT OF BENOA, BALI

    Directory of Open Access Journals (Sweden)

    Bram Setyadji

    2012-06-01

    Full Text Available Billfishes are generally considered as by-product in tuna long line fisheries that have high economic value in the market. By far, the information about Indian Ocean billfish biology and fisheries especially in Indonesia is very limited. This research aimed to elucidate the estimation of production and size distribution of billfishes landed in port of Benoa during 2010 (February – December through daily observation at the processing plants. The result showed that the landings dominated by Swordfish (Xiphias gladius 54.9%, Blue marlin (Makaira mazara 17.8% and Black marlin (Makaira indica 13.0% respectively, followed by small amount of striped marlin (Tetrapturus audax, sailfish (Istiophorus platypterus, and shortbil spearfish (Tetrapturus Angustirostris. Generally the individual size of billfishes range between 68 and 206 cm (PFL, and showing negative allometric pattern except on swordfish that was isometric. Most of the billfish landed haven’t reached their first sexual maturity.

  2. Estimating Land Development Time Lags in China Using DMSP/OLS Nighttime Light Image

    Directory of Open Access Journals (Sweden)

    Li Zhang

    2015-01-01

    Full Text Available The Chinese real estate industry has experienced rapid growth since China’s economic reform. Along with a booming industry, a third of purchased lands were left undeveloped in the last decade. Knowledge of real estate development time lags between land being purchased and property being occupied can enable policymakers to produce more effective policies and regulations to guide the real estate industry and sustain economic development and social welfare. This paper presents an innovative method to estimate provincial land development time lags in China using DMSP/OLS NTL imagery and real estate statistical data. The results showed that real estate development time lag was common in China during 2000–2010. More than half of the study sites showed development time lags of three years or longer. An Increment of Developed Pixels (IDP index was established to outline yearly land development completions in China between 2000 and 2010. A Comprehensive Real Estate Price Index (CREPI was created to explore the causes of the time lags. A strong and positive correlation was found between the real estate development time lags and CREPI values (with r = 0.619, n = 31, p < 0.0005. The results indicated that the land development time lag during the study period was positively correlated to the activity of the local real estate market, the price trend of land and housing properties, and the local economic situation. The results also proved that with the support of statistical data the DMSP/OLS NTL image could offer an economically efficient and reliable solution to estimate the time lag of real estate development.

  3. Estimation of quasi-stiffness and propulsive work of the human ankle in the stance phase of walking.

    Science.gov (United States)

    Shamaei, Kamran; Sawicki, Gregory S; Dollar, Aaron M

    2013-01-01

    Characterizing the quasi-stiffness and work of lower extremity joints is critical for evaluating human locomotion and designing assistive devices such as prostheses and orthoses intended to emulate the biological behavior of human legs. This work aims to establish statistical models that allow us to predict the ankle quasi-stiffness and net mechanical work for adults walking on level ground. During the stance phase of walking, the ankle joint propels the body through three distinctive phases of nearly constant stiffness known as the quasi-stiffness of each phase. Using a generic equation for the ankle moment obtained through an inverse dynamics analysis, we identify key independent parameters needed to predict ankle quasi-stiffness and propulsive work and also the functional form of each correlation. These parameters include gait speed, ankle excursion, and subject height and weight. Based on the identified form of the correlation and key variables, we applied linear regression on experimental walking data for 216 gait trials across 26 subjects (speeds from 0.75-2.63 m/s) to obtain statistical models of varying complexity. The most general forms of the statistical models include all the key parameters and have an R(2) of 75% to 81% in the prediction of the ankle quasi-stiffnesses and propulsive work. The most specific models include only subject height and weight and could predict the ankle quasi-stiffnesses and work for optimal walking speed with average error of 13% to 30%. We discuss how these models provide a useful framework and foundation for designing subject- and gait-specific prosthetic and exoskeletal devices designed to emulate biological ankle function during level ground walking.

  4. Estimation of quasi-stiffness and propulsive work of the human ankle in the stance phase of walking.

    Directory of Open Access Journals (Sweden)

    Kamran Shamaei

    Full Text Available Characterizing the quasi-stiffness and work of lower extremity joints is critical for evaluating human locomotion and designing assistive devices such as prostheses and orthoses intended to emulate the biological behavior of human legs. This work aims to establish statistical models that allow us to predict the ankle quasi-stiffness and net mechanical work for adults walking on level ground. During the stance phase of walking, the ankle joint propels the body through three distinctive phases of nearly constant stiffness known as the quasi-stiffness of each phase. Using a generic equation for the ankle moment obtained through an inverse dynamics analysis, we identify key independent parameters needed to predict ankle quasi-stiffness and propulsive work and also the functional form of each correlation. These parameters include gait speed, ankle excursion, and subject height and weight. Based on the identified form of the correlation and key variables, we applied linear regression on experimental walking data for 216 gait trials across 26 subjects (speeds from 0.75-2.63 m/s to obtain statistical models of varying complexity. The most general forms of the statistical models include all the key parameters and have an R(2 of 75% to 81% in the prediction of the ankle quasi-stiffnesses and propulsive work. The most specific models include only subject height and weight and could predict the ankle quasi-stiffnesses and work for optimal walking speed with average error of 13% to 30%. We discuss how these models provide a useful framework and foundation for designing subject- and gait-specific prosthetic and exoskeletal devices designed to emulate biological ankle function during level ground walking.

  5. Daytime sensible heat flux estimation over heterogeneous surfaces using multitemporal land-surface temperature observations

    Science.gov (United States)

    Castellví, F.; Cammalleri, C.; Ciraolo, G.; Maltese, A.; Rossi, F.

    2016-05-01

    Equations based on surface renewal (SR) analysis to estimate the sensible heat flux (H) require as input the mean ramp amplitude and period observed in the ramp-like pattern of the air temperature measured at high frequency. A SR-based method to estimate sensible heat flux (HSR-LST) requiring only low-frequency measurements of the air temperature, horizontal mean wind speed, and land-surface temperature as input was derived and tested under unstable conditions over a heterogeneous canopy (olive grove). HSR-LST assumes that the mean ramp amplitude can be inferred from the difference between land-surface temperature and mean air temperature through a linear relationship and that the ramp frequency is related to a wind shear scale characteristic of the canopy flow. The land-surface temperature was retrieved by integrating in situ sensing measures of thermal infrared energy emitted by the surface. The performance of HSR-LST was analyzed against flux tower measurements collected at two heights (close to and well above the canopy top). Crucial parameters involved in HSR-LST, which define the above mentioned linear relationship, were explained using the canopy height and the land surface temperature observed at sunrise and sunset. Although the olive grove can behave as either an isothermal or anisothermal surface, HSR-LST performed close to H measured using the eddy covariance and the Bowen ratio energy balance methods. Root mean square differences between HSR-LST and measured H were of about 55 W m-2. Thus, by using multitemporal thermal acquisitions, HSR-LST appears to bypass inconsistency between land surface temperature and the mean aerodynamic temperature. The one-source bulk transfer formulation for estimating H performed reliable after calibration against the eddy covariance method. After calibration, the latter performed similar to the proposed SR-LST method.

  6. The potential of more accurate InSAR covariance matrix estimation for land cover mapping

    Science.gov (United States)

    Jiang, Mi; Yong, Bin; Tian, Xin; Malhotra, Rakesh; Hu, Rui; Li, Zhiwei; Yu, Zhongbo; Zhang, Xinxin

    2017-04-01

    Synthetic aperture radar (SAR) and Interferometric SAR (InSAR) provide both structural and electromagnetic information for the ground surface and therefore have been widely used for land cover classification. However, relatively few studies have developed analyses that investigate SAR datasets over richly textured areas where heterogeneous land covers exist and intermingle over short distances. One of main difficulties is that the shapes of the structures in a SAR image cannot be represented in detail as mixed pixels are likely to occur when conventional InSAR parameter estimation methods are used. To solve this problem and further extend previous research into remote monitoring of urban environments, we address the use of accurate InSAR covariance matrix estimation to improve the accuracy of land cover mapping. The standard and updated methods were tested using the HH-polarization TerraSAR-X dataset and compared with each other using the random forest classifier. A detailed accuracy assessment complied for six types of surfaces shows that the updated method outperforms the standard approach by around 9%, with an overall accuracy of 82.46% over areas with rich texture in Zhuhai, China. This paper demonstrates that the accuracy of land cover mapping can benefit from the 3 enhancement of the quality of the observations in addition to classifiers selection and multi-source data ingratiation reported in previous studies.

  7. Housing land transaction data and structural econometric estimation of preference parameters for urban economic simulation models.

    Science.gov (United States)

    Caruso, Geoffrey; Cavailhès, Jean; Peeters, Dominique; Thomas, Isabelle; Frankhauser, Pierre; Vuidel, Gilles

    2015-12-01

    This paper describes a dataset of 6284 land transactions prices and plot surfaces in 3 medium-sized cities in France (Besançon, Dijon and Brest). The dataset includes road accessibility as obtained from a minimization algorithm, and the amount of green space available to households in the neighborhood of the transactions, as evaluated from a land cover dataset. Further to the data presentation, the paper describes how these variables can be used to estimate the non-observable parameters of a residential choice function explicitly derived from a microeconomic model. The estimates are used by Caruso et al. (2015) to run a calibrated microeconomic urban growth simulation model where households are assumed to trade-off accessibility and local green space amenities.

  8. Integrating Address Geocoding, Land Use Regression, and Spatiotemporal Geostatistical Estimation for Groundwater Tetrachloroethylene

    OpenAIRE

    Messier, Kyle P.; Akita, Yasuyuki; Serre, Marc L.

    2012-01-01

    Geographic Information Systems (GIS) based techniques are cost-effective and efficient methods used by state agencies and epidemiology researchers for estimating concentration and exposure. However, budget limitations have made statewide assessments of contamination difficult, especially in groundwater media. Many studies have implemented address geocoding, land use regression, and geostatistics independently, but this is the first to examine the benefits of integrating these GIS techniques t...

  9. How does the seasonality influence utilitarian walking behaviour in different urbanization settings in Scotland?

    Science.gov (United States)

    Hong, Jinhyun

    2016-08-01

    The relationship between the built environment and walking has been analyzed for decades. However, the seasonality effects on the relationship between the built environment and walking have not been well examined even though weather is one of the key determinants of walking. Therefore, this study used 2007-8 Scottish Household Survey data collected over two years and estimated the interaction effects between the urbanization setting (i.e., residential locations: urban, town and rural areas) and seasons (i.e., spring, summer, autumn and winter) on walking. Scottish Urban-rural classification scheme is measured based on the population and access to large cities, and used as a key independent variable. The number of walking days for specific purposes such as work or shopping (utilitarian walking) during the past 7 days is used as a dependent variable. The results show that there are significant geographical variations of seasonality effect on utilitarian walking. That is, people living in rural areas are more sensitive to seasonality impacts than those living in urban areas. In addition, we found that the association between urbanization setting and utilitarian walking varies across seasons, indicating that their relationship can be miss-estimated if we ignore the seasonality effects. Therefore, policy makers and practitioners should consider the seasonality effects to evaluate the effectiveness of land use policy correctly. Finally, we still find the significant association between the urbanization setting and utilitarian walking behaviour with the consideration of seasonality effects, supporting the claim of New Urbanism.

  10. Application of the unwrapped phase inversion to land data without source estimation

    KAUST Repository

    Choi, Yun Seok

    2015-08-19

    Unwrapped phase inversion with a strong damping was developed to solve the phase wrapping problem in frequency-domain waveform inversion. In this study, we apply the unwrapped phase inversion to band-limited real land data, for which the available minimum frequency is quite high. An important issue of the data is a strong ambiguity of source-ignition time (or source shift) shown in a seismogram. A source-estimation approach does not fully address the issue of source shift, since the velocity model and the source wavelet are updated simultaneously and interact with each other. We suggest a source-independent unwrapped phase inversion approach instead of relying on source-estimation from this land data. In the source-independent approach, the phase of the modeled data converges not to the exact phase value of the observed data, but to the relative phase value (or the trend of phases); thus it has the potential to solve the ambiguity of source-ignition time in a seismogram and work better than the source-estimation approach. Numerical examples show the validation of the source-independent unwrapped phase inversion, especially for land field data having an ambiguity in the source-ignition time.

  11. Application of Wenner Configuration to Estimate Soil Water Content in Pine Plantations on Sandy Land

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    To estimate the mean value of surface soil water content rapidly, accurately, and nonintrusively, field investigations on soil electrical resistivity (SER) with the Yokogawa 324400 earth resistivity meter and the surface (0-150 cm) soil water content (SWC) with time domain reflectometry (TDR), together with the abiotic factors including soil texture, structure,and salinity concentrations were conducted in the Mongolian pine (Pinus sylvestris var. mongolica) plantations on a sandy land. The measurement of SER was based on the 4-probe Wenner configuration method. Relationships between the values of SWC and SER were obtained based on analysis of the abiotic factors of the research site, which play a key role in affecting the soil electrical resistivity. Results indicate that the SER meter could be used to estimate the mean value of SWC in the Mongolian pine plantations on the sandy land during the growing seasons. The bulky nature of the equipment simplified the cumbersome measurements of soil water content with the general methods. It must be noted that the Wenner configuration method could only provide the mean values of the SWC, and the soil texture, structure,temperature, and solute concentrations influenced the SER and further affected the estimation of the SWC by the SER meter. Therefore, the results of this study could be applied on a sandy land during the growing seasons only. However,the SWC of other soil types also may be obtained according to the individual soil types using the procedures of this study.

  12. Comparing potential recharge estimates from three Land Surface Models across the western US

    Science.gov (United States)

    Niraula, Rewati; Meixner, Thomas; Ajami, Hoori; Rodell, Matthew; Gochis, David; Castro, Christopher L.

    2017-02-01

    Groundwater is a major source of water in the western US. However, there are limited recharge estimates in this region due to the complexity of recharge processes and the challenge of direct observations. Land surface Models (LSMs) could be a valuable tool for estimating current recharge and projecting changes due to future climate change. In this study, simulations of three LSMs (Noah, Mosaic and VIC) obtained from the North American Land Data Assimilation System (NLDAS-2) are used to estimate potential recharge in the western US. Modeled recharge was compared with published recharge estimates for several aquifers in the region. Annual recharge to precipitation ratios across the study basins varied from 0.01% to 15% for Mosaic, 3.2% to 42% for Noah, and 6.7% to 31.8% for VIC simulations. Mosaic consistently underestimates recharge across all basins. Noah captures recharge reasonably well in wetter basins, but overestimates it in drier basins. VIC slightly overestimates recharge in drier basins and slightly underestimates it for wetter basins. While the average annual recharge values vary among the models, the models were consistent in identifying high and low recharge areas in the region. Models agree in seasonality of recharge occurring dominantly during the spring across the region. Overall, our results highlight that LSMs have the potential to capture the spatial and temporal patterns as well as seasonality of recharge at large scales. Therefore, LSMs (specifically VIC and Noah) can be used as a tool for estimating future recharge in data limited regions.

  13. Advances in Observation and Estimation of Land Use Impacts on Climate Changes: Improved Data, Upgraded Models, and Case Studies

    Directory of Open Access Journals (Sweden)

    R. B. Singh

    2014-01-01

    Full Text Available Global land use and land cover pattern has greatly changed in the past 50 years, which exerts direct or indirect influence on the climate change remarkably at both regional and global scales. Therefore, observing and estimating the land use impacts on surface climate is essential and has been continuously promoted by researchers. This paper explores the advancement in the models, data, and application for observing and estimating the land use impacts on surface climate and points out further research needs and priorities, which hopefully will provide some references for related studies.

  14. Could peak oxygen uptake be estimated from proposed equations based on the six-minute walk test in chronic heart failure subjects?

    Science.gov (United States)

    Ribeiro-Samora, Giane A; Montemezzo, Dayane; Pereira, Danielle A G; Tagliaferri, Thaysa L; Vieira, Otávia A; Britto, Raquel R

    To evaluate the agreement between the measured peak oxygen uptake (VO2peak) and the VO2peak estimated by four prediction equations based on the six-minute walk test (6MWT) in chronic heart failure patients. Thirty-six chronic heart failure patients underwent cardiopulmonary exercise testing and the 6MWT to assess their VO2peak. Four previously published equations that include the variable six-minute walk distance were used to estimate the VO2peak: Cahalin, 1996a (1); Cahalin, 1996b (2); Ross, 2010 (3); and Adedoyin, 2010 (4). The agreement between the VO2peak in the cardiopulmonary exercise testing and the estimated values was assessed using the Bland-Altman method. A p-value of <0.05 was considered statistically significant. All estimated VO2peak values presented moderate correlation (ranging from 0.55 to 0.70; p<0.001) with measured VO2peak values. Equations 2, 3, and 4 underestimated the VO2peak by 30%, 15.2%, and 51.2%, respectively, showing significant differences from the actual VO2peak measured in the cardiopulmonary exercise testing (p<0.0001 for all), and the limits of agreement were elevated. The VO2peak estimated by equation 1 was similar to that measured by the cardiopulmonary exercise testing, and despite the agreement, bias increased as VO2peak increased. Only equation 1 showed estimated VO2peak similar to the measured VO2peak; however, a large limits of agreement range (∼3 METs) does not allow its use to estimate maximal VO2peak. Copyright © 2017 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier Editora Ltda. All rights reserved.

  15. Towards scale-independent land-surface flux estimates in Noah-MP

    Science.gov (United States)

    Thober, Stephan; Mizukami, Naoki; Samaniego, Luis; Attinger, Sabine; Clark, Martyn; Cuntz, Matthias

    2017-04-01

    Land-surface models use a variety of process representations to calculate terrestrial energy, water and biogeochemical fluxes. These process descriptions are usually derived from point measurements which are, in turn, scaled to much larger resolutions ranging from 1 km in catchment hydrology to 100 km in climate modelling. Both, hydrologic and climate models are nowadays run on different spatial resolutions, using the exactly same land surface representations. A fundamental criterion for the physical consistency of land-surface simulations across scales is that a flux estimated over a given area is independent of the spatial model resolution (i.e., the flux-matching criterion). The Noah-MP land surface model considers only one soil and land cover type per model grid cell without any representation of their subgrid variability, implying a weak flux-matching. A fractional approach simulates the subgrid variability but it requires a higher computational demand than using effective parameters and it is used only for land cover in current land surface schemes. A promising approach to derive scale-independent parameters is the Multiscale Parameter Regionalization (MPR) technique, which consists of two steps: first, it applies transfer functions directly to high-resolution data (such as 100 m soil maps) to derive high-resolution model parameter fields, acknowledging the full subgrid variability. Second, it upscales these high-resolution parameter fields to the model resolution by using appropriate upscaling operators. MPR has shown to improve substantially the scalability of the mesoscale Hydrologic Models mHM (Samaniego et al., 2010 WRR). Here, we apply the MPR technique to the Noah-MP land-surface model for a large sample of basins distributed across the contiguous USA. Specifically, we evaluate the flux-matching criterion for several hydrologic fluxes such as evapotranspiration and drainage at scales ranging from 3 km to 48 km. We investigate the impact of different

  16. Preindustrial nitrous oxide emissions from the land biosphere estimated by using a global biogeochemistry model

    Science.gov (United States)

    Xu, Rongting; Tian, Hanqin; Lu, Chaoqun; Pan, Shufen; Chen, Jian; Yang, Jia; Zhang, Bowen

    2017-07-01

    To accurately assess how increased global nitrous oxide (N2O) emission has affected the climate system requires a robust estimation of the preindustrial N2O emissions since only the difference between current and preindustrial emissions represents net drivers of anthropogenic climate change. However, large uncertainty exists in previous estimates of preindustrial N2O emissions from the land biosphere, while preindustrial N2O emissions on the finer scales, such as regional, biome, or sector scales, have not been well quantified yet. In this study, we applied a process-based Dynamic Land Ecosystem Model (DLEM) to estimate the magnitude and spatial patterns of preindustrial N2O fluxes at the biome, continental, and global level as driven by multiple environmental factors. Uncertainties associated with key parameters were also evaluated. Our study indicates that the mean of the preindustrial N2O emission was approximately 6.20 Tg N yr-1, with an uncertainty range of 4.76 to 8.13 Tg N yr-1. The estimated N2O emission varied significantly at spatial and biome levels. South America, Africa, and Southern Asia accounted for 34.12, 23.85, and 18.93 %, respectively, together contributing 76.90 % of global total emission. The tropics were identified as the major source of N2O released into the atmosphere, accounting for 64.66 % of the total emission. Our multi-scale estimates provide a robust reference for assessing the climate forcing of anthropogenic N2O emission from the land biosphere

  17. Microclimatic models. Estimation of components of the energy balance over land surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Heikinheimo, M.; Venaelaeinen, A.; Tourula, T. [Finnish Meteorological Inst., Helsinki (Finland). Air Quality Dept.

    1996-12-31

    Climates at regional scale are strongly dependent on the interaction between atmosphere and its lower boundary, the oceans and the land surface mosaic. Land surfaces influence climate through their albedo, and the aerodynamic roughness, the processes of the biosphere and many soil hydrological properties; all these factors vary considerably geographically. Land surfaces receive a certain portion of the solar irradiance depending on the cloudiness, atmospheric transparency and surface albedo. Short-wave solar irradiance is the source of the heat energy exchange at the earth`s surface and also regulates many biological processes, e.g. photosynthesis. Methods for estimating solar irradiance, atmospheric transparency and surface albedo were reviewed during the course of this project. The solar energy at earth`s surface is consumed for heating the soil and the lower atmosphere. Where moisture is available, evaporation is one of the key components of the surface energy balance, because the conversion of liquid water into water vapour consumes heat. The evaporation process was studied by carrying out field experiments and testing parameterisation for a cultivated agricultural surface and for lakes. The micrometeorological study over lakes was carried out as part of the international `Northern Hemisphere Climatic Processes Experiment` (NOPEX/BAHC) in Sweden. These studies have been aimed at a better understanding of the energy exchange processes of the earth`s surface-atmosphere boundary for a more accurate and realistic parameterisation of the land surface in atmospheric models

  18. Estimating maximum global land surface wind power extractability and associated climatic consequences

    Directory of Open Access Journals (Sweden)

    L. M. Miller

    2010-09-01

    Full Text Available The availability of wind power for renewable energy extraction is ultimately limited by how much kinetic energy is generated by natural processes within the Earth system and by fundamental limits of how much of the wind power can be extracted. Here we use these considerations to provide a maximum estimate of wind power availability over land. We use three different methods. First, we use simple, established estimates of the energetics of the atmospheric circulation, which yield about 38 TW of wind power available for extraction. Second, we set up a simple momentum balance model to estimate maximum extractability which we then apply to reanalysis climate data, yielding an estimate of 17 TW. Finally, we perform climate model simulations in which we extract different amounts of momentum from the atmospheric boundary layer to obtain a maximum estimate of how much power can be extracted, yielding 36 TW. These three methods consistently yield maximum estimates in the range of 17–38 TW and are notably less than recent estimates that claim abundant wind power availability. Furthermore, we show with the climate model simulations that the climatic effects at maximum wind power extraction are similar in magnitude to those associated with a doubling of atmospheric CO2. We conclude that in order to understand fundamental limits to renewable energy resources, as well as the impacts of their utilization, it is imperative to use a thermodynamic, Earth system perspective, rather than engineering specifications of the latest technology.

  19. Using Microwave Observations to Estimate Land Surface Temperature during Cloudy Conditions

    Science.gov (United States)

    Holmes, T. R.; Crow, W. T.; Hain, C.; Anderson, M. C.

    2014-12-01

    Land surface temperature (LST), a key ingredient for physically-based retrieval algorithms of hydrological states and fluxes, remains a poorly constrained parameter for global scale studies. The main two observational methods to remotely measure T are based on thermal infrared (TIR) observations and passive microwave observations (MW). TIR is the most commonly used approach and the method of choice to provide standard LST products for various satellite missions. MW-based LST retrievals on the other hand are not as widely adopted for land applications; currently their principle use is in soil moisture retrieval algorithms. MW and TIR technologies present two highly complementary and independent means of measuring LST. MW observations have a high tolerance to clouds but a low spatial resolution, and TIR has a high spatial resolution with temporal sampling restricted to clear skies. The nature of the temperature at the very surface layer of the land makes it difficult to combine temperature estimates between different methods. The skin temperature is characterized by a strong diurnal cycle that is dependant in timing and amplitude on the exact sensing depth and thermal properties of the vegetation. This paper builds on recent progress in characterizing the main structural components of the DTC that explain differences in TIR and MW estimates of LST. Spatial patterns in DTC timing (phase lag with solar noon) and DTC amplitude have been calculated for TIR, MW and compared to weather prediction estimates. Based on these comparisons MW LST can be matched to the TIR record. This paper will compare in situ measurements of LST with satellite estimates from (downscaled) TIR and (reconciled) MW products. By contrasting the validation results of clear sky days with those of cloudy days the expected tolerance to clouds of the MW observations will be tested. The goal of this study is to determine the weather conditions in which MW can supplement the TIR LST record.

  20. Changes in the built environment and changes in the amount of walking over time: longitudinal results from the multi-ethnic study of atherosclerosis.

    Science.gov (United States)

    Hirsch, Jana A; Moore, Kari A; Clarke, Philippa J; Rodriguez, Daniel A; Evenson, Kelly R; Brines, Shannon J; Zagorski, Melissa A; Diez Roux, Ana V

    2014-10-15

    Lack of longitudinal research hinders causal inference on the association between the built environment and walking. In the present study, we used data from 6,027 adults in the Multi-Ethnic Study of Atherosclerosis who were 45-84 years of age at baseline to investigate the association of neighborhood built environment with trends in the amount of walking between 2000 and 2012. Walking for transportation and walking for leisure were assessed at baseline and at 3 follow-up visits (median follow-up = 9.15 years). Time-varying built environment measures (measures of population density, land use, number of destinations, bus access, and street connectivity) were created using geographic information systems. We used linear mixed models to estimate the associations between baseline levels of and a change in each built environment feature and a change in the frequency of walking. After adjustment for potential confounders, we found that higher baseline levels of population density, area zoned for retail, social destinations, walking destinations, and street connectivity were associated with greater increases in walking for transportation over time. Higher baseline levels of land zoned for residential use and distance to buses were associated with less pronounced increases (or decreases) in walking for transportation over time. Increases in the number of social destinations, the number of walking destinations, and street connectivity over time were associated with greater increases in walking for transportation. Higher baseline levels of both land zoned for retail and walking destinations were associated with greater increases in leisure walking, but no changes in built environment features were associated with leisure walking. The creation of mixed-use, dense developments may encourage adults to incorporate walking for transportation into their everyday lives.

  1. Assessing the impact of vertical land motion on twentieth century global mean sea level estimates

    Science.gov (United States)

    Hamlington, B. D.; Thompson, P.; Hammond, W. C.; Blewitt, G.; Ray, R. D.

    2016-07-01

    Near-global and continuous measurements from satellite altimetry have provided accurate estimates of global mean sea level in the past two decades. Extending these estimates further into the past is a challenge using the historical tide gauge records. Not only is sampling nonuniform in both space and time, but tide gauges are also affected by vertical land motion (VLM) that creates a relative sea level change not representative of ocean variability. To allow for comparisons to the satellite altimetry estimated global mean sea level (GMSL), typically the tide gauges are corrected using glacial isostatic adjustment (GIA) models. This approach, however, does not correct other sources of VLM that remain in the tide gauge record. Here we compare Global Positioning System (GPS) VLM estimates at the tide gauge locations to VLM estimates from GIA models, and assess the influence of non-GIA-related VLM on GMSL estimates. We find that the tide gauges, on average, are experiencing positive VLM (i.e., uplift) after removing the known effect of GIA, resulting in an increase of 0.24 ± 0.08 mm yr-1 in GMSL trend estimates from 1900 to present when using GPS-based corrections. While this result is likely dependent on the subset of tide gauges used and the actual corrections used, it does suggest that non-GIA VLM plays a significant role in twentieth century estimates of GMSL. Given the relatively short GPS records used to obtain these VLM estimates, we also estimate the uncertainty in the GMSL trend that results from limited knowledge of non-GIA-related VLM.

  2. Local land-use change based risk estimation for future glacier lake outburst flood

    Directory of Open Access Journals (Sweden)

    S. Nussbaumer

    2013-08-01

    Full Text Available Effects of climate change are particularly strong in high-mountain regions. Most visibly, glaciers are shrinking at a rapid pace, and as a consequence, glacier lakes are forming or growing. At the same time the stability of mountain slopes is reduced by glacier retreat, permafrost thaw and other factors, resulting in an increasing risk of landslides which can potentially impact lakes and therewith trigger far reaching and devastating outburst floods. To manage risks from existing or future lakes, strategies need to be developed to plan in time for adequate risk reduction measures at a local level. However, methods to assess risks from future lake outbursts are not available. It is actually a challenge to develop methods to evaluate both, future hazard potential and future damage potential. Here we present an analysis of future risks related to glacier lake outbursts for a local site in southern Switzerland (Naters, Valais. To estimate two hazard scenarios, we used glacier shrinkage and lake formation modelling, simple flood modelling and field work. Further we developed a land-use model to quantify and allocate land-use changes based on local-to-regional storylines and three scenarios of land-use driving forces. Results are conceptualized in a matrix of three land-use and two hazard scenarios for a time period of 2045, and show the distribution of risk in the community of Naters, including high and very high risk areas. The study corroborates the importance of land-use planning to effectively reduce future risks related to lake outburst floods.

  3. Local land-use change based risk estimation for future glacier lake outburst flood

    Science.gov (United States)

    Nussbaumer, S.; Huggel, C.; Schaub, Y.; Walz, A.

    2013-08-01

    Effects of climate change are particularly strong in high-mountain regions. Most visibly, glaciers are shrinking at a rapid pace, and as a consequence, glacier lakes are forming or growing. At the same time the stability of mountain slopes is reduced by glacier retreat, permafrost thaw and other factors, resulting in an increasing risk of landslides which can potentially impact lakes and therewith trigger far reaching and devastating outburst floods. To manage risks from existing or future lakes, strategies need to be developed to plan in time for adequate risk reduction measures at a local level. However, methods to assess risks from future lake outbursts are not available. It is actually a challenge to develop methods to evaluate both, future hazard potential and future damage potential. Here we present an analysis of future risks related to glacier lake outbursts for a local site in southern Switzerland (Naters, Valais). To estimate two hazard scenarios, we used glacier shrinkage and lake formation modelling, simple flood modelling and field work. Further we developed a land-use model to quantify and allocate land-use changes based on local-to-regional storylines and three scenarios of land-use driving forces. Results are conceptualized in a matrix of three land-use and two hazard scenarios for a time period of 2045, and show the distribution of risk in the community of Naters, including high and very high risk areas. The study corroborates the importance of land-use planning to effectively reduce future risks related to lake outburst floods.

  4. Risk estimation for future glacier lake outburst floods based on local land-use changes

    Science.gov (United States)

    Nussbaumer, S.; Schaub, Y.; Huggel, C.; Walz, A.

    2014-06-01

    Effects of climate change are particularly strong in high-mountain regions. Most visibly, glaciers are shrinking at a rapid pace, and as a consequence, glacier lakes are forming or growing. At the same time the stability of mountain slopes is reduced by glacier retreat, permafrost thaw and other factors, resulting in an increasing landslide hazard which can potentially impact lakes and therewith trigger far-reaching and devastating outburst floods. To manage risks from existing or future lakes, strategies need to be developed to plan in time for adequate risk reduction measures at a local level. However, methods to assess risks from future lake outbursts are not available and need to be developed to evaluate both future hazard and future damage potential. Here a method is presented to estimate future risks related to glacier lake outbursts for a local site in southern Switzerland (Naters, Valais). To generate two hazard scenarios, glacier shrinkage and lake formation modelling was applied, combined with simple flood modelling and field work. Furthermore, a land-use model was developed to quantify and allocate land-use changes based on local-to-regional storylines and three scenarios of land-use driving forces. Results are conceptualized in a matrix of three land-use and two hazard scenarios for the year 2045, and show the distribution of risk in the community of Naters, including high and very high risk areas. The study underlines the importance of combined risk management strategies focusing on land-use planning, on vulnerability reduction, as well as on structural measures (where necessary) to effectively reduce future risks related to lake outburst floods.

  5. On Assessment and Estimation of Potential Losses due to Land Subsidence in Urban Areas of Indonesia

    Science.gov (United States)

    Abidin, Hasanuddin Z.; Andreas, Heri; Gumilar, Irwan; Sidiq, Teguh P.

    2016-04-01

    subsidence have also relation among each other, the accurate quantification of the potential losses caused by land subsidence in urban areas is not an easy task to accomplish. The direct losses can be easier to estimate than the indirect losses. For example, the direct losses due to land subsidence in Bandung was estimated to be at least 180 Million USD; but the indirect losses is still unknown.

  6. Median nitrate concentrations in groundwater in the New Jersey Highlands Region estimated using regression models and land-surface characteristics

    Science.gov (United States)

    Baker, Ronald J.; Chepiga, Mary M.; Cauller, Stephen J.

    2015-01-01

    Nitrate-concentration data are used in conjunction with land-use and land-cover data to estimate median nitrate concentrations in groundwater underlying the New Jersey (NJ) Highlands Region. Sources of data on nitrate in 19,670 groundwater samples are from the U.S. Geological Survey (USGS) National Water Information System (NWIS) and the NJ Private Well Testing Act (PWTA).

  7. Estimation of ballistic block landing energy during 2014 Mount Ontake eruption

    Science.gov (United States)

    Tsunematsu, Kae; Ishimine, Yasuhiro; Kaneko, Takayuki; Yoshimoto, Mitsuhiro; Fujii, Toshitsugu; Yamaoka, Koshun

    2016-05-01

    The 2014 Mount Ontake eruption started just before noon on September 27, 2014. It killed 58 people, and five are still missing (as of January 1, 2016). The casualties were mainly caused by the impact of ballistic blocks around the summit area. It is necessary to know the magnitude of the block velocity and energy to construct a hazard map of ballistic projectiles and design effective shelters and mountain huts. The ejection velocities of the ballistic projectiles were estimated by comparing the observed distribution of the ballistic impact craters on the ground with simulated distributions of landing positions under various sets of conditions. A three-dimensional numerical multiparticle ballistic model adapted to account for topographic effect was used to estimate the ejection angles. From these simulations, we have obtained an ejection angle of γ = 20° from vertical to horizontal and α = 20° from north to east. With these ejection angle conditions, the ejection speed was estimated to be between 145 and 185 m/s for a previously obtained range of drag coefficients of 0.62-1.01. The order of magnitude of the mean landing energy obtained using our numerical simulation was 104 J.

  8. Estimation of daily minimum land surface air temperature using MODIS data in southern Iran

    Science.gov (United States)

    Didari, Shohreh; Norouzi, Hamidreza; Zand-Parsa, Shahrokh; Khanbilvardi, Reza

    2016-10-01

    Land surface air temperature (LSAT) is a key variable in agricultural, climatological, hydrological, and environmental studies. Many of their processes are affected by LSAT at about 5 cm from the ground surface (LSAT5cm). Most of the previous studies tried to find statistical models to estimate LSAT at 2 m height (LSAT2m) which is considered as a standardized height, and there is not enough study for LSAT5cm estimation models. Accurate measurements of LSAT5cm are generally acquired from meteorological stations, which are sparse in remote areas. Nonetheless, remote sensing data by providing rather extensive spatial coverage can complement the spatiotemporal shortcomings of meteorological stations. The main objective of this study was to find a statistical model from the previous day to accurately estimate spatial daily minimum LSAT5cm, which is very important in agricultural frost, in Fars province in southern Iran. Land surface temperature (LST) data were obtained using the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Aqua and Terra satellites at daytime and nighttime periods with normalized difference vegetation index (NDVI) data. These data along with geometric temperature and elevation information were used in a stepwise linear model to estimate minimum LSAT5cm during 2003-2011. The results revealed that utilization of MODIS Aqua nighttime data of previous day provides the most applicable and accurate model. According to the validation results, the accuracy of the proposed model was suitable during 2012 (root mean square difference (RMSD) = 3.07 °C, {R}_{adj}^2 = 87 %). The model underestimated (overestimated) high (low) minimum LSAT5cm. The accuracy of estimation in the winter time was found to be lower than the other seasons (RMSD = 3.55 °C), and in summer and winter, the errors were larger than in the remaining seasons.

  9. Enhancing Global Land Surface Hydrology Estimates from the NASA MERRA Reanalysis Using Precipitation Observations and Model Parameter Adjustments

    Science.gov (United States)

    Reichle, Rolf; Koster, Randal; DeLannoy, Gabrielle; Forman, Barton; Liu, Qing; Mahanama, Sarith; Toure, Ally

    2011-01-01

    The Modern-Era Retrospective analysis for Research and Applications (MERRA) is a state-of-the-art reanalysis that provides. in addition to atmospheric fields. global estimates of soil moisture, latent heat flux. snow. and runoff for J 979-present. This study introduces a supplemental and improved set of land surface hydrological fields ('MERRA-Land') generated by replaying a revised version of the land component of the MERRA system. Specifically. the MERRA-Land estimates benefit from corrections to the precipitation forcing with the Global Precipitation Climatology Project pentad product (version 2.1) and from revised parameters in the rainfall interception model, changes that effectively correct for known limitations in the MERRA land surface meteorological forcings. The skill (defined as the correlation coefficient of the anomaly time series) in land surface hydrological fields from MERRA and MERRA-Land is assessed here against observations and compared to the skill of the state-of-the-art ERA-Interim reanalysis. MERRA-Land and ERA-Interim root zone soil moisture skills (against in situ observations at 85 US stations) are comparable and significantly greater than that of MERRA. Throughout the northern hemisphere, MERRA and MERRA-Land agree reasonably well with in situ snow depth measurements (from 583 stations) and with snow water equivalent from an independent analysis. Runoff skill (against naturalized stream flow observations from 15 basins in the western US) of MERRA and MERRA-Land is typically higher than that of ERA-Interim. With a few exceptions. the MERRA-Land data appear more accurate than the original MERRA estimates and are thus recommended for those interested in using '\\-tERRA output for land surface hydrological studies.

  10. Enhancing Global Land Surface Hydrology Estimates from the NASA MERRA Reanalysis Using Precipitation Observations and Model Parameter Adjustments

    Science.gov (United States)

    Reichle, Rolf; Koster, Randal; DeLannoy, Gabrielle; Forman, Barton; Liu, Qing; Mahanama, Sarith; Toure, Ally

    2011-01-01

    The Modern-Era Retrospective analysis for Research and Applications (MERRA) is a state-of-the-art reanalysis that provides. in addition to atmospheric fields. global estimates of soil moisture, latent heat flux. snow. and runoff for J 979-present. This study introduces a supplemental and improved set of land surface hydrological fields ('MERRA-Land') generated by replaying a revised version of the land component of the MERRA system. Specifically. the MERRA-Land estimates benefit from corrections to the precipitation forcing with the Global Precipitation Climatology Project pentad product (version 2.1) and from revised parameters in the rainfall interception model, changes that effectively correct for known limitations in the MERRA land surface meteorological forcings. The skill (defined as the correlation coefficient of the anomaly time series) in land surface hydrological fields from MERRA and MERRA-Land is assessed here against observations and compared to the skill of the state-of-the-art ERA-Interim reanalysis. MERRA-Land and ERA-Interim root zone soil moisture skills (against in situ observations at 85 US stations) are comparable and significantly greater than that of MERRA. Throughout the northern hemisphere, MERRA and MERRA-Land agree reasonably well with in situ snow depth measurements (from 583 stations) and with snow water equivalent from an independent analysis. Runoff skill (against naturalized stream flow observations from 15 basins in the western US) of MERRA and MERRA-Land is typically higher than that of ERA-Interim. With a few exceptions. the MERRA-Land data appear more accurate than the original MERRA estimates and are thus recommended for those interested in using '\\-tERRA output for land surface hydrological studies.

  11. Estimating California ecosystem carbon change using process model and land cover disturbance data: 1951-2000

    Science.gov (United States)

    Liu, J.; Vogelmann, J.E.; Zhu, Z.; Key, C.H.; Sleeter, B.M.; Price, D.T.; Chen, J.M.; Cochrane, M.A.; Eidenshink, J.C.; Howard, S.M.; Bliss, N.B.; Jiang, H.

    2011-01-01

    Land use change, natural disturbance, and climate change directly alter ecosystem productivity and carbon stock level. The estimation of ecosystem carbon dynamics depends on the quality of land cover change data and the effectiveness of the ecosystem models that represent the vegetation growth processes and disturbance effects. We used the Integrated Biosphere Simulator (IBIS) and a set of 30- to 60-m resolution fire and land cover change data to examine the carbon changes of California's forests, shrublands, and grasslands. Simulation results indicate that during 1951-2000, the net primary productivity (NPP) increased by 7%, from 72.2 to 77.1TgCyr-1 (1 teragram=1012g), mainly due to CO2 fertilization, since the climate hardly changed during this period. Similarly, heterotrophic respiration increased by 5%, from 69.4 to 73.1TgCyr-1, mainly due to increased forest soil carbon and temperature. Net ecosystem production (NEP) was highly variable in the 50-year period but on average equalled 3.0TgCyr-1 (total of 149TgC). As with NEP, the net biome production (NBP) was also highly variable but averaged -0.55TgCyr-1 (total of -27.3TgC) because NBP in the 1980s was very low (-5.34TgCyr-1). During the study period, a total of 126Tg carbon were removed by logging and land use change, and 50Tg carbon were directly removed by wildland fires. For carbon pools, the estimated total living upper canopy (tree) biomass decreased from 928 to 834TgC, and the understory (including shrub and grass) biomass increased from 59 to 63TgC. Soil carbon and dead biomass carbon increased from 1136 to 1197TgC. Our analyses suggest that both natural and human processes have significant influence on the carbon change in California. During 1951-2000, climate interannual variability was the key driving force for the large interannual changes of ecosystem carbon source and sink at the state level, while logging and fire were the dominant driving forces for carbon balances in several specific

  12. Estimation of Land Surface Energy Balance Using Satellite Data of Spatial Reduced Resolution

    Science.gov (United States)

    Vintila, Ruxandra; Radnea, Cristina; Savin, Elena; Poenaru, Violeta

    2010-12-01

    The paper presents preliminary results concerning the monitoring at national level of several geo-biophysical variables retrieved by remote sensing, in particular those related to drought or aridisation. The study, which is in progress, represents also an exercise for to the implementation of a Land Monitoring Core Service for Romania, according to the Kopernikus Program and in compliance with the INSPIRE Directive. The SEBS model has been used to retrieve land surface energy balance variables, such as turbulent heat fluxes, evaporative fraction and daily evaporation, based on three information types: (1) surface albedo, emissivity, temperature, fraction of vegetation cover (fCover), leaf area index (LAI) and vegetation height; (2) air pressure, temperature, humidity and wind speed at the planetary boundary layer (PBL) height; (3) downward solar radiation and downward longwave radiation. AATSR and MERIS archived reprocessed images have provided several types of information. Thus, surface albedo, emissivity, and land surface temperature have been retrieved from AATSR, while LAI and fCover have been estimated from MERIS. The vegetation height has been derived from CORINE Land Cover and PELCOM Land Use databases, while the meteorological information at the height of PBL have been estimated from the measurements provided by the national weather station network. Other sources of data used during this study have been the GETASSE30 digital elevation model with 30" spatial resolution, used for satellite image orthorectification, and the SIGSTAR-200 geographical information system of soil resources of Romania, used for water deficit characterisation. The study will continue by processing other AATSR and MERIS archived images, complemented by the validation of SEBS results with ground data collected on the most important biomes for Romania at various phenological stages, and the transformation of evaporation / evapotranspiration into a drought index using the soil texture

  13. Hover performance estimation and validation of battery powered vertical takeoff and landing aircraft

    Institute of Scientific and Technical Information of China (English)

    王波; 侯中喜; 鲁亚飞; 朱雄峰

    2016-01-01

    Battery powered vertical takeoff and landing (VTOL) aircraft attracts more and more interests from public, while limited hover endurance hinders many prospective applications. Based on the weight models of battery, motor and electronic speed controller, the power consumption model of propeller and the constant power discharge model of battery, an efficient method to estimate the hover endurance of battery powered VTOL aircraft was presented. In order to understand the mechanism of performance improvement, the impacts of propulsion system parameters on hover endurance were analyzed by simulations, including the motor power density, the battery capacity, specific energy and Peukert coefficient. Ground experiment platform was established and validation experiments were carried out, the results of which showed a well agreement with the simulations. The estimation method and the analysis results could be used for optimization design and hover performance evaluation of battery powered VTOL aircraft.

  14. High spatial resolution Land Surface Temperature estimation over urban areas with uncertainty indices

    Science.gov (United States)

    Mitraka, Zina; Lazzarini, Michele; Doxani, Georgia; Del Frate, Fabio; Ghedira, Hosni

    2014-05-01

    Land Surface Temperature (LST) is a key variable for studying land surface processes and interactions with the atmosphere and it is listed in the Earth System Data Records (ESDRs) identified by international organizations like Global Climate Observing System. It is a valuable source of information for a range of topics in earth sciences and essential for urban climatology studies. Detailed, frequent and accurate LST mapping may support various urban applications, like the monitoring of urban heat island. Currently, no spaceborne instruments provide frequent thermal imagery at high spatial resolution, thus there is a need for synergistic algorithms that combine different kinds of data for LST retrieval. Moreover, knowing the confidence level of any satellite-derived product is highly important to the users, especially when referred to the urban environment, which is extremely heterogenic. The developed method employs spatial-spectral unmixing techniques for improving the spatial resolution of thermal measurements, combines spectral library information for emissivity estimation and applies a split-window algorithm to estimate LST with an uncertainty estimation inserted in the final product. A synergistic algorithm that utilizes the spatial information provided by visible and near-infrared measurements with more frequent low resolution thermal measurements provides excellent means for high spatial resolution LST estimation. Given the low spatial resolution of thermal infrared sensors, the measured radiation is a combination of radiances of different surface types. High spatial resolution information is used to quantify the different surface types in each pixel and then the measured radiance of each pixel is decomposed. The several difficulties in retrieving LST from space measurements, mainly related to the temperature-emissivity coupling and the atmospheric contribution to the thermal measurements, and the measurements themselves, introduce uncertainties in the final

  15. Estimation and Modelling of Land Surface Temperature Using Landsat 7 ETM+ Images and Fuzzy System Techniques

    Science.gov (United States)

    Bisht, K.; Dodamani, S. S.

    2016-12-01

    Modelling of Land Surface Temperature is essential for short term and long term management of environmental studies and management activities of the Earth's resources. The objective of this research is to estimate and model Land Surface Temperatures (LST). For this purpose, Landsat 7 ETM+ images period from 2007 to 2012 were used for retrieving LST and processed through MATLAB software using Mamdani fuzzy inference systems (MFIS), which includes pre-monsoon and post-monsoon LST in the fuzzy model. The Mangalore City of Karnataka state, India has been taken for this research work. Fuzzy model inputs are considered as the pre-monsoon and post-monsoon retrieved temperatures and LST was chosen as output. In order to develop a fuzzy model for LST, seven fuzzy subsets, nineteen rules and one output are considered for the estimation of weekly mean air temperature. These are very low (VL), low (L), medium low (ML), medium (M), medium high (MH), high (H) and very high (VH). The TVX (Surface Temperature Vegetation Index) and the empirical method have provided estimated LST. The study showed that the Fuzzy model M4/7-19-1 (model 4, 7 fuzzy sets, 19 rules and 1 output) which developed over Mangalore City has provided more accurate outcomes than other models (M1, M2, M3, M5). The result of this research was evaluated according to statistical rules. The best correlation coefficient (R) and root mean squared error (RMSE) between estimated and measured values for pre-monsoon and post-monsoon LST found to be 0.966 - 1.607 K and 0.963- 1.623 respectively.

  16. Land ECVs from QA4ECV using an optimal estimation framework

    Science.gov (United States)

    Muller, Jan-Peter; Kharbouche, Said; Lewis, Philip; Danne, Olaf; Blessing, Simon; Giering, Ralf; Gobron, Nadine; Lanconelli, Christian; Govaerts, Yves; Schulz, Joerg; Doutriaux-Boucher, Marie; Lattanzio, Alessio; Aoun, Youva

    2017-04-01

    In the ESA-DUE GlobAlbedo project (http://www.GlobAlbedo.org), a 15 year record of land surface albedo was generated from the European VEGETATION & MERIS sensors using optimal estimation. This was based on 3 broadbands (0.4-0.7, 0.7-3, 0.4-3µm) and fused data at level-2 after converting from spectral narrowband to these 3 broadbands with surface BRFs. A 10 year long record of land surface albedo climatology was generated from Collection 5 of the MODIS BRDF product for these same broadbands. This was employed as an a priori estimate for an optimal estimation based retrieval of land surface albedo when there were insufficient samples from the European sensors. This so-called MODIS prior was derived at 1km from the 500m MOD43A1,2 BRDF inputs every 8 days using the QA bits and the method described in the GlobAlbedo ATBD which is available from the website (http://www.globalbedo.org/docs/GlobAlbedo_Albedo_ATBD_V4.12.pdf). In the ESA-STSE WACMOS-ET project, FastOpt generated fapar & LAI based on this GlobAlbedo BRDF with associated per pixel uncertainty using the TIP framework. In the successor EU-FP7-QA4ECV* project, we have developed a 33 year record (1981-2014) of Earth surface spectral and broadband albedo (i.e. including the ocean and sea-ice) using optimal estimation for the land and where available, relevant sensors for "instantaneous" retrievals over the poles (Kharbouche & Muller, this conference). This requires the longest possible land surface spectral and broadband BRDF record that can only be supplied by a 16 year of MODIS Collection 6 BRDFs at 500m but produced on a daily basis. The CEMS Big Data computer at RAL was used to generate 7 spectral bands and 3 broadband BRDF with and without snow and snow_only. We will discuss the progress made since the start of the QA4ECV project on the production of a new fused land surface BRDF/albedo spectral and broadband CDR product based on four European sensors: MERIS, (A)ATSR(2), VEGETATION, PROBA-V and two US sensors

  17. Intra-Articular Knee Contact Force Estimation During Walking Using Force-Reaction Elements and Subject-Specific Joint Model.

    Science.gov (United States)

    Jung, Yihwan; Phan, Cong-Bo; Koo, Seungbum

    2016-02-01

    Joint contact forces measured with instrumented knee implants have not only revealed general patterns of joint loading but also showed individual variations that could be due to differences in anatomy and joint kinematics. Musculoskeletal human models for dynamic simulation have been utilized to understand body kinetics including joint moments, muscle tension, and knee contact forces. The objectives of this study were to develop a knee contact model which can predict knee contact forces using an inverse dynamics-based optimization solver and to investigate the effect of joint constraints on knee contact force prediction. A knee contact model was developed to include 32 reaction force elements on the surface of a tibial insert of a total knee replacement (TKR), which was embedded in a full-body musculoskeletal model. Various external measurements including motion data and external force data during walking trials of a subject with an instrumented knee implant were provided from the Sixth Grand Challenge Competition to Predict in vivo Knee Loads. Knee contact forces in the medial and lateral portions of the instrumented knee implant were also provided for the same walking trials. A knee contact model with a hinge joint and normal alignment could predict knee contact forces with root mean square errors (RMSEs) of 165 N and 288 N for the medial and lateral portions of the knee, respectively, and coefficients of determination (R2) of 0.70 and -0.63. When the degrees-of-freedom (DOF) of the knee and locations of leg markers were adjusted to account for the valgus lower-limb alignment of the subject, RMSE values improved to 144 N and 179 N, and R2 values improved to 0.77 and 0.37, respectively. The proposed knee contact model with subject-specific joint model could predict in vivo knee contact forces with reasonable accuracy. This model may contribute to the development and improvement of knee arthroplasty.

  18. Estimation of Land Surface Temperature for the Quantitative Analysis of Land Cover of Lower Areas of Sindh to Assess the Impacts of Climate Variability

    Science.gov (United States)

    Qaisar, Maha

    2016-07-01

    Due to the present land use practices and climate variability, drastic shifts in regional climate and land covers are easily seen and their future reduction and gain are too well predicted. Therefore, there is an increasing need for data on land-cover changes at narrow and broad spatial scales. In this study, a remote sensing-based technique for land-cover-change analysis is applied to the lower Sindh areas for the last decade. Landsat satellite products were analyzed on an alternate yearly basis, from 1990 to 2016. Then Land-cover-change magnitudes were measured and mapped for alternate years. Land Surface Temperature (LST) is one of the critical elements in the natural phenomena of surface energy and water balance at local and global extent. However, LST was computed by using Landsat thermal bands via brightness temperature and a vegetation index. Normalized difference vegetation index (NDVI) was interpreted and maps were achieved. LST reflected NDVI patterns with complexity of vegetation patterns. Along with this, Object Based Image Analysis (OBIA) was done for classifying 5 major classes of water, vegetation, urban, marshy lands and barren lands with significant map layouts. Pakistan Meteorological Department provided the climate data in which rainfall, temperature and air temperature are included. Once the LST and OBIA are performed, overlay analysis was done to correlate the results of LST with OBIA and LST with meteorological data to ascertain the changes in land covers due to increasing centigrade of LST. However, satellite derived LST was also correlated with climate data for environmental analysis and to estimate Land Surface Temperature for assessing the inverse impacts of climate variability. This study's results demonstrate the land-cover changes in Lower Areas of Sindh including the Indus Delta mostly involve variations in land-cover conditions due to inter-annual climatic variability and temporary shifts in seasonality. However it is too concluded

  19. A call for caution and transparency in the calculation of land use mix: measurement bias in the estimation of associations between land use mix and physical activity.

    Science.gov (United States)

    Hajna, Samantha; Dasgupta, Kaberi; Joseph, Lawrence; Ross, Nancy A

    2014-09-01

    There is evidence that land use mix based on the Shannon (1948) entropy formula may be misspecified in some studies. The aim of this study was to quantify the bias arising from this misspecification. Spatial coordinates were obtained from Statistics Canada for 9348 unique point locations. Five hundred-metre polygon-based network buffers were drawn around each coordinate (ArcGIS 10.1). Land use mix was calculated for each buffer using the true and misspecified land use mix formulas. Linear regression models were used to estimate the associations between a simulated dataset of daily steps and the true and misspecified measures. Misspecification of the land use mix formula resulted in a systematic underestimation of the true association by 26.4% (95% CI 25.8-27.0%). To minimize measurement bias in future studies, researchers are encouraged to use a constant definition of N in the denominator of the Shannon entropy formula.

  20. Artificial neural network model for estimating the soil respiration under different land uses

    Science.gov (United States)

    Ebrahimi, Mitra; Sarikhani, Mohammad Reza; Safari Sinegani, Ali Akbar; Ahmadi, Abbas; Keesstra, Saskia

    2017-04-01

    Soil respiration is a biological process in microbes that convert organic carbon to atmospheric CO2. This process is considered to be one of the largest global carbon fluxes and is affected by different physicochemical and biological properties of soil, land usageuse, vegetation types and climate patterns. The aim of this study was to estimate the soil basal (BR) and substrate induced respiration (SIR) of 150 data obtained from soil samples collected from depth (0-25 cm) under different land uses by Artificial Neural Network. Soil samples were chosen from three provinces of Iran, with humid subtropical and semi-arid climate patterns. In each soil sample, soil texture, pH, electrical conductivity (EC), calcium carbonate equivalent (CCE), organic carbon (OC), OC fractionation data e.g. light fraction OC (LOC), heavy fraction OC (HOC), cold water extractable OC (COC) and warm water extractable OC (WOC), population of fungi, bacteria and actinomycete, BR and SIR were measured. Our goal was to use the most efficient ANN-model to predict soil respiration with simple soil data. Our results indicated that in an ANN model containing all the measured parameters, the R2 and RMSE values for BR prediction were 0.64 and 0.047 while these statistical indicators for SIR obtained 0.58 and 0.15, respectively. The R2 and RMSE values of the BR-ANN and SIR-ANN predicted models comprising 7 variables (including OC, pH, EC, CCE and soil texture) were estimated at 0.66, 0.043 and 0.52, 0.16, respectively. It was concluded that ANN modeling is a reliable method for predicting soil respiration. KEYWORDS: Artificial neural network; Land use; Soil physicochemical properties; Soil respiration; Soil microorganism

  1. Estimating maximum global land surface wind power extractability and associated climatic consequences

    Directory of Open Access Journals (Sweden)

    L. M. Miller

    2011-02-01

    Full Text Available The availability of wind power for renewable energy extraction is ultimately limited by how much kinetic energy is generated by natural processes within the Earth system and by fundamental limits of how much of the wind power can be extracted. Here we use these considerations to provide a maximum estimate of wind power availability over land. We use several different methods. First, we outline the processes associated with wind power generation and extraction with a simple power transfer hierarchy based on the assumption that available wind power will not geographically vary with increased extraction for an estimate of 68 TW. Second, we set up a simple momentum balance model to estimate maximum extractability which we then apply to reanalysis climate data, yielding an estimate of 21 TW. Third, we perform general circulation model simulations in which we extract different amounts of momentum from the atmospheric boundary layer to obtain a maximum estimate of how much power can be extracted, yielding 18–34 TW. These three methods consistently yield maximum estimates in the range of 18–68 TW and are notably less than recent estimates that claim abundant wind power availability. Furthermore, we show with the general circulation model simulations that some climatic effects at maximum wind power extraction are similar in magnitude to those associated with a doubling of atmospheric CO2. We conclude that in order to understand fundamental limits to renewable energy resources, as well as the impacts of their utilization, it is imperative to use a "top-down" thermodynamic Earth system perspective, rather than the more common "bottom-up" engineering approach.

  2. Estimation of spatial-temporal gait parameters in level walking based on a single accelerometer: validation on normal subjects by standard gait analysis.

    Science.gov (United States)

    Bugané, F; Benedetti, M G; Casadio, G; Attala, S; Biagi, F; Manca, M; Leardini, A

    2012-10-01

    This paper investigates the ability of a single wireless inertial sensing device stuck on the lower trunk to provide spatial-temporal parameters during level walking. The 3-axial acceleration signals were filtered and the timing of the main gait events identified. Twenty-two healthy subjects were analyzed with this system for validation, and the estimated parameters were compared with those obtained with state-of-the-art gait analysis, i.e. stereophotogrammetry and dynamometry. For each side, from four to six gait cycles were measured with the device, of which two were validated by gait analysis. The new acquisition system is easy to use and does not interfere with regular walking. No statistically significant differences were found between the acceleration-based measurements and the corresponding ones from gait analysis for most of the spatial-temporal parameters, i.e. stride length, stride duration, cadence and speed, etc.; significant differences were found for the gait cycle phases, i.e. single and double support duration, etc. The system therefore shows promise also for a future routine clinical use.

  3. Land

    CSIR Research Space (South Africa)

    Audouin, M

    2007-01-01

    Full Text Available Unsustainable agricultural practices have had a role to play in the degradation of land on which agriculture depends. South Africa has an international obligation to develop a National Action Programme (NAP), the purpose of which is to identify...

  4. Developing first time-series of land surface temperature from AATSR with uncertainty estimates

    Science.gov (United States)

    Ghent, Darren; Remedios, John

    2013-04-01

    Land surface temperature (LST) is the radiative skin temperature of the land, and is one of the key parameters in the physics of land-surface processes on regional and global scales. Earth Observation satellites provide the opportunity to obtain global coverage of LST approximately every 3 days or less. One such source of satellite retrieved LST has been the Advanced Along-Track Scanning Radiometer (AATSR); with LST retrieval being implemented in the AATSR Instrument Processing Facility in March 2004. Here we present first regional and global time-series of LST data from AATSR with estimates of uncertainty. Mean changes in temperature over the last decade will be discussed along with regional patterns. Although time-series across all three ATSR missions have previously been constructed (Kogler et al., 2012), the use of low resolution auxiliary data in the retrieval algorithm and non-optimal cloud masking resulted in time-series artefacts. As such, considerable ESA supported development has been carried out on the AATSR data to address these concerns. This includes the integration of high resolution auxiliary data into the retrieval algorithm and subsequent generation of coefficients and tuning parameters, plus the development of an improved cloud mask based on the simulation of clear sky conditions from radiance transfer modelling (Ghent et al., in prep.). Any inference on this LST record is though of limited value without the accompaniment of an uncertainty estimate; wherein the Joint Committee for Guides in Metrology quote an uncertainty as "a parameter associated with the result of a measurement that characterizes the dispersion of the values that could reasonably be attributed to the measurand that is the value of the particular quantity to be measured". Furthermore, pixel level uncertainty fields are a mandatory requirement in the on-going preparation of the LST product for the upcoming Sea and Land Surface Temperature (SLSTR) instrument on-board Sentinel-3

  5. Walking Problems

    Science.gov (United States)

    ... your legs or feet Movement disorders such as Parkinson's disease Diseases such as arthritis or multiple sclerosis Vision or balance problems Treatment of walking problems depends on the cause. Physical therapy, surgery, or mobility aids may help.

  6. Estimation of Phase Delay due to Precipitable Water for Dinsarbased Land Deformation Monitoring

    Science.gov (United States)

    Susaki, J.; Maeda, N.; Akatsuka, S.

    2017-09-01

    In this paper, we present a method for using the estimated precipitable water (PW) to mitigate atmospheric phase delay in order to improve the accuracy of land-deformation assessment with differential interferometric synthetic aperture radar (DInSAR). The phase difference obtained from multi-temporal synthetic aperture radar images contains errors of several types, and the atmospheric phase delay can be an obstacle to estimating surface subsidence. In this study, we calculate PW from external meteorological data. Firstly, we interpolate the data with regard to their spatial and temporal resolutions. Then, assuming a range direction between a target pixel and the sensor, we derive the cumulative amount of differential PW at the height of the slant range vector at pixels along that direction. The atmospheric phase delay of each interferogram is acquired by taking a residual after a preliminary determination of the linear deformation velocity and digital elevation model (DEM) error, and by applying high-pass temporal and low-pass spatial filters. Next, we estimate a regression model that connects the cumulative amount of PW and the atmospheric phase delay. Finally, we subtract the contribution of the atmospheric phase delay from the phase difference of the interferogram, and determine the linear deformation velocity and DEM error. The experimental results show a consistent relationship between the cumulative amount of differential PW and the atmospheric phase delay. An improvement in land-deformation accuracy is observed at a point at which the deformation is relatively large. Although further investigation is necessary, we conclude at this stage that the proposed approach has the potential to improve the accuracy of the DInSAR technique.

  7. ESTIMATION OF PHASE DELAY DUE TO PRECIPITABLE WATER FOR DINSARBASED LAND DEFORMATION MONITORING

    Directory of Open Access Journals (Sweden)

    J. Susaki

    2017-09-01

    Full Text Available In this paper, we present a method for using the estimated precipitable water (PW to mitigate atmospheric phase delay in order to improve the accuracy of land-deformation assessment with differential interferometric synthetic aperture radar (DInSAR. The phase difference obtained from multi-temporal synthetic aperture radar images contains errors of several types, and the atmospheric phase delay can be an obstacle to estimating surface subsidence. In this study, we calculate PW from external meteorological data. Firstly, we interpolate the data with regard to their spatial and temporal resolutions. Then, assuming a range direction between a target pixel and the sensor, we derive the cumulative amount of differential PW at the height of the slant range vector at pixels along that direction. The atmospheric phase delay of each interferogram is acquired by taking a residual after a preliminary determination of the linear deformation velocity and digital elevation model (DEM error, and by applying high-pass temporal and low-pass spatial filters. Next, we estimate a regression model that connects the cumulative amount of PW and the atmospheric phase delay. Finally, we subtract the contribution of the atmospheric phase delay from the phase difference of the interferogram, and determine the linear deformation velocity and DEM error. The experimental results show a consistent relationship between the cumulative amount of differential PW and the atmospheric phase delay. An improvement in land-deformation accuracy is observed at a point at which the deformation is relatively large. Although further investigation is necessary, we conclude at this stage that the proposed approach has the potential to improve the accuracy of the DInSAR technique.

  8. A spatial resolution threshold of land cover in estimating terrestrial carbon sequestration in four counties in Georgia and Alabama, USA

    Science.gov (United States)

    Zhao, S.Q.; Liu, S.; Li, Z.; Sohl, T.L.

    2010-01-01

    Changes in carbon density (i.e., carbon stock per unit area) and land cover greatly affect carbon sequestration. Previous studies have shown that land cover change detection strongly depends on spatial scale. However, the influence of the spatial resolution of land cover change information on the estimated terrestrial carbon sequestration is not known. Here, we quantified and evaluated the impact of land cover change databases at various spatial resolutions (250 m, 500 m, 1 km, 2 km, and 4 km) on the magnitude and spatial patterns of regional carbon sequestration in four counties in Georgia and Alabama using the General Ensemble biogeochemical Modeling System (GEMS). Results indicated a threshold of 1 km in the land cover change databases and in the estimated regional terrestrial carbon sequestration. Beyond this threshold, significant biases occurred in the estimation of terrestrial carbon sequestration, its interannual variability, and spatial patterns. In addition, the overriding impact of interannual climate variability on the temporal change of regional carbon sequestration was unrealistically overshadowed by the impact of land cover change beyond the threshold. The implications of these findings directly challenge current continental- to global-scale carbon modeling efforts relying on information at coarse spatial resolution without incorporating fine-scale land cover dynamics.

  9. Estimating vegetation vulnerability to detect areas prone to land degradation in the Mediterranean basin

    Science.gov (United States)

    Imbrenda, Vito; Coluzzi, Rosa; D'Emilio, Mariagrazia; Lanfredi, Maria; Simoniello, Tiziana

    2013-04-01

    Vegetation is one of the key components to study land degradation vulnerability because of the complex interactions and feedbacks that link it to soil. In the Mediterranean region, degradation phenomena are due to a mix of predisposing factors (thin soil horizons, low soil organic matter, increasing aridity, etc.) and bad management practices (overgrazing, deforestation, intensification of agriculture, tourism development). In particular, in areas threatened by degradation processes but still covered by vegetation, large scale soil condition evaluation is a hard task and the detection of stressed vegetation can be useful to identify on-going soil degradation phenomena and to reduce their impacts through interventions for recovery/rehabilitation. In this context the use of satellite time series can increase the efficacy and completeness of the land degradation assessment, providing precious information to understand vegetation dynamics. In order to estimate vulnerability levels in Basilicata (a Mediterranean region of Southern Italy) in the framework of PRO-LAND project (PO-FESR Basilicata 2007-2013), we crossed information on potential vegetation vulnerability with information on photosynthetic activity dynamics. Potential vegetation vulnerability represents the vulnerability related to the type of present cover in terms of fire risk, erosion protection, drought resistance and plant cover distribution. It was derived from an updated land cover map by separately analyzing each factor, and then by combining them to obtain concise information on the possible degradation exposure. The analysis of photosynthetic activity dynamics provides information on the status of vegetation, that is fundamental to discriminate the different vulnerability levels within the same land cover, i.e. the same potential vulnerability. For such a purpose, we analyzed a time series (2000-2010) of a satellite vegetation index (MODIS NDVI) with 250m resolution, available as 16-day composite

  10. Estimating spatially distributed monthly evapotranspiration rates by linear transformations of MODIS daytime land surface temperature data

    Directory of Open Access Journals (Sweden)

    J. Szilagyi

    2009-05-01

    Full Text Available Under simplifying conditions catchment-scale vapor pressure at the drying land surface can be calculated as a function of its watershed-representative temperature (<Ts> by the wet-surface equation (WSE, similar to the wet-bulb equation in meteorology for calculating the dry-bulb thermometer vapor pressure of the Complementary Relationship of evaporation. The corresponding watershed ET rate, , is obtained from the Bowen ratio with the help of air temperature, humidity and percent possible sunshine data. The resulting (<Ts>, pair together with the wet-environment surface temperature (<Tws> and ET rate (ETw, obtained by the Priestley-Taylor equation, define a linear transformation on a monthly basis by which spatially distributed ET rates can be estimated as a sole function of MODIS daytime land surface temperature, Ts, values within the watershed. The linear transformation preserves the mean which is highly desirable. <Tws>, in the lack of significant open water surfaces within the study watershed (Elkhorn, Nebraska, was obtained as the mean of the smallest MODIS Ts values each month. The resulting period-averaged (2000–2007 catchment-scale ET rate of 624 mm/yr is very close to the water-balance derived ET rate of about 617 mm/yr. The latter is a somewhat uncertain value due to the effects of (a observed groundwater depletion of about 1m over the study period caused by extensive irrigation, and; (b the uncertain rate of net regional groundwater supply toward the watershed. The spatially distributed ET rates correspond well with soil/aquifer properties and the resulting land use type (i.e. rangeland versus center-pivot irrigated crops.

  11. Estimation of Variability Characteristics of Regional Drought during 1964–2013 in Horqin Sandy Land, China

    Directory of Open Access Journals (Sweden)

    Yongfang Wang

    2016-11-01

    Full Text Available Drought has an important influence on the hydrological cycle, ecological system, industrial and agricultural production, and social life. Based on the different time scales of characteristics of drought variability, the standardized precipitation evapotranspiration index (SPEI, a multi-timescale index with consideration of evaporation, was used in this study to estimate the spatial and temporal variability characteristics of drought. Climatic data from 15 meteorological stations across Horqin Sandy Land during 1964–2013 were used to calculate the SPEI of 1, 3, 6, and 12 months. In order to examine the relationship between droughts and other variables, 10 extreme climate indices were calculated based on the daily precipitation and maximum/mean/minimum temperature data of 15 meteorological stations, and linkages between SPEI-12 and atmosphere indices were established using by the cross wavelet transform method. The results indicated that the climate of Horqin Sandy Land had a tendency towards drought conditions, which is particularly apparent from the year 2000 onwards. During the study period, drought events were frequent in the region. Mild drought occurred in a quarter of the month, with that of moderate, severe, and extreme drought accounting for 0.11, 0.05, and 0.02 of the total months. The spatial trend of multi-timescale drought revealed that there was an increase in the severity of drought throughout Horqin Sandy Land, among which the magnitude in southern parts was larger than that of northern parts. The results also showed that the short time scale drought negatively correlated with precipitation extremes and positively correlated with temperature extremes. Furthermore, the long time scale drought (SPEI-12 was associated with atmosphere indices. Significant resonance periods were found between El Nino southern oscillation (ENSO, the East Asian summer monsoon index (EASMI, and SPEI-12.

  12. Integrating address geocoding, land use regression, and spatiotemporal geostatistical estimation for groundwater tetrachloroethylene.

    Science.gov (United States)

    Messier, Kyle P; Akita, Yasuyuki; Serre, Marc L

    2012-03-06

    Geographic information systems (GIS) based techniques are cost-effective and efficient methods used by state agencies and epidemiology researchers for estimating concentration and exposure. However, budget limitations have made statewide assessments of contamination difficult, especially in groundwater media. Many studies have implemented address geocoding, land use regression, and geostatistics independently, but this is the first to examine the benefits of integrating these GIS techniques to address the need of statewide exposure assessments. A novel framework for concentration exposure is introduced that integrates address geocoding, land use regression (LUR), below detect data modeling, and Bayesian Maximum Entropy (BME). A LUR model was developed for tetrachloroethylene that accounts for point sources and flow direction. We then integrate the LUR model into the BME method as a mean trend while also modeling below detects data as a truncated Gaussian probability distribution function. We increase available PCE data 4.7 times from previously available databases through multistage geocoding. The LUR model shows significant influence of dry cleaners at short ranges. The integration of the LUR model as mean trend in BME results in a 7.5% decrease in cross validation mean square error compared to BME with a constant mean trend.

  13. A land use regression model for estimating the NO2 concentration in Shanghai, China.

    Science.gov (United States)

    Meng, Xia; Chen, Li; Cai, Jing; Zou, Bin; Wu, Chang-Fu; Fu, Qingyan; Zhang, Yan; Liu, Yang; Kan, Haidong

    2015-02-01

    Limited by data accessibility, few exposure assessment studies of air pollutants have been conducted in China. There is an urgent need to develop models for assessing the intra-urban concentration of key air pollutants in Chinese cities. In this study, a land use regression (LUR) model was established to estimate NO2 during 2008-2011 in Shanghai. Four predictor variables were left in the final LUR model: the length of major road within the 2-km buffer around monitoring sites, the number of industrial sources (excluding power plants) within a 10-km buffer, the agricultural land area within a 5-km buffer, and the population counts. The model R(2) and the leave-one-out-cross-validation (LOOCV) R(2) of the NO2 LUR models were 0.82 and 0.75, respectively. The prediction surface of the NO2 concentration based on the LUR model was of high spatial resolution. The 1-year predicted concentration based on the ratio and the difference methods fitted well with the measured NO2 concentration. The LUR model of NO2 outperformed the kriging and inverse distance weighed (IDW) interpolation methods in Shanghai. Our findings suggest that the LUR model may provide a cost-effective method of air pollution exposure assessment in a developing country.

  14. A Comparison of Land Surface Model Soil Hydraulic Properties Estimated by Inverse Modeling and Pedotransfer Functions

    Science.gov (United States)

    Gutmann, Ethan D.; Small, Eric E.

    2007-01-01

    Soil hydraulic properties (SHPs) regulate the movement of water in the soil. This in turn plays an important role in the water and energy cycles at the land surface. At present, SHPS are commonly defined by a simple pedotransfer function from soil texture class, but SHPs vary more within a texture class than between classes. To examine the impact of using soil texture class to predict SHPS, we run the Noah land surface model for a wide variety of measured SHPs. We find that across a range of vegetation cover (5 - 80% cover) and climates (250 - 900 mm mean annual precipitation), soil texture class only explains 5% of the variance expected from the real distribution of SHPs. We then show that modifying SHPs can drastically improve model performance. We compare two methods of estimating SHPs: (1) inverse method, and (2) soil texture class. Compared to texture class, inverse modeling reduces errors between measured and modeled latent heat flux from 88 to 28 w/m(exp 2). Additionally we find that with increasing vegetation cover the importance of SHPs decreases and that the van Genuchten m parameter becomes less important, while the saturated conductivity becomes more important.

  15. Estimating uncertainties in the newly developed multi-source land snow data assimilation system

    Science.gov (United States)

    Zhang, Yong-Fei; Yang, Zong-Liang

    2016-07-01

    The snow simulations from the recently developed multivariate land snow data assimilation system (SNODAS) for the Northern Hemisphere are assessed with regard to uncertainties in atmospheric forcing, model structure, data assimilation technique, and satellite remote sensing product. The SNODAS consists of the Data Assimilation Research Testbed (DART) and the Community Land Model version 4 (CLM4). A series of experiments are conducted to estimate each of the above uncertainty sources. The experiments include several open-loop model cases and data assimilation cases that assimilate the snow cover fraction (SCF) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the terrestrial water storage (TWS) from the Gravity Recovery and Climate Experiment (GRACE). The atmospheric forcing uncertainty in terms of precipitation and radiation is found to be the largest among the various uncertainty sources examined, especially over the Tibetan Plateau (TP) and most of the mid- and high-latitudes. Model structure and choice of data assimilation technique are also two big sources of uncertainty in SNODAS. The uncertainty of model structure is represented by two different parameterizations of SCF. The density-based SCF scheme (as used in CLM4) generally results in better snow simulations than does the stochastic SCF scheme (as in CLM4.5) within the data assimilation framework. The choice of TWS products retrieved from GRACE has relatively the least impact on the snow data assimilation.

  16. Estimation of land surface evapotranspiration with A satellite remote sensing procedure

    Science.gov (United States)

    Irmak, A.; Ratcliffe, I.; Ranade, P.; Hubbard, K.G.; Singh, R.K.; Kamble, B.; Kjaersgaard, J.

    2011-01-01

    There are various methods available for estimating magnitude and trends of evapotranspiration. Bowen ratio energy balance system and eddy correlation techniques offer powerful alternatives for measuring land surface evapotranspiration. In spite of the elegance, high accuracy, and theoretical attractions of these techniques for measuring evapotranspiration, their practical use over large areas can be limited due to the number of sites needed and the related expense. Application of evapotranspiration mapping from satellite measurements can overcome the limitations. The objective of this study was to utilize the METRICTM (Mapping Evapotranspiration at High Resolution using Internalized Calibration) model in Great Plains environmental settings to understand water use in managed ecosystems on a regional scale. We investigated spatiotemporal distribution of a fraction of reference evapotranspiration (ETrF) using eight Landsat 5 images during the 2005 and 2006 growing season for path 29, row 32. The ETrF maps generated by METRICTM allowed us to follow the magnitude and trend in ETrF for major land-use classes during the growing season. The ETrF was lower early in the growing season for agricultural crops and gradually increased as the normalized difference vegetation index of crops increased, thus presenting more surface area over which water could transpire toward the midseason. Comparison of predictions with Bowen ratio energy balance system measurements at Clay Center, NE, showed that METRICTM performed well at the field scale for predicting evapotranspiration from a cornfield. If calibrated properly, the model could be a viable tool to estimate water use in managed ecosystems in subhumid climates at a large scale.

  17. Assessment of model estimates of land-atmosphere CO2 exchange across Northern Eurasia

    Science.gov (United States)

    Rawlins, M. A.; McGuire, A. D.; Kimball, J. S.; Dass, P.; Lawrence, D.; Burke, E.; Chen, X.; Delire, C.; Koven, C.; MacDougall, A.; Peng, S.; Rinke, A.; Saito, K.; Zhang, W.; Alkama, R.; Bohn, T. J.; Ciais, P.; Decharme, B.; Gouttevin, I.; Hajima, T.; Ji, D.; Krinner, G.; Lettenmaier, D. P.; Miller, P.; Moore, J. C.; Smith, B.; Sueyoshi, T.

    2015-07-01

    A warming climate is altering land-atmosphere exchanges of carbon, with a potential for increased vegetation productivity as well as the mobilization of permafrost soil carbon stores. Here we investigate land-atmosphere carbon dioxide (CO2) cycling through analysis of net ecosystem productivity (NEP) and its component fluxes of gross primary productivity (GPP) and ecosystem respiration (ER) and soil carbon residence time, simulated by a set of land surface models (LSMs) over a region spanning the drainage basin of Northern Eurasia. The retrospective simulations cover the period 1960-2009 at 0.5° resolution, which is a scale common among many global carbon and climate model simulations. Model performance benchmarks were drawn from comparisons against both observed CO2 fluxes derived from site-based eddy covariance measurements as well as regional-scale GPP estimates based on satellite remote-sensing data. The site-based comparisons depict a tendency for overestimates in GPP and ER for several of the models, particularly at the two sites to the south. For several models the spatial pattern in GPP explains less than half the variance in the MODIS MOD17 GPP product. Across the models NEP increases by as little as 0.01 to as much as 0.79 g C m-2 yr-2, equivalent to 3 to 340 % of the respective model means, over the analysis period. For the multimodel average the increase is 135 % of the mean from the first to last 10 years of record (1960-1969 vs. 2000-2009), with a weakening CO2 sink over the latter decades. Vegetation net primary productivity increased by 8 to 30 % from the first to last 10 years, contributing to soil carbon storage gains. The range in regional mean NEP among the group is twice the multimodel mean, indicative of the uncertainty in CO2 sink strength. The models simulate that inputs to the soil carbon pool exceeded losses, resulting in a net soil carbon gain amid a decrease in residence time. Our analysis points to improvements in model elements

  18. Assessment of model estimates of land-atmosphere CO2 exchange across northern Eurasia

    Science.gov (United States)

    Rawlins, M.A.; McGuire, A.D.; Kimball, J.S.; Dass, P.; Lawrence, D.; Burke, E.; Chen, X.; Delire, C.; Koven, C.; MacDougall, A.; Peng, S.; Rinke, A.; Saito, K.; Zhang, W.; Alkama, R.; Bohn, T. J.; Ciais, P.; Decharme, B.; Gouttevin, I.; Hajima, T.; Ji, D.; Krinner, G.; Lettenmaier, D.P.; Miller, P.; Moore, J.C.; Smith, B.; Sueyoshi, T.

    2015-01-01

    A warming climate is altering land-atmosphere exchanges of carbon, with a potential for increased vegetation productivity as well as the mobilization of permafrost soil carbon stores. Here we investigate land-atmosphere carbon dioxide (CO2) cycling through analysis of net ecosystem productivity (NEP) and its component fluxes of gross primary productivity (GPP) and ecosystem respiration (ER) and soil carbon residence time, simulated by a set of land surface models (LSMs) over a region spanning the drainage basin of Northern Eurasia. The retrospective simulations cover the period 1960–2009 at 0.5° resolution, which is a scale common among many global carbon and climate model simulations. Model performance benchmarks were drawn from comparisons against both observed CO2 fluxes derived from site-based eddy covariance measurements as well as regional-scale GPP estimates based on satellite remote-sensing data. The site-based comparisons depict a tendency for overestimates in GPP and ER for several of the models, particularly at the two sites to the south. For several models the spatial pattern in GPP explains less than half the variance in the MODIS MOD17 GPP product. Across the models NEP increases by as little as 0.01 to as much as 0.79 g C m−2 yr−2, equivalent to 3 to 340 % of the respective model means, over the analysis period. For the multimodel average the increase is 135 % of the mean from the first to last 10 years of record (1960–1969 vs. 2000–2009), with a weakening CO2 sink over the latter decades. Vegetation net primary productivity increased by 8 to 30 % from the first to last 10 years, contributing to soil carbon storage gains. The range in regional mean NEP among the group is twice the multimodel mean, indicative of the uncertainty in CO2 sink strength. The models simulate that inputs to the soil carbon pool exceeded losses, resulting in a net soil carbon gain amid a decrease in residence time. Our analysis points to improvements in model

  19. Estimation methods and monitoring network issues in the quantitative estimation of land-based COD and TN loads entering the sea: a case study in Qingdao City, China.

    Science.gov (United States)

    Su, Ying; Wang, Xiulin; Li, Keqiang; Liang, Shengkang; Qian, Guodong; Jin, Hong; Dai, Aiquan

    2014-09-01

    At present, the monitoring network of China cannot provide sufficient data to estimate land-based pollutant loads that enter the sea, and estimation methods are imprecisely used. In this study, the selection of monitoring stations, monitoring frequency, and pollutant load estimation methods was studied in Qingdao City, a typical coastal city in China, taken as an example. Land-based pollutant loads from Qingdao were estimated, and load distribution, density, and composition were analyzed to identify the key pollution source regions (SRs) that need to be monitored and controlled. Results show that the administrative land area of Qingdao can be divided into 25 sea-sink source regions (SSRs). A total of 14 more rivers and 62 industrial enterprises should be monitored to determine the comprehensive pollutant loads of the city. Furthermore, the monitoring frequency of rivers should not be less than three times/year; a monitoring frequency of five or more times is preferable. The findings on pollutant load estimation with the use of different estimation methods substantially vary; estimation results with the use of ratio-based methods were 10 and 22 % higher than those with the use of monitoring-based methods in terms of chemical oxygen demand (COD) and total nitrogen (TN), respectively. None-point sources contributed the majority of the pollutant loads at about 70 % of the total COD and 60 % of the total TN.

  20. Improving the spatial estimation of evapotranspiration by assimilating land surface temperature data

    Science.gov (United States)

    Zink, Matthias; Samaniego, Luis; Cuntz, Matthias

    2013-04-01

    A combined investigation of the water and energy balance in hydrologic models might lead to a more accurate estimation of hydrological fluxes and state variables, such as evapotranspiration ET and soil moisture. Hydrologic models are usually calibrated against discharge measurements, and thus are only trained on the integrated signal at few points within a catchment. This procedure does not take into account any spatial variability of fluxes or state variables. Satellite data are a useful source of information to incorporate spatial information into hydrologic models. The objective of this study is to improve the estimation of evapotranspiration in the spatial domain by using satellite derived land surface temperature Ts for the calibration of the distributed hydrological model mHM. The satellite products are based on data of Meteosat Second Generation (MSG) and are provided by the Land Surface Analysis - Satellite Application Facility (LSA-SAF). mHM simulations of Ts are obtained by solving the energy balance wherein evapotranspiration is determined by closing the water balance. Net radiation is calculated by using incoming short- and longwave radiation, albedo and emissivity data provided by LSA-SAF. The Multiscale Parameter Regionalization technique (MPR, Samaniego et al. 2010) is applied to determine the aerodynamic resistance among other parameters. The optimization is performed for the year 2009 using three objective functions that consider (1) only discharge, (2) only Ts, and (3) both discharge and Ts. For the spatial comparison of satellite derived and estimated Ts fields, a new measure accounting for local spatial variabilities is introduced. The proposed method is applied to seven major German river basins, i.e. Danube, Ems, Main, Mulde, Neckar, Saale, and Weser. The results of the Ts simulations show a bias of 4.1 K compared to the satellite data. We hypothesize that this bias is inherent to the satellite data rather than to the model simulations. This

  1. Estimating the Effects of Conversion of Agricultural Land to Urban Land on Deep Percolation of Irrigation Water in the Grand Valley, Western Colorado

    Science.gov (United States)

    Mayo, John W.

    2008-01-01

    The conversion of agricultural land to urban residential land is associated with rapid population growth in the Grand Valley of western Colorado. Information regarding the effects of this land-use conversion on deep percolation, irrigation-water application, and associated salt loading to the Colorado River is needed to support water-resource planning and conservation efforts. The Natural Resources Conservation Service (NRCS) assessed deep percolation and estimated salt loading derived from irrigated agricultural lands in the Grand Valley in a 1985 to 2002 monitoring and evaluation study (NRCS M&E). The U.S. Geological Survey (USGS), in cooperation with the Colorado River Salinity Control Forum and the Mesa Conservation District, quantified the current (2005-2006) deep percolation and irrigation-water application characteristics of 1/4-acre residential lots and 5-acre estates, urban parks, and urban orchard grass fields in the Grand Valley, and compared the results to NRCS M&E results from alfalfa-crop sites. In addition, pond seepage from three irrigation-water holding ponds was estimated. Salt loading was estimated for the urban study results and the NRCS M&E results by using standard salt-loading factors. A daily soil-moisture balance calculation technique was used at all urban study irrigated sites. Deep percolation was defined as any water infiltrating below the top 12 inches of soil. Deep percolation occurred when the soil-moisture balance in the first 12 inches of soil exceeded the field capacity for the soil type at each site. Results were reported separately for urban study bluegrass-only sites and for all-vegetation type (bluegrass, native plants, and orchard grass) sites. Deep percolation and irrigation-water application also were estimated for a complete irrigation season at three subdivisions by using mean site data from each subdivision. It was estimated that for the three subdivisions, 37 percent of the developed acreage was irrigated (the balance

  2. Should total landings be used to correct estimated catch in numbers or mean-weight-at-age?

    DEFF Research Database (Denmark)

    Lewy, Peter; Lassen, H.

    1997-01-01

    Many ICES fish stock assessment working groups have practised Sum Of Products, SOP, correction. This correction stems from a comparison of total weights of the known landings and the SOP over age of catch in number and mean weight-at-age, which ideally should be identical. In case of SOP...... discrepancies some countries correct catch in numbers while others correct mean weight-at-age by a common factor, the ratio between landing and SOP. The paper shows that for three sampling schemes the SOP corrections are statistically incorrect and should not be made since the SOP is an unbiased estimate...... of the total landings. Calculation of the bias of estimated catch in numbers and mean weight-at-age shows that SOP corrections of either of these estimates may increase the bias. Furthermore, for five demersal and one pelagic North Sea species it is shown that SOP discrepancies greater than 2% from...

  3. Fuel moisture content estimation: a land-surface modelling approach applied to African savannas

    Science.gov (United States)

    Ghent, D.; Spessa, A.; Kaduk, J.; Balzter, H.

    2009-04-01

    Despite the importance of fire to the global climate system, in terms of emissions from biomass burning, ecosystem structure and function, and changes to surface albedo, current land-surface models do not adequately estimate key variables affecting fire ignition and propagation. Fuel moisture content (FMC) is considered one of the most important of these variables (Chuvieco et al., 2004). Biophysical models, with appropriate plant functional type parameterisations, are the most viable option to adequately predict FMC over continental scales at high temporal resolution. However, the complexity of plant-water interactions, and the variability associated with short-term climate changes, means it is one of the most difficult fire variables to quantify and predict. Our work attempts to resolve this issue using a combination of satellite data and biophysical modelling applied to Africa. The approach we take is to represent live FMC as a surface dryness index; expressed as the ratio between the Normalised Difference Vegetation Index (NDVI) and land-surface temperature (LST). It has been argued in previous studies (Sandholt et al., 2002; Snyder et al., 2006), that this ratio displays a statistically stronger correlation to FMC than either of the variables, considered separately. In this study, simulated FMC is constrained through the assimilation of remotely sensed LST and NDVI data into the land-surface model JULES (Joint-UK Land Environment Simulator). Previous modelling studies of fire activity in Africa savannas, such as Lehsten et al. (2008), have reported significant levels of uncertainty associated with the simulations. This uncertainty is important because African savannas are among some of the most frequently burnt ecosystems and are a major source of greenhouse trace gases and aerosol emissions (Scholes et al., 1996). Furthermore, regional climate model studies indicate that many parts of the African savannas will experience drier and warmer conditions in future

  4. Estimating the effect of protected lands on the development and conservation of their surroundings.

    Science.gov (United States)

    McDonald, Robert I; Yuan-Farrell, Chris; Fievet, Charles; Moeller, Matthias; Kareiva, Peter; Foster, David; Gragson, Ted; Kinzig, Ann; Kuby, Lauren; Redman, Charles

    2007-12-01

    The fate of private lands is widely seen as key to the fate of biodiversity in much of the world. Organizations that work to protect biodiversity on private lands often hope that conservation actions on one piece of land will leverage the actions of surrounding landowners. Few researchers have, however, examined whether protected lands do in fact encourage land conservation nearby or how protected lands affect development in the surrounding landscape. Using spatiotemporal data sets on land cover and land protection for three sites (western North Carolina, central Massachusetts, and central Arizona), we examined whether the existence of a protected area correlates with an increased rate of nearby land conservation or a decreased rate of nearby land development. At all sites, newly protected conservation areas tended to cluster close to preexisting protected areas. This may imply that the geography of contemporary conservation actions is influenced by past decisions on land protection, often made for reasons far removed from concerns about biodiversity. On the other hand, we found no evidence that proximity to protected areas correlates with a reduced rate of nearby land development. Indeed, on two of our three sites the development rate was significantly greater in regions with more protected land. This suggests that each conservation action should be justified and valued largely for what is protected on the targeted land, without much hope of broader conservation leverage effects.

  5. Global Assessment of Land Surface Temperature From Geostationary Satellites and Model Estimates

    Science.gov (United States)

    Reichle, Rolf H.; Liu, Q.; Minnis, P.; daSilva, A. M., Jr.; Palikonda, R.; Yost, C. R.

    2012-01-01

    Land surface (or 'skin') temperature (LST) lies at the heart of the surface energy balance and is a key variable in weather and climate models. In this research we compare two global and independent data sets: (i) LST retrievals from five geostationary satellites generated at the NASA Langley Research Center (LaRC) and (ii) LST estimates from the quasi-operational NASA GEOS-5 global modeling and assimilation system. The objective is to thoroughly understand both data sets and their systematic differences in preparation for the assimilation of the LaRC LST retrievals into GEOS-5. As expected, mean differences (MD) and root-mean-square differences (RMSD) between modeled and retrieved LST vary tremendously by region and time of day. Typical (absolute) MD values range from 1-3 K in Northern Hemisphere mid-latitude regions to near 10 K in regions where modeled clouds are unrealistic, for example in north-eastern Argentina, Uruguay, Paraguay, and southern Brazil. Typically, model estimates of LST are higher than satellite retrievals during the night and lower during the day. RMSD values range from 1-3 K during the night to 2-5 K during the day, but are larger over the 50-120 W longitude band where the LST retrievals are derived from the FY2E platform

  6. The estimation of future surface water bodies at Olkiluoto area based on statistical terrain and land uplift models

    Energy Technology Data Exchange (ETDEWEB)

    Pohjola, J.; Turunen, J.; Lipping, T. [Tampere Univ. of Technology (Finland); Ikonen, A.

    2014-03-15

    In this working report the modelling effort of future landscape development and surface water body formation at the modelling area in the vicinity of the Olkiluoto Island is presented. Estimation of the features of future surface water bodies is based on probabilistic terrain and land uplift models presented in previous working reports. The estimation is done using a GIS-based toolbox called UNTAMO. The future surface water bodies are estimated in 10 000 years' time span with 1000 years' intervals for the safety assessment of disposal of spent nuclear fuel at the Olkiluoto site. In the report a brief overview on the techniques used for probabilistic terrain modelling, land uplift modelling and hydrological modelling are presented first. The latter part of the report describes the results of the modelling effort. The main features of the future landscape - the four lakes forming in the vicinity of the Olkiluoto Island - are identified and the probabilistic model of the shoreline displacement is presented. The area and volume of the four lakes is modelled in a probabilistic manner. All the simulations have been performed for three scenarios two of which are based on 10 realizations of the probabilistic digital terrain model (DTM) and 10 realizations of the probabilistic land uplift model. These two scenarios differ from each other by the eustatic curve used in the land uplift model. The third scenario employs 50 realizations of the probabilistic DTM while a deterministic land uplift model, derived solely from the current land uplift rate, is used. The results indicate that the two scenarios based on the probabilistic land uplift model behave in a similar manner while the third model overestimates past and future land uplift rates. The main features of the landscape are nevertheless similar also for the third scenario. Prediction results for the volumes of the future lakes indicate that a couple of highly probably lake formation scenarios can be identified

  7. Lake Michigan Diversion Accounting land cover change estimation by use of the National Land Cover Dataset and raingage network partitioning analysis

    Science.gov (United States)

    Sharpe, Jennifer B.; Soong, David T.

    2015-01-01

    The U.S. Army Corps of Engineers (USACE), Chicago District, is responsible for monitoring and computation of the quantity of Lake Michigan water diverted by the State of Illinois. As part of this effort, the USACE uses the Hydrological Simulation Program–FORTRAN (HSPF) with measured meteorological data inputs to estimate runoff from the Lake Michigan diversion special contributing areas (SCAs), the North Branch Chicago River above Niles and the Little Calumet River above South Holland gaged basins, and the Lower Des Plaines and the Calumet ungaged that historically drained to Lake Michigan. These simulated runoffs are used for estimating the total runoff component from the diverted Lake Michigan watershed, which is accountable to the total diversion by the State of Illinois. The runoff is simulated from three interpreted land cover types in the HSPF models: impervious, grass, and forest. The three land cover data types currently in use were derived from aerial photographs acquired in the early 1990s.

  8. Mechanical energy estimation during walking: validity and sensitivity in typical gait and in children with cerebral palsy.

    Science.gov (United States)

    Van de Walle, P; Hallemans, A; Schwartz, M; Truijen, S; Gosselink, R; Desloovere, K

    2012-02-01

    Gait efficiency in children with cerebral palsy is usually quantified by metabolic energy expenditure. Mechanical energy estimations, however, can be a valuable supplement as they can be assessed during gait analysis and plotted over the gait cycle, thus revealing information on timing and sources of increases in energy expenditure. Unfortunately, little information on validity and sensitivity exists. Three mechanical estimation approaches: (1) centre of mass (CoM) approach, (2) sum of segmental energies (SSE) approach and (3) integrated joint power approach, were validated against oxygen consumption and each other. Sensitivity was assessed in typical gait and in children with diplegia. CoM approach underestimated total energy expenditure and showed poor sensitivity. SSE approach overestimated energy expenditure and showed acceptable sensitivity. Validity and sensitivity were best in the integrated joint power approach. This method is therefore preferred for mechanical energy estimation in children with diplegia. However, mechanical energy should supplement, not replace metabolic energy, as total energy expended is not captured in any mechanical approach.

  9. A physical model to estimate snowfall over land using AMSU-B observations

    Science.gov (United States)

    Kim, Min-Jeong; Weinman, J. A.; Olson, W. S.; Chang, D.-E.; Skofronick-Jackson, G.; Wang, J. R.

    2008-05-01

    model developed in this study can reliably estimate the snowfall rate over land using the AMSU-B measured brightness temperatures.

  10. UNITED STATES LAND USE INVENTORY FOR ESTIMATING BIOGENIC OZONE PRECURSOR EMISSIONS

    Science.gov (United States)

    The U.S. Geological Survey's (USGS) Earth Resources Observation System (EROS) Data Center's (EDC) 1-km classified land cover data are combined with other land use data using a Geographic Information System (GIS) to create the Biogenic Emissions Landcover Database (BELD). The land...

  11. Air Temperature estimation from Land Surface temperature and solar Radiation parameters

    Science.gov (United States)

    Lazzarini, Michele; Eissa, Yehia; Marpu, Prashanth; Ghedira, Hosni

    2013-04-01

    Air Temperature (AirT) is a fundamental parameter in a wide range of applications such as climate change studies, weather forecast, energy balance modeling, efficiency of Photovoltaic (PV) solar cells, etc. Air temperature data are generally obtained through regular measurements from meteorological stations. The distribution of these stations is normally sparse, so the spatial pattern of this parameter cannot be accurately estimated by interpolation methods. This work investigated the relationship between Air Temperature measured at meteorological stations and spatially contiguous measurements derived from Remote Sensing techniques, such as Land Surface Temperature (LST) maps, emissivity maps and shortwave radiation maps with the aim of creating a continuous map of AirT. For LST and emissivity, MSG-SEVIRI LST product from Land Surface Analysis Satellite Applications Facility (LSA-SAF) has been used. For shortwave radiation maps, an Artificial Neural Networks ensemble model has been developed and previously tested to create continuous maps from Global Horizontal Irradiance (GHI) point measurements, utilizing six thermal channels of MSG-SEVIRI. The testing sites corresponded to three meteorological stations located in the United Arab Emirates (UAE), where in situ measurements of Air Temperature were available. From the starting parameters, energy fluxes and net radiation have been calculated, in order to have information on the incoming and outgoing long-wave radiation and the incoming short-wave radiation. The preliminary analysis (day and Night measurements, cloud free) showed a strong negative correlation (0.92) between Outgoing long-wave radiation - GHI and LST- AirT, with a RMSE of 1.84 K in the AirT estimation from the initial parameters. Regression coefficients have been determined and tested on all the ground stations. The analysis also demonstrated the predominant impact of the incoming short-wave radiation in the AirT hourly variation, while the incoming

  12. Estimating the effects of potential climate and land use changes on hydrologic processes of a large agriculture dominated watershed

    Science.gov (United States)

    Neupane, Ram P.; Kumar, Sandeep

    2015-10-01

    Land use and climate are two major components that directly influence catchment hydrologic processes, and therefore better understanding of their effects is crucial for future land use planning and water resources management. We applied Soil and Water Assessment Tool (SWAT) to assess the effects of potential land use change and climate variability on hydrologic processes of large agriculture dominated Big Sioux River (BSR) watershed located in North Central region of USA. Future climate change scenarios were simulated using average output of temperature and precipitation data derived from Special Report on Emission Scenarios (SRES) (B1, A1B, and A2) for end-21st century. Land use change was modeled spatially based on historic long-term pattern of agricultural transformation in the basin, and included the expansion of corn (Zea mays L.) cultivation by 2, 5, and 10%. We estimated higher surface runoff in all land use scenarios with maximum increase of 4% while expanding 10% corn cultivation in the basin. Annual stream discharge was estimated higher with maximum increase of 72% in SRES-B1 attributed from higher groundwater contribution of 152% in the same scenario. We assessed increased precipitation during spring season but the summer precipitation decreased substantially in all climate change scenarios. Similar to decreased summer precipitation, discharge of the BSR also decreased potentially affecting agricultural production due to reduced future water availability during crop growing season in the basin. However, combined effects of potential land use change with climate variability enhanced for higher annual discharge of the BSR. Therefore, these estimations can be crucial for implications of future land use planning and water resources management of the basin.

  13. Using remotely sensed data to estimate area-averaged daily surface fluxes over a semi-arid mixed agricultural land

    OpenAIRE

    2008-01-01

    Optical remote sensing has been widely used for diagnostics of land surface atmosphere exchanges, including evapotranspiration (ET). Estimating ET now benefits from modeling maturity at local scale, while ongoing challenges include both spatial and temporal issues: influences of spatial heterogeneities on non-linear behavior when upscaling and extrapolation of instantaneous estimates at satellite overpass to the daily scale. Both issues are very important when using remote sensing for managin...

  14. Can we reconcile differences in estimates of carbon fluxes from land-use change and forestry for the 1990s?

    Directory of Open Access Journals (Sweden)

    A. Ito

    2008-02-01

    Full Text Available The effect of Land Use Change and Forestry (LUCF on terrestrial carbon fluxes can be regarded as a carbon credit or debit under the UNFCCC, but scientific uncertainty in the estimates for LUCF remains large. Here, we assess the LUCF estimates by examining a variety of models of different types with different land cover change maps in the 1990s. Annual carbon pools and their changes are separated into different components for separate geographical regions, while annual land cover change areas and carbon fluxes are disaggregated into different LUCF activities and the biospheric response due to CO2 fertilization and climate change. We developed a consolidated estimate of the terrestrial carbon fluxes that combines book-keeping models with process-based biogeochemical models and inventory estimates and yields an estimate of the global terrestrial carbon flux that is within the uncertainty range developed in the IPCC 4th Assessment Report. We examined the USA and Brazil as case studies in order to assess the cause of differences from the UNFCCC reported carbon fluxes. Major differences in the litter and soil organic matter components are found for the USA. Differences in Brazil result from assumptions about the LUC for agricultural purposes. The effects of CO2 fertilization and climate change also vary significantly in Brazil. Our consolidated estimate shows that the small sink in Latin America is within the uncertainty range from inverse models, but that the sink in the USA is significantly smaller than the inverse models estimates. Because there are different sources of errors at the country level, there is no easy reconciliation of different estimates of carbon fluxes at the global level. Clearly, further work is required to develop data sets for historical land cover change areas and models of biogeochemical changes for an accurate representation of carbon uptake or emissions due to LUC.

  15. Factors controlling carbon isotopic composition of land snail shells estimated from lab culturing experiment

    Science.gov (United States)

    Zhang, Naizhong; Yamada, Keita; Yoshida, Naohiro

    2014-05-01

    Carbon isotopic composition (δ13C) of land snail shell carbonate is widely applied in reconstructing the C3/C4 vegetation distribution of paleo-environment, which is considered to reflect variations of some environmental parameters [1][2][3]. Land snail shell carbon has three potential sources: diet, atmospheric CO2 and ingested carbonate (limestone) [4]. However, their relative contributions to shell carbonate have not been understood well yet [4][5][6][7][8]. More researches are necessary before we could apply this tool in paleo-environment reconstruction, especially inter-lab culturing experiment. A kind of land snail species, Acusta despecta sieboldiana, was collected at Yokohama, Japan and cultured under suitable environment to lay eggs. The second generations were growing up from eggs to adults around 6-12 months at the temperature of 20°, 25° and 30°, respectively. All of the snails at 25° and 30° and most of those at 20° were fed by cabbage (C3 plant) during their life span while others were fed by corn (C4 plant). To investigate the effect of ingested carbonate, some of them were fed by Ca3(PO4)2 powder while others were fed by CaCO3 powder. δ13C of shells were analyzed by an Isotope Ratio Mass Spectrometry (Thermo Finnigan MAT 253); δ13C of food and snail tissue were measured by a Cavity Ring-Down Spectroscopy (Picarro G1121-i). At the same time, δ13C of eggshell and new born snails were analyzed by a Continuous Flow Isotope Ratio Mass Spectrometry (GasBench II). We confirmed that diet, atmospheric CO2 and ingested limestone could be important sources controlling shell δ13C values. And the temperature could affect shell carbonate δ13C values, too. A simple but credible frame was raised to discuss the mechanism of how each possible source and environmental parameter could affect shell carbonate δ13C values based on previous works [4][6][8] and this study. According to this frame and some reasonable assumptions, we have estimated the

  16. Estimation of landslides activities evolution due to land-use changes in a Pyrenean valley

    Science.gov (United States)

    Vandromme, Rosalie; Desramaut, Nicolas; Cottin, Léa; Bernardie, Séverine; Grandjean, Gilles

    2015-04-01

    Global changes would have impacts worldwide, but their effects should be even more exacerbated in areas particularly vulnerable. Mountainous areas are among these vulnerable territories. Ecological systems are often at a fragile equilibrium, socio-economical activities are often climate-dependent and climate-driven natural hazards can be a major threat for human activities. In order to estimate the capacity of such mountainous valleys to face global changes (climate, but also climate- and human- induced land-use changes), it is necessary to be able to evaluate the evolution of the different threats. The present work presents a method to evaluate the influences of the evolution of both climate and vegetation cover on landslides activities over a whole valley, to propose adequate solutions for current and future forestry management. It is therefore necessary to properly estimate the vegetation influences on slope stabilities. In the present study, we develop a complementary module to our large-scale slope stability assessment tool to take into account the effects of vegetation on the mechanical soil properties (cohesion and over-load), but also on the slope hydrology (change in interceptions, run-off, and infiltration). Hence the proposed method combines a mechanical stability model (using finite slope analysis), a hydrological model, and a vegetation module which interfere with both aspects. All these elements are interfaced within a GIS-based solution. The whole chain is applied to a 100-km² Pyrenean Valley, for the ANR Project SAMCO (Society Adaptation for coping with Mountain risks in a global change COntext), as a first step in the chain for risk assessment for different climate and economical development scenarios, to evaluate the resilience of mountainous areas.

  17. [Applying temporally-adjusted land use regression models to estimate ambient air pollution exposure during pregnancy].

    Science.gov (United States)

    Zhang, Y J; Xue, F X; Bai, Z P

    2017-03-06

    The impact of maternal air pollution exposure on offspring health has received much attention. Precise and feasible exposure estimation is particularly important for clarifying exposure-response relationships and reducing heterogeneity among studies. Temporally-adjusted land use regression (LUR) models are exposure assessment methods developed in recent years that have the advantage of having high spatial-temporal resolution. Studies on the health effects of outdoor air pollution exposure during pregnancy have been increasingly carried out using this model. In China, research applying LUR models was done mostly at the model construction stage, and findings from related epidemiological studies were rarely reported. In this paper, the sources of heterogeneity and research progress of meta-analysis research on the associations between air pollution and adverse pregnancy outcomes were analyzed. The methods of the characteristics of temporally-adjusted LUR models were introduced. The current epidemiological studies on adverse pregnancy outcomes that applied this model were systematically summarized. Recommendations for the development and application of LUR models in China are presented. This will encourage the implementation of more valid exposure predictions during pregnancy in large-scale epidemiological studies on the health effects of air pollution in China.

  18. Evaluation of MODIS Land products for air temperature estimations in Colombia

    Directory of Open Access Journals (Sweden)

    Ricardo Castro-Díaz

    2013-08-01

    Full Text Available The moderate resolution imaging spectroradiometer (MODIS land-surface temperature/emissivity (LST product is often used for studies in meteorology due to its ability for near realtime evaluations. Colombia, as a country requires a prospective management for its productive ecosystems, but currently does not have sufficient spatially-distributed field data for air temperature at 2-m above the ground. The traditional validation of MODIS products includes field campaigns for calibrating and measuring differences between the satellite sensor and radiometers. For this research, the LST data on the ground was compared with climatologic stations using multiple regression techniques for improving the accuracy of the LST from MODIS, using MOD09GA , MOD17A2, MOD15A2, MOD13A2 as ancillary parameters (explanatory variables in the final model. The ground measurements were obtained in the Caribbean zone and the Casanare and Valle del Cauca departments in Colombia, using agroclimatic stations in the first dry season of 2007 and daily MODIS data. Enhanced vegetation index, fraction of photosynthetically active radiation, and net photosynthesis were included in the final model for explaining the vegetation as a key parameter for air temperature. Finally, two factors were proposed for LST estimation: sensor zenith angle and solar zenith angle due to the reflectance of the vegetation and sensitivity of the sensor

  19. Utilization of satellite-derived estimates of meteorological and land surface characteristics in the Land Surface Model for vast agricultural region territory

    Science.gov (United States)

    Muzylev, Eugene; Startseva, Zoya; Uspensky, Alexander; Volkova, Elena

    2015-04-01

    The method has been elaborated to evaluate the water and heat regime characteristics of the territory on a regional scale for the vegetation season based on a physical-mathematical model of water and heat exchange between vegetation covered land surface and atmosphere (LSM, Land Surface Model) appropriate for using satellite information on land surface and meteorological conditions. The developed model is intended for calculating soil water content, evapotranspiration (evaporation from bare soil and transpiration by vegetation), vertical water and heat fluxes as well as land surface and vegetation cover temperatures and vertical distributions of temperature and moisture in the active soil layer. Parameters of the model are soil and vegetation characteristics and input variables are meteorological characteristics. Their values have been obtained from ground-based observations at agricultural meteorological stations and satellite-based measurements by scanning radiometers AVHRR/NOAA, MODIS/EOS Terra and Aqua and SEVIRI (geostationary satellites Meteosat-9, -10). The AVHRR data have been used to build the estimates of three types of land surface temperature (LST): land skin temperature Tsg, air temperature at a level of vegetation cover Ta and efficient radiation temperature Tseff, emissivity E, normalized vegetation index NDVI, vegetation cover fraction B, leaf area index LAI, and precipitation. The set of estimates derived from MODIS data has comprised values of LST Tls, E, NDVI and LAI. The SEVIRI-based retrievals have included Tls, Ta, Е at daylight and nighttime, LAI (daily) and precipitation. The case study has been carried out for agricultural Central Black Earth region of the European Russia of 227,300 sq.km containing 7 regions of the Russian Federation for years 2009-2013 vegetation seasons. Estimates of described characteristics have been built with the help of the developed original and improved pre-existing methods and technologies of thematic processing

  20. Aggregation and spatial analysis of walking activity in an urban area: results from the Halifax space-time activity survey

    Science.gov (United States)

    Neatt, K.; Millward, H.; Spinney, J.

    2016-04-01

    This study examines neighborhood characteristics affecting the incidence of walking trips in urban and suburban areas of Halifax, Canada. We employ data from the Space-Time Activity Research (STAR) survey, conducted in 2007-8. Primary respondents completed a two- day time-diary survey, and their movements were tracked using a GPS data logger. Primary respondents logged a total of 5,005 walking trips, specified by 781,205 individual GPS points. Redundant and erroneous points, such as those with zero or excessive speed, were removed. Data points were then imported into ArcGIS, converted from points to linear features, visually inspected for data quality, and cleaned appropriately. From mapped walking tracks we developed hypotheses regarding variations in walking density. To test these, walking distances were aggregated by census tracts (CTs), and expressed as walking densities (per resident, per metre of road, and per developed area). We employed multivariate regression to examine which neighborhood (CT) variables are most useful as estimators of walking densities. Contrary to much of the planning literature, built-environment measures of road connectivity and dwelling density were found to have little estimating power. Office and institutional land uses are more useful estimators, as are the income and age characteristics of the resident population.

  1. Assessment of leaching loss estimates and gross load of nitrogen from arable land in Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, Markus (Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Soil Sciences)

    1999-01-01

    The focus of this thesis is on calculating N leaching loss estimates and gross loads of nitrogen. Calculations were done at two different scales, from field resolution in a small catchment to calculations at a large scale for the south and central part of Sweden. The latter study was initiated by Swedish commitments to international agreements concerning a decrease in N emissions to the Baltic Sea. Three of the papers deal with leaching of nitrogen in different periods: as it may have been in the 19[sup th] century, the current situation, and suggestions for a decrease with different countermeasures. The tools used in making these estimations were the SOIL/SOILN models. Calculations indicate that average N leaching was about the same in the 19[sup th] century as it is today at the end of the 20[sup th] century. The main reasons for high losses in the 19[sup th] century were high mineralisation rates in newly ploughed grassland, crop stress due to unfavourable conditions caused poor utilisation of N by crops, and large areas of bare fallow. N leaching was at its lowest in the 1930's due to larger N utilisation, a general termination of enhanced mineralisation and a large acreage of ley. Since then leaching has increased by on average about 60%, and more in the south of Sweden. Results also indicate that the draining of lakes has considerably decreased the retention capacity and is, along with the increase in gross load, one of the main causes of increased net load to the sea. A decrease in N leaching was estimated for the period 1985-1994. The decrease was mostly due to a smaller total area of arable land and an increase in the acreage of ley at the expense of cereals. The increase in the percentage of ley in the ten-year period (1985-1994) was the largest occurring in such a short time in the last 130 years in Sweden. Scenario calculations indicate that there is a potential for a decrease in the gross load of approximately 10 ktonnes from the current level of

  2. On the Use of FOSS4G in Land Cover Fraction Estimation with Unmixing Algorithms

    Science.gov (United States)

    Kumar, U.; Milesi, C.; Raja, K.; Ganguly, S.; Wang, W.; Zhang, G.; Nemani, R. R.

    2014-12-01

    The popularity and usage of FOSS4G (FOSS for Geoinformatics) has increased drastically in the last two decades with increasing benefits that facilitate spatial data analysis, image processing, graphics and map production, spatial modeling and visualization. The objective of this paper is to use FOSS4G to implement and perform a quantitative analysis of three different unmixing algorithms: Constraint Least-Square (CLS), Unconstraint Least-Square, and Orthogonal Subspace Projection to estimate land cover (LC) fraction estimates from RS data. The LC fractions obtained by unmixing of mixed pixels represent mixture of more than one class per pixel rendering more accurate LC abundance estimates. The algorithms were implemented in C++ programming language with OpenCV package (http://opencv.org/) and boost C++ libraries (www.boost.org) in the NASA Earth Exchange at the NASA Advanced Supercomputing Facility. GRASS GIS was used for visualization of results and statistical analysis was carried in R in a Linux system environment. A set of global endmembers for substrate, vegetation and dark objects were used to unmix the data using the three algorithms and were compared with Singular Value decomposition unmixed outputs available in ENVI image processing software. First, computer simulated data of different signal to noise ratio were used to evaluate the algorithms. The second set of experiments was carried out in an agricultural set-up with a spectrally diverse collection of 11 Landsat-5 scenes (acquired in 2008) for an agricultural setup in Frenso, California and the ground data were collected on those specific dates when the satellite passed through the site. Finally, in the third set of experiments, a pair of coincident clear sky Landsat and World View 2 data for an urbanized area of San Francisco were used to assess the algorithm. Validation of the results using descriptive statistics, correlation coefficient (cc), RMSE, boxplot and bivariate distribution function

  3. Estimating Daily Maximum and Minimum Land Air Surface Temperature Using MODIS Land Surface Temperature Data and Ground Truth Data in Northern Vietnam

    Directory of Open Access Journals (Sweden)

    Phan Thanh Noi

    2016-12-01

    Full Text Available This study aims to evaluate quantitatively the land surface temperature (LST derived from MODIS (Moderate Resolution Imaging Spectroradiometer MOD11A1 and MYD11A1 Collection 5 products for daily land air surface temperature (Ta estimation over a mountainous region in northern Vietnam. The main objective is to estimate maximum and minimum Ta (Ta-max and Ta-min using both TERRA and AQUA MODIS LST products (daytime and nighttime and auxiliary data, solving the discontinuity problem of ground measurements. There exist no studies about Vietnam that have integrated both TERRA and AQUA LST of daytime and nighttime for Ta estimation (using four MODIS LST datasets. In addition, to find out which variables are the most effective to describe the differences between LST and Ta, we have tested several popular methods, such as: the Pearson correlation coefficient, stepwise, Bayesian information criterion (BIC, adjusted R-squared and the principal component analysis (PCA of 14 variables (including: LST products (four variables, NDVI, elevation, latitude, longitude, day length in hours, Julian day and four variables of the view zenith angle, and then, we applied nine models for Ta-max estimation and nine models for Ta-min estimation. The results showed that the differences between MODIS LST and ground truth temperature derived from 15 climate stations are time and regional topography dependent. The best results for Ta-max and Ta-min estimation were achieved when we combined both LST daytime and nighttime of TERRA and AQUA and data from the topography analysis.

  4. Minimal Walking Technicolor

    DEFF Research Database (Denmark)

    Frandsen, Mads Toudal

    2007-01-01

    I report on our construction and analysis of the effective low energy Lagrangian for the Minimal Walking Technicolor (MWT) model. The parameters of the effective Lagrangian are constrained by imposing modified Weinberg sum rules and by imposing a value for the S parameter estimated from the under...... the underlying Technicolor theory. The constrained effective Lagrangian allows for an inverted vector vs. axial-vector mass spectrum in a large part of the parameter space....

  5. Spatially-Explicit Estimates of Greenhouse Gas Emissions from Fire and Land-Use Change in the Brazilian Cerrado

    Science.gov (United States)

    Galford, G. L.; Spera, S. A.; Coe, M. T.; Costa, C., Jr.

    2014-12-01

    Understanding the multiple types of land-use changes that can occur within an ecosystem provides a comprehensive picture of the human's impact on natural systems. We use the Cerrado (savanna) of Brazil to examine the primary and secondary impacts of land-use change on greenhouse gas emissions. The primary land-use changes include fires for land-clearing, conversions to pasture and row-crop agriculture, and shifting management practices of agricultural lands. Secondary land-use changes include savanna degradation due to fires that escape from intended burn areas. These escape fires typically have a lower combustion completion coefficient than clearing fires, so it is important to distinguish them to correctly estimate the regional greenhouse gas budget. We have created a first-order spatio-temporal model of greenhouse gas emissions that can be easily modified for other savanna regions using globally available data products as inputs. Our data inputs are derived from publically available remote sensing imagery. Initial biomass is estimated by Baccini et al. 2012, which is derived from LiDAR and MODIS imagery. All other input data sets give annual estimates. Clearing of the savanna is documented by LAPIG of Universidade Federal de Goias using MODIS (MOD13Q1), LANDSAT and CBERS images. MODIS burned area products delineate annual fires; in combination with the savanna clearing database we determine primary and escape fires. Pastures and row-crop agriculture are documented by LAPIG and Spera et al. 2014, respectively. The row-crop agriculture dataset enables us to estimate greenhouse gas emissions associated with specific crops (e.g., soy or maize) and management (e.g., fertilizer use). Recent contributions to the literature have provided many in situ measurements from the land-use changes of interest needed to estimate a regional greenhouse gas budget, including combustion coefficients of savanna sub-types, carbon emission soil stocks, nitrogen emissions from fertilizer

  6. Assessment of model behavior and acceptable forcing data uncertainty in the context of land surface soil moisture estimation

    Science.gov (United States)

    Dumedah, Gift; Walker, Jeffrey P.

    2017-03-01

    The sources of uncertainty in land surface models are numerous and varied, from inaccuracies in forcing data to uncertainties in model structure and parameterizations. Majority of these uncertainties are strongly tied to the overall makeup of the model, but the input forcing data set is independent with its accuracy usually defined by the monitoring or the observation system. The impact of input forcing data on model estimation accuracy has been collectively acknowledged to be significant, yet its quantification and the level of uncertainty that is acceptable in the context of the land surface model to obtain a competitive estimation remain mostly unknown. A better understanding is needed about how models respond to input forcing data and what changes in these forcing variables can be accommodated without deteriorating optimal estimation of the model. As a result, this study determines the level of forcing data uncertainty that is acceptable in the Joint UK Land Environment Simulator (JULES) to competitively estimate soil moisture in the Yanco area in south eastern Australia. The study employs hydro genomic mapping to examine the temporal evolution of model decision variables from an archive of values obtained from soil moisture data assimilation. The data assimilation (DA) was undertaken using the advanced Evolutionary Data Assimilation. Our findings show that the input forcing data have significant impact on model output, 35% in root mean square error (RMSE) for 5cm depth of soil moisture and 15% in RMSE for 15cm depth of soil moisture. This specific quantification is crucial to illustrate the significance of input forcing data spread. The acceptable uncertainty determined based on dominant pathway has been validated and shown to be reliable for all forcing variables, so as to provide optimal soil moisture. These findings are crucial for DA in order to account for uncertainties that are meaningful from the model standpoint. Moreover, our results point to a proper

  7. Estimation of Ecosystem Parameters of the Community Land Model with DREAM: Evaluation of the Potential for Upscaling Net Ecosystem Exchange

    Science.gov (United States)

    Hendricks Franssen, H. J.; Post, H.; Vrugt, J. A.; Fox, A. M.; Baatz, R.; Kumbhar, P.; Vereecken, H.

    2015-12-01

    Estimation of net ecosystem exchange (NEE) by land surface models is strongly affected by uncertain ecosystem parameters and initial conditions. A possible approach is the estimation of plant functional type (PFT) specific parameters for sites with measurement data like NEE and application of the parameters at other sites with the same PFT and no measurements. This upscaling strategy was evaluated in this work for sites in Germany and France. Ecosystem parameters and initial conditions were estimated with NEE-time series of one year length, or a time series of only one season. The DREAM(zs) algorithm was used for the estimation of parameters and initial conditions. DREAM(zs) is not limited to Gaussian distributions and can condition to large time series of measurement data simultaneously. DREAM(zs) was used in combination with the Community Land Model (CLM) v4.5. Parameter estimates were evaluated by model predictions at the same site for an independent verification period. In addition, the parameter estimates were evaluated at other, independent sites situated >500km away with the same PFT. The main conclusions are: i) simulations with estimated parameters reproduced better the NEE measurement data in the verification periods, including the annual NEE-sum (23% improvement), annual NEE-cycle and average diurnal NEE course (error reduction by factor 1,6); ii) estimated parameters based on seasonal NEE-data outperformed estimated parameters based on yearly data; iii) in addition, those seasonal parameters were often also significantly different from their yearly equivalents; iv) estimated parameters were significantly different if initial conditions were estimated together with the parameters. We conclude that estimated PFT-specific parameters improve land surface model predictions significantly at independent verification sites and for independent verification periods so that their potential for upscaling is demonstrated. However, simulation results also indicate

  8. Biofuels and Land Use Change: Applying Recent Evidence to Model Estimates

    Directory of Open Access Journals (Sweden)

    Wallace E. Tyner

    2013-01-01

    Full Text Available Biofuels impact on global land use has been a controversial yet important topic. Up until recently, there has not been enough biofuels to have caused major land use change, so the evidence from actual global land use data has been scant. However, in the past decade, there have been 72 million hectares added to global crop cover. In this research we take advantage of this new data to calibrate the Global Trade Analysis Project (GTAP model and parameters. We make two major changes. First, we calibrate the land transformation parameters (called constant elasticity of transformation, CET to global regions so that the parameters better reflect the actual land cover change that has occurred. Second, we alter the land cover nesting structure. In the old GTAP model, cropland, pasture, and forest were all in the same nest suggesting, everything else being equal, that pasture or forest convert to cropland with equal ease and cost. However, we now take advantage of the fact that pasture converts to cropland at lower cost than forest. The paper provides the theoretical and empirical justification for these two model improvements. Then it re-evaluates the global land use impacts due to the USA ethanol program using the improved model tuned with actual observations. Finally, it shows that compared to the old model, the new model projects: (1 less expansion in global cropland due to ethanol expansion; (2 lower U.S. share in global cropland expansion; (3 and lower forest share in global cropland expansion.

  9. Sub-grid scale representation of vegetation in global land surface schemes: implications for estimation of the terrestrial carbon sink

    Directory of Open Access Journals (Sweden)

    J. R. Melton

    2014-02-01

    Full Text Available Terrestrial ecosystem models commonly represent vegetation in terms of plant functional types (PFTs and use their vegetation attributes in calculations of the energy and water balance as well as to investigate the terrestrial carbon cycle. Sub-grid scale variability of PFTs in these models is represented using different approaches with the "composite" and "mosaic" approaches being the two end-members. The impact of these two approaches on the global carbon balance has been investigated with the Canadian Terrestrial Ecosystem Model (CTEM v 1.2 coupled to the Canadian Land Surface Scheme (CLASS v 3.6. In the composite (single-tile approach, the vegetation attributes of different PFTs present in a grid cell are aggregated and used in calculations to determine the resulting physical environmental conditions (soil moisture, soil temperature, etc. that are common to all PFTs. In the mosaic (multi-tile approach, energy and water balance calculations are performed separately for each PFT tile and each tile's physical land surface environmental conditions evolve independently. Pre-industrial equilibrium CLASS-CTEM simulations yield global totals of vegetation biomass, net primary productivity, and soil carbon that compare reasonably well with observation-based estimates and differ by less than 5% between the mosaic and composite configurations. However, on a regional scale the two approaches can differ by > 30%, especially in areas with high heterogeneity in land cover. Simulations over the historical period (1959–2005 show different responses to evolving climate and carbon dioxide concentrations from the two approaches. The cumulative global terrestrial carbon sink estimated over the 1959–2005 period (excluding land use change (LUC effects differs by around 5% between the two approaches (96.3 and 101.3 Pg, for the mosaic and composite approaches, respectively and compares well with the observation-based estimate of 82.2 ± 35 Pg C over the same

  10. Human walking estimation with radar

    NARCIS (Netherlands)

    Dorp, Ph. van; Groen, F.C.A.

    2003-01-01

    Radar can be used to observe humans that are obscured by objects such as walls. These humans cannot be visually observed. The radar measurements are used to animate an obscured human in virtual reality. This requires detailed information about the motion. The radar measurements give detailed informa

  11. Human walking estimation with radar

    NARCIS (Netherlands)

    Dorp, Ph. van; Groen, F.C.A.

    2003-01-01

    Radar can be used to observe humans that are obscured by objects such as walls. These humans cannot be visually observed. The radar measurements are used to animate an obscured human in virtual reality. This requires detailed information about the motion. The radar measurements give detailed

  12. Incorporating changes in albedo in estimating the climate mitigation benefits of land use change projects

    OpenAIRE

    Bird, D. N.; Kunda, M.; Mayer, A.; Schlamadinger, B.; Canella, L.; Johnston, M.

    2008-01-01

    Some climate scientists are questioning whether the practice of converting of non-forest lands to forest land (afforestation or reforestation) is an effective climate change mitigation option. The discussion focuses particularly on areas where the new forest is primarily coniferous and there is significant amount of snow since the increased climate forcing due to the change in albedo may counteract the decreased climate forcing due to carbon dioxide removal.

    In this pape...

  13. Random Walks and Diffusions on Graphs and Databases An Introduction

    CERN Document Server

    Blanchard, Philippe

    2011-01-01

    Most networks and databases that humans have to deal with contain large, albeit finite number of units. Their structure, for maintaining functional consistency of the components, is essentially not random and calls for a precise quantitative description of relations between nodes (or data units) and all network components. This book is an introduction, for both graduate students and newcomers to the field, to the theory of graphs and random walks on such graphs. The methods based on random walks and diffusions for exploring the structure of finite connected graphs and databases are reviewed (Markov chain analysis). This provides the necessary basis for consistently discussing a number of applications such diverse as electric resistance networks, estimation of land prices, urban planning, linguistic databases, music, and gene expression regulatory networks.

  14. Estimating Evapotranspiration Demands of Different Land Cover Using Diurnal Signals in Dry Season Stream Discharge

    Science.gov (United States)

    Bhalla, R. S.; K, K.; Srinivas, V.; Krishnaswamy, J.; Chappell, N. A.; Jones, T.

    2015-12-01

    We use a paired catchment approach to compare the dry season flows between natural grasslands and introduced plantations of black wattle (Acacia mearnsii) in the Nilgiri South range forest which lies in the southern parts of the Western Ghat mountain range in Sothern India, a global biodiversity hot-spot. Discharges were measured using a portable flume and a weir fitted with capacitance probes logging water levels every five minutes in two adjacent catchments. Sensor artefacts in the data were filtered out before analysis. Diurnal variations in dry season flows from March 1st to April 15th, 2014 were used to estimate the daily ET based on Boronina et al. 2005 (Hyd. Proc. 19, 20, pp. 4055-4068.) using the equation 1. : E T daily = ∑ i=1 24 ( Q max - Q i ) Δ t , where E T daily is the daily loss of water from the catchment through ET, Q max is the daily maximum flow rate in the river, Q i is the average flow rate for every hour of the day and Δ t is one hour. Our results show that land use conversion from grasslands to wattle has increased ET by 40.97mm which is to the order of 60% during the period of the study (table 1). This has immediate relevance for dry season flows in the region. Nilgiris provide 40% of the total hydro-power generation for the state of Tamil Nadu and these streams sustain biodiversity and are tributaries of the Cauvery river, the largest the state. They also highlight the potential consequences of programmes such as the National Mission for Greening India which explicitly targets conversions of 10m ha of degraded forests, scrub and grasslands to tree cover and forest. Grassland Wattle Difference 1st Qu. 1.14 1.36 -1.33 Median 1.94 2.04 0.28 Mean 2.06 2.97 0.91 3rd Qu. 2.66 3.51 2.43 Sum 92.63 133.60 40.97 Table 1: Summary statistics for daily dry season ET for catchment under grassland, wattle and the daily differences between the two in mm per day.

  15. MITRA Virtual laboratory for operative application of satellite time series for land degradation risk estimation

    Science.gov (United States)

    Nole, Gabriele; Scorza, Francesco; Lanorte, Antonio; Manzi, Teresa; Lasaponara, Rosa

    2015-04-01

    This paper aims to present the development of a tool to integrate time series from active and passive satellite sensors (such as of MODIS, Vegetation, Landsat, ASTER, COSMO, Sentinel) into a virtual laboratory to support studies on landscape and archaeological landscape, investigation on environmental changes, estimation and monitoring of natural and anthropogenic risks. The virtual laboratory is composed by both data and open source tools specifically developed for the above mentioned applications. Results obtained for investigations carried out using the implemented tools for monitoring land degradation issues and subtle changes ongoing on forestry and natural areas are herein presented. In detail MODIS, SPOT Vegetation and Landsat time series were analyzed comparing results of different statistical analyses and the results integrated with ancillary data and evaluated with field survey. The comparison of the outputs we obtained for the Basilicata Region from satellite data analyses and independent data sets clearly pointed out the reliability for the diverse change analyses we performed, at the pixel level, using MODIS, SPOT Vegetation and Landsat TM data. Next steps are going to be implemented to further advance the current Virtual Laboratory tools, by extending current facilities adding new computational algorithms and applying to other geographic regions. Acknowledgement This research was performed within the framework of the project PO FESR Basilicata 2007/2013 - Progetto di cooperazione internazionale MITRA "Remote Sensing tecnologies for Natural and Cultural heritage Degradation Monitoring for Preservation and valorization" funded by Basilicata Region Reference 1. A. Lanorte, R Lasaponara, M Lovallo, L Telesca 2014 Fisher-Shannon information plane analysis of SPOT/VEGETATION Normalized Difference Vegetation Index (NDVI) time series to characterize vegetation recovery after fire disturbance International Journal of Applied Earth Observation and

  16. Estimation of Daily Air Temperature Based on MODIS Land Surface Temperature Products over the Corn Belt in the US

    Directory of Open Access Journals (Sweden)

    Linglin Zeng

    2015-01-01

    Full Text Available Air temperature (Ta is a key input in a wide range of agroclimatic applications. Moderate Resolution Imaging Spectroradiometer (MODIS Ts (Land Surface Temperature (LST products are widely used to estimate daily Ta. However, only daytime LST (Ts-day or nighttime LST (Ts-night data have been used to estimate Tmax/Tmin (daily maximum or minimum air temperature, respectively. The relationship between Tmax and Ts-night, and the one between Tmin and Ts-day has not been studied. In this study, both the ability of Ts-night data to estimate Tmax and the ability of Ts-day data to estimate Tmin were tested and studied in the Corn Belt during the growing season (May–September from 2008 to 2012, using MODIS daily LST products from both Terra and Aqua. The results show that using Ts-night for estimating Tmax could result in a higher accuracy than using Ts-day for a similar estimate. Combining Ts-day and Ts-night, the estimation of Tmax was improved by 0.19–1.85, 0.37–1.12 and 0.26–0.93 °C for crops, deciduous forest and developed areas, respectively, when compared with using only Ts-day or Ts-night data. The main factors influencing the Ta estimation errors spatially and temporally were analyzed and discussed, such as satellite overpassing time, air masses, irrigation, etc.

  17. The influence of simulation model complexity on the estimation of internal loading in gymnastics landings.

    Science.gov (United States)

    Mills, Chris; Pain, Matthew T G; Yeadon, Maurice R

    2008-01-01

    Evaluating landing technique using a computer simulation model of a gymnast and landing mat could be a useful tool when attempting to assess injury risk. The aims of this study were: (1) to investigate whether a subject-specific torque-driven or a subject-specific muscle-driven model of a gymnast is better at matching experimental ground reaction forces and kinematics during gymnastics landings, (2) to calculate their respective simulation run times and (3) to determine what level of model complexity is required to assess injury risk. A subject-specific planar seven-link wobbling mass model of a gymnast and a multi-layer model of a landing mat were developed for this study. Subject-specific strength parameters were determined which defined the maximum voluntary torque/angle/angular velocity relationship about each joint. This relationship was also used to produce subject-specific 'lumped' muscle models for each joint. Kinetic and kinematic data were obtained during landings from backward and forward rotating gymnastics vaults. Both torque-driven and muscle-driven models were capable of producing simulated landings that matched the actual performances (with overall percentage differences between 10.1% and 18.2%). The torque-driven model underestimated the internal loading on joints and bones, resulting in joint reaction forces that were less than 50% of those calculated using the muscle-driven model. Simulation time increased from approximately 3 min (torque driven) to more than 10 min (muscle driven) as model complexity increased. The selection of a simulation model for assessing injury risk must consider the need for determining realistic internal forces as the priority despite increases in simulation run time.

  18. Estimating the benefits of land imagery in environmental applications: a case study in nonpoint source pollution of groundwater

    Science.gov (United States)

    Bernknopf, Richard L.; Forney, William M.; Raunikar, Ronald P.; Mishra, Shruti K.; Laxminarayan, Ramanan; Maccauley, Molly K.

    2012-01-01

    Moderate-resolution land imagery (MRLI) is crucial to a more complete assessment of the cumulative, landscape-level effect of agricultural land use and land cover on environmental quality. If this improved assessment yields a net social benefit, then that benefit reflects the value of information (VOI) from MRLI. Environmental quality and the capacity to provide ecosystem services evolve because of human actions, changing natural conditions, and their interaction with natural physical processes. The human actions, in turn, are constrained and redirected by many institutions and regulations such as agricultural, energy, and environmental policies. We present a general framework for bringing together sociologic, biologic, physical, hydrologic, and geologic processes at meaningful scales to interpret environmental implications of MRLI applications. We set out a specific application using MRLI observations to identify crop planting patterns and thus estimate surface management activities that influence groundwater resources over a regional landscape. We tailor the application to the characteristics of nonpoint source groundwater pollution hazards in Iowa to illustrate a general framework in a land use-hydrologic-economic system. In the example, MRLI VOI derives from reducing the risk of both losses to agricultural production and damage to human health and other consequences of contaminated groundwater.

  19. Estimating surface turbulent heat fluxes from land surface temperature and soil moisture observations using the particle batch smoother

    Science.gov (United States)

    Lu, Yang; Dong, Jianzhi; Steele-Dunne, Susan C.; van de Giesen, Nick

    2016-11-01

    Surface heat fluxes interact with the overlying atmosphere and play a crucial role in meteorology, hydrology, and climate change studies, but in situ observations are costly and difficult. It has been demonstrated that surface heat fluxes can be estimated from assimilation of land surface temperature (LST). One approach is to estimate a neutral bulk heat transfer coefficient (CHN) to scale the sum of turbulent heat fluxes, and an evaporative fraction (EF) that represents the partitioning between fluxes. Here the newly developed particle batch smoother (PBS) is implemented. The PBS makes no assumptions about the prior distributions and is therefore well-suited for non-Gaussian processes. It is also particularly advantageous for parameter estimation by tracking the entire prior distribution of parameters using Monte Carlo sampling. To improve the flux estimation on wet or densely vegetated surfaces, a simple soil moisture scheme is introduced to further constrain EF, and soil moisture observations are assimilated simultaneously. This methodology is implemented with the FIFE 1987 and 1988 data sets. Validation against observed fluxes indicates that assimilating LST using the PBS significantly improves the flux estimates at both daily and half-hourly timescales. When soil moisture is assimilated, the estimated EFs become more accurate, particularly when the surface heat flux partitioning is energy-limited. The feasibility of extending the methodology to use remote sensing observations is tested by limiting the number of LST observations. Results show that flux estimates are greatly improved after assimilating soil moisture, particularly when LST observations are sparse.

  20. Using microwave observations to estimate land surface temperature during cloudy conditions

    Science.gov (United States)

    Land surface temperature (LST), a key ingredient for physically-based retrieval algorithms of hydrological states and fluxes, remains a poorly constrained parameter for global scale studies. The main two observational methods to remotely measure T are based on thermal infrared (TIR) observations and...

  1. A MODELING APPROACH FOR ESTIMATING WATERSHED IMPERVIOUS SURFACE AREA FROM NATIONAL LAND COVER DATA 92

    Science.gov (United States)

    We used National Land Cover Data 92 (NLCD92), vector impervious surface data, and raster GIS overlay methods to derive impervious surface coefficients per NLCD92 class in portions of the Nfid-Atlantic physiographic region. The methods involve a vector to raster conversion of the ...

  2. Capabilities and limitations of Landsat and land cover data for aboveground woody biomass estimation of Uganda

    NARCIS (Netherlands)

    Avitabile, V.; Baccini, A.; Friedl, M.A.; Schmullius, C.

    2012-01-01

    Aboveground woody biomass for circa-2000 is mapped at national scale in Uganda at 30-m spatial resolution on the basis of Landsat ETM + images, a National land cover dataset and field data using an object-oriented approach. A regression tree-based model (Random Forest) produces good results (cross-v

  3. Implications of some early Jewish sources for estimates of earthquake hazardin the Holy Land

    Directory of Open Access Journals (Sweden)

    I. Karcz

    2004-06-01

    Full Text Available For the past two millennia the Holy Land was under the yoke of successive invaders and oppressors, not a fertile ground for growth of historiographic traditions. Consequently, earthquake cataloguers had to rely largely on chronicles and texts written at distant administrative and cultural centers of the day, where earthquake destruction suffered by a culturally and economically depressed province may have been overshadowed by damage in more important parts of the empire. On this assumption, and aided by an implicit notion that the lands bounded by the Dead Sea Rift and Anatolian Fault systems are seismically contiguous, early cataloguers often extended the impact of earthquakes documented in nearby East Mediterranean countries to the Holy Land. Once published, such reports of supposed destructive intensities in Israel were used by Judaic scholars and archaeologists to date poorly defined, often metaphoric, literary seismic echoes, and to justify assigning seismic origin to equivocal signs of damage, asymmetry, or abandonment at archaeological sites of corresponding age. The spread of damage and intensity portraits are therefore enhanced and distorted, and so is their application in palaeoseismic analysis. Four test cases are presented, illustrating the use and misuse of local Judaic sources in identifying destructive intensities supposedly generated in the Holy Land by earthquakes of 92 B.C., 64 B.C. and 31 B.C., and in postulating a regional seismic catastrophe in 749 A.D..

  4. High resolution land surface geophysical parameters estimation from ALOS PALSAR data

    Science.gov (United States)

    High resolution land surface geophysical products, such as soil moisture, surface roughness and vegetation water content, are essential for a variety of applications ranging from water management to regional climate predictions. In India high resolution geophysical products, in particular soil moist...

  5. Estimating land-surface temperature under clouds using MSG/SEVIRI observations

    NARCIS (Netherlands)

    Lu, L.; Venus, V.; Skidmore, A.K.; Wang, T.; Luo, G.

    2011-01-01

    The retrieval of land-surface temperature (LST) from thermal infrared satellite sensor observations is known to suffer from cloud contamination. Hence few studies focus on LST retrieval under cloudy conditions. In this paper a temporal neighboring-pixel approach is presented that reconstructs the di

  6. Using NOAA-AVHRR estimates of land surface temperature for regional agrometeoro[lo]gical modelling

    NARCIS (Netherlands)

    Wit, de A.J.W.; Boogaard, H.L.; Diepen, van C.A.

    2004-01-01

    This paper presents a case study on the use of features derived from remote sensing data for mapping the highly fragmented semideciduous Atlantic forest in Brazil. Innovative aspects of this research include the evaluation of different feature sets in order to improve land cover mapping. The feature

  7. Satellite detection of land-use change and effects on regional forest aboveground biomass estimates

    Science.gov (United States)

    Daolan Zheng; Linda S. Heath; Mark J. Ducey

    2008-01-01

    We used remote-sensing-driven models to detect land-cover change effects on forest aboveground biomass (AGB) density (Mg·ha−1, dry weight) and total AGB (Tg) in Minnesota, Wisconsin, and Michigan USA, between the years 1992-2001, and conducted an evaluation of the approach. Inputs included remotely-sensed 1992 reflectance data...

  8. Estimating land-surface temperature under clouds using MSG/SEVIRI observations

    NARCIS (Netherlands)

    Lu, L.; Venus, V.; Skidmore, A.K.; Wang, T.; Luo, G.

    2011-01-01

    The retrieval of land-surface temperature (LST) from thermal infrared satellite sensor observations is known to suffer from cloud contamination. Hence few studies focus on LST retrieval under cloudy conditions. In this paper a temporal neighboring-pixel approach is presented that reconstructs the

  9. MAPPING SPATIAL ACCURACY AND ESTIMATING LANDSCAPE INDICATORS FROM THEMATIC LAND COVER MAPS USING FUZZY SET THEORY

    Science.gov (United States)

    This paper presents a fuzzy set-based method of mapping spatial accuracy of thematic map and computing several ecological indicators while taking into account spatial variation of accuracy associated with different land cover types and other factors (e.g., slope, soil type, etc.)...

  10. Doppler shift estimation for GNSS reflectometry using a land topography adapted reflection model

    Science.gov (United States)

    Semmling, Maximilian; Peraza, Luis; Falck, Carsten; Gerland, Sebastian; Wickert, Jens

    2016-04-01

    A GNSS setup with a receiver capable for reflectometry is operated by GFZ at Kongsfjorden (Spitsbergen), 78°54'14''N, 11°52'37''E, 512 m above ellipsoid (WGS-84). This permanent station at the Zeppelin mountain outpost, operated by the Norwegian Polar Institute (NPI), accumulates data since Summer 2013 observing reflections over the fjord and the adjacent land surface. Especially the presence of sea ice over the fjord and snow cover over land are of interest for reflectometry to investigate altimetry and remote sensing applications. The setup contains a GORS (GNSS Occultation Reflectometry Scatterometry) two-frontend receiver, which is based on commercial JAVAD hardware. The receiver is connected to one up-looking and one horizon-looking patch antenna with right-handed and left-handed circular polarization, respectively. Both antennas are installed on the same mount approximately 475 m above the fjord mean sea level. Reflections are observed at low transmitter elevation angles (between 10 and 2°). For these geometries the relative Doppler shift (sea surface reflected relative to direct signal) is almost constant 0.5 to 0.6 Hz and can be calculated with an established reflection model. Rather easily, sea surface reflections are identified in the data and the corresponding reflection points are located. About 55 daily recurring reflection events over the fjord are observed. They form a fan-shaped swath with 3 to 13 km distance around the receiver, corresponding to elevations of 10° to 2°. Also signatures of potential land reflections are found in the data. About 13 daily recurring events extend mainly over land. The potential land signatures have a rather variable Doppler shift between 0.2 to 1Hz. The significant topography of the mountainous surrounding, which varies between sea level and 900 m altitude, prevents the use of established reflection models. A topography adapted reflection model, which considers sloped surface facets, is developed. It incorporates

  11. Estimation of the Total Atmospheric Water Vapor Content and Land Surface Temperature Based on AATSR Thermal Data

    Directory of Open Access Journals (Sweden)

    Rong Liu

    2008-03-01

    Full Text Available The total atmospheric water vapor content (TAWV and land surfacetemperature (LST play important roles in meteorology, hydrology, ecology and some otherdisciplines. In this paper, the ENVISAT/AATSR (The Advanced Along-Track ScanningRadiometer thermal data are used to estimate the TAWV and LST over the Loess Plateauin China by using a practical split window algorithm. The distribution of the TAWV isaccord with that of the MODIS TAWV products, which indicates that the estimation of thetotal atmospheric water vapor content is reliable. Validations of the LST by comparingwith the ground measurements indicate that the maximum absolute derivation, themaximum relative error and the average relative error is 4.0K, 11.8% and 5.0%respectively, which shows that the retrievals are believable; this algorithm can provide anew way to estimate the LST from AATSR data.

  12. Land Surface Temperature Retrieval in Wetlands Using Normalized Difference Vegetation Index-Emissivity Estimation and ASTER Emissivity Product

    Science.gov (United States)

    Muro, Javier; Heinmann, Sascha; Strauch, Adrian; Menz, Gunter

    2016-08-01

    Land Surface Temperature (LST) has the potential to act as a continuous indicator of the ecological status of wetlands. Accurate emissivity values are required in order to calculate precise LST. We test two emissivity retrieval methods and their influence on LST calculated from a Landsat 7 image of a highly dynamic wetland in Southern Spain. LST calculated using NDVI (Normalized Difference Vegetation Index) threshold estimations and the ASTER emissivity product are compared. The results show differences of around 0-1 K for most land covers, and up to 3 K for areas of bare soil when Landsat and ASTER images have the same acquisition date. Tests using Landsat and ASTER images from different seasons do not show greater differences between both LSTs. This has important implications for automated LST retrieval methods, such as the one planed by the USGS using Landsat and ASTER emissivity products.

  13. Rainfall estimation over-land using SMOS soil moisture observations: SM2RAIN, LMAA and SMART algorithms

    Science.gov (United States)

    Massari, Christian; Brocca, Luca; Pellarin, Thierry; Kerr, Yann; Crow, Wade; Cascon, Carlos; Ciabatta, Luca

    2016-04-01

    Recent advancements in the measurement of precipitation from space have provided estimates at scales that are commensurate with the needs of the hydrological and land-surface model communities. However, as demonstrated in a number of studies (Ebert et al. 2007, Tian et al. 2007, Stampoulis et al. 2012) satellite rainfall estimates are characterized by low accuracy in certain conditions and still suffer from a number of issues (e.g., bias) that may limit their utility in over-land applications (Serrat-Capdevila et al. 2014). In recent years many studies have demonstrated that soil moisture observations from ground and satellite sensors can be used for correcting satellite precipitation estimates (e.g. Crow et al., 2011; Pellarin et al., 2013), or directly estimating rainfall (SM2RAIN, Brocca et al., 2014). In this study, we carried out a detailed scientific analysis in which these three different methods are used for: i) estimating rainfall through satellite soil moisture observations (SM2RAIN, Brocca et al., 2014); ii) correcting rainfall through a Land surface Model Assimilation Algorithm (LMAA) (an improvement of a previous work of Crow et al. 2011 and Pellarin et al. 2013) and through the Soil Moisture Analysis Rainfall Tool (SMART, Crow et al. 2011). The analysis is carried within the ESA project "SMOS plus Rainfall" and involves 9 sites in Europe, Australia, Africa and USA containing high-quality hydrometeorological and soil moisture observations. Satellite soil moisture data from Soil Moisture and Ocean Salinity (SMOS) mission are employed for testing their potential in deriving a cumulated rainfall product at different temporal resolutions. The applicability and accuracy of the three algorithms is investigated also as a function of climatic and soil/land use conditions. A particular attention is paid to assess the expected limitations soil moisture based rainfall estimates such as soil saturation, freezing/snow conditions, SMOS RFI, irrigated areas

  14. Estimation of Land Surface Temperature under Cloudy Skies Using Combined Diurnal Solar Radiation and Surface Temperature Evolution

    Directory of Open Access Journals (Sweden)

    Xiaoyu Zhang

    2015-01-01

    Full Text Available Land surface temperature (LST is a key parameter in the interaction of the land-atmosphere system. However, clouds affect the retrieval of LST data from thermal-infrared remote sensing data. Thus, it is important to determine a method for estimating LSTs at times when the sky is overcast. Based on a one-dimensional heat transfer equation and on the evolution of daily temperatures and net shortwave solar radiation (NSSR, a new method for estimating LSTs under cloudy skies (Tcloud from diurnal NSSR and surface temperatures is proposed. Validation is performed against in situ measurements that were obtained at the ChangWu ecosystem experimental station in China. The results show that the root-mean-square error (RMSE between the actual and estimated LSTs is as large as 1.23 K for cloudy data. A sensitivity analysis to the errors in the estimated LST under clear skies (Tclear and in the estimated NSSR reveals that the RMSE of the obtained Tcloud is less than 1.5 K after adding a 0.5 K bias to the actual Tclear and 10 percent NSSR errors to the actual NSSR. Tcloud is estimated by the proposed method using Tclear and NSSR products of MSG-SEVIRI for southern Europe. The results indicate that the new algorithm is practical for retrieving the LST under cloudy sky conditions, although some uncertainty exists. Notably, the approach can only be used during the daytime due to the assumption of the variation in LST caused by variations in insolation. Further, if there are less than six Tclear observations on any given day, the method cannot be used.

  15. What do moisture recycling estimates tell? Lessons from an extreme global land-cover change model experiment

    Directory of Open Access Journals (Sweden)

    H. F. Goessling

    2011-04-01

    Full Text Available Moisture evaporated from the continents (recycled moisture contributes up to 80% to the total atmospheric moisture content and, hence, precipitation in some regions. Recycling estimates are traditionally used to indicate a region's rainfall-dependence on land-surface evaporation. Accordingly, recycling estimates are employed to deduce the hydrological consequences of land-cover change. However, moisture is not a passive but an active constituent of the atmosphere. Recent studies indicate that at small scales (up to 1000 km local to regional evaporation-precipitation coupling by far dominates the atmospheric precipitation response, while the water-balance effect from moisture recycling in the traditional sense seems to be of minor importance. The value of moisture recycling estimates as indicator for consequences of land-cover change is therefore questionable. However, since atmospheric moisture is still subject to mass conservation, the relevance of moisture recycling may come into play at the continental scale.

    To explore the relevance of recycling estimates regarding land-cover change at the continental scale, we conduct two global experiments with an atmospheric general circulation model: (I with present-day conditions and (II with extreme land-cover change conditions, namely with totally suppressed continental evaporation. Using the simulated fields of moisture, wind, and evaporation from the present-day experiment, we quantify continental moisture recycling with a vertically integrating tracing scheme. We then compare the computed recycling patterns with the hydrological changes that follow the suppression of continental evaporation.

    While under present-day conditions the fraction of recycled moisture increases from continental upstream to downstream regions with respect to the prevailing winds, the suppression of continental evaporation leads to severe precipitation loss in almost all continental regions, no matter if

  16. The Walk Poem.

    Science.gov (United States)

    Padgett, Ron

    2000-01-01

    Discusses the long history of writing poems about a walk, noting many titles. Notes four basic types of walk poems and includes one by American poet Bill Zavatksy, called "Class Walk With Notebooks After Storm." Offers numerous brief ideas for both the writing and the form of walk poems. (SR)

  17. Walking, places and wellbeing

    NARCIS (Netherlands)

    Ettema, Dick; Smajic, Ifeta

    2015-01-01

    While there is a substantial body of research on the health implications of walking, the physical, emotional and social outcomes of walking have received limited attention. This paper explores the wellbeing effects of walking and how the walking environment fosters or hinders such wellbeing effects.

  18. Walking, places and wellbeing

    NARCIS (Netherlands)

    Ettema, Dick; Smajic, Ifeta

    2015-01-01

    While there is a substantial body of research on the health implications of walking, the physical, emotional and social outcomes of walking have received limited attention. This paper explores the wellbeing effects of walking and how the walking environment fosters or hinders such wellbeing effects.

  19. Quantitative Estimation of Soil Carbon Sequestration in Three Land Use Types (Orchard, Paddy Rice and Forest in a Part of Ramsar Lands, Northern Iran

    Directory of Open Access Journals (Sweden)

    zakieh pahlavan yali

    2017-02-01

    Full Text Available Introduction: The increasing Greenhouse Gases in atmosphere is the main cause of climate and ecosystems changes. The most important greenhouse gas is CO2 that causes global warming or the greenhouse effect. One of the known solutions that reduces atmospheric carbon and helps to improve the situation, is carbon sequestration in vegetation cover and soil. Carbon sequestration refers to the change in atmospheric CO2 into organic carbon compounds by plants and capture it for a certain time . However, the ecosystems with different vegetation have Impressive Influence on soil carbon sequestration (SCS. Soil as the main component of these ecosystems is a world-wide indicator which has been known to play an important role in global balance of carbon sequestration. Furthermore, carbon sequestration can be a standard world trade and becomes guaranteed. Costs of transfer of CO2 (carbon transfer From the atmosphere into the soil based on the negative effects of increased CO2 on Weather is always increasing, This issue can be faced by developing countries to create a new industry, especially when conservation and restoration of rangeland to follow. This research was regarded due to estimation of SCS in three land use types (orchard, paddy rice and forest in a Part of Ramsar Lands, Northern Iran. Materials and Methods: Ramsar city with an area of about 729/7 km2 is located in the western part of Mazandaran province. Its height above sea level is 20 meters. Ramsar city is situated in a temperate and humid climate. Land area covered by forest, orchard and paddy rice. After field inspection of the area, detailed topographic maps of the specified zone on the study were also tested. In each of the three land types, 500 hectares in the every growing and totally 1,500 hectares as study area were selected .For evaluation the sequestration of carbon in different vegetation systems,15 soil profile selected and sampling from depth of 0 to 100 centimetres of each profile

  20. Understanding the Effect of Land Cover Classification on Model Estimates of Regional Carbon Cycling in the Boreal Forest Biome

    Science.gov (United States)

    Kimball, John; Kang, Sinkyu

    2003-01-01

    The original objectives of this proposed 3-year project were to: 1) quantify the respective contributions of land cover and disturbance (i.e., wild fire) to uncertainty associated with regional carbon source/sink estimates produced by a variety of boreal ecosystem models; 2) identify the model processes responsible for differences in simulated carbon source/sink patterns for the boreal forest; 3) validate model outputs using tower and field- based estimates of NEP and NPP; and 4) recommend/prioritize improvements to boreal ecosystem carbon models, which will better constrain regional source/sink estimates for atmospheric C02. These original objectives were subsequently distilled to fit within the constraints of a 1 -year study. This revised study involved a regional model intercomparison over the BOREAS study region involving Biome-BGC, and TEM (A.D. McGuire, UAF) ecosystem models. The major focus of these revised activities involved quantifying the sensitivity of regional model predictions associated with land cover classification uncertainties. We also evaluated the individual and combined effects of historical fire activity, historical atmospheric CO2 concentrations, and climate change on carbon and water flux simulations within the BOREAS study region.

  1. Estimates of land in agricultural production in counties in the conterminous United States as reported in the 1987 Census of Agriculture

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This coverage contains estimates of land in agricultural production in counties in the conterminous United States as reported in the 1987 Census of Agriculture (U.S....

  2. Crop Frequency Mapping for Land Use Intensity Estimation During Three Decades

    Science.gov (United States)

    Schmidt, Michael; Tindall, Dan

    2016-08-01

    Crop extent and frequency maps are an important input to inform the debate around land value and competitive land uses, food security and sustainability of agricultural practices. Such spatial datasets are likely to support decisions on natural resource management, planning and policy. The complete Landsat Time Series (LTS) archive for 23 Landsat footprints in western Queensland from 1987 to 2015 was used in a multi-temporal mapping approach. Spatial, spectral and temporal information were combined in multiple crop-modelling steps, supported by on ground training data sampled across space and time for the classes Crop and No-Crop. Temporal information within summer and winter growing seasons for each year were summarised, and combined with various vegetation indices and band ratios computed from a mid-season spectral-composite image. All available temporal information was spatially aggregated to the scale of image segments in the mid- season composite for each growing season and used to train a random forest classifier for a Crop and No- Crop classification. Validation revealed that the predictive accuracy varied by growing season and region to be within k = 0.88 to 0.97 and are thus suitable for mapping current and historic cropping activity. Crop frequency maps were produced for all regions at different time intervals. The crop frequency maps were validated separately with a historic crop information time series. Different land use intensities and conversions e.g. from agricultural to pastures are apparent and potential drivers of these conversions are discussed.

  3. Using a Support Vector Machine and a Land Surface Model to Estimate Large-Scale Passive Microwave Temperatures over Snow-Covered Land in North America

    Science.gov (United States)

    Forman, Barton A.; Reichle, Rolf Helmut

    2014-01-01

    A support vector machine (SVM), a machine learning technique developed from statistical learning theory, is employed for the purpose of estimating passive microwave (PMW) brightness temperatures over snow-covered land in North America as observed by the Advanced Microwave Scanning Radiometer (AMSR-E) satellite sensor. The capability of the trained SVM is compared relative to the artificial neural network (ANN) estimates originally presented in [14]. The results suggest the SVM outperforms the ANN at 10.65 GHz, 18.7 GHz, and 36.5 GHz for both vertically and horizontally-polarized PMW radiation. When compared against daily AMSR-E measurements not used during the training procedure and subsequently averaged across the North American domain over the 9-year study period, the root mean squared error in the SVM output is 8 K or less while the anomaly correlation coefficient is 0.7 or greater. When compared relative to the results from the ANN at any of the six frequency and polarization combinations tested, the root mean squared error was reduced by more than 18 percent while the anomaly correlation coefficient was increased by more than 52 percent. Further, the temporal and spatial variability in the modeled brightness temperatures via the SVM more closely agrees with that found in the original AMSR-E measurements. These findings suggest the SVM is a superior alternative to the ANN for eventual use as a measurement operator within a data assimilation framework.

  4. Joint State and Parameter Estimation for Two Land Surface Models Using the Ensemble Kalman Filter and Particle Filter

    Science.gov (United States)

    Zhang, Hongjuan; Hendricks-Franssen, Harrie-Jan; Han, Xujun; Vrugt, Jasper A.; Vereecken, Harry

    2016-04-01

    Land surface models (LSMs) resolve the water and energy balance with different parameters and state variables. Many of the parameters of these models cannot be measured directly in the field, and require calibration against flux and soil moisture data. Two LSMs are used in our work: Variable Infiltration Capacity Hydrologic Model (VIC) and the Community Land Model (CLM). Temporal variations in soil moisture content at 5, 20 and 50 cm depth in the Rollesbroich experimental watershed in Germany are simulated in both LSMs. Data assimilation (DA) provides a good way to jointly estimate soil moisture content and soil properties of the resolved soil domain. Four DA methods combined with the two LSMs are used in our work: the Ensemble Kalman Filter (EnKF) using state augmentation or dual estimation, the Residual Resampling Particle Filter (RRPF) and Markov chain Monte Carlo Particle Filter (MCMCPF). These four DA methods are tuned and calibrated for a five month period, and subsequently evaluated for another five month period. Performances of the two LSMs and the four DA methods are compared. Our results show that all DA methods improve the estimation of soil moisture content of the VIC and CLM models, especially if the soil hydraulic properties (VIC), the maximum baseflow velocity (VIC) and/or soil texture (CLM) are jointly estimated with soil moisture content. The augmentation and dual estimation methods performed slightly better than RRPF and MCMCPF in the evaluation period. The differences in simulated soil moisture content between CLM and VIC were larger than variations among the DA methods. The CLM performed better than the VIC model. The strong underestimation of soil moisture content in the third layer of the VIC model is likely related to an inadequate parameterization of groundwater drainage.

  5. Fire-Walking

    Science.gov (United States)

    Willey, David

    2010-01-01

    This article gives a brief history of fire-walking and then deals with the physics behind fire-walking. The author has performed approximately 50 fire-walks, took the data for the world's hottest fire-walk and was, at one time, a world record holder for the longest fire-walk (www.dwilley.com/HDATLTW/Record_Making_Firewalks.html). He currently…

  6. Fire-Walking

    Science.gov (United States)

    Willey, David

    2010-01-01

    This article gives a brief history of fire-walking and then deals with the physics behind fire-walking. The author has performed approximately 50 fire-walks, took the data for the world's hottest fire-walk and was, at one time, a world record holder for the longest fire-walk (www.dwilley.com/HDATLTW/Record_Making_Firewalks.html). He currently…

  7. The sensitivity of land emissivity estimates from AMSR-E at C and X bands to surface properties

    Directory of Open Access Journals (Sweden)

    H. Norouzi

    2011-11-01

    Full Text Available Microwave observations at low frequencies exhibit more sensitivity to surface and subsurface properties with little interference from the atmosphere. The objective of this study is to develop a global land emissivity product using passive microwave observations from the Advanced Microwave Scanning Radiometer – Earth Observing System (AMSR-E and to investigate its sensitivity to land surface properties. The developed product complements existing land emissivity products from SSM/I and AMSU by adding land emissivity estimates at two lower frequencies, 6.9 and 10.65 GHz (C- and X-band, respectively. Observations at these low frequencies penetrate deeper into the soil layer. Ancillary data used in the analysis, such as surface skin temperature and cloud mask, are obtained from International Satellite Cloud Climatology Project (ISCCP. Atmospheric properties are obtained from the TIROS Operational Vertical Sounder (TOVS observations to determine the small upwelling and downwelling atmospheric emissions as well as the atmospheric transmission. A sensitivity test confirms the small effect of the atmosphere but shows that skin temperature accuracy can significantly affect emissivity estimates. Retrieved emissivities at C- and X-bands and their polarization differences exhibit similar patterns of variation with changes in land cover type, soil moisture, and vegetation density as seen at SSM/I-like frequencies (Ka and Ku bands. The emissivity maps from AMSR-E at these higher frequencies agree reasonably well with the existing SSM/I-based product. The inherent discrepancy introduced by the difference between SSM/I and AMSR-E frequencies, incidence angles, and calibration has been assessed. Significantly greater standard deviation of estimated emissivities compared to SSM/I land emissivity product was found over desert regions. Large differences between emissivity estimates from ascending and descending overpasses were found at lower frequencies due to the

  8. Mapping land water and energy balance relations through conditional sampling of remote sensing estimates of atmospheric forcing and surface states

    Science.gov (United States)

    Farhadi, Leila; Entekhabi, Dara; Salvucci, Guido

    2016-04-01

    In this study, we develop and apply a mapping estimation capability for key unknown parameters that link the surface water and energy balance equations. The method is applied to the Gourma region in West Africa. The accuracy of the estimation method at point scale was previously examined using flux tower data. In this study, the capability is scaled to be applicable with remotely sensed data products and hence allow mapping. Parameters of the system are estimated through a process that links atmospheric forcing (precipitation and incident radiation), surface states, and unknown parameters. Based on conditional averaging of land surface temperature and moisture states, respectively, a single objective function is posed that measures moisture and temperature-dependent errors solely in terms of observed forcings and surface states. This objective function is minimized with respect to parameters to identify evapotranspiration and drainage models and estimate water and energy balance flux components. The uncertainty of the estimated parameters (and associated statistical confidence limits) is obtained through the inverse of Hessian of the objective function, which is an approximation of the covariance matrix. This calibration-free method is applied to the mesoscale region of Gourma in West Africa using multiplatform remote sensing data. The retrievals are verified against tower-flux field site data and physiographic characteristics of the region. The focus is to find the functional form of the evaporative fraction dependence on soil moisture, a key closure function for surface and subsurface heat and moisture dynamics, using remote sensing data.

  9. Use of field and laboratory methods for estimating unsaturated hydraulic properties under different land uses

    Science.gov (United States)

    Siltecho, S.; Hammecker, C.; Sriboonlue, V.; Clermont-Dauphin, C.; Trelo-ges, V.; Antonino, A. C. D.; Angulo-Jaramillo, R.

    2015-03-01

    Adequate water management is required to improve the efficiency and sustainability of agricultural systems when water is scarce or over-abundant, especially in the case of land use changes. In order to quantify, to predict and eventually to control water and solute transport into soil, soil hydraulic properties need to be determined precisely. As their determination is often tedious, expensive and time-consuming, many alternative field and laboratory techniques are now available. The aim of this study was to determine unsaturated soil hydraulic properties under different land uses and to compare the results obtained with different measurement methods (Beerkan, disc infiltrometer, evaporation, pedotransfer function). The study has been realized on a tropical sandy soil in a mini-watershed in northeastern Thailand. The experimental plots were positioned in a rubber tree plantation in different positions along a slope, in ruzi grass pasture and in an original forest site. Non-parametric statistics demonstrated that van Genuchten unsaturated soil parameters (Ks, α and n) were significantly different according to the measurement methods employed, whereas the land use was not a significant discriminating factor when all methods were considered together. However, within each method, parameters n and α were statistically different according to the sites. These parameters were used with Hydrus1D for a 1-year simulation and computed pressure head did not show noticeable differences for the various sets of parameters, highlighting the fact that for modeling, any of these measurement methods could be employed. The choice of the measurement method would therefore be motivated by the simplicity, robustness and its low cost.

  10. Optimal Parameter and Uncertainty Estimation of a Land Surface Model: Sensitivity to Parameter Ranges and Model Complexities

    Institute of Scientific and Technical Information of China (English)

    Youlong XIA; Zong-Liang YANG; Paul L. STOFFA; Mrinal K. SEN

    2005-01-01

    Most previous land-surface model calibration studies have defined global ranges for their parameters to search for optimal parameter sets. Little work has been conducted to study the impacts of realistic versus global ranges as well as model complexities on the calibration and uncertainty estimates. The primary purpose of this paper is to investigate these impacts by employing Bayesian Stochastic Inversion (BSI)to the Chameleon Surface Model (CHASM). The CHASM was designed to explore the general aspects of land-surface energy balance representation within a common modeling framework that can be run from a simple energy balance formulation to a complex mosaic type structure. The BSI is an uncertainty estimation technique based on Bayes theorem, importance sampling, and very fast simulated annealing.The model forcing data and surface flux data were collected at seven sites representing a wide range of climate and vegetation conditions. For each site, four experiments were performed with simple and complex CHASM formulations as well as realistic and global parameter ranges. Twenty eight experiments were conducted and 50 000 parameter sets were used for each run. The results show that the use of global and realistic ranges gives similar simulations for both modes for most sites, but the global ranges tend to produce some unreasonable optimal parameter values. Comparison of simple and complex modes shows that the simple mode has more parameters with unreasonable optimal values. Use of parameter ranges and model complexities have significant impacts on frequency distribution of parameters, marginal posterior probability density functions, and estimates of uncertainty of simulated sensible and latent heat fluxes.Comparison between model complexity and parameter ranges shows that the former has more significant impacts on parameter and uncertainty estimations.

  11. Improved estimates of global sea level change from Ice Sheets, glaciers and land water storage using GRACE

    Science.gov (United States)

    Velicogna, I.; Hsu, C. W.; Ciraci, E.; Sutterley, T. C.

    2015-12-01

    We use observations of time variable gravity from GRACE to estimate mass changes for the Antarctic and Greenland Ice Sheets, the Glaciers and Ice Caps (GIC) and land water storage for the time period 2002-2015 and evaluate their total contribution to sea level. We calculate regional sea level changes from these present day mass fluxes using an improved scaling factor for the GRACE data that accounts for the spatial and temporal variability of the observed signal. We calculate a separate scaling factor for the annual and the long-term components of the GRACE signal. To estimate the contribution of the GIC, we use a least square mascon approach and we re-analyze recent inventories to optimize the distribution of mascons and recover the GRACE signal more accurately. We find that overall, Greenland controls 43% of the global trend in eustatic sea level rise, 16% for Antarctica and 29% for the GIC. The contribution from the GIC is dominated by the mass loss of the Canadian Arctic Archipelago, followed by Alaska, Patagonia and the High Mountains of Asia. We report a marked increase in mass loss for the Canadian Arctic Archipelago. In Greenland, following the 2012 high summer melt, years 2013 and 2014 have slowed down the increase in mass loss, but our results will be updated with summer 2015 observations at the meeting. In Antarctica, the mass loss is still on the rise with increased contributions from the Amundsen Sea sector and surprisingly from the Wilkes Land sector of East Antarctica, including Victoria Land. Conversely, the Queen Maud Land sector experienced a large snowfall in 2009-2013 and has now resumed to a zero mass gain since 2013. We compare sea level changes from these GRACE derived mass fluxes after including the atmospheric and ocean loading signal with sea level change from satellite radar altimetry (AVISO) corrected for steric signal of the ocean using Argo measurements and find an excellent agreement in amplitude, phase and trend in these estimates

  12. Model estimation of land-use effects on water levels of northern prairie wetlands.

    Science.gov (United States)

    Voldseth, Richard A; Johnson, W Carter; Gilmanov, Tagir; Guntenspergen, Glenn R; Millett, Bruce V

    2007-03-01

    Wetlands of the Prairie Pothole Region exist in a matrix of grassland dominated by intensive pastoral and cultivation agriculture. Recent conservation management has emphasized the conversion of cultivated farmland and degraded pastures to intact grassland to improve upland nesting habitat. The consequences of changes in land-use cover that alter watershed processes have not been evaluated relative to their effect on the water budgets and vegetation dynamics of associated wetlands. We simulated the effect of upland agricultural practices on the water budget and vegetation of a semipermanent prairie wetland by modifying a previously published mathematical model (WETSIM). Watershed cover/land-use practices were categorized as unmanaged grassland (native grass, smooth brome), managed grassland (moderately heavily grazed, prescribed burned), cultivated crops (row crop, small grain), and alfalfa hayland. Model simulations showed that differing rates of evapotranspiration and runoff associated with different upland plant-cover categories in the surrounding catchment produced differences in wetland water budgets and linked ecological dynamics. Wetland water levels were highest and vegetation the most dynamic under the managed-grassland simulations, while water levels were the lowest and vegetation the least dynamic under the unmanaged-grassland simulations. The modeling results suggest that unmanaged grassland, often planted for waterfowl nesting, may produce the least favorable wetland conditions for birds, especially in drier regions of the Prairie Pothole Region. These results stand as hypotheses that urgently need to be verified with empirical data.

  13. Optimal estimation of areal values of near-land-surface temperatures for testing global and local spatio-temporal trends

    Science.gov (United States)

    Wang, Hong; Pardo-Igúzquiza, Eulogio; Dowd, Peter A.; Yang, Yongguo

    2017-09-01

    This paper provides a solution to the problem of estimating the mean value of near-land-surface temperature over a relatively large area (here, by way of example, applied to mainland Spain covering an area of around half a million square kilometres) from a limited number of weather stations covering a non-representative (biased) range of altitudes. As evidence mounts for altitude-dependent global warming, this bias is a significant problem when temperatures at high altitudes are under-represented. We correct this bias by using altitude as a secondary variable and using a novel clustering method for identifying geographical regions (clusters) that maximize the correlation between altitude and mean temperature. In addition, the paper provides an improved regression kriging estimator, which is optimally determined by the cluster analysis. The optimal areal values of near-land-surface temperature are used to generate time series of areal temperature averages in order to assess regional changes in temperature trends. The methodology is applied to records of annual mean temperatures over the period 1950-2011 across mainland Spain. The robust non-parametric Theil-Sen method is used to test for temperature trends in the regional temperature time series. Our analysis shows that, over the 62-year period of the study, 78% of mainland Spain has had a statistically significant increase in annual mean temperature.

  14. Sea-Level Rise and Land Subsidence in Deltas: Estimating Future Flood Risk Through Integrated Natural and Human System Modeling

    Science.gov (United States)

    Tessler, Z. D.; Vorosmarty, C. J.

    2016-12-01

    Deltas are highly sensitive to local human activities, land subsidence, regional water management, global sea-level rise, and climate extremes. We present a new delta flood exposure and risk framework for estimating the sensitivity of deltas to relative sea-level rise. We have applied this framework to a set of global environmental, geophysical, and social indicators over 48 major river deltas to quantify how contemporary risks vary across delta systems. The risk modeling framework incorporates upstream sediment flux and coastal land subsidence models, global empirical estimates of contemporary storm surge exposure, and population distribution and growth. Future scenarios are used to test the impacts on coastal flood risk of upstream dam construction, coastal population growth, accelerated sea-level rise, and enhanced storm surge. Results suggest a wide range of outcomes across different delta systems within each scenario. Deltas in highly engineered watersheds (Mississippi, Rhine) exhibit less sensitivity to increased dams due to saturation of sediment retention effects, though planned or under-construction dams are expected to have a substantial impact in the Yangtze, Irrawaddy, and Magdalena deltas. Population growth and sea-level rise are expected to be the dominant drivers of increased human risk in most deltas, with important exceptions in several countries, particularly China, where population are forecast to contract over the next several decades.

  15. Land leveling impact on surface runoff and soil losses: Estimation with coupled deterministic/stochastic models for a Québec agricultural field

    Science.gov (United States)

    Gagnon, Patrick; Chrétien, François; Thériault, Georges

    2017-01-01

    Land leveling impact on water quality had not received much attention for fields in humid continental climate. The objectives of this study were to isolate the impact of land leveling, performed on an agricultural field (Québec, Canada) in spring 2012, on runoff and TSS load and to make recommendations to attenuate adverse environmental impacts of land leveling, if any. A total of 66 runoff events, including 22 with total suspended sediments (TSS) load estimates, from 2010 to 2014 were analyzed. To this end, deterministic models were coupled to an adaptive Metropolis-Hastings algorithm to estimate the unknown distribution of the parameters representing the most important effects, namely land leveling, tillage, and crop cover. Simulated runoff events were generated by the hydrological model SWMM version 5 while simulated TSS loads were generated by an empirical equation based on the Revised Universal Soil Loss Equation version 2 (RUSLE2). Thanks to the algorithm used, it was demonstrated that land leveling significantly decreased total runoff volume at least for the two following years. The impact on peak flow was mixed: land leveling significantly decreased peak flow for a typical stratiform rainfall event but the effect was unclear for a typical convective rainfall event. Based on 90% confidence interval, TSS load increased from 10 to 1000 times immediately after land leveling (spring 2012) compared to pre-land leveling events. The TSS load increase remained significant one year after land leveling, with TSS loads 5-20 times higher compared to pre-land leveling events. It would thus be recommended to grow crops with high ground coverage ratios coupled with cover crops during the year when land leveling is done. Sediment retention structures could also be installed at the beginning of the land leveling process to provide protection against the short term and delayed impact on water quality.

  16. Estimation of land surface evaporation using a generalized nonlinear complementary relationship

    Science.gov (United States)

    Zhang, Lu; Cheng, Lei; Brutsaert, Wilfried

    2017-02-01

    Evaporation is a key component of the hydrological cycle and affects regional water resources. Although the physics of evaporation is well understood, its estimation in practice remains a challenge. Among available methods for estimating it, the complementary principle of Bouchet has the potential to provide a practical tool for regional water resources assessment. In this study, the generalized nonlinear formulation of this principle by Brutsaert (2015) was tested against evaporation measurements from four flux stations in Australia under different climatic and vegetation conditions. The method was implemented using meteorological data and Class A pan evaporation measurements. After calibration the estimated daily evaporation values were in good agreement with flux station measurements with a mean correlation coefficient of 0.83 and a bias of 4% on average. More accurate estimates of daily evaporation were obtained when the evaporative demand or apparent potential evaporation was determined from the Penman equation instead of from pan evaporation. The obtained parameter values were found to lie well within the ranges of reported values in the literature. Advantages of the method are that only routine meteorological data are required and that it can be used to estimate long-term evaporation trends.

  17. Estimation of land surface directional emissivity in mid-infrared channel around 4.0 microm from MODIS data.

    Science.gov (United States)

    Tang, Bo-Hui; Li, Zhao-Liang; Bi, Yuyun

    2009-03-01

    This work addressed the estimate of the directional emissivity in the mid-infrared (MIR) channel around 4.0 microm from MODIS data. A series of bidirectional reflectances in MODIS channel 22 (3.97 mum) were retrieved using the method developed by Tang and Li (Int. J. Remote Sens. 29, 4907, 2008) and then were used to estimate the directional emissivity in this channel with the aid of the BRDF model modified by Jiang and Li (Opt. Express 16, 19310, 2008). To validate the estimated directional emissivity, a cross-comparison of MODIS derived emissivities in channel 22 using the proposed method were performed with those provided by the MODIS land surface temperature/emissivity product MYD11B1 data. The results show that the proposed method for estimating the directional emissivity in MIR channel gives results comparable to those of MYD11B1 product with a Mean Error of -0.007 and a Root Mean Square Error of 0.024.

  18. Demarcation and Estimation of Agricultural Lands Using ETM+ Imagery Data (Case study: Astan Ghods Razavi Great Farm

    Directory of Open Access Journals (Sweden)

    F Alipour

    2014-09-01

    Full Text Available Application of satellite imagery and remote sensing techniques in agriculture and other natural resources has been approved by many studies. In this study two ETM+ imagery data for May and September 2012 of Astan Ghods Razavi Great Farm were acquired to identify the boundaries of lands cultivated with different crops coverage and to create crops maps of that farm. . To classify the images, the supervised classification methods including Maximum Likelihood and artificial neural network were used. In order to compare the results of two applied classification methods, the same training and testing samples were used. To evaluate the accuracy of classification results, the produced map was compared with the ground control points extracted by GPS and local observations. Kappa coefficient and overall accuracy were estimated to be 82% and 85%, respectively by maximum likelihood method and these outputs were estimated to be 84% and 87%, respectively by neural network approach. The difference of cultivated area estimated by maximum likelihood and by neural network methods with actual measured area was 16.8% and 14.2%, respectively. The results of this study showed that satellite imagery has high capabilities to classify and estimate agricultural and cultivated areas. These data can be useful for strategic management to develop mechanization and cultivation plans.

  19. Use of field and laboratory methods for estimating unsaturated hydraulic properties under different land-use

    Directory of Open Access Journals (Sweden)

    S. Siltecho

    2014-06-01

    Full Text Available Adequate water management is required to improve the efficiency and sustainability of agricultural systems when water is scarce or over-abundant, especially in the case of land-use changes. In order to quantify, to predict and eventually to control water and solute transport into soil, soil hydraulic properties need to be determined precisely. As their determination is often tedious, expensive and time-consuming, many alternative field and laboratory techniques are now available. The aim of this study was to determine unsaturated soil hydraulic properties under different land-uses and to compare the results obtained with different measurement methods (Beerkan, Disk infiltrometer, Evaporation, pedotransfer function. The study has been realised on a tropical sandy soil in a mini watershed in NE Thailand. The experimental plots were positioned in a rubber tree plantation in different positions along a slope, in ruzi grass pasture and in an original forest site. Non parametric statistics demonstrated that van Genuchten unsaturated soil parameters (Ks, α and n, were significantly different according to the measurement methods employed whereas location was not a significant discriminating factor when all methods were considered together. However within each method, parameters n and α were statistically different according to the sites. These parameters were used with Hydrus1D for a one year simulation and computed pressure head did not show noticeable differences for the various sets of parameters, highlighting the fact that for modelling, any of these measurement method could be employed. The choice of the measurement method would therefore be motivated by the simplicity, robustness and its low cost.

  20. Use of field and laboratory methods for estimating unsaturated hydraulic properties under different land-use

    Science.gov (United States)

    Siltecho, S.; Hammecker, C.; Sriboonlue, V.; Clermont-Dauphin, C.; Trelo-ges, V.; Antonino, A. C. D.; Angulo-Jaramillo, R.

    2014-06-01

    Adequate water management is required to improve the efficiency and sustainability of agricultural systems when water is scarce or over-abundant, especially in the case of land-use changes. In order to quantify, to predict and eventually to control water and solute transport into soil, soil hydraulic properties need to be determined precisely. As their determination is often tedious, expensive and time-consuming, many alternative field and laboratory techniques are now available. The aim of this study was to determine unsaturated soil hydraulic properties under different land-uses and to compare the results obtained with different measurement methods (Beerkan, Disk infiltrometer, Evaporation, pedotransfer function). The study has been realised on a tropical sandy soil in a mini watershed in NE Thailand. The experimental plots were positioned in a rubber tree plantation in different positions along a slope, in ruzi grass pasture and in an original forest site. Non parametric statistics demonstrated that van Genuchten unsaturated soil parameters (Ks, α and n), were significantly different according to the measurement methods employed whereas location was not a significant discriminating factor when all methods were considered together. However within each method, parameters n and α were statistically different according to the sites. These parameters were used with Hydrus1D for a one year simulation and computed pressure head did not show noticeable differences for the various sets of parameters, highlighting the fact that for modelling, any of these measurement method could be employed. The choice of the measurement method would therefore be motivated by the simplicity, robustness and its low cost.

  1. Estimating the Counterfactual Impact of Conservation Programs on Land Cover Outcomes: The Role of Matching and Panel Regression Techniques.

    Directory of Open Access Journals (Sweden)

    Kelly W Jones

    Full Text Available Deforestation and conversion of native habitats continues to be the leading driver of biodiversity and ecosystem service loss. A number of conservation policies and programs are implemented--from protected areas to payments for ecosystem services (PES--to deter these losses. Currently, empirical evidence on whether these approaches stop or slow land cover change is lacking, but there is increasing interest in conducting rigorous, counterfactual impact evaluations, especially for many new conservation approaches, such as PES and REDD, which emphasize additionality. In addition, several new, globally available and free high-resolution remote sensing datasets have increased the ease of carrying out an impact evaluation on land cover change outcomes. While the number of conservation evaluations utilizing 'matching' to construct a valid control group is increasing, the majority of these studies use simple differences in means or linear cross-sectional regression to estimate the impact of the conservation program using this matched sample, with relatively few utilizing fixed effects panel methods--an alternative estimation method that relies on temporal variation in the data. In this paper we compare the advantages and limitations of (1 matching to construct the control group combined with differences in means and cross-sectional regression, which control for observable forms of bias in program evaluation, to (2 fixed effects panel methods, which control for observable and time-invariant unobservable forms of bias, with and without matching to create the control group. We then use these four approaches to estimate forest cover outcomes for two conservation programs: a PES program in Northeastern Ecuador and strict protected areas in European Russia. In the Russia case we find statistically significant differences across estimators--due to the presence of unobservable bias--that lead to differences in conclusions about effectiveness. The Ecuador case

  2. Estimating the Counterfactual Impact of Conservation Programs on Land Cover Outcomes: The Role of Matching and Panel Regression Techniques.

    Science.gov (United States)

    Jones, Kelly W; Lewis, David J

    2015-01-01

    Deforestation and conversion of native habitats continues to be the leading driver of biodiversity and ecosystem service loss. A number of conservation policies and programs are implemented--from protected areas to payments for ecosystem services (PES)--to deter these losses. Currently, empirical evidence on whether these approaches stop or slow land cover change is lacking, but there is increasing interest in conducting rigorous, counterfactual impact evaluations, especially for many new conservation approaches, such as PES and REDD, which emphasize additionality. In addition, several new, globally available and free high-resolution remote sensing datasets have increased the ease of carrying out an impact evaluation on land cover change outcomes. While the number of conservation evaluations utilizing 'matching' to construct a valid control group is increasing, the majority of these studies use simple differences in means or linear cross-sectional regression to estimate the impact of the conservation program using this matched sample, with relatively few utilizing fixed effects panel methods--an alternative estimation method that relies on temporal variation in the data. In this paper we compare the advantages and limitations of (1) matching to construct the control group combined with differences in means and cross-sectional regression, which control for observable forms of bias in program evaluation, to (2) fixed effects panel methods, which control for observable and time-invariant unobservable forms of bias, with and without matching to create the control group. We then use these four approaches to estimate forest cover outcomes for two conservation programs: a PES program in Northeastern Ecuador and strict protected areas in European Russia. In the Russia case we find statistically significant differences across estimators--due to the presence of unobservable bias--that lead to differences in conclusions about effectiveness. The Ecuador case illustrates that

  3. Estimation of long-term environmental inventory factors associated with land application of sewage sludge

    DEFF Research Database (Denmark)

    Bruun, Sander; Yoshida, Hiroko; Nielsen, Martin P.

    2016-01-01

    . However, because of the complexity of the agricultural production system, it is difficult to estimate emissions consistently under different conditions. In the current paper, a mechanistic agro-ecosystem model was calibrated to be able to simulate different sludge types stabilized using different...

  4. A new technique for evaluating land use regression models and their impact on health effect estimates

    NARCIS (Netherlands)

    Wang, Meng; Brunekreef, Bert; Gehring, Ulrike; Szpiro, Adam; Hoek, Gerard; Beelen, Rob

    2016-01-01

    BACKGROUND: Leave-one-out cross-validation that fails to account for variable selection does not properly reflect prediction accuracy when the number of training sites is small. The impact on health effect estimates has rarely been studied. METHODS: We randomly generated ten training and test sets f

  5. Contributions of Precipitation and Soil Moisture Observations to the Skill of Soil Moisture Estimates in a Land Data Assimilation System

    Science.gov (United States)

    Reichle, Rolf H.; Liu, Qing; Bindlish, Rajat; Cosh, Michael H.; Crow, Wade T.; deJeu, Richard; DeLannoy, Gabrielle J. M.; Huffman, George J.; Jackson, Thomas J.

    2011-01-01

    The contributions of precipitation and soil moisture observations to the skill of soil moisture estimates from a land data assimilation system are assessed. Relative to baseline estimates from the Modern Era Retrospective-analysis for Research and Applications (MERRA), the study investigates soil moisture skill derived from (i) model forcing corrections based on large-scale, gauge- and satellite-based precipitation observations and (ii) assimilation of surface soil moisture retrievals from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E). Soil moisture skill is measured against in situ observations in the continental United States at 44 single-profile sites within the Soil Climate Analysis Network (SCAN) for which skillful AMSR-E retrievals are available and at four CalVal watersheds with high-quality distributed sensor networks that measure soil moisture at the scale of land model and satellite estimates. The average skill (in terms of the anomaly time series correlation coefficient R) of AMSR-E retrievals is R=0.39 versus SCAN and R=0.53 versus CalVal measurements. The skill of MERRA surface and root-zone soil moisture is R=0.42 and R=0.46, respectively, versus SCAN measurements, and MERRA surface moisture skill is R=0.56 versus CalVal measurements. Adding information from either precipitation observations or soil moisture retrievals increases surface soil moisture skill levels by IDDeltaR=0.06-0.08, and root zone soil moisture skill levels by DeltaR=0.05-0.07. Adding information from both sources increases surface soil moisture skill levels by DeltaR=0.13, and root zone soil moisture skill by DeltaR=0.11, demonstrating that precipitation corrections and assimilation of satellite soil moisture retrievals contribute similar and largely independent amounts of information.

  6. Estimation of four land surface essential climate variables (albedo, LAI/FAPAR, and Fcover) from VIIRS data

    Science.gov (United States)

    Liang, Shunlin

    2016-07-01

    As the successor of MODIS, the Visible Infrared Imaging Radiometer Suite (VIIRS) from the Suomi National Polar-orbiting Partnership (S-NPP) and future Joint Polar Satellite System (JPSS) brings us into a new era of global daily Earth observations. VIIRS was designed to improve upon the capabilities of the operational AVHRR and provide observation continuity with MODIS. This presentation will describe the progress in estimating four Essential Climate Variables (ECV): shortwave albedo (Wang, et al., 2013; Zhou, et al., 2016), leaf area index (LAI) (Xiao et al., 2016), fraction of absorbed photosynthetically active radiation (FAPAR) (Xiao et al., 2016), and fractional vegetation coverage (Fcover) (Li, et al., 2016) from VIIRS data. The algorithms have been peer reviewed, and shortwave albedo has been operationally produced by NOAA and accessible to the scientific community. Li, Y., K. Jia, S. Liang, Z. Xiao, X. Wang, L. Yang, (2016), An operational algorithm for estimating fractional vegetation cover from VIIRS reflectance data based on general regression neural networks, Remote Sensing, revised Xiao, Z., S. Liang, T. Wang, and B. Jiang, (2016), Retrieval of Leaf Area Index and Fraction of Absorbed Photosynthetically Active Radiation from VIIRS Time Series Data, Remote Sensing, revised. Wang, D., S. Liang, T. He, and Y. Yu, (2013), Direct Estimation of Land Surface Albedo from VIIRS Data: Algorithm Improvement and Preliminary Validation, Journal of Geophysical Research, 118(22):12,577-12,586 Zhou, Y., D. Wang, S. Liang, Y. Yu, and T. He, (2016), Assessment of the Suomi NPP VIIRS Land Surface Albedo Data Using Station Measurements and High-Resolution Albedo Maps, Remote Sensing, in press.

  7. Estimating litter carbon stocks on forest land in the United States.

    Science.gov (United States)

    Domke, Grant M; Perry, Charles H; Walters, Brian F; Woodall, Christopher W; Russell, Matthew B; Smith, James E

    2016-07-01

    Forest ecosystems are the largest terrestrial carbon sink on earth, with more than half of their net primary production moving to the soil via the decomposition of litter biomass. Therefore, changes in the litter carbon (C) pool have important implications for global carbon budgets and carbon emissions reduction targets and negotiations. Litter accounts for an estimated 5% of all forest ecosystem carbon stocks worldwide. Given the cost and time required to measure litter attributes, many of the signatory nations to the United Nations Framework Convention on Climate Change report estimates of litter carbon stocks and stock changes using default values from the Intergovernmental Panel on Climate Change or country-specific models. In the United States, the country-specific model used to predict litter C stocks is sensitive to attributes on each plot in the national forest inventory, but these predictions are not associated with the litter samples collected over the last decade in the national forest inventory. Here we present, for the first time, estimates of litter carbon obtained using more than 5000 field measurements from the national forest inventory of the United States. The field-based estimates mark a 44% reduction (2081±77Tg) in litter carbon stocks nationally when compared to country-specific model predictions reported in previous United Framework Convention on Climate Change submissions. Our work suggests that Intergovernmental Panel on Climate Change defaults and country-specific models used to estimate litter carbon in temperate forest ecosystems may grossly overestimate the contribution of this pool in national carbon budgets.

  8. Improved regional sea-level estimates from present day mass fluxes from Ice Sheets, Glaciers and land water using GRACE

    Science.gov (United States)

    Hsu, C. W.; Velicogna, I.

    2016-02-01

    Changes in ice sheets, glaciers and ice caps (GIC) and land water mass cause regional sea level variations that differ significantly from a uniform sea level, with a decrease in sea level near the sources of mass added to the ocean and an increase up to 30% larger than the global mean sea level in the far field. This effect called sea level fingerprints (SLF) are difficult to separate from the variation from ocean dynamics on short time and spatial scales. Most studies removed the uniform sea level to avoid this additional mass flux from atmosphere and land. However, as ice continues to melt, the SLF signal will become significantly different from uniform sea level. This makes removal of uniform mass flux to introduce additional error in the studies of ocean dynamic variation. Here, we employ observations of time variable gravity from GRACE over land, including the mass change of ice sheets, GIC, and land water storage to precisely calculate the SLF for the time period 2002-2015. We compare the results with sea level change from satellite radar altimetry (AVISO) corrected for the steric signal of the ocean from Argo measurements. We find an excellent agreement at the global scale in trend for the entire period between GRACE-derived SLF and AVISO minus Argo estimates. The agreement extends at the spatial scale of oceanic regions. Locally, the GRACE-derived SLF also agrees with in situ ocean bottom pressure recorder. The agreement demonstrates for the first time that SLF are reliable in terms of amplitude (intensity of mass loss), phase (spatial distribution of sources), and trends (increase in mass loss with time) using GRACE. During our observation period, we find that changes in land water mass dominate the seasonal variability of SLF. Greenland controls 42% of the total trend and 39% along the western and eastern US. Antarctica contributes 16% of the total trend and 21% in the western and eastern US. This work was performed at UC Irvine and at Caltech's Jet

  9. Incorporating changes in albedo in estimating the climate mitigation benefits of land use change projects

    Directory of Open Access Journals (Sweden)

    D. N. Bird

    2008-04-01

    Full Text Available Some climate scientists are questioning whether the practice of converting of non-forest lands to forest land (afforestation or reforestation is an effective climate change mitigation option. The discussion focuses particularly on areas where the new forest is primarily coniferous and there is significant amount of snow since the increased climate forcing due to the change in albedo may counteract the decreased climate forcing due to carbon dioxide removal.

    In this paper, we develop a stand-based model that combines changes in surface albedo, solar radiation, latitude, cloud cover and carbon sequestration. As well, we develop a procedure to convert carbon stock changes to equivalent climatic forcing or climatic forcing to equivalent carbon stock changes. Using the model, we investigate the sensitivity of combined affects of changes in surface albedo and carbon stock changes to model parameters. The model is sensitive to amount of cloud, atmospheric absorption, timing of canopy closure, carbon sequestration rate among other factors. The sensitivity of the model is investigated at one Canadian site, and then the model is tested at numerous sites across Canada.

    In general, we find that the change in albedo reduces the carbon sequestration benefits by approximately 30% over 100 years, but this is not drastic enough to suggest that one should not use afforestation or reforestation as a climate change mitigation option. This occurs because the forests grow in places where there is significant amount of cloud in winter. As well, variations in sequestration rate seem to be counterbalanced by the amount and timing of canopy closure.

    We close by speculating that the effects of albedo may also be significant in locations at lower latitudes, where there are less clouds, and where there are extended dry seasons. These conditions make grasses light coloured and when irrigated crops, dark forests or other vegetation such as

  10. Estimation of Groundwater Radon in North Carolina Using Land Use Regression and Bayesian Maximum Entropy.

    Science.gov (United States)

    Messier, Kyle P; Campbell, Ted; Bradley, Philip J; Serre, Marc L

    2015-08-18

    Radon ((222)Rn) is a naturally occurring chemically inert, colorless, and odorless radioactive gas produced from the decay of uranium ((238)U), which is ubiquitous in rocks and soils worldwide. Exposure to (222)Rn is likely the second leading cause of lung cancer after cigarette smoking via inhalation; however, exposure through untreated groundwater is also a contributing factor to both inhalation and ingestion routes. A land use regression (LUR) model for groundwater (222)Rn with anisotropic geological and (238)U based explanatory variables is developed, which helps elucidate the factors contributing to elevated (222)Rn across North Carolina. The LUR is also integrated into the Bayesian Maximum Entropy (BME) geostatistical framework to increase accuracy and produce a point-level LUR-BME model of groundwater (222)Rn across North Carolina including prediction uncertainty. The LUR-BME model of groundwater (222)Rn results in a leave-one out cross-validation r(2) of 0.46 (Pearson correlation coefficient = 0.68), effectively predicting within the spatial covariance range. Modeled results of (222)Rn concentrations show variability among intrusive felsic geological formations likely due to average bedrock (238)U defined on the basis of overlying stream-sediment (238)U concentrations that is a widely distributed consistently analyzed point-source data.

  11. Estimating the Total Economic Value of Cultivated Flower Land in Taiwan

    Directory of Open Access Journals (Sweden)

    Chin-Huang Huang

    2015-04-01

    Full Text Available Many arable land areas have been converted to residential or business uses by Taiwan government authorities, because the low farmland value is associated with the low value of agricultural products. However, agriculture is multifunctional. This study investigates farmland value through Total Economic Value (TEV for Tianwei Township, which is Taiwan’s largest floral farmland region. Direct use value measures the floral products’ output value and recreational benefit. Recreational benefit from visitors’ flower sightseeing was measured by the travel cost method (TCM. Option value and non-use value, including bequest value and existence value, measure the residents’ willingness to pay through the double-bounded dichotomous contingent valuation method (CVM. The results show that the total floral products’ output is NT$1.441 billion in 2007, recreational benefit is roughly NT$17.757 billion. The intangible value of option value and non-use values are approximately between NT$5 million to 15 million. Therefore, ignoring various values of farmland might lead to an underestimation of farmland value.

  12. Walk-In Hunting Access (WIHA) Fall 2009

    Data.gov (United States)

    Kansas Data Access and Support Center — This shapefile represents the private lands leased by the Kansas Department of Wildlife and Parks for fall 2009 public hunting access through the Walk-In Hunting...

  13. Walk-In Hunting Access (WIHA) Fall 2008

    Data.gov (United States)

    Kansas Data Access and Support Center — This shapefile represents the private lands leased by the Kansas Department of Wildlife and Parks for fall 2008 public hunting access through the Walk-In Hunting...

  14. Walk-In Hunting Access (WIHA) Fall 2010

    Data.gov (United States)

    Kansas Data Access and Support Center — This shapefile represents the private lands leased by the Kansas Department of Wildlife and Parks for fall 2010 public hunting access through the Walk-In Hunting...

  15. On alternating quantum walks

    Science.gov (United States)

    Rousseva, Jenia; Kovchegov, Yevgeniy

    2017-03-01

    We study an inhomogeneous quantum walk on a line that evolves according to alternating coins, each a rotation matrix. For the quantum walk with the coin alternating between clockwise and counterclockwise rotations by the same angle, we derive a closed form solution for the propagation of probabilities, and provide its asymptotic approximation via the method of stationary phase. Finally, we observe that for a x03c0;/4 angle, this alternating rotation walk will replicate the renown Hadamard walk.

  16. The effect on river discharge estimation by considering an interaction between land surface process and river routing process

    Science.gov (United States)

    Yorozu, K.; Tachikawa, Y.

    2015-06-01

    There is much research assessing the impact of climate change on the hydrologic cycle. However, it has often focused on a specific hydrologic process, without considering the interaction among hydrologic processes. In this study, a distributed hydrologic model considering the interaction between flow routing and land surface processes was developed, and its effect on river discharge estimation was investigated. The model enables consideration of flow routing, irrigation withdrawal from rivers at paddy fields, crop growth depending on water and energy status, and evapotranspiration based on meteorological, soil water and vegetation status. To examine the effects of hydrologic process interaction on river discharge estimation, a developed model was applied to the Chao Phraya river basin using near surface meteorological data collected by the Japanese Meteorological Research Institute's Atmospheric General Circulation Model (MRI-AGCM3.2S) with TL959 spatial resolution as forcing data. Also, a flow routing model, which was part of the developed model, was applied independently, using surface and subsurface runoff data from the same GCM. In the results, the developed model tended to estimate a smaller river discharge than was estimated by the river routing model, because of the irrigation effect. In contrast, the annual maximum daily discharge calculated by the developed model was 24% greater than that by the flow routing model. It is assumed that surface runoff in the developed model was greater than that in the flow routing model because the soil water content was maintained at a high level through irrigation withdrawal. As for drought discharge, which is defined as the 355th largest daily discharge, the developed model gave a discharge 2.7-fold greater than the flow routing model. It seems that subsurface runoff in the developed model was greater than that in the flow routing model. The results of this study suggest that considering hydrologic interaction in a

  17. A Systems Approach to the Estimation of Ecosystem and Human Health Stressors in Air, Land and Water

    Science.gov (United States)

    Cooter, E. J.; Dennis, R. L.; Bash, J. O.

    2013-12-01

    Nitrogen (N) and sulfur oxides (SOx) in air, land and water media are parts of tightly coupled geophysical systems resulting in multiple routes for human and ecosystem exposure. For instance, excess forms of total reactive N in water can lead to harmful algal blooms, with the depletion of oxygen and adverse impacts to aquatic ecosystem productivity in coastal estuaries. Acidic deposition can result in lost forest productivity for terrestrial ecosystem and impacts to trout and other fishery resources in inland waters. Human pulmonary health can be impaired when N and SOx in the atmosphere lead to the generation of ozone and particulate matter (PM). Atmospheric N deposition can also contribute to eutrophication of drinking water sources. The U.S. Environmental Protection Agency (USEPA) Office of Research and Development (ORD) has embarked on the development of a multi-media 'one environment' systems approach to these issues to help develop management decisions that create win-win policies. The purpose of this project is to develop a 'one environment' set of models that can inform protection of ecosystems and human health in both the current state and under future climate scenarios. The research framework focuses on three interrelated themes; coupling air quality with land use and agricultural land management, connecting the hydrosphere (i.e., coupling meteorology and hydrology) and linking the air/land/hydrosphere with ecosystem models and benefits models. We will present an overall modeling framework and then move to the presentation of on-going research results related to direct linkage of air quality with land use and agricultural land management. A modeling interface system has been developed that facilitates the simulation of field-scale agricultural land management decisions over a gridded domain at multiple grid resolutions for the Contiguous United States (CONUS) using a modified version of the USDA EPIC (Environmental Policy Integrated Climate) model. EPIC

  18. A variational data assimilation system for soil–atmosphere flux estimates for the Community Land Model (CLM3.5

    Directory of Open Access Journals (Sweden)

    C. M. Hoppe

    2014-05-01

    Full Text Available This paper presents the development and implementation of a spatio-temporal variational data assimilation system (4D-var for the soil–vegetation–atmosphere transfer model "Community Land Model" (CLM3.5, along with the development of the adjoint code for the core soil–atmosphere transfer scheme of energy and soil moisture. The purpose of this work is to obtain an improved estimation technique for the energy fluxes (sensible and latent heat fluxes between the soil and the atmosphere. Optimal assessments of these fluxes are neither available from model simulations nor measurements alone, while a 4D-var data assimilation has the potential to combine both information sources by a Best Linear Unbiased Estimate (BLUE. The 4D-var method requires the development of the adjoint model of the CLM which is established in this work. The new data assimilation algorithm is able to assimilate soil temperature and soil moisture measurements for one-dimensional columns of the model grid. Numerical experiments were first used to test the algorithm under idealised conditions. It was found that the analysis delivers improved results whenever there is a dependence between the initial values and the assimilated quantity. Furthermore, soil temperature and soil moisture from in situ field measurements were assimilated. These calculations demonstrate the improved performance of flux estimates, whenever soil property parameters are available of sufficient quality. Misspecifications could also be identified by the performance of the variational scheme.

  19. Assimilation of Global Radar Backscatter and Radiometer Brightness Temperature Observations to Improve Soil Moisture and Land Evaporation Estimates

    Science.gov (United States)

    Lievens, H.; Martens, B.; Verhoest, N. E. C.; Hahn, S.; Reichle, R. H.; Miralles, D. G.

    2017-01-01

    Active radar backscatter (s?) observations from the Advanced Scatterometer (ASCAT) and passive radiometer brightness temperature (TB) observations from the Soil Moisture Ocean Salinity (SMOS) mission are assimilated either individually or jointly into the Global Land Evaporation Amsterdam Model (GLEAM) to improve its simulations of soil moisture and land evaporation. To enable s? and TB assimilation, GLEAM is coupled to the Water Cloud Model and the L-band Microwave Emission from the Biosphere (L-MEB) model. The innovations, i.e. differences between observations and simulations, are mapped onto the model soil moisture states through an Ensemble Kalman Filter. The validation of surface (0-10 cm) soil moisture simulations over the period 2010-2014 against in situ measurements from the International Soil Moisture Network (ISMN) shows that assimilating s? or TB alone improves the average correlation of seasonal anomalies (Ran) from 0.514 to 0.547 and 0.548, respectively. The joint assimilation further improves Ran to 0.559. Associated enhancements in daily evaporative flux simulations by GLEAM are validated based on measurements from 22 FLUXNET stations. Again, the singular assimilation improves Ran from 0.502 to 0.536 and 0.533, respectively for s? and TB, whereas the best performance is observed for the joint assimilation (Ran = 0.546). These results demonstrate the complementary value of assimilating radar backscatter observations together with brightness temperatures for improving estimates of hydrological variables, as their joint assimilation outperforms the assimilation of each observation type separately.

  20. Assimilation of Global Radar Backscatter and Radiometer Brightness Temperature Observations to Improve Soil Moisture and Land Evaporation Estimates

    Science.gov (United States)

    Lievens, H.; Martens, B.; Verhoest, N. E. C.; Hahn, S.; Reichle, R. H.; Miralles, D. G.

    2017-01-01

    Active radar backscatter (s?) observations from the Advanced Scatterometer (ASCAT) and passive radiometer brightness temperature (TB) observations from the Soil Moisture Ocean Salinity (SMOS) mission are assimilated either individually or jointly into the Global Land Evaporation Amsterdam Model (GLEAM) to improve its simulations of soil moisture and land evaporation. To enable s? and TB assimilation, GLEAM is coupled to the Water Cloud Model and the L-band Microwave Emission from the Biosphere (L-MEB) model. The innovations, i.e. differences between observations and simulations, are mapped onto the model soil moisture states through an Ensemble Kalman Filter. The validation of surface (0-10 cm) soil moisture simulations over the period 2010-2014 against in situ measurements from the International Soil Moisture Network (ISMN) shows that assimilating s? or TB alone improves the average correlation of seasonal anomalies (Ran) from 0.514 to 0.547 and 0.548, respectively. The joint assimilation further improves Ran to 0.559. Associated enhancements in daily evaporative flux simulations by GLEAM are validated based on measurements from 22 FLUXNET stations. Again, the singular assimilation improves Ran from 0.502 to 0.536 and 0.533, respectively for s? and TB, whereas the best performance is observed for the joint assimilation (Ran = 0.546). These results demonstrate the complementary value of assimilating radar backscatter observations together with brightness temperatures for improving estimates of hydrological variables, as their joint assimilation outperforms the assimilation of each observation type separately.

  1. Inter-comparison of energy balance and hydrological models for land surface energy flux estimation over a whole river catchment

    DEFF Research Database (Denmark)

    Guzinski, R.; Nieto, H.; Stisen, S.

    2015-01-01

    Evapotranspiration (ET) is the main link between the natural water cycle and the land surface energy budget. Therefore water-balance and energy-balance approaches are two of the main methodologies for modelling this process. The water-balance approach is usually implemented as a complex, distribu...... derived with the energy-balance models, satellite based LST or another source) into the hydrological models. How this could be achieved and how to evaluate the improvements, or lack of thereof, is still an open research question.......-balance (TSEB) scheme, against a hydrological model, MIKE SHE, calibrated over the Skjern river catchment in western Denmark. The three models utilize different primary inputs to estimate ET (LST from different satellites in the case of remote sensing models and modelled soil moisture and heat flux in the case...

  2. Estimation and Validation of Land Surface Temperatures from Chinese Second-Generation Polar-Orbit FY-3A VIRR Data

    Directory of Open Access Journals (Sweden)

    Bo-Hui Tang

    2015-03-01

    Full Text Available This work estimated and validated the land surface temperature (LST from thermal-infrared Channels 4 (10.8 µm and 5 (12.0 µm of the Visible and Infrared Radiometer (VIRR onboard the second-generation Chinese polar-orbiting FengYun-3A (FY-3A meteorological satellite. The LST, mean emissivity and atmospheric water vapor content (WVC were divided into several tractable sub-ranges with little overlap to improve the fitting accuracy. The experimental results showed that the root mean square errors (RMSEs were proportional to the viewing zenith angles (VZAs and WVC. The RMSEs were below 1.0 K for VZA sub-ranges less than 30° or for VZA sub-ranges less than 60° and WVC less than 3.5 g/cm2, provided that the land surface emissivities were known. A preliminary validation using independently simulated data showed that the estimated LSTs were quite consistent with the actual inputs, with a maximum RMSE below 1 K for all VZAs. An inter-comparison using the Moderate Resolution Imaging Spectroradiometer (MODIS-derived LST product MOD11_L2 showed that the minimum RMSE was 1.68 K for grass, and the maximum RMSE was 3.59 K for barren or sparsely vegetated surfaces. In situ measurements at the Hailar field site in northeastern China from October, 2013, to September, 2014, were used to validate the proposed method. The result showed that the RMSE between the LSTs calculated from the ground measurements and derived from the VIRR data was 1.82 K.

  3. State and parameter estimation of two land surface models using the ensemble Kalman filter and the particle filter

    Directory of Open Access Journals (Sweden)

    H. Zhang

    2017-09-01

    Full Text Available Land surface models (LSMs use a large cohort of parameters and state variables to simulate the water and energy balance at the soil–atmosphere interface. Many of these model parameters cannot be measured directly in the field, and require calibration against measured fluxes of carbon dioxide, sensible and/or latent heat, and/or observations of the thermal and/or moisture state of the soil. Here, we evaluate the usefulness and applicability of four different data assimilation methods for joint parameter and state estimation of the Variable Infiltration Capacity Model (VIC-3L and the Community Land Model (CLM using a 5-month calibration (assimilation period (March–July 2012 of areal-averaged SPADE soil moisture measurements at 5, 20, and 50 cm depths in the Rollesbroich experimental test site in the Eifel mountain range in western Germany. We used the EnKF with state augmentation or dual estimation, respectively, and the residual resampling PF with a simple, statistically deficient, or more sophisticated, MCMC-based parameter resampling method. The performance of the calibrated LSM models was investigated using SPADE water content measurements of a 5-month evaluation period (August–December 2012. As expected, all DA methods enhance the ability of the VIC and CLM models to describe spatiotemporal patterns of moisture storage within the vadose zone of the Rollesbroich site, particularly if the maximum baseflow velocity (VIC or fractions of sand, clay, and organic matter of each layer (CLM are estimated jointly with the model states of each soil layer. The differences between the soil moisture simulations of VIC-3L and CLM are much larger than the discrepancies among the four data assimilation methods. The EnKF with state augmentation or dual estimation yields the best performance of VIC-3L and CLM during the calibration and evaluation period, yet results are in close agreement with the PF using MCMC resampling. Overall, CLM demonstrated the

  4. Estimation of Land Surface Parameters by LDAS-UT: Model Development and Validation on Tanashi Field Experiment

    Science.gov (United States)

    Lu, H.; Koike, T.; Yang, K.; Li, X.; Graf, T.; Boussetta, S.; Tsutsui, H.; Kuria, D. N.

    2007-12-01

    The estimation of soil moisture and surface energy fluxes at various temporal and spatial scales remains to be an outstanding problem in hydrologic and meteorological researches. Remote sensed data retrieval algorithms, land surface models and data assimilation systems are highly expected to provide a solution to this problem. But the parameters required by those algorithms and systems, such as the soil texture, porosity, roughness parameters and so on, are highly variable or unavailable. In this study, a land data assimilation system (LDAS- UT) is employed to inversely estimate the optimal values of those land surface parameters with meteorological forcing data and remote sensed data. And a field experiment is designed to provide a well-controlled data set for the system validation. The Tanashi experiment has been in operation since November, 2006 in the farm of the University of Tokyo. Continuous ground measurements of meteorological variables, soil moisture and temperature profiles and vegetation status have been taken over a plot, in which winter wheat was planted. At the same time, the ground based microwave radiometers (GBMR) are employed to provide accurate field measurements of brightness temperature up-welling from the plot, at the frequencies of 6.925, 10.65, 18.7, 23.8, 36.5 and 89 GHz. The LDAS_UT is then run with using data obtained from this experiment to retrieval parameters for two periods. One is the period from December 2006 to February 2007, the germination period of winter wheat, and during which the vegetation effects are small. The second period is from April to May 2007, during which the winter wheat was developing rapidly. The optimize parameters were compared with the in situ observed ¡®real' ones. It found that, for the first period, the retrieved parameters are close to the ¡®real' values, while for the second period, the gap between the retrieved parameters and the ¡®real' values are much bigger. The difference between the

  5. Estimation of annual actual evapotranspiration from nonsaturated land surfaces with conventional meteorological data

    Institute of Scientific and Technical Information of China (English)

    QIU; Xinfa; ZENG; Yan; MIAO; Qilong; YU; Qiang

    2004-01-01

    Views diverge greatly on the relationship between actual evapotranspiration (AE) and potential evapotranspiration (PE). Penman showed that AE is determined in intensity by PE and changes proportionally as a function of PE. In contrast, Bouchet indicated that AE determines PE and varies inversely with PE. Based on nearly 30 years data from 432 weather stations and 512 hydrological stations in China, the two different theories, Penman's assumption and Bouchet's complementary relationship between AE and PE, were tested on nine river basins. With data integration technique, the complementary relationship between AE and PE was displayed entirely. A general model to estimate the actual evapotranspiration from nonsaturated surfaces by routine meteorological observations has been established on the basis of thorough analysis of the concept of PE. The results show that the calculations are all in error control of <10%, except for a few years over the Yellow River Basin.

  6. An operational method for the disaggregation of land surface temperature to estimate actual evapotranspiration in the arid region of Chile

    Science.gov (United States)

    Olivera-Guerra, L.; Mattar, C.; Merlin, O.; Durán-Alarcón, C.; Santamaría-Artigas, A.; Fuster, R.

    2017-06-01

    Monitoring evapotranspiration in arid and semi-arid environments plays a key role in water irrigation scheduling for water use efficiency. This work presents an operational method for evapotranspiration retrievals based on disaggregated Land Surface Temperature (LST). The retrieved LSTs from Landsat-8 and MODIS data were merged in order to provide an 8-day composite LST product at 100 × 100 m resolution. The method was tested in the arid region of Copiapó, Chile using data from years 2013-2014 and validated using data from years 2015-2016. In-situ measurements from agrometeorological stations such as air temperature and potential evapotranspiration (ET0) estimated at the location were used in the ET estimation method. The disaggregation method was developed by taking into account (1) the spatial relationship between Landsat-8 and MODIS LST, (2) the spatial relationship between LST and the Normalized Difference Vegetation Index (NDVI) at high spatial resolution (Landsat-8), and (3) the temporal variations along the year of both relationships aforementioned. The comparison between disaggregated LST at 100 m resolution and in situ LST measurements presents a coefficient of determination (r2), in average, equal to 0.70 and a RMSE equal to 3.6 K. The disaggregated LST was used in an operational model to estimate the actual evapotranspiration (ETa). The ETa shows good results in terms of seasonal variations and in comparison to the evapotranspiration estimated by using crop coefficients (kc). The comparison between remotely sensed and in situ ETa presents an overall r2 close to 0.67 and a RMSE equal to 0.6 mm day-1 for both crops. These results are important for further improvements in water use sustainability in the Copiapó valley, which is currently affected by high water demand.

  7. Walking and child pedestrian injury: a systematic review of built environment correlates of safe walking.

    Science.gov (United States)

    Rothman, Linda; Buliung, Ron; Macarthur, Colin; To, Teresa; Howard, Andrew

    2014-02-01

    The child active transportation literature has focused on walking, with little attention to risk associated with increased traffic exposure. This paper reviews the literature related to built environment correlates of walking and pedestrian injury in children together, to broaden the current conceptualization of walkability to include injury prevention. Two independent searches were conducted focused on walking in children and child pedestrian injury within nine electronic databases until March, 2012. Studies were included which: 1) were quantitative 2) set in motorized countries 3) were either urban or suburban 4) investigated specific built environment risk factors 5) had outcomes of either walking in children and/or child pedestrian roadway collisions (ages 0-12). Built environment features were categorized according to those related to density, land use diversity or roadway design. Results were cross-tabulated to identify how built environment features associate with walking and injury. Fifty walking and 35 child pedestrian injury studies were identified. Only traffic calming and presence of playgrounds/recreation areas were consistently associated with more walking and less pedestrian injury. Several built environment features were associated with more walking, but with increased injury. Many features had inconsistent results or had not been investigated for either outcome. The findings emphasise the importance of incorporating safety into the conversation about creating more walkable cities.

  8. Back-extrapolating a land use regression model for estimating past exposures to traffic-related air pollution.

    Science.gov (United States)

    Levy, Ilan; Levin, Noam; Yuval; Schwartz, Joel D; Kark, Jeremy D

    2015-03-17

    Land use regression (LUR) models rely on air pollutant measurements for their development, and are therefore limited to recent periods where such measurements are available. Here we propose an approach to overcome this gap and calculate LUR models several decades before measurements were available. We first developed a LUR model for NOx using annual averages of NOx at all available air quality monitoring sites in Israel between 1991 and 2011 with time as one of the independent variables. We then reconstructed historical spatial data (e.g., road network) from historical topographic maps to apply the model's prediction to each year from 1961 to 2011. The model's predictions were then validated against independent estimates about the national annual NOx emissions from on-road vehicles in a top-down approach. The model's cross validated R2 was 0.74, and the correlation between the model's annual averages and the national annual NOx emissions between 1965 and 2011 was 0.75. Information about the road network and population are persistent predictors in many LUR models. The use of available historical data about these predictors to resolve the spatial variability of air pollutants together with complementary national estimates on the change in pollution levels over time enable historical reconstruction of exposures.

  9. Detailed comparison of neuro-fuzzy estimation of subpixel land-cover composition from remotely sensed data

    Science.gov (United States)

    Baraldi, Andrea; Binaghi, Elisabetta; Blonda, Palma N.; Brivio, Pietro A.; Rampini, Anna

    1998-10-01

    Mixed pixels, which do not follow a known statistical distribution that could be parameterized, are a major source of inconvenience in classification of remote sensing images. This paper reports on an experimental study designed for the in-depth investigation of how and why two neuro-fuzzy classification schemes, whose properties are complementary, estimate sub-pixel land cover composition from remotely sensed data. The first classifier is based on the fuzzy multilayer perceptron proposed by Pal and Mitra: the second classifier consists of a two-stage hybrid (TSH) learning scheme whose unsupervised first stage is based on the fully self- organizing simplified adaptive resonance theory clustering network proposed by Baraldi. Results of the two neuro-fuzzy classifiers are assessed by means of specific evaluation tools designed to extend conventional descriptive and analytical statistical estimators to the case of multi-membership in classes. When a synthetic data set consisting of pure and mixed pixels is processed by the two neuro-fuzzy classifiers, experimental result show that: i) the two neuro- fuzzy classifiers perform better than the traditional MLP; ii) classification accuracies of the two neuro-fuzzy classifiers are comparable; and iii) the TSH classifier requires to train less background knowledge than FMLP.

  10. Further evaluation of wetland emission estimates from the JULES land surface model using SCIAMACHY and GOSAT atmospheric column methane measurements

    Science.gov (United States)

    Hayman, Garry; Comyn-Platt, Edward; McNorton, Joey; Chipperfield, Martyn; Gedney, Nicola

    2016-04-01

    The atmospheric concentration of methane began rising again in 2007 after a period of near-zero growth [1,2], with the largest increases observed over polar northern latitudes and the Southern Hemisphere in 2007 and in the tropics since then. The observed inter-annual variability in atmospheric methane concentrations and the associated changes in growth rates have variously been attributed to changes in different methane sources and sinks [2,3]. Wetlands are generally accepted as being the largest, but least well quantified, single natural source of CH4, with global emission estimates ranging from 142-284 Tg yr-1 [3]. The modelling of wetlands and their associated emissions of CH4 has become the subject of much current interest [4]. We have previously used the HadGEM2 chemistry-climate model to evaluate the wetland emission estimates derived using the UK community land surface model (JULES, the Joint UK Land Earth Simulator) against atmospheric observations of methane, including SCIAMACHY total methane columns [5] up to 2007. We have undertaken a series of new HadGEM2 runs using new JULES emission estimates extended in time to the end of 2012, thereby allowing comparison with both SCIAMACHY and GOSAT atmospheric column methane measurements. We will describe the results of these runs and the implications for methane wetland emissions. References [1] Rigby, M., et al.: Renewed growth of atmospheric methane. Geophys. Res. Lett., 35, L22805, 2008; [2] Nisbet, E.G., et al.: Methane on the Rise-Again, Science 343, 493, 2014; [3] Kirschke, S., et al.,: Three decades of global methane sources and sinks, Nature Geosciences, 6, 813-823, 2013; [4] Melton, J. R., et al.: Present state of global wetland extent and wetland methane modelling: conclusions from a model inter-comparison project (WETCHIMP), Biogeosciences, 10, 753-788, 2013; [5] Hayman, G.D., et al.: Comparison of the HadGEM2 climate-chemistry model against in situ and SCIAMACHY atmospheric methane data, Atmos. Chem

  11. Landing on empty: estimating the benefits from reducing fuel uplift in US Civil Aviation

    Science.gov (United States)

    Ryerson, Megan S.; Hansen, Mark; Hao, Lu; Seelhorst, Michael

    2015-09-01

    Airlines and Air Navigation Service Providers are united in their goal to reduce fuel consumption. While changes to flight operations and technology investments are the focus of a number of studies, our study is among the first to investigate an untapped source of aviation fuel consumption: excess contingency fuel loading. Given the downside risk of fuel exhaustion of diverting to an alternate airport, airline dispatchers may load excess fuel onto an aircraft. Such conservatism comes at a cost of consuming excess fuel, as fuel consumed is a function of, among other factors, aircraft weight. The aim of this paper is to quantify, on a per-flight basis, the fuel burned due to carrying fuel beyond what is needed for foreseeable contingencies, and thereby motivate research, federal guidance, and investments that allow airline dispatchers to reduce fuel uplift while maintaining near zero risks of fuel exhaustion. We merge large publicly available aviation and weather databases with a detailed dataset from a major US airline. Upon estimating factors that capture the quantity fuel consumed due to carrying a pound of weight for a range of aircraft types, we calculate the cost and greenhouse gas emissions from carrying unused fuel on arrival and additional contingency fuel above a conservative buffer for foreseeable contingencies. We establish that the major US carrier does indeed load fuel conservatively. We find that 4.48% of the fuel consumed by an average flight is due to carrying unused fuel and 1.04% of the fuel consumed by an average flight is due to carrying additional contingency fuel above a reasonable buffer. We find that simple changes in flight dispatching that maintain a statistically minimal risk of fuel exhaustion could result in yearly savings of 338 million lbs of CO2, the equivalent to the fuel consumed from 4760 flights on midsized commercial aircraft. Moreover, policy changes regarding maximum fuel loads or investments that reduce uncertainty or increase

  12. Factors controlling shell carbon isotopic composition of land snail Acusta despecta sieboldiana estimated from lab culturing experiment

    Directory of Open Access Journals (Sweden)

    N. Zhang

    2014-05-01

    Full Text Available The carbon isotopic composition (δ13C of land snail shell carbonate derives from three potential sources: diet, atmospheric CO2, and ingested carbonate (limestone. However, their relative contributions remain unclear. Under various environmental conditions, we cultured one land snail species, Acusta despecta sieboldiana collected from Yokohama, Japan, and confirmed that all of these sources affect shell carbonate δ13C values. Herein, we consider the influences of metabolic rates and temperature on the carbon isotopic composition of the shell carbonate. Based on previous works and on results obtained in this study, a simple but credible framework is presented for discussion of how each source and environmental parameter can affect shell carbonate δ13C values. According to this framework and some reasonable assumptions, we have estimated the contributions of different carbon sources for each snail individual: for cabbage (C3 plant fed groups, the contributions of diet, atmospheric CO2 and ingested limestone respectively vary as 66–80%, 16–24%, and 0–13%. For corn (C4 plant fed groups, because of the possible food stress (lower consumption ability of C4 plant, the values vary respectively as 56–64%, 18–20%, and 16–26%. Moreover, we present new evidence that snails have discrimination to choose C3 and C4 plants as food. Therefore, we suggest that food preferences must be considered adequately when applying δ13C in paleo-environment studies. Finally, we inferred that, during egg laying and hatching of our cultured snails, carbon isotope fractionation is controlled only by the isotopic exchange of the calcite–HCO3−–aragonite equilibrium.

  13. Factors controlling shell carbon isotopic composition of land snail Acusta despecta sieboldiana estimated from lab culturing experiment

    Science.gov (United States)

    Zhang, N.; Yamada, K.; Suzuki, N.; Yoshida, N.

    2014-05-01

    The carbon isotopic composition (δ13C) of land snail shell carbonate derives from three potential sources: diet, atmospheric CO2, and ingested carbonate (limestone). However, their relative contributions remain unclear. Under various environmental conditions, we cultured one land snail species, Acusta despecta sieboldiana collected from Yokohama, Japan, and confirmed that all of these sources affect shell carbonate δ13C values. Herein, we consider the influences of metabolic rates and temperature on the carbon isotopic composition of the shell carbonate. Based on previous works and on results obtained in this study, a simple but credible framework is presented for discussion of how each source and environmental parameter can affect shell carbonate δ13C values. According to this framework and some reasonable assumptions, we have estimated the contributions of different carbon sources for each snail individual: for cabbage (C3 plant) fed groups, the contributions of diet, atmospheric CO2 and ingested limestone respectively vary as 66-80%, 16-24%, and 0-13%. For corn (C4 plant) fed groups, because of the possible food stress (lower consumption ability of C4 plant), the values vary respectively as 56-64%, 18-20%, and 16-26%. Moreover, we present new evidence that snails have discrimination to choose C3 and C4 plants as food. Therefore, we suggest that food preferences must be considered adequately when applying δ13C in paleo-environment studies. Finally, we inferred that, during egg laying and hatching of our cultured snails, carbon isotope fractionation is controlled only by the isotopic exchange of the calcite-HCO3--aragonite equilibrium.

  14. Estimation of Stand Type Parameters and Land Cover Using Landsat-7 ETM Image: A Case Study from Turkey.

    Science.gov (United States)

    Günlü, Alkan; Sivrikaya, Fatih; Baskent, Emin Zeki; Keles, Sedat; Çakir, Günay; Kadiogullari, Ali İhsan

    2008-04-09

    Remote sensing has been considered a low-cost, large-area coverage forest information resource ideally suited to broad-scale forest inventory objectives. The objective of this study is to determine stand type parameters such as crown closure, development stage and stand types, and land cover obtained from Landsat 7 ETM image and forest cover type map (stand type map). The research also focuses on classifying and mapping the stand parameters with the spatial analysis functions of GIS. In the study, stand parameters determined by forest cover type map and remote sensing methods were compared and contrasted to evaluate the potential use of the remote sensing methods. The result showed that development stage were estimated with Landsat 7 ETM image using supervised classification with a 0.89 kappa statistic value and 92% overall accuracy assessments. Among the features, development stages were the most successfully classified stand parameters in classification process. According to the spatial accuracy assessment results, development stages also had the highest accuracy of 72.2%. As can be seen in the results, spatial accuracy is lower than classification accuracy. Stand type had the lowest accuracy of 32.8. In conclusion, it could be stated that development stages, crown closure and land cover could be determined at an acceptable level using Landsat 7 ETM image. However, Landsat 7 ETM image do not provide means to map and monitor minor vegetation communities and stand types at stand level due to low spatial resolution. High resolution satellite images could be used either alone or with field survey data.

  15. Assimilating the Cosmic-Ray Soil Moisture Observing System Measurements for Land Surface Hydrologic Model Parameter Estimation Using the Ensemble Kalman Filter

    Science.gov (United States)

    Xiao, D.; Shi, Y.; Li, L.

    2015-12-01

    Parameter estimation is generally required for land surface models (LSMs) and hydrologic models to reproduce observed water and energy fluxes in different watersheds. Using soil moisture observations for parameter estimation in addition to discharge and land surface temperature observations can improve the prediction of land surface and subsurface processes. Due to their representativity, point measurements cannot capture the watershed-scale soil moisture conditions and may lead to notable bias in watershed soil moisture predictions if used for model calibration. The intermediate-scale cosmic-ray soil moisture observing system (COSMOS) provides average soil water content measurement over a footprint of 0.34 m2 and depths up to 50 cm, and may provide better calibration data for low-order watersheds. In this study, we will test using COSMOS observations for Flux-PIHM parameter and state estimation via the ensemble Kalman filter (EnKF). Flux-PIHM is a physically-based land surface hydrologic model that couples the Penn State Integrated Hydrologic Model (PIHM) with the Noah land surface model. Synthetic data experiments will be performed at the Shale Hills watershed (area: 0.08 km2, smaller than COSMOS footprint) and the Garner Run watershed (1.34 km2, larger than COSMOS footprint) in the Shale Hills Susquehanna Critical Zone Observatory in central Pennsylvania. COSMOS observations will be assimilated into Flux-PIHM using the EnKF, in addition to discharge and land surface temperature (LST) observations. The accuracy of EnKF estimated parameters and water and energy flux predictions will be evaluated. In addition, the results will be compared with assimilating point soil moisture measurement (in addition to discharge and LST), to assess the effects of using different scales of soil moisture observations for parameter estimation. The results at Shale Hills and Garner Run will be compared to test whether performance of COSMOS data assimilation is affected by the size of

  16. Estimation of landslides activities evolution due to land-use and climate change in a Pyrenean valley

    Science.gov (United States)

    Vandromme, Rosalie; Bernardie, Séverine; Houet, Thomas; Grémont, Marine; Grandjean, Gilles; Thiery, Yannick

    2016-04-01

    Global changes would have impacts worldwide, but their effects should be even more exacerbated in areas particularly vulnerable. Mountainous areas are among these vulnerable territories. Ecological systems are often at a fragile equilibrium, socio-economical activities are often climate-dependent and climate-driven natural hazards can be a major threat for human activities. In order to estimate the capacity of such mountainous valleys to face global changes (climate, but also climate- and human- induced land-use changes), it is necessary to be able to evaluate the evolution of the different threats. The present work shows a method to evaluate the influences of the evolution of both vegetation cover and climate on landslides activities over a whole valley until 2100, to propose adequate solutions for current and future forestry management. Firstly, the assessment of future land use is addressed through the construction of four prospective socio-economic scenarios up to 2050 and 2100, which are then spatially validated and modeled with LUCC models. Secondly, the climate change inputs of the project correspond to 2 scenarios of emission of greenhouse gases. The used simulations available on the portal DRIAS (http://www.drias-climat.fr) were performed with the GHG emissions scenarios (RCP: Representative concentration pathways, according to the standards defined by the GIEC) RCP 4.5 and RCP 8.5. The impact of land use and climate change is then addressed through the use of these scenarios into hazards computations. For that we use a large-scale slope stability assessment tool ALICE which combines a mechanical stability model (using finite slope analysis), a vegetation module which interfere with the first model, to take into account the effects of vegetation on the mechanical soil properties (cohesion and over-load), and an hydrogeological model. All these elements are interfaced within a GIS-based solution. In that way, future changes in temperature, precipitation and

  17. Walks on Weighted Networks

    Institute of Scientific and Technical Information of China (English)

    WU An-Cai; XU Xin-Jian; WU Zhi-Xi; WANG Ying-Hai

    2007-01-01

    We investigate the dynamics of random walks on weighted networks. Assuming that the edge weight and the node strength are used as local information by a random walker. Two kinds of walks, weight-dependent walk and strength-dependent walk, are studied. Exact expressions for stationary distribution and average return time are derived and confirmed by computer simulations. The distribution of average return time and the mean-square that a weight-dependent walker can arrive at a new territory more easily than a strength-dependent one.

  18. Virtually Abelian quantum walks

    Science.gov (United States)

    Mauro D'Ariano, Giacomo; Erba, Marco; Perinotti, Paolo; Tosini, Alessandro

    2017-01-01

    We study discrete-time quantum walks on Cayley graphs of non-Abelian groups, focusing on the easiest case of virtually Abelian groups. We present a technique to reduce the quantum walk to an equivalent one on an Abelian group with coin system having larger dimension. This method allows one to extend the notion of wave-vector to the virtually Abelian case and study analytically the walk dynamics. We apply the technique in the case of two quantum walks on virtually Abelian groups with planar Cayley graphs, finding the exact solution in terms of dispersion relation.

  19. A radiance-based method for estimating uncertainties in the Atmospheric Infrared Sounder (AIRS) land surface temperature product

    Science.gov (United States)

    Hulley, Glynn C.; Hook, Simon J.

    2012-10-01

    Land Surface Temperature (LST) has been identified by NASA and other international organizations as an important Earth System Data Record (ESDR). An ESDR is defined as a long-term, well calibrated and validated data set. Identifying uncertainties in LST products with coarse spatial resolutions (>10 km) such as those from hyperspectral infrared sounders is notoriously difficult due to the challenges of making reliable in situ measurements representative of the spatial scales of the output products. In this study we utilize a Radiance-based (R-based) LST method for estimating uncertainties in the Atmospheric Infrared Sounder (AIRS) v5 LST product. The R-based method provides estimates of the true LST using a radiative closure simulation without the need for in situ measurements, and requires input air temperature, relative humidity profiles and emissivity data. The R-based method was employed at three validation sites over the Namib Desert, Gran Desierto, and Redwood National Park for all AIRS observations from 2002 to 2010. Results showed daytime LST root-mean square errors (RMSE) of 2-3 K at the Namib and Desierto sites, and 1.5 K at the Redwood site. Nighttime LST RMSEs at the two desert sites were a factor of two less when compared to daytime results. Positive daytime LST biases were found at each site due to an underestimation of the daytime AIRS v5 longwave spectral emissivity, while the reverse occurred at nighttime. In the AIRS v6 product (release 2012), LST biases and RMSEs will be reduced significantly due to improved methodologies for the surface retrieval and emissivity first guess.

  20. Estimating water consumption of potential natural vegetation on global dry lands: building an LCA framework for green water flows.

    Science.gov (United States)

    Núñez, Montserrat; Pfister, Stephan; Roux, Philippe; Antón, Assumpció

    2013-01-01

    This study aimed to provide a framework for assessing direct soil-water consumption, also termed green water in the literature, in life cycle assessment (LCA). This was an issue that LCA had not tackled before. The approach, which is applied during the life cycle inventory phase (LCI), consists of quantifying the net change in the evapo(transpi)ration of the production system compared to the natural reference situation. Potential natural vegetation (PNV) is used as the natural reference situation. In order to apply the method, we estimated PNV evapotranspiration adapted to local biogeographic conditions, on global dry lands, where soil-water consumption impacts can be critical. Values are reported at different spatial aggregation levels: 10-arcmin global grid, ecoregions (501 units), biomes (14 units), countries (124 units), continents, and a global average, to facilitate the assessment for different spatial information detail levels available in the LCI. The method is intended to be used in rain-fed agriculture and rainwater harvesting contexts, which includes direct soil moisture uptake by plants and rainwater harvested and then reused in production systems. The paper provides the necessary LCI method and data for further development of impact assessment models and characterization factors to evaluate the environmental effects of the net change in evapo(transpi)ration.

  1. Large scale air pollution estimation method combining land use regression and chemical transport modeling in a geostatistical framework.

    Science.gov (United States)

    Akita, Yasuyuki; Baldasano, Jose M; Beelen, Rob; Cirach, Marta; de Hoogh, Kees; Hoek, Gerard; Nieuwenhuijsen, Mark; Serre, Marc L; de Nazelle, Audrey

    2014-04-15

    In recognition that intraurban exposure gradients may be as large as between-city variations, recent air pollution epidemiologic studies have become increasingly interested in capturing within-city exposure gradients. In addition, because of the rapidly accumulating health data, recent studies also need to handle large study populations distributed over large geographic domains. Even though several modeling approaches have been introduced, a consistent modeling framework capturing within-city exposure variability and applicable to large geographic domains is still missing. To address these needs, we proposed a modeling framework based on the Bayesian Maximum Entropy method that integrates monitoring data and outputs from existing air quality models based on Land Use Regression (LUR) and Chemical Transport Models (CTM). The framework was applied to estimate the yearly average NO2 concentrations over the region of Catalunya in Spain. By jointly accounting for the global scale variability in the concentration from the output of CTM and the intraurban scale variability through LUR model output, the proposed framework outperformed more conventional approaches.

  2. walk around Irkutsk

    Directory of Open Access Journals (Sweden)

    Elena Grigoryeva

    2011-08-01

    Full Text Available It is noteworthy that this country develops through two types of events: either through a jubilee or through a catastrophe.It seems that Irkutsk Airport will be built only after the next crash. At least the interest to this problem returns regularly after sad events, and this occurs almost half a century (a jubilee, too! – the Council of Ministers decided to relocate the Airport away from the city as long ago as 1962. The Airport does not relate to the topic of this issue, but an attentive reader understands that it is our Carthage, and that the Airport should be relocated. The Romans coped with it faster and more effectively.Back to Irkutsk’s jubilee, we should say that we will do without blare of trumpets. We will just make an unpretentious walk around the city in its summer 350. Each our route covers new (some of them have been completed by the jubilee and old buildings, some of them real monuments. All these buildings are integrated into public spaces of different quality and age.We will also touch on the problems, for old houses, especially the wooden ones often provoke a greedy developer to demolish or to burn them down. Thus a primitive thrift estimates an output of additional square meters. Not to mention how attractive it is to seize public spaces without demolition or without reallocation of the dwellers. Or, rather, the one who is to preserve, to cherish and to improve such houses for the good of the citizens never speaks about this sensitive issue. So we have to do it.Walking is a no-hurry genre, unlike the preparation for the celebration. Walking around the city you like is a pleasant and cognitive process. It will acquaint the architects with the works of their predecessors and colleagues. We hope that such a walk may be interesting for Irkutsk citizens and visitors, too. Isn’t it interesting to learn “at first hand” the intimate details of the restoration of the Trubetskoys’ estate

  3. A global land-cover validation data set, II: augmenting a stratified sampling design to estimate accuracy by region and land-cover class

    NARCIS (Netherlands)

    Stehman, S.; Olofsson, P.; Woodcock, C.; Herold, M.; Friedl, M.A.

    2012-01-01

    A global validation database that can be used to assess the accuracy of multiple global and regional land-cover maps would yield significant cost savings and enhance comparisons of accuracy of different maps. Because the global validation database should expand over time as new validation data are c

  4. Attributing greenhouse gas emissions associated with land use and land use change to direct and indirect human and natural drivers: a modelling study to estimate their relative importance.

    Science.gov (United States)

    Hastings, Astley; Abdalla, Mohamed; Bell, Madeleine; Blagodatskiy, Sergey; Datta, Arindam; Dondini, Marta; Fitton, Nuala; Jones, Ed; Klumpp, Katja; Nemoto, Rie; Richards, Mark; Yeluripati, Jagadeesh; Smith, Pete

    2013-04-01

    Since humans cultivated crops, domesticated livestock and exploited woods and grasslands they have directly changed land use. In Europe, most of the landscapes are anthropogenically influenced. Each land use will have its carbon stock in the soil and vegetation that will depend on the geography, parent material of the soil, the climate and its land use history. For each land use and cover the soil carbon stock will reach a steady state where the rate of decomposition of the soil carbon is balanced by the organic material input each year. Each type of vegetation will reach a steady state depending on the length of its plants life cycle; for annual plants it is months, perennial grasslands it is years and for forest it is decades or centuries. In addition, the management of the crops, grasses or trees can be intensive, where the maximum vegetation is harvested or grazed, or extensive, when part of the plant material is left as a soil input. Net carbon flux will depend on the carbon balance between photosynthesis and respiration. Methane flux will mainly depend of the water content and redox potential of the soil and nitrous oxide emissions will depend of the type and amount of nitrogen input, pH and the relative timing of rainfall events, as well as the climatic conditions. In his study we have used site experiments to parameterize ecosystem models such as ECOSSE, DAYCENT, PASIM and DNDC on sites where there were more than one land use treatment to investigate the relative impact of human direct and indirect drivers compared to natural ones. Once the models have been parameterized the drivers to be investigated are systematically changed. The land uses investigated are grassland, forest, peatland and cropland. The direct drivers investigated are land use change (from cropland and grassland to bioenergy grasses, cropland to grassland and forest) and management change from intensive to extensive and vice versa. The management drivers investigated include tillage

  5. Caminhada em ambiente aquático e terrestre: revisão de literatura sobre a comparação das respostas neuromusculares e cardiorrespiratórias Walking on land and in water: a review study about the comparison of neuromuscular and cardiorespiratory responses

    Directory of Open Access Journals (Sweden)

    Eduardo Marczwski da Silva

    2008-12-01

    Full Text Available O objetivo deste estudo foi realizar uma revisão de literatura sobre a comparação das respostas neuromusculares e cardiorrespiratórias durante a caminhada em meio aquático e em meio terrestre. As respostas foram apresentadas para a caminhada em piscina rasa e para a caminhada em piscina funda. Em relação à caminhada em piscina rasa, as respostas neuromusculares (sinal EMG e cardiorrespiratórias (FC e VO2 são muito dependentes da velocidade do exercício. As respostas neuromusculares podem ser menores no meio aquático quando a velocidade da caminhada é menor nesse ambiente. Por outro lado, quando o exercício é realizado com velocidades similares, a atividade dos músculos propulsores pode ser superior durante a caminhada aquática. Da mesma forma, respostas cardiorrespiratórias maiores são registradas no exercício aquático quando velocidades similares de caminhada são utilizadas. Contudo, com velocidades menores, essas respostas são semelhantes ou menores que as encontradas em meio terrestre. No que diz respeito à caminhada em piscina funda, as respostas neuromusculares diferem daquelas encontradas durante a caminhada em meio terrestre devido à ausência das forças de reação com o solo. Essa característica possivelmente modifica os músculos envolvidos na produção de força propulsiva nesse exercício. Além do mais, durante a caminhada em piscina funda, as respostas cardiorrespiratórias parecem sempre mais baixas devido à grande redução no peso hidrostático e à menor atividade dos músculos posturais e pela utilização do cinturão flutuador nessa modalidade.The purpose of this review was to analyze neuromuscular and cardiorespiratory responses during walking in water and on dry land. The responses were presented during walking in shallow and in deep water. During walking in shallow water, neuromuscular (EMG signal and cardiorespiratory (HR and VO2 responses are very dependant on the exercise speed

  6. Sensitivity Study of Stochastic Walking Load Models

    DEFF Research Database (Denmark)

    Pedersen, Lars; Frier, Christian

    2010-01-01

    On flexible structures such as footbridges and long-span floors, walking loads may generate excessive structural vibrations and serviceability problems. The problem is increasing because of the growing tendency to employ long spans in structural design. In many design codes, the vibration...... serviceability limit state is assessed using a walking load model in which the walking parameters are modelled deterministically. However, the walking parameters are stochastic (for instance the weight of the pedestrian is not likely to be the same for every footbridge crossing), and a natural way forward...... investigates whether statistical distributions of bridge response are sensitive to some of the decisions made by the engineer doing the analyses. For the paper a selected part of potential influences are examined and footbridge responses are extracted using Monte-Carlo simulations and focus is on estimating...

  7. More Adults Are Walking

    Centers for Disease Control (CDC) Podcasts

    2012-07-31

    This podcast is based on the August 2012 CDC Vital Signs report. While more adults are walking, only half get the recommended amount of physical activity. Listen to learn how communities, employers, and individuals may help increase walking.  Created: 7/31/2012 by Centers for Disease Control and Prevention (CDC).   Date Released: 8/7/2012.

  8. Land Cover Mapping using GEOBIA to Estimate Loss of Salacca zalacca Trees in Landslide Area of Clapar, Madukara District of Banjarnegara

    Science.gov (United States)

    Permata, Anggi; Juniansah, Anwar; Nurcahyati, Eka; Dimas Afrizal, Mousafi; Adnan Shafry Untoro, Muhammad; Arifatha, Na'ima; Ramadhani Yudha Adiwijaya, Raden; Farda, Nur Mohammad

    2016-11-01

    Landslide is an unpredictable natural disaster which commonly happens in highslope area. Aerial photography in small format is one of acquisition method that can reach and obtain high resolution spatial data faster than other methods, and provide data such as orthomosaic and Digital Surface Model (DSM). The study area contained landslide area in Clapar, Madukara District of Banjarnegara. Aerial photographs of landslide area provided advantage in objects visibility. Object's characters such as shape, size, and texture were clearly seen, therefore GEOBIA (Geography Object Based Image Analysis) was compatible as method for classifying land cover in study area. Dissimilar with PPA (PerPixel Analyst) method that used spectral information as base object detection, GEOBIA could use spatial elements as classification basis to establish a land cover map with better accuracy. GEOBIA method used classification hierarchy to divide post disaster land cover into three main objects: vegetation, landslide/soil, and building. Those three were required to obtain more detailed information that can be used in estimating loss caused by landslide and establishing land cover map in landslide area. Estimating loss in landslide area related to damage in Salak (Salacca zalacca) plantations. This estimation towards quantity of Salak tree that were drifted away by landslide was calculated in assumption that every tree damaged by landslide had same age and production class with other tree that weren't damaged. Loss calculation was done by approximating quantity of damaged trees in landslide area with data of trees around area that were acquired from GEOBIA classification method.

  9. Does neighborhood walkability moderate the effects of intrapersonal characteristics on amount of walking in post-menopausal women?

    Science.gov (United States)

    Perry, Cynthia K; Herting, Jerald R; Berke, Ethan M; Nguyen, Huong Q; Vernez Moudon, Anne; Beresford, Shirley A A; Ockene, Judith K; Manson, Joann E; Lacroix, Andrea Z

    2013-05-01

    This study identifies factors associated with walking among postmenopausal women and tests whether neighborhood walkability moderates the influence of intrapersonal factors on walking. We used data from the Women's Health Initiative Seattle Center and linear regression models to estimate associations and interactions. Being white and healthy, having a high school education or beyond and greater non-walking exercise were significantly associated with more walking. Neighborhood walkability was not independently associated with greater walking, nor did it moderate influence of intrapersonal factors on walking. Specifying types of walking (e.g., for transportation) can elucidate the relationships among intrapersonal factors, the built environment, and walking.

  10. Biomechanical analysis of rollator walking

    DEFF Research Database (Denmark)

    Alkjaer, T; Larsen, Peter K; Pedersen, Gitte

    2006-01-01

    The rollator is a very popular walking aid. However, knowledge about how a rollator affects the walking patterns is limited. Thus, the purpose of the study was to investigate the biomechanical effects of walking with and without a rollator on the walking pattern in healthy subjects.......The rollator is a very popular walking aid. However, knowledge about how a rollator affects the walking patterns is limited. Thus, the purpose of the study was to investigate the biomechanical effects of walking with and without a rollator on the walking pattern in healthy subjects....

  11. An intercomparison of available soil moisture estimates from thermal infrared and passive microwave remote sensing and land surface modeling

    Science.gov (United States)

    Hain, Christopher R.; Crow, Wade T.; Mecikalski, John R.; Anderson, Martha C.; Holmes, Thomas

    2011-08-01

    Remotely sensed soil moisture studies have mainly focused on retrievals using active and passive microwave (MW) sensors, which provide measurements that are directly related to soil moisture (SM). MW sensors have obvious advantages such as the ability to retrieve through nonprecipitating cloud cover which provides shorter repeat cycles. However, MW sensors offer coarse spatial resolution and suffer from reduced retrieval skill over moderate to dense vegetation. A unique avenue for filling these information gaps is to exploit the retrieval of SM from thermal infrared (TIR) observations, which can provide SM information under vegetation cover and at significantly higher resolutions than MW. Previously, an intercomparison of TIR-based and MW-based SM has not been investigated in the literature. Here a series of analyses are proposed to study relationships between SM products during a multiyear period (2003-2008) from a passive MW retrieval (AMSR-E), a TIR based model (ALEXI), and a land surface model (Noah) over the continental United States. The three analyses used in this study include (1) a spatial anomaly correlation analysis, (2) a temporal correlation analysis, and (3) a triple collocation error estimation technique. In general, the intercomparison shows that the TIR and MW methods provide complementary information about the current SM state. TIR can provide SM information over moderate to dense vegetation, a large information gap in current MW methods, while serving as an additional independent source of SM information over low to moderate vegetation. The complementary nature of SM information from MW and TIR sensors implies a potential for integration within an advanced SM data assimilation system.

  12. Estimation of Land Surface Temperature through Blending MODIS and AMSR-E Data with the Bayesian Maximum Entropy Method

    Directory of Open Access Journals (Sweden)

    Xiaokang Kou

    2016-01-01

    Full Text Available Land surface temperature (LST plays a major role in the study of surface energy balances. Remote sensing techniques provide ways to monitor LST at large scales. However, due to atmospheric influences, significant missing data exist in LST products retrieved from satellite thermal infrared (TIR remotely sensed data. Although passive microwaves (PMWs are able to overcome these atmospheric influences while estimating LST, the data are constrained by low spatial resolution. In this study, to obtain complete and high-quality LST data, the Bayesian Maximum Entropy (BME method was introduced to merge 0.01° and 0.25° LSTs inversed from MODIS and AMSR-E data, respectively. The result showed that the missing LSTs in cloudy pixels were filled completely, and the availability of merged LSTs reaches 100%. Because the depths of LST and soil temperature measurements are different, before validating the merged LST, the station measurements were calibrated with an empirical equation between MODIS LST and 0~5 cm soil temperatures. The results showed that the accuracy of merged LSTs increased with the increasing quantity of utilized data, and as the availability of utilized data increased from 25.2% to 91.4%, the RMSEs of the merged data decreased from 4.53 °C to 2.31 °C. In addition, compared with the filling gap method in which MODIS LST gaps were filled with AMSR-E LST directly, the merged LSTs from the BME method showed better spatial continuity. The different penetration depths of TIR and PMWs may influence fusion performance and still require further studies.

  13. Self-Adaptive Revised Land Use Regression Models for Estimating PM2.5 Concentrations in Beijing, China

    Directory of Open Access Journals (Sweden)

    Lujin Hu

    2016-08-01

    Full Text Available Heavy air pollution, especially fine particulate matter (PM2.5, poses serious challenges to environmental sustainability in Beijing. Epidemiological studies and the identification of measures for preventing serious air pollution both require accurate PM2.5 spatial distribution data. Land use regression (LUR models are promising for estimating the spatial distribution of PM2.5 at a high spatial resolution. However, typical LUR models have a limited sampling point explanation rate (SPER, i.e., the rate of the sampling points with reasonable predicted concentrations to the total number of sampling points and accuracy. Hence, self-adaptive revised LUR models are proposed in this paper for improving the SPER and accuracy of typical LUR models. The self-adaptive revised LUR model combines a typical LUR model with self-adaptive LUR model groups. The typical LUR model was used to estimate the PM2.5 concentrations, and the self-adaptive LUR model groups were constructed for all of the sampling points removed from the typical LUR model because they were beyond the prediction data range, which was from 60% of the minimum observation to 120% of the maximum observation. The final results were analyzed using three methods, including an accuracy analysis, and were compared with typical LUR model results and the spatial variations in Beijing. The accuracy satisfied the demands of the analysis, and the accuracies at the different monitoring sites indicated spatial variations in the accuracy of the self-adaptive revised LUR model. The accuracy was high in the central area and low in suburban areas. The comparison analysis showed that the self-adaptive LUR model increased the SPER from 75% to 90% and increased the accuracy (based on the root-mean-square error from 20.643 μg/m3 to 17.443 μg/m3 for the PM2.5 concentrations during the winter of 2014 in Beijing. The spatial variation analysis for Beijing showed that the PM2.5 concentrations were low in the north

  14. Achieving scale-independent land-surface flux estimates - Application of the Multiscale Parameter Regionalization (MPR) to the Noah-MP land-surface model across the contiguous USA

    Science.gov (United States)

    Thober, S.; Mizukami, N.; Samaniego, L. E.; Attinger, S.; Clark, M. P.; Cuntz, M.

    2016-12-01

    Land-surface models use a variety of process representations to calculate terrestrial energy, water and biogeochemical fluxes. These process descriptions are usually derived from point measurements but are scaled to much larger resolutions in applications that range from about 1 km in catchment hydrology to 100 km in climate modelling. Both, hydrologic and climate models are nowadays run on different spatial resolutions, using the exact same land surface representations. A fundamental criterion for the physical consistency of land-surface simulations across scales is that a flux estimated over a given area is independent of the spatial model resolution (i.e., the flux-matching criterion). The Noah-MP land surface model considers only one soil and land cover type per model grid cell without any representation of subgrid variability, implying a weak flux-matching. A fractional approach simulates subgrid variability but it requires a higher computational demand than using effective parameters and it is used only for land cover in current land surface schemes. A promising approach to derive scale-independent parameters is the Multiscale Parameter Regionalization (MPR) technique, which consists of two steps: first, it applies transfer functions directly to high-resolution data (such as 100 m soil maps) to derive high-resolution model parameter fields, acknowledging the full subgrid variability. Second, it upscales these high-resolution parameter fields to the model resolution by using appropriate upscaling operators. MPR has shown to improve substantially the scalability of hydrologic models. Here, we apply the MPR technique to the Noah-MP land-surface model for a large sample of basins distributed across the contiguous USA. Specifically, we evaluate the flux-matching criterion for several hydrologic fluxes such as evapotranspiration and total runoff at scales ranging from 3 km to 48 km. We also investigate a p-norm scaling operator that goes beyond the current

  15. Quantum walks: a comprehensive review

    CERN Document Server

    Venegas-Andraca, Salvador E

    2012-01-01

    Quantum walks, the quantum mechanical counterpart of classical random walks, is an advanced tool for building quantum algorithms that has been recently shown to constitute a universal model of quantum computation. Quantum walks is now a solid field of research of quantum computation full of exciting open problems for physicists, computer scientists, mathematicians and engineers. In this paper we review theoretical advances on the foundations of both discrete- and continuous-time quantum walks, together with the role that randomness plays in quantum walks, the connections between the mathematical models of coined discrete quantum walks and continuous quantum walks, the quantumness of quantum walks, a summary of papers published on discrete quantum walks and entanglement as well as a succinct review of experimental proposals and realizations of discrete-time quantum walks. Furthermore, we have reviewed several algorithms based on both discrete- and continuous-time quantum walks as well as a most important resul...

  16. Walking - Sensing - Participation

    DEFF Research Database (Denmark)

    Bødker, Mads; Meinhardt, Nina Dam; Browning, David

    Building on ethnographic research and social theory in the field of ‘mobilities’, this workshop paper suggests that field work based on simply walking with people entails a form of embodied participation that informs technological interventions by creating a space within which to address a wider ...... set of experiential or ‘felt’ qualities of living with mobile technologies. Moving from reflections on the value of walking with people, the paper outlines some affordances of a smartphone application built to capture place experiences through walking....

  17. Estimation of evapotranspiration for different land covers in a Brazilian semi-arid region: A case study of the Brígida River basin, Brazil

    Science.gov (United States)

    Santos, Celso Augusto Guimarães; Silva, Richarde Marques da; Silva, Alexandro Medeiros; Brasil Neto, Reginaldo Moura

    2017-03-01

    In this study, the Surface Energy Balance Algorithm for Land (SEBAL) was used to compute the surface albedo, vegetation indices (NDVI, SAVI and LAI), surface temperature, soil heat flux and evapotranspiration (ET) over two contrasting years (dry and wet) in the Brígida River basin, a semi-arid region of north-eastern Brazil. The actual ET was computed during satellite overpass and was integrated for 24 h on a pixel-by-pixel basis for the daily ET distribution. Due to the topographic effects, an attempt was also made to incorporate DEM information to estimate the net radiation. The land cover types identified in the watershed are cropland, bare land, dense canopy, grassland, and caatinga vegetation. In order to study the variation among the biophysical parameters and ET, two-way analysis of variance (ANOVA) was used. The ET calculated by SEBAL ranged between 2.46 and 6.87 mm/day for the dry year (1990) and 1.31 and 6.84 mm/day for the wet year (2009) for the river basin. The results showed that a reduction in vegetation cover is evident in the temporal and spatial analysis over the studied periods in the region and that these facts influence the values of the energy balance and ET. The results showed significant differences in the variables of land cover type and year at the probability level of 0.05 for all land cover types.

  18. When Human Walking is a Random Walk

    Science.gov (United States)

    Hausdorff, J. M.

    1998-03-01

    The complex, hierarchical locomotor system normally does a remarkable job of controlling an inherently unstable, multi-joint system. Nevertheless, the stride interval --- the duration of a gait cycle --- fluctuates from one stride to the next, even under stationary conditions. We used random walk analysis to study the dynamical properties of these fluctuations under normal conditions and how they change with disease and aging. Random walk analysis of the stride-to-stride fluctuations of healthy, young adult men surprisingly reveals a self-similar pattern: fluctuations at one time scale are statistically similar to those at multiple other time scales (Hausdorff et al, J Appl Phsyiol, 1995). To study the stability of this fractal property, we analyzed data obtained from healthy subjects who walked for 1 hour at their usual pace, as well as at slower and faster speeds. The stride interval fluctuations exhibited long-range correlations with power-law decay for up to a thousand strides at all three walking rates. In contrast, during metronomically-paced walking, these long-range correlations disappeared; variations in the stride interval were uncorrelated and non-fractal (Hausdorff et al, J Appl Phsyiol, 1996). To gain insight into the mechanism(s) responsible for this fractal property, we examined the effects of aging and neurological impairment. Using detrended fluctuation analysis (DFA), we computed α, a measure of the degree to which one stride interval is correlated with previous and subsequent intervals over different time scales. α was significantly lower in healthy elderly subjects compared to young adults (p < .003) and in subjects with Huntington's disease, a neuro-degenerative disorder of the central nervous system, compared to disease-free controls (p < 0.005) (Hausdorff et al, J Appl Phsyiol, 1997). α was also significantly related to degree of functional impairment in subjects with Huntington's disease (r=0.78). Recently, we have observed that just as

  19. Crossover from random walk to self-avoiding walk

    Science.gov (United States)

    Rieger, Jens

    1988-11-01

    A one-dimensional n-step random walk on openZ1 which must not visit a vertex more than k times is studied via Monte Carlo methods. The dependences of the mean-square end-to-end distance of the walk and of the fraction of trapped walks on λ=(k-1)/n will be given for the range from λ=0 (self-avoiding walk) to λ=1 (unrestricted random walk). From the results it is conjectured that in the limit n-->∞ the walk obeys simple random walk statistics with respect to its static properties for all λ>0.

  20. Surface runoff estimation from various land use in Mapili Watershed using SCS Curve Number and Geographic Information System

    Science.gov (United States)

    Malahayati Yusuf, Sri; Guluda, David; Jayanegara, Trisumitra

    2017-01-01

    Mapili watershed which is located in West Sulawesi is dominated by secondary forest and agriculture land. The condition of the watershed is affected by land use and soil type. Land use is a form of interaction between man and land in order to meet their needs. Soil is function from organism, climate, topographic, material, and time. This information then will affect the hydrological condition in the watershed, especially surface runoff. The objective of study is to analyze the surface runoff in Mapili watershed. SCS curve number method that integrates with geographic information system was used in the analysis. The highest surface runoff value is about 887.6 mm and the highest of surface runoff coefficient is about 0.31.

  1. Adaptive Levy walks in foraging fallow deer.

    Directory of Open Access Journals (Sweden)

    Stefano Focardi

    Full Text Available BACKGROUND: Lévy flights are random walks, the step lengths of which come from probability distributions with heavy power-law tails, such that clusters of short steps are connected by rare long steps. Lévy walks maximise search efficiency of mobile foragers. Recently, several studies raised some concerns about the reliability of the statistical analysis used in previous analyses. Further, it is unclear whether Lévy walks represent adaptive strategies or emergent properties determined by the interaction between foragers and resource distribution. Thus two fundamental questions still need to be addressed: the presence of Lévy walks in the wild and whether or not they represent a form of adaptive behaviour. METHODOLOGY/PRINCIPAL FINDINGS: We studied 235 paths of solitary and clustered (i.e. foraging in group fallow deer (Dama dama, exploiting the same pasture. We used maximum likelihood estimation for discriminating between a power-tailed distribution and the exponential alternative and rank/frequency plots to discriminate between Lévy walks and composite Brownian walks. We showed that solitary deer perform Lévy searches, while clustered animals did not adopt that strategy. CONCLUSION/SIGNIFICANCE: Our demonstration of the presence of Lévy walks is, at our knowledge, the first available which adopts up-to-date statistical methodologies in a terrestrial mammal. Comparing solitary and clustered deer, we concluded that the Lévy walks of solitary deer represent an adaptation maximising encounter rates with forage resources and not an epiphenomenon induced by a peculiar food distribution.

  2. Validity of the Nike+ device during walking and running.

    Science.gov (United States)

    Kane, N A; Simmons, M C; John, D; Thompson, D L; Bassett, D R; Basset, D R

    2010-02-01

    We determined the validity of the Nike+ device for estimating speed, distance, and energy expenditure (EE) during walking and running. Twenty trained individuals performed a maximal oxygen uptake test and underwent anthropometric and body composition testing. Each participant was outfitted with a Nike+ sensor inserted into the shoe and an Apple iPod nano. They performed eight 6-min stages on the treadmill, including level walking at 55, 82, and 107 m x min(-1), inclined walking (82 m x min(-1)) at 5 and 10% grades, and level running at 134, 161, and 188 m x min(-1). Speed was measured using a tachometer and EE was measured by indirect calorimetry. Results showed that the Nike+ device overestimated the speed of level walking at 55 m x min(-1) by 20%, underestimated the speed of level walking at 107 m x min(-1) by 12%, but closely estimated the speed of level walking at 82 m x min(-1), and level running at all speeds (p<0.05). Similar results were found for distance. The Nike+ device overestimated the EE of level walking by 18-37%, but closely estimated the EE of level running (p<0.05). In conclusion the Nike+ in-shoe device provided reasonable estimates of speed and distance during level running at the three speeds tested in this study. However, it overestimated EE during level walking and it did not detect the increased cost of inclined locomotion.

  3. Toe Walking in Children

    Science.gov (United States)

    ... may simply monitor your child's gait during regular office visits. If a physical problem is contributing to toe walking, treatment options may include: Physical therapy. Gentle stretching of the leg and foot muscles may improve ...

  4. The Act of Walking

    DEFF Research Database (Denmark)

    Vestergaard, Maria Quvang Harck; Olesen, Mette; Helmer, Pernille Falborg

    2014-01-01

    individuals in Denmark conduct and experience walking, and the ‘rationalities’ (Giddens 1984) that lie behind their choice of mobility. It provides insight into how different lifestyles perceive and act walking in their everyday life. Kaufmann (2002) describes how the individual mobility is influenced......’ of mobility (Jensen 2013:111) such as the urban environment, and the infrastructures. Walking has indeed also a ‘software dimension’ as an embodied performance that trigger the human senses (Jensen 2013) and which is closely related to the habitus and identity of the individual (Halprin 1963). The individual...... by individual strategies, values, perceptions and habits, and how appropriation of mobility is constructed through the internalization of standards and values. The act of walking could thus be understood as the result of dynamic internal negotiation of individual, everyday mobility strategies (Lassen 2005...

  5. Nitrogen dioxide levels estimated from land use regression models several years apart and association with mortality in a large cohort study

    Directory of Open Access Journals (Sweden)

    Cesaroni Giulia

    2012-07-01

    Full Text Available Abstract Background Land Use Regression models (LUR are useful to estimate the spatial variability of air pollution in urban areas. Few studies have evaluated the stability of spatial contrasts in outdoor nitrogen dioxide (NO2 concentration over several years. We aimed to compare measured and estimated NO2 levels 12 years apart, the stability of the exposure estimates for members of a large cohort study, and the association of the exposure estimates with natural mortality within the cohort. Methods We measured NO2 at 67 locations in Rome in 1995/96 and 78 sites in 2007, over three one-week-long periods. To develop LUR models, several land-use and traffic variables were used. NO2 concentration at each residential address was estimated for a cohort of 684,000 adults. We used Cox regression to analyze the association between the two estimated exposures and mortality. Results The mean NO2 measured concentrations were 45.4 μg/m3 (SD 6.9 in 1995/96 and 44.6 μg/m3 (SD 11.0 in 2007, respectively. The correlation of the two measurements was 0.79. The LUR models resulted in adjusted R2 of 0.737 and 0.704, respectively. The correlation of the predicted exposure values for cohort members was 0.96. The association of each 10 μg/m3 increase in NO2 with mortality was 6 % for 1995/96 and 4 % for 2007 LUR models. The increased risk per an inter-quartile range change was identical (4 %, 95 % CI:3–6 % for both estimates of NO2. Conclusions Measured and predicted NO2 values from LUR models, from samples collected 12 years apart, had good agreement, and the exposure estimates were similarly associated with mortality in a large cohort study.

  6. Iterated random walks with shape prior

    DEFF Research Database (Denmark)

    Pujadas, Esmeralda Ruiz; Kjer, Hans Martin; Piella, Gemma;

    2016-01-01

    We propose a new framework for image segmentation using random walks where a distance shape prior is combined with a region term. The shape prior is weighted by a confidence map to reduce the influence of the prior in high gradient areas and the region term is computed with k-means to estimate th...

  7. Performance and effects of land cover type on synthetic surface reflectance data and NDVI estimates for assessment and monitoring of semi-arid rangeland

    Science.gov (United States)

    Olexa, Edward M.; Lawrence, Rick L

    2014-01-01

    Federal land management agencies provide stewardship over much of the rangelands in the arid andsemi-arid western United States, but they often lack data of the proper spatiotemporal resolution andextent needed to assess range conditions and monitor trends. Recent advances in the blending of com-plementary, remotely sensed data could provide public lands managers with the needed information.We applied the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) to five Landsat TMand concurrent Terra MODIS scenes, and used pixel-based regression and difference image analyses toevaluate the quality of synthetic reflectance and NDVI products associated with semi-arid rangeland. Pre-dicted red reflectance data consistently demonstrated higher accuracy, less bias, and stronger correlationwith observed data than did analogous near-infrared (NIR) data. The accuracy of both bands tended todecline as the lag between base and prediction dates increased; however, mean absolute errors (MAE)were typically ≤10%. The quality of area-wide NDVI estimates was less consistent than either spectra lband, although the MAE of estimates predicted using early season base pairs were ≤10% throughout the growing season. Correlation between known and predicted NDVI values and agreement with the 1:1regression line tended to decline as the prediction lag increased. Further analyses of NDVI predictions,based on a 22 June base pair and stratified by land cover/land use (LCLU), revealed accurate estimates through the growing season; however, inter-class performance varied. This work demonstrates the successful application of the STARFM algorithm to semi-arid rangeland; however, we encourage evaluation of STARFM’s performance on a per product basis, stratified by LCLU, with attention given to the influence of base pair selection and the impact of the time lag.

  8. Biomechanical analysis of rollator walking

    Directory of Open Access Journals (Sweden)

    Nielsen Linda H

    2006-01-01

    Full Text Available Abstract Background The rollator is a very popular walking aid. However, knowledge about how a rollator affects the walking patterns is limited. Thus, the purpose of the study was to investigate the biomechanical effects of walking with and without a rollator on the walking pattern in healthy subjects. Methods The walking pattern during walking with and without rollator was analyzed using a three-dimensional inverse dynamics method. Sagittal joint dynamics and kinematics of the ankle, knee and hip were calculated. In addition, hip joint dynamics and kinematics in the frontal plane were calculated. Seven healthy women participated in the study. Results The hip was more flexed while the knee and ankle joints were less flexed/dorsiflexed during rollator walking. The ROM of the ankle and knee joints was reduced during rollator-walking. Rollator-walking caused a reduction in the knee extensor moment by 50% when compared to normal walking. The ankle plantarflexor and hip abductor moments were smaller when walking with a rollator. In contrast, the angular impulse of the hip extensors was significantly increased during rollator-walking. Conclusion Walking with a rollator unloaded the ankle and especially the knee extensors, increased the hip flexion and thus the contribution of hip extensors to produce movement. Thus, rollator walking did not result in an overall unloading of the muscles and joints of the lower extremities. However, the long-term effect of rollator walking is unknown and further investigation in this field is needed.

  9. Measurement and estimation of radiocesium discharge rate from paddy field during land preparation and mid-summer drainage.

    Science.gov (United States)

    Miyazu, Susumu; Yasutaka, Tetsuo; Yoshikawa, Natsuki; Tamaki, Shouhei; Nakajima, Kousei; Sato, Iku; Nonaka, Masanori; Harada, Naoki

    2016-05-01

    In this research, we evaluated the range of (137)Cs discharge rates from paddy fields during land preparation and mid-summer drainage. First, we investigated (137)Cs discharge loads during land preparation and mid-summer drainage and their ratio to the (137)Cs inventory of paddy field soil. We found that total discharge rates were 0.003-0.028% during land preparation and 0.001-0.011% during mid-summer drainage. Next, we validated the range of obtained total discharge of (137)Cs from the paddy fields using a simplified equation and literature review. As a result, we conclude that the range of total outflow loads of suspended solids for the investigated paddy field was generally representative of paddy fields in Japan. Moreover, the (137)Cs discharge ratio had a wide range, but was extremely small relative to (137)Cs present in paddy field soil before irrigation.

  10. Establishing the Range of Perceptually Natural Visual Walking Speeds for Virtual Walking-In-Place Locomotion

    DEFF Research Database (Denmark)

    Nilsson, Niels Christian; Serafin, Stefania; Nordahl, Rolf

    2014-01-01

    from 1.0 to 3.0. Thus, the slowest speed was equal to an estimate of the subjects normal walking speed, while the highest speed was three times greater. The perceived naturalness of the visual speed was assessed using self-reports. The first study compared four different types of movement, namely...... to virtual motion. This paper describes two within-subjects studies performed with the intention of establishing the range of perceptually natural walking speeds for WIP locomotion. In both studies, subjects performed a series of virtual walks while exposed to visual gains (optic flow multipliers) ranging......, no leg movement, walking on a treadmill, and two forms of gestural input for WIP locomotion. The results suggest that WIP locomotion is accompanied by a perceptual distortion of the speed of optic flow. The second study was performed using a 4×2 factorial design and compared four different display field...

  11. Walking for Health in Pregnancy: Assessment by Indirect Calorimetry and Accelerometry

    Science.gov (United States)

    DiNallo, Jennifer M.; Le Masurier, Guy C.; Williams, Nancy I.; Downs, Danielle Symons

    2008-01-01

    The purpose of this study was to examine RT3 accelerometer activity counts and activity energy expenditure of 36 pregnant women at 20 and 32 weeks' gestation during treadmill walking and free-living conditions. During treadmill walking, oxygen consumption was collected, and activity energy expenditure was estimated for a 30-min walk at a…

  12. Walking for Health in Pregnancy: Assessment by Indirect Calorimetry and Accelerometry

    Science.gov (United States)

    DiNallo, Jennifer M.; Le Masurier, Guy C.; Williams, Nancy I.; Downs, Danielle Symons

    2008-01-01

    The purpose of this study was to examine RT3 accelerometer activity counts and activity energy expenditure of 36 pregnant women at 20 and 32 weeks' gestation during treadmill walking and free-living conditions. During treadmill walking, oxygen consumption was collected, and activity energy expenditure was estimated for a 30-min walk at a…

  13. Parameter estimation of a physically-based land surface hydrologic model using an ensemble Kalman filter: A multivariate real-data experiment

    Science.gov (United States)

    Shi, Yuning; Davis, Kenneth J.; Zhang, Fuqing; Duffy, Christopher J.; Yu, Xuan

    2015-09-01

    The capability of an ensemble Kalman filter (EnKF) to simultaneously estimate multiple parameters in a physically-based land surface hydrologic model using multivariate field observations is tested at a small watershed (0.08 km2). Multivariate, high temporal resolution, in situ measurements of discharge, water table depth, soil moisture, and sensible and latent heat fluxes encompassing five months of 2009 are assimilated. It is found that, for five out of the six parameters, the EnKF estimated parameter values from different test cases converge strongly, and the estimates after convergence are close to the manually calibrated parameter values. The EnKF estimated parameters and manually calibrated parameters yield similar model performance, but the EnKF sequential method significantly decreases the time and labor required for calibration. The results demonstrate that, given a limited number of multi-state, site-specific observations, an automated sequential calibration method (EnKF) can be used to optimize physically-based land surface hydrologic models.

  14. Random walk term weighting for information retrieval

    DEFF Research Database (Denmark)

    Blanco, R.; Lioma, Christina

    2007-01-01

    We present a way of estimating term weights for Information Retrieval (IR), using term co-occurrence as a measure of dependency between terms.We use the random walk graph-based ranking algorithm on a graph that encodes terms and co-occurrence dependencies in text, from which we derive term weights...... that represent a quantification of how a term contributes to its context. Evaluation on two TREC collections and 350 topics shows that the random walk-based term weights perform at least comparably to the traditional tf-idf term weighting, while they outperform it when the distance between co-occurring terms...

  15. Walk Score, Transportation Mode Choice, and Walking Among French Adults: A GPS, Accelerometer, and Mobility Survey Study

    Directory of Open Access Journals (Sweden)

    Dustin T. Duncan

    2016-06-01

    Full Text Available Background: Few studies have used GPS data to analyze the relationship between Walk Score, transportation choice and walking. Additionally, the influence of Walk Score is understudied using trips rather than individuals as statistical units. The purpose of this study is to examine associations at the trip level between Walk Score, transportation mode choice, and walking among Paris adults who were tracked with GPS receivers and accelerometers in the RECORD GPS Study. Methods: In the RECORD GPS Study, 227 participants were tracked during seven days with GPS receivers and accelerometers. Participants were also surveyed with a GPS-based web mapping application on their activities and transportation modes for all trips (6969 trips. Walk Score, which calculates neighborhood walkability, was assessed for each origin and destination of every trip. Multilevel logistic and linear regression analyses were conducted to estimate associations between Walk Score and walking in the trip or accelerometry-assessed number of steps for each trip, after adjustment for individual/neighborhood characteristics. Results: The mean overall Walk Scores for trip origins were 87.1 (SD = 14.4 and for trip destinations 87.1 (SD = 14.5. In adjusted trip-level associations between Walk Score and walking only in the trip, we found that a walkable neighborhood in the trip origin and trip destination was associated with increased odds of walking in the trip assessed in the survey. The odds of only walking in the trip were 3.48 (95% CI: 2.73 to 4.44 times higher when the Walk Score for the trip origin was “Walker’s Paradise” compared to less walkable neighborhoods (Very/Car-Dependent or Somewhat Walkable, with an identical independent effect of trip destination Walk Score on walking. The number of steps per 10 min (as assessed with accelerometry was cumulatively higher for trips both originating and ending in walkable neighborhoods (i.e., “Very Walkable”. Conclusions

  16. Spatial estimation of air PM2.5 emissions using activity data, local emission factors and land cover derived from satellite imagery

    Directory of Open Access Journals (Sweden)

    H. P. Gibe

    2017-09-01

    Full Text Available Exposure to particulate matter (PM is a serious environmental problem in many urban areas on Earth. In the Philippines, most existing studies and emission inventories have mainly focused on point and mobile sources, while research involving human exposures to particulate pollutants is rare. This paper presents a method for estimating the amount of fine particulate (PM2.5 emissions in a test study site in the city of Cabanatuan, Nueva Ecija, in the Philippines, by utilizing local emission factors, regionally procured data, and land cover/land use (activity data interpreted from satellite imagery. Geographic information system (GIS software was used to map the estimated emissions in the study area. The present results suggest that vehicular emissions from motorcycles and tricycles, as well as fuels used by households (charcoal and burning of agricultural waste, largely contribute to PM2.5 emissions in Cabanatuan. Overall, the method used in this study can be applied in other small urbanizing cities, as long as on-site specific activity, emission factor, and satellite-imaged land cover data are available.

  17. Spatial estimation of air PM2.5 emissions using activity data, local emission factors and land cover derived from satellite imagery

    Science.gov (United States)

    Gibe, Hezron P.; Cayetano, Mylene G.

    2017-09-01

    Exposure to particulate matter (PM) is a serious environmental problem in many urban areas on Earth. In the Philippines, most existing studies and emission inventories have mainly focused on point and mobile sources, while research involving human exposures to particulate pollutants is rare. This paper presents a method for estimating the amount of fine particulate (PM2.5) emissions in a test study site in the city of Cabanatuan, Nueva Ecija, in the Philippines, by utilizing local emission factors, regionally procured data, and land cover/land use (activity data) interpreted from satellite imagery. Geographic information system (GIS) software was used to map the estimated emissions in the study area. The present results suggest that vehicular emissions from motorcycles and tricycles, as well as fuels used by households (charcoal) and burning of agricultural waste, largely contribute to PM2.5 emissions in Cabanatuan. Overall, the method used in this study can be applied in other small urbanizing cities, as long as on-site specific activity, emission factor, and satellite-imaged land cover data are available.

  18. Climate, water management, and land use: Estimating potential potato and corn production in the U.S. northeastern seaboard region

    Science.gov (United States)

    The potential production capacity of the United States Northeastern Seaboard Region (NESR) was assessed using corn and potato as representative commodities. Geospatial data regarding historical climate, land use, soils, and management were coupled with a weather generator, the crop models SPUDSIM a...

  19. Unitary equivalence of quantum walks

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, Sandeep K., E-mail: sandeep.goyal@ucalgary.ca [School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X54001, 4000 Durban (South Africa); Konrad, Thomas [School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X54001, 4000 Durban (South Africa); National Institute for Theoretical Physics (NITheP), KwaZulu-Natal (South Africa); Diósi, Lajos [Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, H-1525 Budapest 114, P.O.B. 49 (Hungary)

    2015-01-23

    Highlights: • We have found unitary equivalent classes in coined quantum walks. • A single parameter family of coin operators is sufficient to realize all simple one-dimensional quantum walks. • Electric quantum walks are unitarily equivalent to time dependent quantum walks. - Abstract: A simple coined quantum walk in one dimension can be characterized by a SU(2) operator with three parameters which represents the coin toss. However, different such coin toss operators lead to equivalent dynamics of the quantum walker. In this manuscript we present the unitary equivalence classes of quantum walks and show that all the nonequivalent quantum walks can be distinguished by a single parameter. Moreover, we argue that the electric quantum walks are equivalent to quantum walks with time dependent coin toss operator.

  20. Method for estimating potential wetland extent by utilizing streamflow statistics and flood-inundation mapping techniques: Pilot study for land along the Wabash River near Terre Haute, Indiana

    Science.gov (United States)

    Kim, Moon H.; Ritz, Christian T.; Arvin, Donald V.

    2012-01-01

    Potential wetland extents were estimated for a 14-mile reach of the Wabash River near Terre Haute, Indiana. This pilot study was completed by the U.S. Geological Survey in cooperation with the U.S. Department of Agriculture, Natural Resources Conservation Service (NRCS). The study showed that potential wetland extents can be estimated by analyzing streamflow statistics with the available streamgage data, calculating the approximate water-surface elevation along the river, and generating maps by use of flood-inundation mapping techniques. Planning successful restorations for Wetland Reserve Program (WRP) easements requires a determination of areas that show evidence of being in a zone prone to sustained or frequent flooding. Zone determinations of this type are used by WRP planners to define the actively inundated area and make decisions on restoration-practice installation. According to WRP planning guidelines, a site needs to show evidence of being in an "inundation zone" that is prone to sustained or frequent flooding for a period of 7 consecutive days at least once every 2 years on average in order to meet the planning criteria for determining a wetland for a restoration in agricultural land. By calculating the annual highest 7-consecutive-day mean discharge with a 2-year recurrence interval (7MQ2) at a streamgage on the basis of available streamflow data, one can determine the water-surface elevation corresponding to the calculated flow that defines the estimated inundation zone along the river. By using the estimated water-surface elevation ("inundation elevation") along the river, an approximate extent of potential wetland for a restoration in agricultural land can be mapped. As part of the pilot study, a set of maps representing the estimated potential wetland extents was generated in a geographic information system (GIS) application by combining (1) a digital water-surface plane representing the surface of inundation elevation that sloped in the downstream

  1. Six-minute-walk test in chronic obstructive pulmonary disease

    DEFF Research Database (Denmark)

    Polkey, Michael I; Spruit, Martijn A; Edwards, Lisa D

    2013-01-01

    Outcomes other than spirometry are required to assess nonbronchodilator therapies for chronic obstructive pulmonary disease. Estimates of the minimal clinically important difference for the 6-minute-walk distance (6MWD) have been derived from narrow cohorts using nonblinded intervention.......Outcomes other than spirometry are required to assess nonbronchodilator therapies for chronic obstructive pulmonary disease. Estimates of the minimal clinically important difference for the 6-minute-walk distance (6MWD) have been derived from narrow cohorts using nonblinded intervention....

  2. Estimation of soil erosion for a sustainable land use planning: RUSLE model validation by remote sensing data utilization in the Kalikonto watershed

    Directory of Open Access Journals (Sweden)

    C. Andriyanto

    2015-10-01

    Full Text Available Technology of Geographic Information Systems (GIS and Remote Sensing (RS are increasingly used for planning and natural resources management. GIS and RS is based on pixels is used as a tool of spatial modeling for predicting the erosion. One of the methods developed for predicting the erosion is a Revised Universal Soil Loss Equation (RUSLE. RUSLE is the method used for predicting the erosion associated with runoff gained from five parameters, namely: rain erosivity (R, soil erodibility (K, length of slopes (L, slope (S, and land management (CP. The main constraint encountered in the process of operating the GIS is the calculation of the slope length factor (L.This study was designed to create a plan of sustainable land use and low erosion through the RULSE erosion modeling by utilizing the remote sensing data. With this approach, this study was divided into three activities, namely (1 the preparation and analysis of spatial data for the determination of the parameters and estimating the erosion by using RUSLE models, (2 the validation and calibration of the model of RUSLE by measuring soil erosion at the scale of plots on the field, and (3 Creating a plan of sustainable land use and low erosion with RUSLE. The validation erosion shows the value of R2 = 0.56 and r = 0.74. Results of this study showed that the RUSLE model could be used in the Kalikonto watershed. The erosions at the value of the actual estimation, spatial Plan (RTRW and land capability class in the Kalikonto watershed were 72t / ha / year, 62 t / ha / year and 58 t / ha / year, respectively.

  3. Walking With Meaning

    Directory of Open Access Journals (Sweden)

    Jennifer McDuff

    2015-09-01

    Full Text Available Physical activity is beneficial for people with dementia, but little research explores subjective experiences of physical activity in this population. Interpretive description guided the analysis of 26 interviews conducted with 12 people with dementia. Three themes described the subjective meaning of everyday physical activity: Participants were attracted to activity because it improved physical well-being, provided social connections, gave opportunity to be in nature, and provided structure and focus; participants experienced impediments to activity because of physical discomfort, environmental factors, lack of enthusiasm, and memory loss; and participants made adjustments by choosing walking over other activities and by being active with others. Results show that physical activity remains important for people with dementia, although they encounter barriers. They may prefer walking with others as a form of activity. Findings could influence how nurses conceptualize wandering and suggest that walking programs could be well received by people with dementia.

  4. Biomechanical conditions of walking

    CERN Document Server

    Fan, Y F; Luo, L P; Li, Z Y; Han, S Y; Lv, C S; Zhang, B

    2015-01-01

    The development of rehabilitation training program for lower limb injury does not usually include gait pattern design. This paper introduced a gait pattern design by using equations (conditions of walking). Following the requirements of reducing force to the injured side to avoid further injury, we developed a lower limb gait pattern to shorten the stride length so as to reduce walking speed, to delay the stance phase of the uninjured side and to reduce step length of the uninjured side. This gait pattern was then verified by the practice of a rehabilitation training of an Achilles tendon rupture patient, whose two-year rehabilitation training (with 24 tests) has proven that this pattern worked as intended. This indicates that rehabilitation training program for lower limb injury can rest on biomechanical conditions of walking based on experimental evidence.

  5. Bouncing and walking droplets

    Science.gov (United States)

    Molacek, Jan; Bush, John

    2012-11-01

    Motivated by the hydrodynamic quantum analogue system of Yves Couder, we examine the dynamics of silicone oil drops bouncing on a vertically vibrating liquid bath. We report regime diagrams indicating the dependence of the vertical drop motion on the system parameters. A logarithmic spring model for the interface is developed, and provides new rationale for the regime diagrams. We further examine the spatio-temporal evolution of the standing waves created on the bath surface by repeated drop impacts. Measurement of the tangential coefficient of restitution of drops bouncing on a quiescent bath enables us to accurately determine all the major forces acting on the drop during flight and impact. By combining the horizontal and vertical dynamics, we thus develop a model for the walking drops that enables us to rationalize both the extent of the walking regime and the walking speeds. The model predictions compare favorably with experimental data in the parameter range explored.

  6. Ways of Walking

    DEFF Research Database (Denmark)

    Eslambolchilar, Parisa; Bødker, Mads; Chamberlain, Alan

    2016-01-01

    It seems logical to argue that mobile computing technologies are intended for use "on-the-go." However, on closer inspection, the use of mobile technologies pose a number of challenges for users who are mobile, particularly moving around on foot. In engaging with such mobile technologies...... and their envisaged development, we argue that interaction designers must increasingly consider a multitude of perspectives that relate to walking in order to frame design problems appropriately. In this paper, we consider a number of perspectives on walking, and we discuss how these may inspire the design of mobile...... technologies. Drawing on insights from non-representational theory, we develop a partial vocabulary with which to engage with qualities of pedestrian mobility, and we outline how taking more mindful approaches to walking may enrich and inform the design space of handheld technologies....

  7. Probabilistic estimation of future emissions of isoprene and surface oxidant chemistry associated with land use change in response to growing food needs

    Directory of Open Access Journals (Sweden)

    C. J. Hardacre

    2012-12-01

    Full Text Available We quantify the impact of land use change, determined by our growing need for food and biofuel production, on isoprene emissions and subsequent atmospheric oxidant chemistry in 2015 and 2030, relative to 1990, ignoring compound climate change effects over that period. We estimate isoprene emissions from an ensemble (n = 1000 of land use change realizations from 1990–2050, broadly guided by the IPCC AR4/SRES scenarios A1 and B1. We also superimpose land use change required to address projected biofuel usage using two scenarios: (1 assuming that world governments make no changes to biofuel policy after 2009, and (2 assuming that world governments develop biofuel policy with the aim of keeping equivalent atmospheric CO2 at 450 ppm. We present the median and interquartile range (IQR statistics of the ensemble and show that land use change between −1.50 × 1012 m2 to +6.06 × 1012 m2 was found to drive changes in the global isoprene burden of −3.5 to +2.8 Tg yr−1 in 2015 and −7.7 to +6.4 Tg yr−1 in 2030. We use land use change realizations corresponding to the median and IQR of these emission estimates to drive the GEOS-Chem global 3-D chemistry transport model to investigate the perturbation to global and regional surface concentrations of isoprene, nitrogen oxides (NO+NO2, and the atmospheric concentration and deposition of ozone (O3. We show that across sub-continental regions the monthly surface O3 increases by 0.1–0.8 ppb, relative to a zero land-use change calculation, driven by increases (decreases in surface isoprene in high (low NOx environments. At the local scale (4° × 5° we find that surface O3 increases by 5–12 ppb over temperate North America, China and Boreal Eurasia, driven by large increases in isoprene emissions from short-rotation coppice crop cultivation for biofuel

  8. Probabilistic estimation of future emissions of isoprene and surface oxidant chemistry associated with land-use change in response to growing food needs

    Directory of Open Access Journals (Sweden)

    C. J. Hardacre

    2013-06-01

    Full Text Available We quantify the impact of land-use change, determined by our growing demand for food and biofuel production, on isoprene emissions and subsequent atmospheric oxidant chemistry in 2015 and 2030, relative to 1990, ignoring compound climate change effects over that period. We estimate isoprene emissions from an ensemble (n = 1000 of land-use change realizations from 1990–2050, broadly guided by the IPCC AR4/SRES scenarios A1 and B1. We also superimpose land-use change required to address projected biofuel usage using two scenarios: (1 assuming that world governments make no changes to biofuel policy after 2009, and (2 assuming that world governments develop biofuel policy with the aim of keeping equivalent atmospheric CO2 at 450 ppm. We present the median and interquartile range (IQR statistics of the ensemble and show that land-use change between −1.50 × 1012 m2 to +6.06 × 1012 m2 was found to drive changes in the global isoprene burden of −3.5 to +2.8 Tg yr−1 in 2015 and −7.7 to +6.4 Tg yr−1 in 2030. We use land-use change realizations corresponding to the median and IQR of these emission estimates to drive the GEOS-Chem global 3-D chemistry transport model to investigate the perturbation to global and regional surface concentrations of isoprene, nitrogen oxides (NO+NO2, and the atmospheric concentration and deposition of ozone (O3. We show that across subcontinental regions the monthly surface O3 increases by 0.1–0.8 ppb, relative to a zero land-use change calculation, driven by increases (decreases in surface isoprene in high (low NOx environments. At the local scale (4° × 5° we find that surface O3 increases by 5–12 ppb over temperate North America, China and boreal Eurasia, driven by large increases in isoprene emissions from short-rotation coppice crop cultivation for biofuel production.

  9. Probabilistic estimation of future emissions of isoprene and surface oxidant chemistry associated with land use change in response to growing food needs

    Science.gov (United States)

    Hardacre, C. J.; Palmer, P. I.; Baumanns, K.; Rounsevell, M.; Murray-Rust, D.

    2012-12-01

    We quantify the impact of land use change, determined by our growing need for food and biofuel production, on isoprene emissions and subsequent atmospheric oxidant chemistry in 2015 and 2030, relative to 1990, ignoring compound climate change effects over that period. We estimate isoprene emissions from an ensemble (n = 1000) of land use change realizations from 1990-2050, broadly guided by the IPCC AR4/SRES scenarios A1 and B1. We also superimpose land use change required to address projected biofuel usage using two scenarios: (1) assuming that world governments make no changes to biofuel policy after 2009, and (2) assuming that world governments develop biofuel policy with the aim of keeping equivalent atmospheric CO2 at 450 ppm. We present the median and interquartile range (IQR) statistics of the ensemble and show that land use change between -1.50 × 1012 m2 to +6.06 × 1012 m2 was found to drive changes in the global isoprene burden of -3.5 to +2.8 Tg yr-1 in 2015 and -7.7 to +6.4 Tg yr-1 in 2030. We use land use change realizations corresponding to the median and IQR of these emission estimates to drive the GEOS-Chem global 3-D chemistry transport model to investigate the perturbation to global and regional surface concentrations of isoprene, nitrogen oxides (NO+NO2), and the atmospheric concentration and deposition of ozone (O3). We show that across sub-continental regions the monthly surface O3 increases by 0.1-0.8 ppb, relative to a zero land-use change calculation, driven by increases (decreases) in surface isoprene in high (low) NOx environments. At the local scale (4° × 5°) we find that surface O3 increases by 5-12 ppb over temperate North America, China and Boreal Eurasia, driven by large increases in isoprene emissions from short-rotation coppice crop cultivation for biofuel production.

  10. Probabilistic estimation of future emissions of isoprene and surface oxidant chemistry associated with land-use change in response to growing food needs

    Science.gov (United States)

    Hardacre, C. J.; Palmer, P. I.; Baumanns, K.; Rounsevell, M.; Murray-Rust, D.

    2013-06-01

    We quantify the impact of land-use change, determined by our growing demand for food and biofuel production, on isoprene emissions and subsequent atmospheric oxidant chemistry in 2015 and 2030, relative to 1990, ignoring compound climate change effects over that period. We estimate isoprene emissions from an ensemble (n = 1000) of land-use change realizations from 1990-2050, broadly guided by the IPCC AR4/SRES scenarios A1 and B1. We also superimpose land-use change required to address projected biofuel usage using two scenarios: (1) assuming that world governments make no changes to biofuel policy after 2009, and (2) assuming that world governments develop biofuel policy with the aim of keeping equivalent atmospheric CO2 at 450 ppm. We present the median and interquartile range (IQR) statistics of the ensemble and show that land-use change between -1.50 × 1012 m2 to +6.06 × 1012 m2 was found to drive changes in the global isoprene burden of -3.5 to +2.8 Tg yr-1 in 2015 and -7.7 to +6.4 Tg yr-1 in 2030. We use land-use change realizations corresponding to the median and IQR of these emission estimates to drive the GEOS-Chem global 3-D chemistry transport model to investigate the perturbation to global and regional surface concentrations of isoprene, nitrogen oxides (NO+NO2), and the atmospheric concentration and deposition of ozone (O3). We show that across subcontinental regions the monthly surface O3 increases by 0.1-0.8 ppb, relative to a zero land-use change calculation, driven by increases (decreases) in surface isoprene in high (low) NOx environments. At the local scale (4° × 5°) we find that surface O3 increases by 5-12 ppb over temperate North America, China and boreal Eurasia, driven by large increases in isoprene emissions from short-rotation coppice crop cultivation for biofuel production.

  11. From Walking to Running

    Science.gov (United States)

    Rummel, Juergen; Blum, Yvonne; Seyfarth, Andre

    The implementation of bipedal gaits in legged robots is still a challenge in state-of-the-art engineering. Human gaits could be realized by imitating human leg dynamics where a spring-like leg behavior is found as represented in the bipedal spring-mass model. In this study we explore the gap between walking and running by investigating periodic gait patterns. We found an almost continuous morphing of gait patterns between walking and running. The technical feasibility of this transition is, however, restricted by the duration of swing phase. In practice, this requires an abrupt gait transition between both gaits, while a change of speed is not necessary.

  12. The Act of Walking

    DEFF Research Database (Denmark)

    Vestergaard, Maria Quvang Harck; Olesen, Mette; Helmer, Pernille Falborg

    2014-01-01

    ’ of mobility (Jensen 2013:111) such as the urban environment, and the infrastructures. Walking has indeed also a ‘software dimension’ as an embodied performance that trigger the human senses (Jensen 2013) and which is closely related to the habitus and identity of the individual (Halprin 1963). The individual...... the individuals evaluate, interpret and act (Bourdieu 1984), and how this affects their choice to walk. Therefore it could be questioned if whether an assessment of the physical environment is sufficient to identify all the factors that influence the individual perception of ‘walkability’, or if other influencing...

  13. Walking for data

    DEFF Research Database (Denmark)

    Bødker, Mads; Browning, David; Meinhardt, Nina Dam

    We suggest that ‘walking’ in ethnographic work sensitizes researchers to a particular means of making sense of place. Following a brief conceptual exposition, we present our research tool iMaCam) that supports capturing and representing activities such as walking.......We suggest that ‘walking’ in ethnographic work sensitizes researchers to a particular means of making sense of place. Following a brief conceptual exposition, we present our research tool iMaCam) that supports capturing and representing activities such as walking....

  14. Aperiodic Quantum Random Walks

    CERN Document Server

    Ribeiro, P; Mosseri, R; Ribeiro, Pedro; Milman, Perola; Mosseri, Remy

    2004-01-01

    We generalize the quantum random walk protocol for a particle in a one-dimensional chain, by using several types of biased quantum coins, arranged in aperiodic sequences, in a manner that leads to a rich variety of possible wave function evolutions. Quasiperiodic sequences, following the Fibonacci prescription, are of particular interest, leading to a sub-ballistic wavefunction spreading. In contrast, random sequences leads to diffusive spreading, similar to the classical random walk behaviour. We also describe how to experimentally implement these aperiodic sequences.

  15. Application of small baseline subsets D-InSAR technique to estimate time series land deformation of Jinan area, China

    Science.gov (United States)

    Liu, Xiangtong; Cao, Qiuxiang; Xiong, Zhuguo; Yin, Haitao; Xiao, Genru

    2016-04-01

    Jinan, located in the South of the North China Plain, is an area where underground water has been exploited excessively. However, land deformation surveys only focus on the small district obtained by GPS and Leveling. Here, we use interferometric synthetic aperture radar (InSAR) time-series of ASAR data to resolve land subsidence in the entire Jinan region. In our research, we get 20 interferograms with a temporal threshold of 700 days and spatial-baseline threshold of 300 m from 14 ASAR satellite images on a descending orbit, and then get the surface displacement using Small Baseline InSAR (SBAS D-InSAR) retrained with a periodic model. Meanwhile, the accuracy of our work is proved by the results of GPS measurements. Finally, several settlement funnels are observed with extreme values of -20 cm, and their generation is related to massive groundwater extraction.

  16. Rangeland Brush Estimation Toolbox (RaBET): An Approach for Evaluating Brush Management Conservation Efforts in Western Grazing Lands

    Science.gov (United States)

    Holifield Collins, C.; Kautz, M. A.; Skirvin, S. M.; Metz, L. J.

    2016-12-01

    There are over 180 million hectares of rangelands and grazed forests in the central and western United States. Due to the loss of perennial grasses and subsequent increased runoff and erosion that can degrade the system, woody cover species cannot be allowed to proliferate unchecked. The USDA-Natural Resources Conservation Service (NRCS) has allocated extensive resources to employ brush management (removal) as a conservation practice to control woody species encroachment. The Rangeland-Conservation Effects Assessment Project (CEAP) has been tasked with determining how effective the practice has been, however their land managers lack a cost-effective means to conduct these assessments at the necessary scale. An ArcGIS toolbox for generating large-scale, Landsat-based, spatial maps of woody cover on grazing lands in the western United States was developed through a collaboration with NRCS Rangeland-CEAP. The toolbox contains two main components of operation, image generation and temporal analysis, and utilizes simple interfaces requiring minimum user inputs. The image generation tool utilizes geographically specific algorithms developed from combining moderate-resolution (30-m) Landsat imagery and high-resolution (1-m) National Agricultural Imagery Program (NAIP) aerial photography to produce the woody cover scenes at the Major Land Resource (MLRA) scale. The temporal analysis tool can be used on these scenes to assess treatment effectiveness and monitor woody cover reemergence. RaBET provides rangeland managers an operational, inexpensive decision support tool to aid in the application of brush removal treatments and assessing their effectiveness.

  17. Integration of MODIS land and atmosphere products with a coupled-process model to estimate gross primary productivity and evapotranspiration from 1 km to global scales

    Science.gov (United States)

    Ryu, Youngryel; Baldocchi, Dennis D.; Kobayashi, Hideki; van Ingen, Catharine; Li, Jie; Black, T. Andy; Beringer, Jason; van Gorsel, Eva; Knohl, Alexander; Law, Beverly E.; Roupsard, Olivier

    2011-12-01

    We propose the Breathing Earth System Simulator (BESS), an upscaling approach to quantify global gross primary productivity and evapotranspiration using MODIS with a spatial resolution of 1-5 km and a temporal resolution of 8 days. This effort is novel because it is the first system that harmonizes and utilizes MODIS Atmosphere and Land products on the same projection and spatial resolution over the global land. This enabled us to use the MODIS Atmosphere products to calculate atmospheric radiative transfer for visual and near infrared radiation wave bands. Then we coupled atmospheric and canopy radiative transfer processes, with models that computed leaf photosynthesis, stomatal conductance and transpiration on the sunlit and shaded portions of the vegetation and soil. At the annual time step, the mass and energy fluxes derived from BESS showed strong linear relations with measurements of solar irradiance (r2 = 0.95, relative bias: 8%), gross primary productivity (r2 = 0.86, relative bias: 5%) and evapotranspiration (r2 = 0.86, relative bias: 15%) in data from 33 flux towers that cover seven plant functional types across arctic to tropical climatic zones. A sensitivity analysis revealed that the gross primary productivity and evapotranspiration computed in BESS were most sensitive to leaf area index and solar irradiance, respectively. We quantified the mean global terrestrial estimates of gross primary productivity and evapotranpiration between 2001 and 2003 as 118 ± 26 PgC yr-1 and 500 ± 104 mm yr-1 (equivalent to 63,000 ± 13,100 km3 yr-1), respectively. BESS-derived gross primary productivity and evapotranspiration estimates were consistent with the estimates from independent machine-learning, data-driven products, but the process-oriented structure has the advantage of diagnosing sensitivity of mechanisms. The process-based BESS is able to offer gridded biophysical variables everywhere from local to the total global land scales with an 8-day interval over

  18. Physiological Cost Index and Comfort Walking Speed in Two Level Lower Limb Amputees Having No Vascular Disease

    National Research Council Canada - National Science Library

    Teuta Osmani Vllasolli; Nikola Orovcanec; Beti Zafirova; Blerim Krasniqi; Ardiana Murtezani; Bukurije Rama

    2015-01-01

      Background: The Physiological Cost Index (PCI) was introduced by MacGregor to estimate the energy cost in walking of healthy people, also it has been reported for persons with lower limb amputation, walking with prosthesis. Objective...

  19. Walking for data

    DEFF Research Database (Denmark)

    Bødker, Mads; Browning, David; Meinhardt, Nina Dam

    We suggest that ‘walking’ in ethnographic work sensitizes researchers to a particular means of making sense of place. Following a brief conceptual exposition, we present our research tool iMaCam) that supports capturing and representing activities such as walking....

  20. Walking. Sensing. Participation

    DEFF Research Database (Denmark)

    Bødker, Mads

    2014-01-01

    This paper uses three meditations to contemplate walking, sensing and participation as three ways with which we can extend the notion of ‘experiential computing’ proposed by Yoo (2010). By using the form of meditations, loosely associated concepts that are part introspective and part ‘causative’, i...

  1. Dynamic walking with Dribbel

    NARCIS (Netherlands)

    Dertien, Edwin Christian; Stramigioli, Stefano; Stramigioli, S.

    This paper describes the design and construction of Dribbel, a passivity-based walking robot. Dribbel has been designed and built at the Control Engineering group of the University of Twente. This paper focuses on the practical side: the design approach, construction, electronics, and software

  2. Dynamic walking with Dribbel

    NARCIS (Netherlands)

    Dertien, Edwin

    2006-01-01

    This paper describes the design and construction of Dribbel, a passivity-based walking robot. Dribbel has been designed and built at the Control Engineering group of the University of Twente. This paper focuses on the practical side: the design approach, construction, electronics, and software desig

  3. Walking Advisement: Program Description.

    Science.gov (United States)

    Byram Hills School District, Armonk, NY.

    The Walking Advisement program at Crittenden Middle School in Armonk, New York was started during the 1984-1985 school year. It was based on the work of Alfred Arth, a middle school specialist at the University of Wyoming. Essentially, the program attempts to expand the guidance function of the school by bringing faculty and students together to…

  4. Walking along water

    DEFF Research Database (Denmark)

    Rasmussen, Mattias Borg

    2014-01-01

    Steep slopes, white peaks and deep valleys make up the Andes. As phenomenologists of landscape have told us, different people have different landscapes. By moving across the terrain, walking along, we might get a sense of how this has been carved out by the movement of wind and water, tectonics...

  5. The walking robot project

    Science.gov (United States)

    Williams, P.; Sagraniching, E.; Bennett, M.; Singh, R.

    1991-01-01

    A walking robot was designed, analyzed, and tested as an intelligent, mobile, and a terrain adaptive system. The robot's design was an application of existing technologies. The design of the six legs modified and combines well understood mechanisms and was optimized for performance, flexibility, and simplicity. The body design incorporated two tripods for walking stability and ease of turning. The electrical hardware design used modularity and distributed processing to drive the motors. The software design used feedback to coordinate the system and simple keystrokes to give commands. The walking machine can be easily adapted to hostile environments such as high radiation zones and alien terrain. The primary goal of the leg design was to create a leg capable of supporting a robot's body and electrical hardware while walking or performing desired tasks, namely those required for planetary exploration. The leg designers intent was to study the maximum amount of flexibility and maneuverability achievable by the simplest and lightest leg design. The main constraints for the leg design were leg kinematics, ease of assembly, degrees of freedom, number of motors, overall size, and weight.

  6. Deterministic Walks with Choice

    Energy Technology Data Exchange (ETDEWEB)

    Beeler, Katy E.; Berenhaut, Kenneth S.; Cooper, Joshua N.; Hunter, Meagan N.; Barr, Peter S.

    2014-01-10

    This paper studies deterministic movement over toroidal grids, integrating local information, bounded memory and choice at individual nodes. The research is motivated by recent work on deterministic random walks, and applications in multi-agent systems. Several results regarding passing tokens through toroidal grids are discussed, as well as some open questions.

  7. Walking along water

    DEFF Research Database (Denmark)

    Rasmussen, Mattias Borg

    2014-01-01

    Steep slopes, white peaks and deep valleys make up the Andes. As phenomenologists of landscape have told us, different people have different landscapes. By moving across the terrain, walking along, we might get a sense of how this has been carved out by the movement of wind and water, tectonics...

  8. Air Pollution and Lung Function in Dutch Children: A Comparison of Exposure Estimates and Associations Based on Land Use Regression and Dispersion Exposure Modeling Approaches.

    Science.gov (United States)

    Wang, Meng; Gehring, Ulrike; Hoek, Gerard; Keuken, Menno; Jonkers, Sander; Beelen, Rob; Eeftens, Marloes; Postma, Dirkje S; Brunekreef, Bert

    2015-08-01

    There is limited knowledge about the extent to which estimates of air pollution effects on health are affected by the choice for a specific exposure model. We aimed to evaluate the correlation between long-term air pollution exposure estimates using two commonly used exposure modeling techniques [dispersion and land use regression (LUR) models] and, in addition, to compare the estimates of the association between long-term exposure to air pollution and lung function in children using these exposure modeling techniques. We used data of 1,058 participants of a Dutch birth cohort study with measured forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), and peak expiratory flow (PEF) measurements at 8 years of age. For each child, annual average outdoor air pollution exposure [nitrogen dioxide (NO2), mass concentration of particulate matter with diameters ≤ 2.5 and ≤ 10 μm (PM2.5, PM10), and PM2.5 soot] was estimated for the current addresses of the participants by a dispersion and a LUR model. Associations between exposures to air pollution and lung function parameters were estimated using linear regression analysis with confounder adjustment. Correlations between LUR- and dispersion-modeled pollution concentrations were high for NO2, PM2.5, and PM2.5 soot (R = 0.86-0.90) but low for PM10 (R = 0.57). Associations with lung function were similar for air pollutant exposures estimated using LUR and dispersion modeling, except for associations of PM2.5 with FEV1 and FVC, which were stronger but less precise for exposures based on LUR compared with dispersion model. Predictions from LUR and dispersion models correlated very well for PM2.5, NO2, and PM2.5 soot but not for PM10. Health effect estimates did not depend on the type of model used to estimate exposure in a population of Dutch children.

  9. Walking and Sensing Mobile Lives

    DEFF Research Database (Denmark)

    Bødker, Mads; Meinhardt, Nina Dam

    In this position paper, we discuss how mindful walking with people allow us to explore sensory aspects of mobile lives that are typically absent from research. We present an app that aids researchers collect impressions from a walk.......In this position paper, we discuss how mindful walking with people allow us to explore sensory aspects of mobile lives that are typically absent from research. We present an app that aids researchers collect impressions from a walk....

  10. Snakes and perturbed random walks

    CERN Document Server

    Basak, Gopal

    2011-01-01

    In this paper we study some properties of random walks perturbed at extrema, which are generalizations of the walks considered e.g., in Davis (1999). This process can also be viewed as a version of {\\em excited random walk}, studied recently by many authors. We obtain a few properties related to the range of the process with infinite memory. We also prove the Strong law, Central Limit Theorem, and the criterion for the recurrence of the perturbed walk with finite memory.

  11. k-Walk-Regular Digraphs

    Institute of Scientific and Technical Information of China (English)

    Wen LIU; Jing LIN

    2011-01-01

    In this paper,we define a class of strongly connected digraph,called the k-walk-regular digraph,study some properties of it,provide its some algebraic characterization and point out that the O-walk-regular digraph is the same as the walk-regular digraph discussed BY Liu and Lin in 2010 and the D-walk-regular digraph is identical with the weakly distance-regular digraph defined by Comellas et al in 2004.

  12. Walking and Sensing Mobile Lives

    DEFF Research Database (Denmark)

    Bødker, Mads; Meinhardt, Nina Dam

    In this position paper, we discuss how mindful walking with people allow us to explore sensory aspects of mobile lives that are typically absent from research. We present an app that aids researchers collect impressions from a walk.......In this position paper, we discuss how mindful walking with people allow us to explore sensory aspects of mobile lives that are typically absent from research. We present an app that aids researchers collect impressions from a walk....

  13. Simulation of energy consumption for quadruped walking vehicle

    Science.gov (United States)

    Lei, Jingtao; Gao, Feng; Xu, Guoyan

    2006-11-01

    Simulation of energy consumption for walking vehicle is one of the basic way to preliminarily estimate the energy that will be consumed before constructing the real vehicle, providing basis for the design of vehicle to minish energy consumption. One of the most influential factors of the accuracy dynamic simulation is the appropriate contact model between leg and ground. In this paper, we adopt virtual prototyping technique to develop the dynamic modeling of a quadruped walking vehicle considering contact force between legs and ground during walking, finish simulation of dynamics and obtain dynamics characteristics, investigate the effects of different contact condition and the energy consumption. The purpose is to analyze the relationship between energy consumption and relevant influence factors, and the energy efficiency during walking is discussed with different walking velocity, strokes, duty factors and different contact material. Moreover contact force is obtained from simulations. Commercial ADAMS package is used.

  14. Comparison of Satellite-Derived TOA Shortwave Clear-Sky Fluxes to Estimates from GCM Simulations Constrained by Satellite Observations of Land Surface Characteristics

    Science.gov (United States)

    Anantharaj, Valentine G.; Nair, Udaysankar S.; Lawrence, Peter; Chase, Thomas N.; Christopher, Sundar; Jones, Thomas

    2010-01-01

    Clear-sky, upwelling shortwave flux at the top of the atmosphere (S(sub TOA raised arrow)), simulated using the atmospheric and land model components of the Community Climate System Model 3 (CCSM3), is compared to corresponding observational estimates from the Clouds and Earth's Radiant Energy System (CERES) sensor. Improvements resulting from the use of land surface albedo derived from Moderate Resolution Imaging Spectroradiometer (MODIS) to constrain the simulations are also examined. Compared to CERES observations, CCSM3 overestimates global, annual averaged S(sub TOA raised arrow) over both land and oceans. However, regionally, CCSM3 overestimates S(sub TOA raised arrow) over some land and ocean areas while underestimating it over other sites. CCSM3 underestimates S(sub TOA raised arrow) over the Saharan and Arabian Deserts and substantial differences exist between CERES observations and CCSM3 over agricultural areas. Over selected sites, after using groundbased observations to remove systematic biases that exist in CCSM computation of S(sub TOA raised arrow), it is found that use of MODIS albedo improves the simulation of S(sub TOA raised arrow). Inability of coarse resolution CCSM3 simulation to resolve spatial heterogeneity of snowfall over high altitude sites such as the Tibetan Plateau causes overestimation of S(sub TOA raised arrow) in these areas. Discrepancies also exist in the simulation of S(sub TOA raised arrow) over ocean areas as CCSM3 does not account for the effect of wind speed on ocean surface albedo. This study shows that the radiative energy budget at the TOA is improved through the use of MODIS albedo in Global Climate Models.

  15. Estimating daily surface NO2 concentrations from satellite data - a case study over Hong Kong using land use regression models

    Science.gov (United States)

    Anand, Jasdeep S.; Monks, Paul S.

    2017-07-01

    Land use regression (LUR) models have been used in epidemiology to determine the fine-scale spatial variation in air pollutants such as nitrogen dioxide (NO2) in cities and larger regions. However, they are often limited in their temporal resolution, which may potentially be rectified by employing the synoptic coverage provided by satellite measurements. In this work a mixed-effects LUR model is developed to model daily surface NO2 concentrations over the Hong Kong SAR during the period 2005-2015. In situ measurements from the Hong Kong Air Quality Monitoring Network, along with tropospheric vertical column density (VCD) data from the OMI, GOME-2A, and SCIAMACHY satellite instruments were combined with fine-scale land use parameters to provide the spatiotemporal information necessary to predict daily surface concentrations. Cross-validation with the in situ data shows that the mixed-effects LUR model using OMI data has a high predictive power (adj. R2 = 0. 84), especially when compared with surface concentrations derived using the MACC-II reanalysis model dataset (adj. R2 = 0. 11). Time series analysis shows no statistically significant trend in NO2 concentrations during 2005-2015, despite a reported decline in NOx emissions. This study demonstrates the utility in combining satellite data with LUR models to derive daily maps of ambient surface NO2 for use in exposure studies.

  16. Estimation of Regional Evapotranspiration Using Remotely Sensed Land Surface Temperature. Part 2: Application of Equilibrium Evaporation Model to Estimate Evapotranspiration by Remote Sensing Technique. [Japan

    Science.gov (United States)

    Kotoda, K.; Nakagawa, S.; Kai, K.; Yoshino, M. M.; Takeda, K.; Seki, K.

    1985-01-01

    In a humid region like Japan, it seems that the radiation term in the energy balance equation plays a more important role for evapotranspiration then does the vapor pressure difference between the surface and lower atmospheric boundary layer. A Priestley-Taylor type equation (equilibrium evaporation model) is used to estimate evapotranspiration. Net radiation, soil heat flux, and surface temperature data are obtained. Only temperature data obtained by remotely sensed techniques are used.

  17. Perceived neighbourhood environmental attributes associated with adults׳ recreational walking

    DEFF Research Database (Denmark)

    Sugiyama, Takemi; Cerin, Ester; Owen, Neville

    2014-01-01

    This study examined the strength and shape of associations between perceived environmental attributes and adults' recreational walking, using data collected from 13,745 adult participants in 12 countries. Perceived residential density, land use mix, street connectivity, aesthetics, safety from cr...

  18. The use of LIDAR as a potential data source for the creation of digital elevation models and estimation of wetness in northern peat lands

    Science.gov (United States)

    Hasan, Abdulghani; Pilesjö, Petter; Person, Andreas; Roulet, Nigel

    2010-05-01

    The main objective of this study is to investigate the potential of using high resolution LIDAR data for the creation of accurate digital elevation models covering peat lands. The secondary aim is to get an indication of the possibility to use these digital elevation models for estimations of wetness in peat lands areas. The scale problem, i.e. the spatial resolution of the DEM, will be discussed for both objectives. Our hypothesis is that very accurate digital elevation models can be created, that these, by applying an appropriate algorithm reflect wetness in a good way, and that the estimated wetness values are highly dependant on resolution. In DEMs creation, three different interpolation methods are used with four different search radius and six selected cell resolution. We create new MATLAB code program to have full control on the interpolation process. One of the big challenges is how to deal with the huge number of data points. Processing such with computational complexity On2 was very slow. Adding a spatial index key (morton value) speed up the searching process and makes the search in nlog2n time. The new code was successful to deal with the huge number of data with a reasonable time. An important outcome from this study is the statistical comparison between different DEMs.

  19. Quantum walks on Cayley graphs

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Acevedo, O [Laboratoire de Physique Theorique et Modelisation, Universite de Cergy-Pontoise, 2 Avenue Adolphe Chauvin 95302 Cergy Pontoise Cedex (France); Institut fuer Mathematik und Informatik, Ernst-Moritz-Arndt-Universitaet, Friedrich-Ludwig-Jahn Str.15a, 17487 Greifswald (Germany); Gobron, T [Laboratoire de Physique Theorique et Modelisation, Universite de Cergy-Pontoise, 2 Avenue Adolphe Chauvin 95302 Cergy Pontoise Cedex (France)

    2006-01-20

    We address the problem of the construction of quantum walks on Cayley graphs. Our main motivation is the relationship between quantum algorithms and quantum walks. In particular, we discuss the choice of the dimension of the local Hilbert space and consider various classes of graphs on which the structure of quantum walks may differ. We completely characterize quantum walks on free groups and present partial results on more general cases. Some examples are given including a family of quantum walks on the hypercube involving a Clifford algebra.

  20. [Walking abnormalities in children].

    Science.gov (United States)

    Segawa, Masaya

    2010-11-01

    Walking is a spontaneous movement termed locomotion that is promoted by activation of antigravity muscles by serotonergic (5HT) neurons. Development of antigravity activity follows 3 developmental epochs of the sleep-wake (S-W) cycle and is modulated by particular 5HT neurons in each epoch. Activation of antigravity activities occurs in the first epoch (around the age of 3 to 4 months) as restriction of atonia in rapid eye movement (REM) stage and development of circadian S-W cycle. These activities strengthen in the second epoch, with modulation of day-time sleep and induction of crawling around the age of 8 months and induction of walking by 1 year. Around the age of 1 year 6 months, absence of guarded walking and interlimb cordination is observed along with modulation of day-time sleep to once in the afternoon. Bipedal walking in upright position occurs in the third epoch, with development of a biphasic S-W cycle by the age of 4-5 years. Patients with infantile autism (IA), Rett syndrome (RTT), or Tourette syndrome (TS) show failure in the development of the first, second, or third epoch, respectively. Patients with IA fail to develop interlimb coordination; those with RTT, crawling and walking; and those with TS, walking in upright posture. Basic pathophysiology underlying these condition is failure in restricting atonia in REM stage; this induces dysfunction of the pedunculopontine nucleus and consequently dys- or hypofunction of the dopamine (DA) neurons. DA hypofunction in the developing brain, associated with compensatory upward regulation of the DA receptors causes psychobehavioral disorders in infancy (IA), failure in synaptogenesis in the frontal cortex and functional development of the motor and associate cortexes in late infancy through the basal ganglia (RTT), and failure in functional development of the prefrontal cortex through the basal ganglia (TS). Further, locomotion failure in early childhood causes failure in development of functional

  1. Effects of slash-and-burn land management on soil spectral properties estimated with VIS-NIR-SWIR spectroscopy

    Science.gov (United States)

    Rosero-Vlasova, Olga Alexandra; Vlassova, Lidia; Rosero Tufiño, Pedro; Pérez-Cabello, Fernando; Montorio Llovería, Raquel

    2017-04-01

    Slash-and-burn land management is typical for low-income tropical countries, such as Ecuador. It involves conversion of forest into areas used for agriculture. At first trees are cut and the wood debris is burnt. After initial clearing, biomass burning is performed after each production cycle. Usually, cultivation cycles are followed by the fallow period. In the medium and long term, these practices have negative effect on soil fertility and there is the need for clearing more forest for agricultural use. This is one of the reasons for continuing deforestation with the consequent loss of biodiversity. Changes in physico-chemical properties due to periodic burning are accompanied by changes in soil spectral properties and can be determined using VIS-NIR-SWIR spectroscopy, which can be a cost-effective alternative for traditional methods of soil analysis. The purpose of the study is to assess the viability of VIS-NIR-SWIR spectroscopy for characterization of soils from land areas under slash-and-burn management system. Eighteen samples from soil surface layer were collected from two corn fields in the province of Los Rios, Ecuador, in September 2015. One of the areas has experienced six slash-and-burn cycles, while in the other the samples were collected at the end of the first corn cultivation cycle. Spectral measurements of sieved and air-dried samples were performed in the laboratory of the University of Zaragoza using ASD Fieldspec®4 spectroradiometer (350-2500nm spectral range) and ASD Illuminator Lamp as a light source. Statistically significant differences were observed between soil spectra of the samples from two soil groups. Reflectance of repeatedly burnt soils was 20% higher (mean value for the entire spectrum) for 65% of the samples, being especially important in VIS (>45%) and NIR ( 35%), probably due to the lower organic matter (OM) content. OM models built using Partial least Squares Regression demonstrated high predictive capacity (R2>0.8). Thus, the

  2. Generalized Split-Window Algorithm for Estimate of Land Surface Temperature from Chinese Geostationary FengYun Meteorological Satellite (FY-2C Data

    Directory of Open Access Journals (Sweden)

    Jun Xia

    2008-02-01

    Full Text Available On the basis of the radiative transfer theory, this paper addressed the estimate ofLand Surface Temperature (LST from the Chinese first operational geostationarymeteorological satellite-FengYun-2C (FY-2C data in two thermal infrared channels (IR1,10.3-11.3 μ m and IR2, 11.5-12.5 μ m , using the Generalized Split-Window (GSWalgorithm proposed by Wan and Dozier (1996. The coefficients in the GSW algorithmcorresponding to a series of overlapping ranging of the mean emissivity, the atmosphericWater Vapor Content (WVC, and the LST were derived using a statistical regressionmethod from the numerical values simulated with an accurate atmospheric radiativetransfer model MODTRAN 4 over a wide range of atmospheric and surface conditions.The simulation analysis showed that the LST could be estimated by the GSW algorithmwith the Root Mean Square Error (RMSE less than 1 K for the sub-ranges with theViewing Zenith Angle (VZA less than 30° or for the sub-rangs with VZA less than 60°and the atmospheric WVC less than 3.5 g/cm2 provided that the Land Surface Emissivities(LSEs are known. In order to determine the range for the optimum coefficients of theGSW algorithm, the LSEs could be derived from the data in MODIS channels 31 and 32 provided by MODIS/Terra LST product MOD11B1, or be estimated either according tothe land surface classification or using the method proposed by Jiang et al. (2006; and theWVC could be obtained from MODIS total precipitable water product MOD05, or beretrieved using Li et al.’ method (2003. The sensitivity and error analyses in term of theuncertainty of the LSE and WVC as well as the instrumental noise were performed. Inaddition, in order to compare the different formulations of the split-window algorithms,several recently proposed split-window algorithms were used to estimate the LST with thesame simulated FY-2C data. The result of the intercomparsion showed that most of thealgorithms give

  3. Temporal disaggregation of satellite-derived monthly precipitation estimates and the resulting propagation of error in partitioning of water at the land surface

    Directory of Open Access Journals (Sweden)

    S.A. Margulis

    2001-01-01

    Full Text Available Global estimates of precipitation can now be made using data from a combination of geosynchronous and low earth-orbit satellites. However, revisit patterns of polar-orbiting satellites and the need to sample mixed-clouds scenes from geosynchronous satellites leads to the coarsening of the temporal resolution to the monthly scale. There are prohibitive limitations to the applicability of monthly-scale aggregated precipitation estimates in many hydrological applications. The nonlinear and threshold dependencies of surface hydrological processes on precipitation may cause the hydrological response of the surface to vary considerably based on the intermittent temporal structure of the forcing. Therefore, to make the monthly satellite data useful for hydrological applications (i.e. water balance studies, rainfall-runoff modelling, etc., it is necessary to disaggregate the monthly precipitation estimates into shorter time intervals so that they may be used in surface hydrology models. In this study, two simple statistical disaggregation schemes are developed for use with monthly precipitation estimates provided by satellites. The two techniques are shown to perform relatively well in introducing a reasonable temporal structure into the disaggregated time series. An ensemble of disaggregated realisations was routed through two land surface models of varying complexity so that the error propagation that takes place over the course of the month could be characterised. Results suggest that one of the proposed disaggregation schemes can be used in hydrological applications without introducing significant error. Keywords: precipitation, temporal disaggregation, hydrological modelling, error propagation

  4. Estimation of the effects of land use and groundwater withdrawals on streamflow for the Pomperaug River, Connecticut

    Science.gov (United States)

    Bjerklie, David M.; Starn, J. Jeffrey; Tamayo, Claudia

    2010-01-01

    A precipitation runoff model for the Pomperaug River watershed, Connecticut was developed to address issues of concern including the effect of development on streamflow and groundwater recharge, and the implications of water withdrawals on streamflow. The model was parameterized using a strategy that requires a minimum of calibration and optimization by establishing basic relations between the parameter value and physical characteristics of individual hydrologic response units (HRUs) that comprise the model. The strategy was devised so that the information needed can be obtained from Geographic Information System and other general databases for Connecticut. Simulation of groundwater recharge enabled evaluation of the temporal and spatial mapping of recharge variation across the watershed and the spatial effects of changes in land cover on base flow and surface runoff. The modeling indicated that over the course of a year, groundwater provides between 60 and 70 percent of flow in the Pomperaug River; the remainder is generated by more rapid flow through the shallow subsurface and runoff from impermeable surfaces and saturated ground. Groundwater is recharged primarily during periods of low evapotranspiration in the winter, spring, and fall. The largest amount of recharge occurs in the spring in response to snowmelt. During floods, the Weekeepeemee and Nonnewaug Rivers (tributaries that form the Pomperaug River) respond rapidly with little flood peak attenuation due to flood-plain storage. In the Pomperaug River, flood-plain storage is more important in attenuating floods; abandoned quarry ponds (O&G ponds) adjacent to the river provide substantial flood storage above specific river stages when flow from the river spills over the banks and fills the ponds. Discharge from the ponds also helps to sustain low flows in the Pomperaug River. Similarly, releases from the Bronson-Lockwood reservoir sustain flow in the Nonnewaug River and tend to offset the effect of

  5. PestLCI 2.0: a second generation model for estimating emissions of pesticides from arable land in LCA

    DEFF Research Database (Denmark)

    Dijkman, Teunis Johannes; Birkved, Morten; Hauschild, Michael Zwicky

    2012-01-01

    due to new pesticide fate calculation approaches and the inclusion of macropore flow. Differences between the SWASH and FOCUSPEARL and PestLCI 2.0 emission estimates were generally lower than 2 orders of magnitude, with PestLCI generally calculating lower emissions. This is attributed to the LCA...... data and case study, PestLCI 2.0 is a pesticide emission model in acceptable accordance with both state-of-the-art pesticide risk assessment models. The case study underlines that the common pesticide emission estimation practice in LCI may lead to misestimating the toxicity impacts of pesticide use...

  6. Fractional random walk lattice dynamics

    CERN Document Server

    Michelitsch, Thomas; Riascos, Alejandro Perez; Nowakowski, Andrzeij; Nicolleau, Franck

    2016-01-01

    We analyze time-discrete and continuous `fractional' random walks on undirected regular networks with special focus on cubic periodic lattices in $n=1,2,3,..$ dimensions.The fractional random walk dynamics is governed by a master equation involving {\\it fractional powers of Laplacian matrices $L^{\\frac{\\alpha}{2}}$}where $\\alpha=2$ recovers the normal walk.First we demonstrate thatthe interval $0\\textless{}\\alpha\\leq 2$ is admissible for the fractional random walk. We derive analytical expressions for fractional transition matrix and closely related the average return probabilities. We further obtain thefundamental matrix $Z^{(\\alpha)}$, and the mean relaxation time (Kemeny constant) for the fractional random walk.The representation for the fundamental matrix $Z^{(\\alpha)}$ relates fractional random walks with normal random walks.We show that the fractional transition matrix elements exihibit for large cubic $n$-dimensional lattices a power law decay of an $n$-dimensional infinite spaceRiesz fractional deriva...

  7. Estimating groundwater recharge in Hebei Plain, China under varying land use practices using tritium and bromide tracers

    Science.gov (United States)

    Wang, B.; Jin, M.; Nimmo, J.R.; Yang, L.; Wang, W.

    2008-01-01

    Tritium and bromide were used as applied tracers to determine groundwater recharge in Hebei Plain, North China, to evaluate the impacts of different soil types, land use, irrigation, and crop cultivation practice on recharge. Additional objectives were to evaluate temporal variability of recharge and the effect on results of the particular tracer used. Thirty-nine profiles at representative locations were chosen for investigation. Average recharge rates and recharge coefficient determined by tritium and bromide tracing for different sites were 0.00-1.05 mm/d and 0.0-42.5%, respectively. The results showed relative recharge rates for the following paired influences (items within each pair are listed with the influence producing greater recharge first): flood-irrigated cropland and non-irrigated non-cultivation land, flood irrigation (0.42-0.58 mm/d) and sprinkling irrigation (0.17-0.23 mm/d), no stalk mulch (0.56-0.80 mm/d) and stalk mulch (0.44-0.60 mm/d), vegetable (e.g. Chinese cabbage and garlic, 0.70 mm/d) and wheat-maize (0.38 mm/d), peanut (0.51 mm/d) and peach (0.43 mm/d). The results also showed greater recharge for the first year of tracer travel than for the second. Because total precipitation and irrigation were greater in the first year than in the second, this may reflect temporal variability of recharge. The method may not be applicable where the water table is shallow (less than 3 m). A comparison of the near-ideal tritium tracer with the more common but less ideal bromide showed that bromide moved approximately 23% faster than tritiated water, perhaps because of anion exclusion. ?? 2008 Elsevier B.V.

  8. Estimating groundwater recharge in Hebei Plain, China under varying land use practices using tritium and bromide tracers

    Science.gov (United States)

    Wang, Bingguo; Jin, Menggui; Nimmo, John R.; Yang, Lei; Wang, Wenfeng

    2008-07-01

    SummaryTritium and bromide were used as applied tracers to determine groundwater recharge in Hebei Plain, North China, to evaluate the impacts of different soil types, land use, irrigation, and crop cultivation practice on recharge. Additional objectives were to evaluate temporal variability of recharge and the effect on results of the particular tracer used. Thirty-nine profiles at representative locations were chosen for investigation. Average recharge rates and recharge coefficient determined by tritium and bromide tracing for different sites were 0.00-1.05 mm/d and 0.0-42.5%, respectively. The results showed relative recharge rates for the following paired influences (items within each pair are listed with the influence producing greater recharge first): flood-irrigated cropland and non-irrigated non-cultivation land, flood irrigation (0.42-0.58 mm/d) and sprinkling irrigation (0.17-0.23 mm/d), no stalk mulch (0.56-0.80 mm/d) and stalk mulch (0.44-0.60 mm/d), vegetable (e.g. Chinese cabbage and garlic, 0.70 mm/d) and wheat-maize (0.38 mm/d), peanut (0.51 mm/d) and peach (0.43 mm/d). The results also showed greater recharge for the first year of tracer travel than for the second. Because total precipitation and irrigation were greater in the first year than in the second, this may reflect temporal variability of recharge. The method may not be applicable where the water table is shallow (less than 3 m). A comparison of the near-ideal tritium tracer with the more common but less ideal bromide showed that bromide moved approximately 23% faster than tritiated water, perhaps because of anion exclusion.

  9. Smallest worthwhile effect of land-based and water-based pulmonary rehabilitation for COPD

    Science.gov (United States)

    Elkins, Mark R.; Ferreira, Manuela L.; Spencer, Lissa M.; Herbert, Robert D.

    2015-01-01

    This study aimed to determine the smallest worthwhile effect of land-based and water-based pulmonary rehabilitation on 6-min walk distance among people with chronic obstructive pulmonary disease (COPD). Using a benefit–harm trade-off method, people with COPD who had completed two baseline 6-min walk tests at the commencement of outpatient pulmonary rehabilitation were presented with two scenarios: 8 weeks of land-based and 8 weeks of water-based pulmonary rehabilitation. Participants were guided through an iterative process allowing them to progressively refine their estimates of the smallest improvement due to each form of rehabilitation that would outweigh the associated costs, risks and inconvenience presented in the scenario. 100 people with COPD participated (mean±sd age 72±9 years, forced expiratory volume in 1 s 54±16% predicted and baseline 6-min walk distance 377±101 m). For land-based pulmonary rehabilitation, the median smallest worthwhile effect was 20 m (95% CI 15–37 m). For water-based pulmonary rehabilitation, the median smallest worthwhile effect was 26 m (95% CI 15–33 m). These estimates did not differ significantly (p=0.10). People with COPD typically perceive that pulmonary rehabilitation would be worthwhile if it increased the 6-min walk distance by about 6%. The smallest worthwhile effects of land- and water-based pulmonary rehabilitation were similar. PMID:27730130

  10. Smallest worthwhile effect of land-based and water-based pulmonary rehabilitation for COPD

    Directory of Open Access Journals (Sweden)

    Renae J. McNamara

    2015-06-01

    Full Text Available This study aimed to determine the smallest worthwhile effect of land-based and water-based pulmonary rehabilitation on 6-min walk distance among people with chronic obstructive pulmonary disease (COPD. Using a benefit–harm trade-off method, people with COPD who had completed two baseline 6-min walk tests at the commencement of outpatient pulmonary rehabilitation were presented with two scenarios: 8 weeks of land-based and 8 weeks of water-based pulmonary rehabilitation. Participants were guided through an iterative process allowing them to progressively refine their estimates of the smallest improvement due to each form of rehabilitation that would outweigh the associated costs, risks and inconvenience presented in the scenario. 100 people with COPD participated (mean±sd age 72±9 years, forced expiratory volume in 1 s 54±16% predicted and baseline 6-min walk distance 377±101 m. For land-based pulmonary rehabilitation, the median smallest worthwhile effect was 20 m (95% CI 15–37 m. For water-based pulmonary rehabilitation, the median smallest worthwhile effect was 26 m (95% CI 15–33 m. These estimates did not differ significantly (p=0.10. People with COPD typically perceive that pulmonary rehabilitation would be worthwhile if it increased the 6-min walk distance by about 6%. The smallest worthwhile effects of land- and water-based pulmonary rehabilitation were similar.

  11. Covering walks in graphs

    CERN Document Server

    Fujie, Futaba

    2014-01-01

    Covering Walks  in Graphs is aimed at researchers and graduate students in the graph theory community and provides a comprehensive treatment on measures of two well studied graphical properties, namely Hamiltonicity and traversability in graphs. This text looks into the famous Kӧnigsberg Bridge Problem, the Chinese Postman Problem, the Icosian Game and the Traveling Salesman Problem as well as well-known mathematicians who were involved in these problems. The concepts of different spanning walks with examples and present classical results on Hamiltonian numbers and upper Hamiltonian numbers of graphs are described; in some cases, the authors provide proofs of these results to illustrate the beauty and complexity of this area of research. Two new concepts of traceable numbers of graphs and traceable numbers of vertices of a graph which were inspired by and closely related to Hamiltonian numbers are introduced. Results are illustrated on these two concepts and the relationship between traceable concepts and...

  12. Nordic Walking Classes

    CERN Multimedia

    Fitness Club

    2015-01-01

    Four classes of one hour each are held on Tuesdays. RDV barracks parking at Entrance A, 10 minutes before class time. Spring Course 2015: 05.05/12.05/19.05/26.05 Prices 40 CHF per session + 10 CHF club membership 5 CHF/hour pole rental Check out our schedule and enroll at: https://espace.cern.ch/club-fitness/Lists/Nordic%20Walking/NewForm.aspx? Hope to see you among us! fitness.club@cern.ch

  13. Estimation of daily PM10 concentrations in Italy (2006-2012) using finely resolved satellite data, land use variables and meteorology.

    Science.gov (United States)

    Stafoggia, Massimo; Schwartz, Joel; Badaloni, Chiara; Bellander, Tom; Alessandrini, Ester; Cattani, Giorgio; De' Donato, Francesca; Gaeta, Alessandra; Leone, Gianluca; Lyapustin, Alexei; Sorek-Hamer, Meytar; de Hoogh, Kees; Di, Qian; Forastiere, Francesco; Kloog, Itai

    2017-02-01

    Health effects of air pollution, especially particulate matter (PM), have been widely investigated. However, most of the studies rely on few monitors located in urban areas for short-term assessments, or land use/dispersion modelling for long-term evaluations, again mostly in cities. Recently, the availability of finely resolved satellite data provides an opportunity to estimate daily concentrations of air pollutants over wide spatio-temporal domains. Italy lacks a robust and validated high resolution spatio-temporally resolved model of particulate matter. The complex topography and the air mixture from both natural and anthropogenic sources are great challenges difficult to be addressed. We combined finely resolved data on Aerosol Optical Depth (AOD) from the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm, ground-level PM10 measurements, land-use variables and meteorological parameters into a four-stage mixed model framework to derive estimates of daily PM10 concentrations at 1-km2 grid over Italy, for the years 2006-2012. We checked performance of our models by applying 10-fold cross-validation (CV) for each year. Our models displayed good fitting, with mean CV-R2=0.65 and little bias (average slope of predicted VS observed PM10=0.99). Out-of-sample predictions were more accurate in Northern Italy (Po valley) and large conurbations (e.g. Rome), for background monitoring stations, and in the winter season. Resulting concentration maps showed highest average PM10 levels in specific areas (Po river valley, main industrial and metropolitan areas) with decreasing trends over time. Our daily predictions of PM10 concentrations across the whole Italy will allow, for the first time, estimation of long-term and short-term effects of air pollution nationwide, even in areas lacking monitoring data.

  14. Walking with springs

    Science.gov (United States)

    Sugar, Thomas G.; Hollander, Kevin W.; Hitt, Joseph K.

    2011-04-01

    Developing bionic ankles poses great challenges due to the large moment, power, and energy that are required at the ankle. Researchers have added springs in series with a motor to reduce the peak power and energy requirements of a robotic ankle. We developed a "robotic tendon" that reduces the peak power by altering the required motor speed. By changing the required speed, the spring acts as a "load variable transmission." If a simple motor/gearbox solution is used, one walking step would require 38.8J and a peak motor power of 257 W. Using an optimized robotic tendon, the energy required is 21.2 J and the peak motor power is reduced to 96.6 W. We show that adding a passive spring in parallel with the robotic tendon reduces peak loads but the power and energy increase. Adding a passive spring in series with the robotic tendon reduces the energy requirements. We have built a prosthetic ankle SPARKy, Spring Ankle with Regenerative Kinetics, that allows a user to walk forwards, backwards, ascend and descend stairs, walk up and down slopes as well as jog.

  15. An invariance principle for random walk bridges conditioned to stay positive

    CERN Document Server

    Caravenna, Francesco

    2012-01-01

    We prove an invariance principle for the bridge of a random walk conditioned to stay positive, when the random walk is in the domain of attraction of a stable law, both in the discrete and in the absolutely continuous setting. This includes as a special case the convergence under diffusive rescaling of random walk excursions toward the normalized Brownian excursion, for zero mean, finite variance random walks. The proof exploits a suitable absolute continuity relation together with some local asymptotic estimates for random walks conditioned to stay positive, recently obtained by Vatutin and Wachtel [38] and Doney [21]. We review and extend these relations to the absolutely continuous setting.

  16. Biomechanically Excited SMD Model of a Walking Pedestrian

    DEFF Research Database (Denmark)

    Zhang, Mengshi; Georgakis, Christos T.; Chen, Jun

    2016-01-01

    estimated from a known walking frequency and the pedestrian's weight, assuming that pedestrians always walk in displacement resonance and retain a constant damping ratio of 0.3. Thus, biomechanical forces were extracted using the measured SMD dynamic responses and the estimated SMD parameters. Extracted...... of biomechanical forces, was used to model a pedestrian for application in vertical human-structure interaction (HSI). Tests were undertaken in a gait laboratory, where a three-dimensional motion-capture system was used to record a pedestrian's walking motions at various frequencies. The motion-capture system...... produced the pedestrian's center of mass (COM) trajectories from the captured motion markers. The vertical COM trajectory was approximated to be the pedestrian SMD dynamic responses under the excitation of biomechanical forces. SMD model parameters of a pedestrian for a specific walking frequency were...

  17. Do Inequalities in Neighborhood Walkability Drive Disparities in Older Adults’ Outdoor Walking?

    Directory of Open Access Journals (Sweden)

    Razieh Zandieh

    2017-07-01

    Full Text Available Older residents of high-deprivation areas walk less than those of low-deprivation areas. Previous research has shown that neighborhood built environment may support and encourage outdoor walking. The extent to which the built environment supports and encourages walking is called “walkability”. This study examines inequalities in neighborhood walkability in high- versus low-deprivation areas and their possible influences on disparities in older adults’ outdoor walking levels. For this purpose, it focuses on specific neighborhood built environment attributes (residential density, land-use mix and intensity, street connectivity, and retail density relevant to neighborhood walkability. It applied a mixed-method approach, included 173 participants (≥65 years, and used a Geographic Information System (GIS and walking interviews (with a sub-sample to objectively and subjectively measure neighborhood built environment attributes. Outdoor walking levels were measured by using the Geographic Positioning System (GPS technology. Data on personal characteristics was collected by completing a questionnaire. The results show that inequalities in certain land-use intensity (i.e., green spaces, recreation centers, schools and industries in high- versus low-deprivation areas may influence disparities in older adults’ outdoor walking levels. Modifying neighborhood land use intensity may help to encourage outdoor walking in high-deprivation areas.

  18. Autonomous exoskeleton reduces metabolic cost of walking.

    Science.gov (United States)

    Mooney, Luke M; Rouse, Elliott J; Herr, Hugh M

    2014-01-01

    We developed an autonomous powered leg exoskeleton capable of providing large amounts of positive mechanical power to the wearer during powered plantarflexion phase of walking. The autonomous exoskeleton consisted of a winch actuator fasted to the shin which pulled on fiberglass struts attached to a boot. The fiberglass struts formed a rigid extension of the foot when the proximal end of the strut was pulled in forward by the winch actuator. This lightweight, geometric transmission allowed the electric winch actuator to efficiently produce biological levels of power at the ankle joint. The exoskeleton was powered and controlled by lithium polymer batteries and motor controller worn around the waist. Preliminary testing on two subjects walking at 1.4 m/s resulted in the exoskeleton reducing the metabolic cost of walking by 6-11% as compared to not wearing the device. The exoskeleton provided a peak mechanical power of over 180 W at each ankle (mean standard ± deviation) and an average positive mechanical power of 27 ± 1 W total to both ankles, while electrically using 75-89 W of electricity. The batteries (800 g) used in this experiment are estimated to be capable of providing this level of assistance for up to 7 km of walking.

  19. Estimation of water requirement per unit carbon fixed by Eucalyptus camaldulensis in semi-arid land of Western Australia

    Institute of Scientific and Technical Information of China (English)

    T. Kojima; Y. Tanaka; S. Katoh; K. Tahara; N. Takahashi; K, Yamada

    2002-01-01

    Afforestation in arid land is a promising method for carbon fixation, but the effective utili-zation of water is highly important and required. Thus, the evaluation of the amount of water perunit carbon fixed with the tree growth is required to minimize the amount of water supplied to theplants. In this research, a tree is regarded as a carbon fixation reactor with inflows of water andnutrients from roots, and CO2 as the carbon source from leaves with outflow of water vapor fromleaves and accumulation in the tree itself. In the process of photosynthesis and respiration nutri-tional elements are dissolved in water flow in trees. They do not flow out by these reactions, butare accumulated in trees. Thus, we have treated the behaviour of nutrients as a marker to evaluatethe water/carbon ratio. Assuming that nutrient concentration is constant in sap, and the differences in the ratios ofnutrient to carbon in living trees and dead (i.e. litter fall, etc.) are negiected, the ratio of the usedwater to fixed carbon is given as the ratio of nutrient to carbon in the tree body divided by the ratioof nutrient to water in sap. However, some nutrients are translocated and concentrated within thetree and some may be discarded through litter fall. Thus it is important to examine which nutrientelement is the most suitable as the tracer. In this paper, the results of the above method applied to Eucalyptus camaldulensis in semi-arid land of Western Australia are shown. The value of water requirement per unit carbon fixationdetermined from potassium balance is between 421 kg-H2O/kg-C for mature trees and 285kg-H2O/k9-C for young trees, while the values from calcium balance are much larger than these.The cause of the discrepancy between these values is discussed based on the measured elementconcentrations in sap and trees and the plant physiology. Finally, the actual average value throughthe life of a tree is suggested to fall between the two values.

  20. Estimating Temperature Fields from MODIS Land Surface Temperature and Air Temperature Observations in a Sub-Arctic Alpine Environment

    Directory of Open Access Journals (Sweden)

    Scott N. Williamson

    2014-01-01

    Full Text Available Spatially continuous satellite infrared temperature measurements are essential for understanding the consequences and drivers of change, at local and regional scales, especially in northern and alpine environments dominated by a complex cryosphere where in situ observations are scarce. We describe two methods for producing daily temperature fields using MODIS “clear-sky” day-time Land Surface Temperatures (LST. The Interpolated Curve Mean Daily Surface Temperature (ICM method, interpolates single daytime Terra LST values to daily means using the coincident diurnal air temperature curves. The second method calculates daily mean LST from daily maximum and minimum LST (MMM values from MODIS Aqua and Terra. These ICM and MMM models were compared to daily mean air temperatures recorded between April and October at seven locations in southwest Yukon, Canada, covering characteristic alpine land cover types (tundra, barren, glacier at elevations between 1,408 m and 2,319 m. Both methods for producing mean daily surface temperatures have advantages and disadvantages. ICM signals are strongly correlated with air temperature (R2 = 0.72 to 0.86, but have relatively large variability (RMSE = 4.09 to 4.90 K, while MMM values had a stronger correlation to air temperature (R2 = 0.90 and smaller variability (RMSE = 2.67 K. Finally, when comparing 8-day LST averages, aggregated from the MMM method, to air temperature, we found a high correlation (R2 = 0.84 with less variability (RMSE = 1.54 K. Where the trend was less steep and the y-intercept increased by 1.6 °C compared to the daily correlations. This effect is likely a consequence of LST temperature averages being differentially affected by cloud cover over warm and cold surfaces. We conclude that satellite infrared skin temperature (e.g., MODIS LST, which is often aggregated into multi-day composites to mitigate data reductions caused by cloud cover, changes in its relationship to air temperature

  1. Improving Soil Moisture and Temperature Profile and Surface Turbulent Fluxes Estimations in Irrigated Field by Assimilating Multi-source Data into Land Surface Model

    Science.gov (United States)

    Chen, Weijing; Huang, Chunlin; Shen, Huanfeng; Wang, Weizhen

    2016-04-01

    The optimal estimation of hydrothermal conditions in irrigation field is restricted by the deficiency of accurate irrigation information (when and how much to irrigate). However, the accurate estimation of soil moisture and temperature profile and surface turbulent fluxes are crucial to agriculture and water management in irrigated field. In the framework of land surface model, soil temperature is a function of soil moisture - subsurface moisture influences the heat conductivity at the interface of layers and the heat storage in different layers. In addition, soil temperature determines the phase of soil water content with the transformation between frozen and unfrozen. Furthermore, surface temperature affects the partitioning of incoming radiant energy into ground (sensible and latent heat flux), as a consequence changes the delivery of soil moisture and temperature. Given the internal positive interaction lying in these variables, we attempt to retrieve the accurate estimation of soil moisture and temperature profile via assimilating the observations from the surface under unknown irrigation. To resolve the input uncertainty of imprecise irrigation quantity, original EnKS is implemented with inflation and localization (referred to as ESIL) aiming at solving the underestimation of the background error matrix and the extension of observation information from the top soil to the bottom. EnKS applied in this study includes the states in different time points which tightly connect with adjacent ones. However, this kind of relationship gradually vanishes along with the increase of time interval. Thus, the localization is also employed to readjust temporal scale impact between states and filter out redundant or invalid correlation. Considering the parameter uncertainty which easily causes the systematic deviation of model states, two parallel filters are designed to recursively estimate both states and parameters. The study area consists of irrigated farmland and is

  2. Dielectric properties estimation of the lunar regolith at CE-3 landing site using lunar penetrating radar data

    Science.gov (United States)

    Feng, Jianqing; Su, Yan; Ding, Chunyu; Xing, Shuguo; Dai, Shun; Zou, Yongliao

    2017-03-01

    The second channel (CH2) of the Lunar Penetrating Radar (LPR) carried on the Chang'e-3 (CE-3) Yutu Rover was used to determine the thickness and structure of the lunar regolith. Accurately revealing the true structure beneath the surface requires knowledge of the dielectric permittivity of the regolith, which allows one to properly apply migration to the radar image. In contrast to simple assumptions in previous studies, this paper takes account of heterogeneity of the regolith and derives regolith's permittivity distribution laterally and vertically by a method widely used in data processing of terrestrial Ground Penetrating Radar (GPR). We find that regolith permittivity at the landing site increases with depth more quickly than previously recognized. At a depth of ∼2.5-3 m, the dielectric constant reaches the value of solid basalt. The radar image was migrated on the basis of the permittivity profile. We do not find any continuous distinct layers or an apparent regolith/rock interface in the migrated radargram, which implies that this area is covered by relatively young, poorly layered deposits.

  3. Estimating the relationship between urban 3D morphology and land surface temperature using airborne LiDAR and Landsat-8 Thermal Infrared Sensor data

    Science.gov (United States)

    Lee, J. H.

    2015-12-01

    Urban forests are known for mitigating the urban heat island effect and heat-related health issues by reducing air and surface temperature. Beyond the amount of the canopy area, however, little is known what kind of spatial patterns and structures of urban forests best contributes to reducing temperatures and mitigating the urban heat effects. Previous studies attempted to find the relationship between the land surface temperature and various indicators of vegetation abundance using remote sensed data but the majority of those studies relied on two dimensional area based metrics, such as tree canopy cover, impervious surface area, and Normalized Differential Vegetation Index, etc. This study investigates the relationship between the three-dimensional spatial structure of urban forests and urban surface temperature focusing on vertical variance. We use a Landsat-8 Thermal Infrared Sensor image (acquired on July 24, 2014) to estimate the land surface temperature of the City of Sacramento, CA. We extract the height and volume of urban features (both vegetation and non-vegetation) using airborne LiDAR (Light Detection and Ranging) and high spatial resolution aerial imagery. Using regression analysis, we apply empirical approach to find the relationship between the land surface temperature and different sets of variables, which describe spatial patterns and structures of various urban features including trees. Our analysis demonstrates that incorporating vertical variance parameters improve the accuracy of the model. The results of the study suggest urban tree planting is an effective and viable solution to mitigate urban heat by increasing the variance of urban surface as well as evaporative cooling effect.

  4. Estimating Urban Heat Island Effects on the Temperature Series of Uccle (Brussels, Belgium Using Remote Sensing Data and a Land Surface Scheme

    Directory of Open Access Journals (Sweden)

    Rafiq Hamdi

    2010-12-01

    Full Text Available In this letter, the urban heat island effects on the temperature time series of Uccle (Brussels, Belgium during the summers months 1960–1999 was estimated using both ground-based weather stations and remote sensing imagery, combined with a numerical land surface scheme including state-of-the-art urban parameterization, the Town Energy Balance Scheme. Analysis of urban warming based on remote sensing method reveals that the urban bias on minimum temperature is rising at a higher rate, 2.5 times (2.85 ground-based observed more, than on maximum temperature, with a linear trend of 0.15 °C (0.19 °C ground-based observed and 0.06 °C (0.06 °C ground-based observed per decade respectively. The results based on remote sensing imagery are compatible with estimates of urban warming based on weather stations. Therefore, the technique presented in this work is a useful tool in estimating the urban heat island contamination in long time series, countering the drawbacks of a ground-observational approach.

  5. Estimating carbon flux phenology with satellite-derived land surface phenology and climate drivers for different biomes: a synthesis of AmeriFlux observations.

    Directory of Open Access Journals (Sweden)

    Wenquan Zhu

    Full Text Available Carbon Flux Phenology (CFP can affect the interannual variation in Net Ecosystem Exchange (NEE of carbon between terrestrial ecosystems and the atmosphere. In this study, we proposed a methodology to estimate CFP metrics with satellite-derived Land Surface Phenology (LSP metrics and climate drivers for 4 biomes (i.e., deciduous broadleaf forest, evergreen needleleaf forest, grasslands and croplands, using 159 site-years of NEE and climate data from 32 AmeriFlux sites and MODIS vegetation index time-series data. LSP metrics combined with optimal climate drivers can explain the variability in Start of Carbon Uptake (SCU by more than 70% and End of Carbon Uptake (ECU by more than 60%. The Root Mean Square Error (RMSE of the estimations was within 8.5 days for both SCU and ECU. The estimation performance for this methodology was primarily dependent on the optimal combination of the LSP retrieval methods, the explanatory climate drivers, the biome types, and the specific CFP metric. This methodology has a potential for allowing extrapolation of CFP metrics for biomes with a distinct and detectable seasonal cycle over large areas, based on synoptic multi-temporal optical satellite data and climate data.

  6. Estimating carbon flux phenology with satellite-derived land surface phenology and climate drivers for different biomes: a synthesis of AmeriFlux observations.

    Science.gov (United States)

    Zhu, Wenquan; Chen, Guangsheng; Jiang, Nan; Liu, Jianhong; Mou, Minjie

    2013-01-01

    Carbon Flux Phenology (CFP) can affect the interannual variation in Net Ecosystem Exchange (NEE) of carbon between terrestrial ecosystems and the atmosphere. In this study, we proposed a methodology to estimate CFP metrics with satellite-derived Land Surface Phenology (LSP) metrics and climate drivers for 4 biomes (i.e., deciduous broadleaf forest, evergreen needleleaf forest, grasslands and croplands), using 159 site-years of NEE and climate data from 32 AmeriFlux sites and MODIS vegetation index time-series data. LSP metrics combined with optimal climate drivers can explain the variability in Start of Carbon Uptake (SCU) by more than 70% and End of Carbon Uptake (ECU) by more than 60%. The Root Mean Square Error (RMSE) of the estimations was within 8.5 days for both SCU and ECU. The estimation performance for this methodology was primarily dependent on the optimal combination of the LSP retrieval methods, the explanatory climate drivers, the biome types, and the specific CFP metric. This methodology has a potential for allowing extrapolation of CFP metrics for biomes with a distinct and detectable seasonal cycle over large areas, based on synoptic multi-temporal optical satellite data and climate data.

  7. Attentional costs of visually guided walking: effects of age, executive function and stepping-task demands.

    Science.gov (United States)

    Mazaheri, Masood; Roerdink, Melvyn; Bood, Robert Jan; Duysens, Jacques; Beek, Peter J; Peper, C Lieke E

    2014-01-01

    During walking, attention needs to be flexibly allocated to deal with varying environmental constraints. This ability may be affected by aging and lower overall executive function. The present study examined the influence of aging and executive function on the attentional costs of visually guided walking under different task demands. Three groups, young adults (n=15) and elderly adults with higher (n=16) and lower (n=10) executive function, walked on a treadmill in three conditions: uncued walking and walking with regular and irregular patterns of visual stepping targets projected onto the belt. Attentional costs were assessed using a secondary probe reaction time task and corrected by subtracting baseline single-task reaction time, yielding an estimate of the additional attentional costs of each walking condition. We found that uncued walking was more attentionally demanding for elderly than for young participants. In young participants, the attentional costs increased significantly from uncued to regularly cued to irregularly cued walking, whereas for the higher executive function group, attentional costs only increased significantly from regularly cued to irregularly cued walking. For the group with lower executive function, no significant differences were observed. The observed decreased flexibility of elderly, especially those with lower executive function, to allocate additional attentional resources to more challenging walking conditions may be attributed to the already increased attentional costs of uncued walking, presumably required for visuomotor and/or balance control of walking.

  8. Estimating annual generation rates of total P and total N for different land uses in Tasmania, Australia.

    Science.gov (United States)

    Broad, S T; Corkrey, R

    2011-06-01

    Water quality issues have become increasingly important to Australian catchment stakeholders. As extensive nutrient sampling and modelling expertise are often absent or unattainable, simple unit-area models like Catchment Management Support System (CMSS) remain an attractive option for informing water quality management decisions. The selection of nutrient generation rates for use in CMSS is often an arbitrary assignment based on limited literature sources or expert opinion. Using a Bayesian model to estimate nutrient generation rates for the region of Tasmania, Australia, improved the rigor of CMSS modelling and in the process highlighted that dairy pastures were the most significant contributor of total phosphorus and total nitrogen loads to Tasmanian rivers.

  9. Real-Time Global Flood Estimation Using Satellite-Based Precipitation and a Coupled Land Surface and Routing Model

    Science.gov (United States)

    Wu, Huan; Adler, Robert F.; Tian, Yudong; Huffman, George J.; Li, Hongyi; Wang, JianJian

    2014-01-01

    A widely used land surface model, the Variable Infiltration Capacity (VIC) model, is coupled with a newly developed hierarchical dominant river tracing-based runoff-routing model to form the Dominant river tracing-Routing Integrated with VIC Environment (DRIVE) model, which serves as the new core of the real-time Global Flood Monitoring System (GFMS). The GFMS uses real-time satellite-based precipitation to derive flood monitoring parameters for the latitude band 50 deg. N - 50 deg. S at relatively high spatial (approximately 12 km) and temporal (3 hourly) resolution. Examples of model results for recent flood events are computed using the real-time GFMS (http://flood.umd.edu). To evaluate the accuracy of the new GFMS, the DRIVE model is run retrospectively for 15 years using both research-quality and real-time satellite precipitation products. Evaluation results are slightly better for the research-quality input and significantly better for longer duration events (3 day events versus 1 day events). Basins with fewer dams tend to provide lower false alarm ratios. For events longer than three days in areas with few dams, the probability of detection is approximately 0.9 and the false alarm ratio is approximately 0.6. In general, these statistical results are better than those of the previous system. Streamflow was evaluated at 1121 river gauges across the quasi-global domain. Validation using real-time precipitation across the tropics (30 deg. S - 30 deg. N) gives positive daily Nash-Sutcliffe Coefficients for 107 out of 375 (28%) stations with a mean of 0.19 and 51% of the same gauges at monthly scale with a mean of 0.33. There were poorer results in higher latitudes, probably due to larger errors in the satellite precipitation input.

  10. Quantum walks on general graphs

    CERN Document Server

    Kendon, V

    2003-01-01

    A scheme for a discrete time quantum walk on a general graph of N vertices with undirected edges is given, and compared with the continuous time quantum walk on a general graph introduced by Farhi and Gutmann [PRA 58 915 (1998)]. Both walks are contrasted with the examples of quantum walks in the literature treating graphs of fixed, small (< log N) degree. This illustrates the way in which extra information about the graph allows more efficient algorithms to be designed. To obtain a quantum speed up over classical for comparable resources it is necessary to code the position space of the quantum walk into a qubit register (or equivalent). The role of the oracle is also discussed and an efficient gate sequence is presented for implementing a discrete quantum walk given one copy of a quantum state encoding the adjacency matrix of the graph.

  11. Quantum walks on Cayley graphs

    CERN Document Server

    Acevedo, O L

    2006-01-01

    We address the problem of the construction of quantum walks on Cayley graphs. Our main motivation is the relationship between quantum algorithms and quantum walks. Thus we consider quantum walks on a general basis and try to classify them as a preliminary step in the construction of new algorithms that could be devised in this way. In particular, we discuss the choice of the dimension of the local Hilbert space, and consider various classes of graphs on which the structure of quantum walks may differ. We characterize completely the quantum walks on free groups and present partial results on more general cases. Examples are given among which a family of quantum walks on the hypercube involving a Clifford Algebra.

  12. Enhancing the Applicability of Satellite Remote Sensing for PM2.5 Estimation Using MODIS Deep Blue AOD and Land Use Regression in California, United States.

    Science.gov (United States)

    Lee, Hyung Joo; Chatfield, Robert B; Strawa, Anthony W

    2016-06-21

    We estimated daily ground-level PM2.5 concentrations combining Collection 6 deep blue (DB) Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) data (10 km resolution) with land use regression in California, United States, for the period 2006-2012. The Collection 6 DB method for AOD provided more reliable data retrievals over California's bright surface areas than previous data sets. Our DB AOD and PM2.5 data suggested that the PM2.5 predictability could be enhanced by temporally varying PM2.5 and AOD relations at least at a seasonal scale. In this study, we used a mixed effects model that allowed daily variations in DB AOD-PM2.5 relations. Because DB AOD might less effectively represent local source emissions compared to regional ones, we added geographic information system (GIS) predictors into the mixed effects model to further explain PM2.5 concentrations influenced by local sources. A cross validation (CV) mixed effects model revealed reasonably high predictive power for PM2.5 concentrations with R(2) = 0.66. The relations between DB AOD and PM2.5 considerably varied by day, and seasonally varying effects of GIS predictors on PM2.5 suggest season-specific source emissions and atmospheric conditions. This study indicates that DB AOD in combination with land use regression can be particularly useful to generate spatially resolved PM2.5 estimates. This may reduce exposure errors for health effect studies in California. We expect that more detailed PM2.5 concentration patterns can help air quality management plan to meet air quality standards more effectively.

  13. Effects of change in growing season on water use efficiency of lowland rice estimated using a coupled land surface and crop growth model

    Science.gov (United States)

    Maruyama, A.; Kuwagata, T.

    2010-12-01

    The effect of changes in the growing season for rice, which are agronomical adaptation to climate change, on water use efficiency (WUE) was estimated using a coupled land surface and crop growth model. The crop growth model consisted of calculations of phenological development (Ps), growth of leaf area index (LAI) and canopy height (h). The land surface model consisted of calculations of energy budget on the surface, radiation transport and stomatal movements using the output of the crop growth model (Ps, LAI, h). An empirical relationship between stomatal conductance and phenological stage was used for this calculation. The relationship between leaf geometry and phenological stage was also used to express the change in radiation transport in the canopy. Variations in evapotranspiration (ET) were estimated using the coupled model for five different transplanting times (from March to July) based on climatic data for the Miyazaki Plain, Japan. The seasonal variation in ET showed a common pattern, where most of the ET just after transplanting consisted of evaporation (E), and the transpiration (T) increased with rice growth until heading. However, the timing of the increase in T varied with the growing seasons due to the difference of LAI growth rate. The ratios of total transpiration to evapotranspiration (T/ET) were 40, 48, 48, 46 and 36% for transplanting on March 1st, April 1st, May 1st, June 1st and July 1st, respectively. Assuming the amount of production by photosynthesis is proportional to transpiration; our results suggest that the WUE would be higher at mid growing season.

  14. Daily snow cover estimation from Advanced Very High Resolution Radiometer Polar Pathfinder data over Northern Hemisphere land surfaces during 1982-2004

    Science.gov (United States)

    Zhao, Hongxu; Fernandes, Richard

    2009-03-01

    The Global Climate Observing System has identified the need for systematic global daily snow cover data sets over land. Current in situ snow cover data sets have limited spatial coverage while satellite-based snow cover records have either limited historical extent or limited temporal and spatial resolution because of cloud cover or specific sensor availability. NOAA Advanced Very High Resolution Radiometer (AVHRR) data offers nearly complete daily global coverage of the Northern Hemisphere, extending back to the early 1980s with successors slated to continue into the next decade. In this paper, we apply a new algorithm, Snowcover, to estimate daily snow cover, including periods of cloudy conditions, from AVHRR Polar Pathfinder (APP) data over Northern Hemisphere land surfaces. This new snow cover product is compared to snow cover estimates derived from long-term in situ snow depth measurements over Canada and the northern Eurasia. The APP snow cover maps showed an 80% agreement rate or better at 95% of the in situ sites. This performance was comparable to the agreement of MODIS 0.05 degree snow cover products over the same sites; although the MODIS product was only retrieved ˜20% of the time corresponding to clear sky conditions in contrast to over 95% of the time with the APP snow product. The almost continuously temporal and spatial coverage for the past 23 years from 1982 to 2004 over Northern Hemisphere makes the new daily snow cover product especially suitable for analysis of large-scale patterns of spring snowmelt in association with variability of circumpolar climate and ecological parameters.

  15. Cookie branching random walks

    CERN Document Server

    Bartsch, Christian; Kochler, Thomas; Müller, Sebastian; Popov, Serguei

    2011-01-01

    We consider a branching random walk on $\\Z$, where the particles behave differently in visited and unvisited sites. Informally, each site on the positive half-line contains initially a cookie. On the first visit of a site its cookie is removed and particles at positions with a cookie reproduce and move differently from particles on sites without cookies. Therefore, the movement and the reproduction of the particles depend on the previous behaviour of the population of particles. We study the question if the process is recurrent or transient, i.e., whether infinitely many particles visit the origin or not.

  16. Collisions of Random Walks

    CERN Document Server

    Barlow, Martin T; Sousi, Perla

    2010-01-01

    A recurrent graph $G$ has the infinite collision property if two independent random walks on $G$, started at the same point, collide infinitely often a.s. We give a simple criterion in terms of Green functions for a graph to have this property, and use it to prove that a critical Galton-Watson tree with finite variance conditioned to survive, the incipient infinite cluster in $\\Z^d$ with $d \\ge 19$ and the uniform spanning tree in $\\Z^2$ all have the infinite collision property. For power-law combs and spherically symmetric trees, we determine precisely the phase boundary for the infinite collision property.

  17. A mathematical nature walk

    CERN Document Server

    Adam, John A

    2009-01-01

    How heavy is that cloud? Why can you see farther in rain than in fog? Why are the droplets on that spider web spaced apart so evenly? If you have ever asked questions like these while outdoors, and wondered how you might figure out the answers, this is a book for you. An entertaining and informative collection of fascinating puzzles from the natural world around us, A Mathematical Nature Walk will delight anyone who loves nature or math or both. John Adam presents ninety-six questions about many common natural phenomena--and a few uncommon ones--and then shows how to answer them using mostly b

  18. Coupled land surface-subsurface hydrogeophysical inverse modeling to estimate soil organic carbon content and explore associated hydrological and thermal dynamics in the Arctic tundra

    Science.gov (United States)

    Phuong Tran, Anh; Dafflon, Baptiste; Hubbard, Susan S.

    2017-09-01

    Quantitative characterization of soil organic carbon (OC) content is essential due to its significant impacts on surface-subsurface hydrological-thermal processes and microbial decomposition of OC, which both in turn are important for predicting carbon-climate feedbacks. While such quantification is particularly important in the vulnerable organic-rich Arctic region, it is challenging to achieve due to the general limitations of conventional core sampling and analysis methods, and to the extremely dynamic nature of hydrological-thermal processes associated with annual freeze-thaw events. In this study, we develop and test an inversion scheme that can flexibly use single or multiple datasets - including soil liquid water content, temperature and electrical resistivity tomography (ERT) data - to estimate the vertical distribution of OC content. Our approach relies on the fact that OC content strongly influences soil hydrological-thermal parameters and, therefore, indirectly controls the spatiotemporal dynamics of soil liquid water content, temperature and their correlated electrical resistivity. We employ the Community Land Model to simulate nonisothermal surface-subsurface hydrological dynamics from the bedrock to the top of canopy, with consideration of land surface processes (e.g., solar radiation balance, evapotranspiration, snow accumulation and melting) and ice-liquid water phase transitions. For inversion, we combine a deterministic and an adaptive Markov chain Monte Carlo (MCMC) optimization algorithm to estimate a posteriori distributions of desired model parameters. For hydrological-thermal-to-geophysical variable transformation, the simulated subsurface temperature, liquid water content and ice content are explicitly linked to soil electrical resistivity via petrophysical and geophysical models. We validate the developed scheme using different numerical experiments and evaluate the influence of measurement errors and benefit of joint inversion on the

  19. Persistence of random walk records

    Science.gov (United States)

    Ben-Naim, E.; Krapivsky, P. L.

    2014-06-01

    We study records generated by Brownian particles in one dimension. Specifically, we investigate an ordinary random walk and define the record as the maximal position of the walk. We compare the record of an individual random walk with the mean record, obtained as an average over infinitely many realizations. We term the walk ‘superior’ if the record is always above average, and conversely, the walk is said to be ‘inferior’ if the record is always below average. We find that the fraction of superior walks, S, decays algebraically with time, S ˜ t-β, in the limit t → ∞, and that the persistence exponent is nontrivial, β = 0.382 258…. The fraction of inferior walks, I, also decays as a power law, I ˜ t-α, but the persistence exponent is smaller, α = 0.241 608…. Both exponents are roots of transcendental equations involving the parabolic cylinder function. To obtain these theoretical results, we analyze the joint density of superior walks with a given record and position, while for inferior walks it suffices to study the density as a function of position.

  20. Quantum Walks on the Hypercube

    CERN Document Server

    Moore, Cristopher; Moore, Cristopher; Russell, Alexander

    2001-01-01

    Recently, it has been shown that one-dimensional quantum walks can mix more quickly than classical random walks, suggesting that quantum Monte Carlo algorithms can outperform their classical counterparts. We study two quantum walks on the n-dimensional hypercube, one in discrete time and one in continuous time. In both cases we show that the quantum walk mixes in (\\pi/4)n steps, faster than the O(n log n) steps required by the classical walk. In the continuous-time case, the probability distribution is {\\em exactly} uniform at this time. More importantly, these walks expose several subtleties in the definition of mixing time for quantum walks. Even though the continuous-time walk has an O(n) instantaneous mixing time at which it is precisely uniform, it never approaches the uniform distribution when the stopping time is chosen randomly as in [AharonovAKV2001]. Our analysis treats interference between terms of different phase more carefully than is necessary for the walk on the cycle; previous general bounds p...

  1. Physical implementation of quantum walks

    CERN Document Server

    Manouchehri, Kia

    2013-01-01

    Given the extensive application of random walks in virtually every science related discipline, we may be at the threshold of yet another problem solving paradigm with the advent of quantum walks. Over the past decade, quantum walks have been explored for their non-intuitive dynamics, which may hold the key to radically new quantum algorithms. This growing interest has been paralleled by a flurry of research into how one can implement quantum walks in laboratories. This book presents numerous proposals as well as actual experiments for such a physical realization, underpinned by a wide range of

  2. Colors of a Second Earth: Estimating the fractional areas of ocean, land, and vegetation of Earth-like exoplanets

    CERN Document Server

    Fujii, Y; Suto, Y; Taruya, A; Fukuda, S; Nakajima, T; Turner, E L

    2009-01-01

    Characterizing the surfaces of rocky exoplanets via the scattered light will be an essential challenge to investigate the existence of life on habitable exoplanets. We present a simple reconstruction method for fractional areas of different surface types from photometric variations, or colors, of a second Earth. We create mock light curves for Earth without clouds using empirical data. Then these light curves are fitted to the isotropic scattering model consisting of 4 surface types: ocean, soil, snow and vegetation. In an idealized situation where the photometric errors are only photon shot noise, we are able to reproduce the fractional areas of those components fairly well. We may be even able to detect a signature of vegetation from the distinct feature of photosynthesis on the Earth, known as the red edge. In our reconstruction method, Rayleigh scattering due to the atmosphere has an important effect, and for terrestrial exoplanets with atmosphere similar to our Earth, it is possible to estimate the prese...

  3. Aerial Photography Estimation of CH4 and N2O Emissions from Adelie Penguins During 1983-2012 in Victoria Land, Antarctic

    Science.gov (United States)

    He, H.; Li, X.; Cheng, X.

    2016-12-01

    Sea animals are the "bio-indicators" of the climate change in the Antarctic. The abundant nutrient components in their excreta such as carbon (C) and nitrogen (N) promote the emissions of greenhouse gases (GHGs) including methane (CH4) and nitrous oxide (N2O). Adélie Penguins are important sea animals, their colonies therefore become the potential "hotspots" of the GHGs emissions. Some field observations have been carried out to study the penguin excreta on CH4 and N2O emissions in the Antarctic peninsula. However, due to the lacking of the penguin population data, the total emissions of GHGs have not been estimated at regional scale. This study aimed to extract penguin information from two period aerial photographs respectively in 1983 and 2012 using object-oriented method in Victoria Land, Antarctic, and then estimate the Adélie penguin populations on Inexpressible Island combined with the shadow analysis. Meanwhile, a GHGs model was developed to estimate CH4 and N2O emissions from Adelie penguins based on the CH4 and N2O fluxes of penguin guanos, the number of penguins, and the fresh weight of penguin guanos and so on. The results indicated that object-oriented method was effective in penguin information extraction from high-resolution images, and there were 17120 and 21183 Adélie penguins respectively in 1983 and 2012, respectively. The main reasons for the increase in penguin populations from 1983 to 2012 might be explained from physical environment and biological environment, such as the rising temperatures and reduced Antarctic toothfishes. And the total CH4 and N2O emissions from penguins on Inexpressible Island during breeding season were 246 kg CH4 and 2.67 kg N2O in 1983, and 304 kg CH4 and 3.31 kg N2O in 2012. Our study aimed to provide important reference value for the estimation of GHG budget in Antarctic.

  4. Performance evaluation of WRF-Noah Land surface model estimated soil moisture for hydrological application: Synergistic evaluation using SMOS retrieved soil moisture

    Science.gov (United States)

    Srivastava, Prashant K.; Han, Dawei; Rico-Ramirez, Miguel A.; O'Neill, Peggy; Islam, Tanvir; Gupta, Manika; Dai, Qiang

    2015-10-01

    This study explores the performance of soil moisture data from the global European Centre for Medium Range Weather Forecasts (ECMWF) ERA interim reanalysis datasets using the Weather Research and Forecasting (WRF) mesoscale numerical weather model coupled with the Noah Land surface model for hydrological applications. For evaluating the performance of WRF for soil moisture estimation, three domains are taken into account. The domain with best performance is used for estimating the soil moisture deficit (SMD). Further, several approaches are presented in this study to evaluate the efficiency of WRF simulated soil moisture for SMD estimation and compared against Soil Moisture and Ocean Salinity (SMOS) downscaled and non-downscaled soil moisture. In this study, the first approach is based on the empirical relationship between WRF soil moisture and the SMD on a continuous time series basis, while the second approach is focused on the vegetation cover impact on SMD retrieval, depicted in terms of growing and non-growing seasons. The linear growing and non-growing seasonal model in combination performs well with the NSE = 0.79, RMSE = 0.011 m; Bias = 0.24 m, in comparison to linear model (NSE = 0.70, RMSE = 0.013 m; Bias = 0.01 m). The performance obtained using WRF soil moisture is comparable to SMOS level 2 product but lower than the downscaled SMOS datasets. The results indicate that methodologies could be useful for modelers working in the field of soil moisture information system and SMD estimation at a catchment scale. The study could be useful for ungauged basins that pose a challenge to hydrological modeling due to unavailability of datasets for proper model calibration and validation.

  5. Random-walk enzymes.

    Science.gov (United States)

    Mak, Chi H; Pham, Phuong; Afif, Samir A; Goodman, Myron F

    2015-09-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C→U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics.

  6. Random-walk enzymes

    Science.gov (United States)

    Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.

    2015-09-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C →U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics.

  7. Random-walk enzymes

    Science.gov (United States)

    Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.

    2015-01-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C → U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics. PMID:26465508

  8. Using built environment characteristics to predict walking for exercise

    Directory of Open Access Journals (Sweden)

    Siscovick David S

    2008-02-01

    Full Text Available Abstract Background Environments conducive to walking may help people avoid sedentary lifestyles and associated diseases. Recent studies developed walkability models combining several built environment characteristics to optimally predict walking. Developing and testing such models with the same data could lead to overestimating one's ability to predict walking in an independent sample of the population. More accurate estimates of model fit can be obtained by splitting a single study population into training and validation sets (holdout approach or through developing and evaluating models in different populations. We used these two approaches to test whether built environment characteristics near the home predict walking for exercise. Study participants lived in western Washington State and were adult members of a health maintenance organization. The physical activity data used in this study were collected by telephone interview and were selected for their relevance to cardiovascular disease. In order to limit confounding by prior health conditions, the sample was restricted to participants in good self-reported health and without a documented history of cardiovascular disease. Results For 1,608 participants meeting the inclusion criteria, the mean age was 64 years, 90 percent were white, 37 percent had a college degree, and 62 percent of participants reported that they walked for exercise. Single built environment characteristics, such as residential density or connectivity, did not significantly predict walking for exercise. Regression models using multiple built environment characteristics to predict walking were not successful at predicting walking for exercise in an independent population sample. In the validation set, none of the logistic models had a C-statistic confidence interval excluding the null value of 0.5, and none of the linear models explained more than one percent of the variance in time spent walking for exercise. We did not

  9. Estimating wetland vegetation abundance from Landsat-8 operational land imager imagery: a comparison between linear spectral mixture analysis and multinomial logit modeling methods

    Science.gov (United States)

    Zhang, Min; Gong, Zhaoning; Zhao, Wenji; Pu, Ruiliang; Liu, Ke

    2016-01-01

    Mapping vegetation abundance by using remote sensing data is an efficient means for detecting changes of an eco-environment. With Landsat-8 operational land imager (OLI) imagery acquired on July 31, 2013, both linear spectral mixture analysis (LSMA) and multinomial logit model (MNLM) methods were applied to estimate and assess the vegetation abundance in the Wild Duck Lake Wetland in Beijing, China. To improve mapping vegetation abundance and increase the number of endmembers in spectral mixture analysis, normalized difference vegetation index was extracted from OLI imagery along with the seven reflective bands of OLI data for estimating the vegetation abundance. Five endmembers were selected, which include terrestrial plants, aquatic plants, bare soil, high albedo, and low albedo. The vegetation abundance mapping results from Landsat OLI data were finally evaluated by utilizing a WorldView-2 multispectral imagery. Similar spatial patterns of vegetation abundance produced by both fully constrained LSMA algorithm and MNLM methods were observed: higher vegetation abundance levels were distributed in agricultural and riparian areas while lower levels in urban/built-up areas. The experimental results also indicate that the MNLM model outperformed the LSMA algorithm with smaller root mean square error (0.0152 versus 0.0252) and higher coefficient of determination (0.7856 versus 0.7214) as the MNLM model could handle the nonlinear reflection phenomenon better than the LSMA with mixed pixels.

  10. Air temperature field distribution estimations over a Chinese mega-city using MODIS land surface temperature data: the case of Shanghai

    Science.gov (United States)

    Ma, Weichun; Zhou, Liguo; Zhang, Hao; Zhang, Yan; Dai, Xiaoyan

    2016-03-01

    The capability of obtaining spatially distributed air temperature data from remote sensing measurements is an improvement for many environmental applications focused on urban heat island, carbon emissions, climate change, etc. This paper is based on the MODIS/Terra and Aqua data utilized to study the effect of the urban atmospheric heat island in Shanghai, China. The correlation between retrieved MODIS land surface temperature (LST) and air temperature measured at local weather stations was initially studied at different temporal and spatial scales. Secondly, the air temperature data with spatial resolutions of 250 m and 1 km were estimated from MODIS LST data and in-situ measured air temperature. The results showed that there is a slightly higher correlation between air temperature and MODIS LST at a 250m resolution in spring and autumn on an annual scale than observed at a 1 km resolution. Although the distribution pattern of the air temperature thermal field varies in different seasons, the urban heat island (UHI) in Shanghai is characterized by a distribution pattern of multiple centers, with the central urban area as the primary center and the built-up regions in each district as the subcenters. This study demonstrates the potential not only for estimating the distribution of the air temperature thermal field from MODIS LST with 250 m resolution in spring and autumn in Shanghai, but also for providing scientific and effective methods for monitoring and studying UHI effect in a Chinese mega-city such as Shanghai.

  11. Integration of Human Walking Gyroscopic Data Using Empirical Mode Decomposition

    Directory of Open Access Journals (Sweden)

    Vincent Bonnet

    2013-12-01

    Full Text Available The present study was aimed at evaluating the Empirical Mode Decomposition (EMD method to estimate the 3D orientation of the lower trunk during walking using the angular velocity signals generated by a wearable inertial measurement unit (IMU and notably flawed by drift. The IMU was mounted on the lower trunk (L4-L5 with its active axes aligned with the relevant anatomical axes. The proposed method performs an offline analysis, but has the advantage of not requiring any parameter tuning. The method was validated in two groups of 15 subjects, one during overground walking, with 180° turns, and the other during treadmill walking, both for steady-state and transient speeds, using stereophotogrammetric data. Comparative analysis of the results showed that the IMU/EMD method is able to successfully detrend the integrated angular velocities and estimate lateral bending, flexion-extension as well as axial rotations of the lower trunk during walking with RMS errors of 1 deg for straight walking and lower than 2.5 deg for walking with turns.

  12. Delayed Random Walks: Modeling Human Posture Control

    Science.gov (United States)

    Ohira, Toru

    1998-03-01

    We consider a phenomenological description of a noisy trajectory which appears on a stabiliogram platform during human postural sway. We hypothesize that this trajectory arises due to a mixture of uncontrollable noise and a corrective delayed feedback to an upright position. Based on this hypothesis, we model the process with a biased random walk whose transition probability depends on its position at a fixed time delay in the past, which we call a delayed random walk. We first introduce a very simple model (T. Ohira and J. G. Milton, Phys.Rev.E. 52), 3277, (1995), which can nevertheless capture the rough qualitative features of the two--point mean square displacement of experimental data with reasonable estimation of delay time. Then, we discuss two approaches toward better capturing and understanding of the experimental data. The first approach is an extension of the model to include a spatial displacement threshold from the upright position below which no or only weak corrective feedback motion takes place. This can be incorporated into an extended delayed random walk model. Numerical simulations show that this extended model can better capture the three scaling region which appears in the two--point mean square displacement. The other approach studied the autocorrelation function of the experimental data, which shows oscillatory behavior. We recently investigated a delayed random walk model whose autocorrelation function has analytically tractable oscillatory behavior (T. Ohira, Phys.Rev.E. 55), R1255, (1997). We discuss how this analytical understanding and its application to delay estimation (T. Ohira and R. Sawatari, Phys.Rev.E. 55), R2077, (1997) could possibly be used to further understand the postural sway data.

  13. Spatially-explicit estimates of greenhouse-gas payback times for perennial cellulosic biomass production on open lands in the Lake States

    Science.gov (United States)

    Sahajpal, R.

    2015-12-01

    The development of renewable energy sources is an integral step towards mitigating the carbon dioxide induced component of climate change. One important renewable source is plant biomass, comprising both food crops such as corn (Zea mays) and cellulosic biomass from short-rotation woody crops (SRWC) such as hybrid-poplar (Populus spp.) and Willow (Salix spp.). Due to their market acceptability and excellent energy balance, cellulosic feedstocks represent an abundant and if managed properly, a carbon-neutral and environmentally beneficial resource. We evaluate how site variability impacts the greenhouse-gas (GHG) benefits of SRWC plantations on lands potentially suited for bioenergy feedstock production in the Lake States (Minnesota, Wisconsin, Michigan). We combine high-resolution, spatially-explicit estimates of biomass, soil organic carbon and nitrous oxide emissions for SRWC plantations from the Environmental Policy Integrated Climate (EPIC) model along with life cycle analysis results from the GREET model to determine the greenhouse-gas payback time (GPBT) or the time needed before the GHG savings due to displacement of fossil fuels exceeds the initial losses from plantation establishment. We calibrate our models using unique yield and N2O emission data from sites across the Lake states that have been converted from pasture and hayfields to SRWC plantations. Our results show a reduction of 800,000 ha in non-agricultural open land availability for biomass production, a loss of nearly 37% (see attached figure). Overall, GPBTs range between 1 and 38 years, with the longest GPBTs occurring in the northern Lake states. Initial soil nitrate levels and site drainage potential explain more than half of the variation in GPBTs. Our results indicate a rapidly closing window of opportunity to establish a sustainable cellulosic feedstock economy in the Lake States.

  14. Estimation of carbon sequestration in reclaimed coalmine degraded land dominated by Albizia lebbeck, Dalbergia sissoo and Bambusa arundinacea plantation: a case study from Jharia Coalfields, India

    Institute of Scientific and Technical Information of China (English)

    Rimi Das; Subodh Kumar Maiti

    2016-01-01

    Reclaimed mined lands provide an excellent opportunity to sequester carbon and combat global warming.Carbon sequestration on reclaimed sites depend on age of reclamation,composition of species,geomining conditions (soil characteristics) and prevailing climate.The aims of the present study were to calculate carbon ?—stock of biomass of 4 years old plantation (dominated by Albizia lebbeck,Dalbergia sissoo and Bambusa arundinacea),understorey vegetation and litter,soil organic carbon in reclaimed minesoil (RMS) and compare with reference forest site.Allometric equation was used for the estimation of biomass C stock and found 13.0 Mg C ha-1 (A lebbeck 7.8 Mg C ha-1,D sissoo 3.5 Mg C ha-1 and B.arundincea 1.2 Mg C ha-1),while stock of understorey vegetation was 0.98 Mg C ha-1.In RMS,C stock was 16.3 Mg C ha-1,out of which inorganic C contributed 1.7 g kg-1 (8 % of total soil C),Coal C 8.7 g kg-1(43 % of total soil C) and biogenic C 9.8 g kg-1 (49 % of total soil C).Total C stock in reclaimed site was calculated as 30.3 Mg C ha-1 (equivalent to 111 Mg CO2 ha-1).The study concluded that (i) coal C is responsible for overestimation of C stock in RMS (ii) Maximun C stock stored in aboveground biomass component and (iii) reclaimed mined lands will take approximately 17 years to reach the level of C stock of reference forest site in dry tropical climate.

  15. Quantum walks and search algorithms

    CERN Document Server

    Portugal, Renato

    2013-01-01

    This book addresses an interesting area of quantum computation called quantum walks, which play an important role in building quantum algorithms, in particular search algorithms. Quantum walks are the quantum analogue of classical random walks. It is known that quantum computers have great power for searching unsorted databases. This power extends to many kinds of searches, particularly to the problem of finding a specific location in a spatial layout, which can be modeled by a graph. The goal is to find a specific node knowing that the particle uses the edges to jump from one node to the next. This book is self-contained with main topics that include: Grover's algorithm, describing its geometrical interpretation and evolution by means of the spectral decomposition of the evolution operater Analytical solutions of quantum walks on important graphs like line, cycles, two-dimensional lattices, and hypercubes using Fourier transforms Quantum walks on generic graphs, describing methods to calculate the limiting d...

  16. Walking around to grasp interaction

    DEFF Research Database (Denmark)

    Lykke, Marianne; Jantzen, Christian

    2013-01-01

    with the sound installations. The aim was to gain an understanding of the role of the in-teraction, if interaction makes a difference for the understanding of the sound art. 30 walking interviews were carried out at ZKM, Karlsruhe with a total of 57 museum guests, individuals or groups. During the walk......The paper presents experiences from a study using walk-alongs to provide insight into museum visitors’ experience with interactive features of sound art installations. The overall goal of the study was to learn about the participants’ opinions and feelings about the possibility of interaction...... knowledge of spa-tial conditions, e.g. noise, crowds, darkness provided a profound and shared un-derstanding of e.g. the visitors’ engagement in and dislike of the installations. Another finding concerns group walking that, compared to walking with a sin-gle person, generated a diversified discussion...

  17. Algebraic Techniques for Enumerating Self-Avoiding Walks on the Square Lattice

    CERN Document Server

    Conway, A R; Guttmann, A J

    1993-01-01

    We describe a new algebraic technique for enumerating self-avoiding walks on the rectangular lattice. The computational complexity of enumerating walks of $N$ steps is of order $3^{N/4}$ times a polynomial in $N$, and so the approach is greatly superior to direct counting techniques. We have enumerated walks of up to 39 steps. As a consequence, we are able to accurately estimate the critical point, critical exponent, and critical amplitude.

  18. Human treadmill walking needs attention

    Directory of Open Access Journals (Sweden)

    Daniel Olivier

    2006-08-01

    Full Text Available Abstract Background The aim of the study was to assess the attentional requirements of steady state treadmill walking in human subjects using a dual task paradigm. The extent of decrement of a secondary (cognitive RT task provides a measure of the attentional resources required to maintain performance of the primary (locomotor task. Varying the level of difficulty of the reaction time (RT task is used to verify the priority of allocation of attentional resources. Methods 11 healthy adult subjects were required to walk while simultaneously performing a RT task. Participants were instructed to bite a pressure transducer placed in the mouth as quickly as possible in response to an unpredictable electrical stimulation applied on the back of the neck. Each subject was tested under five different experimental conditions: simple RT task alone and while walking, recognition RT task alone and while walking, walking alone. A foot switch system composed of a pressure sensitive sensor was placed under the heel and forefoot of each foot to determine the gait cycle duration. Results Gait cycle duration was unchanged (p > 0.05 by the addition of the RT task. Regardless of the level of difficulty of the RT task, the RTs were longer during treadmill walking than in sitting conditions (p 0.05 was found between the attentional demand of the walking task and the decrement of performance found in the RT task under varying levels of difficulty. This finding suggests that the healthy subjects prioritized the control of walking at the expense of cognitive performance. Conclusion We conclude that treadmill walking in young adults is not a purely automatic task. The methodology and outcome measures used in this study provide an assessment of the attentional resources required by walking on the treadmill at a steady state.

  19. Water-walking devices

    Science.gov (United States)

    Hu, David L.; Prakash, Manu; Chan, Brian; Bush, John W. M.

    We report recent efforts in the design and construction of water-walking machines inspired by insects and spiders. The fundamental physical constraints on the size, proportion and dynamics of natural water-walkers are enumerated and used as design criteria for analogous mechanical devices. We report devices capable of rowing along the surface, leaping off the surface and climbing menisci by deforming the free surface. The most critical design constraint is that the devices be lightweight and non-wetting. Microscale manufacturing techniques and new man-made materials such as hydrophobic coatings and thermally actuated wires are implemented. Using highspeed cinematography and flow visualization, we compare the functionality and dynamics of our devices with those of their natural counterparts.

  20. Walking for art's sake

    CERN Multimedia

    2005-01-01

      The man who compared himself to a proton ! On 20 May, Gianni Motti went down into the LHC tunnel and walked around the 27 kilometres of the underground ring at an average, unaccelerated pace of 5 kph. This was an artistic rather than an athletic performance, aimed at drawing a parallel between the fantastic speed of the beams produced by the future accelerator and the leisurely stroll of a human. The artist, who hails from Lombardy, was accompanied by cameraman Ivo Zanetti, who filmed the event from start to finish, and physicist Jean-Pierre Merlo. The first part of the film can be seen at the Villa Bernasconi, 8 route du Grand-Lancy, Grand Lancy, until 26 June.

  1. Walking for art's sake

    CERN Document Server

    2005-01-01

    The man who compared himself to a proton ! On 20 May, Gianni Motti went down into the LHC tunnel and walked around the 27 kilometres of the underground ring at an average, unaccelerated pace of 5 kph. This was an artistic rather than an athletic performance, aimed at drawing a parallel between the fantastic speed of the beams produced by the future accelerator and the leisurely stroll of a human. The artist, who hails from Lombardy, was accompanied by cameraman Ivo Zanetti, who filmed the event from start to finish, and physicist Jean-Pierre Merlo. The first part of the film can be seen at the Villa Bernasconi, 8 route du Grand-Lancy, Grand Lancy, until 26 June.

  2. Walking indoors, walking outdoors: an fMRI study

    Directory of Open Access Journals (Sweden)

    Riccardo eDalla Volta

    2015-10-01

    Full Text Available An observation/execution matching system for walking has not been assessed yet. The present fMRI study was aimed at assessing whether, as for object-directed actions, an observation/execution matching system is active for walking and whether the spatial context of walking (open or narrow space recruits different neural correlates. Two experimental conditions were employed. In the execution condition, while being scanned, participants performed walking on a rolling cylinder located just outside the scanner. The same action was performed also while observing a video presenting either an open space (a country field or a narrow space (a corridor. In the observation condition, participants observed a video presenting an individual walking on the same cylinder on which the actual action was executed, the open space video and the narrow space video, respectively. Results showed common bilateral activations in the dorsal premotor/supplementary motor areas and in the posterior parietal lobe for both execution and observation of walking, thus supporting a matching system for this action. Moreover, specific sectors of the occipital-temporal cortex and the middle temporal gyrus were consistently active when processing a narrow space versus an open one, thus suggesting their involvement in the visuo-motor transformation required when walking in a narrow space. We forward that the present findings may have implications for rehabilitation of gait and sport training.

  3. Optimal speeds for walking and running, and walking on a moving walkway

    Science.gov (United States)

    Srinivasan, Manoj

    2009-06-01

    Many aspects of steady human locomotion are thought to be constrained by a tendency to minimize the expenditure of metabolic cost. This paper has three parts related to the theme of energetic optimality: (1) a brief review of energetic optimality in legged locomotion, (2) an examination of the notion of optimal locomotion speed, and (3) an analysis of walking on moving walkways, such as those found in some airports. First, I describe two possible connotations of the term "optimal locomotion speed:" that which minimizes the total metabolic cost per unit distance and that which minimizes the net cost per unit distance (total minus resting cost). Minimizing the total cost per distance gives the maximum range speed and is a much better predictor of the speeds at which people and horses prefer to walk naturally. Minimizing the net cost per distance is equivalent to minimizing the total daily energy intake given an idealized modern lifestyle that requires one to walk a given distance every day—but it is not a good predictor of animals' walking speeds. Next, I critique the notion that there is no energy-optimal speed for running, making use of some recent experiments and a review of past literature. Finally, I consider the problem of predicting the speeds at which people walk on moving walkways—such as those found in some airports. I present two substantially different theories to make predictions. The first theory, minimizing total energy per distance, predicts that for a range of low walkway speeds, the optimal absolute speed of travel will be greater—but the speed relative to the walkway smaller—than the optimal walking speed on stationary ground. At higher walkway speeds, this theory predicts that the person will stand still. The second theory is based on the assumption that the human optimally reconciles the sensory conflict between the forward speed that the eye sees and the walking speed that the legs feel and tries to equate the best estimate of the

  4. Exercise on land or in water?

    Directory of Open Access Journals (Sweden)

    Boussuges A

    2012-04-01

    Full Text Available Alain Boussuges1, Olivier Gavarry21French Armed Forces Biomedical Research Institute, Brétigny sur Orge and UMR MD2, Aix-Marseilles University, Marseilles, France; 2Engineering Laboratory for Handicaps. South University of Toulon – Var, La Garde, FranceWe have read with interest the study published in the International Journal of General Medicine entitled “Hypotensive response after water-walking and land walking exercise sessions in healthy trained and untrained women” by Rodriguez et al.1 In this study, the authors investigated cardiovascular changes induced by walking in water in comparison with walking on land. Water exercises are commonly used in rehabilitation programs, particularly patients with mobility problems. Recently, some studies have suggested that exercise performed in water could improve cardiovascular function.2View original paper by Bocalini et al.

  5. Inventory-based model estimates of the net impact of natural disturbances on the C balance of Canada’s managed forest lands

    Science.gov (United States)

    Stinson, G.; Kurz, W.; Neilson, E.; Metsaranta, J.

    2009-12-01

    The net impact of natural disturbances on the C budget of Canada’s managed forest lands (230 million ha) has not previously been estimated. Natural disturbances affect forest ecosystem C budgets by directly releasing C to the atmosphere, by transferring large quantities of living biomass to dead organic matter pools which subsequently decompose, and by altering the carbon uptake capacity of the affected ecosystems. We define the net impact as the difference in the forest carbon balance with and without a specific natural disturbance type. We estimated the net impact of fire and insect disturbances on Canada’s managed forest C budget from 1990 through 2007 using the CBM-CFS3, an inventory-based simulation model that uses data from Canada’s National Forest Carbon Monitoring, Accounting and Reporting System (NFCMARS). Four scenarios were simulated: (i) a base scenario that includes all natural disturbances, (ii) base with fire removed, (iii) base with insects removed, and (iv) base with both fire and insects removed. Disturbance impacts were found to be highly variable between years and not normally distributed about their means. Direct fire emissions ranged from 3 to 75 Tg C yr-1 (11 to 291 Mt CO2e yr-1, accounting for CO2, CO, CH4 and N2O) during 1990-2007. Fires that occurred during 1990-2007 reduced NEP during this same period by 1 to 5 Tg C yr-1 and insects reduced NEP by 1 to 17 Tg C yr-1. Fires resulted in a 1 to 12 Tg C yr-1 reduction in NPP while insects reduced NPP by 1 to 13 Tg C yr-1. Insect impacts on heterotrophic respiration (Rh) during 1990-2007 were minor because most of the recorded insect-induced tree mortality occurred towards the end of the period. Interactive effects between natural disturbances and forest management activities (harvest and salvage) were also analyzed. Quantification of natural disturbance impacts on the forest ecosystem C budget is not staight forward on a land base where natural and anthropogenic factors are interacting

  6. About the walking machine motion stability

    Directory of Open Access Journals (Sweden)

    V. V. Lapshin

    2014-01-01

    Full Text Available The use of legs as propulsive devices of the machine will increase its capability to cross rough and deformable terrain as compared with wheeled and trucked machines. Today it is already possible to speak about design of statically stable walking robots to be used in the certain areas of application. The most promising areas of their application are exploration and emergency-rescue operations in extremely complicated situations (e.g. in the zone of destruction after earthquakes, technogenic catastrophe, etc..In such dangerous situations there is a possibility for the walking machine to be overturned either because of loosing a support to one or several legs or due to significant displacement of the leg support points, which are caused by deformation or destruction of the terrain in the points of the legs support. Therefore, it is necessary to design motion control algorithms that enable teaching the motion control system of a walking robot: How to decrease the possibility of the robot overturning? How to stop the robot as quickly as possible keeping its static stability? What must be done if static stability is lost? Note that the loss of static stability does not inevitably result in the robot falling down. How to fall down better (with minimal robot destruction in inevitable case?This work investigates the first abovementioned problems, i.e. preventing a walking machine from overturning in dangerous situations. For this purpose it suggests to use a special cautious (safe gait, which allows the machine to remain statically stable if it suddenly looses support to its any leg. The natural price for the increased safety to prevent from overturning is the reduced capabilities of robot kinematics and, as a consequence, its capability to cross rough terrain. It is also suggested to reconsider the general definition of a walking machine static stability margin in order to obtain an adequate estimation of the robot overturning possibility

  7. Comparison of the performances of land use regression modelling and dispersion modelling in estimating small-scale variations in long-term air pollution concentrations in a Dutch urban area

    NARCIS (Netherlands)

    Beelen, R.; Voogt, M.; Duyzer, J.; Zandveld, P.Y.J.; Hoek, G.

    2010-01-01

    The performance of a Land Use Regression (LUR) model and a dispersion model (URBIS - URBis Information System) was compared in a Dutch urban area. For the Rijnmond area, i.e. Rotterdam and surroundings, nitrogen dioxide (NO2) concentrations for 2001 were estimated for nearly 70 000 centro

  8. Visual control of walking velocity.

    Science.gov (United States)

    François, Matthieu; Morice, Antoine H P; Bootsma, Reinoud J; Montagne, Gilles

    2011-06-01

    Even if optical correlates of self-motion velocity have already been identified, their contribution to the control of displacement velocity remains to be established. In this study, we used a virtual reality set-up coupled to a treadmill to test the role of both Global Optic Flow Rate (GOFR) and Edge Rate (ER) in the regulation of walking velocity. Participants were required to walk at a constant velocity, corresponding to their preferred walking velocity, while eye height and texture density were manipulated. This manipulation perturbed the natural relationship between the actual walking velocity and its optical specification by GOFR and ER, respectively. Results revealed that both these sources of information are indeed used by participants to control walking speed, as demonstrated by a slowing down of actual walking velocity when the optical specification of velocity by either GOFR or ER gives rise to an overestimation of actual velocity, and vice versa. Gait analyses showed that these walking velocity adjustments result from simultaneous adaptations in both step length and step duration. The role of visual information in the control of self-motion velocity is discussed in relation with other factors.

  9. Air temperature field distribution estimations over a Chinese mega-city using MODIS land surface temperature data: the case of Shanghai

    Institute of Scientific and Technical Information of China (English)

    Weichun MA; Liguo ZHOU; Hao ZHANG; Yan ZHANG; Xiaoyan DAI

    2016-01-01

    The capability of obtaining spatially distributed air temperature data from remote sensing measurements is an improvement for many environmental applications focused on urban heat island,carbon emissions,climate change,etc.This paper is based on the MODIS/Terra and Aqua data utilized to study the effect of the urban atmospheric heat island in Shanghai,China.The correlation between retrieved MODIS land surface temperature (LST) and air temperature measured at local weather stations was initially studied at different temporal and spatial scales.Secondly,the air temperature data with spatial resolutions of 250 m and 1 km were estimated from MODIS LST data and in-situ measured air temperature.The results showed that there is a slightly higher correlation between air temperature and MODIS LST at a 250 m resolution in spring and autumn on an annual scale than observed at a 1 km resolution.Although the distribution pattern of the air temperature thermal field varies in different seasons,the urban heat island (UHI) in Shanghai is characterized by a distribution pattern of multiple centers,with the central urban area as the primary center and the built-up regions in each district as the subcenters.This study demonstrates the potential not only for estimating the distribution of the air temperature thermal field from MODIS LST with 250 m resolution in spring and autumn in Shanghai,but also for providing scientific and effective methods for monitoring and studying UHI effect in a Chinese mega-city such as Shanghai.

  10. Estimation of Diurnal Cycle of Land Surface Temperature at High Temporal and Spatial Resolution from Clear-Sky MODIS Data

    Directory of Open Access Journals (Sweden)

    Si-Bo Duan

    2014-04-01

    Full Text Available The diurnal cycle of land surface temperature (LST is an important element of the climate system. Geostationary satellites can provide the diurnal cycle of LST with low spatial resolution and incomplete global coverage, which limits its applications in some studies. In this study, we propose a method to estimate the diurnal cycle of LST at high temporal and spatial resolution from clear-sky MODIS data. This method was evaluated using the MSG-SEVIRI-derived LSTs. The results indicate that this method fits the diurnal cycle of LST well, with root mean square error (RMSE values less than 1 K for most pixels. Because MODIS provides at most four observations per day at a given location, this method was further evaluated using only four MSG-SEVIRI-derived LSTs corresponding to the MODIS overpass times (10:30, 13:30, 22:30, and 01:30 local solar time. The results show that the RMSE values using only four MSG-SEVIRI-derived LSTs are approximately two times larger than those using all LSTs. The spatial distribution of the modeled LSTs at the MODIS pixel scale is presented from 07:00 to 05:00 local solar time of the next day with an increment of 2 hours. The diurnal cycle of the modeled LSTs describes the temporal evolution of the LSTs at the MODIS pixel scale.

  11. THE ESTIMATION OF SOME CHANGES OF SOIL PHYSICAL STATE UNDER THE EFFECT OF LAND RECLAMATION TECHNOLOGIES, IN THE CONDITION OF SUBSURFACE DRAINAGE IN BAIA-MOLDOVA DEPPRESSION

    Directory of Open Access Journals (Sweden)

    V. Moca

    2006-10-01

    Full Text Available In the pedo-climatic conditions of Suceava County that extends on a total surface of 855 300 ha, the balance of agricultural land affected by humidity excess with temporar or permanent character is differenciated from south to north and from east to west, between 30 % till 40%, which means almost 100 000 ha. On these soils with underground water or pluvial excess hydro ameliorative drainage systems have been installed, associated to a complex agroameliorative works. For long effect estimation of the underground drainage asociated with the agropedoameliorative works upon the some physical and hydrophysical characteristics, there were analyzed the soil and the environment conditions from Baia field. For this reason, we analyzed the agrophysical conditions for luvisol albic pseudogleic (SRCS-1980, respectively luvosol albic stagnic-glosic (SRTS-2003 albic luvosoil drained and cultivated, after a period of 28 years (1978-2006 use. The obtained data regarding to te water balance and the evolution of the major physical properties of soil, under the influence of drainage and amelioration works, put into evidence in the first stage (1978-1986 a general improvement of the aerohidrycal state and physical-chemical conditioning. In the next two experimental cycles of 10 years each, have been noticed a increased of compaction degree of soil drained and cultivated on 0-30 cm depth, from weak loose to moderately compaction depending on the remanence of the reclamation technologies.

  12. Energetics and passive dynamics of the ankle in downhill walking.

    Science.gov (United States)

    Holm, Jonathan K; Contakos, Jonas; Lee, Sang-Wook; Jang, John

    2010-11-01

    This study investigated the energetics of the human ankle during the stance phase of downhill walking with the goal of modeling ankle behavior with a passive spring and damper mechanism. Kinematic and kinetic data were collected on eight male participants while walking down a ramp with inclination varying from 0° to 8°. The ankle joint moment in the sagittal plane was calculated using inverse dynamics. Mechanical energy injected or dissipated at the ankle joint was computed by integrating the power across the duration of the stance phase. The net mechanical energy of the ankle was approximately zero for level walking and monotonically decreased (i.e., became increasingly negative) during downhill walking as the slope decreased. The indication is that the behavior of the ankle is energetically passive during downhill walking, playing a key role in dissipating energy from one step to the next. A passive mechanical model consisting of a pin joint coupled with a revolute spring and damper was fit to the ankle torque and its parameters were estimated for each downhill slope using linear regression. The passive model demonstrated good agreement with actual ankle dynamics as indicated by low root-mean-square error values. These results indicate the stance phase behavior of the human ankle during downhill walking may be effectively duplicated by a passive mechanism with appropriately selected spring and damping characteristics.

  13. Neural compensation within the human triceps surae during prolonged walking.

    Science.gov (United States)

    Cronin, Neil J; Peltonen, Jussi; Sinkjaer, Thomas; Avela, Janne

    2011-02-01

    During human walking, muscle activation strategies are approximately constant across consecutive steps over a short time, but it is unknown whether they are maintained over a longer duration. Prolonged walking may increase tendinous tissue (TT) compliance, which can influence neural activation, but the neural responses of individual muscles have not been investigated. This study investigated the hypothesis that muscle activity is up- or down-regulated in individual triceps surae muscles during prolonged walking. Thirteen healthy subjects walked on a treadmill for 60 min at 4.5 km/h, while triceps surae muscle activity, maximal muscle compound action potentials, and kinematics were recorded every 5 min, and fascicle lengths were estimated at the beginning and end of the protocol using ultrasound. After 1 h of walking, soleus activity increased by 9.3 ± 0.2% (P triceps surae muscles and that changes in muscle activation are generally mirrored by changes in muscle fascicle length. These findings also support the notion of muscle-specific changes in TT compliance after prolonged walking and highlight the ability of the CNS to maintain relatively constant movement patterns in spite of neuromechanical changes in individual muscles.

  14. Four-legged friend or foe? Dog walking displaces native birds from natural areas

    OpenAIRE

    Banks, Peter B.; Bryant, Jessica V.

    2007-01-01

    Dog walking is among the world's most popular recreational activities, attracting millions of people to natural areas each year with diverse benefits to human and canine health. But conservation managers often ban dog walking from natural areas fearing that wildlife will see dogs as potential predators and abandon their natural habitats, resulting in outcry at the restricted access to public land. Arguments are passionate on both sides and debate has remained subjective and unresolved because...

  15. Minimal walking distance following exercise treatment in patients with arterial occlusive disease.

    Science.gov (United States)

    Rosetzsky, A; Struckmann, J; Mathiesen, F R

    1985-01-01

    79 patients with intermittent claudication were tested with peripheral blood pressure measurement and determination of minimal walking distance before and after a 3 months' period with scheduled walking exercises under supervision. No change in peripheral blood pressure was observed following the treatment whereas the minimum walking distance was increased with statistical significance. The gain was most pronounced in patients with an initial combination of high peripheral pressures and short walking distances. A graphic presentation allows for the estimation of the expected gain in individual patients with claudication.

  16. Estimating photosynthetic vegetation, non-photosynthetic vegetation and bare soil fractions using Landsat and MODIS data: Effects of site heterogeneity, soil properties and land cover

    Science.gov (United States)

    Guerschman, J. P.; Scarth, P.; McVicar, T.; Malthus, T. J.; Stewart, J.; Rickards, J.; Trevithick, R.; Renzullo, L. J.

    2013-12-01

    Vegetation fractional cover is a key indicator for land management monitoring, both in pastoral and agricultural settings. Maintaining adequate vegetation cover protects the soil from the effects of water and wind erosion and also ensures that carbon is returned to soil through decomposition. Monitoring vegetation fractional cover across large areas and continuously in time needs good remote sensing techniques underpinned by high quality ground data to calibrate and validate algorithms. In this study we used Landsat and MODIS reflectance data together with field measurements from 1476 observations across Australia to produce estimates of vegetation fractional cover using a linear unmixing technique. Specifically, we aimed at separating fractions of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV) and bare soil (B). We used Landsat reflectance averaged over a 3x3 pixel window representing the area actually measured on the ground and also a 'degraded' Landsat reflectance 40x40 pixel window to simulate the effect of a coarser sensor. Using these two Landsat reflectances we quantified the heterogeneity of each site. We used data from two MODIS-derived reflectance products: the Nadir BRDF-Adjusted surface Reflectance product (MCD43A4) and the MODIS 8-day surface reflectance (MOD09A1). We derived endmembers from the data and estimated fractional cover using a linear unmixing technique. Log transforms and band interaction terms were added to account for non-linearities in the spectral mixing. For each reflectance source we investigated if the residuals were correlated with site heterogeneity, soil colour, soil moisture and land cover type. As expected, the best model was obtained when Landsat data for a small region around each site was used. We obtained root mean square error (RMSE) values of 0.134, 0.175 and 0.153 for PV, NPV and B respectively. When we degraded the Landsat data to an area of ~1 km2 around each site the model performance decreased to

  17. A Study of Spatial Soil Moisture Estimation Using a Multiple Linear Regression Model and MODIS Land Surface Temperature Data Corrected by Conditional Merging

    Directory of Open Access Journals (Sweden)

    Chunggil Jung

    2017-08-01

    Full Text Available This study attempts to estimate spatial soil moisture in South Korea (99,000 km2 from January 2013 to December 2015 using a multiple linear regression (MLR model and the Terra moderate-resolution imaging spectroradiometer (MODIS land surface temperature (LST and normalized distribution vegetation index (NDVI data. The MODIS NDVI was used to reflect vegetation variations. Observed precipitation was measured using the automatic weather stations (AWSs of the Korea Meteorological Administration (KMA, and soil moisture data were recorded at 58 stations operated by various institutions. Prior to MLR analysis, satellite LST data were corrected by applying the conditional merging (CM technique and observed LST data from 71 KMA stations. The coefficient of determination (R2 of the original LST and observed LST was 0.71, and the R2 of corrected LST and observed LST was 0.95 for 3 selected LST stations. The R2 values of all corrected LSTs were greater than 0.83 for total 71 LST stations. The regression coefficients of the MLR model were estimated seasonally considering the five-day antecedent precipitation. The p-values of all the regression coefficients were less than 0.05, and the R2 values were between 0.28 and 0.67. The reason for R2 values less than 0.5 is that the soil classification at each observation site was not completely accurate. Additionally, the observations at most of the soil moisture monitoring stations used in this study started in December 2014, and the soil moisture measurements did not stabilize. Notably, R2 and root mean square error (RMSE in winter were poor, as reflected by the many missing values, and uncertainty existed in observations due to freezing and mechanical errors in the soil. Thus, the prediction accuracy is low in winter due to the difficulty of establishing an appropriate regression model. Specifically, the estimated map of the soil moisture index (SMI can be used to better understand the severity of droughts with the

  18. The Dead Walk

    Directory of Open Access Journals (Sweden)

    Bill Phillips

    2014-02-01

    Full Text Available Monsters have always enjoyed a significant presence in the human imagination, and religion was instrumental in replacing the physical horror they engendered with that of a moral threat. Zombies, however, are amoral – their motivation purely instinctive and arbitrary, yet they are, perhaps, the most loathed of all contemporary monsters. One explanation for this lies in the theory of the uncanny valley, proposed by robotics engineer Masahiro Mori. According to the theory, we reserve our greatest fears for those things which seem most human, yet are not – such as dead bodies. Such a reaction is most likely a survival mechanism to protect us from danger and disease – a mechanism even more essential when the dead rise up and walk. From their beginnings zombies have reflected western societies’ greatest fears – be they of revolutionary Haitians, women, or communists. In recent years the rise in the popularity of the zombie in films, books and television series reflects our fears for the planet, the economy, and of death itself

  19. Quantum Walk with Jumps

    CERN Document Server

    Lavička, H; Kiss, T; Lutz, E; Jex, I

    2011-01-01

    We analyze a special class of 1-D quantum walks (QWs) realized using optical multi-ports. We assume non-perfect multi-ports showing errors in the connectivity, i.e. with a small probability the multi- ports can connect not to their nearest neighbor but to another multi-port at a fixed distance - we call this a jump. We study two cases of QW with jumps where multiple displacements can emerge at one timestep. The first case assumes time-correlated jumps (static disorder). In the second case, we choose the positions of jumps randomly in time (dynamic disorder). The probability distributions of position of the QW walker in both instances differ significantly: dynamic disorder leads to a Gaussian-like distribution, while for static disorder we find two distinct behaviors depending on the parity of jump size. In the case of even-sized jumps, the distribution exhibits a three-peak profile around the position of the initial excitation, whereas the probability distribution in the odd case follows a Laplace-like discre...

  20. Big power from walking

    Science.gov (United States)

    Illenberger, Patrin K.; Madawala, Udaya K.; Anderson, Iain A.

    2016-04-01

    Dielectric Elastomer Generators (DEG) offer an opportunity to capture the energy otherwise wasted from human motion. By integrating a DEG into the heel of standard footwear, it is possible to harness this energy to power portable devices. DEGs require substantial auxiliary systems which are commonly large, heavy and inefficient. A unique challenge for these low power generators is the combination of high voltage and low current. A void exists in the semiconductor market for devices that can meet these requirements. Until these become available, existing devices must be used in an innovative way to produce an effective DEG system. Existing systems such as the Bi-Directional Flyback (BDFB) and Self Priming Circuit (SPC) are an excellent example of this. The BDFB allows full charging and discharging of the DEG, improving power gained. The SPC allows fully passive voltage boosting, removing the priming source and simplifying the electronics. This paper outlines the drawbacks and benefits of active and passive electronic solutions for maximizing power from walking.

  1. Integrated photonic quantum walks

    Science.gov (United States)

    Gräfe, Markus; Heilmann, René; Lebugle, Maxime; Guzman-Silva, Diego; Perez-Leija, Armando; Szameit, Alexander

    2016-10-01

    Over the last 20 years quantum walks (QWs) have gained increasing interest in the field of quantum information science and processing. In contrast to classical walkers, quantum objects exhibit intrinsic properties like non-locality and non-classical many-particle correlations, which renders QWs a versatile tool for quantum simulation and computation as well as for a deeper understanding of genuine quantum mechanics. Since they are highly controllable and hardly interact with their environment, photons seem to be ideally suited quantum walkers. In order to study and exploit photonic QWs, lattice structures that allow low loss coherent evolution of quantum states are demanded. Such requirements are perfectly met by integrated optical waveguide devices that additionally allow a substantial miniaturization of experimental settings. Moreover, by utilizing the femtosecond direct laser writing technique three-dimensional waveguide structures are capable of analyzing QWs also on higher dimensional geometries. In this context, advances and findings of photonic QWs are discussed in this review. Various concepts and experimental results are presented covering, such as different quantum transport regimes, the Boson sampling problem, and the discrete fractional quantum Fourier transform.

  2. Cross Sectional Association between Spatially Measured Walking Bouts and Neighborhood Walkability

    Directory of Open Access Journals (Sweden)

    Liang-Dar Hwang

    2016-04-01

    Full Text Available Walking is the most popular choice of aerobic physical activity to improve health among U.S. adults. Physical characteristics of the home neighborhood can facilitate or hinder walking. The purpose of this study was to quantify neighborhood walking, using objective methods and to examine the association between counts of walking bouts in the home neighborhood and neighborhood walkability. This was a cross-sectional study of 106 adults who wore accelerometers and GPS devices for two weeks. Walking was quantified within 1, 2, and 3 km Euclidean (straight-line and network buffers around the geocoded home location. Walkability was estimated using a commercially available index. Walking bout counts increased with buffer size and were associated with walkability, regardless of buffer type or size (p < 0.001. Quantification of walking bouts within (and outside of pre-defined neighborhood buffers of different sizes and types allowed for the specification of walking locations to better describe and elucidate walking behaviors. These data support the concept that neighborhood characteristics can influence walking among adults.

  3. Walking Robot Locomotion System Conception

    Directory of Open Access Journals (Sweden)

    Ignatova D.

    2014-09-01

    Full Text Available This work is a brief analysis on the application and perspective of using the walking robots in different areas in practice. The most common characteristics of walking four legs robots are presented here. The specific features of the applied actuators in walking mechanisms are also shown in the article. The experience of Institute of Mechanics - BAS is illustrated in creation of Spiroid and Helicon1 gears and their assembly in actuation of studied robots. Loading on joints reductors of robot legs is modelled, when the geometrical and the walking parameters of the studied robot are preliminary defined. The obtained results are purposed for designing the control of the loading of reductor type Helicon in the legs of the robot, when it is experimentally tested.

  4. Quantum Snake Walk on Graphs

    CERN Document Server

    Rosmanis, Ansis

    2010-01-01

    I introduce a new type of continuous-time quantum walk on graphs called the quantum snake walk, the basis states of which are fixed-length paths (snakes) in the underlying graph. First I analyze the quantum snake walk on the line, and I show that, even though most states stay localized throughout the evolution, there are specific states which most likely move on the line as wave packets with momentum inversely proportional to the length of the snake. Next I discuss how an algorithm based on the quantum snake walk might be able to solve an extended version of the glued trees problem which asks to find a path connecting both roots of the glued trees graph. No efficient quantum algorithm solving this problem is known yet.

  5. Localization of reinforced random walks

    CERN Document Server

    Tarrès, Pierre

    2011-01-01

    We describe and analyze how reinforced random walks can eventually localize, i.e. only visit finitely many sites. After introducing vertex and edge self-interacting walks on a discrete graph in a general setting, and stating the main results and conjectures so far on the topic, we present martingale techniques that provide an alternative proof of the a.s. localization of vertex-reinforced random walks (VRRWs) on the integers on finitely many sites and, with positive probability, on five consecutive sites, initially proved by Pemantle and Volkov (1999). Next we introduce the continuous time-lines representation (sometimes called Rubin construction) and its martingale counterpart, and explain how it has been used to prove localization of some reinforced walks on one attracting edge. Then we show how a modified version of this construction enables one to propose a new short proof of the a.s. localization of VRRWs on five sites on Z.

  6. Bouchaud walks with variable drift

    CERN Document Server

    Parra, Manuel Cabezas

    2010-01-01

    In this paper we study a sequence of Bouchaud trap models on $\\mathbb{Z}$ with drift. We analyze the possible scaling limits for a sequence of walks, where we make the drift decay to 0 as we rescale the walks. Depending on the speed of the decay of the drift we obtain three different scaling limits. If the drift decays slowly as we rescale the walks we obtain the inverse of an \\alpha$-stable subordinator as scaling limit. If the drift decays quickly as we rescale the walks, we obtain the F.I.N. diffusion as scaling limit. There is a critical speed of decay separating these two main regimes, where a new process appears as scaling limit. This critical speed is related to the index $\\alpha$ of the inhomogeneity of the environment.

  7. International comparisons of the associations between objective measures of the built environment and transport-related walking and cycling

    DEFF Research Database (Denmark)

    Christiansen, Lars B; Cerin, Ester; Badland, Hannah;

    2016-01-01

    and socioeconomic status. Analyses were conducted on 12,181 adults aged 18-66 years, drawn from 14 cities across 10 countries worldwide. Frequency of transport-related walking and cycling over the last seven days was assessed by questionnaire and four objectively measured built environment variables were calculated......-connected street network, more diverse land uses, and having more parks were positively associated with transport-related walking and/or cycling. Except for land-use-mix, all built environment variables had curvilinear relationships with walking, with a plateau in the relationship at higher levels of the scales....

  8. Position-space renormalization-group approach to the resistance of random walks

    Science.gov (United States)

    Sahimi, Muhammad; Jerauld, Gary R.; Scriven, L. E.; Davis, H. Ted

    1984-06-01

    We consider a Pólya random walk, i.e., an unbiased, nearest-neighbor walk, on a d-dimensional hypercubic lattice and study the scaling behavior of the mean end-to-end resistance of the walk as a function of the number of steps in the walk. The resistance of the walk is generated by assigning a constant conductance to each step of the walk. This problem was recently proposed by Banavar, Harris, and Koplik, and may be useful for understanding the physics of disordered systems. We develop a position-space renormalization-group approach, a generalization of the one developed for percolation conductivity, and study the problem and a modification of it proposed here in one, two, and three dimensions. Our results are in good agreement with the numerical estimates of Banavar et al.

  9. Walking behavior in technicolored GUTs

    Energy Technology Data Exchange (ETDEWEB)

    Doff, A. [Universidade Tecnologica Federal do Parana-UTFPR-COMAT, Pato Branco, PR (Brazil)

    2009-03-15

    There exist two ways to obtain walk behavior: assuming a large number of technifermions in the fundamental representation of the technicolor (TC) gauge group, or a small number of technifermions, assuming that these fermions are in higher-dimensional representations of the TC group. We propose a scheme to obtain the walking behavior based on technicolored GUTs (TGUTs), where elementary scalars with the TC degree of freedom may remain in the theory after the GUT symmetry breaking. (orig.)

  10. Going round the bend: Persistent personal biases in walked angles.

    Science.gov (United States)

    Jetzschke, Simon; Ernst, Marc O; Moscatelli, Alessandro; Boeddeker, Norbert

    2016-03-23

    For navigation through our environment, we can rely on information from various modalities, such as vision and audition. This information enables us for example to estimate our position relative to the starting position, or to integrate velocity and acceleration signals from the vestibular organ and proprioception to estimate the displacement due to self-motion. To better understand the mechanisms that underlie human navigation we analysed the performance of participants in an angle-walking task in the absence of visual and auditory signals. To this end, we guided them along paths of different lengths and asked them to turn by an angle of ±90°. We found significant biases in turn angles, i.e. systematic deviations from the correct angle and that these were characteristic for individual participants. Varying path length, however, had little effect on turn accuracy and precision. To check whether this idiosyncrasy was persistent over time and present in another type of walking task, we performed a second experiment several weeks later. Here, the same participants were guided to walk angles with varying amplitude. We then asked them to judge whether they had walked an angle larger or smaller than 90° in a two-alternative forced-choice paradigm. The personal bias was highly correlated between the two experiments even though they were conducted weeks apart. The presence of a persistent bias in walked angles in the absence of external directional cues indicates a possible error component for navigation, which is surprisingly time stable and idiosyncratic.

  11. UKF滤波方法及其在车辆导航状态估计中的应用%Application of Unscented Kalman Filter in State Estimation for Land Vehicle Navigation System

    Institute of Scientific and Technical Information of China (English)

    张传斌; 田蔚风; 金志华

    2005-01-01

    In a land vehicle navigation system, generally the Extended Kalman Filter (EKF) is as a state estimation method to improve the accuracy of navigation. However, as defects of the EKF in nonlinear estimation, there exists estimated error, which affects the accuracy of the navigation system, when it is adopted in nonlinear estimation of a navigation system. In order to yield the higher accuracy of navigation, a novel method-Unscented Kalman Filter (UKF) was employed in state estimation for a land vehicle navigation system. For a land vehicle DR/GPS navigation system, the EKF and UKF are compared through simulation. Simulation results show that the UKF is superior to the EKF in state estimation for a land vehicle navigation system.%在车载导航系统中,通常采用EKF作为状态估计方法提高导航的精度.由于EKF进行非线性估计存在一些缺陷,因此将其用于导航系统的非线性估计时,存在估计误差,从而影响导航系统的精度.为了获得更高的导航精度,将一种新的滤波方法-UKF方法用于车载导航系统的状态估计中.对一个车载DR/GPS组合系统,将EKF和UKF方法分别进行了滤波仿真.仿真结果表明:在车载导航状态估计中,UKF方法优于EKF方法.

  12. Applying the Land Use Portfolio Model to Estimate Natural-Hazard Loss and Risk - A Hypothetical Demonstration for Ventura County, California

    Science.gov (United States)

    Dinitz, Laura B.

    2008-01-01

    -MH currently performs analyses for earthquakes, floods, and hurricane wind. HAZUS-MH loss estimates, however, do not account for some uncertainties associated with the specific natural-hazard scenarios, such as the likelihood of occurrence within a particular time horizon or the effectiveness of alternative risk-reduction options. Because of the uncertainties involved, it is challenging to make informative decisions about how to cost-effectively reduce risk from natural-hazard events. Risk analysis is one approach that decision-makers can use to evaluate alternative risk-reduction choices when outcomes are unknown. The Land Use Portfolio Model (LUPM), developed by the U.S. Geological Survey (USGS), is a geospatial scenario-based tool that incorporates hazard-event uncertainties to support risk analysis. The LUPM offers an approach to estimate and compare risks and returns from investments in risk-reduction measures. This paper describes and demonstrates a hypothetical application of the LUPM for Ventura County, California, and examines the challenges involved in developing decision tools that provide quantitative methods to estimate losses and analyze risk from natural hazards.

  13. Measuring walking within and outside the neighborhood in Chinese elders: reliability and validity

    Directory of Open Access Journals (Sweden)

    Cerin Ester

    2011-11-01

    Full Text Available Abstract Background Walking is a preferred, prevalent and recommended activity for aging populations and is influenced by the neighborhood built environment. To study this influence it is necessary to differentiate whether walking occurs within or outside of the neighborhood. The Neighborhood Physical Activity Questionnaire (NPAQ collects information on setting-specific physical activity, including walking, inside and outside one's neighborhood. While the NPAQ has shown to be a reliable measure in adults, its reliability in older adults is unknown. Additionally its validity and the influence of type of neighborhood on reliability and validity have yet to be explored. Methods The NPAQ walking component was adapted for Chinese speaking elders (NWQ-CS. Ninety-six Chinese elders, stratified by social economic status and neighborhood walkability, wore an accelerometer and completed a log of walks for 7 days. Following the collection of valid data the NWQ-CS was interviewer-administered. Fourteen to 20 days (average of 17 days later the NWQ-CS was re-administered. Test-retest reliability and validity of the NWQ-CS were assessed. Results Reliability and validity estimates did not differ with type of neighborhood. NWQ-CS measures of walking showed moderate to excellent reliability. Reliability was generally higher for estimates of weekly frequency than minutes of walking. Total weekly minutes of walking were moderately related to all accelerometry measures. Moderate-to-strong associations were found between the NWQ-CS and log-of-walks variables. The NWQ-CS yielded statistically significantly lower mean values of total walking, weekly minutes of walking for transportation and weekly frequency of walking for transportation outside the neighborhood than the log-of-walks. Conclusions The NWQ-CS showed measurement invariance across types of neighborhoods. It is a valid measure of walking for recreation and frequency of walking for transport. However, it may

  14. A lower bound for S-parameter for Walking Technicolor

    Energy Technology Data Exchange (ETDEWEB)

    Ignjatovic, S.R. [Prirodno-Matematicki Fakultet, Banja Luka (BA)

    2008-04-15

    The author applies the ACD method (M. A. Shifman, A. I. Vainshtein, V. I. Zakharov (1979)), modified by the approximation of the kernel by a truncated Taylor series around the upper cut-off, to the estimation of the S-parameter describing the electroweak radiative corrections in walking technicolor. (HSI)

  15. Simulating intrafraction prostate motion with a random walk model

    Directory of Open Access Journals (Sweden)

    Tobias Pommer, PhD

    2017-07-01

    Conclusions: Random walk modeling is feasible and recreated the characteristics of the observed prostate motion. Introducing artificial transient motion did not improve the overall agreement, although the first 30 seconds of the traces were better reproduced. The model provides a simple estimate of prostate motion during delivery of radiation therapy.

  16. Perceived neighborhood environmental attributes associated with adults’ transport-related walking and cycling: Findings from the USA, Australia and Belgium

    Directory of Open Access Journals (Sweden)

    Van Dyck Delfien

    2012-06-01

    Full Text Available Abstract Background Active transportation has the potential to contribute considerably to overall physical activity levels in adults and is likely to be influenced by neighborhood-related built environment characteristics. Previous studies that examined the associations between built environment attributes and active transportation, focused mainly on transport-related walking