Pump to signal noise transfer in parametric fiber amplifiers

DEFF Research Database (Denmark)

Lund-Hansen, Toke; Rottwitt, Karsten; Peucheret, Christophe

2010-01-01

Fiber optic parametric amplifiers have been suggested due to their potential low spontaneous emission. However, by nature the parametric amplifier only work in a forward pumped configuration, which result in transfer of relative intensity noise in the pump to the signal.......Fiber optic parametric amplifiers have been suggested due to their potential low spontaneous emission. However, by nature the parametric amplifier only work in a forward pumped configuration, which result in transfer of relative intensity noise in the pump to the signal....

Noise and signal interference in optical fiber transmission systems an optimum design approach

CERN Document Server

Bottacchi, Stefano

2008-01-01

A comprehensive reference to noise and signal interference in optical fiber communications Noise and Signal Interference in Optical Fiber Transmission Systems is a compendium on specific topics within optical fiber transmission and the optimization process of the system design. It offers comprehensive treatment of noise and intersymbol interference (ISI) components affecting optical fiber communications systems, containing coverage on noise from the light source, the fiber and the receiver. The ISI is modeled with a statistical approach, leading to new useful computational m

Tree Climbing Robot Design, Kinematics and Motion Planning

CERN Document Server

Lam, Tin Lun

2012-01-01

Climbing robot is a challenging research topic that has gained much attention from researchers. Most of the robots reported in the literature are designed to climb on manmade structures, but seldom robots are designed for climbing natural environment such as trees. Trees and manmade structures are very different in nature. It brings different aspects of technical challenges to the robot design. In this book, you can find a collection of the cutting edge technologies in the field of tree-climbing robot and the ways that animals climb. It provides a valuable reference for robot designers to select appropriate climbing methods in designing tree-climbing robots for specific purposes. Based on the study, a novel bio-inspired tree-climbing robot with several breakthrough performances has been developed and presents in this book. It is capable of performing various actions that is impossible in the state-of-the-art tree-climbing robots, such as moving between trunk and branches. This book also proposes several appro...

Optical frequency upconversion technique for transmission of wireless MIMO-type signals over optical fiber.

Science.gov (United States)

Shaddad, R Q; Mohammad, A B; Al-Gailani, S A; Al-Hetar, A M

2014-01-01

The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength.

Bouldering: an alternative strategy to long-vertical climbing in root-climbing hortensias.

Science.gov (United States)

Granados Mendoza, Carolina; Isnard, Sandrine; Charles-Dominique, Tristan; Van den Bulcke, Jan; Rowe, Nick P; Van Acker, Joris; Goetghebeur, Paul; Samain, Marie-Stéphanie

2014-10-06

In the Neotropics, the genus Hydrangea of the popular ornamental hortensia family is represented by climbing species that strongly cling to their support surface by means of adhesive roots closely positioned along specialized anchoring stems. These root-climbing hortensia species belong to the nearly exclusive American Hydrangea section Cornidia and generally are long lianescent climbers that mostly flower and fructify high in the host tree canopy. The Mexican species Hydrangea seemannii, however, encompasses not only long lianescent climbers of large vertical rock walls and coniferous trees, but also short 'shrub-like' climbers on small rounded boulders. To investigate growth form plasticity in root-climbing hortensia species, we tested the hypothesis that support variability (e.g. differences in size and shape) promotes plastic responses observable at the mechanical, structural and anatomical level. Stem bending properties, architectural axis categorization, tissue organization and wood density were compared between boulder and long-vertical tree-climbers of H. seemannii. For comparison, the mechanical patterns of a closely related, strictly long-vertical tree-climbing species were investigated. Hydrangea seemannii has fine-tuned morphological, mechanical and anatomical responses to support variability suggesting the presence of two alternative root-climbing strategies that are optimized for their particular environmental conditions. Our results suggest that variation of some stem anatomical traits provides a buffering effect that regulates the mechanical and hydraulic demands of two distinct plant architectures. The adaptive value of observed plastic responses and the importance of considering growth form plasticity in evolutionary and conservation studies are discussed. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Lifting as You Climb

Science.gov (United States)

Sullivan, Debra R.

2009-01-01

This article addresses leadership themes and answers leadership questions presented to "Exchange" by the Panel members who attended the "Exchange" Panel of 300 Reception in Dallas, Texas, last November. There is an old proverb that encourages people to lift as they climb: "While you climb a mountain, you must not forget others along the way." With…

Modeling borehole microseismic and strain signals measured by a distributed fiber optic sensor

Science.gov (United States)

Mellors, R. J.; Sherman, C. S.; Ryerson, F. J.; Morris, J.; Allen, G. S.; Messerly, M. J.; Carr, T.; Kavousi, P.

2017-12-01

The advent of distributed fiber optic sensors installed in boreholes provides a new and data-rich perspective on the subsurface environment. This includes the long-term capability for vertical seismic profiles, monitoring of active borehole processes such as well stimulation, and measuring of microseismic signals. The distributed fiber sensor, which measures strain (or strain-rate), is an active sensor with highest sensitivity parallel to the fiber and subject to varying types of noise, both external and internal. We take a systems approach and include the response of the electronics, fiber/cable, and subsurface to improve interpretation of the signals. This aids in understanding noise sources, assessing error bounds on amplitudes, and developing appropriate algorithms for improving the image. Ultimately, a robust understanding will allow identification of areas for future improvement and possible optimization in fiber and cable design. The subsurface signals are simulated in two ways: 1) a massively parallel multi-physics code that is capable of modeling hydraulic stimulation of heterogeneous reservoir with a pre-existing discrete fracture network, and 2) a parallelized 3D finite difference code for high-frequency seismic signals. Geometry and parameters for the simulations are derived from fiber deployments, including the Marcellus Shale Energy and Environment Laboratory (MSEEL) project in West Virginia. The combination mimics both the low-frequency strain signals generated during the fracture process and high-frequency signals from microseismic and perforation shots. Results are compared with available fiber data and demonstrate that quantitative interpretation of the fiber data provides valuable constraints on the fracture geometry and microseismic activity. These constraints appear difficult, if not impossible, to obtain otherwise.

Indoor rock climbing: who gets injured?

Science.gov (United States)

Wright, D M; Royle, T J; Marshall, T

2001-06-01

To determine the frequency of overuse injury in indoor climbers, the common sites of such injury, and the factors that influence the probability that a climber will have sustained an overuse injury while climbing indoors. A semisupervised questionnaire was used to survey overuse injury in 295 spectators and competitors at the Entre-Prises World Climbing Championships held in Birmingham 3-5 December 1999. Statistical analysis included simple cross tabulations, calculation of odds ratios, and multiple logistic regression to explore the effect of several factors simultaneously. Some 44% of respondents had sustained an overuse injury, 19% at more than one site. The most common site of injury was the fingers. Univariate analysis showed that the probability of having sustained a climbing injury is higher in men (p = 0.009), those who have climbed for more than 10 years (p = 0.006), those who climb harder routes (p<0.0005), and those who boulder or lead more than they top rope (p<0.0005). The relation between lead grade and climbing injury is linear. Multivariate analysis removed the effect of sex as an independent predictor. Many climbers sustain overuse injury. The most at risk are those with the most ability and dedication to climbing. Climbers should be aware of the risk factors that influence injury and be able to spot the signs and symptoms of injury once they occur.

Kinematic and Dynamic Analysis of a Cable-Climbing Robot

Directory of Open Access Journals (Sweden)

Xu Fengyu

2015-07-01

Full Text Available To inspect broken cables or a cracked protective layer on cable-stayed bridges, a cable-climbing robot has been proposed and designed. In this paper, the complex 3D obstacles that may be encountered on cables are theoretically described, in order to investigate the obstacle-climbing capability of the cable-climbing robot. A climbing model is then proposed and used to design the robot. In the climbing model, two driven wheels are independently supported with a spring. Kinematics and dynamics models are further derived for the obstacle-climbing capabilities of the driving and driven wheels of the robot. In addition, the robot's obstacle-climbing tracks and its obstacle-climbing performance are simulated. Payload and obstacle-climbing experiments were conducted on the climbing robot in the laboratory. Based on the results of the simulation and the experiments, we obtained the variation of the driving torque in obstacle climbing. The contribution of this paper is intended to provide a basis for the precise motion control of the robot.

Evolutionary novelty versus exaptation: oral kinematics in feeding versus climbing in the waterfall-climbing Hawaiian Goby Sicyopterus stimpsoni.

Directory of Open Access Journals (Sweden)

Joshua A Cullen

Full Text Available Species exposed to extreme environments often exhibit distinctive traits that help meet the demands of such habitats. Such traits could evolve independently, but under intense selective pressures of extreme environments some existing structures or behaviors might be coopted to meet specialized demands, evolving via the process of exaptation. We evaluated the potential for exaptation to have operated in the evolution of novel behaviors of the waterfall-climbing gobiid fish genus Sicyopterus. These fish use an "inching" behavior to climb waterfalls, in which an oral sucker is cyclically protruded and attached to the climbing surface. They also exhibit a distinctive feeding behavior, in which the premaxilla is cyclically protruded to scrape diatoms from the substrate. Given the similarity of these patterns, we hypothesized that one might have been coopted from the other. To evaluate this, we filmed climbing and feeding in Sicyopterus stimpsoni from Hawai'i, and measured oral kinematics for two comparisons. First, we compared feeding kinematics of S. stimpsoni with those for two suction feeding gobiids (Awaous guamensis and Lentipes concolor, assessing what novel jaw movements were required for algal grazing. Second, we quantified the similarity of oral kinematics between feeding and climbing in S. stimpsoni, evaluating the potential for either to represent an exaptation from the other. Premaxillary movements showed the greatest differences between scraping and suction feeding taxa. Between feeding and climbing, overall profiles of oral kinematics matched closely for most variables in S. stimpsoni, with only a few showing significant differences in maximum values. Although current data cannot resolve whether oral movements for climbing were coopted from feeding, or feeding movements coopted from climbing, similarities between feeding and climbing kinematics in S. stimpsoni are consistent with evidence of exaptation, with modifications, between these

Evolutionary novelty versus exaptation: oral kinematics in feeding versus climbing in the waterfall-climbing Hawaiian Goby Sicyopterus stimpsoni.

Science.gov (United States)

Cullen, Joshua A; Maie, Takashi; Schoenfuss, Heiko L; Blob, Richard W

2013-01-01

Species exposed to extreme environments often exhibit distinctive traits that help meet the demands of such habitats. Such traits could evolve independently, but under intense selective pressures of extreme environments some existing structures or behaviors might be coopted to meet specialized demands, evolving via the process of exaptation. We evaluated the potential for exaptation to have operated in the evolution of novel behaviors of the waterfall-climbing gobiid fish genus Sicyopterus. These fish use an "inching" behavior to climb waterfalls, in which an oral sucker is cyclically protruded and attached to the climbing surface. They also exhibit a distinctive feeding behavior, in which the premaxilla is cyclically protruded to scrape diatoms from the substrate. Given the similarity of these patterns, we hypothesized that one might have been coopted from the other. To evaluate this, we filmed climbing and feeding in Sicyopterus stimpsoni from Hawai'i, and measured oral kinematics for two comparisons. First, we compared feeding kinematics of S. stimpsoni with those for two suction feeding gobiids (Awaous guamensis and Lentipes concolor), assessing what novel jaw movements were required for algal grazing. Second, we quantified the similarity of oral kinematics between feeding and climbing in S. stimpsoni, evaluating the potential for either to represent an exaptation from the other. Premaxillary movements showed the greatest differences between scraping and suction feeding taxa. Between feeding and climbing, overall profiles of oral kinematics matched closely for most variables in S. stimpsoni, with only a few showing significant differences in maximum values. Although current data cannot resolve whether oral movements for climbing were coopted from feeding, or feeding movements coopted from climbing, similarities between feeding and climbing kinematics in S. stimpsoni are consistent with evidence of exaptation, with modifications, between these behaviors. Such

An evanescent wave biosensor--Part I: Fluorescent signal acquisition from step-etched fiber optic probes.

Science.gov (United States)

Anderson, G P; Golden, J P; Ligler, F S

1994-06-01

A fiber-optic biosensor capable of remote continuous monitoring has recently been designed. To permit sensing at locations separate from the optoelectronic instrumentation, long optical fibers are utilized. An evanescent wave immuno-probe is prepared by removing the cladding near the distal end of the fiber and covalently attaching antibodies to the core. Probes with a radius unaltered from that of the original core inefficiently returned the signal produced upon binding the fluorescent-labelled antigen. To elucidate the limiting factors in signal acquisition, a series of fibers with increasingly reduced probe core radius was examined. The results were consistent with the V-number mismatch, the difference in mode carrying capacity between the clad and unclad fiber, being a critical factor in limiting signal coupling from the fiber probe. However, it was also delineated that conditions which conserve excitation power, such that power in the evanescent wave is optimized, must also be met to obtain a maximal signal. The threshold sensitivity for the optimal step-etched fiber probe was improved by over 20-fold in an immunoassay, although, it was demonstrated that signal acquisition decreased along the probe length, suggesting that a sensor region of uniform radius is not ideal.

Effects of Sport Climbing on Multiple Sclerosis

Directory of Open Access Journals (Sweden)

Julia Steimer

2017-12-01

Full Text Available Multiple sclerosis (MS is an autoimmune and neurodegenerative disease of the central nervous system (CNS with different types of disease courses (relapsing-remitting, secondary-progressive, primary progressive that leads to physical as well as mental disability. The symptoms comprise paresis or/and paralysis, ataxia, bladder dysfunction, visual problems as well as effects on cognition. There is limited data regarding the possible effects of sport climbing respectively therapeutic climbing on patients with MS. Sport climbing offers many potentially beneficial effects for patients with MS since there are effects on coordination, muscular strength, and cognition to name the most relevant ones. Also, disease models in rodents point toward such positive outcomes of climbing. Therefore, we assessed the currently available research literature on general effects of physical exercise, impact of climbing on body and mind and therapeutic climbing for prevention or therapy for the treatment of MS. The sparse published controlled trials that investigated this sport activity on different groups of patients with neurological or geriatric diseases grossly differ in study design and outcome parameters. Nevertheless, it appears that climbing offers the opportunity to improve some of the symptoms of patients with MS and can contribute to an enhanced quality of life.

Measurement of splanchnic photoplethysmographic signals using a new reflectance fiber optic sensor

Science.gov (United States)

Hickey, Michelle; Samuels, Neal; Randive, Nilesh; Langford, Richard M.; Kyriacou, Panayiotis A.

2010-03-01

Splanchnic organs are particularly vulnerable to hypoperfusion. Currently, there is no technique that allows for the continuous estimation of splanchnic blood oxygen saturation (SpO2). As a preliminary to developing a suitable splanchnic SpO2 sensor, a new reflectance fiber optic photoplethysmographic (PPG) sensor and processing system are developed. An experimental procedure to examine the effect of fiber source detector separation distance on acquired PPG signals is carried out before finalizing the sensor design. PPG signals are acquired from four volunteers for separation distances of 1 to 8 mm. The separation range of 3 to 6 mm provides the best quality PPG signals with large amplitudes and the highest signal-to-noise ratios (SNRs). Preliminary calculation of SpO2 shows that distances of 3 and 4 mm provide the most realistic values. Therefore, it is suggested that the separation distance in the design of a fiber optic reflectance pulse oximeter be in the range of 3 to 4 mm. Preliminary PPG signals from various splanchnic organs and the periphery are obtained from six anaesthetized patients. The normalized amplitudes of the splanchnic PPGs are, on average, approximately the same as those obtained simultaneously from the periphery. These observations suggest that fiber optic pulse oximetry may be a valid monitoring technique for splanchnic organs.

All-fiber 7x1 signal combiner for incoherent laser beam combining

Science.gov (United States)

Noordegraaf, D.; Maack, M. D.; Skovgaard, P. M. W.; Johansen, J.; Becker, F.; Belke, S.; Blomqvist, M.; Laegsgaard, J.

2011-02-01

We demonstrate an all-fiber 7x1 signal combiner for incoherent laser beam combining. This is a potential key component for reaching several kW of stabile laser output power. The combiner couples the output from 7 single-mode (SM) fiber lasers into a single multi-mode (MM) fiber. The input signal fibers have a core diameter of 17 μm and the output MM fiber has a core diameter of 100 μm. In a tapered section light gradually leaks out of the SM fibers and is captured by a surrounding fluorine-doped cladding. The combiner is tested up to 2.5 kW of combined output power and only a minor increase in device temperature is observed. At an intermediate power level of 600 W a beam parameter product (BPP) of 2.22 mm x mrad is measured, corresponding to an M2 value of 6.5. These values are approaching the theoretical limit dictated by brightness conservation.

All-fiber 7x1 signal combiner for incoherent laser beam combining

DEFF Research Database (Denmark)

Noordegraaf, Danny; Maack, Martin D.; Skovgaard, Peter M. W.

2011-01-01

We demonstrate an all-fiber 7x1 signal combiner for incoherent laser beam combining. This is a potential key component for reaching several kW of stabile laser output power. The combiner couples the output from 7 single-mode (SM) fiber lasers into a single multi-mode (MM) fiber. The input signal ...... in device temperature is observed. At an intermediate power level of 600 W a beam parameter product (BPP) of 2.22 mm x mrad is measured, corresponding to an M2 value of 6.5. These values are approaching the theoretical limit dictated by brightness conservation....

Precise timing signal transmission by a new optical fiber cable

International Nuclear Information System (INIS)

Tanaka, Shigeru; Murakami, Yasunori; Sato, Yoshihiro; Urakawa, Junji.

1990-05-01

For the precise timing signal transmission, a new optical fiber cable system was developed and installed between the 2.5GeV LINAC gun room and the TRISTAN control room. This fiber cable showed the reduced thermal transmission delay change less than 10psec/km in the temperature range from -20 to 30degC (average 0.04ppm/degC), which is 100 times smaller than that of any other existing coaxial cables and conventional optical fiber cables. The developed optical to electrical (O/E) and electrical to optical (E/O) converters also achieved the timing accuracy within 11psec over the temperature range from 10 to 35degC. The installed cable system in KEK eliminated the necessity of adjusting the phase drift of the TRISTAN Accumulation Ring (AR) RF signal (508MHz), which was required with the former coaxial cable due to the temperature change in a year. Measured full width of jitter over the installed 1600m fiber link was 18.8psec. (author)

Tracked robot controllers for climbing obstacles autonomously

Science.gov (United States)

Vincent, Isabelle

2009-05-01

Research in mobile robot navigation has demonstrated some success in navigating flat indoor environments while avoiding obstacles. However, the challenge of analyzing complex environments to climb obstacles autonomously has had very little success due to the complexity of the task. Unmanned ground vehicles currently exhibit simple autonomous behaviours compared to the human ability to move in the world. This paper presents the control algorithms designed for a tracked mobile robot to autonomously climb obstacles by varying its tracks configuration. Two control algorithms are proposed to solve the autonomous locomotion problem for climbing obstacles. First, a reactive controller evaluates the appropriate geometric configuration based on terrain and vehicle geometric considerations. Then, a reinforcement learning algorithm finds alternative solutions when the reactive controller gets stuck while climbing an obstacle. The methodology combines reactivity to learning. The controllers have been demonstrated in box and stair climbing simulations. The experiments illustrate the effectiveness of the proposed approach for crossing obstacles.

Bio-inspired step-climbing in a hexapod robot

International Nuclear Information System (INIS)

Chou, Ya-Cheng; Yu, Wei-Shun; Huang, Ke-Jung; Lin, Pei-Chun

2012-01-01

Inspired by the observation that the cockroach changes from a tripod gait to a different gait for climbing high steps, we report on the design and implementation of a novel, fully autonomous step-climbing maneuver, which enables a RHex-style hexapod robot to reliably climb a step up to 230% higher than the length of its leg. Similar to the climbing strategy most used by cockroaches, the proposed maneuver is composed of two stages. The first stage is the ‘rearing stage,’ inclining the body so the front side of the body is raised and it is easier for the front legs to catch the top of the step, followed by the ‘rising stage,’ maneuvering the body's center of mass to the top of the step. Two infrared range sensors are installed on the front of the robot to detect the presence of the step and its orientation relative to the robot's heading, so that the robot can perform automatic gait transition, from walking to step-climbing, as well as correct its initial tilt approaching posture. An inclinometer is utilized to measure body inclination and to compute step height, thus enabling the robot to adjust its gait automatically, in real time, and to climb steps of different heights and depths successfully. The algorithm is applicable for the robot to climb various rectangular obstacles, including a narrow bar, a bar and a step (i.e. a bar of infinite width). The performance of the algorithm is evaluated experimentally, and the comparison of climbing strategies and climbing behaviors in biological and robotic systems is discussed. (paper)

Activity of southeastern bats along sandstone cliffs used for rock climbing

Science.gov (United States)

Loeb, Susan C.; Jodice, Patrick G. R.

2018-01-01

Bats in the eastern U.S. are facing numerous threats and many species are in decline. Although several species of bats commonly roost in cliffs, little is known about use of cliffs for foraging and roosting. Because rock climbing is a rapidly growing sport and may cause disturbance to bats, our objectives were to examine use of cliff habitats by bats and to assess the effects of climbing on their activity. We used radio-telemetry to track small-footed bats (Myotis leibii) to day roosts, and Anabat SD2 detectors to compare bat activity between climbed and unclimbed areas of regularly climbed cliff faces, and between climbed and unclimbed cliffs. Four adult male small-footed bats were tracked to nine day roosts, all of which were in various types of crevices including five cliff face roosts (three on climbed and two on unclimbed faces). Bat activity was high along climbed cliffs and did not differ between climbed and unclimbed areas of climbed cliffs. In contrast, overall bat activity was significantly higher along climbed cliffs than unclimbed cliffs; species richness did not differ between climbed and unclimbed cliffs or areas. Lower activity along unclimbed cliffs may have been related to lower cliff heights and more clutter along these cliff faces. Due to limited access to unclimbed cliffs of comparable size to climbed cliffs, we could not thoroughly test the effects of climbing on bat foraging and roosting activity. However, the high overall use of climbed and unclimbed cliff faces for foraging and commuting that we observed suggests that cliffs may be important habitat for a number of bat species. Additional research on bats' use of cliff faces will improve our understanding of the factors that affect their use of this habitat including the impacts of climbing.

Performance characterization of the IEEE 802.11 signal transmission over a multimode fiber PON

Science.gov (United States)

Maksymiuk, L.; Siuzdak, J.

2014-11-01

In this paper there are presented measurements concerning performance analysis of the IEEE 802.11 signal distribution over multimode fiber based passive optical network. In the paper there are addressed three main sources of impairments: modal noise, frequency response fluctuation of the multimode fiber and non-linear distortion of the signal in the receiver.

The fastest drop climbing on a wet conical fibre

KAUST Repository

Li, Erqiang; Thoroddsen, Sigurdur T

2013-01-01

We use high-speed video imaging to study the capillary-driven motion of a micro-droplet along the outside of a pre-wetted conical fiber. The cones are fabricated on a glass-puller with tip diameters as small as 1 μm, an order of magnitude smaller than in previous studies. The liquid is fed through the hollow fiber accumulating at the fiber tip to form droplets. The droplets are initially attached to the opening as they grow in size before detaching and traveling up the cone. This detachment can produce a transient oscillation of high frequency. The spatial variation of the capillary pressure drives the droplets towards the wider side of the cone. Various liquids were used to change the surface tension by a factor of 3.5 and viscosity by a factor of 1500. Within each droplet size and viscous-dissipation regime, the data for climbing speeds collapse on a single curve. Droplets traveling with and against gravity allow us to pinpoint the absolute strength of the driving capillary pressure and viscous stresses and thereby determine the prefactors in the dimensionless relationships. The motions are consistent with earlier results obtained from much larger cones. Translation velocities up to 270 mm/s were observed and overall the velocities follow capillary-viscous scaling, whereas the speed of the fastest droplets is limited by inertia following their emergence at the cone tip.

The fastest drop climbing on a wet conical fibre

KAUST Repository

Li, Erqiang

2013-05-21

We use high-speed video imaging to study the capillary-driven motion of a micro-droplet along the outside of a pre-wetted conical fiber. The cones are fabricated on a glass-puller with tip diameters as small as 1 μm, an order of magnitude smaller than in previous studies. The liquid is fed through the hollow fiber accumulating at the fiber tip to form droplets. The droplets are initially attached to the opening as they grow in size before detaching and traveling up the cone. This detachment can produce a transient oscillation of high frequency. The spatial variation of the capillary pressure drives the droplets towards the wider side of the cone. Various liquids were used to change the surface tension by a factor of 3.5 and viscosity by a factor of 1500. Within each droplet size and viscous-dissipation regime, the data for climbing speeds collapse on a single curve. Droplets traveling with and against gravity allow us to pinpoint the absolute strength of the driving capillary pressure and viscous stresses and thereby determine the prefactors in the dimensionless relationships. The motions are consistent with earlier results obtained from much larger cones. Translation velocities up to 270 mm/s were observed and overall the velocities follow capillary-viscous scaling, whereas the speed of the fastest droplets is limited by inertia following their emergence at the cone tip.

Architectures for radio over fiber transmission of high-quality video and data signals

DEFF Research Database (Denmark)

Lebedev, Alexander

with a constraint on complexity. For wireless personal area networks distribution, we explore the notion of joint optimization of physical layer parameters of a fiber-wireless link (optical power levels, wireless transmission distance) and the codec parameters (quantization, error-resilience tools) based...... on the peak signal-to-noise ratio as an objective video quality metric for compressed video transmission. Furthermore, we experimentally demonstrate uncompressed 1080i highdefinition video distribution in V-band (50–75 GHz) and W-band (75–110 GHz) fiber-wireless links achieving 3 m of wireless transmission...... efficient wired/wireless backhaul of picocell networks. Gigabit signal transmission is realized in combined fiber-wireless-fiber link enabling simultaneous backhaul of dense metropolitan and suburban areas. In this Thesis, we propose a technique to combat periodic chromatic dispersion-induced radio...

A simple-architecture fibered transmission system for dissemination of high stability 100 MHz signals

Science.gov (United States)

Bakir, A.; Rocher, C.; Maréchal, B.; Bigler, E.; Boudot, R.; Kersalé, Y.; Millo, J.

2018-05-01

We report on the development of a simple-architecture fiber-based frequency distribution system used to transfer high frequency stability 100 MHz signals. This work is focused on the emitter and the receiver performances that allow the transmission of the radio-frequency signal over an optical fiber. The system exhibits a residual fractional frequency stability of 1 × 10-14 at 1 s integration time and in the low 10-16 range after 100 s. These performances are suitable to transfer the signal of frequency references such as those of a state-of-the-art hydrogen maser without any phase noise compensation scheme. As an application, we demonstrate the dissemination of such a signal through a 100 m long optical fiber without any degradation. The proposed setup could be easily extended for operating frequencies in the 10 MHz-1 GHz range.

Effectiveness and cost of two stair-climbing interventions-less is more.

Science.gov (United States)

Olander, Ellinor K; Eves, Frank F

2011-01-01

The current study compared two interventions for promotion of stair climbing in the workplace, an information-based intervention at a health information day and an environmental intervention (point-of-choice prompts), for their effectiveness in changing stair climbing and cost per employee. Interrupted time-series design. Four buildings on a university campus. Employees at a university in the United Kingdom. Two stair-climbing interventions were compared: (1) a stand providing information on stair climbing at a health information day and (2) point-of-choice prompts (posters). Observers recorded employees' gender and method of ascent (n = 4279). The cost of the two interventions was calculated. Logistic regression. There was no significant difference between baseline (47.9% stair climbing) and the Workplace Wellbeing Day (48.8% stair climbing), whereas the prompts increased stair climbing (52.6% stair climbing). The health information day and point-of-choice prompts cost $773.96 and $31.38, respectively. The stand at the health information day was more expensive than the point-of-choice prompts and was inferior in promoting stair climbing. It is likely that the stand was unable to encourage stair climbing because only 3.2% of targeted employees visited the stand. In contrast, the point-of-choice prompts were potentially visible to all employees using the buildings and hence better for disseminating the stair climbing message to the target audience.

CLIMB grammars: three projects using metagrammar engineering

NARCIS (Netherlands)

Fokkens, A.S.; Avgustinova, T.; Zhang, Yi

2012-01-01

This paper introduces the CLIMB (Comparative Libraries of Implementations with Matrix Basis) methodology and grammars. The basic idea behind CLIMB is to use code generation as a general methodology for grammar development in order to create a more systematic approach to grammar development. The

Biomechanical Analyses of Stair-climbing while Dual-tasking

Science.gov (United States)

Vallabhajosula, Srikant; Tan, Chi Wei; Mukherjee, Mukul; Davidson, Austin J.; Stergiou, Nicholas

2015-01-01

Stair-climbing while doing a concurrent task like talking or holding an object is a common activity of daily living which poses high risk for falls. While biomechanical analyses of overground walking during dual-tasking have been studied extensively, little is known on the biomechanics of stair-climbing while dual-tasking. We sought to determine the impact of performing a concurrent cognitive or motor task during stair-climbing. We hypothesized that a concurrent cognitive task will have a greater impact on stair climbing performance compared to a concurrent motor task and that this impact will be greater on a higher-level step. Ten healthy young adults performed 10 trials of stair-climbing each under four conditions: stair ascending only, stair ascending and performing subtraction of serial sevens from a three-digit number, stair ascending and carrying an empty opaque box and stair ascending, performing subtraction of serial sevens from a random three-digit number and carrying an empty opaque box. Kinematics (lower extremity joint angles and minimum toe clearance) and kinetics (ground reaction forces and joint moments and powers) data were collected. We found that a concurrent cognitive task impacted kinetics but not kinematics of stair-climbing. The effect of dual-tasking during stair ascent also seemed to vary based on the different phases of stair ascent stance and seem to have greater impact as one climbs higher. Overall, the results of the current study suggest that the association between the executive functioning and motor task (like gait) becomes stronger as the level of complexity of the motor task increases. PMID:25773590

The effectiveness of chocolate milk as a post-climbing recovery aid.

Science.gov (United States)

Potter, J; Fuller, B

2015-12-01

Recovery is essential to effective performance in climbing competitions which often involve repeated bouts, and sport climbing where climbers may work a route over a number of days prior to a complete ascent. This study employed a cross-over design to compare water with chocolate milk as recovery aids following an exhaustive bout of high intensity endurance climbing. Ten male climbers (age: 22±1 years; height: 178.5±7.9 cm; mass: 74.7±11.3 kg) climbed a Tredwall (Brewer Ledge M6) until volitional exhaustion. The participants consumed either water or chocolate milk 20 minutes after the climb and then again with their evening meal. The exercise protocol was repeated 24 hours after the original climb. The second condition was completed 7 days later. Workload indicators of heart rate, rate of perceived exertion (RPE), blood lactate and muscle soreness scores were recorded alongside climbing performance measures of duration and distance of the climb. A improved performance was found after the consumption of chocolate milk, with both a greater distance climbed (F(1,9)=11.704, P=0.008) and duration (F(1,9) =10.922, P=0.009), there were no differences in end of climb heart rate or RPE. Muscle soreness scores were lower three days after exercise following chocolate milk (t(8)=3.773, P=0.005). Chocolate milk as a recovery drink resulted in further sustained climbing, a decrease in muscle soreness, compared to water. It may be pertinent for climbers to consider its use as a recovery aid during repeated climbing bouts. Chocolate milk is a relatively unexplored recovery aid and warrants further attention.

Fiber nonlinearity compensation of an 8-channel WDM PDM-QPSK signal using multiple phase conjugations

DEFF Research Database (Denmark)

Hu, Hao; Jopson, R. M.; Dinu, M.

2013-01-01

We demonstrate compensation of fiber nonlinearities using optical phase conjugation of an 8-chamiel WDM 32-Gbaud PDM QPSK signal. Conjugating phase every 600 km in a fiber loop enabled a 6000 km transmission over True Wave fiber. © 2013 Optical Society of America....

Stable transmission of radio frequency signals on fiber links using interferomectric delay sensing

International Nuclear Information System (INIS)

Wilcox, Russell B.; Byrd, J.M.; Doolittle, Lawrence; Huang, Gang; Staples, J.W.

2009-01-01

The authors demonstrate distribution of a 2850 MHz rf signal over stabilized optical fiber links. For a 2.2 km link they measure an rms drift of 19.4 fs over 60 h, and for a 200 m link an rms drift of 8.4 fs over 20 h. The rf signals are transmitted as amplitude modulation on a continuous optical carrier. Variations in the delay length are sensed using heterodyne interferometry and used to correct the rf phase. The system uses standard fiber telecommunications components.

Climbing plants: attachment adaptations and bioinspired innovations.

Science.gov (United States)

Burris, Jason N; Lenaghan, Scott C; Stewart, C Neal

2018-04-01

Climbing plants have unique adaptations to enable them to compete for sunlight, for which they invest minimal resources for vertical growth. Indeed, their stems bear relatively little weight, as they traverse their host substrates skyward. Climbers possess high tensile strength and flexibility, which allows them to utilize natural and manmade structures for support and growth. The climbing strategies of plants have intrigued scientists for centuries, yet our understanding about biochemical adaptations and their molecular undergirding is still in the early stages of research. Nonetheless, recent discoveries are promising, not only from a basic knowledge perspective, but also for bioinspired product development. Several adaptations, including nanoparticle and adhesive production will be reviewed, as well as practical translation of these adaptations to commercial applications. We will review the botanical literature on the modes of adaptation to climb, as well as specialized organs-and cellular innovations. Finally, recent molecular and biochemical data will be reviewed to assess the future needs and new directions for potential practical products that may be bioinspired by climbing plants.

Frequency dependence of the pump-to-signal RIN transfer in fiber optical parametric amplifiers

DEFF Research Database (Denmark)

Pakarzadeh Dezfuli Nezhad, Hassan; Rottwitt, Karsten; Zakery, A.

2009-01-01

Using a numerical model, the frequency dependence of the pump-to-signal RIN transfer in FOPAs has been investigated. The model includes fiber loss, pump depletion as well as difference in group velocity among interacting beams.......Using a numerical model, the frequency dependence of the pump-to-signal RIN transfer in FOPAs has been investigated. The model includes fiber loss, pump depletion as well as difference in group velocity among interacting beams....

Changes in handgrip force and blood lactate as response to simulated climbing competition

Directory of Open Access Journals (Sweden)

J Gajewski

2009-07-01

Full Text Available The aim of the study was to estimate post-competition changes in handgrip strength and blood lactate in climbers and relationships of the studied variables with declared climbing ability of the tested athletes. Twenty one male climbers volunteered to take part in the experiment. Each subject took part in simulated lead climbing competition on the artificial wall – (difficulty 7a in French scale. The blood lactate concentration was measured pre-climbing and then 3 min and 30 min post-climbing. Grip force of both hands (dominant and non-dominant was measured twice – pre-climbing and 1 min post-climbing (semi-final. Maximum heart rate during climbing reached 181.4±7.7 beats per minute. Lactate concentration amounted to 6.35±1.50 mmol/l and 2.28±0.66 mmol/l 3 min and 30 min post-climbing, respectively. Handgrip force related to body mass (averaged for both hands decreased significantly from 7.39±1.30 N/kg pre-climbing to 6.57±1.05 N/kg 1 min post-climbing. Self reported climbing ability was correlated with lactate concentration and handgrip force, as well. It was demonstrated that athletes reporting higher climbing ability showed better lactate recovery.

Promoting workplace stair climbing: sometimes, not interfering is the best.

Science.gov (United States)

Åvitsland, Andreas; Solbraa, Ane Kristiansen; Riiser, Amund

2017-01-01

Stair climbing is a vigorous activity and can lead to several health benefits. Studies seeking to increase stair climbing in various public locations have shown positive effects, while results from similar studies conducted in the workplace are inconclusive. This study examined stair climbing in the workplace, and monitored effects from a single- and a combined intervention. Interventions were inspired by nudging, the libertarian method of influencing behavior. By quasi-experimental design, stair- and elevator traffic in two office buildings was monitored preceding-, during- and following interventions with stair leading footprints alone, and combined with stair-riser banners. Chi square tests were applied to determine differences between baseline and the subsequent periods. Web-based questionnaires were distributed after follow-up period. Elevators and stairs were used 45 237 times, of which 89.6% was stair use. Intervention site stair climbing at baseline (79.0%) was significantly reduced with footprints (-5.1%, p   0.027). Stair climbing was significantly reduced during the intervention periods. Use of stair leading footprints alone, or combined with stair-riser banners in an attempt to influence stair climbing may be ineffective, or cause a negative reaction, when applied in a workplace with a pre-existing high amount of stair climbing.

Incoherent beam combining of fiber lasers by an all-fiber 7 × 1 signal combiner at a power level of 14 kW.

Science.gov (United States)

Lei, Chengmin; Gu, Yanran; Chen, Zilun; Wang, Zengfeng; Zhou, Pu; Ma, Yanxing; Xiao, Hu; Leng, Jinyong; Wang, Xiaolin; Hou, Jing; Xu, Xiaojun; Chen, Jinbao; Liu, Zejin

2018-04-16

We demonstrate an all-fiber 7 × 1 signal combiner with an output core diameter of 50 μm for high power incoherent beam combining of seven self-made Yb-doped single-mode fiber lasers around a wavelength of 1080 nm and output power of 2 kW. 14.1 kW combined output power is achieved with a total transmission efficiency of higher than 98.5% and a beam quality of M 2 = 5.37, which is close to the theoretical results based on finite-difference beam propagation technique. To the best of our knowledge, this is the highest output power ever reported for all-fiber structure beam combining generation, which indicates the feasibility and potential of >10 kW high brightness incoherent beam combining based on an all-fiber signal combiner.

Physiological responses to indoor rock-climbing and their relationship to maximal cycle ergometry.

Science.gov (United States)

Sheel, A William; Seddon, Nicholas; Knight, Andrew; McKenzie, Donald C; R Warburton, Darren E

2003-07-01

To quantify the cardiorespiratory responses to indoor climbing during two increasingly difficult climbs and relate them to whole-body dynamic exercise. It was hypothesized that as climbing difficulty increased, oxygen consumption ([V02] and heart rate would increase, and that climbing would require utilization of a significant fraction of maximal cycling values. Elite competitive sport rock climbers (6 male, 3 female) completed two data collection sessions. The first session was completed at an indoor climbing facility, and the second session was an incremental cycle test to exhaustion. During indoor climbing subjects were randomly assigned to climb two routes designated as "harder" or "easier" based on their previous best climb. Subjects wore a portable metabolic system, which allowed measurement of oxygen consumption [V02], minute ventilation ([V02]E), respiratory exchange ratio (RER), and heart rate. During the second session, maximal values for [V02], [V02]E, RER, and heart rate were determined during an incremental cycle test to exhaustion. Heart rate and [VO2], expressed as percent of cycling maximum, were significantly higher during harder climbing compared with easier climbing. During harder climbing, %HR(max) was significantly higher than %[V02] (2max) (89.6% vs 51.2%), and during easier climbing, %HR(max) was significantly higher than %[V02] (2max) (66.9% vs 45.3%). With increasing levels of climbing difficulty, there is a rise in both heart rate and [V02]. However, there is a disproportional rise in heart rate compared with [V02], which we attribute to the fact that climbing requires the use of intermittent isometric contractions of the arm musculature and the reliance of both anaerobic and aerobic metabolism.

Reliable Stair Climbing in the Simple Hexapod 'RHex'

National Research Council Canada - National Science Library

Moore, E. Z; Campbell, D; Grimminger, F; Buehler, M

2002-01-01

.... In this paper, we describe an open loop controller that enables our small robot (Length: 51 cm, Width: 20 cm, Height: 12.7 cm. Leg length: 16 cm), to reliably climb a wide range of regular, full-size stairs with no operator input during stair climbing...

Dual fiber Bragg gratings configuration-based fiber acoustic sensor for low-frequency signal detection

Science.gov (United States)

Yang, Dong; Wang, Shun; Lu, Ping; Liu, Deming

2014-11-01

We propose and fabricate a new type fiber acoustic sensor based on dual fiber Bragg gratings (FBGs) configuration. The acoustic sensor head is constructed by putting the sensing cells enclosed in an aluminum cylinder space built by two Cband FBGs and a titanium diaphragm of 50 um thickness. One end of each FBG is longitudinally adhered to the diaphragm by UV glue. Both of the two FBGs are employed for reflecting light. The dual FBGs play roles not only as signal transmission system but also as sensing component, and they demodulate each other's optical signal mutually during the measurement. Both of the two FBGs are pre-strained and the output optical power experiences fluctuation in a linear relationship along with a variation of axial strain and surrounding acoustic interference. So a precise approach to measure the frequency and sound pressure of the acoustic disturbance is achieved. Experiments are performed and results show that a relatively flat frequency response in a range from 200 Hz to 1 kHz with the average signal-to-noise ratio (SNR) above 21 dB is obtained. The maximum sound pressure sensitivity of 11.35mV/Pa is achieved with the Rsquared value of 0.99131 when the sound pressure in the range of 87.7-106.6dB. It has potential applications in low frequency signal detection. Owing to its direct self-demodulation method, the sensing system reveals the advantages of easy to demodulate, good temperature stability and measurement reliability. Besides, performance of the proposed sensor could be improved by optimizing the parameters of the sensor, especially the diaphragm.

The evolution of vertical climbing in primates: evidence from reaction forces.

Science.gov (United States)

Hanna, Jandy B; Granatosky, Michael C; Rana, Pooja; Schmitt, Daniel

2017-09-01

Vertical climbing is an essential behavior for arboreal animals, yet limb mechanics during climbing are poorly understood and rarely compared with those observed during horizontal walking. Primates commonly engage in both arboreal walking and vertical climbing, and this makes them an ideal taxa in which to compare these locomotor forms. Additionally, primates exhibit unusual limb mechanics compared with most other quadrupeds, with weight distribution biased towards the hindlimbs, a pattern that is argued to have evolved in response to the challenges of arboreal walking. Here we test an alternative hypothesis that functional differentiation between the limbs evolved initially as a response to climbing. Eight primate species were recorded locomoting on instrumented vertical and horizontal simulated arboreal runways. Forces along the axis of, and normal to, the support were recorded. During walking, all primates displayed forelimbs that were net braking, and hindlimbs that were net propulsive. In contrast, both limbs served a propulsive role during climbing. In all species, except the lorisids, the hindlimbs produced greater propulsive forces than the forelimbs during climbing. During climbing, the hindlimbs tends to support compressive loads, while the forelimb forces tend to be primarily tensile. This functional disparity appears to be body-size dependent. The tensile loading of the forelimbs versus the compressive loading of the hindlimbs observed during climbing may have important evolutionary implications for primates, and it may be the case that hindlimb-biased weight support exhibited during quadrupedal walking in primates may be derived from their basal condition of climbing thin branches. © 2017. Published by The Company of Biologists Ltd.

Penyelesaian Masalah 8-Puzzle dengan Algoritma Steepest-Ascent Hill Climbing

Directory of Open Access Journals (Sweden)

David Abraham

2016-03-01

Full Text Available 8 puzzle merupakan salah satu implementasi dari Artificial Intelegence. Dalam proses penyelesaiannya banyak terdapat algoritma-algoritma pencarian yang dapat diterapkan. Solusi 8 puzzle akan lebih cepat diperoleh jika digunakan prinsip array dengan variasi algoritma Steepest-Ascent Hill Climbing (Hill Climbing dengan memilih kemiringan yang paling tajam / curam dengan parameter heuristik posisi yang benar dan heuristik jarak serta dikombinasikan dengan LogList sebagai penyimpanan state state yang pernah dilalui untuk menanggulangi permasalah pada algoritma hill climbing itu sendiri dan terhindar dari looping state yang pernah dilalui. Metode-metode yang termasuk ke dalam teknik pencarian yang berdasarkan pada fungsi heuristik salah satu diantaranya adalah Hill Climbing, Best First Search, A* (A Bintang. Loglist merupakan tempat penyimpanan setiap kunjungan dari state-state puzzle yang telah dilakukan untuk menghindari looping atau pengulangan terhadap state yang pernah dilalui. Untuk menanggulangi permasalahan pada SteepestAscent Hill Climbing.

Full-duplex radio-over-fiber system with tunable millimeter-wave signal generation and wavelength reuse for upstream signal.

Science.gov (United States)

Wang, Yiqun; Pei, Li; Li, Jing; Li, Yueqin

2017-06-10

A full-duplex radio-over-fiber system is proposed, which provides both the generation of a millimeter-wave (mm-wave) signal with tunable frequency multiplication factors (FMFs) and wavelength reuse for uplink data. A dual-driving Mach-Zehnder modulator and a phase modulator are cascaded to form an optical frequency comb. An acousto-optic tunable filter based on a uniform fiber Bragg grating (FBG-AOTF) is employed to select three target optical sidebands. Two symmetrical sidebands are chosen to generate mm waves with tunable FMFs up to 16, which can be adjusted by changing the frequency of the applied acoustic wave. The optical carrier is reused at the base station for uplink connection. FBG-AOTFs driven by two acoustic wave signals are experimentally fabricated and further applied in the proposed scheme. Results of the research indicate that the 2-Gbit/s data can be successfully transmitted over a 25-km single-mode fiber for bidirectional full-duplex channels with power penalty of less than 2.6 dB. The feasibility of the proposed scheme is verified by detailed simulations and partial experiments.

Research on feature extraction and classification of AE signals of fibers' tensile failure based on HHT and SVM

Directory of Open Access Journals (Sweden)

Yanding SHEN

2016-10-01

Full Text Available In order to study the feature extraction and recognition method of fibers' tensile failure, AE technology is used to collect AE signals of fiber bundle's tensile fracture of two kinds of fibers of Aramid 1313 and viscose. A transform called wavelet is used to deal with the signals to reduce noise. A method called Hilbert-Huang transform (HHT is used to extract characteristic frequencies of the signals after the noise is reduced. And a classification method called Least Squares support vector machines (LSSVM is used for the classification and recognition of characteristic frequencies of the two kinds of fibers. The results show that wavelet de-noise method can reduce some noise of the signals. Hilbert spectrum can reflect fracture circumstances of the two kinds of fibers in the time dimension to some extent. Characteristic frequencies' extraction can be done from marginal spectrum. The LSSVM can be used for the classification and recognition of characteristic frequencies. The recognition rates of Aramid 1313 and viscose reach 40%, 80% respectively, and the total recognition rate reaches 60%.

Simultaneous transmission of the IEEE 802.11 radio signal and optical Gbit Ethernet over the multimode fiber link

Science.gov (United States)

Maksymiuk, L.; Podziewski, A.

2015-09-01

In the paper we present a successful joint transmission of the IEEE 802.11 signal and an optical Gbit Ethernet over a multimode fiber based link. Most importantly, the multiplexation of both signals was performed in the optical domain. Due to the utilization of the multimode fiber the OBI noise was avoided and both channels were able to operate at the same wavelength. We prove that potential RoF link for IEEE 802.11 signal distribution may be used to additionally transmit other signals as Gbit Ethernet and therefore utilize the fiber infrastructure installed more effectively. The qualities of both the IEEE 802.11 and Ethernet transmissions fulfilled the requirements imposed by appropriate standards.

A Wheel-based Stair-climbing Robot with a Hopping Mechanism

OpenAIRE

Kikuchi, Koki; Bushida, Naoki; Sakaguchi, Keisuke; Chiba, Yasuhiro; Otsuka, Hiroshi; Saito, Yusuke; Hirano, Masamitsu; Kobayashi, Shunya

2010-01-01

We introduced a wheel-based stair-climbing robot with a hopping mechanism for stairclimbing. The robot, consisting of two body parts connected by springs, climbed stairs quickly, softly, and economically by using the vibration of a two-degrees-of-freedom system. In the future, we intend to shorten the required tread length by controlling the wire tension and minimizing the body length to realize a practical stair-climbing robot.

Research on Dynamics and Stability in the Stairs-Climbing of a Tracked Mobile Robot

Directory of Open Access Journals (Sweden)

Weijun Tao

2012-10-01

Full Text Available Aiming at the functional requirement of climbing up the stairs, the dynamics and stability during a tracked mobile robot's climbing of stairs is studied. First, from the analysis of its cross-country performance, the mechanical structure of the tracked mobile robot is designed and the hardware composition of its control system is given. Second, based on the analysis to its stairs-climbing process, the dynamical model of stairs-climbing is established by using the classical mechanics method. Next, the stability conditions for its stairs-climbing are determined and an evaluation method of its stairs-climbing stability is proposed, based on a mechanics analysis on the robot's backwards tumbling during the stairs-climbing process. Through simulation and experiments, the effectiveness of the dynamical model and the stability evaluation method of the tracked mobile robot in stairs-climbing is verified, which can provide design and analysis foundations for the tracked mobile robots' stairs-climbing.

A Kinect-sensor-based Tracked Robot for Exploring and Climbing Stairs

Directory of Open Access Journals (Sweden)

I-Hsum Li

2014-05-01

Full Text Available This paper focuses on the stair-climbing problem for a tracked robot. The tracked robot designed in this paper has the ability to explore stairs in an unknown indoor environment, climbing up and down the stairs, keeping balance while climbing, and successfully landing on the stair platform. Intelligent algorithms are proposed to explore and align stairs, and a fuzzy controller is introduced to stabilize the tracked robot's movement during the exploration. An inexpensive Kinect depth sensor is the only equipment needed for all the control modes. Finally, experiments illustrate the effectiveness of the proposed approach for climbing stairs.

Therapeutic use of sport climbing for patients with multiple sclerosis

Directory of Open Access Journals (Sweden)

Ana Ožura

2009-05-01

Full Text Available Sport climbing is a form of exercise that requires complex and variable movement. Because of the use of the so-called "top-rope system", this is a safe activity appropriate for individuals with physical disabilities. Therefore, climbing might prove to be an effective form of therapy for patients with multiple sclerosis. Multiple sclerosis is a chronic neurological disease that may include motor and cognitive deficits as well as affective disturbances. The illness is characterized by multifocal areas of brain damage (plaques, as consequence of autoimmune inflammation. Sport climbing might be a potentially useful activity for treating spasticity, improving a person's self image and certain aspects of cognition, such as attention and executive functions, as well as for managing emotional disturbances. All of the above are areas where patients with multiple sclerosis might be in need of assistance. The article also describes the experience of a patient with multiple sclerosis who was enrolled in our climbing program. Future research is needed to evaluate the effect of climbing therapy for patients with multiple sclerosis.

Finding paradise: cues directing the migration of the waterfall climbing Hawaiian gobioid Sicyopterus stimpsoni.

Science.gov (United States)

Leonard, G; Maie, T; Moody, K N; Schrank, G D; Blob, R W; Schoenfuss, H L

2012-07-01

A series of waterfall-climbing trials were conducted to identify cues that direct the climbing of juvenile Sicyopterus stimpsoni. In the first experiment, whether climbing juveniles preferentially ascend water sources with conspecifics or whether the presence of just stream water is sufficient to attract fish to ascend a climbing path were assessed. In the second experiment, whether climbing juveniles create a trail of mucus that facilitates the ability of conspecifics to follow their lead was determined. The results indicate that juvenile S. stimpsoni are less likely to climb in waters devoid of organic cues but are strongly attracted to stream water with or without the odour of conspecifics. Once climbing, performance did not differ for juveniles climbing in differing water choices, suggesting an all-or-nothing commitment once climbing commences. Climbing S. stimpsoni did produce a mucous trail while climbing that was associated with a mucous gland that dramatically increases in size just prior to juveniles gaining the ability to climb. The trail was not followed closely by subsequent juveniles traversing the same channel, however, suggesting only weak trail-following in waterfall climbing S. stimpsoni. Previous genetic studies suggest that juvenile S. stimpsoni do not home to natal streams in the face of strong near-shore oceanic currents. Instead, these fish appear primarily to rely on cues that suggest the presence of organic growth in streams, a factor that may indicate suitable habitat in an ever-changing stream environment but which may also be vulnerable to interference through human activity. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Signal Processing using Nonlinear Optical Eects in Single- and Few-Mode Fibers

DEFF Research Database (Denmark)

Friis, Søren Michael Mørk

noise, loss, and pump depletion on the noise properties of parametric frequency conversion and phase-insensitive and phase-sensitive parametric amplification. An important part of realizing space-division multiplexing is the ability of optical signal processing so the second part of this thesis......-wave mixing in two-mode fibers acvi counting for six simultaneous processes is derived, and the conversion efficiency from signal to idler in the four-wave mixing processes of phase conjugation and Bragg scattering in two two-mode fibers with different phase matching properties are experimentally investigated......The stagnating increase in data transmission capacity in optical communication systems combined with the ever growing demand of transmission bandwidth is leading to an impending capacity crunch, referring to the point in time after which the available bandwidth of the individual user starts...

Analog signals transmission of up to 100 khz though optical fiber

International Nuclear Information System (INIS)

Cremy, C.

1996-12-01

Around TJ-II device, potential problems may arise as a consequence of an adverse electromagnetic environment, presence of strong DC and AC currents, motors, coils, power supplies, magnetic fields and so on. Consequently, signal transmission towards monitoring or data acquisition systems may be affected due to induced noise, ground loops and other undesirable effects. Trying to avoid such problems, signals may be translated in a proper way in order to be routed through optical fiber. The present report shows a method to solve the difficulty, by means of a galvanic isolation between the signal source and the measurement circuit. (Author)

Human muscle fiber type-specific insulin signaling: Impact of obesity and type 2 diabetes

DEFF Research Database (Denmark)

Albers, Peter Hjorth; Pedersen, Andreas J T; Birk, Jesper Bratz

2015-01-01

Skeletal muscle is a heterogeneous tissue composed of different fiber types. Studies suggest that insulin-mediated glucose metabolism is different between muscle fiber types. We hypothesized that differences are due to fiber-type specific expression/regulation of insulin signaling elements and....../or metabolic enzymes. Pools of type I and II fibers were prepared from biopsies of the vastus lateralis muscles from lean, obese and type 2 diabetic subjects before and after a hyperinsulinemic-euglycemic clamp. Type I fibers compared to type II fibers have higher protein levels of the insulin receptor, GLUT4......, hexokinase II, glycogen synthase (GS), pyruvate dehydrogenase (PDH-E1α) and a lower protein content of Akt2, TBC1D4 and TBC1D1. In type I fibers compared to type II fibers, the phosphorylation-response to insulin was similar (TBC1D4, TBC1D1 and GS) or decreased (Akt and PDH-E1α). Phosphorylation...

Optical phase-modulated radio-over-fiber links with k-means algorithm for digital demodulation of 8PSK subcarrier multiplexed signals

DEFF Research Database (Denmark)

Guerrero Gonzalez, Neil; Zibar, Darko; Yu, Xianbin

2010-01-01

A k-means algorithm for phase recovery of three, 50 Mbaud, 8PSK subcarrier multiplexed signals at 5 GHz for optical phase-modulated radio-over-fiber is proposed and experimentally demonstrated after 40 km of single mode fiber transmission......A k-means algorithm for phase recovery of three, 50 Mbaud, 8PSK subcarrier multiplexed signals at 5 GHz for optical phase-modulated radio-over-fiber is proposed and experimentally demonstrated after 40 km of single mode fiber transmission...

Pregnant Women in Sport Climbing - Is there a Higher Risk for Preterm Birth?

Science.gov (United States)

Drastig, Jan; Hillebrandt, David; Rath, Werner; Küpper, Thomas

2017-02-01

Sport climbing is a popular recreational sport with an increasing proportion of female athletes. International recommendations emphasize the physical and mental benefits of regular sport activity during any uncomplicated pregnancy. In this context, sport climbing is associated with a high risk potential.The aim of this study was to examine if there is a higher risk for preterm birth in active climbing athletes.Original manuscript.A retrospective self-report online survey in the German language collected data between September 2012 and November 2013. In addition to anthropometric and demographic data, data on climbing experience, preferred climbing discipline, skill level and changes of climbing habits during pregnancy, known risk factors for preterm birth and information on delivery and the newborn were requested. The rate of preterm birth of the survey was tested with Fisher's exact test with information from the German Federal Statistical Office.Sample size was 32. 72% had a university degree, 81% were primiparous, all were singleton pregnancies. A 33 rd questionnaire was excluded because of described preeclampsia. Age ranged between 21 and 39 years, climbing experience before pregnancy between 2 and 24 years, and skill level before pregnancy between 4 and 7 on the UIAA scale (International Climbing and Mountaineering Federation). Half of the women climbed until the 36 th week and 90% adjusted their climbing habits mostly by reducing climbing difficulty and doing more top roping. 2 preterm births in the 36 th week of gestation were found (2 from 15, p=0.36). According to the data from the German Federal Statistical Office, 8.9% births in the year 2013 in Germany were preterm.This is the first study investigating the risk of preterm birth in recreational sport climbing athletes. No significantly higher proportion of preterm birth could be found. Limitations are small sample size and high social status of participants. What is known about the subject: Sport

A cerebellar learning model of vestibulo-ocular reflex adaptation in wild-type and mutant mice

NARCIS (Netherlands)

Clopath, Claudia; Badura, Aleksandra; De Zeeuw, Chris I; Brunel, Nicolas

2014-01-01

Mechanisms of cerebellar motor learning are still poorly understood. The standard Marr-Albus-Ito theory posits that learning involves plasticity at the parallel fiber to Purkinje cell synapses under control of the climbing fiber input, which provides an error signal as in classical supervised

The Mechanical Properties of a Wall-Climbing Caterpillar Robot: Analysis and Experiment

Directory of Open Access Journals (Sweden)

Kun Wang

2013-01-01

Full Text Available This paper builds the kinematic model of a wall-climbing caterpillar robot to reveal the validity and the benefits of the closed-chain kinematics of the four-linkage mechanism to a crawling gait. The caterpillar robot can climb on a vertical wall by coordinating the rotations of one active joint and three passive joints. The mechanical property of the closed-chain kinematics of the four-linkage model is analysed. Furthermore, the relation between the driving joint torque and joint angle in the wall-climbing process is deduced based on the coplanar arbitrary force system. Afterwards, the joint control method is discussed in order to coordinate the rotation of the four joints so as to realize a reasonable wall climbing gait. To testify to the availability of the closed-chain four-linkage model, a wall-climbing caterpillar robot is developed with three different adhesion modules based on the vibrating suction method. A successful wall-climbing test confirms both the practicality of the four-linkage model and the validity of the adhesion modules based on the vibrating suction method. The results also show the reasonableness of the driving joint selection rule for ensuring a safe and reliable wall-climbing procedure.

Forest climbing plants of West Africa: diversity, ecology and management

NARCIS (Netherlands)

Bongers, F.J.J.M.; Parren, M.P.E.; Traoré, D.

2005-01-01

Climbing plants, including lianas, represent a fascinating component of the ecology of tropical forests. This book focuses on the climbing plants of West African forests. Based on original research, it presents information on the flora (including a checklist), diversity (with overviews at several

High-speed ultra-wideband wireless signals over fiber systems: photonic generation and DSP detection

DEFF Research Database (Denmark)

Yu, Xianbin; Gibbon, Timothy Braidwood; Tafur Monroy, Idelfonso

2009-01-01

We firstly review the efforts in the literature on ultra-wideband (UWB)-over-fiber systems. Secondly, we present experimental results on photonic generation of high-speed UWB signals by both direct modulation and external optical injecting an uncooled semiconductor laser. Furthermore, we introduce...... the use of digital signal processing (DSP) technology to receive the generated UWB signal at 781.25 Mbit/s. Error-free transmission is achieved....

Research on a Micro Flip Robot That Can Climb Stairs

Directory of Open Access Journals (Sweden)

Jianzhong Wang

2016-03-01

Full Text Available Micro mobile robots (MMRs can operate in rugged, narrow or dangerous regions; thus, they are widely used in numerous areas including surveillance, rescue and exploration. In urban environments, stairs are common obstacles, ones that such robots find difficult to manoeuvre over. The authors analysed the research status of MMRs, particularly in terms of difficulties when performing stair climbing and present a novel type of MMR called the micro flip robot (MFRobot. A support arm subassembly was added to the centre of a wheeled chassis; using this structure, the MFRobot can climb stairs when a flipping mode is utilized. Based on this structure, the authors established a kinematic model of the stair-climbing process and analysed the force conditions for the key status, contributing to the existing knowledge of robot design. An MFRobot prototype was produced and the stair-climbing experiments, as well as experiments on manoeuvring through rubble regions and slope surfaces, were conducted. The results show that the MFRobot can rapidly climb common stairs and can easily manoeuvre through a rubble region. The maximum slope angle the robot can climb was shown to be about 35° for concrete and wooden slope surfaces. In the case where the robot needed to be equipped with sensors, particularly a camera, the camera was equipped on the support arm of robot. The MFRobot prototype weighs 2.5 kg and is easily transportable. This structure can resolve contradictions between portability and performance in terms of overcoming obstacles; in addition, operational effectiveness can be improved using this structure.

A Kinect-sensor-based Tracked Robot for Exploring and Climbing Stairs

OpenAIRE

I-Hsum Li; Wei-Yen Wang; Chien-Kai Tseng

2014-01-01

This paper focuses on the stair-climbing problem for a tracked robot. The tracked robot designed in this paper has the ability to explore stairs in an unknown indoor environment, climbing up and down the stairs, keeping balance while climbing, and successfully landing on the stair platform. Intelligent algorithms are proposed to explore and align stairs, and a fuzzy controller is introduced to stabilize the tracked robot's movement during the exploration. An inexpensive Kinect depth sensor is...

Amplification of the Signal Intensity of Fluorescence-Based Fiber-Optic Biosensors Using a Fabry-Perot Resonator Structure

Directory of Open Access Journals (Sweden)

Meng-Chang Hsieh

2015-02-01

Full Text Available Fluorescent biosensors have been widely used in biomedical applications. To amplify the intensity of fluorescence signals, this study developed a novel structure for an evanescent wave fiber-optic biosensor by using a Fabry-Perot resonator structure. An excitation light was coupled into the optical fiber through a laser-drilled hole on the proximal end of the resonator. After entering the resonator, the excitation light was reflected back and forth inside the resonator, thereby amplifying the intensity of the light in the fiber. Subsequently, the light was used to excite the fluorescent molecules in the reactive region of the sensor. The experimental results showed that the biosensor signal was amplified eight-fold when the resonator reflector was formed using a 92% reflective coating. Furthermore, in a simulation, the biosensor signal could be amplified 20-fold by using a 99% reflector.

The acute toxicity of the metaldehyde on the climbing perch

Science.gov (United States)

Wahida Mohamad Ismail, Syamimi; Aini Dahalan, Farrah; Zakaria, Ammar; Mad Shakaff, Ali Yeon; Aqlima Ahmad, Siti; Shukor, Mohd Yunus Abd; Khalizan Sabullah, Mohd; Khalil, Khalilah Abdul; Jalil, Mohd Faizal Ab

2018-03-01

In Asia, Climbing perch (Anabas testudineus) is commonly found in paddy fields and irrigation systems. Due to its habitat, Climbing perch is exposed to toxic pesticides used in paddy fields such as metaldehyde which is one of the most widely used molluscicide. This study aims to determine the acute toxicity Lethal Concentration50 (LC50) of metaldehyde and its effect on the behaviour and physical changes of the Climbing perch. The fish mortality responses to six different metaldehyde concentrations ranging from 180 to 330 mg/L were investigated. The 96-h LC50 values were determined and analysed using three different analysis methods which is arithmetic, logarithmic and probit graphic. The LC50 values obtained in this study were 239, 234 and 232 mg/L, respectively. After 96-h of exposure to metaldehyde, the fish showed a series of abnormal behavioural response in all cases: imbalance position, and restlessness of movement. The LC50 values show that metaldehyde is moderately toxic to the Climbing perch indicating that metaldehyde is not destructive to Climbing perch. However, long term exposure of aquatic organisms to the metaldehyde means a continuous health risk for the fish population as they are more vulnerable and it is on high risk for human to consume this toxicated fishes.

Enhancing the Trajectory Generation of a Stair-Climbing Mobility System

Science.gov (United States)

Chocoteco, Jose Abel

2017-01-01

Recent advances in mobile robotic technologies have enabled significant progress to be made in the development of Stair-Climbing Mobility Systems (SCMSs) for people with mobility impairments and limitations. These devices are mainly characterized by their ability to negotiate those architectural barriers associated with climbing stairs (curbs, ramps, etc.). The development of advanced trajectory generators with which to surpass such architectural barriers is one of the most important aspects of SCMSs that has not yet been appropriately exploited. These advanced trajectory generators have a considerable influence on the time invested in the stair climbing process and on passenger comfort and, consequently, provide people with physical disabilities with greater independence and a higher quality of life. In this paper, we propose a new nonlinear trajectory generator for an SCMS. This generator balances the stair-climbing time and the user’s comfort and includes the most important constraints inherent to the system behavior: the geometry of the architectural barrier, the reconfigurable nature of the SCMS (discontinuous states), SCMS state-transition diagrams, comfort restrictions and physical limitations as regards the actuators, speed and acceleration. The SCMS was tested on a real two-step staircase using different time-comfort combinations and different climbing strategies to verify the effectiveness and the robustness of the proposed approach.

Performance and scaling of a novel locomotor structure: adhesive capacity of climbing gobiid fishes.

Science.gov (United States)

Maie, Takashi; Schoenfuss, Heiko L; Blob, Richard W

2012-11-15

Many species of gobiid fishes adhere to surfaces using a sucker formed from fusion of the pelvic fins. Juveniles of many amphidromous species use this pelvic sucker to scale waterfalls during migrations to upstream habitats after an oceanic larval phase. However, adults may still use suckers to re-scale waterfalls if displaced. If attachment force is proportional to sucker area and if growth of the sucker is isometric, then increases in the forces that climbing fish must resist might outpace adhesive capacity, causing climbing performance to decline through ontogeny. To test for such trends, we measured pressure differentials and adhesive suction forces generated by the pelvic sucker across wide size ranges in six goby species, including climbing and non-climbing taxa. Suction was achieved via two distinct growth strategies: (1) small suckers with isometric (or negatively allometric) scaling among climbing gobies and (2) large suckers with positively allometric growth in non-climbing gobies. Species using the first strategy show a high baseline of adhesive capacity that may aid climbing performance throughout ontogeny, with pressure differentials and suction forces much greater than expected if adhesion were a passive function of sucker area. In contrast, large suckers possessed by non-climbing species may help compensate for reduced pressure differentials, thereby producing suction sufficient to support body weight. Climbing Sicyopterus species also use oral suckers during climbing waterfalls, and these exhibited scaling patterns similar to those for pelvic suckers. However, oral suction force was considerably lower than that for pelvic suckers, reducing the ability for these fish to attach to substrates by the oral sucker alone.

Application of a fiber Fabry-Perot interferometer sensor for receiving SH-EMAT signals

Energy Technology Data Exchange (ETDEWEB)

Lee, Jin Hyuk; Kim, Dae Hyun; Park, Ik Keun [Seoul National University of Technology, Seoul (Korea, Republic of)

2014-04-15

Shear horizontal (SH) waves propagate as a type of plate wave in a thin sheet. The dispersion characteristics of SH waves can be used for signal analysis. Therefore, SH-waves are useful for monitoring the structural health of a thin-sheet-structure. An electromagnetic acoustic transducer (EMAT), which is a non-contact ultrasonic transducer, can generate SH-waves easily by varying the shape and array of magnets and coils. Therefore, an EMAT can be applied to an automated ultrasonic testing system for structural health monitoring. When used as a sensor, however, the EMAT has a weakness in that electromagnetic interference (EMI) noise can occur easily in the automated system because of motors and electric devices. Alternatively, a fiber optic sensor works well in the same environment with EMI noise because it uses a light signal instead of an electric signal. In this paper, a fiber Fabry-Prot interferometer (FFPI) was proposed as a sensor to receive the SH-waves generated by an EMAT. A simple test was performed to verify the performance of the FFPI sensor. It is thus shown that the FFPI can receive SH-wave signals clearly.

Valgus-varus motion of the knee in normal level walking and stair climbing.

Science.gov (United States)

Yu, B; Stuart, M J; Kienbacher, T; Growney, E S; An, K-N

1997-07-01

OBJECTIVE: The knee valgus-varus moment and the knee angles were compared between normal level walking and stair climbing. DESIGN: Ten healthy subjects were tested for ascent, descent, and level walking. BACKGROUND: An understanding of the normal valgus-varus motion of the knee during stair climbing is needed to apply biomechanical analysis of stair climbing as a evaluation tool for knee osteoarthritis patients. METHODS: A motion analysis system, three force plates, and a flight of stairs were used to collect kinematic and kinetic data. The knee angles and moments were calculated from the collected kinematic and kinetic data. RESULTS: The knee varus angle for the maximum knee valgus moments in stair climbing was significantly greater than that in level walking. The knee valgus moment was significantly correlated to ground reaction forces and knee valgus-varus angle during stair climbing and level walking. CONCLUSIONS: There is a coupling between the knee valgus-varus motion and flexion-extension motion. Ground reaction forces are the major contributors to the within-subject variation in the knee valgus-varus moment during stair climbing and level walking. The knee valgus-varus angle is a major contributor to the between-subject variation in the knee valgus moment during stair climbing and level walking.

The climb of dissociated dislocations in a quenched Cu-13.43 at.% Al alloy

International Nuclear Information System (INIS)

Decamps, B.; Cherns, D.; Condat, M.

1983-01-01

The weak-beam electron microscopy technique has been used to study the climb of dissociated dislocations in a Cu-13.43 at.% Al alloy under conditions of supersaturation of vacancies introduced by quenching. The results are similar to those obtained under electron irradiation (interstitial climb) in the same alloy (Cherns, Hirsch and Saka 1980) in that climb may proceed by the nucleation of prismatic loops on the individual partials. The nature of the loops is such as to minimize the total energy of the configuration (partial plus loop) and to maximize their edge component. Interaction with the other partial has been observed, causing the entire dislocation to climb. Additional features observed suggest that climb under quenching is initiated by the nucleation of Frank loops. The detailed configurations also enable climb by absorption of vacancies and interstitials to be distinguished. (author)

Amount of balance necessary for the independence of transfer and stair-climbing in stroke inpatients.

Science.gov (United States)

Fujita, Takaaki; Sato, Atsushi; Ohashi, Yuji; Nishiyama, Kazutaka; Ohashi, Takuro; Yamane, Kazuhiro; Yamamoto, Yuichi; Tsuchiya, Kenji; Otsuki, Koji; Tozato, Fusae

2018-05-01

The purpose of this study was to clarify the amount of balance necessary for the independence of transfer and stair-climbing in stroke patients. This study included 111 stroke inpatients. Simple and multiple regression analyses were conducted to establish the association between the FIM ® instrument scores for transfer or stair-climbing and Berg Balance Scale. Furthermore, receiver operating characteristic curves were used to elucidate the amount of balance necessary for the independence of transfer and stair-climbing. Simple and multiple regression analyses showed that the FIM ® instrument scores for transfer and stair-climbing were strongly associated with Berg Balance Scale. On comparison of the independent and supervision-dependent groups, Berg Balance Scale cut-off values for transfer and stair-climbing were 41/40 and 54/53 points, respectively. On comparison of the independent-supervision and dependent groups, the cut-off values for transfer and stair-climbing were 30/29 and 41/40 points, respectively. The calculated cut-off values indicated the amount of balance necessary for the independence of transfer and stair-climbing, with and without supervision, in stroke patients. Berg Balance Scale has a good discriminatory ability and cut-off values are clinically useful to determine the appropriate independence levels of transfer and stair-climbing in hospital wards. Implications for rehabilitation The Berg Balance Scale's (BBS) strong association with transfer and stair-climbing independence and performance indicates that establishing cut-off values is vitally important for the established use of the BBS clinically. The cut-off values calculated herein accurately demonstrate the level of balance necessary for transfer and stair-climbing independence, with and without supervision, in stroke patients. These criteria should be employed clinically for determining the level of independence for transfer and stair-climbing as well as for setting balance training

Tunable microwave signal generation based on an Opto-DMD processor and a photonic crystal fiber

International Nuclear Information System (INIS)

Wang Tao; Sang Xin-Zhu; Yan Bin-Bin; Li Yan; Song Fei-Jun; Zhang Xia; Wang Kui-Ru; Yuan Jin-Hui; Yu Chong-Xiu; Ai Qi; Chen Xiao; Zhang Ying; Chen Gen-Xiang; Xiao Feng; Kamal Alameh

2014-01-01

Frequency-tunable microwave signal generation is proposed and experimentally demonstrated with a dual-wavelength single-longitudinal-mode (SLM) erbium-doped fiber ring laser based on a digital Opto-DMD processor and four-wave mixing (FWM) in a high-nonlinear photonic crystal fiber (PCF). The high-nonlinear PCF is employed for the generation of the FWM to obtain stable and uniform dual-wavelength oscillation. Two different short passive sub-ring cavities in the main ring cavity serve as mode filters to make SLM lasing. The two lasing wavelengths are electronically selected by loading different gratings on the Opto-DMD processor controlled with a computer. The wavelength spacing can be smartly adjusted from 0.165 nm to 1.08 nm within a tuning accuracy of 0.055 nm. Two microwave signals at 17.23 GHz and 27.47 GHz are achieved. The stability of the microwave signal is discussed. The system has the ability to generate a 137.36-GHz photonic millimeter signal at room temperature

Fiber nonlinearity mitigation of WDM-PDM QPSK/16-QAM signals using fiber-optic parametric amplifiers based multiple optical phase conjugations

DEFF Research Database (Denmark)

Hu, Hao; Jopson, Robert M.; Gnauck, Alan H.

2017-01-01

We demonstrate fiber nonlinearity mitigation by using multiple optical phase conjugations (OPCs) in the WDM transmission systems of both 8 x 32-Gbaud PDM QPSK channels and 8 x 32-Gbaud PDM 16-QAM channels, showing improved performance over a single mid-span OPC and no OPC in terms of nonlinear...... threshold and a best achievable Q(2) factor after transmission. In addition, after an even number of OPCs, the signal wavelength can be preserved after transmission. The performance of multiple OPCs for fiber nonlinearity mitigation was evaluated independently for WDM PDM QPSK signals and WDM PDM 16QAM...... to 1 dB compared to the case of mid-span OPC. The improvements in the best achievable Q(2) factors were more modest, ranging from 0.2 dB to 1.1 dB for the results presented. (C) 2017 Optical Society of America...

Beneficial aerodynamic effect of wing scales on the climbing flight of butterflies.

Science.gov (United States)

Slegers, Nathan; Heilman, Michael; Cranford, Jacob; Lang, Amy; Yoder, John; Habegger, Maria Laura

2017-01-30

It is hypothesized that butterfly wing scale geometry and surface patterning may function to improve aerodynamic efficiency. In order to investigate this hypothesis, a method to measure butterfly flapping kinematics optically over long uninhibited flapping sequences was developed. Statistical results for the climbing flight flapping kinematics of 11 butterflies, based on a total of 236 individual flights, both with and without their wing scales, are presented. Results show, that for each of the 11 butterflies, the mean climbing efficiency decreased after scales were removed. Data was reduced to a single set of differences of climbing efficiency using are paired t-test. Results show a mean decrease in climbing efficiency of 32.2% occurred with a 95% confidence interval of 45.6%-18.8%. Similar analysis showed that the flapping amplitude decreased by 7% while the flapping frequency did not show a significant difference. Results provide strong evidence that butterfly wing scale geometry and surface patterning improve butterfly climbing efficiency. The authors hypothesize that the wing scale's effect in measured climbing efficiency may be due to an improved aerodynamic efficiency of the butterfly and could similarly be used on flapping wing micro air vehicles to potentially achieve similar gains in efficiency.

Intelligent Network Management and Functional Cerebellum Synthesis

Science.gov (United States)

Loebner, Egon E.

1989-01-01

Transdisciplinary modeling of the cerebellum across histology, physiology, and network engineering provides preliminary results at three organization levels: input/output links to central nervous system networks; links between the six neuron populations in the cerebellum; and computation among the neurons of the populations. Older models probably underestimated the importance and role of climbing fiber input which seems to supply write as well as read signals, not just to Purkinje but also to basket and stellate neurons. The well-known mossy fiber-granule cell-Golgi cell system should also respond to inputs originating from climbing fibers. Corticonuclear microcomplexing might be aided by stellate and basket computation and associate processing. Technological and scientific implications of the proposed cerebellum model are discussed.

Broadband true time delay for microwave signal processing, using slow light based on stimulated Brillouin scattering in optical fibers.

Science.gov (United States)

Chin, Sanghoon; Thévenaz, Luc; Sancho, Juan; Sales, Salvador; Capmany, José; Berger, Perrine; Bourderionnet, Jérôme; Dolfi, Daniel

2010-10-11

We experimentally demonstrate a novel technique to process broadband microwave signals, using all-optically tunable true time delay in optical fibers. The configuration to achieve true time delay basically consists of two main stages: photonic RF phase shifter and slow light, based on stimulated Brillouin scattering in fibers. Dispersion properties of fibers are controlled, separately at optical carrier frequency and in the vicinity of microwave signal bandwidth. This way time delay induced within the signal bandwidth can be manipulated to correctly act as true time delay with a proper phase compensation introduced to the optical carrier. We completely analyzed the generated true time delay as a promising solution to feed phased array antenna for radar systems and to develop dynamically reconfigurable microwave photonic filters.

Research on Dynamics and Stability in the Stairs-climbing of a Tracked Mobile Robot

OpenAIRE

Tao, Weijun; Ou, Yi; Feng, Hutian

2012-01-01

Aiming at the functional requirement of climbing up the stairs, the dynamics and stability during a tracked mobile robot's climbing of stairs is studied. First, from the analysis of its cross-country performance, the mechanical structure of the tracked mobile robot is designed and the hardware composition of its control system is given. Second, based on the analysis to its stairs-climbing process, the dynamical model of stairs-climbing is established by using the classical mechanics method. N...

Hybrid CATV/MMW/BB lightwave transmission system based on fiber-wired/fiber-wireless/fiber-VLLC integrations.

Science.gov (United States)

Li, Chung-Yi; Lu, Hai-Han; Lu, Ting-Chieh; Chu, Chien-An; Chen, Bo-Rui; Lin, Chun-Yu; Peng, Peng-Chun

2015-12-14

A hybrid lightwave transmission system for cable television (CATV)/millimeter-wave (MMW)/baseband (BB) signal transmission based on fiber-wired/fiber-wireless/fiber-visible laser light communication (VLLC) integrations is proposed and demonstrated. For down-link transmission, the light is intensity-modulated with 50-550 MHz CATV signal and optically promoted from 25 GHz radio frequency (RF) signal to 10 Gbps/50 GHz and 20 Gbps/100 GHz MMW data signals based on fiber-wired and fiber-wireless integrations. Good performances of carrier-to-noise ratio (CNR), composite second-order (CSO), composite triple-beat (CTB), and bit error rate (BER) are obtained over a 40-km single-mode fiber (SMF) and a 10-m RF wireless transport. For up-link transmission, the light is successfully intensity-remodulated with 5-Gbps BB data stream based on fiber-VLLC integration. Good BER performance is achieved over a 40-km SMF and a 10-m free-space VLLC transport. Such a hybrid CATV/MMW/BB lightwave transmission system is an attractive alternative, it gives the benefits of a communication link for broader bandwidth and higher transmission rate.

Global diversification of a tropical plant growth form: environmental correlates and historical contingencies in climbing palms.

Science.gov (United States)

Couvreur, Thomas L P; Kissling, W Daniel; Condamine, Fabien L; Svenning, Jens-Christian; Rowe, Nick P; Baker, William J

2014-01-01

Tropical rain forests (TRF) are the most diverse terrestrial biome on Earth, but the diversification dynamics of their constituent growth forms remain largely unexplored. Climbing plants contribute significantly to species diversity and ecosystem processes in TRF. We investigate the broad-scale patterns and drivers of species richness as well as the diversification history of climbing and non-climbing palms (Arecaceae). We quantify to what extent macroecological diversity patterns are related to contemporary climate, forest canopy height, and paleoclimatic changes. We test whether diversification rates are higher for climbing than non-climbing palms and estimate the origin of the climbing habit. Climbers account for 22% of global palm species diversity, mostly concentrated in Southeast Asia. Global variation in climbing palm species richness can be partly explained by past and present-day climate and rain forest canopy height, but regional differences in residual species richness after accounting for current and past differences in environment suggest a strong role of historical contingencies in climbing palm diversification. Climbing palms show a higher net diversification rate than non-climbers. Diversification analyses of palms detected a diversification rate increase along the branches leading to the most species-rich clade of climbers. Ancestral character reconstructions revealed that the climbing habit originated between early Eocene and Miocene. These results imply that changes from non-climbing to climbing habits may have played an important role in palm diversification, resulting in the origin of one fifth of all palm species. We suggest that, in addition to current climate and paleoclimatic changes after the late Neogene, present-day diversity of climbing palms can be explained by morpho-anatomical innovations, the biogeographic history of Southeast Asia, and/or ecological opportunities due to the diversification of high-stature dipterocarps in Asian TRFs.

Realization of rapid debugging for detection circuit of optical fiber gas sensor: Using an analog signal source

Science.gov (United States)

Tian, Changbin; Chang, Jun; Wang, Qiang; Wei, Wei; Zhu, Cunguang

2015-03-01

An optical fiber gas sensor mainly consists of two parts: optical part and detection circuit. In the debugging for the detection circuit, the optical part usually serves as a signal source. However, in the debugging condition, the optical part can be easily influenced by many factors, such as the fluctuation of ambient temperature or driving current resulting in instability of the wavelength and intensity for the laser; for dual-beam sensor, the different bends and stresses of the optical fiber will lead to the fluctuation of the intensity and phase; the intensity noise from the collimator, coupler, and other optical devices in the system will also result in the impurity of the optical part based signal source. In order to dramatically improve the debugging efficiency of the detection circuit and shorten the period of research and development, this paper describes an analog signal source, consisting of a single chip microcomputer (SCM), an amplifier circuit, and a voltage-to-current conversion circuit. It can be used to realize the rapid debugging detection circuit of the optical fiber gas sensor instead of optical part based signal source. This analog signal source performs well with many other advantages, such as the simple operation, small size, and light weight.

Mechanical Design and Dynamcis of an Autonomous Climbing Robot for Elliptic Half-shell Cleaning

Directory of Open Access Journals (Sweden)

Houxiang Zhang

2007-12-01

Full Text Available This paper presents an auto-climbing robot for cleaning the elliptic half-shell of National Grand Theatre in China. The robot consists of a climbing mechanism, a moving mechanism, two cleaning brushes and supporting mechanisms. The mechanism and unique aspects are presented in detail. A distributed control system based on CAN bus is designed to meet the requirements of controlling the robot. After that the emphasis for discussion is on the motion realization which includes climbing and cleaning movements. The robot independently climbs and descends in the vertical direction and cleans in the horizontal direction. It takes the circling tracks as supports for climbing up and down between strips and moving horizontally along one strip around the ellipsoid. For system design and control purposes, the dynamic models of the climbing and cleaning processes are given applying of the Lagrange equation. Furthermore the force distribution of the front and rear supporting mechanisms is computed in a way that ensures the safety of the climbing process. In the end, the successful on-site tests confirm the principles described above and the robot's ability.

Mechanical Design and Dynamcis of an Autonomous Climbing Robot for Elliptic Half-shell Cleaning

Directory of Open Access Journals (Sweden)

Houxiang Zhang

2008-11-01

Full Text Available This paper presents an auto-climbing robot for cleaning the elliptic half-shell of National Grand Theatre in China. The robot consists of a climbing mechanism, a moving mechanism, two cleaning brushes and supporting mechanisms. The mechanism and unique aspects are presented in detail. A distributed control system based on CAN bus is designed to meet the requirements of controlling the robot. After that the emphasis for discussion is on the motion realization which includes climbing and cleaning movements. The robot independently climbs and descends in the vertical direction and cleans in the horizontal direction. It takes the circling tracks as supports for climbing up and down between strips and moving horizontally along one strip around the ellipsoid. For system design and control purposes, the dynamic models of the climbing and cleaning processes are given applying of the Lagrange equation. Furthermore the force distribution of the front and rear supporting mechanisms is computed in a way that ensures the safety of the climbing process. In the end, the successful on-site tests confirm the principles described above and the robot's ability.

A Fuzzy Control Based Stair-Climbing Service Robot

OpenAIRE

Wang, Ming-Shyan

2010-01-01

In the chapter, we have developed a stair-climbing robot to provide service for the elders and completed two walking experiments of moving up and down stairs with the rise/depth of 120/400 mm and 175/280 mm. The third experiment of object tracking, capturing, and loading by the arm have been shown in the taped pictures from videos to verify the proposed design. In fact, we will show the arm may capture the specific object during climbing up and down in the future. In addition, the robot will ...

FEEDING ECOLOGY OF TREE-CLIMBING MANGROVE SESARMID CRABS FROM LUZON, PHILIPPINES

Directory of Open Access Journals (Sweden)

JIMMY TEVAR MASAGCA

2009-01-01

Full Text Available Despite the large ecological study of tree-climbing mangrove sesarmid crabs in other countries, the Philippine representatives appear to have not been investigated extensively. This paper presents the feeding ecology as to dependence on mangrove trees of sesarmids in different mangrove areas of southern Luzon. This is biased on the nature of the crab habitats, arboreal climbing skills and burrowing behavior of the sesarmids: Selatium elongatum and Episesarma versicolor − exclusive mangrove tree climbers (EMTC; Sarmatium germaini − occasional mangrove tree climber (OMTC; and the non-mangrove tree-climbing (NMTC sesarmids- Neosarmatium smithii, Perisesarma bidens and Perisesarma eumolpe

Criterion-related validity of self-reported stair climbing in older adults.

Science.gov (United States)

Higueras-Fresnillo, Sara; Esteban-Cornejo, Irene; Gasque, Pablo; Veiga, Oscar L; Martinez-Gomez, David

2018-02-01

Stair climbing is an activity of daily living that might contribute to increase levels of physical activity (PA). To date, there is no study examining the validity of climbing stairs assessed by self-report. The aim of this study was, therefore, to examine the validity of estimated stair climbing from one question included in a common questionnaire compared to a pattern-recognition activity monitor in older adults. A total of 138 older adults (94 women), aged 65-86 years (70.9 ± 4.7 years), from the IMPACT65 + study participated in this validity study. Estimates of stair climbing were obtained from the European Prospective Investigation into Cancer and Nutrition (EPIC) PA questionnaire. An objective assessment of stair climbing was obtained with the Intelligent Device for Energy Expenditure and Activity (IDEEA) monitor. The correlation between both methods to assess stair climbing was fair (ρ = 0.22, p = 0.008 for PA energy expenditure and ρ = 0.26, p = 0.002 for duration). Mean differences between self-report and the IDEEA were 7.96 ± 10.52 vs. 9.88 ± 3.32 METs-min/day for PA energy expenditure, and 0.99 ± 1.32 vs. 1.79 ± 2.02 min/day for duration (both Wilcoxon test p < 0.001). Results from the Bland-Altman analysis indicate that bias between both instruments were -1.91 ± 10.30 METs-min/day and -0.80 ± 1.99 min/day, and corresponding limits of agreement for the two instruments were from 18.27 to -22.10 METs-min/day and from 3.09 to -4.70 min/day, respectively. Our results indicate that self-reported stair climbing has modest validity to accurately rank old age participants, and underestimates both PAEE and its duration, as compared with an objectively measured method.

Stair-climbing capabilities of USU's T3 ODV mobile robot

Science.gov (United States)

Robinson, D. Reed; Wood, Carl G.

2001-09-01

A six-wheeled autonomous omni-directional vehicle (ODV) called T3 has been developed at Utah State University's (USU) Center for Self-Organizing and Intelligent Systems (CSOIS). This paper focuses on T3's ability to climb stairs using its unique configuration of 6 independently driven and steered wheels and active suspension height control. The ability of T3, or any similar vehicle, to climb stairs is greatly dependent on the chassis orientation relative to the stairs. Stability criteria is developed for any vehicle dimensions and orientation, on any staircase. All possible yaw and pitch angles on various staircases are evaluated to find vehicle orientations that will allow T3 to climb with the largest margin of stability. Different controller types are investigated for controlling vertical wheel movement with the objective of keeping all wheels in contact with the stairs, providing smooth load transfer between loaded and unloaded wheels, and maintaining optimum chassis pitch and roll angles. A controller is presented that uses feedback from wheel loading, vertical wheel position, and chassis orientation sensors. The implementation of the controller is described, and T3's stair climbing performance is presented and evaluated.

Measurement of weak low frequency pressure signal using stretchable polyurethane fiber sensor for application in wearables

DEFF Research Database (Denmark)

Kaysir, Md Rejvi; Stefani, Alessio; Lwin, Richard

2017-01-01

.e. a capillary) to measure a weak low frequency signal comparable to respiration/heart rate. We characterized the fiber and measured the sensitivity of a PU capillary using a speaker connected to a function generator. The frequency of the modulated signal was recovered using Fourier Transform (FT). This bodes...

Permanent Magnetic System Design for the Wall-Climbing Robot

Directory of Open Access Journals (Sweden)

W. Shen

2006-01-01

Full Text Available This paper presents the design and analysis of the permanent magnetic system for a wall-climbing robot with permanent magnetic tracks. Based on the behaviour of gecko lizards, the architecture of the robot was designed and built, including the structure of the adhesion mechanism, the mechanical architecture and the anti-toppling mechanism. The permanent magnetic adhesion mechanism and the tracked locomotion mechanism were employed in this kind of wall-climbing robot. Through static and dynamic force analysis of the robot under different situations, design requirements for the adhesion mechanism were derived. Two different types of structures were put forward for the permanent magnetic units and are further discussed in this paper. These two types of structures are also analysed in detail. In addition, a finite-element method was used to verify the results of magnetic units. Finally, two wall-climbing robots, equipped with different magnetic systems described previously, are explained and their applications are discussed in this paper.

Photon statistics of pulse-pumped four-wave mixing in fiber with weak signal injection

Science.gov (United States)

Nan-Nan, Liu; Yu-Hong, Liu; Jia-Min, Li; Xiao-Ying, Li

2016-07-01

We study the photon statistics of pulse-pumped four-wave mixing in fibers with weak coherent signal injection by measuring the intensity correlation functions of individual signal and idler fields. The experimental results show that the intensity correlation function of individual signal (idler) field decreases with the intensity of signal injection. After applying narrow band filter in signal (idler) band, the value of decreases from 1.9 ± 0.02 (1.9 ± 0.02) to 1.03 ± 0.02 (1.05 ± 0.02) when the intensity of signal injection varies from 0 to 120 photons/pulse. The results indicate that the photon statistics changes from Bose-Einstein distribution to Poisson distribution. We calculate the intensity correlation functions by using the multi-mode theory of four-wave mixing in fibers. The theoretical curves well fit the experimental results. Our investigation will be useful for mitigating the crosstalk between quantum and classical channels in a dense wavelength division multiplexing network. Project supported by the National Natural Science Foundation of China (Grant No. 11527808), the State Key Development Program for Basic Research of China (Grant No. 2014CB340103), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120032110055), the Natural Science Foundation of Tianjin, China (Grant No. 14JCQNJC02300), the Program for Changjiang Scholars and Innovative Research Team in University, China, and the Program of Introducing Talents of Discipline to Universities, China (Grant No. B07014).

Amooty, a stair climbing intelligent maintenance robot

Energy Technology Data Exchange (ETDEWEB)

1985-04-01

Toshiba Corporation and a team from Tokyo University have jointly developed a prototype of a mobile, stair climbing intelligent robot, named Amooty, for inspection and maintenance tasks in nuclear power plants.

Retrograde Signaling from Progranulin to Sort1 Counteracts Synapse Elimination in the Developing Cerebellum.

Science.gov (United States)

Uesaka, Naofumi; Abe, Manabu; Konno, Kohtarou; Yamazaki, Maya; Sakoori, Kazuto; Watanabe, Takaki; Kao, Tzu-Huei; Mikuni, Takayasu; Watanabe, Masahiko; Sakimura, Kenji; Kano, Masanobu

2018-02-21

Elimination of redundant synapses formed early in development and strengthening of necessary connections are crucial for shaping functional neural circuits. Purkinje cells (PCs) in the neonatal cerebellum are innervated by multiple climbing fibers (CFs) with similar strengths. A single CF is strengthened whereas the other CFs are eliminated in each PC during postnatal development. The underlying mechanisms, particularly for the strengthening of single CFs, are poorly understood. Here we report that progranulin, a multi-functional growth factor implicated in the pathogenesis of frontotemporal dementia, strengthens developing CF synaptic inputs and counteracts their elimination from postnatal day 11 to 16. Progranulin derived from PCs acts retrogradely onto its putative receptor Sort1 on CFs. This effect is independent of semaphorin 3A, another retrograde signaling molecule that counteracts CF synapse elimination. We propose that progranulin-Sort1 signaling strengthens and maintains developing CF inputs, and may contribute to selection of single "winner" CFs that survive synapse elimination. Copyright © 2018 Elsevier Inc. All rights reserved.

Amooty, a stair climbing intelligent maintenance robot

International Nuclear Information System (INIS)

Anon.

1985-01-01

Toshiba Corporation and a team from Tokyo University have jointly developed a prototype of a mobile, stair climbing intelligent robot, named Amooty, for inspection and maintenance tasks in nuclear power plants. (author)

Effect of pretreatments and processing conditions on anti-nutritional factors in climbing bean flours

Directory of Open Access Journals (Sweden)

Emmanuel Mugabo

2017-04-01

Full Text Available It is difficult for many Rwandans to utilize climbing bean seeds (Phaseolus vulgaris. L mainly because of longer cooking time (2 hours and the high consumption of basic fuel. Climbing beans also contain anti-nutritional factors such tannins, phytates, trypsin inhibitors and phytohemagglutinins that limit nutrient absorption. One way to solve this problem is to utilize the flour of climbing beans made from different treatments and processing methods. In this study, climbing beans were pre-treated by soaking them in water for 24 hours, soaking in 2% sodium bicarbonate solution and steam blanching for 10 minutes. After that, pre-treated climbing beans were processed into flours by processing methods such as roasting, cooking and germination where anti-nutritional factors were reduced. The pretreatments did not significantly (p>0.05 affect phytates in climbing bean flours but processing conditions significantly (p<0.05 reduced it. Pretreatments and processing conditions significantly (p<0.05 reduced tannin content. The pretreatments followed by different processing conditions significantly (p<0.05 decreased trypsin inhibitors content. The great significant decrease in phytohemagglutinins content was observed in pretreatment followed by different processing methods. All pretreatments and processing conditions effectively decreased anti-nutritional factors at low level. However, pretreatments or untreated followed by germination and roasting were found to be the most and the least effective respectively.  Making flour from germinated climbing bean seeds is a good option for sustainable food processing as it reduces anti-nutritional factors. It is an inexpensive method in terms of time, energy and fuel for Rwandan households, restaurants and industries where climbing bean seeds are integral part of daily meal.

WITHIN-POPULATION GENETIC DIVERSITY OF CLIMBING PLANTS AND TREES IN A TEMPERATE FOREST IN CENTRAL CHILE

OpenAIRE

Torres-Díaz, Cristian; Ruiz, Eduardo; Salgado-Luarte, Cristian; Molina-Montenegro, Marco A; Gianoli, Ernesto

2013-01-01

The climbing habit is a key innovation in angiosperm evolution: climbing plant taxa have greater species richness than their non-climbing sister groups. It is considered that highly diversified clades should show increased among-population genetic differentiation. Less clear is the expected pattern regarding within-population genetic diversity in speciose lineages. We tested the hypothesis of greater within-population genetic diversity in climbing plants compared to trees in a temperate fores...

Does a video displaying a stair climbing model increase stair use in a worksite setting?

Science.gov (United States)

Van Calster, L; Van Hoecke, A-S; Octaef, A; Boen, F

2017-08-01

This study evaluated the effects of improving the visibility of the stairwell and of displaying a video with a stair climbing model on climbing and descending stair use in a worksite setting. Intervention study. Three consecutive one-week intervention phases were implemented: (1) the visibility of the stairs was improved by the attachment of pictograms that indicated the stairwell; (2) a video showing a stair climbing model was sent to the employees by email; and (3) the same video was displayed on a television screen at the point-of-choice (POC) between the stairs and the elevator. The interventions took place in two buildings. The implementation of the interventions varied between these buildings and the sequence was reversed. Improving the visibility of the stairs increased both stair climbing (+6%) and descending stair use (+7%) compared with baseline. Sending the video by email yielded no additional effect on stair use. By contrast, displaying the video at the POC increased stair climbing in both buildings by 12.5% on average. One week after the intervention, the positive effects on stair climbing remained in one of the buildings, but not in the other. These findings suggest that improving the visibility of the stairwell and displaying a stair climbing model on a screen at the POC can result in a short-term increase in both climbing and descending stair use. Copyright © 2017 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

How do Continuous Climb Operations affect the capacity of a Terminal Manoeuvre Area?

Energy Technology Data Exchange (ETDEWEB)

Perez Casan, J.A.

2016-07-01

Continuous climb operations are the following step to optimise departure trajectories with the goals of minimizing fuel consumption and pollutants and noise emissions in the airports neighbourhood, although due to intrinsic nature of these procedures, the integration of these procedures need to develop a new framework for airline operators and air traffic control. Based on the BADA model developed by EUROCONTROL, three activities have been carried out: simulation of several continuous climbs for three aircraft types (Light, Medium and Heavy), analysation of different applied separations throughout the climb from the runway up to cruise level and, as third activity, definition of new separation minima to ensure that the minimum separations are not violated with this new procedures along the climb. In this work are presented the results of modelling three continuous climb type (constant true airspeed, constant climb angle and constant vertical speed) and new time-based separations for most used models in Palma TMA, which will be the case-study scenario. Finally, this theoretical analysis has been applied to a real scenario in Palma de Mallorca TMA in order to compare how the capacity deals with the introduction of this new procedure to standard departures, standard departures are understood as a departure with a level-off at a determined altitude and with the possibility to be affected by any ATC action. First outcomes are promising because capacity, theoretically, would not be grossly diminished, which could initially be expected based on previous studies on continuous descent approaches, although these results should be considered cautiously due to the fact that the model lacks several factors of associated uncertainty for a real climb. (Author)

The role of multiple dopamine receptors in apomorphine and N-n-propylnorapomorphine-induced climbing and hypothermia.

Science.gov (United States)

Moore, N A; Axton, M S

1990-03-20

Apomorphine and N-n-propylnorapomorphine (NPA) were compared for their ability to induce stereotyped cage climbing and hypothermia in mice. Climbing behavior was produced by similar doses of apomorphine and NPA (0.625-2.5 mg/kg s.c.), whereas NPA was 43 times more potent than apomorphine in inducing a hypothermic response. SKF38393 caused a shift to the left in the dose-response curve for NPA-induced climbing, the ED50 changing from 0.98 to 0.014 mg/kg. SKF38393 had no effect on apomorphine-induced climbing behaviour. The climbing response produced by apomorphine was antagonised by both D-1 and D-2 antagonists. Climbing behaviour induced by NPA (2.5 mg/kg) could be antagonised by SCH23390 but not by clebopride, however climbing behaviour induced by a low dose of NPA (0.06 mg/kg) plus SKF38393 could be blocked by both D-1 and D-2 receptor antagonists. The hypothermic responses produced by either apomorphine or NPA could only be reversed by the selective D-2 antagonist, clebopride. These results demonstrate that dopamine agonist-induced stereotyped cage climbing requires both D-1 and D-2 receptor stimulation, whereas the hypothermic response is D-2-mediated. The results also show that it is possible to assess the relative activity of a dopamine agonist at D-1 or D-2 receptors in vivo by comparing the ability of the compound to induce hypothermia and climbing behaviour.

Does perceived steepness deter stair climbing when an alternative is available?

Science.gov (United States)

Eves, Frank F; Thorpe, Susannah K S; Lewis, Amanda; Taylor-Covill, Guy A H

2014-06-01

Perception of hill slant is exaggerated in explicit awareness. Proffitt (Perspectives on Psychological Science 1:110-122, 2006) argued that explicit perception of the slant of a climb allows individuals to plan locomotion in keeping with their available locomotor resources, yet no behavioral evidence supports this contention. Pedestrians in a built environment can often avoid climbing stairs, the man-made equivalent of steep hills, by choosing an adjacent escalator. Stair climbing is avoided more by women, the old, and the overweight than by their comparators. Two studies tested perceived steepness of the stairs as a cue that promotes this avoidance. In the first study, participants estimated the steepness of a staircase in a train station (n = 269). Sex, age, height, and weight were recorded. Women, older individuals, and those who were heavier and shorter reported the staircase as steeper than did their comparison groups. In a follow-up study in a shopping mall, pedestrians were recruited from those who chose the stairs and those who avoided them, with the samples stratified for sex, age, and weight status. Participants (n = 229) estimated the steepness of a life-sized image of the stairs they had just encountered, presented on the wall of a vacant shop in the mall. Pedestrians who avoided stair climbing by choosing the escalator reported the stairs as steeper even when demographic differences were controlled. Perceived steepness may to be a contextual cue that pedestrians use to avoid stair climbing when an alternative is available.

Optimization of E r-density profile for efficient pumping and high signal gain in Erbium-doped fiber amplifiers

International Nuclear Information System (INIS)

Arzi, E.; Hassani, A.; Esmaili Seraji, F.

2000-01-01

Recently, the Erbium-Doped Fiber Amplifier has been shown to have a great potentiality in Fiber-Optics Communication. A model is suggested for calculating the E r-density profile, using the propagation and rate equations of a homogeneous two-level laser medium in Erbium-Doped Fiber Amplifier, such that efficient pumping and high signal gain is achieved for different fiber waveguide structure. The result of this numerical calculation shows that the gain, compared with the gain of the existing Erbium-Doped Fiber Amplifier, is higher by a factor of 3.5. This model is applicable in all active waveguides and any other dopant as well

Design and Development of a Step Climbing Wheeled Robot

Directory of Open Access Journals (Sweden)

Srijan BHATTACHARYA

2009-08-01

Full Text Available This paper presents a design of Step Climbing Robot that can move in uneven environment and traverse a slope or staircase. The condition imposed on this new system of robot is that it will move only in linear fashion, which will reduce the demands on the physical complexity of the robot unit. A summary of the current state of research in the field of mobile robots as it relates to robot stair climbing and moving in uneven surfaces. The architecture of the robot is developed and compared with the previous design.

Stem signal suppression in fiber-coupled Al2O3:C dosimetry for 192Ir brachytherapy

DEFF Research Database (Denmark)

Kertzscher Schwencke, Gustavo Adolfo Vladimir; Andersen, Claus Erik; Edmund, J.M.

2011-01-01

was adapted for on-line in-vivo dosimetry using fiber-coupled carbon doped aluminum oxide (Al2O3:C). The technique involved a two-channel optical filtration of the radioluminescence (RL) emitted from a pre-irradiated Al2O3:C crystal with enhanced sensitivity. The system responded linearly in the absorbed dose......The stem signal, composed of fluorescence and Čerenkov light, becomes a significant source of uncertainty in fiber-coupled afterloaded brachytherapy dosimetry when the source dwells near the fiber cable but far from the detector. A stem suppression technique originally developed for scintillators...

Irradiation creep by climb-enables glide of dislocations resulting from preferred absorption of point defects

Energy Technology Data Exchange (ETDEWEB)

Mansur, L K [Oak Ridge National Lab., TN (USA)

1979-04-01

A mechanism of irradiation creep arising from the climb-enabled glide of dislocations due to stress-induced preferred absorption of radiation-produced point defects is proposed. This creep component is here termed preferred absorption glide, PAG. PAG-creep operates in addition to the previously studied components of creep from climb by stress-induced preferred absorption, (SI) PA-creep, and the climb-enabled glide due to excess absorption of interstitials on dislocations during swelling, I-creep. A formulation of the various climb and climb-enabled glide processes which includes earlier results is presented. PAG-creep is comparable in magnitude to PA-creep in the parameter range of applications. While the PSA-creep rate and the I-creep rate are linear in stress, the PAG-creep rate is quadratic in stress and thus dominates at high stresses.

The effects of therapeutic climbing in patients with chronic low back pain: a randomized controlled study.

Science.gov (United States)

Engbert, Kai; Weber, Michaela

2011-05-15

A randomized controlled study investigated the effects of therapeutic climbing in patients with chronic low back pain. Before and after 4 weeks of training, physical and mental well-being were measured by two questionnaires (36-Item Short Form Health Survey [SF-36]; Hannover Functional Ability Questionnaire for measuring back pain-related disability [FFbH-R]). Therapeutic climbing has been suggested to increase muscular strength and perceived physical and mental well-being. This study focused on the psychological effects of therapeutic climbing and compared it with standard exercise therapy. Therapeutic climbing has become increasingly popular in rehabilitation and its effects on muscular strengthening have been shown. Therapeutic climbing has also been suggested to yield psychological effects such as changes in attentional focus from pain to physical capabilities. To date, no controlled clinical trial has investigated these psychological effects and it is unclear whether therapeutic climbing is comparable or superior to other forms of exercise. Twenty-eight patients with chronic low back pain conducted either a therapeutic climbing or a standard exercise regime. Each program took 4 weeks, including four guided training sessions per week. Before and after the program, patients answered two questionnaires assessing their physical and mental well-being. For the Hannover Functional Ability Questionnaire for measuring back pain-related disability, there was no difference before versus after or between the treatments. For the SF-36, both treatments showed significant improvements in 3/8 subscales of the SF-36. In 2/8 subscales, only the participants of the therapeutic climbing improved and in 1/8 subscales the converse was true. Comparing both groups, significantly larger improvements were found after therapeutic climbing in two subscales of the SF-36: physical functioning and general health perception. The benefits of therapeutic climbing were comparable with those of

Space-division-multiplexed transmission of 3x3 multiple-input multiple-output wireless signals over conventional graded-index multimode fiber.

Science.gov (United States)

Lei, Yi; Li, Jianqiang; Fan, Yuting; Yu, Dawei; Fu, Songnian; Yin, Feifei; Dai, Yitang; Xu, Kun

2016-12-12

In this paper, we experimentally demonstrate space-division-multiplexed (SDM) transmission of IEEE 802.11ac-compliant 3-spatial-stream WLAN signals over 3 spatial modes of conventional 50um graded-index (GI) multimode fiber (MMF) employing non-mode-selective 3D-waveguide photonic lantern. Two kinds of scenarios, including fiber-only transmission and fiber-wireless hybrid transmission, were investigated by measuring error vector magnitude (EVM) performance for each stream and condition number (CN) of the channel matrix. The experimental results show that, SDM-based MMF link could offer a CNwireless MIMO signals over existing in-building commercially-available MMFs with enormous cost-saving.

Using optical fibers with different modes to improve the signal-to-noise ratio of diffuse correlation spectroscopy flow-oximeter measurements

Science.gov (United States)

He, Lian; Lin, Yu; Shang, Yu; Shelton, Brent J.; Yu, Guoqiang

2013-03-01

The dual-wavelength diffuse correlation spectroscopy (DCS) flow-oximeter is an emerging technique enabling simultaneous measurements of blood flow and blood oxygenation changes in deep tissues. High signal-to-noise ratio (SNR) is crucial when applying DCS technologies in the study of human tissues where the detected signals are usually very weak. In this study, single-mode, few-mode, and multimode fibers are compared to explore the possibility of improving the SNR of DCS flow-oximeter measurements. Experiments on liquid phantom solutions and in vivo muscle tissues show only slight improvements in flow measurements when using the few-mode fiber compared with using the single-mode fiber. However, light intensities detected by the few-mode and multimode fibers are increased, leading to significant SNR improvements in detections of phantom optical property and tissue blood oxygenation. The outcomes from this study provide useful guidance for the selection of optical fibers to improve DCS flow-oximeter measurements.

Reliability and Validity of Finger Strength and Endurance Measurements in Rock Climbing

Science.gov (United States)

Michailov, Michail Lubomirov; Baláš, Jirí; Tanev, Stoyan Kolev; Andonov, Hristo Stoyanov; Kodejška, Jan; Brown, Lee

2018-01-01

Purpose: An advanced system for the assessment of climbing-specific performance was developed and used to: (a) investigate the effect of arm fixation (AF) on construct validity evidence and reliability of climbing-specific finger-strength measurement; (b) assess reliability of finger-strength and endurance measurements; and (c) evaluate the…

Comparative multibody dynamics analysis of falls from playground climbing frames

OpenAIRE

Forero Rueda, Manuel A.; Gilchrist, M. D.

2009-01-01

This paper shows the utility of multibody dynamics in evaluating changes in injury related parameters of the head and lower limbs of children following falls from playground climbing frames. A particular fall case was used as a starting point to analyze the influence of surface properties, posture of the body at impact, and intermediate collisions against the climbing frame before impacting the ground. Simulations were made using the 6-year-old pedestrian MADYMO rigid body model and scaled he...

High-speed ultra-wideband wireless signals over fiber systems: Photonic generation and DSP detection

DEFF Research Database (Denmark)

Yu, Xianbin; Gibbon, Timothy Braidwood; Tafur Monroy, Idelfonso

2009-01-01

We firstly review the efforts in the literature on UWB over-fiber systems. Secondly, we present experimental results on photonic generation of high-speed UWB signals by both direct modulation and external optical injecting an uncooled semiconductor laser. Furthermore, we introduce the use of digi...

The condensed chromatin fiber: an allosteric chemo-mechanical machine for signal transduction and genome processing

International Nuclear Information System (INIS)

Lesne, Annick; Victor, Jean–Marc; Bécavin, Christophe

2012-01-01

Allostery is a key concept of molecular biology which refers to the control of an enzyme activity by an effector molecule binding the enzyme at another site rather than the active site (allos = other in Greek). We revisit here allostery in the context of chromatin and argue that allosteric principles underlie and explain the functional architecture required for spacetime coordination of gene expression at all scales from DNA to the whole chromosome. We further suggest that this functional architecture is provided by the chromatin fiber itself. The structural, mechanical and topological features of the chromatin fiber endow chromosomes with a tunable signal transduction from specific (or nonspecific) effectors to specific (or nonspecific) active sites. Mechanical constraints can travel along the fiber all the better since the fiber is more compact and regular, which speaks in favor of the actual existence of the (so-called 30 nm) chromatin fiber. Chromatin fiber allostery reconciles both the physical and biochemical approaches of chromatin. We illustrate this view with two supporting specific examples. Moreover, from a methodological point of view, we suggest that the notion of chromatin fiber allostery is particularly relevant for systemic approaches. Finally we discuss the evolutionary power of allostery in the context of chromatin and its relation to modularity. (perspective)

The condensed chromatin fiber: an allosteric chemo-mechanical machine for signal transduction and genome processing

Science.gov (United States)

Lesne, Annick; Bécavin, Christophe; Victor, Jean–Marc

2012-02-01

Allostery is a key concept of molecular biology which refers to the control of an enzyme activity by an effector molecule binding the enzyme at another site rather than the active site (allos = other in Greek). We revisit here allostery in the context of chromatin and argue that allosteric principles underlie and explain the functional architecture required for spacetime coordination of gene expression at all scales from DNA to the whole chromosome. We further suggest that this functional architecture is provided by the chromatin fiber itself. The structural, mechanical and topological features of the chromatin fiber endow chromosomes with a tunable signal transduction from specific (or nonspecific) effectors to specific (or nonspecific) active sites. Mechanical constraints can travel along the fiber all the better since the fiber is more compact and regular, which speaks in favor of the actual existence of the (so-called 30 nm) chromatin fiber. Chromatin fiber allostery reconciles both the physical and biochemical approaches of chromatin. We illustrate this view with two supporting specific examples. Moreover, from a methodological point of view, we suggest that the notion of chromatin fiber allostery is particularly relevant for systemic approaches. Finally we discuss the evolutionary power of allostery in the context of chromatin and its relation to modularity.

The RiSE climbing robot: body and leg design

Science.gov (United States)

Saunders, A.; Goldman, D. I.; Full, R. J.; Buehler, M.

2006-05-01

The RiSE robot is a biologically inspired, six legged climbing robot, designed for general mobility in scansorial (vertical walls, horizontal ledges, ground level) environments. It exhibits ground reaction forces that are similar to animal climbers and does not rely on suction, magnets or other surface-dependent specializations to achieve adhesion and shear force. We describe RiSE's body and leg design as well as its electromechanical, communications and computational infrastructure. We review design iterations that enable RiSE to climb 90° carpeted, cork covered and (a growing range of) stucco surfaces in the quasi-static regime.

Stair climbing is more detrimental to the cement in hip replacement than walking

NARCIS (Netherlands)

Stolk, J.; Verdonschot, N.J.J.; Huiskes, H.W.J.

2002-01-01

Stair climbing may be detrimental to cemented total hip arthroplasties, because it subjects the reconstruction to high torsional loads. The current study investigated how stair climbing contributes to damage accumulation in the cement around a femoral stem compared with walking, taking into account

A Survey of Wall Climbing Robots: Recent Advances and Challenges

Directory of Open Access Journals (Sweden)

Shunsuke Nansai

2016-07-01

Full Text Available In recent decades, skyscrapers, as represented by the Burj Khalifa in Dubai and Shanghai Tower in Shanghai, have been built due to the improvements of construction technologies. Even in such newfangled skyscrapers, the façades are generally cleaned by humans. Wall climbing robots, which are capable of climbing up vertical surfaces, ceilings and roofs, are expected to replace the manual workforce in façade cleaning works, which is both hazardous and laborious work. Such tasks require these robotic platforms to possess high levels of adaptability and flexibility. This paper presents a detailed review of wall climbing robots categorizing them into six distinct classes based on the adhesive mechanism that they use. This paper concludes by expanding beyond adhesive mechanisms by discussing a set of desirable design attributes of an ideal glass façade cleaning robot towards facilitating targeted future research with clear technical goals and well-defined design trade-off boundaries.

Wall Climbing Robot Using Electrostatic Adhesion Force Generated by Flexible Interdigital Electrodes

Directory of Open Access Journals (Sweden)

Rong Liu

2013-01-01

Full Text Available Electrostatic adhesion technology has broad application prospects on wall climbing robots because of its unique characteristics compared with other types of adhesion technologies. A double tracked wall climbing robot based on electrostatic adhesion technology is presented including electrode panel design, mechanical structure design, power supply system design and control system design. A theoretical adhesion model was established and the electrostatic potential and field were expressed by series expansions in terms of solutions of the Laplace function. Based on this model, the electrostatic adhesion force was calculated using the Maxwell stress tensor formulation. Several important factors which may influence the electrostatic adhesion force were analysed and discussed by both FEM simulation and theoretical calculation. In addition, experiments on the adhesion performance of the electrode panel and the climbing performance of the robot on various wall materials were carried out. Both the simulation and experiment results verify the feasibility of electrostatic adhesion technology being applied on wall climbing robots. The theoretical model and calculation method for the electrostatic adhesion force proposed in this paper are also justified.

Footwear in rock climbing: Current practice.

Science.gov (United States)

McHenry, R D; Arnold, G P; Wang, W; Abboud, R J

2015-09-01

Many rock climbers wear ill-fitting and excessively tight footwear during activity. However, there is insufficient evidence of the extent or harms of this practice. To investigate footwear use in rock climbers with a focus on issues surrounding fit. A cross-sectional study with active rock climbers of over one year of experience completing a survey on their activity and footwear. Additionally, the authors quantified foot and shoe lengths and sizes alongside demographic data. Ill-fitting and excessively tight footwear was found in 55 out of 56 rock climbers. Foot pain during activity was also commonplace in 91% of the climbers. A mean size reduction of almost 4 UK shoe sizes was found between the climbers' street shoe size and that of their climbing footwear using a calibrated foot/shoe ruler. There is an unfortunate association of climbers of higher abilities seeking a tighter shoe fit (pfootwear use amongst rock climbers, further investigation may aim to quantify its impact and seek a solution balancing climbing performance while mitigating foot injury. Copyright © 2015 Elsevier Ltd. All rights reserved.

Affordance Realization in Climbing: Learning and Transfer.

Science.gov (United States)

Seifert, Ludovic; Orth, Dominic; Mantel, Bruno; Boulanger, Jérémie; Hérault, Romain; Dicks, Matt

2018-01-01

The aim of this study was to investigate how the affordances of an indoor climbing wall changed for intermediate climbers following a period of practice during which hold orientation was manipulated within a learning and transfer protocol. The learning protocol consisted of four sessions, in which eight climbers randomly ascended three different routes of fixed absolute difficulty (5c on the French scale), as fluently as possible. All three routes were 10.3 m in height and composed of 20 hand-holds at the same locations on an artificial climbing wall; only hold orientations were altered: (i) a horizontal-edge route (H) was designed to afford horizontal hold grasping, (ii) a vertical-edge route (V) afforded vertical hold grasping, and (iii), a double-edge route (D) was designed to afford both horizontal and vertical hold grasping. Five inertial measurement units (IMU) (3D accelerometer, 3D gyroscope, 3D magnetometer) were attached to the hip, feet and forearms to analyze the vertical acceleration and direction (3D unitary vector) of each limb and hip in ambient space during the entire ascent. Segmentation and classification processes supported detection of movement and stationary phases for each IMU. Depending on whether limbs and/or hip were moving, a decision tree distinguished four states of behavior: stationary (absence of limb and hip motion), hold exploration (absence of hip motion but at least one limb in motion), hip movement (hip in motion but absence of limb motion) and global motion (hip in motion and at least one limb in motion). Results showed that with practice, the learners decreased the relative duration of hold exploration, suggesting that they improved affordance perception of hold grasp-ability. The number of performatory movements also decreased as performance increased during learning sessions, confirming that participants' climbing efficacy improved as a function of practice. Last, the results were more marked for the H route, while the D route

Affordance Realization in Climbing: Learning and Transfer

Directory of Open Access Journals (Sweden)

Ludovic Seifert

2018-05-01

Full Text Available The aim of this study was to investigate how the affordances of an indoor climbing wall changed for intermediate climbers following a period of practice during which hold orientation was manipulated within a learning and transfer protocol. The learning protocol consisted of four sessions, in which eight climbers randomly ascended three different routes of fixed absolute difficulty (5c on the French scale, as fluently as possible. All three routes were 10.3 m in height and composed of 20 hand-holds at the same locations on an artificial climbing wall; only hold orientations were altered: (i a horizontal-edge route (H was designed to afford horizontal hold grasping, (ii a vertical-edge route (V afforded vertical hold grasping, and (iii, a double-edge route (D was designed to afford both horizontal and vertical hold grasping. Five inertial measurement units (IMU (3D accelerometer, 3D gyroscope, 3D magnetometer were attached to the hip, feet and forearms to analyze the vertical acceleration and direction (3D unitary vector of each limb and hip in ambient space during the entire ascent. Segmentation and classification processes supported detection of movement and stationary phases for each IMU. Depending on whether limbs and/or hip were moving, a decision tree distinguished four states of behavior: stationary (absence of limb and hip motion, hold exploration (absence of hip motion but at least one limb in motion, hip movement (hip in motion but absence of limb motion and global motion (hip in motion and at least one limb in motion. Results showed that with practice, the learners decreased the relative duration of hold exploration, suggesting that they improved affordance perception of hold grasp-ability. The number of performatory movements also decreased as performance increased during learning sessions, confirming that participants' climbing efficacy improved as a function of practice. Last, the results were more marked for the H route, while the D

Stable Stair Climbing in a Simple Hexapod Robot

National Research Council Canada - National Science Library

Moore, E. Z; Buehler, M

2001-01-01

.... Its ability to traverse highly fractured and unstable terrain has already been documented. In this paper, we describe open loop controllers for our small robot to climb and descend regular stairs...

135 tf climbing crane for the construction of large scale plants

International Nuclear Information System (INIS)

1981-01-01

Development of a larger capacity, wider working radius and higher lift climbing crane was in demand since the large block construction method become common in plant construction. At first, scaling up of the conventional climbing crane was planned. But, it turned out that the deflection at the top of the jib would cause the load to drift at takeoff in crane operation. Therefore, the crane was newly designed to solve the problem. Some of its advantage are as follows. (1) This crane can be used as either a climbing or a nonclimbing type depending on installation locations and objective plants. (2) Accurate and easy operation is achieved because of little deflection at the top of the jib. (3) Efficient crane operation is possible through high speed hoisting and slewing motions in frequent auxiliary hoisting operations. (4) The construction time can be shortened by adopting pin joints between the blocks and by reducing the number of assembling parts at the site. A nonclimbing type crane is now in operation at the nuclear power plant in Kashiwazaki and a climbing type will be in operation at the nuclear power plant in Fukushima this year. The report presents an outline of the specifications, structures and advantages. (author)

Analysis of Relations between Spatiotemporal Movement Regulation and Performance of Discrete Actions Reveals Functionality in Skilled Climbing.

Science.gov (United States)

Orth, Dominic; Kerr, Graham; Davids, Keith; Seifert, Ludovic

2017-01-01

In this review of research on climbing expertise, we focus on different measures of climbing performance, including spatiotemporal measures related to fluency and activity states (i.e., discrete actions), adopted by climbers for achieving overall performance goals of getting to the end of a route efficiently and safely. Currently, a broad range of variables have been reported, however, many of these fail to capture how climbers adapt to a route whilst climbing. We argue that spatiotemporal measures should be considered concurrently with evaluation of activity states (such as reaching or exploring) in order gain a more comprehensive picture of how climbers successfully adapt to a route. Spatial and temporal movement measures taken at the hip are a traditional means of assessing efficiency of climbing behaviors. More recently, performatory and exploratory actions of the limbs have been used in combination with spatiotemporal indicators, highlighting the influence of limb states on climbing efficiency and skill transfer. However, only a few studies have attempted to combine spatiotemporal and activity state measures taken during route climbing. This review brings together existing approaches for observing climbing skill at performance outcome (i.e., spatiotemporal assessments) and process (i.e., limb activity states) levels of analysis. Skill level is associated with a spatially efficient route progression and lower levels of immobility. However, more difficult hold architecture designs require significantly greater mobility and more complex movement patterning to maintain performance. Different forms of functional, or goal-supportive, movement variability, including active recovery and hold exploration, have been implicated as important adaptations to physiological and environmental dynamics that emerge during the act of climbing. Indeed, recently it has also been shown that, when climbing on new routes, efficient exploration can improve the transfer of skill. This

Diode-laser-pump module with integrated signal ports for pumping amplifying fibers and method

Science.gov (United States)

Savage-Leuchs,; Matthias, P [Woodinville, WA

2009-05-26

Apparatus and method for collimating pump light of a first wavelength from laser diode(s) into a collimated beam within an enclosure having first and second optical ports, directing pump light from the collimated beam to the first port; and directing signal light inside the enclosure between the first and second port. The signal and pump wavelengths are different. The enclosure provides a pump block having a first port that emits pump light to a gain fiber outside the enclosure and that also passes signal light either into or out of the enclosure, and another port that passes signal light either out of or into the enclosure. Some embodiments use a dichroic mirror to direct pump light to the first port and direct signal light between the first and second ports. Some embodiments include a wavelength-conversion device to change the wavelength of at least some of the signal light.

A multistage controlled intervention to increase stair climbing at work: effectiveness and process evaluation.

Science.gov (United States)

Bellicha, Alice; Kieusseian, Aurélie; Fontvieille, Anne-Marie; Tataranni, Antonio; Copin, Nane; Charreire, Hélène; Oppert, Jean-Michel

2016-04-11

Stair climbing helps to accumulate short bouts of physical activity throughout the day as a strategy for attaining recommended physical activity levels. There exists a need for effective long-term stair-climbing interventions that can be transferred to various worksite settings. The aims of this study were: 1) to evaluate short- and long-term effectiveness of a worksite stair-climbing intervention using an objective measurement of stair climbing and a controlled design; and 2) to perform a process evaluation of the intervention. We performed a controlled before-and-after study. The study was conducted in two corporate buildings of the same company located in Paris (France), between September, 2013 and September, 2014. The status of either "intervention site" or "control site" was assigned by the investigators. Participants were on-site employees (intervention site: n = 783; control site: n = 545 at baseline). Two one-month intervention phases using signs (intervention phase 1) and enhancement of stairwell aesthetics (intervention phase 2) were performed. The main outcome was the change in stair climbing, measured with automatic counters and expressed in absolute counts/day/100 employees and percent change compared to baseline. Qualitative outcomes were used to describe the intervention process. Stair climbing significantly increased at the intervention site (+18.7%) but decreased at the control site (-13.3%) during the second intervention phase (difference between sites: +4.6 counts/day/100 employees, p levels at the intervention site, but a significant difference between sites was found (intervention site vs. control site: +2.9 counts/day/100 employees, p level after the end of the study. This study shows a successful stair-climbing intervention at the worksite. The main barriers to adoption and implementation were related to location and visibility of posters. Process evaluation was useful in identifying these barriers throughout the study, and in

Effect of sunflower climbing bean intercroping system on insect pest incidence and crop productivity

International Nuclear Information System (INIS)

Tuey, R.K.; Koros, I.; Wanyonyi, W.

2001-01-01

Intercropping of sunflower and climping beans were evaluated for pest incidence and yield advantages during the main season of 2000/2001 at KARI-NPBRC, Njoro. Three sunflower varieties, Fedha, Record, PAN-7553 and three climbing beans varieties, Puebla, Omukingi and Flora were laid out in a complete randomised block design with four replications. Sunflower was spaced at 75 x 30 cm while the climbing beans were spaced at 50 x 37.5 cm. Assessment of pest damage on various treatments commenced 17 days after planting. Results showed that low plant germination was mainly a result of dry weather and taht cutworm damage was insignificant. There was a sunflower x climbing bean variety interaction, which regulated the aphid infestation of the climbing beans. Sunflower variety PAN-7553 recorded significantly (P<0.01) more pecked heads than the other two varieties. (author)

Linearized Optically Phase-Modulated Fiber Optic Links for Microwave Signal Transport

Science.gov (United States)

2009-03-03

detectors (with internal 50- Ohm resistors) capable of 40-mA dc current per detector. With this link, the linearized SFDR would improve to 133 dB/Hz4/5...the IF) limitation on the signal. All calculations consider the 3dB power loss from the hybrid combiner and 6dB loss from parallel 50- Ohm resistors...283. [25] M. Nazarathy, J. Berger, A. Ley , I. Levi, and Y. Kagan, “Externally Modulated 80 Channel Am Catv Fiber-to-feeder Distribution System Over

Design and Implementation of Autonomous Stair Climbing with Nao Humanoid Robot

OpenAIRE

Lu, Wei

2015-01-01

With the development of humanoid robots, autonomous stair climbing is an important capability. Humanoid robots will play an important role in helping people tackle some basic problems in the future. The main contribution of this thesis is that the NAO humanoid robot can climb the spiral staircase autonomously. In the vision module, the algorithm of image filtering and detecting the contours of the stair contributes to calculating the location of the stairs accurately. Additionally, the st...

On the static structural design of climbing robots: part 1.

Science.gov (United States)

Ahmed, Ausama Hadi; Menon, Carlo

This manuscript is the first of two parts of a work investigating optimal configurations of legged climbing robots while loitering on vertical surfaces. In this part 1, a mathematical model of a climbing robot based on the finite element method (FEM), specifically the stiffness method, is generated. A number of parameters, namely the height of the robot, the length of its body and the position of its legs, are investigated to assess their effect on the adhesion requirements needed for the robot to stay attached to a wall. Predictions of the developed mathematical model are validated using FEM commercial software. The body and the legs are assumed to be perpendicular to each other in this part 1. The effect of their inclination is investigated in the subsequent part 2 of our work. In part 2, the model is also used to predict postures that ants have while standing on vertical surfaces. The model is validated by comparing the predicted results to images of loitering ants. The parameters investigated provide guidelines to design legged climbing robots.

Distributed Weak Fiber Bragg Grating Vibration Sensing System Based on 3 × 3 Fiber Coupler

Science.gov (United States)

Li, Wei; Zhang, Jian

2018-06-01

A novel distributed weak fiber Bragg gratings (FBGs) vibration sensing system has been designed to overcome the disadvantages of the conventional methods for optical fiber sensing networking, which are: low signal intensity in the usually adopted time-division multiplexing (TDM) technology, insufficient quantity of multiplexed FBGs in the wavelength-division multiplexing (WDM) technology, and that the mixed WDM/TDM technology measures only the physical parameters of the FBG locations but cannot perform distributed measurement over the whole optical fiber. This novel system determines vibration events in the optical fiber line according to the intensity variation of the interference signals between the adjacent weak FBG reflected signals and locates the vibration points accurately using the TDM technology. It has been proven by tests that this system performs vibration signal detection and demodulation in a way more convenient than the conventional methods for the optical fiber sensing system. It also measures over the whole optical fiber, therefore, distributed measurement is fulfilled, and the system locating accuracy is up to 20 m, capable of detecting any signals of whose drive signals lower limit voltage is 0.2 V while the frequency range is 3 Hz‒1 000 Hz. The system has the great practical significance and application value for perimeter surveillance systems.

Impulse radio ultra wide-band over multi-mode fiber for in-home signal distribution

DEFF Research Database (Denmark)

Caballero Jambrina, Antonio; Rodes, Roberto; Jensen, Jesper Bevensee

2009-01-01

We propose and experimentally demonstrate a high speed impulse radio ultra wide-band (IR-UWB) wireless link for in-home network signal distribution. The IR-UWB pulse is distributed over a multimode fiber to the transmitter antenna. Wireless transmitted bit-rates of 1 Gbps at 2 m and 2 Gbps at 1.5 m...

Comparative multibody dynamics analysis of falls from playground climbing frames.

Science.gov (United States)

Forero Rueda, M A; Gilchrist, M D

2009-10-30

This paper shows the utility of multibody dynamics in evaluating changes in injury related parameters of the head and lower limbs of children following falls from playground climbing frames. A particular fall case was used as a starting point to analyze the influence of surface properties, posture of the body at impact, and intermediate collisions against the climbing frame before impacting the ground. Simulations were made using the 6-year-old pedestrian MADYMO rigid body model and scaled head contact characteristics. Energy absorbing surfaces were shown to reduce injury severity parameters by up to 30-80% of those of rigid surfaces, depending on impact posture and surface. Collisions against components of a climbing frame during a fall can increase injury severity of the final impact of the head with the ground by more than 90%. Negligible changes are associated with lower limb injury risks when different surfacing materials are used. Computer reconstructions of actual falls that are intended to quantify the severity of physical injuries rely on accurate knowledge of initial conditions prior to falling, intermediate kinematics of the fall and the orientation of the body when it impacts against the ground. Multibody modelling proved to be a valuable tool to analyze the quality of eyewitness information and analyze the relative injury risk associated with changes in components influencing fall injuries from playground climbing frames. Such simulations can also support forensic investigations by evaluating alternative hypotheses for the sequence of kinematic motion of falls which result in known injuries.

Analysis of Relations between Spatiotemporal Movement Regulation and Performance of Discrete Actions Reveals Functionality in Skilled Climbing

Directory of Open Access Journals (Sweden)

Dominic Orth

2017-10-01

Full Text Available In this review of research on climbing expertise, we focus on different measures of climbing performance, including spatiotemporal measures related to fluency and activity states (i.e., discrete actions, adopted by climbers for achieving overall performance goals of getting to the end of a route efficiently and safely. Currently, a broad range of variables have been reported, however, many of these fail to capture how climbers adapt to a route whilst climbing. We argue that spatiotemporal measures should be considered concurrently with evaluation of activity states (such as reaching or exploring in order gain a more comprehensive picture of how climbers successfully adapt to a route. Spatial and temporal movement measures taken at the hip are a traditional means of assessing efficiency of climbing behaviors. More recently, performatory and exploratory actions of the limbs have been used in combination with spatiotemporal indicators, highlighting the influence of limb states on climbing efficiency and skill transfer. However, only a few studies have attempted to combine spatiotemporal and activity state measures taken during route climbing. This review brings together existing approaches for observing climbing skill at performance outcome (i.e., spatiotemporal assessments and process (i.e., limb activity states levels of analysis. Skill level is associated with a spatially efficient route progression and lower levels of immobility. However, more difficult hold architecture designs require significantly greater mobility and more complex movement patterning to maintain performance. Different forms of functional, or goal-supportive, movement variability, including active recovery and hold exploration, have been implicated as important adaptations to physiological and environmental dynamics that emerge during the act of climbing. Indeed, recently it has also been shown that, when climbing on new routes, efficient exploration can improve the transfer

Hardware-efficient signal generation of layered/enhanced ACO-OFDM for short-haul fiber-optic links.

Science.gov (United States)

Wang, Qibing; Song, Binhuang; Corcoran, Bill; Boland, David; Zhu, Chen; Zhuang, Leimeng; Lowery, Arthur J

2017-06-12

Layered/enhanced ACO-OFDM is a promising candidate for intensity modulation and direct-detection based short-haul fiber-optic links due to its both power and spectral efficiency. In this paper, we firstly demonstrate a hardware-efficient real-time 9.375 Gb/s QPSK-encoded layered/enhanced asymmetrical clipped optical OFDM (L/E-ACO-OFDM) transmitter using a Virtex-6 FPGA. This L/E-ACO-OFDM signal is successfully transmitted over 20-km uncompensated standard single-mode fiber (S-SMF) using a directly modulated laser. Several methods are explored to reduce the FPGA's logic resource utilization by taking advantage of the L/E-ACO-OFDM's signal characteristics. We show that the logic resource occupation of L/E-ACO-OFDM transmitter is almost the same as that of DC-biased OFDM transmitter when they achieve the same spectral efficiency, proving its great potential to be used in a real-time short-haul optical transmission link.

Development of Vmax III. Magnetic wall climbing robot with holonomic and omni-directional mobility

International Nuclear Information System (INIS)

Tsuru, Kiyoshi; Hirose, Shigeo

2012-01-01

Wall-climbing robots having holonomic and omni-directional mobility would enhance the manipulation performance of the mounted arm and enable it to execute various tasks on the surface of large structures. This study focuses on the wall-climbing robots having permanent magnet attractive units to stick to the surface of iron structure such as atomic reactors and discuss the development of a specific holonomic and omni-directional wall-climbing mechanisms. Basic driving mechanism of the wall-climbing robot is based on our former invention named Omni Disk which consists of multiple rollers attached to one side of a rotating disk and having a mechanism to direct the rollers to the same direction. We firstly discuss about the mechanical improvements of the Omni Disk to make it lightweight and low cost. We next discusses about four types of methods to attach permanent magnets to the wall-climbing robot and generates attractive force on the iron wall and select the best type based on the motion experiments about the constructed models. As the result of these considerations, we developed a holonomic and omni-directional wall-climbing robot named Vmax III which consists of three Omni Disks having permanent magnet at their center having the function to change the magnetic attractive force. By using the Vmax III, we studied about the relation among the magnetic attractive force of three Omni Disks, posture of the Vmax III and inclination angle of the iron wall and clarified the optimized distribution of the magnetic attractive force of the Omni Disks in different inclination of the iron wall. (author)

Specific effects of a calorie-based intervention on stair climbing in overweight commuters.

Science.gov (United States)

Lewis, Amanda L; Eves, Frank F

2011-10-01

Point-of-choice prompts consistently increase stair climbing; a greater increase in overweight than normal weight individuals was reported in a multi-component worksite campaign. The purpose of this study is to investigate effects of a multi-component campaign, on stair climbing, in a public access setting. In an interrupted-time-series-design, baseline observations (2 weeks) preceded a 2-week point-of-choice prompt. An additional message, positioned at the top of the climb for a further 6-week period, summarised the calorific consequences of a single ascent. Inconspicuous observers recorded traveller's methods of ascent, coded by sex and weight status, twice a week between 08:00 and 09:59. At baseline, the overweight chose stairs less than normal weight individuals. The multi-component campaign targeting weight control reversed this bias, increasing stair climbing only in overweight individuals. The specificity of the effect confirms the appeal of this lifestyle activity for the overweight. The discussion focuses on how intentions to control weight may be converted into behaviour.

Advanced digital signal processing for short haul optical fiber transmission beyond 100G

Science.gov (United States)

Kikuchi, Nobuhiko

2017-01-01

Significant increase of intra and inter data center traffic has been expected by the rapid spread of various network applications like SNS, IoT, mobile and cloud computing, and the needs for ultra-high speed and cost-effective short- to medium-reach optical fiber links beyond 100-Gbit/s is becoming larger and larger. Such high-speed links typically use multilevel modulation to lower signaling speed, which in turn face serious challenges in limited loss budget and waveform distortion tolerance. One of the promising techniques to overcome them is the use of advanced digital signal processing (DSP) and we review various DSP applications for short-to-medium reach applications.

Climbing ripple structure and associated storm-lamination from a ...

Indian Academy of Sciences (India)

Pranhita–Godavari Valley, south India, displays well developed climbing ripple lamination and ... sedimentary environments, such as river flood .... Sediment, sequence and facies ..... tic Archaean Witwatersrand Supergroup, South Africa;.

Effects of Temperature and X-rays on Plastic Scintillating Fiber and Infrared Optical Fiber.

Science.gov (United States)

Lee, Bongsoo; Shin, Sang Hun; Jang, Kyoung Won; Yoo, Wook Jae

2015-05-11

In this study, we have studied the effects of temperature and X-ray energy variations on the light output signals from two different fiber-optic sensors, a fiber-optic dosimeter (FOD) based on a BCF-12 as a plastic scintillating fiber (PSF) and a fiber-optic thermometer (FOT) using a silver halide optical fiber as an infrared optical fiber (IR fiber). During X-ray beam irradiation, the scintillating light and IR signals were measured simultaneously using a dosimeter probe of the FOD and a thermometer probe of the FOT. The probes were placed in a beaker with water on the center of a hotplate, under variation of the tube potential of a digital radiography system or the temperature of the water in the beaker. From the experimental results, in the case of the PSF, the scintillator light output at the given tube potential decreased as the temperature increased in the temperature range from 25 to 60 °C. We demonstrated that commonly used BCF-12 has a significant temperature dependence of -0.263 ± 0.028%/°C in the clinical temperature range. Next, in the case of the IR fiber, the intensity of the IR signal was almost uniform at each temperature regardless of the tube potential range from 50 to 150 kVp. Therefore, we also demonstrated that the X-ray beam with an energy range used in diagnostic radiology does not affect the IR signals transmitted via a silver halide optical fiber.

Climbing Mont Blanc and Scalability

OpenAIRE

Chavez, Christian

2016-01-01

This thesis details a proposed system implementation upgrade for the CMB system, accessible at \\url{climb.idi.ntnu.no}, which profiles C/C++ code for its energy efficiency on an Odroid-XU3 board, which utilises a Samsung Exynos 5 Octa CPU, and has an ARM Mali-T628 GPU. Our proposed system implementation improves the robustness of the code base and its execution, in addition to permitting an increased throughput of submissions profiled by the system with the implementation's dispatcher whic...

Effects of sports climbing on muscle performance and balance for patients with multiple sclerosis

DEFF Research Database (Denmark)

Jolk, Christoph; Dalgas, Ulrik; Osada, Nani

2015-01-01

Background/Aims: The potential benefits of sports climbing for many diseases have not been investigated. The aim of this case series was to examine whether sports climbing is feasible and whether it can influence isometric muscle performance and balance in people with multiple sclerosis (MS). Met...

Climbing the health learning curve together | IDRC - International ...

International Development Research Centre (IDRC) Digital Library (Canada)

2011-01-25

Jan 25, 2011 ... Climbing the health learning curve together ... Many of the projects are creating master's programs at their host universities ... Formerly based in the high Arctic, Atlantis is described by Dr Martin Forde of St George's University ...

Agronomic description of new improved climbing bean varieties

African Journals Online (AJOL)

. 21. David, S and Hoogendijk,M. 1997. Bean production systems in MbaJe district, Uganda with emphasis on varietal diversity and the adoption of new climbing beans. Network on bean research in Africa. CIA T. CIA T, occasional publication ...

Analysis of sociodemographic, sport and psychological profile in a rock-climbing experience on university students

Directory of Open Access Journals (Sweden)

Pablo Morilla Portela

2013-07-01

Full Text Available The relationships among several psychological factors in rock climbing was proved a long time ago, nevertheless, most researches are limited to very artificial situations, far away from nature. There are few studies which have carried out this kind of investigation in the natural environment and have combined data collection with real rock climbing practice. The instruments used for this data collection were two questionnaires: CSAI-2 and another one specifically designed to gather the necessary information about sociodemographic characteristic and sport habits. In our work we have studied various individuals’ features (sociodemographic, general sport and outdoor profiles and we have confirmed how they are interrelated and their influence on several psychological factors (cognitive anxiety, somatic anxiety and self-confidence. Through this article we show that there are higher percentages of women than men participants who climb IV-V grade, whereas in higher grades the percentages equalize. Regarding psychological factors, we can notice how on the one hand those participants who climb higher grades and are more interested in rock climbing, feel lower cognitive anxiety and somatic anxiety, while on the other hand they feel higher self-confidence levels

Single Particle Differentiation through 2D Optical Fiber Trapping and Back-Scattered Signal Statistical Analysis: An Exploratory Approach.

Science.gov (United States)

Paiva, Joana S; Ribeiro, Rita S R; Cunha, João P S; Rosa, Carla C; Jorge, Pedro A S

2018-02-27

Recent trends on microbiology point out the urge to develop optical micro-tools with multifunctionalities such as simultaneous manipulation and sensing. Considering that miniaturization has been recognized as one of the most important paradigms of emerging sensing biotechnologies, optical fiber tools, including Optical Fiber Tweezers (OFTs), are suitable candidates for developing multifunctional small sensors for Medicine and Biology. OFTs are flexible and versatile optotools based on fibers with one extremity patterned to form a micro-lens. These are able to focus laser beams and exert forces onto microparticles strong enough (piconewtons) to trap and manipulate them. In this paper, through an exploratory analysis of a 45 features set, including time and frequency-domain parameters of the back-scattered signal of particles trapped by a polymeric lens, we created a novel single feature able to differentiate synthetic particles (PMMA and Polystyrene) from living yeasts cells. This single statistical feature can be useful for the development of label-free hybrid optical fiber sensors with applications in infectious diseases detection or cells sorting. It can also contribute, by revealing the most significant information that can be extracted from the scattered signal, to the development of a simpler method for particles characterization (in terms of composition, heterogeneity degree) than existent technologies.

Climbing for preventing and treating health problems: a systematic review of randomized controlled trials

Directory of Open Access Journals (Sweden)

Fechtelpeter, Dennis

2011-01-01

Full Text Available Objective: To summarize the best available evidence on effectiveness of therapeutic or sport climbing in preventing or treating health problems. Methods: We searched Medline, Embase, CENTRAL, PsycINFO, PEDro, OTseeker and SportDiscus for randomized controlled trials published up to December 26, 2010. We included all trials assessing patient-relevant outcomes. Two reviewers independently selected relevant studies, assessed their methodological quality and extracted data. Quality of evidence was rated using the GRADE system. Data were entered into RevMan 5 to calculate effect sizes and 95% confidence intervals where appropriate.Results: Eligible for inclusion were four RCTs studying the effectiveness of climbing in (a geriatric patients, (b adults with multiple sclerosis, (c adults with chronic low-back pain and (d children with disabilities and poor motor function. The sample sizes ranged between 20 and 95. All trials had major methodological limitations. We found very low quality evidence that therapeutic climbing may improve activities of daily living in geriatric patients compared to physiotherapy as measured by the Barthel index (difference in mean change score: 2.32 [95%-CI: 0.45 to 4.19]. We found very low quality evidence that therapeutic climbing compared to standard exercise therapy may improve physical functioning (difference in mean change score: 16.15 [95%-CI: 4.45 to 27.85] and general physical health (13.14 [95%-CI: 3.61 to 22.67] as measured by the SF-36 in adults with chronic low back-pain. Conclusions: Evidence for the effectiveness of therapeutic climbing is limited to small trials at high risk of bias. The effects of therapeutic climbing are therefore unclear.

Bidirectional fiber-wireless and fiber-IVLLC integrated system based on polarization-orthogonal modulation scheme.

Science.gov (United States)

Lu, Hai-Han; Li, Chung-Yi; Chen, Hwan-Wei; Ho, Chun-Ming; Cheng, Ming-Te; Huang, Sheng-Jhe; Yang, Zih-Yi; Lin, Xin-Yao

2016-07-25

A bidirectional fiber-wireless and fiber-invisible laser light communication (IVLLC) integrated system that employs polarization-orthogonal modulation scheme for hybrid cable television (CATV)/microwave (MW)/millimeter-wave (MMW)/baseband (BB) signal transmission is proposed and demonstrated. To our knowledge, it is the first one that adopts a polarization-orthogonal modulation scheme in a bidirectional fiber-wireless and fiber-IVLLC integrated system with hybrid CATV/MW/MMW/BB signal. For downlink transmission, carrier-to-noise ratio (CNR), composite second-order (CSO), composite triple-beat (CTB), and bit error rate (BER) perform well over 40-km single-mode fiber (SMF) and 10-m RF/50-m optical wireless transport scenarios. For uplink transmission, good BER performance is obtained over 40-km SMF and 50-m optical wireless transport scenario. Such a bidirectional fiber-wireless and fiber-IVLLC integrated system for hybrid CATV/MW/MMW/BB signal transmission will be an attractive alternative for providing broadband integrated services, including CATV, Internet, and telecommunication services. It is shown to be a prominent one to present the advancements for the convergence of fiber backbone and RF/optical wireless feeder.

AMA- and RWE- Based Adaptive Kalman Filter for Denoising Fiber Optic Gyroscope Drift Signal.

Science.gov (United States)

Yang, Gongliu; Liu, Yuanyuan; Li, Ming; Song, Shunguang

2015-10-23

An improved double-factor adaptive Kalman filter called AMA-RWE-DFAKF is proposed to denoise fiber optic gyroscope (FOG) drift signal in both static and dynamic conditions. The first factor is Kalman gain updated by random weighting estimation (RWE) of the covariance matrix of innovation sequence at any time to ensure the lowest noise level of output, but the inertia of KF response increases in dynamic condition. To decrease the inertia, the second factor is the covariance matrix of predicted state vector adjusted by RWE only when discontinuities are detected by adaptive moving average (AMA).The AMA-RWE-DFAKF is applied for denoising FOG static and dynamic signals, its performance is compared with conventional KF (CKF), RWE-based adaptive KF with gain correction (RWE-AKFG), AMA- and RWE- based dual mode adaptive KF (AMA-RWE-DMAKF). Results of Allan variance on static signal and root mean square error (RMSE) on dynamic signal show that this proposed algorithm outperforms all the considered methods in denoising FOG signal.

Step-Climbing Power Wheelchairs: A Literature Review

Science.gov (United States)

Sundaram, S. Andrea; Wang, Hongwu; Ding, Dan

2017-01-01

Background: Power wheelchairs capable of overcoming environmental barriers, such as uneven terrain, curbs, or stairs, have been under development for more than a decade. Method: We conducted a systematic review of the scientific and engineering literature to identify these devices, and we provide brief descriptions of the mechanism and method of operation for each. We also present data comparing their capabilities in terms of step climbing and standard wheelchair functions. Results: We found that all the devices presented allow for traversal of obstacles that cannot be accomplished with traditional power wheelchairs, but the slow speeds and small wheel diameters of some designs make them only moderately effective in the basic area of efficient transport over level ground and the size and configuration of some others limit maneuverability in tight spaces. Conclusion: We propose that safety and performance test methods more comprehensive than the International Organization for Standards (ISO) testing protocols be developed for measuring the capabilities of advanced wheelchairs with step-climbing and other environment-negotiating features to allow comparison of their clinical effectiveness. PMID:29339886

All-Fiber Raman Probe

DEFF Research Database (Denmark)

Brunetti, Anna Chiara

by means of fiber components. Assuming the possibility to use a fiber laser with a fundamental radiation at 1064nm, in-fiber efficient second harmonic generation is achieved by optically poling the core of the waveguide delivering the excitation light to the sample. In this way, Raman spectroscopy...... in the visible range can be performed. The simultaneous delivery of the excitation light and collection of the Raman signal from the sample are achieved by means of a doubleclad fiber, whose core and inner cladding act as \\independent" transmission channels. A double-clad fiber coupler allows for the recovery...... of the collected Raman scattering from the inner-cladding region of the double-clad fiber, thus replacing the bulk dichroic component normally used to demultiplex the pump and Raman signal. A tunable Rayleigh-rejection filter based on a liquid filled-photonic bandgap fiber is also demonstrated in this work...

Using a body sensor network to measure the effect of fatigue on stair climbing performance

International Nuclear Information System (INIS)

Bergmann, Jeroen H M; Smith, Ian C H; Mayagoitia, Ruth E

2012-01-01

In terms of self-rated health, the most important activities of daily living are those involving mobility. Of these activities stair climbing is regarded as the most strenuous. A loss of stair climbing ability with age is normally associated with a loss of muscle strength and power, while other factors that influence muscle function, such as fatigue, are often not taken into account. So far no research has been published on how long-lasting fatigue affects activities of daily living, despite the fact that it has been repeatedly proven, in laboratory settings, to influence muscle force production over long periods of time. Technological advances in body sensor networks (BSNs) now provide a method to measure performance during complex real-life situations. In this study the use of a BSN was explored to investigate the effects of long-lasting fatigue on stair climbing performance in 20 healthy adults. Stair climbing performance was measured before and after a fatiguing protocol using a BSN. Performance was defined by temporal and spatial parameters. Long-lasting fatigue was successfully induced in all participants using an exercise protocol. The BSN showed that post-exercise fatigue did not influence stair climbing times (p > 0.2) and no meaningful changes in joint angles were found. No effect on overall stair climbing performance was found, despite a clear presence of long-lasting fatigue. This study shows that physiological paradigms can be further explored using BSNs. Ecological validity of lab-based measurements can be increased by combining them with BSNs. (paper)

Climbing performance of Harris' hawks (Parabuteo unicinctus) with added load: Implications for muscle mechanics and for radiotracking

Science.gov (United States)

Pennycuick, C.J.; Fuller, M.R.; McAllister, L.

1989-01-01

Two Harris' hawks were trained to fly along horizontal and climbing flight paths, while carrying loads of various masses, to provide data for estimating available muscle power during short flights. The body mass of both hawks was about 920 g, and they were able to carry loads up to 630 g in horizontal flight. The rate of climb decreased with increasing all-up mass, as also did the climbing power (product of weight and rate of climb). Various assumptions about the aerodynamic power in low-speed climbs led to estimates of the maximum power output of the flight muscles ranging from 41 to 46 W. This, in turn, would imply a stress during shortening of around 210 kPa. The effects of a radio package on a bird that is raising young should be considered in relation to the food load that the forager can normally carry, rather than in relation to its body mass.

Inhibition of platelet-derived growth factor signaling prevents muscle fiber growth during skeletal muscle hypertrophy.

Science.gov (United States)

Sugg, Kristoffer B; Korn, Michael A; Sarver, Dylan C; Markworth, James F; Mendias, Christopher L

2017-03-01

The platelet-derived growth factor receptors alpha and beta (PDGFRα and PDGFRβ) mark fibroadipogenic progenitor cells/fibroblasts and pericytes in skeletal muscle, respectively. While the role that these cells play in muscle growth and development has been evaluated, it was not known whether the PDGF receptors activate signaling pathways that control transcriptional and functional changes during skeletal muscle hypertrophy. To evaluate this, we inhibited PDGFR signaling in mice subjected to a synergist ablation muscle growth procedure, and performed analyses 3 and 10 days after induction of hypertrophy. The results from this study indicate that PDGF signaling is required for fiber hypertrophy, extracellular matrix production, and angiogenesis that occur during muscle growth. © 2017 Federation of European Biochemical Societies.

Research on Centroid Position for Stairs Climbing Stability of Search and Rescue Robot

Directory of Open Access Journals (Sweden)

Yan Guo

2011-01-01

Full Text Available This paper represents the relationship between the stability of stairs climbing and the centroid position of the search and rescue robot. The robot system is considered as a mass point-plane model and the kinematics features are analyzed to find the relationship between centroid position and the maximal pitch angle of stairs the robot could climb up. A computable function about this relationship is given in this paper. During the stairs climbing, there is a maximal stability-keeping angle depends on the centroid position and the pitch angle of stairs, and the numerical formula is developed about the relationship between the maximal stability-keeping angle and the centroid position and pitch angle of stairs. The experiment demonstrates the trustworthy and correction of the method in the paper.

Fuel management optimization in pressure water reactors with hexagonal geometry using hill climbing method

International Nuclear Information System (INIS)

Andres Diaz, J.; Quintero, Ruben; Melian, Manuel; Rosete, Alejandro

2000-01-01

In this work the general-purpose optimization method, Hill Climbing, was applied to the Fuel Management Optimization problem in PWR reactors, WWER type. They were carried out a series of experiments in order to study the performance of Hill Climbing. It was proven two starting point for initialize the search: a reload configuration by project and a reload configuration generated with the application of a minimal knowledge of the problem. It was also studied the effect of imposing constraints based on the physics of the reactor in order to reduce the number of possible solutions to be generated. The operator used in Hill Climbing was defined as a binary exchange of fuel assemblies. For the simulation of each generated configuration, the tridimensional simulator program SPPS-1 was used. It was formulated an objective function with power peaking constraint to guide the search. As results, a methodology ws proposed for the In-core Fuel Management Optimization in hexagonal geometry, and the feasibility of the application of the Hill Climbing to this type of problem was demonstrated. (author)

Hill climbing algorithms and trivium

DEFF Research Database (Denmark)

Borghoff, Julia; Knudsen, Lars Ramkilde; Matusiewicz, Krystian

2011-01-01

This paper proposes a new method to solve certain classes of systems of multivariate equations over the binary field and its cryptanalytical applications. We show how heuristic optimization methods such as hill climbing algorithms can be relevant to solving systems of multivariate equations....... A characteristic of equation systems that may be efficiently solvable by the means of such algorithms is provided. As an example, we investigate equation systems induced by the problem of recovering the internal state of the stream cipher Trivium. We propose an improved variant of the simulated annealing method...

Multipoint fiber-optic laser-ultrasonic actuator based on fiber core-opened tapers.

Science.gov (United States)

Tian, Jiajun; Dong, Xiaolong; Gao, Shimin; Yao, Yong

2017-11-27

In this study, a novel fiber-optic, multipoint, laser-ultrasonic actuator based on fiber core-opened tapers (COTs) is proposed and demonstrated. The COTs were fabricated by splicing single-mode fibers using a standard fiber splicer. A COT can effectively couple part of a core mode into cladding modes, and the coupling ratio can be controlled by adjusting the taper length. Such characteristics are used to obtain a multipoint, laser-ultrasonic actuator with balanced signal strength by reasonably controlling the taper lengths of the COTs. As a prototype, we constructed an actuator that generated ultrasound at four points with a balanced ultrasonic strength by connecting four COTs with coupling ratios of 24.5%, 33.01%, 49.51%, and 87.8% in a fiber link. This simple-to-fabricate, multipoint, laser-ultrasonic actuator with balanced ultrasound signal strength has potential applications in fiber-optic ultrasound testing technology.

The performance of integrated active fiber composites in carbon fiber laminates

International Nuclear Information System (INIS)

Melnykowycz, M; Brunner, A J

2011-01-01

Piezoelectric elements integrated into fiber-reinforced polymer-matrix laminates can provide various functions in the resulting adaptive or smart composite. Active fiber composites (AFC) composed of lead zirconate titanate (PZT) fibers can be used as a component in a smart material system, and can be easily integrated into woven composites. However, the impact of integration on the device and its functionality has not been fully investigated. The current work focuses on the integration and performance of AFC integrated into carbon-fiber-reinforced plastic (CFRP) laminates, focusing on the strain sensor performance of the AFC–CFRP laminate under tensile loading conditions. AFC were integrated into cross-ply CFRP laminates using simple insertion and interlacing of the CFRP plies, with the AFC always placed in the 90° ply cutout area. Test specimens were strained to different strain levels and then cycled with a 0.01% strain amplitude, and the resulting signal from the AFC was monitored. Acoustic emission monitoring was performed during tensile testing to provide insight to the failure characteristics of the PZT fibers. The results were compared to those from past studies on AFC integration; the strain signal of AFC integrated into CFRP was much lower than that for AFC integrated into woven glass fiber laminates. However, the profiles of the degradations of the AFC signal resulting from the strain were nearly identical, showing that the PZT fibers fragmented in a similar manner for a given global strain. The sensor performance recovered upon unloading, which is attributed to the closure of cracks between PZT fiber fragments

Piper (Piperaceae) in New Guinea: the climbing species

NARCIS (Netherlands)

Gardner, R.O.

2012-01-01

Sixteen climbing Piper species are accepted for New Guinea. The three endemics, P. arfakianum, P. subcanirameum and P. versteegii, are fully described. Eight taxa of unclear circumscription are noted. A new variety of P. macropiper, endemic to Morobe Province of Papua New Guinea, is described. The

Construct Validity and Test-Retest Reliability of the Climbing Stairs Questionnaire in Lower-Limb Amputees

NARCIS (Netherlands)

de Laat, Fred A.; Rommers, Gerardus M.; Geertzen, Jan H.; Roorda, Leo D.

de Laat FA, Rommers GM, Geertzen JH, Roorda LD. Construct validity and test-retest reliability of the Climbing Stairs Questionnaire in lower-limb amputees. Arch Phys Med Rehabil 2010;91:1396-401. Objective: To investigate the construct validity and test-retest reliability of the Climbing Stairs

Multiband LTE-A and 4-PAM signals over large-core plastic fibers for in-home networks

NARCIS (Netherlands)

Forni, F.; Shi, Y.; van den Boom, H.P.A.; Tangdiongga, E.; Koonen, A.M.J.

2016-01-01

This letter presents the transmission of eight standard compliant 64-QAM long term evolution advanced (LTE-A) bands and 1.4 Gb/s 4-pulse amplitude modulation (PAM) signals over 20 m of 1 mm core diameter graded-index polymethyl methacrylate plastic optical fiber. The optical transceiver consists of

Side-emitting fiber optic position sensor

Science.gov (United States)

Weiss, Jonathan D [Albuquerque, NM

2008-02-12

A side-emitting fiber optic position sensor and method of determining an unknown position of an object by using the sensor. In one embodiment, a concentrated beam of light source illuminates the side of a side-emitting fiber optic at an unknown axial position along the fiber's length. Some of this side-illuminated light is in-scattered into the fiber and captured. As the captured light is guided down the fiber, its intensity decreases due to loss from side-emission away from the fiber and from bulk absorption within the fiber. By measuring the intensity of light emitted from one (or both) ends of the fiber with a photodetector(s), the axial position of the light source is determined by comparing the photodetector's signal to a calibrated response curve, look-up table, or by using a mathematical model. Alternatively, the side-emitting fiber is illuminated at one end, while a photodetector measures the intensity of light emitted from the side of the fiber, at an unknown position. As the photodetector moves further away from the illuminated end, the detector's signal strength decreases due to loss from side-emission and/or bulk absorption. As before, the detector's signal is correlated to a unique position along the fiber.

Dynamic analysis of a bio-inspired climbing robot using ADAMS-Simulink co-simulation

Science.gov (United States)

Chattopadhyay, P.; Dikshit, H.; Majumder, A.; Ghoshal, S.; Maity, A.

2018-04-01

Climbing robot has been an area of interest since the demand of inspection of pipeline, nuclear power plant, and various big structure is growing up rapidly. This paper represents the development of a bio-inspired modular robot which mimics inchworm locomotion during climbing. In the present paper, the climbing motion is achieved only on a flat vertical plane by magnetic adhesion principle. The robot is modelled as a 4-link planar mechanism with three revolute joints actuated by DC servo motors. Sinusoidal gait pattern is used to approximate the motion of an inchworm. The dynamics of the robot is presented by using ADAMS/MATLAB co-simulation methodology. The simulation result gives the maximum value of joint torque during one complete cycle of motion. This torque value is used for the selection of servo motor specifications required to build the prototype.

Characteristics of the scientific researches in sport climbing (review of the articles, theses, programs, methodical works.

Directory of Open Access Journals (Sweden)

Sedliar Yu.V.

2011-04-01

Full Text Available The general estimation of the condition of the scientific developments will presented in sport climbing and on this base is specified the most perspective ways of scientific searching for in this area. Analysis publication reflecting different questions of preparation sport climbing athletes was organized. On base of the analysis of the special literature and coming from generally accepted in home science structure of the knowledge, was ascertained degree of the development different theoretical and practical aspect in this sphere. Discovered increase amount of the experimental studies in sport climbing.

Stair Climbing in a Quadruped Robot

OpenAIRE

Shen-Chiang Chen; Chih-Chung Ko; Cheng-Hsin Li; Pei-Chun Lin

2012-01-01

This paper reports the algorithm of trajectory planning and the strategy of four-leg coordination for quasi-static stair climbing in a quadruped robot. This development is based on the geometrical interactions between robot legs and the stair, starting from single-leg analysis, followed by two-leg collaboration, and then four-leg coordination. In addition, a brief study on the robot’s locomotion stability is also included. Finally, simulation and experimental testing were executed to evaluate...

Robot-assisted practice of gait and stair climbing in nonambulatory stroke patients.

Science.gov (United States)

Hesse, Stefan; Tomelleri, Christopher; Bardeleben, Anita; Werner, Cordula; Waldner, Andreas

2012-01-01

A novel gait robot enabled nonambulatory patients the repetitive practice of gait and stair climbing. Thirty nonambulatory patients with subacute stroke were allocated to two groups. During 60 min sessions every workday for 4 weeks, the experimental group received 30 min of robot training and 30 min of physiotherapy and the control group received 60 min of physiotherapy. The primary variable was gait and stair climbing ability (Functional Ambulation Categories [FAC] score 0-5); secondary variables were gait velocity, Rivermead Mobility Index (RMI), and leg strength and tone blindly assessed at onset, intervention end, and follow-up. Both groups were comparable at onset and functionally improved over time. The improvements were significantly larger in the experimental group with respect to the FAC, RMI, velocity, and leg strength during the intervention. The FAC gains (mean +/- standard deviation) were 2.4 +/- 1.2 (experimental group) and 1.2 +/- 1.5 (control group), p = 0.01. At the end of the intervention, seven experimental group patients and one control group patient had reached an FAC score of 5, indicating an ability to climb up and down one flight of stairs. At follow-up, this superior gait ability persisted. In conclusion, the therapy on the novel gait robot resulted in a superior gait and stair climbing ability in nonambulatory patients with subacute stroke; a higher training intensity was the most likely explanation. A large randomized controlled trial should follow.

Comparison of Genetic Algorithm and Hill Climbing for Shortest Path Optimization Mapping

Directory of Open Access Journals (Sweden)

Fronita Mona

2018-01-01

Full Text Available Traveling Salesman Problem (TSP is an optimization to find the shortest path to reach several destinations in one trip without passing through the same city and back again to the early departure city, the process is applied to the delivery systems. This comparison is done using two methods, namely optimization genetic algorithm and hill climbing. Hill Climbing works by directly selecting a new path that is exchanged with the neighbour’s to get the track distance smaller than the previous track, without testing. Genetic algorithms depend on the input parameters, they are the number of population, the probability of crossover, mutation probability and the number of generations. To simplify the process of determining the shortest path supported by the development of software that uses the google map API. Tests carried out as much as 20 times with the number of city 8, 16, 24 and 32 to see which method is optimal in terms of distance and time computation. Based on experiments conducted with a number of cities 3, 4, 5 and 6 producing the same value and optimal distance for the genetic algorithm and hill climbing, the value of this distance begins to differ with the number of city 7. The overall results shows that these tests, hill climbing are more optimal to number of small cities and the number of cities over 30 optimized using genetic algorithms.

Experimental Demonstration of Nonlinearity and Phase Noise Tolerant 16-QAM OFDM W-Band (75–110 GHz) Signal Over Fiber System

DEFF Research Database (Denmark)

Deng, Lei; Pang, Xiaodan; Tafur Monroy, Idelfonso

2014-01-01

We propose a nonlinearity and phase noise tolerant orthogonal frequency division multiplexing (OFDM) W-band signal over fiber system based on phase modulation and photonic heterodyne up-conversion techniques. By heterodyne mixing the phase-modulated optical OFDM signal with a free-running laser i...

Development of a field measurement instrument for nuclear electromagnetic pulse (NEMP) based on signal transmission through fiber

International Nuclear Information System (INIS)

Song Wenwu; Zhang Chuandong; Liu Yi; Chen Jiuchun; Fan Youwen

2007-01-01

This paper deals with design principles, development and performance of a field measurement instrument for nuclear electromagnetic pulse (EMP) based on signal transmission through fiber. To determine the minimum band width this instrument needs, we analyze cutoff spectrum of a time domain double exponential signal, employing Fast Fourier Transform (FFT), and get its inverse transform signal. Then we design the circuit of laser device and the circuit of measuring device according to previous analysis. This instrument meets requirements of related regulations. Its specifications meet requirements of NEMP hazard protection research and can be of great significance to it. (authors)

Development and Initial Validation of a Rock Climbing Craving Questionnaire (RCCQ

Directory of Open Access Journals (Sweden)

Gareth Roderique-Davies

2018-02-01

Full Text Available Conceptual similarities have been identified between experiences of extreme sports athletes and those with drug and behavioral addictions. Evidence suggests rock climbers experience craving and other withdrawal-like states when abstinent from their sport. However, no studies have attempted to quantitatively measure the craving experienced by participants of any extreme sports. Such a measure could allow a greater understanding of the craving experienced by extreme sports athletes and a comparison of these across sports (e.g., surfing and activities (e.g., drug-use. Therefore, using validated craving measures as a template, the aim of the two studies outlined here was to design and preliminarily validate a subjective multidimensional inventory that could be used to measure craving in the sports of rock-climbing and mountaineering (“RCCQ”. The aim of the first study was to investigate the factor structure of a preliminary measure of craving. Climbers (n = 407 completed the RCCQ. A 3-factor model explained 53.65% of the total variance in item scores. All three factors comprised five items each, which were conceptually labeled as “urge to climb” “negative reinforcement” and “positive reinforcement.” The aim of the second study was to validate the 15-item 3-factor RCCQ resulting from Study 1 using confirmatory factor analysis (CFA. Climbers (n = 254 completed the questionnaire under a climbing-related cue condition or a cue-neutral condition. CFA revealed a good model fit and that all individual parameter estimates were significant and standard errors were within reasonable limits once item 13 was removed from Factor 1. Study 1 supports the multi-dimensional nature of rock climbing craving and shows parallels with substance-related craving in reflecting intention and positive (desire and negative (withdrawal reinforcement. Study 2 confirms this factor structure and gives initial validation to the measure with evidence that these

Transition Analysis and Its Application to Global Path Determination for a Biped Climbing Robot

Directory of Open Access Journals (Sweden)

Haifei Zhu

2018-01-01

Full Text Available Biped climbing robots are considered good assistants and (or substitutes for human workers carrying out high-rise truss-associated routine tasks. Flexible locomotion on three-dimensional complex trusses is a fundamental skill for these robots. In particular, the capability to transit from one structural member to another is paramount for switching objects to be climbed upon. In this paper, we study member-to-member transition and its utility in global path searching for biped climbing robots. To compute operational regions for transition, hierarchical inspection of safety, reachability, and accessibility of grips is taken into account. A novel global path rapid determination approach is subsequently proposed based on the transition analysis. This scheme is efficient for finding feasible routes with respect to the overall structural environment, which also benefits the subsequent grip and motion planning. Simulations are conducted with Climbot, our self-developed biped climbing robot, to verify the efficiency of the presented method. Results show that our proposed method is able to accurately determine the operational region for transition within tens of milliseconds and can obtain global paths within seconds in general.

Analysis of second order harmonic distortion due to transmitter non-linearity and chromatic and modal dispersion of optical OFDM SSB modulated signals in SMF-MMF fiber links

Science.gov (United States)

Patel, Dhananjay; Singh, Vinay Kumar; Dalal, U. D.

2017-01-01

Single mode fibers (SMF) are typically used in Wide Area Networks (WAN), Metropolitan Area Networks (MAN) and also find applications in Radio over Fiber (RoF) architectures supporting data transmission in Fiber to the Home (FTTH), Remote Antenna Units (RAUs), in-building networks etc. Multi-mode fibers (MMFs) with low cost, ease of installation and low maintenance are predominantly (85-90%) deployed in-building networks providing data access in local area networks (LANs). The transmission of millimeter wave signals through the SMF in WAN and MAN, along with the reuse of MMF in-building networks will not levy fiber reinstallation cost. The transmission of the millimeter waves experiences signal impairments due to the transmitter non-linearity and modal dispersion of the MMF. The MMF exhibiting large modal dispersion limits the bandwidth-length product of the fiber. The second and higher-order harmonics present in the optical signal fall within the system bandwidth. This causes degradation in the received signal and an unwanted radiation of power at the RAU. The power of these harmonics is proportional to the non-linearity of the transmitter and the modal dispersion of the MMF and should be maintained below the standard values as per the international norms. In this paper, a mathematical model is developed for Second-order Harmonic Distortion (HD2) generated due to non-linearity of the transmitter and chromatic-modal dispersion of the SMF-MMF optic link. This is also verified using a software simulation. The model consists of a Mach Zehnder Modulator (MZM) that generates two m-QAM OFDM Single Sideband (SSB) signals based on phase shift of the hybrid coupler (90° and 120°). Our results show that the SSB signal with 120° hybrid coupler has suppresses the higher-order harmonics and makes the system more robust against the HD2 in the SMF-MMF optic link.

Climbing the Needs Pyramids

Directory of Open Access Journals (Sweden)

J. C. Lomas

2013-08-01

Full Text Available Abraham Maslow’s theory of human adult motivation is often represented by a pyramid image showing two proposals: First, the five needs stages in emergent order of hierarchical ascension and second, a percentage of the adult population suggested to occupy each needs tier. Specifically, Maslow proposed that adults would be motivated to satisfy their unfilled needs until they reached the hierarchy’s apex and achieved self-transcendence. Yet how adults can purposefully ascend Maslow’s pyramid through satisfying unfilled needs remains elusive. This brief article challenges this on the theory’s 70th anniversary by presenting a new image of the needs hierarchy, based on ecological design principles to support adults’ purposeful endeavors to climb the needs pyramid.

Dislocation climb and interstitial loop growth under cascade damage irradiation

International Nuclear Information System (INIS)

Woo, C.H.; Semenov, A.A.

1993-01-01

The effects of intracascade clustering and recombination in radiation damage have been considered previously in semiquantitative calculations involving vacancy accumulation at voids, within the concept of production bias. To model void swelling and microstructural evolution quantitatively, similar effects on dislocation climb and interstitial loop growth have to be considered. In this regard, at elevated temperatures (such as in the peak-swelling temperature regime), the concentration of freely migrating vacancies is much higher than that of the interstitials, owing to the evaporation from the primary vacancy clusters (i.e. those produced by intracascade clustering). It is not immediately obvious how the dislocations can be net interstitials sinks, and hence that the observed nucleation and growth of the interstitial loops at elevated temperatures can be correctly predicted as in the conventional theory. To address these basic questions, a rate theory model is formulated in this paper, which describes the dislocation climb and loop growth in the presence of intracascade primary clusters. Within this model, conservation equations for the concentrations and average radii of the two kinds of primary cluster are derived, and the corresponding steady-state concentrations and average radii are calculated. From this, the dislocation climb velocity and interstitial loop growth rate are calculated. On the basis of the results of this calculation, some of the basic questions of production bias are discussed. (Author)

Penerapan Metode Hill Climbing Pada Sistem Informasi Geografis Untuk Mencari Lintasan Terpendek

Directory of Open Access Journals (Sweden)

Eka Vickraien Dangkua

2016-04-01

Full Text Available Heuristic search methods is one of the methods commonly in use in finding the shortest path, one of which, namely the methods Hill Climbing process where testing is done using heuristic functions. Problems generally encountered is the shortest path search to solve the problem of distance can be changed into a graph structure, where the point of declaring the city and the State line that connects the two cities. From the logic so that it can locate destinations and save on travel costs. The hallmarks of this algorithm are all possible solutions will have then checked one by one from the left side, so it will be obtained solutions with optimal results. On a Hill Climbing method according to case using geographic information systems as a tool in making a decision, by way of collect, examine, and analyze information related to digital map. with a combination of Hill Climbing method and geographic information systems can result in an application that is certainly feasible for use in the search path problems.   Keywords: Hill Climbin method; digital map; Geographic Information Systems

Evolutionary Novelty versus Exaptation: Oral Kinematics in Feeding versus Climbing in the Waterfall-Climbing Hawaiian Goby Sicyopterus stimpsoni

OpenAIRE

Cullen, Joshua A.; Maie, Takashi; Schoenfuss, Heiko L.; Blob, Richard W.

2013-01-01

Species exposed to extreme environments often exhibit distinctive traits that help meet the demands of such habitats. Such traits could evolve independently, but under intense selective pressures of extreme environments some existing structures or behaviors might be coopted to meet specialized demands, evolving via the process of exaptation. We evaluated the potential for exaptation to have operated in the evolution of novel behaviors of the waterfall-climbing gobiid fish genus Sicyopterus. T...

Re-configurable digital receiver for optically envelope detected half cycle BPSK and MSK radio-on-fiber signals

DEFF Research Database (Denmark)

Guerrero Gonzalez, Neil; Prince, Kamau; Zibar, Darko

2011-01-01

We present the first known integration of a digital receiver into optically envelope detection radio-on-fiber systems. We also present a re-configurable scheme for two different types of optically envelope detected wireless signals while keeping the complexity of used optical components low. Our...... novel digital receiver consists of a digital signal processing unit integrating functions such as filtering, peak-powers detection, symbol synchronization and signal demodulation for optically envelope detected half-cycle binary phase-shift-keying and minimum-shift-keying signals. Furthermore, radio......-frequency signal down-conversion is not required in our proposed approach; simplifying evens more the optical receiver front-end. We experimentally demonstrate error-free optical transmission (bit-error rate corresponding to 10−3 related to FEC-compatible levels) for both 416.6 Mbit/s half-cycle binary phase...

Leading Organizational Change Is Like Climbing a Mountain

Science.gov (United States)

Zimmerman, Judith

2004-01-01

Leading organizational change is like climbing a mountain. Transformational leaders must prepare to lead change, understand the process and nature of change, and provide the essential gear so that those involved can be successful. The author draws on the literature and personal experiences as a hiker and change leader to provide a guide for…

Fiber Wireless Transmission of 8.3 Gb/s/ch QPSK-OFDM Signals in 75-110 GHz Band

DEFF Research Database (Denmark)

Deng, Lei; Beltrán Ramírez, Marta; Pang, Xiaodan

2012-01-01

In this paper, we present a scalable high speed Wband (75-110 GHz) fiber wireless communication system. By using an optical frequency comb generator, 3-channel 8.3 Gb/s/ch optical orthogonal frequency division multiplexing (OOFDM) baseband signals in a 15 GHz bandwidth are seamlessly translated f...

A cerebellar learning model of vestibulo-ocular reflex adaptation in wild-type and mutant mice.

Science.gov (United States)

Clopath, Claudia; Badura, Aleksandra; De Zeeuw, Chris I; Brunel, Nicolas

2014-05-21

Mechanisms of cerebellar motor learning are still poorly understood. The standard Marr-Albus-Ito theory posits that learning involves plasticity at the parallel fiber to Purkinje cell synapses under control of the climbing fiber input, which provides an error signal as in classical supervised learning paradigms. However, a growing body of evidence challenges this theory, in that additional sites of plasticity appear to contribute to motor adaptation. Here, we consider phase-reversal training of the vestibulo-ocular reflex (VOR), a simple form of motor learning for which a large body of experimental data is available in wild-type and mutant mice, in which the excitability of granule cells or inhibition of Purkinje cells was affected in a cell-specific fashion. We present novel electrophysiological recordings of Purkinje cell activity measured in naive wild-type mice subjected to this VOR adaptation task. We then introduce a minimal model that consists of learning at the parallel fibers to Purkinje cells with the help of the climbing fibers. Although the minimal model reproduces the behavior of the wild-type animals and is analytically tractable, it fails at reproducing the behavior of mutant mice and the electrophysiology data. Therefore, we build a detailed model involving plasticity at the parallel fibers to Purkinje cells' synapse guided by climbing fibers, feedforward inhibition of Purkinje cells, and plasticity at the mossy fiber to vestibular nuclei neuron synapse. The detailed model reproduces both the behavioral and electrophysiological data of both the wild-type and mutant mice and allows for experimentally testable predictions. Copyright © 2014 the authors 0270-6474/14/347203-13$15.00/0.

Piper (Piperaceae) in the Solomon Islands: the climbing species

NARCIS (Netherlands)

Gardner, R.O.

2010-01-01

Eleven climbing species of Piper in the Solomon Islands are recognized: P. abbreviatum, P. betle, P. bosnicanum, P. caninum, P. celtidiforme, P. fragile, P. insectifugum (syn. P. austrocaledonicum), P. interruptum, P. macropiper, P. majusculum, and, as the only endemic, P. sclerophloeum, for which a

Piper (Piperaceae) in the Philippine Islands: the climbing species

NARCIS (Netherlands)

Gardner, R.O.

2006-01-01

Piper in the Philippine Islands is reviewed. Fifteen climbing species are recognized (many fewer than in previous treatments) and distinguished in a key. Most are widely distributed through Malesia, with ranges that end eastwards in the Solomon Islands or Australia. Piper myrmecophilum, the only

Nutrient composition of climbing and prostrate vegetable cowpea ...

African Journals Online (AJOL)

The study evaluated the nutrient content of different accessions of two vegetable cowpea genotypes. The mineral content of the vegetable cowpea accessions were high. Potassium content of the accessions of the climbing genotype “Akidi enu” ranged from 1.25 to 1.52% with a mean value of 1.43 ± 0.13% while in the ...

In-fiber modal interferometer based on multimode and double cladding fiber segments for tunable fiber laser applications

Science.gov (United States)

Prieto-Cortés, P.; Álvarez-Tamayo, R. I.; Durán-Sánchez, M.; Castillo-Guzmán, A.; Salceda-Delgado, G.; Ibarra-Escamilla, B.; Kuzin, E. A.; Barcelata-Pinzón, A.; Selvas-Aguilar, R.

2018-02-01

We report an in-fiber structure based on the use of a multimode fiber segment and a double cladding fiber segment, and its application as spectral filter in an erbium-doped fiber laser for selection and tuning of the laser line wavelength. The output transmission of the proposed device exhibit spectrum modulation of the input signal with free spectral range of 21 nm and maximum visibility enhanced to more than 20 dB. The output spectrum of the in-fiber filter is wavelength displaced by bending application which allows a wavelength tuning of the generated laser line in a range of 12 nm. The use of the proposed in-fiber structure is demonstrated as a reliable, simple, and low-cost wavelength filter for tunable fiber lasers design and optical instrumentation applications.

Climbing Up the Technology Ladder? High-Technology Exports in China and Latin America

OpenAIRE

Gallagher, Kevin P.; Porzecanski, Roberto

2008-01-01

In this paper we determine the “dynamic revealed competitiveness position” (DRCP) of nations for high technology exports between 1980 and 2005. We find that the developed world has lost significant market share in high technology and that China has climbed the high technology ladder during this period. In 1980 China was ranked 99th of all nations in terms of the percentage of global exports in high technology. By 2005 China climbed to second place in the world, first place if high technology ...

Grain-size distribution of surface sediments of climbing and falling ...

Indian Academy of Sciences (India)

45

The climbing and falling dunes distributing in the wide valleys of China's Yarlung. 64. Zangbo River ...... Food and Agriculture Organization (FAO). 2006. The state of ... Global land use change, economic globalization, and. 450 the looming ...

Hold design supports learning and transfer of climbing fluency

NARCIS (Netherlands)

Orth, Dominic; Davids, Keith; Seifert, Ludovic

2014-01-01

Being a discipline with a broad range of genres, rock climbing is an activity where participants seek to generalize the skills they learn in different performance contexts. A training strategy for achieving skill transfer was explored in a group of experienced climbers. Specifically, we tested the

Climbing ability of teneral and sclerotized adult bed bugs and assessment of adhesive properties of the exoskeletal fluid using atomic force microscopy.

Directory of Open Access Journals (Sweden)

Kevin R Hinson

Full Text Available We observed that teneral adults (72 h, and sclerotized group 2 (S2 bed bugs (n = 30, height climbed = 2.64 cm at >72 h post molt. When heights from all climbing events were summed, teneral bed bugs (650.8 cm climbed differed significantly (P< 0.01 from recently sclerotized (82 cm climbed and sclerotized (group 1 = 104.6 cm climbed, group 2 = 107.8 cm climbed bed bugs. These findings suggested that the external surface of teneral bed bug exoskeletons possess an adhesive property. Using atomic force microscopy (AFM, we found that adhesion force of an exoskeletal (presumably molting fluid decreased almost five-fold from 88 to 17 nN within an hour of molting. Our findings may have implications for laboratory safety and the effectiveness of bed bug traps, barriers, and biomimetic-based adhesives.

Complete Spinal Accessory Nerve Palsy From Carrying Climbing Gear.

Science.gov (United States)

Coulter, Jess M; Warme, Winston J

2015-09-01

We report an unusual case of spinal accessory nerve palsy sustained while transporting climbing gear. Spinal accessory nerve injury is commonly a result of iatrogenic surgical trauma during lymph node excision. This particular nerve is less frequently injured by blunt trauma. The case reported here results from compression of the spinal accessory nerve for a sustained period-that is, carrying a load over the shoulder using a single nylon rope for 2.5 hours. This highlights the importance of using proper load-carrying equipment to distribute weight over a greater surface area to avoid nerve compression in the posterior triangle of the neck. The signs and symptoms of spinal accessory nerve palsy and its etiology are discussed. This report is particularly relevant to individuals involved in mountaineering and rock climbing but can be extended to anyone carrying a load with a strap over one shoulder and across the body. Copyright © 2015 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

Suppression of Instability on Sensing Signal of Optical Pulse Correlation Measurement in Remote Fiber Sensing

Directory of Open Access Journals (Sweden)

Hirokazu Kobayashi

2012-01-01

response and improve the accuracy of signals at the focused sensing regions. We also experimentally demonstrate remote temperature monitoring over a 30 km-long distance using a remote reference technique, and we estimate the resolution and the measurable span of the temperature variation as (1.1/L∘C and (5.9×10/L°C, respectively, where L is the length of the fiber in the sensing region.

Electrospun amplified fiber optics.

Science.gov (United States)

Morello, Giovanni; Camposeo, Andrea; Moffa, Maria; Pisignano, Dario

2015-03-11

All-optical signal processing is the focus of much research aiming to obtain effective alternatives to existing data transmission platforms. Amplification of light in fiber optics, such as in Erbium-doped fiber amplifiers, is especially important for efficient signal transmission. However, the complex fabrication methods involving high-temperature processes performed in a highly pure environment slow the fabrication process and make amplified components expensive with respect to an ideal, high-throughput, room temperature production. Here, we report on near-infrared polymer fiber amplifiers working over a band of ∼20 nm. The fibers are cheap, spun with a process entirely carried out at room temperature, and shown to have amplified spontaneous emission with good gain coefficients and low levels of optical losses (a few cm(-1)). The amplification process is favored by high fiber quality and low self-absorption. The found performance metrics appear to be suitable for short-distance operations, and the large variety of commercially available doping dyes might allow for effective multiwavelength operations by electrospun amplified fiber optics.

Purkinje Cell Signaling Deficits in Animal Models of Ataxia

Directory of Open Access Journals (Sweden)

Eriola Hoxha

2018-04-01

Full Text Available Purkinje cell (PC dysfunction or degeneration is the most frequent finding in animal models with ataxic symptoms. Mutations affecting intrinsic membrane properties can lead to ataxia by altering the firing rate of PCs or their firing pattern. However, the relationship between specific firing alterations and motor symptoms is not yet clear, and in some cases PC dysfunction precedes the onset of ataxic signs. Moreover, a great variety of ionic and synaptic mechanisms can affect PC signaling, resulting in different features of motor dysfunction. Mutations affecting Na+ channels (NaV1.1, NaV1.6, NaVβ4, Fgf14 or Rer1 reduce the firing rate of PCs, mainly via an impairment of the Na+ resurgent current. Mutations that reduce Kv3 currents limit the firing rate frequency range. Mutations of Kv1 channels act mainly on inhibitory interneurons, generating excessive GABAergic signaling onto PCs, resulting in episodic ataxia. Kv4.3 mutations are responsible for a complex syndrome with several neurologic dysfunctions including ataxia. Mutations of either Cav or BK channels have similar consequences, consisting in a disruption of the firing pattern of PCs, with loss of precision, leading to ataxia. Another category of pathogenic mechanisms of ataxia regards alterations of synaptic signals arriving at the PC. At the parallel fiber (PF-PC synapse, mutations of glutamate delta-2 (GluD2 or its ligand Crbl1 are responsible for the loss of synaptic contacts, abolishment of long-term depression (LTD and motor deficits. At the same synapse, a correct function of metabotropic glutamate receptor 1 (mGlu1 receptors is necessary to avoid ataxia. Failure of climbing fiber (CF maturation and establishment of PC mono-innervation occurs in a great number of mutant mice, including mGlu1 and its transduction pathway, GluD2, semaphorins and their receptors. All these models have in common the alteration of PC output signals, due to a variety of mechanisms affecting incoming

Comparative Effect of Forward and Backward Stair Climbing on ...

African Journals Online (AJOL)

olagbegi

The groups were not significantly different (p> 0.05) in their cardiovascular parameters at weeks 0, 4, and 8. The FSC group had ... KEY WORDS: Stair climbing, blood pressure, cardiovascular endurance ... significantly greater metabolic responses compared to ... This was taken with the subject in sitting position, with the.

An Omni-Directional Wall-Climbing Microrobot with Magnetic Wheels Directly Integrated with Electromagnetic Micromotors

Directory of Open Access Journals (Sweden)

Xiaoning Tang

2012-04-01

Full Text Available This paper presents an omni-directional wall-climbing microrobot with magnetic wheels. The integral design with an actuator and adhesive is realized by integrating stators and rotors of an MEMS-based electromagnetic micromotor with a magnetic wheel. The omni-directional wall-climbing mechanism is designed by a set of steering gears and three standard magnetic wheels. The required torque and magnetic force for microrobot movement are derived by its static analysis. The size of the magnetic wheel is optimized, with consideration of its own design constraints, by ANSOFT and Pro/Engineer simulation so as to reduce unnecessary torque consumption under the same designed load. Related experiments demonstrate that the microrobot (diameter: 26mm; height: 16.4; mass: 7.2g; load capacity: 3g we have developed has a good wall-climbing ability and flexible mobility, and it can perform visual detection in a ferromagnetic environment.

Short-pulse propagation in fiber optical parametric amplifiers

DEFF Research Database (Denmark)

Cristofori, Valentina

Fiber optical parametric amplifiers (FOPAs) are attractive because they can provide large gain over a broad range of central wavelengths, depending only on the availability of a suitable pump laser. In addition, FOPAs are suitable for the realization of all-optical signal processing functionalities...... transfer can be reduced in saturated F OPAs. In order to characterize propagation impairments such as dispersion and Kerr effect, affecting signals reaching multi-terabit per second per channel, short pulses on the order of 500 fs need to be considered. Therefore, a short pulses fiber laser source...... is implemented to obtain an all-fiber system. The advantages of all fiber-systems are related to their reliability, long-term stability and compactness. Fiber optical parametric chirped pulse amplification is promising for the amplification of such signals thanks to the inherent compatibility of FOPAs with fiber...

Applications of nonlinear fiber optics

CERN Document Server

Agrawal, Govind

2008-01-01

* The only book describing applications of nonlinear fiber optics * Two new chapters on the latest developments: highly nonlinear fibers and quantum applications* Coverage of biomedical applications* Problems provided at the end of each chapterThe development of new highly nonlinear fibers - referred to as microstructured fibers, holey fibers and photonic crystal fibers - is the next generation technology for all-optical signal processing and biomedical applications. This new edition has been thoroughly updated to incorporate these key technology developments.The bo

CLIMBING.CREACIÓN DE UNA MRCA DEPORTIVA

OpenAIRE

MESEGUER SANCHEZ, RAQUEL

2017-01-01

El presente TFG plantea el desarrollo de la imagen de marca de una empresa de ropa deportiva y la adaptación a sus productos, esta imagen plantea las connotaciones de fuerza y juventud y adaptable a cualquier tipo de deporte. Se estudian todos los valores implícitos en el branding y el proceso de elaboración. Meseguer Sanchez, R. (2017). CLIMBING.CREACIÓN DE UNA MRCA DEPORTIVA. http://hdl.handle.net/10251/92805 TFGM

Biomechanics and functional morphology of a climbing monocot

Science.gov (United States)

Hesse, Linnea; Wagner, Sarah T.; Neinhuis, Christoph

2016-01-01

Plants with a climbing growth habit possess unique biomechanical properties arising from adaptations to changing loading conditions connected with close attachment to mechanical supports. In monocot climbers, mechanical adaptation is restricted by the absence of a bifacial vascular cambium. Flagellaria indica was used to investigate the mechanical properties and adaptations of a monocot climber that, uniquely, attaches to the surrounding vegetation via leaf tendrils. Biomechanical methods such as three-point bending and torsion tests were used together with anatomical studies on tissue development, modification and distribution. In general, the torsional modulus was lower than the bending modulus; hence, torsional stiffness was less than flexural stiffness. Basal parts of mature stems showed the greatest stiffness while that of more apical stem segments levelled off. Mechanical properties were modulated via tissue maturation processes mainly affecting the peripheral region of the stem. Peripheral vascular bundles showed a reduction in the amount of conducting tissue while the proportion and density of the bundle sheath increased. Furthermore, adjacent bundle sheaths merged resulting in a dense ring of fibrous tissue. Although F. indica lacks secondary cambial growth, the climbing habit is facilitated by a complex interaction of tissue maturation and attachment. PMID:26819259

Modeling and analysis of a meso-hydraulic climbing robot with artificial muscle actuation.

Science.gov (United States)

Chapman, Edward M; Jenkins, Tyler E; Bryant, Matthew

2017-07-10

This paper presents a fully coupled electro-hydraulic model of a bio-inspired climbing robot actuated by fluidic artificial muscles (FAMs). This analysis expands upon previous FAM literature by considering not only the force and contraction characteristics of the actuator, but the complete hydraulic and electromechanical circuits as well as the dynamics of the climbing robot. This analysis allows modeling of the time-varying applied pressure, electrical current, and actuator contraction for accurate prediction of the robot motion, energy consumption, and mechanical work output. The developed model is first validated against mechanical and electrical data collected from a proof-of-concept prototype robot. The model is then employed to study the system-level sensitivities of the robot locomotion efficiency and average climbing speed to several design and operating parameters. The results of this analysis demonstrate that considering only the transduction efficiency of the FAM actuators is insufficient to maximize the efficiency of the complete robot, and that a holistic approach can lead to significant improvements in performance. © 2017 IOP Publishing Ltd.

Watch Out for Your Neighbor: Climbing onto Shrubs Is Related to Risk of Cannibalism in the Scorpion Buthus cf. occitanus.

Science.gov (United States)

Sánchez-Piñero, Francisco; Urbano-Tenorio, Fernando

The distribution and behavior of foraging animals usually imply a balance between resource availability and predation risk. In some predators such as scorpions, cannibalism constitutes an important mortality factor determining their ecology and behavior. Climbing on vegetation by scorpions has been related both to prey availability and to predation (cannibalism) risk. We tested different hypotheses proposed to explain climbing on vegetation by scorpions. We analyzed shrub climbing in Buthus cf. occitanus with regard to the following: a) better suitability of prey size for scorpions foraging on shrubs than on the ground, b) selection of shrub species with higher prey load, c) seasonal variations in prey availability on shrubs, and d) whether or not cannibalism risk on the ground increases the frequency of shrub climbing. Prey availability on shrubs was compared by estimating prey abundance in sticky traps placed in shrubs. A prey sample from shrubs was measured to compare prey size. Scorpions were sampled in six plots (50 m x 10 m) to estimate the proportion of individuals climbing on shrubs. Size difference and distance between individuals and their closest scorpion neighbor were measured to assess cannibalism risk. The results showed that mean prey size was two-fold larger on the ground. Selection of particular shrub species was not related to prey availability. Seasonal variations in the number of scorpions on shrubs were related to the number of active scorpions, but not with fluctuations in prey availability. Size differences between a scorpion and its nearest neighbor were positively related with a higher probability for a scorpion to climb onto a shrub when at a disadvantage, but distance was not significantly related. These results do not support hypotheses explaining shrub climbing based on resource availability. By contrast, our results provide evidence that shrub climbing is related to cannibalism risk.

Innovative gait robot for the repetitive practice of floor walking and stair climbing up and down in stroke patients.

Science.gov (United States)

Hesse, Stefan; Waldner, Andreas; Tomelleri, Christopher

2010-06-28

Stair climbing up and down is an essential part of everyday's mobility. To enable wheelchair-dependent patients the repetitive practice of this task, a novel gait robot, G-EO-Systems (EO, Lat: I walk), based on the end-effector principle, has been designed. The trajectories of the foot plates are freely programmable enabling not only the practice of simulated floor walking but also stair climbing up and down. The article intended to compare lower limb muscle activation patterns of hemiparetic subjects during real floor walking and stairs climbing up, and during the corresponding simulated conditions on the machine, and secondly to demonstrate gait improvement on single case after training on the machine. The muscle activation pattern of seven lower limb muscles of six hemiparetic patients during free and simulated walking on the floor and stair climbing was measured via dynamic electromyography. A non-ambulatory, sub-acute stroke patient additionally trained on the G-EO-Systems every workday for five weeks. The muscle activation patterns were comparable during the real and simulated conditions, both on the floor and during stair climbing up. Minor differences, concerning the real and simulated floor walking conditions, were a delayed (prolonged) onset (duration) of the thigh muscle activation on the machine across all subjects. Concerning stair climbing conditions, the shank muscle activation was more phasic and timely correct in selected patients on the device. The severely affected subject regained walking and stair climbing ability. The G-EO-Systems is an interesting new option in gait rehabilitation after stroke. The lower limb muscle activation patterns were comparable, a training thus feasible, and the positive case report warrants further clinical studies.

The effects of climbing cages on behaviour of female mink during the lactation period

DEFF Research Database (Denmark)

Lidfors, L.; Axelsson, H.; Loberg, J.

2012-01-01

=46) or standard cages (2.550 cm², n=44). Behavioural observations were made four weeks before birth until kits were nine weeks old with one-zero sampling during two hours before feeding. During week 1-4 after females had given birth they were mostly recorded in the nest box and there were......The aim was to investigate if there were differences in behaviour of female mink when kept in a climbing cage compared with a standard cage during the lactation period. The study was carried out on 90 mink of the colour type "black cross". Females were housed in either climbing cages (4.350 cm², n...... no differences between cage types. Week 5-8 after giving birth females in climbing cages were less in the nest box, less active out in the cage and had fewer abnormal behaviours, but were on the platforms and more inactive out in the cage. In the bottom cage females were more often walking, grooming and inactive...

The CLIMB Geoportal - A web-based dissemination and documentation platform for hydrological modelling data

Science.gov (United States)

Blaschek, Michael; Gerken, Daniel; Ludwig, Ralf; Duttmann, Rainer

2015-04-01

Geoportals are important elements of spatial data infrastructures (SDIs) that are strongly based on GIS-related web services. These services are basically meant for distributing, documenting and visualizing (spatial) data in a standardized manner; an important but challenging task especially in large scientific projects with a high number of data suppliers and producers from various countries. This presentation focuses on introducing the free and open-source based geoportal solution developed within the research project CLIMB (Climate Induced Changes on the Hydrology of Mediterranean Basins, www.climb-fp7.eu) that serves as the central platform for interchanging project-related spatial data and information. In this collaboration, financed by the EU-FP7-framework and coordinated at the LMU Munich, 21 partner institutions from nine European and non-European countries were involved. The CLIMB Geoportal (lgi-climbsrv.geographie.uni-kiel.de) stores and provides spatially distributed data about the current state and future changes of the hydrological conditions within the seven CLIMB test sites around the Mediterranean. Hydrological modelling outcome - validated by the CLIMB partners - is offered to the public in forms of Web Map Services (WMS), whereas downloading the underlying data itself through Web Coverage Services (WCS) is possible for registered users only. A selection of common indicators such as discharge, drought index as well as uncertainty measures including their changes over time were used in different spatial resolution. Besides map information, the portal enables the graphical display of time series of selected variables calculated by the individual models applied within the CLIMB-project. The implementation of the CLIMB Geoportal is finally based on version 2.0c5 of the open source geospatial content management system GeoNode. It includes a GeoServer instance for providing the OGC-compliant web services and comes with a metadata catalog (pycsw) as well

On the development a pneumatic four-legged mechanism autonomous vertical wall climbing robot

International Nuclear Information System (INIS)

Mohamad Shukri Zainal Abidin; Shamsudin H.M. Amin . shukri@suria.fke.utm.my

1999-01-01

The paper describes the design of a prototype legged mechanism together with suction mechanism, the mechanical design, on-board controller and an initial performance test. The design is implemented in the form of a pneumatically powered multi-legged robot equipped with suction pads at the sole of the feet for wall climbing purpose. The whole mechanism and suction system is controlled by controller which is housed on-board the robot. The gait of the motion depended on the logic control patterns as dictated by the controller. The robot is equipped with sensors both at the front and rear ends that function as an obstacle avoidance facility. Once objects are detected, signals are sent to the controller to start an evasive action that is to move in the opposite direction. The mechanism has been tested and initial results have shown promising potential for an autonomous mobile. (Author)

Psychological profile of Turkish rock climbers: an examination of climbing experience and route difficulty.

Science.gov (United States)

Aşçi, F Hülya; Demirhan, Giyasettin; Dinç, S Cem

2007-06-01

The purpose of this study was to examine sensation seeking, physical self-perception, and intrinsic and extrinsic motives of rock climbers and to compare these psychological constructs with respect to their years of climbing experience and the difficulty of their climbing routes. 64 climbers (M age=29.1 yr., SD=6.4) voluntarily participated in this study. The Arnett Inventory of Sensation Seeking (AISS), Physical Self-Description Questionnaire (PSDQ), and Sport Motivation Scale (SMS) were administered to the rock climbers. Analysis indicated that the mean score of rock climbers on the Novelty subscale of the Sensation Seeking Scale was 33.9 (SD= 3.6) and mean value on the Intensity subscale was 29.2 (SD=5.2). The mean scores of rock climbers on the PSDQ ranged between 3.9 (SD= 1.0, Physical Activity) and 5.1 (SD= 1.1, Body Fat). Descriptive analysis indicated that the highest mean score of rock climbers on the SMS was obtained in Intrinsic motivation to Experience Stimulation (5.7, SD= 0.9). The independent sample t test showed no significant differences in sensation seeking, physical self-perception, and sport motivation with regard to years of climbing experience and route difficulty (p>.05). It may be concluded that sensation seeking in climbers is high, and they have internal motivational orientation and positive physical self-perception; their competence in climbing has no obvious relationship to these variables.

Innovative gait robot for the repetitive practice of floor walking and stair climbing up and down in stroke patients

Directory of Open Access Journals (Sweden)

Waldner Andreas

2010-06-01

Full Text Available Abstract Background Stair climbing up and down is an essential part of everyday's mobility. To enable wheelchair-dependent patients the repetitive practice of this task, a novel gait robot, G-EO-Systems (EO, Lat: I walk, based on the end-effector principle, has been designed. The trajectories of the foot plates are freely programmable enabling not only the practice of simulated floor walking but also stair climbing up and down. The article intended to compare lower limb muscle activation patterns of hemiparetic subjects during real floor walking and stairs climbing up, and during the corresponding simulated conditions on the machine, and secondly to demonstrate gait improvement on single case after training on the machine. Methods The muscle activation pattern of seven lower limb muscles of six hemiparetic patients during free and simulated walking on the floor and stair climbing was measured via dynamic electromyography. A non-ambulatory, sub-acute stroke patient additionally trained on the G-EO-Systems every workday for five weeks. Results The muscle activation patterns were comparable during the real and simulated conditions, both on the floor and during stair climbing up. Minor differences, concerning the real and simulated floor walking conditions, were a delayed (prolonged onset (duration of the thigh muscle activation on the machine across all subjects. Concerning stair climbing conditions, the shank muscle activation was more phasic and timely correct in selected patients on the device. The severely affected subject regained walking and stair climbing ability. Conclusions The G-EO-Systems is an interesting new option in gait rehabilitation after stroke. The lower limb muscle activation patterns were comparable, a training thus feasible, and the positive case report warrants further clinical studies.

Quartz fiber calorimeter

International Nuclear Information System (INIS)

Akchurin, N.; Doulas, S.; Ganel, O.; Gershtein, Y.; Gavrilov, V.; Kolosov, V.; Kuleshov, S.; Litvinsev, D.; Merlo, J.-P.; Onel, Y.; Osborne, D.; Rosowsky, A.; Stolin, V.; Sulak, L.; Sullivan, J.; Ulyanov, A.; Wigmans, R.; Winn, D.

1996-01-01

A calorimeter with optical quartz fibers embedded into an absorber matrix was proposed for the small angle region of the CMS detector at LHC (CERN). This type of calorimeter is expected to be radiation hard and to produce extremely fast signal. Some results from beam tests of the quartz fiber calorimeter prototype are presented. (orig.)

Multi-Stress Monitoring System with Fiber-Optic Mandrels and Fiber Bragg Grating Sensors in a Sagnac Loop.

Science.gov (United States)

Kim, Hyunjin; Sampath, Umesh; Song, Minho

2015-07-29

Fiber Bragg grating sensors are placed in a fiber-optic Sagnac loop to combine the grating temperature sensors and the fiber-optic mandrel acoustic emission sensors in single optical circuit. A wavelength-scanning fiber-optic laser is used as a common light source for both sensors. A fiber-optic attenuator is placed at a specific position in the Sagnac loop in order to separate buried Bragg wavelengths from the Sagnac interferometer output. The Bragg wavelength shifts are measured with scanning band-pass filter demodulation and the mandrel output is analyzed by applying a fast Fourier transform to the interference signal. This hybrid-scheme could greatly reduce the size and the complexity of optical circuitry and signal processing unit, making it suitable for low cost multi-stress monitoring of large scale power systems.

Radio-over-Fiber Transmission Using Vortex Modes

DEFF Research Database (Denmark)

Tatarczak, Anna; Lu, Xiaofeng; Rommel, Simon

2015-01-01

This paper demonstrates experimentally the distribution of radio-over-fiber (RoF) signals using orbital angular momentum (OAM) of light over standard OM4 multimode fiber (MMF) at 850 nm wavelength. Five independent OAM modes are used to convey RoF signals in the microwave regime showing robust pe...

Angle-tip Fiber Probe as Humidity Sensor

Directory of Open Access Journals (Sweden)

Pabitra NATH

2010-05-01

Full Text Available In this paper, I present a simple fiber optic relative humidity sensor (FORHS using an angled-tip multimode optical fiber. The sensing region is fabricated by coating moisture sensitive Cobalt Chloride (CoCl2 doped polyvinyl alcohol (PVA film on the surface of fiber optic tip. Light signal introducing from flat-end of the fiber is back-reflected at the fiber tip-air interface by the effect of total internal refection. The change of relative humidity (RH in the outstanding medium affects of evanescent field absorption at the fiber tip-sensing film interface thus, modulates the back-reflected signal. With the present sensing investigation, RH ranging from 5 % to 95 % can be measured with high degree of repeatability and has a fast response time of about 2 seconds.

To be active through indoor-climbing: an exploratory feasibility study in a group of children with cerebral palsy and typically developing children

DEFF Research Database (Denmark)

Christensen, Mark Schram; Jensen, Thor; Voigt, Camilla B.

2017-01-01

beneficial effects of climbing activities in populations with functional and/or cognitive challenges. The aim of this study was therefore to test the feasibility of an intensive 3 weeks indoor-climbing training program in children with CP and typically developing (TD) peers. In addition we evaluated possible...... indoor-climbing training sessions, and climbing abilities were measured. The participants were tested in a series of physiological, psychological and cognitive tests: two times prior to and one time following the training in order to explore possible effects of the intervention.Results: The children...... in cognitive abilities or psychological well-being in any of the groups.Conclusions: These findings show that it is possible to use climbing as means to make children with CP physically active. The improved motor abilities obtained through the training is likely reflected by increased synchronization between...

Neuropharmacologic characterization of strychnine seizure potentiation in the inferior olive lesioned rat

International Nuclear Information System (INIS)

Anderson, M.C.

1988-01-01

Cerebellar stimulation is associated with anticonvulsant activity in several animal models. There are two afferent inputs to cerebellar Purkinje cells: (1) parallel fibers, which relay mossy fiber input, from brainstem, spinal cord, cerebral cortex and cerebellum, and (2) climbing fibers, arising from the inferior olive. Both climbing and parallel fibers release excitatory amino acid neurotransmitters, which stimulate Purkinje cells and cause GABA release in the deep cerebellar nuclei. Climbing fibers also exert tonic inhibition over Purkinje cell activity by producing an absolute refractory period following stimulation, rendering Purkinje cells unresponsive to parallel fibers. Climbing fiber deafferentation by bilateral inferior olive lesions produced a specific decrease in threshold for strychnine-seizures in the rat. Inferior olive lesions produced no change in threshold to seizures induced by picrotoxin, bicuculline or pentylenetetrazole. Inferior olive lesions also produced abnormal motor behavior including, myoclonus, backward locomotion and hyperextension, which was significantly aggravated by strychnine, brucine, picrotoxin, bicuculline and pentylenetetrazole. Inferior olive lesions produced a significant increase in quisqualate sensitive [ 3 H]AMPA ((Rs)-alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid) binding to cerebellar membranes. AMPA is a glutamate analog with high affinity for quisqualate sensitive receptors

The Secreted Protein C1QL1 and Its Receptor BAI3 Control the Synaptic Connectivity of Excitatory Inputs Converging on Cerebellar Purkinje Cells

Directory of Open Access Journals (Sweden)

Séverine M. Sigoillot

2015-02-01

Full Text Available Precise patterns of connectivity are established by different types of afferents on a given target neuron, leading to well-defined and non-overlapping synaptic territories. What regulates the specific characteristics of each type of synapse, in terms of number, morphology, and subcellular localization, remains to be understood. Here, we show that the signaling pathway formed by the secreted complement C1Q-related protein C1QL1 and its receptor, the adhesion-GPCR brain angiogenesis inhibitor 3 (BAI3, controls the stereotyped pattern of connectivity established by excitatory afferents on cerebellar Purkinje cells. The BAI3 receptor modulates synaptogenesis of both parallel fiber and climbing fiber afferents. The restricted and timely expression of its ligand C1QL1 in inferior olivary neurons ensures the establishment of the proper synaptic territory for climbing fibers. Given the broad expression of C1QL and BAI proteins in the developing mouse brain, our study reveals a general mechanism contributing to the formation of a functional brain.

Fiber-ring laser-based intracavity photoacoustic spectroscopy for trace gas sensing.

Science.gov (United States)

Wang, Qiang; Wang, Zhen; Chang, Jun; Ren, Wei

2017-06-01

We demonstrated a novel trace gas sensing method based on fiber-ring laser intracavity photoacoustic spectroscopy. This spectroscopic technique is a merging of photoacoustic spectroscopy (PAS) with a fiber-ring cavity for sensitive and all-fiber gas detection. A transmission-type PAS gas cell (resonant frequency f0=2.68  kHz) was placed inside the fiber-ring laser to fully utilize the intracavity laser power. The PAS signal was excited by modulating the laser wavelength at f0/2 using a custom-made fiber Bragg grating-based modulator. We used this spectroscopic technique to detect acetylene (C2H2) at 1531.6 nm as a proof of principle. With a low Q-factor (4.9) of the PAS cell, our sensor achieved a good linear response (R2=0.996) to C2H2 concentration and a minimum detection limit of 390 ppbv at 2-s response time.

Climbing walls as multitasking sites of geo(morpho)logical interests: Italian examples from the Western Alps and Sardinia

Science.gov (United States)

Bollati, Irene; Fossati, Maria; Panizza, Valeria; Pelfini, Manuela; Zanoletti, Enrico; Zucali, Michele

2015-04-01

Geosites and in particular geomorphosites have been recently more and more used as base for educational activities in Earth Sciences and to enhance the geodiversity of a territory. Their attributes acquire a greater value and become especially appreciable when associated with field and outdoor activities. Frequently rock walls represent key sites for geological and gemorphological researches due to the wide outcrops of rocks where mineralogical composition and structures are very evident as well as landforms deriving from the modeling of outcrops surfaces. Where the rock walls are equipped for climbing activities they may be considered open-air laboratories useful to get in touch with the different features of rocks that condition progression on climbing routes. Due to these two aspects, geohistorical importance and educational exemplarity contribute to the increase of the scientific value and, as a consequence, of the global value of these sites as geosites. Geomorphosites from climbing sites allow to realize educational projects with different goals: 1) Recent researches in the Western Italian Alps have been conducted to make a census of climbing rock cliffs along the Ossola Valley (Verbanio-Cusio-Ossola Province, Italy) and to operate a choice of the ones characterized by high educational value (considering easy accessibility, grades for experts and beginners and the good exposition of rock features), representativeness, geohistorical importance, high cultural and socio-economic values, in order to propose an educational project addressed to students of an Italian secondary school aimed at introducing the three great families of rocks (magmatic, metamorphic and sedimentary); 2) The Eclogitic Micaschist Complex of the Austroalpine Domain (Montestrutto climbing wall, Turin Province, Italy) has been investigated in order to i) reconstruct the deformation stages at local scales along the sport climbing wall and the relationships between geological elements and

Optical characteristics of modified fiber tips in single fiber, laser Doppler flowmetry

Science.gov (United States)

Oberg, P. Ake; Cai, Hongming; Rohman, Hakan; Larsson, Sven-Erik

1994-02-01

Percutaneous laser Doppler flowmetry (LDF) and bipolar surface electromyography (EMG) were used simultaneously for measurement of skeletal muscle (trapezius) perfusion in relation to static load and fatigue. On-line computer (386 SX) processing of the LDF- and EMG- signals made possible interpretation of the relationship between the perfusion and the activity of the muscle. The single fiber laser Doppler technique was used in order to minimize the trauma. A ray-tracing program was developed in the C language by which the optical properties of the fiber and fiber ends could be simulated. Isoirradiance graphs were calculated for three fiber end types and the radiance characteristics were measured for each fiber end. The three types of fiber-tips were evaluated and compared in flow model measurements.

The effect of climbing Mount Everest on spleen contraction and increase in hemoglobin concentration during breath holding and exercise.

Science.gov (United States)

Engan, Harald K; Lodin-Sundström, Angelica; Schagatay, Fanny; Schagatay, Erika

2014-04-01

Release of stored red blood cells resulting from spleen contraction improves human performance in various hypoxic situations. This study determined spleen volume resulting from two contraction-evoking stimuli: breath holding and exercise before and after altitude acclimatization during a Mount Everest ascent (8848 m). Eight climbers performed the following protocol before and after the climb: 5 min ambient air respiration at 1370 m during rest, 20 min oxygen respiration, 20 min ambient air respiration at 1370 m, three maximal-effort breath holds spaced by 2 min, 10 min ambient air respiration, 5 min of cycling at 100 W, and finally 10 min ambient air respiration. We measured spleen volume by ultrasound and capillary hemoglobin (HB) concentration after each exposure, and heart rate (HR) and arterial oxygen saturation (Sao2) continuously. Mean (SD) baseline spleen volume was unchanged at 213 (101) mL before and 206 (52) mL after the climb. Before the climb, spleen volume was reduced to 184 (83) mL after three breath holds, and after the climb three breath holds resulted in a spleen volume of 132 (26) mL (p=0.032). After exercise, the preclimb spleen volume was 186 (89) mL vs. 112 (389) mL) after the climb (p=0.003). Breath hold duration and cardiovascular responses were unchanged after the climb. We concluded that spleen contraction may be enhanced by altitude acclimatization, probably reflecting both the acclimatization to chronic hypoxic exposure and acute hypoxia during physical work.

Low-latency fiber-millimeter-wave system for future mobile fronthauling

Science.gov (United States)

Tien Dat, Pham; Kanno, Atsushi; Yamamoto, Naokatsu; Kawanishi, Tetsuya

2016-02-01

A seamless combination of fiber and millimeter-wave (MMW) systems can be very attractive for future heterogeneous mobile networks such as 5G because of its flexibility and high bandwidth. Analog mobile signal transmission over seamless fiber-MMW systems is very promising to reduce the latency and the required band-width, and to simplify the systems. However, stable and high-performance seamless systems are indispensable to conserve the quality of the analog signal transmission. In this paper, we present several technologies to develop such seamless fiber-MMW systems. In the downlink direction, a high-performance system can be realized using a high-quality optical MMW signal generator and a self-homodyne MMW signal detector. In the uplink direction, a cascade of radio-on-radio and radio-over-fiber systems using a burst-mode optical amplifier can support bursty radio signal transmission. A full-duplex transmission with negligible interference effects can be realized using frequency multiplexing in the radio link and wavelength-division multiplexing in the optical link. A high-spectral efficiency MMW-over-fiber system using an intermediate frequency-over-fiber system and a high-quality remote delivery of a local oscillator signal is highly desirable to reduce the costs.

Full-duplex transmission of IEEE 802.11ac-compliant MIMO WLAN signals over a 2-km 7-core fiber

NARCIS (Netherlands)

Fan, Yuting; Li, Jianqiang; Lei, Yi; Tang, Ming; Yin, Feifei; Dai, Yitang; Xu, Kun

2017-01-01

In this Letter, we experimentally demonstrate a full-duplex transmission system of IEEE 802.11ac-compliant multiple-input multiple-output (MIMO) signals over a 2-km 7-core fiber for in-building wireless local-area network (WLAN) distributed antenna systems. For full-duplex 3 � 3 MIMO

Polymer fiber detectors for photoacoustic imaging

Science.gov (United States)

Grün, Hubert; Berer, Thomas; Pühringer, Karoline; Nuster, Robert; Paltauf, Günther; Burgholzer, Peter

2010-02-01

Photoacoustic imaging is a novel imaging method for medical and biological applications, combining the advantages of Diffuse Optical Imaging (high contrast) and Ultrasonic Imaging (high spatial resolution). A short laser pulse hits the sample. The absorbed energy causes a thermoelastic expansion and thereby launches a broadband ultrasonic wave (photoacoustic signal). The distribution of absorbed energy density is reconstructed from measurements of the photoacoustic signals around the sample. For collecting photoacoustic signals either point like or extended, integrating detectors can be used. The latter integrate the pressure at least in one dimension, e.g. along a line. Thereby, the three dimensional imaging problem is reduced to a two dimensional problem. For a tomography device consisting of a scanning line detector and a rotating sample, fiber-based detectors made of polymer have been recently introduced. Fiber-based detectors are easy to use and possess a constant, high spatial resolution over their entire active length. Polymer fibers provide a better impedance matching and a better handling compared with glass fibers which were our first approach. First measurement results using polymer fiber detectors and some approaches for improving the performance are presented.

Electrochromic fiber-shaped supercapacitors.

Science.gov (United States)

Chen, Xuli; Lin, Huijuan; Deng, Jue; Zhang, Ye; Sun, Xuemei; Chen, Peining; Fang, Xin; Zhang, Zhitao; Guan, Guozhen; Peng, Huisheng

2014-12-23

An electrochromic fiber-shaped super-capacitor is developed by winding aligned carbon nanotube/polyaniline composite sheets on an elastic fiber. The fiber-shaped supercapacitors demonstrate rapid and reversible chromatic transitions under different working states, which can be directly observed by the naked eye. They are also stretchable and flexible, and are woven into textiles to display designed signals in addition to storing energy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using optical fibers with different modes to improve the signal-to-noise ratio of diffuse correlation spectroscopy flow-oximeter measurements

OpenAIRE

He, Lian; Lin, Yu; Shang, Yu; Shelton, Brent J.; Yu, Guoqiang

2013-01-01

The dual-wavelength diffuse correlation spectroscopy (DCS) flow-oximeter is an emerging technique enabling simultaneous measurements of blood flow and blood oxygenation changes in deep tissues. High signal-to-noise ratio (SNR) is crucial when applying DCS technologies in the study of human tissues where the detected signals are usually very weak. In this study, single-mode, few-mode, and multimode fibers are compared to explore the possibility of improving the SNR of DCS flow-oximeter measure...

Development of non-contract fiber jumper cord and evaluation of light transmission performance

International Nuclear Information System (INIS)

Kim, Heon Young; Kang, Dong Hoon

2016-01-01

Recently, fiber optic sensors, which have many advantages are being applied in various fields by replacing conventional electric sensors. To transmit the light signals between an interrogator and a sensor head, optical components such as an optical adapt or and optical jumper cords are generally used. When signals are transmitted using an adapt or, the end surface of each jumper cord is faced together. If alien substances exist on the core surface of an optical fiber, those can cause light transmission loss and signal disappearance. For this reason, non-contact fiber jumper cords are developed to overcome the problems that require continual attention. The light transmission performance of non-contact fiber jumper cords are also evaluated. From the test results, conventional fiber jumper cords are unable to transmit the signals over 2 mm cavity between the ends of both cords. Otherwise, non-contact fiber jumper cords can transmit the signals with stability up to the cavity of 7 mm though they have more transmission loss than the conventional ones. Consequently, non-contact fiber jumper cords that have better signal stability than conventional ones in environments are highly recommended in field applications, especially if they play a role as a cable for signal transmission between fiber optic sensors

Development of non-contract fiber jumper cord and evaluation of light transmission performance

Energy Technology Data Exchange (ETDEWEB)

Kim, Heon Young; Kang, Dong Hoon [Advanced Materials Research Team, Korea Railroad Research Institute, Uiwang (Korea, Republic of)

2016-10-15

Recently, fiber optic sensors, which have many advantages are being applied in various fields by replacing conventional electric sensors. To transmit the light signals between an interrogator and a sensor head, optical components such as an optical adapt or and optical jumper cords are generally used. When signals are transmitted using an adapt or, the end surface of each jumper cord is faced together. If alien substances exist on the core surface of an optical fiber, those can cause light transmission loss and signal disappearance. For this reason, non-contact fiber jumper cords are developed to overcome the problems that require continual attention. The light transmission performance of non-contact fiber jumper cords are also evaluated. From the test results, conventional fiber jumper cords are unable to transmit the signals over 2 mm cavity between the ends of both cords. Otherwise, non-contact fiber jumper cords can transmit the signals with stability up to the cavity of 7 mm though they have more transmission loss than the conventional ones. Consequently, non-contact fiber jumper cords that have better signal stability than conventional ones in environments are highly recommended in field applications, especially if they play a role as a cable for signal transmission between fiber optic sensors.

Experimental investigation of saturation effect on pump-to-signal intensity modulation transfer in single-pump phase-insensitive fiber optic parametric amplifiers

DEFF Research Database (Denmark)

Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke

2013-01-01

We present an experimental characterization of how signal gain saturation affects the transfer of intensity modulation from the pump to the signal in single-pump, phase-insensitive fiber optic parametric amplifiers (FOPAs). In this work, we demonstrate experimentally for the first time, to our...... knowledge, how gain saturation of a FOPA reduces the noise contribution due to the transfer of pump power fluctuations to the signal. In a particular example, it is shown that the transferred noise is significantly reduced by a factor of 3, while the FOPA gain remains above 10 dB....

Ask Dr. Sue: Tree Climbing and Care of Sand Play Areas.

Science.gov (United States)

Aronson, Susan S.

1993-01-01

Discusses safety aspects of tree climbing and the use of sand in outdoor play areas at day care centers. Specifies ways to prune trees so that they are unclimbable and methods for maintaining sand areas. Includes a recipe for sand disinfectant. (MDM)

Umbrella Wheel - a stair-climbing and obstacle-handling wheel design concept

DEFF Research Database (Denmark)

Iversen, Simon; Jouffroy, Jerome

2017-01-01

This paper proposes a new design for stair-climbing using a wheel that can split into segments and walk up stairs or surmount other obstacles often found where humans traverse, while still being able to retain a perfectly round shape for traveling on smooth ground. Using this change of configurat......This paper proposes a new design for stair-climbing using a wheel that can split into segments and walk up stairs or surmount other obstacles often found where humans traverse, while still being able to retain a perfectly round shape for traveling on smooth ground. Using this change...... of configuration, staircases with a wide range of dimensions can be covered efficiently and safely. The design, named Umbrella Wheel, can consist of as many wheel segments as desired, and as few as two. A smaller or higher number of wheel segments has advantages and disadvantages depending on the specific...

Stochastic phenomena in a fiber Raman amplifier

Energy Technology Data Exchange (ETDEWEB)

Kalashnikov, Vladimir [Aston Institute of Photonic Technologies, Aston University, Birmingham (United Kingdom); Institute of Photonics, Vienna University of Technology (Austria); Sergeyev, Sergey V. [Aston Institute of Photonic Technologies, Aston University, Birmingham (United Kingdom); Ania-Castanon, Juan Diego [Instituto de Optica CSIC, Madrid (Spain); Jacobsen, Gunnar [Acreo, Kista (Sweden); Popov, Sergei [Royal Institute of Technology (KTH), Stockholm (Sweden)

2017-01-15

The interplay of such cornerstones of modern nonlinear fiber optics as a nonlinearity, stochasticity and polarization leads to variety of the noise induced instabilities including polarization attraction and escape phenomena harnessing of which is a key to unlocking the fiber optic systems specifications required in high resolution spectroscopy, metrology, biomedicine and telecommunications. Here, by using direct stochastic modeling, the mapping of interplay of the Raman scattering-based nonlinearity, the random birefringence of a fiber, and the pump-to-signal intensity noise transfer has been done in terms of the fiber Raman amplifier parameters, namely polarization mode dispersion, the relative intensity noise of the pump laser, fiber length, and the signal power. The obtained results reveal conditions for emergence of the random birefringence-induced resonance-like enhancement of the gain fluctuations (stochastic anti-resonance) accompanied by pulse broadening and rare events in the form of low power output signals having probability heavily deviated from the Gaussian distribution. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Space-division-multiplexed transmission of 3x3 multiple-input multiple-output wireless signals over conventional graded-index multimode fiber

NARCIS (Netherlands)

Lei, Yi; Li, Jianqiang; Fan, Yuting; Yu, Dawei; Fu, Songnian; Yin, Feifei; Dai, Yitang; Xu, Kun

2016-01-01

In this paper, we experimentally demonstrate space-division-multiplexed (SDM) transmission of IEEE 802.11ac-compliant 3-spatial-stream WLAN signals over 3 spatial modes of conventional 50um graded-index (GI) multimode fiber (MMF) employing non-mode-selective 3D-waveguide photonic lantern. Two kinds

Polymer microstructured fibers for guiding of THz radiation

DEFF Research Database (Denmark)

Nielsen, Kristian; Bang, Ole; Jepsen, Peter Uhd

2010-01-01

THz radiation, including low-loss transport of THz signals [1] between high-speed devices, integrated components for manipulation of THz light [2], such as power splitters, polarization management, and frequency filters, and confinement of the electric field of a THz signal in a small volume, enabling...... the facets of the fiber have allowed a direct visualization of the guided modes in the fiber [5]. We will discuss the optimal material choice for various kinds of polymer-based fibers, including solid-core and air-core photonic crystal fibers, and show examples of characterization of such components. We...

relative performance of staking techniques on yield of climbing bean

African Journals Online (AJOL)

ACSS

Common bean (Phaseolus vulgaris L.) is an important staple grain legume in the Great Lakes Region of Africa. In addition, it is a major source of proteins, energy and micro-nutrients (e.g. Fe and Zn), especially for smallholder farmers. The climbing bean is particularly more productive, an efficient land user and tolerant to ...

Bi-directional ultrasonic wave coupling to FBGs in continuously bonded optical fiber sensing.

Science.gov (United States)

Wee, Junghyun; Hackney, Drew; Bradford, Philip; Peters, Kara

2017-09-01

Fiber Bragg grating (FBG) sensors are typically spot-bonded onto the surface of a structure to detect ultrasonic waves in laboratory demonstrations. However, to protect the rest of the optical fiber from any environmental damage during real applications, bonding the entire length of fiber, called continuous bonding, is commonly done. In this paper, we investigate the impact of continuously bonding FBGs on the measured Lamb wave signal. In theory, the ultrasonic wave signal can bi-directionally transfer between the optical fiber and the plate at any adhered location, which could potentially produce output signal distortion for the continuous bonding case. Therefore, an experiment is performed to investigate the plate-to-fiber and fiber-to-plate signal transfer, from which the signal coupling coefficient of each case is theoretically estimated based on the experimental data. We demonstrate that the two coupling coefficients are comparable, with the plate-to-fiber case approximately 19% larger than the fiber-to-plate case. Finally, the signal waveform and arrival time of the output FBG responses are compared between the continuous and spot bonding cases. The results indicate that the resulting Lamb wave signal output is only that directly detected at the FBG location; however, a slight difference in signal waveform is observed between the two bonding configurations. This paper demonstrates the practicality of using continuously bonded FBGs for ultrasonic wave detection in structural health monitoring (SHM) applications.

Memory effects and systematic errors in the RL signal from fiber coupled Al2O3:C for medical dosimetry

DEFF Research Database (Denmark)

Damkjær, Sidsel Marie Skov; Andersen, Claus Erik

2010-01-01

This review describes 40 years of experience gained at Risø The radioluminescence (RL) signal from fiber coupled Al2O3:C can be used for real-time in vivo dosimetry during radiotherapy. RL generally provides measurements with a reproducibility of 2% (one standard deviation). However, we have...

Distributed mechatronics controller for modular wall climbing robot

CSIR Research Space (South Africa)

Tlale, NS

2006-07-01

Full Text Available - climbing robot for inspection in nuclear power plants.”, Proc. IEEE Int. Conf. on Robotics and Automation, pp. 409-1414. (Chen 2001) Chen, D-. J., 2001, “Architecture for Systematic Development of Mechatronics Software Systems”, Licentiate Thesis... provide a more cost effective solution to the problem (Luk et al 1991). Such robots are termed service robots by the International Service Robot Association (ISRA) (Pransky 1996). They are defined as machines that sense, think, and act to benefit (or...

Influence of skew rays on the sensitivity and signal-to-noise ratio of a fiber-optic surface-plasmon-resonance sensor: a theoretical study

International Nuclear Information System (INIS)

Dwivedi, Yogendra S.; Sharma, Anuj K.; Gupta, Banshi D.

2007-01-01

We have theoretically analyzed the influence of skew rays on the performance of a fiber-optic sensor based on surface plasmon resonance. The performance of the sensor has been evaluated in terms of its sensitivity and signal-to-noise ratio (SNR). The theoretical model for skewness dependence includes the material dispersion in fiber cores and metal layers, simultaneous excitation of skew rays, and meridional rays in the fiber core along with all guided rays launching from a collimated light source. The effect of skew rays on the SNR and the sensitivity of the sensor with two different metals has been compared. The same comparison is carried out for the different values of design parameters such as numerical aperture, fiber core diameter, and the length of the surface-plasmon-resonance (SPR)active sensing region. This detailed analysis for the effect of skewness on the SNR and the sensitivity of the sensor leads us to achieve the best possible performance from a fiber-optic SPR sensor against the skewness in the optical fiber

Balancing on the Edge: An Approach to Leadership and Resiliency that Combines Rock Climbing with Four Key Touch Points

Science.gov (United States)

Winkler, Harold E.

2005-01-01

In this article, the author compares leadership and resiliency with rock climbing. It describes the author's personal experience on a rock climbing adventure with his family and how it required application of similar elements as that of leadership and resiliency. The article contains the following sections: (1) Being Resilient; (2) Points of…

Novel Fiber-Optic Ring Acoustic Emission Sensor.

Science.gov (United States)

Wei, Peng; Han, Xiaole; Xia, Dong; Liu, Taolin; Lang, Hao

2018-01-13

Acoustic emission technology has been applied to many fields for many years. However, the conventional piezoelectric acoustic emission sensors cannot be used in extreme environments, such as those with heavy electromagnetic interference, high pressure, or strong corrosion. In this paper, a novel fiber-optic ring acoustic emission sensor is proposed. The sensor exhibits high sensitivity, anti-electromagnetic interference, and corrosion resistance. First, the principle of a novel fiber-optic ring sensor is introduced. Different from piezoelectric and other fiber acoustic emission sensors, this novel sensor includes both a sensing skeleton and a sensing fiber. Second, a heterodyne interferometric demodulating method is presented. In addition, a fiber-optic ring sensor acoustic emission system is built based on this method. Finally, fiber-optic ring acoustic emission experiments are performed. The novel fiber-optic ring sensor is glued onto the surface of an aluminum plate. The 150 kHz standard continuous sinusoidal signals and broken lead signals are successfully detected by the novel fiber-optic ring acoustic emission sensor. In addition, comparison to the piezoelectric acoustic emission sensor is performed, which shows the availability and reliability of the novel fiber-optic ring acoustic emission sensor. In the future, this novel fiber-optic ring acoustic emission sensor will provide a new route to acoustic emission detection in harsh environments.

Inferior Olive HCN1 Channels Coordinate Synaptic Integration and Complex Spike Timing

Directory of Open Access Journals (Sweden)

Derek L.F. Garden

2018-02-01

Full Text Available Cerebellar climbing-fiber-mediated complex spikes originate from neurons in the inferior olive (IO, are critical for motor coordination, and are central to theories of cerebellar learning. Hyperpolarization-activated cyclic-nucleotide-gated (HCN channels expressed by IO neurons have been considered as pacemaker currents important for oscillatory and resonant dynamics. Here, we demonstrate that in vitro, network actions of HCN1 channels enable bidirectional glutamatergic synaptic responses, while local actions of HCN1 channels determine the timing and waveform of synaptically driven action potentials. These roles are distinct from, and may complement, proposed pacemaker functions of HCN channels. We find that in behaving animals HCN1 channels reduce variability in the timing of cerebellar complex spikes, which serve as a readout of IO spiking. Our results suggest that spatially distributed actions of HCN1 channels enable the IO to implement network-wide rules for synaptic integration that modulate the timing of cerebellar climbing fiber signals.

Role of route previewing strategies on climbing fluency and exploratory movements

NARCIS (Netherlands)

Seifert, Ludovic; Cordier, Romain; Orth, Dominic; Courtine, Yoan; Croft, James L.

2017-01-01

This study examined the role of route previewing strategies on climbing fluency and on exploratory movements of the limbs, in order to understand whether previewing helps people to perceive and to realize affordances. Eight inexperienced and ten experienced climbers previewed a 10 m high route of 5b

Fused-fiber-based 3-dB mode insensitive power splitters for few-mode optical fiber networks

Science.gov (United States)

Ren, Fang; Huang, Xiaoshan; Wang, Jianping

2017-11-01

We propose a 3-dB mode insensitive power splitter (MIPS) capable of broadcasting and combining optical signals. It is fabricated with two identical few-mode fibers (FMFs) by a heating and pulling technique. The mode-dependent power transfer characteristic as a function of pulling length is investigated. For exploiting its application, we experimentally demonstrate both FMF-based transmissive and reflective star couplers consisting of multiple 3-dB mode insensitive power splitters, which perform broadcasting and routing signals in few-mode optical fiber networks such as mode-division multiplexing (MDM) local area networks using star topology. For experimental demonstration, optical on-off keying signals at 10 Gb/s carried on three spatial modes are successfully processed with open and clear eye diagrams. Measured bit error ratio results show reasonable power penalties. It is found that a reflective star coupler in MDM networks can reduce half of the total amount of required fibers comparing to that of a transmissive star coupler. This MIPS is more efficient, more reliable, more flexible, and more cost-effective for future expansion and application in few-mode optical fiber networks.

Focusing over Optical Fiber Using Time Reversal

DEFF Research Database (Denmark)

Piels, Molly; Porto da Silva, Edson; Estaran Tolosa, Jose Manuel

2015-01-01

A time-reversal array in multimode fiber is proposed for lossless remotely controlled switching using passive optical splitters. The signal to be transmitted is digitally pre-distorted so that it is routed through the physical layer in order to arrive at only one receiver in an array. System...... performance in the presence of additive white gaussian noise, modal group delay, and timing error is investigated numerically for single-mode and 10-mode fiber. Focusing using a two-transmitter array and 44 km of single- mode fiber is demonstrated experimentally for 3 GBd QPSK signals with a bit error rate...

Cerebellar motor learning versus cerebellar motor timing: the climbing fibre story

Science.gov (United States)

Llinás, Rodolfo R

2011-01-01

Abstract Theories concerning the role of the climbing fibre system in motor learning, as opposed to those addressing the olivocerebellar system in the organization of motor timing, are briefly contrasted. The electrophysiological basis for the motor timing hypothesis in relation to the olivocerebellar system is treated in detail. PMID:21486816

Dislocation climb models from atomistic scheme to dislocation dynamics

OpenAIRE

Niu, Xiaohua; Luo, Tao; Lu, Jianfeng; Xiang, Yang

2016-01-01

We develop a mesoscopic dislocation dynamics model for vacancy-assisted dislocation climb by upscalings from a stochastic model on the atomistic scale. Our models incorporate microscopic mechanisms of (i) bulk diffusion of vacancies, (ii) vacancy exchange dynamics between bulk and dislocation core, (iii) vacancy pipe diffusion along the dislocation core, and (iv) vacancy attachment-detachment kinetics at jogs leading to the motion of jogs. Our mesoscopic model consists of the vacancy bulk dif...

On Climbing Scalars in String Theory

CERN Document Server

Dudas, E; Sagnotti, A

2010-01-01

In string models with "brane supersymmetry breaking" exponential potentials emerge at (closed-string) tree level but are not accompanied by tachyons. Potentials of this type have long been a source of embarrassment in flat space, but can have interesting implications for Cosmology. For instance, in ten dimensions the logarithmic slope |V'/V| lies precisely at a "critical" value where the Lucchin--Matarrese attractor disappears while the scalar field is \\emph{forced} to climb up the potential when it emerges from the Big Bang. This type of behavior is in principle perturbative in the string coupling, persists after compactification, could have trapped scalar fields inside potential wells as a result of the cosmological evolution and could have also injected the inflationary phase of our Universe.

Fiber optic hydrophone

Science.gov (United States)

Kuzmenko, Paul J.; Davis, Donald T.

1994-01-01

A miniature fiber optic hydrophone based on the principles of a Fabry-Perot interferometer. The hydrophone, in one embodiment, includes a body having a shaped flexible bladder at one end which defines a volume containing air or suitable gas, and including a membrane disposed adjacent a vent. An optic fiber extends into the body with one end terminating in spaced relation to the membrane. Acoustic waves in the water that impinge on the bladder cause the pressure of the volume therein to vary causing the membrane to deflect and modulate the reflectivity of the Fabry-Perot cavity formed by the membrane surface and the cleaved end of the optical fiber disposed adjacent to the membrane. When the light is transmitted down the optical fiber, the reflected signal is amplitude modulated by the incident acoustic wave. Another embodiment utilizes a fluid filled volume within which the fiber optic extends.

Novel Fiber-Optic Ring Acoustic Emission Sensor

Directory of Open Access Journals (Sweden)

Peng Wei

2018-01-01

Full Text Available Acoustic emission technology has been applied to many fields for many years. However, the conventional piezoelectric acoustic emission sensors cannot be used in extreme environments, such as those with heavy electromagnetic interference, high pressure, or strong corrosion. In this paper, a novel fiber-optic ring acoustic emission sensor is proposed. The sensor exhibits high sensitivity, anti-electromagnetic interference, and corrosion resistance. First, the principle of a novel fiber-optic ring sensor is introduced. Different from piezoelectric and other fiber acoustic emission sensors, this novel sensor includes both a sensing skeleton and a sensing fiber. Second, a heterodyne interferometric demodulating method is presented. In addition, a fiber-optic ring sensor acoustic emission system is built based on this method. Finally, fiber-optic ring acoustic emission experiments are performed. The novel fiber-optic ring sensor is glued onto the surface of an aluminum plate. The 150 kHz standard continuous sinusoidal signals and broken lead signals are successfully detected by the novel fiber-optic ring acoustic emission sensor. In addition, comparison to the piezoelectric acoustic emission sensor is performed, which shows the availability and reliability of the novel fiber-optic ring acoustic emission sensor. In the future, this novel fiber-optic ring acoustic emission sensor will provide a new route to acoustic emission detection in harsh environments.

A multi-component stair climbing promotional campaign targeting calorific expenditure for worksites; a quasi-experimental study testing effects on behaviour, attitude and intention

Directory of Open Access Journals (Sweden)

Eves Frank F

2012-06-01

Full Text Available Abstract Background Accumulation of lifestyle physical activity is a current aim of health promotion, with increased stair climbing one public health target. While the workplace provides an opportunity for regular stair climbing, evidence for effectiveness of point-of-choice interventions is equivocal. This paper reports a new approach to worksite interventions, aimed at changing attitudes and, hence, behaviour. Methods Pre-testing of calorific expenditure messages used structured interviews with members of the public (n = 300. Effects of multi-component campaigns on stair climbing were tested with quasi-experimental, interrupted time-series designs. In one worksite, a main campaign poster outlining the amount of calorific expenditure obtainable from stair climbing and a conventional point-of-choice prompt were used (Poster alone site. In a second worksite, additional messages in the stairwell about calorific expenditure reinforced the main campaign (Poster + Stairwell messages site. The outcome variables were automated observations of stair and lift ascent (28,854 and descent (29,352 at baseline and for three weeks after the intervention was installed. Post-intervention questionnaires for employees at the worksites assessed responses to the campaign (n = 253. Analyses employed Analysis of Variance with follow-up Bonferroni t-tests (message pre-testing, logistic regression of stair ascent and descent (campaign testing, and Bonferroni t-tests and multiple regression (follow-up questionnaire. Results Pre-testing of messages based on calorific expenditure suggested they could motivate stair climbing if believed. The new campaign increased stair climbing, with greater effects at the Poster + Stairwell messages site (OR = 1.52, 95% CI = 1.40-1.66 than Posters alone (OR = 1.24, 95% CI = 1.15-1.34. Follow-up revealed higher agreement with two statements about calorific outcomes of stair climbing in the site where they

On Heels and Toes: How Ants Climb with Adhesive Pads and Tarsal Friction Hair Arrays.

Directory of Open Access Journals (Sweden)

Thomas Endlein

Full Text Available Ants are able to climb effortlessly on vertical and inverted smooth surfaces. When climbing, their feet touch the substrate not only with their pretarsal adhesive pads but also with dense arrays of fine hairs on the ventral side of the 3rd and 4th tarsal segments. To understand what role these different attachment structures play during locomotion, we analysed leg kinematics and recorded single-leg ground reaction forces in Weaver ants (Oecophylla smaragdina climbing vertically on a smooth glass substrate. We found that the ants engaged different attachment structures depending on whether their feet were above or below their Centre of Mass (CoM. Legs above the CoM pulled and engaged the arolia ('toes', whereas legs below the CoM pushed with the 3rd and 4th tarsomeres ('heels' in surface contact. Legs above the CoM carried a significantly larger proportion of the body weight than legs below the CoM. Force measurements on individual ant tarsi showed that friction increased with normal load as a result of the bending and increasing side contact of the tarsal hairs. On a rough sandpaper substrate, the tarsal hairs generated higher friction forces in the pushing than in the pulling direction, whereas the reverse effect was found on the smooth substrate. When the tarsal hairs were pushed, buckling was observed for forces exceeding the shear forces found in climbing ants. Adhesion forces were small but not negligible, and higher on the smooth substrate. Our results indicate that the dense tarsal hair arrays produce friction forces when pressed against the substrate, and help the ants to push outwards during horizontal and vertical walking.

On Heels and Toes: How Ants Climb with Adhesive Pads and Tarsal Friction Hair Arrays.

Science.gov (United States)

Endlein, Thomas; Federle, Walter

2015-01-01

Ants are able to climb effortlessly on vertical and inverted smooth surfaces. When climbing, their feet touch the substrate not only with their pretarsal adhesive pads but also with dense arrays of fine hairs on the ventral side of the 3rd and 4th tarsal segments. To understand what role these different attachment structures play during locomotion, we analysed leg kinematics and recorded single-leg ground reaction forces in Weaver ants (Oecophylla smaragdina) climbing vertically on a smooth glass substrate. We found that the ants engaged different attachment structures depending on whether their feet were above or below their Centre of Mass (CoM). Legs above the CoM pulled and engaged the arolia ('toes'), whereas legs below the CoM pushed with the 3rd and 4th tarsomeres ('heels') in surface contact. Legs above the CoM carried a significantly larger proportion of the body weight than legs below the CoM. Force measurements on individual ant tarsi showed that friction increased with normal load as a result of the bending and increasing side contact of the tarsal hairs. On a rough sandpaper substrate, the tarsal hairs generated higher friction forces in the pushing than in the pulling direction, whereas the reverse effect was found on the smooth substrate. When the tarsal hairs were pushed, buckling was observed for forces exceeding the shear forces found in climbing ants. Adhesion forces were small but not negligible, and higher on the smooth substrate. Our results indicate that the dense tarsal hair arrays produce friction forces when pressed against the substrate, and help the ants to push outwards during horizontal and vertical walking.

To be active through indoor-climbing: an exploratory feasibility study in a group of children with cerebral palsy and typically developing children

DEFF Research Database (Denmark)

Christensen, Mark Schram; Jensen, Thor; Voigt, Camilla B.

2017-01-01

functional and cognitive benefits of 3 weeks of intensive climbing training in 11 children with cerebral palsy (CP) aged 11-13 years and six of their TD peers.Method: The study was designed as a feasibility and interventional study. We evaluated the amount of time spent being physically active during the 9...... in cognitive abilities or psychological well-being in any of the groups.Conclusions: These findings show that it is possible to use climbing as means to make children with CP physically active. The improved motor abilities obtained through the training is likely reflected by increased synchronization between...... be challenged functionally and cognitively, making climbing of great potential interest in (re) habilitation settings. However, until now only few research projects have investigated the feasibility of climbing as a potential activity for heightening physical activity in children with CP and the possible...

IMPLEMENTASI ALGORITMA HILL CLIMBING DAN ALGORITMA A* DALAM PENYELESAIAN PENYUSUNAN SUKU KATA DASAR DENGAN POLA PERMAINAN BINTANG KEJORA

Directory of Open Access Journals (Sweden)

Nurdin Nurdin

2016-07-01

Full Text Available Permainan Bintang Kejora merupakan permainan yang sama seperti permainan pergeseran angka dalam kotak berbentuk persegi (Puzzle. Jenis permainan seperti ini cenderung mudah untuk diselesaikan. Bentuk wadah bintang menyebabkan arah pergeseran akan menjadi terbatas. Permainan bintang kejora ini cukup rumit dan sukar untuk diselesaikan secara manual. Permainan ini dapat diselesaikan dengan metode heuristik, yaitu dengan menggunakan algoritma hill climbing dan algoritma A*. Sifat algoritma hill climbing adalah mencari kemungkinan-kemungkinan dari calon solusi untuk mendapatkan yang optimal bagi penyelesaian masalah dengan mencari nilai heuristik yang terkecil. Sedangkan algoritma A* membantu menemukan solusi pencarian dalam ruang keadaan dengan mempertimbangkan nilai heuristik terbesar yang dilacak sesuai node yang akan dilewati. Pembuatan perangkat lunak ini dirancang terlebih dahulu dengan menggunakan diagram State Transition Diagram, Use Case Diagram, Activity Diagram, dan Class Diagram. Perangkat lunak ini dapat memberikan penyelesaian yang optimum atas permainan bintang kejora yang nantinya menghasilkan huruf yang sebelumnya diacak menjadi tersusun membentuk sebuah kata dasar. Hasil yang didapatkan berupa langkah-langkah ditemukan solusi serta ditampilkan waktu pencarian yang dibutuhkan dalam menemukan solusi. Pencarian A* lebih cepat menemukan solusi dibandingkan Hill Climbing, karena A* mencari nilai heuristik pada jarak yang terjauh sehingga langsung tepat menuju sasaran. Kata kunci: Hill Climbing, Algoritma A*, Bintang Kejora

A Demonstration of Helping Adolescents with Mild Intellectual Disability Climb Ladders

Science.gov (United States)

Chan, Kok Hoe Anthony; Varahan, Jayashree Lakshmi; Loh, Peng Loong Daniel; Tan, Sey Ing

2011-01-01

A research team at a vocational school in Singapore, catering mainly to students between the ages of 17-21 with mild intellectual disability, studied how to best address the challenge of enabling students to learn how to climb ladders (a skill necessary at many job placements). They documented the approach used and suggested extrapolations and…

Static third-harmonic lines in widely variable fiber continuum generation

Science.gov (United States)

Tu, Haohua; Zhao, Youbo; Liu, Yuan; Boppart, Stephen A.

2014-01-01

An intriguing phenomenon of third-harmonic generation under fiber continuum generation is the emission of an anharmonic signal. One popular interpretation of this effect has developed into a general theory of fiber third-harmonic generation. Here we produce "static" third-harmonic lines dictated fully by fiber properties independent of pump parameters, in contrast to the signals of all known phase-matched nonlinear optical processes that vary dynamically with these parameters. We argue that the anharmonic signal is an illusion of the continuum generation, that it is in fact harmonic, and that this theory should be reevaluated.

A full-duplex CATV/wireless-over-fiber lightwave transmission system.

Science.gov (United States)

Li, Chung-Yi; Lu, Hai-Han; Ying, Cheng-Ling; Cheng, Chun-Jen; Lin, Che-Yu; Wan, Zhi-Wei; Chen, Jian-Hua

2015-04-06

A full-duplex CATV/wireless-over-fiber lightwave transmission system consisting of one broadband light source (BLS), two optical interleavers (ILs), one intensity modulator, and one phase modulator is proposed and experimentally demonstrated. The downstream light is optically promoted from 10Gbps/25GHz microwave (MW) data signal to 10Gbps/100GHz and 10Gbps/50GHz millimeter-wave (MMW) data signals in fiber-wireless convergence, and intensity-modulated with 50-550 MHz CATV signal. For up-link transmission, the downstream light is phase-remodulated with 10Gbps/25GHz MW data signal in fiber-wireless convergence. Over a 40-km single-mode fiber (SMF) and a 10-m radio frequency (RF) wireless transport, bit error rate (BER), carrier-to-noise ratio (CNR), composite second-order (CSO), and composite triple-beat (CTB) are observed to perform well in such full-duplex CATV/wireless-over-fiber lightwave transmission systems. This full-duplex 100-GHz/50-GHz/25-GHz/550-MHz lightwave transmission system is an attractive alternative. This transmission system not only presents its advancement in the integration of fiber backbone and CATV/wireless feeder networks, but also it provides the advantages of a communication channel for higher data rates and bandwidth.

Relationship between the climbing up and climbing down stairs domain scores on the FES-DMD, the score on the Vignos Scale, age and timed performance of functional activities in boys with Duchenne muscular dystrophy

Directory of Open Access Journals (Sweden)

Lilian A. Y. Fernandes

2014-12-01

Full Text Available BACKGROUND: Knowing the potential for and limitations of information generated using different evaluation instruments favors the development of more accurate functional diagnoses and therapeutic decision-making. OBJECTIVE: To investigate the relationship between the number of compensatory movements when climbing up and going down stairs, age, functional classification and time taken to perform a tested activity (TA of going up and down stairs in boys with Duchenne muscular dystrophy (DMD. METHOD: A bank of movies featuring 30 boys with DMD performing functional activities was evaluated. Compensatory movements were assessed using the climbing up and going down stairs domain of the Functional Evaluation Scale for Duchenne Muscular Dystrophy (FES-DMD; age in years; functional classification using the Vignos Scale (VS, and TA using a timer. Statistical analyses were performed using the Spearman correlation test. RESULTS: There is a moderate relationship between the climbing up stairs domain of the FES-DMD and age (r=0.53, p=0.004 and strong relationships with VS (r=0.72, p=0.001 and TA for this task (r=0.83, p<0.001. There were weak relationships between the going down stairs domain of the FES-DMD-going down stairs with age (r=0.40, p=0.032, VS (r=0.65, p=0.002 and TA for this task (r=0.40, p=0.034. CONCLUSION: These findings indicate that the evaluation of compensatory movements used when climbing up stairs can provide more relevant information about the evolution of the disease, although the activity of going down stairs should be investigated, with the aim of enriching guidance and strengthening accident prevention. Data from the FES-DMD, age, VS and TA can be used in a complementary way to formulate functional diagnoses. Longitudinal studies and with broader age groups may supplement this information.

Compact 84 GHz passive mode-locked fiber laser using dual-fiber coupled fused-quartz microresonator

Science.gov (United States)

Liu, Tze-An; Hsu, Yung; Chow, Chi-Wai; Chuang, Yi-Chen; Ting, Wei-Jo; Wang, Bo-Chun; Peng, Jin-Long; Chen, Guan-Hong; Chang, Yuan-Chia

2017-10-01

We propose and demonstrate a compact and portable-size 84-GHz passive mode-locked fiber laser, in which a dual-fiber coupled fused-quartz microresonator is employed as the intracavity optical comb filter as well as the optical nonlinear material for optical frequency comb generation. About eight coherent optical tones can be generated in the proposed fiber laser. The 20-dB bandwidth is larger than 588 GHz. The full-width half-maximum pulse-width of the proposed laser is 2.5 ps. We also demonstrate the feasibility of using the proposed passive mode-locked fiber laser to carry a 5-Gbit/s on-off-keying signal and transmit over 20-km standard single mode fiber. A 7% forward error correction requirement can be achieved, showing the proposed fiber laser can be a potential candidate for fiber-wireless applications.

Trunk and lower limb biomechanics during stair climbing in people with and without symptomatic femoroacetabular impingement.

Science.gov (United States)

Hammond, Connor A; Hatfield, Gillian L; Gilbart, Michael K; Garland, S Jayne; Hunt, Michael A

2017-02-01

Femoroacetabular impingement is a pathomechanical hip condition leading to pain and impaired physical function. It has been shown that those with femoroacetabular impingement exhibit altered gait characteristics during level walking and stair climbing, and decreased muscle force production during isometric muscle contractions. However, no studies to-date have looked at trunk kinematics or muscle activation during dynamic movements such as stair climbing in this patient population. The purpose of this study was to compare biomechanical outcomes (trunk and lower limb kinematics as well as lower limb kinetics and muscle activation) during stair climbing in those with and without symptomatic femoroacetabular impingement. Trunk, hip, knee and ankle kinematics, as well as hip, knee and ankle kinetics and muscle activity of nine lower limb muscles were collected during stair climbing for 20 people with clinical and radiographic femoroacetabular impingement and compared to 20 age- and sex-matched pain-free individuals. Those with femoroacetabular impingement ascended the stairs slower (effect size=0.82), had significantly increased peak trunk forward flexion angles (effect size=0.99) and external hip flexion moments (effect size=0.94) and had decreased peak external knee flexion moments (effect size=0.90) compared to the control group. Findings from this study indicate that while those with and without femoroacetabular impingement exhibit many biomechanical similarities when ascending stairs, differences in trunk forward flexion and joint kinetics indicate some important differences. Further longitudinal research is required to elucidate the cause of these differences as well as the clinical relevance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hill-Climbing search and diversification within an evolutionary approach to protein structure prediction.

Science.gov (United States)

Chira, Camelia; Horvath, Dragos; Dumitrescu, D

2011-07-30

Proteins are complex structures made of amino acids having a fundamental role in the correct functioning of living cells. The structure of a protein is the result of the protein folding process. However, the general principles that govern the folding of natural proteins into a native structure are unknown. The problem of predicting a protein structure with minimum-energy starting from the unfolded amino acid sequence is a highly complex and important task in molecular and computational biology. Protein structure prediction has important applications in fields such as drug design and disease prediction. The protein structure prediction problem is NP-hard even in simplified lattice protein models. An evolutionary model based on hill-climbing genetic operators is proposed for protein structure prediction in the hydrophobic - polar (HP) model. Problem-specific search operators are implemented and applied using a steepest-ascent hill-climbing approach. Furthermore, the proposed model enforces an explicit diversification stage during the evolution in order to avoid local optimum. The main features of the resulting evolutionary algorithm - hill-climbing mechanism and diversification strategy - are evaluated in a set of numerical experiments for the protein structure prediction problem to assess their impact to the efficiency of the search process. Furthermore, the emerging consolidated model is compared to relevant algorithms from the literature for a set of difficult bidimensional instances from lattice protein models. The results obtained by the proposed algorithm are promising and competitive with those of related methods.

Hill-Climbing search and diversification within an evolutionary approach to protein structure prediction

Directory of Open Access Journals (Sweden)

Chira Camelia

2011-07-01

Full Text Available Abstract Proteins are complex structures made of amino acids having a fundamental role in the correct functioning of living cells. The structure of a protein is the result of the protein folding process. However, the general principles that govern the folding of natural proteins into a native structure are unknown. The problem of predicting a protein structure with minimum-energy starting from the unfolded amino acid sequence is a highly complex and important task in molecular and computational biology. Protein structure prediction has important applications in fields such as drug design and disease prediction. The protein structure prediction problem is NP-hard even in simplified lattice protein models. An evolutionary model based on hill-climbing genetic operators is proposed for protein structure prediction in the hydrophobic - polar (HP model. Problem-specific search operators are implemented and applied using a steepest-ascent hill-climbing approach. Furthermore, the proposed model enforces an explicit diversification stage during the evolution in order to avoid local optimum. The main features of the resulting evolutionary algorithm - hill-climbing mechanism and diversification strategy - are evaluated in a set of numerical experiments for the protein structure prediction problem to assess their impact to the efficiency of the search process. Furthermore, the emerging consolidated model is compared to relevant algorithms from the literature for a set of difficult bidimensional instances from lattice protein models. The results obtained by the proposed algorithm are promising and competitive with those of related methods.

Bandwidths of micro-twisted-pair cables and fusion-spliced SIMM-GRIN fiber

International Nuclear Information System (INIS)

Gan, K.K.; Kagan, H.P.; Kass, R.D.; Smith, D.S.

2007-01-01

The SLHC is designed to increase the luminosity of the LHC by a factor of 10. In the present ATLAS pixel detector, electrical signals between the pixel modules and the optical modules (opto-boards) are transmitted in ∼1 m of micro-twisted-pair cables. The optical signals between the opto-boards and the off-detector optical modules are transmitted in fiber ribbons. Each fiber link consists of 8 m of rad-hard/low bandwidth SIMM fiber fusion spliced to 70 m of rad-tolerant/medium bandwidth GRIN fiber. We currently transmit optical signals at 80 Mb/s and expect to transmit signals at 1 Gb/s in the SLHC. For the SLHC optical link, we would like to take advantage of some of the design features of the present pixel optical links and the many years of R and D effort and production experience. If the present architecture can transmit signals at the higher speed required by the SLHC, the constraint of requiring no extra service space is automatically satisfied. We have measured the bandwidths of the transmission lines and our preliminary results indicate that the micro-twisted-pair cables can transmit signals up to ∼1 Gb/s and the fusion-spliced fiber ribbon can transmit signals up to ∼2 Gb/s

Fiber-Optic Vibration Sensor Based on Multimode Fiber

Directory of Open Access Journals (Sweden)

I. Lujo

2008-06-01

Full Text Available The purpose of this paper is to present a fiberoptic vibration sensor based on the monitoring of the mode distribution in a multimode optical fiber. Detection of vibrations and their parameters is possible through observation of the output speckle pattern from the multimode optical fiber. A working experimental model has been built in which all used components are widely available and cheap: a CCD camera (a simple web-cam, a multimode laser in visible range as a light source, a length of multimode optical fiber, and a computer for signal processing. Measurements have shown good agreement with the actual frequency of vibrations, and promising results were achieved with the amplitude measurements although they require some adaptation of the experimental model. Proposed sensor is cheap and lightweight and therefore presents an interesting alternative for monitoring large smart structures.

Development and optimization of a miniaturized fiber-optic photoplethysmographic sensor

Science.gov (United States)

Morley, Aisha; Davenport, John J.; Hickey, Michelle; Phillips, Justin P.

2017-11-01

Photoplethysmography (PPG) is a widely used technique for measuring blood oxygen saturation, commonly using an external pulse oximeter applied to a finger, toe, or earlobe. Previous research has demonstrated the utility of direct monitoring of the oxygen saturation of internal organs, using optical fibers to transmit light between the photodiode/light emitting diode and internal site. However, little research into the optimization and standardization of such a probe has yet been carried out. This research establishes the relationship between fiber separation distance and PPG signal, and between fiber core width and PPG signal. An ideal setup is suggested: 1000-μm fibers at a separation distance of 3 to 3.5 mm, which was found to produce signals around 0.35 V in amplitude with a low variation coefficient.

Sapphire-fiber-based distributed high-temperature sensing system.

Science.gov (United States)

Liu, Bo; Yu, Zhihao; Hill, Cary; Cheng, Yujie; Homa, Daniel; Pickrell, Gary; Wang, Anbo

2016-09-15

We present, for the first time to our knowledge, a sapphire-fiber-based distributed high-temperature sensing system based on a Raman distributed sensing technique. High peak power laser pulses at 532 nm were coupled into the sapphire fiber to generate the Raman signal. The returned Raman Stokes and anti-Stokes signals were measured in the time domain to determine the temperature distribution along the fiber. The sensor was demonstrated from room temperature up to 1200°C in which the average standard deviation is about 3.7°C and a spatial resolution of about 14 cm was achieved.

Suppression of dynamic laser speckle signals in multimode fibers of various lengths

NARCIS (Netherlands)

Petoukhova, Anna; Cleven, Ester; de Mul, F.F.M.; Steenbergen, Wiendelt

2004-01-01

The effects of fiber coupling and fiber length on photocurrent fluctuations are studied when the light of a laser diode transmitted to and from a dynamic turbid medium by a step-index multimode fiber is studied. When the laser light is coupled asymmetrically, filling only the higher-order modes, the

77 FR 33777 - General Aviation Safety Forum: Climbing to the Next Level

Science.gov (United States)

2012-06-07

... NATIONAL TRANSPORTATION SAFETY BOARD General Aviation Safety Forum: Climbing to the Next Level The National Transportation Safety Board (NTSB) will convene a 2- day forum focused on safety issues related to... the Next Level,'' will be chaired by NTSB Chairman Deborah A. P. Hersman and all five Board Members...

Detection and recognition of mechanical, digging and vehicle signals in the optical fiber pre-warning system

Science.gov (United States)

Tian, Qing; Yang, Dan; Zhang, Yuan; Qu, Hongquan

2018-04-01

This paper presents detection and recognition method to locate and identify harmful intrusions in the optical fiber pre-warning system (OFPS). Inspired by visual attention architecture (VAA), the process flow is divided into two parts, i.e., data-driven process and task-driven process. At first, data-driven process takes all the measurements collected by the system as input signals, which is handled by detection method to locate the harmful intrusion in both spatial domain and time domain. Then, these detected intrusion signals are taken over by task-driven process. Specifically, we get pitch period (PP) and duty cycle (DC) of the intrusion signals to identify the mechanical and manual digging (MD) intrusions respectively. For the passing vehicle (PV) intrusions, their strong low frequency component can be used as good feature. In generally, since the harmful intrusion signals only account for a small part of whole measurements, the data-driven process reduces the amount of input data for subsequent task-driven process considerably. Furthermore, the task-driven process determines the harmful intrusions orderly according to their severity, which makes a priority mechanism for the system as well as targeted processing for different harmful intrusion. At last, real experiments are performed to validate the effectiveness of this method.

Plastic scintillation dosimetry: Optimal selection of scintillating fibers and scintillators

International Nuclear Information System (INIS)

Archambault, Louis; Arsenault, Jean; Gingras, Luc; Sam Beddar, A.; Roy, Rene; Beaulieu, Luc

2005-01-01

Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for four commercial models of scintillating fibers (BCF-12, BCF-60, SCSF-78, SCSF-3HF) and two models of plastic scintillators (BC-400, BC-408). The emission spectra of all six scintillators were obtained by using an optical spectrum analyzer and they were compared with theoretical behavior. For scintillation in the blue region, the signal intensity of a singly clad scintillating fiber (BCF-12) was 120% of that of the plastic scintillator (BC-400). For the multiclad fiber (SCSF-78), the signal reached 144% of that of the plastic scintillator. The intensity of the green scintillating fibers was lower than that of the plastic scintillator: 47% for the singly clad fiber (BCF-60) and 77% for the multiclad fiber (SCSF-3HF). The collected light was studied as a function of the scintillator length and radius for a cylindrical probe. We found that symmetric detectors with nearly the same spatial resolution in each direction (2 mm in diameter by 3 mm in length) could be made with a signal equivalent to those of the more commonly used asymmetric scintillators. With augmentation of the signal-to-noise ratio in consideration, this paper presents a series of comparisons that should provide insight into selection of a scintillator type and volume for development of a medical dosimeter

Time-of-flight positron emission tomography using optical fiber circuit

International Nuclear Information System (INIS)

Yamawaki, Masato; Katsumura, Yousuke; Suzuki, Takenori

2008-01-01

The measurement method and system architecture of a new time-of-flight positron emission tomography (TOF-PET) system are proposed. This system collects scintillation light using optical fibers connected directly to scintillators and measures the position of positron annihilation. Many scintillators are placed cylindrically whereby a pair of scintillators detects a pair of γ-rays generated at the positron annihilation point. Optical fiber circuits, most of which are bundles of optical fibers bound clockwise or counterclockwise around the cylinder of scintillators, collect light signals generated by γ-rays. These light signals are amplified by several photomultiplier tubes and processed using a single digital oscilloscope to determine the TOF of the positron annihilation γ-rays. One of the most important factors in the performance of the TOF-PET system is the TOF resolution. When fiber circuits are used for transmitting light signals, the dispersion of light signals and the decrease in light intensity are the major factors in the deterioration of the TOF resolution. The result of the preliminary experiment leads to the conclusion that the use of optical fibers degrades the intensity of light but does not severely degrade the TOF resolution. (author)

Optical fiber-applied radiation detection system

International Nuclear Information System (INIS)

Nishiura, Ryuichi; Uranaka, Yasuo; Izumi, Nobuyuki

2001-01-01

A technique to measure radiation by using plastic scintillation fibers doped radiation fluorescent (scintillator) to plastic optical fiber for a radiation sensor, was developed. The technique contains some superiority such as high flexibility due to using fibers, relatively easy large area due to detecting portion of whole of fibers, and no electromagnetic noise effect due to optical radiation detection and signal transmission. Measurable to wide range of and continuous radiation distribution along optical fiber cable at a testing portion using scintillation fiber and flight time method, the optical fiber-applied radiation sensing system can effectively monitor space radiation dose or apparatus operation condition monitoring. And, a portable type scintillation optical fiber body surface pollution monitor can measure pollution concentration of radioactive materials attached onto body surface by arranging scintillation fiber processed to a plate with small size and flexibility around a man to be tested. Here were described on outline and fundamental properties of various application products using these plastic scintillation fiber. (G.K.)

Cerenkov light spectrum in an optical fiber exposed to a photon or electron radiation therapy beam

International Nuclear Information System (INIS)

Lambert, Jamil; Yin Yongbai; McKenzie, David R.; Law, Sue; Suchowerska, Natalka

2009-01-01

A Cerenkov signal is generated when energetic charged particles enter the core of an optical fiber. The Cerenkov intensity can be large enough to interfere with signals transmitted through the fiber. We determine the spectrum of the Cerenkov background signal generated in a poly(methyl methacrylate) optical fiber exposed to photon and electron therapeutic beams from a linear accelerator. This spectral measurement is relevant to discrimination of the signal from the background, as in scintillation dosimetry using optical fiber readouts. We find that the spectrum is approximated by the theoretical curve after correction for the wavelength dependent attenuation of the fiber. The spectrum does not depend significantly on the angle between the radiation beam and the axis of the fiber optic but is dependent on the depth in water at which the fiber is exposed to the beam.

Miniature fiber-optic multiphoton microscopy system using frequency-doubled femtosecond Er-doped fiber laser.

Science.gov (United States)

Huang, Lin; Mills, Arthur K; Zhao, Yuan; Jones, David J; Tang, Shuo

2016-05-01

We report on a miniature fiber-optic multiphoton microscopy (MPM) system based on a frequency-doubled femtosecond Er-doped fiber laser. The femtosecond pulses from the laser source are delivered to the miniature fiber-optic probe at 1.58 µm wavelength, where a standard single mode fiber is used for delivery without the need of free-space dispersion compensation components. The beam is frequency-doubled inside the probe by a periodically poled MgO:LiNbO3 crystal. Frequency-doubled pulses at 786 nm with a maximum power of 80 mW and a pulsewidth of 150 fs are obtained and applied to excite intrinsic signals from tissues. A MEMS scanner, a miniature objective, and a multimode collection fiber are further used to make the probe compact. The miniature fiber-optic MPM system is highly portable and robust. Ex vivo multiphoton imaging of mammalian skins demonstrates the capability of the system in imaging biological tissues. The results show that the miniature fiber-optic MPM system using frequency-doubled femtosecond fiber laser can potentially bring the MPM imaging for clinical applications.

Objective-lens-free Fiber-based Position Detection with Nanometer Resolution in a Fiber Optical Trapping System.

Science.gov (United States)

Ti, Chaoyang; Ho-Thanh, Minh-Tri; Wen, Qi; Liu, Yuxiang

2017-10-13

Position detection with high accuracy is crucial for force calibration of optical trapping systems. Most existing position detection methods require high-numerical-aperture objective lenses, which are bulky, expensive, and difficult to miniaturize. Here, we report an affordable objective-lens-free, fiber-based position detection scheme with 2 nm spatial resolution and 150 MHz bandwidth. This fiber based detection mechanism enables simultaneous trapping and force measurements in a compact fiber optical tweezers system. In addition, we achieved more reliable signal acquisition with less distortion compared with objective based position detection methods, thanks to the light guiding in optical fibers and small distance between the fiber tips and trapped particle. As a demonstration of the fiber based detection, we used the fiber optical tweezers to apply a force on a cell membrane and simultaneously measure the cellular response.

Decorative values of selected cultivars of climbing roses (Rosa L. with regard to thermal conditions

Directory of Open Access Journals (Sweden)

Zofia Włodarczyk

2012-12-01

Full Text Available In the years 2004-2006 in Kraków, phenological observations of climbing roses were conducted in order to determine the length and dates of their flowering period. The diameters of their flowers were also compared. Eight flowering repeating cultivars were selected for the experiment: 'Climbing Souvenir de la Malmaison', 'Dortmund', 'Golden Showers', 'Goldstern', 'New Dawn', 'Parade', 'Sympathie' and 'White New Dawn'. During the studies, the shrub roses were not artificially watered in order to create conditions similar to those prevailing in public green areas. It was observed that irrespective of the air temperature pattern in a given year, the studied cultivars did not bloom before 15 June. In 2006 high temperatures (above 20oC, which continued throughout the whole flowering period, caused its shortening, and the interval between the first and the next flowering in the season lasted longer than in the previous years. In the years 2004-2006, the cultivar 'New Dawn' bloomed the longest. In 2005 the studied cultivars produced larger flowers than the next year. The cultivars 'Dortmund' and 'White New Dawn' were characterised by the smallest diameter of flowers, whereas 'Climbing Souvenir de la Malmaison', 'Golden Showers' and 'Parade' were marked by the largest diameter.

When Affordances Climb into Your Mind: Advantages of Motor Simulation in a Memory Task Performed by Novice and Expert Rock Climbers

Science.gov (United States)

Pezzulo, Giovanni; Barca, Laura; Bocconi, Alessandro Lamberti; Borghi, Anna M.

2010-01-01

Does the sight of multiple climbing holds laid along a path activate a motor simulation of climbing that path? One way of testing whether multiple affordances and their displacement influence the formation of a motor simulation is to study acquired motor skills. We used a behavioral task in which expert and novice rock climbers were shown three…

Noninvasive blood pressure measurement scheme based on optical fiber sensor

Science.gov (United States)

Liu, Xianxuan; Yuan, Xueguang; Zhang, Yangan

2016-10-01

Optical fiber sensing has many advantages, such as volume small, light quality, low loss, strong in anti-jamming. Since the invention of the optical fiber sensing technology in 1977, optical fiber sensing technology has been applied in the military, national defense, aerospace, industrial, medical and other fields in recent years, and made a great contribution to parameter measurement in the environment under the limited condition .With the rapid development of computer, network system, the intelligent optical fiber sensing technology, the sensor technology, the combination of computer and communication technology , the detection, diagnosis and analysis can be automatically and efficiently completed. In this work, we proposed a noninvasive blood pressure detection and analysis scheme which uses optical fiber sensor. Optical fiber sensing system mainly includes the light source, optical fiber, optical detector, optical modulator, the signal processing module and so on. wavelength optical signals were led into the optical fiber sensor and the signals reflected by the human body surface were detected. By comparing actual testing data with the data got by traditional way to measure the blood pressure we can establish models for predicting the blood pressure and achieve noninvasive blood pressure measurement by using spectrum analysis technology. Blood pressure measurement method based on optical fiber sensing system is faster and more convenient than traditional way, and it can get accurate analysis results in a shorter period of time than before, so it can efficiently reduce the time cost and manpower cost.

Application of Negative Curvature Hollow-Core Fiber in an Optical Fiber Sensor Setup for Multiphoton Spectroscopy.

Science.gov (United States)

Popenda, Maciej Andrzej; Stawska, Hanna Izabela; Mazur, Leszek Mateusz; Jakubowski, Konrad; Kosolapov, Alexey; Kolyadin, Anton; Bereś-Pawlik, Elżbieta

2017-10-06

In this paper, an application of negative curvature hollow core fiber (NCHCF) in an all-fiber, multiphoton fluorescence sensor setup is presented. The dispersion parameter (D) of this fiber does not exceed the value of 5 ps/nm × km across the optical spectrum of (680-750) nm, making it well suited for the purpose of multiphoton excitation of biological fluorophores. Employing 1.5 m of this fiber in a simple, all-fiber sensor setup allows us to perform multiphoton experiments without any dispersion compensation methods. Multiphoton excitation of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) with this fiber shows a 6- and 9-fold increase, respectively, in the total fluorescence signal collected when compared with the commercial solution in the form of a hollow-core photonic band gap fiber (HCPBF). To the author's best knowledge, this is the first time an NCHCF was used in an optical-fiber sensor setup for multiphoton fluorescence experiments.

Single mode optical fiber vibration sensor: design and development

Science.gov (United States)

Alanis-Carranza, L. E.; Alvarez-Chavez, J. A.; Perez-Sanchez, G. G.; Sierra-Calderon, A.; Rodriguez-Novelo, J. C.

2016-09-01

This work deals with the design and development of an SMF28-based vibration detector including the fiber segment, the data acquisition via an NI-USB-6212 card, the data processing code in Visual Basic and the signal spectrum obtained via Fourier analysis. The set-up consists of a regulated voltage source at 2.6V, 300mA, which serves as the power source for a 980nm semiconductor laser operating at 150mW which is fiber coupled into a 20m-piece of SMF-28 fiber. Perpendicular to such fiber the perturbations ranged from 1 to 100 kHz, coming from a DC motor at 12 Volts. At the detection stage, a simple analog filter and a commercial photo diode were employed for data acquisition, before a transimpedance amplification stage reconstructed the signal into the National Instruments data acquisition card. At the output, the signals Fourier transformation allows the signal to be displayed in a personal computer. The presentation will include a full electrical and optical characterization of the device and preliminary sensing results, which could be suitable for structural health monitoring applications.

A method to control the fabrication of etched optical fiber probes with nanometric tips

International Nuclear Information System (INIS)

Tao, Miaomiao; Gu, Ning; Huang, Lan; Jin, Yonglong

2010-01-01

Optical fiber probes with small size tips have attracted much interest in the areas of biosensor and near-field scanning optical microscopy. Chemical etching is a common useful method to fabricate such probes. But it is difficult to study or determine the etching time and control the shape of the fiber during the etching. In this work, a new method combining a fiber optic spectrometer with static chemical etching has been developed to fabricate optical fiber probe nanotips, where the fiber optic spectrometer is used to measure the optical signal during the etching. By calculating and analyzing the testing data, the relationship between the apex angle and the optical signal can be obtained. Accordingly, the process of fabricating optical fibers based on the optical signal can be controlled

Conservation of a medieval climbing stem by freeze-drying and resin impregnation

International Nuclear Information System (INIS)

Schaudy, R.; Slais, E.; Eibner, C.

1985-12-01

The conservation of a climbing stem originating from a medieval mining adit is described. The fragile wet object was preserved by a combined process consisting of freeze-drying after a polyethylene glycol bath and consecutive resin impregnation with curing by gamma irradiation. The whole conservation process took 1 year. The result is discussed. (Author)

Engineers find climbing techniques work well for dam inspections

Energy Technology Data Exchange (ETDEWEB)

O`Shea, M.; Graves, A. [Bureau of Reclamation, Denver, CO (United States)

1996-10-01

Climbing techniques adopted by the Bureau of Reclamation to inspect previously inaccessible or difficult to reach features at dams are described. Following the failure of the steel radial-arm gate at Folsom Dam, engineers mounted an effort to reach and inspect the dam`s seven other spillway gates. This close-up examination was performed to: (1) determine the condition of these gates; and (2) gather clues about the failure of the one gate. The access techniques described involved mountaineering techniques, as opposed to high scaling techniques, performed with dynamic and static nylon kermantle ropes.

Information transmission via fiber optics in the shiva laser control system

International Nuclear Information System (INIS)

Parker, J.

1978-01-01

The Fiber Optic Serial Link package performs the functions of transmission and reception of signals over a pair of fiber optic cables and the I/O of serial data to a local device in EIA format. Present sysems requirements include fiber cable transmission length of up to 150 m and baud rates up to 9600, although the design criterium of transmission at 19.2 KB has been met. Fiber optic links are used between the central control area and each of the alignment control subsystems, in addition to sending timing signals over long distances between subsystems

Colocalization properties of elementary Ca(2+) release signals with structures specific to the contractile filaments and the tubular system of intact mouse skeletal muscle fibers.

Science.gov (United States)

Georgiev, Tihomir; Zapiec, Bolek; Förderer, Moritz; Fink, Rainer H A; Vogel, Martin

2015-12-01

Ca(2+) regulates several important intracellular processes. We combined second harmonic generation (SHG) and two photon excited fluorescence microscopy (2PFM) to simultaneously record the SHG signal of the myosin filaments and localized elementary Ca(2+) release signals (LCSs). We found LCSs associated with Y-shaped structures of the myosin filament pattern (YMs), so called verniers, in intact mouse skeletal muscle fibers under hypertonic treatment. Ion channels crucial for the Ca(2+) regulation are located in the tubular system, a system that is important for Ca(2+) regulation and excitation-contraction coupling. We investigated the tubular system of intact, living mouse skeletal muscle fibers using 2PFM and the fluorescent Ca(2+) indicator Fluo-4 dissolved in the external solution or the membrane dye di-8-ANEPPS. We simultaneously measured the SHG signal from the myosin filaments of the skeletal muscle fibers. We found that at least a subset of the YMs observed in SHG images are closely juxtaposed with Y-shaped structures of the transverse tubules (YTs). The distances of corresponding YMs and YTs yield values between 1.3 μm and 4.1 μm including pixel uncertainty with a mean distance of 2.52±0.10 μm (S.E.M., n=41). Additionally, we observed that some of the linear-shaped areas in the tubular system are colocalized with linear-shaped areas in the SHG images. Copyright © 2015 Elsevier Inc. All rights reserved.

Optical fiber applied to radiation detection

Energy Technology Data Exchange (ETDEWEB)

Junior, Francisco A.B.; Costa, Antonella L.; Oliveira, Arno H. de; Vasconcelos, Danilo C., E-mail: fanbra@yahoo.com.br, E-mail: antonella@nuclear.ufmg.br, E-mail: heeren@nuclear.ufmg.br, E-mail: danilochagas@yahoo.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Escola de Engenharia. Departamento de Engenharia Nuclear

2015-07-01

In the last years, the production of optical fibers cables has make possible the development of a range of spectroscopic probes for in situ analysis performing beyond nondestructive tests, environmental monitoring, security investigation, application in radiotherapy for dose monitoring, verification and validation. In this work, a system using an optical fiber cable to light signal transmission from a NaI(Tl) radiation detector is presented. The innovative device takes advantage mainly of the optical fibers small signal attenuation and immunity to electromagnetic interference to application for radiation detection systems. The main aim was to simplify the detection system making it to reach areas where the conventional device cannot access due to its lack of mobility and external dimensions. Some tests with this innovative system are presented and the results stimulate the continuity of the researches. (author)

Fiber-optic control of the ZT-P experiment

International Nuclear Information System (INIS)

Caudill, L.D.; Chandler, G.I.; Hall, C.R.; Trujillo, J.F.

1986-01-01

The computer control system for the ZT-P experiment has been implemented using a fiber-optic link in all 161 control signal paths. Four classes of control signals are used in this design. These are (a) digital-out, an on--off signal from computer to machine actuator, (b) digital-in, an on--off signal from machine sensor to computer, (c) analog-out, a 0--10-V analog signal from computer to machine actuator, (d) analog-in, a 0--1-mA analog signal from machine sensor to computer. The digital-in and the digital-out class of signals require no control power at the machine. The analog-out and the analog-in class of signals use available machine power for control. This unique power arrangement and the use of fiber-optic links totally isolate the electrically noisy machine areas from the sensitive electronics in the computer control. Advantages of this system including low cost, small size, personnel safety, and ease of maintenance and modification are discussed

Fiber-optic control of the ZT-P experiment

International Nuclear Information System (INIS)

Caudill, L.D.; Chandler, G.I.; Hall, C.R.; Trujillo, J.F.

1986-01-01

The computer control system for the ZT-P experiment has been implemented using a fiber-optic link in all 161 control signal paths. Four classes of control signals are used in this design. These are: (a) digital-out, an on-off signal from computer to machine actuator, (b) digital-in, an on-off signal from machine sensor to computer, (c) analog-out, a 0 to 10 volt analog signal from computer to machine actuator, (d) analog-in, a 0 to +1 milliampere analog signal from machine sensor to computer. The digital-in and the digital-out class of signals require no control power at the machine. The analog-out and the analog-in class of signals use available machine power for control. This unique power arrangement and the use of fiber-optic links totally isolate the electrically noisy machine areas from the sensitive electronics in the computer control. Advantages of this system including low cost, small size, personnel safety, and ease of maintenance and modification are discussed

Fiber-optic control of the ZT-P experiment

International Nuclear Information System (INIS)

Caudill, L.D.; Chandler, G.I.; Hall, C.R.; Trujillo, J.F.

1986-01-01

The computer control system for the ZT-P experiment has been implemented using a fiber-optic link in all 161 control signal paths. Four classes of control signals are used in this design. These are: digital-out; an on-off signal from computer to machine actuator, digital-in, and on-off signal from machine sensor to computer, analog-out, a 0 - 10 volt analog signal from computer to machine actuator, analog-in, 0 to +1 milliampere analog signal from machine sensor to computer. The digital-in and the digital-out class of signals require no control power at the machine end. The analog-out and the analog-in class of signals use available machine power for control. This unique power arrangement and the use of fiber-optic links serve to totally isolate electrically noisy machine areas from the sensitive electronics in the computer control. Advantages, including low cost, small size, personnel safety, and ease of maintenance and modification are discussed

Influence of Fiber Orientation on Single-Point Cutting Fracture Behavior of Carbon-Fiber/Epoxy Prepreg Sheets

Directory of Open Access Journals (Sweden)

Yingying Wei

2015-10-01

Full Text Available The purpose of this article is to investigate the influences of carbon fibers on the fracture mechanism of carbon fibers both in macroscopic view and microscopic view by using single-point flying cutting method. Cutting tools with three different materials were used in this research, namely, PCD (polycrystalline diamond tool, CVD (chemical vapor deposition diamond thin film coated carbide tool and uncoated carbide tool. The influence of fiber orientation on the cutting force and fracture topography were analyzed and conclusions were drawn that cutting forces are not affected by cutting speeds but significantly influenced by the fiber orientation. Cutting forces presented smaller values in the fiber orientation of 0/180° and 15/165° but the highest one in 30/150°. The fracture mechanism of carbon fibers was studied in different cutting conditions such as 0° orientation angle, 90° orientation angle, orientation angles along fiber direction, and orientation angles inverse to the fiber direction. In addition, a prediction model on the cutting defects of carbon fiber reinforced plastic was established based on acoustic emission (AE signals.

Influence of Fiber Orientation on Single-Point Cutting Fracture Behavior of Carbon-Fiber/Epoxy Prepreg Sheets.

Science.gov (United States)

Wei, Yingying; An, Qinglong; Cai, Xiaojiang; Chen, Ming; Ming, Weiwei

2015-10-02

The purpose of this article is to investigate the influences of carbon fibers on the fracture mechanism of carbon fibers both in macroscopic view and microscopic view by using single-point flying cutting method. Cutting tools with three different materials were used in this research, namely, PCD (polycrystalline diamond) tool, CVD (chemical vapor deposition) diamond thin film coated carbide tool and uncoated carbide tool. The influence of fiber orientation on the cutting force and fracture topography were analyzed and conclusions were drawn that cutting forces are not affected by cutting speeds but significantly influenced by the fiber orientation. Cutting forces presented smaller values in the fiber orientation of 0/180° and 15/165° but the highest one in 30/150°. The fracture mechanism of carbon fibers was studied in different cutting conditions such as 0° orientation angle, 90° orientation angle, orientation angles along fiber direction, and orientation angles inverse to the fiber direction. In addition, a prediction model on the cutting defects of carbon fiber reinforced plastic was established based on acoustic emission (AE) signals.

Multi-Objective Climb Path Optimization for Aircraft/Engine Integration Using Particle Swarm Optimization

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Aristeidis Antonakis

2017-04-01

Full Text Available In this article, a new multi-objective approach to the aircraft climb path optimization problem, based on the Particle Swarm Optimization algorithm, is introduced to be used for aircraft–engine integration studies. This considers a combination of a simulation with a traditional Energy approach, which incorporates, among others, the use of a proposed path-tracking scheme for guidance in the Altitude–Mach plane. The adoption of population-based solver serves to simplify case setup, allowing for direct interfaces between the optimizer and aircraft/engine performance codes. A two-level optimization scheme is employed and is shown to improve search performance compared to the basic PSO algorithm. The effectiveness of the proposed methodology is demonstrated in a hypothetic engine upgrade scenario for the F-4 aircraft considering the replacement of the aircraft’s J79 engine with the EJ200; a clear advantage of the EJ200-equipped configuration is unveiled, resulting, on average, in 15% faster climbs with 20% less fuel.

Flexible Structural Design for Side-Sliding Force Reduction for a Caterpillar Climbing Robot

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Weina Cui

2012-11-01

Full Text Available Due to sliding force arising from the closed chain mechanism among the adhering points of a climbing caterpillar robot (CCR, a sliding phenomenon will happen at the adhering points, e.g., the vacuum pads or claws holding the surface. This sliding force makes the attachment of the climbing robot unsteady and reducesthe motion efficiency. According to the new bionic research on the soft-body structure of caterpillars, some flexible structures made of natural rubber bars are applied in CCRs correspondingly as an improvement to the old rigid mechanical design of the robotic structure. This paper firstly establishes the static model of the sliding forces, the distortion of flexible bars and the driving torques of joints. Then, a method to reduce the sliding force by exerting a compensating angle to an active joint of the CCR is presented. The analyses and experimental results indicate that the flexible structure and the compensating angle method can reduce the sliding forces remarkably.

Determination of moisture in fiber reinforced composites using pulsed NMR

International Nuclear Information System (INIS)

Matzkanin, G.A.

1982-01-01

Nuclear magnetic resonance (NMR) signals from hydrogen atoms in two organic matrix composite systems subjected to environmental conditioning at 51.6 C (125 F) and 95% relative humidity were examined. The composites were 8 ply, + or - 45 deg laminates fabricated from SP 250 resin/S2 glass fiber and Reliabond 9350 resin/Kevlar 49 fiber. Free induction decay NMR signals from the composite specimens consisted of a large amplitude, fast decaying component associated with hydrogen in rigid polymer molecules and a lower amplitude, slower decaying component associated with hydrogen in the mobile absorbed moisture molecules. The absorbed moisture NMR signals consists of distinct multiple components which were attributed to moisture in various states of molecular binding. Particularly complex free induction decay signals were observed from Kevlar composite as well as from Kevlar fiber. Good correlation was obtained between the NMR signal amplitude and the dry weight moisture percentage for both composite systems. Results of destructive tensile tests were examined

The Effect of Climbing as a Recreational Event on Adoles ent ’ s Locus of Control

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Güçlü ÖZEN

2014-07-01

Full Text Available The aim of this study was to determine the effect of experience of the secondary education ( class 10th and 11th students‟ participation on artificial wall climbing refe r r ed to experiential learning education and defined as high activity on th eir locus of control . Artifical wall climbing is a learning point beyond the sport act ivity that give an opportunity to participants recognize their own limits and others and do they active not passive . This study was done as pretest - posttest control group with quasi - experimental model and the data were collected using „ Nowicki - Strickland Locus of Control Scale‟ adapted to Turkish by Yeşilyaprak (1988 . In this research, 90 students (40 female, 50 male aged 17 ,75 ±1.06 participated voluntery and divided in two groups as a trail and control group randomly. Trial group participated artifcial wall climbing twice a week, totel six weeks. During this time period the control group not join any activity has continued to normal life. As a result of the statistical analysis, no significant difference s were found between control and trial groups pre - test scores (p>0.05. No significant difference s were found between pre and post - test scores of control group (p>0.05, significant differences were found between pre and post - test scores of trial group (p0.05 and no significant differences between the difference of the differences (p>0.05. C onsequently, it could be said that the articifal wall climbing activities has a positive efect on the particip ants‟ locus of control, it caused a movement from out side to inside. And it has a significant effect on gender differences, that women have more gain than men.

Optical Fiber Sensing Based on Reflection Laser Spectroscopy

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Gianluca Gagliardi

2010-03-01

Full Text Available An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs and FBG resonators built in fibers of different types are used for strain, temperature and acceleration measurements using heterodyne-detection and optical frequency-locking techniques. Silica fiber-ring cavities are used for chemical sensing based on evanescent-wave spectroscopy. Various arrangements for signal recovery and noise reduction, as an extension of most typical spectroscopic techniques, are illustrated and results on detection performances are presented.

Innovative gait robot for the repetitive practice of floor walking and stair climbing up and down in stroke patients

OpenAIRE

Hesse, Stefan; Waldner, Andreas; Tomelleri, Christopher

2010-01-01

Abstract Background Stair climbing up and down is an essential part of everyday's mobility. To enable wheelchair-dependent patients the repetitive practice of this task, a novel gait robot, G-EO-Systems (EO, Lat: I walk), based on the end-effector principle, has been designed. The trajectories of the foot plates are freely programmable enabling not only the practice of simulated floor walking but also stair climbing up and down. The article intended to compare lower limb muscle activation pat...

Optical microphone with fiber Bragg grating and signal processing techniques

Science.gov (United States)

Tosi, Daniele; Olivero, Massimo; Perrone, Guido

2008-06-01

In this paper, we discuss the realization of an optical microphone array using fiber Bragg gratings as sensing elements. The wavelength shift induced by acoustic waves perturbing the sensing Bragg grating is transduced into an intensity modulation. The interrogation unit is based on a fixed-wavelength laser source and - as receiver - a photodetector with proper amplification; the system has been implemented using devices for standard optical communications, achieving a low-cost interrogator. One of the advantages of the proposed approach is that no voltage-to-strain calibration is required for tracking dynamic shifts. The optical sensor is complemented by signal processing tools, including a data-dependent frequency estimator and adaptive filters, in order to improve the frequency-domain analysis and mitigate the effects of disturbances. Feasibility and performances of the optical system have been tested measuring the output of a loudspeaker. With this configuration, the sensor is capable of correctly detecting sounds up to 3 kHz, with a frequency response that exhibits a top sensitivity within the range 200-500 Hz; single-frequency input sounds inducing an axial strain higher than ~10nɛ are correctly detected. The repeatability range is ~0.1%. The sensor has also been applied for the detection of pulsed stimuli generated from a metronome.

Optical feedback-induced light modulation for fiber-based laser ablation.

Science.gov (United States)

Kang, Hyun Wook

2014-11-01

Optical fibers have been used as a minimally invasive tool in various medical fields. However, due to excessive heat accumulation, the distal end of a fiber often suffers from severe melting or devitrification, leading to the eventual fiber failure during laser treatment. In order to minimize thermal damage at the fiber tip, an optical feedback sensor was developed and tested ex vivo. Porcine kidney tissue was used to evaluate the feasibility of optical feedback in terms of signal activation, ablation performance, and light transmission. Testing various signal thresholds demonstrated that 3 V was relatively appropriate to trigger the feedback sensor and to prevent the fiber deterioration during kidney tissue ablation. Based upon the development of temporal signal signatures, full contact mode rapidly activated the optical feedback sensor possibly due to heat accumulation. Modulated light delivery induced by optical feedback diminished ablation efficiency by 30% in comparison with no feedback case. However, long-term transmission results validated that laser ablation assisted with optical feedback was able to almost consistently sustain light delivery to the tissue as well as ablation efficiency. Therefore, an optical feedback sensor can be a feasible tool to protect optical fiber tips by minimizing debris contamination and delaying thermal damage process and to ensure more efficient and safer laser-induced tissue ablation.

Fiber Optic Calorimetry

International Nuclear Information System (INIS)

Rudy, C.; Bayliss, S.; Bracken, D.; Bush, J.; Davis, P.

1997-01-01

A twin-bridge calorimeter using optical fiber as the sensor element was constructed and tested. This system demonstrates the principle and capability of using optical fibers for heat-flow measurements of special nuclear material. This calorimeter uses piezoelectric-generated phase-carrier modulation with subsequent electronic signal processes to allow phase shifts as small as 1 microradian (microrad) to be measured. The sensing element consists of 21-m lengths of single-mode optical fiber wrapped around sample and reference chambers. The sensitivity of the calorimeter was determined to be 74 radians (rad) of phase shift per milliwatt of thermal power. One milliwatt of thermal power is equivalent to 400 mg of plutonium (6% 240 Pu). The system noise base was about 0.2 rad, equivalent to about 1 mg of plutonium

Fiber optic calorimetry

International Nuclear Information System (INIS)

Rudy, C.R.; Bayliss, S.C.; Bracken, D.S.; Bush, I.J.; Davis, P.G.

1998-01-01

A twin-bridge calorimeter using optical fiber as the sensor element was constructed and tested. This system demonstrates the principle and capability of using optical fibers for heat-flow measurements of special nuclear material. This calorimeter uses piezoelectric-generated phase-carrier modulation with subsequent electronic signal processing to allow phase shifts as small as 1 microrad to be measured. The sensing element consists of 21-m lengths of single-mode optical fiber wrapped around sample and reference chambers. The sensitivity of the calorimeter was determined to be 74 rad of phase shift per mW of thermal power. One milliwatt of thermal power is equivalent to 400 mg of plutonium (6% 240 Pu). The system noise base was about 0.2 rad, equivalent to about 1 mg of plutonium

Fiber optic calorimetry

International Nuclear Information System (INIS)

Rudy, C.; Bayliss, S.; Bracken, D.; Bush, J.; Davis, P.

1998-01-01

A twin-bridge calorimeter using optical fiber as the sensor element was constructed and tested. This system demonstrates the principle and capability of using fiber for heat-flow measurements of special nuclear material. This calorimeter uses piezoelectric-generated phase-carrier modulation with subsequent electronic signal processing to allow phase shifts as small as 1 microradian (μrad) to be measured. The sensing element consists of 21-m lengths of single-mode optical fiber wrapped around sample and reference chambers. The sensitivity of the calorimeter was determined to be 74 radians (rad) of phase shift per milliwatt of thermal power. One milliwatt of thermal power is equivalent to 400 mg of plutonium (6% 240 Pu). The system noise base was about 0.2 rad, equivalent to about 1 mg of plutonium

Effects of stair-climbing on balance, gait, strength, resting heart rate, and submaximal endurance in healthy seniors.

Science.gov (United States)

Donath, L; Faude, O; Roth, R; Zahner, L

2014-04-01

Stair-climbing serves as a feasible opportunity to remain physically active within everyday-life. Data on neuromuscular and cardiorespiratory performance after regular stair-climbing in seniors are scarce. Forty-eight seniors were stratified to a one- (taking every step, INT1) or two-step strategy (every second step, INT2) or a control group (CON). Thirty-nine seniors [females: n = 22, males: n = 17; age: 70.5 (SD 5.1) years; BMI: 25.8 (3.1) kg/m(2)] completed the 8-week intervention (three weekly sessions). Before and after the intervention, balance, gait, strength, and submaximal endurance (at different intensities) were assessed. Maximal strength and explosive power did not improve significantly (0.10 walking significantly decreased (-11/min; P beam balancing (4.5 cm width) increased in INT2 (P = 0.007) compared with CON. With more pronounced effects in INT2, stair-climbing significantly improved resting and exercise heart rates, perceived exertion, and dynamic balance performance in healthy seniors and may contribute to better overall fitness, reduced fall risk, and less perceived strain during daily life activities. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Thermally switchable adhesions of polystyrene-block-poly(n-isopropylacrylamide) copolymer pillar array mimicking climb attitude of geckos

Science.gov (United States)

Chen, Jem-Kun; Wang, Jing-Hong; Chang, Jia-Yaw; Fan, Shih-Kang

2012-09-01

Inspired by the gecko foot pad, we fabricated polystyrene-block-poly(N-isopropylacrylamide) (PS-b-PNIPAAm) copolymer pillar array to mimic climbing attitude of a gecko, alternately attach to and detach from a surface. The pillar array structure of the PS segment significantly enhances both of the hydrophilic and hydrophobic property of PNIPAAm segment tips at 25 and 50 °C, respectively, which could generate alternating adhesive forces of approximately 120 and 11 nN. The dramatic change in adhesive and friction force difference at 25 and 50 °C may guide the design of bio-inspired artificial analogues, which could approach gecko's climbing behavior.

Applications of plastic optical fiber in communication

Science.gov (United States)

Tayahi, Moncef Ben

In this thesis, we report the results of our theoretical and experimental studies of large core polymer fibers. This relatively low loss and high bandwidth plastic optical fiber (POF) potentially have important applications in LAN. We measured the power penalty due to modal noise. We also developed a model to calculate the signal to noise ratio (SNR) and the bit error rate (BER) floor just by knowing the coupling coefficient in the mode selective loss being considered. The calculated bandwidth using the WKB approximation was found to be 0.44 GHz per 100 m, which is much lower than the measured bandwidth of 3 GHz per 100 m. This discrepancy was explained by the presence of strong mode coupling in POFs. We studied distortions products in CATV systems. Composite second order (CSO) and composite triple beat (CTB) for different channels were measured using a spectrum analyzer and adjustable band pass filter. Since the CSO and the CTB did not meet the CATV standard, a predistortion circuit was used to minimize CSO and CTB products produced by the laser. The predistortion circuit provides a signal comprising multiple subcarrier signals substantially equal in magnitude and opposite in phase to those associated with the nonlinear transfer function of the laser being deployed. The RF signal is split into a primary branch that has a time delayed portion (80% of the RF signal), the secondary branch (10% of the RF signal) is where the second order products are generated with a 180 °phase shift from the fundamental, and the last remaining 10% of the RF signal is where the third order distortion products are generated with a 180 °phase shift from the fundamental. The output signal is taken as the summation of three signals processed by the branch circuits and coupled to the directly to the laser to be linearized. Finally, using cyclic transparent optical polymer (CYTOP), a perfluorinated graded index fiber, different transmission characteristics were investigated. CYTOP fiber

Physiological responses to simulated stair climbing in professional firefighters wearing rubber and leather boots.

Science.gov (United States)

Huang, Chun-Jung; Garten, Ryan S; Wade, Chip; Webb, Heather E; Acevedo, Edmund O

2009-09-01

No studies have considered whether a firefighter's boots are a factor influencing physiological responses. The purpose of this study was to examine physiological responses to a fire simulation activity (stair climb) in professional firefighters wearing rubber boots (RB) and leather boots (LB). Twelve professional firefighters participated in two counterbalanced simulated firefighter stair climb (SFSC) sessions, one wearing RB and the other wearing LB. Heart rate, oxygen uptake (VO(2)), expiratory ventilation (V(E)), blood lactate (BLa), salivary cortisol (SCORT), and leg strength were assessed prior to and following a SFSC. LB elicited significantly greater SCORT values and knee flexion time to peak torque. Furthermore, RB revealed significantly greater ankle dorsiflexion peak torque after SFSC. BLa was positively related to knee flexion peak torque after SFSC in the RB. Firefighters when wearing the RB may be more effective at resisting fatigue and increase more force production.

Development of an optical fiber SERS microprobe for minimally invasive sensing applications

Science.gov (United States)

Mamun, Md Abdullah Al; Juodkazis, Saulius; Mahadevan-Jansen, Anita; Stoddart, Paul R.

2018-02-01

Numerous potential biomedical sensing applications of surface-enhanced Raman scattering (SERS) have been reported, but its practical use has been limited by the lack of a robust sensing platform. Optical fiber SERS probes show great promise, but are limited by the prominent silica Raman background, which requires the use of bulky optics for filtering the signal collection and excitation delivery paths. In the present study, a SERS microprobe has been designed and developed to eliminate the bottlenecks outlined above. For efficient excitation and delivery of the SERS signal, both hollow core photonic crystal fiber and double clad fiber have been investigated. While the hollow core fiber was still found to have excessive silica background, the double clad fiber allows efficient signal collection via the multi-mode inner cladding. A micro filtering mechanism has been designed, which can be integrated into the tip of the optical fiber SERS probe, providing filtering to suppress silica Raman background and thus avoiding the need for bulky optics. The design also assists in the efficient collection of SERS signal from the sample by rejecting Rayleigh scattered light from the sample. Optical fiber cleaving using ultra-short laser pulses was tested for improved control of the fiber tip geometry. With this miniaturized and integrated filtering mechanism, it is expected that the developed probe will promote the use of SERS for minimally invasive biomedical monitoring and sensing applications in future. The probe could potentially be placed inside a small gauge hypodermic needle and would be compatible with handheld portable spectrometers.

Classification of reflected signals from cavitated tooth surfaces using an artificial intelligence technique incorporating a fiber optic displacement sensor

Science.gov (United States)

Rahman, Husna Abdul; Harun, Sulaiman Wadi; Arof, Hamzah; Irawati, Ninik; Musirin, Ismail; Ibrahim, Fatimah; Ahmad, Harith

2014-05-01

An enhanced dental cavity diameter measurement mechanism using an intensity-modulated fiber optic displacement sensor (FODS) scanning and imaging system, fuzzy logic as well as a single-layer perceptron (SLP) neural network, is presented. The SLP network was employed for the classification of the reflected signals, which were obtained from the surfaces of teeth samples and captured using FODS. Two features were used for the classification of the reflected signals with one of them being the output of a fuzzy logic. The test results showed that the combined fuzzy logic and SLP network methodology contributed to a 100% classification accuracy of the network. The high-classification accuracy significantly demonstrates the suitability of the proposed features and classification using SLP networks for classifying the reflected signals from teeth surfaces, enabling the sensor to accurately measure small diameters of tooth cavity of up to 0.6 mm. The method remains simple enough to allow its easy integration in existing dental restoration support systems.

A hybrid optic-fiber sensor network with the function of self-diagnosis and self-healing

Science.gov (United States)

Xu, Shibo; Liu, Tiegen; Ge, Chunfeng; Chen, Cheng; Zhang, Hongxia

2014-11-01

We develop a hybrid wavelength division multiplexing optical fiber network with distributed fiber-optic sensors and quasi-distributed FBG sensor arrays which detect vibrations, temperatures and strains at the same time. The network has the ability to locate the failure sites automatically designated as self-diagnosis and make protective switching to reestablish sensing service designated as self-healing by cooperative work of software and hardware. The processes above are accomplished by master-slave processors with the help of optical and wireless telemetry signals. All the sensing and optical telemetry signals transmit in the same fiber either working fiber or backup fiber. We take wavelength 1450nm as downstream signal and wavelength 1350nm as upstream signal to control the network in normal circumstances, both signals are sent by a light emitting node of the corresponding processor. There is also a continuous laser wavelength 1310nm sent by each node and received by next node on both working and backup fibers to monitor their healthy states, but it does not carry any message like telemetry signals do. When fibers of two sensor units are completely damaged, the master processor will lose the communication with the node between the damaged ones.However we install RF module in each node to solve the possible problem. Finally, the whole network state is transmitted to host computer by master processor. Operator could know and control the network by human-machine interface if needed.

All-fiber incoherent frequency-to-time mapping method for microwave signal generation with baseband transmission and multicasting support

DEFF Research Database (Denmark)

Company Torres, Victor; Tafur Monroy, Idelfonso; Lancis, Jesus

2008-01-01

We present a proof-of-principle experiment for achieving simultaneous distribution of baseband radio-frequency data and up-conversion with broadcasting support over a passive optical network. The technique is based on an incoherent frequency-to-time mapping method for pulse shaping. Specifically...... resembles the shape of the incoherent source. The photodetected signal contains both the baseband data and an up-frequency converted copy with central wavelength for the microwave carrier into the ultra-wideband range and tuning capability by selection of the fiber length. (c) 2008 Elsevier B.V. All rights...

Hybrid opto-digital signal processing in 112 Gbit/s DP-16QAM and DP-QDB transmission for long-haul large-Aeff pure-silica-core fiber links

DEFF Research Database (Denmark)

Asif, Rameez; Ahmad, Ramshah; Basir, Rabeea

2016-01-01

By means of numerical simulations, we demonstrated that all-optical signal processing methods (XPM-suppressor module and in-line nonlinear equalization) significantly increase the system performance of digital nonlinear compensation (digital backward propagation) and improve the system performanc...... in five-channel 112 Gbit/s DP-16QAM and DP-QDB transmission over 2400 km large- effective-area pure-silica-core fiber ((Formula presented.)-PSCF). The system performance is quantified with the help of Q-factor (dB) for both dispersion-managed and nondispersion-managed fiber links....

Cerium-doped scintillating fused-silica fibers

Science.gov (United States)

Akchurin, N.; Cowden, C.; Damgov, J.; Dragoiu, C.; Dudero, P.; Faulkner, J.; Kunori, S.

2018-04-01

We report on a set of measurements made on (scintillating) cerium-doped fused-silica fibers using high-energy particle beams. These fibers were uniformly embedded in a copper absorber in order to utilize electromagnetic showers as a source of charged particles for generating signals. This new type of cerium-doped fiber potentially offers myriad new applications in calorimeters in high-energy physics, tracking systems, and beam monitoring detectors for future applications. The light yield, pulse shape, attenuation length, and light propagation speeds are given and discussed. Possible future applications are also explored.

Multigigabit W-Band (75–110 GHz) Bidirectional Hybrid Fiber-Wireless Systems in Access Networks

DEFF Research Database (Denmark)

Pang, Xiaodan; Lebedev, Alexander; Vegas Olmos, Juan José

2014-01-01

compare the transmission performances in terms of achievable wireless distances with and without using a high-frequency electrical power amplifier at the wireless transmitter. A downlink 16-Gbit/s QPSK signal and an uplink 1.25-Gbit/s ASK signal transmission over the two implementations are experimentally......We experimentally demonstrate multigigabit capacity bidirectional hybrid fiber-wireless systems with RF carrier frequencies at the W-band (75-110 GHz) that enables the seamless convergence between wireless and fiber-optic data transmission systems in access networks. In this study, we evaluate...... the transmission performances in two scenarios: a fiber-wireless access link that directly provide high-speed connections to wireless end users, and a fiber-wireless-fiber signal relay where a high capacity wireless link can be used to bridge two access fiber spans over physical obstacles. In both scenarios, we...

Hamilton-Jacobi-Bellman approach for the climbing problem for heavy launchers

OpenAIRE

Bokanowski , Olivier; Cristiani , Emiliano; Laurent-Varin , Julien; Zidani , Hasnaa

2012-01-01

International audience; In this paper we investigate the Hamilton-Jacobi-Bellman (HJB) approach for solving a complex real-world optimal control problem in high dimension. We consider the climbing problem for the European launcher Ariane V: The launcher has to reach the Geostationary Transfer Orbit with minimal propellant consumption under state/control constraints. In order to circumvent the well-known curse of dimensionality, we reduce the number of variables in the model exploiting the spe...

Wavelength conversion of a 40 Gb/s RZ-DPSK signal using four-wave mixing in a dispersion-flattened highly nonlinear photonic crystal fiber

DEFF Research Database (Denmark)

Andersen, Peter Andreas; Tokle, Torger; Geng, Yan

2005-01-01

Wavelength conversion of a 40-Gb/s return-to-zero differential phase-shift keying signal is demonstrated in a highly nonlinear photonic crystal fiber (HNL-PCF) for the first time. A conversion efficiency of -20 dB for a pump power of 23 dBm and a conversion bandwidth of 31 nm, essentially limited...

A survey of safety issues in tree-climbing applications for forestry management

Directory of Open Access Journals (Sweden)

D. Longo

2013-09-01

Full Text Available Topping, trimming, consolidation, securing and felling are very common operations in arboriculture, in city park as well as in forests. In case of very large trees, these operations are often not possible from ground level using ladders or Mobile Elevating Work Platforms (MEWPs because of excessive height or uneven/inaccessible terrain. In past years, different people start applying techniques, materials and procedures normally used in mountaineering and caving, to climb trees and these techniques start to be applied to forestry management operations; these techniques are now worldwide used. Work activities at height, as tree-climbing for forestry management purpose, are regulated in Italy by Legislative Decree 81/08 about safety in the workplace, as this activity expose operators to fall from height and many other risks. Moreover, as this activity involves the use of specific tools, operators must be trained (with periodic refreshment and tools must been periodically checked by authorised operators. The objective of this work is to present and synthesise regulations and some technical aspects in order to allow operators to better understand different issues and general principles related to this activity.

Reliability improvement methods for sapphire fiber temperature sensors

Science.gov (United States)

Schietinger, C.; Adams, B.

1991-08-01

Mechanical, optical, electrical, and software design improvements can be brought to bear in the enhancement of fiber-optic sapphire-fiber temperature measurement tool reliability in harsh environments. The optical fiber thermometry (OFT) equipment discussed is used in numerous process industries and generally involves a sapphire sensor, an optical transmission cable, and a microprocessor-based signal analyzer. OFT technology incorporating sensors for corrosive environments, hybrid sensors, and two-wavelength measurements, are discussed.

Crystal-free Formation of Non-Oxide Optical Fiber

Science.gov (United States)

Nabors, Sammy A.

2015-01-01

Researchers at NASA Marshall Space Flight Center have devised a method for the creation of crystal-free nonoxide optical fiber preforms. Non-oxide fiber optics are extensively used in infrared transmitting applications such as communication systems, chemical sensors, and laser fiber guides for cutting, welding and medical surgery. However, some of these glasses are very susceptible to crystallization. Even small crystals can lead to light scatter and a high attenuation coefficient, limiting their usefulness. NASA has developed a new method of non-oxide fiber formation that uses axial magnetic fields to suppress crystallization. The resulting non-oxide fibers are crystal free and have lower signal attenuation rates than silica based optical fibers.

Application technology for optical fiber in nuclear facilities

International Nuclear Information System (INIS)

Lee, Jong Min; Kim, Chul Jung; Lee, Yong Bum; Kim, Woong Ki; Yoon, Tae Seob; Sohn, Surg Won; Kim, Chang Hoi; Hwang, Suk Yong; Baik, Sung Hum; Kwon, Seong Ouk

1987-12-01

Lately, the optical fiber increasingly used in such adverse environments as nuclear power plant, radiation facilities because of their endurant properties against heat, radiation, corrosion, etc. Moreover, the transmission of signal through optical fiber does not induce interference from the electromagnetic wave. Basic theory about the optical fiber technology was studied and the developed techniques for nuclear facilities were reviewed. Since the radiations change the characteristics of the optical fiber, the effects of γ-ray irradiation on single mode and multimode optical fiber were examined. The image transmission system through optical fiber bundle was designed, constructed, and tested. Its software system was also updated. It can be used for remote internal inspection in adverse environment. (Author)

Monolithic Yb-fiber femtosecond laser with intracavity all-solid PBG fiber and ex-cavity HC-PCF

DEFF Research Database (Denmark)

Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

2010-01-01

(PM) photonic bandgap fiber (PBG) is used in the cavity of the master oscillator for dispersion compensation and stabilization of modelocking. The final compression of an chirped-pulse-amplified laser signal is performed in a hollow PM PCF, yielding final fiber-delivered pulse energy of around 7 n......J, and pulse duration of around 297 fs. The self-stabilization mechanism of the oscillator, based on the optical nonlinearities in an AS PCF, results in excellent environmental and operational stability of our laser. Stable self-starting fundamental modelocking is maintained for at least 4 days of operation......We demonstrate an all-fiber femtosecond master oscillator / power amplifier operating at the central wavelength of 1033 nm, based on Yb-doped fiber as gain medium, and two different kinds of photonic crystal fibers for dispersion control and stabilization. An all-solid (AS) polarization maintaining...

Stimulated Brillouin scattering threshold in fiber amplifiers

International Nuclear Information System (INIS)

Liang Liping; Chang Liping

2011-01-01

Based on the wave coupling theory and the evolution model of the critical pump power (or Brillouin threshold) for stimulated Brillouin scattering (SBS) in double-clad fiber amplifiers, the influence of signal bandwidth, fiber-core diameter and amplifier gain on SBS threshold is simulated theoretically. And experimental measurements of SBS are presented in ytterbium-doped double-clad fiber amplifiers with single-frequency hundred nanosecond pulse amplification. Under different input signal pulses, the forward amplified pulse distortion is observed when the pulse energy is up to 660 nJ and the peak power is up to 3.3 W in the pulse amplification with pulse duration of 200 ns and repetition rate of 1 Hz. And the backward SBS narrow pulse appears. The pulse peak power equals to SBS threshold. Good agreement is shown between the modeled and experimental data. (authors)

A study on a wheel-based stair-climbing robot with a hopping mechanism

Science.gov (United States)

Kikuchi, Koki; Sakaguchi, Keisuke; Sudo, Takayuki; Bushida, Naoki; Chiba, Yasuhiro; Asai, Yuji

2008-08-01

In this study, we propose a simple hopping mechanism using the vibration of a two-degree-of-freedom system for a wheel-based stair-climbing robot. The robot, consisting of two bodies connected by springs and a wire, hops by releasing energy stored in the springs and quickly travels using wheels mounted in its lower body. The trajectories of the bodies during hopping change in accordance with the design parameters, such as the reduced mass of the two bodies, the mass ratio between the upper and lower bodies, the spring constant, the control parameters such as the initial contraction of the spring and the wire tension. This property allows the robot to quickly and economically climb up and down stairs, leap over obstacles, and landing softly without complex control. In this paper, the characteristics of hopping motion for the design and control parameters are clarified by both numerical simulations and experiments. Furthermore, using the robot design based on the results the abilities to hop up and down a step, leap over a cable, and land softly are demonstrated.

An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography.

Science.gov (United States)

Eom, Jonghyun; Shin, Jun Geun; Park, Soongho; Rim, Sunghwan; Lee, Byeong Ha

2016-05-20

We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT) and optical coherence tomography (OCT). The PAT remotely measures photoacoustic (PA) signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF) and a large-core multimode fiber (MMF). The compact and robust common probe is capable of obtaining both the PA and the OCT signals at the same position without any physical contact. Additionally, the MMF of the probe delivers the short pulses of a Nd:YAG laser to efficiently excite the PA signals. We experimentally demonstrate the feasibility of the proposed dual-modal system with a phantom made of a fishing line and a black polyethylene terephthalate fiber in a tissue mimicking solution. The all-fiber-optic system, capable of providing complementary information about absorption and scattering, has a promising potential in minimally invasive and endoscopic imaging.

An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography

Science.gov (United States)

Eom, Jonghyun; Shin, Jun Geun; Park, Soongho; Rim, Sunghwan; Lee, Byeong Ha

2016-01-01

We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT) and optical coherence tomography (OCT). The PAT remotely measures photoacoustic (PA) signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF) and a large-core multimode fiber (MMF). The compact and robust common probe is capable of obtaining both the PA and the OCT signals at the same position without any physical contact. Additionally, the MMF of the probe delivers the short pulses of a Nd:YAG laser to efficiently excite the PA signals. We experimentally demonstrate the feasibility of the proposed dual-modal system with a phantom made of a fishing line and a black polyethylene terephthalate fiber in a tissue mimicking solution. The all-fiber-optic system, capable of providing complementary information about absorption and scattering, has a promising potential in minimally invasive and endoscopic imaging. PMID:27213392

An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography

Directory of Open Access Journals (Sweden)

Jonghyun Eom

2016-05-01

Full Text Available We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT and optical coherence tomography (OCT. The PAT remotely measures photoacoustic (PA signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF and a large-core multimode fiber (MMF. The compact and robust common probe is capable of obtaining both the PA and the OCT signals at the same position without any physical contact. Additionally, the MMF of the probe delivers the short pulses of a Nd:YAG laser to efficiently excite the PA signals. We experimentally demonstrate the feasibility of the proposed dual-modal system with a phantom made of a fishing line and a black polyethylene terephthalate fiber in a tissue mimicking solution. The all-fiber-optic system, capable of providing complementary information about absorption and scattering, has a promising potential in minimally invasive and endoscopic imaging.

Improved extrinsic polymer optical fiber sensors for gamma-ray monitoring in radioprotection applications

Science.gov (United States)

de Andrés, A. I.; Esteban, Ó.; Embid, M.

2017-08-01

Gamma radiation detection in the range of 662 keV, the reference for environmental protection, is done through extrinsic optical fiber sensors. The fluorescence rendered by an inorganic scintillator when irradiated with such gamma rays is gathered by a modified polymer optical fiber tip. This modification increases the recorded signal when compared with plain unaltered fiber. Two fiber tip modification are then compared in terms of light gathering capability. A chemically etched fiber, in which the cladding and part of the core are removed, and a tapered fiber in which the core-cladding structure is kept. Both structures are comparable in length and final diameter, and show linear response in the tested range up to 2 Gy/h air Kerma rate. The etched fiber shows a higher slope than the tapered one, although both improve the signal gathered by a plain fiber tip. The easy fabrication and handling of the reported transducers, together with the improved signal gathering, allow to reduce the overall system budget with the use of low-cost optoelectronics in the detection stage. This offers a significant improvement for surveillance systems in radioprotection applications, in which presence of gamma radiation coming out accidental leakage or spurious sources activity is the main target.

DSP-Based Focusing over Optical Fiber Using Time Reversal

DEFF Research Database (Denmark)

Piels, Molly; Porto da Silva, Edson; Estaran Tolosa, Jose Manuel

2014-01-01

A time-reversal array in multimode fiber is proposed for lossless switching using passive optical splitters. Numerical investigations are performed, and a two-transmitter array that routes a 3GBd QPSK signal through the physical layer is demonstrated experimentally.......A time-reversal array in multimode fiber is proposed for lossless switching using passive optical splitters. Numerical investigations are performed, and a two-transmitter array that routes a 3GBd QPSK signal through the physical layer is demonstrated experimentally....

Existing PON Infrastructure Supported Hybrid Fiber-Wireless Sensor Networks

DEFF Research Database (Denmark)

Yu, Xianbin; Zhao, Ying; Deng, Lei

2012-01-01

We propose a hybrid fiber wireless sensor network based on the existing PON infrastructure. The feasibility of remote sensing and PON convergence is experimentally proven by transmitting direct-sequence spread-spectrum wireless sensing and 2.5Gbps GPON signals.......We propose a hybrid fiber wireless sensor network based on the existing PON infrastructure. The feasibility of remote sensing and PON convergence is experimentally proven by transmitting direct-sequence spread-spectrum wireless sensing and 2.5Gbps GPON signals....

Radiation resistance of optical fibers, (10)

International Nuclear Information System (INIS)

Tsunoda, Tsunemi; Ara, Katsuyuki; Morimoto, Naoki; Sanada, Kazuo; Inada, Koichi.

1991-01-01

Optical fibers have many excellent characteristics such as the light weight of the material, insulation, the noninductivity of electromagnetic interference noise, the wide band of signal transmission, and small loss. Also in the field of atomic energy, the utilization of optical fibers is positively expanded, and the research on the method of application and so on has been advanced. However in optical fibers, there is the problem that color centers are formed at the relatively low level of radiation, and they are colored. Accordingly, for effectively utilizing optical fibers in radiation environment, it is indispensable to improve their radiation resistance. For the purpose of solving this problem, the authors have carried out the basic research on the effect that radiation exerts to optical fibers and the development of the optical fibers having excellent radiation resistance. For the purpose of expanding the range of application of GeO 2 -doped silica core fibers including GI type in radiation regions, the transmission characteristics of the fibers during irradiation were examined by using the Cl content as the parameter. Therefore, the results are reported. The fibers put to the test, the testing method and the results are described. (K.I.)

THE IMPACT OF SPORT CLIMBING ON SOME MORPHOLOGICAL CHARACTERISTICS AND MOTOR ABILITIES IN CLIMBERS OF 14 YEARS OF AGE

Directory of Open Access Journals (Sweden)

Blaž Jereb

2009-11-01

Full Text Available The objective of our research was to identify the impact of sport climbing on some morphologic characteristics and motor abilities in climbers. The sample group consisted of 19 climbers, who trained climbing for one year beside their regular physical education after the initially survey was made, and 72 nonclimbers, who’s only sport activity was their regular physical education. At the time of the test, climbers as well as nonclimbers were 14 years of age. The measurement included all the variables from the Physical education chart. Data were processed with statistical programme package SPSS for Windows. The result of analysis of covariance show that after a year long period of sport climbing statistically significant differences were shown in the results of t he test Polygon backwards in favour of the experimental group. It is also possible to observe a trend towards better results of the experimental group in the tests Skin fold thickness of the upper arm and Bend and touch on bench. The nonclimbers achieved larger differences than climbers in torso lifting and 600 m run.

All fiber passively mode locked zirconium-based erbium-doped fiber laser

Science.gov (United States)

Ahmad, H.; Awang, N. A.; Paul, M. C.; Pal, M.; Latif, A. A.; Harun, S. W.

2012-04-01

All passively mode locked erbium-doped fiber laser with a zirconium host is demonstrated. The fiber laser utilizes the Non-Linear Polarization Rotation (NPR) technique with an inexpensive fiber-based Polarization Beam Splitter (PBS) as the mode-locking element. A 2 m crystalline Zirconia-Yttria-Alumino-silicate fiber doped with erbium ions (Zr-Y-Al-EDF) acts as the gain medium and generates an Amplified Spontaneous Emission (ASE) spectrum from 1500 nm to 1650 nm. The generated mode-locked pulses have a spectrum ranging from 1548 nm to more than 1605 nm, as well as a 3-dB bandwidth of 12 nm. The mode-locked pulse train has an average output power level of 17 mW with a calculated peak power of 1.24 kW and energy per pulse of approximately 730 pJ. The spectrum also exhibits a Signal-to-Noise Ratio (SNR) of 50 dB as well as a repetition rate of 23.2 MHz. The system is very stable and shows little power fluctuation, in addition to being repeatable.

Independent component analysis based digital signal processing in coherent optical fiber communication systems

Science.gov (United States)

Li, Xiang; Luo, Ming; Qiu, Ying; Alphones, Arokiaswami; Zhong, Wen-De; Yu, Changyuan; Yang, Qi

2018-02-01

In this paper, channel equalization techniques for coherent optical fiber transmission systems based on independent component analysis (ICA) are reviewed. The principle of ICA for blind source separation is introduced. The ICA based channel equalization after both single-mode fiber and few-mode fiber transmission for single-carrier and orthogonal frequency division multiplexing (OFDM) modulation formats are investigated, respectively. The performance comparisons with conventional channel equalization techniques are discussed.

A novel method for length of chirped fiber Bragg grating sensor

Science.gov (United States)

Li, Zhenwei; Wei, Peng; Liu, Taolin

2018-03-01

Length of chirped fiber Bragg grating sensor is very important for detonation velocity. Different from other ways, we proposed a novel method based on the optical frequency domain reflection theory to measure the length of chirped fiber grating sensor in non-contact condition. This method adopts a tunable laser source to provide wavelength scanning laser, which covers the Full Width at Half Maximum of spectrum of the chirped fiber Bragg grating sensor. A Michelson interferometer is used to produce optical interference signal. Finally, the grating's length is attainable by distance domain signal. In theory, length resolution of chirped fiber Bragg grating sensor could be 0.02 mm. We perform a series of length measurement experiments for chirped fiber grating sensor, including comparison experiments with hot-tip method. And the experiment results show that the novel method could accurately measure the length of chirped fiber Bragg grating sensors, and the length differences between the optical frequency domain reflection method and the hot-tip probe method are very small.

The characteristics of acoustic emission signal under composite destruction on GFRP gas cylinder

International Nuclear Information System (INIS)

Jee, Hyun Sup; Lee, Jong O; Ju, No Hoe; So, Cheal Ho; Lee, Jong Kyu

2013-01-01

This study is investigation of the characteristics for acoustic emission signal generated by destruction on glass fiber bundles and specimen that was machined composite materials surrounding the outside of GFRP cylinder. The Amplitude of acoustic emission signal gets bigger as the cutting angle of knife increases. Accordingly, the number of hits in destruction of composite materials specimen have more in longitudinal direction (longitudinal direction to the glass fiber) than in hoop direction (horizontal direction to the glass fiber) while the amplitude of signals were bigger in hoop direction than longitudinal direction. It was found out that the amplitude of the glass fiber breakage is more than 40 dB and that the amplitude of signal for matrix crack was less than 40 dB because matrix crack signal was not observed when threshold value is 40 dB and matrix crack signal suddenly appeared when threshold value is 32 dB. The slope of the amplitude is related to the acoustic emission source and the slope of the amplitude of the horizontal and vertical directions are 0.16 and 0.08. In particular, The slope of the amplitude of longitudinal direction breakage appear similar to the glass fiber breakage and therefore Acoustic emission source of longitudinal direction breakage is estimated the glass fiber breakage.

Uniform spacing interrogation of a Fourier domain mode-locked fiber Bragg grating sensor system using a polarization-maintaining fiber Sagnac interferometer

Science.gov (United States)

Lee, Hwi Don; Jung, Eun Joo; Jeong, Myung Yung; Chen, Zhongping; Kim, Chang-Seok

2014-01-01

A novel linearized interrogation method is presented for a Fourier domain mode-locked (FDML) fiber Bragg grating (FBG) sensor system. In a high speed regime over several tens of kHz modulations, a sinusoidal wave is available to scan the center wavelength of an FDML wavelength-swept laser, instead of a conventional triangular wave. However, sinusoidal wave modulation suffers from an exaggerated non-uniform wavelength-spacing response in demodulating the time-encoded parameter to the absolute wavelength. In this work, the calibration signal from a polarization-maintaining fiber Sagnac interferometer shares the FDML wavelength-swept laser for FBG sensors to convert the time-encoded FBG signal to the wavelength-encoded uniform-spacing signal. PMID:24489440

Uniform spacing interrogation of a Fourier domain mode-locked fiber Bragg grating sensor system using a polarization-maintaining fiber Sagnac interferometer

International Nuclear Information System (INIS)

Lee, Hwi Don; Jeong, Myung Yung; Chen, Zhongping; Kim, Chang-Seok; Jung, Eun Joo

2013-01-01

A novel linearized interrogation method is presented for a Fourier domain mode-locked (FDML) fiber Bragg grating (FBG) sensor system. In a high speed regime over several tens of kHz modulations, a sinusoidal wave is available to scan the center wavelength of an FDML wavelength-swept laser, instead of a conventional triangular wave. However, sinusoidal wave modulation suffers from an exaggerated non-uniform wavelength-spacing response in demodulating the time-encoded parameter to the absolute wavelength. In this work, the calibration signal from a polarization-maintaining fiber Sagnac interferometer shares the FDML wavelength-swept laser for FBG sensors to convert the time-encoded FBG signal to the wavelength-encoded uniform-spacing signal. (paper)

Uniform spacing interrogation of a Fourier domain mode-locked fiber Bragg grating sensor system using a polarization-maintaining fiber Sagnac interferometer

Science.gov (United States)

Lee, Hwi Don; Jung, Eun Joo; Jeong, Myung Yung; Chen, Zhongping; Kim, Chang-Seok

2013-06-01

A novel linearized interrogation method is presented for a Fourier domain mode-locked (FDML) fiber Bragg grating (FBG) sensor system. In a high speed regime over several tens of kHz modulations, a sinusoidal wave is available to scan the center wavelength of an FDML wavelength-swept laser, instead of a conventional triangular wave. However, sinusoidal wave modulation suffers from an exaggerated non-uniform wavelength-spacing response in demodulating the time-encoded parameter to the absolute wavelength. In this work, the calibration signal from a polarization-maintaining fiber Sagnac interferometer shares the FDML wavelength-swept laser for FBG sensors to convert the time-encoded FBG signal to the wavelength-encoded uniform-spacing signal.

High-power fiber optic cable with integrated active sensors for live process monitoring

Science.gov (United States)

Blomster, Ola; Blomqvist, Mats; Bergstrand, Hans; Pålsson, Magnus

2012-03-01

In industrial applications using high-brilliance lasers at power levels up to and exceeding 20 kW and similarly direct diode lasers of 10 kW, there is an increasing demand to continuously monitor component status even in passive components such as fiber-optic cables. With fiber-optic cables designed according to the European Automotive Industry fiber standard interface there is room for integrating active sensors inside the connectors. In this paper we present the integrated active sensors in the new Optoskand QD fiber-optic cable designed to handle extreme levels of power losses, and how these sensors can be employed in industrial manufacturing. The sensors include photo diodes for detection of scattered light inside the fiber connector, absolute temperature of the fiber connector, difference in temperature of incoming and outgoing cooling water, and humidity measurement inside the fiber connector. All these sensors are connected to the fiber interlock system, where interlock break enable functions can be activated when measured signals are higher than threshold levels. It is a very fast interlock break system as the control of the signals is integrated in the electronics inside the fiber connector. Also, since all signals can be logged it is possible to evaluate what happened inside the connector before the interlock break instance. The communication to the fiber-optic connectors is via a CAN interface. Thus it is straightforward to develop the existing laser host control to also control the CAN-messages from the QD sensors.

Analog data transmission via fiber optics

International Nuclear Information System (INIS)

Cisneros, E.L.; Burgueno, G.F.

1987-01-01

In the SLAC Linear Collider Detector (SLD), as in most high-energy particle detectors, the electromagnetic noise environment is the limiting factor in electronic readout performance. Front-end electronics are particularly susceptible to electromagnetic interference (EMI), and great care has been taken to minimize its effects. The transfer of preprocessed analog signals from the detector environs, to the remote digital processing electronics, by conventional means (via metal conductors), may ultimately limit the performance of the system. Because it is highly impervious to EMI and ground loops, a fiber-optic medium has been chosen for the transmission of these signals. This paper describes several fiber-optic transmission schemes which satisfy the requirements of the SLD analog data transmission

Analog data transmission via fiber optics

International Nuclear Information System (INIS)

Cisneros, E.L.; Burgueno, G.F.

1986-10-01

In the SLAC Linear Collider Detector (SLD), as in most high-energy particle detectors, the electromagnetic noise environment is the limiting factor in electronic readout performance. Front-end electronics are particulary susceptible to electromagnetic interference (EMI), and great care has been taken to minimize its effects. The transfer of preprocessed analog signals from the detector environs, to the remote digital processing electronics, by conventional means (via metal conductors), may ultimately limit the performance of the system. Because it is highly impervious to EMI and ground loops, a fiber-optic medium has been chosen for the transmission of these signals. This paper describes several fiber-optic transmission schemes which satisfy the requirements of the SLD analog data transmission

Radiotherapy fiber dosimeter probes based on silver-only coated hollow glass waveguides

Science.gov (United States)

Darafsheh, Arash; Melzer, Jeffrey E.; Harrington, James A.; Kassaee, Alireza; Finlay, Jarod C.

2018-01-01

Manifestation of Čerenkov radiation as a contaminating signal is a significant issue in radiation therapy dose measurement by fiber-coupled scintillator dosimeters. To enhance the scintillation signal transmission while minimizing Čerenkov radiation contamination, we designed a fiber probe using a silver-only coated hollow waveguide (HWG). The HWG with scintillator inserted in its tip, embedded in tissue-mimicking phantoms, was irradiated with clinical electron and photon beams generated by a medical linear accelerator. Optical spectra of the irradiated tip were taken using a fiber spectrometer, and the signal was deconvolved with a linear fitting algorithm. The resultant decomposed spectra of the scintillator with and without Čerenkov correction were in agreement with measurements performed by a standard electron diode and ion chamber for electron and photon beam dosimetry, respectively, indicating the minimal effect of Čerenkov contamination in the HWG-based dosimeter. Furthermore, compared with a silver/dielectric-coated HWG fiber dosimeter design, we observed higher signal transmission in the design based on the use of silver-only HWG.

Local adaptation despite high gene flow in the waterfall-climbing Hawaiian goby, Sicyopterus stimpsoni.

Science.gov (United States)

Moody, K N; Hunter, S N; Childress, M J; Blob, R W; Schoenfuss, H L; Blum, M J; Ptacek, M B

2015-02-01

Environmental heterogeneity can promote the emergence of locally adapted phenotypes among subpopulations of a species, whereas gene flow can result in phenotypic and genotypic homogenization. For organisms like amphidromous fishes that change habitats during their life history, the balance between selection and migration can shift through ontogeny, making the likelihood of local adaptation difficult to predict. In Hawaiian waterfall-climbing gobies, it has been hypothesized that larval mixing during oceanic dispersal counters local adaptation to contrasting topographic features of streams, like slope gradient, that can select for predator avoidance or climbing ability in juvenile recruits. To test this hypothesis, we used morphological traits and neutral genetic markers to compare phenotypic and genotypic distributions in recruiting juveniles and adult subpopulations of the waterfall-climbing amphidromous goby, Sicyopterus stimpsoni, from the islands of Hawai'i and Kaua'i. We found that body shape is significantly different between adult subpopulations from streams with contrasting slopes and that trait divergence in recruiting juveniles tracked stream topography more so than morphological measures of adult subpopulation differentiation. Although no evidence of population genetic differentiation was observed among adult subpopulations, we observed low but significant levels of spatially and temporally variable genetic differentiation among juvenile cohorts, which correlated with morphological divergence. Such a pattern of genetic differentiation is consistent with chaotic genetic patchiness arising from variable sources of recruits to different streams. Thus, at least in S. stimpsoni, the combination of variation in settlement cohorts in space and time coupled with strong postsettlement selection on juveniles as they migrate upstream to adult habitats provides the opportunity for morphological adaptation to local stream environments despite high gene flow. © 2014

Inhibition of presynaptic activity by zinc released from mossy fiber terminals during tetanic stimulation.

Science.gov (United States)

Minami, Akira; Sakurada, Naomi; Fuke, Sayuri; Kikuchi, Kazuya; Nagano, Tetsuo; Oku, Naoto; Takeda, Atsushi

2006-01-01

Zinc exists in high densities in the giant boutons of hippocampal mossy fibers. On the basis of the evidence that zinc decreases extracellular glutamate concentration in the hippocampus, the presynaptic action of zinc released from mossy fibers during high-frequency (tetanic) stimulation was examined using hippocampal slices. The increase in zinc-specific fluorescent signals was observed in both extracellular and intracellular compartments in the mossy fiber terminals during the delivery of tetanic stimuli (100 Hz, 1 sec) to the dentate granule cell layer, suggesting that zinc released from mossy fibers is immediately retaken up by mossy fibers. When mossy fiber terminals were preferentially double-stained with zinc and calcium indicators and tetanic stimuli (100 Hz, 1 sec) were delivered to the dentate granule cell layer, the increase in calcium orange signal during the stimulation was enhanced in mossy fiber terminals by addition of CaEDTA, a membrane-impermeable zinc chelator, and was suppressed by addition of zinc. The decrease in FM4-64 signal (vesicular exocytosis) during tetanic stimulation (10 Hz, 180 sec), which induced mossy fiber long-term potentiation, was also enhanced in mossy fiber terminals by addition of CaEDTA and was suppressed by addition of zinc. The present study demonstrates that zinc released from mossy fibers may be a negative-feedback factor against presynaptic activity during tetanic stimulation.

Fiber-Optic Magnetic-Field-Strength Measurement System for Lightning Detection

Science.gov (United States)

Gurecki, Jay; Scully, Robert; Davis, Allen; Kirkendall, Clay; Bucholtz, Frank

2011-01-01

A fiber-optic sensor system is designed to measure magnetic fields associated with a lightning stroke. Field vector magnitudes are detected and processed for multiple locations. Since physical limitations prevent the sensor elements from being located in close proximity to highly conductive materials such as aluminum, the copper wire sensor elements (3) are located inside a 4-cubic-in. (.66-cubic-cm) plastic housing sensor head and connected to a fiber-optic conversion module by shielded cabling, which is limited to the shortest length feasible. The signal path between the conversion module and the avionics unit which processes the signals are fiber optic, providing enhanced immunity from electromagnetic radiation incident in the vicinity of the measurements. The sensors are passive, lightweight, and much smaller than commercial B-dot sensors in the configuration which measures a three-dimensional magnetic field. The system is expandable, and provides a standard-format output signal for downstream processing. Inside of the sensor head, three small search coils, each having a few turns on a circular form, are mounted orthogonally inside the non-metallic housing. The fiber-optic conversion module comprises three interferometers, one for each search coil. Each interferometer has a high bandwidth optical phase modulator that impresses the signal received from its search coil onto its output. The output of each interferometer travels by fiber optic cable to the avionics unit, and the search coil signal is recovered by an optical phase demodulator. The output of each demodulator is fed to an analog-to-digital converter, whose sampling rate is determined by the maximum expected rate of rise and peak signal magnitude. The output of the digital processor is a faithful reproduction of the coil response to the incident magnetic field. This information is provided in a standard output format on a 50-ohm port that can be connected to any number of data collection and processing

DFB fiber laser as source for optical communication systems

DEFF Research Database (Denmark)

Varming, Poul; Hübner, Jörg; Kristensen, Martin

1997-01-01

The results demonstrate that DFB fiber lasers are an attractive alternative as sources in telecommunication systems. The lasers show excellent long-term stability with very high signal to noise ratio and a reasonable output power, combined with exceptional temperature stability and inherent fiber...

1-kilowatt CW all-fiber laser oscillator pumped with wavelength-beam-combined diode stacks.

Science.gov (United States)

Xiao, Y; Brunet, F; Kanskar, M; Faucher, M; Wetter, A; Holehouse, N

2012-01-30

We have demonstrated a monolithic cladding-pumped ytterbium-doped single all-fiber laser oscillator generating 1 kW of CW signal power at 1080 nm with 71% slope efficiency and near diffraction-limited beam quality. Fiber components were highly integrated on "spliceless" passive fibers to promote laser efficiency and alleviate non-linear effects. The laser was pumped through a 7:1 pump combiner with seven 200-W 91x nm fiber-pigtailed wavelength-beam-combined diode-stack modules. The signal power of such a single all-fiber laser oscillator showed no evidence of roll-over, and the highest output was limited only by available pump power.

Fiber inline Michelson interferometer fabricated by a femtosecond laser.

Science.gov (United States)

Yuan, Lei; Wei, Tao; Han, Qun; Wang, Hanzheng; Huang, Jie; Jiang, Lan; Xiao, Hai

2012-11-01

A fiber inline Michelson interferometer was fabricated by micromachining a step structure at the tip of a single-mode optical fiber using a femtosecond laser. The step structure splits the fiber core into two reflection paths and produces an interference signal. A fringe visibility of 18 dB was achieved. Temperature sensing up to 1000°C was demonstrated using the fabricated assembly-free device.

Analysis of the reflection of a micro drop fiber sensor

Science.gov (United States)

Sun, Weimin; Liu, Qiang; Zhao, Lei; Li, Yingjuan; Yuan, Libo

2005-01-01

Micro drop fiber sensors are effective tools for measuring characters of liquids. These types of sensors are wildly used in biotechnology, beverage and food markets. For a fiber micro drop sensor, the signal of the output light is wavy with two peaks, normally. Carefully analyzing the wavy process can identify the liquid components. Understanding the reason of forming this wavy signal is important to design a suitable sensing head and to choose a suitable signal-processing method. The dripping process of a type of liquids is relative to the characters of the liquid and the shape of the sensing head. The quasi-Gauss model of the light field from the input-fiber end is used to analyse the distribution of the light field in the liquid drop. In addition, considering the characters of the liquid to be measured, the dripping process of the optical signal from the output-fiber end can be expected. The reflection surface of the micro drop varies as serials of spheres with different radiuses and global centers. The intensity of the reflection light changes with the shape of the surface. The varying process of the intensity relates to the tense, refractive index, transmission et al. To support the analyse above, an experimental system is established. In the system, LED is chosen as the light source and the PIN transform the light signal to the electrical signal, which is collected by a data acquisition card. An on-line testing system is made to check the theory discussed above.

Fiber Optical Parametric Chirped Pulse Amplification of Sub-Picosecond Pulses

DEFF Research Database (Denmark)

Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Da Ros, Francesco

2013-01-01

We demonstrate experimentally, for the first time to our knowledge, fiber optical parametric chirped pulse amplification of 400-fs pulses. The 400-fs signal is stretched, amplified by 26 dB and compressed back to 500 fs.......We demonstrate experimentally, for the first time to our knowledge, fiber optical parametric chirped pulse amplification of 400-fs pulses. The 400-fs signal is stretched, amplified by 26 dB and compressed back to 500 fs....

Recovering Signals from Optical Fiber Interferometric Sensors

Science.gov (United States)

1991-06-01

electronic functions to be combined onto a single -integrated circuit on- a silicon (or other) substrate. These custom -designed circuits are known by...largely unknown to the ordinary :itizen and seldom mentioned in the- popular press. Yet optical fiber sensors have attracted considerable- interest...write the-power in output leg I by performing the same interchange on Equation (95). a3(L) 12 {2B 2B1 -cos(3KL)I + B3B;[5+4cos(3KL)] 2 18 - B2B ;e(4-"?1 +e

A high spatial resolution distributed optical fiber grating sensing system based on OFDR

Science.gov (United States)

Dong, Ke; Xiong, Yuchuan; Wen, Hongqiao; Tong, Xinlin; Zhang, Cui; Deng, Chengwei

2017-10-01

A distributed optical fiber grating sensing system with large capacity and high spatial resolution is presented. Since highdensity identical weak grating array was utilized as sensing fiber, the multiplexing number was greatly increased, meanwhile, optical frequency domain reflectometry (OFDR) technology was used to implement high resolution distributed sensing system. In order to eliminate the nonlinear effect of tunable light source, a windowed FFT algorithm based on cubic spline interpolation was applied. The feasibility of the algorithm was experimentally testified, ultimately, the spatial resolution of system can reach mm-level. The influence of the crosstalk signal in the grating array on the OFDR system was analyzed. A method that a long enough delay fiber was added before the first FBG to remove crosstalk signal was proposed. The experiment was verified using an optical fiber with 113 uniform Bragg gratings at an interval of 10cm whose reflectivity are less than 1%. It demonstrates that crosstalk signal and measurement signal can be completely separated in the distance domain after adding a long enough delay fiber. Finally, the temperature experiment of distributed grating sensing system was carried out. The results display that each raster's center wavelength in the fiber link is independent of each other and the center wavelength drift has a good linear relationship with the temperature. The sensitivity of linear fitting is equal to 11.1pm/°C.

Micromycetes on climbing roses leaves (Rosa L. in the Botanic Garden of the Jagiellonian University in Cracow

Directory of Open Access Journals (Sweden)

Maria Kowalik

2015-08-01

Full Text Available Micromycetes inhabiting the leaves of 20 cultivars of climbing roses (Rosa L., grown in Botanic Garden of the Jagiellonian University in Cracow was investigated in the three successive years of research. Sixty-five taxa of of micromycetes was recorded with a few species dominating: Alternaria alternata, Epicoccum nigrum, Pestalotia rosae, Penicillium brevicompactum and Sordaria fimicola, accompanied by various other microfungi. A high abundance of rose black spot caused by Diplocarpon rosae was also observed. The affected leaves revealed advancing necrosis, substantially enhancing at the end of the growing season. Defoliation took place from June to October. Micromycetes inhabiting the leaves of climbing roses in Botanic Garden of the Jagiellonian University in Cracow considerably deteriorated the decorative aspect of the plants.

Transport Schemes for Fiber-Wireless Technology: Transmission Performance and Energy Efficiency

Directory of Open Access Journals (Sweden)

Christina Lim

2014-04-01

Full Text Available Fiber-wireless technology has been actively researched as a potential candidate for next generation broadband wireless signal distribution. Despite the popularity, this hybrid scheme has many technical challenges that impede the uptake and commercial deployment. One of the inherent issues is the transport of the wireless signals over a predominantly digital optical network in today’s telecommunication infrastructure. Many different approaches have been introduced and demonstrated with digitized RF transport of the wireless signals being the most compatible with the existing optical fiber networks. In this paper, we review our work in the area of digitized RF transport to address the inherent issues related to analog transport in the fiber-wireless links and compare the transmission performance and energy efficiency with the other transport strategies.

Development of an optical fiber flow velocity sensor.

Science.gov (United States)

Harada, Toshio; Kamoto, Kenji; Abe, Kyutaro; Izumo, Masaki

2009-01-01

A new optical fiber flow velocity sensor was developed by using an optical fiber information network system in sewer drainage pipes. The optical fiber flow velocity sensor operates without electric power, and the signals from the sensor can be transmitted over a long distance through the telecommunication system in the optical fiber network. Field tests were conducted to check the performance of the sensor in conduits in the pumping station and sewage pond managed by the Tokyo Metropolitan Government. Test results confirmed that the velocity sensor can be used for more than six months without any trouble even in sewer drainage pipes.

Physiological properties of afferents to the rat cerebellum during normal development and after postnatal x irradiation

International Nuclear Information System (INIS)

Puro, D.G.

1975-01-01

The consequences of an altered cerebellar cortical development on afferent transmission and terminal organization were analyzed in adult rats which had received x irradiation to the cerebellum postnatally. Rats, anesthetized with 0.5 percent halothane, were studied in various ages from day 3 to adult. The ascending mossy and climbing fiber systems were activated by electrical stimulation of the limbs with needle electrodes. Stimulation of the motor cortex activated the descending climbing fiber pathways. Extracellular responses from cerebellar Purkinje cells were observed on an oscilloscope as poststimulus time histograms were constructed ''on-line''. Conclusions and assertions include: (1) Synaptogenesis between incoming afferent fibers and target neurons takes place early in cerebellar cortical development. (2) Mossy fiber transmission is mature before the bulk of cerebellar synaptogenesis occurs. (3) The ascending and descending components of the climbing fiber system mature, with respect to latency, in synchrony. (4) The terminal synaptic organization has little effect on the development of transmission characteristics in these afferent systems. (5) One possible mechanism by which an adult neural structure can have an abnormal synaptic organization is to maintain immature synaptic relationships due to the neonatal loss of interneurons

Dislocation Climb Sources Activated by 1 MeV Electron Irradiation of Copper-Nickel Alloys

DEFF Research Database (Denmark)

Barlow, P.; Leffers, Torben

1977-01-01

Climb sources emitting dislocation loops are observed in Cu-Ni alloys during irradiation with 1 MeV electrons in a high voltage electron microscope. High source densities are found in alloys containing 5, 10 and 20% Ni, but sources are also observed in alloys containing 1 and 2% Ni. The range of ...

Ripple distribution for nonlinear fiber-optic channels.

Science.gov (United States)

Sorokina, Mariia; Sygletos, Stylianos; Turitsyn, Sergei

2017-02-06

We demonstrate data rates above the threshold imposed by nonlinearity on conventional optical signals by applying novel probability distribution, which we call ripple distribution, adapted to the properties of the fiber channel. Our results offer a new direction for signal coding, modulation and practical nonlinear distortions compensation algorithms.

Mid-infrared fiber-coupled supercontinuum spectroscopic imaging using a tapered chalcogenide photonic crystal fiber

Science.gov (United States)

Rosenberg Petersen, Christian; Prtljaga, Nikola; Farries, Mark; Ward, Jon; Napier, Bruce; Lloyd, Gavin Rhys; Nallala, Jayakrupakar; Stone, Nick; Bang, Ole

2018-02-01

We present the first demonstration of mid-infrared spectroscopic imaging of human tissue using a fiber-coupled supercontinuum source spanning from 2-7.5 μm. The supercontinuum was generated in a tapered large mode area chalcogenide photonic crystal fiber in order to obtain broad bandwidth, high average power, and single-mode output for good imaging properties. Tissue imaging was demonstrated in transmission by raster scanning over a sub-mm region of paraffinized colon tissue on CaF2 substrate, and the signal was measured using a fiber-coupled grating spectrometer. This demonstration has shown that we can distinguish between epithelial and surrounding connective tissues within a paraffinized section of colon tissue by imaging at discrete wavelengths related to distinct chemical absorption features.

Acquirement and enhancement of remote speech signals

Science.gov (United States)

Lü, Tao; Guo, Jin; Zhang, He-yong; Yan, Chun-hui; Wang, Can-jin

2017-07-01

To address the challenges of non-cooperative and remote acoustic detection, an all-fiber laser Doppler vibrometer (LDV) is established. The all-fiber LDV system can offer the advantages of smaller size, lightweight design and robust structure, hence it is a better fit for remote speech detection. In order to improve the performance and the efficiency of LDV for long-range hearing, the speech enhancement technology based on optimally modified log-spectral amplitude (OM-LSA) algorithm is used. The experimental results show that the comprehensible speech signals within the range of 150 m can be obtained by the proposed LDV. The signal-to-noise ratio ( SNR) and mean opinion score ( MOS) of the LDV speech signal can be increased by 100% and 27%, respectively, by using the speech enhancement technology. This all-fiber LDV, which combines the speech enhancement technology, can meet the practical demand in engineering.

Fiber-Optic Communication Links Suitable for On-Board Use in Modern Aircraft

Science.gov (United States)

Nguyen, Hung; Ngo, Duc; Alam, Mohammad F.; Atiquzzaman, Mohammed; Sluse, James; Slaveski, Filip

2004-01-01

The role of the Advanced Air Transportation Technologies program undertaken at the NASA Glenn Research Centers has been focused mainly on the improvement of air transportation safety, with particular emphasis on air transportation communication systems in on-board aircraft. The conventional solutions for digital optical communications systems specifically designed for local/metro area networks are, unfortunately, not capable of transporting the microwave and millimeter RF signals used in avionics systems. Optical networks capable of transporting RF signals are substantially different from the standard digital optical communications systems. The objective of this paper is to identify a number of different communication link architectures for RF/fiber optic transmission using a single backbone fiber for carrying VHF and UHF RF signals in the aircraft. To support these architectures, two approaches derived from both hybrid RF-optical and all-optical processing methodologies are discussed with single and multiple antennas for explicitly transporting VHF and UHF signals, while the relative merits and demerits of each architecture are also addressed. Furthermore, the experimental results of wavelength division multiplexing (WDM) link architecture from our test-bed platform, configured for aircraft environment to support simultaneous transmission of multiple RF signals over a single optical fiber, exhibit no appreciable signal degradation at wavelengths of both 1330 and 1550 nm, respectively. Our measurements of signal to noise ratio carried out for the transmission of FM and AM analog modulated signals at these wavelengths indicate that WDM is a fiber optic technology which is potentially suitable for avionics applications.

Improved slow-light performance of 10 Gb/s NRZ, PSBT and DPSK signals in fiber broadband SBS.

Science.gov (United States)

Yi, Lilin; Jaouen, Yves; Hu, Weisheng; Su, Yikai; Bigo, Sébastien

2007-12-10

We have demonstrated error-free operations of slow-light via stimulated Brillouin scattering (SBS) in optical fiber for 10-Gb/s signals with different modulation formats, including non-return-to-zero (NRZ), phase-shaped binary transmission (PSBT) and differential phase-shiftkeying (DPSK). The SBS gain bandwidth is broadened by using current noise modulation of the pump laser diode. The gain shape is simply controlled by the noise density function. Super-Gaussian noise modulation of the Brillouin pump allows a flat-top and sharp-edge SBS gain spectrum, which can reduce slow-light induced distortion in case of 10-Gb/s NRZ signal. The corresponding maximal delay-time with error-free operation is 35 ps. Then we propose the PSBT format to minimize distortions resulting from SBS filtering effect and dispersion accompanied with slow light because of its high spectral efficiency and strong dispersion tolerance. The sensitivity of the 10-Gb/s PSBT signal is 5.2 dB better than the NRZ case with a same 35-ps delay. The maximal delay of 51 ps with error-free operation has been achieved. Futhermore, the DPSK format is directly demodulated through a Gaussian-shaped SBS gain, which is achieved using Gaussian-noise modulation of the Brillouin pump. The maximal error-free time delay after demodulation of a 10-Gb/s DPSK signal is as high as 81.5 ps, which is the best demonstrated result for 10-Gb/s slow-light.

SU-E-T-610: Phosphor-Based Fiber Optic Probes for Proton Beam Characterization

Energy Technology Data Exchange (ETDEWEB)

Darafsheh, A; Soldner, A; Liu, H; Kassaee, A; Zhu, T; Finlay, J [Univ Pennsylvania, Philadelphia, PA (United States)

2015-06-15

Purpose: To investigate feasibility of using fiber optics probes with rare-earth-based phosphor tips for proton beam radiation dosimetry. We designed and fabricated a fiber probe with submillimeter resolution (<0.5 mm3) based on TbF3 phosphors and evaluated its performance for measurement of proton beam including profiles and range. Methods: The fiber optic probe with TbF3 phosphor tip, embedded in tissue-mimicking phantoms was irradiated with double scattering proton beam with energy of 180 MeV. Luminescence spectroscopy was performed by a CCD-coupled spectrograph to analyze the emission spectra of the fiber tip. In order to measure the spatial beam profile and percentage depth dose, we used singular value decomposition method to spectrally separate the phosphors ionoluminescence signal from the background Cerenkov radiation signal. Results: The spectra of the TbF3 fiber probe showed characteristic ionoluminescence emission peaks at 489, 542, 586, and 620 nm. By using singular value decomposition we found the contribution of the ionoluminescence signal to measure the percentage depth dose in phantoms and compared that with measurements performed with ion chamber. We observed quenching effect at the spread out Bragg peak region, manifested as under-responding of the signal, due to the high LET of the beam. However, the beam profiles were not dramatically affected by the quenching effect. Conclusion: We have evaluated the performance of a fiber optic probe with submillimeter resolution for proton beam dosimetry. We demonstrated feasibility of spectral separation of the Cerenkov radiation from the collected signal. Such fiber probes can be used for measurements of proton beams profile and range. The experimental apparatus and spectroscopy method developed in this work provide a robust platform for characterization of proton-irradiated nanophosphor particles for ultralow fluence photodynamic therapy or molecular imaging applications.

Use of neutron-capture plastic fibers for nondestructive assay

International Nuclear Information System (INIS)

Heger, A.S.; Grazioso, R.F.; Mayo, D.R.; Ensslin, N.; Miller, M.C.; Huang, H.Y.; Russo, P.A.

1998-01-01

Neutron-capture plastic fibers can be used as a nondestructive assay tool. The detectors consist of an active region assembled from ribbons of boron-( 10 B) loaded optical fibers. The mixture of the moderator and thermal neutron absorber in the fiber yields a detector with high efficiency (var-epsilon) and a short die-away time (τ). The deposited energy of the resultant charged particles is converted to light that is collected by photomultiplier tubes mounted at both ends of the fiber. Thermal neutron coincidence counters (TNCC) made of these fibers can serve to verify fissile materials generated from the nuclear fuel cycle. This type of detector may extend the range of materials now accessible to assay by 3 He detectors. Experiments with single fibers of diameters 0.25, 0.50, and 1.00 mm test their ability to distinguish between the signals generated from neutron interactions and those from gamma rays. These results are compared with those obtained from simulation analyses for the same purpose. Light output and attenuation, neutron detection efficiency, and the signal-to-noise ratios of these fibers have also been investigated. The experimental results for light attenuation and neutron detection efficiency are consistent with the values obtained from simulation studies. A comparison of the performance of various configurations of the plastic scintillating fibers with that of other neutron-capture devices such as 3 He detectors is also discussed

Low Loss and Highly Birefringent Hollow-Core Photonic Crystal Fiber

DEFF Research Database (Denmark)

Roberts, P. John; Williams, D.P.; Mangan, Brian J.

2006-01-01

A hollow-core photonic crystal fiber design is proposed which enables both low-loss and polarization-maintained signal propagation. The design relies on an arrangement of antiresonant features positioned on the glass ring that surrounds the air core.......A hollow-core photonic crystal fiber design is proposed which enables both low-loss and polarization-maintained signal propagation. The design relies on an arrangement of antiresonant features positioned on the glass ring that surrounds the air core....

Damage detection in laminar thermoplastic composite materials by means of embedded optical fibers

Directory of Open Access Journals (Sweden)

Kojović Aleksandar M.

2006-01-01

Full Text Available This paper investigates the possibility of applying optical fibers as sensors for investigating low energy impact damage in laminar thermoplastic composite materials, in real time. Impact toughness testing by a Charpy impact pendulum with different loads was conducted in order to determine the method for comparative measurement of the resulting damage in the material. For that purpose intensity-based optical fibers were built in to specimens of composite materials with Kevlar 129 (the DuPont registered trade-mark for poly(p-phenylene terephthalamide woven fabric as reinforcement and thermoplastic PVB (poly(vinyl butyral as the matrix. In some specimens part of the layers of Kevlar was replaced with metal mesh (50% or 33% of the layers. Experimental testing was conducted in order to observe and analyze the response of the material under multiple low-energy impacts. Light from the light-emitting diode (LED was launched to the embedded optical fiber and was propagated to the phototransistor-based photo detector. During each impact, the signal level, which is proportional to the light intensity in the optical fiber, drops and then slowly recovers. The obtained signals were analyzed to determine the appropriate method for real time damage monitoring. The major part of the damage occurs during impact. The damage reflects as a local, temporary release of strain in the optical fiber and an increase of the signal level. The obtained results show that intensity-based optical fibers could be used for measuring the damage in laminar thermoplastic composite materials. The acquired optical fiber signals depend on the type of material, but the same set of rules (relatively different, depending on the type of material could be specified. Using real time measurement of the signal during impact and appropriate analysis enables quantitative evaluation of the impact damage in the material. Existing methods in most cases use just the intensity of the signal before

Impact of Carbohydrate-Electrolyte Beverage Ingestion on Heart Rate Response While Climbing Mountain Fuji at ~3000 m

Directory of Open Access Journals (Sweden)

Masahiro Horiuchi

2017-01-01

Full Text Available We sought to investigate whether carbohydrate-electrolyte beverage ingestion reduced heart rate (HR in twenty-three healthy young adults while climbing Mount Fuji at a given exercise intensity. Twenty-three healthy adults were randomly divided into two groups: the tap water (11 males [M] and 1 female [F] and the carbohydrate-electrolyte group (10 M and 1 F. HR and activity energy expenditure (AEE were recorded every min. The HRs for the first 30 minutes of climbing were not significantly different between the groups [121 ± 2 beats per min (bpm in the tap water and 116 ± 3 bpm in the carbohydrate-electrolyte]; however, HR significantly increased with climbing in the tap water group (129 ± 2 bpm but showed no significant increase in the carbohydrate-electrolyte group (121 ± 3 bpm. In addition, body weight changes throughout two days ascending and descending on Mount Fuji were inversely related to changes in resting HR. Further, individual variation of body weight changes was suppressed by carbohydrate-electrolyte drink. Collectively, carbohydrate-electrolyte beverage intake may attenuate an increase in HR at a given AEE while mountaineering at ~3000 m compared with tap water intake.

Monitoring of temperature fatigue failure mechanism for polyvinyl alcohol fiber concrete using acoustic emission sensors.

Science.gov (United States)

Li, Dongsheng; Cao, Hai

2012-01-01

The applicability of acoustic emission (AE) techniques to monitor the mechanism of evolution of polyvinyl alcohol (PVA) fiber concrete damage under temperature fatigue loading is investigated. Using the temperature fatigue test, real-time AE monitoring data of PVA fiber concrete is achieved. Based on the AE signal characteristics of the whole test process and comparison of AE signals of PVA fiber concretes with different fiber contents, the damage evolution process of PVA fiber concrete is analyzed. Finally, a qualitative evaluation of the damage degree is obtained using the kurtosis index and b-value of AE characteristic parameters. The results obtained using both methods are discussed.

Scalable Optical-Fiber Communication Networks

Science.gov (United States)

Chow, Edward T.; Peterson, John C.

1993-01-01

Scalable arbitrary fiber extension network (SAFEnet) is conceptual fiber-optic communication network passing digital signals among variety of computers and input/output devices at rates from 200 Mb/s to more than 100 Gb/s. Intended for use with very-high-speed computers and other data-processing and communication systems in which message-passing delays must be kept short. Inherent flexibility makes it possible to match performance of network to computers by optimizing configuration of interconnections. In addition, interconnections made redundant to provide tolerance to faults.

Remote (250 km Fiber Bragg Grating Multiplexing System

Directory of Open Access Journals (Sweden)

Manuel Lopez-Amo

2011-09-01

Full Text Available We propose and demonstrate two ultra-long range fiber Bragg grating (FBG sensor interrogation systems. In the first approach four FBGs are located 200 km from the monitoring station and a signal to noise ratio of 20 dB is obtained. The second improved version is able to detect the four multiplexed FBGs placed 250 km away, offering a signal to noise ratio of 6–8 dB. Consequently, this last system represents the longest range FBG sensor system reported so far that includes fiber sensor multiplexing capability. Both simple systems are based on a wavelength swept laser to scan the reflection spectra of the FBGs, and they are composed by two identical-lengths optical paths: the first one intended to launch the amplified laser signal by means of Raman amplification and the other one is employed to guide the reflection signal to the reception system.

On factoring RSA modulus using random-restart hill-climbing algorithm and Pollard’s rho algorithm

Science.gov (United States)

Budiman, M. A.; Rachmawati, D.

2017-12-01

The security of the widely-used RSA public key cryptography algorithm depends on the difficulty of factoring a big integer into two large prime numbers. For many years, the integer factorization problem has been intensively and extensively studied in the field of number theory. As a result, a lot of deterministic algorithms such as Euler’s algorithm, Kraitchik’s, and variants of Pollard’s algorithms have been researched comprehensively. Our study takes a rather uncommon approach: rather than making use of intensive number theories, we attempt to factorize RSA modulus n by using random-restart hill-climbing algorithm, which belongs the class of metaheuristic algorithms. The factorization time of RSA moduli with different lengths is recorded and compared with the factorization time of Pollard’s rho algorithm, which is a deterministic algorithm. Our experimental results indicates that while random-restart hill-climbing algorithm is an acceptable candidate to factorize smaller RSA moduli, the factorization speed is much slower than that of Pollard’s rho algorithm.

Fiber Optic Sensors for Health Monitoring of Morphing Airframes. Part 2; Chemical Sensing Using Optical Fibers with Bragg Gratings

Science.gov (United States)

Wood, Karen; Brown, Timothy; Rogowski, Robert; Jensen, Brian

2000-01-01

Part 1 of this two part series described the fabrication and calibration of Bragg gratings written into a single mode optical fiber for use in strain and temperature monitoring. Part 2 of the series describes the use of identical fibers and additional multimode fibers, both with and without Bragg gratings, to perform near infrared spectroscopy. The demodulation system being developed at NASA Langley Research Center currently requires the use of a single mode optical fiber. Attempts to use this single mode fiber for spectroscopic analysis are problematic given its small core diameter, resulting in low signal intensity. Nonetheless, we have conducted a preliminary investigation using a single mode fiber in conjunction with an infrared spectrometer to obtain spectra of a high-performance epoxy resin system. Spectra were obtained using single mode fibers that contained Bragg gratings; however, the peaks of interest were barely discernible above the noise. The goal of this research is to provide a multipurpose sensor in a single optical fiber capable of measuring a variety of chemical and physical properties.

Distributed optical fiber vibration sensing using phase-generated carrier demodulation algorithm

Science.gov (United States)

Yu, Zhihua; Zhang, Qi; Zhang, Mingyu; Dai, Haolong; Zhang, Jingjing; Liu, Li; Zhang, Lijun; Jin, Xing; Wang, Gaifang; Qi, Guang

2018-05-01

A novel optical fiber-distributed vibration-sensing system is proposed, which is based on self-interference of Rayleigh backscattering with phase-generated carrier (PGC) demodulation algorithm. Pulsed lights are sent into the sensing fiber and the Rayleigh backscattering light from a certain position along the sensing fiber would interfere through an unbalanced Michelson interferometry to generate the interference light. An improved PGC demodulation algorithm is carried out to recover the phase information of the interference signal, which carries the sensing information. Three vibration events were applied simultaneously to different positions over 2000 m sensing fiber and demodulated correctly. The spatial resolution is 10 m, and the noise level of the Φ-OTDR system we proposed is about 10-3 rad/\\surd {Hz}, and the signal-to-noise ratio is about 30.34 dB.

The usage of optical fibers for damage detection in ballistic protection composite laminates

Directory of Open Access Journals (Sweden)

Živković Irena D.

2006-01-01

Full Text Available This paper describes the procedure of embedding fiber optic sensors in laminar thermoplastic composite material, as well as damage investigation after ballistic loading. Thermoplastic-reinforced composite materials were made for increased material damage resistance during ballistic loading. Damage inside the composite material was detected by observing the intensity drop of the light signal transmitted through the optical fibers. Experimental testing was carried out in order to observe and analyze the response of the material under various load conditions. Different types of Kevlar reinforced composite materials (thermoplastic, thermo reactive and thermoplastic with ceramic plate as the impact face were made. Material damage resistance during ballistic loading was investigated and compared. Specimens were tested under multiple load conditions. The opto-electronic part of the measurement system consists of two light-emitting diodes as light sources for the optical fibers, and two photo detectors for the light intensity measurement. The output signal was acquired from photo detectors by means of a data acquisition board and personal computer. The measurements showed an intensity drop of the transmitted light signal as a result of the applied loading on composite structure for all the optical fibers. All the diagrams show similar behavior of the light signal intensity. In fact, all of them may be divided into three zones: the zone of penetration of the first composite layer, the bullet traveling zone through the composite material till its final stop, and the material relaxation zone. The attenuation of the light signal intensity during impact is caused by the influence of the applied dynamic stress on the embedded optical fibers. The applied stress caused micro bending of the optical fiber, changes in the shape of the cross-section and the unequal changes of the indices of refraction of the core and cladding due to the stress-optic effect. The

Optical fiber communications

CERN Document Server

Keiser, Gerd

2008-01-01

The fourth edition of this popular text and reference book presents the fundamental principles for understanding and applying optical fiber technology to sophisticated modern telecommunication systems. Optical-fiber-based telecommunication networks have become a major information-transmission-system, with high capacity links encircling the globe in both terrestrial and undersea installations. Numerous passive and active optical devices within these links perform complex transmission and networking functions in the optical domain, such as signal amplification, restoration, routing, and switching. Along with the need to understand the functions of these devices comes the necessity to measure both component and network performance, and to model and stimulate the complex behavior of reliable high-capacity networks.

Online Structural-Health Monitoring of Glass Fiber-Reinforced Thermoplastics Using Different Carbon Allotropes in the Interphase

Directory of Open Access Journals (Sweden)

Michael Thomas Müller

2018-06-01

Full Text Available An electromechanical response behavior is realized by nanostructuring the glass fiber interphase with different highly electrically conductive carbon allotropes like carbon nanotubes (CNT, graphene nanoplatelets (GNP, or conductive carbon black (CB. The operational capability of these multifunctional glass fibers for an online structural-health monitoring is demonstrated in endless glass fiber-reinforced polypropylene. The electromechanical response behavior, during a static or dynamic three-point bending test of various carbon modifications, shows qualitative differences in the signal quality and sensitivity due to the different aspect ratios of the nanoparticles and the associated electrically conductive network densities in the interphase. Depending on the embedding position within the glass fiber-reinforced composite compression, shear and tension loadings of the fibers can be distinguished by different characteristics of the corresponding electrical signal. The occurrence of irreversible signal changes during the dynamic loading can be attributed to filler reorientation processes caused by polymer creeping or by destruction of electrically conductive paths by cracks in the glass fiber interphase.

Exploit the Bandwidth Capacities of the Perfluorinated Graded Index Polymer Optical Fiber for Multi-Services Distribution

Directory of Open Access Journals (Sweden)

Paul Alain Rolland

2011-06-01

Full Text Available The study reported here deals with the exploitation of perfluorinated graded index polymer optical fiber bandwidth to add further services in a home/office network. The fiber properties are exhibited in order to check if perfluorinated graded index plastic optical fiber (PFGI-POF is suitable to support a multiplexing transmission. According to the high bandwidth length of plastic fibers, both at 850 nm and 1,300 nm, the extension of the classical baseband existing network is proposed to achieve a dual concept, allowing the indoor coverage of wireless signals transmitted using the Radio over Fiber technology. The simultaneous transmission of a 10 GbE signal and a wireless signal is done respectively at 850 nm and 1,300 nm on a single plastic fiber using wavelength division multiplexing commercially available devices. The penalties have been evaluated both in digital (Bit Error Rate measurement and radiofrequency (Error Vector Magnitude measurement domains.

Stars and Stripes in the Cerebellar Cortex: A Voltage Sensitive Dye Study

Science.gov (United States)

Rokni, Dan; Llinas, Rodolfo; Yarom, Yosef

2007-01-01

The lattice-like structure of the cerebellar cortex and its anatomical organization in two perpendicular axes provided the foundations for many theories of cerebellar function. However, the functional organization does not always match the anatomical organization. Thus direct measurement of the functional organization is central to our understanding of cerebellar processing. Here we use voltage sensitive dye imaging in the isolated cerebellar preparation to characterize the spatio-temporal organization of the climbing and mossy fiber (MF) inputs to the cerebellar cortex. Spatial and temporal parameters were used to develop reliable criteria to distinguish climbing fiber (CF) responses from MF responses. CF activation excited postsynaptic neurons along a parasagittal cortical band. These responses were composed of slow (∼25 ms), monophasic depolarizing signals. Neither the duration nor the spatial distribution of CF responses were affected by inhibition. Activation of MF generated responses that were organized in radial patches, and were composed of a fast (∼5 ms) depolarizing phase followed by a prolonged (∼100 ms) negative wave. Application of a GABAA blocker eliminated the hyperpolarizing phase and prolonged the depolarizing phase, but did not affect the spatial distribution of the response, thus suggesting that it is not the inhibitory system that is responsible for the inability of the MF input to generate beams of activity that propagate along the parallel fiber system. PMID:18958242

Stars and stripes in the cerebellar cortex: a voltage sensitive dye study

Directory of Open Access Journals (Sweden)

Dan Rokni

2007-08-01

Full Text Available The lattice-like structure of the cerebellar cortex and its anatomical organization in two perpendicular axes provided the foundations for many theories of cerebellar function. However, the functional organization does not always match the anatomical organization. Thus direct measurement of the functional organization is central to our understanding of cerebellar processing. Here we use voltage sensitive dye imaging in the isolated cerebellar preparation to characterize the spatio-temporal organization of the climbing and mossy fiber (MF inputs to the cerebellar cortex. Spatial and temporal parameters were used to develop reliable criteria to distinguish climbing fiber (CF responses from MF responses. CF activation excited postsynaptic neurons along a parasagittal cortical band. These responses were composed of slow (~25 ms, monophasic depolarizing signals. Neither the duration nor the spatial distribution of CF responses were affected by inhibition. Activation of MF generated responses that were organized in radial patches, and were composed of a fast (~5 ms depolarizing phase followed by a prolonged (~100 ms negative wave. Application of a GABAA blocker eliminated the hyperpolarizing phase and prolonged the depolarizing phase, but did not affect the spatial distribution of the response, thus suggesting that it is not the inhibitory system that is responsible for the inability of the MF input to generate beams of activity that propagate along the parallel fiber system.

Cortical activities evoked by the signals ascending through unmyelinated C fibers in humans. A fMRI study

International Nuclear Information System (INIS)

Kakigi, Ryusuke; Qiu, Yunhai; Noguchi, Yasuki

2006-01-01

Acute pain is classified as first and second pain associated with rapidly conducting Aδ fibers and slowly conducting unmyelinated C fibers, respectively. First pain aims at achieving relative safety from the source of injury, whereas second pain, with its strong affective component, attracts longer-lasting attention and initiates behavioral responses in order to limit further injury and optimize recovery. Accordingly, the distinct brain representations for first and second pain should reflect distinct biological functions of both sensations. In this study, therefore, an event-related functional magnetic resonance imaging (fMRI) was used to investigate brain processing of the signals ascending from peripheral C and Aδ fibers evoked by phasic laser stimuli on the right hand in humans. The stimulation of both C and Aδ nociceptors activated the bilateral thalamus, bilateral secondary somatosensory cortex (SII), right (ipsilateral) middle insula, and bilateral Brodmann's area (BA) 24/32, with the majority of activity found in the posterior portion of the anterior cingulate cortex (pACC). However, magnitude of activity in the right (ipsilateral) BA32/8/6, including dorsal parts in the anterior portion of the ACC (aACC) and pre-supplementary motor area (pre-SMA), and the bilateral anterior insula was significantly stronger following the stimulation of C nociceptors than Aδ nociceptors. It was concluded that the activation of C nociceptors, related to second pain, evokes different brain processing from that of Aδ nociceptors, related to first pain, probably due to the differences in the emotional and motivational aspects of either pain, which are mainly related to the aACC, pre-SMA and anterior insula. (author)

Applications of Telecommunication Transceiver Architectures in All-Fiber Coherent Detection Lidars

DEFF Research Database (Denmark)

Abari, Cyrus F.

. As a result, the new fiber-optic technology was quickly adopted in these lidars. Although coherent detection lidars, especially all-fiber coherent detection lidars, have benefited from the technology available in coherent fiber-optic communications, a considerable gap (in both research and technology) seems...... enable the possibility for performance improvements in existing lidars but also pave the way for the application of coherent detection lidars in areas where their presence was neither plausible nor easy to realize. This thesis, composed of an introduction and four scientific paper and one manuscript...... approaches to signal processing, necessary for the estimation of mean velocity from the spectra, are discussed and the associated advantages and disadvantages such as the signal to noise ratio and signal processing overhead are discussed. The performance of the system proposed paper I is put to test...

Phase-matched light amplification by three-wave mixing process in a birefringent fiber due to externally applied stress

International Nuclear Information System (INIS)

Ohashi, M.; Kitayama, K.; Ishida, Y.; Uchida, N.

1982-01-01

A novel method to achieve phase-matched light amplification in a birefringent fiber via the three-wave mixing is proposed by using frequency shift change due to the stress applied to the fiber. It is confirmed that the signal power from a cw laser diode at lambda = 1.292 μm is amplified by 6.1 x 10 3 times in the birefringent fiber pumped with a Q-switched Nd: yttrium aluminum garnet laser at lambda = 1.064 μm. This will provide a new fiber-optic light signal amplifier having a good tolerance for variation of signal wavelengths

A life to risk: cultural differences in motivations to climb among elite male mountaineers

Science.gov (United States)

Patrick T. Maher; Tom G. Potter

2001-01-01

This study explored the cultural differences and motivations to climb of elite, male mountaineers. The purpose of the study was to first determine the motivations of elite male mountaineers and then link these motivations to the culture in which the mountaineer lives or grew up in. Five co-researchers participated in the study: two Canadians, two Americans, and one...

Raman probes based on optically-poled double-clad fiber and coupler

DEFF Research Database (Denmark)

Brunetti, Anna Chiara; Margulis, Walter; Rottwitt, Karsten

2012-01-01

of a sample of dimethyl sulfoxide (DMSO), when illuminating the waveguide with 1064nm laser light. The Raman signal is collected in the inner cladding, from which it is retrieved with either a bulk dichroic mirror or a double-clad fiber coupler. The coupler allows for a substantial reduction of the fiber......Two fiber Raman probes are presented, one based on an optically-poled double-clad fiber and the second based on an optically-poled double-clad fiber coupler respectively. Optical poling of the core of the fiber allows for the generation of enough 532nm light to perform Raman spectroscopy...

An automatic mode-locked system for passively mode-locked fiber laser

Science.gov (United States)

Li, Sha; Xu, Jun; Chen, Guoliang; Mei, Li; Yi, Bo

2013-12-01

This paper designs and implements one kind of automatic mode-locked system. It can adjust a passively mode-locked fiber laser to keep steady mode-locked states automatically. So the unsteadiness of traditional passively mode-locked fiber laser can be avoided. The system transforms optical signals into electrical pulse signals and sends them into MCU after processing. MCU calculates the frequency of the signals and judges the state of the output based on a quick judgment algorithm. A high-speed comparator is used to check the signals and the comparison voltage can be adjusted to improve the measuring accuracy. Then by controlling two polarization controllers at an angle of 45degrees to each other, MCU extrudes the optical fibers to change the polarization until it gets proper mode-locked output. So the system can continuously monitor the output signal and get it back to mode-locked states quickly and automatically. States of the system can be displayed on the LCD and PC. The parameters of the steady mode-locked states can be stored into an EEPROM so that the system will get into mode-locked states immediately next time. Actual experiments showed that, for a 6.238MHz passively mode-locked fiber lasers, the system can get into steady mode-locked states automatically in less than 90s after starting the system. The expected lock time can be reduced to less than 20s after follow up improvements.

Heart rate response to a climber’s fall in sport climbing

OpenAIRE

Chaloupsky, David

2015-01-01

The research deals with response of heart rate to a climber’s simulated fall in a leading position when indoor climbing. Heart rate of climbers was recorded during ascents of an overhanging route in the leading position, to the given point high above the ground, followed by falling into the last protection. The length of the free fall was defined by the place of the last belay anchor, which was at the height of climber’s ankles. The length of the fall was about two meters of free fall plus th...

EXPERIMENTAL COMPARISON OF HOMODYNE DEMODULATION ALGORITHMS FOR PHASE FIBER-OPTIC SENSOR

Directory of Open Access Journals (Sweden)

M. N. Belikin

2015-11-01

Full Text Available Subject of Research. The paper presents the results of experimental comparative analysis of homodyne demodulation algorithms based on differential cross multiplying method and on arctangent method under the same conditions. The dependencies of parameters for the output signals on the optical radiation intensity are studied for the considered demodulation algorithms. Method. The prototype of single fiber optic phase interferometric sensor has been used for experimental comparison of signal demodulation algorithms. Main Results. We have found that homodyne demodulation based on arctangent method provides greater (by 7 dB at average signal-to-noise ratio of output signals over the frequency band of acoustic impact from 100 Hz to 500 Hz as compared to differential cross multiplying algorithms. We have demonstrated that no change in the output signal amplitude occurs for the studied range of values of the optical pulses amplitudes. Obtained results indicate that the homodyne demodulation based on arctangent method is most suitable for application in the phase fiber-optic sensors. It provides higher repeatability of their characteristics than the differential cross multiplying algorithm. Practical Significance. Algorithms of interferometric signals demodulation are widely used in phase fiber-optic sensors. Improvement of their characteristics has a positive effect on the performance of such sensors.

Intelligent fiber optic sensor for solution concentration examination

Science.gov (United States)

Borecki, Michal; Kruszewski, Jerzy

2003-09-01

This paper presents the working principles of intelligent fiber-optic intensity sensor used for solution concentration examination. The sensor head is the ending of the large core polymer optical fiber. The head works on the reflection intensity basis. The reflected signal level depends on Fresnel reflection and reflection on suspended matter when the head is submersed in solution. The sensor head is mounted on a lift. For detection purposes the signal includes head submerging, submersion, emerging and emergence is measured. This way the viscosity turbidity and refraction coefficient has an effect on measured signal. The signal forthcoming from head is processed electrically in opto-electronic interface. Then it is feed to neural network. The novelty of presented sensor is implementation of neural network that works in generalization mode. The sensor resolution depends on opto-electronic signal conversion precision and neural network learning accuracy. Therefore, the number and quality of points used for learning process is very important. The example sensor application for examination of liquid soap concentration in water is presented in the paper.

Detection of Ultrasonic Stress Waves in Structures Using 3D Shaped Optic Fiber Based on a Mach-Zehnder Interferometer.

Science.gov (United States)

Lan, Chengming; Zhou, Wensong; Xie, Yawen

2018-04-16

This work proposes a 3D shaped optic fiber sensor for ultrasonic stress waves detection based on the principle of a Mach–Zehnder interferometer. This sensor can be used to receive acoustic emission signals in the passive damage detection methods and other types of ultrasonic signals propagating in the active damage detection methods, such as guided wave-based methods. The sensitivity of an ultrasonic fiber sensor based on the Mach–Zehnder interferometer mainly depends on the length of the sensing optical fiber; therefore, the proposed sensor achieves the maximum possible sensitivity by wrapping an optical fiber on a hollow cylinder with a base. The deformation of the optical fiber is produced by the displacement field of guided waves in the hollow cylinder. The sensor was first analyzed using the finite element method, which demonstrated its basic sensing capacity, and the simulation signals have the same characteristics in the frequency domain as the excitation signal. Subsequently, the primary investigations were conducted via a series of experiments. The sensor was used to detect guided wave signals excited by a piezoelectric wafer in an aluminum plate, and subsequently it was tested on a reinforced concrete beam, which produced acoustic emission signals via impact loading and crack extension when it was loaded to failure. The signals obtained from a piezoelectric acoustic emission sensor were used for comparison, and the results indicated that the proposed 3D fiber optic sensor can detect ultrasonic signals in the specific frequency response range.

Detection of Ultrasonic Stress Waves in Structures Using 3D Shaped Optic Fiber Based on a Mach–Zehnder Interferometer

Science.gov (United States)

Xie, Yawen

2018-01-01

This work proposes a 3D shaped optic fiber sensor for ultrasonic stress waves detection based on the principle of a Mach–Zehnder interferometer. This sensor can be used to receive acoustic emission signals in the passive damage detection methods and other types of ultrasonic signals propagating in the active damage detection methods, such as guided wave-based methods. The sensitivity of an ultrasonic fiber sensor based on the Mach–Zehnder interferometer mainly depends on the length of the sensing optical fiber; therefore, the proposed sensor achieves the maximum possible sensitivity by wrapping an optical fiber on a hollow cylinder with a base. The deformation of the optical fiber is produced by the displacement field of guided waves in the hollow cylinder. The sensor was first analyzed using the finite element method, which demonstrated its basic sensing capacity, and the simulation signals have the same characteristics in the frequency domain as the excitation signal. Subsequently, the primary investigations were conducted via a series of experiments. The sensor was used to detect guided wave signals excited by a piezoelectric wafer in an aluminum plate, and subsequently it was tested on a reinforced concrete beam, which produced acoustic emission signals via impact loading and crack extension when it was loaded to failure. The signals obtained from a piezoelectric acoustic emission sensor were used for comparison, and the results indicated that the proposed 3D fiber optic sensor can detect ultrasonic signals in the specific frequency response range. PMID:29659540

Fiber optics physics and technology

CERN Document Server

Mitschke, Fedor

2016-01-01

This book tells you all you want to know about optical fibers: Their structure, their light-guiding mechanism, their material and manufacture, their use. It began with telephone, then came telefax and email. Today we use search engines, music downloads and internet videos, all of which require shuffling of bits and bytes by the zillions. The key to all this is the conduit: the line which is designed to carry massive amounts of data at breakneck speed. In their data carrying capacity optical fiber lines beat all other technologies (copper cable, microwave beacons, satellite links) hands down, at least in the long haul; wireless devices rely on fibers, too. Several effects tend to degrade the signal as it travels down the fiber: they are spelled out in detail. Nonlinear processes are given due consideration for a twofold reason: On the one hand they are fundamentally different from the more familiar processes in electrical cable. On the other hand, they form the basis of particularly interesting and innovative ...

Composite cavity based fiber optic Fabry–Perot strain sensors demodulated by an unbalanced fiber optic Michelson interferometer with an electrical scanning mirror

International Nuclear Information System (INIS)

Zhang, Jianzhong; Yang, Jun; Sun, Weimin; Yuan, Libo; Jin, Wencai; Peng, G D

2008-01-01

A composite cavity based fiber optic Fabry–Perot strain sensor system, interrogated by a white light source and demodulated by an unbalanced fiber optic Michelson interferometer with an electrical scanning mirror, is proposed and demonstrated. Comparing with the traditional extrinsic fiber optic Fabry–Perot strain sensor, the potential multiplexing capability and the dynamic measurement range are improved simultaneously. At the same time, the measurement stability of the electrical scanning mirror system is improved by the self-referenced signal of the sensor structure

Optical Switching for Dynamic Distribution of Wireless-over-Fiber Signals

DEFF Research Database (Denmark)

Rodes Lopez, Guillermo Arturo; Vegas Olmos, Juan José; Karinou, Fotini

2012-01-01

In this paper, we report on an experimental validation of dynamic distribution of wireless-over-fiber by employing optical switching using semiconductor optical amplifiers; the rest of the network was designed according to the channel distribution over the optical spectra required by the optical...... switch. An experimental validation was also conducted. The experiment consists of a four wavelength division multiplexed (WDM) channel system operating on a WiMax frequency band, and employing an orthogonal frequency-division multiplexing (OFDM) modulation at 625 Mbit/s per channel, transmission...... of the data over 20 km of optical fiber, and active switching in a one-by-sixteen active optical switch. The results show a negligible power penalty on each channel, for both the best and the worst case in terms of inter-channel crosstalk....

Radio-over-fiber using an optical antenna based on Rydberg states of atoms

Science.gov (United States)

Deb, A. B.; Kjærgaard, N.

2018-05-01

We provide an experimental demonstration of a direct fiber-optic link for RF transmission ("radio-over-fiber") using a sensitive optical antenna based on a rubidium vapor cell. The scheme relies on measuring the transmission of laser light at an electromagnetically induced transparency resonance that involves highly excited Rydberg states. By dressing pairs of Rydberg states using microwave fields that act as local oscillators, we encoded RF signals in the optical frequency domain. The light carrying the information is linked via a virtually lossless optical fiber to a photodetector where the signal is retrieved. We demonstrate a signal bandwidth in excess of 1 MHz limited by the available coupling laser power and atomic optical density. Our sensitive, non-metallic and readily scalable optical antenna for microwaves allows extremely low-levels of optical power (˜1 μW) throughput in the fiber-optic link. It offers a promising future platform for emerging wireless network infrastructures.

Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique

OpenAIRE

Md. Rajibur Rahaman Khan; Shin-Won Kang

2016-01-01

In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal?s pulse width changes when the optical-fiber pH sensing-element of the array comes into contact with pH buffer solutions. The proposed optical-fiber PWM pH-sensing system offers a linear sensing response over a wide range of pH values from 2 to 12, with a high pH-sensing ability. The...

All-fiber, long-active-length Fabry-Perot strain sensor.

Science.gov (United States)

Pevec, Simon; Donlagic, Denis

2011-08-01

This paper presents a high-sensitivity, all-silica, all-fiber Fabry-Perot strain-sensor. The proposed sensor provides a long active length, arbitrary length of Fabry-Perot cavity, and low intrinsic temperature sensitivity. The sensor was micro-machined from purposely-developed sensor-forming fiber that is etched and directly spliced to the lead-in fiber. This manufacturing process has good potential for cost-effective, high-volume production. Its measurement range of over 3000 µε, and strain-resolution better than 1 µε were demonstrated by the application of a commercial, multimode fiber-based signal processor.

Mapping misoriented fibers using X-ray dark field tomography

DEFF Research Database (Denmark)

Lauridsen, Torsten; Lauridsen, Erik Mejdal; Feidenhans’l, Robert

2014-01-01

such tomograms on a highly nonisotropic sample, i.e. a five layer “sandwich” of oriented carbon fibers. The fibers are parallel within the individual sandwich layers, but perpendicular to the fibers in the adjacent layers. We show that by choosing a rotation axis parallel to the grating stepping direction (i.......e. a horizontal rotation axis in most setup configurations) it is possible to produce a darkfield tomogram where fibers parallel to the probed scattering direction appear to have no dark field signal. The method produces a tomogram in the form of a scalar field of dark field scattering values....

Fiber-Optic Monitoring System of Particle Counters

Directory of Open Access Journals (Sweden)

A. A. Titov

2016-01-01

Full Text Available The article considers development of a fiber-optic system to monitor the counters of particles. Presently, optical counters of particles, which are often arranged at considerable distance from each other, are used to study the saltation phenomenon. For monitoring the counters, can be used electric communication lines.However, it complicates and raises the price of system Therefore, we offered a fiber-optic system and the counter of particles, free from these shortcomings. The difference between the offered counter of particles and the known one is that the input of radiation to the counter and the output of radiation scattering on particles are made by the optical fibers, and direct radiation is entered the optical fiber rather than is delayed by a light trap and can be used for lighting the other counters thereby allowing to use their connection in series.The work involved a choice of the quartz multimode optical fiber for communication, defining the optical fiber and lenses parameters of the counter of particles, and a selection of the radiation source and the photo-detector.Using the theory of light diffraction on a particle, a measuring range of the particle sizes has been determined. The system speed has been estimated, and it has been shown that a range of communication can reach 200km.It should be noted that modulation noise of counters of particles connected in series have the impact on the useful signal. To assess the extent of this influence we have developed a calculation procedure to illustrate that with ten counters connected in series this influence on the signal-to-noise ratio will be insignificant.Thus, it has been shown that the offered fiber-optic system can be used for monitoring the counters of particles across the desertified territories. 

Direct modulation and detection link using polybinary signaling

DEFF Research Database (Denmark)

Suhr, L.F.; Vegas Olmos, Juan José; Peucheret, Christophe

2014-01-01

This paper presents experimental results on a spectral efficient optical fiber link by using a novel seven-level polybinary signaling at 14.32 Gbps achieving a potential 7.95 b/s/Hz with very little complexity and processing footprint.......This paper presents experimental results on a spectral efficient optical fiber link by using a novel seven-level polybinary signaling at 14.32 Gbps achieving a potential 7.95 b/s/Hz with very little complexity and processing footprint....

Morphological selection in an extreme flow environment: body shape and waterfall-climbing success in the Hawaiian stream fish Sicyopterus stimpsoni.

Science.gov (United States)

Blob, Richard W; Bridges, William C; Ptacek, Margaret B; Maie, Takashi; Cediel, Roberto A; Bertolas, Morgan M; Julius, Matthew L; Schoenfuss, Heiko L

2008-12-01

Flow characteristics are a prominent factor determining body shapes in aquatic organisms, and correlations between body shape and ambient flow regimes have been established for many fish species. In this study, we investigated the potential for a brief period of extreme flow to exert selection on the body shape of juvenile climbing Hawaiian gobiid fishes. Because of an amphidromous life history, juvenile gobies that complete an oceanic larval phase return to freshwater habitats, where they become adults. Returning juveniles often must scale waterfalls (typically with the use of a ventral sucker) in order to reach the habitats they will use as adults, thereby exposing these animals to brief periods of extreme velocities of flow. Hydrodynamic theory predicts that bodies with larger suckers and with lower heights that reduce drag would have improved climbing success and, thus, be well suited to meet the demands of the flows in waterfalls. To test the potential for the flow environment of waterfalls to impose selection that could contribute to differences in body shape between islands, we subjected juvenile Sicyopterus stimpsoni to climbing trials up artificial waterfalls (∼100 body lengths) and measured differences in body shape between successful and unsuccessful climbers. Waterfalls appear to represent a significant selective barrier to these fishes, as nearly 30% failed our climbing test. However, the effects of selection on morphology were not straightforward, as significant differences in shape between successful and unsuccessful climbers did not always match hydrodynamic predictions. In both selection experiments and in adult fish collected from habitats with different prevailing conditions of flow (the islands of Hawai'i versus Kaua'i), lower head heights were associated with exposure to high-flow regimes, as predicted by hydrodynamic theory. Thus, a premium appears to be placed on the reduction of drag via head morphology throughout the ontogeny of this

Rock climbing and acute emotion regulation in patients with major depressive disorder in the context of a psychological inpatient treatment: a controlled pilot trial

Directory of Open Access Journals (Sweden)

Kleinstäuber M

2017-08-01

Full Text Available Maria Kleinstäuber,1,2 Merle Reuter,3 Norbert Doll,4 Andreas J Fallgatter4 1Division of Clinical Psychology and Psychotherapy, Faculty of Psychology, Philipps University, Marburg, Germany; 2Department of Psychological Medicine, School of Medicine, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand; 3Department of Educational Psychology, Faculty of Psychology, Eberhard Karls University, Tübingen, Germany, 4Department of General Psychiatry and Psychotherapy, University Hospital for Psychiatry and Psychotherapy, Eberhard Karls University, Tübingen, Germany Background: Major depressive disorder is characterized by deficits in emotion regulation. This study examined associations between rock climbing and acute emotion regulating effects in patients with major depression. Patients and methods: In a nonrandomized, controlled study, 40 major depressive disorder inpatients were assigned to either a climbing session (n=20 or a relaxation session (n=20. Positive and negative affect, depressiveness, and coping emotions were assessed immediately before and after the session. Results: Mixed analyses of variance and covariance revealed significant time × group interaction effects for all assessed outcomes (p≤0.012: positive affect and coping emotions significantly increased and negative affect and depressiveness significantly decreased after the climbing session (1.04≤ Cohen’s d ≤1.30, in contrast to a relaxation session (0.16≤ Cohen’s d ≤0.36. Conclusion: The results show that rock climbing is associated with acute emotion regulatory effects. These findings have to be replicated with a randomized design, and future research should pay attention to possible mechanisms of rock climbing in regard to emotion regulation. Keywords: physical activity, controlled trial, relaxation, inpatient treatment

E- and W-band high-capacity hybrid fiber-wireless link

DEFF Research Database (Denmark)

Vegas Olmos, Juan José; Pang, Xiaodan; Tafur Monroy, Idelfonso

2014-01-01

In this paper we summarize the work conducted in our group in the area of E- and W-band optical high-capacity fiber-wireless links. We present performance evaluations of E- and W-band mm-wave signal generation using photonic frequency upconversion employing both VCSELs and ECLs, along with transm...... in mobile backhaul/fronthaul applications, dense distributed antenna systems and fiber-over-radio scenarios.......In this paper we summarize the work conducted in our group in the area of E- and W-band optical high-capacity fiber-wireless links. We present performance evaluations of E- and W-band mm-wave signal generation using photonic frequency upconversion employing both VCSELs and ECLs, along...... with transmission over different type of optical fibers and for a number of values for the wireless link distance. Hybrid wireless-optical links can be composed of mature and resilient technology available off-the-shelf, and provide functionalities that can add value to optical access networks, specifically...

2 micron femtosecond fiber laser

Science.gov (United States)

Liu, Jian; Wan, Peng; Yang, Lihmei

2014-07-29

Methods and systems for generating femtosecond fiber laser pulses are disclose, including generating a signal laser pulse from a seed laser oscillator; using a first amplifier stage comprising an input and an output, wherein the signal laser pulse is coupled into the input of the first stage amplifier and the output of the first amplifier stage emits an amplified and stretched signal laser pulse; using an amplifier chain comprising an input and an output, wherein the amplified and stretched signal laser pulse from the output of the first amplifier stage is coupled into the input of the amplifier chain and the output of the amplifier chain emits a further amplified, stretched signal laser pulse. Other embodiments are described and claimed.

Fiber-wireless transmission system of 108  Gb/sdata over 80 km fiber and 2×2multiple-input multiple-output wireless links at 100 GHz W-band frequency.

Science.gov (United States)

Li, Xinying; Dong, Ze; Yu, Jianjun; Chi, Nan; Shao, Yufeng; Chang, G K

2012-12-15

We experimentally demonstrate a seamlessly integrated fiber-wireless system that delivers a 108  Gb/s signal through 80 km fiber and 1 m wireless transport over free space at 100 GHz adopting polarization-division-multiplexing quadrature-phase-shift-keying (PDM-QPSK) modulation and heterodyning coherent detection. The X- and Y-polarization components of the optical PDM-QPSK baseband signal are simultaneously upconverted to 100 GHz wireless carrier by optical polarization-diversity heterodyne beating, and then independently transmitted and received by two pairs of transmitter and receiver antennas, which form a 2×2 multiple-input multiple-output wireless link. At the wireless receiver, two-stage downconversion is performed firstly in the analog domain based on balanced mixer and sinusoidal radio frequency signal, and then in the digital domain based on digital signal processing (DSP). Polarization demultiplexing is realized by the constant modulus algorithm in the DSP part at the receiver. The bit-error ratio for the 108  Gb/s PDM-QPSK signal is less than the pre-forward-error-correction threshold of 3.8×10(-3) after both 1 m wireless delivery at 100 GHz and 80 km single-mode fiber-28 transmission. To our knowledge, this is the first demonstration to realize 100  Gb/s signal delivery through both fiber and wireless links at 100 GHz.

The measurement system of birefringence and Verdet constant of optical fiber

Science.gov (United States)

Huang, Yi; Chen, Li; Guo, Qiang; Pang, Fufei; Wen, Jianxiang; Shang, Yana; Wang, Tingyun

2013-12-01

The Faraday magneto-optical effect of optical fiber has many applications in monitoring magnetic field and electric current. When a linearly polarized light propagates in the direction of a magnetic field, the plane of polarization will rotate linearly proportional to the strength of the applied magnetic field, which following the relationship of θF =VBl. θF is the Faraday rotation angle, which is proportional to the magnetic flux density B and the Verdet constant V . However, when the optical fiber contains the effect of linear birefringence, the detection of Faraday rotation angle will depend on the line birefringence. In order to determine the Verdet constant of an optical fiber under a linear birefringence, the fiber birefringence needs to be accurately measured. In this work, a model is applied to analyze the polarization properties of an optical fiber by using the Jones matrix method. A measurement system based on the lock-in amplifier technology is designed to test the Verdet constant and the birefringence of optical fiber. The magnetic field is produced by a solenoid with a DC current. A tunable laser is intensity modulated with a motorized rotating chopper. The actuator supplies a signal as the phase-locked synchronization reference to the signal of the lock-in amplifier. The measurement accuracy is analyzed and the sensitivity of the system is optimized. In this measurement system, the Verdet constant of the SMF-28 fiber was measured to be 0.56±0.02 rad/T·m at 1550nm. This setup is well suitable for measuring the high signal-to-noise ratio (SNR) sensitivity for lock-in amplifier at a low magnetic field strength.

Optic fiber pulse-diagnosis sensor of traditional Chinese medicine

Science.gov (United States)

Ni, J. S.; Jin, W.; Zhao, B. N.; Zhang, X. L.; Wang, C.; Li, S. J.; Zhang, F. X.; Peng, G. D.

2013-09-01

The wrist-pulse is a kind of signals, from which a lot of physiological and pathological status of patients are deduced according to traditional Chinese medicine theories. This paper designs a new optic fiber wrist-pulse sensor that based on a group of FBGs. Sensitivity of the optic fiber wrist-pulse measurement system reaches 0.05% FS and the range reaches 50kPa. Frequency response is from 0 Hz to 5 kHz. A group of typical pulse signal is given out in the paper to compare different status of patient. It will improve quantification of pulse diagnosis greatly.

Body shape helps legged robots climb and turn in complex 3-D terrains

Science.gov (United States)

Han, Yuanfeng; Wang, Zheliang; Li, Chen

Analogous to streamlined shapes that reduce drag in fluids, insects' ellipsoid-like rounded body shapes were recently discovered to be ``terradynamically streamlined'' and enhance locomotion in cluttered terrain by facilitating body rolling. Here, we hypothesize that there exist more terradynamic shapes that facilitate other modes of locomotion like climbing and turning in complex 3-D terrains by facilitating body pitching and yawing. To test our hypothesis, we modified the body shape of a legged robot by adding an elliptical and a rectangular shell and tested how it negotiated with circular and square vertical pillars. With a rectangular shell the robot always pitched against square pillars in an attempt to climb, whereas with an elliptical shell it always yawed and turned away from circular pillars given a small initial lateral displacement. Square / circular pillars facilitated pitching / yawing, respectively. To begin to reveal the contact physics, we developed a locomotion energy landscape model. Our model revealed that potential energy barriers to transition from pitching to yawing are high for angular locomotor and obstacle shapes (rectangular / square) but vanish for rounded shapes (elliptical / circular). Our study supports the plausibility of locomotion energy landscapes for understanding the rich locomotor transitions in complex 3-D terrains.

A Fiber Optic PD Sensor Using a Balanced Sagnac Interferometer and an EDFA-Based DOP Tunable Fiber Ring Laser

Science.gov (United States)

Wang, Lutang; Fang, Nian; Wu, Chunxu; Qin, Haijuan; Huang, Zhaoming

2014-01-01

A novel fiber-optic acoustic sensor using an erbium-doped fiber amplifier (EDFA)-based fiber ring laser and a balanced Sagnac interferometer for acoustic sensing of the partial discharge (PD) in power transformers is proposed and demonstrated. As a technical background, an experimental investigation on how the variations of the fiber birefringence affect the sensor performances was carried out, and the results are discussed. The operation principles are described, and the relevant formulas are derived. The analytical results show that an EDFA-based fiber ring laser operating in chaotic mode can provide a degree of polarization (DOP) tunable light beam for effectively suppressing polarization fading noises. The balanced Sagnac interferometer can eliminate command intensity noises and enhance the signal-to-noise ratio (SNR). Furthermore, it inherently operates at the quadrature point of the response curve without any active stabilizations. Several experiments are conducted for evaluating the performances of the sensor system, as well as for investigating the ability of the detection of high-frequency acoustic emission signals. The experimental results demonstrate that the DOP of the laser beam can be continuously tuned from 0.2% to 100%, and the power fluctuation in the whole DOP tuning range is less than 0.05 dBm. A high-frequency response up to 300 kHz is reached, and the high sensing sensitivity for detections of weak corona discharges, as well as partial discharges also is verified. PMID:24824371

Turbine-blade tip clearance and tip timing measurements using an optical fiber bundle sensor

Science.gov (United States)

Garcia, Iker; Beloki, Josu; Zubia, Joseba; Durana, Gaizka; Aldabaldetreku, Gotzon

2013-04-01

Traditional limitations of capacitive, inductive or discharging probe sensor for tip timing and tip clearance measurements are overcome by reflective intensity modulated optical fiber sensors. This paper presents the signals and results corresponding to a one stage turbine rig which rotor has 146 blades, obtained from a transonic wind-tunnel test. The probe is based on a trifurcated bundle of optical fibers that is mounted on turbine casing. It is composed of a central illuminating fiber that guides the light from a laser to the turbine blade, and two concentric rings of receiving fibers that collect the reflected light. Two photodetectors turn this reflected light signal from the receiving rings into voltage. The electrical signals are acquired and saved by a high-sample-rate oscilloscope. In tip clearance calculations the ratio of the signals provided by each ring of receiving fibers is evaluated and translated into distance. In the case of tip timing measurements, only one of the signals is considered to get the arrival time of the blade. The differences between the real and theoretical arrival times of the blades are used to obtain the deflections amplitude. The system provides the travelling wave spectrum, which presents the average vibration amplitude of the blades at a certain nodal diameter. The reliability of the results in the turbine rig testing facilities suggests the possibility of performing these measurements in real turbines under real working conditions.

Modulation, plasticity and pathophysiology of the parallel fiber-Purkinje cell synapse

Directory of Open Access Journals (Sweden)

Eriola Hoxha

2016-11-01

Full Text Available The parallel fiber-Purkinje cell synapse represents the point of maximal signal divergence in the cerebellar cortex with an estimated number of about 60 billion synaptic contacts in the rat and 100,000 billions in humans. At the same time, the Purkinje cell dendritic tree is a site of remarkable convergence of more than 100,000 parallel fiber synapses. Parallel fibers activity generates fast postsynaptic currents via AMPA receptors, and slower signals, mediated by mGlu1 receptors, resulting in Purkinje cell depolarization accompanied by sharp calcium elevation within dendritic regions. Long-term depression and long-term potentiation have been widely described for the parallel fiber-Purkinje cell synapse and have been proposed as mechanisms for motor learning. The mechanisms of induction for LTP and LTD involve different signaling mechanisms within the presynaptic terminal and/or at the postsynaptic site, promoting enduring modification in the neurotransmitter release and change in responsiveness to the neurotransmitter. The parallel fiber-Purkinje cell synapse is finely modulated by several neurotransmitters, including serotonin, noradrenaline, and acetylcholine. The ability of these neuromodulators to gate LTP and LTD at the parallel fiber-Purkinje cell synapse could, at least in part, explain their effect on cerebellar-dependent learning and memory paradigms. Overall, these findings have important implications for understanding the cerebellar involvement in a series of pathological conditions, ranging from ataxia to autism. For example, parallel fiber-Purkinje cell synapse dysfunctions have been identified in several murine models of spinocerebellar ataxia (SCA types 1, 3, 5 and 27. In some cases, the defect is specific for the AMPA receptor signaling (SCA27, while in others the mGlu1 pathway is affected (SCA1, 3, 5. Interestingly, the parallel fiber-Purkinje cell synapse has been shown to be hyper-functional in a mutant mouse model of autism

Fiber-Optic Continuous Liquid Sensor for Cryogenic Propellant Gauging

Science.gov (United States)

Xu. Wei

2010-01-01

An innovative fiber-optic sensor has been developed for low-thrust-level settled mass gauging with measurement uncertainty optical fiber to measure liquid level and liquid distribution of cryogenic propellants. Every point of the sensing fiber is a point sensor that not only distinguishes liquid and vapor, but also measures temperature. This sensor is able to determine the physical location of each point sensor with 1-mm spatial resolution. Acting as a continuous array of numerous liquid/vapor point sensors, the truly distributed optical sensing fiber can be installed in a propellant tank in the same manner as silicon diode point sensor stripes using only a single feedthrough to connect to an optical signal interrogation unit outside the tank. Either water or liquid nitrogen levels can be measured within 1-mm spatial resolution up to a distance of 70 meters from the optical interrogation unit. This liquid-level sensing technique was also compared to the pressure gauge measurement technique in water and liquid nitrogen contained in a vertical copper pipe with a reasonable degree of accuracy. It has been demonstrated that the sensor can measure liquid levels in multiple containers containing water or liquid nitrogen with one signal interrogation unit. The liquid levels measured by the multiple fiber sensors were consistent with those virtually measured by a ruler. The sensing performance of various optical fibers has been measured, and has demonstrated that they can survive after immersion at cryogenic temperatures. The fiber strength in liquid nitrogen has also been measured. Multiple water level tests were also conducted under various actual and theoretical vibration conditions, and demonstrated that the signal-to-noise ratio under these vibration conditions, insofar as it affects measurement accuracy, is manageable and robust enough for a wide variety of spacecraft applications. A simple solution has been developed to absorb optical energy at the termination of

Fiber optic spectrophotometer with photodiode linear array

International Nuclear Information System (INIS)

Blanc, F.; Vernet, P.

1988-01-01

Spectrophotometric measurements are used in a great number of industrial processes, in nuclear environment and with optical precision components. Especially the evolution of a chemical process or of an optical coating could be followed by these measurements. Spectrophotometers, using optical fibers to transport the signal out of the instrument make possible the measurement ''in-situ'' and in real time. The advantage of using a diode array to detect the signal is an instantaneous measurement all over the spectral range without moving parts. It allows an excellent reproductibility. The instrument is controlled by a micro computer. The spectrophotometer is described and technical performance presented. An extension using optical fibers on a ''classical'' spectrophotometer (a H.P. one) is also described and technical performance presented

Sub-cycle QAM modulation for VCSEL-based optical fiber links

DEFF Research Database (Denmark)

Pham, Tien-Thang; Rodes Lopez, Roberto; Jensen, Jesper Bevensee

2013-01-01

QAM modulation utilizing subcarrier frequency lower than the symbol rate is both theoretically and experimentally investigated. High spectral efficiency and concentration of power in low frequencies make sub-cycle QAM signals attractive for optical fiber links with direct modulated light sources....... Real-time generated 10-Gbps 4-level QAM signal in a 7.5-GHz bandwidth utilizing subcarrier frequency at a half symbol rate was successfully transmitted over 20-km SMF using an un-cooled 1.5-μm VCSEL. Only 2.5-dB fiber transmission power penalty was observed with no equalization applied....

Theoretical analysis of mode instability in high-power fiber amplifiers

DEFF Research Database (Denmark)

Hansen, Kristian Rymann; Alkeskjold, Thomas Tanggaard; Broeng, Jes

2013-01-01

We present a simple theoretical model of transverse mode instability in high-power rare-earth doped fiber amplifiers. The model shows that efficient power transfer between the fundamental and higher-order modes of the fiber can be induced by a nonlinear interaction mediated through the thermo......-optic effect, leading to transverse mode instability. The temporal and spectral characteristics of the instability dynamics are investigated, and it is shown that the instability can be seeded by both quantum noise and signal intensity noise, while pure phase noise of the signal does not induce instability...

Available friction of ladder shoes and slip potential for climbing on a straight ladder.

Science.gov (United States)

Chang, Wen-Ruey; Chang, Chien-Chi; Matz, Simon

2005-07-15

Straight ladder accidents are a major safety problem. As a leading cause of injuries involving straight ladders, slips at the ladder base occur when the required friction exceeds the available friction at the ladder shoe and floor interface. The objectives of this experiment were to measure the available friction at the base of a portable straight ladder in contact with a floor and to estimate the slip potential of the ladder. The results of friction measurements indicated that the measured friction coefficient on the oily surfaces differed among the six commercially available ladder shoes evaluated. A statistical model was used to compare the available friction results from the current study with the friction requirements under different climbing conditions from a previous study based on their stochastic distributions to estimate the slip potential at the base of the ladder. The results showed that different climbing conditions used in the previous study could be supported by available friction on dry surfaces. However, when the ladder was put onto oily surfaces, resulting in a significant reduction in the available friction due to contamination, slip potential was significantly increased.

Experimental demonstration of 24-Gb/s CAP-64QAM radio-over-fiber system over 40-GHz mm-wave fiber-wireless transmission.

Science.gov (United States)

Zhang, Junwen; Yu, Jianjun; Chi, Nan; Li, Fan; Li, Xinying

2013-11-04

We propose and demonstrate a novel CAP-ROF system based on multi-level carrier-less amplitude and phase modulation (CAP) 64QAM with high spectrum efficiency for mm-wave fiber-wireless transmission. The performance of novel CAP modulation with high order QAM, for the first time, is investigated in the mm-wave fiber-wireless transmission system. One I/Q modulator is used for mm-wave generation and base-band signal modulation based on optical carrier suppression (OCS) and intensity modulation. Finally, we demonstrated a 24-Gb/s CAP-64QAM radio-over-fiber (ROF) system over 40-km stand single-mode-fiber (SMMF) and 1.5-m 38-GHz wireless transmission. The system operation factors are also experimentally investigated.

Quantifying anisotropy and fiber orientation in human brain histological sections

Directory of Open Access Journals (Sweden)

Matthew D Budde

2013-02-01

Full Text Available Diffusion weighted imaging (DWI has provided unparalleled insight into the microscopic structure and organization of the central nervous system. Diffusion tensor imaging (DTI and other models of the diffusion MRI signal extract microstructural properties of tissues with relevance to the normal and injured brain. Despite the prevalence of such techniques and applications, accurate and large-scale validation has proven difficult, particularly in the human brain. In this report, human brain sections obtained from a digital public brain bank were employed to quantify anisotropy and fiber orientation using structure tensor analysis. The derived maps depict the intricate complexity of white matter fibers at a resolution not attainable with current DWI experiments. Moreover, the effects of multiple fiber bundles (i.e. crossing fibers and intravoxel fiber dispersion were demonstrated. Examination of the cortex and hippocampal regions validated specific features of previous in vivo and ex vivo DTI studies of the human brain. Despite the limitation to two dimensions, the resulting images provide a unique depiction of white matter organization at resolutions currently unattainable with DWI. The method of analysis may be used to validate tissue properties derived from DTI and alternative models of the diffusion signal.

Cerebellar-inspired adaptive control of a robot eye actuated by pneumatic artificial muscles.

Science.gov (United States)

Lenz, Alexander; Anderson, Sean R; Pipe, A G; Melhuish, Chris; Dean, Paul; Porrill, John

2009-12-01

In this paper, a model of cerebellar function is implemented and evaluated in the control of a robot eye actuated by pneumatic artificial muscles. The investigated control problem is stabilization of the visual image in response to disturbances. This is analogous to the vestibuloocular reflex (VOR) in humans. The cerebellar model is structurally based on the adaptive filter, and the learning rule is computationally analogous to least-mean squares, where parameter adaptation at the parallel fiber/Purkinje cell synapse is driven by the correlation of the sensory error signal (carried by the climbing fiber) and the motor command signal. Convergence of the algorithm is first analyzed in simulation on a model of the robot and then tested online in both one and two degrees of freedom. The results show that this model of neural function successfully works on a real-world problem, providing empirical evidence for validating: 1) the generic cerebellar learning algorithm; 2) the function of the cerebellum in the VOR; and 3) the signal transmission between functional neural components of the VOR.

Goffman Goes Rock Climbing: Using Creative Fiction to Explore the Presentation of Self in Outdoor Education

Science.gov (United States)

Beames, Simon K.; Pike, Elizabeth C. J.

2008-01-01

Outdoor education literature has a recent history of examining its practice through a variety of sociological, philosophical, psychological, and anthropological lenses. Following this trend, this paper explores the face-to-face social interaction of a fictional introductory rock-climbing course. The analysis of this creative fiction draws on…

A Special Fiber Optic Sensor for Measuring Wheel Loads of Vehicles on Highways

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Norman W. Garrick

2008-04-01

Full Text Available This paper presents results from an investigation on a special optical fiber as a load sensor for application in Weigh-in-Motion (WIM systems to measure wheel loads of vehicles traveling at normal speed on highways. The fiber used has a unique design with two concentric light guiding regions of different effective optical path lengths, which has the potential to enable direct measurement of magnitudes as well as locations of forces acting at multiple points along a single fiber. The optical characteristic of the fiber for intended sensing purpose was first assessed by a simple fiber bending experiment and by correlating the bend radii with the output light signal intensities. A simple laboratory load transmitting/fiber bending device was then designed and fabricated to appropriately bend the optical fiber under applied loads in order to make the fiber work as load sensor. The device with the optical fiber was tested under a universal loading machine and an actual vehicle wheel in the laboratory. The test results showed a good relationship between the magnitude of the applied load and the output optical signal changes. The results also showed a good correlation between the time delay between the inner and outer core light pulses and the distance of the applied load as measured from the output end of the fiber.

Behavior of optical fibers under heavy irradiation

International Nuclear Information System (INIS)

Kakuta, T.; Sagawa, T.

1998-01-01

Several kinds of optical diagnostics are planned in a fusion reactor. Complicated optical systems such as periscopes are thought to be primary candidates for optical measurements, especially for visible wavelengths. However, optical fibers have several advantages over such optical systems. Also, the optical fibers could be a far better transmission line for signals under a high electromagnetic field. However, they have been considered vulnerable to heavy irradiation. In this study, several kinds of optical fibers were irradiated in the JMTR fission reactor. The optical transmissivity in fibers was measured in situ during fast neutron and gamma irradiation, up to doses of 2 x 10 24 n m -2 and 5 x 10 9 Gy, respectively. The irradiation temperature ranged from 300 to 700 K. For pure ionizing irradiation environments, some methods for improving the radiation resistance of optical fibers were indicated. The results showed that effects of the irradiation associated with fast neutrons would be different from the effects of pure ionizing irradiation. Some fibers were found to withstand the heavy irradiation, especially in an infrared wavelength range. (orig.)

Bidirectional 3.125 Gbps downstream / 2 Gbps upstream impulse radio ultrawide-band (UWB) over combined fiber and wireless link

DEFF Research Database (Denmark)

Jensen, Jesper Bevensee; Gibbon, Timothy Braidwood; Yu, Xianbin

2010-01-01

We demonstrate bidirectional fiber and wireless transmission of impulse radio ultra-wideband at 3.125 Gbps downstream and 2 Gbps upstream. After transmission over 50 km fiber and 1.85 m wireless link both signals are recovered without errors.......We demonstrate bidirectional fiber and wireless transmission of impulse radio ultra-wideband at 3.125 Gbps downstream and 2 Gbps upstream. After transmission over 50 km fiber and 1.85 m wireless link both signals are recovered without errors....

Fiber Pulling Apparatus

Science.gov (United States)

Workman, Gary L.; Smith, Guy A.; OBrien, Sue; Adcock, Leonard

1998-01-01

than 50% of the total budget each year through 1998. A newly emerging activity is the commercial development of doped optical fibers which can be pumped by laser diodes to provide amplification of the communication signals. This technology is newly emerging and will be developed for commercial interests in the United States by Galileo Electro-optical Incorporated in Sturbridge, MA on a license from British Telecom. Long repeaterless communication links provide the biggest stimulus for this technology. As an example of the of the revenues involved in the optical fiber communications 3 industry, the current trade journal lists that for the fiscal years, 1991 - 1994, 185 separate undersea links were established. In addition, another 105 links are planned through 1998. The distribution of revenues involved in the undersea installations is roughly $8.5 billion through 1993 and another $13 billion planned through 1998. A large portion of the future activity (34%) is planned for Southeast Asia and the Pacific Region. Other examples of the commercial utility of optical fiber networks is given in a recent scientific symposium in which the outlook for HMFG infrared fiber was determined to be very bright.Another area of interest lies in the use of fiber optics for laser surgery delivery systems.

Fiber optical asssembly for fluorescence spectrometry

Science.gov (United States)

Piltch, Martin S.; Gray, Perry Clayton; Rubenstein, Richard

2015-08-18

System is provided for detecting the presence of an analyte of interest in a sample, said system comprising an elongated, transparent container for a sample; an excitation source in optical communication with the sample, wherein radiation from the excitation source is directed along the length of the sample, and wherein the radiation induces a signal which is emitted from the sample; and, at least two linear arrays disposed about the sample holder, each linear array comprising a plurality of optical fibers having a first end and a second end, wherein the first ends of the fibers are disposed along the length of the container and in proximity thereto; the second ends of the fibers of each array are bundled together to form a single end port.

Single-step emulation of nonlinear fiber-optic link with gaussian mixture model

DEFF Research Database (Denmark)

Borkowski, Robert; Doberstein, Andy; Haisch, Hansjörg

2015-01-01

We use a fast and low-complexity statistical signal processing method to emulate nonlinear noise in fiber links. The proposed emulation technique stands in good agreement with the numerical NLSE simulation for 32 Gbaud DP-16QAM nonlinear transmission.......We use a fast and low-complexity statistical signal processing method to emulate nonlinear noise in fiber links. The proposed emulation technique stands in good agreement with the numerical NLSE simulation for 32 Gbaud DP-16QAM nonlinear transmission....

Hybrid fiber grating cavity for multi-parametric sensing.

Science.gov (United States)

Paladino, Domenico; Quero, Giuseppe; Caucheteur, Christophe; Mégret, Patrice; Cusano, Andrea

2010-05-10

We propose an all-fiber hybrid cavity involving two unbalanced uniform fiber Bragg gratings (FBGs) written at both sides of a tilted FBG (TFBG) to form an all-fiber interferometer. This configuration provides a wavelength gated reflection signal with interference fringes depending on the cavity features modulated by spectral dips associated to the wavelength dependent optical losses due to cladding mode coupling occurring along the TFBG. Such a robust structure preserves the advantages of uniform FBGs in terms of interrogation methods and allows the possibility of simultaneous physical and chemical sensing. (c) 2010 Optical Society of America.

Characterization of Scintillating X-ray Optical Fiber Sensors

Science.gov (United States)

Sporea, Dan; Mihai, Laura; Vâţă, Ion; McCarthy, Denis; O'Keeffe, Sinead; Lewis, Elfed

2014-01-01

The paper presents a set of tests carried out in order to evaluate the design characteristics and the operating performance of a set of six X-ray extrinsic optical fiber sensors. The extrinsic sensor we developed is intended to be used as a low energy X-ray detector for monitoring radiation levels in radiotherapy, industrial applications and for personnel dosimetry. The reproducibility of the manufacturing process and the characteristics of the sensors were assessed. The sensors dynamic range, linearity, sensitivity, and reproducibility are evaluated through radioluminescence measurements, X-ray fluorescence and X-ray imaging investigations. Their response to the operating conditions of the excitation source was estimated. The effect of the sensors design and implementation, on the collecting efficiency of the radioluminescence signal was measured. The study indicated that the sensors are efficient only in the first 5 mm of the tip, and that a reflective coating can improve their response. Additional tests were done to investigate the concentricity of the sensors tip against the core of the optical fiber guiding the optical signal. The influence of the active material concentration on the sensor response to X-ray was studied. The tests were carried out by measuring the radioluminescence signal with an optical fiber spectrometer and with a Multi-Pixel Photon Counter. PMID:24556676

K-means-clustering-based fiber nonlinearity equalization techniques for 64-QAM coherent optical communication system.

Science.gov (United States)

Zhang, Junfeng; Chen, Wei; Gao, Mingyi; Shen, Gangxiang

2017-10-30

In this work, we proposed two k-means-clustering-based algorithms to mitigate the fiber nonlinearity for 64-quadrature amplitude modulation (64-QAM) signal, the training-sequence assisted k-means algorithm and the blind k-means algorithm. We experimentally demonstrated the proposed k-means-clustering-based fiber nonlinearity mitigation techniques in 75-Gb/s 64-QAM coherent optical communication system. The proposed algorithms have reduced clustering complexity and low data redundancy and they are able to quickly find appropriate initial centroids and select correctly the centroids of the clusters to obtain the global optimal solutions for large k value. We measured the bit-error-ratio (BER) performance of 64-QAM signal with different launched powers into the 50-km single mode fiber and the proposed techniques can greatly mitigate the signal impairments caused by the amplified spontaneous emission noise and the fiber Kerr nonlinearity and improve the BER performance.

Improving patient safety: lessons from rock climbing.

Science.gov (United States)

Robertson, Nic

2012-02-01

How to improve patient safety remains an intractable problem, despite large investment and some successes. Academics have argued that the root of the problem is a lack of a comprehensive 'safety culture' in hospitals. Other safety-critical industries such as commercial aviation invest heavily in staff training to develop such a culture, but comparable programmes are almost entirely absent from the health care sector. In rock climbing and many other dangerous activities, the 'buddy system' is used to ensure that safety systems are adhered to despite adverse circumstances. This system involves two or more people using simple checks and clear communication to prevent problems causing harm. Using this system as an example could provide a simple, original and entertaining way of introducing medical students to the idea that human factors are central to ensuring patient safety. Teaching the buddy system may improve understanding and acceptance of other patient safety initiatives, and could also be used by junior doctors as a tool to improve the safety of their practice. © Blackwell Publishing Ltd 2012.

Autonomous stair-climbing with miniature jumping robots.

Science.gov (United States)

Stoeter, Sascha A; Papanikolopoulos, Nikolaos

2005-04-01

The problem of vision-guided control of miniature mobile robots is investigated. Untethered mobile robots with small physical dimensions of around 10 cm or less do not permit powerful onboard computers because of size and power constraints. These challenges have, in the past, reduced the functionality of such devices to that of a complex remote control vehicle with fancy sensors. With the help of a computationally more powerful entity such as a larger companion robot, the control loop can be closed. Using the miniature robot's video transmission or that of an observer to localize it in the world, control commands can be computed and relayed to the inept robot. The result is a system that exhibits autonomous capabilities. The framework presented here solves the problem of climbing stairs with the miniature Scout robot. The robot's unique locomotion mode, the jump, is employed to hop one step at a time. Methods for externally tracking the Scout are developed. A large number of real-world experiments are conducted and the results discussed.

Nanosphere Lithography on Fiber: Towards Engineered Lab-On-Fiber SERS Optrodes

Directory of Open Access Journals (Sweden)

Giuseppe Quero

2018-02-01

Full Text Available In this paper we report on the engineering of repeatable surface enhanced Raman scattering (SERS optical fiber sensor devices (optrodes, as realized through nanosphere lithography. The Lab-on-Fiber SERS optrode consists of polystyrene nanospheres in a close-packed arrays configuration covered by a thin film of gold on the optical fiber tip. The SERS surfaces were fabricated by using a nanosphere lithography approach that is already demonstrated as able to produce highly repeatable patterns on the fiber tip. In order to engineer and optimize the SERS probes, we first evaluated and compared the SERS performances in terms of Enhancement Factor (EF pertaining to different patterns with different nanosphere diameters and gold thicknesses. To this aim, the EF of SERS surfaces with a pitch of 500, 750 and 1000 nm, and gold films of 20, 30 and 40 nm have been retrieved, adopting the SERS signal of a monolayer of biphenyl-4-thiol (BPT as a reliable benchmark. The analysis allowed us to identify of the most promising SERS platform: for the samples with nanospheres diameter of 500 nm and gold thickness of 30 nm, we measured values of EF of 4 × 105, which is comparable with state-of-the-art SERS EF achievable with highly performing colloidal gold nanoparticles. The reproducibility of the SERS enhancement was thoroughly evaluated. In particular, the SERS intensity revealed intra-sample (i.e., between different spatial regions of a selected substrate and inter-sample (i.e., between regions of different substrates repeatability, with a relative standard deviation lower than 9 and 15%, respectively. Finally, in order to determine the most suitable optical fiber probe, in terms of excitation/collection efficiency and Raman background, we selected several commercially available optical fibers and tested them with a BPT solution used as benchmark. A fiber probe with a pure silica core of 200 µm diameter and high numerical aperture (i.e., 0.5 was found to be the

Turning behaviors of T cells climbing up ramp-like structures are regulated by myosin light chain kinase activity and lamellipodia formation.

Science.gov (United States)

Song, Kwang Hoon; Lee, Jaehyun; Jung, Hong-Ryul; Park, HyoungJun; Doh, Junsang

2017-09-14

T cells navigate diverse microenvironments to perform immune responses. Micro-scale topographical structures within the tissues, which may inherently exist in normal tissues or may be formed by inflammation or injury, can influence T cell migration, but how T cell migration is affected by such topographical structures have not been investigated. In this study, we fabricated ramp-like structures with a 5 μm height and various slopes, and observed T cells climbing up the ramp-like structures. T cells encountering the ramp-like structures exhibited MLC accumulation near head-tail junctions contacting the ramp-like structures, and made turns to the direction perpendicular to the ramp-like structures. Pharmacological study revealed that lamellipodia formation mediated by arp2/3 and contractility regulated by myosin light chain kinase (MLCK) were responsible for the intriguing turning behavior of T cells climbing the ramp-like structures. Arp2/3 or MLCK inhibition substantially reduced probability of T cells climbing sharp-edged ramp-like structures, indicating intriguing turning behavior of T cells mediated by lamellipodia formation and MLCK activity may be important for T cells to access inflamed or injured tissues with abrupt topographical changes.

Guided wave and damage detection in composite laminates using different fiber optic sensors.

Science.gov (United States)

Li, Fucai; Murayama, Hideaki; Kageyama, Kazuro; Shirai, Takehiro

2009-01-01

Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber reinforced plastic (CFRP) laminate and acquired by these fiber optic sensors. Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared. Results demonstrated that both the FBG and FOD sensors can be applied in guided wave and damage detection for the CFRP laminates. The signal-to-noise ratio (SNR) of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection. Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH(0)) guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent.

On the static structural design of climbing robots: part 2.

Science.gov (United States)

Ahmed, Ausama Hadi; Menon, Carlo

This manuscript is the second of two parts of a work investigating optimal configurations of legged climbing robots while loitering on vertical surfaces. In this Part 2, a structural analysis based on the finite element method, specifically the stiffness method, is performed to address the problem. Parameters that are investigated in this Part 2 include the inclination of both the body and the legs of the robot. Outcomes of the performed study are validated by analyzing the posture of 150 ants when loitering on vertical surfaces. The obtained validation ensures the predictions of the developed structural model are correct and can be used to identify optimal configurations of legged robots when loitering on vertical surfaces.

Improving Students’ Mastery on Simple Present Tense Through Climbing Grammar Mountain Game

Directory of Open Access Journals (Sweden)

Fadilla Taslim

2016-07-01

Full Text Available This study aims to determine whether the use of Climbing Grammar Mountain Game gave significant improvement on students in learning simple present tense. Classroom action research was used in this study where the data were analyzed by using quantitative and qualitative approaches. The population of the study was the students of grade eleventh at SMPN 1 Luak 50 Kota. There were 21 students in this class. Six kinds of instruments were used to collect data, namely teaching ,scenario, observation sheet, questionnaire, test, interview, and teacher’s journal. This study ran for two cycles. In the second cycle, it was shown that there was gradual improvement from the previous cycle which changed from 64 (insufficient to 79 (sufficient of the mean score. it was more than criteria of the students’ mean score which were determined in this study and it was significant because it proved that the students enthusiasm to study simple present tense, it mean that the students liked and were not bored again so this was a motivation for them to more concentrate to study simple present tense and they could use it in daily life for communication. They understand that simple present tense is important in learning English because it is used in daily life, either in writing and spoken language. It could be concluded that Climbing Grammar Mountain Game could improve the ability of the students in class VII B of SMPN 1 Luak 50 Kota in using Simple Present Tense.

Development of suspended core soft glass fibers for far-detuned parametric conversion