WorldWideScience

Sample records for two-phase region grows

  1. Two-phase treatment of class II malocclusion in young growing patient

    Directory of Open Access Journals (Sweden)

    U S Krishna Nayak

    2011-01-01

    Full Text Available The use of functional jaw orthopedics, at the correct time during growth, can ultimately result in malocclusion patients achieving a broad beautiful smile, an excellent functional occlusion, a full face with a beautiful jaw line and lateral profile. Following is a case report of a young growing individual with mandibular retrognathia. Treatment was planned in two stages with the use of twin block during the first phase for correction of skeletal malocclusion and forward positioning of the mandible, followed by the second phase of fixed pre-adjusted edgewise orthodontic appliance for camouflaging the remaining skeletal discrepancy and achieving a stable harmonious occlusion.

  2. Broadcast classical-quantum capacity region of two-phase bidirectional relaying channels

    Energy Technology Data Exchange (ETDEWEB)

    Boche, Holger; Cai, Minglai; Deppe, Christian [Technische Universitaet Muenchen, Fakultaet fuer Elektrotechnik und Informationstechnik, Lehrstuhl fuer Theoretische Informationstechnik (Germany)

    2014-07-01

    The transmission of quantum states over long distances is essential for future applications such as quantum networks. The direct transmission is limited by unavoidable losses of the channel. A promising alternative for long distance quantum states distribution is the use of quantum repeaters. We analyze a quantum repeater protocol which takes advantage of bidirectional communication. We consider a three-node quantum network which enables bidirectional communication between two nodes with a half-duplex relay node. The message m{sub 2} element of M{sub 2} is located at node 1 and the message m{sub 1} element of M{sub 1} is located at node 2, respectively. Our goal is that the message m{sub 2} element of M{sub 2} is known at node 2 and the message m{sub 1} element of M{sub 1} is known at node 1, respectively. We simplify the problem by assuming an a priori separation of the communication into two phases. The capacity of the first phase (MAC) is known. We determine the capacity region of the second phase (broadcast).

  3. Parallelized Seeded Region Growing Using CUDA

    Science.gov (United States)

    Park, Seongjin; Lee, Hyunna; Seo, Jinwook; Lee, Kyoung Ho; Shin, Yeong-Gil; Kim, Bohyoung

    2014-01-01

    This paper presents a novel method for parallelizing the seeded region growing (SRG) algorithm using Compute Unified Device Architecture (CUDA) technology, with intention to overcome the theoretical weakness of SRG algorithm of its computation time being directly proportional to the size of a segmented region. The segmentation performance of the proposed CUDA-based SRG is compared with SRG implementations on single-core CPUs, quad-core CPUs, and shader language programming, using synthetic datasets and 20 body CT scans. Based on the experimental results, the CUDA-based SRG outperforms the other three implementations, advocating that it can substantially assist the segmentation during massive CT screening tests. PMID:25309619

  4. Parallelized seeded region growing using CUDA.

    Science.gov (United States)

    Park, Seongjin; Lee, Jeongjin; Lee, Hyunna; Shin, Juneseuk; Seo, Jinwook; Lee, Kyoung Ho; Shin, Yeong-Gil; Kim, Bohyoung

    2014-01-01

    This paper presents a novel method for parallelizing the seeded region growing (SRG) algorithm using Compute Unified Device Architecture (CUDA) technology, with intention to overcome the theoretical weakness of SRG algorithm of its computation time being directly proportional to the size of a segmented region. The segmentation performance of the proposed CUDA-based SRG is compared with SRG implementations on single-core CPUs, quad-core CPUs, and shader language programming, using synthetic datasets and 20 body CT scans. Based on the experimental results, the CUDA-based SRG outperforms the other three implementations, advocating that it can substantially assist the segmentation during massive CT screening tests.

  5. Mathematical model of the two-phase flow in a vertical well with an electric centrifugal pump located in the permafrost region

    Science.gov (United States)

    Musakaev, N. G.; Borodin, S. L.

    2016-05-01

    The mathematical model of the two-phase flow in a vertical well with an electric centrifugal pump located in the permafrost region is presented. The comparison of the calculation's results with experimental data, the results of numerical experiments by determining the flow structure, the temperature distribution in a well, influence of the temperature distribution on paraffin deposition and change in time of the radius of thawing in the frozen ground are presented.

  6. Fabric Defect Detection Based on Regional Growing PCNN

    OpenAIRE

    2012-01-01

    This paper presents an adaptive image segmentation method based on a new Regional Growing Pulse Coupled Neural Network (PCNN) model for detecting fabric defects. In this method, the pixels of analyzed image are mapped on the neurons in a pulse coupled neural network. Improved PCNN model and regional growing theory are combined in the light of the requirements for fabric defect detection. And the mean and variance value of the defect-free images are introduced into this model. The validation t...

  7. Microstructure Formations in the Two-Phase Region of the Binary Peritectic Organic System TRIS-NPG

    Science.gov (United States)

    Mogeritsch, Johann; Ludwig, Andreas

    2012-01-01

    In order to prepare for an onboard experiment on the International Space Station (ISS), systematic directional solidification experiments with transparent hypoperitectic alloys were carried out at different solidification rates around the critical velocity for morphological stability of both solid phases. The investigations were done in the peritectic region of the binary transparent organic TRIS-NPG system where the formation of layered structures is expected to occur. The transparent appearance of the liquid and solid phase enables real time observations of the dynamic of pattern formation during solidification. The investigations show that frequently occurring nucleation events govern the peritectic solidification morphology which occurs at the limit of morphological stability. As a consequence, banded structures lead to coupled growth even if the lateral growth is much faster compared to the growth in pulling direction.

  8. SAR Imagery Segmentation by Statistical Region Growing and Hierarchical Merging

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela Mayumi; Carvalho, E.A.; Medeiros, F.N.S.; Martins, C.I.O.; Marques, R.C.P.; Oliveira, I.N.S.

    2010-05-22

    This paper presents an approach to accomplish synthetic aperture radar (SAR) image segmentation, which are corrupted by speckle noise. Some ordinary segmentation techniques may require speckle filtering previously. Our approach performs radar image segmentation using the original noisy pixels as input data, eliminating preprocessing steps, an advantage over most of the current methods. The algorithm comprises a statistical region growing procedure combined with hierarchical region merging to extract regions of interest from SAR images. The region growing step over-segments the input image to enable region aggregation by employing a combination of the Kolmogorov-Smirnov (KS) test with a hierarchical stepwise optimization (HSWO) algorithm for the process coordination. We have tested and assessed the proposed technique on artificially speckled image and real SAR data containing different types of targets.

  9. Two phase sampling

    CERN Document Server

    Ahmad, Zahoor; Hanif, Muhammad

    2013-01-01

    The development of estimators of population parameters based on two-phase sampling schemes has seen a dramatic increase in the past decade. Various authors have developed estimators of population using either one or two auxiliary variables. The present volume is a comprehensive collection of estimators available in single and two phase sampling. The book covers estimators which utilize information on single, two and multiple auxiliary variables of both quantitative and qualitative nature. Th...

  10. A MICRO-IMAGE FUSION ALGORITHM BASED ON REGION GROWING

    Institute of Scientific and Technical Information of China (English)

    Bai Cuixia; Jiang Gangyi; Yu Mei; Wang Yigang; Shao Feng; Peng Zongju

    2013-01-01

    Due to the limitation of Depth Of Field (DOF) of microscope,the regions which are not within the DOF will be blurring after imaging.Thus for micro-image fusion,the most important step is to identify the blurring regions within each micro-image,so as to remove their undesirable impacts on the fused image.In this paper,a fusion algorithm based on a novel region growing method is proposed for micro-image fusion.The local sharpness of micro-image is judged block by block,then blocks whose sharpness is lower than an adaptive threshold are used as seeds,and the sharpness of neighbors of each seed are evaluated again during the region growing until the blurring regions are identified completely.With the decreasing in block size,the obtained region segmentation becomes more and more accurate.Finally,the micro-images are fused with pixel-wise fusion rules.The experimental results show that the proposed algorithm benefits from the novel region segmentation and it is able to obtain fused micro-image with higher sharpness compared with some popular image fusion method.

  11. Modeling of Developing Inhomogeneities in the Ferrite Microstructure and Resulting Mechanical Properties Induced by Deformation in the Two-Phase Region

    Energy Technology Data Exchange (ETDEWEB)

    Majta, J; Zurek, A.K.; Pietrzyk, M.

    1999-07-13

    The differences in microstructure development of hot deformed steels in the austenite and two-phase region have been effectively described using an integrated computer modeling process. In general, the complete model presented here takes into account kinetics of recrystallization, precipitation, phase transformation, recrystallized austenite grain size, ferrite grain size, and the resulting mechanical properties. The transformation submodel of niobium-microalloyed steels is based on the nucleation and grain growth theory and additivity rule. The thermomechanical part of the modeling process was effectively carried out using the finite element method. Results were obtained in different temperatures, strain rates, and range of deformation. The thermomechanical treatments are different for two grades of niobium-steels to make possible analysis of the resulting structure and properties for different histories of deformation and chemical composition.

  12. Fabric Defect Detection Based on Regional Growing PCNN

    Directory of Open Access Journals (Sweden)

    Xiaoshu Si

    2012-10-01

    Full Text Available This paper presents an adaptive image segmentation method based on a new Regional Growing Pulse Coupled Neural Network (PCNN model for detecting fabric defects. In this method, the pixels of analyzed image are mapped on the neurons in a pulse coupled neural network. Improved PCNN model and regional growing theory are combined in the light of the requirements for fabric defect detection. And the mean and variance value of the defect-free images are introduced into this model. The validation tests on the developed algorithm were performed with fabric images from TILDA database and results showed that the proposed method is feasible and efficient for fabric defect detection. 

  13. The Growing Use of GMES across Europe’s Regions

    Directory of Open Access Journals (Sweden)

    Redazione GEOmedia

    2013-03-01

    Full Text Available Una guida per i decisori politici sulle potenzialità e ibenefici derivanti dall’uso delle tecnologie di monitoraggiodella Terra nelle regioni EuropeeAbstractThe Growing Use of GMES across Europe’s Regions” LaunchEvent at the European Parliament.NEREUS – Network of European Regions Using Space Technologiesand ESA – European Space Agency, are pleased to announce the launch of a joint publication with the title “TheGrowing Use of GMES across Europe’s Regions”, a collection of 67 illustrative articles on regional GMES applications. Addressed to a non-specialist audience, the collection illustrates the strategic value of the Programme for regional administrations and authorities in the context of territorial management and forward planning. The variety of existing andpotential regional uses across Europe shows how GMES not only contributes to better informed decision making but also how the data can be exploited to support sustainable environmental protection with a long term perspective. Quoting end user experiences, the publication gives a first-hand impression on the impact of GMES on regional development and policy implementation.

  14. MELNIK VINE-GROWING REGION – HISTORY AND TRADITIONS

    Directory of Open Access Journals (Sweden)

    Radoslava Ganeva

    2017-06-01

    Full Text Available The region of Melnik (Southwest Bulgaria has exclusively appropriate climate for wine growing. Its borders are defined by the dissemination of the wide Melnik grape vine, revealed by experts as an old local variety. Few are the wine-growing centers that carry such an effective ampelographic tradition. A few are the viticulture centers, bearing such effective tradition. The vine is grown here from the Thracian antiquity and is the basis for a livelihood, preserved and retransmitted for many generations. It is characterized by a specialization in the production and marketing of high quality red dry wines. The article deals with the development of the Melnik vineyard as a result of different political and economic conditions in the course of historical development. Various archival materials, specialized studies and personal fieldwork research have been used.

  15. An iterative approach to region growing using associative memories

    Science.gov (United States)

    Snyder, W. E.; Cowart, A.

    1983-01-01

    Region growing, often given as a classical example of the recursive control structures used in image processing which are often awkward to implement in hardware where the intent is the segmentation of an image at raster scan rates, is addressed in light of the postulate that any computation which can be performed recursively can be performed easily and efficiently by iteration coupled with association. Attention is given to an algorithm and hardware structure able to perform region labeling iteratively at scan rates. Every pixel is individually labeled with an identifier which signifies the region to which it belongs. Difficulties otherwise requiring recursion are handled by maintaining an equivalence table in hardware transparent to the computer, which reads the labeled pixels. A simulation of the associative memory has demonstrated its effectiveness.

  16. Video Segmentation Using Fast Marching and Region Growing Algorithms

    Directory of Open Access Journals (Sweden)

    Eftychis Sifakis

    2002-04-01

    Full Text Available The algorithm presented in this paper is comprised of three main stages: (1 classification of the image sequence and, in the case of a moving camera, parametric motion estimation, (2 change detection having as reference a fixed frame, an appropriately selected frame or a displaced frame, and (3 object localization using local colour features. The image sequence classification is based on statistical tests on the frame difference. The change detection module uses a two-label fast marching algorithm. Finally, the object localization uses a region growing algorithm based on the colour similarity. Video object segmentation results are shown using the COST 211 data set.

  17. Flotation bubble image segmentation based on seed region boundary growing

    Institute of Scientific and Technical Information of China (English)

    Zhang Guoying; Zhu Hong; Xu Ning

    2011-01-01

    Segmenting blurred and conglutinated bubbles in a flotation image is done using a new segmentation method based on Seed Region and Boundary Growing (SRBG). Bright pixels located on bubble tops were extracted as the seed regions. Seed boundaries are divided into four curves: left-top, right-top, rightbottom, and left-bottom. Bubbles are segmented from the seed boundary by moving these curves to the bubble boundaries along the corresponding directions. The SRBG method can remove noisy areas and it avoids over- and under-segmentation problems. Each bubble is segmented separately rather than segmenting the entire flotation image. The segmentation results from the SRBG method are more accurate than those from the Watershed algorithm.

  18. Influence of growing and exploatation of bovins on regional agroecosystems

    Directory of Open Access Journals (Sweden)

    Cornel Podar

    2011-12-01

    Full Text Available Scientists all over the are concerned regarding the influence of growing ruminants on regional agro-ecosystems due to green house gases resulted (CO 2, CH4, N2O5. Cattle have contributed to environmental pollution in old industrial farming systems, when the cattle number in Romania, reached 8 million, manure evacuation was not solved and manure was accumulating around the farm polluting the soil, water and air. Low density of ruminants existing in the agricultural sector of the country is not significant in terms of pollution. Currently cattle have positive effects on the environment by the use of legumes, grasses and manure production contributing to the increase of agricultural production: crop production (sugar beet, potato and cereals, animal production (milk, meat, leather production and industrial production also (biogas, befouls, alcohol, oil production.

  19. ORGANIZATION AND PROFITABILITY OF POTATOES GROWING IN SLAVONIA REGION

    Directory of Open Access Journals (Sweden)

    J. Kanisek

    2001-12-01

    Full Text Available In the period 1997-1999 vegetable areas in Croatia were reduced by 8.2% and potatoes by 17.3% compared to the pre-war period. Slavonia and Baranya region is known for 16.8% of potatoes domestic production. Total production costs of mercantile potatoes on a farm of Vukovar region amount to HRK 26,828.66 /ha of which 11,750.00 accounts for seed consumption, 4796.70 machinery work, 4371.38 human labour, 1334.47 fertilizers, 1352.94 manure and 1907.35 chemical agents. Two hundred and ninety nine human labour hours and 61.9 machinery work hours were consumed per hectare. A profit of HRK 5671.34/ha was obtained by the yield of 25 t/ha. The work productivity was 83.6 kg/hour and profitability 21.14%. Amount of HRK 26,342.78/ha was consumed at a production of 23,834 kg/ha on a farm in Brodsko-Posavian county. The work productivity was 93.1 kg/hr. with 10.8 hr/t whereas profitability amounted to 17.52%. Early potatoes growing is profitable on the insured market. A profit of HRK 7.761.00/ha was attained from 8.000 kg/ha or HRK 32.02 per HRK100 invested in production.Keywords: potatoes, organization, profit, profitablity

  20. Yeast diversity on grapes in two German wine growing regions.

    Science.gov (United States)

    Brysch-Herzberg, Michael; Seidel, Martin

    2015-12-01

    The yeast diversity on wine grapes in Germany, one of the most northern wine growing regions of the world, was investigated by means of a culture dependent approach. All yeast isolates were identified by sequence analysis of the D1/D2 domain of the 26S rDNA and the ITS region. Besides Hanseniaspora uvarum and Metschnikowia pulcherrima, which are well known to be abundant on grapes, Metschnikowia viticola, Rhodosporidium babjevae, and Curvibasidium pallidicorallinum, as well as two potentially new species related to Sporidiobolus pararoseus and Filobasidium floriforme, turned out to be typical members of the grape yeast community. We found M. viticola in about half of the grape samples in high abundance. Our data strongly suggest that M. viticola is one of the most important fermenting yeast species on grapes in the temperate climate of Germany. The frequent occurrence of Cu. pallidicorallinum and strains related to F. floriforme is a new finding. The current investigation provides information on the distribution of recently described yeast species, some of which are known from a very few strains up to now. Interestingly yeasts known for their role in the wine making process, such as Saccharomyces cerevisiae, Saccharomyces bayanus ssp. uvarum, Torulaspora delbrueckii, and Zygosaccharomyces bailii, were not found in the grape samples.

  1. Knudsen effusion mass spectrometric studies over (USn3+U3Sn7) two-phase region of U-Sn system

    Science.gov (United States)

    Manikandan, P.; Trinadh, V. V.; Bera, Suranjan; Narasimhan, T. S. Lakshmi; Ananthasivan, K.; Joseph, M.; Mudali, U. Kamachi

    2017-08-01

    Vaporisation studies over (USn3+U3Sn7) ;two-phase; field have been carried out by employing Knudsen effusion mass spectrometry (KEMS) in the temperature range of 1050-1226 K. Sn(g) was the species observed in the mass spectrum of the equilibrium vapour phase over the samples (71.5 at% Sn and 73.0 at% Sn). The partial pressure of Sn(g) was measured as a function of temperature over (USn3+U3Sn7) ;two-phase; field and the p-T relation was derived as log (pSn/Pa) = ((-14580 ± 91)/(T/K)) + (8.82 ± 0.08) (1050-1226 K). The vaporisation reaction 3USn3(s) = U3Sn7(s) + 2Sn(g) was evaluated by second law method. The Gibbs energy of formation of USn3(s) was derived as ΔfGm°(U Sn3 , s , T) (±1.8) = -173.4 + 0.055 T (K) (kJ mol-1) (1050-1226 K). The mass spectrometric studies on this system have been carried out for the first time.

  2. Coupling two-phase fluid flow with two-phase darcy flow in anisotropic porous media

    KAUST Repository

    Chen, J.

    2014-06-03

    This paper reports a numerical study of coupling two-phase fluid flow in a free fluid region with two-phase Darcy flow in a homogeneous and anisotropic porous medium region. The model consists of coupled Cahn-Hilliard and Navier-Stokes equations in the free fluid region and the two-phase Darcy law in the anisotropic porous medium region. A Robin-Robin domain decomposition method is used for the coupled Navier-Stokes and Darcy system with the generalized Beavers-Joseph-Saffman condition on the interface between the free flow and the porous media regions. Obtained results have shown the anisotropic properties effect on the velocity and pressure of the two-phase flow. 2014 Jie Chen et al.

  3. Relationships of a growing magnetic flux region to flares

    NARCIS (Netherlands)

    Schadee, A.; Martin, S.F.; Bentley, R.D.; Antalova, A.; Kucera, A.; Dezs, L.; Gesztelyi, L.; Harvey, K.L.; Jones, H.; Livi, S.H.B.; Wang, J.

    1984-01-01

    Some sites for solar flares are known to develop where new magnetic flux emerges and becomes abutted against opposite polarity pre-existing magnetic flux (review by Galzauskas/1/). We have identified and analyzed the evolution of such flare sites at the boundaries of a major new and growing magnetic

  4. Regional and seasonal analyses of weights in growing Angus cattle.

    Science.gov (United States)

    Bradford, H L; Fragomeni, B O; Bertrand, J K; Lourenco, D A L; Misztal, I

    2016-10-01

    This study evaluated the impact of region and season on growth in Angus seed stock. To assess geographic differences, the United States was partitioned into 9 regions based on similar climate and topography related to cow-calf production. Seasonal effects were associated with the month that animals were weighed. The American Angus Association provided growth data, and records were assigned to regions based on the owner's zip code. Most Angus cattle were in the Cornbelt, Lower Plains, Rocky Mountain, Upper Plains, and Upper South regions, with proportionally fewer Angus in Texas compared with the national cow herd. Most calves were born in the spring, especially February and March. Weaning weights (WW; = 49,886) and yearling weights (YW; = 45,168) were modeled with fixed effects of age-of-dam class (WW only), weigh month, region, month-region interaction, and linear covariate of age. Random effects included contemporary group nested within month-region combination and residual. The significant month-region interaction ( Angus seed stock producers have used calving seasons to adapt to the specific environmental conditions in their regions and to optimize growth in young animals.

  5. Stereo-Based Region-Growing using String Matching

    Science.gov (United States)

    Mandelbaum, Robert; Mintz, Max

    1995-01-01

    We present a novel stereo algorithm based on a coarse texture segmentation preprocessing phase. Matching is performed using a string comparison. Matching sub-strings correspond to matching sequences of textures. Inter-scanline clustering of matching sub-strings yields regions of matching texture. The shape of these regions yield information concerning object's height, width and azimuthal position relative to the camera pair. Hence, rather than the standard dense depth map, the output of this algorithm is a segmentation of objects in the scene. Such a format is useful for the integration of stereo with other sensor modalities on a mobile robotic platform. It is also useful for localization; the height and width of a detected object may be used for landmark recognition, while depth and relative azimuthal location determine pose. The algorithm does not rely on the monotonicity of order of image primitives. Occlusions, exposures, and foreshortening effects are not problematic. The algorithm can deal with certain types of transparencies. It is computationally efficient, and very amenable to parallel implementation. Further, the epipolar constraints may be relaxed to some small but significant degree. A version of the algorithm has been implemented and tested on various types of images. It performs best on random dot stereograms, on images with easily filtered backgrounds (as in synthetic images), and on real scenes with uncontrived backgrounds.

  6. Study on Eco-climate Type Regionalization of Wheat Growing Areas in Yunnan Province

    Institute of Scientific and Technical Information of China (English)

    Yongxin; LU; Limin; CAO; Zhongping; ZHANG; Hongbo; LI

    2013-01-01

    In order to provide an objective and scientific theoretical basis for rational distribution of wheat growth in Yunnan Province,according to the relationship between Yunnan weather conditions and wheat growth adaptability,a study on eco-climate type regionalization of wheat growing areas in Yunnan was conducted using principal component analysis and GIS technology. The results show that Yunnan Province could be divided into four types,namely southern warm and humid wheat growing area,central semi-arid wheat growing area,central semi-humid wheat growing area and north-central cold wheat growing area.

  7. Geographically Sourcing Cocaine's Origin - Delineation of the Nineteen Major Coca Growing Regions in South America.

    Science.gov (United States)

    Mallette, Jennifer R; Casale, John F; Jordan, James; Morello, David R; Beyer, Paul M

    2016-03-23

    Previously, geo-sourcing to five major coca growing regions within South America was accomplished. However, the expansion of coca cultivation throughout South America made sub-regional origin determinations increasingly difficult. The former methodology was recently enhanced with additional stable isotope analyses ((2)H and (18)O) to fully characterize cocaine due to the varying environmental conditions in which the coca was grown. An improved data analysis method was implemented with the combination of machine learning and multivariate statistical analysis methods to provide further partitioning between growing regions. Here, we show how the combination of trace cocaine alkaloids, stable isotopes, and multivariate statistical analyses can be used to classify illicit cocaine as originating from one of 19 growing regions within South America. The data obtained through this approach can be used to describe current coca cultivation and production trends, highlight trafficking routes, as well as identify new coca growing regions.

  8. A modified region growing algorithm for multi-colored image object segmentation

    Institute of Scientific and Technical Information of China (English)

    Yuxi Chen; Chongzhao Han

    2007-01-01

    A hybrid algorithm based on seeded region growing and k-means clustering was proposed to improve image object segmentation result. A user friendly segmentation tool was provided for the definition of objects,then k-means algorithm was utilized to cluster the selected points into k seeds-clusters, finally the seeded region growing algorithm was used for object segmentation. Experimental results show that the proposed method is suitable for segmentation of multi-colored object, while conventional seeded region growing methods can only segment uniform-colored object.

  9. Recursive Hierarchical Image Segmentation by Region Growing and Constrained Spectral Clustering

    Science.gov (United States)

    Tilton, James C.

    2002-01-01

    This paper describes an algorithm for hierarchical image segmentation (referred to as HSEG) and its recursive formulation (referred to as RHSEG). The HSEG algorithm is a hybrid of region growing and constrained spectral clustering that produces a hierarchical set of image segmentations based on detected convergence points. In the main, HSEG employs the hierarchical stepwise optimization (HS WO) approach to region growing, which seeks to produce segmentations that are more optimized than those produced by more classic approaches to region growing. In addition, HSEG optionally interjects between HSWO region growing iterations merges between spatially non-adjacent regions (i.e., spectrally based merging or clustering) constrained by a threshold derived from the previous HSWO region growing iteration. While the addition of constrained spectral clustering improves the segmentation results, especially for larger images, it also significantly increases HSEG's computational requirements. To counteract this, a computationally efficient recursive, divide-and-conquer, implementation of HSEG (RHSEG) has been devised and is described herein. Included in this description is special code that is required to avoid processing artifacts caused by RHSEG s recursive subdivision of the image data. Implementations for single processor and for multiple processor computer systems are described. Results with Landsat TM data are included comparing HSEG with classic region growing. Finally, an application to image information mining and knowledge discovery is discussed.

  10. New Region Growing based on Thresholding Technique Applied to MRI Data

    Directory of Open Access Journals (Sweden)

    A. Afifi

    2015-06-01

    Full Text Available This paper proposes an optimal region growing threshold for the segmentation of magnetic resonance images (MRIs. The proposed algorithm combines local search procedure with thresholding region growing to achieve better generic seeds and optimal thresholds for region growing method. A procedure is used to detect the best possible seeds from a set of data distributed all over the image as a high accumulator of the histogram. The output seeds are fed to the local search algorithm to extract the best seeds around initial seeds. Optimal thresholds are used to overcome the limitations of region growing algorithm and to select the pixels sequentially in a random walk starting at the seed point. The proposed algorithm works automatically without any predefined parameters. The proposed algorithm is applied to the challenging application "gray matter/white matter" segmentation datasets. The experimental results compared with other segmentation techniques show that the proposed algorithm produces more accurate and stable results.

  11. Medicinal plants growing in the Judea region: network approach for searching potential therapeutic targets

    Directory of Open Access Journals (Sweden)

    Arie Budovsky

    2012-09-01

    Full Text Available Plants growing in the Judea region are widely used in traditional medicine of the Levant region. Nevertheless, they have not so far been sufficiently analyzed and their medicinal potential has not been evaluated. This study is the first attempt to fill the gap in the knowledge of the plants growing in the region. Comprehensive data mining of online botanical databases and peer-reviewed scientific literature including ethno-pharmacological surveys from the Levant region was applied to compile a full list of plants growing in the Judea region, with the focus on their medicinal applications. Around 1300 plants growing in the Judea region were identified. Of them, 25% have medicinal applications which were analyzed in this study. Screening for chemical-protein interactions, together with the network-based analysis of potential targets, will facilitate discovery and therapeutic applications of the Judea region plants. Such an approach could also be applied as an integrative platform for further searching the potential therapeutic targets of plants growing in other regions of the world.

  12. Lengthening of the growing season in wheat and maize producing regions

    Directory of Open Access Journals (Sweden)

    Brigitte Mueller

    2015-09-01

    Full Text Available Human-induced increases in atmospheric greenhouse gas concentrations have led to rising global temperatures. Here we investigate changes in an annual temperature-based index, the growing season length, defined as the number of days with temperature above 5 °C. We show that over extratropical regions where wheat and maize are harvested, the increase in growing season length from 1956 to 2005 can be attributed to increasing greenhouse gas concentrations. Our analyses also show that climate change has increased the probability of extremely long growing seasons by a factor of 25, and decreased the probability of extremely short growing seasons. A lengthening of the growing season in regions with these mostly rain-fed crops could improve yields, provided that water availability does not become an issue. An expansion of areas with more than 150 days of growing season into the northern latitudes makes more land potentially available for planting wheat and maize. Furthermore, double-cropping can become an alternative to current practices in areas with very long growing seasons which are also shown to increase with a warming climate. These results suggest that there is a strong impact of anthropogenic climate change on growing season length. However, in some regions and with further exacerbated climate change, high temperatures may already be or may become a limiting factor for plant productivity.

  13. Location algorithm for seal imprints on Chinese bank-checks based on region growing

    Institute of Scientific and Technical Information of China (English)

    CHEN Li-jiang; LIU Tie-gen; CHEN Jia-jia; ZHU Jun-chao; DENG Ji-jie; MA She-xiang

    2006-01-01

    The paper focuses on location of seal imprints on Chinese bank-checks based on region growing.Region growing method can be applied to searching and locating connection region in an image.A seal imprint,however,is generally composed of various connection regions which are unconnected to each other.In order to locate the seal imprint,these connection regions must be fused together.In the paper,an algorithm for locating seal imprints on Chinese bankchecks based on region growing is proposed, of which a fusion criterion for connection regions in a seal imprint is put forth based on the image feature of Chinese bankcheck,and a center-rays model is proposed to find the topological relationship between connection regions,for which externally-tangent rectangle of region is used as the mark of location of region.The location experiment is achieved with a false-acceptance rate of 7.1% and a false-rejection rate of 0% on Chinese bankcheck.

  14. Two-phase viscoelastic jetting

    Energy Technology Data Exchange (ETDEWEB)

    Yu, J-D; Sakai, S.; Sethian, J.A.

    2008-12-10

    A coupled finite difference algorithm on rectangular grids is developed for viscoelastic ink ejection simulations. The ink is modeled by the Oldroyd-B viscoelastic fluid model. The coupled algorithm seamlessly incorporates several things: (1) a coupled level set-projection method for incompressible immiscible two-phase fluid flows; (2) a higher-order Godunov type algorithm for the convection terms in the momentum and level set equations; (3) a simple first-order upwind algorithm for the convection term in the viscoelastic stress equations; (4) central difference approximations for viscosity, surface tension, and upper-convected derivative terms; and (5) an equivalent circuit model to calculate the inflow pressure (or flow rate) from dynamic voltage.

  15. Projections of Suitable Wine Growing Regions and Varieties: Adaptation in Space or Place?

    Science.gov (United States)

    Forrestel, E. J.; Cook, B.; Garcia de Cortazar-Atauri, I.; Nicholas, K. A.; Parker, A.; van Leeuwen, C.; Wolkovich, E. M.

    2015-12-01

    Winegrapes (Vitis vinifera L) are the most valuable horticultural crop in the world with nearly eight million hectares of vineyards in cultivation. Different varieties of winegrapes (e.g., Grenache or Syrah) exhibit an unprecedented amount of phenological and genetic diversity for a cultivated species, which is an important resource to buffer against climate change. Matching phenological strategies of the different winegrape varieties to a particular climate is a fundamental aim for every vineyard manager, especially in the face of significant climatic shifts in many winegrape growing regions. Yet current projections of suitable winegrape growing regions based on future climate scenarios are limited in their utility, as they do not consider the possibility that other varieties better suited to a future climate could be planted within an existing region. For our projections, we built phenological models for the nine most-planted winegrapes globally, which constitutes over 40% of all planted hectares, using a global dataset of budburst, flowering, veraison and maturity. These models were then used to characterize the growing range of 1300 globally planted winegrape varieties. Combing these models with climate projection models under RCP 4.5 and 8.5 emission scenarios we examined future distributions of suitable wine growing regions, as well as the turnover of suitable varieties within existing regions. In some regions of the world, predicted climate change will not significantly alter the varieties that are able to grow, while in others there will need to be shifts in the region itself or in the varieties that are currently planted. Some regions will also see a significant increase in the number and diversity of varieties that can be grown. Our results suggest the need to utilize the full range of winegrape diversity available when considering adaptive strategies in response to changing climates.

  16. Design and experiment of household biogas system in alpine region based on two-phase anaerobic fermentation%高寒地区两相厌氧户用沼气系统设计与试验

    Institute of Scientific and Technical Information of China (English)

    孙勇; 李文哲; 张鸿琼

    2012-01-01

    摘要;针对高寒地区农村户用沼气发酵周期过长、产气量少的状况,该文提出并设计了适用于高寒地区农村户用的两相厌氧发酵装置,通过确立合理的工艺方案,控制两相厌氧发酵中产酸相、料液温度和pH值、水力滞留时间等因素,探讨了在哈尔滨地区最寒冷季节,所设计的新型农村户用沼气发酵装置产气量与维持发酵罐体内料液温度所消耗沼气量之间的关系.结果表明:基于两相厌氧发酵的高寒地区高效户用沼气发酵装置最高产气率为1.35m3/(m3·d),是传统沼气池产气率( 0.35 m3/(m3·d))的4倍.冬季1月份日均结余4.08 m3沼气量足以满足三口之家照明、炊事所需能源,实现高寒地区户用沼气全年正能输出,可以取代传统沼气池.该文研究成果为今后寒地户用沼气的发展提供技术支持和参考依据.%According to the problems of long fermentation period and low gas production in the alpine region, a two-phase anaerobic fermentation device was designed for rural household biogas production in the alpine region. The fermentation parameters such as acid production, temperature and pH value of feed and hydraulic retention time were controlled during two-phase anaerobic fermentation. The relationship between the quantity of produced biogas during fermentation and the quantity of consumed biogas to maintain the biogas slurry temperature in most cold season in Harbin was discussed. Results showed that the highest methan production was 1.35 m3/(m3d) using the two-phase anaerobic fermentation process, which was four times higher than the traditional process of 0.35 m3/(m3-d). There was 4.08 m3 daily balance biogas to satisfy lighting and cooking for three people family in January of winter, which could operate in alpine region year-round. In addition, the equipment structure is reasonable and perfect, which might replace the traditional digester. The research can provide a technical support

  17. Landscape planning for agridevelopment at regional scale: an example from cotton growing Yavatmal district, Maharashtra, India

    Directory of Open Access Journals (Sweden)

    Bhaskara Phaneendra Bhaskar

    2015-12-01

    Full Text Available The basaltic landscape planning on the hot semiarid ecosystem in cotton growing Yavatmal district, Maharashtra tends to concentrate on 52 per cent of total cultivated area with 43 per cent of rural families living below poverty line posing major problem for environmental protection and resource management. Concepts of sustainable development at regional-level planning suggested that there is a growing concern for the landscape community to develop a strategic regional agricultural planning perspective in order to assist landscape planning goals. These challenges were explored with particular reference to the cotton growing Yavatmal district in Maharashtra through baseline land resource / agronomic surveys and assessing the production potential of regional rural landscapes for crop planning. Landscape analysis, premised on the geopedological and elevation constructs, culminated in a spatial coverage of hills and ridges (12.6 per cent of total area in northern and central parts whereas plateaus (29.3 per cent in association with isolated hills, mesas and butte and escarpments (17.7 per cent, pediplains (28.8 per cent and plains (8.1 per cent in south western parts of the district. Regional level analysis revealed spatially variable soil typologies dominated by vertisols and vertic intergrades. An exploration and brief account of integration landscape planning was discussed with some reflections on the experience and highlighting some of the problems and potentials of this approach within the regional context.

  18. A Study on the Application of Fuzzy Information Seeded Region Growing in Brain MRI Tissue Segmentation

    Directory of Open Access Journals (Sweden)

    Chuin-Mu Wang

    2014-01-01

    Full Text Available After long-term clinical trials, MRI has been proven to be used in humans harmlessly, and it is popularly used in medical diagnosis. Although MR is highly sensitive, it provides abundant organization information. Therefore, how to transform the multi-spectral images which is easier to be used for doctor’s clinical diagnosis. In this thesis, the fuzzy bidirectional edge detection method is used to solve conventional SRG problem of growing order in the initial seed stages. In order to overcome the problems of the different regions, although it is the same Euclidean distance for region growing and merging process stages, we present the peak detection method to improve them. The standard deviation target generation process (SDTGP is applied to guarantee the regions merging process does not cause over- or undersegmentation. Experimental results reveal that FISRG segments a multispectral MR image much more effectively than FAST and K-means.

  19. Automated Segmentation of Coronary Arteries Based on Statistical Region Growing and Heuristic Decision Method

    Directory of Open Access Journals (Sweden)

    Yun Tian

    2016-01-01

    Full Text Available The segmentation of coronary arteries is a vital process that helps cardiovascular radiologists detect and quantify stenosis. In this paper, we propose a fully automated coronary artery segmentation from cardiac data volume. The method is built on a statistics region growing together with a heuristic decision. First, the heart region is extracted using a multi-atlas-based approach. Second, the vessel structures are enhanced via a 3D multiscale line filter. Next, seed points are detected automatically through a threshold preprocessing and a subsequent morphological operation. Based on the set of detected seed points, a statistics-based region growing is applied. Finally, results are obtained by setting conservative parameters. A heuristic decision method is then used to obtain the desired result automatically because parameters in region growing vary in different patients, and the segmentation requires full automation. The experiments are carried out on a dataset that includes eight-patient multivendor cardiac computed tomography angiography (CTA volume data. The DICE similarity index, mean distance, and Hausdorff distance metrics are employed to compare the proposed algorithm with two state-of-the-art methods. Experimental results indicate that the proposed algorithm is capable of performing complete, robust, and accurate extraction of coronary arteries.

  20. Landscape character assessment using region growing techniques in geographical information systems.

    Science.gov (United States)

    Jellema, André; Stobbelaar, Derk-Jan; Groot, Jeroen C J; Rossing, Walter A H

    2009-05-01

    Landscape character can be defined as the presence, variety and arrangement of landscape features, which give a landscape a specific identity and make it stand out from surrounding landscapes. Landscape character contributes to the esthetical and perceptional value of an area, which is important for the development of non-production functions in the countryside as demanded by society. In this paper we present a new methodology for landscape character assessment using the pattern of landscape features as stored in a GIS to delineate, characterize and evaluate landscapes using a region growing algorithm. We have applied this methodology in a case study area in the north of The Netherlands and compared the results with a series of expert classifications of the study area. The results of the region growing algorithms were good and interpretable in relation to the underlying data. The resemblance between the expert classification and the classification based on the region growing results varied between 34% and 100% for the different landscape types. The differences between the two data sets can be explained in terms of input data and knowledge about the study area. The classification of the region growing algorithm was more consistent than the expert classification throughout the study area. The presented methodology for landscape character assessment is proposed as support for spatial planning processes and policy development for landscape conservation by providing a quantitative tool to analyze landscape patterns, to discriminate between the various landscapes in a study area and by elucidating features that are important for the identity of a region.

  1. Intravenous drug abuse and tricuspid valve endocarditis: Growing trends in the Middle East Gulf region.

    Science.gov (United States)

    Panduranga, Prashanth; Al-Abri, Seif; Al-Lawati, Jawad

    2013-11-26

    Traditionally, tricuspid valve endocarditis is uncommon in the Middle East region. However, recent global data indicate growing trends in the use of illicit drug abuse, specifically injectable heroin, in the Middle East Gulf region. The presence of many transit port services in the Middle East Gulf States has led to smuggling of substance abuse drugs in the region. The Middle East Gulf States, currently a transit market, are also becoming a growing consumer market in view of the increased substance abuse in the youth. However, there is a paucity of data with respect to the prevalence or incidence of tricuspid valve endocarditis in the region, probably due to underdiagnosis or underreporting. A high index of suspicion of tricuspid valve endocarditis is essential in patients with a history of intravenous drug abuse. This article reviews the epidemiology of illicit drug abuse in the Middle East Gulf region, as well as the diagnosis and treatment of tricuspid valve endocarditis, and calls for all physicians in the region to be vigilant while dealing with intravenous drug abuse.

  2. Seeded Region Growing pada Ruang Warna HSI untuk Segmentasi Citra Ikan Tuna

    Directory of Open Access Journals (Sweden)

    Wanvy Arifha Saputra

    2017-02-01

    Full Text Available Citra ikan tuna sebelum masuk tahapan klasifikasi, harus memiliki hasil segmentasi yang baik. Hasil segmentasi yang baik adalah objek dan background terpisah dengan jelas. Citra ikan tuna yang memiliki sebaran cahaya yang tidak merata dan memiliki tekstur yang kompleks akan menghasilkan kesalahan segmentasi. Salah satu metode segmentasi pada citra adalah seeded region growing dan parameter yang digunakan hanya dua yaitu seed dan threshold. Penelitian ini mengusulkan metode seeded region growing pada ruang warna HSI untuk segmentasi citra ikan tuna. Ruang warna RGB (red green blue pada citra ikan tuna ditransformasikan kedalam ruang warna HSI (hue saturasi intesitas yang kemudian hanya ruang hue untuk dijadikan segmentasi dengan menggunakan seeded region growing. Penentuan parameter seed dan threshold dilakukan secara manual dan hasil dari segmentasi tersebut dilakukan refinement dengan morfologi matematika. Pengujian dilakukan sebanyak 30 citra dan metode evaluasi hasil segmentasi menggunakan RAE (relative foreground area error, MAE (missclassification error dan MHD (modified Hausdroff distance. Citra ikan tuna berhasil dilakukan segmentasi dengan dibuktikan nilai RAE, ME dan MHD secara berturut adalah 5,40%, 1,53% dan 0,41%.

  3. Robust protein microarray image segmentation using improved seeded region growing algorithm

    Institute of Scientific and Technical Information of China (English)

    Liqiang Wang(王立强); Xuxiang Ni(倪旭翔); Zukang Lu(陆祖康)

    2003-01-01

    Protein microarray technology has recently emerged as a powerful tool for biomedical research. Before automatic analysis the protein microarray images, protein spots in the images must be determined appropriately by spot segmentation algorithm. In this paper, an improved seeded region growing (ISRG)algorithm for protein microarray segmentation is presented, the seeds are obtained by finding the positions of the printed spots, and the protein spot regions are grown through these seeds. The experiment results show that the presented algorithm is accurate for adaptive shape segmentation and robust for protein microarray images contaminated by noise.

  4. Two Phase Technology Development Initiatives

    Science.gov (United States)

    Didion, Jeffrey R.

    1999-01-01

    Three promising thermal technology development initiatives, vapor compression thermal control system, electronics cooling, and electrohydrodynamics applications are outlined herein. These technologies will provide thermal engineers with additional tools to meet the thermal challenges presented by increased power densities and reduced architectural options that will be available in future spacecraft. Goddard Space Flight Center and the University of Maryland are fabricating and testing a 'proto- flight' vapor compression based thermal control system for the Ultra Long Duration Balloon (ULDB) Program. The vapor compression system will be capable of transporting approximately 400 W of heat while providing a temperature lift of 60C. The system is constructed of 'commercial off-the-shelf' hardware that is modified to meet the unique environmental requirements of the ULDB. A demonstration flight is planned for 1999 or early 2000. Goddard Space Flight Center has embarked upon a multi-discipline effort to address a number of design issues regarding spacecraft electronics. The program addressed the high priority design issues concerning the total mass of standard spacecraft electronics enclosures and the impact of design changes on thermal performance. This presentation reviews the pertinent results of the Lightweight Electronics Enclosure Program. Electronics cooling is a growing challenge to thermal engineers due to increasing power densities and spacecraft architecture. The space-flight qualification program and preliminary results of thermal performance tests of copper-water heat pipes are presented. Electrohydrodynamics (EHD) is an emerging technology that uses the secondary forces that result from the application of an electric field to a flowing fluid to enhance heat transfer and manage fluid flow. A brief review of current EHD capabilities regarding heat transfer enhancement of commercial heat exchangers and capillary pumped loops is presented. Goddard Space Flight

  5. The Sabethines of Northern Andean Coffee-Growing Regions of Colombia.

    Science.gov (United States)

    Suaza-Vasco, Juan; López-Rubio, Andrés; Galeano, Juan; Uribe, Sandra; Vélez, Iván; Porter, Charles

    2015-06-01

    Sampling for sabethine mosquitoes occurred intermittently from September 2007 to April 2013 in 17 municipalities, located in 5 departments (divisions) in the northern Andean coffee-growing regions of Colombia. Of the 9 genera within the Sabethini tribe known to occur in the Neotropical region, 6 were encountered including 15 species: Jonhbelkinia ulopus, Limatus durhamii, Sabethes ignotus, Sa. luxodens, Sa. undosus, Shannoniana fluviatilis, Trichoprosopon compressum, Tr. digitatum, Tr. evansae, Tr. pallidiventer s.l., Tr. pallidiventer s.s., Wyeomyia arthrostigma, Wy. oblita, Wy. ulocoma, and Wy. undulata. The species Sa. luxodens and Wy. undulata constitute new records for Colombia. These records broaden the knowledge of this important group that includes some important species related to the arbovirus transmission. Records are from the northern Colombian Andes, a region noted for coffee cultivation and ecotourism.

  6. Segmentation of Extrapulmonary Tuberculosis Infection Using Modified Automatic Seeded Region Growing

    Directory of Open Access Journals (Sweden)

    Nordin Abdul

    2009-01-01

    Full Text Available Abstract In the image segmentation process of positron emission tomography combined with computed tomography (PET/CT imaging, previous works used information in CT only for segmenting the image without utilizing the information that can be provided by PET. This paper proposes to utilize the hot spot values in PET to guide the segmentation in CT, in automatic image segmentation using seeded region growing (SRG technique. This automatic segmentation routine can be used as part of automatic diagnostic tools. In addition to the original initial seed selection using hot spot values in PET, this paper also introduces a new SRG growing criterion, the sliding windows. Fourteen images of patients having extrapulmonary tuberculosis have been examined using the above-mentioned method. To evaluate the performance of the modified SRG, three fidelity criteria are measured: percentage of under-segmentation area, percentage of over-segmentation area, and average time consumption. In terms of the under-segmentation percentage, SRG with average of the region growing criterion shows the least error percentage (51.85%. Meanwhile, SRG with local averaging and variance yielded the best results (2.67% for the over-segmentation percentage. In terms of the time complexity, the modified SRG with local averaging and variance growing criterion shows the best performance with 5.273 s average execution time. The results indicate that the proposed methods yield fairly good performance in terms of the over- and under-segmentation area. The results also demonstrated that the hot spot values in PET can be used to guide the automatic segmentation in CT image.

  7. Where is my wine from? - A global exposure database for wineries and wine growing regions

    Science.gov (United States)

    Daniell, James E.; Daniell, Trevor M.; Wenzel, Friedemann; Schaefer, Andreas M.; Daniell, Katherine A.; Burford, Robert

    2017-04-01

    The production of a global winery and wine database is a great undertaking and was required for the evaluation of winery risk in various locations (see NH ECS Lecture MH42/NH). The following study detailed a country wide study of wineries in 15 major wine growing locations globally in order to evaluate the ability of using existing information to detail the risk properties of the wine growing regions. In addition parameters such as the winery types, grape types, slopes, buildings, hazard properties and land use were surveyed. In terms of the winery locations, point-based as well as spatial land-use disaggregated polygons were used. For grape production, national and winery region data was aggregated from existing sources in each country. The value and type were assessed. For the slopes, global and regional DEMs such as ALOS, SRTM and EU-DEM were examined and converted within GIS envrionments. Building level information was often difficult to establish where OSM data was lacking (OpenStreetMap). Hazard parameters such as earthquake ground motion probability, weather, wind speeds, changing grape types, seasonality as well as the variability within seasons were collected with the variability being key to showing an increase or decrease in quality. Tools that were used can be applied to other exposure datasets; and shows a methodology to aggregate exposure information with respect to industries as well as other sectors using open data.

  8. The growing challenges of vector-borne diseases to regionally-aligned forces.

    Science.gov (United States)

    Robert, Leon L; Debboun, Mustapha

    2014-01-01

    The long-term strategic focus of US foreign policy has pivoted to the Pacific, but tensions in the Middle East require constant attention in the present. As our current role in Afghanistan diminishes, we must seize the opportunity to refocus on the new priority of regionally-aligned forces. The short-term reality requires first reestablishing core warfighting competencies of a smaller Army and then building the capacity of forces focused on regional alignment. The continuing threat of vector-borne and other infectious diseases will present growing challenges to US forces focused on regional alignment and engagement. Greater understanding of these threats, host nation vulnerabilities and capabilities, and the regional presence of international and nongovernmental organizations will enable US forces to respond and engage more effectively and appropriately to accomplish assigned missions and future contingencies. Effective vector surveillance and control has a longstanding and proven record of preventing, reducing, and eliminating vector-borne diseases and must remain a focus of regionally-aligned forces. Operational readiness of armed forces continues to rely heavily on vector surveillance and control, and on personal protection strategies. Regionally-aligned forces must also work closely with the US Department of State and US Agency for International Development, international governments, governmental and nongovernmental organizations, and private organizations operating in the region and know how to effectively interact with these diverse organizations. In addition, a working knowledge of a host country's public health policy, capabilities and economic realities will be essential. Teamwork with previously unfamiliar groups and organizations will be an essential component of working in regional environments and can present unfamiliar tasks for traditionally-trained military units.

  9. A region growing technique adapted to precise micro calcification characterization in mammography

    Energy Technology Data Exchange (ETDEWEB)

    Darboux, M.; Dinten, J.M.; Nicolas, E.

    1996-12-31

    To-day, mammography is the only breast screening technique capable of detecting breast cancer at a very early stage. The presence of a breast tumor is indicated by some features on the mammogram. One sign of malignancy is the presence of clusters of fine, granular micro-calcifications. We present here a new three-step method for detecting and characterizing these micro-calcifications. We design with the detection of potential candidates (`seeds`). The aim of this first step is to detect all the pixels be a micro-calcification. Then we focus on our specific region growing technique which provides an accurate extraction of the shape of the region corresponding to each detected seed. This second step is essential because micro-calcifications shape is a very important feature for the diagnosis. It is then possible to determine precise parameters to characterize these micro-calcifications. (authors). 4 refs.

  10. Attenuation correction with Region Growing Method used in the Positron Emission Mammography System

    CERN Document Server

    Gu, Xiao-Yue; Yin, Peng-Fei; Yun, Ming-Kai; Pei, Chai; Fan, Xin; Huang, Xian-Chao; Sun, Xiao-Li; Wei, Long

    2014-01-01

    Positron Emission Mammography imaging system (PEMi) is a nuclear medicine diagnosis method dedicated for breast imaging. It provides a better resolution in detection of millimeter-sized breast tumors than whole-body PET. To address the requirement of semi-quantitative analysis with the radiotracer concentration map of the breast, a new attenuation correction method based on three-dimensional seeded region growing image segmentation (3DSRG-AC) solution was developed. The method gives a 3D connected region as the segmentation result instead of image slices. The continuously segmentation property makes this new method free of activity variation of breast tissues. Threshold value chosen is the key point for the segmentation process. The first valley of the grey level histogram of the reconstruction image is set as the lower threshold, which works fine in clinical application. Results show that attenuation correction for PEMi improves the image quality and the quantitative accuracy of radioactivity distribution de...

  11. CAMSHIFT IMPROVEMENT WITH MEAN-SHIFT SEGMENTATION, REGION GROWING, AND SURF METHOD

    Directory of Open Access Journals (Sweden)

    Ferdinan Ferdinan

    2013-10-01

    Full Text Available CAMSHIFT algorithm has been widely used in object tracking. CAMSHIFT utilizescolor features as the model object. Thus, original CAMSHIFT may fail when the object color issimilar with the background color. In this study, we propose CAMSHIFT tracker combined withmean-shift segmentation, region growing, and SURF in order to improve the tracking accuracy.The mean-shift segmentation and region growing are applied in object localization phase to extractthe important parts of the object. Hue-distance, saturation, and value are used to calculate theBhattacharyya distance to judge whether the tracked object is lost. Once the object is judged lost,SURF is used to find the lost object, and CAMSHIFT can retrack the object. The Object trackingsystem is built with OpenCV. Some measurements of accuracy have done using frame-basedmetrics. We use datasets BoBoT (Bonn Benchmark on Tracking to measure accuracy of thesystem. The results demonstrate that CAMSHIFT combined with mean-shift segmentation, regiongrowing, and SURF method has higher accuracy than the previous methods.

  12. A new seeded region growing technique for retinal blood vessels extraction.

    Science.gov (United States)

    Sajadi, Atefeh Sadat; Sabzpoushan, Seyed Hojat

    2014-07-01

    Distribution of retinal blood vessels (RBVs) in retinal images has an important role in the prevention, diagnosis, monitoring and treatment of diseases, such as diabetes, high blood pressure, or heart disease. Therefore, detection of the exact location of RBVs is very important for Ophthalmologists. One of the frequently used techniques for extraction of these vessels is region growing-based Segmentation. In this paper, we propose a new region growing (RG) technique for RBVs extraction, called cellular automata-based segmentation. RG techniques often require manually seed point selection, that is, human intervention. However, due to the complex structure of vessels in retinal images, manual tracking of them is very difficult. Therefore, to make our proposed technique full automatic, we use an automatic seed point selection method. The proposed RG technique was tested on Digital Retinal Images for Vessel Extraction database for three different initial seed sets and evaluated against the manual segmentation of retinal images available at this database. Three quantitative criteria including accuracy, true positive rate and false positive rate, were considered to evaluate this method. The visual scrutiny of the segmentation results and the quantitative criteria show that, using cellular automata for extracting the blood vessels is promising. However, the important point at here is that the correct initial seeds have an effective role on the final results of segmentation.

  13. Two-phase flow in refrigeration systems

    CERN Document Server

    Gu, Junjie; Gan, Zhongxue

    2013-01-01

    Two-Phase Flow in Refrigeration Systems presents recent developments from the authors' extensive research programs on two-phase flow in refrigeration systems. This book covers advanced mass and heat transfer and vapor compression refrigeration systems and shows how the performance of an automotive air-conditioning system is affected through results obtained experimentally and theoretically, specifically with consideration of two-phase flow and oil concentration. The book is ideal for university postgraduate students as a textbook, researchers and professors as an academic reference book, and b

  14. Geographically Sourcing Cocaine’s Origin – Delineation of the Nineteen Major Coca Growing Regions in South America

    Science.gov (United States)

    Mallette, Jennifer R.; Casale, John F.; Jordan, James; Morello, David R.; Beyer, Paul M.

    2016-01-01

    Previously, geo-sourcing to five major coca growing regions within South America was accomplished. However, the expansion of coca cultivation throughout South America made sub-regional origin determinations increasingly difficult. The former methodology was recently enhanced with additional stable isotope analyses (2H and 18O) to fully characterize cocaine due to the varying environmental conditions in which the coca was grown. An improved data analysis method was implemented with the combination of machine learning and multivariate statistical analysis methods to provide further partitioning between growing regions. Here, we show how the combination of trace cocaine alkaloids, stable isotopes, and multivariate statistical analyses can be used to classify illicit cocaine as originating from one of 19 growing regions within South America. The data obtained through this approach can be used to describe current coca cultivation and production trends, highlight trafficking routes, as well as identify new coca growing regions. PMID:27006288

  15. Two-phase flow studies. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kestin, J.; Maeder, P.F.

    1980-08-01

    Progress on the following is reported: literature survey, design of two-phase flow testing facility, design of nozzle loop, thermophysical properties, design manual, and advanced energy conversion systems. (MHR)

  16. GROWING REGIONAL SCIENTIFIC MIGRATION AND MOBILITY: THE EUROPEAN UNION AND THE EASTERN PARTNERSHIP

    Directory of Open Access Journals (Sweden)

    Ganna KHARLAMOVA

    2016-11-01

    Full Text Available The article contributes to the growing strand of the literature on the scientific mobility and migration in the European Union (EU and the Eastern Partnership. The paper provides the quantitative assessment of the costs and benefits of ‘smart’ labour migration in the Eastern Partnership (EaP countries (particularly, Ukraine, explores the potential of future new rules for the mobility within the EU-EaP, and proposes some policy recommendations to enhance the benefits stemming from such flows. One of the rigorous idea – to provide an explanation whether the scientific migration and mobility, and remittances impact on economic development in the donor and recipient states, and, in particular, how important it is as a resource for the EaP enhancing. The convergence effect of scientific migration in the EU and the Eastern Partnership region is considered by means of calculative assessment.

  17. The mechanical properties of Acer velutinum var. glabrescens wood growing in different regions of Caspian forests

    Directory of Open Access Journals (Sweden)

    fardad golbabaei

    2016-06-01

    Full Text Available The major engineering properties of Acer velutinum var. glabrescens wood growing in different regions of Caspian forests (North of Iran was determined. Test materials were selected randomly from Acer velutinum var. glabrescens tree plantation and the test specimens were prepared according to ASTM D-143 standard. Mechanical and physical properties were measured on both green and air-dried samples (12% moisture content. The results of the measurement were statistically analyzed based on randomized block design and factorial experiment. The influence of specimen locations at different stem heights was examined. Based on the results of this study, Significant areas of habitat in the area, Maple Vysr Mazandaran species most resistant of the Maple Sangdeh Frame has the lowest resistance. Keywords: Maple, statice bending, compression parallel to grain, compression perpendicular to grain, tension perpendicular to grain, Acer velutinum var. glabrescens.

  18. AN ADAPTIVE REGION GROWING ALGORITHM WITH SUPPORT VECTOR MACHINE CLASSIFIER FOR TUBERCULOSIS CAVITY IDENTIFICATION

    Directory of Open Access Journals (Sweden)

    K. Meenakshi Sundaram

    2013-01-01

    Full Text Available The major world health menace is Tuberculosis (TB that has the effect on one-third of the global population and millions of new infections are occurring every year. The cavities in the upper lung zone are a strong indicator that the disease has developed into a highly contagious state. The study includes 52 Chest X-ray images with Tuberculosis and 43 Chest X-ray images without Tuberculosis. The identification of the TB cavities is mostly conducted by the clinicians by observing the chest radiographs. But the automatic screening has lot of advantages such as substantial reduction in the labor workload of clinicians, enhancing the sensitivity of the test and better precision in diagnosis by increasing the number of images that can be analyzed by the computer. Many researchers have proposed different techniques to improve the performance of automatic screening process. This paper improves the accuracy over the existing technique using the adaptive region growing property and SVM classifier. Initially, pre-processing is carried out for the input image using Gaussian filtering technique to make the image suitable for further processing. The contours of the image will be obtained using region growing technique. The SVM classifier is then used to confirm the suspected TB cavities. The classification will be carried out by the features which the study has taken from the segmented image. The proposed technique is implemented in MATLAB and the performance is compared with the existing technique. From the result, the study has achieved eighty-five percentage accuracy over the existing technique’s seventy eight-percentage accuracy.

  19. Dynamic Modeling of Phase Crossings in Two-Phase Flow

    DEFF Research Database (Denmark)

    Madsen, Søren; Veje, Christian; Willatzen, Morten

    2012-01-01

    of the variables and are usually very slow to evaluate. To overcome these challenges, we use an interpolation scheme with local refinement. The simulations show that the method handles crossing of the saturation lines for both liquid to two-phase and two-phase to gas regions. Furthermore, a novel result obtained...... in this work, the method is stable towards dynamic transitions of the inlet/outlet boundaries across the saturation lines. Results for these cases are presented along with a numerical demonstration of conservation of mass under dynamically varying boundary conditions. Finally we present results...

  20. Velocity and energy relaxation in two-phase flows

    CERN Document Server

    Meyapin, Yannick; Gisclon, Marguerite

    2009-01-01

    In the present study we investigate analytically the process of velocity and energy relaxation in two-phase flows. We begin our exposition by considering the so-called six equations two-phase model [Ishii1975, Rovarch2006]. This model assumes each phase to possess its own velocity and energy variables. Despite recent advances, the six equations model remains computationally expensive for many practical applications. Moreover, its advection operator may be non-hyperbolic which poses additional theoretical difficulties to construct robust numerical schemes |Ghidaglia et al, 2001]. In order to simplify this system, we complete momentum and energy conservation equations by relaxation terms. When relaxation characteristic time tends to zero, velocities and energies are constrained to tend to common values for both phases. As a result, we obtain a simple two-phase model which was recently proposed for simulation of violent aerated flows [Dias et al, 2010]. The preservation of invariant regions and incompressible li...

  1. Automated lung tumor segmentation for whole body PET volume based on novel downhill region growing

    Science.gov (United States)

    Ballangan, Cherry; Wang, Xiuying; Eberl, Stefan; Fulham, Michael; Feng, Dagan

    2010-03-01

    We propose an automated lung tumor segmentation method for whole body PET images based on a novel downhill region growing (DRG) technique, which regards homogeneous tumor hotspots as 3D monotonically decreasing functions. The method has three major steps: thoracic slice extraction with K-means clustering of the slice features; hotspot segmentation with DRG; and decision tree analysis based hotspot classification. To overcome the common problem of leakage into adjacent hotspots in automated lung tumor segmentation, DRG employs the tumors' SUV monotonicity features. DRG also uses gradient magnitude of tumors' SUV to improve tumor boundary definition. We used 14 PET volumes from patients with primary NSCLC for validation. The thoracic region extraction step achieved good and consistent results for all patients despite marked differences in size and shape of the lungs and the presence of large tumors. The DRG technique was able to avoid the problem of leakage into adjacent hotspots and produced a volumetric overlap fraction of 0.61 +/- 0.13 which outperformed four other methods where the overlap fraction varied from 0.40 +/- 0.24 to 0.59 +/- 0.14. Of the 18 tumors in 14 NSCLC studies, 15 lesions were classified correctly, 2 were false negative and 15 were false positive.

  2. Viscosity Solutions for the two-phase Stefan Problem

    CERN Document Server

    Kim, Inwon C

    2010-01-01

    We introduce a notion of viscosity solutions for the two-phase Stefan problem, which incorporates possible existence of a mushy region generated by the initial data. We show that a comparison principle holds between viscosity solutions, and investigate the coincidence of the viscosity solutions and the weak solutions defined via integration by parts. In particular, in the absence of initial mushy region, viscosity solution is the unique weak solution with the same boundary data.

  3. Automatic segmentation of meningioma from non-contrasted brain MRI integrating fuzzy clustering and region growing

    Directory of Open Access Journals (Sweden)

    Liao Chun-Chih

    2011-08-01

    Full Text Available Abstract Background In recent years, magnetic resonance imaging (MRI has become important in brain tumor diagnosis. Using this modality, physicians can locate specific pathologies by analyzing differences in tissue character presented in different types of MR images. This paper uses an algorithm integrating fuzzy-c-mean (FCM and region growing techniques for automated tumor image segmentation from patients with menigioma. Only non-contrasted T1 and T2 -weighted MR images are included in the analysis. The study's aims are to correctly locate tumors in the images, and to detect those situated in the midline position of the brain. Methods The study used non-contrasted T1- and T2-weighted MR images from 29 patients with menigioma. After FCM clustering, 32 groups of images from each patient group were put through the region-growing procedure for pixels aggregation. Later, using knowledge-based information, the system selected tumor-containing images from these groups and merged them into one tumor image. An alternative semi-supervised method was added at this stage for comparison with the automatic method. Finally, the tumor image was optimized by a morphology operator. Results from automatic segmentation were compared to the "ground truth" (GT on a pixel level. Overall data were then evaluated using a quantified system. Results The quantified parameters, including the "percent match" (PM and "correlation ratio" (CR, suggested a high match between GT and the present study's system, as well as a fair level of correspondence. The results were compatible with those from other related studies. The system successfully detected all of the tumors situated at the midline of brain. Six cases failed in the automatic group. One also failed in the semi-supervised alternative. The remaining five cases presented noticeable edema inside the brain. In the 23 successful cases, the PM and CR values in the two groups were highly related. Conclusions Results indicated

  4. Study of two-phase flows in reduced gravity

    Science.gov (United States)

    Roy, Tirthankar

    have been done in the past to understand the global structure of gas-liquid two-phase flows under reduced gravity conditions, using experimental setups aboard drop towers or aircrafts flying parabolic flights, detailed data on local structure of such two-phase flows are extremely rare. Hence experiments were carried out in a 304 mm inner diameter (ID) test facility on earth. Keeping in mind the detailed experimental data base that needs to be generated to evaluate two-fluid model along with IATE, ground based simulations provide the only economic path. Here the reduced gravity condition is simulated using two-liquids of similar densities (water and Therminol 59 RTM in the present case). Only adiabatic two-phase flows were concentrated on at this initial stage. Such a large diameter test section was chosen to study the development of drops to their full extent (it is to be noted that under reduced gravity conditions the stable bubble size in gas-liquid two-phase flows is much larger than that at normal gravity conditions). Twelve flow conditions were chosen around predicted bubbly flow to cap-bubbly flow transition region. Detailed local data was obtained at ten radial locations for each of three axial locations using state-of-the art multi-sensor conductivity probes. The results are presented and discussed. Also one-group as well as two-group, steady state, one-dimensional IATE was evaluated against data obtained here and by other researchers, and the results presented and discussed.

  5. Automatic segmentation of canine retinal OCT using adaptive gradient enhancement and region growing

    Science.gov (United States)

    He, Yufan; Sun, Yankui; Chen, Min; Zheng, Yuanjie; Liu, Hui; Leon, Cecilia; Beltran, William; Gee, James C.

    2016-03-01

    In recent years, several studies have shown that the canine retina model offers important insight for our understanding of human retinal diseases. Several therapies developed to treat blindness in such models have already moved onto human clinical trials, with more currently under development [1]. Optical coherence tomography (OCT) offers a high resolution imaging modality for performing in-vivo analysis of the retinal layers. However, existing algorithms for automatically segmenting and analyzing such data have been mostly focused on the human retina. As a result, canine retinal images are often still being analyzed using manual segmentations, which is a slow and laborious task. In this work, we propose a method for automatically segmenting 5 boundaries in canine retinal OCT. The algorithm employs the position relationships between different boundaries to adaptively enhance the gradient map. A region growing algorithm is then used on the enhanced gradient maps to find the five boundaries separately. The automatic segmentation was compared against manual segmentations showing an average absolute error of 5.82 +/- 4.02 microns.

  6. Insects associated with tropical foliage produced in the coffee growing region of Colombia

    Directory of Open Access Journals (Sweden)

    Luis F. Aristizábal

    2013-09-01

    Full Text Available We conducted a survey of insects and pest management practices on 34 farms growing ornamental tropical foliage plants in the central coffee region of Colombia over two years. Tropical foliage provided habitat for a diverse range of insects. In total, phytophagous or detritivorous insects from six orders, 40 families and 62 genera were collected. The most common were Hemiptera (29 genera from 16 families, followed by Coleoptera (17 genera from 4 families, Diptera (5 genera from 5 families, Lepidoptera (5 genera from 4 families, Hymenoptera (3 genera from 2 families and Orthoptera (2 genera from 2 families. The most common phytophagous species were leaf cutting ants (Atta and Acromyrmex spp., leaf beetles (Chrysomelidae, leafhoppers (Cicadellidae, stinkbugs (Pentatomidae, squash bugs (Coreidae, tree hoppers (Membracidae and plant hoppers (Fulgoridae. Beneficial insects identified from tropical foliage included predators and parasitoids amongst 5 orders, 12 families and 22 genera. The most abundant were predators among the Coccinellidae, Chrysopidae, Reduviidae, Lycidae and Formicidae but only low numbers of parasitoids (Ichneumonidae, Braconidae and Tachinidae were collected. A pest management questionnaire given to growers revealed a preponderance of reliance on broad spectrum insecticides with a smaller number of growers (approximately one third also using some biological control methods. Our survey contributes basic information regarding diversity of Neotropical insects associated with ornamental foliage plants.

  7. [Inequalities in mortality by cardiovascular diseases in the Colombian Coffee Growing Region, 2009-2011].

    Science.gov (United States)

    Cardona, Dora; Cerezo, María Del Pilar; Parra, Hernán; Quintero, Liliana; Muñoz, Liliana; Cifuentes, Olga Lucía; Vélez, Silvia Clemencia

    2015-01-01

    The impact of mortality from cardiovascular diseases requires the measurement of the relationship between the local socioeconomic conditions and these death causes. To determine the inequality in mortality from cardiovascular diseases in the municipalities of the Colombian Coffee Growing Region (2009-2011). We conducted an ecological study to compare the mortality from cardiovascular diseases (hypertensive, ischemic, cerebrovascular) in municipalities and their economic situation. Mortality rates and the index of unsatisfied basic needs were obtained from the Colombian Departamento Administrativo Nacional de Estadística (DANE) vital statistics, while the municipal gross domestic product per capita was estimated for this study. The inequality indices were calculated using regression models, and concentration and Theil indices with Epidat 3.1. The death risk resulting from ischemic or hypertensive diseases was greater in those municipalities with a higher index of unsatisfied basic needs. Mortality due to hypertensive disease tended to concentrate in municipalities with a higher level of unsatisfied basic needs. The municipalities with a lower gross domestic product showed a higher rate of deaths due to hypertensive disease in years 2009 and 2010, and due to ischemic disease in years 2010 and 2011. Nevertheless, this indicator does not measure the gap existing among poor communities. Disaggregated inequality indicators at municipal level are lacking. Suggested indicators are estimated only for country and provincial levels and they do not favor the characterization of health social inequalities at territorial level.

  8. Two-Phase Cavitating Flow in Turbomachines

    Directory of Open Access Journals (Sweden)

    Sandor I. Bernad

    2012-11-01

    Full Text Available Cavitating flows are notoriously complex because they are highly turbulent and unsteady flows involving two species (liquid/vapor with a large density difference. These features pose a unique challenge to numerical modeling works. The study briefly reviews the methodology curently employed for industrial cavitating flow simulations using the two-phase mixture model. The two-phase mixture model is evaluated and validated using benchmark problem where experimental data are available. A 3D cavitating flow computation is performed for the GAMM Francis runner. The model is able to qualitatively predict the location and extent of the 3D cavity on the blade, but further investigation are needed to quatitatively assess the accuracy for real turbomachinery cavitating flows.

  9. Review of two-phase instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Han Ok; Seo, Han Ok; Kang, Hyung Suk; Cho, Bong Hyun; Lee, Doo Jeong

    1997-06-01

    KAERI is carrying out a development of the design for a new type of integral reactors. The once-through helical steam generator is important design features. The study on designs and operating conditions which prevent flow instability should precede the introduction of one-through steam generator. Experiments are currently scheduled to understand two-phase instability, evaluate the effect of each design parameter on the critical point, and determine proper inlet throttling for the prevention of instability. This report covers general two-phase instability with review of existing studies on this topics. The general classification of two phase flow instability and the characteristics of each type of instability are first described. Special attention is paid to BWR core flow instability and once-through steam generator instability. The reactivity feedback and the effect of system parameters are treated mainly for BWR. With relation to once-through steam generators, the characteristics of convective heating and dryout point oscillation are first investigated and then the existing experimental studies are summarized. Finally chapter summarized the proposed correlations for instability boundary conditions. (author). 231 refs., 5 tabs., 47 figs

  10. Critical thinking: a two-phase framework.

    Science.gov (United States)

    Edwards, Sharon L

    2007-09-01

    This article provides a comprehensive review of how a two-phase framework can promote and engage nurses in the concepts of critical thinking. Nurse education is required to integrate critical thinking in their teaching strategies, as it is widely recognised as an important part of student nurses becoming analytical qualified practitioners. The two-phase framework can be incorporated in the classroom using enquiry-based scenarios or used to investigate situations that arise from practice, for reflection, analysis, theorising or to explore issues. This paper proposes a two-phase framework for incorporation in the classroom and practice to promote critical thinking. Phase 1 attempts to make it easier for nurses to organise and expound often complex and abstract ideas that arise when using critical thinking, identify more than one solution to the problem by using a variety of cues to facilitate action. Phase 2 encourages nurses to be accountable and responsible, to justify a decision, be creative and innovative in implementing change.

  11. Spatially explicit exposure assessment for small streams in catchments of the orchard growing region `Lake Constance

    Science.gov (United States)

    Golla, B.; Bach, M.; Krumpe, J.

    2009-04-01

    1. Introduction Small streams differ greatly from the standardised water body used in the context of aquatic risk assessment for the regulation of plant protection products in Germany. The standard water body is static, with a depth of 0.3 m and a width of 1.0 m. No dilution or water replacement takes place. Spray drift happens always in direction to the water body. There is no variability in drift deposition rate (90th percentile spray drift deposition values [2]). There is no spray drift filtering by vegetation. The application takes place directly adjacent to the water body. In order to establish a more realistic risk assessment procedure the Federal Office for Consumer Protection and Food Safety (BVL) and the Federal Environment Agency (UBA) aggreed to replace deterministic assumptions with data distributions and spatially explicit data and introduce probabilistic methods [3, 4, 5]. To consider the spatial and temporal variability in the exposure situations of small streams the hydraulic and morphological characteristics of catchments need to be described as well as the spatial distribution of fields treated with pesticides. As small streams are the dominant type of water body in most German orchard regions, we use the growing region Lake Constance as pilot region. 2. Materials and methods During field surveys we derive basic morphological parameters for small streams in the Lake Constance region. The mean water width/depth ratio is 13 with a mean depth of 0.12 m. The average residence time is 5.6 s/m (n=87) [1]. Orchards are mostly located in the upper parts of the catchments. Based on an authoritative dataset on rivers and streams of Germany (ATKIS DLM25) we constructed a directed network topology for the Lake Constance region. The gradient of the riverbed is calculated for river stretches of > 500 m length. The network for the pilot region consists of 2000 km rivers and streams. 500 km stream length are located within a distance of 150 m to orchards. Within

  12. Role of Nucleation and Growth in Two-Phase Microstructure Formation

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Jong Ho [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    oscillatory microstructures that depend on the imposed velocity and the size of the sample. At low thermal gradient to velocity ratio, a steady-state composite microstructure is observed. Two mechanisms of composite microstructure formation were examined: (1) the formation of the peritectic phase in the intercellular region of the primary phase where the solute rejected by the primary phase is absorbed by the peritectic phase. The peritectic phase forms a small distance behind the growing primary phase front. (2) The second mechanism is the coupled growth of the two phases with a macroscopically planar interface, as in the case of eutectic growth. Detailed studies showed that this composite microstructure, although it appears as a eutectic microstructure, did not grow in the coupled manner at the advancing interface in the Sn-cd system. However, a new observation was made when experiments were carried out in thin ampoule of Ta. The peritectic phase nucleated at the wall-interface triple junction and grew along the wall, while the primary phase continued to grow at the center, giving rise to a steady-state couple growth at some specific velocity. The mechanism of coupled growth in this case was shown to be operative due to the presence of a finite contact angle at the wall, and this was demonstrated by including the contact angle effect at the wall in the rod eutectic growth model. The experimental results were summarized to map out the conditions of thermal gradient and velocity on the regimes of composite and oscillatory microstructure formation. The formation of complex time-dependent microstructures was then discussed in terms of the time-dependent dynamics of planar interface growth.

  13. Determination of Soil Parameters in Apple-Growing Regions by Near- and Mid-Infrared Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    DONG Yi-Wei; YANG Shi-Qi; XU Chun-Ying; LI Yu-Zhong; BAI Wei; FAN Zhong-Nan; WANG Ya-Nan; LI Qiao-Zhen

    2011-01-01

    Soil quality monitoring is important in precision agriculture.This study aimed to examine the possibility of assessing the soil parameters in apple-growing regions using spectroscopic methods.A total of 111 soil samples were collected from 11 typical sites of apple orchards,and the croplands surrounding them.Near-infrared (NIR) and mid-infrared (MIR)spectra,combined with partial least square regression,were used to predict the soil parameters,including organic matter (OM) content,pH,and the contents of As,Cu,Zn,Pb,and Cr.Organic matter and pH were closely correlated with As and the heavy metals.The NIR model showed a high prediction accuracy for the determination of OM,pH,and As,with correlation coefficients (r) of 0.89,0.89,and 0.90,respectively.The predictions of these three parameters by MIR showed reduced accuracy,with r values of 0.77,0.84,and 0.92,respectively.The heavy metals could also be measured by spectroscopy due to their correlation with organic matter.Both NIR and MIR had high correlation coefficients for the determination of Cu,Zn,and Cr,with standard errors of prediction of 2.95,10.48,and 9.49 mg kg-1 for NIR and 3.69,5.84,and 6.94 mg kg-1 for MIR,respectively.Pb content behaved differently from the other parameters.Both NIR and MIR underestimated Pb content,with r values of 0.67 and 0.56 and standard errors of prediction of 3.46 and 2.99,respectively.Cu and Zn had a higher correlation with OM and pH and were better predicted than Pb and Cr.Thus,NIR spectra could accurately predict several soil parameters,metallic and nonmetallic,simultaneously,and were more feasible than MIR in analyzing soil parameters in the study area.

  14. Microgravity Two-Phase Flow Transition

    Science.gov (United States)

    Parang, M.; Chao, D.

    1999-01-01

    Two-phase flows under microgravity condition find a large number of important applications in fluid handling and storage, and spacecraft thermal management. Specifically, under microgravity condition heat transfer between heat exchanger surfaces and fluids depend critically on the distribution and interaction between different fluid phases which are often qualitatively different from the gravity-based systems. Heat transfer and flow analysis in two-phase flows under these conditions require a clear understanding of the flow pattern transition and development of appropriate dimensionless scales for its modeling and prediction. The physics of this flow is however very complex and remains poorly understood. This has led to various inadequacies in flow and heat transfer modeling and has made prediction of flow transition difficult in engineering design of efficient thermal and flow systems. In the present study the available published data for flow transition under microgravity condition are considered for mapping. The transition from slug to annular flow and from bubbly to slug flow are mapped using dimensionless variable combination developed in a previous study by the authors. The result indicate that the new maps describe the flow transitions reasonably well over the range of the data available. The transition maps are examined and the results are discussed in relation to the presumed balance of forces and flow dynamics. It is suggested that further evaluation of the proposed flow and transition mapping will require a wider range of microgravity data expected to be made available in future studies.

  15. Droplet Manipulations in Two Phase Flow Microfluidics

    Directory of Open Access Journals (Sweden)

    Arjen M. Pit

    2015-11-01

    Full Text Available Even though droplet microfluidics has been developed since the early 1980s, the number of applications that have resulted in commercial products is still relatively small. This is partly due to an ongoing maturation and integration of existing methods, but possibly also because of the emergence of new techniques, whose potential has not been fully realized. This review summarizes the currently existing techniques for manipulating droplets in two-phase flow microfluidics. Specifically, very recent developments like the use of acoustic waves, magnetic fields, surface energy wells, and electrostatic traps and rails are discussed. The physical principles are explained, and (potential advantages and drawbacks of different methods in the sense of versatility, flexibility, tunability and durability are discussed, where possible, per technique and per droplet operation: generation, transport, sorting, coalescence and splitting.

  16. Two phase decision algorithm of replica allocation

    Institute of Scientific and Technical Information of China (English)

    Zuo Chaoshu; Liu Xinsong; Wang Zheng; Li Yi

    2006-01-01

    In distributed parallel server system, location and redundancy of replicas have great influence on availability and efficiency of the system. In order to improve availahility and efficiency of the system, two phase decision algorithm of replica allocation is proposed. The algorithm which makes use of auto-regression model dynamically predicts the future count of READ and WRITE operation, and then determines location and redundancy of replicas by considering availability, CPU and bands of the network. The algorithm can not only ensure the requirement of availability, but also reduce the system resources consumed by all the operations in a great scale. Analysis and test show that communication complexity and time complexity of the algorithm satisfy O( n ), resource optimizing scale increases with the increase of READ count.

  17. Comparative analysis of antioxidant activity and functional components of the ethanol extract of lotus (Nelumbo nucifera) from various growing regions.

    Science.gov (United States)

    Zhao, Xu; Shen, Jian; Chang, Kyung Ja; Kim, Sung Hoon

    2014-07-01

    The variations in antioxidant activity and concentration of functional components in the ethanol extracts of lotus seeds and rhizomes based on the growing region and dryness were investigated. Free radical scavenging activity, total phenolic and flavonoid content, and concentration of several specific flavonoids and alkaloids in the ethanol extracts of lotus were measured. Antioxidant activity and its correlative total phenolic content varied characteristically depending on the growing region and dryness. High-perfomance liquid chromatography analysis showed that the ethanol extracts of lotus seeds from Vietnam (Ho Chi Minh City), raw rhizomes from Korea (Siheung), and dried rhizomes from Japan (Nigata) had the greatest specific flavonoid content. The ethanol extracts of seeds from China (Hubei), raw rhizomes from Japan (Nigata), and dried rhizomes from Korea (Siheung) had the greatest specific alkaloid content. Astragaline, rutin, isoquercetin, nuciferine, dauricine, isoliensinine, and neferine were identified in lotus rhizomes for the first time in this study.

  18. Numerical Simulation of Two-phase Flow in Subcooled Boiling Region of Steam Generator%蒸汽发生器传热管束过冷沸腾区两相流动数值模拟

    Institute of Scientific and Technical Information of China (English)

    王成龙; 丛腾龙; 田文喜; 秋穗正; 苏光辉

    2014-01-01

    基于两流体欧拉数学模型结合RPI壁面沸腾模型,利用大型商用CFD软件ANSYS CFX 12.0对蒸汽发生器传热管束过冷沸腾区一次侧、壁面和二次侧耦合传热过程进行了数值模拟。研究了三叶梅花孔支撑板和不同入口过冷度条件下蒸汽发生器传热管束内的流动沸腾现象,得到一、二次侧流场与温度场,二次侧空泡份额分布,支撑板梅花孔局部的流动状况及不同入口过冷度对蒸汽发生器热工水力特性的影响。数值模拟结果表明,三叶梅花孔支撑板的存在及不同入口过冷度对蒸汽发生器传热管束过冷沸腾区域的热工水力特性影响显著。%Based on two fluid Euler model combining with RPI wall boiling model ,the coupled heat transfer among the primary side ,the tube wall and the secondary side in the subcooled boiling region of the heat transfer tube bundle of steam generator (SG) was simulated by using ANSYS CFX 12.0 code .The flow boiling phenomenon occurred in the heat transfer tube bundle of SG under trefoil orifice plate and different inlet subcooling conditions was researched . The velocity and temperature distributions of both the primary and the secondary sides ,the void fraction distribution of the secondary side ,the local flow characteristics around trefoil orifice plate ,and the effect of different inlet subcoolings on thermal-hydraulic characteristics of SG were acquired .Numerical simulated results show that the existence of trefoil orifice plate and inlet subcooling have a significant influence on thermal-hydraulic characteristics in the subcooled boiling region of the tube bundle of SG .

  19. Rapidly changing climatic conditions for wine grape growing in the Okanagan Valley region of British Columbia, Canada.

    Science.gov (United States)

    Rayne, Sierra; Forest, Kaya

    2016-06-15

    A statistical analysis was conducted on long-term climate records for sites bordering Okanagan Lake in the Okanagan Valley viticultural region of British Columbia, Canada. Average wine grape growing season temperatures are increasing rapidly in the area over the post-1980 period at rates upwards of 7.0±1.3°C/century. Similar increases in the average dormant season temperature are evident. These temperature changes are likely some of the most extreme observed among the world's wine producing areas during the past few decades. Growing degree day base 10°C (GDD10) has increased by nearly 50% at some locations since the 1970s, resulting in major impacts on the corresponding climate classification for viticulture. If current climate trends continue, the southern and central portions of the region will likely enter Winkler region II within the next few decades, placing them in the same category as well-established warmer wine regions from France, Spain, Italy, and Australia. The large dormant season temperature increases over the last several decades have resulted in the area no longer being a cold season outlier when compared to most other cool-climate viticultural areas. Based on average growing season temperatures, the southern end of Okanagan Lake has moved out of the cool-climate viticultural classification and into the intermediate zone, while the central and northern regions are now at the cool/intermediate viticulture interface, similar to the historical positions of the Rhine Valley in Germany, northern Oregon in the United States, and the Loire Valley, Burgundy-Cote, Burgundy-Beaujolais, and Champagne appelations of France. The corresponding suitable grape species for the area have evolved into warmer region varietals during this time frame, having substantial economic impacts on producers. Increased temperatures are also expected to bring greater threats from agricultural pests, notably Pierce's disease from the bacterium Xylella fastidiosa.

  20. Benefits of environmental conditions for growing coriander in Banat Region, Serbia.

    Science.gov (United States)

    Acimovic, Milica; Oljaca, Snezana; Jacimovic, Goran; Drazic, Slobodan; Tasic, Slavoljub

    2011-10-01

    As one of the oldest multi-purpose plants (spice, aromatic, honey and medicinal), coriander is widespread across Europe. Although in Serbia there are favorable conditions for its growth and development, it is grown on relatively small areas. During both investigated years it took more than 1200 degrees C for transfer from vegetative to generative phase of development and over 2000 degrees C for it to be ready for harvesting. Coriander is a photophilic plant, which requires around 1000 hours of light from sowing to ripening.. As for humidity, coriander grows well, if there are more than 200 mm of rainfall during growing season. In 2009 and 2010, the experiment carried out at the experimental field in Ostojićevo (Banat, Vojvodina province, Serbia) monitored the effect of parameters mentioned above on development of coriander plants, seed yield and essential oil content. The average yields of 1866 kg ha(-1) (2009) and 2470 kg ha(-1) (2010), and relatively high content of essential oil (1.06% in both years) indicate a great potential of this plant species in Serbia, which is, however, greatly dependent on environmental conditions during year.

  1. Characterization of horizontal air–water two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Ran; Kim, Seungjin, E-mail: skim@psu.edu

    2017-02-15

    Highlights: • A visualization study is performed to develop flow regime map in horizontal flow. • Database in horizontal bubbly flow is extended using a local conductivity probe. • Frictional pressure drop analysis is performed in horizontal bubbly flow. • Drift flux analysis is performed in horizontal bubbly flow. - Abstract: This paper presents experimental studies performed to characterize horizontal air–water two-phase flow in a round pipe with an inner diameter of 3.81 cm. A detailed flow visualization study is performed using a high-speed video camera in a wide range of two-phase flow conditions to verify previous flow regime maps. Two-phase flows are classified into bubbly, plug, slug, stratified, stratified-wavy, and annular flow regimes. While the transition boundaries identified in the present study compare well with the existing ones (Mandhane et al., 1974) in general, some discrepancies are observed for bubbly-to-plug/slug, and plug-to-slug transition boundaries. Based on the new transition boundaries, three additional test conditions are determined in horizontal bubbly flow to extend the database by Talley et al. (2015a). Various local two-phase flow parameters including void fraction, interfacial area concentration, bubble velocity, and bubble Sauter mean diameter are obtained. The effects of increasing gas flow rate on void fraction, bubble Sauter mean diameter, and bubble velocity are discussed. Bubbles begin to coalesce near the gas–liquid layer instead of in the highly packed region when gas flow rate increases. Using all the current experimental data, two-phase frictional pressure loss analysis is performed using the Lockhart–Martinelli method. It is found that the coefficient C = 24 yields the best agreement with the data with the minimum average difference. Moreover, drift flux analysis is performed to predict void-weighted area-averaged bubble velocity and area-averaged void fraction. Based on the current database, functional

  2. Essential oil compositions of two populations of Salvia samuelssonii growing in different biogeographical regions of Jordan.

    Science.gov (United States)

    Bader, Ammar; Cioni, Pier Luigi; De Tommasi, Nunziatina; Flamini, Guido

    2014-01-01

    The composition of the essential oils of flowering aerial parts of Salvia samuelssonii Rech. fil. (Lamiaceae Section Aethiopis), collected in two different biogeographical regions, has been analyzed. Samplel, collected in a Mediterranean-like region, "As-Subayhi", contains mainly monoterpenes (54.2%), sesquiterpenes (27.6%) and phenylpropanoids (10.5%), while sample 2, collected in the Irano-Turanian region, "Al-Adasiyyah", contains mainly phenylpropanoids (30.6%), monoterpenes (24.9%) and sesquiterpenes (21.2%). In Samplel, the most representative constituents were sabinene (21.5%), cis-chrysanthenyl acetate (20.8%), germacrene D (9.3%) and myristicin (5.9%), while in sample 2, myristicin (24.1%), sclareoloxide (6.3%), and germacrene D (5.7%) were main constituents. The rate of oxygenated derivatives in the Irano-Turanian sample was higher than the Mediterranean sample. Myristicin is an unusual constituent of Salvia species.

  3. Two-Phase Quality/Flow Meter

    Science.gov (United States)

    Moerk, J. Steven (Inventor); Youngquist, Robert C. (Inventor); Werlink, Rudy J. (Inventor)

    1999-01-01

    A quality and/or flow meter employs a capacitance probe assembly for measuring the dielectric constant of flow stream, particularly a two-phase flow stream including liquid and gas components.ne dielectric constant of the flow stream varies depending upon the volume ratios of its liquid and gas components, and capacitance measurements can therefore be employed to calculate the quality of the flow, which is defined as the volume ratio of liquid in the flow to the total volume ratio of gas and liquid in the flow. By using two spaced capacitance sensors, and cross-correlating the time varying capacitance values of each, the velocity of the flow stream can also be determined. A microcontroller-based processing circuit is employed to measure the capacitance of the probe sensors.The circuit employs high speed timer and counter circuits to provide a high resolution measurement of the time interval required to charge each capacitor in the probe assembly. In this manner, a high resolution, noise resistant, digital representation of each of capacitance value is obtained without the need for a high resolution A/D converter, or a high frequency oscillator circuit. One embodiment of the probe assembly employs a capacitor with two ground plates which provide symmetry to insure that accurate measurements are made thereby.

  4. Southern Slippage: Growing School Segregation in the Most Desegregated Region of the Country

    Science.gov (United States)

    Siegel-Hawley, Genevieve; Frankenberg, Erica

    2012-01-01

    The South remains the most desegregated region in the country for black students, but along every measure of segregation and at each level of geography, gains made during the desegregation era are slipping away at a steady pace. This report shows that the segregation of Southern black students has been progressively increasing since judicial…

  5. The Growing Trend of Moderate Preterm Births: An Ecological Study in One Region of Brazil.

    Directory of Open Access Journals (Sweden)

    Rosana Rosseto de Oliveira

    Full Text Available Preterm birth is a serious public health problem, as it is linked to high rates of neonatal and child morbidity and mortality, with Brazil listed among the countries with the ten highest numbers of premature births. Nonetheless, knowledge is scarce regarding prematurity and associated factors in mid-sized cities. The objective of this study was to analyze the trend of preterm births and associated factors in a municipality located in the state of Paraná, Brazil.This was an ecological time series study of births recorded into the Live Birth Information System for residents of Maringá, Paraná, Brazil, between 2000 and 2013. The polynomial regression model was used for trend analysis of preterm birth, characteristics of the mother, gestation and delivery, and newborn. The association with preterm birth was analyzed using odds ratio (OR.A total of 61,634 live births were analyzed, of which 5,632 were preterm births. Prematurity increased from 7.9% in 2000 to 11.2% in 2013 -an average increase of 0.54% per year (r2 = 0.93-with a growing share of moderate preterm births (32 to <37 weeks, which rose from 7.0% in 2000 to 9.7% in 2013. Between 2011 and 2013, multiple pregnancy (OR = 16.64; CI = 13.24-20.92, inadequate number of prenatal visits (OR = 2.81; CI = 2.51-3.15, Apgar score below 7 at 1 (OR = 4.07; CI = 3.55-4.67 and 5 minutes (OR = 10.88; CI = 7.71-15.36, low birth weight (OR = 38.75; CI = 33.72-44.55 and congenital malformations (OR = 3.18; CI = 2.14-4.74 were associated with preterm birth. A growing trend was observed for multiple pregnancies, with an average annual increase of 0.32% (r2 = 0.90, as well as for C-section birth (2.38% yearly increase. Of all newborn characteristics, Apgar score below 7 at 5 minutes (-0.19% per year and low birth weight (-1.43% decreased, whereas congenital malformations rose (0.20% per year.Efforts are required to prevent premature delivery, particularly during the moderate period, as well as greater care

  6. Male flight phenology of the European grapevine moth Lobesia botrana (Lepidoptera: Tortricidae) in different wine-growing regions in Spain.

    Science.gov (United States)

    Ortega-López, V; Amo-Salas, M; Ortiz-Barredo, A; Díez-Navajas, A M

    2014-10-01

    Lobesia botrana is the most significant pest of grape berries in Spain. Further knowledge of its phenology would enable wine growers to decide on an optimal treatment schedule. The aim of this study is, therefore, to predict the flight peaks of L. botrana in seven wine-growing regions of Spain. The main goal is to provide a prediction model based on meteorological data records. A logistic function model, based on temperature and humidity records, together with an exhaustive statistical analysis, were used to compare the wine-growing regions in which the male flight phenology of L. botrana displays similar patterns and to sort them into groups. By doing so, a joint study of the dynamics of the moth is possible in the regions within each group. A comparison of the prediction errors before and after applying the Touzeau model confirmed that the fit of the latter model is not sufficiently accurate for the regions under study. Moth flight predictions with the logistic function model are good, but accuracy may still be improved by evaluating other non-biotic and biotic factors.

  7. The detection of roadside pollution of rapidly growing city in arid region using the magnetic proxies

    Science.gov (United States)

    El-Hasan, Tayel

    2008-03-01

    This work is a complementary investigation to the earlier urban soil survey for a rapidly growing city of relatively high traffic density. Therefore, it aims to apply the environmental magnetism approach to assess the roadside pollution at a known polluted site. The used magnetic proxies are the initial magnetic susceptibility and saturation magnetization. The results prove the applicability of this method in detecting roadside pollution. The shape and magnitude of the magnetic signals was affected by the topography and prevailing wind direction that caused the magnetic peaks to be shifted accordingly. Particle size was found to affect the magnetic material content, where sand size (63-150 μm) bears the highest magnetic signals relative to smaller silt size (<63 μm). The magnetic anomalies coincided positively with heavy metal pollution in the studied site, which might indicate that the magnetic materials serve as an effective proxy for the metallic pollution (i.e., Fe, Ni, Pb, Cu, and Zn) originated mainly from vehicular sources.

  8. [An updated checklist of Phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae) from the Colombian Andean coffee-growing region].

    Science.gov (United States)

    Contreras-Gutiérrez, María Angélica; Vélez, Iván Darío; Porter, Charles; Uribe, Sandra Inés

    2014-01-01

    An updated list of phlebotomine sand flies species in coffee growing areas in the Colombian Andean region is presented. Fifty three species were reported from 12 departments. In addition, species distribution in the region was derived from specimens obtained during intensive field work in five departments, from previously published studies and from the taxonomic revision of specimens in the entomological collection of the Programa de Estudio y Control de Enfermedades Tropicales (PECET). The list includes the genera Brumptomyia (2 species), Lutzomyia (50 species) and Warileya (1 species). The updated list contains eleven new records in the region under study, including Lutzomyia panamensis , a species of medical importance not recorded previously in this zone. Eighteen of the species are considered to be anthropophilic, and many of them have been implicated in the transmission of leishmaniasis.

  9. Pressure Loss across Tube Bundles in Two-phase Flow

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Woo Gun; Banzragch, Dagdan [Hannam Univ., Daejon (Korea, Republic of)

    2016-03-15

    An analytical model was developed by Sim to estimate the two-phase damping ratio for upward two-phase flow perpendicular to horizontal tube bundles. The parameters of two-phase flow, such as void fraction and pressure loss evaluated in the model, were calculated based on existing experimental formulations. However, it is necessary to implement a few improvements in the formulations for the case of tube bundles. For the purpose of the improved formulation, we need more information about the two-phase parameters, which can be found through experimental test. An experiment is performed with a typical normal square array of cylinders subjected to the two-phase flow of air-water in the tube bundles, to calculate the two-phase Euler number and the two-phase friction multiplier. The pitch-to-diameter ratio is 1.35 and the diameter of cylinder is 18mm. Pressure loss along the flow direction in the tube bundles is measured with a pressure transducer and data acquisition system to calculate the two-phase Euler number and the two-phase friction multiplier. The void fraction model by Feenstra et al. is used to estimate the void fraction of the two-phase flow in tube bundles. The experimental results of the two phase friction multiplier and two-phase Euler number for homogeneous and non-homogeneous two-phase flows are compared and evaluated against the analytical results given by Sim's model.

  10. Analysis of transient gas-liquid two-phase natural circulation

    Energy Technology Data Exchange (ETDEWEB)

    Kataoka, Isao; Matsumoto, Tadayoshi; Morita, Yu; Kawashima, Atsushi [Department of Mechanophysics Engineering, Osaka University, Suita, Osaka (Japan); Nakayama, Akio

    1999-07-01

    Analyses were made on the transient behavior of two-phase natural circulation in annular passage. Drift flux model was used in the analyses and several correlations of drift velocity were used and compared. Transient variation of void fraction, inlet liquid flux and length of two-phase region were predicted based on simplified model. It was revealed that in transient two-phase natural circulation, the condition for pressure difference between inlet and outlet is quite important and difficult to be specified. A simplified model for inlet pressure condition was assumed and transient two-phase natural circulation was reasonably predicted. The correlation of drift velocity was shown to have important effect on the flow behavior particularly for the transient variation of two-phase length. (author)

  11. Vapor Compressor Driven Hybrid Two-Phase Loop Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will demonstrate a vapor compressor driven hybrid two-phase loop technology. The hybrid two-phase loop...

  12. Interannual Variations in Growing-Season NDVI and Its Correlation with Climate Variables in the Southwestern Karst Region of China

    Directory of Open Access Journals (Sweden)

    Wenjuan Hou

    2015-08-01

    Full Text Available In this study, the updated Global Inventory Modeling and Mapping Studies (GIMMS Normalized Difference Vegetation Index (NDVI dataset for growing season (April to October, which can better reflect the vegetation vigor, was used to investigate the interannual variations in NDVI and its relationship with climatic factors, in order to preliminarily understand the climate impact on vegetation and provide theoretical basis for the response of ecosystem to climate change. Multivariate linear regression models, including the Ordinary Least Squares (OLS and Geographically Weighted Regression (GWR, were adopted to analyze the correlation between NDVI and climatic factors (temperature and precipitation together. Average growing-season NDVI significantly increased at a rate of 0.0015/year from 1982 to 2013, larger than several regions in China. On the whole, its relationship with temperature is positive and also stronger than precipitation, which indicated that temperature may be a limiting factor for the vegetation growth in the Karst region. Moreover, the correlation coefficients between grassland NDVI and climatic factors are the largest. Under the background of NDVI increasing trend from 1982 to 2013, the period of 2009–2012 was chosen to investigate the influencing factors of a sharp decline in NDVI. It can be found that the reduced temperature and solar radiation, caused by the increase in cloud cover and precipitation, may play important roles in the vegetation cover change. All in all, the systematic research on the interannual variations of growing-season NDVI and its relationship with climate revealed the heterogeneity and variability in the complicated climate change in the Karst ecosystem for the study area. It is the Karst characteristics that hinder obtaining more representative conclusions and tendencies in this region. Hence, more attention should be paid to promoting Karst research in the future.

  13. Aphasia induced by gliomas growing in the ventrolateral frontal region: assessment with diffusion MR tractography, functional MR imaging and neuropsychology.

    Science.gov (United States)

    Bizzi, Alberto; Nava, Simone; Ferrè, Francesca; Castelli, Gianmarco; Aquino, Domenico; Ciaraffa, Francesca; Broggi, Giovanni; DiMeco, Francesco; Piacentini, Sylvie

    2012-02-01

    Lesions in the ventrolateral region of the dominant frontal lobe have been historically associated with aphasia. Recent imaging results suggest that frontal language regions extend beyond classically defined Broca's area to include the ventral precentral gyrus (VPCG) and the arcuate fasciculus (AF). Frontal gliomas offer a unique opportunity to identify structures that are essential for speech production. The aim of this prospective study was to investigate the correlation between language deficits and lesion location in patients with gliomas. Nineteen patients with glioma and 10 healthy subjects were evaluated with diffusion tensor imaging magnetic resonance (MR) tractography, functional MR (verb generation task) and the Aachener Aphasie Test. Patients were divided into two groups according to lesion location with respect to the ventral precentral sulcus: (i) anterior (n=8) with glioma growing in the inferior frontal gyrus (IFG) and underlying white matter; (ii) posterior (n=11) with glioma growing in the VPCG and underlying white matter. Virtual dissection of the AF, frontal intralobar tract, uncinate fasciculus (UF) and inferior frontal occipital fasciculus (IFOF) was performed with a deterministic approach. Seven posterior patients showed aphasia classified as conduction (4), Broca (1), transcortical motor (1) and an isolated deficit of semantic fluency; one anterior patient had transcortical mixed aphasia. All posterior patients had invasion of the VPCG, however only patients with aphasia had also lesion extension to the AF as demonstrated by tractography dissections. All patients with language deficits had high grade glioma. Groups did not differ regarding tumour volume. A functional pars opercularis was identified with functional MR imaging (fMRI) in 17 patients. Gliomas growing in the left VPCG are much more likely to cause speech deficits than gliomas infiltrating the IFG, including Broca's area. Lesion extension to the AF connecting frontal to parietal

  14. Thermo-fluid dynamics of two-phase flow

    CERN Document Server

    Ishii, Mamoru; Ishii, Mamoru; Ishii, M

    2006-01-01

    Provides a very systematic treatment of two phase flow problems from a theoretical perspectiveProvides an easy to follow treatment of modeling and code devlopemnt of two phase flow related phenomenaCovers new results of two phase flow research such as coverage of fuel cells technology.

  15. A real two-phase submarine debris flow and tsunami

    Energy Technology Data Exchange (ETDEWEB)

    Pudasaini, Shiva P.; Miller, Stephen A. [Department of Geodynamics and Geophysics, Steinmann Institute, University of Bonn Nussallee 8, D-53115, Bonn (Germany)

    2012-09-26

    The general two-phase debris flow model proposed by Pudasaini is employed to study subaerial and submarine debris flows, and the tsunami generated by the debris impact at lakes and oceans. The model, which includes three fundamentally new and dominant physical aspects such as enhanced viscous stress, virtual mass, and generalized drag (in addition to buoyancy), constitutes the most generalized two-phase flow model to date. The advantage of this two-phase debris flow model over classical single-phase, or quasi-two-phase models, is that the initial mass can be divided into several parts by appropriately considering the solid volume fraction. These parts include a dry (landslide or rock slide), a fluid (water or muddy water; e.g., dams, rivers), and a general debris mixture material as needed in real flow simulations. This innovative formulation provides an opportunity, within a single framework, to simultaneously simulate the sliding debris (or landslide), the water lake or ocean, the debris impact at the lake or ocean, the tsunami generation and propagation, the mixing and separation between the solid and fluid phases, and the sediment transport and deposition process in the bathymetric surface. Applications of this model include (a) sediment transport on hill slopes, river streams, hydraulic channels (e.g., hydropower dams and plants); lakes, fjords, coastal lines, and aquatic ecology; and (b) submarine debris impact and the rupture of fiber optic, submarine cables and pipelines along the ocean floor, and damage to offshore drilling platforms. Numerical simulations reveal that the dynamics of debris impact induced tsunamis in mountain lakes or oceans are fundamentally different than the tsunami generated by pure rock avalanches and landslides. The analysis includes the generation, amplification and propagation of super tsunami waves and run-ups along coastlines, debris slide and deposition at the bottom floor, and debris shock waves. It is observed that the

  16. Diversity of malaria in rice growing areas of the Afrotropical region.

    Science.gov (United States)

    Carnevale, P; Guillet, P; Robert, V; Fontenille, D; Doannio, J; Coosemans, M; Mouchet, J

    1999-09-01

    It is well known that 'in many instances the rice agrosystem perfectly fits the ecological requirements of pathogens or vectors' and in fact 'malaria, schistosomiasis and Japanese encephalitis are important vector-borne diseases associated with rice production in developing countries' (IRRI, 1987). In spite of these fears, rice cultivation has been on the increase in the African region in response to demographic and economic pressures. However, although rice fields provide suitable breeding places for Anopheles mosquitoes and rice cultivation leads to an increase in the biting rates, the species which are adapted to these sites are not the same in all parts of Africa. Several examples illustrate this phenomenon: An. funestus in the rice fields of Madagascar, An. pharoensis in saline water rice fields in the delta of the Senegal river, An. arabiensis in northern Cameroon and Burundi, An. gambiae Mopti form in the Kou Valley (Burkina Faso) and An. gambiae Savanna form in the rice fields of Kafine near Bouaké (Côte d'Ivoire). The vectorial capacities of these species are not the same and malaria inoculation rates are not necessarily increased in the riceland agroecosystem. The consequences for malaria of introducing rice cultivation depend on the situation before its introduction: it could be worsened in unstable malaria areas but not in stable malaria areas. Therefore, sound epidemiological and entomological knowledge are needed before causing any environmental modifications for agricultural purposes and there should be regular monitoring to avoid any outbreak.

  17. Uptake of uranium, thorium and radium isotopes by plants growing in dam impoundment Tasotkel and the Lower Shu region (Kazakhstan)

    Energy Technology Data Exchange (ETDEWEB)

    Matveyeva, Ilona; Burkitbayev, Mukhambetkali [al-Farabi Kazakh National University, Almaty (Kazakhstan). Faculty of Chemistry and Chemical Technology; Jacimovic, Radojko [Jozef Stefan Institute, Ljubljana (Slovenia). Dept. of Environmental Sciences; Planinsek, Petra; Smodis, Borut [Jozef Stefan Institute, Ljubljana (Slovenia). Dept. of Environmental Sciences; Jozef Stefan International Postgraduate School, Ljubljana (Slovenia)

    2016-04-01

    The activity concentrations of isotopes of uranium, thorium and radium-226 in dominant species of plants (Xantium strumarium, Phragmites communis, Artemisia nitrosa and Artemisia serotina) growing on the territories contaminated by uranium industry of Kazakhstan (close to dam impoundment Tasotkel and the Lower Shu region) are presented. The obtained data showed the significant variations of activity concentrations of isotopes of uranium, thorium and radium-226 in above ground parts. The concentrations of most of the investigated radionuclides in the root system are higher than in the aboveground parts; it can be explained by root barrier. It was found that the highest root barrier has Xantium strumarium, especially for uranium isotopes. The concentration ratios of radionuclides were calculated, and as the result it was found that the highest accumulation ability in the investigated region has Artemisia serotina.

  18. A Self-Calibrating Multi-Band Region Growing Approach to Segmentation of Single and Multi-Band Images

    Energy Technology Data Exchange (ETDEWEB)

    Paglieroni, D W

    2002-12-20

    Image segmentation transforms pixel-level information from raw images to a higher level of abstraction in which related pixels are grouped into disjoint spatial regions. Such regions typically correspond to natural or man-made objects or structures, natural variations in land cover, etc. For many image interpretation tasks (such as land use assessment, automatic target cueing, defining relationships between objects, etc.), segmentation can be an important early step. Remotely sensed images (e.g., multi-spectral and hyperspectral images) often contain many spectral bands (i.e., multiple layers of 2D images). Multi-band images are important because they contain more information than single-band images. Objects or natural variations that are readily apparent in certain spectral bands may be invisible in 2D broadband images. In this paper, the classical region growing approach to image segmentation is generalized from single to multi-band images. While it is widely recognized that the quality of image segmentation is affected by which segmentation algorithm is used, this paper shows that algorithm parameter values can have an even more profound effect. A novel self-calibration framework is developed for automatically selecting parameter values that produce segmentations that most closely resemble a calibration edge map (derived separately using a simple edge detector). Although the framework is generic in the sense that it can imbed any core segmentation algorithm, this paper only demonstrates self-calibration with multi-band region growing. The framework is applied to a variety of AVIRIS image blocks at different spectral resolutions, in an effort to assess the impact of spectral resolution on segmentation quality. The image segmentations are assessed quantitatively, and it is shown that segmentation quality does not generally appear to be highly correlated with spectral resolution.

  19. INNOVATIVE CULTURE QUINOA (CHENOPODIUM QUINOA – THE PROSPECTS OF GROWING IN THE KRASNODAR REGION TO PRODUCE FOODS HIGH NUTRITIONAL VALUE

    Directory of Open Access Journals (Sweden)

    Shchekoldina T. V.

    2016-09-01

    Full Text Available Healthy nutrition is the foundation of the nation and the most important factor affecting the length of human life. Therefore, the search and the use of new sources of food are important. One of such source is the ancient culture of quinoa (Chenopodium quinoa, known as a "qinoa", "quinva" or "rice quinoa. The uniqueness of the quinoa is its chemical composition, the absence of anti-nutritional substances and unpretentious in growing and harvesting. Currently quinoa is grown in more than 70 countries. In Russia, quinoa is not cultivated, although the presence of different agro-ecological zones of the plains to the highlands allows it to grow. In April 2014 quinoa was first planted in the Krasnodar region. In September, quinoa whisk acquired red and yellow. The seeds have a size of between 1 and 2.5 mm. Preliminary calculations yield was approximately 39hundredweight / hectare, which is the basis for the introduction of quinoa in a mass planting. Thus, quinoa can be grown in Russia in the Krasnodar region, thereby ensuring its own raw material base for development of new specialized foods (gluten-free and prophylactic (high nutritional value destination

  20. Reynolds transport theorem for a two-phase flow

    Science.gov (United States)

    Collado, Francisco J.

    2007-01-01

    Transport equations for one-dimensional (1d), steady, two-phase flow have been proposed based on the fact that if the phases have different velocities, they cannot cover the same distance (the control volume length) in the same time. Thus, working in the same control volume for the two phases, the time scales of the phases have to be different. From this approach, transport balances for 1D, steady, two-phase flow have been already derived, supplying acceptable correlations for two-phase flow. Here, based on the strict application of the Reynolds transport theorem, general transport balances for two-phase flow are suggested.

  1. Effects of Different Growing Regions on Quality Characteristics, Bioactive Compound Contents, and Antioxidant Activity of Aronia (Aronia melanocarpa) in Korea

    Science.gov (United States)

    Hwang, Eun-Sun; Thi, Nhuan Do

    2016-01-01

    The objective of this study was to determine the effects of different growing regions on quality characteristics, total bioactive compound contents, and in vitro antioxidant activity in aronia. Aronia grown in 3 different regions (Sangjoo, Ulju, and Youngcheon) in Korea was obtained and used fresh or as a freeze-dried powder. No statistically significant differences were observed for moisture, ash, crude lipid, and crude protein contents in aronia sampled from the 3 different regions. Aronia grown in Sangjoo had the highest total acid content and the lowest sugar content and pH value. Conversely, aronia grown in Youngcheon possessed the lowest total acid content and the highest sugar content and pH value. Aronia grown in Sangjoo possessed relatively high levels of polyphenols, flavonoids, and anthocyanins, as well as high antioxidant activity in comparison with aronia produced in other regions. Aronia grown in Youngcheon scored the highest for taste and overall acceptability in sensory evaluations, which may be related to the high sugar content and pH, and the low total acidity of the fruits. It is possible that higher sugar contents and pH, and lower total acidity in the aronia grown in Youngcheon result in more preferable sensory characteristics. However, they also contain relatively low levels of total polyphenols, flavonoids, and anthocyanins, and have low antioxidant activity as measured by 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assays. PMID:27752502

  2. Two-phase flow instability in a parallel multichannel system

    Institute of Scientific and Technical Information of China (English)

    HOU Suxia

    2009-01-01

    The two-phase flow instabilities observed in through parallel multichannel can be classified into three types, of which only one is intrinsic to parallel multichannel systems. The intrinsic instabilities observed in parallel multichannel system have been studied experimentally. The stable boundary of the flow in such a parallel-channel system are sought, and the nature of inlet flow oscillation in the unstable region has been examined experimentally under various conditions of inlet velocity, heat flux, liquid temperature, cross section of channel and entrance throttling. The results show that parallel multichannel system possess a characteristic oscillation that is quite independent of the magnitude and duration of the initial disturbance, and the stable boundary is influenced by the characteristic frequency of the system as well as by the exit quality when this is low, and upon raising the exit quality and reducing the characteristic frequency, the system increases its instability, and entrance throttling effectively contributes to stabilization of the system.

  3. Response of two-phase droplets to intense electromagnetic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Spann, J.F. (Morgantown Energy Technology Center, U.S. Department of Energy, P.O. Box 880, Morgantown, West Virginia 26507-0880 (United States)); Maloney, D.J.; Lawson, W.F.; Casleton, K.H. (Morgantown Energy Technology Center, U.S. Department of Energy, P.O. Box 880, Morgantown, West Virginia 26507-0880 (United States))

    1993-04-20

    The response of two-phase droplets to intense radiant heating is studied to determine the incident power that is required for causing explosive boiling in the liquid phase. The droplets studied consist of strongly absorbing coal particles dispersed in a weakly absorbing water medium. Experiments are performed by confining droplets (radii = 37, 55, and 80 [mu]m) electrodynamically and irradiating them from two sides with pulsed laser beams. Emphasis is placed on the transition region from accelerated droplet vaporization to droplet superheating and explosive boiling. The time scale observed for explosive boiling is more than 2 orders of magnitude longer than published values for pure liquids. The delayed response is the result of energy transfer limitations between the absorbing solid phase and the surrounding liquid.

  4. Solutal Marangoni instability in layered two-phase flows

    CERN Document Server

    Picardo, Jason R; Pushpavanam, S

    2015-01-01

    In this paper, the instability of layered two-phase flows caused by the presence of a soluble surfactant (or a surface active solute) is studied. The fluids have different viscosities, but are density matched to focus on Marangoni effects. The fluids flow between two flat plates, which are maintained at different solute concentrations. This establishes a constant flux of solute from one fluid to the other in the base state. A linear stability analysis is performed, using a combination of asymptotic and numerical methods. In the creeping flow regime, Marangoni stresses destabilize the flow, provided a concentration gradient is maintained across the fluids. One long wave and two short wave Marangoni instability modes arise, in different regions of parameter space. A well-defined condition for the long wave instability is determined in terms of the viscosity and thickness ratios of the fluids, and the direction of mass transfer. Energy budget calculations show that the Marangoni stresses that drive long and shor...

  5. Response of two-phase droplets to intense electromagnetic radiation

    Science.gov (United States)

    Spann, James F.; Maloney, Daniel J.; Lawson, William F.; Casleton, Kent H.

    1993-01-01

    The response of two-phase droplets to intense radiant heating is studied to determine the incident power that is required for causing explosive boiling in the liquid phase. The droplets studied consist of strongly absorbing coal particles dispersed in a weakly absorbing water medium. Experiments are performed by confining droplets (radii of 37, 55, and 80 microns) electrodynamically and irradiating them from two sides with pulsed laser beams. Emphasis is placed on the transition region from accelerated droplet vaporization to droplet superheating and explosive boiling. The time scale observed for explosive boiling is more than 2 orders of magnitude longer than published values for pure liquids. The delayed response is the result of energy transfer limitations between the absorbing solid phase and the surrounding liquid.

  6. The interaction between deepwater channel systems and growing thrusts and folds, toe-thrust region of the deepwater Niger Delta

    Science.gov (United States)

    Jolly, Byami; Whittaker, Alex; Lonergan, Lidia

    2015-04-01

    Gravity-driven seaward-verging thrusts, landward-verging back-thrusts and associated folds often characterize the slope and deepwater settings of passive margins. These structures, found in the 'toe-thrust' region of the system, exert a significant control on sediment gravity flows because they create and determine the location and configuration of sediment depocentres and transport systems. Consequently, a quantitative understanding of the interaction between sediment gravity flows and seabed topography is required to understand these systems effectively. Here we make quantitative measurements of the geomorphic response of submarine channels to growing tectonic structures with the aim of providing new constraints on the long-term erosional dynamics of submarine channel systems. This study exploits 3D seismic data in the outer toe-thrust region of the deepwater Niger Delta to analyze the interaction between Plio-Pleistocene channel systems and actively growing folds and thrusts. We mapped folds and thrusts from the seismic data and we used this data to reconstruct the history of fold growth. We then used the sea-bed seismic horizon to build a 50 m resolution Digital Elevation Model (DEM) of the sea floor in Arc-GIS. We extracted channel long- profiles across growing structures from the DEM, and made measurements of channel geometries at regular intervals along the channel length. This information was used to infer morphodyanamic processes that sculpted the channel systems through time, and to estimate the bed shear stresses and fluid velocities of typical flow events. The bathymetric long profiles of these channels are relatively linear with concavity that range from -0.08 to -0.34, and an average gradient of ~1o. Actively growing thrusts are typically associated with a local steepening in channel gradient by a factor of up to 3, and this effect extends 0.5 - 2 km upstream of the thrust. Within these knickzones, channel incision increases by approximately by a

  7. Comparison of Insecticide Susceptibilities of Empoasca vitis (Hemiptera: Cicadellidae) from Three Main Tea-Growing Regions in China.

    Science.gov (United States)

    Wei, Qi; Yu, Hua-Yang; Niu, Chun-Dong; Yao, Rong; Wu, Shun-Fan; Chen, Zhuo; Gao, Cong-Fen

    2015-06-01

    Empoasca vitis (Göthe) is an important insect pest in tea-growing areas of China, and chemical control is the main tactic for the management of this pest. Due to the pressure of increasing insecticide resistance and more stringent food safety regulations, development of sound IPM strategies for E. vitis is an urgent matter. This study comparatively evaluated four field populations of E. vitis from three different tea-growing regions in China for their susceptibilities to eight insecticides using a simple leaf-dip methodology. E. vitis was found to be most sensitive to indoxacarb (LC505 mg/liter) and sophocarpidine (LC50>95 mg/liter, a botanical pesticide) regardless of populations. Population (geographical) variations were higher for indoxacarb and imidacloprid than other compounds. Judging by the 95% fiducial limits of LC50 values, all populations had similar susceptibilities to chlorfenapyr, bifenthrin, and acetamiprid or imidacloprid. Correlation analysis suggested that chlorfenapyr and indoxacarb or isoprocarb may have a high risk of cross resistance. Considering potency (LC50) and maximum residual levels, chlorfenapyr and bifenthrin are good insecticide options followed by acetamiprid and indoxacarb. These results provide valuable information to intelligently select insecticides for IPM programs that are efficacious against E. vitis while also managing insecticide resistance and maximum residual levels for tea production in China. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Sap Flow of Populus euphratica in a Desert Riparian Forest in an Extreme Arid Region During the Growing Season

    Institute of Scientific and Technical Information of China (English)

    Jian-Hua Si; Qi Feng; Xiao-You Zhang; Zong-Qiang Chang; Yong-Hong Su; Hai-Yang Xi

    2007-01-01

    In the present study, the heat pulse technique was applied to investigate the stem sap flow of Populus euphratica in a desert riparian forest in an extreme arid region from April to October 2003 and from May to October 2004. The experimental sites were in Qidaoqiao (101 °10'E, 41°59'N) and Bayantaolai farm (101°14'E, 42°01'N) in Ejina county, in the Iow reaches of the Heihe River, China. The results indicated that the diurnal change in the velocity of sap flow showed minor fluctuations. At night, the rising of sap flow could be observed in the main tree species because of root pressure. During the growing season, the maximum average velocity was observed in July, followed by August, and the same velocity was observed in September and May; the minimum velocity was observed in October. The transpiration from June to August during the growing season accounted for approximately 70% of the annual total transpiration. The sap flow velocity of P. euphratica trees of different ages could be arranged in the order: 15 yr > 25 yr > 50 yr. Sap flow velocity was closely related to changes in micrometeorological factors, with average sap flow velocity showing a significant linear correlation with net radiation, air temperature and relative humidity.

  9. A region-growing approach for automatic outcrop fracture extraction from a three-dimensional point cloud

    Science.gov (United States)

    Wang, Xin; Zou, Lejun; Shen, Xiaohua; Ren, Yupeng; Qin, Yi

    2017-02-01

    Conventional manual surveys of rock mass fractures usually require large amounts of time and labor; yet, they provide a relatively small set of data that cannot be considered representative of the study region. Terrestrial laser scanners are increasingly used for fracture surveys because they can efficiently acquire large area, high-resolution, three-dimensional (3D) point clouds from outcrops. However, extracting fractures and other planar surfaces from 3D outcrop point clouds is still a challenging task. No method has been reported that can be used to automatically extract the full extent of every individual fracture from a 3D outcrop point cloud. In this study, we propose a method using a region-growing approach to address this problem; the method also estimates the orientation of each fracture. In this method, criteria based on the local surface normal and curvature of the point cloud are used to initiate and control the growth of the fracture region. In tests using outcrop point cloud data, the proposed method identified and extracted the full extent of individual fractures with high accuracy. Compared with manually acquired field survey data, our method obtained better-quality fracture data, thereby demonstrating the high potential utility of the proposed method.

  10. Heavy metal accumulation in leaves and beans of cacao (Theobroma cacao L.) in major cacao growing regions in Peru.

    Science.gov (United States)

    Arévalo-Gardini, Enrique; Arévalo-Hernández, Cesar O; Baligar, Virupax C; He, Zhenli L

    2017-12-15

    Peru is one of the leading exporters of organic cacao beans in the world. However, the accumulation of heavy metals in cacao beans represents a problem for cocoa bean export and chocolate quality. The aim of this study was to investigate the distribution and accumulation of heavy metals in cacao leaves and cocoa beans in three major cacao growing regions of Peru. The study was conducted in cacao plantations of 10 to 15years old in three regions of Peru: North (Regions of Tumbes, Piura, Cajamarca, and Amazonas); Center (Regions of Huánuco and San Martin) and South (Junin and Cuzco). Samples of leaf and cacao beans were collected from 70 cacao plantations, and the nature of cacao clone or genotype sampled was recorded. The concentrations of heavy metals such as Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in leaves and beans were determined using atomic absorption spectrophotometer. Overall, concentrations of heavy metals were below the critical limits; however, the presence of high levels of Cd in cacao grown in Amazonas, Piura, and Tumbes regions is of primary concern. Plantations of cacao with different cacao clones show differences in Cd accumulation both in leaves and cocoa beans. Therefore, it is promising to screen low Cd accumulator cacao genotypes for safe production of cacao on lightly to moderately Cd contaminated soils. Also, synergism between Zn and Cd present both in plant and soil suggests that Zn has a direct effect on Cd accumulation in cacao. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Rarefaction Waves at the Outlet of the Supersonic Two-Phase Flow Nozzle

    Science.gov (United States)

    Nakagawa, Masafumi; Miyazaki, Hiroki; Harada, Atsushi

    Two-phase flow nozzles are used in the total flow system for geothermal power plants and in the ejector of the refrigerant cycle, etc. One of the most important functions of a two-phase flow nozzle is to convert the thermal energy to the kinetic energy of the two-phase flow. The kinetic energy of the two-phase flow exhausted from a nozzle is available for all applications of this type. There exist the shock waves or rarefaction waves at the outlet of a supersonic nozzle in the case of non-best fitting expansion conditions when the operation conditions of the nozzle are widely chosen. Those waves affect largely on the energy conversion efficiency of the two-phase flow nozzle. The purpose of the present study is to elucidate the character of the rarefaction waves at the outlet of the supersonic two-phase flow nozzle. The high pressure hot water blow down experiment has been carried out. The decompression curves by the rarefaction waves are measured by changing the flow rate of the nozzle and inlet temperature of the hot water. The back pressures of the nozzle are also changed in those experiments. The divergent angles of the two-phase flow flushed out from the nozzle are measured by means of the photograph. The experimental results show that the recompression curves are different from those predicted by the isentropic homogenous two-phase flow. The regions where the rarefaction waves occur become wide due to the increased outlet speed of two-phase flow. The qualitative dependency of this expansion character is the same as the isotropic homogenous flow, but the values obtained from the experiments are quite different. When the back pressure of the nozzle is higher, these regions do not become small in spite of the super sonic two-phase flow. This means that the disturbance of the down-stream propagate to the up-stream. It is shown by the present experiments that the rarefaction waves in the supersonic two-phase flow of water have a subsonic feature. The measured

  12. Expansion Waves at the Outlet of the Supersonic Two-Phase Flow Nozzle

    Science.gov (United States)

    Nakagawa, Masafumi; Miyazaki, Hiroki; Harada, Atsushi; Ibragimov, Zokirjon

    Two-phase flow nozzles are used in the total flow system of geothermal power plants and in the ejector of the refrigeration cycle, etc. One of the most important functions of the two-phase flow nozzle is converting two-phase flow thermal energy into kinetic energy. The kinetic energy of the two-phase flow exhausted from a nozzle is available for all applications of this type. In the case of non-best fitting expansion conditions, when the operation conditions of the supersonic nozzle are widely chosen, there exist shock waves or expansion waves at the outlet of the nozzle. Those waves affect largely the energy conversion efficiency of the two-phase flow nozzle. The purpose of the present study is to elucidate character of the expansion waves at the outlet of the supersonic two-phase flow nozzle. High-pressure hot water blowdown experiments have been carried out. The decompression curves of the expansion waves are measured by changing the flowrate in the nozzle and inlet temperature of the hot water. The back pressures of the nozzle are also changed in those experiments. The expansion angles of the two-phase flow flushed out from the nozzle are measured by means of the photograph. The experimental results show that the decompression curves are different from those predicted by the isentropic homogeneous two-phase flow theory. The regions where the expansion waves occur become wide due to the increased outlet speed of the two-phase flow. The qualitative dependency of this expansion character is the same as the isentropic homogeneous flow, but the values obtained from the experiments are quite different. When the back pressure of the nozzle is higher, these regions do not become small in spite of the supersonic two-phase flow. This means that the disturbance in the downstream propagates to the upstream. It is shown by the present experiments that the expansion waves in the supersonic two-phase flow of water have a subsonic feature. The measured expansion angles become

  13. Guidelines regarding the interim use and phase out of neonicotinoid insecticides to grow agricultural crops for wildlife on NWRs in the Pacific Region

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Memorandum describing a phased approach in the Pacific Region to eliminate the use of neonicotinoidinsecticides (by any method) to grow agricultural crops for...

  14. Next steps in two-phase flow: executive summary

    Energy Technology Data Exchange (ETDEWEB)

    DiPippo, R.

    1980-09-01

    The executive summary includes the following topics of discussion: the state of affairs; the fundamental governing equations; the one-dimensional mixture model; the drift-flux model; the Denver Research Institute two-phase geothermal flow program; two-phase flow pattern transition criteria; a two-fluid model under development; the mixture model as applied to geothermal well flow; DRI downwell instrumentation; two-phase flow instrumentation; the Sperry Research Corporation downhole pump and gravity-head heat exchanger systems; and the Brown University two-phase flow experimental program. (MHR)

  15. Non-local two phase flow momentum transport in S BWR

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa P, G.; Salinas M, L.; Vazquez R, A., E-mail: gepe@xanum.uam.mx [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Area de Ingenieria en Recursos Energeticos, Apdo. Postal 55-535, 09340 Ciudad de Mexico (Mexico)

    2015-09-15

    The non-local momentum transport equations derived in this work contain new terms related with non-local transport effects due to accumulation, convection, diffusion and transport properties for two-phase flow. For instance, they can be applied in the boundary between a two-phase flow and a solid phase, or in the boundary of the transition region of two-phase flows where the local volume averaging equations fail. The S BWR was considered to study the non-local effects on the two-phase flow thermal-hydraulic core performance in steady-state, and the results were compared with the classical local averaging volume conservation equations. (Author)

  16. Satellite Images for Monitoring Mangrove Cover Changes in a Fast Growing Economic Region in Southern Peninsular Malaysia

    Directory of Open Access Journals (Sweden)

    Kasturi Devi Kanniah

    2015-10-01

    Full Text Available Effective monitoring is necessary to conserve mangroves from further loss in Malaysia. In this context, remote sensing is capable of providing information on mangrove status and changes over a large spatial extent and in a continuous manner. In this study we used Landsat satellite images to analyze the changes over a period of 25 years of mangrove areas in Iskandar Malaysia (IM, the fastest growing national special economic region located in southern Johor, Malaysia. We tested the use of two widely used digital classification techniques to classify mangrove areas. The Maximum Likelihood Classification (MLC technique provided significantly higher user, producer and overall accuracies and less “salt and pepper effects” compared to the Support Vector Machine (SVM technique. The classified satellite images using the MLC technique showed that IM lost 6740 ha of mangrove areas from 1989 to 2014. Nevertheless, a gain of 710 ha of mangroves was observed in this region, resulting in a net loss of 6030 ha or 33%. The loss of about 241 ha per year of mangroves was associated with a steady increase in urban land use (1225 ha per year from 1989 until 2014. Action is necessary to protect the existing mangrove cover from further loss. Gazetting of the remaining mangrove sites as protected areas or forest reserves and introducing tourism activities in mangrove areas can ensure the continued survival of mangroves in IM.

  17. Heavy Metals Accumulation in Topsoils from the Wine-growing Regions Part 1. Factors which Control Retention

    Directory of Open Access Journals (Sweden)

    Marija Romić

    2004-03-01

    Full Text Available The problem of exposure of agricultural soils to different anthropogenic inputs of heavy metals has been investigated in soils from two wine-producing subregions in northwestern Croatia. The aim of this study was to explore :(i the main soil properties and topsoil accumulation of heavy metals in vineyards under long-term cultivation, and (ii the origin and the preferential feature of metal retention in vineyard topsoil using the multivariate statistical method. The investigated area was marked on regular square grid with 1-km spacing. Topsoil samples (0-10 cm were collected from each sampling point and analyzed for soil chemical properties, particle size distribution and heavy metal concentrations after aqua region digestion. All soil data were incorporate into the GIS base. Summary statistics of the data set were first calculated to evaluate the distributions, and afterward processed by means of R-mode factor analysis, applying the varimax-raw rotational technique. Anthropogenic input of metals in soils of the studied wine-growing regions mostly originates from agrochemicals, since the direct influence of the urban environment or industry is almost negligible. Accumulation of copper and zinc in topsoil, determined in this research, is the most common effect of continuing fertilization and protection against diseases and pests in vineyards.

  18. Detection of pedestrians in far-infrared automotive night vision using region-growing and clothing distortion compensation

    Science.gov (United States)

    O'Malley, Ronan; Jones, Edward; Glavin, Martin

    2010-11-01

    We present a night-time pedestrian detection system based on automotive infrared video processing. Far-infrared or thermal night vision is a technology well suited for automatic detection of pedestrians at night as they generally appear warmer than the background. However, the appearance of a pedestrian in IR video can vary dramatically depending on the physical properties of the clothing they wear, the time spent adjusting to the outside environment, and the ambient temperature. We highlight the difficulties of detection in low temperatures (below 8 °C) when pedestrians typically wear highly insulating clothing, which can lead to distortion of the IR signature of the pedestrian. A pre-processing step is presented, which compensates for this clothing-based distortion using vertically-biased morphological closing. Potential pedestrians (Regions of Interest) are then segmented using feature-based region-growing with high intensity seeds. Histogram of Oriented Gradients (HOG) features are extracted from candidates and utilised for Support Vector Machine classification. Positively classified targets are tracked between frames using a Kalman filter, adding robustness and increasing performance. The proposed system adapts not just to variations between images or video frames, but to variations in appearance between different pedestrians in the same image or frame. Results indicate improved performance compared to previous HOG-SVM automotive IR pedestrian detection systems, which utilised stereo IR cameras.

  19. Adaptive region-growing with maximum curvature strategy for tumor segmentation in 18F-FDG PET

    Science.gov (United States)

    Tan, Shan; Li, Laquan; Choi, Wookjin; Kang, Min Kyu; D'Souza, Warren D.; Lu, Wei

    2017-07-01

    Accurate tumor segmentation in PET is crucial in many oncology applications. We developed an adaptive region-growing (ARG) algorithm with a maximum curvature strategy (ARG_MC) for tumor segmentation in PET. The ARG_MC repeatedly applied a confidence connected region-growing algorithm with increasing relaxing factor f. The optimal relaxing factor (ORF) was then determined at the transition point on the f-volume curve, where the volume just grew from the tumor into the surrounding normal tissues. The ARG_MC along with five widely used algorithms were tested on a phantom with 6 spheres at different signal to background ratios and on two clinic datasets including 20 patients with esophageal cancer and 11 patients with non-Hodgkin lymphoma (NHL). The ARG_MC did not require any phantom calibration or any a priori knowledge of the tumor or PET scanner. The identified ORF varied with tumor types (mean ORF  =  9.61, 3.78 and 2.55 respectively for the phantom, esophageal cancer, and NHL datasets), and varied from one tumor to another. For the phantom, the ARG_MC ranked the second in segmentation accuracy with an average Dice similarity index (DSI) of 0.86, only slightly worse than Daisne’s adaptive thresholding method (DSI  =  0.87), which required phantom calibration. For both the esophageal cancer dataset and the NHL dataset, the ARG_MC had the highest accuracy with an average DSI of 0.87 and 0.84, respectively. The ARG_MC was robust to parameter settings and region of interest selection, and it did not depend on scanners, imaging protocols, or tumor types. Furthermore, the ARG_MC made no assumption about the tumor size or tumor uptake distribution, making it suitable for segmenting tumors with heterogeneous FDG uptake. In conclusion, the ARG_MC was accurate, robust and easy to use, it provides a highly potential tool for PET tumor segmentation in clinic.

  20. A region growing method for tumor volume segmentation on PET images for rectal and anal cancer patients.

    Science.gov (United States)

    Day, Ellen; Betler, James; Parda, David; Reitz, Bodo; Kirichenko, Alexander; Mohammadi, Seyed; Miften, Moyed

    2009-10-01

    The application of automated segmentation methods for tumor delineation on 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) images presents an opportunity to reduce the interobserver variability in radiotherapy (RT) treatment planning. In this work, three segmentation methods were evaluated and compared for rectal and anal cancer patients: (i) Percentage of the maximum standardized uptake value (SUV% max), (ii) fixed SUV cutoff of 2.5 (SUV2.5), and (iii) mathematical technique based on a confidence connected region growing (CCRG) method. A phantom study was performed to determine the SUV% max threshold value and found to be 43%, SUV43% max. The CCRG method is an iterative scheme that relies on the use of statistics from a specified region in the tumor. The scheme is initialized by a subregion of pixels surrounding the maximum intensity pixel. The mean and standard deviation of this region are measured and the pixels connected to the region are included or not based on the criterion that they are greater than a value derived from the mean and standard deviation. The mean and standard deviation of this new region are then measured and the process repeats. FDG-PET-CT imaging studies for 18 patients who received RT were used to evaluate the segmentation methods. A PET avid (PETavid) region was manually segmented for each patient and the volume was then used to compare the calculated volumes along with the absolute mean difference and range for all methods. For the SUV43% max method, the volumes were always smaller than the PETavid volume by a mean of 56% and a range of 21%-79%. The volumes from the SUV2.5 method were either smaller or larger than the PETavid volume by a mean of 37% and a range of 2%-130%. The CCRG approach provided the best results with a mean difference of 9% and a range of 1%-27%. Results show that the CCRG technique can be used in the segmentation of tumor volumes on FDG-PET images, thus providing treatment planners with a clinically

  1. Combining GIS with fuzzy multicriteria decision-making for landfill siting in a fast-growing urban region.

    Science.gov (United States)

    Chang, Ni-Bin; Parvathinathan, G; Breeden, Jeff B

    2008-04-01

    Landfill siting is a difficult, complex, tedious, and protracted process requiring evaluation of many different criteria. This paper presents a fuzzy multicriteria decision analysis alongside with a geospatial analysis for the selection of landfill sites. It employs a two-stage analysis synergistically to form a spatial decision support system (SDSS) for waste management in a fast-growing urban region, south Texas. The first-stage analysis makes use of the thematic maps in Geographical information system (GIS) in conjunction with environmental, biophysical, ecological, and socioeconomic variables leading to support the second-stage analysis using the fuzzy multicriteria decision-making (FMCDM) as a tool. It differs from the conventional methods of integrating GIS with MCDM for landfill selection because the approach follows two sequential steps rather than a full-integrated scheme. The case study was made for the city of Harlingen in south Texas, which is rapidly evolving into a large urban area due to its vantage position near the US-Mexico borderlands. The purpose of GIS was to perform an initial screening process to eliminate unsuitable land followed by utilization of FMCDM method to identify the most suitable site using the information provided by the regional experts with reference to five chosen criteria. Research findings show that the proposed SDSS may aid in recognizing the pros and cons of potential areas for the localization of landfill sites in any study region. Based on initial GIS screening and final FMCDM assessment, "site 1" was selected as the most suitable site for the new landfill in the suburban area of the City of Harlingen. Sensitivity analysis was performed using Monte Carlo simulation where the decision weights associated with all criteria were varied to investigate their relative impacts on the rank ordering of the potential sites in the second stage. Despite variations of the decision weights within a range of 20%, it shows that "site 1

  2. Response of two-phase droplets to intense electromagnetic radiation

    Science.gov (United States)

    Spann, James F.; Maloney, Daniel J.; Lawson, William F.; Casleton, Kent H.

    1993-04-01

    The behavior of two-phase droplets subjected to high intensity radiation pulses is studied. Droplets are highly absorbing solids in weakly absorbing liquid medium. The objective of the study was to define heating thresholds required for causing explosive boiling and secondary atomization of the fuel droplet. The results point to mechanisms for energy storage and transport in two-phase systems.

  3. Two-Phase Technology at NASA/Johnson Space Center

    Science.gov (United States)

    Ungar, Eugene K.; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    Since the baseline International Space Station (ISS) External Active Thermal Control System (EATCS) was changed from a two-phase mechanically pumped system to a single phase cascade system in the fall of 1993, two-phase EATCS research has continued at a low level at JSC. One of-the lessons of the ISS EATCS selection was that two-phase thermal control systems must have significantly lower power than comparable single phase systems to overcome their larger radiator area, larger line and fluid mass, and perceived higher technical risk. Therefore, research at JSC has concentrated on low power mechanically pumped two-phase EATCSs. In the presentation, the results of a study investigating the trade of single and two-phase mechanically pumped EATCSs for space vehicles will be summarized. The low power two-phase mechanically pumped EATCS system under development at JSC will be described in detail and the current design status of the subscale test unit will be reviewed. Also, performance predictions for a full size EATCS will be presented. In addition to the discussion of two-phase mechanically pumped EATCS development at JSC, two-phase technologies under development for biological water processing will be discussed. These biological water processor technologies are being prepared for a 2001 flight experiment and subsequent usage on the TransHab module on the International Space Station.

  4. Two Phases of Coherent Structure Motions in Turbulent Boundary Layer

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Hua; JIANG Nan

    2007-01-01

    Two phases of coherent structure motion are acquired after obtaining conditional phase-averaged waveforms for longitudinal velocity of coherent structures in turbulent boundary layer based on Harr wavelet transfer. The correspondences of the two phases to the two processes (i.e. ejection and sweep) during a burst are determined.

  5. SEGMENTACIÓN DE FRUTOS DE CAFÉ MEDIANTE MÉTODOS DE CRECIMIENTO DE REGIONES SEGMENTATION OF COFFEE BEANS BY MEANS OF SEEDED REGION GROWING TECHNIQUES

    Directory of Open Access Journals (Sweden)

    Julián Andrés Betancur Acevedo

    2006-06-01

    Full Text Available Se presentan tres diferentes sistemas de segmentación los cuales utilizan la técnica de crecimiento de regiones a partir de semillas SRG (Seeded Region Growing. El primero de ellos, llamado Sistema Euclídeo, hace uso de la distancia euclídea con el fin de encontrar la región de interés (grano de café. El Sistema ACB-PCB utiliza dos medidas de discontinuidad llamadas contraste promedio y contraste periférico, las cuales se derivan del promedio de las componentes de color de los pıxeles que conforman la región y aquellos que conforman dos de sus contornos. Luego de un proceso iterativo, se halla el contorno de contraste promedio ACB y el contorno de contraste periférico PCB, que se usan para segmentar el grano de café. Por último, el Sistema Híbrido utiliza la información de las principales componentes geométricas presentes en la escena (dadas por un Detector de Bordes de Color, y la medida de contraste promedio. Las herramientas de segmentación fueron aplicadas a imágenes de frutos de café, adquiridas bajo condiciones controladas. Los resultados obtenidos muestran un buen desempeño del detector de bordes de color implementado, así como de los sistemas de segmentación, en especial de los sistemas ACB-PCB e Híbrido.Three segmentation systems are presented which use the Seeded Region Growing Technique SRG. The first one, called the Euclidean System, uses a Euclidean distance measure in order to find the region of interest (coffee bean. The ACB-PCB System uses two discontinuity measures called average contrast and peripheral contrast, which are derived from the mean of the color components of the pixels that form the region and those that form two of its boundaries. Following an iterative process, the Average Contrast Boundary ACB and the Peripheral Contrast Boundary PCB are computed for use in performing the coffee bean segmentation. Finally, the Hybrid System uses both information from the principal geometrical components in

  6. SU-C-9A-01: Parameter Optimization in Adaptive Region-Growing for Tumor Segmentation in PET

    Energy Technology Data Exchange (ETDEWEB)

    Tan, S [University of Maryland School of Medicine, Baltimore, MD (United States); Huazhong University of Science and Technology, Wuhan, Hubei (China); Xue, M; Chen, W; D' Souza, W; Lu, W [University of Maryland School of Medicine, Baltimore, MD (United States); Li, H [Washington University School of Medicine, Saint Louis, MO. (United States)

    2014-06-01

    Purpose: To design a reliable method to determine the optimal parameter in the adaptive region-growing (ARG) algorithm for tumor segmentation in PET. Methods: The ARG uses an adaptive similarity criterion m - fσ ≤ I-PET ≤ m + fσ, so that a neighboring voxel is appended to the region based on its similarity to the current region. When increasing the relaxing factor f (f ≥ 0), the resulting volumes monotonically increased with a sharp increase when the region just grew into the background. The optimal f that separates the tumor from the background is defined as the first point with the local maximum curvature on an Error function fitted to the f-volume curve. The ARG was tested on a tumor segmentation Benchmark that includes ten lung cancer patients with 3D pathologic tumor volume as ground truth. For comparison, the widely used 42% and 50% SUVmax thresholding, Otsu optimal thresholding, Active Contours (AC), Geodesic Active Contours (GAC), and Graph Cuts (GC) methods were tested. The dice similarity index (DSI), volume error (VE), and maximum axis length error (MALE) were calculated to evaluate the segmentation accuracy. Results: The ARG provided the highest accuracy among all tested methods. Specifically, the ARG has an average DSI, VE, and MALE of 0.71, 0.29, and 0.16, respectively, better than the absolute 42% thresholding (DSI=0.67, VE= 0.57, and MALE=0.23), the relative 42% thresholding (DSI=0.62, VE= 0.41, and MALE=0.23), the absolute 50% thresholding (DSI=0.62, VE=0.48, and MALE=0.21), the relative 50% thresholding (DSI=0.48, VE=0.54, and MALE=0.26), OTSU (DSI=0.44, VE=0.63, and MALE=0.30), AC (DSI=0.46, VE= 0.85, and MALE=0.47), GAC (DSI=0.40, VE= 0.85, and MALE=0.46) and GC (DSI=0.66, VE= 0.54, and MALE=0.21) methods. Conclusions: The results suggest that the proposed method reliably identified the optimal relaxing factor in ARG for tumor segmentation in PET. This work was supported in part by National Cancer Institute Grant R01 CA172638; The

  7. Developing Inventory Projection Models Using Empirical Net Forest Growth and Growing-Stock Density Relationships Across U.S. Regions and Species Group

    Science.gov (United States)

    Prakash Nepal; Peter J. Ince; Kenneth E. Skog; Sun J. Chang

    2012-01-01

    This paper describes a set of empirical net forest growth models based on forest growing-stock density relationships for three U.S. regions (North, South, and West) and two species groups (softwoods and hardwoods) at the regional aggregate level. The growth models accurately predict historical U.S. timber inventory trends when we incorporate historical timber harvests...

  8. Two Phase Flow Mapping and Transition Under Microgravity Conditions

    Science.gov (United States)

    Parang, Masood; Chao, David F.

    1998-01-01

    In this paper, recent microgravity two-phase flow data for air-water, air-water-glycerin, and air- water-Zonyl FSP mixtures are analyzed for transition from bubbly to slug and from slug to annular flow. It is found that Weber number-based maps are inadequate to predict flow-pattern transition, especially over a wide range of liquid flow rates. It is further shown that slug to annular flow transition is dependent on liquid phase Reynolds number at high liquid flow rate. This effect may be attributed to growing importance of liquid phase inertia in the dynamics of the phase flow and distribution. As a result a new form of scaling is introduced to present data using liquid Weber number based on vapor and liquid superficial velocities and Reynolds number based on liquid superficial velocity. This new combination of the dimensionless parameters seem to be more appropriate for the presentation of the microgravity data and provides a better flow pattern prediction and should be considered for evaluation with data obtained in the future. Similarly, the analysis of bubble to slug flow transition indicates a strong dependence on both liquid inertia and turbulence fluctuations which seem to play a significant role on this transition at high values of liquid velocity. A revised mapping of data using a new group of dimensionless parameters show a better and more consistent description of flow transition over a wide range of liquid flow rates. Further evaluation of the proposed flow transition mapping will have to be made after a wider range of microgravity data become available.

  9. A modified Seeded Region Growing algorithm for vessel segmentation in breast MRI images for investigating the nature of potential lesions

    Science.gov (United States)

    Glotsos, D.; Vassiou, K.; Kostopoulos, S.; Lavdas, El; Kalatzis, I.; Asvestas, P.; Arvanitis, D. L.; Fezoulidis, I. V.; Cavouras, D.

    2014-03-01

    The role of Magnetic Resonance Imaging (MRI) as an alternative protocol for screening of breast cancer has been intensively investigated during the past decade. Preliminary research results have indicated that gadolinium-agent administrative MRI scans may reveal the nature of breast lesions by analyzing the contrast-agent's uptake time. In this study, we attempt to deduce the same conclusion, however, from a different perspective by investigating, using image processing, the vascular network of the breast at two different time intervals following the administration of gadolinium. Twenty cases obtained from a 3.0-T MRI system (SIGNA HDx; GE Healthcare) were included in the study. A new modification of the Seeded Region Growing (SRG) algorithm was used to segment vessels from surrounding background. Delineated vessels were investigated by means of their topology, morphology and texture. Results have shown that it is possible to estimate the nature of the lesions with approximately 94.4% accuracy, thus, it may be claimed that the breast vascular network does encodes useful, patterned, information, which can be used for characterizing breast lesions.

  10. Thermo-Fluid Dynamics of Two-Phase Flow

    CERN Document Server

    Ishii, Mamrou

    2011-01-01

    "Thermo-fluid Dynamics of Two-Phase Flow, Second Edition" is focused on the fundamental physics of two-phase flow. The authors present the detailed theoretical foundation of multi-phase flow thermo-fluid dynamics as they apply to: Nuclear reactor transient and accident analysis; Energy systems; Power generation systems; Chemical reactors and process systems; Space propulsion; Transport processes. This edition features updates on two-phase flow formulation and constitutive equations and CFD simulation codes such as FLUENT and CFX, new coverage of the lift force model, which is of part

  11. Critical transport velocity in two-phase, horizontal pipe flow

    Energy Technology Data Exchange (ETDEWEB)

    Sommerville, D. (U.S. Army Chemical Research, Development and Engineering Center, Aberdeen Proving Grounds, MD (US))

    1991-02-01

    This paper reports on the suspension of solid particles or entrainment of liquid droplets in two- phase flow. Theoretical and empirical relationships have been derived for both instances without any consideration to the similarities between the two. However, a general relation for two-phase flow is desirable since there are systems that cannot be readily defined due to the dual (solid/liquid) nature of the transported material, such as colloids, pulp, slurries, and sludge. Using turbulence theory, one general equation can be derived to predict critical transport velocities for two-phase horizontal flow.

  12. What types of investors generate the two-phase phenomenon?

    Science.gov (United States)

    Ryu, Doojin

    2013-12-01

    We examine the two-phase phenomenon described by Plerou, Gopikrishnan, and Stanley (2003) [1] in the KOSPI 200 options market, one of the most liquid options markets in the world. By analysing a unique intraday dataset that contains information about investor type for each trade and quote, we find that the two-phase phenomenon is generated primarily by domestic individual investors, who are generally considered to be uninformed and noisy traders. In contrast, our empirical results indicate that trades by foreign institutions, who are generally considered informed and sophisticated investors, do not exhibit two-phase behaviour.

  13. Tunable two-phase coexistence in half-doped manganites

    Indian Academy of Sciences (India)

    P Chaddah; A Banerjee

    2008-02-01

    We discuss our very interesting experimental observation that the low-temperature two-phase coexistence in half-doped manganites is multi-valued (at any field) in that we can tune the coexisting antiferromagnetic-insulating (AF-I) and the ferromagnetic-metallic (FM-M) phase fractions by following different paths in (; ) space. We have shown experimentally that the phase fraction, in this two-phase coexistence, can take continuous infinity of values. All but one of these are metastable, and two-phase coexistence is not an equilibrium state.

  14. A Multi-Level Approach to Modeling Rapidly Growing Mega-Regions as a Coupled Human-Natural System

    Science.gov (United States)

    Koch, J. A.; Tang, W.; Meentemeyer, R. K.

    2013-12-01

    The FUTure Urban-Regional Environment Simulation (FUTURES) integrates information on nonstationary drivers of land change (per capita land area demand, site suitability, and spatial structure of conversion events) into spatial-temporal projections of changes in landscape patterns (Meentemeyer et al., 2013). One striking feature of FUTURES is its patch-growth algorithm that includes feedback effects of former development events across several temporal and spatial scales: cell-level transition events are aggregated into patches of land change and their further growth is based on empirically derived parameters controlling its size, shape, and dispersion. Here, we augment the FUTURES modeling framework by expanding its multilevel structure and its representation of human decision making. The new modeling framework is hierarchically organized as nested subsystems including the latest theory on telecouplings in coupled human-natural systems (Liu et al., 2013). Each subsystem represents a specific level of spatial scale and embraces agents that have decision making authority at a particular level. The subsystems are characterized with regard to their spatial representation and are connected via flows of information (e.g. regulations and policies) or material (e.g. population migration). To provide a modeling framework that is applicable to a wide range of settings and geographical regions and to keep it computationally manageable, we implement a 'zooming factor' that allows to enable or disable subsystems (and hence the represented processes), based on the extent of the study region. The implementation of the FUTURES modeling framework for a specific case study follows the observational modeling approach described in Grimm et al. (2005), starting from the analysis of empirical data in order to capture the processes relevant for specific scales and to allow a rigorous calibration and validation of the model application. In this paper, we give an introduction to the basic

  15. India Should Develop Its Naval Power in View of Growing Potential Security Concerns Connected to China’s Non-Transparent Intentions in the Indian Ocean Region

    Science.gov (United States)

    2017-06-09

    INDIAN OCEAN REGION A thesis presented to the Faculty of the U.S. Army Command and General Staff College in partial fulfillment of the...its naval power in view of growing potential security concerns connected to China’s non-transparent intentions in the Indian Ocean Region 5a...across the Indian Ocean is central to interests of India and China. Hence, both have increased their regional presence using diplomatic, economic, and

  16. Climatic warming above the Arctic Circle: are there trends in timing and length of the thermal growing season in Murmansk Region (Russia) between 1951 and 2012?

    Science.gov (United States)

    Blinova, Ilona; Chmielewski, Frank-Michael

    2015-06-01

    Anomalies in the timing of the thermal growing season have become obvious in the NE part of Fennoscandia since 2000. They are in accordance with climatic changes reported for Europe and Fennoscandia. The actual length of the growing season reached 120 days on average, onset on 30 May and ending on 27 September (1981-2010). Shifts in the timing of the growing season and its mean prolongation by 18.5 days/62a are demonstrated for Murmansk Region (1951-2012). In this period, the onset of the growing season advanced by 7.1 days/62a, while the end was extended by 11.4 days/62a. The delay in the end of the growing season is similar to the entire Fennoscandian pattern but it has not been detected in the rest of Europe. The regional pattern of climatic regimes in Murmansk Region remained stable in comparison with earlier climatic maps (1971). However, the actual shifts in the timing of the growing season were more pronounced in colder (oceanic and mountainous) parts. Recent climatic trends could influence the retreat of the tundra zone and changes in the forest line. Losses of tundra biodiversity and enrichment of the northern taiga by southern species could be expected from present climatic trends.

  17. Time dependent two phase flows in Magnetohydrodynamics: A ...

    African Journals Online (AJOL)

    Journal of the Nigerian Association of Mathematical Physics ... Open Access DOWNLOAD FULL TEXT Subscription or Fee Access. Time dependent two phase flows in Magnetohydrodynamics: A Greens function approach. BK Jha, HM Jibril ...

  18. Gravity Independence of Microchannel Two-Phase Flow Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Most of the amassed two-phase flow and heat transfer knowledge comes from experiments conducted in Earth’s gravity. Space missions span varying gravity levels,...

  19. Vapor Compressor Driven Hybrid Two-Phase Loop Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Phase I project successfully demonstrated the feasibility of the vapor compression hybrid two-phase loop (VCHTPL). The test results showed the high...

  20. TWO PHASE FLOW SPLIT MODEL FOR PARALLEL CHANNELS

    African Journals Online (AJOL)

    Ifeanyichukwu Onwuka

    The equations are solved using the Broyden'smethod ... channel system subjected to a two-phase flow transient, and the results have been very .... system pressure, the heat addition rates inside ... three dimensional flows in the LP.

  1. Particle modulations to turbulence in two-phase round jets

    Institute of Scientific and Technical Information of China (English)

    Bing Wang; Huiqiang Zhang; Yi Liu; Xiaofen Yan; Xilin Wang

    2009-01-01

    The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer (PDA). Laden with very large particles, no significant attenuations of turbulence intensities were measured in the far-fields, due to small two-phase slip velocities and particle Reynolds number. The gas-phase turbulence is enhanced by particles in the near-fields, but it is significantly attenuated by the small particles in the far-fields. The smaller particles have a more profound effect on the attenuation of turbulence intensities. The enhancements or attenuations of turbulence intensities in the far-fields depends on the energy production, transport and dissipation mechanisms between the two phases, which are determined by the particle prop-erties and two-phase velocity slips. The non-dimensional parameter CTI is introduced to represent the change of turbulence intensity.

  2. Transient two-phase performance of LOFT reactor coolant pumps

    Energy Technology Data Exchange (ETDEWEB)

    Chen, T.H.; Modro, S.M.

    1983-01-01

    Performance characteristics of Loss-of-Fluid Test (LOFT) reactor coolant pumps under transient two-phase flow conditions were obtained based on the analysis of two large and small break loss-of-coolant experiments conducted at the LOFT facility. Emphasis is placed on the evaluation of the transient two-phase flow effects on the LOFT reactor coolant pump performance during the first quadrant operation. The measured pump characteristics are presented as functions of pump void fraction which was determined based on the measured density. The calculated pump characteristics such as pump head, torque (or hydraulic torque), and efficiency are also determined as functions of pump void fractions. The importance of accurate modeling of the reactor coolant pump performance under two-phase conditions is addressed. The analytical pump model, currently used in most reactor analysis codes to predict transient two-phase pump behavior, is assessed.

  3. Scaling of Two-Phase Systems Across Gravity Levels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — There is a defined need for long term earth based testing for the development and deployment of two-phase flow systems in reduced-gravity, including lunar gravity,...

  4. Selección de Píxel Semilla mediante Wavelets para Crecimiento por Regiones Difuso (Selection of Seed Pixel Through Wavelets for Fuzzy Region Growing

    Directory of Open Access Journals (Sweden)

    Damián Valdés Santiago

    2015-08-01

    Full Text Available RESUMEN El análisis de masas y tumores en mamografía es un problema difícil porque los signos del cáncer pueden ser mínimos o estar superpuestos en el tejido. Las técnicas de procesamiento de imágenes pueden mejorar el diagnóstico reduciendo los costos. La detección de masas es un reto debido al bajo contraste y la pobre definición de los bordes. Una solución al problema es representar una masa mediante conjuntos difusos. En este trabajo se estudia la propuesta de Guliato et al. que plantean dos métodos de segmentación difusos. El primero determina el borde de una masa por crecimiento por regiones clásico, luego de un preprocesamiento difuso de la región de interés. El segundo es un método de crecimiento por regiones difuso. Estos métodos necesitan un píxel semilla y un umbral. En este trabajo se propone una selección automática del píxel semilla mediante la selección de píxeles muy correlacionados según la transformada wavelet de la imagen. Como medida de evaluación en la segmentación, se emplea la medida de ambigüedad definida por los autores citados. Con la selección de semilla propuesta se obtienen mejores resultados en la segmentación, respecto al uso de una semilla aleatoria. ABSTRACT The analysis of masses and tumors in mammography is difficult because developing signs of cancer may be minimal or masked by superimposed tissues. Image analysis techniques have the potential to improve the diagnostic accuracy of mammography, and reduce health-care costs. Detection of breast masses is a challenging problem due to low contrast and poor definition of their boundaries. An alternative to address this problem is to represent tumor or mass regions by fuzzy sets. In this paper, two methods of fuzzy segmentation proposed by Guliato et al. are studied. The first method determines the boundary of a mass by classic region growing after a fuzzy preprocessing step. The second method is a fuzzy region-growing method. This

  5. Two-phase cooling fluids; Les fluides frigoporteurs diphasiques

    Energy Technology Data Exchange (ETDEWEB)

    Lallemand, A. [Institut National des Sciences Appliquees (INSA), 69 - Lyon (France)

    1997-12-31

    In the framework of the diminution of heat transfer fluid consumption, the concept of indirect refrigerating circuits, using cooling intermediate fluids, is reviewed and the fluids that are currently used in these systems are described. Two-phase cooling fluids advantages over single-phase fluids are presented with their thermophysical characteristics: solid fraction, two-phase mixture enthalpy, thermal and rheological properties, determination of heat and mass transfer characteristics, and cold storage through ice slurry

  6. Spatiotemporal properties of growing season indices during 1961-2010 and possible association with agroclimatological regionalization of dominant crops in Xinjiang, China

    Science.gov (United States)

    Ci, Hui; Zhang, Qiang; Singh, Vijay P.; Xiao, Mingzhong; Liu, Lin

    2016-08-01

    Variations of frost days and growing season length (GSL) have been drawing increasing attention due to their impact on agriculture. The Xinjiang region in China is climatically an arid region and plays an important role in agriculture development. In this study, the GSL and frost events are analyzed in both space and time, based on the daily minimum, mean and maximum air surface temperature data covering a period of 1961-2010. Results indicate that: (1) a significant lengthening of GSL is detected during 1961-2010 in Xinjiang, China. The increasing rate of GSL over Xinjiang is about 2.5 days per decade. Besides, the starting time of growing season is 0.7 days earlier per decade and the ending time is 1.6 days later per decade. Generally, GSL in southern Xinjiang has larger increasing magnitude when compared to other regions of Xinjiang; (2) longer GSL and larger changing magnitude of growing season start (GSS), growing season end (GSE) and GSL in southern Xinjiang implies higher sensitivity of the growing season response to climate warming. Besides, GSL is in close relation with latitude, and higher latitude usually corresponds to later start and earlier end of growing season, and hence shorter GSL. In general, a northward increase of 1° latitude triggers an 8-day delay of the starting time of growing season, 6-day advance of the ending time of growing season, and thus the GSL is 14 days shorter; (3) GSL under different rates can reflect light and heat resources over Xinjiang. The GSL related to 80 % guarantee rate is 5-14 days shorter than the long-term annual mean GSL; (4) Lengthening of GSL has the potential to increase agricultural production. However, negative influences by climate warming, such as enhanced evapotranspiration, increasing weeds, insects, and pathogen-mediated plant diseases, should also be considered in planning, management and development of agriculture in Xinjiang.

  7. Two-phase application of multi-objective genetic algorithms in green building design

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.; Zmeureanu, R. [Concordia Univ., Centre for Building Studies, Montreal, PQ (Canada). Dept. of Building, Civil and Environmental Engineering; Rivard, H. [Ecole de Technologie Superieure, Montreal, PQ (Canada). Dept. of Construction Engineering

    2005-07-01

    The application of multi-objective genetic algorithms for green building design in two phases were presented in order to better help designers in the decision-making process. The purpose is to minimize two conflicting criteria: the life-cycle cost and the life-cycle environmental impact. Environmental impact criteria examined include energy and non-energy natural resources, global warming, and acidification. Variables focus on building envelope-related parameters. The application of multi-objective genetic algorithms is divided into two phases. The first phase intends to help designers in understanding the trade-off relationship between the two conflicting criteria. The second phase intends to refine the performance region that is of the designer's interest. The results after the two-phase application of the multi objective genetic algorithm were then presented. 13 refs., 4 tabs., 3 figs.

  8. A Derivation of the Nonlocal Volume-Averaged Equations for Two-Phase Flow Transport

    Directory of Open Access Journals (Sweden)

    Gilberto Espinosa-Paredes

    2012-01-01

    Full Text Available In this paper a detailed derivation of the general transport equations for two-phase systems using a method based on nonlocal volume averaging is presented. The local volume averaging equations are commonly applied in nuclear reactor system for optimal design and safe operation. Unfortunately, these equations are limited to length-scale restriction and according with the theory of the averaging volume method, these fail in transition of the flow patterns and boundaries between two-phase flow and solid, which produce rapid changes in the physical properties and void fraction. The non-local volume averaging equations derived in this work contain new terms related with non-local transport effects due to accumulation, convection diffusion and transport properties for two-phase flow; for instance, they can be applied in the boundary between a two-phase flow and a solid phase, or in the boundary of the transition region of two-phase flows where the local volume averaging equations fail.

  9. New Results in Two-Phase Pressure Drop Calculations at Reduced Gravity Conditions

    Science.gov (United States)

    Braisted, Jon; Kurwitz, Cable; Best, Frederick

    2004-02-01

    The mass, power, and volume energy savings of two-phase systems for future spacecraft creates many advantages over current single-phase systems. Current models of two-phase phenomena such as pressure drop, void fraction, and flow regime prediction are still not well defined for space applications. Commercially available two-phase modeling software has been developed for a large range of acceleration fields including reduced-gravity conditions. Recently, a two-phase experiment has been flown to expand the two-phase database. A model of the experiment was created in the software to determine how well the software could predict the pressure drop observed in the experiment. Of the simulations conducted, the computer model shows good agreement of the pressure drop in the experiment to within 30%. However, the software does begin to over-predict pressure drop in certain regions of a flow regime map indicating that some models used in the software package for reduced-gravity modeling need improvement.

  10. Combining Remote Sensing and Landscape Metrics to monitor Urban Spatial Variation - Examples from Growing and Shrinking Regions

    Science.gov (United States)

    Netzband, M.

    2011-12-01

    also fragmentation of recreational sites within metropolitan areas and of built-up areas within green spaces in suburban areas. Dynamic urban area indicators refer to typology of changes and the transition from one land-use class to another. A methodological approach is presented applied to different parts of Europe in growing as well as shrinking urban regions, after which monitoring and evaluation of a landscape diversity in suburban landscapes are feasible on the basis of medium and high resolution satellite data.

  11. Numerical investigation of the mechanism of two-phase flow instability in parallel narrow channels

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Lian [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University (China); Chen, Deqi, E-mail: chendeqi@cqu.edu.cn [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University (China); CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology, Nuclear Power Institute of China, Chengdu 610041 (China); Huang, Yanping, E-mail: hyanping007@163.com [CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology, Nuclear Power Institute of China, Chengdu 610041 (China); Yuan, Dewen; Wang, Yanling [CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology, Nuclear Power Institute of China, Chengdu 610041 (China); Pan, Liangming [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University (China)

    2015-06-15

    Highlights: • A mathematical model is proposed to predict the two-phase flow instability. • The mathematical model predicted result agrees well with the experimental result. • Oscillation characteristics of the two-phase flow instability is discussed in detail. - Abstract: In this paper, the mechanism of two-phase flow instability in parallel narrow channels is studied theoretically, and the characteristic of the flow instability is discussed in detail. Due to the significant confining effect of the narrow channel on the vapor–liquid interface, the two-phase flow resistance in the narrow channel is probably different from that in conventional channel. Therefore, the vapor confined number (N{sub conf}), defined by the size of narrow channel and bubble detachment diameter, is considered in the “Chisholm B model” to investigate the two-phase flow pressure drop. The flow instability boundaries are plotted in parameter plane with phase-change-number (N{sub pch}) and subcooling-number (N{sub sub}) under different working conditions. It is found that the predicted result agrees well with the experimental result. According to the predicted result, the oscillation behaviors near the flow instability boundary indicate that the Supercritical Hopf bifurcation appears in high sub-cooled region and the Subcritical Hopf bifurcation appears in low sub-cooled region. Also, a detailed analysis about the effects of key parameters on the characteristic of two-phase flow instability and the flow instability boundary is proposed, including the effects of inlet subcooling, heating power, void distribution parameter and drift velocity.

  12. A Hybrid Technique Based on Combining Fuzzy K-means Clustering and Region Growing for Improving Gray Matter and White Matter Segmentation

    Directory of Open Access Journals (Sweden)

    Ashraf Afifi

    2012-07-01

    Full Text Available In this paper we present a hybrid approach based on combining fuzzy k-means clustering, seed region growing, and sensitivity and specificity algorithms to measure gray (GM and white matter (WM tissue. The proposed algorithm uses intensity and anatomic information for segmenting of MRIs into different tissue classes, especially GM and WM. It starts by partitioning the image into different clusters using fuzzy k-means clustering. The centers of these clusters are the input to the region growing (SRG method for creating the closed regions. The outputs of SRG technique are fed to sensitivity and specificity algorithm to merge the similar regions in one segment. The proposed algorithm is applied to challenging applications: gray matter/white matter segmentation in magnetic resonance image (MRI datasets. The experimental results show that the proposed technique produces accurate and stable results.

  13. Mathematical modeling of disperse two-phase flows

    CERN Document Server

    Morel, Christophe

    2015-01-01

    This book develops the theoretical foundations of disperse two-phase flows, which are characterized by the existence of bubbles, droplets or solid particles finely dispersed in a carrier fluid, which can be a liquid or a gas. Chapters clarify many difficult subjects, including modeling of the interfacial area concentration. Basic knowledge of the subjects treated in this book is essential to practitioners of Computational Fluid Dynamics for two-phase flows in a variety of industrial and environmental settings. The author provides a complete derivation of the basic equations, followed by more advanced subjects like turbulence equations for the two phases (continuous and disperse) and multi-size particulate flow modeling. As well as theoretical material, readers will discover chapters concerned with closure relations and numerical issues. Many physical models are presented, covering key subjects including heat and mass transfers between phases, interfacial forces and fluid particles coalescence and breakup, a...

  14. A SAS Package for Logistic Two-Phase Studies

    Directory of Open Access Journals (Sweden)

    Walter Schill

    2014-04-01

    Full Text Available Two-phase designs, in which for a large study a dichotomous outcome and partial or proxy information on risk factors is available, whereas precise or complete measurements on covariates have been obtained only in a stratified sub-sample, extend the standard case-control design and have been proven useful in practice. The application of two-phase designs, however, seems to be hampered by the lack of appropriate, easy-to-use software. This paper introduces sas-twophase-package, a collection of SAS-macros, to fulfill this task. sas-twophase-package implements weighted likelihood, pseudo likelihood and semi- parametric maximum likelihood estimation via the EM algorithm and via profile likelihood in two-phase settings with dichotomous outcome and a given stratification.

  15. Two-Phase flow instrumentation for nuclear accidents simulation

    Science.gov (United States)

    Monni, G.; De Salve, M.; Panella, B.

    2014-11-01

    The paper presents the research work performed at the Energy Department of the Politecnico di Torino, concerning the development of two-phase flow instrumentation and of models, based on the analysis of experimental data, that are able to interpret the measurement signals. The study has been performed with particular reference to the design of power plants, such as nuclear water reactors, where the two-phase flow thermal fluid dynamics must be accurately modeled and predicted. In two-phase flow typically a set of different measurement instruments (Spool Piece - SP) must be installed in order to evaluate the mass flow rate of the phases in a large range of flow conditions (flow patterns, pressures and temperatures); moreover, an interpretative model of the SP need to be developed and experimentally verified. The investigated meters are: Turbine, Venturi, Impedance Probes, Concave sensors, Wire mesh sensor, Electrical Capacitance Probe. Different instrument combinations have been tested, and the performance of each one has been analyzed.

  16. A mechanical erosion model for two-phase mass flows

    CERN Document Server

    Pudasaini, Shiva P

    2016-01-01

    Erosion, entrainment and deposition are complex and dominant, but yet poorly understood, mechanical processes in geophysical mass flows. Here, we propose a novel, process-based, two-phase, erosion-deposition model capable of adequately describing these complex phenomena commonly observed in landslides, avalanches, debris flows and bedload transport. The model is based on the jump in the momentum flux including changes of material and flow properties along the flow-bed interface and enhances an existing general two-phase mass flow model (Pudasaini, 2012). A two-phase variably saturated erodible basal morphology is introduced and allows for the evolution of erosion-deposition-depths, incorporating the inherent physical process including momentum and rheological changes of the flowing mixture. By rigorous derivation, we show that appropriate incorporation of the mass and momentum productions or losses in conservative model formulation is essential for the physically correct and mathematically consistent descript...

  17. Simulating confined swirling gas-solid two phase jet

    Institute of Scientific and Technical Information of China (English)

    金晗辉; 夏钧; 樊建人; 岑可法

    2002-01-01

    A k-ε-kp multi-fluid model was used to simulate confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. After considering the drag force between the two phases and gravity, a series of numerical simulations of the two-phase flow of 30μm, 45μm, 60μm diameter particles were performed on a x×r=50×50 mesh grid respectively. The results showed that the k-ε-kp multi-fluid model can be applied to predict moderate swirling multi-phase flow. When the particle diameter is large, the collision of the particles with the wall will influence the prediction accuracy. The bigger the diameter of the particles, the stronger the collision with the wall, and the more obvious the difference between measured and calculated results.

  18. Numerical methods for two-phase flow with contact lines

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Clauido

    2012-07-01

    This thesis focuses on numerical methods for two-phase flows, and especially flows with a moving contact line. Moving contact lines occur where the interface between two fluids is in contact with a solid wall. At the location where both fluids and the wall meet, the common continuum descriptions for fluids are not longer valid, since the dynamics around such a contact line are governed by interactions at the molecular level. Therefore the standard numerical continuum models have to be adjusted to handle moving contact lines. In the main part of the thesis a method to manipulate the position and the velocity of a contact line in a two-phase solver, is described. The Navier-Stokes equations are discretized using an explicit finite difference method on a staggered grid. The position of the interface is tracked with the level set method and the discontinuities at the interface are treated in a sharp manner with the ghost fluid method. The contact line is tracked explicitly and its dynamics can be described by an arbitrary function. The key part of the procedure is to enforce a coupling between the contact line and the Navier-Stokes equations as well as the level set method. Results for different contact line models are presented and it is demonstrated that they are in agreement with analytical solutions or results reported in the literature.The presented Navier-Stokes solver is applied as a part in a multiscale method to simulate capillary driven flows. A relation between the contact angle and the contact line velocity is computed by a phase field model resolving the micro scale dynamics in the region around the contact line. The relation of the microscale model is then used to prescribe the dynamics of the contact line in the macro scale solver. This approach allows to exploit the scale separation between the contact line dynamics and the bulk flow. Therefore coarser meshes can be applied for the macro scale flow solver compared to global phase field simulations

  19. Shock wave of vapor-liquid two-phase flow

    Institute of Scientific and Technical Information of China (English)

    Liangju ZHAO; Fei WANG; Hong GAO; Jingwen TANG; Yuexiang YUAN

    2008-01-01

    The shock wave of vapor-liquid two-phase flow in a pressure-gain steam injector is studied by build-ing a mathematic model and making calculations. The results show that after the shock, the vapor is nearly com-pletely condensed. The upstream Mach number and the volume ratio of vapor have a great effect on the shock. The pressure and Mach number of two-phase shock con-form to the shock of ideal gas. The analysis of available energy shows that the shock is an irreversible process with entropy increase.

  20. Two Phase Flow and Space-Based Applications

    Science.gov (United States)

    McQuillen, John

    1999-01-01

    A reduced gravity environment offers the ability to remove the effect of buoyancy on two phase flows whereby density differences that normally would promote relative velocities between the phases and also alter the shape of the interface are removed. However, besides being a potent research tool, there are also many space-based technologies that will either utilize or encounter two-phase flow behavior, and as a consequence, several questions must be addressed. This paper presents some of these technologies missions. Finally, this paper gives a description of web-sites for some funding.

  1. Two-phase analysis in consensus genetic mapping.

    Science.gov (United States)

    Ronin, Y; Mester, D; Minkov, D; Belotserkovski, R; Jackson, B N; Schnable, P S; Aluru, S; Korol, A

    2012-05-01

    Numerous mapping projects conducted on different species have generated an abundance of mapping data. Consequently, many multilocus maps have been constructed using diverse mapping populations and marker sets for the same organism. The quality of maps varies broadly among populations, marker sets, and software used, necessitating efforts to integrate the mapping information and generate consensus maps. The problem of consensus genetic mapping (MCGM) is by far more challenging compared with genetic mapping based on a single dataset, which by itself is also cumbersome. The additional complications introduced by consensus analysis include inter-population differences in recombination rate and exchange distribution along chromosomes; variations in dominance of the employed markers; and use of different subsets of markers in different labs. Hence, it is necessary to handle arbitrary patterns of shared sets of markers and different level of mapping data quality. In this article, we introduce a two-phase approach for solving MCGM. In phase 1, for each dataset, multilocus ordering is performed combined with iterative jackknife resampling to evaluate the stability of marker orders. In this phase, the ordering problem is reduced to the well-known traveling salesperson problem (TSP). Namely, for each dataset, we look for order that gives minimum sum of recombination distances between adjacent markers. In phase 2, the optimal consensus order of shared markers is selected from the set of allowed orders and gives the minimal sum of total lengths of nonconflicting maps of the chromosome. This criterion may be used in different modifications to take into account the variation in quality of the original data (population size, marker quality, etc.). In the foregoing formulation, consensus mapping is considered as a specific version of TSP that can be referred to as "synchronized TSP." The conflicts detected after phase 1 are resolved using either a heuristic algorithm over the

  2. Film boiling on spheres in single- and two-phase flows.

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.; Theofanous, T. G.

    2000-08-29

    Film boiling on spheres in single- and two-phase flows was studied experimentally and theoretically with an emphasis on establishing the film boiling heat transfer closure law, which is useful in the analysis of nuclear reactor core melt accidents. Systematic experimentation of film boiling on spheres in single-phase water flows was carried out to investigate the effects of liquid subcooling (from 0 to 40 C), liquid velocity (from 0 to 2 m/s), sphere superheat (from 200 to 900 C), sphere diameter (from 6 to 19 mm), and sphere material (stainless steel and brass) on film boiling heat transfer. Based on the experimental data a general film boiling heat transfer correlation is developed. Utilizing a two-phase laminar boundary-layer model for the unseparated front film region and a turbulent eddy model for the separated rear region, a theoretical model was developed to predict the film boiling heat transfer in all single-phase regimes. The film boiling from a sphere in two-phase flows was investigated both in upward two-phase flows (with void fraction from 0.2 to 0.65, water velocity from 0.6 to 3.2 m/s, and steam velocity from 3.0 to 9.0 m/s) and in downward two-phase flows (with void fraction from 0.7 to 0.95, water velocity from 1.9 to 6.5 m/s, and steam velocity from 1.1 to 9.0 m/s). The saturated single-phase heat transfer correlation was found to be applicable to the two-phase film boiling data by making use of the actual water velocity (water phase velocity), and an adjustment factor of (1 - {alpha}){sup 1/4} (with a being the void fraction) for downward flow case only. Slight adjustments of the Reynolds number exponents in the correlation provided an even better interpretation of the two-phase data. Preliminary experiments were also conducted to address the influences of multi-sphere structure on the film boiling heat transfer in single- and two-phase flows.

  3. Modelling two-phase transport of 3H/3He

    NARCIS (Netherlands)

    Visser, A.; Schaap, J.D.; Leijnse, T.; Broers, H.P.; Bierkens, M.F.P.

    2008-01-01

    Degassing of groundwater by excess denitrification of agricultural pollution complicates the interpretation of 3H/3He data and hinders the estimation of travel times in nitrate pollution studies. In this study we used a two-phase flow and transport model (STOMP) to evaluate the method presented by

  4. Two-phase alkali-metal experiments in reduced gravity

    Energy Technology Data Exchange (ETDEWEB)

    Antoniak, Z.I.

    1986-06-01

    Future space missions envision the use of large nuclear reactors utilizing either a single or a two-phase alkali-metal working fluid. The design and analysis of such reactors require state-of-the-art computer codes that can properly treat alkali-metal flow and heat transfer in a reduced-gravity environment. A literature search of relevant experiments in reduced gravity is reported on here, and reveals a paucity of data for such correlations. The few ongoing experiments in reduced gravity are noted. General plans are put forth for the reduced-gravity experiments which will have to be performed, at NASA facilities, with benign fluids. A similar situation exists regarding two-phase alkali-metal flow and heat transfer, even in normal gravity. Existing data are conflicting and indequate for the task of modeling a space reactor using a two-phase alkali-metal coolant. The major features of past experiments are described here. Data from the reduced-gravity experiments with innocuous fluids are to be combined with normal gravity data from the two-phase alkali-metal experiments. Analyses undertaken here give every expectation that the correlations developed from this data base will provide a valid representation of alkali-metal heat transfer and pressure drop in reduced gravity.

  5. Coal-Face Fracture With A Two-Phase Liquid

    Science.gov (United States)

    Collins, E. R., Jr.

    1985-01-01

    In new method for mining coal without explosive, two-phase liquid such as CO2 and water, injected at high pressure into deeper ends of holes drilled in coal face. Liquid permeates coal seam through existing microfractures; as liquid seeps back toward face, pressure eventually drops below critical value at which dissolved gas flashvaporizes, breaking up coal.

  6. Two-phase flow in micro and nanofluidic devices

    NARCIS (Netherlands)

    Shui, Lingling

    2009-01-01

    This thesis provides experimental data and theoretical analysis on two-phase flow in devices with different layouts of micrometer or nanometer-size channels. A full flow diagram is presented for oil and water flow in head-on microfluidic devices. Morphologically different flow regimes (dripping, jet

  7. Modelling two-phase transport of 3H/3He

    NARCIS (Netherlands)

    Visser, A.; Schaap, J.D.; Leijnse, T.; Broers, H.P.; Bierkens, M.F.P.

    2008-01-01

    Degassing of groundwater by excess denitrification of agricultural pollution complicates the interpretation of 3H/3He data and hinders the estimation of travel times in nitrate pollution studies. In this study we used a two-phase flow and transport model (STOMP) to evaluate the method presented by V

  8. Experimental Investigation of two-phase nitrogen Cryo transfer line

    Science.gov (United States)

    Singh, G. K.; Nimavat, H.; Panchal, R.; Garg, A.; Srikanth, GLN; Patel, K.; Shah, P.; Tanna, V. L.; Pradhan, S.

    2017-02-01

    A 6-m long liquid nitrogen based cryo transfer line has been designed, developed and tested at IPR. The test objectives include the thermo-hydraulic characteristics of Cryo transfer line under single phase as well as two phase flow conditions. It is always easy in experimentation to investigate the thermo-hydraulic parameters in case of single phase flow of cryogen but it is real challenge when one deals with the two phase flow of cryogen due to availibity of mass flow measurements (direct) under two phase flow conditions. Established models have been reported in the literature where one of the well-known model of Lockhart-Martenelli relationship has been used to determine the value of quality at the outlet of Cryo transfer line. Under homogenous flow conditions, by taking the ratio of the single-phase pressure drop and the two-phase pressure drop, we estimated the quality at the outlet. Based on these equations, vapor quality at the outlet of the transfer line was predicted at different heat loads. Experimental rresults shown that from inlet to outlet, there is a considerable increment in the pressure drop and vapour quality of the outlet depending upon heat load and mass flow rate of nitrogen flowing through the line.

  9. Numerical simulation of two-phase flow in offshore environments

    NARCIS (Netherlands)

    Wemmenhove, Rik

    2008-01-01

    Numerical Simulation of Two-Phase Flow in Offshore Environments Rik Wemmenhove Weather conditions on full sea are often violent, leading to breaking waves and lots of spray and air bubbles. As high and steep waves may lead to severe damage on ships and offshore structures, there is a great need for

  10. TWO-PHASE EJECTOR of CARBON DIOXIDE HEAT PUMP CALCULUS

    Directory of Open Access Journals (Sweden)

    Sit B.M.

    2010-12-01

    Full Text Available It is presented the calculus of the two-phase ejector for carbon dioxide heat pump. The method of calculus is based on the method elaborated by S.M. Kandil, W.E. Lear, S.A. Sherif, and is modified taking into account entrainment ratio as the input for the calculus.

  11. The Effect of Natural Disasters on Mexico’s Regional Economic Growth:Growing Disparity or Creative Destruction?

    OpenAIRE

    Andrea García Tapia, Carlos Muñoz Piña

    2014-01-01

    Over the last decade, Mexico has experienced a sharp increase in the economic costs associated with hydrometeorological disasters, most notably floods, hurricanes and droughts. This is attributed to the combination of an increasing population and expanding economic activities along Mexico’s coastal areas and arid zones with the mismanagement of its urban growth. To make it worse, risks would only grow in the future under the current basic Climate Change predictions for Mexico. While immediate...

  12. INNOVATIVE CULTURE QUINOA (CHENOPODIUM QUINOA) – THE PROSPECTS OF GROWING IN THE KRASNODAR REGION TO PRODUCE FOODS HIGH NUTRITIONAL VALUE

    OpenAIRE

    Shchekoldina T. V.; Rodionova L. Y.; Chernigovets E. A.

    2016-01-01

    Healthy nutrition is the foundation of the nation and the most important factor affecting the length of human life. Therefore, the search and the use of new sources of food are important. One of such source is the ancient culture of quinoa (Chenopodium quinoa), known as a "qinoa", "quinva" or "rice quinoa. The uniqueness of the quinoa is its chemical composition, the absence of anti-nutritional substances and unpretentious in growing and harvesting. Currently quinoa is grown in more than 70 c...

  13. [The cytogenetic effects in natural populations of Crepis tectorum L. growing in the region of the eastern Urals radioactive trace].

    Science.gov (United States)

    Shevchenko, V V; Grinikh, L I; Abramov, V I

    1998-01-01

    Genetic consequences of a prolonged action of ionizing radiation were analyzed in five natural Crepis tectorum populations growing at the radioactively contaminated territory of the East-Ural radioactive track. In these populations about 40 years after the start of a chronic irradiation an increased frequency of chromosome aberrations was found out. An additional acute gamma irradiation at the dose of 20 Gy did not reveal any changes of radioresistance of the plants investigated.

  14. A numerical method for a model of two-phase flow in a coupled free flow and porous media system

    KAUST Repository

    Chen, Jie

    2014-07-01

    In this article, we study two-phase fluid flow in coupled free flow and porous media regions. The model consists of coupled Cahn-Hilliard and Navier-Stokes equations in the free fluid region and the two-phase Darcy law in the porous medium region. We propose a Robin-Robin domain decomposition method for the coupled Navier-Stokes and Darcy system with the generalized Beavers-Joseph-Saffman condition on the interface between the free flow and the porous media regions. Numerical examples are presented to illustrate the effectiveness of this method. © 2014 Elsevier Inc.

  15. Investigations of two-phase flame propagation under microgravity conditions

    Science.gov (United States)

    Gokalp, Iskender

    2016-07-01

    Investigations of two-phase flame propagation under microgravity conditions R. Thimothée, C. Chauveau, F. Halter, I Gökalp Institut de Combustion, Aérothermique, Réactivité et Environnement (ICARE), CNRS, 1C Avenue de la Recherche Scientifique, 45071 Orléans Cedex 2, France This paper presents and discusses recent results on two-phase flame propagation experiments we carried out with mono-sized ethanol droplet aerosols under microgravity conditions. Fundamental studies on the flame propagation in fuel droplet clouds or sprays are essential for a better understanding of the combustion processes in many practical applications including internal combustion engines for cars, modern aircraft and liquid rocket engines. Compared to homogeneous gas phase combustion, the presence of a liquid phase considerably complicates the physico-chemical processes that make up combustion phenomena by coupling liquid atomization, droplet vaporization, mixing and heterogeneous combustion processes giving rise to various combustion regimes where ignition problems and flame instabilities become crucial to understand and control. Almost all applications of spray combustion occur under high pressure conditions. When a high pressure two-phase flame propagation is investigated under normal gravity conditions, sedimentation effects and strong buoyancy flows complicate the picture by inducing additional phenomena and obscuring the proper effect of the presence of the liquid droplets on flame propagation compared to gas phase flame propagation. Conducting such experiments under reduced gravity conditions is therefore helpful for the fundamental understanding of two-phase combustion. We are considering spherically propagating two-phase flames where the fuel aerosol is generated from a gaseous air-fuel mixture using the condensation technique of expansion cooling, based on the Wilson cloud chamber principle. This technique is widely recognized to create well-defined mono-size droplets

  16. A Stable Parametric Finite Element Discretization of Two-Phase Navier--Stokes Flow

    CERN Document Server

    Barrett, John W; Nürnberg, Robert

    2013-01-01

    We present a parametric finite element approximation of two-phase flow. This free boundary problem is given by the Navier--Stokes equations in the two phases, which are coupled via jump conditions across the interface. Using a novel variational formulation for the interface evolution gives rise to a natural discretization of the mean curvature of the interface. The parametric finite element approximation of the evolving interface is then coupled to a standard finite element approximation of the two-phase Navier--Stokes equations in the bulk. Here enriching the pressure approximation space with the help of an XFEM function ensures good volume conservation properties for the two phase regions. In addition, the mesh quality of the parametric approximation of the interface in general does not deteriorate over time, and an equidistribution property can be shown for a semidiscrete continuous-in-time variant of our scheme in two space dimensions. Moreover, our finite element approximation can be shown to be uncondit...

  17. MICROGRAVITY EXPERIMENTS OF TWO-PHASE FLOW PATTERNS ABOARD MIR SPACE STATION

    Institute of Scientific and Technical Information of China (English)

    赵建福; 解京昌; 林海; 胡文瑞; A.V. Ivanov; A.Yu. Belyaev

    2001-01-01

    A first experimental study on two-phase flow patterns at a long-term,steady microgravity condition was conducted on board the Russian Space Station "MIR" in August 1999. Carbogal and air are used as the liquid and the gas phase,respectively. Bubble, slug, slug-annular transitional, and annular flows are observed.A new region of annular flow with lower liquid superficial velocity is discovered,and the region of the slug-annular transitionalfiow is wider than that observed by experiments on board the parabolic aircraft. The main patterns are bubble, slug annular transitional and annular flows based on the experiments on board MIR space station. Some influences on the two-phase flow patterns in the present experiments are discussed.

  18. How fast will the registered nurse workforce grow through 2030? Projections in nine regions of the country.

    Science.gov (United States)

    Auerbach, David I; Buerhaus, Peter I; Staiger, Douglas O

    After an unprecedented increase in nursing school enrollment and graduates in the past 10 years, projected shortages of nurses have been erased at a national level. However, nursing markets are local, and an uneven distribution of health care providers of all types is a longstanding feature of health care in the United States. The purpose of this study was to understand how the outlook for future registered nurse (RN) supply varies regionally across the United States. We apply our nursing supply model to the nine U.S. Census Divisions to produce separate supply forecasts for each region. We find dramatic differences in expected future growth of the nursing workforce across U.S. regions. These range from zero expected growth in the number of RNs per capita in New England and in the Pacific regions between 2015 and 2030 to 40% growth in the East South Central region (Mississippi, Alabama, Tennessee, Kentucky) and in the West South Central region (Texas, Oklahoma, Arkansas, Louisiana). Assuming growth in the demand for RNs per population, some regions of the United States are expected to face shortfalls in their nursing workforce if recent trends do not change. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. A Simple and Efficient Diffuse Interface Method for Compressible Two-Phase Flows

    Energy Technology Data Exchange (ETDEWEB)

    Ray A. Berry; Richard Saurel; Fabien Petitpas

    2009-05-01

    In nuclear reactor safety and optimization there are key issues that rely on in-depth understanding of basic two-phase flow phenomena with heat and mass transfer. For many reasons, to be discussed, there is growing interest in the application of two-phase flow models to provide diffuse, but nevertheless resolved, simulation of interfaces between two immiscible compressible fluids – diffuse interface method (DIM). Because of its ability to dynamically create interfaces and to solve interfaces separating pure media and mixtures for DNS-like (Direct Numerical Simulation) simulations of interfacial flows, we examine the construction of a simple, robust, fast, and accurate numerical formulation for the 5-equation Kapila et al. [1] reduced two-phase model. Though apparently simple, the Kapila et al. model contains a volume fraction differential transport equation containing a nonlinear, non-conservative term which poses serious computational challenges. To circumvent the difficulties encountered with the single velocity and single pressure Kapila et al. [1] multiphase flow model, a 6-equation relaxation hyperbolic model is built to solve interface problems with compressible fluids. In this approach, pressure non-equilibrium is first restored, followed by a relaxation to an asymptotic solution which is convergent to the solutions of the Kapila et al. reduced model. The apparent complexity introduced with this extended hyperbolic model actually leads to considerable simplifications regarding numerical resolution, and the various ingredients used by this method are general enough to consider future extensions to problems involving complex physics.

  20. Two-phase relative permeability models in reservoir engineering calculations

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqui, S.; Hicks, P.J.; Ertekin, T.

    1999-01-15

    A comparison of ten two-phase relative permeability models is conducted using experimental, semianalytical and numerical approaches. Model predicted relative permeabilities are compared with data from 12 steady-state experiments on Berea and Brown sandstones using combinations of three white mineral oils and 2% CaCl1 brine. The model results are compared against the experimental data using three different criteria. The models are found to predict the relative permeability to oil, relative permeability to water and fractional flow of water with varying degrees of success. Relative permeability data from four of the experimental runs are used to predict the displacement performance under Buckley-Leverett conditions and the results are compared against those predicted by the models. Finally, waterflooding performances predicted by the models are analyzed at three different viscosity ratios using a two-dimensional, two-phase numerical reservoir simulator. (author)

  1. Computer simulation of two-phase flow in nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Wulff, W.

    1992-09-01

    Two-phase flow models dominate the economic resource requirements for development and use of computer codes for analyzing thermohydraulic transients in nuclear power plants. Six principles are presented on mathematical modeling and selection of numerical methods, along with suggestions on programming and machine selection, all aimed at reducing the cost of analysis. Computer simulation is contrasted with traditional computer calculation. The advantages of run-time interactive access operation in a simulation environment are demonstrated. It is explained that the drift-flux model is better suited for two-phase flow analysis in nuclear reactors than the two-fluid model, because of the latter`s closure problem. The advantage of analytical over numerical integration is demonstrated. Modeling and programming techniques are presented which minimize the number of needed arithmetical and logical operations and thereby increase the simulation speed, while decreasing the cost.

  2. Computer simulation of two-phase flow in nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Wulff, W.

    1992-01-01

    Two-phase flow models dominate the economic resource requirements for development and use of computer codes for analyzing thermohydraulic transients in nuclear power plants. Six principles are presented on mathematical modeling and selection of numerical methods, along with suggestions on programming and machine selection, all aimed at reducing the cost of analysis. Computer simulation is contrasted with traditional computer calculation. The advantages of run-time interactive access operation in a simulation environment are demonstrated. It is explained that the drift-flux model is better suited for two-phase flow analysis in nuclear reactors than the two-fluid model, because of the latter's closure problem. The advantage of analytical over numerical integration is demonstrated. Modeling and programming techniques are presented which minimize the number of needed arithmetical and logical operations and thereby increase the simulation speed, while decreasing the cost.

  3. Two-phase Flow Distribution in Heat Exchanger Manifolds

    OpenAIRE

    Vist, Sivert

    2004-01-01

    The current study has investigated two-phase refrigerant flow distribution in heat exchange manifolds. Experimental data have been acquired in a heat exchanger test rig specially made for measurement of mass flow rate and gas and liquid distribution in the manifolds of compact heat exchangers. Twelve different manifold designs were used in the experiments, and CO2 and HFC-134a were used as refrigerants.

  4. Computational methods for two-phase flow and particle transport

    CERN Document Server

    Lee, Wen Ho

    2013-01-01

    This book describes mathematical formulations and computational methods for solving two-phase flow problems with a computer code that calculates thermal hydraulic problems related to light water and fast breeder reactors. The physical model also handles the particle and gas flow problems that arise from coal gasification and fluidized beds. The second part of this book deals with the computational methods for particle transport.

  5. Recent advances in two-phase flow numerics

    Energy Technology Data Exchange (ETDEWEB)

    Mahaffy, J.H.; Macian, R. [Pennsylvania State Univ., University Park, PA (United States)

    1997-07-01

    The authors review three topics in the broad field of numerical methods that may be of interest to individuals modeling two-phase flow in nuclear power plants. The first topic is iterative solution of linear equations created during the solution of finite volume equations. The second is numerical tracking of macroscopic liquid interfaces. The final area surveyed is the use of higher spatial difference techniques.

  6. Relative Prevalence of Grapevine Leafroll-Associated Virus Species in Wine Grape-Growing Regions of California.

    Directory of Open Access Journals (Sweden)

    Abhineet M Sharma

    Full Text Available Some diseases manifest as one characteristic set of symptoms to the host, but can be caused by multiple pathogens. Control treatments based on plant symptoms can make it difficult to effectively manage such diseases, as the biology of the underlying pathogens can vary. Grapevine leafroll disease affects grapes worldwide, and is associated with several viral species in the family Closteroviridae. Whereas some of the viruses associated with this disease are transmitted by insect vectors, others are only graft-transmissible. In three regions of California, we surveyed vineyards containing diseased vines and screened symptomatic plants for all known viral species associated with grapevine leafroll disease. Relative incidence of each virus species differed among the three regions regions, particularly in relation to species with known vectors compared with those only known to be graft-transmitted. In one region, the pathogen population was dominated by species not known to have an insect vector. In contrast, populations in the other surveyed regions were dominated by virus species that are vector-transmissible. Our survey did not detect viruses associated with grapevine leafroll disease at some sites with characteristic disease symptoms. This could be explained either by undescribed genetic diversity among these viruses that prevented detection with available molecular tools at the time the survey was performed, or a misidentification of visual symptoms that may have had other underlying causes. Based on the differences in relative prevalence of each virus species among regions and among vineyards within regions, we expect that region and site-specific management strategies are needed for effective disease control.

  7. Estimating disease prevalence in two-phase studies.

    Science.gov (United States)

    Alonzo, Todd A; Pepe, Margaret Sullivan; Lumley, Thomas

    2003-04-01

    Disease prevalence is ideally estimated using a 'gold standard' to ascertain true disease status on all subjects in a population of interest. In practice, however, the gold standard may be too costly or invasive to be applied to all subjects, in which case a two-phase design is often employed. Phase 1 data consisting of inexpensive and non-invasive screening tests on all study subjects are used to determine the subjects that receive the gold standard in the second phase. Naive estimates of prevalence in two-phase studies can be biased (verification bias). Imputation and re-weighting estimators are often used to avoid this bias. We contrast the forms and attributes of the various prevalence estimators. Distribution theory and simulation studies are used to investigate their bias and efficiency. We conclude that the semiparametric efficient approach is the preferred method for prevalence estimation in two-phase studies. It is more robust and comparable in its efficiency to imputation and other re-weighting estimators. It is also easy to implement. We use this approach to examine the prevalence of depression in adolescents with data from the Great Smoky Mountain Study.

  8. Suitability analysis for rice growing sites using a multicriteria evaluation and GIS approach in great Mwea region, Kenya.

    Science.gov (United States)

    Kihoro, Joseph; Bosco, Njoroge J; Murage, Hunja

    2013-12-01

    Land suitability analysis is a prerequisite to achieving optimum utilization of the available land resources. Lack of knowledge on best combination of factors that suit production of rice has contributed to the low production. The aim of this study was to develop a suitability map for rice crop based on physical and climatic factors of production using a Multi-Criteria Evaluation (MCE) & GIS approach. The study was carried out in Kirinyaga, Embu and Mberee counties in Kenya. Biophysical variables of soil, climate and topography were considered for suitability analysis. All data were stored in ArcGIS 9.3 environment and the factor maps were generated. For MCE, Pairwise Comparison Matrix was applied and the suitable areas for rice crop were generated and graduated. The current land cover map of the area was developed from a scanned survey map of the rice growing areas. According to the present land cover map, the rice cultivated area was 13,369 ha. Finally, we overlaid the land cover map with the suitability map to identify variances between the present and potential land use. The crop-land evaluation results of the present study showed that, 75% of total area currently being used was under highly suitable areas and 25% was under moderately suitable areas. The results showed that the potential area for rice growing is 86,364 ha and out of this only 12% is under rice cultivation. This research provided information at local level that could be used by farmers to select cropping patterns and suitability.

  9. The contribution of soil biogenic NO and HONO emissions from a managed hyperarid ecosystem to the regional NOx emissions during growing season

    Science.gov (United States)

    Mamtimin, Buhalqem; Meixner, Franz X.; Behrendt, Thomas; Badawy, Moawad; Wagner, Thomas

    2016-08-01

    A study was carried out to understand the contributions of soil biogenic NO emissions from managed (fertilized and irrigated) hyperarid ecosystems in NW China to the regional NOx emissions during the growing season. Soil biogenic net potential NO fluxes were quantified by laboratory incubation of soil samples from the three dominating ecosystems (desert, cotton, and grape fields). Regional biogenic NO emissions were calculated bottom-up hourly for the entire growing season (April-September 2010) by considering corresponding land use, hourly data of soil temperature, gravimetric soil moisture, and fertilizer enhancement factors. The regional HONO emissions were estimated using the ratio of the optimum condition ((FN,opt(HONO) to FN,opt (NO)). Regional anthropogenic NOx emissions were calculated bottom-up from annual statistical data provided by regional and local government bureaus which have been downscaled to monthly value. Regional top-down emission estimates of NOx were derived on the monthly basis from satellite observations (OMI) of tropospheric vertical NO2 column densities and prescribed values of the tropospheric NOx lifetime. In order to compare the top-down and bottom-up emission estimates, all emission estimates were expressed in terms of mass of atomic nitrogen. Consequently, monthly top-down NOx emissions (total) were compared with monthly bottom-up NOx emissions (biogenic + anthropogenic) for the time of the satellite overpass (around 13:00 LT) with the consideration of the diurnal cycle of bottom-up estimates. Annual variation in total Tohsun Oasis NOx emissions is characterized by a strong peak in winter (December-February) and a secondary peak in summer (June-August). During summer, soil biogenic emissions were from equal to double that of related anthropogenic emissions, and grape soils were the main contributor to soil biogenic emissions, followed by cotton soils, while emissions from the desert were negligible. The top-down and bottom

  10. Establishment and early development of 'Kanza', 'Peruque', and other pecan cultivars in northern U.S. growing regions

    Science.gov (United States)

    Most pecan (Carya illinoensis) nut production in the northern range of the species (Missouri, Kansas, Northern Arkansas) is from managed wild trees. Orchards of trees grafted to improved cultivars are slowly being established in the region as economic opportunities improve. Pecan cultivars that are ...

  11. The Quest for Regional Hub of Education: Growing Heterarchies, Organizational Hybridization, and New Governance in Singapore and Malaysia

    Science.gov (United States)

    Mok, Ka Ho

    2011-01-01

    With strong intention to enhance the global competitiveness of their higher education systems, the governments of Singapore and Malaysia have made attempts to develop their societies into regional hubs of education; hence transnational education has become increasingly popular in these societies. In order to attract more students from overseas to…

  12. Development of soil and terrain digital database for major food-growing regions of India for resource planning

    NARCIS (Netherlands)

    Chandran, P.; Tiwary, P.; Bhattacharyya, T.; Mandal, C.; Prasad, J.; Ray, S.K.; Sarkar, D.; Pal, D.K.; Dijkshoorn, J.A.; Batjes, N.H.; Bindraban, P.S.; Thakre, S.

    2014-01-01

    Soil information system in SOTER (soil and terrain digital database) framework is developed for the Indo-Gangetic Plains (IGP) and black soil regions (BSR) of India with the help of information from 842 georeferenced soil profiles including morphological, physical and chemical properties of soils in

  13. Characterization of leaves and flowers volatile constituents of Lantana camara growing in central region of Saudi Ar

    Directory of Open Access Journals (Sweden)

    Merajuddin Khan

    2016-11-01

    Full Text Available The chemical components of essential oils derived from leaves and flowers of Lantana camara growing in Saudi Arabia are analyzed for the first time using gas chromatography techniques (GC–MS, GC–FID, Co-GC, LRI determination, and database and literature searches on two different stationary phase columns (polar and nonpolar. This analysis led to the identification of total 163 compounds from leaves and flowers oils. 134 compounds were identified in the oil obtained from leaves of L. camara, whereas 127 compounds were identified in the oil obtained from flowers; these compounds account for 96.3% and 95.3% of the oil composition, respectively. The major components in the oil from leaves were cis-3-hexen-1-ol (11.3%, 1-octen-3-ol (8.7%, spathulenol (8.6%, caryophyllene oxide (7.5% and 1-hexanol (5.8%. In contrast, the major compounds in the flowers oil were caryophyllene oxide (10.6%, β-caryophyllene (9.7%, spathulenol (8.6%, γ-cadinene (5.6% and trans-β-farnesene (5.0%. To the best of our knowledge, cis-3-hexen-1-ol and 1-octen-3-ol that were identified as major components in this study have not been reported earlier from Lantana oils.

  14. Comparison on Phenolic Compounds and Antioxidant Properties of Cabernet Sauvignon and Merlot Wines from Four Wine Grape-Growing Regions in China

    Directory of Open Access Journals (Sweden)

    Bao Jiang

    2012-07-01

    Full Text Available The antioxidant activities in the Cabernet Sauvignon and Merlot wines from four wine grape-growing regions in China were measured by different analytical assays: 2,2-diphenyl-1-picrylhydrazyl (DPPH·, cupric reducing antioxidant capacity (CUPRAC, superoxide radical-scavenging activity (SRSA and the contents of total phenols, total flavonoids, total flavanols and total anthocyanins were determined. The results showed that the contents of phenolic compounds and the levels of antioxidant activity in the wine samples greatly varied with cultivar and environmental factors of vine growth. The contents of phenolic compounds and antioxidant activities in Cabernet Sauvignon and Merlot wines from the Yuquanying region of Ningxia were significantly higher than other three regions, followed by the wines from Shacheng region of Hebei, and these parameters were the lowest in Cabernet Sauvignon and Merlot wines from the Changli regions of Hebei and Xiangning region of Shanxi. Taken together, a close relationship between phenolic subclasses and antioxidant activity was observed for the wine samples. Moreover, there were significant discrepancies in the individual phenolic composition and content of four regional Cabernet Sauvignon and Merlot wines, among which the individual phenolic compounds (catechin, epicatechin, cinnamic acid, quercetin-3-O-glucuronide, quercetin-3-O-glucoside, laricitrin-3-O-glucoside and isorhamnetin-3-O-glucoside revealed a significant correlation (p < 0.05 with the antioxidant capacity in present study, especially for catechin and epicatechin.

  15. Temporal stability of growth and yield among Hevea genotypes introduced to a non-traditional rubber growing region of peninsular India

    Directory of Open Access Journals (Sweden)

    K.K. Vinod

    2010-09-01

    Full Text Available Extensive cultivation of Hevea brasiliensis in India now focus onnon-traditional regions for rubber cultivation. As a prelude for selection of genotypes for commercial cultivation, many introduced genotypes are being tested in genotype adaptation experiments in these regions. Present study,reports for the first time, growth and yield adaptation of 28 genotypes in a non-traditional rubber growing region of peninsular India viz., the coastal Karnataka region. Agroclimate of this region was found favoring growth andestablishment of all the genotypes evaluated. However, not all the genotypes grew and yielded well. Only four genotypes, RRII 203, KRS 25, PB 260 and PB 235 showed good growth and yield. On grouping, the genotypes fell into categories of moderate high yielders, moderate low yielders and low yielders. The most popular variety of the traditional region, RRII 105 did not perform well in this region. Biological stability in growth and yield of RRII 203 and PB 260 was identified as stable and these genotypes were the best adapted. KRS 25 and PB 235 had unstable yielding pattern. The best identifiedgenotypes can be considered for extensive culture as single clone plantations or as major constituent of clone blends as well as parents in future breeding programmes. Other moderate stable yielders may be used for clone blending in smaller proportions and may be subjected to yield improvement.

  16. Temporal stability of growth and yield among Hevea genotypes introduced to a non-traditional rubber growing region of peninsular India

    Directory of Open Access Journals (Sweden)

    K.K. Vinod

    2013-12-01

    Full Text Available Extensive cultivation of Hevea brasiliensis in India now focus on non-traditional regions for rubber cultivation. As a prelude for selection of genotypes for commercial cultivation, many introduced genotypes are being tested in genotype adaptation experiments in these regions. Present study, reports for the first time, growth and yield adaptation of 28 genotypes in a non-traditional rubber growing region of peninsular India viz., the coastal Karnataka region. Agroclimate of this region was found favoring growth and establishment of all the genotypes evaluated. However, not all the genotypes grew and yielded well. Only four genotypes, RRII 203, KRS 25, PB 260 and PB 235 showed good growth and yield. On grouping, the genotypes fell into categories of moderate high yielders, moderate low yielders and low yielders. The most popular variety of the traditional region, RRII 105 did not perform well in this region. Biological stability in growth and yield of RRII 203 and PB 260 was identified as stable and these genotypes were the best adapted. KRS 25 and PB 235 had unstable yielding pattern. The best identified genotypes can be considered for extensive culture as single clone plantations or as major constituent of clone blends as well as parents in future breeding programmes. Other moderate stable yielders may be used for clone blending in smaller proportions and may be subjected to yield improvement.

  17. Targeted Delivery by Smart Capsules for Controlling Two-phase Flow in Porous Media

    Science.gov (United States)

    Fan, J.; Weitz, D.

    2015-12-01

    Understanding and controlling two-phase flow in porous media are of particular importance to the relevant industry applications, such as enhanced oil recovery, CO2 sequestration, and groundwater remediation. We develop a variety of smart microcapsules that can deliver and release specific substances to the target location in the porous medium, and therefore change the fluid property or medium geometry at certain locations. In this talk, I will present two types of smart capsules for (a) delivering surfactant to the vicinity of oil-water interface and (b) delivering microgels to the high permeability region and therefore blocking the pore space there, respectively. We also show that flooding these two capsules into porous media effectively reduces the trapped oil and improves the homogeneity of the medium, respectively. Besides of its industrial applications, this technique also opens a new window to study the mechanism of two-phase flow in porous media.

  18. Numerical Fractional-Calculus Model for Two-Phase Flow in Fractured Media

    Directory of Open Access Journals (Sweden)

    Wenwen Zhong

    2013-01-01

    Full Text Available Numerical simulation of two-phase flow in fractured porous media is an important topic in the subsurface flow, environmental problems, and petroleum reservoir engineering. The conventional model does not work well in many cases since it lacks the memory property of fracture media. In this paper, we develop a new numerical formulation with fractional time derivative for two-phase flow in fractured porous media. In the proposed formulation, the different fractional time derivatives are applied to fracture and matrix regions since they have different memory properties. We further develop a two-level time discrete method, which uses a large time step for the pressure and a small time step size for the saturation. The pressure equation is solved implicitly in each large time step, while the saturation is updated by an explicit fractional time scheme in each time substep. Finally, the numerical tests are carried out to demonstrate the effectiveness of the proposed numerical model.

  19. Experimental Two-Phase Liquid-Metal Magnetohydrodynamic Generator Program

    Science.gov (United States)

    1979-04-01

    efficiencies in excess of 0.8 are attainable. Initial measurements of local flow parameters in a NaK -nitrogen two-phase liquid - metal MHD generator...hot liquid metals . Thus, the concept of using surface-active aaents in MHD generators can be evaluated more rapidly and inexpensively with NaK , the...describe this aggregation of bchbles as a foam. When the Ba- NaK solution was transferred, helium was blown under the surface of the liquid metal with the

  20. Recurrent pyogenic cholangitis : efficacy of two-phase helical CT

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Ki Ho; Cho, June Sik; Shin, Kyung Sook; Lee, Se Hyo; Yu, Ho Jun; Park, Jin Yong; Kim, Young Min [College of Medicine, Chungnam National University, Taejon (Korea, Republic of)

    2000-01-01

    To evaluate the usefulness of two-phase helical CT in patients with recurrent pyogenic cholangitis (RPC) for the detection of acute inflammation and assessment of the degree of portal vein (PV) stenosis as a cause of hepatic parenchymal atrophy. We retrospectively reviewed two-phase CT findings in 30 patients with RPC diagnosed by CT, ERCP (endoscopic retrograde cholangiopancreatography), and surgery. Two-phase helical CT scans were obtained 30 sec (arterial phase, AP) and 70 sec (portal phase, PP) after the start of IV administration of contrast material. Without prior information, we analyzed periductal parenchymal and ductal wall enhancement during the AP and PP, and the degree of PV stenosis during the PP. Acute inflammation was diagnosed on the basis of symptoms and laboratory findings. To evaluate the relationship between parenchymal a trophy and PV stenosis, the degree of PV stenosis in affected parenchyma was classified as one of three types (mild, less than 25%; moderate, 25-75%; severe, greater than 75%), as compared with the diameter of normal PV in unaffected parenchyma. Ten of the 30 patients underwent CT during the acute inflammatory stage and 20 during the remission stage. Of the ten patients with acute inflammation, eight (80%) showed transient periductal parenchymal enhancement during the AP (p less than 0.05), which correlated closely with acute inflammation. Only three (15%) of the 20 patients with remission, however, showed transient parenchymal enhancement during this phase, at which time ductal wall enhancement was seen in three (30%) of the ten patients with acute inflammation and in seven (35%) of the 20 who showed remission (p greater than 0.05). There was no significant difference in parenchymal and ductal wall enhancement during the PP between patients with acute inflammation and those who showed remission (p greater than 0.05). Hepatic parenchymal atrophy of the lesion was seen in 24 patients. Among these, PV stenosis was mild in five

  1. Two algorithms for two-phase Stefan type problems

    Institute of Scientific and Technical Information of China (English)

    LIAN Xiao-peng; CHENG Xiao-liang; HAN Wei-min

    2009-01-01

    In this paper, the relaxation algorithm and two Uzawa type algorithms for solving discretized variational inequalities arising from the two-phase Stefan type problem are proposed. An analysis of their convergence is presented and the upper bounds of the convergence rates are derived. Some numerical experiments are shown to demonstrate that for the second Uzawa algorithm which is an improved version of the first Uzawa algorithm, the convergence rate is uniformly bounded away from 1 if τh-2 is kept bounded, where τ is the time step size and h the space mesh size.

  2. Stochastic analysis of particle-fluid two-phase flows

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper is devoted to exploring approaches to understanding the stochastic characteristics of particle-fluid two-phase flow. By quantifying the forces dominating the particle motion and modelling the less important and/or unclear forces as random forces, a stochastic differential equation is proposed to describe the complex behavior of a particle motion. An exploratory simulation has shown satisfactory agreement with phase doppler particle analyzer (PDPA) measurements, which indicates that stochastic analysis is a potential approach for revealing the details of particle-fluid flow phenomena.

  3. Experimental and numerical investigation on two-phase flow instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Ruspini, Leonardo Carlos

    2013-03-01

    Two-phase flow instabilities are experimentally and numerically studied within this thesis. In particular, the phenomena called Ledinegg instability, density wave oscillations and pressure drop oscillations are investigated. The most important investigations regarding the occurrence of two-phase flow instabilities are reviewed. An extensive description of the main contributions in the experimental and analytical research is presented. In addition, a critical discussion and recommendations for future investigations are presented. A numerical framework using a hp-adaptive method is developed in order to solve the conservation equations modelling general thermo-hydraulic systems. A natural convection problem is analysed numerically in order to test the numerical solver. Moreover, the description of an adaptive strategy to solve thermo-hydraulic problems is presented. In the second part of this dissertation, a homogeneous model is used to study Ledinegg, density wave and pressure drop oscillations phenomena numerically. The dynamic characteristics of the Ledinegg (flow excursion) phenomenon are analysed through the simulation of several transient examples. In addition, density wave instabilities in boiling and condensing systems are investigated. The effects of several parameters, such as the fluid inertia and compressibility volumes, on the stability limits of Ledinegg and density wave instabilities are studied, showing a strong influence of these parameters. Moreover, the phenomenon called pressure drop oscillations is numerically investigated. A discussion of the physical representation of several models is presented with reference to the obtained numerical results. Finally, the influence of different parameters on these phenomena is analysed. In the last part, an experimental investigation of these phenomena is presented. The designing methodology used for the construction of the experimental facility is described. Several simulations and a non

  4. Two-phase nozzle flow and the subcharacteristic condition

    DEFF Research Database (Denmark)

    Linga, Gaute; Aursand, Peder; Flåtten, Tore

    2015-01-01

    We consider nozzle flow models for two-phase flow with phase transfer. Such models are based on energy considerations applied to the frozen and equilibrium limits of the underlying relaxation models. In this paper, we provide an explicit link between the mass flow rate predicted by these models a...... leakage of CO2 is presented, indicating that the frozen and equilibrium models provide significantly different predictions. This difference is comparable in magnitude to the modeling error introduced by applying simple ideal-gas/incompressible-liquid equations-of-state for CO2....

  5. Crop evapotranspiration-based irrigation management during the growing season in the arid region of northwestern China.

    Science.gov (United States)

    Chang, Xuexiang; Zhao, Wenzhi; Zeng, Fanjiang

    2015-11-01

    In arid northwestern China, water shortages have triggered recent regulations affecting irrigation water use in desert-oasis agricultural systems. In order to determine the actual water demand of various crops and to develop standards for the rational use of water resources, we analyzed meteorological data from the Fukang desert ecosystem observation and experiment station (FKD), the Cele desert-grassland ecosystem observation and research station (CLD), and the Linze Inland River Basin Comprehensive Research Station (LZD), which all belong to the Chinese Ecosystem Research Network. We researched crop evapotranspiration (ETc) using the water balance method, the FAO-56 Penman-Monteith method, the Priestley-Taylor method, and the Hargreaves method, during the growing seasons of 2005 through 2009. Results indicate substantial differences in ETc, depending on the method used. At the CLD, the ETc from the soil water balance, FAO-56 Penman-Monteith, Priestley-Taylor, and Hargreaves methods were 1150.3±380.8, 783.7±33.6, 1018.3±22.1, and 611.2±23.3 mm, respectively; at the FKD, the corresponding results were 861.0±67.0, 834.2±83.9, 1453.5±47.1, and 1061.0±38.2 mm, respectively; and at the LZD, 823.4±110.4, 726.0±0.4, 722.3±29.4, and 1208.6±79.1 mm, respectively. The FAO-56 Penman-Monteith method provided a fairly good estimation of E Tc compared with the Priestley-Taylor and Hargreaves methods.

  6. Conflict resolution in the zoning of eco-protected areas in fast-growing regions based on game theory.

    Science.gov (United States)

    Lin, Jinyao; Li, Xia

    2016-04-01

    Zoning eco-protected areas is important for ecological conservation and environmental management. Rapid and continuous urban expansion, however, may exert negative effects on the performance of practical zoning designs. Various methods have been developed for protected area zoning, but most of them failed to consider the conflicts between urban development (for the benefit of land developers) and ecological protection (local government). Some real-world zoning schemes even have to be modified occasionally after the lengthy negotiations between the government and land developers. Therefore, our study has presented a game theory-based method to deal with this problem. Future urban expansion in the study area will be predicted by a logistic regression cellular automaton, while eco-protected areas will be delimitated using multi-objective optimization algorithm. Then, two types of conflicts between them can be resolved based on game theory, a theory of decision-making. We established a two-person dynamic game for each conflict zone. The ecological compensation mechanism was taken into account by simulating the negotiation processes between the government and land developers. A final zoning scheme can be obtained when the two sides reach agreements. The proposed method is applied to the eco-protected area zoning in Guangzhou, a fast-growing city in China. The experiments indicate that the conflicts between eco-protection and urban development will inevitably arise when using only traditional zoning methods. Based on game theory, our method can effectively resolve those conflicts, and can provide a relatively reasonable zoning scheme. This method is expected to support policy-making in environmental management and urban planning.

  7. Molecular and biological characterization of Potato mop-top virus (PMTV, Pomovirus) isolates from potato-growing regions in Colombia

    DEFF Research Database (Denmark)

    Gil, José; Adams, Ian; Boonham, Neil

    2016-01-01

    samples were taken from the main potato-producing regions in Colombia and virus was recovered by planting Nicotiana benthamiana as bait plants. The complete genomes of five isolates were sequenced and three of the isolates were inoculated to four different indicator plants. Based on sequence comparisons......Potato mop-top virus (PMTV) causes necrotic flecks inside and on tubers in temperate countries. In South America, these symptoms have not been observed, although the presence of the virus has been confirmed in the Andes and in Central America. To characterize PMTV isolates from the Andes, soil...

  8. Droplets Formation and Merging in Two-Phase Flow Microfluidics

    Directory of Open Access Journals (Sweden)

    Hao Gu

    2011-04-01

    Full Text Available Two-phase flow microfluidics is emerging as a popular technology for a wide range of applications involving high throughput such as encapsulation, chemical synthesis and biochemical assays. Within this platform, the formation and merging of droplets inside an immiscible carrier fluid are two key procedures: (i the emulsification step should lead to a very well controlled drop size (distribution; and (ii the use of droplet as micro-reactors requires a reliable merging. A novel trend within this field is the use of additional active means of control besides the commonly used hydrodynamic manipulation. Electric fields are especially suitable for this, due to quantitative control over the amplitude and time dependence of the signals, and the flexibility in designing micro-electrode geometries. With this, the formation and merging of droplets can be achieved on-demand and with high precision. In this review on two-phase flow microfluidics, particular emphasis is given on these aspects. Also recent innovations in microfabrication technologies used for this purpose will be discussed.

  9. Experimental study of two-phase natural circulation circuit

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Wanderley Freitas; Su, Jian, E-mail: wlemos@lasme.coppe.ufrj.br, E-mail: sujian@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Faccini, Jose Luiz Horacio, E-mail: faccini@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), RIo de Janeiro, RJ (Brazil). Lab. de Termo-Hidraulica Experimental

    2012-07-01

    This paper reports an experimental study on the behavior of fluid flow in natural circulation under single-and two-phase flow conditions. The natural circulation circuit was designed based on concepts of similarity and scale in proportion to the actual operating conditions of a nuclear reactor. This test equipment has similar performance to the passive system for removal of residual heat presents in Advanced Pressurized Water Reactors (A PWR). The experiment was carried out by supplying water to primary and secondary circuits, as well as electrical power resistors installed inside the heater. Power controller has available to adjust the values for supply of electrical power resistors, in order to simulate conditions of decay of power from the nuclear reactor in steady state. Data acquisition system allows the measurement and control of the temperature at different points by means of thermocouples installed at several points along the circuit. The behavior of the phenomenon of natural circulation was monitored by a software with graphical interface, showing the evolution of temperature measurement points and the results stored in digital format spreadsheets. Besides, the natural circulation flow rate was measured by a flowmeter installed on the hot leg. A flow visualization technique was used the for identifying vertical flow regimes of two-phase natural circulation. Finally, the Reynolds Number was calculated for the establishment of a friction factor correlation dependent on the scale geometrical length, height and diameter of the pipe. (author)

  10. Two-phase electrochemical lithiation in amorphous silicon.

    Science.gov (United States)

    Wang, Jiang Wei; He, Yu; Fan, Feifei; Liu, Xiao Hua; Xia, Shuman; Liu, Yang; Harris, C Thomas; Li, Hong; Huang, Jian Yu; Mao, Scott X; Zhu, Ting

    2013-02-13

    Lithium-ion batteries have revolutionized portable electronics and will be a key to electrifying transport vehicles and delivering renewable electricity. Amorphous silicon (a-Si) is being intensively studied as a high-capacity anode material for next-generation lithium-ion batteries. Its lithiation has been widely thought to occur through a single-phase mechanism with gentle Li profiles, thus offering a significant potential for mitigating pulverization and capacity fade. Here, we discover a surprising two-phase process of electrochemical lithiation in a-Si by using in situ transmission electron microscopy. The lithiation occurs by the movement of a sharp phase boundary between the a-Si reactant and an amorphous Li(x)Si (a-Li(x)Si, x ~ 2.5) product. Such a striking amorphous-amorphous interface exists until the remaining a-Si is consumed. Then a second step of lithiation sets in without a visible interface, resulting in the final product of a-Li(x)Si (x ~ 3.75). We show that the two-phase lithiation can be the fundamental mechanism underpinning the anomalous morphological change of microfabricated a-Si electrodes, i.e., from a disk shape to a dome shape. Our results represent a significant step toward the understanding of the electrochemically driven reaction and degradation in amorphous materials, which is critical to the development of microstructurally stable electrodes for high-performance lithium-ion batteries.

  11. Droplets formation and merging in two-phase flow microfluidics.

    Science.gov (United States)

    Gu, Hao; Duits, Michel H G; Mugele, Frieder

    2011-01-01

    Two-phase flow microfluidics is emerging as a popular technology for a wide range of applications involving high throughput such as encapsulation, chemical synthesis and biochemical assays. Within this platform, the formation and merging of droplets inside an immiscible carrier fluid are two key procedures: (i) the emulsification step should lead to a very well controlled drop size (distribution); and (ii) the use of droplet as micro-reactors requires a reliable merging. A novel trend within this field is the use of additional active means of control besides the commonly used hydrodynamic manipulation. Electric fields are especially suitable for this, due to quantitative control over the amplitude and time dependence of the signals, and the flexibility in designing micro-electrode geometries. With this, the formation and merging of droplets can be achieved on-demand and with high precision. In this review on two-phase flow microfluidics, particular emphasis is given on these aspects. Also recent innovations in microfabrication technologies used for this purpose will be discussed.

  12. Acute cholecystitis: two-phase spiral CT finding

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Eung Young; Yoon, Myung Hwan; Yang, Dal Mo; Chun Seok; Bae, Jun Gi; Kim, Hak Soo; Kim, Hyung Sik [Chungang Ghil Hospital, Incheon (Korea, Republic of)

    1998-07-01

    To describe the two-phase spiral CT findings of acute cholecystitis. Materials and Methods : CT scans of nine patients with surgically-proven acute cholecystitis were retrospectively reviewed for wall thickening, enhancement pattern of the wall, attenuation of the liver adjacent to the gallbladder, gallstones,gallbladder distension, gas collection within the gallbladder, pericholecystic fluid and infiltration of pericholecystic fat. Results : In all cases, wall thickening of the gallbladder was seen, though this was more distinct on delayed images, Using high-low-high attenuation, one layer was seen in five cases, nd three layers in four. On arterial images, eight cases showed transient focal increased attenuation of the liver adjacent to the gall bladder;four of these showed curvilinear attenuation and four showed subsegmental attenuation. One case showed curvilinear decreased attenuation between increased attenuation of the liver and the gallbladder, and during surgery, severe adhesion between the liver and gallbladder was confirmed. Additional CT findings were infiltration of pericholecystic fat (n=9), gallstones (n=7), gallbladder distension (n=6), pericholecystic fluid(n=3), and gas collection within the gallbladder (n=2). Conclusion : In patients with acute cholecystitis,two-phase spiral CT revealed wall thickening in one or three layers ; on delayed images this was more distinct. In many cases, arterial images showed transient focal increased attenuation of the liver adjacent to the gallbladder.

  13. Experimental study of a two-phase surface jet

    Science.gov (United States)

    Perret, Matias; Esmaeilpour, Mehdi; Politano, Marcela S.; Carrica, Pablo M.

    2013-04-01

    Results of an experimental study of a two-phase jet are presented, with the jet issued near and below a free surface, parallel to it. The jet under study is isothermal and in fresh water, with air injectors that allow variation of the inlet air volume fraction between 0 and 13 %. Measurements of water velocity have been performed using LDV, and the jet exit conditions measured with PIV. Air volume fraction, bubble velocity and chord length distributions were measured with sapphire optical local phase detection probes. The mean free surface elevation and RMS fluctuations were obtained using local phase detection probes as well. Visualization was performed with laser-induced fluorescence. Measurements reveal that the mean free surface elevation and turbulent fluctuations significantly increase with the injection of air. The water normal Reynolds stresses are damped by the presence of bubbles in the bulk of the liquid, but very close to the free surface the effect is reversed and the normal Reynolds stresses increase slightly for the bubbly flow. The Reynolds shear stresses time it takes the bubbles to pierce the free surface, resulting in a considerable increase in the local air volume fraction. In addition to first explore a bubbly surface jet, the comprehensive dataset reported herein can be used to validate two-phase flow models and computational tools.

  14. Experimental study of two phase flow in inclined channel

    Energy Technology Data Exchange (ETDEWEB)

    Park, Goon Cherl; Lee, Tae Ho; Lee, Sang Won [Seoul National University, Seoul (Korea, Republic of)

    1997-07-01

    Local two-phase flow parameters were measured to investigate the internal flow structures of steam-water boiling flow in an inclined channel. The vapor phase local flow parameters, such as void fraction, bubble frequency, vapor velocity, interfacial area concentration and chord length, were measured, using two conductivity probe method, and local liquid phase velocity was measured by pitot tube. In order to investigate the effects of channel inclination on two phase flow structure, the experiments were conducted for three angles of inclination; 0 degree(vertical), 30 degree and 60 degree. The experimental flow conditions were confined to the liquid superficial velocities less than 1.4 m/sec and nearly atmospheric pressure, and the flow regime was limited to the subcooled boiling. Using the measured distributions of the local phasic parameters, correlations for the drift-flux parameters such as distribution parameter and drift velocity were proposed. Those correlations were compared with the available correlation applicable to the inclined channel by the calculation of average void fraction using the present data. 44 refs., 4 tabs., 88 figs. (author)

  15. Chemical analysis and antioxidant activity of the essential oils of three Piperaceae species growing in the central region of Cuba.

    Science.gov (United States)

    Rodríguez, Elisa Jorge; Saucedo-Hernández, Yanelis; Vander Heyden, Yvan; Simó-Alfonso, Ernesto F; Ramis-Ramos, Guillermo; Lerma-García, María Jesús; Monteagudo, Urbano; Bravo, Luis; Medinilla, Mildred; de Armas, Yuriam; Herrero-Martínez, José Manuel

    2013-09-01

    The present study describes the phytochemical profile and antioxidant activity of the essential oils of three Piperaceae species collected in the central region of Cuba. The essential oils of Piper aduncum, P. auritum and P. umbellatum leaves, obtained by hydrodistillation, were analyzed by gas chromatography-mass spectrometry. The main components of P. aduncum oil were piperitone (34%), camphor (17.1%), camphene (10.9%), 1,8-cineol (8.7%) and viridiflorol (7.4%), whereas that of P. auritum and P. umbellatum was safrole (71.8 and 26.4%, respectively). The antioxidant properties of the essential oils were also evaluated using several assays for radical scavenging ability (DPPH test and reducing power) and inhibition of lipid oxidation (ferric thiocyanate method and evaluation against Cucurbita seed oil by peroxide, thiobarbituric acid and p-anisidine methods). P. auritum showed the strongest antioxidant activity among the Piper species investigated, but lower than those of butylated hydroxyanisol and propyl gallate.

  16. [Genetic variability of the bacterium Ralstonia solanacearum (Burkholderiales: Burholderiaceae) in the banana-growing region of Uraba (Colombia)].

    Science.gov (United States)

    Cardozo, Carolina; Rodríguez, Paola; Cotes, José Miguel; Marín, Mauricio

    2010-03-01

    The banana moko disease, caused by the bacterium Ralstonia solanacearum, is one of the most important phytopathological problems of the banana agribusiness in tropical countries. In Uraba and Magdalena (Colombia), the main exporting regions of banana in Colombia, this disease causes a destruction estimated in 16.5 ha/year. The bacterium presents an extremely high level of genetic variation that affects control measures. This is the first study of its variation in Colombia and was done with AFLP molecular markers on a population of 100 isolates from banana plants, soils and "weeds". The high level of genetic diversity, with Nei and Shannon indexes of h=0.32 and I=0.48, respectively, and the AMOVA, showed that this population is subestructured (Fst=0.66): the host is the main factor of differentiation. Even so, previous tests show that all varieties have pathogenicity on Musa.

  17. Effect of land cover and green space on land surface temperature of a fast growing economic region in Malaysia

    Science.gov (United States)

    Sheikhi, A.; Kanniah, K. D.; Ho, C. H.

    2015-10-01

    Green space must be increased in the development of new cities as green space can moderate temperature in the cities. In this study we estimated the land surface temperature (LST) and established relationships between LST and land cover and various vegetation and urban surface indices in the Iskandar Malaysia (IM) region. IM is one of the emerging economic gateways of Malaysia, and is envisaged to transform into a metropolis by 2025. This change may cause increased temperature in IM and therefore we conducted a study by using Landsat 5 image covering the study region (2,217 km2) to estimate LST, classify different land covers and calculate spectral indices. Results show that urban surface had highest LST (24.49 °C) and the lowest temperature was recorded in, forest, rubber and water bodies ( 20.69 to 21.02°C). Oil palm plantations showed intermediate mean LST values with 21.65 °C. We further investigated the relationship between vegetation and build up densities with temperature. We extracted 1000 collocated pure pixels of Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Normalized Difference Built-up Index (NDBI), Urban Index (UI) and LST in the study area. Results show a strong and significant negative correlation with (R2= -0.74 and -0.79) respectively between NDVI, NDWI and LST . Meanwhile a strong positive correlation (R2=0.8 and 0.86) exists between NDBI, UI and LST. These results show the importance of increasing green cover in urban environment to combat any adverse effects of climate change.

  18. The Effect of pH Difference Between Two Phases on the Partition of Lysozyme in Aqueous Two-Phase System

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the investigation of effect of KSCN on the partitioning of lysozyme in PEG2000/ammonium sulfate aqueous two-phase system, it was found that the KSCN could alter the pH difference between the two phases, and thus affect the partition of lysozyme. The relationship between partition coefficients of lysozyme and pH differences between two phases was discussed.

  19. Maturity stages affect the postharvest quality and shelf-life of fruits of strawberry genotypes growing in subtropical regions

    Directory of Open Access Journals (Sweden)

    M. Moshiur Rahman

    2016-01-01

    Full Text Available The postharvest changes of five promising strawberry genotypes viz. Sweet Charlie, Festival, Camarosa, FA 008 and BARI Strawberry-1 at ambient temperature were studied under sub tropical region during the winter season (December–April of 2010–2011 and 2011–2012 in Bangladesh. Irrespective of maturity stages percent fruit decay and weight of fruits were noted minimum in Camarosa and maximum in FA 008 up to day 4 of storage. The shelf life of fruits was maximum in Camarosa and minimum in FA 008 and BARI Strawberry-1 regardless of maturity stage throughout the storage period. The TSS, total sugar and ascorbic acid content of fruits were increased with the increase in maturity stage during the storage period. In 1/3rd and 2/3rd maturity stages, the TSS and total sugar content were found the highest in Festival but at full maturity stage those were recorded higher in Camarosa. The titratable acidity was noticed the highest in 1/3rd matured fruits and gradually decreased with the increase in maturity stage as well as storage duration in all the genotypes. Ascorbic acid content of strawberry gradually decreases during the storage period. Fully matured fresh fruits of Festival contained maximum ascorbic acid content while BARI Strawberry-1 contained minimum ascorbic acid that was reduced after 3 days of storage.

  20. Characterization of root-nodulating bacteria associated to Prosopis farcta growing in the arid regions of Tunisia.

    Science.gov (United States)

    Fterich, A; Mahdhi, M; Caviedes, M A; Pajuelo, E; Rivas, R; Rodriguez-Llorente, I D; Mars, M

    2011-06-01

    Diversity of 50 bacterial isolates recovered from root nodules of Prosopis farcta grown in different arid soils in Tunisia, was investigated. Characterization of isolates was assessed using a polyphasic approach including phenotypic characteristics, 16S rRNA gene PCR--RFLP and sequencing, nodA gene sequencing and MLSA. It was found that most of isolates are tolerant to high temperature (40°C) and salinity (3%). Genetic characterization emphasizes that isolates were assigned to the genus Ensifer (80%), Mesorhizobium (4%) and non-nodulating endophytic bacteria (16%). Forty isolates belonging to the genus Ensifer were affiliated to Ensifer meliloti, Ensifer xinjiangense/Ensifer fredii and Ensifer numidicus species. Two isolates belonged to the genus Mesorhizobium. Eight isolates failing to renodulate their host plant were endophytic bacteria and belonged to Bacillus, Paenibacillus and Acinetobacter genera. Symbiotic properties of nodulating isolates showed a diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Isolate PG29 identified as Ensifer meliloti was the most effective one. Ability of Prosopis farcta to establish symbiosis with rhizobial species confers an important advantage for this species to be used in reforestation programs. This study offered the first systematic information about the diversity of microsymbionts nodulating Prosopis farcta in the arid regions of Tunisia.

  1. Contrast enhanced two-phase spiral CT of urinary bladder

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeung Uk; Cha, Seong Sook; Ryu, Ji Hwa; Oh, Jeong Geun; Chang, Seung Kuk; Choi, Seok Jin; Eun, Choong Kie [Inje Univ. College of Medicine, Pusan (Korea, Republic of); Seo, Chang Hye [Daedong General Hospital, Pusan (Korea, Republic of)

    1997-10-01

    To determine optimal scan time for the early phase of two-phase spiral CT and to evaluate its usefulness in the detection and assessment of extension of urinary bladder lesions. In four normal adults, we performed dynamic scanning and obtained time-density curves for internal and external iliac arteries and veins, and the wall of the urinary bladder. Sixty patients with 68 lesions of the urinary bladder or prostate underwent precontrast and two-phase spiral CT scanning. After injection of 100ml of noninonic contrast material, images for the early and delayed phases were obtained at 60 seconds and 5 minutes, respectively. We measured CT H. U. of the wall, the lesion, and lumen of urinary bladder as seen on axial scanning, in each image in which the lesion was best shown. For the detection of bladder lesions and assessment of their extension, precontrast, early-, and delayed phsed images were compared. Dynamic study of normal adults showed maximum enhancement of bladder wall between 60 and 100 seconds. The difference of CT H. U. between bladder wall and the lesion was greatest in the early phase. The best detection rate(98.5%) was seen during this phase, and for the detection of bladder lesion, this same phase was superior or equal (66/68, 97.1%) to the delayed phase. The precontrast image was also superior or equal (31/68, 45.6%) to that of the delayed phase. For the assessment of extension of bladder lesion, the early phase was superior (36/68, 52.9%) to the delayed phase, and precontrast image was superiour (1/68, 1.5%) to that of the delayed phase. For determining the stage of bladder cancer, the early phase was most accurate if the stages was below B{sub 2} or D, while for stage C, the delayed phase was most accurate. In two-hpase spiral CT scanning, we consider the optimal time for the early phase to be between 60 and 100 seconds after injection of contrast material. For the detection and assessment of extension of urinary bladder lesion, the early phase was

  2. Prediction of shear bands in sand based on granular flow model and two-phase equilibrium

    Institute of Scientific and Technical Information of China (English)

    张义同; 齐德瑄; 杜如虚; 任述光

    2008-01-01

    In contrast to the traditional interpretation of shear bands in sand as a bifurcation problem in continuum mechanics,shear bands in sand are considered as high-strain phase(plastic phase) of sand and the materials outside the bands are still in low-strain phase(elastic phase),namely,the two phases of sand can coexist under certain condition.As a one-dimensional example,the results show that,for materials with strain-softening behavior,the two-phase solution is a stable branch of solutions,but the method to find two-phase solutions is very different from the one for bifurcation analysis.The theory of multi-phase equilibrium and the slow plastic flow model are applied to predict the formation and patterns of shear bands in sand specimens,discontinuity of deformation gradient and stress across interfaces between shear bands and other regions is considered,the continuity of displacements and traction across interfaces is imposed,and the Maxwell relation is satisfied.The governing equations are deduced.The critical stress for the formation of a shear band,both the stresses and strains inside the band and outside the band,and the inclination angle of the band can all be predicted.The predicted results are consistent with experimental measurements.

  3. Two-phase PIV measurements of particle suspension in a forced impinging jet

    Science.gov (United States)

    Mulinti, Rahul; Kiger, Ken

    2010-11-01

    The condition of rotorcraft brownout is characterized by intense dust suspension that is uplifted during landing and takeoff operations in regions covered with loose sediment. To predict particle suspension and sedimentation within coupled particle-laden flows, detailed characterization of the micro-scale mechanics is needed within a prototypical flow that captures the essence of the rotorcraft/ground wake interactions. Two-phase PIV has been used to study the interaction of a sediment bed made of glass spheres with characteristic flow structures reminiscent from flow within a rotor wake. In order to make reliable simultaneous two-phase PIV measurements, a phase discrimination algorithm from a single two-phase image has been implemented. The validity of the separation is checked by processing images that consisted only of the very small tracer particles, or only the dispersed phase particles, and examining how much "cross-talk" was present between the phases. The mobilization and wall-normal flux of particulates by the vortex-wall interaction will be reported for several different operational conditions, and correlated to the local vortex conditions.

  4. Aedes aegypti (L.) in Latin American and Caribbean region: With growing evidence for vector adaptation to climate change?

    Science.gov (United States)

    Chadee, Dave D; Martinez, Raymond

    2016-04-01

    Within Latin America and the Caribbean region the impact of climate change has been associated with the effects of rainfall and temperature on seasonal outbreaks of dengue but few studies have been conducted on the impacts of climate on the behaviour and ecology of Aedes aegypti mosquitoes.This study was conducted to examine the adaptive behaviours currently being employed by A. aegypti mosquitoes exposed to the force of climate change in LAC countries. The literature on the association between climate and dengue incidence is small and sometimes speculative. Few laboratory and field studies have identified research gaps. Laboratory and field experiments were designed and conducted to better understand the container preferences, climate-associated-adaptive behaviour, ecology and the effects of different temperatures and light regimens on the life history of A. aegypti mosquitoes. A. aegypti adaptive behaviours and changes in container preferences demonstrate how complex dengue transmission dynamics is, in different ecosystems. The use of underground drains and septic tanks represents a major behaviour change identified and compounds an already difficult task to control A. aegypti populations. A business as usual approach will exacerbate the problem and lead to more frequent outbreaks of dengue and chikungunya in LAC countries unless both area-wide and targeted vector control approaches are adopted. The current evidence and the results from proposed transdisciplinary research on dengue within different ecosystems will help guide the development of new vector control strategies and foster a better understanding of climate change impacts on vector-borne disease transmission. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. 一种自适应的区域生长算法用于道路分割%Road Image Segmentation Based on an Adaptive Region Growing

    Institute of Scientific and Technical Information of China (English)

    肖晓明; 马智; 蔡自兴; 唐琏

    2011-01-01

    Aiming at road detection of vehicle driving on the highway, this thesis focused on the color and gray of image, an improved method based on cluster analysis and region growing for road detection was presented. In order to enhance the algorithm' s accuracy,inage pre-process which could eliminate lane' s interferences was taken. After the image pre-process, according to the distribution of the characteristics of the image, it was divided into three parts which were processed in different algorithms. For the central region which had much road information and mixed non-road information, an adaptive region growing rules algorithm which based on the traditional region growing algorithm and cluster analysis was used for segmenting the road region effectively. The algorithm could adaptive mauy situations on the highway, and it is an algorithm with high accuracy, real-times and robustness.%针对汽车在高速公路上行驶的道路区域分割问题,以路面颜色特征为研究对象,提出了一种将聚类分析应用于区域生长准则的算法,实现道路分割.为了提高算法的精确度,对图像进行预处理,消除车道线对道路分割的干扰.根据图像预处理之后道路信息分布的特点,将图像分为3块子区域分别用不同的算法进行检测.对于道路信息丰富,非道路信息也较多的中部区域,在传统区域生长的基础上结合聚类分析,提出了一种自适应生长准则的区域生长算法.该算法既能适应高速公路各种行驶环境,且实时性好、可靠性高、鲁棒性强.

  6. Modelling of two-phase flow based on separation of the flow according to velocity

    Energy Technology Data Exchange (ETDEWEB)

    Narumo, T. [VTT Energy, Espoo (Finland). Nuclear Energy

    1997-12-31

    The thesis concentrates on the development work of a physical one-dimensional two-fluid model that is based on Separation of the Flow According to Velocity (SFAV). The conventional way to model one-dimensional two-phase flow is to derive conservation equations for mass, momentum and energy over the regions occupied by the phases. In the SFAV approach, the two-phase mixture is divided into two subflows, with as distinct average velocities as possible, and momentum conservation equations are derived over their domains. Mass and energy conservation are treated equally with the conventional model because they are distributed very accurately according to the phases, but momentum fluctuations follow better the flow velocity. Submodels for non-uniform transverse profile of velocity and density, slip between the phases within each subflow and turbulence between the subflows have been derived. The model system is hyperbolic in any sensible flow conditions over the whole range of void fraction. Thus, it can be solved with accurate numerical methods utilizing the characteristics. The characteristics agree well with the used experimental data on two-phase flow wave phenomena Furthermore, the characteristics of the SFAV model are as well in accordance with their physical counterparts as of the best virtual-mass models that are typically optimized for special flow regimes like bubbly flow. The SFAV model has proved to be applicable in describing two-phase flow physically correctly because both the dynamics and steady-state behaviour of the model has been considered and found to agree well with experimental data This makes the SFAV model especially suitable for the calculation of fast transients, taking place in versatile form e.g. in nuclear reactors. 45 refs. The thesis includes also five previous publications by author.

  7. Interfacial Tension Effect on Cell Partition in Aqueous Two-Phase Systems.

    Science.gov (United States)

    Atefi, Ehsan; Joshi, Ramila; Mann, Jay Adin; Tavana, Hossein

    2015-09-30

    Aqueous two-phase systems (ATPS) provide a mild environment for the partition and separation of cells. We report a combined experimental and theoretical study on the effect of interfacial tension of polymeric ATPS on the partitioning of cells between two phases and their interface. Two-phase systems are generated using polyethylene glycol and dextran of specific properties as phase-forming polymers and culture media as the solvent component. Ultralow interfacial tensions of the solutions are precisely measured using an axisymmetric drop shape analysis method. Partition experiments show that two-phase systems with an interfacial tension of 30 μJ/m(2) result in distribution of majority of cells to the bottom dextran phase. An increase in the interfacial tension results in a distribution of cells toward the interface. An independent cancer cell spheroid formation assay confirms these observations: a drop of the dextran phase containing cancer cells is dispensed into the immersion polyethylene glycol phase to form a cell-containing drop. Only at very small interfacial tensions do cells remain within the drop to aggregate into a spheroid. We perform a thermodynamic modeling of cell partition to determine variations of free energy associated with displacement of cells in ATPS with respect to the ultralow interfacial tensions. This modeling corroborates with the experimental results and demonstrates that at the smallest interfacial tension of 30 μJ/m(2), the free energy is a minimum with cells in the bottom phase. Increasing the interfacial tension shifts the minimum energy and partition of cells toward the interfacial region of the two aqueous phases. Examining differences in the partition behavior and minimum free energy modeling of A431.H9 cancer cells and mouse embryonic stem cells shows that the surface properties of cells further modulate partition in ATPS. This combined approach provides a fundamental understanding of interfacial tension role on cell partition in

  8. A Variational Model for Two-Phase Immiscible Electroosmotic Flow at Solid Surfaces

    KAUST Repository

    Shao, Sihong

    2012-01-01

    We develop a continuum hydrodynamic model for two-phase immiscible flows that involve electroosmotic effect in an electrolyte and moving contact line at solid surfaces. The model is derived through a variational approach based on the Onsager principle of minimum energy dissipation. This approach was first presented in the derivation of a continuum hydrodynamic model for moving contact line in neutral two-phase immiscible flows (Qian, Wang, and Sheng, J. Fluid Mech. 564, 333-360 (2006)). Physically, the electroosmotic effect can be formulated by the Onsager principle as well in the linear response regime. Therefore, the same variational approach is applied here to the derivation of the continuum hydrodynamic model for charged two-phase immiscible flows where one fluid component is an electrolyte exhibiting electroosmotic effect on a charged surface. A phase field is employed to model the diffuse interface between two immiscible fluid components, one being the electrolyte and the other a nonconductive fluid, both allowed to slip at solid surfaces. Our model consists of the incompressible Navier-Stokes equation for momentum transport, the Nernst-Planck equation for ion transport, the Cahn-Hilliard phase-field equation for interface motion, and the Poisson equation for electric potential, along with all the necessary boundary conditions. In particular, all the dynamic boundary conditions at solid surfaces, including the generalized Navier boundary condition for slip, are derived together with the equations of motion in the bulk region. Numerical examples in two-dimensional space, which involve overlapped electric double layer fields, have been presented to demonstrate the validity and applicability of the model, and a few salient features of the two-phase immiscible electroosmotic flows at solid surface. The wall slip in the vicinity of moving contact line and the Smoluchowski slip in the electric double layer are both investigated. © 2012 Global-Science Press.

  9. Stability of stratified two-phase flows in horizontal channels

    CERN Document Server

    Barmak, Ilya; Ullmann, Amos; Brauner, Neima; Vitoshkin, Helen

    2016-01-01

    Linear stability of stratified two-phase flows in horizontal channels to arbitrary wavenumber disturbances is studied. The problem is reduced to Orr-Sommerfeld equations for the stream function disturbances, defined in each sublayer and coupled via boundary conditions that account also for possible interface deformation and capillary forces. Applying the Chebyshev collocation method, the equations and interface boundary conditions are reduced to the generalized eigenvalue problems solved by standard means of numerical linear algebra for the entire spectrum of eigenvalues and the associated eigenvectors. Some additional conclusions concerning the instability nature are derived from the most unstable perturbation patterns. The results are summarized in the form of stability maps showing the operational conditions at which a stratified-smooth flow pattern is stable. It is found that for gas-liquid and liquid-liquid systems the stratified flow with smooth interface is stable only in confined zone of relatively lo...

  10. Two-phase microfluidics: thermophysical fundamentals and engineering concepts

    Science.gov (United States)

    Kuznetsov, V. V.

    2016-10-01

    Thermophysical fundamentals and engineering concepts of the two-phase microfluidic devises based on controlled liquid decay are discussed in this paper. The results of an experimental study of the explosive evaporation at a thin film heater of the MEMS devise in application to thermal inkjet printing are presented. The peculiarities of homogeneous nucleation and bubble growth in the liquid subjected to pulse heating are discussed. Using experimental data a simple equation suitable for predicting the growth rate of a vapor bubble in a non-uniformly superheated liquid was obtained and used to complete a mathematical model of the self-consistent nucleation and vapor bubbles growth in the induced pressure field. The results of numerical calculations according to the proposed model showed good agreement with the experimental data on a time of nucleation and duration of the initial stage of an explosive evaporation of water.

  11. Mathematical model of two-phase flow in accelerator channel

    Directory of Open Access Journals (Sweden)

    О.Ф. Нікулін

    2010-01-01

    Full Text Available  The problem of  two-phase flow composed of energy-carrier phase (Newtonian liquid and solid fine-dispersed phase (particles in counter jet mill accelerator channel is considered. The mathematical model bases goes on the supposition that the phases interact with each other like independent substances by means of aerodynamics’ forces in conditions of adiabatic flow. The mathematical model in the form of system of differential equations of order 11 is represented. Derivations of equations by base physical principles for cross-section-averaged quantity are produced. The mathematical model can be used for estimation of any kinematic and thermodynamic flow characteristics for purposely parameters optimization problem solving and transfer functions determination, that take place in  counter jet mill accelerator channel design.

  12. Two phase coexistence for the hydrogen-helium mixture

    CERN Document Server

    Fantoni, Riccardo

    2015-01-01

    We use our newly constructed quantum Gibbs ensemble Monte Carlo algorithm to perform computer experiments for the two phase coexistence of a hydrogen-helium mixture. Our results are in quantitative agreement with the experimental results of C. M. Sneed, W. B. Streett, R. E. Sonntag, and G. J. Van Wylen. The difference between our results and the experimental ones is in all cases less than 15% relative to the experiment, reducing to less than 5% in the low helium concentration phase. At the gravitational inversion between the vapor and the liquid phase, at low temperatures and high pressures, the quantum effects become relevant. At extremely low temperature and pressure the first component to show superfluidity is the helium in the vapor phase.

  13. Phase appearance or disappearance in two-phase flows

    CERN Document Server

    Cordier, Floraine; Kumbaro, Anela

    2011-01-01

    This paper is devoted to the treatment of specific numerical problems which appear when phase appearance or disappearance occurs in models of two-phase flows. Such models have crucial importance in many industrial areas such as nuclear power plant safety studies. In this paper, two outstanding problems are identified: first, the loss of hyperbolicity of the system when a phase appears or disappears and second, the lack of positivity of standard shock capturing schemes such as the Roe scheme. After an asymptotic study of the model, this paper proposes accurate and robust numerical methods adapted to the simulation of phase appearance or disappearance. Polynomial solvers are developed to avoid the use of eigenvectors which are needed in usual shock capturing schemes, and a method based on an adaptive numerical diffusion is designed to treat the positivity problems. An alternate method, based on the use of the hyperbolic tangent function instead of a polynomial, is also considered. Numerical results are presente...

  14. Two-phase flow simulation of aeration on stepped spillway

    Institute of Scientific and Technical Information of China (English)

    CHENG Xiangju; LUO Lin; ZHAO Wenqian; LI Ran

    2004-01-01

    Stepped spillways have existed as escape works for a very long time. It is found that water can trap a lot of air when passing through steps and then increasing oxygen content in water body, so stepped spillways can be used as a measure of re-aeration and to improve water quality of water body. However, there is no reliable theoretical method on quantitative calculation of re-aeration ability for the stepped spillways. By introducing an air-water two-phase flow model, this paper used k-ε turbulence model to calculate the characteristic variables of free-surface aeration on stepped spillway. The calculated results fit with the experimental results well. It supports that the numerical modeling method is reasonable and offers firm foundation on calculating re-aeration ability of stepped spillways. The simulation approach can provide a possible optimization tool for designing stepped spillways of more efficient aeration capability.

  15. A TWO-PHASE APPROACH TO FUZZY SYSTEM IDENTIFICATION

    Institute of Scientific and Technical Information of China (English)

    Ta-Wei HUNG; Shu-Cherng FANG; Henry L.W.NUTTLE

    2003-01-01

    A two-phase approach to fuzzy system identification is proposed. The first phase produces a baseline design to identify a prototype fuzzy system for a target system from a coIlection of input-output data pairs. It uses two easily implemented clustering techniques: the subtractive clustering method and the fuzzy c-means (FCM) clustering algorithm. The second phase (fine tuning)is executed to adjust the parameters identified in the baseline design. This phase uses the steepest descent and recursive least-squares estimation methods. The proposed approach is validated by applying it to both a function approximation type of problem and a classification type of problem. An analysis of the learning behavior of the proposed approach for the two test problems is conducted for further confirmation.

  16. Emerging Two-Phase Cooling Technologies for Power Electronic Inverters

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, J.S.

    2005-08-17

    In order to meet the Department of Energy's (DOE's) FreedomCAR and Vehicle Technologies (FVCT) goals for volume, weight, efficiency, reliability, and cost, the cooling of the power electronic devices, traction motors, and generators is critical. Currently the power electronic devices, traction motors, and generators in a hybrid electric vehicle (HEV) are primarily cooled by water-ethylene glycol (WEG) mixture. The cooling fluid operates as a single-phase coolant as the liquid phase of the WEG does not change to its vapor phase during the cooling process. In these single-phase systems, two cooling loops of WEG produce a low temperature (around 70 C) cooling loop for the power electronics and motor/generator, and higher temperature loop (around 105 C) for the internal combustion engine. There is another coolant option currently available in automobiles. It is possible to use the transmission oil as a coolant. The oil temperature exists at approximately 85 C which can be utilized to cool the power electronic and electrical devices. Because heat flux is proportional to the temperature difference between the device's hot surface and the coolant, a device that can tolerate higher temperatures enables the device to be smaller while dissipating the same amount of heat. Presently, new silicon carbide (SiC) devices and high temperature direct current (dc)-link capacitors, such as Teflon capacitors, are available but at significantly higher costs. Higher junction temperature (175 C) silicon (Si) dies are gradually emerging in the market, which will eventually help to lower hardware costs for cooling. The development of high-temperature devices is not the only way to reduce device size. Two-phase cooling that utilizes the vaporization of the liquid to dissipate heat is expected to be a very effective cooling method. Among two-phase cooling methods, different technologies such as spray, jet impingement, pool boiling and submersion, etc. are being developed. The

  17. Two-Phase Algorithm for Optimal Camera Placement

    Directory of Open Access Journals (Sweden)

    Jun-Woo Ahn

    2016-01-01

    Full Text Available As markers for visual sensor networks have become larger, interest in the optimal camera placement problem has continued to increase. The most featured solution for the optimal camera placement problem is based on binary integer programming (BIP. Due to the NP-hard characteristic of the optimal camera placement problem, however, it is difficult to find a solution for a complex, real-world problem using BIP. Many approximation algorithms have been developed to solve this problem. In this paper, a two-phase algorithm is proposed as an approximation algorithm based on BIP that can solve the optimal camera placement problem for a placement space larger than in current studies. This study solves the problem in three-dimensional space for a real-world structure.

  18. Two-phase flow instabilities in a vertical annular channel

    Energy Technology Data Exchange (ETDEWEB)

    Babelli, I.; Nair, S.; Ishii, M. [Purdue Univ., West Lafayette, IN (United States)

    1995-09-01

    An experimental test facility was built to study two-phase flow instabilities in vertical annular channel with emphasis on downward flow under low pressure and low flow conditions. The specific geometry of the test section is similar to the fuel-target sub-channel of the Savannah River Site (SRS) Mark 22 fuel assembly. Critical Heat Flux (CHF) was observed following flow excursion and flow reversal in the test section. Density wave instability was not recorded in this series of experimental runs. The results of this experimental study show that flow excursion is the dominant instability mode under low flow, low pressure, and down flow conditions. The onset of instability data are plotted on the subcooling-Zuber (phase change) numbers stability plane.

  19. Equations of two-phase flow in spray chamber

    Institute of Scientific and Technical Information of China (English)

    李新禹; 张志红; 金星; 徐杰

    2009-01-01

    The downstream water-air heat and moisture transfer system in a moving coordinate was studied. The relationship between the diameter of the misted droplets and the spray pressure was determined. Based on the theory of the relative velocity,the two-phase flow mode of the spray chamber and the efficiency equation for heat and moisture exchange were established. Corrections were carried out for the efficiency equation with spray pressure of 157 kPa. The results show that the pressure plays an important part in determining the efficiency of heat and moisture exchange. When the spray pressure is less than 157 kPa,better coincidence is noticed between the theoretical analysis and the test results with the error less than 6%. Greater error will be resulted in the case when the spray pressure is beyond 157 kPa. After the correction treatment,the coincidence between the theoretical and the experimental results is greatly improved.

  20. Transient thermohydraulic modeling of two-phase fluid systems

    Science.gov (United States)

    Blet, N.; Delalandre, N.; Ayel, V.; Bertin, Y.; Romestant, C.; Platel, V.

    2012-11-01

    This paper presents a transient thermohydraulic modeling, initially developed for a capillary pumped loop in gravitational applications, but also possibly suitable for all kinds of two-phase fluid systems. Using finite volumes method, it is based on Navier-Stokes equations for transcribing fluid mechanical aspects. The main feature of this 1D-model is based on a network representation by analogy with electrical. This paper also proposes a parametric study of a counterflow condenser following the sensitivity to inlet mass flow rate and cold source temperature. The comparison between modeling results and experimental data highlights a good numerical evaluation of temperatures. Furthermore, the model is able to represent a pretty good dynamic evolution of hydraulic variables.

  1. Flooding in counter-current two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Ragland, W.A.; Ganic, E.N.

    1982-01-01

    Flooding is a phenomenon which is best described as the transition from counter-current to co-current flow. Early notice was taken of this phenomenon in the chemical engineering industry. Flooding also plays an important role in the field of two-phase heat transfer since it is a limit for many systems involving counter-current flow. Practical applications of flooding limited processes include wickless thermosyphons and the emergency core cooling system (ECCS) of pressurized water nuclear reactors. The phenomenon of flooding also is involved in the behavior of nuclear reactor core materials during severe accident conditions where flooding is one of the mechanisms governing the motion of the molten fuel pin cladding.

  2. Note on Two-Phase Phenomena in Financial Markets

    Institute of Scientific and Technical Information of China (English)

    JIANG Shi-Mei; CAI Shi-Min; ZHOU Wao; ZHOU Pei-Ling

    2008-01-01

    The two-phase behaviour in financial markets actually means the bifurcation phenomenon, which represents the change of the conditional probability from an unimodal to a bimodal distribution. We investigate the bifurcation phenomenon in Hang-Seng index. It is observed that the bifurcation phenomenon in financial index is not universal, but specific under certain conditions. For Hang-Seng index and randomly generated time series, the phenomenon just emerges when the power-law exponent of absolute increment distribution is between i and 2 with appropriate period. Simulations on a randomly generated time series suggest the bifurcation phenomenon itself is subject to the statistics of absolute increment, thus it may not be able to reflect essential financial behaviours. However, even under the same distribution of absolute increment, the range where bifurcation phenomenon occurs is far different from real market to artificial data, which may reflect certain market information.

  3. Thirty-two phase sequences design with good autocorrelation properties

    Indian Academy of Sciences (India)

    S P Singh; K Subba Rao

    2010-02-01

    Polyphase Barker Sequences are finite length, uniform complex sequences; the magnitude of their aperiodic autocorrelation sidelobes are bounded by 1. Such sequences have been used in numerous real-world applications such as channel estimation, radar and spread spectrum communication. In this paper, thirty-two phase Barker sequences up to length 24 with an alphabet size of only 32 are presented. The sequences from length 25 to 289 have autocorrelation properties better than well-known Frank codes. Because of the complex structure the sequences are very difficult to detect and analyse by an enemy’s electronic support measures (ESMs). The synthesized sequences are promising for practical application to radar and spread spectrum communication systems. These sequences are found using the Modified Simulated Annealing Algorithm (MSAA). The convergence rate of the algorithm is good.

  4. Chemical diversity of essential oils from flowers, leaves, and stems of Rhanterium epapposum Oliv. growing in northern border region of Saudi Arabia

    Institute of Scientific and Technical Information of China (English)

    Marwa Awad; Abdelrhman Abdelwahab

    2016-01-01

    Objective: To evaluate the medicinal uses of Rhanterium epapposum Oliv. (R. epapposum) growing in northern border region of Saudi Arabia, through the chemical diversity of essential oils extracted from its flowers, leaves and stems. Methods: Aerial parts of R. epapposum were collected in April 2014. Air dried flowers, leaves, and stems were separately subjected to hydrodistillation in a Clevenger-type apparatus for 4 h to extract the essential oils. Gas chromatography-mass spectrometry analysis of the essential oils was carried out using an Agilent 6890 gas chromatograph equipped with an Agilent 5973 mass spectrometric detector. Results: A total of 51 compounds representing 76.35%–94.86%of flowers, leaves and stems oils composition were identified. The chemical profiles of the studied fractions revealed the dominance of monoterpenes, regardless of qualitative and quantitative dif-ferences observed. Limonene, linalool, 4-terpineol and a-cadinol represented the major constituents of flowers oil. Leaves oil was dominated by limonene, sabinene, a-pinene and β-myrcene whereas linalool, ionole, a-cadinol, β-eudesmol, 4-terpineol, and a-terpineol were the major constituents of stems oil. Conclusions: Essential oils from flowers, leaves and stems of R. epapposum growing in northern border region of Saudi Arabia are considered as a rich source of monoterpenes which have biological activities.

  5. Distribution of ionic currents in the soma and growing region of an identified peptidergic neuron in defined culture.

    Science.gov (United States)

    Meyers, D E

    1993-02-01

    lamellipodia-somata pairs ranged from 0.5 to 1.7 (mean = 1.2, SD +/- 0.6), suggesting that both channel types are distributed relatively evenly over the cell surface. 5. The differences in current density in the different regions did not correlate with the length of the neurite remaining after separation of the soma and lamellipodium. 6. It is concluded that CHH neurons in the early phase of regeneration in primary culture show a distinct pattern of ion channel distribution. These ion channels are present in new membrane < 18 h after formation.(ABSTRACT TRUNCATED AT 400 WORDS)

  6. Two-phase methanization of food wastes in pilot scale.

    Science.gov (United States)

    Lee, J P; Lee, J S; Park, S C

    1999-01-01

    A 5 ton/d pilot scale two-phase anaerobic digester was constructed and tested to treat Korean food wastes in Anyang city near Seoul. The easily degradable presorted food waste was efficiently treated in the two-phase anaerobic digestion process. The waste contained in plastic bags was shredded and then screened for the removal of inert materials such as fabrics and plastics, and subsequently put into the two-stage reactors. Heavy and light inerts such as bones, shells, spoons, and plastic pieces were again removed by gravity differences. The residual organic component was effectively hydrolyzed and acidified in the first reactor with 5 d space time at pH of about 6.5. The second, methanization reactor converted the acids into methane with pH between 7.4 and 7.8. The space time for the second reactor was 15 d. The effluent from the second reactor was recycled to the first reactor to provide alkalinities. The process showed stable steady-state operation with the maximum organic loading rate of 7.9 kg volatile solid (VS)/m3/d and the volatile solid reduction efficiency of about 70%. The total of 3.6 tons presorted MSW containing 2.9 tons of food organic was treated to produce about 230 m3 of biogas with 70% (v/v) of methane and 80 kg of humus. This process is extended to full-scale treating 15 tons of food waste a day in Euiwang city and the produced biogas is utilized for the heating/cooling of adjacent buildings.

  7. Two phase continuous digestion of solid manure on-farm

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, W.; Lehto, M. [MTT Agrifood Research Finland, Vihti (Finland). Animal Production Research; Evers, L.; Granstedt, A. [Biodynamic Research Inst., Jaerna (Sweden)

    2007-07-01

    Present commercially available biogas plants are mainly suitable for slurry and co-substrates. Cattle, horse and poultry farms using a solid manure chain experience a crucial competitive disadvantage, because conversion to slurry technology requires additional investments. Based on the technological progress of anaerobic digestion of municipal solid waste, so called 'dry fermentation' prototype plants were developed for anaerobic digestion of organic material containing 15-50% total solids (Hoffman, 2001). These plants show added advantages compared to slurry digestion plants: Less reactor volume, less process energy, less transport capacity, less odour emissions. On-farm research (Gronauer and Aschmann, 2004; Kusch and Oechsner, 2004) and prototype research (Linke, 2004) on dry fermentation in batch reactors show that loading and discharging of batch reactors remains difficult and/or time-consuming compared to slurry reactors. Additionally a constant level of gas generation requires offset operation of several batch reactors. Baserga et al. (1994) developed a pilot plant of 9.6 m{sup 3} capacity for continuous digestion of solid beef cattle manure on-farm. However, on-farm dry fermentation plants are not common and rarely commercially available. We assume that lack of tested technical solutions and scarceness of on-farm research results are the main reason for low acceptance of dry fermentation technology on-farm. We report about an innovative two phase farm-scale biogas plant. The plant continuously digests dairy cattle manure and organic residues of the farm and the surrounding food processing units. The two phase reactor technology was chosen for two reasons: first it offers the separation of a liquid fraction and a solid fraction for composting after hydrolysis and secondly the methanation of the liquid fraction using fixed film technology results in a very short hydraulic retention time, reduction in reactor volume, and higher methane content of the

  8. Correct numerical simulation of a two-phase coolant

    Science.gov (United States)

    Kroshilin, A. E.; Kroshilin, V. E.

    2016-02-01

    Different models used in calculating flows of a two-phase coolant are analyzed. A system of differential equations describing the flow is presented; the hyperbolicity and stability of stationary solutions of the system is studied. The correctness of the Cauchy problem is considered. The models' ability to describe the following flows is analyzed: stable bubble and gas-droplet flows; stable flow with a level such that the bubble and gas-droplet flows are observed under and above it, respectively; and propagation of a perturbation of the phase concentration for the bubble and gas-droplet media. The solution of the problem about the breakdown of an arbitrary discontinuity has been constructed. Characteristic times of the development of an instability at different parameters of the flow are presented. Conditions at which the instability does not make it possible to perform the calculation are determined. The Riemann invariants for the nonlinear problem under consideration have been constructed. Numerical calculations have been performed for different conditions. The influence of viscosity on the structure of the discontinuity front is studied. Advantages of divergent equations are demonstrated. It is proven that a model used in almost all known investigating thermohydraulic programs, both in Russia and abroad, has significant disadvantages; in particular, it can lead to unstable solutions, which makes it necessary to introduce smoothing mechanisms and a very small step for describing regimes with a level. This does not allow one to use efficient numerical schemes for calculating the flow of two-phase currents. A possible model free from the abovementioned disadvantages is proposed.

  9. Supporting universal prevention programs: a two-phased coaching model.

    Science.gov (United States)

    Becker, Kimberly D; Darney, Dana; Domitrovich, Celene; Keperling, Jennifer Pitchford; Ialongo, Nicholas S

    2013-06-01

    Schools are adopting evidence-based programs designed to enhance students' emotional and behavioral competencies at increasing rates (Hemmeter et al. in Early Child Res Q 26:96-109, 2011). At the same time, teachers express the need for increased support surrounding implementation of these evidence-based programs (Carter and Van Norman in Early Child Educ 38:279-288, 2010). Ongoing professional development in the form of coaching may enhance teacher skills and implementation (Noell et al. in School Psychol Rev 34:87-106, 2005; Stormont et al. 2012). There exists a need for a coaching model that can be applied to a variety of teacher skill levels and one that guides coach decision-making about how best to support teachers. This article provides a detailed account of a two-phased coaching model with empirical support developed and tested with coaches and teachers in urban schools (Becker et al. 2013). In the initial universal coaching phase, all teachers receive the same coaching elements regardless of their skill level. Then, in the tailored coaching phase, coaching varies according to the strengths and needs of each teacher. Specifically, more intensive coaching strategies are used only with teachers who need additional coaching supports, whereas other teachers receive just enough support to consolidate and maintain their strong implementation. Examples of how coaches used the two-phased coaching model when working with teachers who were implementing two universal prevention programs (i.e., the PATHS curriculum and PAX Good Behavior Game [PAX GBG]) provide illustrations of the application of this model. The potential reach of this coaching model extends to other school-based programs as well as other settings in which coaches partner with interventionists to implement evidence-based programs.

  10. Four-phase or two-phase signal plan? A study on four-leg intersection by cellular automaton simulations

    Science.gov (United States)

    Jin, Cheng-Jie; Wang, Wei; Jiang, Rui

    2016-08-01

    The proper setting of traffic signals at signalized intersections is one of the most important tasks in traffic control and management. This paper has evaluated the four-phase traffic signal plans at a four-leg intersection via cellular automaton simulations. Each leg consists of three lanes, an exclusive left-turn lane, a through lane, and a through/right-turn lane. For a comparison, we also evaluate the two-phase signal plan. The diagram of the intersection states in the space of inflow rate versus turning ratio has been presented, which exhibits four regions: In region I/II/III, congestion will propagate upstream and laterally and result in queue spillover with both signal plans/two-phase signal plan/four-phase signal plan, respectively. Therefore, neither signal plan works in region I, and only the four-phase signal plan/two-phase signal plan works in region II/III. In region IV, both signal plans work, but two-phase signal plan performs better in terms of average delays of vehicles. Finally, we study the diagram of the intersection states and average delays in the asymmetrical configurations.

  11. 基于区域生长的前视红外图像分割方法%Forward-looking infrared image segmentation based on region growing

    Institute of Scientific and Technical Information of China (English)

    夏晶; 孙继银

    2011-01-01

    Infrared imaging guidance technology has been the main trend in the development of precision guidance technology today by reason of its predominant capability. Accurate infrared image segmentation is the basis for realizing target recognition. Aiming at the features of forward-looking infrared image and the purpose of image segmentation in imaging guidance technology,a novel segmentation algorithm based on region growing is proposed. Firstly the seed region is selected based on global threshold segmentation and partial gray scale statistics criterion and strategy is defined to choose the seeds in the region. Then regarding the area of target template as the reference, the growing threshold is adjusted automatically for region growing through the estimation of segmentation effect. Finally, the segmented image is obtained. Experimental results show that the target information gained by the proposed algorithm is complete and exact and the result greatly facilitates the target matching recognition based on edge feature.%红外成像制导技术以其优越的性能成为当今精确制导技术发展的主流.红外图像的精确分割是实现目标识别的基础.针对地面目标前视红外图像的特点和成像制导技术中图像分割的目的,提出了一种基于区域生长的前视红外图像分割算法,它首先在全局阈值分割的基础上选择出种子点所在区域,并在区域中定义局部灰度信息统计准则和策略选取出种子点;然后以目标模板面积作为参考,通过对分割效果的判断自动调整生长阈值进行区域生长以得到分割图像.实验结果表明,本方法分割出的目标完整准确,分割结果对基于边缘特征的目标匹配识别非常有利.

  12. Insights into regional adaptations in the growing pulmonary artery using a meso-scale structural model: effects of ascending aorta impingement.

    Science.gov (United States)

    Fata, Bahar; Zhang, Will; Amini, Rouzbeh; Sacks, Michael S

    2014-02-01

    As the next step in our investigations into the structural adaptations of the main pulmonary artery (PA) during postnatal growth, we utilized the extensive experimental measurements of the growing ovine PA from our previous study (Fata et al., 2013, "Estimated in vivo Postnatal Surface Growth Patterns of the Ovine Main Pulmonary Artery and Ascending Aorta," J. Biomech. Eng., 135(7), pp. 71010-71012). to develop a structural constitutive model for the PA wall tissue. Novel to the present approach was the treatment of the elastin network as a distributed fiber network rather than a continuum phase. We then utilized this model to delineate structure-function differences in the PA wall at the juvenile and adult stages. Overall, the predicted elastin moduli exhibited minor differences remained largely unchanged with age and region (in the range of 150 to 200 kPa). Similarly, the predicted collagen moduli ranged from ∼1,600 to 2700 kPa in the four regions studied in the juvenile state. Interestingly, we found for the medial region that the elastin and collagen fiber splay underwent opposite changes (collagen standard deviation juvenile = 17 deg to adult = 28 deg, elastin standard deviation juvenile = 35 deg to adult = 27 deg), along with a trend towards more rapid collagen fiber strain recruitment with age, along with a drop in collagen fiber moduli, which went from 2700 kPa for the juvenile stage to 746 kPa in the adult. These changes were likely due to the previously observed impingement of the relatively stiff ascending aorta on the growing PA medial region. Intuitively, the effects of the local impingement would be to lower the local wall stress, consistent with the observed parallel decrease in collagen modulus. These results suggest that during the postnatal somatic growth period local stresses can substantially modulate regional tissue microstructure and mechanical behaviors in the PA. We further underscore that our previous studies

  13. A speed estimation of sensorless control for asymmetrical parameter type two-phase induction motor drives

    Directory of Open Access Journals (Sweden)

    Nuttapong Muangchan

    2015-06-01

    Full Text Available This paper presents the concept of a speed estimation of sensorless control for asymmetrical parameter type two-phase induction motor drive, by using the adaptive observer system. The motor speed is estimated on the rotor-flux reference frame to simplicity for application. The design guideline of the gain of speed estimate system for a motor has speed change. The experimental results for all test conditions show that the responses of current, torque and speed are stable for the entire operating region.

  14. Simulation Experiments in Electromagnetic Tomography Well Logging in Two-phase flow

    Institute of Scientific and Technical Information of China (English)

    Wu Xiling; Zhao Yanwei

    2006-01-01

    Electromagnetic Computer Tomography (ECT) is a method to probe the interior of an inhomogeneous medium via surface measurement in a non-linear way. Due to the great differences in conductivity and permittivity between oil and water in the well, Electromagnetic Tomography Well Logging (ETWL), a new flow imaging measurement system, is proposed to describe the distribution and movement of oil/water two-phase flow in the well by scanning the detected region and applying a suitable data processing algorithm. The results of the numerical simulation and physical modeling show that the system could provide a clear image of the flow profile.

  15. Two-phase micro- and macro-time scales in particle-laden turbulent channel flows

    Institute of Scientific and Technical Information of China (English)

    Bing Wang; Michael Manhart

    2012-01-01

    The micro- and macro-time scales in two-phase turbulent channel flows are investigated using the direct numerical simulation and the Lagrangian particle trajectory methods for the fluid- and the particle-phases,respectively.Lagrangian and Eulerian time scales of both phases are calculated using velocity correlation functions.Due to flow anisotropy,micro-time scales are not the same with the theoretical estimations in large Reynolds number (isotropic) turbulence.Lagrangian macro-time scales of particle-phase and of fluid-phase seen by particles are both dependent on particle Stokes number.The fluid-phase Lagrangian integral time scales increase with distance from the wall,longer than those time scales seen by particles.The Eulerian integral macro-time scales increase in near-wall regions but decrease in out-layer regions.The moving Eulerian time scales are also investigated and compared with Lagrangian integral time scales,and in good agreement with previous measurements and numerical predictions.For the fluid particles the micro Eulerian time scales are longer than the Lagrangian ones in the near wall regions,while away from the walls the micro Lagrangian time scales are longer.The Lagrangian integral time scales are longer than the Eulerian ones.The results are useful for further understanding two-phase flow physics and especially for constructing accurate prediction models of inertial particle dispersion.

  16. Creep of Two-Phase Microstructures for Microelectronic Applications

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, Heidi Linch [Univ. of California, Berkeley, CA (United States)

    1998-12-01

    The mechanical properties of low-melting temperature alloys are highly influenced by their creep behavior. This study investigates the dominant mechanisms that control creep behavior of two-phase, low-melting temperature alloys as a function of microstructure. The alloy systems selected for study were In-Ag and Sn-Bi because their eutectic compositions represent distinctly different microstructure.” The In-Ag eutectic contains a discontinuous phase while the Sn-Bi eutectic consists of two continuous phases. In addition, this work generates useful engineering data on Pb-free alloys with a joint specimen geometry that simulates microstructure found in microelectronic applications. The use of joint test specimens allows for observations regarding the practical attainability of superplastic microstructure in real solder joints by varying the cooling rate. Steady-state creep properties of In-Ag eutectic, Sn-Bi eutectic, Sn-xBi solid-solution and pure Bi joints have been measured using constant load tests at temperatures ranging from O°C to 90°C. Constitutive equations are derived to describe the steady-state creep behavior for In-Ageutectic solder joints and Sn-xBi solid-solution joints. The data are well represented by an equation of the form proposed by Dom: a power-law equation applies to each independent creep mechanism. Rate-controlling creep mechanisms, as a function of applied shear stress, test temperature, and joint microstructure, are discussed. Literature data on the steady-state creep properties of Sn-Bi eutectic are reviewed and compared with the Sn-xBi solid-solution and pure Bi joint data measured in the current study. The role of constituent phases in controlling eutectic creep behavior is discussed for both alloy systems. In general, for continuous, two-phase microstructure, where each phase exhibits significantly different creep behavior, the harder or more creep resistant phase will dominate the creep behavior in a lamellar microstructure. If a

  17. Statistical descriptions of polydisperse turbulent two-phase flows

    Science.gov (United States)

    Minier, Jean-Pierre

    2016-12-01

    Disperse two-phase flows are flows containing two non-miscible phases where one phase is present as a set of discrete elements dispersed in the second one. These discrete elements, or 'particles', can be droplets, bubbles or solid particles having different sizes. This situation encompasses a wide range of phenomena, from nano-particles and colloids sensitive to the molecular fluctuations of the carrier fluid to inertia particles transported by the large-scale motions of turbulent flows and, depending on the phenomenon studied, a broad spectrum of approaches have been developed. The aim of the present article is to analyze statistical models of particles in turbulent flows by addressing this issue as the extension of the classical formulations operating at a molecular or meso-molecular level of description. It has a three-fold purpose: (1) to bring out the thread of continuity between models for discrete particles in turbulent flows (above the hydrodynamical level of description) and classical mesoscopic formulations of statistical physics (below the hydrodynamical level); (2) to reveal the specific challenges met by statistical models in turbulence; (3) to establish a methodology for modeling particle dynamics in random media with non-zero space and time correlations. The presentation is therefore centered on organizing the different approaches, establishing links and clarifying physical foundations. The analysis of disperse two-phase flow models is developed by discussing: first, approaches of classical statistical physics; then, by considering models for single-phase turbulent flows; and, finally, by addressing current formulations for discrete particles in turbulent flows. This brings out that particle-based models do not cease to exist above the hydrodynamical level and offer great interest when combined with proper stochastic formulations to account for the lack of equilibrium distributions and scale separation. In the course of this study, general results

  18. An experimental study of single-phase and two-phase flows in microchannels

    Science.gov (United States)

    Chung, Peter Mang-Yu

    . The channel shape did not affect the two-phase frictional pressure drop or the void fraction-to-volumetric quality relationship. A region of ring-slug flow that appears in the circular microchannel collapsed in the square microchannel, possibly due to the suppression of the liquid-ring film in the corners of the square channel.

  19. Effects of two-phase flow on the deflagration of porous energetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Margolis, S.B. [Sandia National Labs., Livermore, CA (United States); Williams, F.A. [Univ. of California, San Diego, La Jolla, CA (United States). Dept. of Applied Mechanics and Engineering Sciences

    1994-07-01

    Theoretical analyses are developed for the multi-phase deflagration of porous energetic solids, such as degraded nitramine propellants, that experience significant gas flow in the solid preheat region and are characterized by the presence of exothermic reactions in a bubbling melt layer at their surfaces. Relative motion between the gas and condensed phases is taken into account in both regions, and expressions for the mass burning rate and other quantities of interest, such as temperature and volume-fraction profiles, are derived by activation-energy asymptotics. The model extends recent work by allowing for gas flow in the unburned solid, and by incorporating pressure effects through the gas-phase equation of state. As a consequence, it is demonstrated how most aspects of the deflagration wave, including its structure, propagation speed and final temperature, depend on the local pressure in the two-phase regions.

  20. Biomarker responses of rice plants growing in a potentially toxic element polluted region: A case study in the Le'An Region.

    Science.gov (United States)

    Ji, Yong; Zhang, Jie; Li, Xiaoli; Peng, Yongwen; Cai, Gaotang; Gao, Guiqing; Wu, Jianqiang; Liu, Jiali

    2017-08-22

    Rice plants, planted and grown in the field, were chosen in this study to evaluate the potentially toxic element pollution by combining pollutant analysis and a molecular biomarker response evaluation together in the Le'An Region, a highly polluted area due to anthropogenic activities. Soils and crops at 18 sites classified into four areas based on hydrological, geological and pollutant survey results were collected during the whole growth cycle for chemical and biological analysis. Sediment quality values and pollution indexes were combined with statistical analyses to assess the hazard of potentially toxic elements and evaluate ecological risks. As effective stress-related signals, chlorophyll (Chl), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione content (GSH) and lipoperoxidation (as TBARS) were also determined during the rice plant growth period. The results revealed that heavy metal concentrations were significantly higher than corresponding background values and significantly related to those of the soils. The maximum concentration of potentially toxic elements was observed at the tillering stage, followed by the grain filling stage and heading stage. As biomarkers in field monitoring, a significant increase or decrease in Chl, SOD, POD, CAT, GSH and TBARS in crops means a potential relationship between the indexes and pollutants. This study also demonstrates that the integrated biomarker response (IBR) calculated by combining different biomarkers could be used effectively to evaluate the pollutant-induced stress levels in different areas. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Improved identification of rapidly growing mycobacteria by a 16S-23S internal transcribed spacer region PCR and capillary gel electrophoresis.

    Directory of Open Access Journals (Sweden)

    Timothy J Gray

    Full Text Available The identification of rapidly growing mycobacteria (RGM remains problematic because of evolving taxonomy, limitations of current phenotypic methods and absence of a universal gene target for reliable speciation. This study evaluated a novel method of identification of RGM by amplification of the mycobacterial 16S-23S rRNA internal transcribed spacer (ITS followed by resolution of amplified fragments by capillary gel electrophoresis (CGE. Nineteen American Type Culture Collection (ATCC Mycobacterium strains and 178 clinical isolates of RGM (12 species were studied. All RGM ATCC strains generated unique electropherograms with no overlap with slowly growing mycobacteria species, including M. tuberculosis. A total of 47 electropherograms for the 178 clinical isolates were observed allowing the speciation of 175/178 (98.3% isolates, including the differentiation of the closely related species, M. massiliense (M. abscessus subspecies bolletii and M. abscessus (M. abscessus sensu stricto. ITS fragment size ranged from 332 to 534 bp and 33.7% of clinical isolates generated electropherograms with two distinct peaks, while the remainder where characterized with a single peak. Unique peaks (fragment lengths were identified for 11/12 (92% RGM species with only M. moriokaense having an indistinguishable electropherogram from a rarely encountered CGE subtype of M. fortuitum. We conclude that amplification of the 16S-23S ITS gene region followed by resolution of fragments by CGE is a simple, rapid, accurate and reproducible method for species identification and characterization of the RGM.

  2. Interstellar Cloud Formation through Aggregation of Cold Blobs in a Two-Phase Gas Mixture

    Science.gov (United States)

    Kamaya, Hideyuki

    1997-05-01

    We propose a new formation scenario for interstellar clouds through the aggregation of dense cold blobs (phase II [PII]), which drift in a diffuse warm medium (phase I [PI]). We examine how important it is that there exist numerous PII blobs when the properties of such a two-phase flow are studied. First, we solve a one-dimensional shock-tube problem and find that the shock wave in the mixture is considerably damped because of the drag force between the two phases. This is because the PII blobs are left behind the shock front, since their inertia is larger than that of PI, thus suppressing large spatial variations of PI gas via the drag force. The PII blobs thus play the role of anchors. Therefore, mass aggregation by shocks may be ineffective in a two-phase medium. However, the PII blobs can still aggregate through a kind of fluid dynamical instability. We next suppose that the PI gas is accelerated upward by shocks against downward gravity, while the PII blobs are at rest because of balance between the drag force due to PI and gravity. If we put a positive perturbation in the number density of PII blobs, the upward PI flow above the perturbation is decelerated by the enhanced drag force, and the velocity difference between PI and PII is thereby reduced. Then the PII blobs above the perturbation are accelerated downward, since the gravity on PII now dominates the reduced drag force. As a result, the blobs will fall onto this perturbed region, and this region becomes denser and denser. This is the mechanism of the instability. Therefore, we expect efficient cloud formation by this instability in spiral arms, even when galactic shocks are extremely damped.

  3. Particle migration in two-phase, viscoelastic flows

    Science.gov (United States)

    Jaensson, Nick; Hulsen, Martien; Anderson, Patrick

    2014-11-01

    Particles suspended in creeping, viscoelastic flows can migrate across stream lines due to gradients in normal stresses. This phenomenon has been investigated both numerically and experimentally. However, particle migration in the presence of fluid-fluid interfaces is hardly studied. We present results of simulations in 2D and 3D of rigid spherical particles in two-phase flows, where either one or both of the fluids are viscoelastic. The fluid-fluid interface is assumed to be diffuse and is described using Cahn-Hilliard theory. The particle boundary is assumed to be sharp and is described by a boundary-fitted, moving mesh. The governing equations are solved using the finite element method. We show that differences in normal stresses between the two fluids can induce a migration of the particle towards the interface in a shear flow. Depending on the magnitude of the surface tension and the properties of the fluids, particle migration can be halted due to the induced Laplace pressure, the particle can be adsorbed at the interface, or the particle can cross the interface into the other fluid. Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands.

  4. Criteria for guaranteed breakdown in two-phase inhomogeneous bodies

    Science.gov (United States)

    Bardsley, Patrick; Primrose, Michael S.; Zhao, Michael; Boyle, Jonathan; Briggs, Nathan; Koch, Zoe; Milton, Graeme W.

    2017-08-01

    Lower bounds are obtained on the maximum field strength in one or both phases in a body containing two-phases. These bounds only incorporate boundary data that can be obtained from measurements at the surface of the body, and thus may be useful for determining if breakdown has necessarily occurred in one of the phases, or that some other nonlinearities have occurred. It is assumed the response of the phases is linear up to the point of electric, dielectric, or elastic breakdown, or up to the point of the onset of nonlinearities. These bounds are calculated for conductivity, with one or two sets of boundary conditions, for complex conductivity (as appropriate at fixed frequency when the wavelength is much larger than the body, i.e. for quasistatics), and for two-dimensional elasticity. Sometimes the bounds are optimal when the field is constant in one of the phases, and using the algorithm of Kang, Kim, and Milton (2012) a wide variety of inclusion shapes having this property, for appropriately chosen bodies and appropriate boundary conditions, are numerically constructed. Such inclusions are known as E_Ω -inclusions.

  5. Diagnosing Traffic Anomalies Using a Two-Phase Model

    Institute of Scientific and Technical Information of China (English)

    Bin Zhang; Jia-Hai Yang; Jian-Ping Wu; Ying-Wu Zhu

    2012-01-01

    Network traffic anomalies are unusual changes in a network,so diagnosing anomalies is important for network management.Feature-based anomaly detection models (ab)normal network traffic behavior by analyzing packet header features. PCA-subspace method (Principal Component Analysis) has been verified as an efficient feature-based way in network-wide anomaly detection.Despite the powerful ability of PCA-subspace method for network-wide traffic detection,it cannot be effectively used for detection on a single link.In this paper,different from most works focusing on detection on flow-level traffic,based on observations of six traffc features for packet-level traffic,we propose a new approach B6SVM to detect anomalies for packet-level traffic on a single link.The basic idea of B6-SVM is to diagnose anomalies in a multi-dimensional view of traffic features using Support Vector Machine (SVM).Through two-phase classification,B6-SVM can detect anomalies with high detection rate and low false alarm rate.The test results demonstrate the effectiveness and potential of our technique in diagnosing anomalies.Further,compared to previous feature-based anomaly detection approaches,B6-SVM provides a framework to automatically identify possible anomalous types.The framework of B6-SVM is generic and therefore,we expect the derived insights will be helpful for similar future research efforts.

  6. Thermal performance of closed two-phase thermosyphon using nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Khandekar, Sameer; Mehta, Balkrishna [Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Joshi, Yogesh M. [Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

    2008-06-15

    Nanofluids, stabilized suspensions of nanoparticles typically <100 nm in conventional fluids, are evolving as potential enhanced heat transfer fluids due to their improved thermal conductivity, increase in single phase heat transfer coefficient and significant increase in critical boiling heat flux. In the present paper, we investigate the overall thermal resistance of closed two-phase thermosyphon using pure water and various water based nanofluids (of Al{sub 2}O{sub 3}, CuO and laponite clay) as working fluids. We observe that all these nanofluids show inferior thermal performance than pure water. Furthermore, we observe that the wettability of all nanofluids on copper substrate, having the same average roughness as that of the thermosyphon container pipe, is better than that of pure water. A scaling analysis is presented which shows that the increase in wettability and entrapment of nanoparticles in the grooves of the surface roughness cause decrease in evaporator side Peclet number that finally leads to poor thermal performance. (author)

  7. Aqueous Nanofluid as a Two-Phase Coolant for PWR

    Directory of Open Access Journals (Sweden)

    Pavel N. Alekseev

    2012-01-01

    Full Text Available Density fluctuations in liquid water consist of two topological kinds of instant molecular clusters. The dense ones have helical hydrogen bonds and the nondense ones are tetrahedral clusters with ice-like hydrogen bonds of water molecules. Helical ordering of protons in the dense water clusters can participate in coherent vibrations. The ramified interface of such incompatible structural elements induces clustering impurities in any aqueous solution. These additives can enhance a heat transfer of water as a two-phase coolant for PWR due to natural forming of nanoparticles with a thermal conductivity higher than water. The aqueous nanofluid as a new condensed matter has a great potential for cooling applications. It is a mixture of liquid water and dispersed phase of extremely fine quasi-solid particles usually less than 50 nm in size with the high thermal conductivity. An alternative approach is the formation of gaseous (oxygen or hydrogen nanoparticles in density fluctuations of water. It is possible to obtain stable nanobubbles that can considerably exceed the molecular solubility of oxygen (hydrogen in water. Such a nanofluid can convert the liquid water in the nonstoichiometric state and change its reduction-oxidation (RedOx potential similarly to adding oxidants (or antioxidants for applying 2D water chemistry to aqueous coolant.

  8. Stability of stratified two-phase flows in horizontal channels

    Science.gov (United States)

    Barmak, I.; Gelfgat, A.; Vitoshkin, H.; Ullmann, A.; Brauner, N.

    2016-04-01

    Linear stability of stratified two-phase flows in horizontal channels to arbitrary wavenumber disturbances is studied. The problem is reduced to Orr-Sommerfeld equations for the stream function disturbances, defined in each sublayer and coupled via boundary conditions that account also for possible interface deformation and capillary forces. Applying the Chebyshev collocation method, the equations and interface boundary conditions are reduced to the generalized eigenvalue problems solved by standard means of numerical linear algebra for the entire spectrum of eigenvalues and the associated eigenvectors. Some additional conclusions concerning the instability nature are derived from the most unstable perturbation patterns. The results are summarized in the form of stability maps showing the operational conditions at which a stratified-smooth flow pattern is stable. It is found that for gas-liquid and liquid-liquid systems, the stratified flow with a smooth interface is stable only in confined zone of relatively low flow rates, which is in agreement with experiments, but is not predicted by long-wave analysis. Depending on the flow conditions, the critical perturbations can originate mainly at the interface (so-called "interfacial modes of instability") or in the bulk of one of the phases (i.e., "shear modes"). The present analysis revealed that there is no definite correlation between the type of instability and the perturbation wavelength.

  9. Microporous silica gels from alkylsilicate-water two phase hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Chu, L.; Tejedor-Tejedor, M.I.; Anderson, M.A. [Univ. of Wisconsin, Madison, WI (United States). Water Chemistry Program

    1994-12-31

    Microporous silica gels have been synthesized through a nano-particulate sol-gel route. These gels have uniformly distributed and extremely small pores(< 15 {angstrom} in diameter). Hydrolysis and condensation reactions leading to these gels were carried out in an alkyl silicate-water (ammonia) two phase system. These reactions took place at the alkyl silicate droplet-water interfacial boundary. No alcohol was added. A clear, stable and uniformly distributed colloidal silica suspension having an average particle size less than 6 nm was prepared by this method. Fast hydrolysis, slow condensation and low solubility all contribute to a high supersaturation level and result in the formation of small particles. This process is consistent with classic nucleation theory. When the particles are produced under acidic rather than under basic reaction conditions, smaller particles are formed due to the slower condensation rate and lower solubility of these silica particles in acidic conditions. At the same pH, alkylsilicates having smaller alkyl groups react faster with water leading to smaller primary particles. Homogeneous nucleation conditions are achieved when the water/alkylsilicate ratio is high.

  10. Pressure transient analysis of two-phase flow problems

    Energy Technology Data Exchange (ETDEWEB)

    Chu, W.C.; Reynolds, A.C.; Raghavan, R.

    1986-04-01

    This paper considers the analysis of pressure drawdown and buildup data for two-phase flow problems. Of primary concern is the analysis of data influenced by saturation gradients that exist within the reservoir. Wellbore storage effects are assumed to be negligible. The pressure data considered are obtained from a two-dimensional (2D) numerical coning model for an oil/water system. The authors consider constant-rate production followed by a buildup period and assume that the top, bottom, and outer boundaries of the reservoir are sealed. First, they consider the case where the producing interval is equal to the total formation thickness. Second, they discuss the effect of partial penetration. In both cases, they show that average pressure can be estimated by the Matthews-Brons-Hazebroek method and consider the computation of the skin factor. They also show that a reservoir limit test can estimate reservoir PV only if the total mobility adjacent to the wellbore does not vary with time.

  11. Two-Phase Flow Hydrodynamics in Superhydrophobic Channels

    Science.gov (United States)

    Stevens, Kimberly; Crockett, Julie; Maynes, Daniel; Iverson, Brian

    2015-11-01

    Superhydrophobic surfaces promote drop-wise condensation and droplet removal leading to the potential for increased thermal transport. Accordingly, great interest exists in using superhydrophobic surfaces in flow condensing environments, such as power generation and desalination. Adiabatic air-water mixtures were used to gain insight into the effect of hydrophobicity on two-phase flows and the hydrodynamics present in flow condensation. Pressure drop and onset of various flow regimes in hydrophilic, hydrophobic, and superhydrophobic mini (0.5 x 10 mm) channels were explored. Data for air/water mixtures with superficial Reynolds numbers from 20-200 and 250-1800, respectively, were obtained. Agreement between experimentally obtained pressure drops and correlations in literature for the conventional smooth control surfaces was better than 20 percent. Transitions between flow regimes for the hydrophobic and hydrophilic channels were similar to commonly recognized flow types. However, the superhydrophobic channel demonstrated significantly different flow regime behavior from conventional surfaces including a different shape of the air slugs, as discussed in the presentation.

  12. An automated two-phase system for hydrogel microbead production.

    Science.gov (United States)

    Coutinho, Daniela F; Ahari, Amir F; Kachouie, Nezamoddin N; Gomes, Manuela E; Neves, Nuno M; Reis, Rui L; Khademhosseini, Ali

    2012-09-01

    Polymeric beads have been used for protection and delivery of bioactive materials, such as drugs and cells, for different biomedical applications. Here, we present a generic two-phase system for the production of polymeric microbeads of gellan gum or alginate, based on a combination of in situ polymerization and phase separation. Polymer droplets, dispensed using a syringe pump, formed polymeric microbeads while passing through a hydrophobic phase. These were then crosslinked, and thus stabilized, in a hydrophilic phase as they crossed through the hydrophobic-hydrophilic interface. The system can be adapted to different applications by replacing the bioactive material and the hydrophobic and/or the hydrophilic phases. The size of the microbeads was dependent on the system parameters, such as needle size and solution flow rate. The size and morphology of the microbeads produced by the proposed system were uniform, when parameters were kept constant. This system was successfully used for generating polymeric microbeads with encapsulated fluorescent beads, cell suspensions and cell aggregates proving its ability for generating bioactive carriers that can potentially be used for drug delivery and cell therapy.

  13. Two-Phase Flow Field Simulation of Horizontal Steam Generators

    Directory of Open Access Journals (Sweden)

    Ataollah Rabiee

    2017-02-01

    Full Text Available The analysis of steam generators as an interface between primary and secondary circuits in light water nuclear power plants is crucial in terms of safety and design issues. VVER-1000 nuclear power plants use horizontal steam generators which demand a detailed thermal hydraulics investigation in order to predict their behavior during normal and transient operational conditions. Two phase flow field simulation on adjacent tube bundles is important in obtaining logical numerical results. However, the complexity of the tube bundles, due to geometry and arrangement, makes it complicated. Employment of porous media is suggested to simplify numerical modeling. This study presents the use of porous media to simulate the tube bundles within a general-purpose computational fluid dynamics code. Solved governing equations are generalized phase continuity, momentum, and energy equations. Boundary conditions, as one of the main challenges in this numerical analysis, are optimized. The model has been verified and tuned by simple two-dimensional geometry. It is shown that the obtained vapor volume fraction near the cold and hot collectors predict the experimental results more accurately than in previous studies.

  14. Unsteady flow analysis of a two-phase hydraulic coupling

    Science.gov (United States)

    Hur, N.; Kwak, M.; Lee, W. J.; Moshfeghi, M.; Chang, C.-S.; Kang, N.-W.

    2016-06-01

    Hydraulic couplings are being widely used for torque transmitting between separate shafts. A mechanism for controlling the transmitted torque of a hydraulic system is to change the amount of working fluid inside the system. This paper numerically investigates three-dimensional turbulent flow in a real hydraulic coupling with different ratios of charged working fluid. Working fluid is assumed to be water and the Realizable k-ɛ turbulence model together with the VOF method are used to investigate two-phase flow inside the wheels. Unsteady simulations are conducted using the sliding mesh technique. The primary wheel is rotating at a fixed speed of 1780 rpm and the secondary wheel rotates at different speeds for simulating different speed ratios. Results are investigated for different blade angles, speed ratios and also different water volume fractions, and are presented in the form of flow patterns, fluid average velocity and also torques values. According to the results, blade angle severely affects the velocity vector and the transmitted torque. Also in the partially-filled cases, air is accumulated in the center of the wheel forming a toroidal shape wrapped by water and the transmitted torque sensitively depends on the water volume fraction. In addition, in the fully-filled case the transmitted torque decreases as the speed ration increases and the average velocity associated with lower speed ratios are higher.

  15. Passive Two-Phase Cooling of Automotive Power Electronics: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, G.; Jeffers, J. R.; Narumanchi, S.; Bennion, K.

    2014-08-01

    Experiments were conducted to evaluate the use of a passive two-phase cooling strategy as a means of cooling automotive power electronics. The proposed cooling approach utilizes an indirect cooling configuration to alleviate some reliability concerns and to allow the use of conventional power modules. An inverter-scale proof-of-concept cooling system was fabricated, and tests were conducted using the refrigerants hydrofluoroolefin HFO-1234yf and hydrofluorocarbon HFC-245fa. Results demonstrated that the system can dissipate at least 3.5 kW of heat with 250 cm3 of HFC-245fa. An advanced evaporator design that incorporates features to improve performance and reduce size was conceived. Simulation results indicate its thermal resistance can be 37% to 48% lower than automotive dual side cooled power modules. Tests were also conducted to measure the thermal performance of two air-cooled condensers--plain and rifled finned tube designs. The results combined with some analysis were then used to estimate the required condenser size per operating conditions and maximum allowable system (i.e., vapor and liquid) temperatures.

  16. Simulation and modeling of two-phase bubbly flows

    Energy Technology Data Exchange (ETDEWEB)

    Sylvain L Pigny; Pierre F Coste [DEN/DER/SSTH, CEA/Grenoble, 38054 Grenoble Cedex 9 (France)

    2005-07-01

    Full text of publication follows: Phenomena related to bubbles in two-phase recirculating flows are investigated, via the computational code SIMMER, concerning an experiment in which air is injected in the lower part of a tank filled of water and initially at rest. Averaged mass and momentum transport equations are solved for air and water. Close to the injector, the formation of individual large bubbles is represented in the calculations, via direct simulation. Small scale phenomena, related to small bubbles behavior or turbulence in the liquid continuous phase, are modeled, in a statistical way, via classical closure laws. In a first calculation, the splitting of large bubbles is not represented. It is shown that this phenomenon, the space scale of which is close to the cell size, cannot be simulated, in view of the present computational resources. Nevertheless, relatively fine meshes are used, for an accurate description of hydrodynamical phenomena, and the splitting phenomenon is too large to be modeled via closure laws. A specific approach for the intermediate scales is therefore developed to represent it. (authors)

  17. COMPARATIVE ANALYSIS OF INTER SIMPLE SEQUENCE REPEATS AND SIMPLE SEQUENCE REPEATS MARKERS: GENETIC ANALYSIS OF DESCHAMPSIA CESPITOSA POPULATIONS GROWING IN METAL CONTAMINATED REGIONS IN CANADA

    Directory of Open Access Journals (Sweden)

    K.K. Nkongolo

    2014-01-01

    Full Text Available Comparative studies conducted on the genetic variation of metal-tolerant populations and their non-metal-tolerant counterparts have been performed on numerous species using isozyme markers. Analysis of genetic differences among plant populations growing in heavy metal-contaminated and uncontaminated regions are limited. The main objectives of the present study were to compare ISSR and microsatellite markers in assessing genetic variation in D. cespitosa populations that colonized metal-contaminated and uncontaminated regions in Northern Ontario, Canada. Total genomic DNA from D. cespitosa samples were amplified with ISSR and SSR primers using optimized PCR conditions. The level of polymorphic loci varies from 46 to 74% for ISSR analysis. The level of observed heterozygosity was moderate to high ranging from 0.44 to 0.68 for the SSR primers used. But no significant difference in genetic variation levels was detected between metal contaminated and uncontaminated sites with SSR markers. There was a significant reduction of polymorphic loci in samples from highly metal-contaminated areas of the Cobalt region compared to the reference sites based on ISSR analysis. Use of a combination of different marker systems is recommended to analyse genetic variation in plant populations.

  18. Two-phase flows and heat transfer within systems with ambient pressure above the thermodynamic critical pressure

    Science.gov (United States)

    Hendricks, R. C.; Braun, M. J.; Mullen, R. L.

    1986-01-01

    In systems where the design inlet and outlet pressure P sub amb are maintained above the thermodynamic critical pressure P sub c, it is often assumed that heat and mass transfer are governed by single-phase relations and that two-phase flows cannot occur. This simple rule of thumb is adequate in many low-power designs but is inadequate for high-performance turbomachines, boilers, and other systems where two-phase regions can exist even though P sub amb P sub c. Heat and mass transfer and rotordynamic-fluid-mechanic restoring forces depend on momentum differences, and those for a two-phase zone can differ significantly from those for a single-phase zone. By using a laminar, variable-property bearing code and a rotating boiler code, pressure and temperature surfaces were determined that illustrate nesting of a two-phase region within a supercritical pressure region. The method of corresponding states is applied to bearings with reasonable rapport.

  19. STUDIES OF TWO-PHASE PLUMES IN STRATIFIED ENVIRONMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Scott A. Socolofsky; Brian C. Crounse; E. Eric Adams

    1998-11-18

    Two-phase plumes play an important role in the more practical scenarios for ocean sequestration of CO{sub 2}--i.e. dispersing CO{sub 2} as a buoyant liquid from either a bottom-mounted or ship-towed pipeline. Despite much research on related applications, such as for reservoir destratification using bubble plumes, our understanding of these flows is incomplete, especially concerning the phenomenon of plume peeling in a stratified ambient. To address this deficiency, we have built a laboratory facility in which we can make fundamental measurements of plume behavior. Although we are using air, oil and sediments as our sources of buoyancy (rather than CO{sub 2}), by using models, our results can be directly applied to field scale CO{sub 2} releases to help us design better CO{sub 2} injection systems, as well as plan and interpret the results of our up-coming international field experiment. The experimental facility designed to study two-phase plume behavior similar to that of an ocean CO{sub 2} release includes the following components: 1.22 x 1.22 x 2.44 m tall glass walled tank; Tanks and piping for the two-tank stratification method for producing step- and linearly-stratified ambient conditions; Density profiling system using a conductivity and temperature probe mounted to an automated depth profiler; Lighting systems, including a virtual point source light for shadowgraphs and a 6 W argon-ion laser for laser induced fluorescence (LIF) imaging; Imaging system, including a digital, progressive scanning CCD camera, computerized framegrabber, and image acquisition and analysis software; Buoyancy source diffusers having four different air diffusers, two oil diffusers, and a planned sediment diffuser; Dye injection method using a Mariotte bottle and a collar diffuser; and Systems integration software using the Labview graphical programming language and Windows NT. In comparison with previously reported experiments, this system allows us to extend the parameter range of

  20. Numerical flow analyses of a two-phase hydraulic coupling

    Energy Technology Data Exchange (ETDEWEB)

    Hur, N.; Kwak, M.; Moshfeghi, M. [Sogang University, Seoul (Korea, Republic of); Chang, C.-S.; Kang, N.-W. [VS Engineering, Seoul (Korea, Republic of)

    2017-05-15

    We investigated flow characteristics in a hydraulic coupling at different charged water conditions and speed ratios. Hence, simulations were performed for three-dimensional two-phase flow by using the VOF method. The realizable k-ε turbulence model was adopted. To resolve the interaction of passing blades of the primary and secondary wheels, simulations were conducted in the unsteady framework using a sliding grid technique. The results show that the water-air distribution inside the wheel is strongly dependent upon both amount of charged water and speed ratio. Generally, air is accumulated in the center of the wheel, forming a toroidal shape wrapped by the circulating water. The results also show that at high speed ratios, the solid-body-like rotation causes dry areas on the periphery of the wheels and, hence, considerably decreases the circulating flow rate and the transmitted torque. Furthermore, the momentum transfer was investigated through the concept of a mass flux triangle based on the local velocity multiplied by the local mixture density instead of the velocity triangle commonly used in a single-phase turbomachine analysis. Also, the mass fluxes along the radius of the coupling in the partially charged and fully charged cases were found to be completely different. It is shown that the flow rate at the interfacial plane and also the transmitted torque are closely related and are strongly dependent upon both the amount of charged water and speed ratio. Finally, a conceptual categorization together with two comprehensive maps was provided for the torque transmission and also circulating flow rates. These two maps in turn exhibit valuable engineering information and can serve as bases for an optimal design of a hydraulic coupling.

  1. A novel region-growing based semi-automatic segmentation protocol for three-dimensional condylar reconstruction using cone beam computed tomography (CBCT.

    Directory of Open Access Journals (Sweden)

    Tong Xi

    Full Text Available OBJECTIVE: To present and validate a semi-automatic segmentation protocol to enable an accurate 3D reconstruction of the mandibular condyles using cone beam computed tomography (CBCT. MATERIALS AND METHODS: Approval from the regional medical ethics review board was obtained for this study. Bilateral mandibular condyles in ten CBCT datasets of patients were segmented using the currently proposed semi-automatic segmentation protocol. This segmentation protocol combined 3D region-growing and local thresholding algorithms. The segmentation of a total of twenty condyles was performed by two observers. The Dice-coefficient and distance map calculations were used to evaluate the accuracy and reproducibility of the segmented and 3D rendered condyles. RESULTS: The mean inter-observer Dice-coefficient was 0.98 (range [0.95-0.99]. An average 90th percentile distance of 0.32 mm was found, indicating an excellent inter-observer similarity of the segmented and 3D rendered condyles. No systematic errors were observed in the currently proposed segmentation protocol. CONCLUSION: The novel semi-automated segmentation protocol is an accurate and reproducible tool to segment and render condyles in 3D. The implementation of this protocol in the clinical practice allows the CBCT to be used as an imaging modality for the quantitative analysis of condylar morphology.

  2. On the Suitable Regions for Olive (Olea europaea) Growing in China%中国油橄榄适生区研究

    Institute of Scientific and Technical Information of China (English)

    施宗明; 孙卫邦; 祁治林; 李云; 刘金凤

    2011-01-01

    油橄榄在中国引种已50多年,引种初期对其特殊的生态习性了解不够深入,出现了许多问题.作者从近40年的栽培实践中,认真分析了我国亚热带地区与地中海亚热带地区气候的差异,认为中国发展油橄榄生产的最佳适生区是西部干旱河谷地区,其中以甘南白龙江河谷和滇两北及川西南金沙江河谷发展的潜力最大.%Olive tree ( Olea ewopaea) has been introduced into China for more than fifty years. Because of less knowledge about its unique ecological characteristics known by people in China during the early stage, its cropping has been occurred a rugged development. Based on the experience for about forty years of cultivation practice as well as the comparison and analysis about the climate between China and the Mediterranean region for olive growing, it can be concluded that the dry valleys in west China might be suitable areas for developing olive. The most potential regions for developing olive are the bailongjiang Valley in southern Cansu and the Jinshajiang (upper reach of Yangtze River) Valley in the northwestern Yunnan and the southwestern Sichuan.

  3. Numerical simulation of two-phase flow behavior in Venturi scrubber by interface tracking method

    Energy Technology Data Exchange (ETDEWEB)

    Horiguchi, Naoki, E-mail: s1430215@u.tsukuba.ac.jp [Japan Atomic Energy Agency, 2-4, Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, 305-8577 (Japan); Yoshida, Hiroyuki [Japan Atomic Energy Agency, 2-4, Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Abe, Yutaka [University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, 305-8577 (Japan)

    2016-12-15

    Highlights: • Self-priming occur because of pressure balance between inside and outside of throat is confirmed. • VS has similar flow with a Venturi tube except of disturbance and burble flow is considered. • Some of atomization simulated are validated qualitatively by comparison with previous studies. - Abstract: From the viewpoint of protecting a containment vessel of light water reactor and suppressing the diffusion of radioactive materials from a light water reactor, it is important to develop the device which allows a filtered venting of contaminated high pressure gas. In the filtered venting system that used in European reactors, so called Multi Venturi scrubbers System is used to realize filtered venting without any power supply. This system is able to define to be composed of Venturi scrubbers (VS) and a bubble column. In the VS, scrubbing of contaminated gas is promoted by both gas releases through the submerged VS and gas-liquid contact with splay flow formed by liquid suctioned through a hole provided by the pressure difference between inner and outer regions of a throat part of the VS. However, the scrubbing mechanism of the self-priming VS including effects of gas mass flow rate and shape of the VS are understood insufficiently in the previous studies. Therefore, we started numerical and experimental study to understand the detailed two-phase flow behavior in the VS. In this paper, to understand the VS operation characteristics for the filtered venting, we performed numerical simulations of two-phase flow behavior in the VS. In the first step of this study, we perform numerical simulations of supersonic flow by the TPFIT to validate the applicability of the TPFIT for high velocity flow like flow in the VS. In the second step, numerical simulation of two-phase flow behavior in the VS including self-priming phenomena. As the results, dispersed flow in the VS was reproduced in the numerical simulation, as same as the visualization experiments.

  4. A modified Rusanov scheme for shallow water equations with topography and two phase flows

    Science.gov (United States)

    Mohamed, Kamel; Benkhaldoun, F.

    2016-06-01

    In this work, we introduce a finite volume method for numerical simulation of shallow water equations with source terms in one and two space dimensions, and one-pressure model of two-phase flows in one space dimension. The proposed method is composed of two steps. The first, called predictor step, depends on a local parameter allowing to control the numerical diffusion. A strategy based on limiters theory enables to control this parameter. The second step recovers the conservation equation. The scheme can thus be turned to order 1 in the regions where the flow has a strong variation, and order 2 in the regions where the flow is regular. The numerical scheme is applied to several test cases in one and two space dimensions. This scheme demonstrates its well-balanced property, and that it is an efficient and accurate approach for solving shallow water equations with and without source terms, and water faucet problem.

  5. 48 CFR 36.301 - Use of two-phase design-build selection procedures.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Use of two-phase design... ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Two-Phase Design-Build Selection Procedures 36.301 Use of two-phase design-build selection procedures....

  6. 24 CFR 115.201 - The two phases of substantial equivalency certification.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false The two phases of substantial... ENFORCEMENT AGENCIES Certification of Substantially Equivalent Agencies § 115.201 The two phases of.... The Department has developed a two-phase process of substantial equivalency certification....

  7. 2D-gel spot detection and segmentation based on modified image-aware grow-cut and regional intensity information.

    Science.gov (United States)

    Kostopoulou, E; Katsigiannis, S; Maroulis, D

    2015-10-01

    Proteomics, the study of proteomes, has been increasingly utilized in a wide variety of biological problems. The Two-Dimensional Gel Electrophoresis (2D-PAGE) technique is a powerful proteomics technique aiming at separation of the complex protein mixtures. Spot detection and segmentation are fundamental components of 2D-gel image analysis but remain arduous and difficult tasks. Several software packages and academic approaches are available for 2D-gel image spot detection and segmentation. Each one has its respective advantages and disadvantages and achieves a different level of success in dealing with the challenges of 2D-gel image analysis. A common characteristic of the available methods is their dependency on user intervention in order to achieve optimal results, a process that can lead to subjective and non-reproducible results. In this work, the authors propose a novel spot detection and segmentation methodology for 2D-gel images. This work introduces a novel spot detection and spot segmentation methodology that is based on a multi-thresholding scheme applied on overlapping regions of the image, a custom grow-cut algorithm, a region growing scheme and morphological operators. The performance of the proposed methodology is evaluated on real as well as synthetic 2D-gel images using well established statistical measures, including precision, sensitivity, and their weighted measure, F-measure, as well as volumetric overlap, volumetric error and volumetric overlap error. Experimental results show that the proposed methodology outperforms state-of-the-art software packages and methods proposed in the literature and results in more plausible spot boundaries and more accurate segmentation. The proposed method achieved the highest F-measure (94.8%) for spot detection and the lowest volumetric overlap error (8.3%) for the segmentation process. Evaluation against state-of-the-art 2D-gel image analysis software packages and techniques proposed in the literature

  8. Gradient Augmented Level Set Method for Two Phase Flow Simulations with Phase Change

    Science.gov (United States)

    Anumolu, C. R. Lakshman; Trujillo, Mario F.

    2016-11-01

    A sharp interface capturing approach is presented for two-phase flow simulations with phase change. The Gradient Augmented Levelset method is coupled with the two-phase momentum and energy equations to advect the liquid-gas interface and predict heat transfer with phase change. The Ghost Fluid Method (GFM) is adopted for velocity to discretize the advection and diffusion terms in the interfacial region. Furthermore, the GFM is employed to treat the discontinuity in the stress tensor, velocity, and temperature gradient yielding an accurate treatment in handling jump conditions. Thermal convection and diffusion terms are approximated by explicitly identifying the interface location, resulting in a sharp treatment for the energy solution. This sharp treatment is extended to estimate the interfacial mass transfer rate. At the computational cell, a d-cubic Hermite interpolating polynomial is employed to describe the interface location, which is locally fourth-order accurate. This extent of subgrid level description provides an accurate methodology for treating various interfacial processes with a high degree of sharpness. The ability to predict the interface and temperature evolutions accurately is illustrated by comparing numerical results with existing 1D to 3D analytical solutions.

  9. Experimental study of two-phase flows under reduced gravity conditions

    Energy Technology Data Exchange (ETDEWEB)

    Roy, T., E-mail: tirthankar.roy@ntnu.no [Purdue Univ., West Lafayette, Indiana (United States); Norwegian Univ. of Science and Tech., Trondheim (Norway); Liu, Y.; Chen, S.-W.; Hibiki, T.; Ishii, M., E-mail: liu130@purdue.edu, E-mail: hibiki@purdue.edu, E-mail: ishii@purdue.edu [Purdue Univ., West Lafayette, Indiana (United States); Duval, W., E-mail: walter.m.duval@nasa.gov [NASA Glenn Research Center, Cleveland, Ohio (United States)

    2011-07-01

    Study of gas-liquid two-phase flows under reduced gravity conditions is very important for space applications such as active thermal control systems. Two-fluid model along with Interfacial Area Transport Equation (IATE) is a useful tool available to dynamically predict the behavior of such two-phase flows under normal and reduced gravity conditions. As part of a big program experiments were carried out in a 304 mm inner diameter test facility on earth to generate a detailed experimental data base which is required for the evaluation of two-fluid model along with IATE under reduced gravity conditions. In the present case reduced gravity condition is simulated using two-liquids of similar densities. Such a large diameter test section was chosen to study the development of drops to their full. Twelve flow conditions were chosen around predicted bubbly flow to cap-bubbly flow transition region. Detailed local data was obtained at ten radial locations for each of three axial locations using double-sensor conductivity probes. Some of the results are presented here and discussed. (author)

  10. Experimental Study on Two-Phase Flow in Horizontal Rectangular Minichannel with Y-Junction

    Directory of Open Access Journals (Sweden)

    Agus Santoso

    2016-03-01

    Full Text Available An experimental study was conducted to investigate two-phase air-water flow characteristics, in horizontal rectangular minichannel with Y-junction. The width (W, the height (H and the hydraulic diameter (DH of the rectangular cross section for the upstream side of the junction are 4.60 mm, 2.50 mm and 3.24 mm, while those for the downstream side are 2.36 mm, 2.50 mm and 2.43 mm. The entire test section was machined from transparent acrylic block, so that the flow structure could be visualized. Liquid single-phase and air-liquid twophase flow experiments were conducted at room temperature. The flow pattern, the bubble velocity, the bubble length, and the void fraction were measured with a high-speed video camera. Pressure profile upstream and downstream from the junction was also measured for the respective flows, and the pressure loss due to the contraction at the junction was determined from the pressure profiles. Two flow patterns, i.e., slug and annular flows, were observed in the fully-developed region apart from the junction. In the analysis, the frictional pressure drop data, the two-phase frictional multiplier data, bubble velocity data, bubble length data and void fraction data were compared with calculations by some correlations in literatures. In addition, new pressure loss coefficient correlations for the pressure drop at the junction has been proposed. Results of such experiment and analysis are described in the present paper.

  11. Multiparametric Analysis of Oncology Drug Screening with Aqueous Two-Phase Tumor Spheroids.

    Science.gov (United States)

    Shahi Thakuri, Pradip; Ham, Stephanie L; Luker, Gary D; Tavana, Hossein

    2016-11-07

    Spheroids present a biologically relevant three-dimensional model of avascular tumors and a unique tool for discovery of anticancer drugs. Despite being used in research laboratories for several decades, spheroids are not routinely used in the mainstream drug discovery pipeline primarily due to the difficulty of mass-producing uniformly sized spheroids and intense labor involved in handling, drug treatment, and analyzing spheroids. We overcome this barrier using a polymeric aqueous two-phase microtechnology to robotically microprint spheroids of well-defined size in standard 384-microwell plates. We use different cancer cells and show that resulting spheroids grow over time and display characteristic features of solid tumors. We demonstrate the feasibility of robotic, high-throughput screening of 25 standard chemotherapeutics and molecular inhibitors against tumor spheroids of three different cancer cell lines. This screening uses over 7000 spheroids to elicit high quality dose-dependent drug responses from spheroids. To quantitatively compare performance of different drugs, we employ a multiparametric scoring system using half-maximum inhibitory concentration (IC50), maximum inhibition (Emax), and area under the dose-response curve (AUC) to take into account both potency and efficacy parameters. This approach allows us to identify several compounds that effectively inhibit growth of spheroids and compromise cellular viability, and distinguish them from moderately effective and ineffective drugs. Using protein expression analysis, we demonstrate that spheroids generated with the aqueous two-phase microtechnology reliably resolve molecular targets of drug compounds. Incorporating this low-cost and convenient-to-use tumor spheroid technology in preclinical drug discovery will make compound screening with realistic tumor models a routine laboratory technique prior to expensive and tedious animal tests to dramatically improve testing throughput and efficiency and

  12. Growing Pains

    CERN Multimedia

    Katarina Anthony

    2013-01-01

    Heat expands and cold contracts: it’s a simple thermodynamic rule. But when temperatures swing from 300 K to near-absolute zero, this rule can mean a contraction of more than 80 metres across the LHC’s 27-km-long cryogenic system. Keeping this growth in check are compensators (a.k.a. bellows), which shrink and stretch in response to thermodynamic changes. Leak tests and X-rays now underway in the tunnel have revealed that these “joints” might be suffering from growing pains…   This 25-μm weld crack is thought to be the cause of the helium leaks. Prior to the LS1 warm-up, CERN’s cryogenic experts knew of two points in the machine’s cryogenic distribution system that were leaking helium. Fortunately, these leaks were sufficiently small, confined to known sub-sectors of the cryogenic line and – with help from the vacuum team (TE-VSC) – could easily be compensated for. But as the machine warmed up f...

  13. Stability of stratified two-phase flows in inclined channels

    Science.gov (United States)

    Barmak, I.; Gelfgat, A. Yu.; Ullmann, A.; Brauner, N.

    2016-08-01

    Linear stability of the stratified gas-liquid and liquid-liquid plane-parallel flows in the inclined channels is studied with respect to all wavenumber perturbations. The main objective is to predict the parameter regions in which the stable stratified configuration in inclined channels exists. Up to three distinct base states with different holdups exist in the inclined flows, so that the stability analysis has to be carried out for each branch separately. Special attention is paid to the multiple solution regions to reveal the feasibility of the non-unique stable stratified configurations in inclined channels. The stability boundaries of each branch of the steady state solutions are presented on the flow pattern map and are accompanied by the critical wavenumbers and the spatial profiles of the most unstable perturbations. Instabilities of different nature are visualized by the streamlines of the neutrally stable perturbed flows, consisting of the critical perturbation superimposed on the base flow. The present analysis confirms the existence of two stable stratified flow configurations in a region of low flow rates in the countercurrent liquid-liquid flows. These configurations become unstable with respect to the shear mode of instability. It was revealed that in slightly upward inclined flows the lower and middle solutions for the holdup are stable in the part of the triple solution region, while the upper solution is always unstable. In the case of downward flows, in the triple solution region, none of the solutions are stable with respect to the short-wave perturbations. These flows are stable only in the single solution region at low flow rates of the heavy phase, and the long-wave perturbations are the most unstable ones.

  14. On the Stable Numerical Approximation of Two-Phase Flow with Insoluble Surfactant

    CERN Document Server

    Barrett, John W; Nürnberg, Robert

    2013-01-01

    We present a parametric finite element approximation of two-phase flow with insoluble surfactant. This free boundary problem is given by the Navier--Stokes equations for the two-phase flow in the bulk, which are coupled to the transport equation for the insoluble surfactant on the interface that separates the two phases. We combine the evolving surface finite element method with an approach previously introduced by the authors for two-phase Navier--Stokes flow, which maintains good mesh properties. The derived finite element approximation of two-phase flow with insoluble surfactant can be shown to be stable. Several numerical simulations demonstrate the practicality of our numerical method.

  15. Trinarization of μX-ray CT images of partially saturated sand at different water-retention states using a region growing method

    Energy Technology Data Exchange (ETDEWEB)

    Higo, Yosuke, E-mail: higo.yohsuke.5z@kyoto-u.ac.jp [Department of Urban Management, Kyoto University (Japan); Oka, Fusao [Professor Emeritus, Kyoto University (Japan); Morishita, Ryoichi; Matsushima, Yoshiki; Yoshida, Tatsuya [Department of Civil and Earth Resources Engineering, Kyoto University (Japan)

    2014-04-01

    The trinarization of micro-computed tomography (CT) images for partially saturated soils at different water-retention states has been performed to clearly identify the three phases, i.e., the soil particles, the pore water and the pore air. We have proposed a trinarization technique for partially saturated soils whose histograms of the gray values for the three phases overlap each other. The segmentation method used in this study is the region growing method that ensures the spatial continuity of the phases extracted by the segmentation. Micro CT images of a dense sand specimen during the wetting process in a water retention test have been obtained. It has been found that the trinarization of the CT images in a high pore saturation regime provides reasonable results, while that in a low pore saturation regime overestimates the local void ratio. This is because the gray values of the mixels of the soil particle phase and the air phase, due to the partial volume effect, are similar to those of the water phase. It is necessary, therefore, to validate the trinarization results, by a comparison with the test results, because it is difficult to theoretically evaluate the partial volume effect. The correction of the tolerance value for the low pore saturation case with validation has provided better trinarization results. Through the trinarized CT images, the form of the existing pore water at different water-retention states has been discussed.

  16. Heavy Metals Accumulation in Topsoils from the Wine-growing Regions Part 2. Relationships between soil properties and extractable copper contents

    Directory of Open Access Journals (Sweden)

    Marija Romić

    2004-09-01

    Full Text Available The present study analyses the effects of high copper concentrations on its mobility in the soils from the wine-growing regions of the Northwestern Croatia. The aims of this study were to determine the copper distribution in vineyard soils by single extraction procedures, and to relate the total, mobile and mobilisable copper content to several chemical soil characteristics using multiple regression analysis. The total Cu concentrations were determined by an aqua regia procedure. Two other methods were used for evaluating soil available copper: DTPA extraction and calcium chloride extraction. The physical and chemical characteristics (texture, organic C, pH, CaCO3, total P, CEC were determined as well. Both DTPA- and CaCl2-extractable copper were largely explained by the total copper contents, and they were also highly correlated to each other. It was found that the DTPA-extractable copper decreased with increasing cation exchange capacity, but concentrations of CaCl2-extractable copper mainly depend on pH.

  17. Slug flow transitions in horizontal gas/liquid two-phase flows. Dependence on channel height and system pressure for air/water and steam/water two-phase flows

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Hideo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1996-05-01

    The slug flow transitions and related phenomena for horizontal two-phase flows were studied for a better prediction of two-phase flows that typically appear during the reactor loss-of-coolant accidents (LOCAs). For better representation of the flow conditions experimentally, two large-scaled facility: TPTF for high-pressure steam/water two-phase flows and large duct test facility for air/water two-phase flows, were used. The visual observation of the flow using a video-probe was performed in the TPTF experiments for good understanding of the phenomena. The currently-used models and correlations based mostly on the small-scale low-pressure experiments were reviewed and improved based on these experimental results. The modified Taitel-Dukler model for prediction of transition into slug flow from wavy flow and the modified Steen-Wallis correlation for prediction of onset of liquid entrainment from the interfacial waves were obtained. An empirical correlation for the gas-liquid interfacial friction factor was obtained further for prediction of liquid levels at wavy flow. The region of slug flow regime that is generally under influences of the channel height and system pressure was predicted well when these models and correlations were applied together. (author). 90 refs.

  18. Stability of stratified two-phase flows in inclined channels

    CERN Document Server

    Barmak, Ilya; Ullmann, Amos; Brauner, Neima

    2016-01-01

    Linear stability of stratified gas-liquid and liquid-liquid plane-parallel flows in inclined channels is studied with respect to all wavenumber perturbations. The main objective is to predict parameter regions in which stable stratified configuration in inclined channels exists. Up to three distinct base states with different holdups exist in inclined flows, so that the stability analysis has to be carried out for each branch separately. Special attention is paid to the multiple solution regions to reveal the feasibility of non-unique stable stratified configurations in inclined channels. The stability boundaries of each branch of steady state solutions are presented on the flow pattern map and are accompanied by critical wavenumbers and spatial profiles of the most unstable perturbations. Instabilities of different nature are visualized by streamlines of the neutrally stable perturbed flows, consisting of the critical perturbation superimposed on the base flow. The present analysis confirms the existence of ...

  19. Laryngeal two-phase flow in realistic breathing conditions

    OpenAIRE

    Scheinherr, Adam; Bailly, Lucie; Boiron, Olivier; Legou, Thierry; Lagier, Aude; Caillibotte, Georges; Pichelin, Marine

    2013-01-01

    International audience; Liquid aerosols are efficient vectors for drug delivery in upper and lower respiratory tract. Characteristics of inhaled particles, flow properties, and airway morphology represent the main influential factors of the transport mechanisms. Numerous works have been carried out to characterize the airflow behaviour during human breathing [Baier, 1977; Brancatisano, 1983], and to determine the trajectories of inhaled particles through the extrathoracic region. Recent studi...

  20. Modeling of Two-Phase Immiscible Flow with Moving Contact Lines

    Science.gov (United States)

    Abu Alsaud, Moataz; Soulaine, Cyprien; Riaz, Amir; Tchelepi, Hamdi; Stanford University Collaboration; University of Maryland, College Park Collaboration

    2015-11-01

    A new numerical method based on the implicit interface approach on Cartesian grids is proposed for modeling two-phase immiscible flow with moving contact lines. The reinitialization of level-set function by computing the minimum distance to linearly reconstructed interface to obtain signed distance function is extended to include the contact angle boundary condition. The physics of contact line dynamics is implemented using the Cox-Voinov hydrodynamic theory that efficiently captures the effect of the microscopic contact line region. The numerical method is validated through various examples. Parasitic currents are studied in the case of static and constantly advected parabolic interface intersecting the domain boundary with an imposed contact angle. Moving contact line in the viscous dominated regime is studied and verified through comparison with experiments.

  1. Theoretical analysis and numerical computation of dilute solid/liquid two_phase pipe flow

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Starting with the kinetic theory for dilute solid/liquid two_phase flow, a mathematical model is established to predict the flow in a horizontal square pipe and the predictions are compared with LDV measurements. The present model predicts correctly two types of patterns of the vertical distribution of particle concentration observed in experiments, and also gives different patterns of the distribution of particle fluctuating energy. In the core region of the pipe, the predicted mean velocity of particles is smaller than that of liquid, but near the pipe bottom the reverse case occurs. In addition, full attention is paid to the mechanism for the vertical distribution of the average properties of particles such as concentration and mean velocity. From the kinetic_theory point of view, the cause of formation for different patterns of the vertical concentration distribution is not only related to the lift force exerted on a particle, but also related to the distribution of particle fluctuating energy.

  2. Existence domains for invariant reactions in binary regular solution phase diagrams exhibiting two phases

    Indian Academy of Sciences (India)

    B Nageswara Sarma; S Srinivas Prasad; S Vijayvergiya; V Bharath Kumar; S Lele

    2003-06-01

    The thermodynamic origin of various types of phase diagrams in simple binary systems exhibiting two phases (e.g. a liquid and a solid phase) has been examined using the regular solution model. The necessary conditions for the occurrence of each of these types are identified in terms of the appropriate intersections of the miscibility gap boundaries (in solid/liquid phases) and the liquidus/solidus/iso- curves. Thus, the regions of occurrence of the different types of possible phase diagrams in the space of the regular solution interchange energy parameters (, ) are clearly delineated. This analysis makes it easier to make intelligent initial selections of model (energy) parameters for their optimization in the calculation of phase diagrams using thermodynamic models such as CALPHAD/CVM.

  3. Ice melting and downward transport of meltwater by two-phase flow in Europa's ice shell

    Science.gov (United States)

    Kalousová, Klára; Souček, Ondřej; Tobie, Gabriel; Choblet, Gaël.; Čadek, Ondřej

    2014-03-01

    With its young surface, very few impact craters, and the abundance of tectonic and cryovolcanic features, Europa has likely been subjected to relatively recent endogenic activity. Morphological analyses of chaos terrains and double ridges suggest the presence of liquid water within the ice shell a few kilometers below the surface, which may result from enhanced tidal heating. A major issue concerns the thermal/gravitational stability of these water reservoirs. Here we investigate the conditions under which water can be generated and transported through Europa's ice shell. We address particularly the downward two-phase flow by solving the equations for a two-phase mixture of water ice and liquid water in one-dimensional geometry. In the case of purely temperate ice, we show that water is transported downward very efficiently in the form of successive porosity waves. The time needed to transport the water from the subsurface region to the underlying ocean varies between ˜1 and 100 kyr, depending mostly on the ice permeability. We further show that water produced in the head of tidally heated hot plumes never accumulates at shallow depths and is rapidly extracted from the ice shell (within less than a few hundred kiloyears). Our calculations indicate that liquid water will be largely absent in the near subsurface, with the possible exception of cold conductive regions subjected to strong tidal friction. Recently active double ridges subjected to large tidally driven strike-slip motions are perhaps the most likely candidates for the detection of transient water lenses at shallow depths on Europa.

  4. Preliminary Study on Norovirus, Hepatitis A Virus, Escherichia coli and their Potential Seasonality in Shellfish from Different Growing and Harvesting Areas in Sardinia Region

    Science.gov (United States)

    Fattaccio, Maria Caterina; Salza, Sara; Canu, Antonella; Marongiu, Edoardo; Pisanu, Margherita

    2014-01-01

    Edible lamellibranch molluscs can be involved in foodborne disease and infections of varying severity. They are filter feeding animals able to retain and concentrate in their organism bacteria, parasites, viruses and biotoxins marine algae present in their external environment. Major shellfish harvesting and relaying areas from different areas in Sardinia region were defined and studied by analysing different physicochemical parameters in the water and the levels of Escherichia coli (E. coli), Norovirus (NoVs) genogroup I (NoVGI), NoVs genogroup II (NoVGII) and hepatitis A virus (HAV) in the shellfish harvested and farmed from 2009 to 2011. During that period the identification of the viral agents was carried out by one step real-time reverse transcriptase-polymerase chain reaction and Escherichia coli according to ISO TS 16649-3:2005 standard method. A total of 1266 shellfish samples were tested for NoVGI, NoVGII, HAV and faecal indicators. Norovirus contamination was found in 337 samples (26.6%); only one sample of mussels was positive for HAV (0.08%); while E. coli prevalence was 3.8% in shellfish. The probability of observing shellfish samples positive for NoVs, HAV and E. coli presence was associated with harvesting, growing and relaying areas, period of sampling, environmental parameters, animal species (P<0.05). Although the higher prevalence rate of human enteropathogenic viruses was found in the winter period, we did not observe a significant relationship between the effect of seawater temperature (seasonality) and NoVs presence all over the study period; in fact, according to statistical analysis, the presence of human enteric viruses does not appear to be related to water temperature.

  5. Growing Region Segmentation Software (GRES) for quantitative magnetic resonance imaging of multiple sclerosis: intra- and inter-observer agreement variability: a comparison with manual contouring method.

    Science.gov (United States)

    Parodi, Roberto C; Sardanelli, Francesco; Renzetti, Paolo; Rosso, Elisabetta; Losacco, Caterina; Ferrari, Alessandra; Levrero, Fabrizio; Pilot, Alberto; Inglese, Matilde; Mancardi, Giovanni L

    2002-04-01

    Lesion area measurement in multiple sclerosis (MS) is one of the key points in evaluating the natural history and in monitoring the efficacy of treatments. This study was performed to check the intra- and inter-observer agreement variability of a locally developed Growing Region Segmentation Software (GRES), comparing them to those obtained using manual contouring (MC). From routine 1.5-T MRI study of clinically definite multiple sclerosis patients, 36 lesions seen on proton-density-weighted images (PDWI) and 36 enhancing lesion on Gd-DTPA-BMA-enhanced T1-weighted images (Gd-T1WI) were randomly chosen and were evaluated by three observers. The mean range of lesion size was 9.9-536.0 mm(2) on PDWI and 3.6-57.2 mm(2) on Gd-T1WI. The median intra- and inter-observer agreement were, respectively, 97.1 and 90.0% using GRES on PDWI, 81.0 and 70.0% using MC on PDWI, 88.8 and 80.0% using GRES on Gd-T1WI, and 85.8 and 70.0% using MC on Gd-T1WI. The intra- and inter-observer agreements were significantly greater for GRES compared with MC ( PGRES an MC for Gd-T1WI. The intra-observer variability for GRES was significantly lower on both PDWI ( P=0.0001) and Gd-T1WI ( P=0.0067), whereas for MC the same result was found only for PDWI ( P=0.0147). These data indicate that GRES reduces both the intra- and the inter-observer variability in assessing the area of MS lesions on PDWI and may prove useful in multicentre studies.

  6. Preliminary Study on Norovirus, Hepatitis A Virus, Escherichia coli and their Potential Seasonality in Shellfish from Different Growing and Harvesting Areas in Sardinia Region.

    Science.gov (United States)

    Bazzardi, Riccardo; Fattaccio, Maria Caterina; Salza, Sara; Canu, Antonella; Marongiu, Edoardo; Pisanu, Margherita

    2014-04-17

    Edible lamellibranch molluscs can be involved in foodborne disease and infections of varying severity. They are filter feeding animals able to retain and concentrate in their organism bacteria, parasites, viruses and biotoxins marine algae present in their external environment. Major shellfish harvesting and relaying areas from different areas in Sardinia region were defined and studied by analysing different physicochemical parameters in the water and the levels of Escherichia coli (E. coli), Norovirus (NoVs) genogroup I (NoVGI), NoVs genogroup II (NoVGII) and hepatitis A virus (HAV) in the shellfish harvested and farmed from 2009 to 2011. During that period the identification of the viral agents was carried out by one step real-time reverse transcriptase-polymerase chain reaction and Escherichia coli according to ISO TS 16649-3:2005 standard method. A total of 1266 shellfish samples were tested for NoVGI, NoVGII, HAV and faecal indicators. Norovirus contamination was found in 337 samples (26.6%); only one sample of mussels was positive for HAV (0.08%); while E. coli prevalence was 3.8% in shellfish. The probability of observing shellfish samples positive for NoVs, HAV and E. coli presence was associated with harvesting, growing and relaying areas, period of sampling, environmental parameters, animal species (P<0.05). Although the higher prevalence rate of human enteropathogenic viruses was found in the winter period, we did not observe a significant relationship between the effect of seawater temperature (seasonality) and NoVs presence all over the study period; in fact, according to statistical analysis, the presence of human enteric viruses does not appear to be related to water temperature.

  7. Preliminary study on Norovirus, hepatitis A virus, Escherichia coli and their potential seasonality in shellfish from different growing and harvesting areas in Sardinia region

    Directory of Open Access Journals (Sweden)

    Riccardo Bazzardi

    2014-06-01

    Full Text Available Edible lamellibranch molluscs can be involved in foodborne disease and infections of varying severity. They are filter feeding animals able to retain and concentrate in their organism bacteria, parasites, viruses and biotoxins marine algae present in their external environment. Major shellfish harvesting and relaying areas from different areas in Sardinia region were defined and studied by analysing different physicochemical parameters in the water and the levels of Escherichia coli (E. coli, Norovirus (NoVs genogroup I (NoVGI, NoVs genogroup II (NoVGII and hepatitis A virus (HAV in the shellfish harvested and farmed from 2009 to 2011. During that period the identification of the viral agents was carried out by one step real-time reverse transcriptase-polymerase chain reaction and Escherichia coli according to ISO TS 16649- 3:2005 standard method. A total of 1266 shellfish samples were tested for NoVGI, NoVGII, HAV and faecal indicators. Norovirus contamination was found in 337 samples (26.6%; only one sample of mussels was positive for HAV (0.08%; while E. coli prevalence was 3.8% in shellfish. The probability of observing shellfish samples positive for NoVs, HAV and E. coli presence was associated with harvesting, growing and relaying areas, period of sampling, environmental parameters, animal species (P<0.05. Although the higher prevalence rate of human enteropathogenic viruses was found in the winter period, we did not observe a significant relationship between the effect of seawater temperature (seasonality and NoVs presence all over the study period; in fact, according to statistical analysis, the presence of human enteric viruses does not appear to be related to water temperature.

  8. Heat transfer studies in a spiral plate heat exchanger for water: palm oil two phase system

    Directory of Open Access Journals (Sweden)

    S. Ramachandran

    2008-09-01

    Full Text Available Experimental studies were conducted in a spiral plate heat exchanger with hot water as the service fluid and the two-phase system of water – palm oil in different mass fractions and flow rates as the cold process fluid. The two phase heat transfer coefficients were correlated with Reynolds numbers (Re in the form h = a Re m, adopting an approach available in literature for two phase fluid flow. The heat transfer coefficients were also related to the mass fraction of palm oil for identical Reynolds numbers. The two-phase multiplier (ratio of the heat transfer coefficient of the two phase fluid and that of the single phase fluid was correlated with the Lockhart Martinelli parameter in a polynomial form. This enables prediction of the two-phase coefficients using single-phase data. The predicted coefficients showed a spread of ± 10 % in the laminar range.

  9. Cloud Point and Liquid-Liquid Equilibrium Behavior of Thermosensitive Polymer L61 and Salt Aqueous Two-Phase System.

    Science.gov (United States)

    Rao, Wenwei; Wang, Yun; Han, Juan; Wang, Lei; Chen, Tong; Liu, Yan; Ni, Liang

    2015-06-25

    The cloud point of thermosensitive triblock polymer L61, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO), was determined in the presence of various electrolytes (K2HPO4, (NH4)3C6H5O7, and K3C6H5O7). The cloud point of L61 was lowered by the addition of electrolytes, and the cloud point of L61 decreased linearly with increasing electrolyte concentration. The efficacy of electrolytes on reducing cloud point followed the order: K3C6H5O7 > (NH4)3C6H5O7 > K2HPO4. With the increase in salt concentration, aqueous two-phase systems exhibited a phase inversion. In addition, increasing the temperature reduced the concentration of salt needed that could promote phase inversion. The phase diagrams and liquid-liquid equilibrium data of the L61-K2HPO4/(NH4)3C6H5O7/K3C6H5O7 aqueous two-phase systems (before the phase inversion but also after phase inversion) were determined at T = (25, 30, and 35) °C. Phase diagrams of aqueous two-phase systems were fitted to a four-parameter empirical nonlinear expression. Moreover, the slopes of the tie-lines and the area of two-phase region in the diagram have a tendency to rise with increasing temperature. The capacity of different salts to induce aqueous two-phase system formation was the same order as the ability of salts to reduce the cloud point.

  10. Exact Integral Solutions for Two-Phase Flow

    Science.gov (United States)

    McWhorter, David B.; Sunada, Daniel K.

    1990-03-01

    Exact integral solutions for the horizontal, unsteady flow of two viscous, incompressible fluids are derived. Both one-dimensional and radial displacements are calculated with full consideration of capillary drive and for arbitrary capillary-hydraulic properties. One-dimensional, unidirectional displacement of a nonwetting phase is shown to occur increasingly like a shock front as the pore-size distribution becomes wider. This is in contrast to the situation when an inviscid nonwetting phase is displaced. The penetration of a nonwetting phase into porous media otherwise saturated by a wetting phase occurs in narrow, elongate distributions. Such distributions result in rapid and extensive penetration by the nonwetting phase. The process is remarkably sensitive to the capillary-hydraulic properties that determine the value of knw/kw at large wetting phase saturations, a region in which laboratory measurements provide the least resolution. The penetration of a nonwetting phase can be expected to be dramatically affected by the presence of fissures, worm holes, or other macropores. Calculations for radial displacement of a nonwetting phase resident at a small initial saturation show the displacement to be inefficient. The fractional flow of the nonwetting phase falls rapidly and, for a specific example, becomes 1% by the time one pore volume of water has been injected.

  11. Meso-Scale Modeling of Spall in a Heterogeneous Two-Phase Material

    Energy Technology Data Exchange (ETDEWEB)

    Springer, Harry Keo [Univ. of California, Davis, CA (United States)

    2008-07-11

    The influence of the heterogeneous second-phase particle structure and applied loading conditions on the ductile spall response of a model two-phase material was investigated. Quantitative metallography, three-dimensional (3D) meso-scale simulations (MSS), and small-scale spall experiments provided the foundation for this study. Nodular ductile iron (NDI) was selected as the model two-phase material for this study because it contains a large and readily identifiable second- phase particle population. Second-phase particles serve as the primary void nucleation sites in NDI and are, therefore, central to its ductile spall response. A mathematical model was developed for the NDI second-phase volume fraction that accounted for the non-uniform particle size and spacing distributions within the framework of a length-scale dependent Gaussian probability distribution function (PDF). This model was based on novel multiscale sampling measurements. A methodology was also developed for the computer generation of representative particle structures based on their mathematical description, enabling 3D MSS. MSS were used to investigate the effects of second-phase particle volume fraction and particle size, loading conditions, and physical domain size of simulation on the ductile spall response of a model two-phase material. MSS results reinforce existing model predictions, where the spall strength metric (SSM) logarithmically decreases with increasing particle volume fraction. While SSM predictions are nearly independent of applied load conditions at lower loading rates, which is consistent with previous studies, loading dependencies are observed at higher loading rates. There is also a logarithmic decrease in SSM for increasing (initial) void size, as well. A model was developed to account for the effects of loading rate, particle size, matrix sound-speed, and, in the NDI-specific case, the probabilistic particle volume fraction model. Small-scale spall experiments were designed

  12. Aqueous two-phase system based on natural quaternary ammonium compounds for the extraction of proteins.

    Science.gov (United States)

    Zeng, Chao-Xi; Xin, Rui-Pu; Qi, Sui-Jian; Yang, Bo; Wang, Yong-Hua

    2016-02-01

    Aqueous two-phase systems, based on the use of natural quaternary ammonium compounds, were developed to establish a benign biotechnological route for efficient protein separation. In this study, aqueous two-phase systems of two natural resources betaine and choline with polyethyleneglycol (PEG400/600) or inorganic salts (K2 HPO4 /K3 PO4 ) were formed. It was shown that in the K2 HPO4 -containing aqueous two-phase system, hydrophobic interactions were an important driving force of protein partitioning, while protein size played a vital role in aqueous two-phase systems that contained polyethylene glycol. An extraction efficiency of more than 90% for bovine serum albumin in the betaine/K2 HPO4 aqueous two-phase system can be obtained, and this betaine-based aqueous two-phase system provided a gentle and stable environment for the protein. In addition, after investigation of the cluster phenomenon in the betaine/K2 HPO4 aqueous two-phase systems, it was suggested that this phenomenon also played a significant role for protein extraction in this system. The development of aqueous two-phase systems based on natural quaternary ammonium compounds not only provided an effective and greener method of aqueous two-phase system to meet the requirements of green chemistry but also may help to solve the mystery of the compartmentalization of biomolecules in cells.

  13. Study on two-phase countercurrent flow and transport phenomenon in PEM of a direct methanol fuel cell

    Institute of Scientific and Technical Information of China (English)

    WANG; Jiang; SHI; Mingheng

    2006-01-01

    Based on the requirement of water management for a direct methanol fuel cell, this paper analyzes qualitatively the mechanism of occurrence and development of a two-phase countercurrent flow with corresponding transport phenomenon in the PEM. A one-dimensional, steady state quantitative model of heat and mass transfer in internal volumetric ohmic heating porous media saturated by liquid and vapor phases is developed. The effects of capillarity, electro-osmotic drag and phase change are included. Two important formulas to calculate the theoretical length of two-phase zone δt and determine the critical criterion |-ω/γ|cr for dryout in PEM are deduced. By use of these two dimensionless parameters, dryout of PEM can be easily predicted. Theoretical temperature, pressure and saturation profiles within the two-phase region are obtained numerically, which can help to explore the performance of a DMFC operating in its ohmic polarization region. The simulation results can be used to determine the catalyst content of cathode catalyst layer and the corresponding optimal thickness of PEM.

  14. Correlations for predicting single phase and two-phase flow pressure drop in pebble bed flow channels

    Energy Technology Data Exchange (ETDEWEB)

    Bai Bofeng, E-mail: bfbai@mail.xjtu.edu.cn [State Key Laboratory of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Liu Maolong; Lv Xiaofei; Yan Junjie [State Key Laboratory of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Yan Xiao; Xiao Zejun [Lab of Bubble Physics and Natural Circulation, Nuclear Power Institute of China, Chengdu 610041 (China)

    2011-12-15

    An experimental study was conducted on the pressure drop of the single phase and the air-water two-phase flow in the bed of rectangular cross sections densely filled with uniform spheres. Three kinds of glass spheres with different equivalent diameters (3 mm, 6 mm, and 8 mm) were used for the establishment of the test sections. The Reynolds number in the experiment ranged from a dozen to thousands for the single-phase flow and from hundreds to tens of thousands for the two-phase flow. In the present flow-regime model, the bed was subdivided into a near-wall region and a central region in order to take the wall effect into account to improve the prediction at low tube-to-particle diameter ratios. Improved correlations are obtained based on the previous study to consider the single-phase flow pressure drops for finite pebble beds with spherical particles and nonspherical particles by fitting the coefficients of that equation to both the database and the present experiment. The correlation is consistent with the observed physical behavior which explains its comparatively good agreement with the experimental data. A new empirical correlation for the prediction of two-phase flow pressure drops was proposed based on the gas phase relative permeability as a function of the gas phase saturation and the void fraction. The correlation fit well for both experimental data of spherical particles and nonspherical particles.

  15. Line profiles of the two-phase medium broad-line region in active galactic nuclei

    Institute of Scientific and Technical Information of China (English)

    薛随建; 林宣滨; 程福臻; John Kwan

    1996-01-01

    In the framework of BLR in AGNs, i.e. large number of small, cold and dense emission-line clouds immerging in an intercloud hot medium, a delicate radiation model for a typical emission cloud is established, in which the backside photoionization of the cloud against the central continuum source by the scattered diffuse continuum in the hot medium is considered. Under the assumption of the radial kinematics of the BLR clouds, the line profiles for the two important UV emission-lines, Lya and CIV/11549 are computed; and based on these calculations, various physical factors that affect the properties of the emission-line profiles are discussed. It is concluded that: (i) when the BLR clouds is inflow, there exists a confining hot medium with density around 2 x 105 cm-3. In this case, theoretical line profiles agree well with the observational; (ii) both symmetric Lya and nearly symmetric CIV line profiles show blue velocity shifts, the quantities of which are sensitive to the cutoff of the outer radius of t

  16. Finite temperature collective modes in a two phase coexistence region of asymmetric nuclear matter

    CERN Document Server

    Aguirre, R M

    2010-01-01

    The relation between collective modes and the phase transition in low density nuclear matter is examined. The dispersion relations for collective modes in a linear approach are evaluated within a Landau-Fermi liquid scheme by assuming coexisting phases in thermodynamical equilibrium. Temperature and isospin composition are taken as relevant parameters. The in-medium nuclear interaction is taken from a recently proposed density functional model. We found significative modifications in the energy spectrum, within certain range of temperatures and isospin asymmetry, due to the separation of matter into independent phases. We conclude that detailed calculations should not neglect this effect.

  17. A two-scale second-order moment two-phase turbulence model for simulating dense gas-particle flows

    Institute of Scientific and Technical Information of China (English)

    Zhuoxiong Zeng; Lixing Zhou; Jian Zhang; Keren Wang

    2005-01-01

    A two-scale second-order moment two-phase turbulence model accounting for inter-particle collision is developed, based on the concepts of particle large-scale fluctuation due to turbulence and particle small-scale fluctuation due to collision and through a unified treatment of these two kinds of fluctuations. The proposed model is used to simulate gas-particle flows in a channel and in a downer. Simulation results are in agreement with the experimental results reported in references and are near the results obtained using the single-scale second-order moment two-phase turbulence model superposed with a particle collision model (USM-θ model)in most regions.

  18. CALCULATION ON TWO-PHASE FLOW TRANSIENTS AND THEIR EXPERIMENTAL RESEARCH

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    From basic equations of gas-liquid, solid-liquid, solid-gas two-phase flow, the calculating method on flowtransients of two-phase flow is developed by means of characteristic method. As one example, a gas-liquid flow transientis calculated and it agrees well with the experimental result. It is shown that the method is satisfactory for engineeringdemand.

  19. 48 CFR 570.105-2 - Two-phase design-build selection procedures.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Two-phase design-build... ADMINISTRATION SPECIAL CONTRACTING PROGRAMS ACQUIRING LEASEHOLD INTERESTS IN REAL PROPERTY General 570.105-2 Two..., you must use the two-phase design-build selection procedures in section 303M of the Federal Property...

  20. Two-phase flow experimental studies in micro-models (Utrecht Studies in Earth Sciences 034)

    NARCIS (Netherlands)

    Karadimitriou, N.K.

    2013-01-01

    The aim of this research project was to put more physics into theories of two-phase flow. The significance of including interfacial area as a separate variable in two-phase flow and transport models was investigated. In order to investigate experimentally the significance of the inclusion of interfa

  1. NASA Physical Sciences - Presentation to Annual Two Phase Heat Transfer International Topical Team Meeting

    Science.gov (United States)

    Chiaramonte, Francis; Motil, Brian; McQuillen, John

    2014-01-01

    The Two-phase Heat Transfer International Topical Team consists of researchers and members from various space agencies including ESA, JAXA, CSA, and RSA. This presentation included descriptions various fluid experiments either being conducted by or planned by NASA for the International Space Station in the areas of two-phase flow, flow boiling, capillary flow, and crygenic fluid storage.

  2. NUMERICAL SIMULATION OF CHARGED GAS-LIQUID TWO PHASE JET FLOW IN ELECTROSTATIC SPRAYING

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Multi-fluid k-ε-kp two phase turbulence model is used to simulate charged gas-liquid two phase coaxial jet, which is the transorting flow field in electrostatic spraying. Compared with the results of experiment, charged gas-liquid twophase turbulence can be well predicted by this model.

  3. Solutions of Green s function for Lamb s problem of a two-phase saturated medium

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The solutions of Green's function are significant for simplification of problem on a two-phase saturated medium.Using transformation of axisymmetric cylindrical coordinate and Sommerfeld's integral,superposition of the influence field on a free surface,authors obtained the solutions of a two-phase saturated medium subjected to a concentrated force on the semi-space.

  4. Symmetrical components and power analysis for a two-phase microgrid system

    DEFF Research Database (Denmark)

    Alibeik, M.; Santos Jr., E. C. dos; Blaabjerg, Frede

    2014-01-01

    This paper presents a mathematical model for the symmetrical components and power analysis of a new microgrid system consisting of three wires and two voltages in quadrature, which is designated as a two-phase microgrid. The two-phase microgrid presents the following advantages: 1) constant power...

  5. Experimental Study of gas-liquid two-phase flow affected by wall surface wettability

    Energy Technology Data Exchange (ETDEWEB)

    Takamasa, T. [Faculty of Marine Technology, Tokyo University of Marine Science and Technology, 2-1-6 Etchujima, Koto, Tokyo 135-8533 (Japan); Hazuku, T. [Faculty of Marine Technology, Tokyo University of Marine Science and Technology, 2-1-6 Etchujima, Koto, Tokyo 135-8533 (Japan)], E-mail: hazuku@kaiyodai.ac.jp; Hibiki, T. [School of Nuclear Engineering, Purdue University, 400 Central Drive, West Lafayette, IN 47907-2017 (United States)

    2008-12-15

    To evaluate the effect of wall surface wettability on the characteristics of upward gas-liquid two-phase flow in a vertical pipe, an experimental study was performed using three test pipes: an acrylic pipe, a hydrophilic pipe and a hydrophobic pipe. Basic flow characteristics such as flow patterns, pressure drop and void fraction were measured in these three pipes. In the hydrophilic pipe, a slug to churn flow transition boundary was shifted to a higher gas velocity at a given liquid velocity, whereas a churn to annular flow transition boundary was shifted to a lower gas velocity at a given liquid velocity. In the hydrophobic pipe, an inverted-churn flow regime was observed in the region where the churn flow regime was observed in the acrylic pipe, while a droplet flow regime was observed in the region where an annular flow regime was observed in the acrylic pipe. At a high gas flow rate, the mean void fraction in the hydrophobic pipe was higher than in the acrylic pipe. The effect of surface wettability on frictional pressure loss was confirmed to be insignificant under the present experimental conditions.

  6. Two-phase anaerobic digestion of vegetable market waste fraction of municipal solid waste and development of improved technology for phase separation in two-phase reactor.

    Science.gov (United States)

    Majhi, Bijoy Kumar; Jash, Tushar

    2016-12-01

    Biogas production from vegetable market waste (VMW) fraction of municipal solid waste (MSW) by two-phase anaerobic digestion system should be preferred over the single-stage reactors. This is because VMW undergoes rapid acidification leading to accumulation of volatile fatty acids and consequent low pH resulting in frequent failure of digesters. The weakest part in the two-phase anaerobic reactors was the techniques applied for solid-liquid phase separation of digestate in the first reactor where solubilization, hydrolysis and acidogenesis of solid organic waste occur. In this study, a two-phase reactor which consisted of a solid-phase reactor and a methane reactor was designed, built and operated with VMW fraction of Indian MSW. A robust type filter, which is unique in its implementation method, was developed and incorporated in the solid-phase reactor to separate the process liquid produced in the first reactor. Experiments were carried out to assess the long term performance of the two-phase reactor with respect to biogas production, volatile solids reduction, pH and number of occurrence of clogging in the filtering system or choking in the process liquid transfer line. The system performed well and was operated successfully without the occurrence of clogging or any other disruptions throughout. Biogas production of 0.86-0.889m(3)kg(-1)VS, at OLR of 1.11-1.585kgm(-3)d(-1), were obtained from vegetable market waste, which were higher than the results reported for similar substrates digested in two-phase reactors. The VS reduction was 82-86%. The two-phase anaerobic digestion system was demonstrated to be stable and suitable for the treatment of VMW fraction of MSW for energy generation.

  7. 香樟在徐州地区的引种及前景%Prospect of Growing Camphor Tree in Xuzhou Region

    Institute of Scientific and Technical Information of China (English)

    何树川

    2009-01-01

    Camphor tree has been widely used due to its unique characteritics of large and tall trunk, dense branches and leaves, large and shady canopy,magnificent tree form, long life cycle and evergreen. With global warming,scientific and technological progress and the improvement of plant cultivation techniques, the scope of planting Camphor tree is expanded. In this paper,the conditions and prospect of growing Camphor tree in Xuzhou were illustrated from aspects of biological characteristics,feasibility of growing the trees in Xuzhou, critical techniques of planting and tending..

  8. A MODEL FOR PREDICTING PHASE INVERSION IN OIL-WATER TWO-PHASE PIPE FLOW

    Institute of Scientific and Technical Information of China (English)

    GONG Jing; LI Qing-ping; YAO Hai-yuan; YU Da

    2006-01-01

    Experiments of phase inversion characteristics for horizontal oil-water two-phase flow in a stainless steel pipe loop (25.7 mm inner diameter,52 m long) are conducted. A new viewpoint is brought forward about the process of phase inversion in oil-water two-phase pipe flow. Using the relations between the total free energies of the pre-inversion and post-inversion dispersions, a model for predicting phase inversion in oil-water two-phase pipe flow has been developed that considers the characteristics of pipe flow. This model is compared against other models with relevant data of phase inversion in oil-water two-phase pipe flow. Results indicate that this model is better than other models in terms of calculation precision and applicability. The model is useful for guiding the design for optimal performance and safety in the operation of oil-water two-phase pipe flow in oil fields.

  9. Two-phase aqueous micellar systems: an alternative method for protein purification

    Directory of Open Access Journals (Sweden)

    Rangel-Yagui C. O.

    2004-01-01

    Full Text Available Two-phase aqueous micellar systems can be exploited in separation science for the extraction/purification of desired biomolecules. This article reviews recent experimental and theoretical work by Blankschtein and co-workers on the use of two-phase aqueous micellar systems for the separation of hydrophilic proteins. The experimental partitioning behavior of the enzyme glucose-6-phosphate dehydrogenase (G6PD in two-phase aqueous micellar systems is also reviewed and new results are presented. Specifically, we discuss very recent work on the purification of G6PD using: i a two-phase aqueous micellar system composed of the nonionic surfactant n-decyl tetra(ethylene oxide (C10E4, and (ii a two-phase aqueous mixed micellar system composed of C10E4 and the cationic surfactant decyltrimethylammonium bromide (C10TAB. Our results indicate that the two-phase aqueous mixed (C10E4/C10TAB micellar system can improve significantly the partitioning behavior of G6PD relative to that observed in the two-phase aqueous C10E4 micellar system.

  10. Numerical investigation on the characteristics of two-phase flow in fuel assemblies with spacer grid

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D.; Yang, Z.; Zhong, Y.; Xiao, Y.; Hu, L. [Chongqing Univ. (China). Key Lab. of Low-grade Energy Utilization Technologies and Systems

    2016-07-15

    In pressurized water reactors (PWRs), the spacer grids of the fuel assembly has significant impact on the thermal-hydraulic performance of the fuel assembly. Particularly, the spacer grids with the mixing vanes can dramatically enhance the secondary flow and have significant effect on the void distribution in the fuel assembly. In this paper, the CFD study has been carried out to analyze the effects of the spacer grid with the steel contacts, dimples and mixing vanes on the boiling two-phase flow characteristics, such as the two-phase flow field, the void distribution, and so on. Considered the influence of the boiling phase change on two-phase flow, a boiling model was proposed and applied in the CFD simulation by using the UDF (User Defined Function) method. Furthermore, in order to analyze the effects of the spacer grid with mixing vanes, the adiabatic (without boiling) two-phase flow has also been investigated as comparison with the boiling two-phase flow in the fuel assembly with spacer grids. The CFD simulation on two-phase flow in the fuel assembly with the proposed boiling model can predict the characteristics of two-phase flow better.

  11. Interfacial area and two-phase flow structure development measured by a double-sensor probe

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Waihung; Revankar, S.T.; Ishii, Yoshihiko; Ishii, Mamoru

    1992-06-01

    In this report, we studied the local phasic characters of dispersed flow regime both at the entrance and at the fully developed regions. Since the dispersed phase is distributed randomly in the medium and enclosed in relatively small interfaces, the phasic measurement becomes difficult to obtain. Local probe must be made with a miniaturized sensor in order to reduce the interface distortion. The double-sensor resistivity probe has been widely used in local void fraction and interface velocity measurements because the are small in comparison with the interfaces. It has been tested and proved to be an accurate local phasic measurement tool. In these experiments, a double-sensor probe was employed to measure the local void fraction and interface velocity in an air-water system. The test section was flow regime can be determined by visualization. Furthermore, local phasic measurements can be verified by photographic studies. We concentrated our study on the bubbly flow regime only. The local measurements were conducted at two axial locations, L/D = 8 and 60, in which the first measurement represents the entrance region where the flow develops, and the second measurement represents the fully developed flow region where the radial profile does not change as the flow moves along the axial direction. Four liquid flow rates were chosen in combination with four different gas injection rates. The superficial liquid velocities were j{sub t} = 1.0, 0.6,0.4, and 0.1 m/s and superficial gas velocities were j{sub g} = 0.0965, 0.0696, 0.0384, and 0.0192 m/s. These combinations put the two-phase flow well in the bubbly flow regime. In this sequence of phenomenological studies, the local void fraction, interface area concentration, sauter mean diameter, bubble velocity and bubble frequency were measured.

  12. The use of two-phase molecular dynamics simulations to determine the phase behavior and critical point of propane molecular models.

    Science.gov (United States)

    Patel, Sonal; Wilding, W Vincent; Rowley, Richard L

    2011-01-14

    Molecular dynamics simulations were performed to determine two-phase configurations of model propane molecules below the critical point and in the near-critical, two-phase region. A postprocessor that uses a Monte Carlo method for determination of volumes attributable to each molecule was used to obtain density histograms of the particles from which the bulk coexisting equilibrium vapor and liquid densities were determined. This method of analyzing coexisting densities in a two-phase simulation is straightforward and can be easily implemented for complex, multisite models. Various degrees of internal flexibility in the propane models have little effect on the coexisting densities at temperatures 40 K or more below the critical point, but internal flexibility (angle bending and bond vibrations) does affect the saturated liquid densities in the near-critical region, changing the critical temperature by approximately 20 K. Shorter cutoffs were also found to affect the phase dome and the location of the critical point.

  13. Spacecraft Thermal Management using Advanced Hybrid Two-Phase Loop Technology

    Science.gov (United States)

    2007-02-01

    HYBRID TWO-PHASE LOOPS The schematic of the Hybrid Two-Phase Loop (HTPL) used for a thermal testing is shown in Figure 3. Main components for the...hybrid two-phase loop with single evaporator. The thermal test starts first by turning on the liquid pump to circulate liquid along the loop. Once the...Vapor Out Evaporator Body (E1) Evaporator Body (E2) Total Heat Input Heat Input (E1) Heat Input (E2) Thermal Resistance (E1) FIGURE 10. Thermal test results

  14. Two phase flow bifurcation due to turbulence: transition from slugs to bubbles

    Science.gov (United States)

    Górski, Grzegorz; Litak, Grzegorz; Mosdorf, Romuald; Rysak, Andrzej

    2015-09-01

    The bifurcation of slugs to bubbles within two-phase flow patterns in a minichannel is analyzed. The two-phase flow (water-air) occurring in a circular horizontal minichannel with a diameter of 1 mm is examined. The sequences of light transmission time series recorded by laser-phototransistor sensor is analyzed using recurrence plots and recurrence quantification analysis. Recurrence parameters allow the two-phase flow patterns to be found. On changing the water flow rate we identified partitioning of slugs or aggregation of bubbles.

  15. Numerical simulation of bubbly two-phase flow using the lattice Boltzmann method

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Tadashi; Ebihara, Kenichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2000-09-01

    The two-component two-phase lattice Boltzmann method, in which two distribution functions are used to represent two phases, is used to simulate bubbly flows as one of the fundamental two-phase flow phenomena in nuclear application fields. The inlet flow condition is proposed to simulate steady-state flow fields. The time variation and the spatial distribution of the volume fraction and the interfacial area are measured numerically. The simulation program is parallelized in one direction by the domain decomposition method using the MPI (Message Passing Interface) libraries, and parallel computations are performed on a workstation cluster. (author)

  16. On the nonequilibrium segregation state of a two-phase mixture in a porous column

    DEFF Research Database (Denmark)

    Shapiro, Alexander; Stenby, Erling Halfdan

    1996-01-01

    The problem of segregation of a two-phase multicomponent mixture under the action of thermal gradient, gravity and capillary forces is studied with respect to component distribution in a thick oil-gas-condensate reservoir. Governing equations are derived on the basis of nonequilibrium thermodynam...... thermodynamics. A steady state of the two-phase mixture with nonzero diffusion fluxes and exchange between phases is described. In the case of binary mixtures analytical formulae for saturation, component distribution and flow in the two-phase zone are obtained....

  17. Studies of Two-Phase Gas-Liquid Flow in Microgravity. Ph.D. Thesis, Dec. 1994

    Science.gov (United States)

    Bousman, William Scott

    1995-01-01

    Two-phase gas-liquid flows are expected to occur in many future space operations. Due to a lack of buoyancy in the microgravity environment, two-phase flows are known to behave differently than those in earth gravity. Despite these concerns, little research has been conducted on microgravity two-phase flow and the current understanding is poor. This dissertation describes an experimental and modeling study of the characteristics of two-phase flows in microgravity. An experiment was operated onboard NASA aircraft capable of producing short periods of microgravity. In addition to high speed photographs of the flows, electronic measurements of void fraction, liquid film thickness, bubble and wave velocity, pressure drop and wall shear stress were made for a wide range of liquid and gas flow rates. The effects of liquid viscosity, surface tension and tube diameter on the behavior of these flows were also assessed. From the data collected, maps showing the occurrence of various flow patterns as a function of gas and liquid flow rates were constructed. Earth gravity two-phase flow models were compared to the results of the microgravity experiments and in some cases modified. Models were developed to predict the transitions on the flow pattern maps. Three flow patterns, bubble, slug and annular flow, were observed in microgravity. These patterns were found to occur in distinct regions of the gas-liquid flow rate parameter space. The effect of liquid viscosity, surface tension and tube diameter on the location of the boundaries of these regions was small. Void fraction and Weber number transition criteria both produced reasonable transition models. Void fraction and bubble velocity for bubble and slug flows were found to be well described by the Drift-Flux model used to describe such flows in earth gravity. Pressure drop modeling by the homogeneous flow model was inconclusive for bubble and slug flows. Annular flows were found to be complex systems of ring-like waves and a

  18. Two-phase flow characteristics across sudden expansion in small rectangular channels

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ing Youn [Mechanical Engineering Department, National Yunlin University of Science and Technology, Yunlin 640 (China); Liu, Chung-Che; Chien, Kuo-Hsiang; Wang, Chi-Chuan [D100, Energy and Environment Research Laboratories, Industrial Technology Research Institute, Bldg. 64, 195-6 Section 4, Chung Hsing Road, Chutung, Hsinchu 310 (China)

    2007-11-15

    This study examines the two-phase flow pattern change and frictional pressure loss pertaining to the sudden flow area expansion from a small diameter tube into small rectangular channels. It is found that a unique flow pattern ''liquid jet-like flow pattern'' occurs at a very low quality region of G=100kg/ m{sup 2} s in a test section of 3mm x 9mm. This flow pattern is almost inconceivable for the 3mm x 6mm test section. The pressure difference usually increases with vapor quality but a setback is encountered provided that the liquid jet flow pattern prevails. A phenomenal observation suggests that a conceivable reduction of the pressure difference is related to the liquid jet-like flow pattern, yet a flat or level-off of the pressure difference is seen when the liquid jet-like flow is less pronounced. By contrast, an appreciable increase of pressure difference is seen when the liquid jet-like flow pattern is completely gone. The measured pressure differences are compared with existing correlations/models, whereas none of them gives satisfactory predictions against the present data. It is found that a slight modification to the empirical constant K of Wadle's correlation may give rise to a fair improvement of the predictive ability. (author)

  19. AGN Dusty Tori as a Clumpy Two-Phase Medium: The 10 Micron Silicate Feature

    CERN Document Server

    Stalevski, Marko; Baes, Maarten; Nakos, Theodoros; Popovic, Luka C

    2011-01-01

    We investigated the emission of active galactic nuclei dusty tori in the infrared domain, with a focus on the 10 micron silicate feature. We modeled the dusty torus as a clumpy two-phase medium with high-density clumps and a low-density medium filling the space between the clumps. We employed a three-dimensional radiative transfer code to obtain spectral energy distributions and images of tori at different wavelengths. We calculated a grid of models for different parameters and analyzed the influence of these parameters on the shape of the mid-infrared emission. A corresponding set of clumps-only models and models with a smooth dust distribution is calculated for comparison. We found that the dust distribution, the optical depth and a random arrangement of clumps in the innermost region, all have an impact on the shape and strength of the silicate feature. The 10 micron silicate feature can be suppressed for some parameters, but models with smooth dust distribution are also able to produce a wide range of the...

  20. Numerical Simulations of Two-Phase Flow in a Dorr-Oliver Flotation Cell Model

    Directory of Open Access Journals (Sweden)

    Hassan Fayed

    2013-08-01

    Full Text Available Two-phase (water and air flow in the forced-air mechanically-stirred Dorr-Oliver machine has been investigated using computational fluid dynamics (CFD. A 6 m3 model is considered. The flow is modeled by the Euler-Euler approach, and transport equations are solved using software ANSYS-CFX5. Unsteady simulations are conducted in a 180-degree sector with periodic boundary conditions. Air is injected into the rotor at the rate of 2.63 m3/min, and a uniform bubble diameter is specified. The effects of bubble diameter on velocity field and air volume fraction are determined by conducting simulations for three diameters of 0.5, 1.0, and 2.0 mm. Air volume fraction contours, velocity profiles, and turbulent kinetic energy profiles in different parts of the machine are presented and discussed. Results have been compared to experimental data, and good agreement is obtained for the mean velocity and turbulent kinetic energy profiles in the rotor-stator gap and in the jet region outside stator blades.

  1. Cracking kinetics of two-phase stainless steel alloys in hydrogen gas

    Science.gov (United States)

    Perng, T.-P.; Altstetter, C. J.

    1988-01-01

    The kinetics of hydrogen-induced slow crack growth (SCG) under constant load was studied in two stainless steel alloys containing mixtures of bcc and fcc phases. FERRALIUM 255, a duplex stainless steel, consisting of ˜50 pct austenite in a ferrite matrix, was tested in hydrogen gas at 0 to 100 °C with the loading axis both perpendicular and parallel to the rolling direction. In addition, specimens of AISI 301 were deformed in air in different ways to produce various amounts of bcc phase in an austenite matrix prior to testing in H2 gas at room temperature. The kinetics of subcritical slow crack growth (SCG) in these alloys was compared with that for austenitic and for ferritic stainless steels. The SCG rates were rationalized in terms of differences in hydrogen permeation in the two phases. The results confirm that a higher rate of supply and accumulation of hydrogen in the region ahead of the crack tip allows a higher cracking velocity.

  2. An improved lattice Boltzmann method for incompressible two-phase flows with large density differences

    Science.gov (United States)

    Inamuro, Takaji; Yokoyama, Takaaki; Tanaka, Kentaro; Taniguchi, Motoki

    2013-11-01

    We propose a new LBM for two-phase fluid flows with high density ratios by improving the pressure computing of Inamuro et al.'s method (2004) [J. Comput. Phys. 198 (2004) 628] without solving the pressure Poisson equation. In the proposed method, the velocity and pressure fields are computed by using a single velocity distribution function even for high density ratios and by adjusting the speed of sound in a high density region to satisfy the continuity equation. In order to show the validity of the method, we apply the method to the simulations of a stationary drop, binary droplet collision, rising bubbles, and a milk crown. In a stationary drop, pressure and density profiles are computed, and the effect of a sound speed on time evolution of the pressure field in the drop. In the simulations of a binary droplet collision and rising bubbles, the computed results by the proposed method are compared with those by Inamuro et al.'s method (2004). A thin sheet and tiny drops can be computed in the simulation of a milk crown.

  3. Flow regime transition criteria for two-phase flow in a vertical annulus

    Energy Technology Data Exchange (ETDEWEB)

    Julia, J. Enrique, E-mail: bolivar@emc.uji.es [Departamento de Ingenieria Mecanica y Construccion, Universitat Jaume I., Campus de Riu Sec, 12071 Castellon (Spain); Hibiki, Takashi [School of Nuclear Engineering, Purdue University, 400 Central Dr., West Lafayette, IN 47907-2017 (United States)

    2011-10-15

    Highlights: > Flow regime transition model is presented for two-phase flows in a vertical annulus. > The transition criteria is easy to be implemented in computational codes. > Final equations do not need experimental input. > New developed model shows better predicting capabilities than existing correlations. > New developed model shows good predicting capabilities in boiling flow. - Abstract: In this work, a new flow regime transition model is proposed for two-phase flows in a vertical annulus. Following previous works, the flow regimes considered are bubbly (B), slug (S) or cap-slug (CS), churn (C) and annular (A). The B to CS transition is modeled using the maximum bubble package criteria of small bubbles. The S to C transition takes place for small annulus perimeter flow channels and it is assumed to occur when the mean void fraction over the entire region exceeds that over the slug-bubble section. If the annulus perimeter is larger that the distorted bubble limit the cap-slug flow regime will be considered since in these conditions it is not possible to distinguish between cap and partial-slug bubbles. The CS to C transition is modeled using the maximum bubble package criteria. However, this transition considers the coalescence of cap and spherical bubbles in order to take into account the flow channel geometry. Finally, the C to A transition is modeled assuming two different mechanisms, (a) flow reversal in the liquid film section along large bubbles; (b) destruction on liquid slugs or large waves by entrainment or deformation. In the S to C and C to A flow regime transitions the annulus flow channel is considered as a rectangular flow channel with no side walls. In all the modeled transitions the drift-flux model is used to obtain the final correlations. The final equations for every flow regime transition are easy to be implemented in computational codes and not experimental input is needed. The prediction accuracy of the newly developed model has been

  4. Bubble Generation in a Flowing Liquid Medium and Resulting Two-Phase Flow in Microgravity

    Science.gov (United States)

    Pais, S. C.; Kamotani, Y.; Bhunia, A.; Ostrach, S.

    1999-01-01

    The present investigation reports a study of bubble generation under reduced gravity conditions, using both a co-flow and a cross-flow configuration. This study may be used in the conceptual design of a space-based thermal management system. Ensuing two-phase flow void fraction can be accurately monitored using a single nozzle gas injection system within a continuous liquid flow conduit, as utilized in the present investigation. Accurate monitoring of void fraction leads to precise control of heat and mass transfer coefficients related to a thermal management system; hence providing an efficient and highly effective means of removing heat aboard spacecraft or space stations. Our experiments are performed in parabolic flight aboard the modified DC-9 Reduced Gravity Research Aircraft at NASA Lewis Research Center, using an air-water system. For the purpose of bubble dispersion in a flowing liquid, we use both a co-flow and a cross-flow configuration. In the co-flow geometry, air is introduced through a nozzle in the same direction with the liquid flow. On the other hand, in the cross-flow configuration, air is injected perpendicular to the direction of water flow, via a nozzle protruding inside the two-phase flow conduit. Three different flow conduit (pipe) diameters are used, namely, 1.27 cm, 1.9 cm and 2.54 cm. Two different ratios of nozzle to pipe diameter (D(sub N))sup * are considered, namely (D(sub N))sup * = 0.1 and 0.2, while superficial liquid velocities are varied from 8 to 70 cm/s depending on flow conduit diameter. It is experimentally observed that by holding all other flow conditions and geometry constant, generated bubbles decrease in size with increase in superficial liquid velocity. Detached bubble diameter is shown to increase with air injection nozzle diameter. Likewise, generated bubbles grow in size with increasing pipe diameter. Along the same lines, it is shown that bubble frequency of formation increases and hence the time to detachment of a

  5. Two-phase modelling of equiaxed crystal sedimentation and thermomechanic stress development in the sedimented packed bed

    Science.gov (United States)

    Ludwig, A.; Vakhrushev, A.; Holzmann, T.; Wu, M.; Kharicha, A.

    2015-06-01

    During many industrial solidification processes equiaxed crystals form, grow and move. When those crystals are small they are carried by the melt, whereas when getting larger they sediment. As long as the volume fraction of crystals is below the packing limit, they are able to move relatively free. Crystals being backed in a so called packed bed form a semi-solid slurry, which may behave like a visco-plastic material. In addition, cooling-induced density increase of both, liquid and solid phases might lead to shrinkage of the whole casting domain. So deformation happens and gaps between casting and mold occur. In the present work, a two-phase Eulerian-Eulerian volume averaging model for describing the motion of equiaxed crystals in the melt is combined with a similar two-phase model for describing the dynamic of the packed bed. As constitutive equation for the solid skeleton in the packed bed Norton-Hoff law is applied. Shrinkage induced by density changes in the liquid or the solid phase is explicitly taken into account and handled by remeshing the calculation domain accordantly.

  6. Critical Regimes of Two-Phase Flows with a Polydisperse Solid Phase

    CERN Document Server

    Barsky, Eugene

    2010-01-01

    This book brings to light peculiarities of the formation of critical regimes of two-phase flows with a polydisperse solid phase. A definition of entropy is formulated on the basis of statistical analysis of these peculiarities. The physical meaning of entropy and its correlation with other parameters determining two-phase flows are clearly defined. The interrelations and main differences between this entropy and the thermodynamic one are revealed. The main regularities of two-phase flows both in critical and in other regimes are established using the notion of entropy. This parameter serves as a basis for a deeper insight into the physics of the process and for the development of exhaustive techniques of mass exchange estimation in such flows. The book is intended for graduate and postgraduate students of engineering studying two-phase flows, and to scientists and engineers engaged in specific problems of such fields as chemical technology, mineral dressing, modern ceramics, microelectronics, pharmacology, po...

  7. New results in gravity dependent two-phase flow regime mapping

    Science.gov (United States)

    Kurwitz, Cable; Best, Frederick

    2002-01-01

    Accurate prediction of thermal-hydraulic parameters, such as the spatial gas/liquid orientation or flow regime, is required for implementation of two-phase systems. Although many flow regime transition models exist, accurate determination of both annular and slug regime boundaries is not well defined especially at lower flow rates. Furthermore, models typically indicate the regime as a sharp transition where data may indicate a transition space. Texas A&M has flown in excess of 35 flights aboard the NASA KC-135 aircraft with a unique two-phase package. These flights have produced a significant database of gravity dependent two-phase data including visual observations for flow regime identification. Two-phase flow tests conducted during recent zero-g flights have added to the flow regime database and are shown in this paper with comparisons to selected transition models. .

  8. Concurrent two-phase downflow measurement with an induced voltage electro-magnetic flowmeter

    OpenAIRE

    Opara, Uroš; Bajsič, Ivan

    2015-01-01

    With a set of polynomial approximations a possibility is shown of the use of an induced voltage electromagnetic flowmeter in the area of measuring cocurrent two-phase downflow in tubes. The principle of the meter operation remains hereby unchanged

  9. Numerical simulation of multi-dimensional two-phase flow based on flux vector splitting

    Energy Technology Data Exchange (ETDEWEB)

    Staedtke, H.; Franchello, G.; Worth, B. [Joint Research Centre - Ispra Establishment (Italy)

    1995-09-01

    This paper describes a new approach to the numerical simulation of transient, multidimensional two-phase flow. The development is based on a fully hyperbolic two-fluid model of two-phase flow using separated conservation equations for the two phases. Features of the new model include the existence of real eigenvalues, and a complete set of independent eigenvectors which can be expressed algebraically in terms of the major dependent flow parameters. This facilitates the application of numerical techniques specifically developed for high speed single-phase gas flows which combine signal propagation along characteristic lines with the conservation property with respect to mass, momentum and energy. Advantages of the new model for the numerical simulation of one- and two- dimensional two-phase flow are discussed.

  10. Detection of Two-Phase Flow Patterns in a Vertical Minichannel Using the Recurrence Quantification Analysis

    Directory of Open Access Journals (Sweden)

    Mosdorf Romuald

    2015-06-01

    Full Text Available The two-phase flow (water-air occurring in square minichannel (3x3 mm has been analysed. In the minichannel it has been observed: bubbly flow, flow of confined bubbles, flow of elongated bubbles, slug flow and semi-annular flow. The time series recorded by laser-phototransistor sensor was analysed using the recurrence quantification analysis. The two coefficients:Recurrence rate (RR and Determinism (DET have been used for identification of differences between the dynamics of two-phase flow patterns. The algorithm which has been used normalizes the analysed time series before calculating the recurrence plots.Therefore in analysis the quantitative signal characteristicswas neglected. Despite of the neglect of quantitative signal characteristics the analysis of its dynamics (chart of DET vs. RR allows to identify the two-phase flow patterns. This confirms that this type of analysis can be used to identify the two-phase flow patterns in minichannels.

  11. Reversible, on-demand generation of aqueous two-phase microdroplets

    Energy Technology Data Exchange (ETDEWEB)

    Collier, Charles Patrick; Retterer, Scott Thomas; Boreyko, Jonathan Barton; Mruetusatorn, Prachya

    2017-08-15

    The present invention provides methods of on-demand, reversible generation of aqueous two-phase microdroplets core-shell microbeads, microparticle preparations comprising the core-shell microbeads, and drug delivery formulation comprising the microparticle preparations. Because these aqueous microdroplets have volumes comparable to those of cells, they provide an approach to mimicking the dynamic microcompartmentation of biomaterial that naturally occurs within the cytoplasm of cells. Hence, the present methods generate femtoliter aqueous two-phase droplets within a microfluidic oil channel using gated pressure pulses to generate individual, stationary two-phase microdroplets with a well-defined time zero for carrying out controlled and sequential phase transformations over time. Reversible phase transitions between single-phase, two-phase, and core-shell microbead states are obtained via evaporation-induced dehydration and water rehydration.

  12. Research of Characteristics of Gas-liquid Two-phase Pressure Drop in Microreactor

    Directory of Open Access Journals (Sweden)

    Li Dan

    2015-01-01

    Full Text Available With the research system of nitrogen and deionized water, this paper researches the pressure drop of gas-liquid two-phase flow in the circular microchannel with an inner diameter which is respectively 0.9mm and 0.5mm, analyzes the effect of microchannel diameter on gas-liquid two-phase frictional pressure drop in the microchannel reactor, and compares with the result of frictional pressure drop and the predicting result of divided-phase flow pattern. The result shows that, the gas-liquid two-phase frictional pressure drop in the microchannel significantly increases with the decreasing microchannel diameter; Lockhart-Martinelli relationship in divided-phase flow pattern can preferably predict the gas-liquid two-phase frictional pressure drop in the microchannel, but the Tabular constant needs to be corrected.

  13. Two-phase mixed media dielectric with macro dielectric beads for enhancing resistivity and breakdown strength

    Science.gov (United States)

    Falabella, Steven; Meyer, Glenn A; Tang, Vincent; Guethlein, Gary

    2014-06-10

    A two-phase mixed media insulator having a dielectric fluid filling the interstices between macro-sized dielectric beads packed into a confined volume, so that the packed dielectric beads inhibit electro-hydrodynamically driven current flows of the dielectric liquid and thereby increase the resistivity and breakdown strength of the two-phase insulator over the dielectric liquid alone. In addition, an electrical apparatus incorporates the two-phase mixed media insulator to insulate between electrical components of different electrical potentials. And a method of electrically insulating between electrical components of different electrical potentials fills a confined volume between the electrical components with the two-phase dielectric composite, so that the macro dielectric beads are packed in the confined volume and interstices formed between the macro dielectric beads are filled with the dielectric liquid.

  14. Formation of a two-phase microstructure in Fe-Cr-Ni alloy during directional solidification

    Science.gov (United States)

    Fu, J. W.; Yang, Y. S.; Guo, J. J.; Ma, J. C.; Tong, W. H.

    2008-12-01

    The formation and evolution of a two-phase coupled growth microstructure in AISI 304 stainless steel are investigated using a quenching method during directional solidification. It is found that the two-phase microstructure, which is composed of coupled growth of thin lathy delta ferrite (δ) and austenite (γ), forms from the melt first during solidification. As solidification proceeds, the retained liquid transforms into austenite directly. On cooling, the subsequent incomplete solid-state transformation from ferrite to austenite results in the disappearance of the thinner lathy delta ferrite, and the final two-phase coupled growth microstructure is formed. The formation mechanism of the two-phase coupled growth microstructure is analyzed theoretically based on the nucleation and constitutional undercooling (NCU) criterion. Transmission electron microscope (TEM) and EDS analyses were carried out to identify the phases and determine the phase composition, respectively.

  15. Experimental study on transient behavior of semi-open two-phase thermosyphon

    Institute of Scientific and Technical Information of China (English)

    朱华; 王建新; 张巧惠; 屠传经

    2004-01-01

    An experimental system was set up to measure the temperature, pressure, heat transfer rate and mass flow rate in a semi-open two-phase thermosyphon. The behaviors of a semi-open two-phase thermosyphon during startup, shutdown and lack of water were studied to get complete understanding of its thermal characteristics. The variation of wall temperature, heat-exchange condition and pressure fluctuations of semi-open two-phase thermosyphons showed that the startup of SOTPT needs about 60-70 min; the startup speed of SOTPT is determined by the startup speed of the condensation section; the average pressure in the heat pipe is equal to the environmental pressure usually; the shutdown of SOTPT needs about 30-50min; a semi-open two-phase thermosyphon has good response to lack of water accident.

  16. A Rotational Pressure-Correction Scheme for Incompressible Two-Phase Flows with Open Boundaries.

    Science.gov (United States)

    Dong, S; Wang, X

    2016-01-01

    Two-phase outflows refer to situations where the interface formed between two immiscible incompressible fluids passes through open portions of the domain boundary. We present several new forms of open boundary conditions for two-phase outflow simulations within the phase field framework, as well as a rotational pressure correction based algorithm for numerically treating these open boundary conditions. Our algorithm gives rise to linear algebraic systems for the velocity and the pressure that involve only constant and time-independent coefficient matrices after discretization, despite the variable density and variable viscosity of the two-phase mixture. By comparing simulation results with theory and the experimental data, we show that the method produces physically accurate results. We also present numerical experiments to demonstrate the long-term stability of the method in situations where large density contrast, large viscosity contrast, and backflows occur at the two-phase open boundaries.

  17. Single and two-phase flow pressure drop for CANFLEX bundle

    Energy Technology Data Exchange (ETDEWEB)

    Park, Joo Hwan; Jun, Ji Su; Suk, Ho Chun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Dimmick, G. R.; Bullock, D. E. [Atomic Energy of Canada Limited, Ontario (Canada)

    1998-12-31

    Friction factor and two-phase flow frictional multiplier for a CANFLEX bundle are newly developed and presented in this paper. CANFLEX as a 43-element fuel bundle has been developed jointly by AECL/KAERI to provide greater operational flexibility for CANDU reactor operators and designers. Friction factor and two-phase flow frictional multiplier have been developed by using the experimental data of pressure drops obtained from two series of Freon-134a (R-134a) CHF tests with a string of simulated CANFLEX bundles in a single phase and a two-phase flow conditions. The friction factor for a CANFLEX bundle is found to be about 20% higher than that of Blasius for a smooth circular pipe. The pressure drop predicted by using the new correlations of friction factor and two-phase frictional multiplier are well agreed with the experimental pressure drop data of CANFLEX bundle within {+-} 5% error. 11 refs., 5 figs. (Author)

  18. Bioconversion of apigenin-7-O-β-glucoside in aqueous two-phase system

    OpenAIRE

    Ilić Sanja M.; Đaković Sanja D.; Cvejić Jelena H.; Antov Mirjana G.; Zeković Zoran P.

    2005-01-01

    The study is concerned with the conversion of apigenin-7-O-β-glucoside into apigenin in polyethylene glycol 6000 / dextran 20000 aqueous two-phase system by β-glucosidase. Apigenin was separated from apigenin-7-O-β-glucoside and β-glucosidase by their partition into opposite phases. In 14% PEG / 22.5% DEX aqueous two-phase system obtained yield of apigenin in top phase was 108%.

  19. Bioconversion of apigenin-7-O-β-glucoside in aqueous two-phase system

    Directory of Open Access Journals (Sweden)

    Ilić Sanja M.

    2005-01-01

    Full Text Available The study is concerned with the conversion of apigenin-7-O-β-glucoside into apigenin in polyethylene glycol 6000 / dextran 20000 aqueous two-phase system by β-glucosidase. Apigenin was separated from apigenin-7-O-β-glucoside and β-glucosidase by their partition into opposite phases. In 14% PEG / 22.5% DEX aqueous two-phase system obtained yield of apigenin in top phase was 108%.

  20. CURE OF A MICROGEL-EPOXY RESIN TWO-PHASE POLYMER WITH ETHYLENE DIAMINE

    Institute of Scientific and Technical Information of China (English)

    SONG Aiteng; HUANG Wei; YU Yunzhao

    1992-01-01

    The curing of a microgel-epoxy resin two phase polymer prepared by in situ copolymerization of unsaturated polyester with acrylic monomer was studied. The unsaturated unit reacted with N- H during the cure of the resin with ethylene diamine. The Michael type reaction was ten times more rapid than the addition of N -H to epoxide .This was accounted for the lower apparent activation energy of the curing of the two phase resin.

  1. Estimation of the sugar cane cultivated area from LANDSAT images using the two phase sampling method

    Science.gov (United States)

    Parada, N. D. J. (Principal Investigator); Cappelletti, C. A.; Mendonca, F. J.; Lee, D. C. L.; Shimabukuro, Y. E.

    1982-01-01

    A two phase sampling method and the optimal sampling segment dimensions for the estimation of sugar cane cultivated area were developed. This technique employs visual interpretations of LANDSAT images and panchromatic aerial photographs considered as the ground truth. The estimates, as a mean value of 100 simulated samples, represent 99.3% of the true value with a CV of approximately 1%; the relative efficiency of the two phase design was 157% when compared with a one phase aerial photographs sample.

  2. Numerical investigation of confined swirling gas-solid two phase jet

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper presents a k-ε-kp multi-fluid model for simulating confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. A series of numerical simulations of the two-phase flow of 30 μm, 45 μm, 60 μm diameter particles respectively yielded results fitting well with published experimental data.

  3. Numerical Simulation of Swirling Gas-solid Two Phase Flow through a Pipe Expansion

    Institute of Scientific and Technical Information of China (English)

    Jin Hanhui; Xia Jun; Fan Jianren; Cen Kefa

    2001-01-01

    A k- ε -kp multi-fluid model is stated and adopted to simulate swirling gas-solid two phase flow. A particle-laden flow from a center tube and a swirling air stream from the coaxial annular enter the test section. A series of numerical simulations of the two-phase flow are performed based on 30 μ m, 45 μ m, 60 μ m diameter particles respectively. The results fit well with published experimental data.

  4. Numerical investigation of confined swirling gas-solid two phase jet

    Institute of Scientific and Technical Information of China (English)

    金晗辉; 夏钧; 樊建人; 岑可法

    2002-01-01

    This paper presents a k-e-kp multi-fluid model for simulating confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. A series of numerical simulations of the two-phase flow of 30μm, 45μm, 60μm diameter particles respectively yielded results fitting well with published experimental data.

  5. CHOOSING STRUCTURE-DEPENDENT DRAG COEFFICIENT IN MODELING GAS-SOLID TWO-PHASE FLOW

    Institute of Scientific and Technical Information of China (English)

    Ning Yang; Wei Wang; Wei Ge; Jinghai Li

    2003-01-01

    @@ Introduction Gas-solid two-phase flow is often encountered in chemical reactors for the process industry. For industrial users, design, scale-up, control and optimization for these reactors require a good understanding of the hydrodynamics of gas-solid two-phase flow. For researchers, exploration and prediction of the complex phenomena call for a good comprehension of the heterogeneous structure and of the dominant mechanisms of gas-solid and solid-solid interactions.

  6. Scaling analysis of gas-liquid two-phase flow pattern in microgravity

    Science.gov (United States)

    Lee, Jinho

    1993-01-01

    A scaling analysis of gas-liquid two-phase flow pattern in microgravity, based on the dominant physical mechanism, was carried out with the goal of predicting the gas-liquid two-phase flow regime in a pipe under conditions of microgravity. The results demonstrated the effect of inlet geometry on the flow regime transition. A comparison of the predictions with existing experimental data showed good agreement.

  7. Growing an Emerging Research University

    Science.gov (United States)

    Birx, Donald L.; Anderson-Fletcher, Elizabeth; Whitney, Elizabeth

    2013-01-01

    The emerging research college or university is one of the most formidable resources a region has to reinvent and grow its economy. This paper is the first of two that outlines a process of building research universities that enhance regional technology development and facilitate flexible networks of collaboration and resource sharing. Although the…

  8. Compute raided classification of ventilation patterns inpatients with chronic obstructive pulmonary diseases at two-phase xenon-enhanced CT

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Son Ho; Goo, Jin Mo; Lee, Chang Hyun; Lee, You Kyung; Jin, Kwang Nam; Choo, Ji Yung; Lee, Nyoung Keun [Seoul National University College of Medicine, Seoul (Korea, Republic of); Jung, Julip; Hong, Helen [Dept. of Multimedia Engineering, Seoul Women' s University, Seoul (Korea, Republic of)

    2014-06-15

    To evaluate the technical feasibility, performance, and interobserver agreement of a computer-aided classification (CAC) system for regional ventilation at two-phase xenon-enhanced CT in patients with chronic obstructive pulmonary disease (COPD). Thirty-eight patients with COPD underwent two-phase xenon ventilation CT with resulting wash-in (WI) and wash-out (WO) xenon images. The regional ventilation in structural abnormalities was visually categorized into four patterns by consensus of two experienced radiologists who compared the xenon attenuation of structural abnormalities with that of adjacent normal parenchyma in the WI and WO images, and it served as the reference. Two series of image datasets of structural abnormalities were randomly extracted for optimization and validation. The proportion of agreement on a per-lesion basis and receiver operating characteristics on a per-pixel basis between CAC and reference were analyzed for optimization. Thereafter, six readers independently categorized the regional ventilation in structural abnormalities in the validation set without and with a CAC map. Interobserver agreement was also compared between assessments without and with CAC maps using multirater κ statistics. Computer-aided classification maps were successfully generated in 31 patients (81.5%). The proportion of agreement and the average area under the curve of optimized CAC maps were 94% (75/80) and 0.994, respectively. Multirater k value was improved from moderate (k=0.59: 95% confidence interval [CI], 0.56-0.62) at the initial assessment to excellent with the CAC map.

  9. Multi-rate mass transfer modeling of two-phase flow in highly heterogeneous fractured and porous media

    Science.gov (United States)

    Tecklenburg, Jan; Neuweiler, Insa; Carrera, Jesus; Dentz, Marco

    2016-05-01

    We study modeling of two-phase flow in highly heterogeneous fractured and porous media. The flow behaviour is strongly influenced by mass transfer between a highly permeable (mobile) fracture domain and less permeable (immobile) matrix blocks. We quantify the effective two-phase flow behavior using a multirate rate mass transfer (MRMT) approach. We discuss the range of applicability of the MRMT approach in terms of the pertinent viscous and capillary diffusion time scales. We scrutinize the linearization of capillary diffusion in the immobile regions, which allows for the formulation of MRMT in the form of a non-local single equation model. The global memory function, which encodes mass transfer between the mobile and the immobile regions, is at the center of this method. We propose two methods to estimate the global memory function for a fracture network with given fracture and matrix geometry. Both employ a scaling approach based on the known local memory function for a given immobile region. With the first method, the local memory function is calculated numerically, while the second one employs a parametric memory function in form of truncated power-law. The developed concepts are applied and tested for fracture networks of different complexity. We find that both physically based parameter estimation methods for the global memory function provide predictive MRMT approaches for the description of multiphase flow in highly heterogeneous porous media.

  10. Multi-rate mass transfer modeling of two-phase flow in highly heterogeneous fractured and porous media

    CERN Document Server

    Tecklenburg, Jan; Carrera, Jesus; Dentz, Marco

    2016-01-01

    We study modeling of two-phase flow in highly heterogeneous fractured and porous media. The flow behaviour is strongly influenced by mass transfer between a highly permeable (mobile) fracture domain and less permeable (immobile) matrix blocks. We quantify the effective two-phase flow behaviour using a multirate rate mass transfer (MRMT) approach. We discuss the range of applicability of the MRMT approach in terms of the pertinent viscous and capillary diffusion time scales. We scrutinize the linearization of capillary diffusion in the immobile regions, which allows for the formulation of MRMT in the form of a non-local single equation model. The global memory function, which encodes mass transfer between the mobile and the immobile regions, is at the center of this method. We propose two methods to estimate the global memory function for a fracture network with given fracture and matrix geometry. Both employ a scaling approach based on the known local memory function for a given immobile region. With the firs...

  11. Measurement of local two-phase flow parameters of nanofluids using conductivity double-sensor probe

    Directory of Open Access Journals (Sweden)

    Park Yu sun

    2011-01-01

    Full Text Available Abstract A two-phase flow experiment using air and water-based γ-Al2O3 nanofluid was conducted to observe the basic hydraulic phenomenon of nanofluids. The local two-phase flow parameters were measured with a conductivity double-sensor two-phase void meter. The void fraction, interfacial velocity, interfacial area concentration, and mean bubble diameter were evaluated, and all of those results using the nanofluid were compared with the corresponding results for pure water. The void fraction distribution was flattened in the nanofluid case more than it was in the pure water case. The higher interfacial area concentration resulted in a smaller mean bubble diameter in the case of the nanofluid. This was the first attempt to measure the local two-phase flow parameters of nanofluids using a conductivity double-sensor two-phase void meter. Throughout this experimental study, the differences in the internal two-phase flow structure of the nanofluid were identified. In addition, the heat transfer enhancement of the nanofluid can be resulted from the increase of the interfacial area concentration which means the available area of the heat and mass transfer.

  12. Ionic liquids for two-phase systems and their application for purification, extraction and biocatalysis.

    Science.gov (United States)

    Oppermann, Sebastian; Stein, Florian; Kragl, Udo

    2011-02-01

    The development of biotechnological processes using novel two-phase systems based on molten salts known as ionic liquids (ILs) got into the focus of interest. Many new approaches for the beneficial application of the interesting solvent have been published over the last years. ILs bring beneficial properties compared to organic solvents like nonflammability and nonvolatility. There are two possible ways to use the ILs: first, the hydrophobic ones as a substitute for organic solvents in pure two-phase systems with water and second, the hydrophilic ones in aqueous two-phase systems (ATPS). To effectively utilise IL-based two-phase systems or IL-based ATPS in biotechnology, extensive experimental work is required to gain the optimal system parameters to ensure selective extraction of the product of interest. This review will focus on the most actual findings dealing with the basic driving forces for the target extraction in IL-based ATPS as well as presenting some selected examples for the beneficial application of ILs as a substitute for organic solvents. Besides the research focusing on IL-based two-phase systems, the "green aspect" of ILs, due to their negligible vapour pressure, is widely discussed. We will present the newest results concerning ecotoxicity of ILs to get an overview of the state of the art concerning ILs and their utilisation in novel two-phase systems in biotechnology.

  13. Living between two worlds: two-phase culture systems for producing plant secondary metabolites.

    Science.gov (United States)

    Malik, Sonia; Hossein Mirjalili, Mohammad; Fett-Neto, Arthur Germano; Mazzafera, Paulo; Bonfill, Mercedes

    2013-03-01

    The two-phase culture system is an important in vitro strategy to increase the production of secondary metabolites (SMs) by providing an enhanced release of these compounds from plant cells. Whereas the first phase supports cell growth, the second phase provides an additional site or acts as a metabolic sink for the accumulation of SMs and also reduces feedback inhibition. This review is focused on several aspects of the two-phase culture system and aims to show the diverse possibilities of employing this technique for the in vitro production of SMs from plant cells. Depending on the material used in the secondary phase, two-phase culture systems can be broadly categorised as liquid-liquid or liquid-solid. The choice of material for the second phase depends on the type of compound to be recovered and the compatibility with the other phase. Different factors affecting the efficiency of two-phase culture systems include the choice of material for the secondary phase, its concentration, volume, and time of addition. Factors such as cell elicitation, immobilization, and permeabilization, have been suggested as important strategies to make the two-phase culture system practically reliable on a commercial scale. Since there are many possibilities for designing a two-phase system, more detailed studies are needed to broaden the range of secondary phases compatible with the various plant species producing SMs with potential applications, mainly in the food and pharmacology industries.

  14. IMPROVED SUBGRID SCALE MODEL FOR DENSE TURBULENT SOLID-LIQUID TWO-PHASE FLOWS

    Institute of Scientific and Technical Information of China (English)

    TANG Xuelin; QIAN Zhongdong; WU Yulin

    2004-01-01

    The dense solid-phase governing equations for two-phase flows are obtained by using the kinetic theory of gas molecules. Assuming that the solid-phase velocity distributions obey the Maxwell equations, the collision term for particles under dense two-phase flow conditions is also derived.In comparison with the governing equations of a dilute two-phase flow, the solid-particle's governing equations are developed for a dense turbulent solid-liquid flow by adopting some relevant terms from the dilute two-phase governing equations. Based on Cauchy-Helmholtz theorem and Smagorinsky model,a second-order dynamic sub-grid-scale (SGS) model, in which the sub-grid-scale stress is a function of both the strain-rate tensor and the rotation-rate tensor, is proposed to model the two-phase governing equations by applying dimension analyses. Applying the SIMPLEC algorithm and staggering grid system to the two-phase discretized governing equations and employing the slip boundary conditions on the walls, the velocity and pressure fields, and the volumetric concentration are calculated. The simulation results are in a fairly good agreement with experimental data in two operating cases in a conduit with a rectangular cross-section and these comparisons imply that these models are practical.

  15. Mixed Model for Silt-Laden Solid-Liquid Two-Phase Flows

    Institute of Scientific and Technical Information of China (English)

    唐学林; 徐宇; 吴玉林

    2003-01-01

    The kinetic theory of molecular gases was used to derive the governing equations for dense solid-liquid two-phase flows from a microscopic flow characteristics viewpoint by multiplying the Boltzmann equation for each phase by property parameters and integrating over the velocity space. The particle collision term was derived from microscopic terms by comparison with dilute two-phase flow but with consideration of the collisions between particles for dense two-phase flow conditions and by assuming that the particle-phase velocity distribution obeys the Maxwell equations. Appropriate terms from the dilute two-phase governing equations were combined with the dense particle collision term to develop the governing equations for dense solid-liquid turbulent flows. The SIMPLEC algorithm and a staggered grid system were used to solve the discretized two-phase governing equations with a Reynolds averaged turbulence model. Dense solid-liquid turbulent two-phase flows were simulated for flow in a duct. The simulation results agree well with experimental data.

  16. 16S-23S Internal Transcribed Spacer Region PCR and Sequencer-Based Capillary Gel Electrophoresis has Potential as an Alternative to High Performance Liquid Chromatography for Identification of Slowly Growing Nontuberculous Mycobacteria

    OpenAIRE

    Subedi, Shradha; Kong, Fanrong; Jelfs, Peter; Gray, Timothy J; Xiao, Meng; Sintchenko, Vitali; Chen, Sharon C-A.

    2016-01-01

    Accurate identification of slowly growing nontuberculous mycobacteria (SG-NTM) of clinical significance remains problematic. This study evaluated a novel method of SG-NTM identification by amplification of the mycobacterial 16S-23S rRNA internal transcribed spacer (ITS) region followed by resolution of amplified fragments by sequencer-based capillary gel electrophoresis (SCGE). Fourteen American Type Culture Collection (ATCC) strains and 103 clinical/environmental isolates (total n = 24 speci...

  17. Design, Modelling and Simulation of Two-Phase Two-Stage Electronic System with Orthogonal Output for Supplying of Two-Phase ASM

    Directory of Open Access Journals (Sweden)

    Michal Prazenica

    2011-01-01

    Full Text Available This paper deals with the two-stage two-phase electronic systems with orthogonal output voltages and currents - DC/AC/AC. Design of two-stage DC/AC/AC high frequency converter with two-phase orthogonal output using single-phase matrix converter is also introduced. Output voltages of them are strongly nonharmonic ones, so they must be pulse-modulated due to requested nearly sinusoidal currents with low total harmonic distortion. Simulation experiment results of matrix converter for both steady and transient states for IM motors are given in the paper, also experimental verification under R-L load, so far. The simulation results confirm a very good time-waveform of the phase current and the system seems to be suitable for low-cost application in automotive/aerospace industries and application with high frequency voltage sources.

  18. Mass transport of carbon in one and two phase iron-nickel alloys in a temperature gradient

    Energy Technology Data Exchange (ETDEWEB)

    Okafor, I.C.I.; Carlson, O.N.; Martin, D.M.

    1983-10-01

    The flux of carbon atoms induced by an applied temperature gradient on a specimen was investigated for an Fe-32.5 wt pct Ni alloy for six carbon concentrations. Carbon was found to migrate to the higher temperature region in the low carbon single phase alloys. However, in the higher carbon alloys an abrupt jump in carbon concentrations results when a portion of the specimen is in a two-phase region while the portion in the one-phase region exhibits the usual solute migration toward the higher temperature. A value of -12.2 + or - 0.4 kJ mol/sup -1/ was obtained for the heat of transport of carbon in the ..gamma..-phase Fe-Ni alloys for a wide range of carbon concentrations. A model for diffusion and thermotransport in multiphase systems is presented to explain the observed results.

  19. DYNAMIC MODELING STRATEGY FOR FLOW REGIME TRANSITION IN GAS-LIQUID TWO-PHASE FLOWS

    Energy Technology Data Exchange (ETDEWEB)

    X. Wang; X. Sun; H. Zhao

    2011-09-01

    In modeling gas-liquid two-phase flows, the concept of flow regime has been used to characterize the global interfacial structure of the flows. Nearly all constitutive relations that provide closures to the interfacial transfers in two-phase flow models, such as the two-fluid model, are often flow regime dependent. Currently, the determination of the flow regimes is primarily based on flow regime maps or transition criteria, which are developed for steady-state, fully-developed flows and widely applied in nuclear reactor system safety analysis codes, such as RELAP5. As two-phase flows are observed to be dynamic in nature (fully-developed two-phase flows generally do not exist in real applications), it is of importance to model the flow regime transition dynamically for more accurate predictions of two-phase flows. The present work aims to develop a dynamic modeling strategy for determining flow regimes in gas-liquid two-phase flows through the introduction of interfacial area transport equations (IATEs) within the framework of a two-fluid model. The IATE is a transport equation that models the interfacial area concentration by considering the creation and destruction of the interfacial area, such as the fluid particle (bubble or liquid droplet) disintegration, boiling and evaporation; and fluid particle coalescence and condensation, respectively. For the flow regimes beyond bubbly flows, a two-group IATE has been proposed, in which bubbles are divided into two groups based on their size and shape (which are correlated), namely small bubbles and large bubbles. A preliminary approach to dynamically identifying the flow regimes is provided, in which discriminators are based on the predicted information, such as the void fraction and interfacial area concentration of small bubble and large bubble groups. This method is expected to be applied to computer codes to improve their predictive capabilities of gas-liquid two-phase flows, in particular for the applications in

  20. Fundamental Studies on Two-Phase Gas-Liquid Flows Through Packed Beds in Microgravity

    Science.gov (United States)

    Balakotaiah, Vemuri; McCready, Mark J.; Motil, Brian J.

    2002-01-01

    In the typical operation of a packed-bed reactor, gas and liquid flow simultaneously through a fixed bed of solid particles. Depending on the application, the particles can be of various shapes and sizes and provide for intimate contact and high rates of transport between the phases needed to sustain chemical or biological reactions. The packing may also serve as either a catalyst or as a support for growing biological material. NASA has flown two of these packed-bed systems in a microgravity environment with limited or no success. The goal of this research is to develop models (with scale-up capability) needed for the design of the physicochemical equipment to carry out these unit operations in microgravity. New insight will also lead to improvements in normal gravity operations. Our initial experiment was flown using an existing KC-135 two-phase flow rig with a modified test section. The test section is a clear polycarbonate rectangular column with a depth of 2.54 cm, a width of 5.08 cm, and 60 cm long. The column was randomly packed with spherical glass beads by slowly dropping the beads into the bed. Even though care was taken in handling the column after it was filled with packing, the alternating high and low gravity cycles with each parabola created a slightly tighter packed bed than is typically reported for this type. By the usual method of comparing the weight difference of a completely dry column versus a column filled with water, the void fraction was found to be .345 for both sizes of beads used. Five flush mounted differential pressure transducers are spaced at even intervals with the first location 4 cm from the inlet port and the subsequent pressure transducers spaced at 13 cm intervals along the column. Differential pressure data was acquired at 1000 Hz to adequately observe pulse formation and characteristics. Visual images of the flow were recorded using a high-speed SVHS system at 500 frames per second. Over 250 different test conditions were

  1. The Deep Crust Magmatic Refinery, Part 1: A Coupled Thermodynamic and Two-phase Flow Model

    Science.gov (United States)

    Riel, N., Jr.; Bouilhol, P.; Van Hunen, J.; Velic, M.; Magni, V.

    2016-12-01

    Metamorphic and magmatic processes occurring in the deep crust ultimately control the chemical and physical characteristic of the continental crust. A complex interplay between magma intrusion, crystallization, and reaction with the pre-existing crust provide a wide range of differentiated magma and cumulates (and / or restites) that will feed the upper crustal levels with evolved melt while constructing the lower crust. With growing evidence from field and experimental studies, it becomes clearer that crystallization and melting processes are non-exclusive but should be considered together. Incoming H2O bearing mantle melts will start to fractionate to a certain extent, forming cumulates but also releasing heat and H2O to the intruded host-rock allowing it to melt in saturated conditions. The end-result of such dynamic system is a function of the amount and composition of melt input, and extent of reaction with the host which is itself dependent on the migration mode of the melts. To assess the dynamics of this deep magmatic system we developed a new 2-D two-phase flow code using finite volume method. Our formulation takes into account: (i) melt flow through a viscous porous matrix with temperature- and melt-content dependent host-rock viscosity, (ii) heat transfer, assuming local thermal equilibrium between solid and liquid, (iii) thermodynamic modelling of stable phases, (iv) injection of fractionated melt from crystallizing basalt at the Moho and (v) chemical advection of both the solid and liquid compositions. Here we present the core of our modelling approach, especially the petrological implementation. We show in details that our thermodynamic model can reproduce well both the sub- and supra solidus phase relationship and composition of the host-rock. We apply our method to an idealized amphibolite lower crust that is affected by a magmatic event represented by the intrusion of a wet mantle melt into the crust at Moho depth. The models [see Bouilhol et al

  2. FOSSIL EVIDENCE FOR THE TWO-PHASE FORMATION OF ELLIPTICAL GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Huang Song [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Ho, Luis C. [The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Peng, Chien Y. [Giant Magellan Telescope Organization, 251 South Lake Avenue, Suite 300, Pasadena, CA 91101 (United States); Li Zhaoyu [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Barth, Aaron J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697-4575 (United States)

    2013-05-10

    Massive early-type galaxies (ETGs) have undergone dramatic structural evolution over the last 10 Gyr. A companion paper shows that nearby elliptical galaxies with M{sub *} {>=} 1.3 Multiplication-Sign 10{sup 11} M{sub Sun} generically contain three photometric subcomponents: a compact inner component with effective radius R{sub e} {approx}< 1 kpc, an intermediate-scale middle component with R{sub e} Almost-Equal-To 2.5 kpc, and an extended outer envelope with R{sub e} Almost-Equal-To 10 kpc. Here we attempt to relate these substructures with the properties of ETGs observed at higher redshifts. We find that a hypothetical structure formed from combining the inner and middle components of local ellipticals follows a strikingly tight stellar mass-size relation, one that resembles the distribution of ETGs at z Almost-Equal-To 1. Outside of the central kpc, the median stellar mass surface density profiles of this composite structure agree closest with those of massive galaxies that have similar cumulative number density at 1.5 < z < 2.0 within the uncertainty. We propose that the central substructures in nearby ellipticals are the evolutionary descendants of the ''red nuggets'' formed under highly dissipative (''wet'') conditions at high redshifts, as envisioned in the initial stages of the two-phase formation scenario recently advocated for massive galaxies. Subsequent accretion, plausibly through dissipationless (''dry'') minor mergers, builds the outer regions of the galaxy identified as the outer envelope in our decomposition. The large scatter exhibited by this component on the stellar mass-size plane testifies to the stochastic nature of the accretion events.

  3. A two-phase restricted equilibrium model for combustion of metalized solid propellants

    Science.gov (United States)

    Sabnis, J. S.; Dejong, F. J.; Gibeling, H. J.

    1992-01-01

    An Eulerian-Lagrangian two-phase approach was adopted to model the multi-phase reacting internal flow in a solid rocket with a metalized propellant. An Eulerian description was used to analyze the motion of the continuous phase which includes the gas as well as the small (micron-sized) particulates, while a Lagrangian description is used for the analysis of the discrete phase which consists of the larger particulates in the motor chamber. The particulates consist of Al and Al2O3 such that the particulate composition is 100 percent Al at injection from the propellant surface with Al2O3 fraction increasing due to combustion along the particle trajectory. An empirical model is used to compute the combustion rate for agglomerates while the continuous phase chemistry is treated using chemical equilibrium. The computer code was used to simulate the reacting flow in a solid rocket motor with an AP/HTPB/Al propellant. The computed results show the existence of an extended combustion zone in the chamber rather than a thin reaction region. The presence of the extended combustion zone results in the chamber flow field and chemical being far from isothermal (as would be predicted by a surface combustion assumption). The temperature in the chamber increases from about 2600 K at the propellant surface to about 3350 K in the core. Similarly the chemical composition and the density of the propellant gas also show spatially non-uniform distribution in the chamber. The analysis developed under the present effort provides a more sophisticated tool for solid rocket internal flow predictions than is presently available, and can be useful in studying apparent anomalies and improving the simple correlations currently in use. The code can be used in the analysis of combustion efficiency, thermal load in the internal insulation, plume radiation, etc.

  4. Modeling of Immiscible, Two-Phase Flows in a Natural Rock Fracture

    Energy Technology Data Exchange (ETDEWEB)

    Crandall, Dustin; Ahmadi, Goodarz; Smith, Duane H

    2009-01-01

    One potential method of geologically sequestering carbon dioxide (CO2) is to inject the gas into brine-filled, subsurface formations. Within these low-permeability rocks, fractures exist that can act as natural fluid conduits. Understanding how a less viscous fluid moves when injected into an initially saturated rock fracture is important for the prediction of CO2 transport within fractured rocks. Our study examined experimentally and numerically the motion of immiscible fluids as they were transported through models of a fracture in Berea sandstone. The natural fracture geometry was initially scanned using micro-computerized tomography (CT) at a fine volume-pixel (voxel) resolution by Karpyn et al. [1]. This CT scanned fracture was converted into a numerical mesh for two-phase flow calculations using the finite-volume solver FLUENT® and the volume-of-fluid method. Additionally, a translucent experimental model was constructed using stereolithography. The numerical model was shown to agree well with experiments for the case of a constant rate injection of air into the initially water-saturated fracture. The invading air moved intermittently, quickly invading large-aperture regions of the fracture. Relative permeability curves were developed to describe the fluid motion. These permeability curves can be used in reservoir-scale discrete fracture models for predictions of fluid motion within fractured geological formations. The numerical model was then changed to better mimic the subsurface conditions at which CO2 will move into brine saturated fractures. The different fluid properties of the modeled subsurface fluids were shown to increase the amount of volume the less-viscous invading gas would occupy while traversing the fracture.

  5. Two-phase simulations of the full load surge in Francis turbines

    Science.gov (United States)

    Wack, J.; Riedelbauch, S.

    2016-11-01

    At off-design conditions, Francis turbines experience cavitation which may reduce the power output and can cause severe damage in the machine. Certain conditions can cause self-excited oscillations of the vortex rope in the draft tube at full load operating point. For the presented work, two-phase simulations are carried out at model scale on a domain ranging from the inlet of the spiral case to the outlet of the draft tube. At different locations, wall pressure measurements are available and compared to the simulation results. Furthermore, the dynamics of the cavity volume in the draft tube cone and at the trailing edge of the runner blades are investigated by comparing with high speed visualization. To account for the selfexcited behaviour, proper boundary conditions need to be set. In this work, the focus lies on the treatment of the boundary condition at the inlet. In the first step, the dynamic behaviour of the cavity regions is investigated using a constant mass flow. Thereafter, oscillations of the total pressure and mass flow rate are prescribed using various frequencies and amplitudes. This methodology enables to examine the response of the cavity dynamics due to different excitations. It can be observed that setting a constant mass flow boundary condition is not suitable to account for the self-excited behaviour. Prescribing the total pressure has the result that the frequency of the vapour volume oscillation is the same as the frequency of the excitation signal. Contrary to that, for an excitation with a mass flow boundary condition, the response of the system is not equal to the excitation.

  6. Dynamic behavior of pipes conveying gas–liquid two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    An, Chen, E-mail: anchen@cup.edu.cn [Offshore Oil/Gas Research Center, China University of Petroleum-Beijing, Beijing 102249 (China); Su, Jian, E-mail: sujian@lasme.coppe.ufrj.br [Nuclear Engineering Program, COPPE, Universidade Federal do Rio de Janeiro, CP 68509, Rio de Janeiro 21941-972 (Brazil)

    2015-10-15

    Highlights: • Dynamic behavior of pipes conveying gas–liquid two-phase flow was analyzed. • The generalized integral transform technique (GITT) was applied. • Excellent convergence behavior and long-time stability were shown. • Effects of volumetric quality and volumetric flow rate on dynamic behavior were studied. • Normalized volumetric-flow-rate stability envelope of dynamic system was determined. - Abstract: In this paper, the dynamic behavior of pipes conveying gas–liquid two-phase flow was analytically and numerically investigated on the basis of the generalized integral transform technique (GITT). The use of the GITT approach in the analysis of the transverse vibration equation lead to a coupled system of second order differential equations in the dimensionless temporal variable. The Mathematica's built-in function, NDSolve, was employed to numerically solve the resulting transformed ODE system. The characteristics of gas–liquid two-phase flow were represented by a slip-ratio factor model that was devised and used for similar problems. Good convergence behavior of the proposed eigenfunction expansions is demonstrated for calculating the transverse displacement at various points of pipes conveying air–water two-phase flow. Parametric studies were performed to analyze the effects of the volumetric gas fraction and the volumetric flow rate on the dynamic behavior of pipes conveying air–water two-phase flow. Besides, the normalized volumetric-flow-rate stability envelope for the dynamic system was obtained.

  7. Gas-liquid two-phase flow across a bank of micropillars

    Science.gov (United States)

    Krishnamurthy, Santosh; Peles, Yoav

    2007-04-01

    Adiabatic nitrogen-water two-phase flow across a bank of staggered circular micropillars, 100μm long with a diameter of 100μm and a pitch-to-diameter ratio of 1.5, was investigated experimentally for Reynolds number ranging from 5 to 50. Flow patterns, void fraction, and pressure drop were obtained, discussed, and compared to large scale as well as microchannel results. Two-phase flow patterns were determined by flow visualization, and a flow map was constructed as a function of gas and liquid superficial velocities. Significant deviations from conventional scale systems, with respect to flow patterns and trend lines, were observed. A unique flow pattern, driven by surface tension, was observed and termed bridge flow. The applicability of conventional scale models to predict the void fraction and two-phase frictional pressure drop was also assessed. Comparison with a conventional scale void fraction model revealed good agreement, but was found to be in a physically wrong form. Thus, a modified physically based model for void fraction was developed. A two-phase frictional multiplier was found to be a strong function of mass flux, unlike in previous microchannel studies. It was observed that models from conventional scale systems did not adequately predict the two-phase frictional multiplier at the microscale, thus, a modified model accounting for mass flux was developed.

  8. Multi-needle capacitance probe for non-conductive two-phase flows

    Science.gov (United States)

    Monrós-Andreu, G.; Martinez-Cuenca, R.; Torró, S.; Escrig, J.; Hewakandamby, B.; Chiva, S.

    2016-07-01

    Despite its variable degree of application, intrusive instrumentation is the most accurate way to obtain local information in a two-phase flow system, especially local interfacial velocity and local interfacial area parameters. In this way, multi-needle probes, based on conductivity or optical principles, have been extensively used in the past few decades by many researchers in two-phase flow investigations. Moreover, the signal processing methods used to obtain the time-averaged two-phase flow parameters in this type of sensor have been thoroughly discussed and validated by many experiments. The objective of the present study is to develop a miniaturized multi-needle probe, based on capacitance measurements applicable to a wide range of non-conductive two-phase flows and, thus, to extend the applicability of multi-needle sensor whilst also maintaining a signal processing methodology provided in the literature for conductivity probes. Results from the experiments performed assess the applicability of the proposed sensor measurement principle and signal processing method for the bubbly flow regime. These results also provide an insight into the sensor application for more complex two-phase flow regimes.

  9. A new two-phase erosion-deposition model for mass flows

    Science.gov (United States)

    Pudasaini, Shiva P.; Fischer, Jan-Thomas

    2016-04-01

    Erosion, entrainment and deposition are complex and dominant, but yet poorly understood, mechanical processes in geophysical mass flows. Here, we propose a novel, two-phase, erosion-deposition model capable of adequately describing these complex phenomena commonly observed in landslides, avalanches, debris flows and bedload transports. The model enhances an existing general two-phase mass flow model (Pudasaini, 2012) by introducing a two-phase variably saturated erodible basal morphology. The adaptive basal morphology allows for the evolution of erosion-deposition-depths, incorporating the inherent physical process and rheological changes of the flowing mixture. With rigorous derivation, we show that appropriate incorporation of the mass and momentum productions and losses in conservative model formulation is essential for the physically correct and mathematically consistent description of erosion-entrainment-deposition processes. Simulation indicates a sharp erosion-front and steady-state-rear erosion depth. The model appropriately captures the emergence and propagation of complex frontal surge dynamics associated with the frontal ambient-drag which is a new hypothesis associated with erosion. The novel enhanced real two-phase model also allows for simulating fluid-run-off during the deposition process. The model resembles laboratory experiments for particle-fluid mixture flows and reveals some major aspects of the mechanics associated with erosion, entrainment and deposition. Reference: Shiva P. Pudasaini (2012): A general two-phase debris flow model. J. Geophys. Res., 117, F03010, doi: 10.1029/2011JF002186.

  10. Performance characteristics of two-phase-flow turbo-expanders used in water-cooled chillers

    Energy Technology Data Exchange (ETDEWEB)

    Brasz, J.J. [United Technologies Carrier, New York, NY (United States)

    1999-07-01

    Use of two-phase-flow throttle loss recovery devices in water-cooled chillers requires satisfactory part-load operation. This paper describes the results of two-phase-flow impulse turbine testing and the data reduction of the test results into a two-phase-flow turbine off-design performance model. It was found that the main parameter controlling the efficiency of two-phase-flow turbine is the ratio of the nozzle spouting velocity to the rotor speed. The turbine mass flow rate is mainly controlled by inlet subcooling of the entering liquid. The strong sensitivity of turbine mass flow rate on inlet subcooling allows the use of a conventional float valve upstream of the turbine as an effective means of controlling the turbine during part-load operation. For a well-designed two-phase-flow turbine, nozzle spouting velocity and therefore turbine efficiency is hardly affected by the amount of inlet subcooling. Also, capacity can be substantially reduced by a reduction in the amount of inlet subcooling entering the turbine nozzles. Hence, turbine part-load efficiency equals its full-load efficiency over a wide range of flow rates using this control concept. (Author)

  11. DSMC simulation of two-phase plume flow with UV radiation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jie; Liu, Ying; Wang, Ning; Jin, Ling [College of Aerospace Science and Engineering, National University of Defense Technology, Changsha, Hunan, 410073 (China)

    2014-12-09

    Rarefied gas-particle two-phase plume in which the phase of particles is liquid or solid flows from a solid propellant rocket of hypersonic vehicle flying at high altitudes, the aluminum oxide particulates not only impact the rarefied gas flow properties, but also make a great difference to plume radiation signature, so the radiation prediction of the rarefied gas-particle two-phase plume flow is very important for space target detection of hypersonic vehicles. Accordingly, this project aims to study the rarefied gas-particle two-phase flow and ultraviolet radiation (UV) characteristics. Considering a two-way interphase coupling of momentum and energy, the direct simulation Monte Carlo (DSMC) method is developed for particle phase change and the particle flow, including particulate collision, coalescence as well as separation, and a Monte Carlo ray trace model is implemented for the particulate UV radiation. A program for the numerical simulation of the gas-particle two-phase flow and radiation in which the gas flow nonequilibrium is strong is implemented as well. Ultraviolet radiation characteristics of the particle phase is studied based on the calculation of the flow field coupled with the radiation calculation, the radiation model for different size particles is analyzed, focusing on the effects of particle emission, absorption, scattering as well as the searchlight emission of the nozzle. A new approach may be proposed to describe the rarefied gas-particle two-phase plume flow and radiation transfer characteristics in this project.

  12. Design and evaluation of a two-phase turbine for low quality steam--water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Comfort, W.J. III

    1977-05-16

    A new two-phase turbine was designed and built for testing in the laboratory, using a low quality steam-water mixture as a working fluid. The measured performance compares well with performance predictions of a numerical model of the expander. Details of the selection of the type of expander are given. The design of an experimental expander for use in a clean two-phase flow laboratory experiment and the development of a numerical model for performance analysis and extrapolations are described. Experiments including static cascade performance with two-phase fluid, disk friction and windage measurements, and two-phase performance measurements of the experimental expander are reported. Comparisons of the numerical model and experimental results, and the prediction of the performance of an advanced design, indicating how performance improvements can be achieved, are also included. An engine efficiency of 23 percent for a single-nozzle test was measured. Full admission performance, based upon the numerical model and achievable nozzle thrust coefficients indicate that an engine efficiency of between 38 and 48 percent can be realized with present technology. If maximum liquid removal loss is assumed, this performance range is predicted to be 38 to 41 percent. Droplet size reduction and the development and implementation of enhanced two-phase flow analysis techniques should make it possible to achieve the research goal of 70 percent engine efficiency.

  13. Two phase convective heat transfer augmentation in swirl flow with non-boiling

    Energy Technology Data Exchange (ETDEWEB)

    Cha, K.O. [Myong Ji University, Kyonggi-do (Korea, Republic of); Kim, J.G. [Myongji University Graduate School, Kyonggi-do (Korea, Republic of)

    1995-10-01

    Two phase flow phenomena are observed in many industrial facilities and make much importance of optimum design for nuclear power plant and various heat exchangers. This experimental study has been investigated the classification of the flow pattern, the local void distribution and convective heat transfer in swirl and non-swirl two phase flow under the isothermal and nonisothermal conditions. The convective heat transfer coefficients in the single phase water flow were measured and compared with the calculated results from the Sieder-Tate correlation. These coefficients were used for comparisons with the two-phase heat transfer coefficients in the flow orientations. The experimental results indicate, that the void probe signal and probability density function of void distribution can used into classify the flow patterns, no significant difference in voidage distribution was observed between isothermal and non-isothermal condition in non-swirl flow, the values of two phase heat transfer coefficients increase when superficial air velocities increase, and the enhancement of the values is observed to be most pronounced at the highest superficial water velocity in non-swirl flow. Also two phase heat transfer coefficients in swirl flow are increased when the twist ratios are decreased. (author). 13 refs., 15 figs.

  14. Soil CO2 and N2O Emissions in Maize Growing Season Under Different Fertilizer Regimes in an Upland Red Soil Region of South China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xu-bo; WU Lian-hai; SUN Nan; DING Xue-shan; LI Jian-wei; WANG Bo-ren; LI Dong-chu

    2014-01-01

    Upland red soils have been identiifed as major CO2 and N2O sources induced by human activities such as fertilization. To monitor characteristics of soil surface CO2 and N2O lfuxes in cropland ecosystems after continuous fertilizer applications over decades and to separate the respective contributions of root and heterotrophic respiration to the total soil CO2 and N2O lfuxes, the measurements of soil surface CO2 and N2O lfuxes throughout the maize growing season in 2009 were carried out based on a fertilization experiment (from 1990) through of the maize (Zea mays L.) growing season in red soil in southern China. Five fertilization treatments were chosen from the experiment for study: zero-fertilizer application (CK), nitrogen-phosphorus-potassium (NPK) fertilizer application only, pig manure (M), NPK plus pig manure (NPKM) and NPK with straw (NPKS). Six chambers were installed in each plot. Three of them are in the inter-row soil (NR) and the others are in the soil within the row (R). Each fertilizer treatment received the same amount of N (300kg ha-1 yr-1). Results showed that cumulative soil CO2 lfuxes in NR or R were both following the order: NPKS>M, NPKM>NPK>CK. The contributions of root respiration to soil CO2 lfuxes was 40, 44, 50, 47 and 35%in CK, NPK, NPKM, M and NPKS treatments, respectively, with the mean value of 43%. Cumulative soil N2O lfuxes in NR or R were both following the order: NPKS, NPKM>M>NPK>CK, and soil N2O lfuxes in R were 18, 20 and 30%higher than that in NR in NPKM, M and NPKS treatments, respectively, but with no difference between NR and R in NPK treatment. Furthermore, combine with soil temperature at -5 cm depth and soil moisture (0-20cm) together could explain 55-70% and 42-59% of soil CO2 and N2O emissions with root interference and 62-78%and 44-63% of that without root interference, respectively. In addition, soil CO2 and N2O lfuxes per unit yield in NPKM (0.55 and 0.10kg Ct-1) and M(0.65 and 0.13g Nt-1) treatments were lower than

  15. Impacts of Short-Rotation Early-Growing Season Prescribed Fire on a Ground Nesting Bird in the Central Hardwoods Region of North America.

    Directory of Open Access Journals (Sweden)

    H Tyler Pittman

    Full Text Available Landscape-scale short-rotation early-growing season prescribed fire, hereafter prescribed fire, in upland hardwood forests represents a recent shift in management strategies across eastern upland forests. Not only does this strategy depart from dormant season to growing season prescriptions, but the strategy also moves from stand-scale to landscape-scale implementation (>1,000 ha. This being so, agencies are making considerable commitments in terms of time and resources to this management strategy, but the effects on wildlife in upland forests, especially those dominated by hardwood canopy species, are relatively unknown. We initiated our study to assess whether this management strategy affects eastern wild turkey reproductive ecology on the Ozark-St. Francis National Forest. We marked 67 wild turkey hens with Global Positioning System (GPS Platform Transmitting Terminals in 2012 and 2013 to document exposure to prescribed fire, and estimate daily nest survival, nest success, and nest-site selection. We estimated these reproductive parameters in forest units managed with prescribed fire (treated and units absent of prescribed fire (untreated. Of 60 initial nest attempts monitored, none were destroyed or exposed to prescribed fire because a majority of fires occurred early than a majority of the nesting activity. We found nest success was greater in untreated units than treated units (36.4% versus 14.6%. We did not find any habitat characteristic differences between successful and unsuccessful nest-sites. We found that nest-site selection criteria differed between treated and untreated units. Visual concealment and woody ground cover were common selection criteria in both treated and untreated units. However, in treated units wild turkey selected nest-sites with fewer small shrubs (20 cm DBH but not in untreated units. In untreated units wild turkey selected nest-sites with more large shrubs (≥5 cm ground diameter but did not select for small

  16. Impacts of Short-Rotation Early-Growing Season Prescribed Fire on a Ground Nesting Bird in the Central Hardwoods Region of North America.

    Science.gov (United States)

    Pittman, H Tyler; Krementz, David G

    2016-01-01

    Landscape-scale short-rotation early-growing season prescribed fire, hereafter prescribed fire, in upland hardwood forests represents a recent shift in management strategies across eastern upland forests. Not only does this strategy depart from dormant season to growing season prescriptions, but the strategy also moves from stand-scale to landscape-scale implementation (>1,000 ha). This being so, agencies are making considerable commitments in terms of time and resources to this management strategy, but the effects on wildlife in upland forests, especially those dominated by hardwood canopy species, are relatively unknown. We initiated our study to assess whether this management strategy affects eastern wild turkey reproductive ecology on the Ozark-St. Francis National Forest. We marked 67 wild turkey hens with Global Positioning System (GPS) Platform Transmitting Terminals in 2012 and 2013 to document exposure to prescribed fire, and estimate daily nest survival, nest success, and nest-site selection. We estimated these reproductive parameters in forest units managed with prescribed fire (treated) and units absent of prescribed fire (untreated). Of 60 initial nest attempts monitored, none were destroyed or exposed to prescribed fire because a majority of fires occurred early than a majority of the nesting activity. We found nest success was greater in untreated units than treated units (36.4% versus 14.6%). We did not find any habitat characteristic differences between successful and unsuccessful nest-sites. We found that nest-site selection criteria differed between treated and untreated units. Visual concealment and woody ground cover were common selection criteria in both treated and untreated units. However, in treated units wild turkey selected nest-sites with fewer small shrubs (20 cm DBH) but not in untreated units. In untreated units wild turkey selected nest-sites with more large shrubs (≥5 cm ground diameter) but did not select for small shrubs or

  17. Variation in agricultural CO2 fluxes during the growing season, collected from more than ten eddy covariance towers in the Mississippi Delta Region

    Science.gov (United States)

    Runkle, B.; Suvocarev, K.; Reba, M. L.; Novick, K. A.; White, P.; Anapalli, S.; Locke, M. A.; Rigby, J.; Bhattacharjee, J.

    2016-12-01

    Agriculture is unique as an anthropogenic activity that plays both a large role in carbon and water cycling and whose management activities provide a key opportunity for responses to climate change. It is therefore especially crucial to bring field observations into the modeling community, test remote sensing products, encourage policy debate, and enable carbon offsets markets that generate revenue and fund climate-smart activities. The accurate measurement of agricultural CO2 exchange - both primary productivity and ecosystem respiration - in concert with evapotranspiration provides crucial information on agro-ecosystem functioning and improves our predictive capacity for estimating the impacts of climate change. In this study we report field measurements from more than 10 eddy covariance towers in the Lower Mississippi River Basin taken during the summer months of 2016. Many towers, some recently deployed, are being aggregated into a regional network known as Delta-Flux, which will ultimately include 15-20 towers by 2017. Set in and around the Mississippi Delta Region within Louisiana, Arkansas, and Mississippi, the network will collect flux, micrometeorological, and crop yield data in order to construct estimates of regional CO2 exchange. These time-series data are gap-filled using statistical and process-based models to generate estimates of summer CO2 flux. The tower network is comprised of sites representing widespread agriculture production, including rice, cotton, corn, soybean, and sugarcane; intensively managed pine forest; and bottomland hardwood forest. Unique experimental production practices are represented in the network and include restricted water use, bioenergy, and by-product utilization. Several towers compose multi-field sites testing innovative irrigation or management practices. Current mapping of agricultural carbon exchange - based on land cover layers and fixed crop emission factors - suggests an unconstrained carbon flux estimate in this

  18. Two-Phase Cooling of Targets and Electronics for Particle Physics Experiments

    CERN Document Server

    Thome, J R; Park, J E

    2009-01-01

    An overview of the LTCM lab’s decade of experience with two-phase cooling research for computer chips and power electronics will be described with its possible beneficial application to high-energy physics experiments. Flow boiling in multi-microchannel cooling elements in silicon (or aluminium) have the potential to provide high cooling rates (up to as high as 350 W/cm2), stable and uniform temperatures of targets and electronics, and lightweight construction while also minimizing the fluid inventory. An overview of two-phase flow and boiling research in single microchannels and multi-microchannel test elements will be presented together with video images of these flows. The objective is to stimulate discussion on the use of two-phase cooling in these demanding applications, including the possible use of CO2.

  19. Numerical simulation of the two-phase flow produced by spraying a liquid by a nozzle

    Science.gov (United States)

    Simakov, N. N.

    2017-07-01

    A numerical experiment on the simulation of the two-phase flow formed during spraying of a liquid by a nozzle has been described. The radial and axial velocity profiles of the droplets and gas in the free spray and in the two-phase flow through a cylindrical apparatus have been calculated and represented taking into account the early drag crisis of droplets and peculiarities of turbulent friction in the gas, which was detected in previous experiments. The distinguishing feature of the numerical model of the two-phase flow is that it employs the differential equations describing the nonstationary flow of a compressible gas as the initial equations. In transition to their difference analog, the familiar Lax-Wendorff algorithm has been used. A comparison of the results of calculations based on this model with experimental data has demonstrated their concordance.

  20. Selective separation and enrichment of proteins in aqueous two-phase extraction system

    Institute of Scientific and Technical Information of China (English)

    Feng Qu; Hao Qin; Min Dong; Dong Xu Zhao; Xin Ying Zhao; Jing Hua Zhang

    2009-01-01

    A simple aqueous two-phase extraction system(ATPS)of PEG/phosphate was proposed for selective separation and enrichment of proteins.The combination of ATPE with HPLC was applied to identify the partition of proteins in two phases.Five proteins (bovine serum albumin,Cytochrome C,lysozyme,myoglobin,and trypsin)were used as model proteins to study the effect of phosphate concentration and pH on proteins partition.The PEG/phosphate system was firstly applied to real human saliva and plasma samples,some proteins showed obviously different partition in two phases.The primary results manifest the selective separation and enrichment of proteins in ATPS provided the potential for high abundance proteins depletion in proteomics.

  1. Two-phase pressure drop across a hydrofoil-based micro pin device using R-123

    Energy Technology Data Exchange (ETDEWEB)

    Kosar, Ali [Mechatronics Engineering Program, Sabanci University, Orhanli, Tuzla, 34956 Istanbul (Turkey)

    2008-05-15

    The two-phase pressure drop in a hydrofoil-based micro pin fin heat sink has been investigated using R-123 as the working fluid. Two-phase frictional multipliers have been obtained over mass fluxes from 976 to 2349 kg/m{sup 2} s and liquid and gas superficial velocities from 0.38 to 1.89 m/s and from 0.19 to 24 m/s, respectively. It has been found that the two-phase frictional multiplier is strongly dependent on flow pattern. The theoretical prediction using Martinelli parameter based on the laminar fluid and laminar gas flow represented the experimental data fairly well for the spray-annular flow. For the bubbly and wavy-intermittent flow, however, large deviations from the experimental data were recorded. The Martinelli parameter was successfully used to determine the flow patterns, which were bubbly, wavy-intermittent, and spray-annular flow in the current study. (author)

  2. Reduced-gravity two-phase flow experiments in the NASA KC-135

    Science.gov (United States)

    Cuta, Judith M.; Michener, Thomas E.; Best, Frederick R.; Kachnik, Leo J.

    1988-01-01

    An adequate understanding is sought of flow and heat transfer behavior in reduced and zero gravity conditions. Microgravity thermal-hydraulic analysis capabilities were developed for application to space nuclear power systems. A series of reduced gravity two phase flow experiments using the NASA KC-135 were performed. The objective was to supply basic thermal hydraulic information that could be used in development of analytical tools for design of space power systems. The experiments are described. Two main conclusions were drawn. First, the tests demonstrate that the KC-135 is a suitable test environment for obtaining two phase flow and heat transfer data in reduced gravity conditions. Second, the behavior of two phase flow in low gravity is sufficiently different from that obtained in 1 g to warrant intensive investigation of the phenomenon if adequate analytical tools are to be developed for microgravity conditions.

  3. Entropy analysis on non-equilibrium two-phase flow models

    Energy Technology Data Exchange (ETDEWEB)

    Karwat, H.; Ruan, Y.Q. [Technische Universitaet Muenchen, Garching (Germany)

    1995-09-01

    A method of entropy analysis according to the second law of thermodynamics is proposed for the assessment of a class of practical non-equilibrium two-phase flow models. Entropy conditions are derived directly from a local instantaneous formulation for an arbitrary control volume of a structural two-phase fluid, which are finally expressed in terms of the averaged thermodynamic independent variables and their time derivatives as well as the boundary conditions for the volume. On the basis of a widely used thermal-hydraulic system code it is demonstrated with practical examples that entropy production rates in control volumes can be numerically quantified by using the data from the output data files. Entropy analysis using the proposed method is useful in identifying some potential problems in two-phase flow models and predictions as well as in studying the effects of some free parameters in closure relationships.

  4. Analytical solution of laminar-laminar stratified two-phase flows with curved interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Brauner, N.; Rovinsky, J.; Maron, D.M. [Tel-Aviv Univ. (Israel)

    1995-09-01

    The present study represents a complete analytical solution for laminar two-phase flows with curved interfaces. The solution of the Navier-Stokes equations for the two-phases in bipolar coordinates provides the `flow monograms` describe the relation between the interface curvature and the insitu flow geometry when given the phases flow rates and viscosity ratios. Energy considerations are employed to construct the `interface monograms`, whereby the characteristic interfacial curvature is determined in terms of the phases insitu holdup, pipe diameter, surface tension, fluids/wall adhesion and gravitation. The two monograms are then combined to construct the system `operational monogram`. The `operational monogram` enables the determination of the interface configuration, the local flow characteristics, such as velocity profiles, wall and interfacial shear stresses distribution as well as the integral characteristics of the two-phase flow: phases insitu holdup and pressure drop.

  5. On Riemann Solvers and Kinetic Relations for Isothermal Two-Phase Flows with Surface Tension

    CERN Document Server

    Rohde, Christian

    2016-01-01

    We consider a sharp-interface approach for the inviscid isothermal dynamics of compressible two-phase flow, that accounts for phase transition and surface tension effects. To fix the mass exchange and entropy dissipation rate across the interface kinetic relations are frequently used. The complete uni-directional dynamics can then be understood by solving generalized two-phase Riemann problems. We present new well-posedness theorems for the Riemann problem and corresponding computable Riemann solvers, that cover quite general equations of state, metastable input data and curvature effects. The new Riemann solver is used to validate different kinetic relations on physically relevant problems including a comparison with experimental data. Riemann solvers are building blocks for many numerical schemes that are used to track interfaces in two-phase flow. It is shown that the new Riemann solver enables reliable and efficient computations for physical situations that could not be treated before.

  6. Investigation of two-phase heat transfer coefficients of argon-freon cryogenic mixed refrigerants

    Science.gov (United States)

    Baek, Seungwhan; Lee, Cheonkyu; Jeong, Sangkwon

    2014-11-01

    Mixed refrigerant Joule Thomson refrigerators are widely used in various kinds of cryogenic systems these days. Although heat transfer coefficient estimation for a multi-phase and multi-component fluid in the cryogenic temperature range is necessarily required in the heat exchanger design of mixed refrigerant Joule Thomson refrigerators, it has been rarely discussed so far. In this paper, condensation and evaporation heat transfer coefficients of argon-freon mixed refrigerant are measured in a microchannel heat exchanger. A Printed Circuit Heat Exchanger (PCHE) with 340 μm hydraulic diameter has been developed as a compact microchannel heat exchanger and utilized in the experiment. Several two-phase heat transfer coefficient correlations are examined to discuss the experimental measurement results. The result of this paper shows that cryogenic two-phase mixed refrigerant heat transfer coefficients can be estimated by conventional two-phase heat transfer coefficient correlations.

  7. The Two-Phase Hell-Shaw Flow: Construction of an Exact Solution

    Science.gov (United States)

    Malaikah, K. R.

    2013-03-01

    We consider a two-phase Hele-Shaw cell whether or not the gap thickness is time-dependent. We construct an exact solution in terms of the Schwarz function of the interface for the two-phase Hele-Shaw flow. The derivation is based upon the single-valued complex velocity potential instead of the multiple-valued complex potential. As a result, the construction is applicable to the case of the time-dependent gap. In addition, there is no need to introduce branch cuts in the computational domain. Furthermore, the interface evolution in a two-phase problem is closely linked to its counterpart in a one-phase problem

  8. Adaptive sampling in two-phase designs: a biomarker study for progression in arthritis

    Science.gov (United States)

    McIsaac, Michael A; Cook, Richard J

    2015-01-01

    Response-dependent two-phase designs are used increasingly often in epidemiological studies to ensure sampling strategies offer good statistical efficiency while working within resource constraints. Optimal response-dependent two-phase designs are difficult to implement, however, as they require specification of unknown parameters. We propose adaptive two-phase designs that exploit information from an internal pilot study to approximate the optimal sampling scheme for an analysis based on mean score estimating equations. The frequency properties of estimators arising from this design are assessed through simulation, and they are shown to be similar to those from optimal designs. The design procedure is then illustrated through application to a motivating biomarker study in an ongoing rheumatology research program. Copyright © 2015 © 2015 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd. PMID:25951124

  9. Two-Phase Master Sintering Curve for 17-4 PH Stainless Steel

    Science.gov (United States)

    Jung, Im Doo; Ha, Sangyul; Park, Seong Jin; Blaine, Deborah C.; Bollina, Ravi; German, Randall M.

    2016-11-01

    The sintering behavior of 17-4 PH stainless steel has been efficiently characterized by a two-phase master sintering curve model (MSC). The activation energy for the sintering of gas-atomized and water-atomized 17-4 PH powders is derived using the mean residual method, and the relative density of both powders is well predicted by the two-phase MSC model. The average error between dilatometry data and MSC model has been reduced by 68 pct for gas-atomized powder and by 45 pct for water-atomized powder through the consideration of phase transformation of 17-4 PH in MSC model. The effect of δ-ferrite is considered in the two-phase MSC model, leading to excellent explanation of the sintering behavior for 17-4 PH stainless steel. The suggested model is useful in predicting the densification and phase change phenomenon during sintering of 17-4 PH stainless steel.

  10. An Implicit Numerical Method for the Simulation of Two-phase Flow

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Han Young; Lee, Seung-Jun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Jeong, Jae Jun [Pusan National University, Busan (Korea, Republic of)

    2015-10-15

    An implicit numerical method is presented for the analysis of two-phase flows in PWRs. Numerical stability and efficiency are improved by decoupling energy equations from the pressure equation. All the convection and diffusion terms are calculated implicitly. The proposed numerical method is verified against conceptual two-phase flow problems. An implicit numerical method has been proposed for two-phase calculation where energy equations are decoupled from the pressure equation. Convection and diffusion terms are calculated implicitly. The calculation results are the same for PME-explicit, PM explicit, and PM-implicit. Large time step size has been tested with PM-implicit-c and the results are also the same.

  11. Numerical Study of Void Fraction Distribution Propagation in Gas-Liquid Two-Phase Flow

    Institute of Scientific and Technical Information of China (English)

    YANG Jianhui; LI Qing; LU Wenqiang

    2005-01-01

    A dynamic propagation model was developed for waves in two-phase flows by assuming that continuity waves and dynamic waves interact nonlinearly for certain flow conditions. The drift-flux model is solved with the one-dimensional continuity equation for gas-liquid two-phase flows as an initial-boundary value problem solved using the characteristic-curve method. The numerical results give the void fraction distribution propagation in a gas-liquid two-phase flow which shows how the flow pattern transition occurs. The numerical simulations of different flow patterns show that the void fraction distribution propagation is determined by the characteristics of the drift-flux between the liquid and gas flows and the void fraction range. Flow pattern transitions begin around a void fraction of 0.27 and end around 0.58. Flow pattern transitions do not occur for very high void concentrations.

  12. Numerical Simulation of Erosion-Corrosion in the Liquid Solid Two-Phase Flow

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Erosion-corrosion of liquid-solid two-phase flow occurring in a pipe with sudden expansion in cross section is numerically simulated in this paper. The global model for erosion-corrosion process includes three main components: the liquid-solid two-phase flow model, erosion model and corrosion model. The Euierian-Lagranglan approach is used to simulate liquid-solid two-phase flow, while the stochastic trajectory model was adopted to obtain properties of particle phase. Two-way coupling effect between the fluid and the particle phase is considered in the model. The accuracy of the models is tested by the data in the reference. The comparison shows that the model is basically correct and feasible.

  13. The solidification of two-phase heterogeneous materials: Theory versus experiment

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bin; KIM Tongbeum; LU TianJian

    2009-01-01

    The solidification behavior of two-phase heterogeneous materials such as close-celled aluminum foams was analytically studied. The proposed analytical model can precisely predict the location of solidification front as well as the full solidification time for a two-phase heterogeneous material composed of aluminum melt and non-conducting air pores. Experiments using distilled water simulating the aluminum melt to be solidified (frozen) were subsequently conducted to validate the analytical model for two selected porosities (ε), ε=0 and 0.5. Full numerical simulations with the method of finite difference were also performed to examine the influence of pore shape on solidification. The remarkable agreement between theory and experiment suggests that the delay of solidification in the two-phase heterogeneous material is mainly caused by the reduction of bulk thermal conductivity due to the presence of pores, as this is the sole mechanism accounted for by the analytical model for solidification in a porous medium.

  14. Thermodynamic properties and mixing thermodynamic parameters of two-phase metallic melts

    Institute of Scientific and Technical Information of China (English)

    Jian Zhang

    2005-01-01

    Based on the calculating model of metallic melts involving eutectic, the calculating equations of mixing thermodynamic parameters for two phase metallic melts have been formulated in the light of those equations of homogeneous solutions. Irrespective as to whether the activity deviation relative to Raoultian behavior is positive or negative, or the deviation is symmetrical or unsymmetrical, the evaluated results not only agree well with experimental values, but also strictly obey the mass action law. This testifies that these equations can authentically reflect the structural reality and mixing thermodynamic characteristics of two-phase metallic melts. The calculating equations of mixing thermodynamic parameters for the model of two phase metallic melts offer two practical criteria (activity and mixing thermodynamic parameters) and one theoretical criterion (the mass action law).

  15. Thermodynamic calculations of a two-phase thermosyphon loop for cold neutron sources

    Science.gov (United States)

    de Haan, Victor-O.; Gommers, René; Rowe, J. Michael

    2017-07-01

    A new method is described for thermodynamic calculations of a two-phase thermosyphon loop based on a one-dimensional finite element division, where each time-step is split up in a change of enthalpy and a change in entropy. The method enables the investigation of process responses for a cooling loop from room temperature down to cryogenic temperatures. The method is applied for the simulation of two distinct thermosyphon loops: a two-phase deuterium and a two-phase hydrogen thermosyphon loop. The simulated process responses are compared to measurements on these loops. The comparisons show that the method can be used to optimize the design of such loops with respect to performance and resulting void fractions.

  16. OPTIMIZATION DESIGN OF GAS-PARTICLE TWO-PHASE AXIAL-FLOW FAN

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on the shaping theory of writhed blade in streamline design, the geometric shape of blade is designed and then computational formulas for the dynamic design of fan with writhed the blades in gas-particle two-phase axial-flow are derived with the two-phase continuum coupling model. Concurrently, the correlation between the structure of impeller and flow-field dynamic functional parameters is presented. Further, the software for the optimization design of gas-particle two-phase axial-flow fan with writhed blades is obtained. By means of the available software, a sample fan is formed with its all dynamic characteristic curves and geometric shape. Finally, the conclusion on the effect of particles on fan running is reached, quantitatively and qualitatively, as is expected in the fan industry.

  17. Numerical simulation of the two-phase flows in a hydraulic coupling by solving VOF model

    Science.gov (United States)

    Luo, Y.; Zuo, Z. G.; Liu, S. H.; Fan, H. G.; Zhuge, W. L.

    2013-12-01

    The flow in a partially filled hydraulic coupling is essentially a gas-liquid two-phase flow, in which the distribution of two phases has significant influence on its characteristics. The interfaces between the air and the liquid, and the circulating flows inside the hydraulic coupling can be simulated by solving the VOF two-phase model. In this paper, PISO algorithm and RNG k-ɛ turbulence model were employed to simulate the phase distribution and the flow field in a hydraulic coupling with 80% liquid fill. The results indicate that the flow forms a circulating movement on the torus section with decreasing speed ratio. In the pump impeller, the air phase mostly accumulates on the suction side of the blades, while liquid on the pressure side; in turbine runner, air locates in the middle of the flow passage. Flow separations appear near the blades and the enclosing boundaries of the hydraulic coupling.

  18. Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume II. Chapters 6-10)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, T.; Park, J.; Kojasoy, G.

    2003-03-15

    Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.

  19. Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume III. Chapters 11-14)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, T.; Park, J.; Kojasoy, G.

    2003-03-15

    Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.

  20. Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume IV. Chapters 15-19)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, T.; Park, J.; Kojasoy, G.

    2003-03-15

    Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.

  1. Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume I. Chapters 1-5)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, T.; Park, J.; Kojasoy, G.

    2003-03-15

    Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.

  2. Stability of Wavy Films in Gas-Liquid Two-Phase Flows at Normal and Microgravity Conditions

    Science.gov (United States)

    Balakotaiah, V.; Jayawardena, S. S.

    1996-01-01

    For flow rates of technological interest, most gas-liquid flows in pipes are in the annular flow regime, in which, the liquid moves along the pipe wall in a thin, wavy film and the gas flows in the core region. The waves appearing on the liquid film have a profound influence on the transfer rates, and hence on the design of these systems. We have recently proposed and analyzed two boundary layer models that describe the characteristics of laminar wavy films at high Reynolds numbers (300-1200). Comparison of model predictions to 1-g experimental data showed good agreement. The goal of our present work is to understand through a combined program of experimental and modeling studies the characteristics of wavy films in annular two-phase gas-liquid flows under normal as well as microgravity conditions in the developed and entry regions.

  3. The source vector and static displacement field by elastic dislocation on the two-phase saturated medium

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on the Biot's theory about two-phase saturated medium, according to the character of d function, the Green function on two-phase saturated medium by the point source under concentrated force can be derived. By the Betti's theorem for the two-phase saturated medium field, the source vector and static displacement field by elastic dislocation on the two-phase saturated medium were comprehensively discussed.

  4. RESEARCH ON THE FLOW STABILITY IN A CYLINDRICAL PARTICLE TWO-PHASE BOUNDARY LAYER

    Institute of Scientific and Technical Information of China (English)

    林建忠; 聂德明

    2003-01-01

    Based on the momentum and constitutive equations, the modified Orr-Sommerfeld equation describing the flow stability in a cylindrical particle two-phase flow was derived. For a cylindrical particle two-phase boundary layer, the neutral stability curves and critical Reynolds number were given with numerical simulation. The results show that the cylindrical particles have a suppression effect on the flow instability, the larger the particle volume fraction and the particle aspect-ratio are, the more obvious the suppression effect is.

  5. Investigation on two-phase flow instability in steam generator of integrated nuclear reactor

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    In the pressure range of 3-18MPa,high pressure steam-water two-phase flow density wave instability in vertical upward parallel pipes with inner diameter of 12mm is studied experimentally.The oscillation curves of two-phase flow instability and the effects of several parameters on the oscillation threshold of the system are obtained.Based on the small pertubation linearization method and the stability principles of automatic control system,a mathematical model is developed to predict the characteristics of density wave instability threshold.The predictions of the model are in good agreement with the experimental results.

  6. Position Control of Synchronous Motor Drive by Modified Adaptive Two-phase Sliding Mode Controller

    Institute of Scientific and Technical Information of China (English)

    Mohamed Said Sayed Ahmed; Ping Zhang; Yun-Jie Wu

    2008-01-01

    A modified adaptive two-phase sliding mode controller for the synchronous motor drive that is highly robust to uncertain-ties and external disturbances is proposed in this paper. The proposed controller uses two-phase sliding mode control (SMC) where the 1st phase mainly controls the system in steady states and disturbed states-it is a smoothing phase. The 2nd phase is used mainly in the case of disturbed states. Also, it is an autotuning phase and uses a simple adaptive algorithm to tune the gain of conventional variable structure control (VSC). The modified controller is useful in position control of a permanent magnet synchronous drive.

  7. A phenomenological model of two-phase (air/fuel droplet developing and breakup

    Directory of Open Access Journals (Sweden)

    Pavlović Radomir R.

    2013-01-01

    Full Text Available Effervescent atomization namely the air-filled liquid atomization comprehends certain complex two-phase phenomenon that are difficult to be modeled. Just a few researchers have found the mathematical expressions for description of the complex atomization model of the two-phase mixture air/diesel fuel. In the following review, developing model of twophase (air/fuel droplet of Cummins spray pump-injector is shown. The assumption of the same diameters of the droplet and the opening of the atomizer is made, while the air/fuel mass ratio inside the droplet varies.

  8. Camomile autofermentation in polyethylene glycol/dextran two-phase system

    Directory of Open Access Journals (Sweden)

    Đaković Sanja D.

    2008-01-01

    Full Text Available The objective of this study was the investigation of the extractive bioconversion of apigenin-7-O-β-glucoside in camomile ligulate flowers into apigenin by autofermentation in polyethylene glycol 6000/dextran 200000 two-phase system. In 22.5% polyethylene glycol/14% dextran aqueous two-phase system the obtained yield of apigenin in the top phase was 96.5%. In the presence of plant material that partiotioned to the interphase, the yield of apigenin in the top phase was 3.5 times higher in comparison to the model system.

  9. Preliminary Two-Phase Terry Turbine Nozzle Models for RCIC Off-Design Operation Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Haihua [Idaho National Lab. (INL), Idaho Falls, ID (United States); O' Brien, James [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-06-12

    This report presents the effort to extend the single-phase analytical Terry turbine model to cover two-phase off-design conditions. The work includes: (1) adding well-established two-phase choking models – the Isentropic Homogenous Equilibrium Model (IHEM) and Moody’s model, and (2) theoretical development and implementation of a two-phase nozzle expansion model. The two choking models provide bounding cases for the two-phase choking mass flow rate. The new two-phase Terry turbine model uses the choking models to calculate the mass flow rate, the critical pressure at the nozzle throat, and steam quality. In the divergent stage, we only consider the vapor phase with a similar model for the single-phase case by assuming that the liquid phase would slip along the wall with a much slower speed and will not contribute the impulse on the rotor. We also modify the stagnation conditions according to two-phase choking conditions at the throat and the cross-section areas for steam flow at the nozzle throat and at the nozzle exit. The new two-phase Terry turbine model was benchmarked with the same steam nozzle test as for the single-phase model. Better agreement with the experimental data is observed than from the single-phase model. We also repeated the Terry turbine nozzle benchmark work against the Sandia CFD simulation results with the two-phase model for the pure steam inlet nozzle case. The RCIC start-up tests were simulated and compared with the single-phase model. Similar results are obtained. Finally, we designed a new RCIC system test case to simulate the self-regulated Terry turbine behavior observed in Fukushima accidents. In this test, a period inlet condition for the steam quality varying from 1 to 0 is applied. For the high quality inlet period, the RCIC system behaves just like the normal operation condition with a high pump injection flow rate and a nominal steam release rate through the turbine, with the net addition of water to the primary system; for

  10. Two-phase flow stability structure in a natural circulation system

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Zhiwei [Nuclear Engineering Laboratory Zurich (Switzerland)

    1995-09-01

    The present study reports a numerical analysis of two-phase flow stability structures in a natural circulation system with two parallel, heated channels. The numerical model is derived, based on the Galerkin moving nodal method. This analysis is related to some design options applicable to integral heating reactors with a slightly-boiling operation mode, and is also of general interest to similar facilities. The options include: (1) Symmetric heating and throttling; (2) Asymmetric heating and symmetric throttling; (3) Asymmetric heating and throttling. The oscillation modes for these variants are discussed. Comparisons with the data from the INET two-phase flow stability experiment have qualitatively validated the present analysis.

  11. Problems of heat transfer and hydraulics of two-phase media

    CERN Document Server

    Kutateladze, S S

    1969-01-01

    Problems of Heat Transfer and Hydraulics of Two-Phase Media presents the theory of heat transfer and hydrodynamics. This book discusses the various aspects of heat transfer and the flow of two-phase systems. Organized into two parts encompassing 22 chapters, this book starts with an overview of the laws of similarity for heat transfer to or from a flowing liquid with various physical properties and allowed for variation in viscosity and thermal conductivity. This book then explores the general functional relationship that exists between viscosity and thermal conductivity for thermodynamically

  12. Research of Characteristics of Gas-liquid Two-phase Pressure Drop in Microreactor

    OpenAIRE

    Li Dan

    2015-01-01

    With the research system of nitrogen and deionized water, this paper researches the pressure drop of gas-liquid two-phase flow in the circular microchannel with an inner diameter which is respectively 0.9mm and 0.5mm, analyzes the effect of microchannel diameter on gas-liquid two-phase frictional pressure drop in the microchannel reactor, and compares with the result of frictional pressure drop and the predicting result of divided-phase flow pattern. The result shows that, the gas-liquid two-...

  13. Two-Phase Flow in Geothermal Wells: Development and Uses of a Good Computer Code

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz-Ramirez, Jaime

    1983-06-01

    A computer code is developed for vertical two-phase flow in geothermal wellbores. The two-phase correlations used were developed by Orkiszewski (1967) and others and are widely applicable in the oil and gas industry. The computer code is compared to the flowing survey measurements from wells in the East Mesa, Cerro Prieto, and Roosevelt Hot Springs geothermal fields with success. Well data from the Svartsengi field in Iceland are also used. Several applications of the computer code are considered. They range from reservoir analysis to wellbore deposition studies. It is considered that accurate and workable wellbore simulators have an important role to play in geothermal reservoir engineering.

  14. Determination of production-shipment policy using a two-phase algebraic approach

    Directory of Open Access Journals (Sweden)

    Huei-Hsin Chang

    2012-04-01

    Full Text Available The optimal production-shipment policy for end products using mathematicalmodeling and a two-phase algebraic approach is investigated. A manufacturing systemwith a random defective rate, a rework process, and multiple deliveries is studied with thepurpose of deriving the optimal replenishment lot size and shipment policy that minimisestotal production-delivery costs. The conventional method uses differential calculus on thesystem cost function to determine the economic lot size and optimal number of shipmentsfor such an integrated vendor-buyer system, whereas the proposed two-phase algebraicapproach is a straightforward method that enables practitioners who may not havesufficient knowledge of calculus to manage real-world systems more effectively.

  15. The performance of a cryogenic pump for the two-phase flow condition

    OpenAIRE

    YAMADA, HITOSHI; WATANABE, Mitsuo; Hasegawa, Satoshi; Kamijo, Kenjiro; 山田, 仁; 渡辺, 光男; 長谷川, 敏; 上條, 謙二郎

    1985-01-01

    An experimental investigation was carried out in order to obtain the performance characteristics of a cryogenic pump under a two-phase flow condition. The experiment used an oxygen pump with an inducer and liquid nitrogen as the test fluid. The vapor volumetric fraction at the pump inlet was calculated with an assumption of a constant enthalpy process across an orifice which was used to generate the two-phase flow at the pump inlet. The results showed that the pump head rise did hardly decrea...

  16. Estimation of flow velocity for a debris flow via the two-phase fluid model

    Directory of Open Access Journals (Sweden)

    S. Guo

    2014-06-01

    Full Text Available The two-phase fluid model is applied in this study to calculate the steady velocity of a debris flow along a channel bed. By using the momentum equations of the solid and liquid phases in the debris flow together with an empirical formula to describe the interaction between two phases, the steady velocities of the solid and liquid phases are obtained theoretically. The comparison of those velocities obtained by the proposed method with the observed velocities of two real-world debris flows shows that the proposed method can estimate accurately the velocity for a debris flow.

  17. Characterization of annular two-phase gas-liquid flows in microgravity

    Science.gov (United States)

    Bousman, W. Scott; Mcquillen, John B.

    1994-01-01

    A series of two-phase gas-liquid flow experiments were developed to study annular flows in microgravity using the NASA Lewis Learjet. A test section was built to measure the liquid film thickness around the perimeter of the tube permitting the three dimensional nature of the gas-liquid interface to be observed. A second test section was used to measure the film thickness, pressure drop and wall shear stress in annular microgravity two-phase flows. Three liquids were studied to determine the effects of liquid viscosity and surface tension. The result of this study provide insight into the wave characteristics, pressure drop and droplet entrainment in microgravity annular flows.

  18. Thermal Marangoni Convection of Two-phase Dusty Fluid Flow along a Vertical Wavy Surface

    Directory of Open Access Journals (Sweden)

    S. Siddiqa

    2017-01-01

    Full Text Available The paper considers the influence of thermal Marangoni convection on boundary layer flow of two-phase dusty fluid along a vertical wavy surface. The dimensionless boundary layer equations for two-phase problem are reduced to a convenient form by primitive variable transformations (PVF and then integrated numerically by employing the implicit finite difference method along with the Thomas Algorithm. The effect of thermal Marangoni convection, dusty water and sinusoidal waveform are discussed in detail in terms of local heat transfer rate, skin friction coefficient, velocity and temperature distributions. This investigation reveals the fact that the water-particle mixture reduces the rate of heat transfer, significantly.

  19. Two-dimensional Rarefaction Waves in the High-speed Two-phase Flow

    Science.gov (United States)

    Nakagawa, Masafumi; Harada, Atsushi

    Two-phase flow nozzles are used in the total flow system for geothermal power plants and in the ejector of the refrigerant cycle, etc. One of the most important functions of a two-phase flow nozzle is to convert the thermal energy to the kinetic energy of the two-phase flow. The kinetic energy of the two-phase flow exhausted from a nozzle is available for all applications of this type. There exist the shock waves or rarefaction waves at the outlet of a supersonic nozzle in the case of non-best fitting expansion conditions when the operation conditions of the nozzle are widely chosen. The purpose of the present study is to elucidate theoretically the character of the rarefaction waves at the outlet of the supersonic two-phase flow nozzle. Two-dimensional basic equations for the compressible two-phase flow are introduced considering the inter-phase momentum transfer. Sound velocities are obtained from these equations by using monochromatic wave approximation. Those depend on the relaxation time that determines the momentum transfer. The two-phase flow with large relaxation times has a frozen sound velocity, and with small one has an equilibrium sound velocity. Rarefaction waves which occurred behind the two-phase flow nozzle are calculated by the CIP method. Although the frozen Mach number, below one, controls these basic equations, the rarefaction waves appeared for small relaxation time. The Mach line behind which the expansion starts depends on the inlet velocity and the relaxation time. Those relationships are shown in this paper. The pressure expansion curves are only a function of the revolution angle around the corner of the nozzle outlet for the relaxation time less than 0.1. For the larger relaxation time, the pressure decays because of internal friction caused by inter phase momentum transfer, and the expansion curves are a function of not only the angle but also the flow direction. The calculated expansion curves are compared with the experimental ones

  20. Conceptual design of two-phase fluid mechanics and heat transfer facility for spacelab

    Science.gov (United States)

    North, B. F.; Hill, M. E.

    1980-01-01

    Five specific experiments were analyzed to provide definition of experiments designed to evaluate two phase fluid behavior in low gravity. The conceptual design represents a fluid mechanics and heat transfer facility for a double rack in Spacelab. The five experiments are two phase flow patterns and pressure drop, flow boiling, liquid reorientation, and interface bubble dynamics. Hardware was sized, instrumentation and data recording requirements defined, and the five experiments were installed as an integrated experimental package. Applicable available hardware was selected in the experiment design and total experiment program costs were defined.

  1. On the peculiarities of LDA method in two-phase flows with high concentrations of particles

    Science.gov (United States)

    Poplavski, S. V.; Boiko, V. M.; Nesterov, A. U.

    2016-10-01

    Popular applications of laser Doppler anemometry (LDA) in gas dynamics are reviewed. It is shown that the most popular method cannot be used in supersonic flows and two-phase flows with high concentrations of particles. A new approach to implementation of the known LDA method based on direct spectral analysis, which offers better prospects for such problems, is presented. It is demonstrated that the method is suitable for gas-liquid jets. Owing to the progress in laser engineering, digital recording of spectra, and computer processing of data, the method is implemented at a higher technical level and provides new prospects of diagnostics of high-velocity dense two-phase flows.

  2. Investigation of heat transfer and pressure drop of CO(2) two-phase flow in a horizontal minichannel

    CERN Document Server

    Wu, J; Haug, F; Franke, C; Bremer, J; Eisel, T; Koettig, T

    2011-01-01

    An innovative cooling system based on evaporative CO(2) two-phase flow is under investigation for the tracker detectors upgrade at CERN (European Organization for Nuclear Research). The radiation hardness and the excellent thermodynamic properties emphasize carbon dioxide as a cooling agent in the foreseen minichannels. A circular stainless steel tube in horizontal orientation with an inner diameter of 1.42 mm and a length of 0.3 m has been used as a test section to perform the step-wise scanning of the vapor quality in the entire two-phase region. To characterize the heat transfer and the pressure drop depending on the vapor quality in the tube, measurements have been performed by varying the mass flux from 300 to 600 kg/m(2) s, the heat flux from 7.5 to 29.8 kW/m(2) and the saturation temperature from -40 to 0 degrees C (reduced pressures from 0.136 to 0.472). Heat transfer coefficients between 4 kW/m(2) K and 28 kW/m(2) K and pressure gradients up to 75 kPa/m were registered. The measured data was analyzed...

  3. Numerical simulation on the performance of the vortex pump for transporting solid-liquid two-phase with light particles

    Science.gov (United States)

    Mao, W. Y.; Song, P. Y.; Deng, Q. G.; Xu, H. J.

    2016-05-01

    With the purpose of studying performance of the vortex pump for transporting solid-liquid two-phase with light particles whose relative density smaller than 1, the numerical simulation of solid-liquid two phase flowing in the whole channel of a vortex pump with the particle diameter being 0.5 mm, 1 mm, 2 mm, 3 mm and the initial solid phase volume concentrations being 10%, 20% and 30% are respectively carried out by using the commercial software ANSYS Fluent by adopting RNG κ-ɛ turbulent flow model, Eulerian-Eulerian multi-phase flow model and SIMPLEC algorithm. The simulation results show that in the impeller region, the particles concentrate on the non-working surface of the blades, and the particles are rare on the working surface of the blades. As the initial solid phase volume concentration and particle diameter increase, the pump delivery head of vortex pump decrease. The pump delivery head of vortex pump with different initial solid phase concentrations and different particle diameters are predicted and compared with those obtained by an empirical formula, and they shows good agreement.

  4. Extracting oilseed rape growing regions based on variation characteristics of red edge position%基于红边位置变化特征的油菜种植区域提取

    Institute of Scientific and Technical Information of China (English)

    佘宝; 黄敬峰; 石晶晶; 魏传文

    2013-01-01

    The accurate extraction of oilseed rape growing regions is the premise of growth monitoring, yield estimation and disaster assessment, and remote sensing has been proved to be an effective way for this task. Hyperspectral remote sensing has the features of many more bands, higher spectral resolution, being rich in information and so on, which provides new technical means for extracting oilseed rape growing regions. Changxing, the county with the largest oilseed rape cultivated area in Zhejiang Province was selected to be the study area in this paper, and two EO-1 Hyperion images acquired on April 4th and May 6th, 2004 were adopted, corresponding to the full-bloom stage and pod stage respectively for oilseed rape growing in this region. After detailedly preprocessing of L1R data, the"linear four-point interpolation”method was adopted to get the red edge position (REP) of both stages. REP statistical histograms of typical oilseed rape growing regions and woodland covering both stages were generated and analyzed. The result showed that for both oilseed rape and woodland, the histograms spanning the two stages didn’t have overlaps, and for oilseed rape, the REP value demonstrated an obviously “blue shift” characteristic from April 4th to May 6th. On the contrary, the REP value of woodland demonstrated clearly “red shift” characteristic during the same period, which was distinct from oilseed rape. Ignoring other over wintering crops like winter wheat because of the small amount of planting in Changxing that year, and according to the unique“blue shift”characteristic for oilseed rape from full-bloom stage to pod stage, differing from other vegetations, a “decision tree” was built, containing the algorithms of eliminating non-vegetation areas, non-oilseed rape growing regions, and pseudo-growing regions. Then oilseed rape growing regions were extracted based on this method. Next, the result was verified through 500 random sampling points combined with

  5. 甘肃省大樱桃种植区域划分研究%CLASSIFICATION OF SWEET CHERRY GROWING REGION OF GANSU PROVINCE

    Institute of Scientific and Technical Information of China (English)

    巩垠熙; 巩文; 奚存娃; 罗玉恒; 巩金萍

    2015-01-01

    大樱桃因果期早,营养价值高,经济效益好,成为近年来我国发展最快的果树品种之一.由于大樱桃对气候环境较为敏感,引种栽培又缺乏与气候适宜性相关的研究,以致大樱桃区域性盲目引种栽培现象严重,存在种植不成功、且分散独立、栽植面积小、产量低、品质差、上市集中、市场竞争力差、经济效益低等现象.为了研究大樱桃引种栽培的气候适宜性,文章选择甘肃省东南部大樱桃引种栽培地区作为研究范围,以天水市秦城区气候条件为参照,对比大樱桃欧洲原产地气候条件,选取年平均气温、年降雨量、年日照时数、>10℃的有效积温及无霜期5项典型气候因子,用聚类分析和相似系数法进行定量和定性分析法,将甘肃省大樱桃引种栽培区依次划分为优势区、适宜区、较适宜区、可宜区及不宜区5类,并对各栽植区大樱桃发展策略进行了阐述,提出了主要气候因素间相似系数0.95的引种栽培分界线的建议,为大樱桃的科学引种栽培及规模化发展提供指导.%Because of the earlier fruit maturity,the higher nutrition value and the ideal economic benefit,the sweet cherry has recently become one of the fastest developing fruit varieties in China. However,the cultivation of the sweet cherry is not successful because it can be easily affected by the climate change,and the studies on the climate suitability for the introduction and cultivation are insufficient,there are some problems such as the severely aimless regional introduction and cultivation,the unsuccessful plantation with the scattering distribution and the small plantation area,the lower production ,the poor fruit quality ,the focused marketing ,the weak market com-petition competence and the lower economic benefits. Aiming to study the climate suitability of sweet cherry in the introduction and cultivation areas of the south-east parts of Gansu province,this paper

  6. Comparison of two-phase and three-phase methanol synthesis processes

    NARCIS (Netherlands)

    van de Graaf, G.H; Beenackers, A.A C M

    1996-01-01

    A comparison is made between the ICI (two-phase) methanol synthesis process and a three-phase slurry process based on a multi-stage agitated reactor. The process calculations are based on a complete reactor system consisting of the reactor itself, a recycling system and a gas-liquid separator. The b

  7. Pressure Buildup Analysis for Two-Phase Geothermal Wells: Application to the Baca Geothermal Field

    Science.gov (United States)

    Riney, T. D.; Garg, S. K.

    1985-03-01

    The recently published pressure transient analysis methods for two-phase geothermal wells are employed to analyze the pressure buildup data for several wells located in the Redondo Creek area of the Baca geothermal field in New Mexico. The downhole drilling information and pressure/temperature surveys are first interpreted to locate zones at which fluid enters the well bore from the formation and to estimate the initial reservoir temperature and pressure in these zones. All of the Baca wells considered here induced flashing in the formation upon production. Interpretation of the buildup data for each well considers well bore effects (e.g., phase change in the well bore fluid and location of the pressure sensor with respect to the permeable horizon) and the carbon dioxide content of the fluid and its effects on the phase behavior of the reservoir fluids and differentiates between the single- and two-phase portions of the pressure buildup data. Different straight-line approximations to the two portions (i.e., single- and two-phase) of the data on the Homer plot are used to obtain corresponding estimates for the single- and two-phase mobilities. Estimates for the formation permeability-thickness (kH) product are also given.

  8. Effects of Macroparticle Sizes on Two-phase Mixture Discharge Under DC Voltage

    Institute of Scientific and Technical Information of China (English)

    YAO Wenjun; HE Zhenghao; DENG Heming; WANG Guoli; ZHANG Man; MA Jun; LI Jin; YE Qizheng; HU Hui

    2012-01-01

    The discharge laws of the two-phase mixtures are of significance to the lightning protection and external insulation of HV transmission lines under the influence of severe climatic conditions. The initiation and propagation of discharge and its influence factors are the fundamental problems to be studied.

  9. THE UPWIND OPERATOR SPLITTING FINITE DIFFERENCE METHOD FOR COMPRESSIBLE TWO-PHASE DISPLACEMENT PROBLEM AND ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    袁益让

    2002-01-01

    For compressible two-phase displacement problem, a kind of upwind operator splitting finite difference schemes is put forward and make use of operator splitting, of calculus of variations, multiplicative commutation rule of difference operators, decomposition of high order difference operators and prior estimates are adopted. Optimal order estinates in L2 norm are derived to determine the error in the approximate solution.

  10. Investigation of the overall transient performance of the industrial two-phase closed loop thermosyphon

    NARCIS (Netherlands)

    Vincent, Charles C.J.; Kok, Jacobus B.W.

    1992-01-01

    The two-phase closed loop thermosyphon is investigated with emphasis on the overall performance in transient operation. The control volume approach is the base of a global analysis describing the motion of vapor and liquid phases of the thermosyphon system in one-dimensional equations. Interfacial s

  11. Affinity partitioning of human antibodies in aqueous two-phase systems

    NARCIS (Netherlands)

    Rosa, P. A. J.; Azevedo, A. M.; Ferreira, I. F.; de Vries, J.; Korporaal, R.; Verhoef, H. J.; Visser, T. J.; Aires-Barros, M. R.

    2007-01-01

    The partitioning of human immunoglobulin (IgG) in a polymer-polymer and polymer-salt aqueous two-phase system (ATPS) in the presence of several functionalised polyethylene glycols (PEGs) was studied. As a first approach, the partition studies were performed with pure IgG using systems in which the t

  12. Measurements of solids concentration and axial solids velocity in gas-solid two-phase flows.

    NARCIS (Netherlands)

    Nieuwland, J.J.; Meijer, R.; Kuipers, J.A.M.; Swaaij, van W.P.M.

    1996-01-01

    Several techniques reported in the literature for measuring solids concentration and solids velocity in (dense) gas-solid two-phase flow have been briefly reviewed. An optical measuring system, based on detection of light reflected by the suspended particles, has been developed to measure local soli

  13. A Dual-Stage Two-Phase Model of Selective Attention

    Science.gov (United States)

    Hubner, Ronald; Steinhauser, Marco; Lehle, Carola

    2010-01-01

    The dual-stage two-phase (DSTP) model is introduced as a formal and general model of selective attention that includes both an early and a late stage of stimulus selection. Whereas at the early stage information is selected by perceptual filters whose selectivity is relatively limited, at the late stage stimuli are selected more efficiently on a…

  14. A FINITE ELEMENT COLLOCATION METHOD FOR TWO-PHASE INCOMPRESSIBLE IMMISCIBLE PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    Ma Ning

    2007-01-01

    Two-phase, incompressible, immiscible flow in porous media is governed by a coupled system of nonlinear partial differential equations. The pressure equation is elliptic,whereas the concentration equation is parabolic, and both are treated by the collocation scheme. Existence and uniqueness of solutions of the algorithm are proved. A optimal convergence analysis is given for the method.

  15. Two-phase (bio)catalytic reactions in a table-top centrifugal contact separator

    NARCIS (Netherlands)

    Kraai, Gerard N.; Zwol, Floris van; Schuur, Boelo; Heeres, Hero J.; Vries, Johannes G. de

    2008-01-01

    A new spin on catalysis: A table-top centrifugal contact separator allows for fast continuous two-phase reactions to be performed by intimately mixing two immiscible phases and then separating them. Such a device has been used to produce biodiesel from sunflower oil and MeOH/NaOMe. A lipase-catalyze

  16. Two-Phase Instability Characteristics of Printed Circuit Steam Generator for the Low Pressure Condition

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Han-Ok; Han, Hun Sik; Kim, Young-In; Kim, Keung Koo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Reduction of installation space for steam generators can lead to much smaller reactor vessel with resultant decrease of overall manufacturing cost for the components. A PCHE(Printed Circuit Heat Exchanger) is one of the compact types of heat exchangers available as an alternative to conventional shell and tube heat exchangers. Its name is derived from the procedure used to manufacture the flat metal plates that form the core of the heat exchanger, which is done by chemical milling. These plates are then stacked and diffusion bonded, converting the plates into a solid metal block containing precisely engineered fluid flow passages. PCSG(Printed Circuit Steam Generator) is a potential candidate to be applied to the integral reactor with its compactness and mechanical robustness. For the introduction of new steam generator, design requirement for the two-phase flow instability should be considered. This paper describes two-phase flow instability characteristics of PCSG for the low pressure condition. PCSG is a potential candidate to be applied to the integral reactor with its compactness and mechanical robustness. Interconnecting flow path was developed to mitigate the two-phase flow instability in the cold side. The flow characteristics of two-phase flow instability at the PCSG is examined experimentally in this study.

  17. Comparison of two-phase and three-phase methanol synthesis processes

    NARCIS (Netherlands)

    van de Graaf, G.H; Beenackers, A.A C M

    1996-01-01

    A comparison is made between the ICI (two-phase) methanol synthesis process and a three-phase slurry process based on a multi-stage agitated reactor. The process calculations are based on a complete reactor system consisting of the reactor itself, a recycling system and a gas-liquid separator. The

  18. Effects of gravity and inlet location on a two-phase countercurrent imbibition in porous media

    KAUST Repository

    El-Amin, Mohamed

    2012-01-01

    We introduce a numerical investigation of the effect of gravity on the problem of two-phase countercurrent imbibition in porous media. We consider three cases of inlet location, namely, from, side, top, and bottom. A 2D rectangular domain is considered for numerical simulation. The results indicate that gravity has a significant effect depending on open-boundary location.

  19. A Chebyshev collocation method for solving two-phase flow stability problems

    NARCIS (Netherlands)

    Boomkamp, P.A.M.; Boersma, B.J.; Miesen, R.H.M.; Beijnon, G.V.

    1997-01-01

    This paper describes a Chebyshev collocation method for solving the eigenvalue problem that governs the stability of parallel two-phase flow. The method is based on the expansion of the eigenfunctions in terms of Chebyshev polynomials, point collocation, and the subsequent solution of the resulting

  20. Lamb's integral formulas of two-phase saturated medium for soil dynamic with drainage

    Institute of Scientific and Technical Information of China (English)

    Bo-yang DING; Gai-hong DANG; Jin-hua YUAN

    2010-01-01

    When dynamic force is applied to a saturated porous soil,drainage is common.In this paper,the saturated porous soil with a two-phase saturated medium is simulated,and Lamb's integral formulas with drainage and stress formulas for a two-phase saturated medium are given based on Biot's equation and Betti's theorem(the reciprocal theorem).According to the basic solution to Biot's equation,Green's function Gij and three terms of Green's function G4i,Gi4,and G44 of a two-phase saturated medium subject to a concentrated force on a spherical coordinate are presented.The displacement field with drainage,the magnitude of drainage,and the pore pressure of the center explosion source are obtained in computation.The results of the classical Sharpe's solutions and the solutions of the two-phase saturated medium that decays to a single-phase medium are compared.Good agreement is observed.

  1. Approaches to myosin modelling in a two-phase flow model for cell motility

    Science.gov (United States)

    Kimpton, L. S.; Whiteley, J. P.; Waters, S. L.; Oliver, J. M.

    2016-04-01

    A wide range of biological processes rely on the ability of cells to move through their environment. Mathematical models have been developed to improve our understanding of how cells achieve motion. Here we develop models that explicitly track the cell's distribution of myosin within a two-phase flow framework. Myosin is a small motor protein which is important for contracting the cell's actin cytoskeleton and enabling cell motion. The two phases represent the actin network and the cytosol in the cell. We start from a fairly general description of myosin kinetics, advection and diffusion in the two-phase flow framework, then identify a number of sub-limits of the model that may be relevant in practice, two of which we investigate further via linear stability analyses and numerical simulations. We demonstrate that myosin-driven contraction of the actin network destabilizes a stationary steady state leading to cell motion, but that rapid diffusion of myosin and rapid unbinding of myosin from the actin network are stabilizing. We use numerical simulation to investigate travelling-wave solutions relevant to a steadily gliding cell and we consider a reduction of the model in which the cell adheres strongly to the substrate on which it is crawling. This work demonstrates that a number of existing models for the effect of myosin on cell motility can be understood as different sub-limits of our two-phase flow model.

  2. Theoretical aspects of electrical power generation from two-phase flow streaming potentials

    NARCIS (Netherlands)

    Sherwood, J.D.; Xie, Yanbo; van den Berg, Albert; Eijkel, Jan C.T.

    A theoretical analysis of the generation of electrical streaming currents and electrical power by two-phase flow in a rectangular capillary is presented. The injection of a second, non-conducting fluid phase tends to increase the internal electrical resistance of the electrical generator, thereby

  3. Effects of Particles Collision on Separating Gas–Particle Two-Phase Turbulent Flows

    KAUST Repository

    Sihao, L. V.

    2013-10-10

    A second-order moment two-phase turbulence model incorporating a particle temperature model based on the kinetic theory of granular flow is applied to investigate the effects of particles collision on separating gas–particle two-phase turbulent flows. In this model, the anisotropy of gas and solid phase two-phase Reynolds stresses and their correlation of velocity fluctuation are fully considered using a presented Reynolds stress model and the transport equation of two-phase stress correlation. Experimental measurements (Xu and Zhou in ASME-FED Summer Meeting, San Francisco, Paper FEDSM99-7909, 1999) are used to validate this model, source codes and prediction results. It showed that the particles collision leads to decrease in the intensity of gas and particle vortices and takes a larger effect on particle turbulent fluctuations. The time-averaged velocity, the fluctuation velocity of gas and particle phase considering particles colli-sion are in good agreement with experimental measurements. Particle kinetic energy is always smaller than gas phase due to energy dissipation from particle collision. Moreover, axial– axial and radial–radial fluctuation velocity correlations have stronger anisotropic behaviors. © King Fahd University of Petroleum and Minerals 2013

  4. Two-Phase Flow in Rotating Hele-Shaw Cells with Coriolis Effects

    CERN Document Server

    Escher, Joachim; Walker, Christoph

    2011-01-01

    The free boundary problem of a two phase flow in a rotating Hele-Shaw cell with Coriolis effects is studied. Existence and uniqueness of solutions near spheres is established, and the asymptotic stability and instability of the trivial solution is characterized in dependence on the fluid densities.

  5. Liquid-liquid extraction of enzymes by affinity aqueous two-phase systems

    Directory of Open Access Journals (Sweden)

    Xu Yan

    2003-12-01

    Full Text Available From analytical to commercial scale, aqueous two-phase systems have their application in the purification, characterization and study of biomaterials. In order to improve the selectivity of the systems, the biospecific affinity ligands were introduced. In the affinity partitioning aqueous two-phase system, have many enzymes been purified. This review discusses the partitioning of some enzymes in the affinity aqueous two-phase systems in regard to the different ligands, including reactive dyes, metal ions and other ligands. Some integration of aqueous two-phase system with other techniques for more effective purification of enzymes are also presented.Tanto em escala de laboratório como industrial, os sistemas de duas fases aquosas podem ser utilizados para a purificação, caracterização e estudos de biomateriais. Para aumentar a seletividade desse sistema, ligantes de afinidade bioespecíficos podem ser utilizados. No sistema de duas fases aquosas por afinidade, muitas enzimas podem ser purificadas. Neste artigo de revisão, a partição de algumas enzimas por esse tipo de afinidade, utilizando diferentes ligantes como corantes e íons metálicos, são discutidas. Além disso, a integração desse sistema de duas fases aquosas com outras técnicas de purificação estão sendo apresentados, com o objetivo mostrar a melhoria da eficiência do processo.

  6. Two-phase (bio)catalytic reactions in a table-top centrifugal contact separator

    NARCIS (Netherlands)

    Kraai, Gerard N.; Zwol, Floris van; Schuur, Boelo; Heeres, Hero J.; Vries, Johannes G. de

    2008-01-01

    A new spin on catalysis: A table-top centrifugal contact separator allows for fast continuous two-phase reactions to be performed by intimately mixing two immiscible phases and then separating them. Such a device has been used to produce biodiesel from sunflower oil and MeOH/NaOMe. A lipase-catalyze

  7. Process Intensification. Continuous Two-Phase Catalytic Reactions in a Table-Top Centrifugal Contact Separator

    NARCIS (Netherlands)

    Kraai, Gerard N.; Schuur, Boelo; van Zwol, Floris; Haak, Robert M.; Minnaard, Adriaan J.; Feringa, Ben L.; Heeres, Hero J.; de Vries, Johannes G.; Prunier, ML

    2009-01-01

    Production of fine chemicals is mostly performed in batch reactors. Use of continuous processes has many advantages which may reduce the cost of production. We have developed the use of centrifugal contact separators (CCSs) for continuous two-phase catalytic reactions. This equipment has previously

  8. Visualization and research of gas-liquid two phase flow structures in cylindrical channel

    Directory of Open Access Journals (Sweden)

    Stefański Sebastian

    2017-01-01

    Full Text Available Two-phase flows are commonly found in many industries, especially in systems, where efficient and correct functioning depend on specific values of flow parameters. In thermal engineering and chemical technology the most popular types of two-phase mixture are gas-liquid or liquid-vapour mixtures. Bubbles can create in flow different structures and determine diverse properties of flow (velocity of phase, void fraction, fluctuations of pressure, pipe vibrations, etc.. That type of flow is difficult to observe, especially in liquid-vapour mixture, where vapour is being made by heating the medium. Production of vapour and nucleation process are very complicated issues, which are important part of two-phase flow phenomenon. Gas-liquid flow structures were observed and described with figures, but type of structure depends on many parameters. Authors of this paper made an attempt to simulate gas-liquid flow with air and water. In the paper there was presented specific test stand built to observe two-phase flow structures, methodology of experiment and conditions which were maintained during observation. The paper presents also the structures which were observed and the analysis of results with reference to theoretical models and diagrams available in literature.

  9. Numerical Simulation of Hydrodynamic Wave Loading by a Compressible Two-Phase Model

    NARCIS (Netherlands)

    Wemmenhove, R.; Loots, G.E.; Veldman, A.E.P.

    2006-01-01

    The numerical simulation of hydrodynamic wave loading on different types of offshore structures is important to predict forces on and water motion around these structures. This paper presents a numerical study of the effects of two-phase flow on an offshore structure subject to breaking waves. The

  10. Lattice-Boltzmann-based two-phase thermal model for simulating phase change

    NARCIS (Netherlands)

    Kamali, M.R.; Gillissen, J.J.J.; Van den Akker, H.E.A.; Sundaresan, S.

    2013-01-01

    A lattice Boltzmann (LB) method is presented for solving the energy conservation equation in two phases when the phase change effects are included in the model. This approach employs multiple distribution functions, one for a pseudotemperature scalar variable and the rest for the various species. A

  11. An ALE Finite Element Approach for Two-Phase Flow with Phase Change

    Science.gov (United States)

    Gros, Erik; Anjos, Gustavo; Thome, John; Ltcm Team; Gesar Team

    2016-11-01

    In this work, two-phase flow with phase change is investigated through the Finite Element Method (FEM) in the Arbitrary Lagrangian-Eulerian (ALE) framework. The equations are discretized on an unstructured mesh where the interface between the phases is explicitly defined as a sub-set of the mesh. The two-phase interface position is described by a set of interconnected nodes which ensures a sharp representation of the boundary, including the role of the surface tension. The methodology proposed for computing the curvature leads to very accurate results with moderate programming effort and computational costs. Such a methodology can be employed to study accurately many two-phase flow and heat transfer problems in industry such as oil extraction and refinement, design of refrigeration systems, modelling of microfluidic and biological systems and efficient cooling of electronics for computational purposes. The latter is the principal aim of the present research. The numerical results are discussed and compared to analytical solutions and reference results, thereby revealing the capability of the proposed methodology as a platform for the study of two-phase flow with phase change.

  12. Nonequilibrium capillarity effects in two-phase flow through porous media at different scales

    NARCIS (Netherlands)

    Bottero, S.; Hassanizadeh, S.M.; Kleingeld, P.J.; Heimovaara, T.J.

    2011-01-01

    A series of primary drainage experiments was carried out in order to investigate nonequilibrium capillarity effects in two-phase flow through porous media. Experiments were performed with tetrachloroethylene (PCE) and water as immiscible fluids in a sand column 21 cm long. Four drainage experiments

  13. Trapping and hysteresis in two-phase flow in porous media: A pore-network study

    NARCIS (Netherlands)

    Joekar-Niasar, V.|info:eu-repo/dai/nl/30484229X; Doster, F.; Armstrong, R.T.; Wildenschild, D.; Celia, M.A.

    2013-01-01

    Several models for two-phase flow in porous media identify trapping and connectivityof fluids as an important contribution to macroscale hysteresis. This is especially true forhysteresis in relative permeabilities. The trapping models propose trajectories from theinitial saturation to the end saturati

  14. An experimental investigation on the evaporation and condensation heat transfer of two-phase closed thermosyphons

    NARCIS (Netherlands)

    Jafari, Davoud; Di Marco, Paolo; Filippeschi, Sauro; Franco, Alessandro

    2017-01-01

    Abstract Two-phase closed thermosyphons (TPCTs) are excellent thermal transfer devices that their integration into heat exchangers has been shown a strong potential for energy savings. The scope of this study is an experimental evaluation of the evaporation and condensation heat transfer of a TPCT

  15. Effects of a two-phase oil-water mouthwash on halitosis.

    Science.gov (United States)

    Yaegaki, K; Sanada, K

    1992-01-01

    Many oral microorganisms possess hydrophobic outer surfaces. A two-phase, oil-water mouthwash has, therefore, recently been developed to remove such oral microorganisms. The oil phase consists of olive oil and other essential oils. The aqueous phase includes cetylpyridinium chloride, which is a disinfectant that promotes the adhesion of microorganisms to oil droplets. This study determined the effects of this mouthwash on the production of volatile sulfide in vivo and in vitro. Neither rinsing with water nor brushing teeth decreased the concentration of sulfide in mouth air at 3.5 h after treatment. A reduction of only 30% of sulfide was observed when a commercial mouthwash was used. However, this study demonstrated that use of the two-phase mouthwash led to approximately 80% reduction of sulfide. Furthermore, volatile sulfide and 2-ketobutyrate productions from methionine in a saliva putrefaction system were completely inhibited by the two-phase mouthwash; and consumption of methionine was decreased by 65 percent. It is concluded that the two-phase mouthwash strongly inhibits the production of volatile sulfide.

  16. Gravity Effect on Two-Phase Immiscible Flows in Communicating Layered Reservoirs

    DEFF Research Database (Denmark)

    Zhang, Xuan; Shapiro, Alexander; Stenby, Erling Halfdan

    2012-01-01

    An upscaling method is developed for two-phase immiscible incompressible flows in layered reservoirs with good communication between the layers. It takes the effect of gravity into consideration. Waterflooding of petroleum reservoirs is used as a basic example for application of this method...... for gravity segregation. The effects of gravity are analyzed....

  17. Generating a Two-Phase Lesson for Guiding Beginners to Learn Basic Dance Movements

    Science.gov (United States)

    Yang, Yang; Leung, Howard; Yue, Lihua; Deng, Liqun

    2013-01-01

    In this paper, an automated lesson generation system for guiding beginners to learn basic dance movements is proposed. It analyzes the dance to generate a two-phase lesson which can provide a suitable cognitive load thus offering an efficient learning experience. In the first phase, the dance is divided into small pieces which are patterns, and…

  18. Forced Two-Phase Helium Cooling Scheme for the Mu2e Transport Solenoid

    Energy Technology Data Exchange (ETDEWEB)

    Tatkowski, G. [Fermilab; Cheban, S. [Fermilab; Dhanaraj, N. [Fermilab; Evbota, D. [Fermilab; Lopes, M. [Fermilab; Nicol, T. [Fermilab; Sanders, R. [Fermilab; Schmitt, R. [Fermilab; Voirin, E. [Fermilab

    2015-01-01

    The Mu2e Transport Solenoid (TS) is an S-shaped magnet formed by two separate but similar magnets, TS-u and TS-d. Each magnet is quarter-toroid shaped with a centerline radius of approximately 3 m utilizing a helium cooling loop consisting of 25 to 27 horizontal-axis rings connected in series. This cooling loop configuration has been deemed adequate for cooling via forced single phase liquid helium; however it presents major challenges to forced two-phase flow such as “garden hose” pressure drop, concerns of flow separation from tube walls, difficulty of calculation, etc. Even with these disadvantages, forced two-phase flow has certain inherent advantages which make it a more attractive option than forced single phase flow. It is for this reason that the use of forced two-phase flow was studied for the TS magnets. This paper will describe the analysis using helium-specific pressure drop correlations, conservative engineering approach, helium properties calculated and updated at over fifty points, and how the results compared with those in literature. Based on the findings, the use of forced-two phase helium is determined to be feasible for steady-state cooling of the TS solenoids

  19. THE LINEAR HOMOGENEOUS FLOW MODEL FOR TWO-PHASE FLOW INSTABILITY IN BOILING CHANNELS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper presents liner homogeneous model describing two-phase flow instability. Dimensionless parameter η was derived by using the linear homogeneous model. Using parameter η the stability of a system could be easily judged. The calculated results agree with the experimental data well.

  20. Extraction of peptide tagged cutinase in detergent-based aqueous two-phase systems

    NARCIS (Netherlands)

    Rodenbrock, A.; Selber, K.; Egmond, M.R.; Kula, M.-R.

    2010-01-01

    Detergent-based aqueous two-phase systems have the advantage to require only one auxiliary chemical to induce phase separation above the cloud point. In a systematic study the efficiency of tryptophan-rich peptide tags was investigated to enhance the partitioning of an enzyme to the detergent-rich p

  1. Effects of Gravity and Inlet Location on a Two-Phase Countercurrent Imbibition in Porous Media

    Directory of Open Access Journals (Sweden)

    M. F. El-Amin

    2012-01-01

    Full Text Available We introduce a numerical investigation of the effect of gravity on the problem of two-phase countercurrent imbibition in porous media. We consider three cases of inlet location, namely, from, side, top, and bottom. A 2D rectangular domain is considered for numerical simulation. The results indicate that gravity has a significant effect depending on open-boundary location.

  2. Model description of bactrial 3-methylcatechol production in one- and two-phase systems

    NARCIS (Netherlands)

    Husken, L.E.; Hoogakker, J.; Bont, de J.A.M.; Tramper, J.; Beeftink, H.H.

    2003-01-01

    Pseudomonas putida MC2 produces 3-methylcatechol from toluene in aqueous medium. A second phase of 1-octanol may improve total product accumulation. To optimise the design of such a biphasic process, a process model was developed, both for one- and two-phase applications. The insights obtained by th

  3. Multi-scale symbolic time reverse analysis of gas-liquid two-phase flow structures

    Science.gov (United States)

    Wang, Hongmei; Zhai, Lusheng; Jin, Ningde; Wang, Youchen

    Gas-liquid two-phase flows are widely encountered in production processes of petroleum and chemical industry. Understanding the dynamic characteristics of multi-scale gas-liquid two-phase flow structures is of great significance for the optimization of production process and the measurement of flow parameters. In this paper, we propose a method of multi-scale symbolic time reverse (MSTR) analysis for gas-liquid two-phase flows. First, through extracting four time reverse asymmetry measures (TRAMs), i.e. Euclidean distance, difference entropy, percentage of constant words and percentage of reversible words, the time reverse asymmetry (TRA) behaviors of typical nonlinear systems are investigated from the perspective of multi-scale analysis, and the results show that the TRAMs are sensitive to the changing of dynamic characteristics underlying the complex nonlinear systems. Then, the MSTR analysis is used to study the conductance signals from gas-liquid two-phase flows. It is found that the multi-scale TRA analysis can effectively reveal the multi-scale structure characteristics and nonlinear evolution properties of the flow structures.

  4. Milking microalga Dunaliella salina for Beta-carotene production in two-phase bioreactors

    NARCIS (Netherlands)

    Hejazi, M.; Holwerda, E.; Wijffels, R.H.

    2004-01-01

    A new method was developed for production of beta-carotene from Dunaliella salina. Cells were grown in low light intensity and then transferred to a production bioreactor illuminated at a higher light intensity. It was a two-phase bioreactor consisting of an aqueous and a biocompatible organic phase

  5. Lattice-Boltzmann-based two-phase thermal model for simulating phase change

    NARCIS (Netherlands)

    Kamali, M.R.; Gillissen, J.J.J.; Van den Akker, H.E.A.; Sundaresan, S.

    2013-01-01

    A lattice Boltzmann (LB) method is presented for solving the energy conservation equation in two phases when the phase change effects are included in the model. This approach employs multiple distribution functions, one for a pseudotemperature scalar variable and the rest for the various species. A

  6. Generating a Two-Phase Lesson for Guiding Beginners to Learn Basic Dance Movements

    Science.gov (United States)

    Yang, Yang; Leung, Howard; Yue, Lihua; Deng, Liqun

    2013-01-01

    In this paper, an automated lesson generation system for guiding beginners to learn basic dance movements is proposed. It analyzes the dance to generate a two-phase lesson which can provide a suitable cognitive load thus offering an efficient learning experience. In the first phase, the dance is divided into small pieces which are patterns, and…

  7. Well logging interpretation of production profile in horizontal oil-water two phase flow pipes

    Science.gov (United States)

    Zhai, Lu-Sheng; Jin, Ning-De; Gao, Zhong-Ke; Zheng, Xi-Ke

    2012-03-01

    Due to the complicated distribution of local velocity and local phase hold up along the radial direction of pipe in horizontal oil-water two phase flow, it is difficult to measure the total flow rate and phase volume fraction. In this study, we carried out dynamic experiment in horizontal oil-water two phases flow simulation well by using combination measurement system including turbine flowmeter with petal type concentrating diverter, conductance sensor and flowpassing capacitance sensor. According to the response resolution ability of the conductance and capacitance sensor in different range of total flow rate and water-cut, we use drift flux model and statistical model to predict the partial phase flow rate, respectively. The results indicate that the variable coefficient drift flux model can self-adaptively tone the model parameter according to the oil-water two phase flow characteristic, and the prediction result of partial phase flow rate of oil-water two phase flow is of high accuracy.

  8. 23 CFR 636.202 - When are two-phase design-build selection procedures appropriate?

    Science.gov (United States)

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false When are two-phase design-build selection procedures appropriate? 636.202 Section 636.202 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS DESIGN-BUILD CONTRACTING Selection Procedures, Award Criteria §...

  9. Experimental study on two-phase flow pressure drop in small diameter bends

    Directory of Open Access Journals (Sweden)

    A.T. Autee

    2016-09-01

    Full Text Available Measurement of two-phase flow pressure drop and its prediction across curved tubes and bends is important for the enhancement of the performance and safety of the heat exchangers and flow transmitting devices. The comparative study of some of the available two-phase pressure drop correlations reveals that the predicted values of pressure drops by these leading methods may differ by large. The applicability of these correlations to the small diameter tubes of range 4.0–8.0 mm and different bend angles of the range 90–180° is not fully established. The basic objective of the present experimental investigation is to generate the experimental data to develop the unified correlation applicable for the small diameter tubes of range 4.0–8.0 mm and different bend angles of the range 90–180°. Hence, experimental facility was developed to conduct the experiments to generate the data and to assess the predictive capability of some of the available two-phase pressure drop correlations. It was observed that the correlations considered for comparisons were unable to satisfactorily predict the measured experimental data within the ±50% error bands. A new correlation is developed in terms of curvature multiplier to the straight tube two-phase pressure drop. The correlation is validated with the present measured experimental data. The statistical analysis suggests that correlation shows satisfactory results.

  10. A two phase algorithm for solving a class of hard satissfiability problems

    NARCIS (Netherlands)

    J.P. Warners; H. van Maaren

    1998-01-01

    textabstractThe DIMACS suite of satisfiability (SAT) benchmarks contains a set of instances that are very hard for existing algorithms. These instances arise from learning the parity function on 32 bits. In this paper we develop a two phase algorithm that is capable of solving these instances. In

  11. Two-phase flow-induced forces on bends in small scale tubes

    NARCIS (Netherlands)

    Cargnelutti, M.F.; Belfroid, S.P.C.; Schiferli, W.

    2010-01-01

    Two-phase flow occurs in many situations in industry. Under certain circumstances, it can be a source of flow-induced vibrations. The forces generated can be sufficiently large to affect the performance or efficiency of an industrial device. In the worst-case scenario, the mechanical forces that ari

  12. Implementation of the interfacial area transport equation in trace for boiling two-phase flows

    Science.gov (United States)

    Bernard, Matthew S.

    Correctly predicting the interfacial area concentration (a i) is vital to the overall accuracy of the two-fluid model because ai describes the amount of surface area that exists between the two-phases, and is therefore directly related to interfacial mass, momentum and energy transfer. The conventional method for specifying ai in the two-fluid model is through flow regime-based empirical correlations coupled with regime transition criteria. However, a more physically consistent approach to predicting ai is through the interfacial area transport equation (IATE), which can address the deficiencies of the flow regime-based approach. Some previous studies have been performed to demonstrate the feasibility of IATE in developmental versions of the nuclear reactor systems analysis code, TRACE. However, a full TRACE version capable of predicting boiling two-phase flows with the IATE has not been established. Therefore, the current work develops a version of TRACE that is capable of predicting boiling two-phase flows using the IATE. The development is carried out in stages. First, a version of TRACE which employs the two-group IATE for adiabatic, vertical upward, air-water conditions is developed. An in-depth assessment on the existing experimental database is performed to select reliable experimental data for code assessment. Then, the implementation is assessed against the qualified air-water two-phase flow experimental data. Good agreement is observed between the experimental data for ai and the TRACE code with an average error of +/-9% for all conditions. Following the initial development, one-group IATE models for vertical downward and horizontal two-phase flows are implemented and assessed against qualified data. Finally, IATE models capable of predicting subcooled boiling two-phase flows are implemented. An assessment of the models shows that TRACE is capable of generating ai in subcooled boiling two-phase flows with the IATE and that heat transfer effects dominate

  13. Comparison of Experimental and Numerical Two-Phase Flows in a Porous Micro-Model

    Directory of Open Access Journals (Sweden)

    Dustin Crandall

    2009-12-01

    Full Text Available Characterizing two-phase flow in porous media is important to provide estimates of sweep efficiency in enhanced oil recovery and storage estimates in potential geological CO2 sequestration repositories. To further the current understanding of two-phase flow in porous media a micro-model of interconnected channels was designed and fabricated using stereolithography to experimentally study gas-liquid flows. This flowcell was created with a wide variability of throat dimensions to represent naturally occurring porous media. Low flow rate experiments of immiscible two-phase drainage were performed within this cell. Additionally, a computational model for analyzing two-phase flows in the same flowcell was developed and used to simulate conditions not possible with our laboratory settings. The computational model was first tested for the identical conditions used in the experimental studies, and was shown to be in good agreement with the experimentally determined fractal dimension of the invading gas structure, time until breakthrough, and fluid saturation. The numerical model was then used to study two-phase air-water flows in flowcells with the same geometry and different gas-liquid-solid contact angles. The percent saturation of air and the motion of the fluids through the cell were found to vary with changes in these parameters. Finally, to simulate flows expected during geologic carbon sequestration, the fluid properties and interface conditions were set to model the flow of CO2 into a brine-saturated porous medium at representative subsurface conditions. The CO2 flows were shown to have larger gas saturations than the previous air into water studies. Thus the accuracy of the computational model was supported by the flowcell experiments, and the computational model extended the laboratory results to conditions not possible with the apparatus used in the experiments.

  14. Two-phase flow and boiling heat transfer in two vertical narrow annuli

    Energy Technology Data Exchange (ETDEWEB)

    Peng Changhong [Department of Nuclear and Thermal Power Engineering, Xi' an Jiaotong University, Xian 710049 (China)]. E-mail: pxm321@163.com; Guo Yun [Department of Nuclear and Thermal Power Engineering, Xi' an Jiaotong University, Xian 710049 (China); Qiu Suizheng [Department of Nuclear and Thermal Power Engineering, Xi' an Jiaotong University, Xian 710049 (China); Jia Dounan [Department of Nuclear and Thermal Power Engineering, Xi' an Jiaotong University, Xian 710049 (China); Nie Changhua [Nuclear Power Institute of China, Chengdu 610041 (China)

    2005-07-01

    Experimental study associated with two-phase flow and heat transfer during flow boiling in two vertical narrow annuli has been conducted. The parameters examined were: mass flux from 38.8 to 163.1 kg/m{sup 2} s; heat flux from 4.9 to 50.7 kW/m{sup 2} for inside tube and from 4.2 to 78.8 kW/m{sup 2} for outside tube; equilibrium mass quality from 0.02 to 0.88; system pressure from 1.5 to 6.0 MPa. It was found that the boiling heat transfer was strongly influenced by heat flux, while the effect of mass velocity and mass quality were not very significant. This suggested that the boiling heat transfer was mainly via nucleate boiling. The data were used to develop a new correlation for boiling heat transfer in the narrow annuli. In the two-phase flow study, the comparison with the correlation of Chisholm [Chisholm, D., 1967. A theoretical basis for the Lockhart-Martinelli correlation for two-phase flow. Int. J. Heat Mass Transfer 10, 1767-1778] and Mishima and Hibiki [Mishima, K., Hibiki, T., 1996. Some characteristics of air-water two-phase flow in small diameter vertical tubes. Int. J. Multiphase Flow 22, 703-712] indicated that the existing correlations could not predict the two-phase multiplier in the narrow annuli well. Based on the experimental data, a new correlation was developed.

  15. Robust risk prediction with biomarkers under two-phase stratified cohort design.

    Science.gov (United States)

    Payne, Rebecca; Yang, Ming; Zheng, Yingye; Jensen, Majken K; Cai, Tianxi

    2016-12-01

    Identification of novel biomarkers for risk prediction is important for disease prevention and optimal treatment selection. However, studies aiming to discover which biomarkers are useful for risk prediction often require the use of stored biological samples from large assembled cohorts, and thus the depletion of a finite and precious resource. To make efficient use of such stored samples, two-phase sampling designs are often adopted as resource-efficient sampling strategies, especially when the outcome of interest is rare. Existing methods for analyzing data from two-phase studies focus primarily on single marker analysis or fitting the Cox regression model to combine information from multiple markers. However, the Cox model may not fit the data well. Under model misspecification, the composite score derived from the Cox model may not perform well in predicting the outcome. Under a general two-phase stratified cohort sampling design, we present a novel approach to combining multiple markers to optimize prediction by fitting a flexible nonparametric transformation model. Using inverse probability weighting to account for the outcome-dependent sampling, we propose to estimate the model parameters by maximizing an objective function which can be interpreted as a weighted C-statistic for survival outcomes. Regardless of model adequacy, the proposed procedure yields a sensible composite risk score for prediction. A major obstacle for making inference under two phase studies is due to the correlation induced by the finite population sampling, which prevents standard inference procedures such as the bootstrap from being used for variance estimation. We propose a resampling procedure to derive valid confidence intervals for the model parameters and the C-statistic accuracy measure. We illustrate the new methods with simulation studies and an analysis of a two-phase study of high-density lipoprotein cholesterol (HDL-C) subtypes for predicting the risk of coronary heart

  16. Biomass, Carbon and Nitrogen Distribution in Living Woody Plant Parts of Robinia pseudoacacia L. Growing on Reclamation Sites in the Mining Region of Lower Lusatia (Northeast Germany

    Directory of Open Access Journals (Sweden)

    Ansgar Quinkenstein

    2012-01-01

    Full Text Available In the lignite mining region of Lower Lusatia (NE-Germany, Robinia pseudoacacia L. is an increasingly popular tree for the biomass production with short rotation coppices (SRCs on reclamation sites. In order to evaluate biomass production, C and N allocation patterns in R. pseudoacacia stands between shoot, stump, coarse, and fine roots samples were collected from seedlings and three adjacent plantations and plants that were one, two and twelve years old. Results indicated that the summarized average dry matter production (DM of the woody plant parts increased with plant age up to 7.45 t DM ha−1 yr−1 with a corresponding shoot increment of up to 4.77 t DM ha−1 yr−1 in the twelve-year-old stands. The shoot to root ratio changed from 0.2 for the one-year-old trees to 2.0 in the twelve-year-old plantation, whereby an average amount of 3.4 t C ha−1 yr−1 and 0.1 t N ha−1 yr−1 was annually bound in the living woody plant parts over the period of twelve years. Summing up, the results suggest a high potential for C and N storage of R. pseudoacacia what is also beneficial for land reclamation due to positive implications on soil humus and general site fertility.

  17. 基于WheatGrow和CERES模型的区域小麦生育期预测与评价%Regional Prediction and Evaluation of Wheat Phenology Based on the WheatGrow and CERES Models

    Institute of Scientific and Technical Information of China (English)

    吕尊富; 刘小军; 汤亮; 刘蕾蕾; 曹卫星; 朱艳

    2013-01-01

    [Objective] The objectives of this study are to investigate the key techniques of wheat phenological model for regional application,and to evaluate the validity of regional application techniques through analyzing the simulated phenology results of WheatGrow and CERES-Wheat at regional scale.[Method] First,the daily meteorological data at different weather stations were interpolated using the method of Thin Plate Spline (TPS),and the gridded daily meteorological surface data was generated.Then,the historical sowing dates of wheat at different stations were interpolated using TPS method,and the multi-year average values of interpolated results were generated as regional sowing date surface data.In addition,by integrating the Markov Chain Monte Carlo (MCMC) method with the above two wheat models,the region-specific cultivar parameters were estimated with the measured phenology data from 1998 to 2003,and were taken as the typical cultivar parameters of each province.Finally,the regional daily meteorological data,sowing surface data and region-specific cultivar parameters were input into the above two models,which took grid as basic unit to simulate regional wheat phenology.Meanwhile,the simulated results were evaluated with observed data and the uncertainty coming from cultivar parameters was quantified at site and regional scales.[Result] The estimated values from the above two models agreed well with the observed values at regional scale.R2 between estimated and observed values of jointing date,heading date and maturity date were 0.85,0.87 and 0.86 (WheatGrow),0.87,0.85 and 0.82 (CERES),respectively.RMSE between the estimated and observed values of jointing date,heading date and maturity date were 9.6,7.2 and 6.3 d (WheatGrow),9.4,7.8 and 6.6 d (CERES),respectively.By analyzing the simulated results of the two models at regional scale,the WheatGrow model had higher prediction accuracy than CERES-Wheat,while the uncertainty came from crop parameters were also higher

  18. An Ambition to Grow

    OpenAIRE

    Ron Kemp; R Hakkert

    2006-01-01

    This report tries to gain insight in the willingness or ambition to grow of a small business owner. The main question of this report is therefore: Which factors influence the ambition to grow a business? To examine the ambition to grow an economic and a psychological perspective is given in this study.

  19. Growing Pains (For Parents)

    Science.gov (United States)

    ... Month-Old Feeding Your 1- to 2-Year-Old Growing Pains KidsHealth > For Parents > Growing Pains Print A ... olds and, later, in 8- to 12-year-olds. Signs and Symptoms Growing pains always concentrate in the muscles , rather than ...

  20. Comparison of phenology models for predicting the onset of growing season over the Northern Hemisphere.

    Science.gov (United States)

    Fu, Yang; Zhang, Haicheng; Dong, Wenjie; Yuan, Wenping

    2014-01-01

    Vegetation phenology models are important for examining the impact of climate change on the length of the growing season and carbon cycles in terrestrial ecosystems. However, large uncertainties in present phenology models make accurate assessment of the beginning of the growing season (BGS) a challenge. In this study, based on the satellite-based phenology product (i.e. the V005 MODIS Land Cover Dynamics (MCD12Q2) product), we calibrated four phenology models, compared their relative strength to predict vegetation phenology; and assessed the spatial pattern and interannual variability of BGS in the Northern Hemisphere. The results indicated that parameter calibration significantly influences the models' accuracy. All models showed good performance in cool regions but poor performance in warm regions. On average, they explained about 67% (the Growing Degree Day model), 79% (the Biome-BGC phenology model), 73% (the Number of Growing Days model) and 68% (the Number of Chilling Days-Growing Degree Day model) of the BGS variations over the Northern Hemisphere. There were substantial differences in BGS simulations among the four phenology models. Overall, the Biome-BGC phenology model performed best in predicting the BGS, and showed low biases in most boreal and cool regions. Compared with the other three models, the two-phase phenology model (NCD-GDD) showed the lowest correlation and largest biases with the MODIS phenology product, although it could catch the interannual variations well for some vegetation types. Our study highlights the need for further improvements by integrating the effects of water availability, especially for plants growing in low latitudes, and the physiological adaptation of plants into phenology models.