Reintroduction of captive-bred animals into suitable habitats is an important technique for the long-term conservation and recovery of populations of endangered species in fragmented landscapes.Inbreeding depression i...Reintroduction of captive-bred animals into suitable habitats is an important technique for the long-term conservation and recovery of populations of endangered species in fragmented landscapes.Inbreeding depression is an inherent risk when using captive populations for reintroduction programs and needs to be carefully assessed prior to reintroduction.In this study,we evaluated inbreeding levels within a captive breeding program and one remnant wild population of Cabot's Tragopan (Tragopan caboti),an endangered pheasant species endemic to China,for which reintroduction is now an essential conservation strategy for long-term population persistence.Fifteen highly polymorphic microsatellite loci were developed to genotype individuals.Inbreeding coefficients (FIS) reveal that there is no evidence of inbreeding within the Tragopan Breeding Center of Beijing Normal University (TBCBNU) captive population and the remnant population from the Wuyi-Yandang Mountains.Diversity of origin,large founder population size and a rational breeding strategy are the most critical factors preventing inbreeding depression within the TBCBNU captive population.We suggest that the TBCBNU population is a suitable candidate stock for T.caboti reintroduction programs and that there is an urgent need to better coordinate and strengthen reproduction management of captive T.caboti populations to sustain the long-term ex situ conservation of the species.展开更多
[Objective] This study aimed to screen a set of SSR core primers suitable for purity identification of pepper (Capsicum) hybrids. [Method] DNA fingerprint of 100 pepper hybrids was analyzed using 17 SSR primers. [Re...[Objective] This study aimed to screen a set of SSR core primers suitable for purity identification of pepper (Capsicum) hybrids. [Method] DNA fingerprint of 100 pepper hybrids was analyzed using 17 SSR primers. [Result] According to the polymorphism and heterozygosity, Hpms1-214, Es395 and Hpmsl-5 were determined as three preferred core primers for purity identification of pepper hybrids. By using these three preferred core primers, 97 pepper hybrids (accounting for 97%) had heterozygous band pattern with at least one primer. Es330, Es363, Epms923, Es120 and Es64 were determined as candidate core primers for purity identification of pepper hybrids. Specific primers of 14 varieties were obtained, which could be used to further screen parent-complementary primers of each pepper hybrid. [Con- clusion] This study laid the foundation for constructing standard DNA fingerprints for purity identification of pepper hybrids.展开更多
Cities separated in space are connected together by spatial interaction (SI) between them. But the studies focusing on the SI are relatively few in China mainly because of the scarcity of data. This paper deals with t...Cities separated in space are connected together by spatial interaction (SI) between them. But the studies focusing on the SI are relatively few in China mainly because of the scarcity of data. This paper deals with the SI in terms of rail passenger flows, which is an important aspect of the network structure of urban agglomeration. By using a data set consisting of rail O-D (origin-destination) passenger flows among nearly 200 cities, intercity rail distance O-D matrixes, and some other indices, it is found that the attenuating tendency of rail passenger is obvious. And by the analysis on dominant flows and spatial structure of flows, we find that passenger flows have a trend of polarizing to hubs while the linkages between hubs upgrade. However, the gravity model reveals an overall picture of convergence process over time which is not in our expectation of integration process in the framework of globalization and economic integration. Some driven factors for the re-organization process of the structure of urban agglomeration, such as technique advance, globalization, etc. are discussed further based on the results we obtained.展开更多
Various regulations, aimed at the protection of human beings and electrical equipment against possible adverse effects resulting from exposure to electromagnetic fields, have been issued in many countries. Most of the...Various regulations, aimed at the protection of human beings and electrical equipment against possible adverse effects resulting from exposure to electromagnetic fields, have been issued in many countries. Most of them are based on safety guidelines published by international expert groups. In this paper, electric and magnetic fields are calculated in the vicinity of 25 kV traction line supplying railway traction systems. Calculation results are compared to exposure limits specified by safety guidelines and regulations. Possible countermeasures for reduction of electromagnetic fields are proposed. Also, this paper presents a method for calculation of the induced voltages to an underground gas pipeline from a neighbouring 25 kV electric traction overhead line in case of short circuit. Calculations are performed with EMTP-ATP software. Possible countermeasures for reduction of induced voltages are proposed.展开更多
Different results of seed purity identification for Gangyou 158, Ⅱ You 808, Wuyou 308 and Tianfengyou 316 were obtained using different SSR primers in our early work. To find out the reasons, the four hybrid combinat...Different results of seed purity identification for Gangyou 158, Ⅱ You 808, Wuyou 308 and Tianfengyou 316 were obtained using different SSR primers in our early work. To find out the reasons, the four hybrid combinations were grown in field to identify their purity according to their phenotypic traits. Then, the results of field identification were compared with that of laboratory tests using different SSR primers. The comparison revealed that only sterile lines (female parent) were distin- guished from true hybrids using the primers RM208, RM264, RM242 and RM164 for the purity identification of Gangyou 158, II You 808, Wuyou 308 and Tianfengyou 316, so the results were higher than that of field identification. In contrast, the primers RM341, RM297, RM21 and RM110 were able to distinguish not only the sterile plants but also the cross-pollinated ones from the true hybrids of Gangyou 158,Ⅱ You 808, Wuyou 308 and Tianfengyou 316, and the results of purity identifi- cation using them were close that of field identification, in summary, several pairs of primers should be used for the purity identification of rice hybrids to distinguish all the off-type plants and thus improve the accuracy.展开更多
In traditional urban geography, city contact research is a classic study element in city research. In general, researchers use the traditional gravity model to characterize the contacts that exist between two cities. ...In traditional urban geography, city contact research is a classic study element in city research. In general, researchers use the traditional gravity model to characterize the contacts that exist between two cities. The traditional gravity model assumes ideal conditions, but these preconditions and their results often do not exist in realistic conditions. Thus, we used a modified gravity model to characterize the city contacts within a specific region. This model considers factors such as intercity complementarities, government intervention, and the diversity of the transportation infrastructure which is characterized as the transportation distance instead of the traditional Euclidean distance. We applied this model to an empirical study of city contact in the Zhujiang(Pearl) River Delta(PRD) of China. The regression results indicated that the modified gravity model could measure city contact more accurately and comprehensively than the traditional gravity model, i.e., it yielded a higher adjusted R2 value(0.379) than the traditional gravity model result(0.259). Our study also suggests that, in addition to urban-regional and metropolitan development, the complementarities of the basic functions of cities at the administrative and market levels, as well as the corporeal and immaterial levels, play very significant roles in the characterization of city contact. Given the complexity of city contact, it will be necessary to consider more relevant influential factors in the modified gravity model to characterize the features of city contact in the future.展开更多
The interactive Lagrangian density of massive photons and gravitons is proposed after an investigation into the interaction between photons with or without mass under the influence of gravity either as classical field...The interactive Lagrangian density of massive photons and gravitons is proposed after an investigation into the interaction between photons with or without mass under the influence of gravity either as classical field, gravitational wave, or gravitons from a perspective of quantum field. This interactive Lagrangian density can provide a step-stone for further research of gravitational wave and the possible rest mass of photon.展开更多
On the basis of the theoretical analysis of a single-machine infinite-bus (SMIB), using the modified linearized Phil- lips-Heffron model installed with unified power flow controller (UPFC), the potential of the UP...On the basis of the theoretical analysis of a single-machine infinite-bus (SMIB), using the modified linearized Phil- lips-Heffron model installed with unified power flow controller (UPFC), the potential of the UPFC supplementary controller to enhance the dynamic stability of a power system is evaluated by measuring the electromechanical controllability through singular value decomposition (SVD) analysis. This controller is tuned to simultaneously shift the undamped electromeehanical modes to a prescribed zone in the s-plane. The problem of robust UPFC based damping controller is formulated as an optimization problem according to the eigenvalue-based multi-objective function comprising the damping factor, and the damping ratio of the undamped electromechanical modes to be solved using gravitational search algorithm (GSA) that has a strong ability to find the most optimistic results. The different loading conditions are simulated on a SMIB system and the rotor speed deviation, internal voltage deviation, DC voltage deviation and electrical power deviation responses are studied with the effect of this flexible AC transmission systems (FACTS) controller. The results reveal that the tuned GSA based UPFC controller using the proposed multi-objective function has an excellent capability in damping power system with low frequency oscillations and greatly enhances the dynamic stability of the power systems.展开更多
Underwater vehicles have already adopted self-correcting directional guidance algorithms based on multi-beam self-guidance systems, not waiting for research to determine the most effective algorithms. The main challen...Underwater vehicles have already adopted self-correcting directional guidance algorithms based on multi-beam self-guidance systems, not waiting for research to determine the most effective algorithms. The main challenges facing research on these guidance systems have been effective modeling of the guidance algorithm and a means to analyze the simulation results. A simulation structure based on Simulink that dealt with both issues was proposed. Initially, a mathematical model of relative motion between the vehicle and the target was developed, which was then encapsulated as a subsystem. Next, steps for constructing a model of the self-correcting guidance algorithm based on the Stateflow module were examined in detail. Finally, a 3-D model of the vehicle and target was created in VRML, and by processing mathematical results, the model was shown moving in a visual environment. This process gives more intuitive results for analyzing the simulation. The results showed that the simulation structure performs well. The simulation program heavily used modularization and encapsulation, so has broad applicability to simulations of other dynamic systems.展开更多
Three drums with different helical angles (15°, 20°, and 25°) were developed to investigate improved loading performance of the shearer drum. Nine trials were performed at different drum rotation spee...Three drums with different helical angles (15°, 20°, and 25°) were developed to investigate improved loading performance of the shearer drum. Nine trials were performed at different drum rotation speeds (80, 100, and 120 r/min) and different haulage speeds (1.5, 2.0, and 2.5 m/min) in an orthogonal test design. Loaded coal quantity and cutting power of the drum were the responses measured under the dif- ferent conditions. The effect of the parameters was determined by means of the extreme difference method. The significance of the effects was determined by analysis of variance. The results indicate that the effect from changes in the helical vane on loading performance of the drum is the largest in magnitude. The haulage speed has the least affect on loading performance. The helical angle has the least affect on cutting power of the drum. Haulage speed has the largest affect on the cutting power of the drum. 2011 Published by Elsevier B.V. on behalf of China University of Mining & Technology.展开更多
While modeling a power supply system for an electric railway traction, knowing equivalent circuits of locomotives supplied this way is an essential issue. In alternating current traction, it is important to diagnose i...While modeling a power supply system for an electric railway traction, knowing equivalent circuits of locomotives supplied this way is an essential issue. In alternating current traction, it is important to diagnose inter alia processes taking place in transformers installed on electric vehicles. This article presents specific phenomena occurring during the work of mono-phase, multi-winding, multisystem (systems AC: 50 Hz, 16.7 Hz) laboratory traction transformer. It also shows difficulties encountered during the process of identifying multi-port equivalent scheme's elements of the described device, in which a construction defect occurs.展开更多
The discrete choice model is used to estimate the walking access area of rail transit stations while considering the influence of existing competition from other traffic modes. The acceptable walking access area is de...The discrete choice model is used to estimate the walking access area of rail transit stations while considering the influence of existing competition from other traffic modes. The acceptable walking access area is determined according to the willingness of passengers to walk who prefer rail transit compared with bus and automobile. Empirical studies were conducted using the survey data of six stations from the rail transit in Nanjing, China. The results indicate that the rail transit is more preferable compared with bus and private automobile in this case when excluding the influence of individual and environmental factors. It is found that passengers tend to underestimate their willingness to walk. The acceptable walking access area of every rail transit station is different from each other. Suburban stations generally have a larger walking access area than downtown stations. In addition, a better walking environment and a scarcer surrounding traffic environment can also lead to a larger walking area. The model was confirmed to be effective and reasonable according to the model validation. This study can be of benefit to the passenger transportation demand estimation in the location planning and evaluation of rail transit stations.展开更多
Preparation of thermoplastic elastomer of Polypropylene-SIR 10 rubber blends with addition of DCP (dicumil peroxide) as initiator and DVB (divinylbenzene) as a crosslinker has been done. Blends of Polypropylene-SI...Preparation of thermoplastic elastomer of Polypropylene-SIR 10 rubber blends with addition of DCP (dicumil peroxide) as initiator and DVB (divinylbenzene) as a crosslinker has been done. Blends of Polypropylene-SIR 10 rubber with variation of weight 60/40 (w/w), 50/50 (w/w) and 40/60 (w/w) with variation concentration of DCP and DVB 1 phr, 2 phr and 3 phr were mixed into internal mixer at temperature 180 ℃. Then, the blends were pressed at 185 ℃ and specimen were molded according to the ASTM D638. The characterization were carried out based on tensile strength testing, crosslink percentage, morphology surface analysis with SEM and fungtional group analysis with FTIR (Fourier Transform Infra Red). The result showed that the blends of Polypropilene-SIR 10 rubber 60/40 (w/w) with 2 phr DCP and 1 phr DVB posses a higher tensile strength with value 1.37 Kgf/mm2 and value of elongation at break 17.58%, and value of percentage crosslink 82.4%. The result of morphology test with SEM showed that the blend was well homogenous. Spectra analysis with FT-IR has shown physical interaction among components of the blends.展开更多
Internet based social-networking sites like Facebook are highly attractive, user-friendly, and increasingly popular. Current estimates indicate over 750 million users of Facebook alone. However, Internet addiction is ...Internet based social-networking sites like Facebook are highly attractive, user-friendly, and increasingly popular. Current estimates indicate over 750 million users of Facebook alone. However, Internet addiction is an increasing problem amongst today's youth and as yet, is understudied in the United States. This study looked at the relationship between this new social-networking tool and the increasing phenomenon of internet addiction symptoms using both a US college sample (age 19years) and a US high-school sample (age 14years). Findings indicate that SNS (Social Networking Site) activity maybe more predictive of addictive behaviors than general internet use and that higher percents of symptomology occur in those users reporting SNS activity as their primary internet activity.展开更多
The development of an analytic solution in terms of laminate parameters is presented for contact stresses and joint strength in pin-loaded orthotropic plates. This involved the determination of complex stress function...The development of an analytic solution in terms of laminate parameters is presented for contact stresses and joint strength in pin-loaded orthotropic plates. This involved the determination of complex stress functions required to compute stresses in terms of a set of unknown coefficients for the specified displacement expressions satisfying the prescribed boundary conditions. The assumed Coulomb friction between the plate and the pin was used to provide the solution and iteration was also used to determine the extent of contact region. The results from present study showed good agreement with the available results in literature for all the joint configurations evaluated.展开更多
Based on the single-factor market model, this paper examines the confirmation basis and measurement of the losses arising from systematic risk in the civil damages of false statements. The paper argues that the system...Based on the single-factor market model, this paper examines the confirmation basis and measurement of the losses arising from systematic risk in the civil damages of false statements. The paper argues that the systematic risk not only affects the investment in securities during times of financial crisis, but also causes losses in daily securities trading. The paper carries out an empirical analysis on the existence of fl coefficient for China's listed companies within a period of one year, and examines the impact of systematic risk on the losses of investors. The civil damages of false statements should take full account of the losses arising from systematic risk. After analysis, the paper uses the correlation coefficient to represent the ratio of losses arising from systematic risk of all the transactions of a particular stock during a certain period of time, and tries to develop two methods to measure the damages after adjusting the losses caused by the systematic risk. The paper has a theoretical foundation for the estimation of losses caused by systematic risk, and matches the risks and returns. The result of the paper has provided an effective method of calculation in the determination of reasonable damages in the case of China Langfang Development Co., Ltd.展开更多
The most challenging problem in mesh denoising is to distinguish features from noise. Based on the robust guided normal estimation and alternate vertex updating strategy, we investigate a new feature-preserving mesh d...The most challenging problem in mesh denoising is to distinguish features from noise. Based on the robust guided normal estimation and alternate vertex updating strategy, we investigate a new feature-preserving mesh denoising method. To accurately capture local structures around features, we propose a corner-aware neighborhood (CAN) scheme. By combining both overall normal distribution of all faces in a CAN and individual normal influence of the interested face, wc give a new consistency measuring method, which greatly improves the reliability of the estimated guided normals. As the noise level lowers, we take as guidance the previous filtered normals, which coincides with the emerging roUing guidance idea. In the vertex updating process, we classify vertices according to filtered normals at each iteration and reposition vertices of distinct types alternately with individual regularization constraints. Experiments on a variety of synthetic and real data indicate that our method adapts to various noise, both Gaussian and impulsive, no matter in the normal direction or in a random direction, with fcw triangles flippcd.展开更多
Purpose: To identify and appraise the published studies assessing interventions accounting for reducing fatigue and sleepiness while driving. Methods: This systematic review searched the following electronic databa...Purpose: To identify and appraise the published studies assessing interventions accounting for reducing fatigue and sleepiness while driving. Methods: This systematic review searched the following electronic databases: Medline, Science direct, Scopus, EMBASE, PsyclNFO, Transport Database, Cochrane, BIOSIS, ISI Web of Knowledge, specialist road injuries journals and the Australian Transport and Road Index database. Additional searches included websites of relevant organizations, reference lists of included studies, and issues of major injury journals published within the past 15 years. Studies were included if they investigated interventions/exposures accounting for reducing fatigue and sleepiness as the outcome, measured any potential interventions for mitigation of sleepiness and were written in English. Meta-analysis was not attempted because of the heterogeneity of the included studies. Results: Of 63 studies identified, 18 met the inclusion criteria. Based on results of our review, many interventions in the world have been used to reduce drowsiness while driving such as behavioral (talking to passengers, face washing, listening to the radio, no alcohol use, limiting the driving behavior at the time of 12 p.m. - 6 a.m. etc), educational interventions and also changes in the environment (such as rumble strips, chevrons, variable message signs, etc). Meta-analysis on the effect of all these in- terventions was impossible due to the high heterogeneity in methodology, effect size and interventions reported in the assessed studies. Conclusion: Results of present review showed various interventions in different parts of the world have been used to decrease drowsy driving. Although these interventions can be used in countries with high incidence of road traffic accidents, precise effect of each intervention is still unknown. Further studies are required for comparison of the efficiency of each intervention and localization of each intervention ac- cording to the traffic pattems of each country.展开更多
基金supported by the National Key Technology R & D Program of China (No. 2008BAC39B05)the National Natural Science Foundation of China (No. 30670289)
文摘Reintroduction of captive-bred animals into suitable habitats is an important technique for the long-term conservation and recovery of populations of endangered species in fragmented landscapes.Inbreeding depression is an inherent risk when using captive populations for reintroduction programs and needs to be carefully assessed prior to reintroduction.In this study,we evaluated inbreeding levels within a captive breeding program and one remnant wild population of Cabot's Tragopan (Tragopan caboti),an endangered pheasant species endemic to China,for which reintroduction is now an essential conservation strategy for long-term population persistence.Fifteen highly polymorphic microsatellite loci were developed to genotype individuals.Inbreeding coefficients (FIS) reveal that there is no evidence of inbreeding within the Tragopan Breeding Center of Beijing Normal University (TBCBNU) captive population and the remnant population from the Wuyi-Yandang Mountains.Diversity of origin,large founder population size and a rational breeding strategy are the most critical factors preventing inbreeding depression within the TBCBNU captive population.We suggest that the TBCBNU population is a suitable candidate stock for T.caboti reintroduction programs and that there is an urgent need to better coordinate and strengthen reproduction management of captive T.caboti populations to sustain the long-term ex situ conservation of the species.
基金Supported by Excellent Team Training Program of Yunnan Academy of Agriculture Sciences(YAAS2014YY002)~~
文摘[Objective] This study aimed to screen a set of SSR core primers suitable for purity identification of pepper (Capsicum) hybrids. [Method] DNA fingerprint of 100 pepper hybrids was analyzed using 17 SSR primers. [Result] According to the polymorphism and heterozygosity, Hpms1-214, Es395 and Hpmsl-5 were determined as three preferred core primers for purity identification of pepper hybrids. By using these three preferred core primers, 97 pepper hybrids (accounting for 97%) had heterozygous band pattern with at least one primer. Es330, Es363, Epms923, Es120 and Es64 were determined as candidate core primers for purity identification of pepper hybrids. Specific primers of 14 varieties were obtained, which could be used to further screen parent-complementary primers of each pepper hybrid. [Con- clusion] This study laid the foundation for constructing standard DNA fingerprints for purity identification of pepper hybrids.
基金Under the auspices of Key Project of National Natural Science Foundation of China (No 40635026)
文摘Cities separated in space are connected together by spatial interaction (SI) between them. But the studies focusing on the SI are relatively few in China mainly because of the scarcity of data. This paper deals with the SI in terms of rail passenger flows, which is an important aspect of the network structure of urban agglomeration. By using a data set consisting of rail O-D (origin-destination) passenger flows among nearly 200 cities, intercity rail distance O-D matrixes, and some other indices, it is found that the attenuating tendency of rail passenger is obvious. And by the analysis on dominant flows and spatial structure of flows, we find that passenger flows have a trend of polarizing to hubs while the linkages between hubs upgrade. However, the gravity model reveals an overall picture of convergence process over time which is not in our expectation of integration process in the framework of globalization and economic integration. Some driven factors for the re-organization process of the structure of urban agglomeration, such as technique advance, globalization, etc. are discussed further based on the results we obtained.
文摘Various regulations, aimed at the protection of human beings and electrical equipment against possible adverse effects resulting from exposure to electromagnetic fields, have been issued in many countries. Most of them are based on safety guidelines published by international expert groups. In this paper, electric and magnetic fields are calculated in the vicinity of 25 kV traction line supplying railway traction systems. Calculation results are compared to exposure limits specified by safety guidelines and regulations. Possible countermeasures for reduction of electromagnetic fields are proposed. Also, this paper presents a method for calculation of the induced voltages to an underground gas pipeline from a neighbouring 25 kV electric traction overhead line in case of short circuit. Calculations are performed with EMTP-ATP software. Possible countermeasures for reduction of induced voltages are proposed.
基金Supported by Special Fund for the Screening and Breeding of Low-Cd-accumulating Crop Varieties~~
文摘Different results of seed purity identification for Gangyou 158, Ⅱ You 808, Wuyou 308 and Tianfengyou 316 were obtained using different SSR primers in our early work. To find out the reasons, the four hybrid combinations were grown in field to identify their purity according to their phenotypic traits. Then, the results of field identification were compared with that of laboratory tests using different SSR primers. The comparison revealed that only sterile lines (female parent) were distin- guished from true hybrids using the primers RM208, RM264, RM242 and RM164 for the purity identification of Gangyou 158, II You 808, Wuyou 308 and Tianfengyou 316, so the results were higher than that of field identification. In contrast, the primers RM341, RM297, RM21 and RM110 were able to distinguish not only the sterile plants but also the cross-pollinated ones from the true hybrids of Gangyou 158,Ⅱ You 808, Wuyou 308 and Tianfengyou 316, and the results of purity identifi- cation using them were close that of field identification, in summary, several pairs of primers should be used for the purity identification of rice hybrids to distinguish all the off-type plants and thus improve the accuracy.
基金Under the auspices of National Natural Science Foundation of China(No.41271177)Guangdong Natural Science Foundation(No.S2012010008902)
文摘In traditional urban geography, city contact research is a classic study element in city research. In general, researchers use the traditional gravity model to characterize the contacts that exist between two cities. The traditional gravity model assumes ideal conditions, but these preconditions and their results often do not exist in realistic conditions. Thus, we used a modified gravity model to characterize the city contacts within a specific region. This model considers factors such as intercity complementarities, government intervention, and the diversity of the transportation infrastructure which is characterized as the transportation distance instead of the traditional Euclidean distance. We applied this model to an empirical study of city contact in the Zhujiang(Pearl) River Delta(PRD) of China. The regression results indicated that the modified gravity model could measure city contact more accurately and comprehensively than the traditional gravity model, i.e., it yielded a higher adjusted R2 value(0.379) than the traditional gravity model result(0.259). Our study also suggests that, in addition to urban-regional and metropolitan development, the complementarities of the basic functions of cities at the administrative and market levels, as well as the corporeal and immaterial levels, play very significant roles in the characterization of city contact. Given the complexity of city contact, it will be necessary to consider more relevant influential factors in the modified gravity model to characterize the features of city contact in the future.
基金Funded by the National Basic Research Programs of China under Grant No. 2003CB716300, the Natural Science Foundation of Chongqing under Grant No. 8562, and the Natural Science Foundation of China under Grant No. 10575140.
文摘The interactive Lagrangian density of massive photons and gravitons is proposed after an investigation into the interaction between photons with or without mass under the influence of gravity either as classical field, gravitational wave, or gravitons from a perspective of quantum field. This interactive Lagrangian density can provide a step-stone for further research of gravitational wave and the possible rest mass of photon.
文摘On the basis of the theoretical analysis of a single-machine infinite-bus (SMIB), using the modified linearized Phil- lips-Heffron model installed with unified power flow controller (UPFC), the potential of the UPFC supplementary controller to enhance the dynamic stability of a power system is evaluated by measuring the electromechanical controllability through singular value decomposition (SVD) analysis. This controller is tuned to simultaneously shift the undamped electromeehanical modes to a prescribed zone in the s-plane. The problem of robust UPFC based damping controller is formulated as an optimization problem according to the eigenvalue-based multi-objective function comprising the damping factor, and the damping ratio of the undamped electromechanical modes to be solved using gravitational search algorithm (GSA) that has a strong ability to find the most optimistic results. The different loading conditions are simulated on a SMIB system and the rotor speed deviation, internal voltage deviation, DC voltage deviation and electrical power deviation responses are studied with the effect of this flexible AC transmission systems (FACTS) controller. The results reveal that the tuned GSA based UPFC controller using the proposed multi-objective function has an excellent capability in damping power system with low frequency oscillations and greatly enhances the dynamic stability of the power systems.
文摘Underwater vehicles have already adopted self-correcting directional guidance algorithms based on multi-beam self-guidance systems, not waiting for research to determine the most effective algorithms. The main challenges facing research on these guidance systems have been effective modeling of the guidance algorithm and a means to analyze the simulation results. A simulation structure based on Simulink that dealt with both issues was proposed. Initially, a mathematical model of relative motion between the vehicle and the target was developed, which was then encapsulated as a subsystem. Next, steps for constructing a model of the self-correcting guidance algorithm based on the Stateflow module were examined in detail. Finally, a 3-D model of the vehicle and target was created in VRML, and by processing mathematical results, the model was shown moving in a visual environment. This process gives more intuitive results for analyzing the simulation. The results showed that the simulation structure performs well. The simulation program heavily used modularization and encapsulation, so has broad applicability to simulations of other dynamic systems.
基金support for this work was provided by the National Natural Science Foundation of China (No. 51005232)the China Postdoctoral Science Foundation (No. 20100481176)
文摘Three drums with different helical angles (15°, 20°, and 25°) were developed to investigate improved loading performance of the shearer drum. Nine trials were performed at different drum rotation speeds (80, 100, and 120 r/min) and different haulage speeds (1.5, 2.0, and 2.5 m/min) in an orthogonal test design. Loaded coal quantity and cutting power of the drum were the responses measured under the dif- ferent conditions. The effect of the parameters was determined by means of the extreme difference method. The significance of the effects was determined by analysis of variance. The results indicate that the effect from changes in the helical vane on loading performance of the drum is the largest in magnitude. The haulage speed has the least affect on loading performance. The helical angle has the least affect on cutting power of the drum. Haulage speed has the largest affect on the cutting power of the drum. 2011 Published by Elsevier B.V. on behalf of China University of Mining & Technology.
文摘While modeling a power supply system for an electric railway traction, knowing equivalent circuits of locomotives supplied this way is an essential issue. In alternating current traction, it is important to diagnose inter alia processes taking place in transformers installed on electric vehicles. This article presents specific phenomena occurring during the work of mono-phase, multi-winding, multisystem (systems AC: 50 Hz, 16.7 Hz) laboratory traction transformer. It also shows difficulties encountered during the process of identifying multi-port equivalent scheme's elements of the described device, in which a construction defect occurs.
基金The Scientific Research Foundation of Graduate School of Southeast University(No.YBJJ1838)the Fundamental Research Funds for the Central Universities(No.KYLX16_0270)the Foundation of China Scholarship Council(No.201606090240)
文摘The discrete choice model is used to estimate the walking access area of rail transit stations while considering the influence of existing competition from other traffic modes. The acceptable walking access area is determined according to the willingness of passengers to walk who prefer rail transit compared with bus and automobile. Empirical studies were conducted using the survey data of six stations from the rail transit in Nanjing, China. The results indicate that the rail transit is more preferable compared with bus and private automobile in this case when excluding the influence of individual and environmental factors. It is found that passengers tend to underestimate their willingness to walk. The acceptable walking access area of every rail transit station is different from each other. Suburban stations generally have a larger walking access area than downtown stations. In addition, a better walking environment and a scarcer surrounding traffic environment can also lead to a larger walking area. The model was confirmed to be effective and reasonable according to the model validation. This study can be of benefit to the passenger transportation demand estimation in the location planning and evaluation of rail transit stations.
文摘Preparation of thermoplastic elastomer of Polypropylene-SIR 10 rubber blends with addition of DCP (dicumil peroxide) as initiator and DVB (divinylbenzene) as a crosslinker has been done. Blends of Polypropylene-SIR 10 rubber with variation of weight 60/40 (w/w), 50/50 (w/w) and 40/60 (w/w) with variation concentration of DCP and DVB 1 phr, 2 phr and 3 phr were mixed into internal mixer at temperature 180 ℃. Then, the blends were pressed at 185 ℃ and specimen were molded according to the ASTM D638. The characterization were carried out based on tensile strength testing, crosslink percentage, morphology surface analysis with SEM and fungtional group analysis with FTIR (Fourier Transform Infra Red). The result showed that the blends of Polypropilene-SIR 10 rubber 60/40 (w/w) with 2 phr DCP and 1 phr DVB posses a higher tensile strength with value 1.37 Kgf/mm2 and value of elongation at break 17.58%, and value of percentage crosslink 82.4%. The result of morphology test with SEM showed that the blend was well homogenous. Spectra analysis with FT-IR has shown physical interaction among components of the blends.
文摘Internet based social-networking sites like Facebook are highly attractive, user-friendly, and increasingly popular. Current estimates indicate over 750 million users of Facebook alone. However, Internet addiction is an increasing problem amongst today's youth and as yet, is understudied in the United States. This study looked at the relationship between this new social-networking tool and the increasing phenomenon of internet addiction symptoms using both a US college sample (age 19years) and a US high-school sample (age 14years). Findings indicate that SNS (Social Networking Site) activity maybe more predictive of addictive behaviors than general internet use and that higher percents of symptomology occur in those users reporting SNS activity as their primary internet activity.
文摘The development of an analytic solution in terms of laminate parameters is presented for contact stresses and joint strength in pin-loaded orthotropic plates. This involved the determination of complex stress functions required to compute stresses in terms of a set of unknown coefficients for the specified displacement expressions satisfying the prescribed boundary conditions. The assumed Coulomb friction between the plate and the pin was used to provide the solution and iteration was also used to determine the extent of contact region. The results from present study showed good agreement with the available results in literature for all the joint configurations evaluated.
文摘Based on the single-factor market model, this paper examines the confirmation basis and measurement of the losses arising from systematic risk in the civil damages of false statements. The paper argues that the systematic risk not only affects the investment in securities during times of financial crisis, but also causes losses in daily securities trading. The paper carries out an empirical analysis on the existence of fl coefficient for China's listed companies within a period of one year, and examines the impact of systematic risk on the losses of investors. The civil damages of false statements should take full account of the losses arising from systematic risk. After analysis, the paper uses the correlation coefficient to represent the ratio of losses arising from systematic risk of all the transactions of a particular stock during a certain period of time, and tries to develop two methods to measure the damages after adjusting the losses caused by the systematic risk. The paper has a theoretical foundation for the estimation of losses caused by systematic risk, and matches the risks and returns. The result of the paper has provided an effective method of calculation in the determination of reasonable damages in the case of China Langfang Development Co., Ltd.
基金Project supported by the National Natural Science Foundation of China (Nos. 61402224 and 61222206), the Natural Science Foundation of Jiangsu Province, China (No. BK2014833), and the Natural Science Foundation of Suzhou University of Science and Technology, China (No. XKZ201611).Acknowledgements The authors would like to appreciate Wang-yu ZHANG for providing executable programs. The models used in this paper are courtesy of the AIM Shape Repos- itory, the Stanford 3D Scanning Repository, and Laser Design.
文摘The most challenging problem in mesh denoising is to distinguish features from noise. Based on the robust guided normal estimation and alternate vertex updating strategy, we investigate a new feature-preserving mesh denoising method. To accurately capture local structures around features, we propose a corner-aware neighborhood (CAN) scheme. By combining both overall normal distribution of all faces in a CAN and individual normal influence of the interested face, wc give a new consistency measuring method, which greatly improves the reliability of the estimated guided normals. As the noise level lowers, we take as guidance the previous filtered normals, which coincides with the emerging roUing guidance idea. In the vertex updating process, we classify vertices according to filtered normals at each iteration and reposition vertices of distinct types alternately with individual regularization constraints. Experiments on a variety of synthetic and real data indicate that our method adapts to various noise, both Gaussian and impulsive, no matter in the normal direction or in a random direction, with fcw triangles flippcd.
文摘Purpose: To identify and appraise the published studies assessing interventions accounting for reducing fatigue and sleepiness while driving. Methods: This systematic review searched the following electronic databases: Medline, Science direct, Scopus, EMBASE, PsyclNFO, Transport Database, Cochrane, BIOSIS, ISI Web of Knowledge, specialist road injuries journals and the Australian Transport and Road Index database. Additional searches included websites of relevant organizations, reference lists of included studies, and issues of major injury journals published within the past 15 years. Studies were included if they investigated interventions/exposures accounting for reducing fatigue and sleepiness as the outcome, measured any potential interventions for mitigation of sleepiness and were written in English. Meta-analysis was not attempted because of the heterogeneity of the included studies. Results: Of 63 studies identified, 18 met the inclusion criteria. Based on results of our review, many interventions in the world have been used to reduce drowsiness while driving such as behavioral (talking to passengers, face washing, listening to the radio, no alcohol use, limiting the driving behavior at the time of 12 p.m. - 6 a.m. etc), educational interventions and also changes in the environment (such as rumble strips, chevrons, variable message signs, etc). Meta-analysis on the effect of all these in- terventions was impossible due to the high heterogeneity in methodology, effect size and interventions reported in the assessed studies. Conclusion: Results of present review showed various interventions in different parts of the world have been used to decrease drowsy driving. Although these interventions can be used in countries with high incidence of road traffic accidents, precise effect of each intervention is still unknown. Further studies are required for comparison of the efficiency of each intervention and localization of each intervention ac- cording to the traffic pattems of each country.