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螺纹连接件胶接防松性能测试技术研究 被引量:3
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作者 温楠 刘锴 张忠伟 《航天标准化》 2014年第3期9-12,共4页
对螺纹连接件用防松胶开展防松性能试验方法的研究,选取典型厌氧胶、螺栓与螺母组件进行防松性能试验,对试验结果进行对比分析,根据国外乐泰胶在航天产品上的应用情况,给出后续研究的重点方向。
关键词 接防 扭矩试验 振动试验 乐泰胶 螺纹紧固件
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在朝鲜战场接防中的一段往事
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作者 杨成武 《神州》 2007年第10期74-75,共2页
1951年8月的一天,我在离开中国人民志愿军司令部前往台日里的途中,决定去看看我们的友邻——中国人民志愿军第九兵团。因为,根据志愿军司令部的指示,我们第二十兵团很快将在东线接替第九兵团的防务。守防五圣山一带的第九兵团第二十六... 1951年8月的一天,我在离开中国人民志愿军司令部前往台日里的途中,决定去看看我们的友邻——中国人民志愿军第九兵团。因为,根据志愿军司令部的指示,我们第二十兵团很快将在东线接替第九兵团的防务。守防五圣山一带的第九兵团第二十六军也将转归我们兵团统一指挥。 展开更多
关键词 兵团 武器装备 朝鲜战争 司令员 接防 战场 运动战 战役 作战任务 中国人民志愿军
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当前西部民族地区的群体性事件探析 被引量:6
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作者 谢俊春 《重庆文理学院学报(社会科学版)》 2009年第6期19-22,共4页
目前西部地区群体性事件多发于土地征用、城镇改造、移民安置、劳资关系、环境污染、国企改制、资源开发等领域,贫富差距、分配不公、钱权交易、治安恶化和官员腐败则是群体性事件发生的深层次原因。西部地区以维权为目的的群体性事件... 目前西部地区群体性事件多发于土地征用、城镇改造、移民安置、劳资关系、环境污染、国企改制、资源开发等领域,贫富差距、分配不公、钱权交易、治安恶化和官员腐败则是群体性事件发生的深层次原因。西部地区以维权为目的的群体性事件是人民内部矛盾,在多元利益主体博弈的市场经济条件下具有其合理性。但是,群体性事件表现出来的巨大规模、暴力倾向、"无直接利益冲突"苗头,以及政治诉求的强化,对西部地区的社会稳定构成了严重的威胁。针对西部地区群体性事件多发的情况,地方各级政府要定位准确,真正做到利为民所谋,善于调整各种利益关系,疏通民意表达的渠道,大力进行社会建设,积极推进政治体制改革,并建立起群体性事件的预警、应急和善后机制。 展开更多
关键词 西部地区 群体性事件 公信力 接防制度 预警机制
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Protective effect of inactivated hepatitis A vaccine against the outbreak of hepatitis A in an open rural community 被引量:1
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作者 Yue-Gen Shen Xie-Jun Gu Jian-Hong Zhou 《World Journal of Gastroenterology》 SCIE CAS CSCD 2008年第17期2771-2775,共5页
AIM: To evaluate the protective effect of inactivated hepatitis A vaccine (Healive) against hepatitis A outbreak in an emergency vaccination campaign. METHODS: During an outbreak of hepatitis A in Honghe Town, Xiu... AIM: To evaluate the protective effect of inactivated hepatitis A vaccine (Healive) against hepatitis A outbreak in an emergency vaccination campaign. METHODS: During an outbreak of hepatitis A in Honghe Town, Xiuzhou District, Jiaxing City, Zhejiang Province, two nonrandomized controlled trials were conducted in September 2006. The first trial was to vaccinate 108 anti-HAV negative individuals with close contacts of the patients from September with 1 dose of an inactivated hepatYds A vaccine, HeaUve. The control group comprised of 115 individuals with close contacts of the patients before September. The second trial was to vaccinate 3365 primary and secondary school students who volunteered to receive a dose of Healive and 2572 students who did not receive Healive serving as its controls. An epidemiological survey was conducted to evaluate the pmtectk, e efficacy of the vaccine. RESULTS: A total of 136 hepatitis A cases were reported during an outbreak that started in June, peaked in August and September, and ended after December of 2006. After a massive vaccination of school children in September, the number of cases declined significantly. No hepatitis A was detected in the 108 vaccinated individuals with dose contacts of patients, whereas 4 cases of hepatitis A were found in the controls. The infection rate of hepatitis A was not significantly different in the individuals with close contacts of patients whether or not they received the vaccine (P = 0.122). No hepatitis A was detected in the 3365 students who received the vaccine, four cases of hepatitis A were found in the controls. The infection rate of students with or without vaccination was significantly diffeent in the students who received the vaccine (0/3365 vs 4/2572, P = 0.035). The protective efficacy of the vaccine was 100%.CONCLUSION: Inactivated hepatitis A vaccine demonstrates a good protective effect against an outbreak of hepatitis A. 展开更多
关键词 Hepatitis A OUTBREAK Inactivated hepatitis Avaccine Emergency vaccination Protective efficacy
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Application of Image Processing in Automatic Vehicle Guidance 被引量:1
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作者 唐莉萍 臧珠萍 +1 位作者 曾培峰 欧阳文斌 《Journal of Donghua University(English Edition)》 EI CAS 2011年第2期190-195,共6页
A micro controller unit (MCU) oriented image acquisition and automatic guidance system is proposed. Image rectification and guidance recognition are discussed. The relation between camera setting and sight view is ill... A micro controller unit (MCU) oriented image acquisition and automatic guidance system is proposed. Image rectification and guidance recognition are discussed. The relation between camera setting and sight view is illustrated for smart car. A novel edge detection and trend prediction method is proposed for MCU processing unit for automatic guidance. A hardware-based binary proposal is discussed for guidance information detection with raster data. Keystone distortion correcting algorithm is also designed for MCU application and the performance of track type recognition is improved. Together with rollover preventing calculation, the proposed design is successfully applied to a 1∶10 scale model car. 展开更多
关键词 automatic car guidance BINARIZATION video capture keystone distortion rollover prevention
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TCP-Rab: a receiver advertisement based TCP protocol 被引量:4
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作者 汤旭红 刘正蓝 朱淼良 《Journal of Zhejiang University Science》 EI CSCD 2004年第11期1352-1360,共9页
With the evolution of network technologies, the deficiencies of TCP protocol are becoming more and more distinct. The new TCP implementation, called Receiver Advertisement Based TCP (TCP-Rab) proposed here to eliminat... With the evolution of network technologies, the deficiencies of TCP protocol are becoming more and more distinct. The new TCP implementation, called Receiver Advertisement Based TCP (TCP-Rab) proposed here to eliminate these deficiencies, adopts two basic mechanisms: (1) Bandwidth Estimation and (2) Immediate Recovery. Bandwidth estimation is carried out at the receiver, and the result is sent back to the sender via the acknowledgments. Immediate Recovery guarantees high performance even in lossy link. Rab can distinguish the reason for packet loss, and thus adopt appropriate recovery strategy. For loss by network congestion, it will back off its congestion window, and for loss by link errors, it will recover the congestion window immediately. Simulations indicated that Rab has superiority over other TCP implementations. 展开更多
关键词 Bandwidth Estimation Immediate Recovery TCP protocol
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Establishment of Slip Coefficient for Slip Resistant Connection
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作者 Hwan-Seon Nah Kang-Sik Kim 《Journal of Civil Engineering and Architecture》 2011年第2期112-120,共9页
A slip critical connection has various values to adopt the proper slip coefficient in various conditions of faying surfaces in AISC, AIJ and Eurocode3. The Korean Building Code regulates the unique slip coefficient, f... A slip critical connection has various values to adopt the proper slip coefficient in various conditions of faying surfaces in AISC, AIJ and Eurocode3. The Korean Building Code regulates the unique slip coefficient, from 0.45 to 0.5 without consideration of the diverse faying conditions in 2009. In this study, the slip resistance test, including five kinds of surface treatments were conducted to obtain the proper slip coefficients available to steel plate KS SM490A. The slip coefficient of specimens over zinc primer thickness of 128 lam exhibit was 0.42. The clean mill treated surface had prominently lower values as slip coefficient, 0.27. For red lead painted treatment, it is suggested to setup a minimum slip coefficient, 0,21, below a coating thickness of 65 μam. The slip coefficient of one faced lap connection was higher 1.4 times than the slip coefficient of two faced lap connection. 展开更多
关键词 BOLT SLIP COEFFICIENT faying surface coating TORQUE tension.
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Analysis of Vibration Frequencies of Piezoelectric Ceramic Rings as Ultrasonic Transducers in Welding of Facial Mask Production
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作者 WU Jinghui ZHAO Shengquan +1 位作者 XIE Longtao WANG Ji 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2021年第1期124-131,共8页
The explosive demands for facial masks as vital personal protection equipment(PPE)in the wake of Covid-19 have challenged many industries and enterprises in technology and capacity,and the piezoelectric ceramic(PZT)tr... The explosive demands for facial masks as vital personal protection equipment(PPE)in the wake of Covid-19 have challenged many industries and enterprises in technology and capacity,and the piezoelectric ceramic(PZT)transducers for the production of facial masks in the welding process are in heavy demand.In the earlier days of the epidemic,the supply of ceramic transducers cannot meet its increasing demands,and efforts in materials,development,and production are mobilized to provide the transducers to mask producers for quick production.The simplest solution is presented with the employment of Rayleigh-Ritz method for the vibration analysis,then different materials can be selected to achieve the required frequency and energy standards.The fully tailored method and results can be utilized by the engineers for quick development of the PZT transducers to perform precise function in welding. 展开更多
关键词 piezoelectric ceramic(PZT) TRANSDUCER facial mask welding personal protection equipment(PPE)
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Vaccination Statistics and Reality: How Many Horses Are Really Vaccinated against Equine Influenza?
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作者 Heli I. Koskinen 《Journal of Agricultural Science and Technology(A)》 2014年第5期443-448,共6页
Standard schedules for equine influenza vaccinations have been published in Finland. However, no knowledge about the actual number of vaccinations has been available. Based on previous preliminary studies in slaughter... Standard schedules for equine influenza vaccinations have been published in Finland. However, no knowledge about the actual number of vaccinations has been available. Based on previous preliminary studies in slaughterhouses and among horse owners, it was suspected that vaccination recommendations are not always followed. The aims were to investigate vaccination status against equine influenza among Finnish racehorses in regional competitions. Vaccination status was investigated: (1) by utilizing database vaccination information of show jumping and dressage horses and (2) by carrying out a survey among horse industry experts. A total of 400 horses were selected at the beginning of the Finnish competition season in 2012 and five experts (key persons) were invited to a repeated survey implemented by Delphi techniques. Overall, 50%-100% of horses were properly vaccinated depending on the source available. Thirty-four percent (34%) of the horses had the competition license but no vaccination markings in the database. Differences between types of competition (show jumping and dressage) and between Southern and Northern parts of Finland were found. Vaccinations of show jumping horses were registered more often than vaccinations of dressage horses. Ninety percent (90%) of unvaccinated horses in the database were eight years or older. It can be concluded that equine influenza vaccination registry coverage among racehorses in Finland is incomplete. This poses a risk of misunderstanding, and the growing responsibility of competition organizers. 展开更多
关键词 Competition license Delphi Equestrian Federation of Finland equine influenza vaccine HORSE KIPA database.
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Anti-Tumor Efficacy of Gene Vaccine Expressing PSMA
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作者 Xiao-ling YANG Jing LV +1 位作者 Yue-hong ZHANG Bo NIU 《Clinical oncology and cancer researeh》 CAS CSCD 2010年第6期347-351,共5页
OBJECTIVE To observe anti-tumor effects of PVAX-PSMA gene vaccine. METHODS The PSMA gene was inserted into a mammalian expression vector, PVAX-1, to construct the DNA vaccine candidate, and was then used to vaccinate ... OBJECTIVE To observe anti-tumor effects of PVAX-PSMA gene vaccine. METHODS The PSMA gene was inserted into a mammalian expression vector, PVAX-1, to construct the DNA vaccine candidate, and was then used to vaccinate C57BL/6 mice. Animals vaccinated with PVAX-1 and NaC1 were used as controls. Anti-PSMA antibody was detected in sera of the animals. The proliferation and cytotoxicity of the spleen cells were observed. The immunized mice were inoculated with RM-1 cells. The mice were inoculated with RM-1 cells, and then the mice were immunized. The anti-tumor efficacy of the gene vaccine was evaluated by the ratio of tumor formation, tumor volume, tumor mass before and after gene vaccination and evaluated by survival rate of the immunized mice. RESULTS High level of anti-PSMA antibody was induced in the PVAX-PSMA group. The splenocytes from PVAX-PSMA group were stimulated to produce strong proliferation responses and significant cytotoxic T-cells (CTL) activity. After the mice were immunized with PVAX-PSMA gene, tumor occurrence was decreased, and the growth velocity of tumor was markedly reduced, resulting in prolonged tumor-free time (P 〈 0.05). CONCLUSION PVAX-PSMA gene vaccine has significant anti- tumor effects and provides an experimental basis for primary prevention and immunotherapy of prostate cancer. 展开更多
关键词 prostate cancer prostate-specific membrane antigen gene vaccine.
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Inflammatory bowel disease in travelers:Choosing the right vaccines and check-ups 被引量:1
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作者 Maria Esteve Carme Loras Ester García-Planella 《World Journal of Gastroenterology》 SCIE CAS CSCD 2011年第22期2708-2714,共7页
The majority of patients with inflammatory bowel disease (IBD) achieve good control of the inflammatory activity using available therapies. When remission is achieved and quality of life recovered, a considerable prop... The majority of patients with inflammatory bowel disease (IBD) achieve good control of the inflammatory activity using available therapies. When remission is achieved and quality of life recovered, a considerable proportion of IBD patients express their desire to travel abroad, be it for business, academic or leisure purposes. Their physicians should help and encourage them whenever possible. However, preventive measures are warranted to minimize the risk, since IBD patients are exposed to the same infections affecting the general population, plus opportunistic infections (OI) related to the immunosuppression. There are a large number of potential OI that might affect patients with IBD. The true prevalence of these infections is unknown, and can vary from country to country. Therefore, reactivation or de novo acquisition of infections such as tuberculosis, malaria, and viral hepatitis will be much more frequent in endemic areas. Therefore, physicians should beaware of these aspects when planning specific preventive measures for patients traveling to a particular country. This includes good control of environmental exposure, chemoprophylaxis when indicated, and the use of a specific vaccination program to prevent endemic infections. In addition, it should be noted that, though the risk of acquiring an infectious disease is probably greater for IBD patients traveling from a developed to a developing country, the inverse situation can also occur; it depends on the previous acquired immunity of the host against infections in any particular environment. 展开更多
关键词 Inflammatory bowel disease VACCINATION Opportunistic infections
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Grafting,metham sodium,soil solarization and virtually impermeable films as alternative technologies to methyl bromide for Chinese protected tomatoes 被引量:2
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作者 Han Xuemei Cao Zhiping +4 位作者 Chen Yunfeng Chen Guokang Andrea Camponogara Yang Hang Maria Lodovica Gullino 《Ecological Economy》 2009年第2期177-186,共10页
In the frame of the Sino-ltalian Cooperation Program for Environmental Protection, jointly launched in the year 2000 by the Italian Ministry for Environment and Territory and Sea (IMETS) and the China State Environm... In the frame of the Sino-ltalian Cooperation Program for Environmental Protection, jointly launched in the year 2000 by the Italian Ministry for Environment and Territory and Sea (IMETS) and the China State Environmental Protection Administration (SEPA), experimental trials were carried out in Qingzhou city (Shandong Province, China) during 2001-2003 to test several methyl bromide alternative methods to control soilborne diseases in greenhouse tomatoes. Grafting tomatoes on resistant rootstock (Lyeopersicon lycopersicum × L. hirsutum), metham sodium applied under traditional polyethylene plastic films; metham sodium applied at low rate under virtually impermeable films and soil sotarization combined with biocontrol agents were the alternatives tested and compared to methyl bromide applied under virtually impermeable plastic films too. Collected data show that resistant rootstock (Lycopersicon tycopersicum × L. hirsutum) introduced from Italy is a promising alternative to methyl bromide for local tomato cultivars. Metham sodium applied under traditional polyethylene plastic films is an effective alternative. Moreovez virtually impermeable films demonstrate the help to reduce methyl bromide and metham sodium rates. Finally soil solarization combined with biocontrol agents does not provide satisfactory results in terms of disease control. 展开更多
关键词 International cooperation Methyl bromide Soil disinfestation Soilborne pathogens
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USB Storage Device Protection Software
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作者 Zhao Chunyang Wang Weiping 《International Journal of Technology Management》 2013年第3期72-75,共4页
U disk is the most conveuient external memory, it is simple and easy to carry, but at the same time it is best tools to bring the virus. Limiting the use of USB interface effectively not only can limit the circulation... U disk is the most conveuient external memory, it is simple and easy to carry, but at the same time it is best tools to bring the virus. Limiting the use of USB interface effectively not only can limit the circulation of the virus, but also can play a part in safety precautions. In fact ,the easiest way of restricting USB interface is to modify the registry,but for many users, dealing with Registry keys is a boring job,for ordinary users, the application is the best way to solve this problem. This article describes a software development process, focusing on how to use C # to modify the registry key and password protection settings, to provide some reference for computer enthusiasts. 展开更多
关键词 USB C# PROGRAM REGISTRY VALUE PROTECTION PASSWORD
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An Overview of Anti-Collision Protocols for Radio Frequency Identification Devices 被引量:8
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作者 QIAN Zhihong WANG Xue 《China Communications》 SCIE CSCD 2014年第11期44-59,共16页
Radio frequency identification(RFID) is a new type of non-contact automatic identification technology.Due to its low energy consumption,low cost,and its adaptability to harsh environments,it has been applied to many f... Radio frequency identification(RFID) is a new type of non-contact automatic identification technology.Due to its low energy consumption,low cost,and its adaptability to harsh environments,it has been applied to many fields.In the RFID systems,data collision is inevitable when the reader sends a communication request and multiple tags respond with simultaneous data transmission.Data collision is prone to causing problems such as:identification delay,spectrum resource waste,a decreased system throughput rate,etc.Therefore,an efficient,stable anti-collision protocol is crucial for RFID systems.This research analysed the current research into RFID anticollision protocols and summarised means for its improvement through the mechanism of implementation of different types anticollision protocols.Finally,a new direction is proposed for the future development of RFID anti-collision protocol systems. 展开更多
关键词 radio frequency identification automatic identification data collision anticollision protocol.
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Analysis and Modeling of k-regular and k-connected Protection Structure in Ultra-High Capacity Optical Networks
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作者 LI Xin HUANG Shanguo +3 位作者 ZHANG Jie ZHAO Yongli GU Wanyi WANG Yang 《China Communications》 SCIE CSCD 2015年第3期106-119,共14页
This paper proposes k-regular and k-connected(k&k) structure against multifaults in ultra-high capacity optical networks.Theoretical results show that pre-configured k&k structure can reach the lower bound on ... This paper proposes k-regular and k-connected(k&k) structure against multifaults in ultra-high capacity optical networks.Theoretical results show that pre-configured k&k structure can reach the lower bound on logical redundancy.The switching time of k&k protection structure is as quickly as ringbased protection in SDH network.It is the optimal protection structure in ultra-high capacity optical networks against multi-faults.We develop the linear programming model for k&k structure and propose a construction method for k&k structure design.Simulations are conducted for spare spectrum resources effi ciency of the pre-confi gured k&k structure under multi-faults on representative COST239 and NSFnet topologies.Numerical results show that the spare spectrum resources efficiency of k&k structure can reach the lower bound on logical redundancy in static networks.And it can largely improve spare spectrum resources effi ciency compared with p-cycles based protection structure without reducing protection effi ciency under dynamic traffi cs. 展开更多
关键词 multi-faults k-regular and k-connected structure ultra-high capacity optical networks
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第一支开进北平城的人民解放军
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作者 墙师琼 《党史博览》 1999年第9期46-48,共3页
你知道北平解放后第一支开进城的人民解放军,是哪支部队吗?他们进城的第一夜是怎样度过的?这支部队就是被称为“铁军”的第四十一军(四纵)。该部队战斗作风勇敢,组织纪律严明,执行命令坚决。辽沈战役中死守塔山寸步不让,竟绝了10万蒋军... 你知道北平解放后第一支开进城的人民解放军,是哪支部队吗?他们进城的第一夜是怎样度过的?这支部队就是被称为“铁军”的第四十一军(四纵)。该部队战斗作风勇敢,组织纪律严明,执行命令坚决。辽沈战役中死守塔山寸步不让,竟绝了10万蒋军的生路!平津战役中腰斩长蛇声威震,合力歼敌无一漏。1948年秋天,他们在辽西战役中,宿营在老百姓的苹果园里,树上掉下来很多苹果,他们一个也不吃,捡起来送到老乡家里。毛泽东看了这个消息很感动,他说“在这个问题上,战士们自觉地认为:不吃是很高尚的,而吃了是很卑鄙的,因为这是人民的苹果。我们的纪律就建筑在这个自觉性上边的。” 展开更多
关键词 毛泽东 辽沈战役 接防部队 平城 警备司令部 英雄团 解放军 政治部主任 北平解放 战士
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Sleeping site use of the white-headed langur Trachypithecus leucocephalus: The role of predation risk, territorial defense, and proximity to feeding sites 被引量:3
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作者 Dayong LI Qihai ZHOU +2 位作者 Xiaoping TANG Henglian HUANG Chengming HUANG 《Current Zoology》 SCIE CAS CSCD 北大核心 2011年第3期260-268,共9页
We collected data on sleeping site use from two groups of white-headed langurs Trachypithecus leucocephalus living in Fusui Nature Reserve, China between August 2007 and July 2008. This information was used to test se... We collected data on sleeping site use from two groups of white-headed langurs Trachypithecus leucocephalus living in Fusui Nature Reserve, China between August 2007 and July 2008. This information was used to test several hypotheses regarding ultimate causes of sleeping site use in this primate. White-headed langurs slept either in caves (17 sites) or on a cliffledge (one site). They used all sleeping sites repeatedly, and reused some of them on consecutive nights; three nights was the longest consecutive use of any one sleep site. We suggest that langurs use sleeping sites to make approach and attack by predators difficult, and to increase their own familiarity with a location so as to improve chances for escape. Langurs' cryptic behaviors with an increased level of vigilance before entering sleeping sites may also help in decreasing the possibility of detection by predators. Group 1 spent more sleeping nights in the central area of their territory than expected; in contrast, group 2 spent more sleeping nights in the periphery of their territory, which overlaps with that of another groups, than expected. The position of sleeping site relative to the last feeding site of the day and the first feeding site of the subsequent morning indicated a strategy closer to that of a multiple central place forager than of a central place forager. These results suggest that territory defense and food access may play an important role in sleeping site use of white-headed langurs [Current Zoology 57 (3): 260-268, 2011]. 展开更多
关键词 White-headed langur Trachypithecus leucocephalus Sleeping site Limestone habitat
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Rollover prevention control for a four in-wheel motors drive electric vehicle on an uneven road 被引量:5
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作者 ZHANG LiPeng LI Liang QI BingNan 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2018年第6期934-948,共15页
When a four in-wheel motors drive electric vehicle with a specific wheels mass is running on an uneven road and transient steering occurs in the meantime, the joint action of the large unsprung dynamic load and the ce... When a four in-wheel motors drive electric vehicle with a specific wheels mass is running on an uneven road and transient steering occurs in the meantime, the joint action of the large unsprung dynamic load and the centrifugal force may cause the vehicle to rollover. To avoid the above accident, a rollover prevention control method based on active distribution of the in-wheel motors driving torques is investigated. First, tile rollover evolution process of the four in-wheel motors drive electric vehicle under the described operating condition is analyzed. Next, a multiple degrees of freedom vehicle dynamics model including an uneven road tyre model is established, and the rollover warning threshold is determined according to the load transfer ratio. Then, the hypothesis of the effects of unsprung mass on the vehicle roll stability on a plat road and on an uneven road is verified respectively. Finally, a rollover prevention controller is designed based on the distribution of the four wheels driving torques with sliding mode control, and the control effect is verified by simulations. The conclusion shows that, once the wheels mass does not match road conditions, the large unsprung mass may play a detrimental role on the vehicle roll stability on an uneven road, which is different from the beneficial role of large unsprung mass on the vehicle roll stability on a plat road. With the aforementioned rollover prevention controller, the vehicle rollover, which is caused by the coupling effect between large unsprung dynamic load and suspension potential energy on an uneven road, can be avoided effectively. 展开更多
关键词 electric vehicle in-wheel motor drive roll stability uneven road
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Global stability of SEIVR epidemic model with generalized incidence and preventive vaccination 被引量:1
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作者 Muhammad Altaf Khan Yasir Khan +1 位作者 Qaiser Badshah Saeed Islam 《International Journal of Biomathematics》 2015年第6期203-221,共19页
In this paper, an SEIVR epidemic model with generalized incidence and preventive vaccination is considered. First, we formulate the model and obtain its basic properties. Then, we find the equilibrium points of the mo... In this paper, an SEIVR epidemic model with generalized incidence and preventive vaccination is considered. First, we formulate the model and obtain its basic properties. Then, we find the equilibrium points of the model, the disease-free and the endemic equilibrium. The stability of disease-free and endemic equilibrium is associated with the basic reproduction number R0. If the basic reproduction number R0〈 1, the disease- free equilibrium is locally as well as globally asymptotically stable. Moreover, if the basic reproduction number R0 〉 1, the disease is uniformly persistent and the unique endemic equilibrium of the system is locally as well as globally asymptotically stable under certain conditions. Finally, the numerical results justify the analytical results. 展开更多
关键词 SEIVR reproduction number global stability numerical results.
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Evaluating the blast mitigation performance of hard/soft composite structures through field explosion experiment and numerical analysis 被引量:5
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作者 Fengyuan Yang Zhijie Li +1 位作者 Zhuo Zhuang Zhanli Liu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2022年第1期27-36,共10页
The application of hard/soft composite structure in personnel armor for blast mitigation is relatively practical and effective in realistic protection engineering,such as the shell/liner system of the helmet.However,t... The application of hard/soft composite structure in personnel armor for blast mitigation is relatively practical and effective in realistic protection engineering,such as the shell/liner system of the helmet.However,there is still lacking a reliable experi-mental methodology to effectively evaluate the blast mitigation performance when the structure directly contacts the protected target,which limits the development of protection structures.In this paper,we proposed a new method to evaluate experi-mentally and numerically the blast mitigation performance of hard/soft composite structures.The blast mitigation mechanism is analyzed.The hard/soft structures were composed of ultra-high molecular weight polyethylene(UHMWPE)composite and expanded polyethylene(EPE)foam.In field explosion experiment,a 7.0 kg trinitrotoluene(TNT)spherical charge is used to generate blast waves at a 3.8 m stand-off distance.A pressure test device is designed to support the tested structure and measure the transmitted blast pressure pulses after passing through the structure.Experimental results indicate that the hard/soft structures can mitigate the blast pressure pulse into the triangular pressure pulse,through making the pulse profile flatter,reducing the pressure amplitude,and delaying the pulse arrival time.Specifically,the combination of 7 mm UHMWPE composite and 20 mm EPE foam can reduce the blast pressure amplitude by 40%.Correspondingly,the finite element simulation is also carried out to understand the blast mitigation mechanism.The numerical results indicate that the regulation for blast pressure pulses mainly complete at the hard/soft interface,which is attributed to the reflection of pressure waves at the interface and the deformation of the soft layer compressed by the hard layer possessing kinetic energy.Furthermore,based on these analyses,the corresponding theoretical model is proposed,and it can well explain the experimental and numerical results.This study is meaningful for evaluating and designing high-performance blast mitigation structures. 展开更多
关键词 Blast mitigation Composite structure Field explosion experiment Numerical simulation
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