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Evaluating the Impacts of Human Activities on Diversity, Abundance, and Distribution of Large Mammals in Nimule National Park, South Sudan
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作者 Abdallah Gordon Shazali Joseph Mayindo Mayele +1 位作者 Joel Emmanuel Saburi Jubara Nadlin 《Open Journal of Ecology》 2024年第5期483-507,共25页
Globally, human activities have a significant impact on the diversity, abundance, and distribution of large mammals in Protected Areas (PAs). These disturbances increase human pressure on biodiversity and species habi... Globally, human activities have a significant impact on the diversity, abundance, and distribution of large mammals in Protected Areas (PAs). These disturbances increase human pressure on biodiversity and species habitats, highlighting the need for conservation. This study aimed to assess the abundance and distribution of large mammals in different habitat types within Nimule National Park (NNP) and understand the impacts of human activities on them. Data on the abundance and distribution of large mammals and their respective habitat types were collected through line transect surveys. Human activity signs were observed and recorded along the transect lines. To estimate the impacts of human activities on the diversity, abundance, and distribution of large mammal species, as well as to identify any significant differences between them and their habitat types, the study utilized the Kruskal Wallis test, Polynomial multiple regressions, and diversity indices. The findings from the Shannon-Weiner and Simpson indices indicated that large mammal species were more diverse inside the park (H’ = 1.136;D = 0.570) compared to the buffer zone (H’ = 0.413;D = 0.171), with 85% (443 out of 510 samples) recorded within Nimule National Park. The species abundance showed a semi-balanced status (0.58). The diversity results among different habitat types revealed that large mammals were more diverse and highly distributed in both open woodlands (244) and dense woodlands (192), while riverine vegetation had the lowest diversity (8). Statistical tests demonstrated a highly significant difference at a 99% confidence interval (p-value = 0.01) between habitat types and identified species of large mammals. Additionally, the results highlighted the high abundance of Uganda kob (274), baboons (141), and warthog (57) across most habitat types, accounting for at least 75% of their distribution. The most prevalent human activities observed were cattle footprints (27%) and cattle dung (14%). Human footprints and tree cutting combined accounted for 9%, indicating the practice of livestock grazing, poaching, encroachment, and fuelwood collection by local communities. However, these activities did not appear to significantly impact the diversity, abundance, and distribution of large mammals in Nimule National Park. Therefore, it is crucial to foster shared responsibilities and engage relevant stakeholders in the management and conservation of large wildlife species. Regular community awareness programs should be implemented to cultivate a sense of ownership. Moreover, it is recommended that a comprehensive survey be conducted on the population status of all mammal species in Nimule National Park, including its surrounding Buffer Zone. Monitoring the impact of human activities on their behavior and habitats using satellite images should also be carried out at least every five to ten years. 展开更多
关键词 Diversity of large Mammals Abundance and distribution IMPACTS Biodiversity Conservation Human Activities Nimule National Park South Sudan
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Challenges and Considerations in Developing and Architecting Large-Scale Distributed Systems
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作者 Ion-Alexandru Secara 《International Journal of Internet and Distributed Systems》 2020年第1期1-13,共13页
This paper investigates large-scale distributed system design. It looks at features, main design considerations and provides the Netflix API, Cassandra and Oracle as examples of such systems. Moreover, the paper inves... This paper investigates large-scale distributed system design. It looks at features, main design considerations and provides the Netflix API, Cassandra and Oracle as examples of such systems. Moreover, the paper investigates the challenges of designing, developing, deploying, and maintaining such systems, in regard to the features presented. Finally, the paper discusses aspects of available solutions and current practices to challenges that large-scale distributed systems face. 展开更多
关键词 distributed Systems CONCURRENCY large-SCALE
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Photosynthetic characteristics and nitrogen distribution of large-spike wheat in Northwest China 被引量:4
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作者 WANG Li-fang CHEN Juan SHANGGUAN Zhou-ping 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2016年第3期545-552,共8页
The leaf photosynthesis and nitrogen(N) translocation in three large-spike lines and control cultivar(Xi'nong 979) of winter wheat(Triticum aestivum L.) were studied in 2010–2011 and 2011–2012. The objectives... The leaf photosynthesis and nitrogen(N) translocation in three large-spike lines and control cultivar(Xi'nong 979) of winter wheat(Triticum aestivum L.) were studied in 2010–2011 and 2011–2012. The objectives of this study were to investigate the differences in the physiological characteristics of large-spike lines and control cultivar and identify the limiting factors that play a role in improving the yield of breeding materials. The average yield, grain number per spike, kernel weight per spike, and 1 000-kernel weight of the large-spike lines were 16.0, 26.8, 42.6, and 15.4%, respectively, significantly higher than those of control. The average photosynthetic rates(Pn) were not significant between the large-spike lines and control cultivar during the active growth period. The average PSII maximum energy conversion efficiency(Fv/Fm), PSII actual quantum efficiency(Ф(PSII)), photochemical quenching coefficient(qP), PSII reaction center activity(Fv′/Fm′) and water-use efficiency(WUE) of the large-spike lines were 1.0, 5.1, 3.6, 0.8, and 43.4%, respectively, higher than those of the control during the active growth stages. The N distribution proportions in different tissues were ranked in the order of grains〉culms+sheathes〉rachis+glumes〉flag leaves〉penultimate leaves〉remain leaves. This study suggested that utilization of the large-spike wheat might be a promising approach to obtain higher grain yield in Northwest China. 展开更多
关键词 wheat nitrogen distribution large-spike lines photosynthetic characteristics yield
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Thickness distribution of large scale metallic sheet by EB-PVD on rotating substrate
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作者 单英春 赫晓东 +1 位作者 李明伟 李垚 《中国有色金属学会会刊:英文版》 CSCD 2005年第S3期232-235,共4页
A two-dimensional kinetic Monte-Carlo(KMC) method was used to approach the thickness distribution of large scale metallic sheet deposited by electron beam physical vapor deposition(EB-PVD) on rotating substrate. The K... A two-dimensional kinetic Monte-Carlo(KMC) method was used to approach the thickness distribution of large scale metallic sheet deposited by electron beam physical vapor deposition(EB-PVD) on rotating substrate. The KMC model involves incident atom attachment, adatom diffusion and adatom detachment. The effective deposition rate and effective incident angle along substrate radial were studied as influencing factors of sheet thickness distribution. The KMC simulation results indicate that incident angle is a very important factor to affect the sheet thickness distribution as well as theory deposition mass. The experiments results show that the KMC model can predict the thickness distribution of large scale sheet deposited by EB-PVD on rotating substrate. 展开更多
关键词 thickness distribution large scale METALLIC SHEET KINETIC Monte-Carlo method ROTATING SUBSTRATE electric beam physical vapor deposition(EB-PVD)
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A Tabu Search Algorithm for Fast Restoration of Large Area Breakdown in Distribution Systems
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作者 Jian LIU Hongli CHENG +1 位作者 Xiaojun SHI Jingqiu XU 《Energy and Power Engineering》 2010年第1期1-5,共5页
To restore the distribution systems in emergency states with the minimum load shedding, a novel Tabu search approach is put forward. The set of tripped switches is used as candidate solution. Some virtual tripped node... To restore the distribution systems in emergency states with the minimum load shedding, a novel Tabu search approach is put forward. The set of tripped switches is used as candidate solution. Some virtual tripped nodes are defined at the ends of the terminal nodes and by the source nodes. The neighborhood searching is committed by moving a tripped switch to the adjacent node of its upper stream and down stream, respectively. A Tabu list is formed for the tripped switches. The index is to energize as much as possible loads with as less as possible operated times. The electrical limitations and the voltage criterions are used as constrictions. The global aspiration criterion is adopted. An example is given, which shows that the proposed approach is feasible and can deal with complicated indexes. 展开更多
关键词 distribution systems RESTORATION large area BREAK DOWN load SHEDDING Tabu SEARCH
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The Security Correction of Large Consumers Long-Term Direct Power Trading Based on DC Power Transfer Distribution Factor
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作者 Ouyang Xu Zhenggang Wang +3 位作者 Bifeng Lv Jinguo Zhang Jiangang Yao Bin Wang 《Energy and Power Engineering》 2017年第4期365-375,共11页
The experiments of large consumers direct power trading is conducting in china nationwide, and it’s important to the reform of electricity market. To compensated efficiencies in security correction of large consumers... The experiments of large consumers direct power trading is conducting in china nationwide, and it’s important to the reform of electricity market. To compensated efficiencies in security correction of large consumers direct power trading, a novel security correction method based on DC power transfer distribution factor was proposed. Using the presented method to comply security correction, all the transactions that satisfy the specific requirements of maximizing social welfare are able to enter security correction process, and when the power of transmission line is out of limit, this method avoid the transaction which causes this problem is abandoned directly by introducing supplement transactions. The simulation has shown that the proposed security correction method of large consumers direct power trading based on DC power transfer distribution factor is effective. 展开更多
关键词 large CONSUMERS Direct POWER TRADING DC POWER TRANSFER distribution Factor SECURITY CORRECTION Electricity Markets
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Large Wood Volume and Longitudinal Distribution in Channel Segments Draining Catchments with Different Land Use, Chile
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作者 A. Iroumé L. Mao +2 位作者 H. Ulloa C. Ruz A. Andreoli 《Open Journal of Modern Hydrology》 2014年第2期57-66,共10页
The storage, longitudinal distribution and recruitment processes of in-stream large wood (LW) were studied comparing channel segments draining four Chilean mountain catchments with different land use. The segments wer... The storage, longitudinal distribution and recruitment processes of in-stream large wood (LW) were studied comparing channel segments draining four Chilean mountain catchments with different land use. The segments were divided into relatively uniform reaches of different lengths and surveyed for LW (piece dimensions, position in the channel, orientation to flow and aggregation) and stream morphology (slope and bank full channel width and depth) characterizations. LW volume stored in the Pichun, El Toro and Vuelta de Zorra study channels are within the range informed in international researches from streams draining catchments with similar forest covers. However, the 1057 m3/ha of LW stored in Tres Arroyos is extremely high and in the same order of magnitude than the reports from old-growth forests in the Pacific Northwest of USA. The size of the area that can potentially provide wood to streams depends on the wood supply mechanisms within any catchment, and the LW stored in the study segments increases as the size of this area increases. This study aims to contribute to the knowledge on the effects of LW in mountain channels, gathering new information and expanding investigations developed in Chile since 2008. This research was carried out within the framework of Project FONDECYT 11106209. 展开更多
关键词 large WOOD WOOD STORAGE LW Longitudinal distribution MOUNTAIN CATCHMENTS
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Non-uniform temperature distribution of the main reflector of a large radio telescope under solar radiation
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作者 Shan-Xiang Wei De-Qing Kong Qi-Ming Wang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2021年第11期233-242,共10页
The non-uniform temperature distribution of the main reflector of a large radio telescope may cause serious deformation of the main reflector,which will dramatically reduce the aperture efficiency of a radio telescope... The non-uniform temperature distribution of the main reflector of a large radio telescope may cause serious deformation of the main reflector,which will dramatically reduce the aperture efficiency of a radio telescope.To study the non-uniform temperature field of the main reflector of a large radio telescope,numerical calculations including thermal environment factors,the coefficients on convection and radiation,and the shadow boundary of the main reflector are first discussed.In addition,the shadow coverage and the non-uniform temperature field of the main reflector of a 70-m radio telescope under solar radiation are simulated by finite element analysis.The simulation results show that the temperature distribution of the main reflector under solar radiation is very uneven,and the maximum of the root mean square temperature is 12.3℃.To verify the simulation results,an optical camera and a thermal imaging camera are used to measure the shadow coverage and the non-uniform temperature distribution of the main reflector on a clear day.At the same time,some temperature sensors are used to measure the temperature at some points close to the main reflector on the backup structure.It has been verified that the simulation and measurement results of the shadow coverage on the main reflector are in good agreement,and the cosine similarity between the simulation and the measurement is above 90%.Despite the inevitable thermal imaging errors caused by large viewing angles,the simulated temperature field is similar to the measured temperature distribution of the main reflector to a large extent.The temperature trend measured at the test points on the backup structure close to the main reflector without direct solar radiation is consistent with the simulated temperature trend of the corresponding points on the main reflector with the solar radiation.It is credible to calculate the temperature field of the main reflector through the finite element method.This work can provide valuable references for studying the thermal deformation and the surface accuracy of the main reflector of a large radio telescope. 展开更多
关键词 large radio telescope finite element analysis solar radiation shadow coverage temperature distribution
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Hydrogen and steam distribution following a small-break LOCA in large dry containment
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作者 DENG Jian CAO Xuewu 《Nuclear Science and Techniques》 SCIE CAS CSCD 2007年第3期181-185,共5页
The hydrogen deflagration is one of the major risk contributors to threaten the integrity of the containment in a nuclear power plant, and hydrogen control in the case of severe accidents is required by nuclear regula... The hydrogen deflagration is one of the major risk contributors to threaten the integrity of the containment in a nuclear power plant, and hydrogen control in the case of severe accidents is required by nuclear regulations. Based on the large dry containment model developed with the integral severe-accident analysis tool, a small-break loss-of-coolant-accident (LOCA) without HPI, LPI, AFW and containment sprays, leading to the core degradation and large hydrogen generation, is calculated. Hydrogen and steam distribution in containment compartments is investi- gated. The analysis results show that significant hydrogen deflagration risk exits in the reactor coolant pump (RCP) compartment and the cavity during the early period, if no actions are taken to mitigate the effects of hydrogen accu- mulation. 展开更多
关键词 氢蒸发 严重事故 氢分布 小破口事故
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Precise large deviation result for heavy-tailed random sums and applications to risk theory
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作者 杨洋 林金官 《Journal of Southeast University(English Edition)》 EI CAS 2010年第3期498-501,共4页
The differences between two sequences of nonnegative independent and identically distributed random variables with sub-exponential tails and the random index are studied. The random index is a strictly stationary rene... The differences between two sequences of nonnegative independent and identically distributed random variables with sub-exponential tails and the random index are studied. The random index is a strictly stationary renewal counting process generated by some negatively associated random variables. Using a revised large deviation result of partial sums, the elementary renewal theorem and the central limit theorem of negatively associated random variables, a precise large deviation result is derived for the random sums. The result is applied to the customer-arrival-based insurance risk model. Some uniform asymptotics for the ruin probabilities of an insurance company are obtained as the number of customers or the time tends to infinity. 展开更多
关键词 precise large deviation random sum sub-exponential distribution renewal counting process customer-arrival-based insurance risk model
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Clinical features and outcomes of diffuse large B-cell lymphoma based on nodal or extranodal primary sites of origin:Analysis of 1,085 WHO classified cases in a single institution in China 被引量:25
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作者 Yuankai Shi Ying Han +12 位作者 Jianliang Yang Peng Liu Xiaohui He Changgong Zhang Shengyu Zhou Liqiang Zhou Yan Qin Yongwen Song Yueping Liu Shulian Wang Jing Jin Lin Gui Yan Sun 《Chinese Journal of Cancer Research》 SCIE CAS CSCD 2019年第1期152-161,共10页
Objective: To explore the clinicobiologic features and outcomes of diffuse large B-cell lymphoma(DLBCL)patients in China according to the primary site.Methods: A total of 1,085 patients diagnosed with DLBCL in Nationa... Objective: To explore the clinicobiologic features and outcomes of diffuse large B-cell lymphoma(DLBCL)patients in China according to the primary site.Methods: A total of 1,085 patients diagnosed with DLBCL in National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College during a 6-year period were enrolled. Their clinical characteristics and outcomes were analyzed according to the primary site.Results: In the 1,085 patients, 679(62.6%) cases were nodal DLBCL(N-DLBCL) and 406 cases(37.4%) were extranodal DLBCL(EN-DLBCL). The most common sites of N-DLBCL were lymphonodus(64.8%), Waldeyer's ring(19.7%), mediastinum(12.8%) and spleen(2.7%), while in EN-DLBCL, stomach(22.4%), intestine(16.0%),nose and sinuses(8.9%), testis(8.4%), skin(7.9%), thyroid(6.9%), central nervous system(CNS)(6.4%), breast(5.7%), bone(3.4%), and salivary gland(2.7%) were most common. N-DLBCL patients tend to present B symptoms, bulky disease, and elevated LDH more often, while age >60 years, extranodal sites >1, Ann Arbor stage I or II, bone marrow involvement, and Ki-67 index >90% were usually seen in EN-DLBCL. The 5-year overall survival(OS) rate and progression-free survival(PFS) rate for all patients were 62.5% and 54.2%. The 5-year OS rate for patients with N-DLBCL and EN-DLBCL were 65.5% and 56.9%(P=0.008), and the 5-year PFS were57.0% and 49.0%(P=0.020). Waldeyer's ring originated DLBCL possessed the highest 5-year OS rate(83.6%) and PFS rate(76.9%) in N-DLBCL. The top five EN-DLBCL subtypes with favorable prognosis were stomach,breast, nose and sinuses, lung, salivary gland, with 5-year OS rate: 70.3%, 69.6%, 69.4%, 66.7% and 63.6%,respectively. While CNS, testis, oral cavity and kidney originated EN-DLBCL faced miserable prognosis, with 5-year OS rate of 26.9%, 38.2%, and 42.9%.Conclusions: In our study, primary sites were associated with clinical characteristics and outcomes. Compared with EN-DLBCL, N-DLBCL had better prognosis. 展开更多
关键词 Diffuse large B-CELL lymphoma(DLBCL) distribution NODAL EXTRANODAL
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Cerium dioxide with large particle size prepared by continuous precipitation 被引量:3
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作者 李梅 王觅堂 +2 位作者 柳召刚 胡艳宏 吴锦绣 《Journal of Rare Earths》 SCIE EI CAS CSCD 2009年第6期991-996,共6页
Cerium dioxide(CeO2) has attracted much attention and has wide applications such as automotive exhaust catalysts,polishing materials for optical glasses and additives for advanced glasses,as well as cosmetic materials... Cerium dioxide(CeO2) has attracted much attention and has wide applications such as automotive exhaust catalysts,polishing materials for optical glasses and additives for advanced glasses,as well as cosmetic materials.The particle size and its distribution are key factors to the performance of the materials in the functional applications.However,control of particle size is still a challenge in materials synthesis.Therefore,continuous precipitation of cerium oxalate(precursor of ceria) was carried out at dif... 展开更多
关键词 cerium oxalate continuous precipitation large particle particle size distribution MORPHOLOGY rare earths
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Energy consumption of large space atrium under nozzle outlet during winter season 被引量:1
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作者 赵惠忠 林志芬 +3 位作者 陈飞 黄晨 张敏 王丽慧 《Journal of Central South University》 SCIE EI CAS 2009年第S1期219-223,共5页
Based on the thermal and velocity layer's theory,the experimental setup was established on large space atrium under nozzle outlet. A series of winter experiments were accomplished and the following conclusions cou... Based on the thermal and velocity layer's theory,the experimental setup was established on large space atrium under nozzle outlet. A series of winter experiments were accomplished and the following conclusions could be drawn. At the sunny day of winter in Shanghai,the thermal and velocity layer are similar. The height of the both layer is 10-30 mm,and the temperature gratitude is 5-10 ℃ /m. Decreasing the angle of the nozzle outlet can increase the layer height dramatically. The maximum temperature difference of the occupant zone has relation with the angle of the nozzle outlet. The less the angle of the nozzle outlet is set,the greater the temperature difference is. The occupant temperature differences at these angles of the nozzle outlet are 5.1-4.4 ℃. The velocity of the wind is 0.02 and 0.17 m/s and they can accord with design demand. So,it can decrease the temperature gratitude by about 30% and it can save 10%-15% energy consumption. 展开更多
关键词 large space ATRIUM energy consumption WINTER NOZZLE OUTLET air distributIONS
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Large Deviations for Random Sums on Some Kind of Heavy-tailed Classes in Risk Models 被引量:3
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作者 KONG Fan-chao WANG Jin-liang 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2006年第1期71-79,共9页
This paper is a further investigation into the large deviations for random sums of heavy-tailed,we extended and improved some results in ref. [1] and [2]. These results can applied to some questions in Insurance and F... This paper is a further investigation into the large deviations for random sums of heavy-tailed,we extended and improved some results in ref. [1] and [2]. These results can applied to some questions in Insurance and Finance. 展开更多
关键词 renewal risk model heavy-tailed distribution large deviation renewal counting process
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LARGE DEVIATIONS AND MODERATE DEVIATIONS FOR SUMS OF NEGATIVELY DEPENDENT RANDOM VARIABLES 被引量:1
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作者 刘莉 万成高 冯艳钦 《Acta Mathematica Scientia》 SCIE CSCD 2011年第1期344-352,共9页
In this article, we obtain the large deviations and moderate deviations for negatively dependent (ND) and non-identically distributed random variables defined on (-∞, +∞). The results show that for some non-ide... In this article, we obtain the large deviations and moderate deviations for negatively dependent (ND) and non-identically distributed random variables defined on (-∞, +∞). The results show that for some non-identical random variables, precise large deviations and moderate deviations remain insensitive to negative dependence structure. 展开更多
关键词 large deviation moderate deviation negative dependence non-identical distribution
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Global exponentially stability for time-delay and time-varying measure large scale systems with impulsive effects
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作者 刘云龙 高存臣 +1 位作者 李云艳 刘现明 《中南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2009年第S1期175-180,共6页
The global exponentially stability was studied for time-delay and time-varying measure large scale systems with impulsive effects. Firstly, the concepts are drawn for the functional category. Secondly, some sufficient... The global exponentially stability was studied for time-delay and time-varying measure large scale systems with impulsive effects. Firstly, the concepts are drawn for the functional category. Secondly, some sufficient conditions of the uniformly stability and the global exponentially stability are given for the above systems through defining a Lyapunov function of the weighting sum of the variable absolute by using the Lyapunov function method and the comparison principle. At the same time, the new conclusion of stability of these systems is more universal and contains the existing results. Finally, an example is given to illustrate the feasibility and validity of the obtained results. 展开更多
关键词 distributional DERIVATIVE TIME-DELAY MEASURE large scale systems IMPULSIVE GLOBAL EXPONENTIALLY stability
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The Interaction of C-Band Microwaves with Large Plasma Sheets
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作者 DING Liang HUO Wenqing +1 位作者 YANG Xinjie XU Yuemin 《Plasma Science and Technology》 SCIE EI CAS CSCD 2012年第1期9-13,共5页
A large plasma sheet 60 cm×60 cm×2 cm in size was generated using a hollow cathode, and measurements were conducted for interactions including transmission, reflection and absorption. With different discharg... A large plasma sheet 60 cm×60 cm×2 cm in size was generated using a hollow cathode, and measurements were conducted for interactions including transmission, reflection and absorption. With different discharge parameters, plasma sheets can vary and influence microwave strength. Microwave reflection decreases when the discharge current rises, and the opposite occurs in transmission. The C-band microwave is absorbed when it is propagated through large plasma sheets at higher pressure. When plasma density and collision frequency are fitted with incident microwave frequency, a large amount of microwave energy is consumed. Reflection, transmission and absorption all exist simultaneously. Plasma sheets are an attractive alternative to microwave steering at low pressure, and the microwave reflection used in receiving radar can be altered by changing the discharge parameters. 展开更多
关键词 hollow cathode discharge microwave effect large plasma sheet density distribution
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Large Deviations for Sums of Heavy-tailed Random Variables
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作者 郭晓燕 孔繁超 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2007年第2期282-289,共8页
This paper is a further investigation of large deviations for sums of random variables Sn=i=1∑n Xi and S(t)=i=1∑N(t)Xi,(t≥0), where {X_n,n≥1) are independent identically distribution and non-negative random... This paper is a further investigation of large deviations for sums of random variables Sn=i=1∑n Xi and S(t)=i=1∑N(t)Xi,(t≥0), where {X_n,n≥1) are independent identically distribution and non-negative random variables, and {N(t),t≥0} is a counting process of non-negative integer-valued random variables, independent of {X_n,n≥1}. In this paper, under the suppose F∈G, which is a bigger heavy-tailed class than C, proved large deviation results for sums of random variables. 展开更多
关键词 large deviation heavy-tailed distribution strongly subexponential distribution lognormal distribution
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Using Quantile Regression to Detect Relationships between Large-scale Predictors and Local Precipitation over Northern China 被引量:1
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作者 FAN Lijun XIONG Zhe 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2015年第4期541-552,共12页
Quantile regression(QR) is proposed to examine the relationships between large-scale atmospheric variables and all parts of the distribution of daily precipitation amount at Beijing Station from 1960 to 2008. QR is ... Quantile regression(QR) is proposed to examine the relationships between large-scale atmospheric variables and all parts of the distribution of daily precipitation amount at Beijing Station from 1960 to 2008. QR is also applied to evaluate the relationship between large-scale predictors and extreme precipitation(90th quantile) at 238 stations in northern China.Finally, QR is used to fit observed daily precipitation amounts for wet days at four sample stations. Results show that meridional wind and specific humidity at both 850 h Pa and 500 h Pa(V850, SH850, V500, and SH500) strongly affect all parts of the Beijing precipitation distribution during the wet season(April–September). Meridional wind, zonal wind, and specific humidity at only 850 h Pa(V850, U850, SH850) are significantly related to the precipitation distribution in the dry season(October–March). Impacts of these large-scale predictors on the daily precipitation amount with higher quantile become stronger, whereas their impact on light precipitation is negligible. In addition, SH850 has a strong relationship with wet-season extreme precipitation across the entire region, whereas the impacts of V850, V500, and SH500 are mainly in semi-arid and semi-humid areas. For the dry season, both SH850 and V850 are the major predictors of extreme precipitation in the entire region. Moreover, QR can satisfactorily simulate the daily precipitation amount at each station and for each season, if an optimum distribution family is selected. Therefore, QR is valuable for detecting the relationship between the large-scale predictors and the daily precipitation amount. 展开更多
关键词 quantile regression large-scale predictors precipitation distribution predictor–precipitation relationship northern China
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Large Deviations for a Generalized Compound Renewal Risk Model
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作者 GA O Shan 《Chinese Quarterly Journal of Mathematics》 CSCD 2010年第3期399-406,共8页
This paper extends the ordinary renewal risk model to the case where the premium income process,based on a renewal counting process,is no longer a linear function;and the total claim amount process is described by a c... This paper extends the ordinary renewal risk model to the case where the premium income process,based on a renewal counting process,is no longer a linear function;and the total claim amount process is described by a compound renewal process.For this realistic risk model,the large deviations for the claim surplus process is investigated. 展开更多
关键词 heavy-tailed distribution renewal counting process large deviation
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