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Probabilistic small signal stability analysis of power system with wind power and photovoltaic power based on probability collocation method
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作者 Cai Yan Linli Zhou +2 位作者 Wei Yao Jinyu Wen Shijie Cheng 《全球能源互联网:英文版》 2019年第1期19-28,共10页
Recently, with increasing improvements in the penetration of wind power and photovoltaic power in the world, probabilistic small signal stability analysis(PSSSA) of a power system consisting of multiple types of renew... Recently, with increasing improvements in the penetration of wind power and photovoltaic power in the world, probabilistic small signal stability analysis(PSSSA) of a power system consisting of multiple types of renewable energy has become a key problem. To address this problem, this study proposes a probabilistic collocation method(PCM)-based PSSSA for a power system consisting of wind farms and photovoltaic farms. Compared with the conventional Monte Carlo method, the proposed method meets the accuracy and precision requirements and greatly reduces the computation;therefore, it is suitable for the PSSSA of this power system. Case studies are conducted based on a 4-machine 2-area and New England systems, respectively. The simulation results show that, by reducing synchronous generator output to improve the penetration of renewable energy, the probabilistic small signal stability(PSSS) of the system is enhanced. Conversely, by removing part of the synchronous generators to improve the penetration of renewable energy, the PSSS of the system may be either enhanced or deteriorated. 展开更多
关键词 RENEWABLE energy PROBABILISTIC small signal stability PROBABILISTIC COLLOCATION method Wind POWER Photovoltaic POWER
确定论与概率论相结合的小型模块化压水堆应急堆芯冷却系统配置研究
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作者 高颖贤 张航 +3 位作者 邱志方 刘兆东 李美福 曾未 《核动力工程》 EI CAS CSCD 北大核心 2019年第3期175-179,共5页
基于小型模块化压水堆设计特点,分别采用确定论方法和概率论方法分析了事故工况下的应急堆芯冷却系统配置策略。初步分析表明:确定论方法和概率论方法对于安注箱(ACC)的配置需求存在明显差异;在确保安全目标实现的前提下尽可能简化应急... 基于小型模块化压水堆设计特点,分别采用确定论方法和概率论方法分析了事故工况下的应急堆芯冷却系统配置策略。初步分析表明:确定论方法和概率论方法对于安注箱(ACC)的配置需求存在明显差异;在确保安全目标实现的前提下尽可能简化应急堆芯冷却系统设计,建议可取消安全级的ACC,在非能动堆芯补水箱(CMT)失效后利用其他已有注水水源来平衡设计,如能动余热排出系统增设换料水箱安注功能。 展开更多
关键词 小型模块化压水堆 确定论 概率论 安注箱
Robust Beamforming for Secured Wireless Power Transfer in MIMO Magnetic Resonant Coupling System:A Probabilistic Approach 预览
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作者 Ling Xing Kaikai Deng Feifei Gao 《中国通信:英文版》 SCIE CSCD 2019年第1期97-107,共11页
Wireless power transfer(WPT)to support mobile and portable devices is an emerging wireless technique.Among all kinds of approaches,magnetic resonance coupling(MRC)is an excellent one for mid-range WPT,which provides b... Wireless power transfer(WPT)to support mobile and portable devices is an emerging wireless technique.Among all kinds of approaches,magnetic resonance coupling(MRC)is an excellent one for mid-range WPT,which provides better mobility,flexibility,and convenience due to its simplicity in hardware implementation and longer transmission distances.In this paper,we consider an MRCWPT system with multiple power transmitters,one intended power receiver and multiple unintended power receivers.We investigate the probabilistic robust beamforming designs and provide efficient algorithms to achieve the local optimums under two different criteria,i.e.,total source power minimization problem and min-max unintended receiving power restriction problem.As the problems are quite typical in robust design situations,our proposed robust beamformers can be conveniently applied to other probabilistic robust design problems,thus reduce the complexity as well as improve the beamforming performance.Numerical results demonstrate that the proposed algorithms can significantly improve the performance as well as the robustness of the WPT system. 展开更多
关键词 MAGNETIC resonance coupling wireless POWER transfer BEAMFORMING PROBABILISTIC robustness POWER security
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高层建筑施工现场危险区域识别及评估方法研究
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作者 华莹 何军 赵金城 《施工技术》 CAS 2019年第6期100-104,共5页
考虑施工阶段和危险源空间分布,将高层建筑施工现场划分为普遍适用的18个危险区域,由风险因素归纳进行相关性分析,基于Normal Copula函数构建危险区域风险评估概率方法,结合作业条件危险性评价数据,对提出的高层建筑施工现场危险区域进... 考虑施工阶段和危险源空间分布,将高层建筑施工现场划分为普遍适用的18个危险区域,由风险因素归纳进行相关性分析,基于Normal Copula函数构建危险区域风险评估概率方法,结合作业条件危险性评价数据,对提出的高层建筑施工现场危险区域进行风险性评级、采用简化的随机场模型进行联合概率评估。该方法分析结果能较好地反映建筑施工现场风险水平。 展开更多
关键词 高层建筑 危险源 概率 评估 安全
Probabilistic assessment of rock slopes stability using the response surface approach-A case study 预览
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作者 Hassan Basahel Hani Mitri 《矿业科学技术学报:英文版》 CSCD 2019年第3期357-370,共14页
This paper examines the stability condition of a jointed rock slope in the south western region of Saudi Arabia using deterministic and probabilistic approaches,under both dry and wet conditions.The study area is char... This paper examines the stability condition of a jointed rock slope in the south western region of Saudi Arabia using deterministic and probabilistic approaches,under both dry and wet conditions.The study area is characterized by complex geology in rugged terrains.The stability analysis is carried out using the code FLAC3D to generate a 3-dimensional,ubiquitous joint model,to determine the influence of the dominant,unfavourable discontinuity orientation with respect to the slope face.The deterministic analysis is first implemented using the mean values of the selected random variables,namely the dip,dip direction and friction angle of the dominant discontinuity set,and the stability condition is assessed with a factor of safety based on the classical frictional joint constitutive model.A Box-Behnken design(BBD)approach is then adopted to create the surface response function as a second order polynomial for the factor of safety.To do so,fifteen FLAC3D models are generated in accordance with the BBD.Based on this,10,000 simulations of different slope realizations are carried out using Monte-Carlo simulation technique,and the probability of unsatisfactory of performance of the rock slope is assessed.It is shown that the probabilistic approach provides more insight and confidence in the stability condition of the rock slope,both under dry and steady state heavy rainfall conditions.A discussion is presented on the significance of accepting lower safety factors when heavy rainfall conditions are encountered. 展开更多
关键词 ROCK SLOPE STABILITY Box-Behnken design PROBABILISTIC analysis of SLOPES RESPONSE surface
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A Satellite Communication System Transmission Scheme Based on Probabilistic Shaping 预览
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作者 Wei Zhang Xia Sheng +1 位作者 Xishuo Wang Qi Zhang 《中国通信:英文版》 CSCD 2019年第10期226-233,共8页
In this paper, A transmission scheme based on probabilistic shaping applied to satellite communication systems is proposed. 16QAM is taken as an example to establish a 1GBaud ROF experimental system working in Ka-band... In this paper, A transmission scheme based on probabilistic shaping applied to satellite communication systems is proposed. 16QAM is taken as an example to establish a 1GBaud ROF experimental system working in Ka-band. The experiment results show that the PS-16QAM signal has better performance in terms of bit error rate than the uniform 16QAM, and its performance is close to the uniform 8QAM scheme. 展开更多
关键词 PROBABILISTIC SHAPING SATELLITE COMMUNICATION KA-BAND
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A Survey of 3D Indoor Scene Synthesis
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作者 Song-Hai Zhang Shao-Kui Zhang +1 位作者 Yuan Liang Peter Hall 《计算机科学技术学报:英文版》 SCIE EI CSCD 2019年第3期594-608,共15页
Indoor scene synthesis has become a popular topic in recent years.Synthesizing functional and plausible indoor scenes is an inherently difficult task since it requires considerable knowledge to both choose reasonable ... Indoor scene synthesis has become a popular topic in recent years.Synthesizing functional and plausible indoor scenes is an inherently difficult task since it requires considerable knowledge to both choose reasonable object categories and arrange objects appropriately.In this survey,we propose four criteria which group a wide range of 3D(three-dimensional)indoor scene synthesis techniques according to various aspects(specifically,four groups of categories).It also provides hints,througli comprehensively comparing all the techniques to demonstrate their effectiveness and drawbacks,and discussions of potential remaining problems. 展开更多
关键词 content GENERATION INDOOR SCENE SYNTHESIS layout arrangement PROBABILISTIC model
Learning to Generate Posters of Scientific Papers by Probabilistic Graphical Models
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作者 Yu-Ting Qiang Yan-Wei Fu +3 位作者 Xiao Yu Yan-Wen Guo Zhi-Hua Zhou Leonid Sigal 《计算机科学技术学报:英文版》 SCIE EI CSCD 2019年第1期155-169,共15页
Researchers often summarize their work in the form of scientific posters.Posters provide a coherent and efficient way to convey core ideas expressed in scientific papers.Generating a good scientific poster,however,is ... Researchers often summarize their work in the form of scientific posters.Posters provide a coherent and efficient way to convey core ideas expressed in scientific papers.Generating a good scientific poster,however,is a complex and time-consuming cognitive task,since such posters need to be readable,informative,and visually aesthetic.In this paper, for the first time,we study the challenging problem of learning to generate posters from scientific papers.To this end,a data-driven framework,which utilizes graphical models,is proposed.Specifically,given content to display,the key elements of a good poster,including attributes of each panel and arrangements of graphical elements,are learned and inferred from data.During the inference stage,the maximum a posterior (MAP)estimation framework is employed to incorporate some design principles.In order to bridge the gap between panel attributes and the composition within each panel,we also propose a recursive page splitting algorithm to generate the panel layout for a poster.To learn and validate our model,we collect and release a new benchmark dataset,called NJU-Fudan Paper-Poster dataset,which consists of scientific papers and corresponding posters with exhaustively labelled panels and attributes.Qualitative and quantitative results indicate the effectiveness of our approach. 展开更多
关键词 GRAPHICAL design layout AUTOMATION PROBABILISTIC GRAPHICAL model
Risk-based probabilistic thermal-stress analysis of concrete arch dams
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作者 Narjes SOLTANI Mohammad ALEMBAGHERI Mohammad Houshmand KHANEGHAHI 《结构与土木工程前沿:英文版》 CSCD 2019年第5期1007-1019,共13页
The probabilistic risk of arch dam failure under thermal loading is studied. The incorporated uncertainties, which are defined as random variables, are associated with the most affecting structural (material) properti... The probabilistic risk of arch dam failure under thermal loading is studied. The incorporated uncertainties, which are defined as random variables, are associated with the most affecting structural (material) properties o f concrete and thermal loading conditions. Karaj arch dam is selected as case study. The dam is numerically modeled along with its foundation in three-dimensional space;the temperature and thermal stress distribution is investigated during the operating phase. The deterministic thermal finite element analysis o f the dam is combined with the structural reliability methods in order to obtain thermal response predictions, and estimate the probability o f failure in the risk analysis context. The tensile overstressing failure mode is considered for the reliability analysis. The thermal loading includes ambient air and reservoir temperature variations. The effect o f solar radiation is considered by an increase in the ambient temperatures. Three reliability methods are employed: the first-order second-moment method, the first-order reliability method, and the Monte-Carlo simulation with Latin Hypercube sampling. The estimated failure probabilities are discussed and the sensitivity o f random variables is investigated. Although most of the studies in this line o f research are used only for academic purposes, the results of this investigation can be used for both academic and engineering purposes. 展开更多
关键词 ARCH DAMS PROBABILISTIC analysis thermal STRESS sensitivity RELIABILITY
Spectrally efficient single carrier 400G optical signal transmission
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作者 Jianjun YU 《中国光电子学前沿:英文版》 EI CSCD 2019年第1期15-23,共9页
In this paper,the recent progress on spectrally efficient single carrier(SC)400G optical signal transmission was summarized.By using quadrature phase shift keying(QPSK),16 quadrature amplitude modulation(16QAM)and 64Q... In this paper,the recent progress on spectrally efficient single carrier(SC)400G optical signal transmission was summarized.By using quadrature phase shift keying(QPSK),16 quadrature amplitude modulation(16QAM)and 64QAM,we can realize transmission distance over 10000,6000 and 3000 km,respectively,with large area fiber and all-Raman amplification.To improve the system performance and generate high-order QAM,advanced digital signal processing algorithms such as probabilistic shaping and look-up table pre-distortion are employed to improve the transmission performance. 展开更多
关键词 COHERENT detection digital SIGNAL processing single CARRIER (SC) PROBABILISTIC SHAPING OFDM
Probabilistic estimate of rock mass static and dynamic demands for underground excavation stabilisation 预览
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作者 Ernesto Villaescusa Alan Thompson Christopher Windsor 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第3期481-493,共13页
Excavation damage under high in situ stress depends largely upon the potential block size associated with any violent ejection.The size and shape of the dynamic instability are largely controlled by the location,orien... Excavation damage under high in situ stress depends largely upon the potential block size associated with any violent ejection.The size and shape of the dynamic instability are largely controlled by the location,orientation and extent of the pre-existing geological discontinuities.A new methodology is presented in which the rock mass demand can be expressed in terms of the mass in tonnes of unstable rock that is ejected per unit area of the excavation surface where failure occurs.A probabilistic approach has been implemented to estimate the potential rock mass instabilities and their associated static and dynamic demands.The new methodology considers that the strain energy released by the rock mass during violent stress-driven failure is largely converted into kinetic energy of ejection for blocks.The estimated dynamic demand has been favourably compared with observations of rock mass damage in a number of underground excavations. 展开更多
关键词 GEOLOGICAL structures PROBABILISTIC design Underground EXCAVATIONS High stresses Dynamic and static DEMANDS Deep mining
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A combined control strategy using tuned liquid dampers to reduce displacement demands of base-isolated structures: a probabilistic approach
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作者 Parham SHOAEI Houtan Tahmasebi ORIMI 《结构与土木工程前沿:英文版》 EI CSCD 2019年第4期890-903,共14页
This paper investigates a hybrid structural control system using tuned liquid dampers (TLDs) and lead-rubber bearing (LRB) systems for mitigating earthquake-induced vibrations. Furthermore, a new approach for taking i... This paper investigates a hybrid structural control system using tuned liquid dampers (TLDs) and lead-rubber bearing (LRB) systems for mitigating earthquake-induced vibrations. Furthermore, a new approach for taking into account the uncertainties associated with the steel shear buildings is proposed. In the proposed approach, the probabilistic distributions of the stiffness and yield properties of stories of a set of reference steel moment frame structures are derived through Monte-Carlo sampling. The approach is applied to steel shear buildings isolated with LRB systems. The base isolation systems are designed for different target base displacements by minimizing a relative performance index using Genetic Algorithm. Thereafter, the base-isolated structures are equipped with TLDs and a combination of the base and TLD properties is sought by which the maximum reduction occurs in the base displacement without compromising the performance of the system. In addition, the effects of TLD properties on the performance of the system are studied through a parametric study. Based on the analyses results, the base displacement can be reduced 23% by average, however, the maximum reduction can go beyond 30%. 展开更多
关键词 tuned liquid DAMPER lead-rubber BEARING system PROBABILISTIC framework steel SHEAR building RELATIVE performance index Monte-Carlo sampling
Seismic fragility of fl exible pipeline connections in a base isolated medical building 预览
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作者 Shang Qingxue Wang Tao Li Jichao 《地震工程与工程振动:英文版》 SCIE EI CSCD 2019年第4期903-916,共14页
Flexible pipelines are often used to connect hard pipes from a foundation to a superstructure to accommodate large deformation in the base isolation layer during an earthquake. Although Chinese seismic design guidelin... Flexible pipelines are often used to connect hard pipes from a foundation to a superstructure to accommodate large deformation in the base isolation layer during an earthquake. Although Chinese seismic design guidelines suggest several confi gurations, they are diff erent from the designs that have been proven in practice, e.g., Japanese styles, and extensive experimental investigation into their seismic performance is required. Three types of seals, rubber-, metal- and asbestinebased, were tested quasi-statically with infi lled pressurized water at 2.5 MPa. The asbestine-based seal leaked at a smaller deformation than the other two types of seals. Based on the test results, three damage states were defi ned and the deformation capacity was estimated. To evaluate their performance, a three-dimensional model of a base-isolated medical building was developed using OpenSees, with the fl exible pipelines simulated by a mechanical model calibrated from the experimental data. A probabilistic seismic demand model and the fragility function of the fl exible pipelines were then developed to evaluate the seismic performance. 展开更多
关键词 FL exible PIPELINE CONNECTIONS ISOLATED building QUASI-STATIC tests FRAGILITY curve probabilistic seismic demand model
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Some intriguing upper bounds for separating hash families
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作者 Gennian Ge Chong Shangguan Xin Wang 《中国科学:数学英文版》 SCIE CSCD 2019年第2期269-282,共14页
An N ×n matrix on q symbols is called {w1,...,wt}-separating if for arbitrary t pairwise disjoint column sets C1,..., Ct with |Ci|=wi for 1 ≤i≤t, there exists a row f such that f(C1),...,f(Ct) are also pairwise... An N ×n matrix on q symbols is called {w1,...,wt}-separating if for arbitrary t pairwise disjoint column sets C1,..., Ct with |Ci|=wi for 1 ≤i≤t, there exists a row f such that f(C1),...,f(Ct) are also pairwise disjoint, where f(Ci) denotes the collection of componentn of Ci restricted to row f. Given integers N, q and w1,...,wt, denote by C(N,q,{w1,...,wt}) the maximal a such that a corresponding matrix does exist.The determination of C(N,q,{w1,...,wt}) has received remarkable attention during the recent years. The main purpose of this paper is to introduce two novel methodologies to attack the upper bound of C(N, q, {w1,...,wt}).The first one is a combination of the famous graph removal lemma in extremal graph theory and a Johnson-type recursive inequality in coding theory, and the second onc is the probabilistic method. As a consequence, we obtain several intriguing upper bounds for some parameters of C(N,q,{w1,...,wt}), which significantly improve the previously known results. 展开更多
关键词 SEPARATING HASH families Johnson-type RECURSIVE bound graph removal LEMMA PROBABILISTIC method
Probabilistic rainfall thresholds in Chibo, India: estimation and validation using monitoring system
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作者 Abhirup DIKSHIT Neelima SATYAM 《山地科学学报:英文版》 SCIE CSCD 2019年第4期870-883,共14页
The Himalayan region has been severely affected by landslides especially during the monsoons. In particular, Kalimpong region in Darjeeling Himalayas has recorded several landslides and has caused significant loss of ... The Himalayan region has been severely affected by landslides especially during the monsoons. In particular, Kalimpong region in Darjeeling Himalayas has recorded several landslides and has caused significant loss of life, property and agricultural land. The study region, Chibo has experienced several landslides in the past which were mainly debris and earth slide. Globally, several types of rainfall thresholds have been used to determine rainfall-induced landslide incidents. In this paper, probabilistic thresholds have been defined as it would provide a better understanding compared to deterministic thresholds which provide binary results, i.e., either landslide or no landslide for a particular rainfall event. Not much research has been carried out towards validation of rainfall thresholds using an effective and robust monitoring system. The thresholds are then validated using a reliable system utilizing Microelectromechanical Systems(MEMS) tilt sensor and volumetric water content sensor installed in the region. The system measures the tilt of the instrument which is installed at shallow depths and is ideal for an early warning system for shallow landslides. The change in observed tilt angles due to rainfall would give an understanding of the applicability of the probabilistic model. The probabilities determined using Bayes’ theorem have been calculated using the rainfall parameters and landslide data in 2010-2016. The rainfall values were collected from an automatic rain gauge setup near the Chibo region. The probabilities were validated using the MEMS based monitoring system setup in Chibo for the monsoon season of 2017. This is the first attempt to determine probabilities and validate it with a robust and effective monitoring system in Darjeeling Himalayas. This study would help in developing an early warning system for regions where the installation of monitoring systems may not be feasible. 展开更多
关键词 EARLY WARNING PROBABILISTIC thresholds Kalimpong Monitoring
Scenario-based analysis and probability assessment of sub-synchronous oscillation caused by wind farms with direct-driven wind generators 预览
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作者 Zhi AN Chen SHEN +3 位作者 Zetian ZHENG Feng LIU Xiaoqing CHANG Wei WEI 《现代电力系统与清洁能源学报(英文)》 CSCD 2019年第2期243-253,共11页
Recently, explanations of the sub-synchronous oscillation(SSO) caused by wind farms based on directdriven wind generators(DDWGs) have been published in the literatures, in which the controller parameters of DDWGs and ... Recently, explanations of the sub-synchronous oscillation(SSO) caused by wind farms based on directdriven wind generators(DDWGs) have been published in the literatures, in which the controller parameters of DDWGs and the system equivalent parameters play an important role. However, more than one set of parameters can cause weakly damped sub-synchronous modes. The most vulnerable and highly possible scenario is still unknown. To find scenarios that have potential oscillation risks, this paper proposes a small disturbance model of wind farms with DDWGs connected to the grid using a state-space modeling technique. Taguchi’s orthogonal array testing is introduced to generate different scenarios.Multiple scenarios with different parameter settings that may lead to SSOs are found. A probabilistic analysis method based on the Gaussian mixture model is employed to evaluate the consistency of these scenarios with the actual accidents. Electromagnetic transient simulations are performed to verify the findings. 展开更多
关键词 Direct-driven wind generator Subsynchronous OSCILLATION PROBABILISTIC assessment RANDOMNESS
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History and General Characteristics of the Adaptive Control System of the Deuterium Pre-concentration Stage in Heavy Water Production 预览
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作者 Karachenets Dmitryi 《数学和系统科学:英文版》 2019年第1期7-20,共14页
The history of creation in 1971–1975 years at SDB MMS of the Institute of Cybernetics (Kyiv city) the control system for the deuterium pre-concentration stage in heavy water production at Dneprodzerzhinsk chemical pl... The history of creation in 1971–1975 years at SDB MMS of the Institute of Cybernetics (Kyiv city) the control system for the deuterium pre-concentration stage in heavy water production at Dneprodzerzhinsk chemical plant (now Kamianske city, PJSC “DneprAzot”) is considered. It is given a technological block-diagram of the stage with its components and block-diagram of ACSTP which was developed in consequence of investigations of this complex managed object. A mathematical model of the distillation columns in the separating units of hydrogen isotopes which was used for synthesis of an algorithm of the adaptive stochastic optimal system with active accumulation of information about managed probabilistic processes is described. The results of the carried out tests of the system confirmed its efficiency. 展开更多
关键词 Adaptive control system DEUTERIUM HEAVY water DISTILLATION ACSTP mathematical model managed PROBABILISTIC process
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Assessment of optic nerve and optic tract alterations in patients with orbital space-occupying lesions using probabilistic diffusion tractography
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作者 Chun-Nan Wu Shao-Feng Duan +4 位作者 Xue-Tao Mu Yi Wang Peng-Yu Lan Xiao-Lu Wang Kun-Cheng Li 《国际眼科杂志:英文版》 SCIE CAS 2019年第8期1304-1310,共7页
AIM: To investigate the diffusion changes in both the optic nerve and optic tract in orbital space-occupying lesion patients with decreased visual acuity, and its clinical significance using probabilistic diffusion tr... AIM: To investigate the diffusion changes in both the optic nerve and optic tract in orbital space-occupying lesion patients with decreased visual acuity, and its clinical significance using probabilistic diffusion tractography(PDT). METHODS: Twenty patients with orbital space-occupying lesions and 25 age-and gender-matched healthy persons were included. All patients and controls underwent routine orbital magnetic resonance imaging and diffusion tensor imaging(DTI), using a 3.0 T magnetic resonance scanner(Trio Tim Siemens). After the image data were preprocessed, each DTI parameters of the optic nerve and optic tract was obtained by PDT, including fractional anisotropy(FA), mean diffusivity(MD), axial diffusivity(AD) and radial diffusivity(RD). The asymmetry index(AI) of each parameter was calculated. Compared the parameters of the affected side optic nerve and ipsilateral optic tract with the contralateral side by paired sample t-test;compared AI of parameters of optic nerve and optic tract between the patient group and the control group by independent sample t-test. Patients were divided into threesubgroups according to the low vision grade standard of WHO, compared the FA and AI of FA between the three subgroups by single factor variance analysis. RESULTS: The affected side optic nerve presented significantly decreased FA, increased MD, AD, and RD values compared to the unaffected side(P<0.05). The AI of FA, MD, AD, and RD of optic nerve in the patients was significantly higher than that of the controls(P<0.05). The comparison results of the optic tract showed that there was no significant difference between the patient group and control group in terms of the bilateral optic tracts in patients(P>0.05). The AIs of the FA value of the optic nerve in the eyesight <0.1 subgroup was significantly higher than that in the other groups(P<0.05). CONCLUSION: FA, MD, AD, and RD of the affected side optic nerve of the orbital space-occupying lesions have significantly changed, the FA value is the most sensitive. The PDT 展开更多
关键词 ORBITAL space-occupying lesions decreased vision OPTIC never and OPTIC tract PROBABILISTIC diffusion TRACTOGRAPHY magnetic resonance imaging
Time-variant fragility analysis of the bridge system considering time-varying dependence among typical component seismic demands 预览
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作者 Song Shuai Qian Yongjiu +2 位作者 Liu Jing Xie Xiaorui Wu Gang 《地震工程与工程振动:英文版》 SCIE EI CSCD 2019年第2期363-377,共15页
This paper presents a copula technique to develop time-variant seismic fragility curves for corroded bridges at the system level and considers the realistic time-varying dependence among component seismic demands. Bas... This paper presents a copula technique to develop time-variant seismic fragility curves for corroded bridges at the system level and considers the realistic time-varying dependence among component seismic demands. Based on material deterioration mechanisms and incremental dynamic analysis, the time-evolving seismic demands of components were obtained in the form of marginal probability distributions. The time-varying dependences among bridge components were then captured with the best fitting copula function, which was selected from the commonly used copula classes by the empirical distribution based analysis method. The system time-variant fragility curves at different damage states were developed and the effects of time-varying dependences among components on the bridge system fragility were investigated. The results indicate the time-varying dependence among components significantly affects the time-variant fragility of the bridge system. The copula technique captures the nonlinear dependence among component seismic demands accurately and easily by separating the marginal distributions and the dependence among them. 展开更多
关键词 system FRAGILITY CHLORIDE corrosion TIME-VARYING DEPENDENCE copula function PROBABILISTIC seismic DEMAND
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Risk measurement of international oil and gas projects based on the Value at Risk method
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作者 Cheng Cheng Zhen Wang +1 位作者 Ming-Ming Liu Xiao-Hang Ren 《石油科学:英文版》 SCIE CAS CSCD 2019年第1期199-216,共18页
International oil and gas projects feature high capital-intensity, high risks and contract diversity. Therefore, in order to help decision makers make more reasonable decisions under uncertainty, it is necessary to me... International oil and gas projects feature high capital-intensity, high risks and contract diversity. Therefore, in order to help decision makers make more reasonable decisions under uncertainty, it is necessary to measure the risks of international oil and gas projects. For this purpose, this paper constructs a probabilistic model that is based on the traditional economic evaluation model, and introduces value at risk(VaR) which is a valuable risk measure tool in finance, and applies Va R to measure the risks of royalty contracts, production share contracts and service contracts of an international oil and gas project. Besides, this paper compares the influences of different risk factors on the net present value(NPV) of the project by using the simulation results. The results indicate:(1) risks have great impacts on the project’s NPV, therefore, if risks are overlooked, the decision may be wrong.(2) A simulation method is applied to simulate the stochastic distribution of risk factors in the probabilistic model. Therefore, the probability is related to the project’s NPV, overcoming the inherent limitation of the traditional economic evaluation method.(3) VaR is a straightforward risk measure tool, and can be applied to evaluate the risks of international oil and gas projects. It is helpful for decision making. 展开更多
关键词 RISK measurement Value at RISK INTERNATIONAL oil and gas PROJECTS FISCAL terms - PROBABILISTIC model
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