检索结果-南通市图书馆

Index allocation for a reusable LOX/CH4 rocket engine

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2021年第2期34卷 432-440页

作者： Yi li Jie FANG Bing SUN kaiyang li Guobiao CAI School of Astronautics Beihang UniversityBeijing 100083China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies(Beihang University) Ministry of EducationBeijing 100083China

Reusable rocket engines are the core components of reusable launch vehicles, and have thus become a major focus of aerospace engineering research in recent years. In practice, subsystem design is based on the overall index allocation of an engine;therefore, a multidisciplinary optimization approach is necessary. In this study, design of a reusable methane/liquid oxygen(LOX/CH4)rocket engine with a gas generator cycle was investigated using multidisciplinary optimization. Two parameters were chosen as design variables: pressure and fuel mix ratio of the main combustion chamber. Optimization objectives were specific impulse, structural mass, and life cycle cost of the reusable rocket engine, and constraints were assigned to each discipline according to rocket design requirements. Then, an optimization model was developed, and optimal design parameters were acquired for the LOX/CH4 rocket engine. The proposed method is effective for designing the index allocation of reusable rocket engines and takes into account the multidisciplinary nature of complex systems.

关键词： Index allocation Mass model Multidisciplinary optimization Reliability Rocket engines

Functional Imaging of Breast Tissue and Clinical Application

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2006年第2期11卷 373-376页

作者： li kaiyang liU Shenglin School of Physics Science and Technology Wuhan University Wuhan 430072 Hubei China

A novel approach to image hemoglobin concentration（△Dhb） and oxygen saturation （△Doxy） of breast tissue is presented. The scenograph of dual-wavelength （760 and 850 nm） near infrared lights through breast tissue is acquired by high sensitive charge coupled device （CCD） camera. The evaluation criterion of the difference of △Dhh and △Doxy between detected and referenced breast tissue can be obtained by a calculation formula without complicate caculation. This approach is applied to clinic detection in breast tissue. The ongoing clinical experiments indicate that malignant tumor usually exhibits characterize of ＂higher △Dhb and lower △Doxy＂, while benign lesion often shows ＂lower △Dhb and higher △Doxy＂ or other characters. So it is useful to assist the diagnosis of breast disease.

关键词： near-infrared hemoglobin concentration oxygen saturation functional imaging breast tumor

Plausible Heterogeneous Graph k-Anonymization for Social Networks

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2022年第6期27卷 912-924页

作者： kaiyang li ling Tian Xu Zheng Bei Hui School of Computer Science and Engineering University of Electronic Science and Technology of ChinaChengdu 611731China School of Information and Software Engineering University of Electronic Science and Technology of ChinaChengdu 610054China Trusted Cloud Computing and Big Data Key Laboratory of Sichuan Province Chengdu 610000China

The inefficient utilization of ubiquitous graph data with combinatorial structures necessitates graph embedding methods,aiming at learning a continuous vector space for the graph which is amenable to be adopted in traditional machine learning algorithms in favor of vector *** embedding methods build an important bridge between social network analysis and data analytics as social networks naturally generate an unprecedented volume of graph data *** social network data not only bring benefit for public health,disaster response,commercial promotion,and many other applications,but also give birth to threats that jeopardize each individual’s privacy and ***,most existing works in publishing social graph embedding data only focus on preserving social graph structure with less attention paid to the privacy issues inherited from social *** be specific,attackers can infer the presence of a sensitive relationship between two individuals by training a predictive model with the exposed social network *** this paper,we propose a novel link-privacy preserved graph embedding framework using adversarial learning,which can reduce adversary’s prediction accuracy on sensitive links while persevering sufficient non-sensitive information such as graph topology and node attributes in graph *** experiments are conducted to evaluate the proposed framework using ground truth social network datasets.

关键词： social network graph embedding privacy preservation adversarial learning

Achieving Differential Privacy of Genomic Data Releasing via Belief Propagation

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2018年第4期23卷 389-395页

作者： Zaobo He Yingshu li Ji li kaiyang li Qing Cai Yi liang Department of Computer Science Georgia State University Atlanta GA 30303 USA School of Computer Science and Engineering University of Electronic Science and Technology of China Chengdu 611731 China

Privacy preserving data releasing is an important problem for reconciling data openness with individual privacy. The state-of-the-art approach for privacy preserving data release is differential privacy, which offers powerful privacy guarantee without confining assumptions about the background knowledge about attackers. For genomic data with huge-dimensional attributes, however, current approaches based on differential privacy are not effective to handle. Specifically, amount of noise is required to be injected to genomic data with tens of million of SNPs （Single Nucleotide Polymorphisms）, which would significantly degrade the utility of released data. To address this problem, this paper proposes a differential privacy guaranteed genomic data releasing method. Through executing belief propagation on factor graph, our method can factorize the distribution of sensitive genomic data into a set of local distributions. After injecting differential-privacy noise to these local distributions, synthetic sensitive data can be obtained by sampling on noise distribution. Synthetic sensitive data and factor graph can be further used to construct approximate distribution of non-sensitive data. Finally, non-sensitive genomic data is sampled from the approximate distribution to construct a synthetic genomic dataset.

关键词： differential privacy SNP/trait associations belief propagation factor graph data releasing

Design and experimental research of a sub-Newton N_(2)O monopropellant thruster with inner-heater

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第5期35卷 309-318页

作者： kaiyang li Jie FANG Wei SUN Bing SUN Guobiao CAI School of Astronautics Beihang UniversityBeijing 100083China Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technologies of Ministry of Education Beihang UniversityBeijing 100083China China Academy of Space Technology Beijing 100094China

Nitrous oxide(N_(2)O)is a green propellant with excellent application prospects.A subNewton N_(2)O monopropellant thruster with inner-heater and a N_(2)O self-pressurization stable supply system with regenerative heat compensation are designed in this *** experimental research of the thruster is described,including measurements of preheating power,activation temperature,vacuum thrust,specific impulse,life-span and pulsed operation *** inserting the heater into the catalyst-bed,preheating efficiency of the heater is significantly improved compared to the thruster with ***,the preheating power demand of the thruster is successfully reduced to around 10 *** mean vacuum thrust of 322 mN is attained and the corresponding specific impulse reaches 162s at the mass flow rate of 0.2 g/*** activation temperature of 523 K is achieved,and the activation performance of the thruster is affected by the loading factor.A long term hot-firing test longer than 12000 s is *** pulsed operation performance of the inner-preheating thruster is also studied by measuring chamber *** with different magnitudes are produced by adjusting the opening duration of the control valve.A minimum impulse of 81 mN·s is ***,the performance of the thruster is evaluated by comparison with other thrusters of the same *** results indicate that the proposed thruster with inner-heater is superior in terms of preheating power,activation temperature and specific impulse performance.

关键词： Green propellant Monopropellant thruster Nitrous oxide Regenerative heat compensation Self-pressurization

Neural-based inexact graph de-anonymization

在线全文

学校读者我要写书评

暂无评论

High-Confidence Computing 2024年第1期4卷 52-59页

作者： Guangxi Lu kaiyang li Xiaotong Wang Ziyue liu Zhipeng Cai Wei li Department of Computer Science Georgia State UniversityAtlantaUSA St.George’s School VancouerCanada

Graph de-anonymization is a technique used to reveal connections between entities in anonymized graphs,which is crucial in detecting malicious activities,network analysis,social network analysis,and *** its paramount importance,conventional methods often grapple with inefficiencies and challenges tied to obtaining accurate query graph *** paper introduces a neural-based inexact graph de-anonymization,which comprises an embedding phase,a comparison phase,and a matching *** embedding phase uses a graph convolutional network to generate embedding vectors for both the query and anonymized *** comparison phase uses a neural tensor network to ascertain node *** matching procedure employs a refined greedy algorithm to discern optimal node ***,we comprehensively evaluate its performance via well-conducted experiments on various real *** results demonstrate the effectiveness of our proposed approach in enhancing the efficiency and performance of graph de-anonymization through the use of graph embedding vectors.

关键词： Graph de-anonymization Graph convolutional network Neural tensor network

Biopsy of Canada’s family physician shortage

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Family Medicine and Community Health 2023年第2期11卷 21-24页

作者： kaiyang li Anna Frumkin Wei Guang Bi Jamie Magrill Christie Newton McGill University Faculty of Medicine and Health Sciences MontrealQuebecCanada Max Bell School of Public Policy McGill UniversityMontrealQuebecCanada Western University Schulich School of Medicine&Dentistry LondonOntarioCanada Family Practice The University of British ColumbiaVancouverBritish ColumbiaCanada

Family physicians provide comprehensive care for the community and are an integral part of the healthcare *** is experiencing a shortage of family physicians,driven in part by overbearing expectations of family physicians,limited support and resources,antiquated physician compensation,and high clinic operating *** additional factor contributing to this scarcity is the shortage of medical school and family medicine residency spots,which have not kept pace with population *** analysed and compared data on provincial populations and numbers of physicians,residency spots and medical school seats across *** physician shortages are the highest in the territories(>55%),Quebec(21.5%)and British Columbia(17.7%).Among the provinces,Ontario,Manitoba,Saskatchewan and British Columbia have the fewest family physicians per 100000 persons in the *** the provinces that offer medical education,British Columbia and Ontario have the fewest medical school seats per population,while Quebec has the *** Columbia has the smallest medical class size and the least number of family medicine residency spots as a function of population,and one of the highest percentages of provincial residents without family ***,Quebec has a relatively large medical class size and a high number of family medicine residency spots as a function of population,but also one of the highest percentages of provincial residents without family *** strategies to improve the current shortage include encouraging Canadian medical students and international medical graduates to consider family medicine,and reducing administrative burdens for current *** steps include creating a national data framework,understanding physician needs to guide effective policy changes,increasing seats in medical schools and family residency programmes,providing financial incentives and facilitating entry into family medicine for international medical

关键词： Canada shortage smallest

Using a Hybrid Genetic Algorithm to Learn Rules From Examples

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 1996年第2期1卷 163-166页

作者： liu Juan Huang Ganpin li kaiyang Department of Computer Science Wuhan University Wuhan China Center of Analysis and Measurement Wuhan University Wuhan China

in this article a novel learning method is proposed,which is a combination of GA and the bottomup induction process. The method has been implemented in a system called KAA,and we evaluate it on a multiplexer problem,... 详细信息

关键词： concept learning hybrid genetic algorithm

基于自适应模拟退火算法的生物体三维温度场重构研究

在线全文

学校读者我要写书评

暂无评论

机械工程学报 2016年第6期52卷 166-173页

作者：史贵连李凯扬叶福丽湖北科技学院生物医学工程学院咸宁437100 武汉大学物理科学与技术学院武汉430072

生物体三维温度场的无损重构对于生物医学工程领的发展有着十分重要的意义。提出基于自适应模拟退火算法进行生物体三维温度场无损重构的重要思想,把复杂的生物热传导反问题的求解转换为正问题的求解过程。设生物体内点热源的位置P(x,y... 详细信息

生物体三维温度场的无损重构对于生物医学工程领的发展有着十分重要的意义。提出基于自适应模拟退火算法进行生物体三维温度场无损重构的重要思想,把复杂的生物热传导反问题的求解转换为正问题的求解过程。设生物体内点热源的位置P(x,y,z)和温度t为优化变量,把同一表面各个对应点的试验温度值和计算温度值相减并取绝对值之和,以此为目标函数逐次迭代。目标值越小,则当前变量,即热源位置和温度值最优。为了提高优化效率,提出一种新颖的目标函数建立方法。热源的仿真位置和试验位置十分接近。最优值确定后,相应的三维温度场也随之确定,任意截面的温度分布可以提取出来。自适应模拟退火算法可以很好地应用于生物体三维温度场的重构,它不仅方便,而且快捷,蕴藏着广阔的应用前景,热传导反问题的研究提供了一条具有借鉴性的方法与思路。

关键词：自适应模拟退火算法三维温度场目标函数集成优化