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A Worst-Case Risk Measure by G-VaR

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Acta Mathematicae Applicatae Sinica 2021年第2期37卷 421-440页

作者： Zi-ting pei Xi-shun WANG Yu-hong XU Xing-ye YUE Center for Financial Engineering Soochow UniversitySuzhou 215006China Math Center for Interdiscipline Research Soochow UniversitySuzhou 215006China School of Mathematical Sciences Soochow UniversitySuzhou 215006China

G-VaR,which is a type of worst-case value-at-risk(VaR),is defined as measuring risk incorporating model *** with most extant notions of worst-case VaR,G-VaR can be computed using an explicit formula,and can be applied to large portfolios of several hundred dimensions with low computational *** also apply G-VaR to robust portfolio optimization,thereby providing a tractable means to facilitate optimal allocations under the condition of market ambiguity.

关键词： risk measurement worst-case value-at-risk portfolio management G-expectation

Cyclic oxidation behavior of Ni_(3)Al-based single crystal alloy IC21

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Rare Metals 2023年第5期42卷 1656-1662页

作者： Tian-Tian Yang Xin Zhou Shu-Suo Li Yan-Ling pei Sheng-Kai Gong School of Materials Science and Engineering Beihang UniversityBeijing100191China

In this study,the cyclic oxidation tests of the Ni3Al-based single-crystal super alloy IC21 were carried out at 800,900,950,1000,1050 and 1100℃in *** present study shows that the complex oxide scale on the surface of the alloy is made up of an outer columnar NiO layer,an intermediate mixture of NiO and NiAl2O4layer with a small amount of Mo oxides and an inner continuous layer ofα-Al_(2)O_(3).The cyclic oxidation kinetics curves show that oxidation resistance at 800,900,950,1000 and1050℃seems to follow a similar law and is better than that at 1100℃.The overall weight changes at 1100℃follows a parabolic *** and severe rumpling of the oxide scale are observed on the surface of the alloy at1100℃,revealing the occurrence of disastrous oxidation.

关键词： Ni_(3)Al Thermal cycling Oxidation Microstructure

Evaluating agricultural water-use efficiency based on water footprint of crop values: a case study in Xinjiang of China

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Journal of Arid Land 2020年第4期12卷 580-593页

作者： HAI Yang LONG Aihua ZHANG pei DENG Xiaoya LI Junfeng DENG Mingjiang State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100038China College of Water Conservancy and Architectural Engineering Shihezi UniversityShihezi 832003China Xinjiang Water Conservancy and Hydropower Planning and Design Management Bureau Urumqi 830000China

Efficient agricultural water use is crucial for food safety and water conservation on a global scale. To quantitatively investigate the agricultural water-use efficiency in regions exhibiting the complex agricultural structure, this study developed an indicator named water footprint of crop values(WFV) that is based on the water footprint of crop production. Defined as the water volume used to produce a unit price of crop(m^3/CNY), the new indicator makes it feasible to directly compare the water footprint of different crops from an economic perspective, so as to comprehensively evaluate the water-use efficiency under the complex planting structure. On the basis of WFV, the study further proposed an indicator of structural water-use coefficient(SWUC), which is represented by the ratio of water-use efficiency for a given planting structure to the water efficiency for a reference crop and can quantitatively describe the impact of planting structure on agricultural water efficiency. Then, a case study was implemented in Xinjiang Uygur Autonomous Region of China. The temporal and spatial variations of WFV were assessed for the planting industries in 14 prefectures and cities of Xinjiang between 1991 and 2015. In addition, contribution rate analysis of WFV for different prefectures and cities was conducted to evaluate the variations of WFV caused by different influencing factors: agricultural input, climatic factors, and planting structure. Results from these analyses indicated first that the average WFV of planting industries in Xinjiang significantly decreased from 0.293 m^3/CNY in 1991 to 0.153 m^3/CNY in 2015, corresponding to an average annual change rate of –3.532%. WFV in 13 prefectures and cities(with the exception of Karamay) has declined significantly during the period of 1991–2015, indicating that agricultural water-use efficient has effectively improved. Second, the average SWUC in Xinjiang decreased from 1.17 to 1.08 m^3/CNY in the 1990 s, and then declined

关键词： agricultural input climatic factors contribution rate planting structure structural water-use coefficient water footprint of crop values

共生理论视角下新疆高校“轮转冰”课程探索实证研究

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冰雪运动 2024年第4期46卷 42-50页

作者：赵良朱贺裴盈陈刘宝陈龙新疆教育学院体育学院新疆乌鲁木齐830043 北京体育大学管理学院北京100084

在冰雪运动“南展西扩东进”战略推动下,新疆冰雪运动进校园成效显著。基于共生理论,运用问卷调查、实验、访谈等研究方法,调查新疆教育学院400名学生对冰雪运动进校园的态度,并对30名体育专业学生进行“轮转冰”特色课程教学,分析教学... 详细信息

在冰雪运动“南展西扩东进”战略推动下,新疆冰雪运动进校园成效显著。基于共生理论,运用问卷调查、实验、访谈等研究方法,调查新疆教育学院400名学生对冰雪运动进校园的态度,并对30名体育专业学生进行“轮转冰”特色课程教学,分析教学后的测试结果。得出“轮转冰”课程有利于轮滑、滑冰课程一体化共生,并向非对称性互惠共生发展变化;轮滑与滑冰技能具有运动技能的迁移效果;“轮转冰”课程有助于解决新疆高校冰雪运动进校园的瓶颈。建议增加新疆高校体育经费投入,增强学校冰雪运动专业师资力量;完善“轮转冰”课程实施与宣传,在理论与实践结合中建立成熟模式;将“轮转冰”课程模式向运动专业及公共体育课程延伸,逐步形成校园冰雪运动文化;加强校企合作,深化“轮转冰”课程与培训,以乌鲁木齐市为中心,促进新疆冰雪体育教育事业发展。

关键词：共生理论新疆高校 “轮转冰”课程实证研究

Pd nano-catalyst supported on biowaste-derived porous nanofibrous carbon microspheres for efficient catalysis

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化学科学与工程前沿:英文版 2023年第9期17卷 1289-1300页

作者： Xianglin pei Siyu Long Lingyu Zhang Zhuoyue Liu Wei Gong Aiwen Lei Dongdong Ye School of Materials and Architectural Engineering Guizhou Normal UniversityGuiyang550025China College of Chemistry and Molecular Sciences Wuhan UniversityWuhan430072China School of Textile Materials and Engineering Wuyi UniversityJiangmen529020China Guizhou Key Laboratory of Inorganic Nonmetallic Functional Materials Guizhou Normal UniversityGuiyang550025China

Environmental pollution caused by the presence of aromatic aldehydes and dyes in wastewater is a serious global concern. An effective strategy for the removal of these pollutants is their catalytic conversion, possibly to valuable compounds. Therefore, the design of efficient, stable and long-lifetime catalysts is a worthwhile research goal. Herein, we used nanofibrous carbon microspheres (NCM) derived from the carbohydrate chitin present in seafood waste, and characterized by interconnected nanofibrous networks and N/O-containing groups, as carriers for the manufacture of a highly dispersed, efficient and stable Pd nano-catalyst (mean diameter ca. 2.52 nm). Importantly, the carbonised chitin’s graphitized structure, defect presence and large surface area could promote the transport of electrons between NCM and Pd, thereby endowing NCM supported Pd catalyst with high catalytic activity. The NCM supported Pd catalyst was employed in the degradation of some representative dyes and the chemoselective hydrogenation of aromatic aldehydes;this species exhibited excellent catalytic activity and stability, as well as applicability to a broad range of aromatic aldehydes, suggesting its potential use in green industrial catalysis.

关键词： biowaste chitin nanofibrous palladium nano-catalyst catalysis

Prognostics based on the generalized diffusion process with parameters updated by a sequential Bayesian method

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Science China(Information Sciences) 2022年第6期65卷 172-188页

作者： Hong pei Xiaosheng SI Changhua HU Jianxun ZHANG Dangbo DU Zhenan PANG Shengfei ZHANG School of Missile Engineering Rocket Force University of Engineering School of Mechanical Engineering Xi'an Jiaotong University

The realistic degradation process for the engineering equipment is generally stochastic and complicated owing to the uncertain operational condition and multiple functional loading, exhibiting the absolute nonlinear distinction. Such a nonlinear degradation process is widely modeled as a generalized diffusion process. When utilizing the generalized diffusion process-based model, certain model parameters are considered as the random variables to characterize the unit-to-unit discrepancies. Hence, the estimation of these kinds of parameters usually resorts to the Bayesian method. However, owing to the complex pattern of the model parameters in the generalized diffusion process, computing the Bayesian updated parameters requires plenty of repeated calculation and integration operations once the new degradation monitoring information is available. This will inevitably lower the computing efficiency and real-time performance. Toward this end, this paper presents an adaptive prognostic method based on the generalized diffusion process to determine the remaining useful life(RUL) of degraded equipment. First, a generalized diffusion process-based degradation modeling framework is constructed to describe the health performance of stochastic degraded equipment under complex conditions. Then, we utilize the maximum likelihood estimation(MLE) method to estimate the initial model parameters by analyzing the historical degradation information. Furthermore, a sequential Bayesian method is proposed to recursively update the stochastic model parameters in the generalized diffusion process for particular equipment in service. Unlike the existing studies utilizing the Bayesian method,the primary contrast in the presented method lies in that there is no need to implement the calculation process with complicated integration repeatedly utilizing the whole degradation information obtained before the current time. Particularly, the current measured information is incorporated into the esti

关键词： generalized diffusion process stochastic model parameters remaining useful life maximum likelihood estimation sequential Bayesian methods

Optimization design and residual thermal stress analysis of PDC functionally graded materials

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第8期7卷 1318-1323页

作者： CAO Pin-lu LIU Bao-chang YIN Kun ZHANG Zu-pei College of Constructzon Engineering Jilin University Changchun 130026 China Key Laboratory of Geo-exploration Instrumentation Ministry of Education Changchun 130026 China

The distribution of thermal stresses in functionally graded polycrystalline diamond compact (PDC) and in single coating of PDC are analyzed respectively by thermo-mechanical finite element analysis (FEA). It is shown that they each have a remarkable stress concentration at the edge of the interfaces. The diamond coatings usually suffer premature failure because of spallation, distortion or defects such as cracks near the interface due to these excessive residual stresses. Results showed that the axial tensile stress in FGM coating is reduced from 840 MPa to 229 MPa compared with single coating, and that the shear stress is reduced from 671 MPa to 471 MPa. Therefore, the single coating is more prone to spallation and cracking than the FGM coating. The effects of the volume compositional distribution factor (n) and the number of the graded layers (L) on the thermal stresses in FGM coating are also discussed respectively. Modelling results showed that the optimum value of the compositional distribution factor is 1.2, and that the best number of the graded layers is 6.

关键词： Functionally graded materials (FGM) Optimum design Polycrystalline diamond compact (PDC) Residual thermal stress Finite element method (FEM)

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一种基于边云协同的高精度定位设计方法

长江信息通信 2024年第9期37卷 166-170页

作者：李森马坤裴俊龙柳雅鹏中移(上海)信息通信科技有限公司上海200120

文章提供一种涉及通信技术、定位测绘领域的基于全球卫星导航系统(Global Navigation Satellite System, GNSS)与边缘计算实现的高精度定位系统。该方法能够有效利用边缘云“近源”低时延、弹性计算,以及核心云统一配置、管理、分发等... 详细信息

文章提供一种涉及通信技术、定位测绘领域的基于全球卫星导航系统(Global Navigation Satellite System, GNSS)与边缘计算实现的高精度定位系统。该方法能够有效利用边缘云“近源”低时延、弹性计算,以及核心云统一配置、管理、分发等边云协同特性,进行CORS站管理配置、差分数据采集、数据质量控制、VRS建模、差分数据分发、以及ROVER终端定位观测数据的收集、预处理、差分解算和结果发送处理,进一步优化解算质量,提高解算效率。

关键词：高精度定位边云协同核心云边缘云

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Effect of TiO_(2)coating on the surface condition and corona characteristics of positive DC conductors with particle matters

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High Voltage 2022年第1期7卷 147-157页

作者： pei Xu Yanxiang Ma Jie Zhu Luxing Zhao Boyang Shen Xingming Bian State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijingChina Shijingshan Power Supply Company State Grid Beijing Electric Power Supply CompanyBeijingChina Yangzhou Power Supply Company State Grid Jiangsu Electric Power Supply CompanyYangzhouChina High Voltage Research Department China Electric Power Research InstituteBeijingChina Electrical Engineering Division University of CambridgeCambridgeUK

Persistent severe smog and dust weather exists in many regions of *** accu-mulate on the surface of high‐voltage transmission lines,which affects the surface morphology of the transmission line and induces corona *** work mainly studies the influence of electric field and photocatalysis on the corona characteristics of transmission *** this work,plasma spraying is used to prepare a dense,smooth and excellent photocatalytic TiO_(2)coating on the surface of transmission *** electron microscope and a white light interference profilometer is used to study the surface condition of the *** variation in the surface condition of the samples is observed under different fouling,light time and electric field *** corona characteristics of power transmission lines under different surface conditions are *** results show that light and applied electric field promote the photocatalytic effect of TiO_(2),which helps to decompose the contamination on the surface of power transmission wires and thus reduce the corona discharge of transmission *** increase in corona inception voltage reduces the corona current pulse repetition rate and the ion current density during corona discharge.

关键词： discharge. coating surface