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Divergent asymmetric synthesis of azaarene-functionalized cyclic alcohols through stereocontrolled Beckwith-Enholm cyclizations

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Science China Chemistry 2021年第9期64卷 1522-1529页

作者： Zhanghong Guo xiaowei chen Hao Fang xiaowei Zhao Zhiyong Jiang International Scientific and Technological Cooperation Base of Chiral Chemistry Henan UniversityKaifeng475004China School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiang453007China

The first enantioselective Beckwith-Enholm cyclization reaction is reported *** cooperative photoredox and chiral hydrogen-bonding catalysis mediated by visible light,cyclization of carbonyls with azaarene-based olefins as a new reaction system offers a general and divergent synthetic pathway to furnish a variety of highly valuable enantioenriched azaarenefunctionalized carbocyclic and heterocyclic alcohols,which bear adjacent 1,2-or nonadjacent 1,3-stereocentres on distinct cyclic frameworks,in high yields and enantio-and *** good compatibility of various azaarenes and carbonyls as well as the diversity of cyclic structures of the products underscores the generality of the catalysis *** addition to the ability to precisely introduce deuterium into molecules in an enantioselective manner,the considerable synthetic value of this method includes the excellent antioxidant stress potential of the *** particular,molecule 29 was determined to be a promising lead compound for antioxidant stress drug design.

关键词： photoredox catalysis asymmetric catalysis Beckwith-Enholm cyclizations azaarenes antioxidant stress

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Study on damage mechanism and damage distribution of the rear plate under impact of debris cloud

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Defence Technology（防务技术） 2024年第5期35卷 151-167页

作者： chenyang Wu xiaowei chen Qiguang He State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyHaidian DistrictBeijing 100081China School of Mechatronical Engineering Beijing Institute of TechnologyHaidian DistrictBeijing 100081China Institute of Fluid Physics China Academy of Engineering PhysicsMianyang 621900SichuanChina

The debris cloud generated by the hypervelocity impact(HVI)of orbiting space debris directly threatens the spacecraft.A full understanding of the damage mechanism of rear plate is useful for the optimal design of protective *** this study,the hypervelocity yaw impact of a cylindrical aluminum projectile on a double-layer aluminum plate is simulated by the FE-SPH adaptive method,and the damage process of the rear plate under the impact of the debris cloud is analyzed based on the debris cloud *** damage process can be divided into the main impact stage of the debris cloud and the structural response of the rear *** main impact stage lasts a short time and is the basis of the rear plate *** the stage of structure response,the continuous deformation and inertial motion of the rear plate dominate the perforation of the rear *** further analyze the damage mechanism and damage distribution characteristics of the rear plate in ***,the connection between velocity space and position space of the debris cloud is established,which promotes the general analysis of the damage law of debris *** on the relationship,the features of typical damage areas are identified by the localized fine *** the cumulative effect and structural response cause the perforation of rear plate;in the non-perforated area,cratering by the impact of hazardous fragments is the main damage mode of the rear plate.

关键词： Damage of rear plate Debris cloud Secondary impact Hypervelocity yaw impact FE-SPH adaptive method

Oblique perforation of thick metallic plates by rigid projectiles

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Acta Mechanica Sinica 2006年第4期22卷 367-376页

作者： xiaowei chen Qingming Li Saucheong Fan Institute of Structural Mechanics China Academy of Engineering Physics P.O. Box 919-414 Mianyang 621900 China School of Mechanical Aerospace and Civil Engineering The University of Manchester P.O. Box 88 Pariser Building Manchester M60 1QD UK Protective Technology Research Center School of Civil and Environmental Engineering Nanyang Technological University Nanyang Avenue Nanyang Singapore 639798

Oblique perforation of thick metallic plates by rigid projectiles with various nose shapes is studied in this paper. Two perforation mechanisms, i.e., the hole enlargement for a sharp projectile nose and the plugging formation for a blunt projectile nose, are considered in the proposed analytical model. It is shown that the perforation of a thick plate is dominated by several non-dimensional numbers, i.e., the impact function, the geometry function of projectile, the non-dimensional thickness of target and the impact obliquity. Explicit formulae are obtained to predict the ballistic limit, residual velocity and directional change for the oblique perforation of thick metallic plates. The proposed model is able to predict the critical condition for the occurrence of ricochet. The proposed model is validated by comparing the predictions with other existing models and independent experimental data.

关键词： Oblique perforation Ballistic limit Metallic plate. Rigid projectile Shear plugging

Numerical Modeling of Natural Fracture Distributions in Shale

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Acta Geologica Sinica(English Edition) 2023年第3期97卷 828-840页

作者： LI Yaping chen xiaowei SHAO Yongbo School of Mechatronic Engineering Southwest Petroleum UniversityChengdu 610500China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China School of Civil Engineering and Geomatics Southwest Petroleum UniversityChengdu 610500China

The production efficiency of shale gas is affected by the interaction between hydraulic and natural *** study presents a simulation of natural fractures in shale reservoirs,based on a discrete fracture network(DFN)method for hydraulic fracturing *** properties of the model are calculated from core fracture data,according to statistical mathematical *** calculation results make full use of the quantitative information of core fracture orientation,density,opening and length,which constitute the direct and extensive data of mining *** reliability and applicability of the model are analyzed with regard to model size and density,a calculation method for dominant size and density being ***,finite element analysis is applied to a hydraulic fracturing numerical simulation of a shale fractured reservoir in southeastern *** hydraulic pressure distribution,fracture propagation,acoustic emission information and in situ stress changes during fracturing are *** results show the application of fracture statistics in fracture modeling and the influence of fracture distribution on hydraulic fracturing *** present analysis may provide a reference for shale gas exploitation.

关键词： shale core natural fracture discrete fracture network(DFN) hydraulic fracturing

A study on specialist or special disease clinics based on big data

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Frontiers of Medicine 2014年第3期8卷 376-381页

作者： Zhuyuan Fang xiaowei Fan Gong chen Jiangsu Province Ho spital of TCM Nanjing 210029 China

Correlation analysis and processing of massive medical information can be implemented through big data technology to find the relevance of different factors in the life cycle of a disease and to provide the basis for scientific research and clinical practice. This paper explores the concept of constructing a big medical data platform and introduces the clinical model construction. Medical data can be collected and consolidated by distributed computing technology. Through analysis technology, such as artificial neural network and grey model, a medical model can be built. Big data analysis, such as Hadoop, can be used to construct early prediction and intervention models as well as clinical decision-making model for specialist and special disease clinics. It establishes a new model for common clinical research for specialist and special disease clinics.

关键词： big data correlation analysis medical information integration data analysis clinical model

Fuzzy cost-profit tradeoff model for locating a vehicle inspection station considering regional constraints

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第12期15卷 1138-1146页

作者： Guangdong TIAN Hua KE xiaowei chen Transportation College Northeast Forestry University School of Economics and Management Tongji University Department of Risk Management and Insurance Nankai University

Facility location allocation(FLA) is one of the important issues in the logistics and transportation fields. In practice, since customer demands, allocations, and even locations of customers and facilities are usually changing, the FLA problem features uncertainty. To account for this uncertainty, some researchers have addressed the fuzzy profit and cost issues of FLA. However, a decision-maker needs to reach a specific profit, minimizing the cost to target customers. To handle this issue it is essential to propose an effective fuzzy cost-profit tradeoff approach of FLA. Moreover, some regional constraints can greatly influence FLA. By taking a vehicle inspection station as a typical automotive service enterprise example, and combined with the credibility measure of fuzzy set theory, this work presents new fuzzy cost-profit tradeoff FLA models with regional constraints. A hybrid algorithm integrating fuzzy simulation and genetic algorithms(GA) is proposed to solve the proposed models. Some numerical examples are given to illustrate the proposed models and the effectiveness of the proposed algorithm.

关键词： Cost-profit tradeoff Credibility theory Fuzzy simulation Fuzzy programming Genetic algorithm

Modeling of Normal Perforation of Reinforced Concrete Slabs by a Rigid Projectile

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Transactions of Tianjin University 2006年第B09期12卷 107-111页

作者： chen xiaowei LI Xiaoli Institute of Structural Mechanics China Academy of Engineering Physics Mianyang 621900 China State Key Lab of Explosion Science and Technology Beijing Institute of Technology Beijing 100088 China

An analytical model on the normal perforation of reinforced concrete slabs is constructed. The effect of reinforcing bars is further hybridized in a general three-stage model consisting of initial cratering, tunnelling and shear plugging. Besides three dimensionless numbers, i. e., the impact function I, the geometry function of projectile N and the dimensionless thickness of concrete target X, which are employed to predict the ballistic performance of perforation of concrete slabs, the reinforcement ratio Ps of concrete and the tensile strength fs of reinforcing bars are considered as the other main factors influencing the perforation process. Simpler solutions of ballistic performances of normal perforation of reinforced concrete slabs are formulated. Theoretical predictions agree well with individual published experimental data.

关键词： normal perforation ballistic limit reinforced concrete rigid projectile impact

Phytosterols in edible oil:Distribution,analysis and variation during processing

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Grain & Oil Science and Technology 2021年第1期4卷 33-44页

作者： Ge Bai Chuanguo Ma xiaowei chen College of Food Science and Engineering Henan University of TechnologyZhengzhou 450001China

Phytosterols,which are naturally occurring in plants,have excellent nutritional and health values on lowering both the blood cholesterol level and the risk of cardiovascular *** oils are the main source of daily intake of phytosterols,whereas the properties of phytosterols may vary a lot depending on their *** the processing of edible oil including refining and frying,phytosterol's content fluctuates,which influences the properties of the final *** and their derivatives undergo physical migration between different phases and chemical conversion during the processing,which reduces the quality and the commercial value of edible ***,the loss of phytosterols is the major concern in the process of neutralization and *** addition,oxidation and thermal degradation of phytosterols occur simultaneously during frying,which also reduces the content of ***,the oil matrix has a promoting or an inhibitory effect on the thermal oxidation of ***,various efforts have been devoted to analyzing and improving the remaining contents of phytosterols in edible *** of the processing method,temperature plays an important role in the loss of *** present,themain analysismethods of phytosterols include gas chromatography and liquid chromatography,inwhich the pretreatment of different types of phytosterols is also a crucial *** review focused on the following topics comprehensively:(i)the distribution of phytosterols in the oil-containing plants and edible oils during the refining processing;(ii)the pretreatment and analysis methods of various phytosterols(free phytosterols,phytosteryl fatty acid esters,phytosteryl glycosides and acylated phytosteryl glycosides);(iii)the variation of phytosterols in process of esterification and oxidation,storage and so *** study also proposed that the investigation in the loss and safety of phytosterols during processing of the

关键词： Phytosterols Edible oil Distribution Gas chromatography High performance liquid chromatography Oil refining

Multi-scale finite element simulation on large deformation behavior of wood under axial and transverse compression conditions

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Acta Mechanica Sinica 2021年第7期37卷 1136-1151,I0002页

作者： Weizhou Zhong Zexiong Zhang xiaowei chen Qiang Wei Gang chen Xicheng Huang Institute of Systems Engineering China Academy of Engineering PhysicsMianyang Sichuan621999China Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province Mianyang 621999China College of Engineering Science University of Science and Technology of ChinaHefei 230026China Advanced Research Institute for Multidisciplinary Science Beijing Institute of TechnologyBeijing100081China The State Key Lab of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

Multi-scale finite element method is adopted to simulate wood compression behavior under axial and transverse loading. Representative volume elements (RVE) of wood microfibril and cell are proposed to analyze orthotropic mechanical behavior. Lignin, hemicellulose and crystalline-amorphous cellulose core of spruce are concerned in spruce nanoscale model. The equivalent elastic modulus and yield strength of the microfibril are gained by the RVE simulation. The anisotropism of the crystalline-amorphous cellulose core brings the microfibril buckling deformation during compression loading. The failure mechanism of the cell-wall under axial compression is related to the distribution of amorphous cellulose and crystalline cellulose. According to the spruce cell observation by scanning electron microscope, numerical model of spruce cell is established using simplified circular hole and regular hexagon arrangement respectively. Axial and transverse compression loadings are taken into account in the numerical simulations. It indicates that the compression stress-strain curves of the numerical simulation are consistent with the experimental results. The wood microstructure arrangement has an important effect on the stress plateau during compression process. Cell-wall buckling in axial compression induces the stress value drops rapidly. The wide stress plateau duration means wood is with large energy dissipation under a low stress level. The numerical results show that loading velocity affects greatly wood microstructure failure modes in axial loading. For low velocity axial compression, shear sliding is the main failure mode. For high velocity axial compression, wood occur fold and collapse. In transverse compression, wood deformation is gradual and uniform, which brings stable stress plateau.

关键词： Multi-scale model Representative volume element Spruce Energy dissipation Wood cell