检索结果-南通市图书馆

Formation Principle and Characteristics of Self‑Supercharging Pulsed Water Jet

Chinese Journal of Mechanical Engineering 2022年第3期35卷 250-263页

作者： Zhaolong ge Yuanfei Ling Jiren Tang Yiyu lu Yangkai Zhang Lei Wang qi Yao State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400030China National&Local Joint Engineering Laboratory of Gas Drainage in Complex Coal Seam Chongqing UniversityChongqing 400030China College of Source and Safety Chongqing UniversityChongqing 400030China

High-pressure pulsed water jet technology has considerable development potential in the field of rock *** overcome the shortcomings of existing pulsed jets,a self-supercharging pulsed water jet(SSPWJ)generation method is proposed,which is based on the theory of the pulsed water jet and the principle of hydraulic *** proposed method changes the flow direction of the fluid medium through the valve core to make the piston reciprocate in the cylinder and relies on the effective area difference between the front and rear chambers in the stroke stage of the piston to realize the organic combination of“pulse”and“supercharging”of the jet,thus forming an *** the basis of the formation principle of the SSPWJ,a SSPWJ testing platform was constructed,and tests were performed on the jet pressure acquisition,morphology capture,and granite *** the jet pressure and the jet morphology exhibited periodic changes,and a higher pulse pressure was obtained at lower inlet *** error of the pressure ratio calculated according to the experimental results waslue,confirming the feasibility of the *** pulse pressure and pulse frequency are controllable;that is,as the inlet flow rate increases in the stroke stage of the piston,the pulse pressure and pulse frequency increase,and the pulse duration *** the inlet flow rate increases in the backward-stroke stage of the piston,the pulse frequency increases,and the pulse pressure and pulse duration remain *** the combined action of the waterhammer pressure,high-speed lateral flow,and high-frequency dynamic load of the SSPWJ,local flaky exfoliation was observed when the granite surface was *** results of this study lay the foundation for enriching the theory of pulsed jet generation and expanding its application range.

关键词： Pulsed water jet Self-supercharging Pulse parameters Jet morphology Granite breaking

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Numerical simulation of viscous flows with adaptively refined Cartesian grid

引用

航空动力学报 2014年第2期29卷 467-474页

作者： HAN Yu-qi GAO ge National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Energy and Power EngineeringBeijing University of Aeronautics and Astronautics

Quadtree-based Cartesian grid was automatically generated from specified *** refinements were performed according to geometric parameters and solution of flow *** altered CCST(curvature corrected symmetry technique)approach was proposed to apply solid wall boundary conditions. Driven flows in a square cavity and flows around NACA0012airfoil were simulated and compared with the result of published structured grid and stretched Cartesian *** results show that solid wall boundary condition are accurately applied by current altered CCST approach,while incompressible/compressible subsonic, transonic and supersonic viscous flows are adequately simulated with adaptively refined Cartesian grid.

关键词： adaptively refined Cartesian grid viscous flow CCST(curvature corrected symmetry technique) boundary condition

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Empirical Analysis on Urbanization Patterns in Zhejiang Province Based on Spatial Economy and GIS

引用

Chinese geographical Science 2006年第3期16卷 193-198页

作者： ge Ying LIANG qi College of Civil Engineering Hohai University Nanjing 210098 China School of Business Nanjing University Nanjing 210093 China

Regional core cities are the growth poles for regional economic development, thus the issue about efficient urbanization pattern has always become a hot spot among researchers and policy makers. The Spatial Economy can be employed to improve it. Nevertheless, there actually exists an obvious gap between its theoretical models and the empirical simulation. To do so, this paper modifies the measurement of initial geographical advantages Stelder gave, and implements the empirical analyses of urban distribution in Zhejiang during the period of 1980-1990 by means of computer simulations in GIS environment. There are several interesting results achieved in this process. Firstly, given the values of parameters （transport cost is r, substitution elasticity of manufacturing sector p, and income share of spending on manufacture δ）, initial geographical advantages have the different impacts on urban systems, namely, urban locations, numbers and sizes over time across space. Secondly, the cities were distributed without any overlay in geographical space, which makes the patterns of urbanization generate the largest possible economic efficiencies. Thirdly, the urban systems-the location, number and size of Cities-from the simulation of the study area are suitable for the actual social and economic situations in the real world during the testing periods. Such results may have substantial implications for the policy how to choose the way of urbanization in a region.

关键词： urbanization pattern Spatial Economy empirical analysis GIS technique initial geographical advantage Zhejiang Province

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Sulfur and carbon co-doped g-C_(3)N_(4)microtubes with enhanced photocatalytic H2 production activity

引用

Frontiers in Energy 2024年第1期18卷 110-121页

作者： Yang ge Quanhao SHEN qi ZHANG Naixu LI Danchen lu Zhaoming ZHANG Zhiwei FU Jiancheng ZHOU School of Chemistry and Chemical Engineering Southeast UniversityNanjing 211189China Shangdong Yellow Triangle Biotechnology Industry Research Institute Co. Ltd.Dongying 257091China Xuzhou B&C Chemical Co. Ltd.Xuzhou 221300China

Metal-free graphitic carbon nitride(g-C_(3)N_(4))has captured significant attention as a low-cost and efficient hydrogen production photocatalyst *** regulating the microstructure and accelerating the separation of photogenerated carriers remain crucial strategies for promoting the photocatalytic performance of this ***,a novel sulfur–carbon co-doped g-C_(3)N_(4)(SCCN)hierarchical microtubules filled with abundant nanosheets inside by thermal polymerization is *** nanosheets create abundant pores and cavities inside the SCCN microtubes,thereby increasing the specific surface area of g-C_(3)N_(4)and providing sufficient reactant attachment ***,the hierarchical structure of SCCN microtubules strengthens the reflection and scattering of light,and the utilization of visible light is favorably *** importantly,co-doping S and C has greatly improved the photocatalytic performance of graphitic carbon nitride,optimized the band gap structure and enhanced the photogenerated carrier ***,the SCCN exhibits a remarkable photocatalytic H_(2)evolution rate of 4868μmol/(g·h).This work demonstrates the potential of multi-nonmetal doped g-C_(3)N_(4)as the ideal photocatalyst for H2 evolution.

关键词： carbon nitride photocatalysis hydrogen production

来源：

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

An Enantioselective Approach to Heteroatom-Containing Bicyclic Derivatives via Inverse-Electron-Demand Diels-Alder Reactions

引用

Chinese Journal of Chemistry 2023年第1期41卷 21-26页

作者： Jun-Xiong He Xu-ge Si qi-Tao lu qian-Wei Zhang Quan Cai Department of Chemistry Research Center for Molecular Recognition and Synthesis220 Handan RoadFudan UniversityShanghai 200433China

Chiral heteroatom-containing bicyclic scaffolds are important pharmacophores and prevalent in bioactive natural products and drug ***,we report a unified approach for the divergent synthesis of chiral heteroatom-containing bicyclic derivatives by lanthanide(lil)-catalyzed asymmetric inverse-electron-demand Diels-Alder reactions of *** reactions occur with vari-ous readily available dihydropyrroles and dihydrofurans as dienophiles,providing a step-economical synthetic platform for densely functionalized ciss-hydroindoles and cis-hydrobenzofurans with excellent yields and *** synthetic utility of this approach is demonstrated by the concise synthesis of(-)-α-lycorane and(-)-lycorine alkaloids.

关键词： Asymmetric catalysis Heterocycles Total synthesis 2-Pyrones Inverse-electron-demand Diels-Alder reaction Cycloaddition

来源：

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

Bang-Bang Principle of Time Optimal Controls and Null Controllability of Fractional Order Parabolic Equations

引用

Acta Mathematica Sinica,English Series 2010年第12期26卷 2377-2386页

作者： qi lu School of Mathematics Sichuan University Chengdu 610064 P. R. China

In this paper, we establish a bang-bang principle of time optimal controls for a controlled parabolic equation of fractional order evolved in a bounded domain Ω of R^n, with a controller w to be any given nonempty open subset of Ω. The problem is reduced to a new controllability property for this equation, i.e. the null controllability of the system at any given time T 〉 0 when the control is restricted to be active in ω× E, where E is any given subset of [0, T] with positive （Legesgue） measure. The desired controllability result is established by means of a sharp observability estimate on the eigenfunctions of the Dirichlet Laplacian due to Lebeau and Robbiano, and a delicate result in the measure theory due to Lions.

关键词： Bang-bang principle time optimal control null controllability fractional order parabolicequation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A strategy of the rural governance for territorial spatial planning in China

引用

Journal of geographical Sciences 2021年第9期31卷 1349-1364页

作者： ge Dazhuan lu Yuqi Jiangsu Center for Collaborative Innovation in geographical Information Resource Development and Application School of GeographyNanjing Normal UniversityNanjing 210023China

Rural spatial governance has become an important part of the spatial governance system under the unified management of urban and rural ***-depth theoretical and practical research on rural spatial governance in terms of promoting national spatial planning can help improve the planning and regulation system of rural *** with a description of rural spatial governance,this paper constructs a theoretical analysis framework of rural spatial governance based on the comprehensive perspective of spatial *** study also discusses the internal processes and feasible paths of rural spatial governance in territorial spatial planning and outlines the theoretical and practical research for enhancing rural spatial *** conclusions are as follows:(1)Rural spatial governance starts with the coordination theory of human-land relationships in the rural regional *** planning and negotiation,governance has effective regulation of rural space and allocates spatial rights in an orderly *** spatial governance highlights the comprehensive governance processes that combine"top-down"and"bottom-up"participation by multiple subjects.(2)Through the"action-efficiency-target"system,the comprehensive governance analysis framework of"matter-organization-ownership"in rural space provides an effective scheme for constructing rural spatial *** spatial governance is characterized by both rigidity and flexibility,the interaction between physical space and spatial relationships,and the superposition of spatial ownership and spatial organization.(3)The rural spatial governance features of interconnecting various scales(regional–village–plot)are conducive to improving the rural spatial governance system.(4)The governance means,participation modes,and value-sharing mechanisms of rural spatial governance help enrich the territorial spatial planning system,promote the integration of multiple regulations,refine the regulation of land use,and

关键词： rural spatial restructuring rural revitalization spatial governance village planning territorial spatial planning

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Time-domain training sequences design for MIMO OFDM channel estimation

引用

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第4期9卷 464-469页

作者： Zhen lu Jian-hua ge Department of Electronic Engineering Shanghai Jiao Tong Universiry Shanghai 200240 China Department of Communications Engineering Xidian University Xi＇an 710071 China

This paper describes a Least Squares (LS) channel estimation scheme for MIMO OFDM systems based on time-domain training sequence. We first compute the minimum mean square error (MSE) of the LS channel estimation, and then derive the optimal criteria of the training sequence with respect to the minimum MSE. It is shown that optimal time-domain training sequence should satisfy two criteria. First, the autocorrelation of the sequence transmitted from the same antenna is an impulse function in a region longer than the channel maximum delay. Second, the cross-correlation between sequences transmitted from different antennas is zero in this region. Simulation results show that the estimator using optimal time-domain training sequences has better performance than that using optimal frequency training sequence at low signal-to-noise ratio (SNR). To reduce the training overhead, a suboptimal training sequence is also proposed. Comparing with optimal training sequence, it has low computation complexity and high transmission efficiency at the expense of little performance degradation.

关键词： MIMO OFDM Channel estimation Time-domain training sequence

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Ion acceleration at dipolarization fronts associated with the interchange instability in Earth's magnetotail

引用

Science China(Technological Sciences) 2020年第11期63卷 2375-2383页

作者： lu HaoYu ge YaSong SUN Chao School of Space and Environment Beihang UniversityBeijing 100191China Institute of geology and geophysics Chinese Academy of SciencesBeijing 100029China

It has been confirmed that dipolarization fronts(DFs)are the result of the interchange instability in the Earth's *** this paper,we use a Hall MHD model to simulate the evolution of the interchange instability that produces DFs along the leading edge.A test particle simulation is performed to study the physical phenomenon of ion acceleration at the *** numerical simulation indicates that almost all particles move earthward and dawnward and then drift to the *** DF-reflected ion population at the duskside appears earlier as a consequence of the asymmetric Hall electric *** that are distributed in a dawn-dusk asymmetric semicircle behind the DF tend to be accelerated to higher energies(>13.5 keV).These high-energy particles eventually concentrate in the *** experience effective acceleration by the dawnward electric field,while they drift through the dawn flank at the front,toward the tail.

关键词： dipolarization fronts interchange instability ion acceleration Hall MHD simulation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A novel interfacial thermodynamic model for predicting solubility of nanoparticles coated by stabilizers

引用

Chinese Journal of Chemical Engineering 2021年第3期34卷 103-112页

作者： Kai ge Yuanhui Ji Xiaohua lu Jiangsu Province Hi-Tech Key Laboratory for Biomedical Research School of Chemistry and Chemical EngineeringSoutheast UniversityNanjing 211189China Key Laboratory of Material and Chemical Engineering Nanjing Tech UniversityNanjing 211816China

To improve the stability of nanoparticles in aqueous solution,polymer or surfactant,*** often added in solutions during the preparation process of nanoparticles,which can induce new interfaces that influence the solubility of *** this work,a novel interfacial thermodynamic model for describing the Gibbs energy of the nanoparticles coated by stabilizers was proposed to predict the solubility of *** the developed model,the activity coefficient of nano metal system was determined by Davies model and that of nano drug system by Perturbed-Chain Statistical Associating Fluid Theory(PC-SAFT).The Gibbs energy of the interface was established as a function of molecular parameters via the application for nano metal ***,the model was further used to predict the solubility of nano drugs itraconazole,fenofibrate,and *** was found that the Gibbs energy of the interface plays an important role especially when the radius of nano metal is less than 40 nm,and the developed model can predict the solubility of nano drug with high accuracy in comparison with the experimental data as well as predict the changing trend of solubility of nano drugs that increases as the particle size ***,the stabilization mechanism of stabilizers on nano drugs was studied which provided theoretical guidance for the selection of polymer or surfactant *** findings showed that the developed model can provide a reliable prediction of the solubility of nanoparticles and help to comprehend the stabilization mechanism of the stabilizers on nano drugs with different particle sizes,which is expected to provide important information for the design of nano drugs formulations.

关键词： Nanoparticles Solubility Gibbs energy of the interface PC-SAFT Molecular parameters

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：