检索结果-南通市图书馆

Chinese Journal of Aeronautics 2023年第1期36卷 423-433页

作者： Jipeng CheN Shouchun XIE he huang School of Mechanical and Electronic Engineering Nanjing Forestry UniversityNanjing 210037China Nanjing Huirui Photoelectric Technology Co. LtdNanjing 211121China

Real-time mixing of multi-species powder challenges Laser Metal Deposition(LMD)of Functionally Graded Materials(FGMs).The current work proposes a novel method of using a static mixer to realize rapid,uniform multi-species powder ***,copper powder and 316L stainless steel powder are selected to complete the powder mixing observation experiment with Scanning Electron Microscope(SEM)and Energy Dispersive Spectrometer(EDS).Secondly,computational fluid dynamics and particle mixing simulation models are used to analyze the flow field and particle motion characteristics in the static ***,LMD experiment and metallo-graphic observation are carried out with 316L stainless steel powder and WC powder to verify the feasibility of the static *** study provides a theoretical and practical basis for powder mixing in laser processing with a static *** conclusions can also be applied to other processing fields requiring real-time and uniform mixing of multi-species powders.

关键词： Homogeneity Laser metal deposition Multi-species powder Mixing Static mixer

Cooperative Spectrum Sensing over Generalized Fading Channels Based on Energy Detection

在线全文

学校读者我要写书评

暂无评论

China Communications 2018年第5期15卷 128-137页

作者： he huang Chaowei Yuan School of Information and Communication Engineering Beijing University of Posts and Telecommunications

This paper analyzes the unified performance of energy detection(ED) of spectrum sensing(SS) over generalized fading channels in cognitive radios(CRs). The detective performance of SS will be obviously affected by fading channels among communication nodes, and ED has the advantages of fast implementation, no requirement of priori received information and low complexity, so it is meaningful to investigate ED over various fading channels. The probability density function(p.d.f.) of α-κ-μ distribution is derived to evaluate energy efficiency for sensing *** detection probability with Marcum-Q function has been derived and the close-form expressions with moment generating function(MGF) method are deduced to achieve ***, exact closed-form analytic expressions for average area under the receiver operating characteristics curve( AUC) also have been deduced to analyze the performance characteristics of ED over α-κ-μ fading ***, cooperative spectrum sensing(CSS) with diversity reception has been applied to improve the detection accuracy and mitigate the shadowed fading features with OR-rule. At last, the results show that the detection capacity of ED will be evidently affected by α-κ-μ fading channels, but appropriate channel parameters can improve sensing performance. In addition, the establishedED-fading pattern is approved by simulations,and it can significantly enhance the detection performance of proposed algorithms.

关键词： energy detection cooperativesensing α-κ-μ distribution receiver diversity

On signaling pathways: hematopoietic stem cell specification from hemogenic endothelium

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2015年第12期58卷 1256-1261页

作者： LONG Yan huang he Bone Marrow Transplantation Center The First Affiliated Hospital School of Medicine Zhejiang University

hematopoietic stem cells(HSCs) are specified and generated during the embryonic development and have remarkable potential to replenish the full set of blood cell lineages. Researchers have long been interested in clarifying the molecular events involved in HSC specification. Many studies have reported the development of methods for generating functional hematopoietic cells from pluripotent stem cells(PSCs-embryonic stem cells(ESCs) and induced pluripotent stem cells(i PSCs)) for decades. However, the generation of HSCs with robust long-term repopulation potential remains a swingeing challenge, of which a major factor contributing to this failure is the difficulty to define the intraembryonic signals related to the specification of HSCs. Since HSCs directly derive from hemogenic endothelium, in this review, we summarize both in vivo and in vitro studies on conserved signaling pathways that control the specification of HSCs from hemogenic endothelial cells.

关键词： HSCs hemogenic endothelium signaling pathways

Decoupling Analysis for a Powertrain Mounting System with a Combination of Hydraulic Mounts

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2013年第4期26卷 737-745页

作者： HU Jinfang CheN Wuwei huang he School of Mechanical and Automobile Engineering Hefei University of Technology

The existing torque roll axis(TRA) decoupling theories for a powertrain mounting system assume that the stiffness and viscous damping properties are constant. However, real-life mounts exhibit considerable spectrally varying stiffness and damping characteristics, and the influence of the spectrally-varying properties of the hydraulic mounts on the powertrain system cannot be ignored. To overcome the deficiency, an analytical quasi-linear model of the hydraulic mount and the coupled properties of the powertrain and hydraulic mounts system are formulated. The influence of the hydraulic mounts on the TRA decoupling of a powertrain system is analytically examined in terms of eigensolutions, frequency, and impulse responses, and then a new analytical axiom is proposed based on the TRA decoupling indices. With the experimental setup of a fixed decoupler hydraulic mount in the context of non-resonant dynamic stiffness testing procedure, the quasi-linear model of the hydraulic mount is verified by comparing the predictions with the measurement. And the quasi-linear formulation of the coupled system is also verified by comparing the frequency responses with the numerical results obtained by the direct inversion method. Finally, the mounting system with a combination of hydraulic mounts is redesigned in terms of the stiffness, damping and mount locations by satisfying the new axiom. The frequency and time domain results of the redesigned system demonstrate that the torque roll axis of the redesigned powertrain mounting system is indeed decoupled in the presence of hydraulic mounts (given oscillating torque or impulsive torque excitation). The proposed research provides an important basis and method for the research on a powertrain system with spectrally-varying mount properties, especially for the TRA decoupling.

关键词： hydraulic mount coupled quasi-linear system motion control TRA decoupling

DYNAMIC PRICING AND COMPENSATION ON heTEROGENEOUS SALES FORCES

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2012年第2期21卷 204-225页

作者： Hongyan XU he huang Jian CheN School of Economics and Business Administration Chongqing UniversityChongqing400044China Chongqing Key Laboratory of Logistics Chongqing UniversityChongqing400044China School of Economics and Management Tsinghua UniversityBeijing100084China

In this paper, we analyze the pricing decision and the compensation strategy of a firm that relies on a heterogeneous sales force to sell its product in two periods. The sales agents＇ selling abilities are their private information and will determine the effectiveness of the agents＇ selling efforts. We introduce three compensation contract strategies, i.e. pooling, semi-separating and separating that the firm can adopt in period one and by applying principle-agent theory, derive the optimal compensation contracts and optimal price for the firm in two periods in each strategy. Compai＇ing these three contract strategies, we found that the optimal strategy for the firm depends on the discount factor. We show that the firm will surely offer separating contracts in period one for some small discount factor, and for some large discount factor pooling contract is certain to be provided in period one. However, semi-separating contracts may be considered for some mediate discount factor, and also may not appear for all discount factors in period one. Our analysis also reveals that the optimal price decreases with the discount factor when pooling contract is offered in period one and increases with the discount factor when separating contracts is offered in period one.

关键词： Sales force sales effort selling abilities pricing

A COMPARISON OF A SIMPLE PROCUREMENT AUCTION AND GENERALIZED NASH BARGAINING

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2009年第3期18卷 341-357页

作者： he huang Hongyan XU Jian CheN School of Economics and Business Administration Chongqing University Chongqing 400030 China School of Economics and Management Tsinghua University Beijing 100084 China

This paper presents a comparison mechanism for a simple procurement auction and generalized Nash bargaining solution in a procurement circumstance. The buyer who hopes to fulfill a project has two options. First, she may award the project to the old provider with an efficient quality by bargaining Second, she may give the project to the firm who submits the lowest bid through a simple procurement second-price sealed-bid auction with a pre-fixed quality. We compare the expected revenue in the auction with the deterministic profit of the bargaining. In different parameters cases, we find the borderline functions between the two options with respect to the buyer＇s bargaining power and the amount of bidders. We also compare our simple procurement auction （SPA） with the optimal multidimensional bid auction by Che （1993）, and find our model protects the buyer＇s private valuation information by forfeiting some profits. Some properties of the difference between the two auctions are proposed, especially there is no revenue difference when the amount of bidders approaches infinity.

关键词： Comparison simple procurement auction generalized Nash bargaining multidimensional auction.

Particle Erosion Resistance of Bionic Samples Inspired from Skin Structure of Desert Lizard, Laudakin stoliczkana

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2012年第4期9卷 465-469页

作者： he huang Yan Zhang Luquan Ren Key Laboratory of Bionic Engineering (Ministry of Education China) Jilin University Changchun 130022 P. R. China College of Mechanical Engineering Tianjin University of Science and Technology Tianjin 300222 P. R. China

In order to improve the particle erosion resistance of engineering surfaces, this paper proposed a bionic sample which is inspired from the skin structure of desert lizard, Laudakin stoliczkana. The bionic sample consists of a hard shell （aluminum） and a soft core （silicone rubber） which form a two-layer composite structure. The sand blast tests indicated that the bionic sample has better particle erosion resistance. In steady erosion period, the weight loss per unit time of the bionic sample is about 10% smaller than the contrast sample. The anti-erosion mechanism of the bionic sample was studied by single particle impact test. The results show that, after the impact, the kinetic energy of the particle is reduced by 56.5% on the bionic sample which is higher than that on the contrast sample （31.2%）. That means the bionic sample can partly convert the kinetic energy of the particle into the deformation energy of the silicone rubber layer, thus the erosion is reduced.

关键词： bionics particle erosion sand blast desert lizard

Integration of InSAR and GPS for hydraulic engineering

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

Science China(Technological Sciences) 2007年第z1期50卷 111-124页

作者： he XiuFeng LUO HaiBin huang QiHuan he Min Institute of Satellite Navigation & Spatial Information System Hohai UniversityNanjing 210098China Institute of Satellite Navigation & Spatial Information SystemHohai UniversityNanjing 210098China Institute of Satellite Navigation & Spatial Information SystemHohai UniversityNanjing 210098China Institute of Satellite Navigation & Spatial Information SystemHohai UniversityNanjing 210098China

Interferometric synthetic aperture radar (InSAR) is a potential earth observation approach, and it has been demonstrated to have a variety of applications in measuring ground movement, urban subsidence and landslides. Currently InSAR provides the ability to map accurate DEM and measure ground deformation to sub-centimeter accuracy. However, many factors affect InSAR to measure ground movement since dam constructions are built in a large scale area with a complicated climate and unstable geology. This paper discusses potential applications of integrated InSAR and GPS to monitor a large-scale ground movement due to hydropower developments. The integration of InSAR and GPS can provide a cost-effective means for monitoring deformation of hydropower developments. Moreover, two novel methods, both the improved spatial interpolating method and estimation of 3D surface motion velocities method, are proposed and the experimental results and analysis are given in this paper.

关键词： InSAR GPS hydraulic and hydropower engineering slides monitoring

A pure quasi-human algorithm for solving the cuboid packing problem

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

Science in China(Series F) 2009年第1期52卷 52-58页

作者： huang WenQi he Kun College of Computer Science and Technology Huazhong University of Science and Technology Wuhan 430074 China

We excavate the wisdom from an old Chinese proverb ＂gold corner, silver side and strawy void＂, and further improve it into ＂maximum value in diamond cave＂ for solving the NP-hard cuboid packing problem. We extract, integrate and formalize the idea by west modern mathematical tools, and propose a pure quasi-human algorithm. The performance of the algorithm is evaluated on two sets of public benchmarks. For 100 strongly heterogeneous difficult benchmarks, experiments show an average packing utilization of 87.31%, which surpasses current best record reported in the literature by 1.83%. For 47 difficult benchmarks without orientation constraint, experiments show an average volume utilization of 92.05%, which improves current best record reported in the literature by 1.05%.

关键词： packing problem NP-hard heuristic quasi-human approach caving degree

Constraining the characters of the upper mantle discontinuities beneath the NE margin of the Tibetan Plateau with a dense broadband seismic array

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2020年第3期63卷 425-438页

作者： he huang Xuzhang SheN Xuzhou LIU Yuansheng ZHANG Lanzhou Institute of Seismology China Earthquake AdministrationLanzhou 730000China School of Earth Sciences and Engineering Sun Yat-Sen UniversityGuangzhou 510275China

Based on observations from a dense broadband seismic array located along the northeastern (NE) margin of the Tibetan Plateau in southeastern Gansu Province,we use receiver functions (RFs) to pick the arrival times of P-to-S converted waves and bin the traces in different grids according to the piercing points of the 410 and 660 km discontinuities in the upper *** depths of the two discontinuities are estimated by the ray tracing method with the IASP91 velocity model and a 3-D tomography *** results indicate the following:(1) The arrival times of the P410s and P660s converted phases are delayed by approximately 1 s than those predicted by the IASP91 *** mantle transition zone (MTZ) is thicker than that in the global model.(2) The synchronous lags in the P410s and P660s arrival times are consistent with low-velocity anomalies in the upper mantle,which are believed to result mainly from the eastward migration of materials beneath the NE margin of the Tibetan Plateau.(3) Combined with previous tomography results,the depression of the'660'discontinuity and the thickened MTZ are somewhat consistent with the big mantle wedge (BMW) ***,due to data limitations,more studies are required to explore the BMW in the future.

关键词： NE margin of the Tibetan Plateau Upper mantle discontinuities Low-velocity anomalies Receiver functions