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A New Kind of Pilot Controlled Proportional Direction Valve with Internal Flow Feedback

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Chinese Journal of Mechanical Engineering 2010年第1期23卷 60-65页

作者： QUAN long XU Xiaoqing YAN zheng ZHANG Xiaojun Institute of Mechatronics Engineering Taiyuan University of Technology Taiyuan 030024 China

Proportional direction valve is one of the most fundamental elements in electronic-hydraulic control technique. Its function is to control the operating speed, direction, position, and strength of output force of the hydraulic actuator continuously. Considering the different application and the cost, the existing technique mainly includes the internal feedback valve used in open loop system, and the electronic closed loop controlled valve used in closed loop system. Because of their different mechanical structure and the gre at different in performance, it brings inconvenience for customer to select, also inconvenience for enterprise to produce. Aiming at this problem, the idea of combining the above two kinds of valves into one body is proposed first, and then the new valve＇s structure to realize this target is designed. The idea intends to apply the displacement pilot flow feedback control principle in present 2-position 2-way valve system to the proportional direction valve of 3-position 4-way system. Newly designed feed forward controller can decouple the interference between the internal feedback and the electronic closed loop. Redundant conversion is designed to electronic switch mode. Experiment on dynamic and static characteristic of new proportional direction valve in internal feedback control mode and electronic closed loop control mode is discussed to prove the new theory is correct. Although the new valve is of excellent dynamic response characteristic, its steady control characteristic in open loop control mode needs to be improved further. The research results prepare one new fundamental element for electronic-hydraulic control technology.

关键词： pilot flow feedback proportional direction valve working principle characteristic research

Production scheduling problems of steelmaking-continuous casting process in dynamic production environment

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Journal of Iron and Steel Research International 2017年第6期24卷 586-594页

作者： Zhong zheng Jian-yu long Xiao-qiang Gao College of Materials Science and Engineering Chongqing University Chongqing 400045 China College of Economics and Business Administration Chongqing University Chongqing 400044 China

A concept of production scenario for the steelmaking continuous casting production process and the mathe- matical description of such concept were proposed. The production scenario was described with the varia- tion of the equipment status and the production material properties based on the executing production schedule. Then, the dynamic characteristics of the production process could be described with the evolu tion process of production scenario. Through analyzing the influence of the dynamic production scenario on production scheduling, three key points about the scheduling problems were identified： the problem for integrating the schedules of different batches that is non-neglected when making a schedule, the problem for matching the material flow with the schedule that should be solved when implementing a schedule, and the problem for eliminating the deviations between the initial schedule and implemented schedule that should be solved when rescheduling in a disturbed environment. Finally, a set of experiments were con- ducted, and the results demonstrated that making the production schedule and solving the rescheduling problem for steelmaking continuous casting process with addressing the above three problems improve the adaptability of the schedule in dynamic environment.

关键词： SchedulingReschedulingSteelmakingContinuous castingDisturbanceProduction scenario

Influence of Temperature on the Inverse Hall-Petch Effect in Nanocrystalline Materials:Phase Field Crystal Simulation

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Acta Metallurgica Sinica(English Letters) 2014年第1期27卷 81-86页

作者： Yulong Zhao zheng Chen Jian long Tao Yang State Key Laboratory of Solidification Processing Northwestern Polytechnical University

The influence of temperature on the inverse Hall-Petch effect in nanocrystalline （NC） materials is investigated using phase field crystal simulation method. Simulated results indicate that the inverse Hall-Petch effect in NC materials becomes weakened at low temperature. The results also show that the change in microscopic deformation mechanism with temperature variation is the main reason for the weakening of the inverse Hall-Petch effect. At elevated temperature, grain rotation and grain boundary （GB） migration seriously reduce the yield stress so that the NC materials exhibit the inverse Hall-Petch effect. However, at low temperature, both grain rotation and GB migration occur with great difficulty, instead, the dislocations nucleated from the cusp of serrated GBs become active. The lack of grain rotation and GB migration during deformation is mainly responsible for the weakening of the inverse Hall-Petch effect. Furthermore, it is found that since small grain size is favorable for GB migration, the degree of weakening decreases with decreasing average grain size at low temperature.

关键词： Phase field crystal (PFC) Nanocrystalline (NC) material Temperature Microscopic deformation mechanism Inverse Hall-Petch effect

Investigating the neutron star physics through observations of several young pulsars in the dipole-field re-emergence scenario

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Science China(Physics,Mechanics & Astronomy) 2024年第12期67卷 197-208页

作者： Yu-long Yan Quan Cheng Xiao-Ping zheng Institute of Astrophysics Central China Normal UniversityWuhan430079China Department of Astronomy Huazhong University of Science and TechnologyWuhan430074China

The observed timing data,magnetic tilt angle χ,and age of young pulsars could be used to probe some important issues about neutron star(NS) physics,e.g.,the NS internal magnetic field configuration,and the number of precession cycles ξ.Both quantities are critical in studying the continuous gravitational wave emission from pulsars,and the latter generally characterizes the mutual interactions between superfluid neutrons and other particles in the NS *** timing behavior of pulsars can be influenced by the dipole field evolution,which instead of decaying,may increase with *** increase in the dipole field may result from the re-emergence of the initial dipole field B_(d,i)that was buried into the NS interior shortly after the birth of the *** this work,the field re-emergence scenario ξ and the internal field configuration of several young pulsars,as well as their B_(d,i) are investigated by assuming typical accreted masses ?***,since the Crab pulsar has an exactly known age and its tilt angle change rate can be inferred from observations,we can set stringent constraints on its ξ,B_(d,i),and ?*** for other young pulsars without exactly known ages and tilt angle change rates,these quantities cannot be accurately determined,we find that their ξ are generally within ~10~4-10~6,and some of them probably have magnetar-strength B_(d,i).Our work could be important for investigating the transient emissions associated with NSs,the origin of strong magnetic fields of NSs,pulsar population,continuous gravitational wave emission from pulsars,and accretion under extreme conditions in principle.

关键词： pulsar neutron star magnetic field

Dynamic Event-triggered Control and Estimation: A Survey

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International Journal of Automation and computing 2021年第6期18卷 857-886页

作者： Xiaohua Ge Qing-long Han xian-Ming Zhang Derui Ding School of Software and Electrical Engineering Swinburne University of TechnologyMelbourne 3122Australia

The efficient utilization of computation and communication resources became a critical design issue in a wide range of networked systems due to the finite computation and processing capabilities of system components(e.g., sensor, controller) and shared network bandwidth. Event-triggered mechanisms(ETMs) are regarded as a major paradigm shift in resource-constrained applications compared to the classical time-triggered mechanisms, which allows a trade-off to be achieved between desired control/estimation performance and improved resource efficiency. In recent years, dynamic event-triggered mechanisms(DETMs) are emerging as a promising enabler to fulfill more resource-efficient and flexible design requirements. This paper provides a comprehensive review of the latest developments in dynamic event-triggered control and estimation for networked systems. Firstly, a unified event-triggered control and estimation framework is established, which empowers several fundamental issues associated with the construction and implementation of the desired ETM and controller/estimator to be systematically investigated. Secondly, the motivations of DETMs and their main features and benefits are outlined. Then, two typical classes of DETMs based on auxiliary dynamic variables(ADVs) and dynamic threshold parameters(DTPs) are elaborated. In addition, the main techniques of constructing ADVs and DTPs are classified, and their corresponding analysis and design methods are discussed. Furthermore, three application examples are provided to evaluate different ETMs and verify how and under what conditions DETMs are superior to their static and periodic counterparts. Finally, several challenging issues are envisioned to direct the future research.

关键词： Networked systems dynamic event-triggered control dynamic event-triggered estimation dynamic event-triggered mechanisms vehicle active suspension system water distribution and supply system

Correlation of p53 gene mutation and expression of P53 protein in cholangiocarcinoma

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World Journal of Gastroenterology 2006年第29期12卷 4706-4709页

作者： Xiao-Fang Liu Hao Zhang Shi-Guang Zhu xian-Ting Zhou Hai-long Su zheng Xu Shao-Jun Li Department of Hepatobiliary Surgery The Affiliated Yantai Yuhuangding Hospital of Qingdao University Medical College Yantai 264000 Shangdong Province China Department of General Surgery The First Affiliated Hospital of China Medical University Shenyang 110001Liaoning Province China

AIM： To characterize the tumor suppressor gene P53 mutations and study the correlation of P53 gene mutation and the expression of P53 protein in cholangiocarcinoma. METHODS： A total of 36 unselected, frozen samples of cholangiocarcinoma were collected, p53 gene status（exon 5-8） and P53 protein were examined by automated sequencing and immunohistochemical staining, combined with the clinical parameters of patients. RESULTS： P53 gene mutations were found in 22 of 36 （61.1%） patients. Nineteen of 36 （52.8%） patients were positive for P53 protein expression. There were significant differences in extent of differentiation and invasion between the positive and negative expression of P53 protein. However, there were no significant differences in pathologic parameters between the mutations and non-mutations. CONCLUSION： The alterations of the P53 gene evaluated by DNA sequence analysis is relatively accurate. Expression of P53 protein could not act as an independent index to estimate the prognosis of cholangiocarcinoma.

关键词： Cholangiocarcinoma p53 gene Mutation DNA sequence

EXTENSION OF COMBINED SELF-CONSISTENT AND MORI-TANAKA APPROACH TO EVALUATION OF ELASTOPLASTIC PROPERTY OF PARTICULATE COMPOSITES

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Acta Mechanica Solida Sinica 2013年第1期26卷 71-82页

作者： xianghe Peng Ning Hu Xuesong long Hengwei zheng Department of Engineering Mechanics Chongqing University State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University Department of Mechanical Engineering Chiba University

The combined self-consistent and Mori-Tanaka approach proposed for the evaluation of the effective elastic property of particulate composites is extended to evMuate the effective elastoplastic property of particulate composites. Suppose there are sufficient identical particle inclusions with total volume fraction c in a representative volume element （RVE） of a particulate composite, these inclusions are separated into two groups, with volume fractions （1 -A-1）c and c/A over the RVE, respectively. We assume that the first group of inclusions has already been embedded in the original matrix to form a fictitious matrix, and the RVE of the composite consists of the fictitious matrix and the second group of particle inclusions. The property of the fictitious matrix is determined by the conventional self-consistent scheme, while the effective elastoplastic property of the composite is determined by the conventional Mori-Tanaka scheme. Analysis shows that, the conventional Mori-Tanaka scheme and self-consistent scheme can be obtained as the two limit cases of the extended approach as A = 1 and A = c~, respectively. The constitutive behavior of the inclusions in either Group I or Group II is identical, indicating the consistency in the description of the constitutive behavior in the two steps. ~klrthermore, the effective elastoplastic behavior of some typical particulate composites is analyzed, and the satisfactory agreement between the computational and experimental results demonstrates the validity of the extended approach. The introduced A can serve reasonably as a parameter, which is related to the actual property of composites and can be identified by experiments, for a more accurate evaluation of the effective elastoplastic property of particulate composites.

关键词： particulate composite elastoplasticity effective property combined self-consistent and Mori-Tanaka approach

A Fixed Point Method for the Linear Complementarity Problem Arising from American Option Pricing

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Acta Mathematicae Applicatae Sinica 2016年第4期32卷 921-932页

作者： xian-Jun SHI Lei YANG zheng-Hai HUANG Department of Mathematics School of ScienceTianjin University

For American option pricing, the Black-Scholes-Merton model can be discretized as a linear comple- mentarity problem （LCP） by using some finite difference schemes. It is well known that the Projected Successive Over Relaxation （PSOR） has been widely applied to solve the resulted LCP. In this paper, we propose a fixed point iterative method to solve this type of LCPs, where the splitting technique of the matrix is used. We show that the proposed method is globally convergent under mild assumptions. The preliminary numerical results are reported, which demonstrate that the proposed method is more accurate than the PSOR for the problems we tested.

关键词： American option pricing finite difference method fixed point method linear complementarityproblem

Goos-Hanchen-like shift related to spin and valley polarization in ferromagnetic silicene

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Chinese Physics B 2021年第10期30卷 523-529页

作者： Mei-Rong Liu zheng-Fang Liu Ruo-long Zhang xian-Bo Xiao Qing-Ping Wu Department of Applied Physics East China Jiaotong UniversityNanchang 330013China School of Computer Science Jiangxi University of Traditional Chinese MedicineNanchang 330004China

We study the Goos-Hanchen-like shift of single silicene barrier under the external perpendicular electric field,off- resonant circularly polarized light and the exchange field modulation using the stationary-phase *** results show that the Goos-Hanchen-like shift of silicene resulting from the external perpendicular electric field does not have the characteristics of spin or valley polarization,while that from off-resonant circularly polarized light or the exchange field is *** importantly,the combined effect of the external perpendicular electric field and the exchange field or off-resonant circularly polarized light can cause the Goos-Hanchen-like shift of the system to be spin and valley *** is particularly worth noting that when the three modulations are considered at the same time,as the exchange field changes,the system will have a positive or negative Goos-Hanchen-like shift.

关键词： Goos-Hanchen-like shift silicene polarization