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A compact scheme for two-dimensional nonlinear time fractional wave equations

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International Journal of Modeling, Simulation, and Scientific Computing 2021年第5期12卷 143-161页

作者： Guanghui Zhang min ren College of Mathematics and Statistics Suzhou University SuzhouAnhui 234000P.R.China

Based on the equivalent integro-differential form of the considered problem, a numerical approach to solving the two-dimensional nonlinear time fractional wave equations(NTFWEs) is considered in this paper. To this end, an alternating direction implicit(ADI) numerical scheme is derived. The scheme is established by combining the secondorder convolution quadrature formula and Crank–Nicolson technique in time and afourth-order difference approach in space. The convergence and unconditional stability of the proposed compact ADI scheme are strictly discussed after a concise solvabilityanalysis. A numerical example is shown to demonstrate the theoretical analysis.

关键词： Two-dimensional nonlinear time fractional wave equations ADI scheme convergence

Research on new software compensation method of static and quasi-static errors for precision motion controller

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第12期8卷 1938-1943页

作者： ren Kun fu Jian-zhong CHEN Zi-chen Department of Mechanical Engineering Zhejiang University Hangzhou 310027 China

To reduce mechanical vibrations induced by big errors compensation, a new software compensation method based on an improved digital differential analyzer (DDA) interpolator for static and quasi-static errors of machine tools is proposed. Based on principle of traditional DDA interpolator, a DDA interpolator is divided into command generator and command analyzer. There are three types of errors, considering the difference of positions between compensation points and interpolation segments. According to the classification, errors are distributed evenly in data processing and compensated to certain interpolation segments in machining. On-line implementation results show that the proposed approach greatly improves positioning accuracy of computer numerical control (CNC) machine tools.

关键词： Static and quasi-static errors Positioning and machining accuracy Digital differential analyzer (DDA) interoolator

Effects of film mulching regime on soil water status and grain yield of rain-fed winter wheat on the Loess Plateau of China

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Journal of Integrative Agriculture 2017年第11期16卷 2612-2622页

作者： XUE Nai-wen XUE Jian-fu YANG Zhen-ping SUN min ren Ai-xia GAO Zhi-qiang College of Agronomy Shanxi Agricultural University Taigu 030801 P.R. China

Shortages and fluctuations in precipitation are influential limiting factors for the sustainable cultivation of rain-fed winter wheat on the Loess Plateau of China. Plastic film mulching is one of the most effective water management practices to improve soil moisture, and may be useful in the Loess Plateau for increasing soil water storage. A field experiment was conducted from July 2010 to June 2012 on the Loess Plateau to investigate the effects of mulching time and rates on soil water storage, evapotranspiration （ET）, water use efficiency （WUE）, and grain yield. Six treatments were conducted：（1） early mulching （starting 30 days after harvest） with whole mulching （EW）; （2） early mulching with half mulching （EH）; （3） early mulching with no mulching （EN）; （4） late mulching （starting 60 days after harvest） with whole mulching （LW）; （5） late mulching with half mulching （LH）; and （6） late mulching with no mulching （LN）. EW increased precipitation storage efficiency during the fallow periods of each season by 18.4 and 17.8%, respectively. EW improved soil water storage from 60 days after harvest to the booting stage and also outperformed LN by 13.8 and 20.9% in each growing season. EW also improved spike number per ha by 13.8 and 20.9% and grain yield by 11.7 and 17.4% during both years compared to LN. However, EW decreased WUE compared with LN. The overall results of this study demonstrated that EW could be a productive and efficient practice to improve wheat yield on the Loess Plateau of China.

关键词： soil water status plastic film mulching precipitation storage efficiency winter wheat the Loess Plateau

Method of analyzing vibration characteristics of armature system of hermetically sealed electromagnetic relay

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第3期8卷 434-438页

作者： ren Wan-bin CUI Li LUO fu-biao ZHAI Guo-fu School of Electrical Engineering and Automation Harbin Institute qf Technology Harbin 150001 China Guilin Aerospace Electronics Company Guilin 541002 China

Published research is minimal on vibration characteristics of hermetically sealed electromagnetic relay (EMR) ex- posed to mechanical environment. The vibration characteristics of armature system, link contact system with electromagnetic system will cause EMR malfunction. The nonlinear dynamics model of armature systems was studied by considering electro- magnetic attraction force and opposite mechanical force in this paper. Angular displacements of armature under different sinu- soidal vibration conditions are solved in order to obtain the failure mode result from armature system. Vibration tests showed the presented analyzing method is suitable for EMR. The conclusions are instructive for increasing vibration resistance of armature systems of EMR, and are significant for reliability design of switch apparatus.

关键词： Hermetically sealed electromagnetic relay (EMR) Armature system Vibration characteristics Analyzing method

Effect of Dual Trigger In Vitro Fertilization and Intracytoplasmic Sperm Injection During the Gonadotropin-releasing Hormone-Antagonist Cycle on Final Oocyte Maturation and Cumulative Live Birth Rate in Women with Diminished Ovarian Reserve

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Current Medical Science 2022年第5期42卷 1066-1070页

作者： Yu-meng ren Yan-bin WANG min fu Qiu-xiang ZHANG Huan SHEN Hong-jing HAN fu-mei GAO Reproductive Center of Peking University People’s Hospital Beijing100044China

Objective It is well known that a dual trigger treatment can improve clinical outcomes of in vitro fertilization(IVF)in high or normal ovarian ***,it is not clear whether dual triggering also benefits patients with diminished ovarian reserve(DOR).The aim of this study was to investigate whether a dual trigger treatment of gonadotropin-releasing hormone(GnRH)agonist combined with human chorionic gonadotropin(hCG)for final follicular maturation improves the cumulative live birth rate(CLBR)during the GnRH-antagonist cycle in patients with *** This retrospective study included patients with DOR who received a GnRH-antagonist protocol during IVF and intracytoplasmic sperm injection(IVF-ICSI)cycles at Peking University People’s Hospital from January 1,2017 through December 31,*** maturation was triggered by GnRH combined with hCG(n=110)or hCG alone(n=71).Embryos were transferred on the third day after oocyte retrieval or during a subsequent freeze-thaw *** were followed up for 3 *** The dual trigger treatment did not affect CLBR,which is an overall determinant of the success rate of assisted reproductive technology(ART).Women in the dual trigger group had significantly higher rates of fertilization than those in the hCG group(90.1%vs.83.9%,P=0.040).Conclusion Dual trigger with GnRH agonist and hCG did not improve CLBR in patients with DOR,but did slightly improve fertilization rate,oocyte count,and embryo quality.

关键词： dual trigger gonadotropin releasing hormone antagonist protocols diminished ovarian reserve cumulative live birth rate

Microstructure Study of Photoluminescent Porous Silicon

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Chinese Physics Letters 1996年第1期13卷 35-38页

作者： WENG Yu-min ZONG Xiang-fu Materials Science Institute Fudan UniversityShanghai 200433

We have studied the microstructure and photoluminescent properties of porous *** resolution observations revealed that the microstructure of porous Si consists with nano-crystaliites Si embedded in the surrounding amorphous *** struc-ture of nano-crystallites of porous Si is not consis tent with the usual diamond struc-ture of bulk *** photoluminescence from porous Si is due to the quantum com finement of carriers in this structure.

关键词： porous struc microstructure

MOTION VELOCITY SMOOTH LINK IN HIGH SPEED MACHINING

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Chinese Journal of Mechanical Engineering 2007年第2期20卷 17-20页

作者： ren Kun fu Jianzhong CHEN Zichen Mechanical Engineering Department Zhejiang University Hangzhou 310027 China

To deal with over-shooting and gouging in high speed machining, a novel approach for velocity smooth link is proposed. Considering discrete tool path, cubic spline curve fitting is used to find dangerous points, and according to spatial geometric properties of tool path and the kinematics theory, maximum optimal velocities at dangerous points are obtained. Based on method of velocity control characteristics stored in control system, a fast algorithm for velocity smooth link is analyzed and formulated. On-line implementation results show that the proposed approach makes velocity changing more smoothly compared with traditional velocity control methods and improves productivity greatly.

关键词： High speed machining Motion velocity link S-type control equation

Limiting Case of 1D Delta Anyon Model

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Communications in Theoretical Physics 2008年第12期50卷 1265-1268页

作者： ZHU ren-Gui WANG An-min College of Physics and Electronic Information Anhui Normal University Wuhu 241000 China Department of Modern Physics University of Science and Technology of China Hefei 230026 China

In order to analyze a limiting case of the 1D delta anyon model,the coupling strength of the δ interactionc is modified to become a function of the anyonic parameter κ.A pedagogic derivation of the solution for this modifiedmodel using the method of anyon-boson mapping plus Bethe ansatz is *** limiting case as κ→π andsimultaneously c→0,which was previously neglected,is *** unexpected properties of this limiting case *** BAEs are compared with previous results.

关键词： anyon Bethe ansatz

On pricing of corporate securities in the case of jump-diffusion

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Applied Mathematics(A Journal of Chinese Universities) 2014年第2期29卷 205-216页

作者： ren Xue-min JIANG Li-shang Department of Mathematics Tongji University

Structural models of credit risk are known to present vanishing spreads at very short maturities. This shortcoming, which is due to the diffusive behavior assumed for asset values, can be circumvented by considering discontinuities of the jump type in their evolution over time. In this paper, we extend the pricing model for corporate bond and determine the default probability in jump-diffusion model to address this issue. To make the problem clearly, we first investigate the case that the firm value follows a geometric Brownian motion under similar assumptions to those in Black and Scholes（1973）, Briys and de Varenne（1997）, i.e, the default barrier is KD （t, T） and the recovery rate is （1 -w）, where D （t, T） is the price of zero coupon default free bond and w is a constant （0 〈 w 〈 1）. By changing the numeraire, we obtain the closed-form solution for both the price of bond and default probability. further, we consider the case of jump-diffusion and suppose that a firm will go bankruptcy if its value Vt 〈 KD （t, T） and at the same time, the bondholder will receive （1 - w） vt/k By introducing the Green function of PDE with absorbing boundary and converting the problem to an II-type Volterra integral equation, we get the closed-form expressions in series form for bond price and corresponding default probability. Numerical results are presented to show the impact of different parameters to credit spread of bond.

关键词： default risk corporate bond stochastic interest rate jump diffusion process.