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Anti-plane pull-out of a rigid line inclusion from an elastic medium

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Applied Mathematics and Mechanics(English Edition) 2023年第5期44卷 809-822页

作者： Yansong wang Baolin wang Youjiang CUI kaifa wang Harbin Institute of Technology Shenzhen Campus Harbin Institute of TechnologyHarbin 150001China

The transient and static anti-plane problem of a rigid line inclusion pulled out from an elastic medium is *** singular integral equation method is used to solve the stress *** the static load,the stress intensity factor(SIF)at the inclusion tips increases with the medium *** problem becomes equivalent to an inclusion in a medium with an infinite length when the length of the medium is 3.5times longer than that of the ***,under the transient load,the maximum value of the SIF occurs when the medium length is about two times the inclusion ***,the relation between the pull-out force and the anti-plane displacement is *** conclusions are useful in guiding the design of fiber reinforced composite materials.

关键词： pull-out rigid line inclusion anti-plane stress intensity factor(SIF) stress singularity

Vibration analysis of piezoelectric sandwich nanobeam with flexoelectricity based on nonlocal strain gradient theory

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Applied Mathematics and Mechanics(English Edition) 2020年第6期41卷 859-880页

作者： Shan ZENG kaifa wang Baolin wang Jinwu WU Jiangxi Key Laboratory of Micro Aeroengine School of Aircraft EngineeringNanchang Hangkong UniversityNanchang 330063China Graduate School at Shenzhen Harbin Institute of TechnologyHarbin 150001China School of Engineering Western Sydney UniversityPenrithNSW 2751Australia

A nonlocal strain gradient theory(NSGT) accounts for not only the nongradient nonlocal elastic stress but also the nonlocality of higher-order strain gradients,which makes it benefit from both hardening and softening effects in small-scale *** this study, based on the NSGT, an analytical model for the vibration behavior of a piezoelectric sandwich nanobeam is developed with consideration of flexoelectricity. The sandwich nanobeam consists of two piezoelectric sheets and a non-piezoelectric core. The governing equation of vibration of the sandwich beam is obtained by the Hamiltonian principle. The natural vibration frequency of the nanobeam is calculated for the simply supported(SS) boundary, the clamped-clamped(CC) boundary, the clamped-free(CF)boundary, and the clamped-simply supported(CS) boundary. The effects of geometric dimensions, length scale parameters, nonlocal parameters, piezoelectric constants, as well as the flexoelectric constants are discussed. The results demonstrate that both the flexoelectric and piezoelectric constants enhance the vibration frequency of the *** nonlocal stress decreases the natural vibration frequency, while the strain gradient increases the natural vibration frequency. The natural vibration frequency based on the NSGT can be increased or decreased, depending on the value of the nonlocal parameter to length scale parameter ratio.

关键词： piezoelectric nanobeam sandwich structure flexoelectric nonlocal strain gradient theory(NSGT)

Analysis of t-test misuses and SPSS operations in medical research papers

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Burns & Trauma 2019年第1期7卷 290-294页

作者： Guangping Liang Wenliang Fu kaifa wang State Key Laboratory of Trauma Burnsand Combined InjuryInstitute of Burn ResearchSouthwest HospitalThird Military Medical University(Army Medical University)Chongqing 400038People’s Republic of China School of Mathematics and Statistics Southwest UniversityChongq

In medical research papers,the selection of appropriate statistical methods serves as one of the pivotal premises to ensure the quality of papers and credibility of their results[1–3].To correctly perform the statistical analysis of quantitative data,two key points should be *** is to identify the type of experimental design correctly,and the other is to check whether data meets the preconditions of parameter test[2–4].Otherwise,it may cause different misuse in some situations and may even draw different or opposite conclusions about the same data.

关键词： app operations papers

Global dynamics of a viral infection model with full logistic terms and antivirus treatments

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International Journal of Biomathematics 2017年第1期10卷 209-232页

作者： Lijuan Song Cui Ma Qiang Li Aijun Fan kaifa wang Department of Mathematics School of Biomedical Engineering Third Military Medical University Chongqing 500038 P. R. China Center for Hypertension and Metabolic Diseases Department of Hypertension and EndocrinologyDaping Hospital Third Military Medical University Chongqing 400038 P. R. China Chongqing Institute of Hypertension Chongqing 400042 P. R. China Chongqing Academy of Science and Technology Chongqing 401123 P. R. China

In this paper, mathematical analysis of the global dynamics of a viral infection model in vivo is carried out. Though the model is originally to study hepatitis C virus （HCV） dynamics in patients with high baseline viral loads or advanced liver disease, similar models still hold significance for other viral infection, such as hepatitis B virus （HBV） or human immunodeficiency virus （HIV） infection. By means of Volterra-type Lyapunov functions, we know that the basic reproduction number R0 is a sharp threshold para- meter for the outcomes of viral infections. If R0 ~ 1, the virus-free equilibrium is globally asymptotically stable. If R0 ~ 1, the system is uniformly persistent, the unique endemic equilibrium appears and is globally asymptotically stable under a sufficient condition. Other than that, for the global stability of the unique endemic equilibrium, another suffi- cient condition is obtained by Li-Muldowney global-stability criterion. Using numerical simulation techniques, we further find that sustained oscillations can exist and different maximum de novo hepatocyte influx rate can induce different global dynamics along with the change of overall drug effectiveness. Finally, some biological implications of our findings are given.

关键词： Virus dynamics model Volterra-type Lyapunov function Li-Muldowneyglobal-stability criterion uniform persistence sustained oscillation.

PALYNOLOGICAL AND ALGAL ASSEMBLAGES FROM THE SEDIMENTS OF OKINAWA TROUGH

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Chinese Journal of Oceanology and Limnology 1984年第2期2卷 228-242页

作者： wang kaifa (Tongji University, Shanghai)Sun Yuhua (Second Institute of Oceanography, National Oceanographic Bureau, Hangzhou) Tongji University Shanghai Second Institute of Oceanography National Oceanographic Bureau Hangzhou

According to the distribution of spores, pollen and algae in the surface sediments, Okinawa Trough may be divided into three palynological regions: 1) Pinus-Quercus-Pteridium palynological region lying between the two slopes of Okinawa Trough, 2) Pintts-Castanopsis-Quercus palynological region lying north of the trough and 3) Pinus-Quercus-Polypodiaceae palynological region lying south of the trough. Comparing the sporo-pollen assemblages of the column sections with each other, five sporo-pollen zones have been distinguished and their ages determined. Four problems about the palynology of the trough sediments have been discussed.

关键词： show PALYNOLOGICAL AND ALGAL ASSEMBLAGES FROM THE SEDIMENTS OF OKINAWA TROUGH

Numerical study of the radio-frequency biased accelerating system in ion thrusters

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Plasma Science and Technology 2023年第8期25卷 87-102页

作者：白进纬曹勇李阳王开发田滨胡远 School of Science Harbin Institute of Technology(Shenzhen)Shenzhen 518055People's Republic of China School of Mechanical Engineering and Automation Harbin Institute of Technology(Shenzhen)Shenzhen 518055People's Republic of China School of Aeronautics and Astronautics University of Electronic Science and Technology of ChinaChengdu 611731People's Republic of China State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190People's Republic of China

A 2D-3V implicit immersed-finite-element particle-in-cell(IFE-PIC)model is introduced to investigate the radio-frequency(RF)self-bias accelerating system applied in the RF ion thruster.A set of holes in a two-grid system with slit apertures is simulated in Cartesian *** characteristics of the plasma plume,such as the ion density,the neutralization rate and the ion and electron current density were investigated for different RF voltage amplitudes(600-1200V)and frequencies(6-30 MHz).Furthermore,the performance of the thruster was also carefully *** simulation results show that a well-focused plasma beam can be formed when the voltage amplitude is larger than 900 V and the frequency exceeds the reciprocal of ion transit time(≥12 MHz)in our simulation *** performance of the system can be evidently improved by increasing the voltage amplitude and the frequency,and the losses of the particle and thrust are reduced *** bulk region of the plasma beam downstream shows good quasi-neutrality,and the ions are dominant in the peripheral region when a well-focused state is *** high ion density beamlet in the periphery of the ion beam is closer to the axis when the voltage amplitude is increasing,while it is expanded radially when increasing the *** electrons have been observed upstream,and this mainly occurs in the phase in which the electron cannot escape.

关键词： ion thruster radio-frequency biased grids implicit immersed-finite-element particlein-cell plasma plume

GLOBAL STABILITY IN A VIRAL INFECTION MODEL

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Annals of Differential Equations 2005年第3期21卷 427-430页

作者： wang kaifa wang Wendi Liu Xianning College of Medicine Third Military Medical- University Chongqing 400038 Department of Math. Southwest China Normal University Chongqing 400715

This paper investigates the global stability of a viral infection model with lytic immune response. If the basic reproductive ratio of the virus is less than or equal to one, by the LaSalle＇s invariance principle, the disease-free steady state is globally asymptotically stable. If the basic reproductive ratio of the virus is greater than one but less than or equal to a constant, which is defined by the parameters of the model, then the immune-exhausted steady state is globally asymptotically stable. The endemic steady state is globally asymptotically stable if the inverse is valid.

关键词： virus dynamics lytic immune response global stability

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卡方检验误用辨析

中华烧伤与创面修复杂志 2024年第5期40卷 482-488页

作者：张平原王开发西南大学数学与统计学院重庆400715

计数资料在生物医学研究中十分常见,此类资料常常被整理为列联表的形式。对计数资料,常见的研究目的是检验2个因素之间是否独立,因此常用χ^(2)检验来进行统计分析,却容易忽略χ^(2)检验的适用条件和不同条件下对结果的校正。此外,对计... 详细信息

计数资料在生物医学研究中十分常见,此类资料常常被整理为列联表的形式。对计数资料,常见的研究目的是检验2个因素之间是否独立,因此常用χ^(2)检验来进行统计分析,却容易忽略χ^(2)检验的适用条件和不同条件下对结果的校正。此外,对计数资料,还有检验2个分类变量之间是否存在线性变化趋势、结果是否一致等研究目的,因此如何根据不同的研究目的选择合适的检验方法,也是实际应用时值得关注的问题。该文通过系列示例比较系统地总结归纳了各类计数资料的常用统计分析方法,并对常见的误用情况进行了辨析。

关键词：生物医学研究数据说明,统计计数资料列联表 χ^(2)检验

Assessing the mechanism of citywide test-trace-isolate Zero-COVID policy and exit strategy of COVID-19 pandemic

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Infectious Diseases of Poverty 2022年第5期11卷 97-98页

作者： Pei Yuan Yi Tan Liu Yang Elena Arufo Nicholas H.Ogden Guojing Yang Haixia Lu Zhigui Lin Weichuan Lin Wenjun Ma Meng Fan kaifa wang Jianhe Shen Tianmu Chen Huaiping Zhu Laboratory of Mathematical Parallel Systems(LAMPS) Department of Mathematics and StatisticsYork University4700 Keele StreetTorontoON M3J1P3Canada Key Laboratory of Tropical Translational Medicine of Ministry of Education and School of Tropical Medicine and Laboratory Medicine The First Afliated Hospital of Hainan Medical UniversityHainan Medical UniversityHaikouHainanChina 不详

Background:Countries that aimed for eliminating the cases of COVID-19 with test-trace-isolate policy are found to have lower infections,deaths,and better economic performance,compared with those that opted for other mitigation ***,the continuous evolution of new strains has raised the question of whether COVID-19 eradication is still possible given the limited public health response capacity and fatigue of the *** aim to investigate the mechanism of the Zero-COVID policy on outbreak containment,and to explore the possibility of eradication of Omicron transmission using the citywide test-trace-isolate(CTTI)***:We develop a compartmental model incorporating the CTTI Zero-COVID policy to understand how it contributes to the SARS-CoV-2 *** employ our model to mimic the Delta outbreak in Fujian Province,China,from September 10 to October 9,2021,and the Omicron outbreak in Jilin Province,China for the period from March 1 to April 1,*** and sensitivity analyses were conducted using dynamical system and Latin Hypercube Sampling/Partial Rank Correlation Coefcient(PRCC).Results:Calibration results of the model estimate the Fujian Delta outbreak can end in 30(95%confdence interval CI:28–33)days,after 10(95%CI:9–11)rounds of citywide *** emerging Jilin Omicron outbreak may achieve zero COVID cases in 50(95%CI:41–57)days if supported with sufcient public health resources and population compliance,which shows the efectiveness of the CTTI Zero-COVID ***:The CTTI policy shows the capacity for the eradication of the Delta outbreaks and also the Omicron ***,the implementation of radical CTTI is challenging,which requires routine monitoring for early detection,adequate testing capacity,efcient contact tracing,and high isolation compliance,which constrain its benefts in regions with limited ***,these challenges become even more acute in the face of more contagious variant

关键词： COVID-19 Transmission model Zero-COVID policy Citywide testing Test-trace-isolate Exit strategy