Stability and accuracy of central difference method for real-time dynamic substructure testing considering mass participation coefficient

For real-time dynamic substructure testing(RTDST),the influence of the inertia force of fluid specimens on the stability and accuracy of the integration algorithms has never been investigated.Therefore,this study proposes to investigate the stability and accuracy of the central difference method(CDM)for RTDST considering the specimen mass participation coefficient.First,the theory of the CDM for RTDST is presented.Next,the stability and accuracy of the CDM for RTDST considering the specimen mass participation coefficient are investigated.Finally,numerical simulations and experimental tests are conducted for verifying the effectiveness of the method.The study indicates that the stability of the algorithm is affected by the mass participation coefficient of the specimen,and the stability limit first increases and then decreases as the mass participation coefficient increases.In most cases,the mass participation coefficient will increase the stability limit of the algorithm,but in specific circumstances,the algorithm may lose its stability.The stability and accuracy of the CDM considering the mass participation coefficient are verified by numerical simulations and experimental tests on a three-story frame structure with a tuned liquid damper.

Feasibility of central loop TEM method for prospecting multilayer water-fi lled goaf

With deep mining of coal mines, prospecting multilayer water-filled goaf has become a new content that results from geophysical exploration in coalfields. The central loop transient electromagnetic （TEM） method is favorable for prospecting conductive layers because of the coupling relationship between its field structure and formation. However, the shielding effect of conductive overburden would not only require a longer observation time when prospecting the same depth but also weaken the anomalous response of underlying layers. Through direct time domain numerical simulation and horizontal layered earth forward modeling, this paper estimates the length of observation time required to prospect the target, and the distinguishable criterion of multilayer water-filled goal is presented with observation error according to the effect of noise on observation data. The observed emf curves from Dazigou Coal Mine, Shanxi Province can distinguish multilayer water-filled goaf. In quantitative inversion interpretation of observed curves, using electric logging data as initial parameters restrains the equivalence caused by coal formation thin layers. The deduced three-layer and two-layer water-filled goals are confirmed by the drilling hole. The result suggests that when observation time is long enough and with the anomalous situation of underlying layers being greater than the observation error, the use of the central loop TEM method to orosoect a multilaver water-filled goaf is feasible.

Impact of central venous port implantation method and access choice on outcomes

BACKGROUND Although the number of patients who need central venous ports for permanent vascular access is increasing,there is still no“gold standard”for the implantation technique.AIM To identify the implantation technique that should be favored.METHODS Two hundred central venous port-implanted patients in a tertiary hospital were retrospectively evaluated.Patients were assigned into two groups according to the access method.The first group comprised patients whose jugular veins were used,and the second group comprised patients whose subclavian veins were used.Groups were evaluated regarding age,sex,application side,primary diagnosis,active follow-up period in the hospital,chemotherapy agents administered,number of complications,and the Clavien-Dindo severity score.The distribution of the variables was tested with the Kolmogorov-Smirnov test and the Mann-Whitney U test.Theχ^(2) test was used to analyze the variables.RESULTS There was no statistically significant difference between the groups regarding age,sex,side,number of chemotherapy drugs,and duration of port usage(P>0.05).Only 2 patients in group 1 had complications,whereas in group 2 we observed 19 patients with complications(P<0.05).No port occlusion was found in group 1,but the catheters of 4 patients were occluded in group 2.One port was infected in group 1 compared to three infected ports in group 2.Two port ruptures,two pneumothorax,one revision due to a mechanical problem,one tachyarrhythmia during implantation,and four suture line problems were also recorded in group 2 patients.We also showed that it would be sufficient to evaluate and wash ports once every 2 mo.CONCLUSION Our results robustly confirm that the jugular vein route is safer than the subclavian vein approach for central venous port implantation.

Assessment of Calcimetric and Titrimetric Methods for Calcium Carbonate Estimation of Five Soil Types in Central Sudan

Despite the CaCO3 estimation using titration method was not reliable, but up to the present time, some soil laboratories in Sudan still used this method. The objective of this study was to compare and assess the results of calcimetric and titrimetric methods of quantitative estimation for soil calcium carbonate of different soils in Sudan. 26 soil samples from five soil profiles were collected from different climatological and ecological regions in central Sudan. CaCO3 equivalent was estimated using calcimeter and titration methods in order to find accurate, rapid and suitable method for soils of Sudan. The results revealed that there are no significant differences between calcimeter and titration methods for calcium carbonate estimation in all studied samples except in samples from Gedaref area. We concluded that when the Calcimeter method used for CaCO3 estimation, the differences between one person and another in detecting titration end point would be avoided, rapid and accurate results would be obtained compared to titration method. Additionally, time would be saved;fewer amounts of chemicals would be used. From this study, we highly recommend using calcimeter method for CaCO3 estimation for soils of Sudan.

Determine the Eigen Function of Schrodinger Equation with Non-Central Potential by Using NU Method

So far, Schrodinger equation with central potential has been solved in different methods but solving this equation with non-central potentials is less dealt with. Solving such equations are way more difficult and complicated and a certain and limited number of non-central potentials can be solved. In this paper, we introduce one of the solvable kinds of such potentials and we will use NU method for solving Schrodinger equation and then by using this method we have calculated particular figures of its energy and function.

Central Discontinuous Galerkin Method for the Navier-Stokes Equations

Central discontinuous Galerkin（CDG）method is used to solve the Navier-Stokes equations for viscous flow in this paper.The CDG method involves two pieces of approximate solutions defined on overlapping meshes.Taking advantages of the redundant representation of the solution on the overlapping meshes,the cell interface of one computational mesh is right inside the staggered mesh,hence approximate Riemann solvers are not needed at cell interfaces.Third order total variation diminishing（TVD）Runge-Kutta（RK）methods are applied in time discretization.Numerical examples for 1D and2 D viscous flow simulations are presented to validate the accuracy and robustness of the CDG method.

Extraction Process Optimization of Total Flavonoids from Mallotus apelta Stems by Central Composite Design/Response Surface Method

[Objectives] To optimize the extraction process of total flavonoids in stems of Mallotus apelta. [Methods]On the basis of singlefactor test,with volume fraction of ethanol,extraction time and ratio of solvent as independent variables,the content of total flavonoids as dependent variables,the completely secondary response surface regression fitting was conducted on the independent and dependent variables,and the Response Surface Method was used to optimize the optimum extraction process of total flavonoids in Mallotus apelta stems and predict the optimum process. [Results] The optimum extraction process of total flavonoids in Mallotus apelta was determined as follows: ethanol concentration of 71. 5%; extraction time of 154. 6 min; solid-liquid ratio of 1∶19. 2; total flavonoids content of 7. 060 mg/g; fitted binomial squared correlation coefficient R^2= 0. 8751.[Conclusions]Composite Design/Response Surface Method could be used in the extraction process optimization of total flavonoids in Mallotus apelta stems,the mathematical model established had high prediction accuracy,the method was simple and operability was good.

Analysis of Present Situation and Influencing Factors of Coping Methods by Parents of Children with Central Nervous System Tumors

Background: Central nervous system (CNS) tumors are the most common solid tumors among children. Due to the severity of the tumors and the complexity of therapeutic regimes, it is very important to examine whether parents of the children with CNS tumors have positive coping methods against the disease. This study aims to analyze the coping methods of the parents and the factors influencing the methods. Methods: A total of 108 parents of brain cancer children admitted from January 2019 to September 2020 were selected as subjects. After collecting the general information of the parents, they were studied using the Coping Health Inventory for Parents (CHIP, Chinese version). Additionally, their coping pattern and the influencing factors were analyzed. Results: The average scores of the three subscales of the CHIP were (4.25 ± 0.939), (3.11 ± 1.205) and (3.60 ± 1.187), respectively. Univariate analysis showed that parents’ education, medical payment methods, places of residence and economic concerns were the main factors influencing the coping methods (all P < 0.05). Conclusions: Healthcare staff should fully evaluate the coping methods adopted by the parents having children with CNS tumors, take targeted nursing measures accordingly, and assist the parents in seeking social support and learning disease-related knowledge. In addition, public education on disease is equally important.

Centralized Solar PV Systems for Static Loads Using Constant Voltage Control Method

The alternative energy resources, like solar, are always complementary due to environmental changes. Energy generation with the sources such as solar and wind is gaining importance and of that photovoltaic conversion is the main focus of researches due to its promising potential as the electrical source. This paper presents the constant voltage method of control where the output of the converter is maintained constant irrespective of the variations in the irradiance with the high step-up isolated efficient single switch DC-DC converter for the solar PV systems. Constant voltage method of control uses the array of photovoltaic systems as its energy source. The output of the Solar PV systems is nonlinear and has its dependency on temperature and irradiance by which the panel voltage and current varies with the variation in irradiance. Constant voltage control method always operates in such a way that the converter voltage is tried to be maintained constantly to the reference voltage which is set by the user. The system used here utilizes high step single switch isolated DC-DC converter and monitors the voltage continuously by varying the duty cycle to maintain the converter voltage always constant. As a way of improving the performance, both the open and closed loop analysis is done where the closed loop analysis uses the PI controller for its performance. The model is implemented in MATLAB and it accepts the irradiance as the input and outputs the constant voltage from the converter and the feasibility of the proposed converter topology is confirmed with experimental results of the prototype model.

基于共词分析法的我国骨科日间手术主题热点研究

目的:对国内骨科日间手术领域已发表文献进行信息计量学可视化研究,深入挖掘其热点研究主题与方向。方法:主要基于万方数据库和中国知网(CNKI),综合运用信息计量学手段从发文量、作者、研究机构等角度进行常规分析,利用共词分析法构建高频关键词共现网络进行数据挖掘。结果:从分析结果上看,2011年—2024年骨科日间手术发文量呈现上升趋势;166篇文献中涉及660位作者,人均发文0.25篇,其中最高产作者的发文量为8篇,核心作者共有16位;192家研究机构中四川大学华西医院发文量排在第一;确定词频≥3的35个关键词为高频关键词,通过中心性分析发现日间手术、半月板、全膝关节置换术、睡眠质量等关键词为研究热点,疼痛控制、脊柱结核、中药外敷疗法等为相对边缘的研究主题,根据中心性差异对高频关键词进行核心区、中间区和边缘区的划分;经凝聚子群分析我国目前骨科日间手术主要有腰椎间盘突出、膝关节和髋关节置换、患者心理状况和睡眠质量评估、术后并发症安全管理4个研究方向。结论:近年来国内骨科日间手术研究呈现上升趋势,但整体发文量偏少;研究人员较为分散,国内研究力量有待壮大;研究前沿分析,研究内容上存在一些薄弱点,需要加强研究的广度和深度。

基于平衡计分卡的公立医院临床专科中心化建设评价模型构建

目的:建立公立医院临床专科中心化建设评价模型。方法:基于平衡计分卡,从中心结构、临床发展能力、财务运营、技术创新和临床转化能力等维度建立公立医院临床专科中心化建设评价框架,通过德尔菲法构建评价指标体系,结合层次分析法来确定权重。结果:构建了包含5个一级指标、11个二级指标,28个三级指标的公立医院专科中心化建设评价模型。结论:本研究构建的公立医院专科中心化建设评价模型具有一定的推广性,在实际应用中,医院可根据实际发展情况重新确定权重系数从而形成适宜医院发展的临床专科中心化建设评价模型。

非中心t分布评估方法应用分析

非中心t分布评估是GB/Z 6113.403-2020给出的EMC符合性确定统计评估的三种方法之一。文章基于标准给出的非中心t分布基本评估方法,分别对该评估方法在发射类项目、敏感度类项目上的具体应用进行了研究,给出了具体的数据处理方法和评估步骤,并对30个相同测试样本的测试数据进行多种组合评估和分析,发现该评估方法与样本数量及样本特性的一致性有很大关系。最后给出了评估样本的选取建议,旨在为电磁兼容非中心t分布测试符合性统计评定提供参考。

“中心岛法”锚碇基础开挖技术研究与应用

以张靖皋长江大桥某超大型深基坑工程为研究背景,详细介绍了深厚软土覆盖层地区中心岛开挖方案的概况及施工工艺流程,并对基坑开挖实施过程中的关键节点和技术进行研究。该项目通过采用中心岛法的开挖方式,有效利用了预留核心土来减小坑底隆起、基坑支护结构过大的位移,可增强深基坑的整体稳定性,提高施工效率,可为类似工程提供施工借鉴。

复方麝香黄芪滴丸成型工艺优选及挥发性成分含量测定

目的优选复方麝香黄芪滴丸成型工艺,并完善该复方的质量标准。方法通过单因素实验筛选复方麝香黄芪滴丸的基质种类、基质和药液比例、滴距的最佳考察范围;以外观性状、丸重差异、溶散时限等作为评价指标,采用星点设计-效应面法优选复方麝香黄芪滴丸最佳成型工艺条件;以3批复方麝香黄芪滴丸为检测样品,采用气相色谱法测定龙脑、麝香酮和藁本内酯含量;色谱柱为HP-5石英毛细管柱,进样口温度260℃,程序升温,检测器温度300℃,分流比10:1,载气为氮气,流速为1.0 mL·min^(-1)。结果复方麝香黄芪滴丸的最佳成型工艺条件为基质:基质=0.99、药物:基质=0.55、滴距=6.00,综合评分为0.8452;龙脑、麝香酮和藁本内酯与相邻成分色谱峰均达到基线分离;3种成分的线性范围依次为0.327~1.962、0.140~0.840、0.7105~4.263μg(均r>0.999);平均加样回收率依次为92.30%(RSD=1.65%,n=6)、101.28%(RSD=0.81%,n=6)、98.99%(RSD=0.65%,n=6);3种成分的平均含量依次为0.2017、0.0847、1.3829 mg·g^(-1)。结论该成型工艺稳定可行,可为复方麝香黄芪滴丸的开发及应用提供参考;建立的气相色谱法能同时测定复方麝香黄芪滴丸中龙脑、麝香酮和藁本内酯的含量,可用于复方麝香黄芪滴丸的质量控制。

公立医院药品集中带量采购执行效果评价研究

目的:通过检验公立医院药品集中带量采购政策实施效果,为药品集采工作高质量发展提供理论依据和实证证据。方法:首先运用德尔菲专家咨询法构建公立医院药品集中带量采购政策实施效果评价体系,再采用统计学方法分析14所三级公立医院第5批国家组织药品集采情况,对其进行评价。结果:评价体系包含集采工作报量质量、集采任务完成质量和集采工作保障力度等3个一级指标,以及14个二级指标。评价体系构建科学合理全面,其中集采任务完成质量、约定采购量是否按时完成、违规采购行为、集采药品供应情况以及非中选产品采购量占比是评价重点。14所三级公立医院第5批国家组织药品集采执行效果评价得分偏低,有较大提升空间。结论:建议加强集采药品的供应保障,畅通医保、医疗和医药间的沟通渠道,提高药品集采工作精细化管理水平,开展药品集采工作常态化监管等。

APPLICATION OF THE MOMENT METHODS TO ANALYSIS OF X-RAY DIFFRACTION LINE PROFILE FOR PA1010-BMI SYSTEM

Pure X-ray diffraction profiles have been analysed for polyamide 1010 and PA1O1O-BMI system by means of multipeak fitting resolution of X-ray diffraction. The methods of variance and fourth moment have been applied to determine the particle size and strain values for the paracrystalline materials. The results indicated that both variance and fourth moment of X-ray diffraction line profile yielded approximately the same values of the particle size and the strain. The particle sizes of (100) reflection have been found to decrease with increasing BMI content, whereas the strain values increased.

Simulation on venting process and valve opening control method for gas trunk pipelines

Determining the venting time of a gas trunk pipeline segment provides an important basis for formulating an emergency plan in the advent of unexpected accidents.As the natural gas venting process corresponds to the transient flow,it is necessary to establish a transient hydraulic-thermal simulation model in order to determine the venting time.In this paper,based on two kinds of venting scenarios in which there is only one venting point in the venting system of a gas trunk pipeline segment—namely,where the venting point is either at one of the two ends or at the junction of two gas trunk pipeline segments—transient hydraulic-thermal simulation models are established.The models consist of gas flow governing equations,the gas state equation,gas physical property equations,initial conditions,and appropriate boundary conditions.The implicit central difference method is used to discretize the gas flow partial differential equations,and the trust-region-dogleg algorithm is used to solve the equations corresponding to each time step,in order to dynamically simulate the whole venting process.The judgment condition for the end of the venting process is that the average pressure of gas trunk pipeline segment is less than 0.11 MPa(actual pressure).Comparing the simulation results of the proposed model with those of the OLGA software and real operational data,we find that the venting time error is less than 10%.On this basis,a venting valve opening control principle is proposed,which prevents the venting noise from exceeded the specified noise value(85 d B)in the venting design of domestic gas pipeline projects.The established calculation model for venting time(dynamic simulation model)for a gas trunk pipeline segment and the proposed opening control principle of venting valve provide reference for the optimal operation of gas pipeline venting systems.

Calibration of Discrete Element Heat Transfer Parameters by Central Composite Design

The efficiency and precision of parameter calibration in discrete element method （DEM） are not satisfactory, and parameter calibration for granular heat transfer is rarely involved. Accordingly, parameter calibration for granular heat transfer with the DEM is studied. The heat transfer in granular assemblies is simulated with DEM, and the effective thermal conductivity （ETC） of these granular assemblies is measured with the transient method in simulations. The measurement testbed is designed to test the ETC of the granular assemblies under normal pressure and a vacuum based on the steady method. Central composite design （CCD） is used to simulate the impact of the DEM parameters on the ETC of granular assemblies, and the heat transfer parameters are calibrated and compared with experimental data. The results show that, within the scope of the considered parameters, the ETC of the granular assemblies increases with an increasing particle thermal conductivity and decreases with an increasing particle shear modulus and particle diameter. The particle thermal conductivity has the greatest impact on the ETC of granular assemblies followed by the particle shear modulus and then the particle diameter. The calibration results show good agreement with the experimental results. The error is less than 4%, which is within a reasonable range for the scope of the CCD parameters. The proposed research provides high efficiency and high accuracy parameter calibration for granular heat transfer in DEM.

CHARACTERISTICS OF TROPICAL CYCLONES IMPACTING A NUCLEAR POWER PLANT IN SOUTHERN FUJIAN AND ESTIMATE OF MINIMUM CENTRAL PRESSURE

Based on tropical cyclone (TC) data for the period 1949 to 2008 and following the Gumbe-Imethod, Pearson-Ⅲ method and determinacy method, this article estimates the possible minimum centralpressure of TCs affecting southern Fujian where a nuclear power will be located. Results show that theobserved minimum central pressure of TCs agrees well with the results determined with the methods aboveand there is little difference between them (the minimum central pressure is 867.4 hPa and 868.1 hPa,respectively, in a 1,000-yr return period). Established with the theory of atmospheric dynamics, thedeterminacy method yields a result of 867.28 hPa/1000 years, only a little smaller than the result of theprobability method. Because of randomicity in parameter adjustment with the Pearson-Ⅲ method whereasthe determinacy method is theoretically solid and its estimates are the smallest of the three methods, it istherefore reasonable, for security and conservative concerns, to adopt the result determined with thedeterminacy method as the possible maximum intensity of TC (with the central pressure being 867.28 hPa ina 1,000-yr return period).

压剪试验机结构及集中泵站液压系统仿真建模研究

为了提升压剪试验机的整体稳定性与可靠性,对压剪试验机结构及集中泵站液压系统仿真建模方法进行了研究。分析压剪试验机结构,明确该结构的工作原理,确定集中泵站液压系统控制压剪试验机结构的详细流程,采用机械结构专用的Abaqus有限元软件构建压剪试验机结构的有限元模型,在MATLAB仿真试验软件中,模拟分析集中泵站液压系统对压剪试验机结构的有限元模型作用情况,通过仿真模型分析压剪试验机变化情况。仿真结果显示,使用集中泵站液压系统作用于压剪试验机结构有限元模型,能够明显改善压剪试验机的位移变化情况,避免压剪试验机发生变形,提升试验机的稳定性。同时使用该集中泵站液压系统能够降低试验机应变数值,控制精度始终在90%以上,可以提高试验机的可靠性。