带定压活门的液压阻尼器建模因素分析

针对现有带定压活门的液压阻尼器模型考虑因素不同、形式不统一等问题,通过分析油液含气和压缩性、阀口液动力、阀口流量系数和等效面积、串油管路阻力和管路部分油液压缩性等因素对液压阻尼器等效阻尼及阻尼力峰值的影响,建立了液压阻尼器定压活门内置与外接时统一的力学模型。将某型带定压活门的液压阻尼器在1、9、26 mm共3种不同激振幅值下等效阻尼及阻尼力峰值的计算结果与实验值进行对比,结果显示,等效阻尼误差分别为–9.994 5%、0.672 4%和–2.757 2%,阻尼力峰值误差分别为–0.457 4%、1.973 3%和–4.074 9%,该结果验证了所建力学模型的准确性。在进行影响因素分析时发现,油液体积弹性模量在低压时对含气量较为敏感,随着含气量的增加急速下降,弹性模量的改变对等效阻尼和阻尼力峰值均有较大影响,特别是在激振幅值较小的情况下表现更明显;阀口液动力对定压活门开启后的阻尼力峰值影响较大,而对等效阻尼的影响较小;阀口流量系数取常量且阀口等效面积简化成阀芯位移的一次函数后对等效阻尼及阻尼力峰值基本没有影响;定压活门外接时,串油管路阻力和管路部分油液压缩性对等效阻尼和阻尼力峰值的影响都不大。

糖尿病小鼠模型的常见种类及其构建要素分析

糖尿病是一种以胰岛素绝对或相对缺乏导致高血糖为特征的疾病,其高发病率和并发症对患者生活产生极大的影响。动物模型被广泛运用于研究糖尿病及其并发症的发生机制及治疗方案。由于糖尿病类型的不同,其发病机制和发病特征也不同,导致治疗方案不同。动物实验除了考虑动物的遗传因素与生理特征(性别、年龄)外,还需要考虑实验方案及各种应对方案,这些因素对实验数据、实验结果的可重复性和稳定性有着重要影响。因此,糖尿病研究需要选择合适的动物模型进行实验:1型糖尿病以胰岛素绝对缺乏为特征,现有的1型糖尿病小鼠模型包括化学(STZ诱导)诱导型和自发性糖尿病模型(NOD小鼠)等;2型糖尿病以胰岛素抵抗和葡萄糖耐量受损为主,现有的2型糖尿病动物模型包括高脂饮食诱导型、自发性(包括单基因肥胖小鼠和多基因肥胖小鼠)模型和遗传修饰小鼠模型。本综述主要总结了糖尿病小鼠模型的常见种类和构建要素,以及选用时需考虑的关键因素,并探讨了这些因素对糖尿病研究的影响,以期为相关研究提供参考。

金融房价观点 宏观调控指标--房地产市场交易金融宏观建模探讨

房地产贷款是促进和支撑房地产开发建设的金融支柱,个人住房贷款则是撬动和托起商品住房市场买卖交易的金融杠杆。房地产市场的表现主要由场外资金的流入撬动、场内资金的流转促进,以及供需矛盾等因素所共同决定。场内资金惟有场外资金的激活才能流转,新进的场外资金强度越大,售换房产的场内资金流转量越高,市场交易越活跃。兴旺的楼市未必是泡沫——要区分信贷资金和自有资金分别起的杠杆和内在作用。场外资金的主力来自银行贷款。市场调控的牛鼻子在于调控个人住房购置贷款。本文提出杠杆增熵、本金增熵、本杠比、贷占比、市场增熵、市场熵值、杠杆调控指数和本金调控指数等市场交易金融宏观指标,为衡量房地产市场交易金融因素的作用,研判市场发展趋势、泡沫性质与程度,提供了新颖有效的数字工具——经广州、深圳统计数据建模例示验证。

实验性自身免疫葡萄膜炎大鼠模型炎症程度影响因素及中西医病证特点分析

目的:探讨不同的乳化混合物及乳化方法对实验性自身免疫性葡萄膜炎(EAU)大鼠模型炎症程度的影响及当下EAU模型特点分析。方法:通过给路易斯(Lewis)大鼠皮下注射弗氏完全佐剂(CFA)乳化的光感受器间视黄醇结合蛋白(IRBP)1177-1191皮下免疫,同时予以腹腔注射或不注射百日咳毒素(PTX),建立EAU模型。使用裂隙灯、苏木素-伊红(HE)染色、眼底光学相干断层扫描对EAU造模相关影响因素进行了评估,包括乳化混合物(IRBP1177-1191、PTX、灭活的结核分枝杆菌)的不同剂量及4种不同乳化方法。通过慢性葡萄膜炎的中西医临床诊断标准及病证特点,对EAU动物模型的分类、特点、造模方法、优缺点及中西医病证的吻合度进行归纳与分析。结果:就乳化混合物的乳化剂量而言,增加灭活的结核分枝杆菌、抗原肽的剂量可以加重EAU大鼠眼前节炎症反应。增加注射PTX可以加重EAU大鼠眼前节炎症反应及视网膜厚度。就乳化方法而言,EAU模型的严重程度与乳化方法密切相关。4种乳化方法均可以成功诱导大鼠EAU。相比较而言,超声波细胞粉碎机和T10基本型分散机可以在短时间内获得乳化成功的乳液。乳化混合物的乳化程度也影响EAU大鼠模型严重程度。现有的EAU动物模型与西医诊断及中医眼部主证吻合度较高。结论:IRBP1177-1191、PTX、灭活的结核分枝杆菌、乳化方法可通过不同的途径影响EAU模型的严重程度。现有的EAU动物模型可以较好地模拟西医临床特点,但欠缺中医病因病机及证候特点。因而有必要构建病证结合的EAU动物模型。

我国人口时间序列拟合模型的比较

通过对我国1949年至2012年共49年的人口数据进行实证分析,分别运用确定性因素分解法和ARIMA模型两种不同的时间序列分析方法,对我国人口的变化规律进行了拟合研究。

火电机组热力系统性能故障识别

建立火电机组热力系统实时性能监测技术,是保障机组安全、高效运行的有效途径。以甘肃某电厂超临界350 MW火电机组为研究对象,以换热器为例,利用主导因素建模方法对设备运行规律进行仿真实验,得出长期趋势项、周期项以及随机扰动项的加和共同构成了监测偏差的结论。在此基础上,结合时间序列分解技术,建立依据监测偏差值的统计数字特征的热力系统部件特性可控状态判据,提出了故障识别的方法。

政府资产中公共管理与公共服务用地价值核算研究

公共管理与公共服务用地作为政府资产的重要组成部分,其价值核算是完成政府资产负债核算的重要内容。本文认为除核算基于权责发生制的当期价值外,基于政府未来偿债能力核算公共管理与公共服务用地使用类型发生转换后的价值区间更具现实意义,其价值区间取决于政府在面临债务危机时对该地的处理方式,可作为当期价值核算的修正依据。本文以武汉市2016年成交的382块土地为样本,综合考虑人口密度、容积率、使用期限、土地用途等多种影响因素,采取基准地价修正系数法、市场比较法、影响因素建模法对其价值及价值修正区间核算进行对比分析。研究结果表明,在土地使用类型不发生改变时,采用市场比较法核算其当期价值较为合理;在土地使用类型发生改变时,采用影响因素建模法核算其价值修正区间较为合理。

A Summary of Studies on Prediction of Urban Construction Land Scale

Research results of prediction of urban construction land scale were sum- marized from the aspects of influencing factors of construction land expansion and prediction models of construction land scale, and their characteristics and deficiencies of these studies were analyzed to provide reference for deep research on pre- diction of urban construction land scale in China. The results show that there are few studies on basic theories about total scale of construction land presently, and there is no theoretical framework in studies on influencing factors. A single model has been used to conduct prediction on a small scale in most studies, but there have been few studies on iarge-scale prediction based on comprehensive benefit. Therefore, it is necessary to strengthen the exploration of basic theory and mechanism of urban construction land prediction, study iarge-scale prediction based on comprehensive benefit, and strengthen the comprehensive application of econometric analysis, spatial analysis and information technology analysis.

变电站操作过程的人为可靠性分析

从工程应用的角度出发,对变电站操作过程中的人为因素进行建模分析,将人为因素分为静态影响因素和动态影响因素,根据操作任务的特点,将操作场景分为常规类型操作、长时间持续操作和应急操作三类,针对容易发生人为失误的后两种操作情景,分别提出了相应的人为操作可靠性分析方法,并以变电站实际操作为例,对所提出的方法进行验证。算例分析表明,人为因素模型和人为可靠性分析方法能够充分考虑操作过程中的人为因素,能对操作风险进行事前评估,为操作风险预控和操作规范的制定提供参考。

Physical activity, sedentary behavior, and long-term cardiovascular risk in young people: A review and discussion of methodology in prospective studies

The long-term effects of physical activity （PA） or sedentary behavior on cardiovascular health in young people are not well understood. In this study, we use a narrative format to review the evidence for a prospective association with adiposity and other well-established biological cardiovascular risk factors in healthy young people, considering only studies with at least 2 years of follow-up. PA appears to elicit a long-term beneficial effect on adiposity and particularly markers of cardiovascular health. With adiposity, however, a few studies also reported that higher levels of PA were associated with higher levels of adiposity. Time spent sedentary does not appear to be related to adiposity or markers of cardiovascular health independent of PA. We then discuss the uncertainties in the underlying causal chain and consider a number of alternative modeling strategies, which could improve our understanding of the relationship in future studies. Finally, we consider the current methodology for assessing PA and sedentary time.

Selection model of trip time for rural population

Referring to the 1 248 survey data of rural population in 14 provinces of China, the influencing factors of trip time choice were analyzed. Based on the basic theory of disaggregate model and its modelling method, nine grades were selected as the alternatives of trip time, the variables affecting time choice and the method getting their values were determined, and a multinomial logit (MNL) model was developed. Another 1 200 trip data of rural population were selected to testify the model's validity. The result shows that the maximum absolute error of each period between calculated value and statistic is 3.6%, so MNL model has high calculation accuracy.

Thermal conductivity modeling of water containing metal oxide nanoparticles

The nano particles have demonstrated great potential to improve the heat transfer characteristics of heat transfer fluids.Possible parameters responsible for this increase were studied. The heat transfer profile in the nanolayer region was combined with other parameters such as volume fraction, particle radius thermal conductivity of the fluid, particle and nanolayer, to formulate a thermal conductivity model. Results predicting the thermal conductivity of nanofluids using the model were compared with experimental results as well as studies by other researchers. The comparison of the results obtained for the Cu O/water and Ti O2/water nanofluids studied shows that the correlation proposed is in closest proximity in predicting the experimental results for the thermal conductivity of a nanofluid. Also, a parametric study was performed to understand how a number of factors affect the thermal conductivity of nanofluids using the developed correlation.

Modelling time series properties of Australian lending interest rates

The purpose of this paper is to examine the time series properties of Australian residential mortgage interest rates, and in doing so, establish whether or not selected home loan rates （product-level monthly home loan interest rates for CBA） exhibit the expected cyclical and seasonal variations and whether seasonality, if present, is stochastic or deterministic. In particular, due to a well established presence of cyclicality in financial markets＇ interest rates and strong correlation between financial markets＇ interest rates and home loan interest rates, the paper presumes that cyclicality is also to be found in home loan interest rates. Furthermore, the paper tests the hypothesis that home loan interest rates, for selected products, exhibit the three identified （＂Spring＂, ＂Autumn＂ and ＂The end of the Financial Year＂） season-related interest rate reductions. The paper uses a structural time series modelling approach and product-level home loan interest rates data from one of the biggest banks in Australia, Commonwealth Bank of Australia （CBA）. As expected, the results overall confirm the existence of cyclicality in home loan interest rates. With respect to the seasonality of home loan interest rate, although most of the analysed variables show the presence of statistically significant seasonal factors, the majority of the statistically significant seasonal factors observed cannot be attributed to any of the three considered seasonal effects.

Modeling the Appraisal of Cloud Systems＇ Implementation

Intensity of competition, especially global competition, has driven many organizations to search for innovative ways to improve productivity and performance. This trend has led many firms to adopt approaches to implement cloud systems. Cloud systems have distinct characteristics that differentiate it from traditional internet services, due to a number of significant innovation factors. For example, firms need improved access to high-speed intemet as well as access to customer relationship management （CRM） and enterprise resource planning （ERP） capacities. This means that the interest of many firms in the implementation of cloud systems has increased. Although cloud systems are designed to facilitate knowledge transfer, currently, there is no method to ensure that knowledge transfer is useful or relevant to a firm. This in turn means that finns need to ensure that the cloud system has the capabilities to screen knowledge for compliance against some known knowledge characteristics. The use of cloud systems could result in an efficient delivery of innovation knowledge in an effective way. This paper presents an approach for assessment of the successful implementation of cloud systems. This paper also discusses the various success factors of cloud systems for global innovation.

Structural equation modeling analysis of factors influencing architects' trust in project design teams

This paper describes a structural equation modeling （SEM） analysis of factors influencing architects＇ trust in project design teams. We undertook a survey of architects, during which we distributed 193 questionnaires in 29 A-level architectural design institutes selected radomly from the altogether 59 ones in Shenzhen, P. R. China, and received 130 valid questionnaires. We used Amos 6.0 for SEM to identify significant personal construct based factors affecting interpersonal trust. The results show that only social interaction between architects significantly affects their interpersonal trust. The explained variance of trus~ is not very high in the model. Therefore, future research should add more factors into the current model. The practical implication is that team managers should promote the social interactions between team members such that the interpersonal trust level between team members can be improved.

Modeling Relative Humidity Effects on Power Electronic Performance

Variations in the behavior of power supplies caused electrical behavior dependence with environmental conditions. by environmental conditions require accurate characterization of the This paper introduces models to help predict relative humidity （Rtt） and other environmental factors influence on sensitive circuitry in power electronic systems. The resistivity and permittivity of an insulator have been modeled using different water contents i.e. RH, such model also included the mechanical properties of the design. An application example of a high power density, high voltage DC-DC converter is used to verify the results.

我国人口时间序列拟合模型的比较与选择

通过对我国1990年至2007年共18年的人口数据进行实证分析,运用时间序列的三个不同模型,对我国人口的变化规律进行了拟合研究;并给出了反映各个模型拟合精度的AIC值和SBC值;最后,通过对所建模型的比较分析,对拟合模型的选择提出了相关建议.

Research on influencing factors of urban building carbon emissions based on STIRPAT model——taking Suzhou as an example

The research on the influencing factors of carbon emissions from urban buildings is of great significance for the reduction of carbon in the urban building sector and even the realization of the city’s the carbon peak and neutrality goals.In this paper,combined with the ridge regression method,the STIRPAT model is used to establish a new model for influencing factors of building carbon emissions in Suzhou,and the factors such as urbanization rate,the number of permanent residents,per capita construction and tertiary industry added value,and per capita disposable income are analyzed.The analysis results show that the urbanization rate is the primary driving factor for building carbon emissions in Suzhou,followed by the number of permanent residents,then the added value of the per capita construction industry and tertiary industry,and finally the per capita disposable income.The conclusions of this paper indicate that industrialization and urbanization have strongly promoted the growth of building carbon emissions in Suzhou.In the future,with the continuous development of industrialization and urbanization and the increase of population,Suzhou City can rationally plan urban development boundaries to promote green and low-carbon transformation and development in the field of urban and rural construction,improve residents’low-carbon awareness,and advocate green and low-carbon behavior of residents to reduce building carbon emissions.

教学改革微观系统工程及其SIMPP分析方法

为了提高高等教育教学改革的系统性与可操作性，提升教学改革成效，特提出高等教育教学改革微观系统工程及其SIMPP分析方法。以北京中医药大学中药学院2010至2013级全体学生课堂学习状态问卷调查为例，系统论述了SIMPP分析方法的原理与操作步骤，结合学生受教师影响程度相关的行为模式及应对策略分析，说明了分析结果的解读方法与应用方向。同时，采用专题论文对大学生学业勤奋度、学习兴趣度、学习成效自我认知、自主学习能力、课堂出勤、学习目标系统培养、教学过程中学生受教师的影响程度、课程满意度和专业符合度9个方面进行了SIMPP分析，通过相关因素及其关系建模，明确不同因素之间的内在联系，发现学生的行为模式，并在此基础上设计相应的改革实践措施。研究表明，高等教育教学改革微观系统工程的理念和方法，将对未来的教学改革、课程改革、家庭-学校教育一体化改革等产生积极影响。