Evaluation of working fluids for organic Rankine cycles using group-contribution methods and second-law-based models

The group-contribution (GC) methods suffer from a limitation concerning to the prediction of process-related indexes, e.g., thermal efficiency. Recently developed analytical models for thermal efficiency of organic Rankine cycles (ORCs) provide a possibility of overcoming the limitation of the GC methods because these models formulate thermal efficiency as functions of key thermal properties. Using these analytical relations together with GC methods, more than 60 organic fluids are screened for medium-low temperature ORCs. The results indicate that the GC methods can estimate thermal properties with acceptable accuracy (mean relative errors are 4.45%-11.50%);the precision, however, is low because the relative errors can vary from less than 0.1% to 45.0%. By contrast, the GC-based estimation of thermal efficiency has better accuracy and precision. The relative errors in thermal efficiency have an arithmetic mean of about 2.9% and fall within the range of 0-24.0%. These findings suggest that the analytical equations provide not only a direct way of estimating thermal efficiency but an accurate and precise approach to evaluating working fluids and guiding computer-aided molecular design of new fluids for ORCs using GC methods.

Random failure mechanism method for assessment of working platform bearing capacity with a linear trend in undrained shear strength

A bearing capacity evaluation for the surface strip foundation on a working platform modelled on a twolayered substrate is considered in the study.The upper layer is assumed as man-made and wellcontrolled and thus non-variable.The lower layer modelling natural cohesive soil is subjected to spatial variability of undrained shear strength.The random failure mechanism method(RFMM)is used to evaluate the bearing capacity.This approach employs a kinematic assessment of the critical load and incorporates the averaging of three-dimensional(3 D)random field along dissipation surfaces that result from the failure mechanism geometry.A novel version of the approach considering an additional linear trend of undrained shear strength in the spatially variable layer is proposed.The high efficiency of the RFMM algorithm is preserved.The influences of foundation length,trend slope in the spatially variable layer,fluctuation scales,and thickness of the homogenous sand layer on the resulting bearing capacity evaluations are analysed.Moreover,for selected cases,verification of the RFMM based assessment obtained using random finite difference method(RFDM)based on 3 D analysis is provided.Two types of analyses are performed using RFDM based on associated and non-associated flow rules.For associated flow rule which corresponds to RFMM,the RFMM is conservative and efficient and thus it seems preferable.However,if RFDM employs non-associated flow rule(much lower dilation angle for sand layer),the efficient RFMM is no longer conservative.For this situation,a combined approach that improves the efficiency of the numerical method is suggested.

Optimal arrangement for pressure measurement points in working chamber of earth pressure balance shield

In order to exactly provide scientific basis for pressure dynamic balance control of working chamber of earth pressure balance shield (EPBS),study on optimal arrangement of pressure measurement points in working chamber was conducted. Based on mathematical description of optimal arrangement for pressure measurement points,fuzzy clustering analysis and discriminant analysis were used to divide pressure regions of nodes on bulkhead. Finally,the selection method of optimal measurement points was proposed,and by selecting d6.28 m EPBS as study object,the case study was conducted. By contrast,based on optimal arrangement scheme of pressure measurement points,through adopting weighted algorithm,the absolute error mean of equivalent pressure of working chamber is the smallest. In addition,pressure curve of optimal arrangement points presents parabola,and it can show the state of pressure distribution on bulkhead truly. It is concluded that the optimal arrangement method of pressure measurement points in working chamber is effective and feasible,and the method can provide basis for realizing high precision pressure control of EPBS.

Consistency and Validity of the Mathematical Models and the Solution Methods for BVPs and IVPs Based on Energy Methods and Principle of Virtual Work for Homogeneous Isotropic and Non-Homogeneous Non-Isotropic Solid Continua

Energy methods and the principle of virtual work are commonly used for obtaining solutions of boundary value problems (BVPs) and initial value problems (IVPs) associated with homogeneous, isotropic and non-homogeneous, non-isotropic matter without using (or in the absence of) the mathematical models of the BVPs and the IVPs. These methods are also used for deriving mathematical models for BVPs and IVPs associated with isotropic, homogeneous as well as non-homogeneous, non-isotropic continuous matter. In energy methods when applied to IVPs, one constructs energy functional (I) consisting of kinetic energy, strain energy and the potential energy of loads. The first variation of this energy functional (δI) set to zero is a necessary condition for an extremum of I. In this approach one could use δI = 0 directly in constructing computational processes such as the finite element method or could derive Euler’s equations (differential or partial differential equations) from δI = 0, which is also satisfied by a solution obtained from δI = 0. The Euler’s equations obtained from δI = 0 indeed are the mathematical model associated with the energy functional I. In case of BVPs we follow the same approach except in this case, the energy functional I consists of strain energy and the potential energy of loads. In using the principle of virtual work for BVPs and the IVPs, we can also accomplish the same as described above using energy methods. In this paper we investigate consistency and validity of the mathematical models for isotropic, homogeneous and non-isotropic, non-homogeneous continuous matter for BVPs that are derived using energy functional consisting of strain energy and the potential energy of loads. Similar investigation is also presented for IVPs using energy functional consisting of kinetic energy, strain energy and the potential energy of loads. The computational approaches for BVPs and the IVPs designed using energy functional and principle of virtual work, their consistency and validity are also investigated. Classical continuum mechanics (CCM) principles i.e. conservation and balance laws of CCM with consistent constitutive theories and the elements of calculus of variations are employed in the investigations presented in this paper.

THE VIRTUAL WORK PRINCIPLE AND LINEAR COMPLEMEN-TARY METHOD FOR COUPLING ANALYSIS OF ELASTO-PLASTIC DAMAGE STRUCTURE

The virtual displacement principle of elasto-plastic damage mechanics is presented. A linear complementary method for elasto-plastic damage problem is proposed by using FEM technique. This method is applicable to solving the damage structure analysis of hardened and softened nonlinear material.

Analysis of Software Development and Enhancement Projects Work Effort per Unit Based on the COSMIC Method with Regard to Technological Factors—Case Study

This paper aims to present a case study that consists in the analysis of work effort per unit of software systems Development and Enhancement Projects (D&EP) depending on technological factors. That analysis was commissioned by one of the largest public institutions in Poland. This is the COSMIC (Common Software Measurement International Consortium) function points method that is chosen by this institution as a point of reference for size of software systems developed/enhanced for supporting its functions and therefore this method is the base for the analysis of D&EP work effort per unit with regard to technological factors.

Object-Oriented Finite Element Analysis of Metal Working Processes

Recently an object-oriented approach has been applied in the fields of finite element analysis with a view to treating the various complexities within these. It has been demonstrated that finite element software designed using an object-oriented approach can be significantly more robust than traditional codes. This paper describes a special kind of implementation of object-oriented programming which is rather hybrid in nature, in the development of a finite element code for engineering analysis of metal working problems using C++, and discusses the advantages of this approach.

Research on the theories and methods of the specialization of the college counselor＇s work

The research proposition of this article is to do a brief analysis of the specialized theories and the systems of the methods of the college counselors＇ work under the perspective of the professional theories of the college counselors, and discuss the way of the realization of the specialization of the college counseling work, to achieve the professional orientation of the work of the college counselors. With the use of the specialized ways of work, we can make the college counselors develop themselves in the strict professional training and the continuous autonomous learning. They should use their own professional knowledge to equip themselves, to be the teachers and management personnel able to correctly guide the healthy growth of the university students.

中日友好医院党建引领高质量发展实践与思考

公立医院党建工作是实现高质量发展的重要保障。本文以中日友好医院为例,介绍把党的政治建设、思想建设、组织建设、作风建设、纪律建设、制度建设与医院高质量发展紧密结合的实践探索,逐步形成以高质量党建引领高质量发展的“六提升”工作法,为公立医院党建引领高质量发展提供参考。

石灰石露天矿高陡边坡稳定性计算分析

以西南某石灰石矿高陡边坡为研究对象,根据矿山边坡现状、边坡岩体结构和结构面发育特征因素对“现状边坡”和“终了边坡”进行地质分区,通过岩石室内物理力学试验获得坡体岩石物理力学参数,采用GSI法计算边坡岩体内摩擦角、粘聚力、变形模量和泊松比等参数,评估边坡地质强度特性,采用Morgenstern-Price极限平衡法分三种荷载工况分别计算“现状边坡”和“终了边坡”各分区稳定性系数。经分析,该石灰石矿各地质分区“现状边坡”和“终了边坡”稳定性好,采场边坡参数设计合理,可为矿山扩产安全设施设计和安全生产提供参考。

新质生产力的分配向度:按劳分配与共同富裕之契合性论析

马克思按劳分配思想是内含对生产、分配、交换和消费环节规定的系统性思想,按劳分配是推动实现共同富裕的分配方式,但这一系统思想在现实中表现为生产端、分配端、交换端和消费端的“系统悖论”。按劳分配与共同富裕的理论兼容性与实践契合性应从描述性、规范性和系统性三重视野观照:现行两套分配体系边界的逐渐消融要求重新审视通往共富之路;按劳分配内蕴的革命性精神是当下推动共同富裕的根本精神;新质生产力发展下生产物化趋势与消费人化本性间的张力造成的“劳动”分配标准的弱化呼唤“新质”的分配标准。新质生产力的“颠覆性”影响要求对未来社会分配方式进行初步构建:在新质生产力的解放初期实行按“劳”分配+按“要素”分配;新质生产力深入发展阶段实行按“所有权”分配;在新质生产力的高度发达阶段实行按“需”分配。

基于德尔菲法的大众媒体控烟作品评价指标体系构建

目的构建科学的大众媒体控烟作品评价指标体系,为控烟传播实践提供有效指导。方法采用文献资料法构建大众媒体控烟作品评价指标体系初稿,经2轮德尔菲专家咨询后确定最终的指标体系,根据权重调查分析确定各级指标权重。结果共邀请到29名专家参与德尔菲专家咨询,2轮德尔菲咨询专家积极系数均为100%,专家权威系数Cr均>70%,各指标重要性均数均>3,变异系数Cv的取值区间为0.09~0.39。最终确定的大众媒体控烟作品评价指标体系包括5项一级指标、18项二级指标。其中,一级指标的权重系数分别为0.18、0.20、0.22、0.10、0.30,二级指标的权重系数区间为0.10~0.70。结论本研究构建的大众媒体控烟作品评价指标体系可为媒体控烟作品评价提供科学的评估工具,有助于推动媒体更好地开展控烟传播活动。

瞬变电磁法在煤矿灾害勘察评价的应用案例分析

为进一步明确某现状矿区内易发生地下水危害的区域,采用瞬变电磁法对煤矿地下环境进行勘察,勘察结果表明矿区内可能存在一含水构造带,该构造带纵向基本贯穿标高550~-200 m,可能会对采空区或者巷道的开发使用带来危害。此外在瞬变电磁法对矿区进行勘察时,采空区往往表现为低阻包围着的中高阻特征,而含水裂隙往往表现为低阻特征。本文研究内容对于指导后续矿产资源的开发具有一定指导意义。

滑坡在役防治工程缺陷分类和健康评价方法

为快速评估常见在役滑坡防治工程的运行状态并采取科学有效的维护手段,笔者在三峡库区、汶川震区和川东地区实地调查了160余处抗滑挡墙、抗滑桩和格构锚固工程,获取了上述三类滑坡防治工程表征损伤的第一手资料,总结分析了其变形破坏模式及特征,定义了滑坡防治工程缺陷的概念,定性地提出了缺陷程度分级标准。在统计分析滑坡防治工程损伤特征基础上,选取了墙身滑移距离、墙身沉陷位移、墙身倾斜程度、墙身裂缝密度、桩体倾斜程度、桩体剪切程度、桩体裂缝密度、格梁最大裂缝宽度、单根格构梁裂缝率和受损格构变形区比例等10个控制指标作为其缺陷分类指标,结合多元线性回归法,对单体工程结构进行综合量化评分评定,进而建立了半定量的滑坡防治工程健康评价方法。

临床视角下医务社会工作专业化发展路径探析

目的:从多学科医学人文团队中临床医务人员的视角梳理医务社会工作的服务内容、临床服务流程和专业化发展路径,为医务社会工作标准化研究提供依据。方法:以江苏省人民医院为个案,运用质性研究法对16名参与多学科医学人文团队的临床医务人员进行结构式访谈。结果:运用Colaizzi七步分析法对访谈资料归纳整理,就医务社会工作的专业化发展提炼出5个主题,即需求、内容、优势、问题和期待。结论:医务社工作为临床工作中的专业角色已得到多学科医学人文团队中医护人员的认可,但在专业技能强化、服务流程优化、社会资源链接、科研水平提升等方面还需要进一步加强;可参照医务社会工作的通用过程模式,从“点-线-面”3个阶段逐步向规范化、科学化、专科化发展。

建构共识:在精英结构分化的村庄落实“一肩挑”——基于“S村”的经验研究

村级组织负责人“一肩挑”制度对解决村庄“两委”矛盾,强化党组织在农村基层治理中的领导核心地位有重要意义。但是,在“两委”力量相互制衡、精英结构相对分化的村庄,“一肩挑”制度的推行并不顺利。2021年,A镇在所辖16个行政村推行“一肩挑”制度,其中15个村都顺利实现了村内组织“一肩挑”,唯独“S村”遭遇瓶颈。其主要原因是该村已形成比较稳定的村“两委”相互制衡的精英结构,仅靠村庄自治力量难以实现权力整合。在这种情况下,乡镇党委通过灵活运用党的工作方法分别在村庄精英内部以及村民内部建构共识,为强调权力整合的“一肩挑”制度创造条件。一方面,通过党内干部工作方法在原村干部内部打破隔阂,在村庄精英中凝聚候选人共识;另一方面,利用群众工作方法凝聚村庄民意,在村民中构建选举共识。在村庄自治力量存在分化的情况下,党的领导对整合村庄精英、建构村内共识起到了关键作用。

OSCE实训联合PBL教学法在提升规培护士临床工作能力中的应用

目的:探讨OSCE实训联合PBL教学法在提升规培护士临床工作能力中的应用效果。方法:选取2016年至2018年新入职的70名护士作为研究对象,随机分为对照组和试验组,每组35人。对照组采用常规教学法,试验组在对照组基础上采用OSCE实训联合PBL教学法。分别于培训前后对两组护士进行临床工作能力考核,且培训结束后对两组护士进行患者满意度调查。分析两组护士的考核成绩及患者满意度调查结果。结果:试验组的临床工作能力明显高于对照组(P<0.01);试验组护士的患者满意度明显高于对照组(P<0.01)。结论:OSCE联合PBL教学法能显著提高规培护士的临床工作能力及患者满意度。

习近平民族工作的原则与方法研究

民族工作的原则和方法是习近平总书记关于加强和改进民族工作的重要思想的重要组成部分。本文从必须加强党对民族工作的领导、必须全面把握我国统一的多民族国家的国情、切实帮助少数民族和民族地区加快发展等三个方面阐释习近平民族工作的重要原则;从民族工作重在交心、要见物更要见人、对少数民族流动人口不能采取“关门主义”态度等方面阐释其民族工作的重要方法。提出学习、领会习近平民族工作原则和方法,有利于坚定中国特色解决民族问题的道路自信、有利于推动民族工作高质量发展、有利于贯彻落实新时代民族工作主线。

基于六自由度机械臂的带电作业机械手模型设计研究

为满足高危环境下带电机器人的作业需求,避免机械臂在运动过程中出现抖动、失控等不良现象,提出基于六自由度机械臂的带电作业机械手模型。首先基于机械臂关节参数构建动力学模型,然后引入混合多项式插值法和粒子群算法对机械臂轨迹规划问题进行分析。实验结果表明,在粒子群优化算法下,机械臂4个关节的运行总时间分别为3.48、3.57、4.58和3.84 s,总运行时间最少缩短了10 s。在约束条件下,机械臂各关节始终处于安全范围内,不存在关节力矩大幅振荡情况。实验结果证实该带电作业机械手模型具有较好的应用效果。

防屈曲耗能支撑与框架节点的连接设计

防屈曲耗能支撑作为一种新型的消能减震元件,已被广泛、成功地应用于既有框架结构的抗震加固中。为使结构在地震作用下表现出良好的抗震效果,需保证防屈曲钢支撑与框架具备优良的协同工作性能,因此支撑与框架之间的连接性能尤为重要。防屈曲钢支撑与框架节点之间的连接方法有焊缝连接、螺栓连接以及销轴连接。通过对节点板-框架连接处和节点板-支撑连接处进行受力分析,破坏形态分析,完善了加支撑框架节点处的计算公式。