Experimental and Numerical Investigation of the Performance of Turbulent Heat Transfer in Tubes with Different Cross-Sectioned Wire Coils

The thermal-hydraulic performance of plain tubes with and without wire coils in turbulent regimes is investigated experimentally and numerically.The effects of wire coil distribution(circular cross section)within the tube were explored experimentally,and water was employed as the working fluid.The numerical simulation was carried out using software programmer ANSYS Fluent 2019 R3 using the finite-volume approach.In the turbulent regime,six cross-sectionedwire coilswere analyzed,including:circular,rectangular,hexagonal,square,star shape,and triangle.The utilization of a tube with a wire coil has been shown to increase heat transfer rate and pump consumption.The results indicate a high level of concurrence,as the deviations are all below 8%.Compared with plain tube,the wire coils,according to the arrangement(TWD),gave the best PEC.The heat transfer enhancement ability of different cross sections follows the following order:StCS>RCS>HCS>SqCS>CCS>TCS.Also,the sequence of pump consumption for each cross section is as follows:RCS>StCS>SqCS>HCS>CCS>TCS.

Evaluation of the Anti-Poaching Programme of the Cross River National Park Okwango Division, Nigeria 2002 to 2013

Poaching of wildlife has continued to be the major problem confronting national parks managers in Nigeria in spite of effort being made to curb the ugly trend. This paper examined the anti-poaching programme of the Cross River National Park Okwango Division Nigeria from 2002 to 2013, with a view to making recommendations for the improvement of the programme. Focused group discussions, personal interviews, review of official records and structured questionnaires were used to collect data. Analysis of variance using randomized complete block design and student’s t-test were used to analyse data. Result showed that 1 - 5 arrests of poachers per month per patrol station was significantly (P 0.05) in the number of poachers arrested and fined between 2002 to 2006 and 2007 to 2011. The low performance of the anti-poaching programme was attributed to poorly equipped rangers’ posts as well as well the absence of alternative livelihood options in the enclave and surrounding communities. It was recommended that more rangers should be employed, and the rangers should be adequately kitted, well equipped patrol stations be constructed and the enclave and surrounding communities be involved in the management of the National Park in addition to providing them with alternative livelihood options.

Cross-Language Information Extraction and Auto Evaluation for OOV Term Translations

OOV term translation plays an important role in natural language processing. Although many researchers in the past have endeavored to solve the OOV term translation problems, but none existing methods offer definition or context information of OOV terms. Furthermore, non-existing methods focus on cross-language definition retrieval for OOV terms. Never the less, it has always been so difficult to evaluate the correctness of an OOV term translation without domain specific knowledge and correct references. Our English definition ranking method differentiate the types of OOV terms, and applies different methods for translation extraction. Our English definition ranking method also extracts multilingual context information and monolingual definitions of OOV terms. In addition, we propose a novel cross-language definition retrieval system for OOV terms. Never the less, we propose an auto re-evaluation method to evaluate the correctness of OOV translations and definitions. Our methods achieve high performances against existing methods.

Promoting Balance in Output Efficiencies for Cross-Efficiency Evaluation in Data Envelopment Analysis

Cross-efficiency evaluation is recognized as an effective way of efficiency assessment for a set of decision making units (DMUs) in the framework of data envelopment analysis (DEA). It has been generally suggested that secondary goals be introduced for cross-efficiency evaluation owing to the non-uniqueness of optimal solutions in self-evaluation. This paper develops a variety of secondary goals in the spirit of promoting balance in the output efficiencies of the DMU under evaluation. The proposed models attempt to make each output contribute as equally as possible to the self-evaluated efficiency. In this way, the weight flexibility can for one thing be reduced by the introduced secondary goals with selections from alternate optimal solutions, in addition to counting on the dilution of flexibility in the subsequent peer-evaluation. The proposed approach might be applicable to evaluation problems in which multiple outputs are considered important and balance is encouraged to put all dimensions into sufficient use. The effectiveness of the proposed approach and its comparisons with some relevant secondary goals are illustrated empirically using numerical examples.

Safety evaluation for railway vehicles using an improved indirect measurement method of wheel–rail forces

The wheel-rail force measurement is of great importance to the condition monitoring and safety evaluation of railway vehicles. In this paper, an improved indirect method for wheel-rail force measurement is proposed to evaluate the running safety of railway vehicles. In this method, the equilibrium equations of a suspended wheelset are derived and the wheel-rail forces are then be obtained from measured suspension and inertia forces. This indirect method avoids structural modifications to the wheelset and is applicable to the long-term operation of railway vehicles. As the wheel-rail lateral forces at two sides of the wheelset are difficult to separate, a new derailment criterion by combined use of wheelset derailment coefficient and wheel unloading ratio is proposed. To illustrate its effectiveness, the indirect method is applied to safety evaluation of rail- way vehicles in different scenarios, such as the cross wind safety of a high-speed train and the safety of a metro vehicle with hunting motions. Then, the feasibility of using this method to identify wheel-rail forces for low-floor light rail vehicles with resilient wheels is discussed. The values identified by this method is compared with that by Simpack simulation for the same low-floor vehicle, which shows a good coincidence between them in the time domain of the wheelset lateral force and the wheel-rail vertical force. In addition, use of the method to determine the high-frequency wheel-rail interaction forces reveals that it is possible to identify the high-frequency wheel-rail forces through the accelerations on the axle box.

FAST COMPUTATION OF WIDEBAND RCS USING CHARACTERISTIC BASIS FUNCTION METHOD AND ASYMPTOTIC WAVEFORM EVALUATION TECHNIQUE

The Asymptotic Waveform Evaluation (AWE) technique is an extrapolation method that provides a reduced-order model of linear system and has already been successfully used to analyze wideband electromagnetic scattering problems. As the number of unknowns increases, the size of Method Of Moments (MOM) impedance matrix grows very rapidly, so it is a prohibitive task for the computation of wideband Radar Cross Section (RCS) from electrically large object or multi-objects using the traditional AWE technique that needs to solve directly matrix inversion. In this paper, an AWE technique based on the Characteristic Basis Function (CBF) method, which can reduce the matrix size to a manageable size for direct matrix inversion, is proposed to analyze electromagnetic scattering from multi-objects over a given frequency band. Numerical examples are presented to il-lustrate the computational accuracy and efficiency of the proposed method.

Petrophysical evaluation for reservoir properties of Lower Cretaceous sands in Sawan gas field, central Indus Basin, Pakistan

The Sawan gas field(SGF)is located in Pakistan's central Indus Basin in the Province of Sindh,Pakistan.Tectonically,it is part of the southeastern Jacobabad high;and geographically,it is part of the Thar Desert in the Khairpur district.In the present study,three wells,Sawan 01,Sawan 02 and Sawan 08,were analyzed for reservoir properties of the Lower Goru C sand interval,which has been drilled in the central part of the field.Petrophysical parameters such as effective porosity,the volume of shale,formation water resistivity,and water saturation of the studied basin were calculated.In terms of shale volume,Sawan 01 has 30%–35%of non-clean(shale)lithology,which is the highest of the three wells.The effective porosity of the three wells ranges from 12%–16%,while the average water saturation in the interval of C sand in these wells stands around 50%–60%.But there are zones with relatively lower water saturation values of approximately 30%–50%.These zones are considered better pay zones than the rest of the intervals.A very interesting phenomenon that may be termed the"Gas effect"is visible on cross plots,representing the neutron-density cross over on the E-Logs layout and representing the presence of lighter hydrocarbons in this reservoir zone.

基于无人机技术的露天矿山越界开采监测与评估方法

高效快速评估露天矿山越界开采对开展矿产卫片执法检查和推进严格保护矿产资源策略、推动区域高质量发展具有重要意义。基于无人机飞行技术、传感器技术、通信技术和影像处理技术,结合卫星遥感、地理信息系统应用,采集无人机航测数据与飞控系统数据,快速获取了疑似违法矿山二维场景图像(SIM),动态飞行展示矿区全貌和精细地物;进一步建立了矿山三维数字高程模型(DEM),定性研判违法类型与性质;针对需求建立了矿山的三维数字表面模型(DSM),定量估算违法采矿资源量;利用四维数字表面模型(DSM),查明矿山历史时期的违法过程,测算违法开采的资源量。无人机航测技术实现区域矿产资源开发秩序的快速监测和精细评估,为矿产资源的卫片执法检查工作提供理论支撑和决策依据。在江南某地进行试验的实例表明,基于无人机技术的露天矿山越界开采监测与评估方法技术具有时效性强、操作便捷、精细高效等优势,在支撑服务自然资源领域的卫片执法检查工作方面可以更加广泛地应用。

全科医学和初级保健横断面研究的基本设计和实施步骤

横断面研究是经典的研究设计方法之一,在临床各个专业中均有广泛的应用。在全科医学研究中大量科学问题的解答采用了横断面研究设计。这其中不仅包括了对人群健康特征,疾病特征或卫生服务现状的调查研究,还包括了面向社区人群的疾病筛查诊断方法构建等多种研究场景。在全科医学领域中,横断面研究可以做现况描述和比较分析,关联因素分析以及社区筛查诊断方法探索。开展横断面研究应包括研究设计和研究实施两个阶段,研究设计包括准确提炼研究目标,明确研究人群,研究因素及结局指标等临床要素以及确定样本获取方式,明确样本量的确定依据及合理的统计分析策略等方法学要素。研究实施,则需要通过完备的研究方案和病例报告表呈现研究设计思路,在伦理批准的前提下开展数据收集工作,同时注重数据管理工作质量并严格执行方案中的统计分析方法,求证医学问题。横断面研究的特点是相比于随访观察研究所需要的研究周期相对较短,不同基础的研究团队都能找到适合的研究方向,通过了解健康医疗现状,从探讨关联因素创建筛查方法等角度,服务社区医疗。

大数据背景下跨境电商信用管理体系建设研究

大数据背景下建设跨境电商信用管理体系是促进跨境电商高质量发展的关键。随着跨境电商的快速发展,信用风险层出不穷,为打造公平的跨境交易环境,提高跨境支付安全,完善跨境电商平台和企业信用评价体系,跨境电商行业亟须建立标准规范的信用管理体系。通过梳理分析跨境电商信用体系建设研究现状,归纳总结出跨境电商信用管理体系正面临信用法律制度不完善、信用评价方法不科学、信用管理模式单一、信用数据质量差等挑战。最后从大数据技术角度,提出了跨境电商信用管理体系建设应积极推动跨境电商信用立法与国际标准制定、提高企业及消费者的信用意识、建立健全信用大数据共享机制与标准化大数据跨境电商信用综合服务平台、利用大数据技术优化信用评价体系等建议。

基于DBN的风电机组变桨系统可靠性动态评估

为了对风电机组变桨系统的潜在风险进行可靠的动态预测,针对变桨系统部件种类多、系统复杂、故障特征提取困难的问题,文章首先对变桨系统故障点和故障传递过程进行归纳分析,建立故障树;然后将其转化为融合Leaky Noisy-Or节点的动态贝叶斯网络(DBN),保证了模型精度并具备了动态预测能力;最后采用5折交叉验证的方式对模型进行寻优并验证。测试结果表明,该方法在对变桨系统进行风险预测、故障致因分析、风险动态演化过程分析方面准确率较高,可指导变桨系统进行预防性维护,在保证风电机组整体安全方面具有工程应用价值。

金融数据跨境流动的法律风险量化分析与规制建议

本文从国内外金融数据跨境流动相关立法和实践中提取风险因素,构建了金融数据跨境流动法律风险评估模型,并基于AHP层次分析法和FCE模糊综合评价法,采用国内首批通过数据出境安全评估的金融机构作为案例对该模型进行了实证检验。研究结果表明,数据出境前的合法性审核、数据业务需求评估和接收方合法性,是影响金融数据跨境流动法律风险的关键指标。根据评估结果,本文从监管角度提出了相关规制建议:制定更具针对性的风险评估指引,优化数据安全评估流程,并对金融数据出境范畴进行细化规定;平衡风险控制和数据流动效率,在确保风险可控的基础上,推动金融数据的合理跨境流动,促进金融市场的国际化发展。

跨境电商独立站评价指标体系标准研究

跨境电商独立站已成为跨境电商的重要渠道,带动跨境电商品牌出海促进跨境电商产业高质量发展。通过跨境电商独立站评价能够全面衡量跨境电商独立站发展水平,推动跨境电商独立站高质量发展。然而,跨境电商独立站评价缺乏统一的规范,急需标准进行支撑。本文对跨境电商独立站评价指标体系标准开展研究,通过梳理跨境电商独立站标准化现状,提出跨境电商独立站评价指标体系标准的核心技术内容,为跨境电商独立站建设及发展评价提供参考。

基于改进分层博弈交叉效率模型的政策评价

政策评估作为政策实施过程中的关键环节,是检验政策效果的基本途径与实现资源优化配置的重要依据.在复杂博弈情境下,决策单元群体间竞合关系不变的假设已经不能满足现实中效率评价的需求,考虑群体间动态变化的合作与竞争关系至关重要.本文将外界冲击下主体间竞合关系演变纳入效率评价框架,提出改进分层博弈交叉数据包络分析方法:从公平的视角出发,基于二次目标模型构建多层次效率矩阵,结合Shapley值对决策单元动态关系演变进行效率评价,进而,以水权交易市场试点政策为例,验证该模型的可行性.该方法放松了政策前后群体竞合关系稳定的假设,验证了水权交易市场政策的有效性和外溢性,为能源与环境领域试点政策效果评价提供了新方法.

基于D-I-M协同模型的企业数字化转型财务管理风险识别研究

数字化正在重塑经济发展的轨道,成为赋能经济增长新动力。精准识别财务管理风险中的关键指标及其相互关系,对企业更好地完成数字化转型尤为关键。融合企业人力、运营、财务、环境4个基本维度,从链式传导视角构建转型背景下企业财务管理风险指标体系。通过决策试验与评价实验室(DEMATL)法,分析各影响因素之间中心度和原因度关系,并利用解释结构模型(ISM),将矩阵进一步分析得到影响因素的层级划分,归纳影响因素之间的内在指向关系,最后运用交叉影响矩阵相乘(MICMAC)法计算各因素的驱动—依赖关系以判断其属性类别。提出通过D-I-M协同分析的方法,识别财务管理风险路径,为企业进行多链融合数字化转型、规避财务管理风险提供参考。

基于DEMATEL方法的科学基金项目绩效关键影响因素识别及实证研究——以促进海峡两岸科技合作联合基金项目为例

基础研究是应用研究和重大创新之源,联合基金作为国家基金委联合地方政府支持基础研究的主渠道之一,对提升地区原始创新能力、促进人才队伍建设发挥重要作用。为了真实反映促进海峡两岸科技合作联合基金资助项目的学术水平,从创新成果、人才培养、合作交流、项目延伸和间接影响等5个维度构建结题项目绩效评价指标体系,运用DEMATEL法分析15个二级指标之间的关联影响,结合多层次模糊综合评价法构建模型,并以某大学承担的重点支持项目为案例对影响项目绩效的关键因素进行实证分析,确定这个项目绩效评价等级。实证结果表明:DEMATEL法可以识别影响项目绩效的关键指标;模糊综合评价模型既考虑了评价对象的模糊性,也兼顾了指标体系的层次性,综合评价结果更具科学性。

课程思政融入跨境电商课程体系评价方法研究

德育作为我国教育综合改革重要项目,将思想政治教育贯穿人才培育体系,是提高高校人才培养质量的重要措施。基于课程思政融入国际经济与贸易专业跨境电商课程的目标和任务,以广东省某职业学院为研究对象,分析国际经济与贸易专业跨境电商课程思政质量评价现状,并通过实地调查结果,构建国际经济与贸易专业跨境电商课程思政评价指标体系和方法,旨在为国际经济与贸易专业的高素质跨境电商人才培养提供借鉴和理论依据。

中国城市群突破性创新能力分析——基于环长株潭城市群的实证

为助推以长沙为核心的环长株潭城市群全球研发中心城市建设,选取环长株潭城市群2010—2021年的发展数据,从突破性创新支持、创新管理、创新投入、创新产出和创新环境等5个维度构建城市群突破性创新能力SMIOE评价模型,采用信息贡献率分析法,遴选确定17个核心评价指标,使用“交叉熵权-TOPSIS”法测算环长株潭城市群的突破性创新能力指数。研究结果发现,SMIOE评价模型能客观反映城市群突破性创新能力的真实水平,环长株潭城市群突破性创新能力总体不均匀、发展水平较低,除长沙、株洲、衡阳外,2010—2021年间,其他5个城市指数分别呈“M”型和倒“V”型下降;突破性创新能力较高的城市主要集中于湖南东北部。最后基于研究结论,从树立全域创新、协同创新和重点创新等3个方面理念,提出环长株潭城市群突破性创新能力的发展建议,为促进环长株潭城市群创新群落早日提供参考。

卓越教师经历的学习过程特征及启示——10位个案教师学习经历的跨案例研究

卓越教师培养一直在教育政策和区域教师教育工作中倍受重视,但缺乏微观层面对这一群体教师所经历的学习过程特征的探讨。基于对10位卓越教师所经历的学习过程的个案研究成果,应用跨案例研究法,采用“环境—过程—结果”(EPO)框架得到了卓越教师经历的学习过程中所呈现的特征:卓越教师在学习环境中体验到高挑战性的任务和积极的组织氛围,在学习过程中表现出高水平的内部学习动机和情感意志,学习互动以个体主动投入式为主,经历的学习内容具有多元性和差异性,学习结果更多指向来自内部的专业成就感或价值感。对卓越教师学习设计者和教师继续教育决策者提出如下建议:卓越教师的学习环境需要突出工作场域和高挑战任务特征,教师的学习过程中需要加强学习互动的设计,教师的学习结果预期亟须超越以往狭隘的知识或能力观。

油气人工智能课程实践案例融合与效果评价

人工智能时代下,各行业的交叉学科建设也在不断探索中。针对“油气人工智能”交叉学科的教学建设这一问题,文章研究探索了基于案例式的油气人工智能教学模式。文章从油气人工智能教学的选题模式、学习模式、课程实践模式等方面进行分析,通过具体的教学实施,开展了案例库建立、案例融合教学实践以及教学反馈评价等教学活动,可以为油气人工智能课程的建设提供启发。