柴油机输出功率测量结果的不确定度评定

依据往复式内燃机测量方法,按照测量不确定度评定方式,对影响柴油机输出功率的主要因素逐一进行评定,计算不确定度分量,最终合成,求得在标定工况下柴油机输出功率的扩展不确定度。     

水资源系统分析中模糊隶属度与集对联系数的不确定性特征辨析

为探究模糊隶属度与集对联系数两种理论间的内在联系,分析了二者在概念、理论和适用性的异同,利用集对理论构造联系数模型与模糊数学思想构造隶属度函数,分别评价了黑龙江省水资源承载力现状。结果表明,集对理论与模糊数学理论在水资源系统分析中均有良好的效果。由于模糊性是排中率的破缺,模糊数学在不确定性的现状评价中更有优势;集对联系数可视为模糊隶属度的区间表达,可对评价对象进行简单分级,并能动态评价研究对象。     

活塞热负荷三维子结构有限元分析及试验研究

摘要本文采用十五节点等参元和子结构有限元方法在AST-386微型计算机上分析了活塞三维温度场,并利用热电偶测温技术和四连杆引线机构测量了活塞实际温度.     

柴油机气缸盖热负荷模拟计算与结构改进

以YZ4105QF柴油机热负荷为研究对象,利用热电偶测试技术,测量了标定工况下YZ4105柴油机气缸盖温度。在此基础上,利用Pro／E三维造型软件建立了气缸盖的三维实体模型,确定了相应的换热边界条件;利用大型有限元分析软件ANSYS计算分析了气缸盖的温度场和热变形,并对气缸盖的结构提出了改进措施。     

油冷柴油机燃油耗与热负荷研究

摘要本文利用油冷隔热技术,在一台小型高速柴油机上进行了节能与热负荷的试验研究.同时,对油冷柴油机的燃烧室壁面进行了稳态和瞬态温度测试.说明油冷技术起到隔热效果,使燃烧室壁面温度升高而热冲击负荷减小,传热损失降低,燃烧过程得到改善.尤其在中小负荷时,柴油机经济性可有明显提高.     

Uncertainties of the 50‐year wind from short time series using generalized extreme value distribution and generalized Pareto distribution

This study examines the various sources to the uncertainties in the application of two widely used extreme value distribution functions, the generalized extreme value distribution (GEVD) and the generalized Pareto distribution (GPD). The study is done through the analysis of measurements from several Danish sites, where the extreme winds are caused by the Atlantic lows. The simple extreme wind mechanism here helps us to focus on the issues mostly related to the use of limited wind measurements. Warnings are flagged and possible solutions are discussed. Thus, this paper can be used as a guideline for applying GEVD and GPD to wind time series of limited length. The data analysis shows that, with reasonable choice of relevant parameters, GEVD and GPD give consistent estimates of the return winds. For GEVD, the base period should be chosen in accordance with the occurrence of the extreme wind events of the same mechanism. For GPD, the choices of the threshold, the definition of independent samples and the shape factor are interrelated. It is demonstrated that the lack of climatological representativity is a major source of uncertainty to the use of both GEVD and GPD; the information of climatological variability is suggested to be extracted from global or mesoscale models. © 2013 The Authors. Wind Energy published by John Wiley & Sons, Ltd.     

Influence of using pulsed cooling for mold temperature control on microgroove duplication accuracy and warpage of the Blu-ray Disc

The usage of pulsed cooling for mold temperature to improve the molding process has been gaining increasing attention. In this study, Blu-ray Disc substrates, adapted for the commercial format media, were injection molded by combining pulsed-cooling technology. When applying pulsed cooling, coolant circulation is usually stopped during the melt-filling process and the mold opening and closing period. This leads to the additional cavity surface temperature increase and may vary part qualities. The correlations of mold temperature, cycle time, and pulse cooling duration with microgroove duplication accuracy and substrate qualities such as warpage in different directions were investigated in details. Measured results were also compared with those of injection-compression molded Blu-ray Disc using conventional cooling. The experiments showed that by using pulsed cooling in a proper manner one may manufacture Blu-ray Discs with lower warpage, higher accuracy in microgroove replication meanwhile reducing coolant temperature by 8 °C and shortening the cycle time by10% as compared to the conventional-cooling process. The usefulness of pulsed cooling and its potential in improving part quality and reducing cycle time during injection molding have been successfully demonstrated.     

家用燃气灶热效率测量及不确定度评定

按照GB16410-2007家用燃气灶热效率的测量原理和方法,对测量结果进行了不确定度评定,分析了各输入量对评定结果的影响情况。作为对比,分析了标准状态改变和按旧国标测量时的热效率不确定度。结果表明:铝锅修正系数、上下限锅正投影面积、试验气标态低热值和水的温升对家用灶热效率测量结果影响较大,影响程度依次降低。折算系数、测量时间和实验水量的测量不确定度可忽略不计。标准状态的改变对热效率测量结果不确定度评定的影响很小。相比旧国标,新国标测量结果具有更大的不确定度。     

Uncertainties in the design and operation of distributed energy resources: The case of micro-CHP systems

Large-scale diffusion of distributed energy resources (DERs) will have a profound impact on electricity infrastructure functioning: it will bring radical changes to the traditional model of generation and supply as well as to the business model of the energy industry. DERs comprise distributed power generators, distributed energy storages and controllable loads. There are, however, many uncertainties that influence the design and operation of DERs. This paper clarifies these uncertainties by proposing and applying a comprehensive framework for uncertainty analysis. We thereby adopt an integrated approach that considers not only the technical, but also the economic and institutional uncertainties. A delineation of the work is a focus on residential DERs and on micro-CHP systems specifically. After the proposed framework for uncertainty analysis is explained the uncertainties pertaining to the design and operation of residential DERs and micro-CHP systems are identified. In a case study system a selection of the uncertainties are quantitatively analysed. The case study system consists of a household that intelligently applies a micro-CHP unit in conjunction with energy storages and that interacts with its energy supplier. With a sensitivity analysis of the system model the salient impacts of the uncertainties on system behaviour and performance are enunciated.     

Experimental characterization of the accuracy of multidetector boron meter for operational safety of reactors

The accuracy of a boron meter, which is used to measure the concentration of boric acid, is 1 of the factors affecting operational safety in nuclear reactors. The concept of using a multisensitivity detector to improve the accuracy of the boron meter is proposed, and the accuracy improvement is confirmed by Monte Carlo N‐Particle simulation. A Monte Carlo simulation using a multidetector showed a 30 times lower accuracy error (~2 ppm) than a single‐detector boron meter system (~100 ppm). In this study, a new concept of boron meter with improved accuracy is experimentally verified. Experimental verification confirmed that the accuracy was 50% higher than that of the single detector system. To improve the accuracy of the system, the detection efficiency of BF₃ detector was measured in boron concentration, source strength, and neutron irradiation time.     

Uncertainties and sustainability concepts in biofuel supply chain management: A review

Biofuel energy as an alternative and additive form of energy to fossil fuel has gained much attention in recent times. In order to sustain such a vision, a robust supply chain is of extreme importance in helping to deliver competitive biofuel to the end user markets. In this paper, firstly, an introduction of the evolution of biofuels and the general structure of the biofuel supply chain are presented. Secondly, the three types of decision making levels and uncertainties that are inherent within the biofuel supply chain are discussed. Thirdly, important methodologies for modeling uncertainties in the decision making process are provided. Fourthly, sustainability concepts and models that give perspectives to the social, economical and environmental concepts are reviewed. Finally, conclusions and future research based on incorporating uncertainties and sustainability concepts within the biofuel supply chain are drawn and suggested, respectively.     

Measuring transient temperature of the medium in power engineering machines and installations

Under steady-state conditions when fluid temperature is constant, there is no damping and time lag and temperature measurement can be made with high accuracy. But when fluid temperature is varying rapidly as during start-up, quite appreciable differences occur between the true temperature and the measured temperature because of the time required for the transfer of heat to the thermocouple placed inside a heavy thermometer pocket. In this paper, two different techniques for determining transient fluid temperature based on the first and second order thermometer model are presented. The fluid temperature was determined using measured thermometer temperature, which is suddenly immersed into boiling water. To demonstrate the applicability of the presented method to actual data, the air temperature which changes in time, was calculated based on the temperature readings from the sheathed thermocouple.     

Effect of wavy plate geometry configurations on the temperature and flow distributions

As fluid flowing through the wavy plate, breaking and destabilizing in the thermal boundary layer are induced. In the present study, the numerical investigation on the heat transfer and flow distributions in the channel with various geometry configuration wavy plates under constant heat flux conditions is considered. A finite volume method with the structured uniform grid system is used to solve the turbulent model. Effects of geometry configuration of wavy plates, wavy plate arrangements, and air flow rates on the temperature and flow developments are considered. The sharp edge of wavy plate has a significant effect on the flow structure and heat transfer enhancement. The results of this study are expected to lead to guidelines that will allow the selected wavy plate geometry configuration for designing heat exchanger which increase thermal performance.     

燃烧过程光辐射度测温研究——理论、数值仿真和试验

从普朗克黑体辐射定理出发,根据可光和高温（1000K以上）条件,简化单色辐射率表达式。在此基础上,在探测系统可接收的光光谱带内,求得其所有光谱成分综合的、以温度表示的光辐射度解析表达式,并分析其应用条件,利用该表达式,进行计算机数值仿真,得到温度与光辐射度关系的理论曲线;同时,利用光辐射度探测系统和热电偶测温仪进行试验,得到温度与光辐射度关系的试验曲线。比较理论曲线和试验曲线,发现它们之间虽有误差,但变化趋势吻合,最后,对光辐射度测温方法的局限性和不足之处进行了分析,提出了改进措施。     

延长热水锅炉大修周期及使用寿命的探讨

影响锅炉大修周期的问题很多,其中,腐蚀是一项比较复杂的内容,也是最为关键的问题,如何从预防与防止的角度出发探讨防腐和延长使用寿命是本文所要重点介绍的。     

太阳热水器的测量不确定度评定

按中华人民共和国国家计量技术规范《测量不确定度评定与表示JJF1059—1999》，太阳热水器测量必须以测量不确定度评定与表示，而现行实施的太阳热水器测量国家标准未给出具体的太阳热水器测量不确定度评定与表示方法。以太阳热水系统评定作为实例给出了太阳热水器测量不确定度评定及太阳热水器测量不确定度评定自动化。     

基于少量声学数据的炉内温度场重建

针对炉内温度场声学测量中只有少量声学数据问题,提出了基于平面像素分割和正则化的温度场重建方法.利用二维温度场像素之间的邻近关系,给出了正则化矩阵的一般求取方法,并对正则化参数进行了研究.分别对单峰对称和非对称、双峰对称和非对称的温度场模型进行了仿真实验,得出了三维显示图和等温线图,并给出了温度场的绝对误差和均方根误差.仿真结果表明:该模型的准确度较高,时各种温度场计算有一定的通用性.     

Temperature-dependent dissolution and diffusion of H isotopes in iron for nuclear energy applications: First-principles and vibration spectrum predictions

The dissolution and diffusion of H isotopes in bcc-Fe are fundamental and essential parameters in the H energy application from nuclear conversion, whereas the relevant data are lacking and relatively dispersive, demonstrating some important factors have been missed during the past studies. Here, we carry out first-principles total energy and vibration spectrum calculations to investigate systematically the interstitial H dissolution and diffusion behaviors in bcc-Fe by considering the temperature effect. Temperature and H chemical potential are two important factors to affect the H dissolution property. In the interstitial lattice, the H dissolution energy referring to the static/temperature-dependent H chemical potential decreases/increases with the increasing temperature. The diffusion activation energy and pre-factor of H also depend on the temperature and increase significantly with the increasing temperature from 300 to 1000 K. The temperature-correction can give a reasonable interpretation for the broad disseminating in the experimental data of H diffusivity in bcc-Fe. Our currently calculated results reveal that phonon vibration energy plays a crucial role in the H dissolution and diffusion with the increasing temperature.     

Water distillation: a prototype to determine flow rate gains temperature and salt concentration changes in pressurised system

This paper studies a system to evaluate the flow rate gains in fresh water production when temperature and salt concentration changes. A pressurised system of single effect, operating at constant pressure of 80 mmHg, has been used to control the operational conditions. The distillation process has been conducted under variable evaporation temperature and salt concentration. The results have shown that there is a dependence of the production of fresh water on temperature and salt concentration whose effects are more significant as the temperature rises and salt concentration lowers. The production of fresh water can be increased by 100%. The use of low concentrated salt and sea water solutions, 20 g/l or lower, increase the production of fresh water by 33%, while at high concentrated solutions, 170 g/l or higher, the use of brine and salt water produce the same amount of distilled water.