冷库温度波动频域分析

提出了在频域上对冷库温度波动进行分析的方法。对引起冷库温度波动的主要因素进行了分析和计算，并且研究了冷库对不同频率温度扰动的响应特性。指出可以针对引起冷库温度波动的主导扰动频率，通过改变冷库的有关参数对其产生最大的衰减，从而有效的控制冷库温度的波动。为高精度的控制冷库温度建立了理论分析模型。     

我国氨系统冷库安全现状及发展建议

基于我国氨系统冷库的安全现状和发展趋势,从冷库设备陈旧、搬迁困难等方面分析了冷库现存的安全隐患。针对我国的冷库行业特点,提出了冷库设计应标准化和冷库系统应高度自动化;针对安全管理,建议优化监测点和监测预警技术;针对泄漏处置,建议物理和化学方法相结合的无害处理方式。为我国氨系统冷库的改造和新建提供有效的技术方案。     

当前我国大、中型冷库的防火与安全、环保问题探讨

由于冷链物流的快速发展,我国冷库建设水平也不断提高,冷库建设规模日益扩大,特别是近年来各种大型冷库、多层冷库、高货架冷库相继建成,冷链物流行业发生了巨大的变化。冷库建设中的防火、安全和环保问题十分重要。在冷库规划设计中,采用积极有效的防火、安全和防护措施,保证氨系统安全和无故障运行,保护人身安全,保护环境,充分体现以人为本的宗旨。本文系统论述了当前冷库建设中防火、安全和环保问题及采取的应对措施和做法,对国外冷库防火、安全和环保的状况也作出了介绍。     

中国水产冷库集聚区的优势和发展趋势

本文分析中国水产冷库经过了小型水产冷库蓬勃发展和冷库容量快速增加的发展过程,冷库总量己超过300万吨,占全国冷库总量的1／3。本文指出,由于大型水产批发市场已经成为水产品低温物流的重要节点,所以一批为市场服务的大中型水产冷库必然会建在市场的周围,形成水产冷库集聚区。冷库集聚而建,能够降低冷库建设和管理成本,提高冷库的管理水平,达到安全、节能和高效的目标。今年出台的国家“物流业调整和振兴规划”中,已经将“物流园区”的建设列为重点工程。这将使水产冷库集聚区的发展加速。     

冷库的节能设计

在全球倡导节能减排的大环境下,本文分析了国内冷库领域的节能现状,阐述了冷库节能设计的划分和原则;归纳了冷库节能设计的要点,为广大冷库设计人员提供了节能设计参考。     

自动化冷库发展概述

本文从自动化冷库的定义、中国与欧美发达国家应用现状的对比、冷库安全等多方面浅析了冷库与自动化的关系,如何通过自动化来有效实现中国冷库行业的快速发展。     

以冷库发展趋势论设计方案

本文从冷库的设计角度,对提高冷库的利用率,建设适应市场结构不断发展变化需求的多功能冷库,冷库的操作管理,以及降低冷库的运行成本作了探讨。     

家庭式小冷库介绍

用于食品冻结、冷藏保鲜的大、中、小型冷库在全国各地都很普遍,冷库结构的种类也很多,如:一般的混合结构冷库、山洞冷库、组装式冷库以及小型整体出厂的移动式冷库等等。目前,个人及群众性集资兴建冷库也多起来了,一般而言,这类冷库的容量规模都较小。本文所介绍的是适合于个体户进行投     

有关冷库建设的一些看法与建议

鉴于近期国内涉及氨制冷系统的冷库事故,以及冷库围护结构事故的现象,对列举典型事故分别进行了点评;结合土建冷库改造,提出了一种新的施工技术;针对冷库工程建设,提出了六个方面的看法与建议。     

冷库安全技术问题探讨

冷库是低温储藏食品的适宜场所，但也是容易产生安全隐患的地方。规范冷库管理，防忠于未然，才能保证冷库的安全运行。文中论述了冷库目前在运行管理中存在的一些安全技术问题，列举了冷库发生的一些事故实例，分析了产生不安全因素的主要原因并提出应对措施。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.