微机化仪器中组合式A／D转换器的性能分析

本文分析了由微处理器，Ａ／Ｄ转换器及Ｄ／Ａ转换器组成组合式Ａ／Ｄ转换器的原理，介绍了设计方法和相应的设计公式，并剖析了组合式Ａ／Ｄ转换器的转换速率，误差特性等，为设计出高质量的Ａ／Ｄ转换器提供了定性和定量的保证。     

微机化仪器一组合式A／D转换器的性能分析

本文分析了由微处理器、Ａ／Ｄ转换器及Ｄ／Ａ转换器组成组合式Ａ／Ｄ转换器的原理，介绍了设计方法和相应的设计公式。并剖析了组合式Ａ／Ｄ转换器的转换速率、误差特性等，为设计出高质量的Ａ／Ｄ转换器提供了定性和定量的保证。     

基于Stewart并联机构的直驱式波能转换器能量转换性能研究

为实现对不同方向海洋来流波浪能量的高效俘获，设计了一种基于Stewart并联机构的直接驱动式波浪能量转换器，该转换器的支链单元采用弹簧连接永磁体动子，通过与定子线圈的相对运动实现波浪能与电能的转换。在特定海域波浪环境下对该波能转换器进行动力学分析，并基于弗汝德-克雷洛夫假定法计算了转换器所承受的水平和垂直波浪力；采用ADAMS动力学仿真分析软件对该波能转换器进行动力学建模与能量转换仿真分析，研究了波浪力作用下其弹性支链的变形规律，并分析了支链弹簧刚度系数与动平台质量之比对转换器能量转换率的影响。研究结果表明：在波浪激励下，该波能转换器能够俘获由垂向和横向波浪运动产生的能量；通过优化调整支链弹簧刚度系数与动平台质量的比值，该波能转换器的最大能量转换率可达35.2%。研究结果可为新型高效波能发电装置的设计提供重要的理论依据。     

高分辨率,低成本三斜式A／D转换器的研究

本文介绍了一种在挠性结构主动控制中应用的三斜式Ａ／Ｄ转换器，使用这种转换器能达到很高的分辨率，而成本确很低。     

精密AD／DC平均值转换器

精密ＡＤ／ＤＣ平均值转换器ＯｌｅｖＭａｒｔｅｎｓ等一、引言以往的ａｃ／ｄｃ平均值转换器包含有一个半波整流器或全波整流器和一个低通滤波器。这些转换器用接通和断开负反馈整流通道里的电阻器的方法来完成转换，并在正半波和负半波期间获得十ｌ或一１的增益，开关器...     

电磁流量计使用中周期检定的探讨

本从工作原理和结构特点分析着手，讨论了电磁流量计传感器和转换器的误差来源，提出了为保证测量准确度仅需要对转换器进行周期检定，而对传感器只需在安装前进行首次检定的建议。     

超磁致伸缩电——机械转换器设计及其滞回特性分析

本文介绍采用国产超磁致伸缩材料研制结果的电--机械转换器结构、工作原理、设计方法及其输入--输出特性实验结果，着重分析了转换器输入--输出滞回特性的描述方法，给出了仿真结果。     

基于SOCKS协议的IPv6/IPv4转换器

介绍了IPv6协议出现和IPv6和IPv4将长期共存的必然性。讨论了从IPv4到IPv6的各种过渡机制，包括IPv4网络中IPv6域间互联的机制及IPv6节点及IPv4节点间通信的机制。实现了一个IPv6／IPv4转换器，该转换器利用了SOCKS协议和6to4隧道方式。最后分析了这个转换器的适用性和特点。     

有源R型在线电阻／频率转换器及其接口

本文提出一种有源Ｒ型在线电阻／频率新型转换器。该转换器仅由集成运放和电阻所组成，易于集成化．通过单片机的控制．可实现对电网络的在线电阻测量。     

黑龙江省移动营业厅微波及协议转换器集中监控情景分析

传送网中的5．8G微波及协议转换器等设备因产品种类及厂商众多，一直存在无法实现集中监控，给网络的运行及维护带来较大的阻碍。本文从微波及协议转换器两个大类的组网特点出发，就实现集中监控做了详细的阐述。     

Zr在7050铝合金中的行为与作用的电镜观察

本文研究了含Zr的高强7050铝合金中Zr化合物的存在形态,尺寸和分布特点。TEM观察表明,锭铸中的Zr以ZrAl_3初晶和固溶体两种形式存在;均匀化处理的铸锭中,球形的ZrAl_3在基体上呈共格与非共格形式弥散析出,尺寸约为10～30nμ,热轧变形后,ZrAl_3大都钉轧在位错线和小角晶界上,其形态和尺寸没有明显改变;淬火后,可观察到大量存在的亚结构和亚晶粒,球形ZrAl_3质点分布在亚晶界、晶内以及位错线上,非共格的ZrAl_3周围有η相非均质成核;与含Cr的该系合金相比较,可看到E相尺寸远大于含Zr合金中的ZrAl_3质点,而ZrAl_3周围非均质成核的η相的尺寸和数量要比E相周围的小得多;淬火后经时效和双级过时效热处理,ZrAl_3质点的形态、尺寸和分布,均无显著变化。利用上述实验结果,可以园满地解释Zr对7050铝合金细化晶粒、提高再结晶温度、降低淬火敏感性以及提高强度和抗应力腐蚀性能的作用。     

Experimental investigation of oil retention in air conditioning systems

In air conditioning and refrigeration systems a small amount of oil is carried with the refrigerant and is retained in the system components. Oil retention characteristics in the condenser, evaporator, liquid and suction lines were measured and are presented and discussed here. Refrigerants R22, R410A, and R134a with miscible and non-miscible lubricants were considered to investigate oil retention physics in the widest possible range of transport properties. A parametric analysis in the suction line showed that oil retention depends on the oil mass fraction, vapor refrigerant mass flux, mixture viscosity ratio and orientation of the pipe. In the suction line, an increase in mixture viscosity of about 55% caused a rise in oil retention in the range of 50%, depending on the oil mass fraction. Oil retention in the upward vertical suction line is about 50% higher than in the horizontal line at similar conditions.     

Conservation de hachis de sardine en entreposage à l'état congeléà - 20°C: hachis obtenus à partir de sardine entière, et de sardine étêtée et éviscérée

This Paper presents a comparative study of minces prepared from headed and gutted sardines and minces prepared from whole sardines, with a view to avoiding unnecessary product handling and improving yields. Certain additives (cryoprotectants and antioxidants) were blended into some of the mince lots in an attempt to extend their storage life, and in one of the lots the mince was washed prior to mixing. The minces were prepared by extrusion and the lots were fashioned into 4 cm thick 700 g blocks, frozen in a horizontal plate freezer until a core temperature of −20°C was attained, vacuum packed and stored at −20°C for 12 months. Proximate analysis, minerals analysis (Na,K,Mg,Ca,Fe and Cu) and yield measurements were carried out prior to freezing. Protein solubility, emulsifying capacity, cooking loss, K value, pH, TBA index, viable germ counts, entero and coliform bacteria, instrumental texture analysis and sensory analysis were periodically measured. The results obtained can be summarized as follows: the method of extrusion appears to be particularly well adapted to whole fish with regard to the avoidance of handling and improving yields. In relation to mineral content the only appreciable difference is a higher sodium content in minces made from whole fish (E lots) than in minces made from gutted and headed sardines (D lots), while in the washed lots there was an appreciable decreases in the amounts of Cu, Fe, Mg and K. Protein solubility stayed at higher levels in the E lots than in the D lots, though it was high in both types of mince at the end of storage: the use of protein cryoprotectants is advisable particularly in the washed D lot (DL) and in the E lots when storage of >6 monts is required. The emulsifying capacity, which was initially higher in the E lot than in the D lot, stabilized after the second month of storage. The effect of the protein cryoprotectants was to increase slightly the emulsifying capacity, which remained higher than in the control lots throughout the storage period, even in the DL lot, which the authors feel is important with regard to the use of these minces in sausage-type products. Cooking loss was initially higher in the D lots, but after the fourth month of storage it was the same for both types. The protein cryoprotectants reduced cooking loss and were more effective in the E lots. Due to fluctuations in K values obtained, the authors do not regard them as a reliable indicator of product quality. The pH was slightly more basic in the E lots than in the D lots, and pH increased in the additive-containing lots, especially in the washed mince preparation. The TBA index only showed significant differences between the D and E lots in the final test performed. The antioxidants appeared to be more effective in the E lots than in the D lots. Washing also delayed the onset of randicity, probably through the removal of fat and catalysts with the wash water. No synergistic effect was observed between the protein cryoprotectants and the antioxidants. The total initial count of micro-organisms was substantially higher in the E lots than in the D lots because of the intestinal content, though the levels equalized during storage and at no time exceeded allowable limits. Washing did not significantly decrease germ counts. The initial excessive amounts of enterobacteria in the E lots decreased during storage, whereas the level of caliform bacteria, on the other hand, remained constant. In the E lot without additives (ESS), however, Escherichia coli was detected prior to freezing but not in any of the subsequent analyses. In general, texture as determined by instrumental methods (hardness, firmness, elasticity, and cohesiveness) gave higher values for the D lots than for the E lots. Washing increased hardness and firmness while cryoprotectants reduced them. Cooking considerably hardened the samples in the case of the D lots but did not cause variations in the E minces. Hardness and firmness remained quite stable, although there was a slight increase in the cryoprotectants-free lots and washed minces. Elasticity tended to increase in the E lots during storage, and this effect was more pronounced in the cryoprotectants-free lots; cryoprotectants had the effect of decreasing elasticity and stabilizing it in the D lots, although they were higher in the D lots than in the E lots. Elasticity and cohesiveness remained constant in the washed mince. Cohesiveness increased in all the lots during storage, and the cryoprotectants exerted no effect on this parameter. In connection with the sensory analysis, a certain sweet taste was perceived in the cryoprotectants-containing D lots, slightly reducing the quality of the product, though it was not found unpleasant and was barely detectable in the E lots. The typical sardine flavoured lots by the washed mince reduced its acceptance, though this opens up a series of technological possibilities for it. A rancid taste was detectable in the ESS lot after five months in storage, in the E lot with protein antidenaturants (ESP) after eight months, and in the E lot that contained antioxidants (ESAO) and protein antidenaturants and antioxidants (ESA), in the last test carried out.     

Hollow‐Structured Mesoporous Materials: Chemical Synthesis,Functionalization and Applications

Hollow‐structured mesoporous materials (HMMs), as a kind of mesoporous material with unique morphology, have been of great interest in the past decade because of the subtle combination of the hollow architecture with the mesoporous nanostructure. Benefitting from the merits of low density, large void space, large specific surface area, and, especially, the good biocompatibility, HMMs present promising application prospects in various fields, such as adsorption and storage, confined catalysis when catalytically active species are incorporated in the core and/or shell, controlled drug release, targeted drug delivery, and simultaneous diagnosis and therapy of cancers when the surface and/or core of the HMMs are functionalized with functional ligands and/or nanoparticles, and so on. In this review, recent progress in the design, synthesis, functionalization, and applications of hollow mesoporous materials are discussed. Two main synthetic strategies, soft‐templating and hard‐templating routes, are broadly sorted and described in detail. Progress in the main application aspects of HMMs, such as adsorption and storage, catalysis, and biomedicine, are also discussed in detail in this article, in terms of the unique features of the combined large void space in the core and the mesoporous network in the shell. Functionalization of the core and pore/outer surfaces with functional organic groups and/or nanoparticles, and their performance, are summarized in this article. Finally, an outlook of their prospects and challenges in terms of their controlled synthesis and scaled application is presented.     

Distribution of heavy metals in Lakes Doirani and Kerkini, Northern Greece

The distribution of heavy metals in two lakes of high ecological significance, Doirani and Kerkini, located in Northern Greece was studied. Eight metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were determined in water, total suspended solids, fine and coarse sediments. Moreover, the modified BCR fractionation scheme was employed in sediments and suspended solids to determine soluble, oxidisable, reducible and residual fractions of metals. The Lake Doirani presents higher metal concentrations in aqueous phase than Lake Kerkini; Cd, Cu, Ni, Pb and Zn are above the chronic freshwater quality criteria for aquatic life. In both lakes, Fe and Mn are the most abundant elements in total suspended solids whereas Cd the less abundant. The Lake Kerkini exhibits higher concentrations of all the examined metals in sediments comparing to the Lake Doirani, however the concentrations are lower than the sediment quality guidelines. Cd in sediments is mainly in soluble fraction, Pb and Cu exhibit significant oxidisable fractions whereas, Cr and Fe associated mainly with residual fraction.     

Servitization of manufacturing in the new ICTs era: A survey on operations management

Servitization of manufacturing has become one of the main pathways for transition and upgrade in the manufacturing industry. New information and communication technologies (ICTs), such as the Internet of Things, Big Data, and Cloud Computing have enabled the servitization of manufacturing in terms of value creation, resource management, and supply chain management. This study presents a comprehensive review on the servitization in operations management in the era of new ICTs. A new value chain framework is proposed under the business model that revolves around servitization, which showcases the new activities and ways of implementation in the era of new ICTs. The virtualization, configuration, and evaluation of integrated manufacturing and service resources are analyzed. In particular, the methods used in new ICT-supported resource management platforms are surveyed. Problems in the supply chain management in manufacturing services (including the selection of partners, as well as the coordination, planning, and scheduling among members) are presented. This study concludes with a discussion on state-of-the-art servitization in operations management in the era of new ICTs.     

Condition, safety and cost profiles for deteriorating structures with emphasis on bridges

After an enormous investment in construction of highway networks undertaken in the second half of the 20th century, the highway networks of most European and North American countries are now completed or close to completion. As a result, the need in funding changed from building new highway structures to repair, rehabilitation, and replacement the existing ones. In this paper, a model for analyzing the evolution in time of probabilistic performance indicators of existing structures, in terms of condition, safety, and cost under no maintenance, preventive maintenance, and essential maintenance, is presented. This model integrates the current practice in bridge management systems based on visual inspections (condition index) with structural assessment (safety index) during the lifetime of existing structures. The proposed model allows the consideration of uncertainties in the performance deterioration process, times of application of maintenance actions, and in the effects of maintenance actions on the condition, safety, and life-cycle cost of structures by defining all parameters involved in the model as random variables. Interaction between condition and safety profiles is defined through probabilistic and deterministic relations. The probabilistic characteristics of the condition, safety, and cost profiles of deteriorating structures are computed by Monte-Carlo simulation. Several realistic examples, based on data on highway bridge components gathered in the United Kingdom, are presented.     

数控设备显示器上的汉字文本阅读工效研究

目的研究影响电子显示器上汉字文本阅读工效的因素并提出建议。方法借鉴人机工程学经典理论,采用正交实验法,以数控机床显示器为对象、office word为载体,研究在显示器上进行单行和多行汉字阅读行为时字号、字距和行距对阅读工效的影响,并通过阅读速度、正确率和眼动指标来衡量阅读工效。结果在单行文本阅读中,最佳工效组合为字号12 pt、字间距2 pt;在多行文本阅读中,最佳工效组合为字号12 pt、字距2 pt、行距20 pt。结论研究得到的结果能为数控机床显示器、自助服务终端等类似机械设备上汉字格式的设置提供有效依据,让操作者能快速准确地理解和掌握文本信息,避免误操作。     

基于CiteSpace的PHA研究进展与热点分析

目的 直观把握PHA相关领域的研究进展和热点,推动PHA领域的发展。方法 以CNKI与Web of Science数据库中近10年的相关文献为对象,采用文献计量方法,使用CiteSpace软件绘制PHA研究知识图谱。结果 相关文献的年度发文量不断上升,国内外学术界对PHA领域的关注度越来越高,国际PHA领域的跨单位合作比国内更广泛。该领域的研究力量遍布全球,其中清华大学、葡萄牙里斯本新大学、马来西亚理科大学、昆士兰大学、布尔诺理工大学等机构的贡献突出、影响较大,陈国强是该领域发文量最多的学者。通过分析