Optimal performance for a steady-flow endoreversible refrigerator model including five typical cycles

The optimal performance of a universal endoreversible steady-flow refrigerator cycle consisting of a constant thermal-capacity heating branch, a constant thermal-capacity cooling branch and two adiabatic branches with heat transfer loss was analysed using finite-time thermodynamics. The analytical formulae about cooling load, coefficient of performance, exergy loss rate, exergy output rate and ecological criterion of the endoreversible steady-flow refrigerator cycle are derived. Moreover, analysis and optimisation of the model were carried out in order to investigate the effect of the cycle process on the performance of the cycles using numerical examples. The results obtained include the performance characteristics of endoreversible steady-flow Carnot, Diesel, Otto, Atkinson and Brayton refrigeration cycles. The results can provide some theoretical guidance for the design of practical refrigerators.     

长沙东方芙蓉广场高位连体结构设计

长沙东方芙蓉广场的1#,2#,3#楼通过高空钢连廊连接为双塔连体结构,在风效应或地震作用下,连体结构的动力特性因连廊的存在而相互影响,使连接部位的受力变得非常复杂,连廊极易与主体结构脱离,造成人员或财产的重大损失。采用铅芯橡胶支座的弱连接连体结构形式,对铅芯橡胶支座进行了隔震支座非线性地震响应分析,对比主体结构有连体与无连体结构的动力响应。结果表明,设计中选用的铅芯橡胶支座可以满足要求。同时由于采用了隔震支座,减弱了连体结构对主体结构的影响,可对主体结构和连体部分分别进行设计,从而降低主体结构的设计难度,保证结构的安全性。     

Effect of Microstructure of ZnO Nanorod Film on Humidity Sensing

In this study, a simple thick‐film humidity sensor was fabricated by coating wet‐synthesized ZnO nanorods on screen‐printing interdigitated electrodes. We investigated the influence of the coating procedure on the microstructure of ZnO nanorod films and thereby on humidity sensing. The experimental results revealed that the specific surface area (SSA) decreased and the average pore size (APS) increased with increasing the sintering time and the number of coating layer. The humidity response depended significantly on the pore properties of the ZnO nanorod films. By virtue of the incipient wetness analysis, it was found that the adsorption of water molecules on the ZnO surface led to the decrease in electrical resistance even though the ZnO was rod like, n‐type semiconductor. While tuning the pore structure of the ZnO nanorod film, the thick‐film humidity sensor might display near‐linear response in the full range of 0%–100% relative humidity (RH).     

Compressive mechanical properties of HTPB propellant at low,intermediate, and high strain rates

Low, intermediate, and high strain rate compression testing (1.7 × 10^?4 to 2500 s^?1) of the hydroxyl‐terminated polybutadiene (HTPB) propellant at room temperature, were performed using a universal testing machine, a hydraulic testing machine, and a split Hopkinson pressure bar (SHPB), respectively. Results show that the stress linearly increases with strain at each condition; the increasing trend of stress at a given strain with the logarithm of strain rate changes from a linear to an exponential form at 1 s^?1. By combining these characteristics, we propose a rate‐dependent constitutive model which is a linearly elastic component as a base model, then multiplied by a rate‐dependent component. Comparison of model with experimental data shows that it can characterize the compressive mechanical properties of HTPB propellant at strain rates from 1.7 × 10^?4 to 2500 s^?1. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43512.     

Towards Friction Stir Remanufacturing of High-Strength Aluminum Components

Volumetric defects in high-strength aluminum alloy components were repaired via friction stir remanufacturing (FSR). Various consumable pins made of AA7075-T6 were designed. Top diameters of the consumable pins affected material flow, which ensured that the materials at the repairing interface were forged to metallurgical bonding. Conical angles determined load transfer besides material flow, which affected the fracture of the pins before the dwelling stage. Sound repaired components were achieved when the conical angle of the consumable pin was 1° larger than that of the volumetric defect. The ultimate tensile strength and elongation of the repaired components reached 445.9 MPa and 9.6%, respectively. The design criteria of the consumable pin in the FSR was established, which provided valuable references to repair volumetric defects in high-strength aluminum components.     

基于聚苯胺的光固化防腐蚀涂层

利用十二烷基苯磺酸 (DBSA) 对本征态的聚苯胺 (PANI) 进行掺杂,将不同含量的掺杂后的聚苯胺分别加入到光固化树脂聚氨酯丙烯酸酯 (6071) 中,制备了一种低VOC排放的光固化聚苯胺防腐蚀涂层。通过实时红外以及漆膜性能的测试选择了合适的光引发剂,通过电化学阻抗谱、盐雾实验以及极化曲线对涂层的防腐蚀性能进行了测试。结果表明,加入0.4%DBSA-PANI的光固化涂层具有最佳的防腐蚀性能。     

数字矿区的设计构想

随着“数字地球”时代的到来，各“数字”工程纷纷启动，数字矿区建设也提上日程。本文从我国矿区的现状出发，从区域融合和可持续发展的角度，诠释了矿区的概念，对数字矿区建设的必要性及可行性进行探讨，给出了数字矿区建设的思路和具体框架。     

河南郁山-礼庄寨地区铝土矿重力-CSAMT综合成矿预测

郁山-礼庄寨地区处于华北陆块南部，隶属陕县-渑池-新安主要富铝（黏）土矿成矿带东段，是河南省最为重要的优质铝土矿成矿区。分别采用重力测量、可控源音频大地电磁法测量（Controlled source audio-frequency magnetotelluric method，CSAMT）、瞬变电磁测量（Transient electromagnetic measurement，TEM）、地震测量和地面高精度磁法测量在研究区进行了铝土矿深部找矿试验。结果表明：重力测量对于圈定大地构造效果显著，铝土矿床一般分布于重力高与重力低渐变过度带上；CSAMT法能反映奥陶系灰岩层面的起伏变化，可以准确判断铝土矿隐伏空间的分布状态。根据试验结果，优选重力测量和CSAMT法进行综合成矿预测，采用重力测量确定铝土矿成矿有利区，利用CSAMT法在成矿有利区准确判断隐伏灰岩侵蚀面起伏情况，推测铝土矿隐伏空间特征。综合成矿预测结果表明：①研究区铝土矿多分布于靠近古隆起边缘的凹陷区范围内，铝土矿床产于下古生界奥陶系碳酸盐岩不整合面上，严格受喀斯特地貌控制，侵蚀面上形成大小不等的洼地及溶斗是铝土矿的定位空间；②提交了渑池礼庄寨北、候岭2个大型铝土矿产地和礼庄寨深部找矿靶区1处，其中，礼庄寨北矿产地发现铝土矿矿体3条，提交资源量5 683.02万t；候岭矿产地发现矿体2条，提交资源量9 567.35万t；预测礼庄寨深部找矿靶区矿体埋深300～700 m，有较好的找矿远景；③河南省铝土矿深部成矿预测物探工作方法为重力扫面-CSAMT测量，利用重力扫面确定铝土矿成矿有利区，采用CSAMT剖面测量确定铝土矿隐伏空间特征。     

温敏性双亲水含半乳糖共聚物的合成及其胶束的自组装

采用酶促法合成与可逆加成-链断裂转移自由基聚合(RAFT聚合)有效结合的方法,制备相对分子质量(简称分子量,下同)分散系数(PDI)较低的温敏性含糖共聚物Poly(DEGMA-co-OVNG)。通过核磁共振氢谱(1HNMR),傅里叶变换红外光谱(FTIR),凝胶渗透色谱(GPC)对聚合物结构进行了表征。通过紫外-可见光谱(UV-vis)研究表明,共聚物的低临界溶解温度(LCST)可以通过共聚单体的比例进行调控,当DEGMA与OVNG的物质的量之比为8∶1时,含糖共聚物的LCST值为36℃。在37℃生理温度下,Poly(DEGMA-co-OVNG)可以自组装形成纳米胶束,透射电子显微镜(TEM)显示自组装形成的聚合物胶束是结构均匀、形貌规整的球形,通过动态光散射(DLS)测得纳米微球的粒径约为121 nm,该温敏性含糖共聚物在药物载体方面具有潜在的应用前景。     

A Nanochannel Platform for Single DNA Studies: From Crowding,Protein DNA Interaction,to Sequencing of Genomic Information

The study of nanochannel-confined DNA is important from biotechnological and biophysical points of view. We produce nanochannels in elastomer with soft lithography and proton beam writing. Issues concerning DNA confined in such quasi one-dimensional channels are discussed. We describe DNA stretching via the control of channel diameter and buffer conditions and how the extension can be interpreted with theory and computer simulation. We then discuss the conformation of nano-confined DNA crowded by neutral polymers and like-charged proteins. As an example of a protein that has an affinity to DNA, the effect of heat-stable nucleoid-structuring protein, H-NS, on the folding and compaction of DNA is reviewed. Compaction of DNA by eukaryotic protamine and unpacking of pre-compacted DNA through an increase in salt concentration are discussed. We review results obtained with a novel, cross-channel device that allows the monitoring of the dynamic, conformational response of DNA after exposure to a ligand or protein and/or a change in buffer conditions in situ. As a biotechnological application, linearization of DNA by bottlebrush coating with a polypeptide copolymer is discussed. It is demonstrated that large-scale genomic organization can be sequenced using single DNA molecules on an array of elastomeric nanochannels. Overall, our results show that the effects of ligands and proteins on the conformation, folding, and condensation of DNA are not only related to classical controlling factors, such as osmotic pressure, charge, and binding, but that the interplay with confinement in a nanospace is of paramount importance.