立式三缸双作用往复泵流体噪声的仿真计算与分析

为了满足用户对某新型立式三缸双作用船用往复泵噪声的要求,在数字化样机设计阶段,首先根据该泵结构型式、设计与结构参数,建立了动力学数学模型,然后根据该泵液力端3组双作用活塞缸排出口结构特征,建立了流场有限元模型,采用Fluent软件进行计算,最后将流体速度场转化为噪声值并进行了分析。结果表明该新型泵脉动小,其噪声满足相关标准要求,可为立式船用往复泵优化设计提供工程指导。     

Thermal performance enhancement of melting and solidification process of phase‐change material in triplex tube heat exchanger using longitudinal fins

Efficient application of intermittent renewable energy sources, like solar, waste heat recovery, and so forth, depends on a large extent on the thermal energy storage methods. Latent heat energy storage with the use of phase‐change material (PCM) is the most promising one because it stores large energy in the form of latent heat at a constant temperature. The current study investigates melting and solidification of PCM in the triplex tube heat exchanger (TTHX) numerically. The two‐dimensional numerical model has been developed using Ansys Fluent 16.2, which considers the effects of conduction as well as natural convection. To overcome the limitation imposed by the poor thermal conductivity of PCM, use of fins is the better solution. In the current study, longitudinal fins are used for better performance of TTHX, which increases heat‐transfer area between PCM and heat‐transfer fluid. The effects of location of fins, that is, internal, external, and combined internal‐external fins, are observed. All three configurations improve melting as well as solidification process. During the melting process, internal and combined internal‐external fins are equally efficient, in which maximum 59% to 60% reduction in melting time is achieved. For solidification, internal‐external fins combination gives maximum 58% reduction in solidification time.     

Efficient sequence-specific purification of Listeria innocua mRNA species by triplex affinity capture with parallel tail-clamps

Parallel clamps can interact in a sequence-specific manner with homopyrimidine DNA and RNA oligonucleotides to form triplexes. For longer nucleic acids, we have previously demonstrated the inhibitory effect of DNA-target secondary structures on triplex formation. We further designed a modification of these molecules-that is, tail-clamps formed by addition of a tail sequence to the parallel clamp-and proved efficient binding of the molecules with structured single-stranded DNA targets. Here we explore the possible application of the tail-clamp strategy for triplex formation with RNA targets, which are typically found as strongly folded single-stranded molecules. Efficient and specific binding of a tail-clamp designed to form a parallel triplex with Listeria innocua iap mRNA sequences has been verified by UV melting curves and triplex affinity capture techniques. Furthermore, we show for the first time the formation of stable complexes of mRNA with tail-clamps not only under acidic but also under neutral and slightly basic pH conditions. These results signify a further step towards the possible applications of triplexes with mRNA molecules; research, analytical, and therapeutic uses can be envisaged. As an example, our tail-clamp-based triplex affinity capture assay allowed the specific capture and recovery of iap mRNA molecules from an L. innocua total RNA solution with 45 % yield.     

石油磺酸盐作为轻油、水和煤三元混合燃料分散剂的研究

以TX非离子表面活性剂为乳化剂,廉价易得的石油磺酸盐表面活性剂为分散剂制备了轻油、水和煤三元混合燃料.考察了4种石油磺酸盐所制备的三元混合体系的流变性,优化选择了TX和石油磺酸盐的配比及用量.通过FTIR光谱分析了各种石油磺酸盐产品和分散性能较好的萘磺酸盐甲醛缩合物NF的结构,通过对比研究发现石油磺酸盐的原料馏分油中芳香类物质含量越多,则磺化程度越高,所得的石油磺酸盐产品分散降黏性能越好,更适合作为三元混合体系的分散剂.结果表明:F#石油磺酸盐的分散性能最好,当w(TX):w(PS-F#)=0.3%:0.8%时,可制得w(C):w(W):w(O)=63%:27%:10%和w(C):w(W):w(O)=65%:30%:5%的两种三元混合体系,在25℃下剪切速率为100s-1时体系的表观黏度分别为415.0和1060.7mPa.s,可稳定贮存60d以上,达到了工业上对煤浆燃料的性能要求.     

塑料共挤出吹塑重包装复合膜机组的研发及特点

针对三复合重包装膜应用日益广泛的现状，开发了塑料共挤出吹塑重包装复合膜机组。配备了精密的自动称量和配送供料系统，高产量挤出机，精密双螺旋平面叠加复合机头，闭环控制的自动风环，拥有自主专利的内冷系统，精巧的稳泡机构，旋转器、电晕处理器等。介绍了膜的性能要求和设备技术规范。     

用于2000型压裂车的三缸泵和五缸泵试验研究

供2000型压裂车选择的柱塞泵有三缸泵和五缸泵2种。为了验证压裂车和柱塞泵的性能，进行了台架试验、出厂试验和现场工业试验。经试验研究表明，五缸泵压裂车的参数覆盖范围较三缸泵压裂车有明显优势，五缸泵的泵效优于三缸泵。     

三重管旋喷注浆技术在隧道围岩加固中的应用

厦门机场路一期工程浦南段暗挖隧道具有浅埋、大跨、围岩软弱、周边施工环境复杂等显著特点。YK7+550～YK7+650段地表无建筑物,为了快速、安全地通过该段,本文通过对垂直高压旋喷、水平高压旋喷、全断面幕注浆在成本、工期、效果等方面做了对比分析,最终采用地表三重管高压旋喷对该段隧道内围岩进行加固,并介绍了方案设计、施工工艺及关键技术。经过三重管高压旋喷加固后,围岩强度得到了明显的提高,同时有效地抑制了洞内的失水,确保了洞内的施工安全和进度的加快,周边房屋沉降也得到了有效的控制,取得了较理想的效果.为今后类似工程的设计与施工提供了有益的借鉴。     

Experimental investigations into triplex hybrid process of GA-RDECDM during subtractive processing of MMC’s

The use of Al-6063 SiCp metal matrix composites (MMCs) in electronic packaging applications, heat sinks for printed circuit boards and for microwave housings necessitates certain degree of machining operations to meet the specifications of the product. The various conventional and non-conventional machining processes had been used to machine the MMCs. But all such processes have their limitations in providing the desired outcomes. Therefore, the present research endeavor, a new process variant of ECDM for the machining of Al-6063 SiCp MMCs. The developed grinding assisted rotary disk electrochemical discharge machining (GA-RDECDM) process integrates the concept of triplex hybridization. In GA-RDECDM, an abrasive coated rotary disk was used as a tool electrode. The abrasive coated disk provides micro gaps between the tool electrode and work material surface and thereby it results in thin and stable gas film formation. The breakdown of thin and stable gas films produce high frequency, low intensity discharges and consequently improves the machining performance. The additional abrasion action imparted by rotating disk ensures the continuation of ECDM process. The influence of various process parameters including applied voltage, pulse on time, electrolyte concentration and the disk rotation rate on width over cut (WOC) and depth were experimentally investigated. Multi criteria optimization using desirability approach predicts the parametric combination of applied voltage of 99V, pulse on time of 3 ms, electrolyte concentration of 17%wt./vol. and disk rotation rate of 30 rpm as the optimum setting for fabrication of slits on the MMCs. The underlying process mechanism is also investigated and presented with appropriate illustrations. The major contribution of the present research work is the development of a novel method for the fabrication of the slits on MMCs.