连铸机开浇前备包现象的讨论

针对一些钢厂在连铸机开浇前进行备包的现象,详细分析了其存在的5方面原因,提出了连铸机不备包情况下,各工序时间所应满足的计算公式。根据分析的原因提出了减少连铸机开浇前备包个数的6项措施。最后,通过分析各工序具体的时间,给出了连铸机开浇前合理备包个数的计算公式以及连铸机最大连浇炉数的计算公式。

基于有限容量排队论的铁水包个数计算模型

将"一包到底"模式下的铁水包周转过程抽象为有系统容量限制的3个串联接近闭合的排队系统,即高炉出铁、铁水脱硫以及转炉兑铁排队系统。在此基础上,提出基于有限系统容量排队论的铁水包理论周转个数计算模型。应用该模型,对重钢新区铁水包理论周转个数进行计算,结果表明:铁水包周转到达统计平衡的时间为294min,理论周转个数为17个。研究表明,减少铁水包周转个数的关键在于优化系统容量值,实际生产中主要从改进高炉配罐制度、加强炼铁炼钢工序协调等方面采取措施,并应用模型计算相关参数为:铁水包周转时间为260min,理论周转个数为15个。

供应链视角下的骨科耗材管理模式

骨科耗材传统管理模式的主流改进方案会增加医疗服务供应链成本,因而仍有必要进一步优化。该研究基于供应链视角,通过考察新增的成本点,有针对性地提出模块化备包方案,试点结果显示应用模块化备包方案可降低备包成本32.39%,减少备包数量21.43%,缩短备包时间24.91%,说明骨科耗材模块化备包方案有助于实现更低的供应链成本与更高的运营效率。

Effect of Experimental Parameters on the Encapsulation of Insulin-loaded Poly(lactide-co-glycolide) Nanoparticles Prepared by a Double Emulsion Method

Insulin-loaded poly(lactide-co-glycolide) nanoparticles (INS-PLGA-NPs) were prepared by a double emulsion method (w/o/w), using ethyl acetate as organic solvent and poloxamer188 as emulsifier. Experimental parameters such as the emulsifier and PLGA concentrations, the pH and concentration of the insulin solution, the solvent evaporation method and PVA in the internal phase were investigated for the encapsulation efficiency. The results indicated that higher emulsifier concentration, relatively less amount of PLGA and lower insulin concentration would increase the entrapment of insulin. Furthermore, pH of insulin solution approaching to pI (5.3), adding some PVA to the internal phase and a shorter evaporation time helped to enhance the incorporation efficiency of insulin. Optimized preparation parameters led to nanoparticles with well-defined characteristics such as an average size around 149.6 nm, a polydispersity lower than 0.1 and high encapsulation efficiency up to 42.8%.

Preparation of Conjugated Linoleic Acid of High Purity and Its Apparent Kinetic Characteristics During Formation

Conjugated linoleic acid (CLA) is a fatty acid with physiological activities and potential application prospect. This paper focuses on the method of synthesis of conjugated linoleic acid of high purity and the process line and conditions for its purification that can be used in large scale production. CLA of more than 95% purity was prepared by means of urea adduct purification and conjugation using safflower oil as material. The total recovery of the product adds up to more than 48%. The reactive kinetics about linoleic acid from sunflower oil converted into CLA was investigated, and its apparent kinetic model was also established, which can be used as a base for industrial designs.

Preparation of Air-Stable Iron-Oxide-Coated Metallic Iron Nanoparticles

The α-Fe nanoparticles with oxide shell were prepared by the complete reduction of iron oxide ones with hydrogen, followed by the selective surface oxidation as a thin layer. As-treated α-Fe nanoparticles preserved their saturation magnetization and metal α-Fe phase for at least 80 days in the air. In comparison, the unstabilized α-Fe nanoparticles protected only by their silica shell were oxidized instantly in the air and the saturation magnetization of the unstabilized α-Fe nanoparticles was decreased drastically. Since the stabilization procedure was carried out under dry conditions using silica-coated iron oxide nanoparticles as precursors, it could be applied to nanoparticles of various sizes and shapes to obtain a stable α-Fe phase.

Hydrodynamics and Mass Transfer of Jet Co-flow Packing Tray

The jet co-flow packing tray(JCPT) with three different types of perforation in equal opening fraction was tested in two rectangular columns with 0.12m in width and 0.27m in length operated with air-water system. The influences of gas phase orifice F-factor and clear liquid height Hc on the amount of liquid lifted, Q, were examined. The corresponding correlation between Q with F-factor and equivalent diameter of perforated holes as well as Hc was obtained. Furthermore, the non-steady state mass transfer performance of JCPT was tested by the humidification of air with water. Finally, by the analysis of data and comparison, it was found that the JCPT tray with single cap and two holes exhibited the highest mass transfer efficiency and best performance.

Process Engineering Evaluation of Modern High Performance Packings for Mass Transfer Apparatus

Modem packing technology is presented in terms of correlations and criteria for an extensive evaluation of up-to-date packing design used in current mass transfer operations. The corresponding basic information covers the process engineering aspects, e.g. volumetric effectiveness and optimum geometry of the packing, and the techno-economic aspects, e.g. when selecting a packing adopted in practice for a certain application task. The correlations required for this investigation are derived and evaluated on the basis of a comprehensive experimental re- search by testing and comparison of modem packings, such as Raschig Super-Rings and reference packings. The results thus obtained are correlated and presented in graphic presentation of diagrams, figures and tables.

多功能铁水包模式经济连浇炉数计算模型

以综合成本最优为目标,分别建立转炉热源充足及热源平衡(欠热)两种情况下的经济连浇炉数计算模型,经济连浇炉数为由铁水包备包造成的成本损失与中间包耐材损失、钢水收得率成本损失之和相减,综合成本损失最小的连浇炉数.应用该模型,以重钢新区2~#连铸机SPHC钢种为案例进行计算,转炉热源富余和热源平衡(欠热)情况下的经济连浇炉数分别为16和15炉.

Impact of Prevailing Wages on the Cost among the Various Construction Trades

In 1997, the Ohio Senate passed Senate Bill 102 which established the Ohio School Facilities Commission as a separate agency to oversee the rebuilding projects of the public schools in Ohio. The bill also exempted the construction contractors from paying prevailing wages on these projects on the hypothesis that this exemption would lower the construction cost. The purpose of this study is to investigate this hypothesis through the statistical analysis of 8,093 bids received from the years 2000 through 2007 for the schools＇ construction. Union contractors who paid their workers union wages and non-union contractors who did not pay prevailing wages bid these projects. The hypothesis, that prevailing wage laws increased the construction cost, was tested by comparing the bids/SF （square foot） from both groups （union and nonunion） for the different construction trades. The study indicated that there was statistical significant difference between the bids/square foot for union contractors and the bids/square foot for non-union contractors for only the following trades： earthwork, existing conditions, plumbing, electrical and HVAC （heating, ventilation and air conditioning）. The averages of bids/SF from the union contractors were higher than those from the non-union contractors for earthwork, existing conditions and plumbing works, and the opposite for electrical and HVAC works. There was no statistical significant difference in the bids from the communications, concrete, conveying equipment, electronic safety and security, equipment, finishes, fire suppression, furnishings, masonry, openings, structural steel, thermal and moisture protection, plastics and composites and wood works.

Research on technology innovation capability of equipment manufacturing industry in Shanghai

Equipment manufacturing industry is an important symbol to measure the industrial strength, scientific and technological innovation ability and international competitiveness of a country or region. Firstly, this paper analyzes the development status of equipment manufacturing industry in Shanghai, and then uses DEA to analyze the efficiency of technology innovation capability of equipment manufacturing industry in Shanghai. The results show that the equipment manufacturing industry in Shanghai has stronger overall drawing ability, and besides, the technology innovation ability of the transportation equipment manufacturing industry is weak, other equipment manufacturing sub industries have relatively strong ability of technological innovation. This paper analyzes the shortcomings of the transportation equipment manufacturing industry and gives guidance and puts forward corresponding suggestions and measures.

Preparation and Electrochemical Performance of V2O3-C Dual-Layer Coated LiFePO4 by Carbothermic Reduction of V2O5

The V2O3-C dual-layer coated LiFePO4 cathode materials with excellent rate capability and cycling stability were prepared by carbothermic reduction of V2O5. X-ray powder diffraction, elemental analyzer, high resolution transmission electron microscopy and Raman spectra revealed that the V2O3 phase co-existed with carbon in the coating layer of LiFePO4 particles and the carbon content reduced without graphitization degree changing after the carbothermic reduction of V205. The electrochemical measurement results indicated that small amounts of V203 improved rate capability and cycling stability at elevated temperature of LiFePO4/C cathode materials. The V203-C dual-layer coated LiFePO4 composite with lwt% vanadium oxide delivered an initial specific capacity of 167 mAh/g at 0.2 C and 129 mAh/g at 5 C as well as excellent cycling stability. Even at elevated temperature of 55 ℃, the specific capacity of 151 mAh/g was achieved at 1 C without capacity fading after 100 cycles.

Preparation of Organic Selenocystine Using Locally Isolated Bread Yeast

In contrast to the toxic inorganic forms of selenium to life at very low concentrations, the organic-selenium compounds are of considerable interest and several of them play essential roles in cell biochemistry and nutritional science. Se-yeast （Selenium-enriched yeast） is a common form of selenium used to supplement dietary intake of this important trace mineral. In the present study, we tried to prepare an organic selenocystine using locally isolated bread yeast （Saccharomyces cerevisiae）. A novel locally prepared date extract media enriched by addition of 0.2% KH2PO4 （potassium phosphate）, 0.6% ammonium sulfate was adopted as alternative culture media. Differences concentrations of selenium salt （30, 60, 120 and 240 lag/mL） were added to the yeast culture media. While the best concentration of selenium added was 30Bg/mL, it achieved optimal conditions for the growth of yeast and the production of red yeast growth identical to the standard. The products （organic selenocystine） were analyzed by HPLC （High Performance Liquid Chromatography） and AAS （Atomic Absorption Spectrophotometer） comparing with authentic standard obtained from Sigma. Results confirmed the formation of similar selenocystine products.

A Packet I/O Architecture for Shell Script-based Packet Processing

We propose a new scripting model for rapid and easier development of packet processing using shell scripts. In this paper we present EtherPIPE, a character network I/O device, that allows the programmer to access network traffic data as a file through UNIX commands. By setting a UNIX pipe ＂r＇ from or to EtherP1PE＇s output or input with UNIX commands, packets can be easily processed, executing functions such as packet filtering, packet capturing, generating arbitrary packets, and rewriting header information. In order to prove the utilities of our model, we have developed FPGA-based EtherPIPE adapter using a commodity FPGA card and a character device driver featuring new offloading functions. With our prototype implementation, packet scripting works at 1Gbps wire-speed, receiving packets with precise hardware timestamps. This paper argues for use cases of the EtherPIPE, and discusses enhanced formats of character devices for easier network scripting.）

Split-TCP Based Acceleration Gateway over Packet Lossy Networks

The conservative Additive Increase Multiplicative Decrease mechanism of traditional TCP causes the link under-utilization in the Wide Area Networks(WANs) due to the WANs' intrinsic nature of high latency and high packet loss.To alleviate the problem,we present the design and implantation of STAG,an Acceleration Gateway with Split-TCP in the paper.STAG is built on embedded network equipment and acts as a transparent proxy.In STAG,a new improved congestion control method named Rapid TCP is adopted,which determines whether or not to decrease the congestion window based on the packet loss trend.In particular,in the fast recovery phase,it chooses different window adjustment strategies based on the current size of congestion window to achieve higher utilization.The performance validation of STAG is done on both our emulation testbed and the real wide area network.The results show that STAG with Rapid TCP effectively adapts to the high loss network environment and significantly speeds up the applications without loss of fairness.

Morphology inheritance synthesis of carbon-coated Li3VO4 rods as anode for lithium-ion battery

Li3VO4 shows great potential as an intercalation/de-intercalation type anode material for energy-storage devices. Morphology tailoring and surface modification are effective to enhance its lithium storage performance. In this work, we fabricate carbon coated Li3VO4(C@LVO) rods by a facile morphology inheritance route. The as-prepared C@LVO rods are 400–800 nm in length and 200–400 nm in diameter,and orthorhombic phase with V5+. The unique core-shell rods structure greatly improves the transport ability of electrons and Li+. Such C@LVO submicron-rods as anode materials exhibit excellent rate capability(a reversible capability of 460,438, 416, 359 and 310 m A h g^-1 at 0.2, 1, 2, 5 and 10 C, respectively) and a high stable capacity of 440 and 313 m A h g^-1 up to 300 cycles at 0.2 and 5 C, respectively.