A Computational Model for Two—stage 4K—Pulse Tube Cooler：part I.Theoretical Model and Numerical Method

IntroduedonThe need for ctyogenic coOling of magnehcresonance imaging (MRI), superconduchng quantUminterfernce devices (SQUIDs) and the associatedsuperconduchng devices has brought about a strOngdemand for high reliability and efficiency in coolers.SWg and GM coolers, which are very compact andreliable machines and have already commercial products,are widely used for such aPplications in the last decades.However, they have a tnoving pistOn at the cold end,which caused evidenily mechotal …     

弦支双曲扁网壳结构的鲁棒构型分析及试验研究

针对不良拓扑布置导致的结构鲁棒性不佳问题，以系统传递函数的H₂范数为基础，建立结构鲁棒性定量评价指标和鲁棒构型求解方法。以单元相对密度为设计变量，采用变密度模型描述材料的刚度，将结构的鲁棒设计转化为连续体拓扑优化，并对大爆炸算法进行二级搜索的改进，进而求解连续体拓扑优化模型。以四点支承的弦支双曲扁网壳结构为例，分析不同荷载作用下的鲁棒构型，探索不同参数的大爆炸算法优化效果，通过静力试验和冲击试验，对优化后模型和未优化模型进行对比分析。结果表明，二级搜索的大爆炸算法可以有效地应用于弦支结构的鲁棒设计中，改进的大爆炸算法加快了收敛速度，依据鲁棒构型进行杆件布置，可显著提高结构的力学性能和抗干扰能力。     

Meta-Analytic Structural Equation Modeling: A Two-Stage Approach.

To synthesize studies that use structural equation modeling (SEM), researchers usually use Pearson correlations (univariate r), Fisher z scores (univariate z), or generalized least squares (GLS) to combine the correlation matrices. The pooled correlation matrix is then analyzed by the use of SEM. Questionable inferences may occur for these ad hoc procedures. A 2-stage structural equation modeling (TSSEM) method is proposed to incorporate meta-analytic techniques and SEM into a unified framework. Simulation results reveal that the univariate-r, univariate-z, and TSSEM methods perform well in testing the homogeneity of correlation matrices and estimating the pooled correlation matrix. When fitting SEM, only TSSEM works well. The GLS method performed poorly in small to medium samples. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

超大尺寸双级注水泥器的研制与应用

为解决常规双级注水泥器关闭不严、关闭压力过高及在扫除附件后密封失效等问题,开发了YFZ-A型外关闭式大尺寸双级注水泥器。该双级注水泥器由双级箍总成、挠性塞、打开塞、关闭塞、中胶塞及挠性塞座等部件组成。该注水泥器采用外关闭式结构,将关闭套置于双级注水泥器本体外,在进行扫塞作业时,可有效避免钻头损伤关闭套及其密封件情况的发生,从而根除了扫塞后密封失效问题;另外,它一改由关闭塞推动关闭套下行关闭的传统结构型式,而由液压推动关闭套下行关闭,使得关闭更可靠。密封试验及各种功能试验表明,挠性塞通过压力、打开压力、关闭压力、密封能力等各项性能指标均达到设计要求,并在现场取得良好应用效果。     

混凝吸附一两段SBR法处理垃圾渗滤液

利用赤泥制备复合混凝剂PAFCS（聚合硫酸氯化铝铁）并以炉渣作为吸附剂对垃圾渗滤液进行预处理，对SS和色度的去除率分别为84％和92％，对COD的去除率可达53．3％，还提高了渗滤液的可生化性。然后采用两段SBR法对垃圾渗滤液进行生化处理，结果显示：通过对降解COD和氨氮的两类微生物分别进行培养，保持了较高的生物活性，进而提高了对此类高浓度难降解废水的处理效率。通过两段SBR处理以后，COD、BOD和氨氮的去除率分别为88％、94％和89％，出水水质达到了国家《生活垃圾填埋污染控制标准》（GB 16889—1997）的二级标准。     

Results of Complex Tests of the TGMP-314 Boiler of Cogeneration Plant-23 of the Mosénergo Company After Renovation

Results of complex tests of the TGMP-314 boiler of thermal power plant-23 of the Mosénergo Company operating on natural gas and furnace oil after design improvement are presented. Toxic emissions of nitrogen oxides were diminished by the use of low-toxicity burners, supply of air to secondary blow nozzles, and introduction of recirculating gases into the burner channels. These measures lowered the emissions of NO_x, benz(a)pyrene, and other harmful substances into the atmosphere below the standardized values. The boiler proved to operate reliably in the entire range of tested loads in the gas- and oil-fired modes with stage firing and recirculation of flue gases. The rated parameters of live steam and reheat steam were steadily maintained.     

A two-stage preparation of mesophase pitch from the vacuum residue of FCC decant oil

The preparation of mesophase pitch as a precursor for the high-performance carbon fiber from a vacuum residue of FCC-decant oil (FCC-DOVR) was studied, applying a two-stage heat treatment to improve the pitch yield as well as its liquid crystal properties. The present two-stage preparation consisted of the pressurized heat treatment (1–5 MP) of the first stage at 430–480°C and the successive heat treatment under 13–260 Pa at 430°C. Such a two-stage preparation increased the yield of the spinnable mesophase pitch of 100% domain texture with lower softening point to 45% from 22% by the single-stage one from the same feedstock. Spinning properties of the mesophase pitch were excellent to allow smooth spinning for longer than 15 min and random orientation of mesogen molecules in the tranverse section of the fiber perpendicular to the fiber axis. The chemistry of the two-stage preparation for the higher yield and better properties as the fiber precursor is briefly discussed.     

照相机开关外壳注射模设计

介绍了照相机开关外壳模的结构特点及模具的工作过程。采用斜滑块抽芯 ,解决了一模多腔的难点 ;采用二级推出使操作简易 ,模具更可靠     

Effects of remittances on renewable energy consumption: Evidence from instrumental variable estimation with panel data

This study investigates the impact of remittances on renewable energy consumption (REC) using a panel of 25 top remittance-receiving countries for 1990–2018. We use a generalized two-stage least squares random effect model to estimate the impact of remittance on renewable energy use. Results showed that remittances and REC have a generally positive relationship among the studied nations. Governments may create a system to incentivize remittance-receiving households to adopt and utilize more carbon-neutral energy devices at a lower cost if they pay with remittances. This approach could lead to higher societal adoption and consumption of green energy.