内退原丝脱圈自停装置的研制与应用

介绍了自主研发的脱圈自停装置原理、安全性和特点、装置的生产试验,并将4种无捻粗纱生产过程中采用/未采用脱圈自停装置的粗纱损耗进行对比。对比结果显示:使用脱圈自停装置的纱损耗大大减少,平均脱圈控制率为90.48%,平均减小损耗为77.8%,从而可大大降低工人劳动强度,提高生产效率,提高产品成品率,提高原丝利用率。     

煤岩气储层滑脱效应实验研究

岩石的孔隙度与岩石的渗透率成正相关。岩石的气透测渗率高于液测渗透率,且具有压力依赖性,该现象被称作滑脱效应或Klinkenberg效应。气测渗透率的压力依赖性是由于在计算渗透率时气体黏度取值不当所致,气体黏度在低压下随压力变化很大,但计算渗透率时却选用了定值。滑脱效应将使气体的黏度无法测量,从而出现测试悖论。气体分子每时每刻都在做不规则的热运动,会不停地与孔隙壁面发生碰撞,致使气体无法出现滑脱。岩石渗透率的气测值高于液测值,是测试介质的分子尺度与孔隙尺度对比的结果。     

改进拉丝机排线方式，提高多分束玻纤产品品质

简述了丝饼拉丝机的发展历程；通过分析多分束原丝易出现的络纱脱圈和端面蛛网——“毛耳朵”等问题，提出．了拉丝机排线方式的改进方案。方案经实施验证，效果良好，基本杜绝了上述问题，提高了多分束玻纤产品的品质。     

Viscoelastic Analysis of Shear Adhesion Test for Pressure-Sensitive Adhesive Tape

A new shear adhesion tester of a pressure-sensitive adhesive tape is developed, by which the slippage of the tape under shearing force can be measured as accurately as 1 μm or 0.1 μm per digit by the aid of a linear variable differential transformer. When shearing force is exerted on a tape applied on an adherend, two kinds of slippages are expected, that is, the one between the surface of the adhesive and the adherend and the other of the shearing strain of the adhesive. In order to separate the two kinds of slippages, slippage under shearing force and the recovery displacement after removing the force are measured. Analysing the results of measurements it becomes clear that viscoelastic models of Voigt units connected in series are suitable for both of the slippages.     

Viscoelastic Analysis of Shear Adhesion Test for Pressure-Sensitive Adhesive Tape

A new shear adhesion tester of a pressure-sensitive adhesive tape is developed, by which the slippage of the tape under shearing force can be measured as accurately as 1 μm or 0.1 μm per digit by the aid of a linear variable differential transformer. When shearing force is exerted on a tape applied on an adherend, two kinds of slippages are expected, that is, the one between the surface of the adhesive and the adherend and the other of the shearing strain of the adhesive. In order to separate the two kinds of slippages, slippage under shearing force and the recovery displacement after removing the force are measured. Analysing the results of measurements it becomes clear that viscoelastic models of Voigt units connected in series are suitable for both of the slippages.     

Effect of water saturation on gas slippage in circular and angular pores

A unified model for gas slip flow through circular and angular pores in both single phase flow and two‐phase flow conditions is developed, and the effect of water saturation on gas slippage factors in different pore shapes are revealed. For circular pores, the water saturation retains as thin film binding on pore surfaces without changing the shape of the cross section, and the hydraulic diameters continuously reduce as water saturation increases, directly leading to an increase in the slippage factor. However, for angular pores, the water saturation retains as both films at boundaries and condensations at corners, and the film‐water and corner‐water gradually change their cross‐section shape (from sharp corners to round corners), which further affects the gas slip behavior. Due to the presence of round corners, the ratio of the cross‐sectional area and perimeter, which can also be regarded as the reciprocal of a specific surface area, can even increase at a low water saturation condition. Thus the collisions between gas molecules and pore boundaries weaken, resulting in a slight reduction in the gas slippage factor. This interesting finding in the angular pore case directly explains the contradiction of the published experimental results with the general knowledge (i.e., the gas slip factor always increases as water saturation increases). Thus, the validity of the common assumption regarding actual porous media as capillaries with a circular cross‐section must be considered more carefully. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3529–3541, 2018     

Slip Length Measurements Using µPIV and TIRF-Based Velocimetry

The goal of this paper is to review progress (mostly recent) made in micro and nanovelocimetry, focusing on two techniques: µPIV (microparticle image velocimetry) and nanoPTV (nanoparticle tracking velocimetry). The paper focuses on the measurement of slippage (taken as a benchmark for these techniques), concentrating on work done in our group. We review the developments of µPIV that led, in the last ten years, to the achievement of 100 nm accuracy in the measurement of slip lengths. Later, this approach was complemented by nanoPTV, which recently obtained ±5 nm precision. Here, we also mention recent application of these techniques toward better characterization of microgel and polymer flows. As a whole, the two techniques have conveyed valuable information on flow behavior within and close to the boundaries of microchannels, on the importance of wetting, and on the role of surface heterogeneities. µPIV is commercially available but nanoPTV is not mature. Interesting instrumental developments are expected in the future for the latter technique.     

浓缩机行走辊轮打滑或停运数字监测系统的设计与应用

漳村煤矿选煤厂针对浓缩机原监测系统监测精度低的情况;提出对辊轮行走轨迹分区间进行开关量监测,用PLC对通过区间时间进行逻辑计算,实现了浓缩机行走辊轮打滑或停运的就地和远程报警。     

气辅挤出成型中挤出物直径的理论预测和实验研究

应用Polyflow软件对粘弹性聚合物熔体在气辅挤出口模内的流动进行了研究,得到了挤出物直径的挤出胀大比方程。模拟结果表明,熔体在滑移段的平均停留时间与材料松弛时间之比同挤出胀大比之间存在指数衰减关系。通过HDPE的气辅挤出成型实验,发现不同螺杆转速及挤出温度下挤出物直径的实验值与计算值达到很好的吻合,该计算方法可用于指导气辅口模设计。     

二效蒸发器换热管滑移的处理

在生产过程中,二效蒸发器换热管曾发生大面积堵塞的情况,经高压水清洗疏通后,才能维持生产。经检查发现,有一部分换热管发生了向下滑移的情况,有脱出管板的趋势,严重威胁生产的正常运行。分析了管子向下滑移的原因,并提出了处理的办法。     

Influence of fiber slippage coefficient distributions on the geometry and performance of composite pressure vessels

In this article, the effects of several slippage coefficient distributions on the geometry, fiber trajectories, and the structural efficiency of non‐geodesic domes are evaluated for composite pressure vessels. Several functions, which ensure C¹ continuity of the winding trajectories, are respectively used to describe the slippage coefficient distributions along the fiber paths. With the aid of the fiber slippage law and the optimality condition of equal shell strains, the differential equations that govern the non‐geodesics–based dome shapes and related fiber trajectories are formulated. The meridian profiles and winding angle developments of the carbon–epoxy domes are obtained based on the given slippage coefficient distributions; their structural performances are then determined and compared with each other. The results conclude that the non‐geodesic dome designed using the maximum constant slippage coefficient exhibits better performance than those using other slippage coefficient distributions; this is mainly triggered by maximum utilization of the longitudinal strength of the laminate. It is also revealed that the structural efficiency of domed pressure vessels can be improved using non‐geodesics that provide higher degrees of freedom in the design of filament wound structures. POLYM. COMPOS., 315–321, 2016. © 2014 Society of Plastics Engineers     

Modeling fiber slippage during the preforming process

Until now, the pin-jointed net model has been a widely used method for the prediction of preforming shape for woven fabrics. However, it deals only with pure trellising (or shear) and neglects other possible deformation modes. In some cases, there is evidence showing that other deformation modes have relevance to, and effectiveness in forming the final shape. A model considering only the shear mode will not result in an adequate prediction. In this study, a slippage model is developed to modify the pin-jointed net model. Macrostructure of the fabrics is included in the slippage model in order to capture more deformation modes. Comparisons of experimental and simulation results are presented. It is shown that the numerical prediction using the slippage model has better agreement with experimental measurements.     

Revisiting the Formation and Tunable Dissociation of a [2]Pseudorotaxane Formed by Slippage Approach

A new [2]pseudorotaxane DB24C8⊃1-H·PF₆ with dibenzo[24]crown-8 (DB24C8) crown ether-dibenzylammonium (1-H·PF₆) binding which was formed by slippage approach at different solvents and temperature, had been isolated and characterized by NMR spectroscopy and mass spectrometry. The [2]pseudorotaxane DB24C8⊃1-H·PF₆ was stable at room temperature. The dissociation rate of [2]pseudorotaxane DB24C8⊃1-H·PF₆ could be tuned by using different stimuli such as triethylamine (TEA)/diisopropylethylamine (DIPEA) and dimethyl sulfoxide (DMSO). In particular, the dissociation of [2]pseudorotaxane DB24C8⊃1-H·PF₆ by an excess of TEA/DIPEA base mixture possessed a long and sustained, complete dissociation over 60 days. Other stimuli by DMSO possessed a relatively fast dissociation over 24 h.     

A semianalytical model for simulating real gas transport in nanopores and complex fractures of shale gas reservoirs

An efficient gridless semianalytical model was developed to simulate real gas transport in shale formation with nanopores and complex fracture geometry. This model incorporates multiple physics such as gas desorption, adsorbed gas porosity, gas slippage and diffusion, residual water saturation, non‐Darcy flow, choke skin, and pressure‐dependent matrix permeability, and fracture conductivity. Additionally, this model is easy to handle complex fracture geometry through dividing fractures into a number of segments and nodes. We verified the model against a numerical model and an analytical model for bi‐wing hydraulic fractures. After validation, the impacts of all these physics on well performance were evaluated in detail through a series of case studies. The simulation results confirm that modeling of gas production from complex fracture geometry as well as modeling important physics in shale gas reservoirs is significant. This study improves our understanding of critical physics affecting gas recovery in shale gas reservoirs. © 2017 American Institute of Chemical Engineers AIChE J, 63: 326–337, 2018     

机械设计课程中“带传动设计”部分的教学方法探讨

带传动是最为典型的摩擦传动,带传动设计在机械设计课程教学中占有重要地位。作者根据多年的教学实践,对带传动设计部分的教学困难和教学目标及内在的教学逻辑进行了思考与总结;按照知识体系的理解顺序,将授课逻辑分为8个部分,并对每个部分的授课方法进行了归纳;对"带传动的受力分析"和"带传动的弹性滑动和打滑"两个较难知识点的授课过程进行了示范性说明,指出了教学过程中的注意事项。相关分析可为机械设计课程中带传动设计部分的教学提供借鉴和参考。     

Expertensysteme – ein Hilfsmittel der Prozeß-Synthese

Expert systems for process syntheses . Commercial programs used in computer-aided development of chemical processes need a process flowsheet as starting point. Preparation of flowsheets is based largely on human experience, an uncertain kind of knowledge expressed by heuristic rules. These rules are recognized as true and advantageous in most cases without having the validity of a law. Logic programming languages derived from research on artificial intelligence are proven tools for handling heuristics with so-called “expert systems”. The flowsheets proposed by the expert system reduce all theoretically possible results to a few structures. The example of structuring distillation sequences illustrates what can be expected using an “expert system” in the area of “problem solving” by comparing its proposed sequences with optimized problems.     

Selecting among the multinomial losers

In a multinomial setting with a fixed number k of cells. the problem of screening out cells to find the "best" cell, i.e., the one with the smallest cell probability, or looking for a (small) subset of cells containing the best cell is revisited. An inverse sampling procedure is used, unlike past work on this problem ([l], [2], [3], and [4]). Finding the cell with the smallest cell probability is clearly more difficult than finding the one with the argest cell probability. The proposed procedure takes one observation at a time (as usual) and igns a zero to all those (and only those) k - 1 cells into which the observation does not fall Sampling continues sequentially and stops as soon as any one cell has accumulated r zeros.

For any given integer c (with 0 ≤ c < r), we put into the selected subset (SS) all those cells with at least r - c zeros and assert that this selected subset contains the best cell. It is important to note that for the slippage configuration (SC) we can attain any specified lower bound P^? for the probability P(SCB) that the SS contains the best cell by increasing r and need not increase the value of c. Of principal interest is the case c = 0; the reason is that (i) for c = 0 the procedure is somewhat inore efficient as will be apparent later. especially after viewing the tabled results and (ii) for c = 0 our procedure never selects a subset containing all the cells. Using the SC we determine the smallest alue of r that satisfies a preassigned lower bound P^? for P(SCB). Two different is of a correct selection are considered, both related to (but stinct from) the probability P(SCB) that the SS contains the best cell. The results of this new procedure are numerically mpared with those in the references cited above using randomization to make the comparisons fair nd reasonable. If the other procedure is a fixed sample size procedure using N observations, en we wish to randomize between some r – 1 and the next integer r so that the resulting (N) for a proposed procedure will be (exactly) equal to the N-value for the other procedure. The proposed SAML (selecting among the omial losers) procedure turns out to be more efficient d, for at least one of the criteria, uniformly more efficient for all values of the specified parameters. Later we will make the conjecture based on numerical evidence that under the ive model (which was used in [1] for selecting the cell with the smallest cell probability) the SC is least favorable (LFC).     

Minimum weight design of helically and hoop wound toroidal hydrogen storage tanks with variable slippage coefficients

This article determines the optimal winding parameters for helically and hoop overwound toroidal hydrogen storage tanks, based on the application of variable slippage coefficients. First, an optimality condition between helical winding angle and hoop‐to‐helical thickness ratio is derived from the minimum strain energy density criterion. The winding angle distributions are then obtained with the aid of the optimality condition, taking into account the shell thickness variation along the meridional direction. The general criteria for fiber trajectory stability on a torus are presented, and the relationship for the slippage coefficient and the helical winding angle is formulated according to the windability and manufacturability. The helical winding angle and thickness at the equator are considered as design variables, whereas the minimum weight acts as the objective function. A design example with a toroidal hydrogen storage tank is outlined to demonstrate the favorable performance of the present method. The results show that the present method using variable slippage coefficients leads to a better distribution of the fiber stress in the toroidal shell and an efficient utilization of the laminate strength. The obtained winding parameters can thus be regarded as optimal for filament‐wound toroidal hydrogen storage tanks. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Use of ceramic coatings for yarn guides in equipment for processing man-made fibres

Conclusions Diamond smoothing of ground parts which have been coated with a ceramic considerably changes the microtopography of the surface and increases the contacting ability of the surface of the parts with the yarn as compared with diamond polishing.The entire surface of the yarn-guiding fitting allows yarn slippage, the maximum slippage rate for a definite angle of inclusion by the yarn being constant, and it depends on the state of the microtopography and the material of the surface.With the objection of reducing the slippage coefficient in using rolls coated with a ceramic, one should use the largest possible rate of yarn delivery.Translated from Khimicheskie Volokna, No. 5, pp. 58–59, September–October, 1989.     

Prediction of observer variation in estimating colorimetric values

This article describes a method for computing easily the contribution of observer variation to colorimetric values. Stiles's 20 observers are used for representing color-normal observers. Deviation functions are derived by applying singular-decomposition analysis to their 20 color-matching functions. It is shown that variances and covariances of the 20 color-matching functions are estimated correctly by using the four deviation functions with high contribution factors. By using these deviation functions, a method is developed to derive the confidence ellipsoid of tristimulus values, the confidence ellipse of chromaticity coordinates, and the confidence interval of tristimulus value Y, in the colorimetric computations of a reflecting sample and an illuminant. With a slight modification, the method also can be used to predict the degree of mismatch found by color-normal observers for pairs of reflecting samples that are a metameric match with respect to the average observer and a standard illuminant.