连续管安全夹持摩擦系数允许区间研究

针对连续管作业机在现场作业过程中频繁发生连续管溜管、咬伤等问题,提出摩擦系数区间对连续管安全夹持的影响研究。利用实验研究和数值计算相结合的方法,在不同轴向力和夹紧力工况下,研究摩擦系数对连续管等效应力、等效塑性变形及连续管位移量的影响。以连续管屈服强度和2‰塑性变形为评判依据,得出连续管安全夹持摩擦系数允许区间为0.4~0.6。该研究为连续管安全作业具有一定的指导意义,并为夹持系统设计提供科学依据。     

复杂载荷耦合协作对连续油管极限承载能力的影响研究

针对连续油管在作业过程极易发生自锁、承受高内压等极限工作载荷,且在该极限载荷下极易失效的问题,以经典塑性极限载荷力学模型为基础,基于CAE技术,建立连续油管数值计算模型;并利用实验结果验证数值计算结果的可行性。利用已验证的计算模型研究1(1/4)″和2(3/8)″型号的连续油管在拉伸载荷、弯矩载荷、内压和挤压载荷下的承载能力。研究表明,在上述四种载荷中,得出内压和弯矩载荷是造成连续油管失效的主控载荷。根据计算结果,推荐了连续油管正常服役的载荷范围;并给出了不同载荷的极限载荷值。研究拉伸载荷、弯矩载荷、内压和挤压载荷对连续油管承载能力的影响,可有效避免连续油管提前发生失效和提高连续油管使用寿命。     

基于LNG冷能的海水冷冻淡化机理研究

为利用液化天然气(LNG)的冷能实现海水冷冻淡化,研究了海水在超低温环境下的冷冻淡化机理,试验测试了海水在不同冷冻条件下的制冰淡化性能参数,分析了各因素对海水冷冻淡化过程的作用机理及性能影响,比较得出了该工艺系统的最优运行参数。该研究结果为基于LNG冷能的海水冷冻淡化系统工艺设计提供了重要的参考依据。     

Separation of glucose and fructose by freezing crystallization

This work comprises the implementation of a methodology for the study of an industrial crystallization process by freezing and cooling to be applied in the separation of sugars with industrial relevance (glucose and fructose). The main interest is the production of fructose. This sugar is obtained by sucrose hydrolysis in acidic solutions, which yields an equimolar mixture of glucose and fructose. The developed separation process is based on the solubility difference between the sugars. Experiments were carried out in a jacketed glass crystallizer where the solution coming from the sucrose acid inversion was submitted to a slow cooling. Since glucose has lower solubility than fructose, it crystallizes in the bulk as the temperature is lowered, thus it can be removed from the solution by fliltration or centrifugation. Best fructose‐glucose separation was achieved for a total sugar concentration of 50 wt%. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The impact of quick-freezing methods on the quality,moisture distribution and microstructure of prepared ground pork during storage duration

The aim of present study was to investigate the influences of ultrasound-assisted immersion freezing (UIF), immersion freezing (IF) and air freezing (AF) on the quality, moisture distribution and microstructure properties of the prepared ground pork (PGP) during storage duration (0, 15, 30, 45, 60, 75 and 90 days). UIF treatment significantly reduced the freezing time by 60.32% and 39.02%, respectively, compared to IF and AF (P < 0.05). The experimental results of quality evaluation revealed that the L* and b* values, juice loss, cooking loss, TBARS values and carbonyl contents were decreased in the UIF treated samples, while the a* value, peak temperatures (T_m), enthalpy (ΔH) and sulfhydryl contents were significantly higher than those of IF and AF treated samples (P < 0.05). In addition, low-field nuclear magnetic resonance (LF-NMR) and differential scanning calorimetry (DSC) analysis demonstrated that UIF inhibited the mobility of immobilized water and reduced the loss of immobilized and free water, and then a high water holding capacity (WHC) was achieved. Compared to the IF and AF treatments, the UIF treated PGP samples possessed better microstructure. Therefore, UIF could induce the formation of ice crystals with smaller size and more even distribution during freezing process, which contributed to less damage to the muscle tissue and more satisfied product quality.     

水平管中残余变形管柱的摩擦力实验

连续油管钻井技术已经广泛应用到油井的各作业中,由于连续油管平时缠绕在滚筒上,塑性变形很大,虽然经过注入头的矫直,仍然会有较大的残余弯曲变形,会严重影响水平井延伸长度。本文通过相似实验得到管柱不同曲径比下所受到的摩擦力曲线拟合函数,然后再通过相似分析验证模型实验的正确性并得到各相似常数,进而求得连续油管与管壁之间的摩擦阻力。经实验数据分析得出5.08 cm (2 in) 的连续油管在经过多次弯曲变形后在水平井段所受到的阻力是理想未发生变形的2.3 倍。由此可以按摩擦系数的两倍来估算管柱所受到的实际延伸摩阻。     

蓄盐缓释融雪抑冰材料的制备及性能研究

通过表面改性试验、溶出试验和溶液电导率测定试验,筛选出可用于蓄盐缓释融雪抑冰材料的载体（载体A）和表面改性剂（表面改性剂J）,通过优化制备方法和成分配比,开发出具有降低溶液冰点功能和缓释功能的蓄盐缓释融雪抑冰材料。吸附试验和电导率测定试验的结果表明：载体A能够吸附的氯化钠含量较高,适合作为材料的载体;采用湿法吸附制备的融雪抑冰材料的缓释性能优于干法吸附制备的材料;随着表面改性剂J添加量的增大,融雪抑冰材料的缓释性增强。自制的蓄盐缓释融雪抑冰材料的组成为氯化钠、载体A、表面改性剂J,三者的质量分数分别为57.91%、38.60%、3.49%。溶出试验和溶液冰点测试试验表明自制的蓄盐缓释融雪抑冰材料具有良好的缓释性和降低溶液冰点能力。     

Freezing limits for Calogero–Moser–Sutherland particle models

One-dimensional interacting particle models of Calogero–Moser–Sutherland type with N particles can be regarded as diffusion processes on suitable subsets of ${\mathbb{R}}^N$ like Weyl chambers and alcoves with second-order differential operators as generators of the transition semigroups, where these operators are singular on the boundaries of the state spaces. The most relevant examples are multivariate Bessel processes and Heckman–Opdam processes in a compact and noncompact setting where in all cases, these processes are related to special functions associated with root systems. More precisely, the transition probabilities can be described with the aid of multivariate Bessel functions, Jack and Heckman–Opdam Jacobi polynomials, and Heckman–Opdam hypergeometric functions, respectively. These models, in particular, form dynamic eigenvalue evolutions of the classical random matrix models like β-Hermite, β- Laguerre, and β-Jacobi, that is, MANOVA, ensembles. In particular, Dyson's Brownian motions and multivariate Jacobi processes are included. In all cases, the processes depend on so-called coupling parameters. We review several freezing limit theorems for these diffusions where, for fixed N, one or several of the coupling parameters tend to ∞. In many cases, the limits will be N-dimensional normal distributions and, in the process case, Gauss processes. However, in some cases, normal distributions on half spaces and distributions related to some other ensembles appear as limits. In all cases, the limits are connected with the zeros of the classical one-dimensional orthogonal polynomials of order N.     

Viscoelastic properties of polyacrylonitrile gels: dependence of sol-gel transition on concentration and aging time

Dynamic viscoelasticity was observed for polyacrylonitrile solution in dimethylacetamide in the process of sol-gel transition. The gel was prepared by the freezing and thawing method, i.e., the solution was frozen at −50°C and then kept at 25°C so as to undergo gelation. The longer the freezing time, the shorter was the gelation time. Also the higher the concentration, the shorter the gelation time. The strength of the network, S and critical exponent n at the transition point were evaluated. The S value increased with increasing concentration and was constant in value in spite of the variation of freezing time when the concentration of the solution was constant.