Influence of conical strip inserts in heat transfer enhancement under transition flow

ABSTRACT

The performance of the concentric tube heat exchangers can be increased due to the swirl flow generation caused by the inserts which exchange heat in an effective manner. Many researchers have studied the thermal behaviour of different types of inserts, such as twisted tape and wire coil, with different geometries. This work dealt with the heat transfer and friction factor behaviour of newly fabricated staggered and non-staggered conical strip insets. The conical strip insert produces much swirl flow corresponding to the twist ratios (Y?=?2, 3 and 5). The experimental results are in good agreement with the correlations developed for Nusselt number and friction factor with the help of regression analysis.     

Exploring Large Domain Motions in Proteins Using Atomistic Molecular Dynamics with Enhanced Conformational Sampling

Conformational transitions in multidomain proteins are essential for biological functions. The Apo conformations are typically open and flexible, while the Holo states form more compact conformations stabilized by protein-ligand interactions. Unfortunately, the atomically detailed mechanisms for such open-closed conformational changes are difficult to be accessed experimentally as well as computationally. To simulate the transitions using atomistic molecular dynamics (MD) simulations, efficient conformational sampling algorithms are required. In this work, we propose a new approach based on generalized replica-exchange with solute tempering (gREST) for exploring the open-closed conformational changes in multidomain proteins. Wherein, selected surface charged residues in a target protein are defined as the solute region in gREST simulation and the solute temperatures are different in replicas and exchanged between them to enhance the domain motions. This approach is called gREST selected surface charged residues (gREST_SSCR) and is applied to the Apo and Holo states of ribose binding protein (RBP) in solution. The conformational spaces sampled with gREST_SSCR are much wider than those with the conventional MD, sampling open-closed conformational changes while maintaining RBP domains’ stability. The free-energy landscapes of RBP in the Apo and Holo states are drawn along with twist and hinge angles of the two moving domains. The inter-domain salt-bridges that are not observed in the experimental structures are also important in the intermediate states during the conformational changes.     

从减基序列到螺旋结──B-DNA螺旋扭角的经验预测模型

提出一个从DNA序列预测其二级结构的经验规则，并考虑了碱基之间的非紧邻相互作用，从小沟和大沟中环外基团的空间障碍对结果作了解释。     

Evidence of screw dislocations on (002) cleavages of lithium carbonate single crystals

Well-defined triangular etch pits are produced on etching (002) cleavages of lithium carbonate single crystals with 2% citric acid. On etching of cleavage face and matched face these pits nucleate at the intersection sites of dislocations with the cleavage face. On successive etching of a cleavage face, shallow irregular arrays of pits do not enlarge in size as compared to other isolated pits on the same face. These irregular arrays of pits have reasonable correspondence on an etched match face, suggesting they form at dislocation sites.     

基于圆弧的麻花钻螺旋槽径向截形

建立了普通麻花钻前刀面端截面曲线和用圆弧代替端截面曲线的参数方程;分别改变钻头螺旋角、钻尖半角、钻芯半厚,利用软件MATLAB计算出用圆弧代替前刀面端截面曲线的相对误差;建立了三圆弧螺旋槽径向截形的数学模型。     

摩擦纺纱加拈成纱机理的研讨

本文对摩擦纺纱加拈成纱过程进行了分析和讨论.并对影响加拈力矩的各项参数作了较详细的叙述.指出了这些参数在摩擦纺纱过程中的物理意义.     

Effect of twist on the longitudinal field loss for an in situ superconductor

The effect of twist on the full penetration loss of an in situ superconductor is calculated for the case of a longitudinal applied magnetic field. An increase in hysteresis with increasing twist is predicted due to a large anisotropy in the critical current density. The anisotropy results from the fact that the critical current density along the length of a filament in the in situ material is determined by the filament, while along the thickness it is determined by the proximity effect in the matrix surrounding the filament. From the measurements of Braginski and Wagner the ratio of these critical current densities is calculated to be about 70, which is in order of magnitude agreement with the value previously found from transverse field measurement.     

激光束的参数描述

基于对激光束按空间对称性和空间相干性的分类,对激光束的参数描述进行了研究.以有扭曲的各向异性高斯-谢尔模型光束、有扭曲的各向同性高斯谢尔-模型光束、各向异性高斯-谢尔模型光束、旋转简单像散高斯-谢尔模型光束、准直简单像散高斯-谢尔模型光束、各向同性高斯-谢尔模型光束、复杂像散高斯光束、旋转简单像散高斯光束、准直简单像散高斯光束和无像散高斯光束为典型例,对它们的分类和独立特征参数的数目作了详细分析.对一些相关问题也作了讨论.     

毫米波带条栅扭转极化器的研究

运用微波网络理论分析带条栅扭转极化器的散射场;介绍扭转极化器设计的一种优化方法;给出了8毫米波段的计算实例及其性能测试结果。