(H,R)-Lie coalgebras and (H,R)-Lie bialgebras

Given an (H,R)-Lie coalgebra Γ, we construct (H,R _T )-Lie coalgebra Γ^T through a right cocycle T, where (H,R) is a triangular Hopf algebra, and prove that there exists a bijection between the set of (H,R)-Lie coalgebras and the set of ordinary Lie coalgebras. We also show that if (L, [, ], Δ, R) is an (H,R)-Lie bialgebra of an ordinary Lie algebra then (L ^T , [, ], Δ_T, R _T ) is an (H,R _T )-Lie bialgebra of an ordinary Lie algebra.     

Forced Convection with Slip-flow in a Channel or Duct Occupied by a Hyper-porous Medium Saturated by a Rarefied Gas

An analytic solution is obtained for forced convection flow in a parallel-plates channel or a circular duct occupied by a hyper-porous medium saturated with a rarefied gas in the slip-flow regime, for the case of uniform flux boundary conditions. As expected, it is found that velocity slip leads in general to increased heat transfer and temperature slip leads to reduced heat transfer.     

Computational study of shock wave focusing in a log-spiral duct

The mechanism of shock wave focusing in a two-dimensional log-spiral duct has been investigated here numerically using a finite volume method. This approach is based on a MUSCL TVD scheme with flux-vector splitting applied to the Euler equations. The isopycnics determined from the calculations are compared with the experimental results obtained by use of holographic interferometric photography and are found to be in excellent qualitative agreement with the experiments. The computational results clarify the details of the wave interactions very near to the focus. In particular, phenomena such as the formation of secondary shock waves prior to the implosion, their interaction with the reflected shock and the formation of vortices after the implosion have been examined.     

An experimental technique for measuringtransient natural/forced convective heatfluxes in a vertical channel

A series of systematic experiments for measuring transient natural andforced convected heat fluxes in a one-sided heated vertical channel have beenconducted. The total heat input in transient natural and forced experiments iscomposed of four kinds modes: radiative heat loss, conductiveheat lossm, thermal capacity of the plate, and convective heat transfer in thetest channel. In the transient periods, the generalized correlations for estimatingtransient convective heat flux are proposed in natural and forced convectionexperiments. By using the proposed q_c^″ distributions, satisfactory agreementsare achieved between the transient Nu_x predictions and experimentaldata.     

进气道实验中动态数据采集及处理方法研究

本文介绍了进气道实验中动态数据采集及处理方法，研究了滤波器截止频率以及进气道不同流量对动态畸变指数的影响，对在干扰状态下得到的数据以传统方法、统计方法、误差方法进行了分析及处理，并对所得到的实时数据进行了频谱分析。     

有限元网格自动生成及自动调整技术

本文给出了一种任意平面域内三角形网格自动生成及自动调整算法，并编制了相应的程序。通过对带Ｕ形槽的三点变曲试件的分析，证明本文算法是可行的，并且具有稳定性能好、收敛速度快的优点。     

90°弯管内流动的理论模型及流动特性的数值研究

从三维不可压缩雷诺时均Navier-Stokes方程出发,对90°弯曲管道内湍流流动进行数值模拟。网格划分采用六面体网格,湍流模型为RNGk-ε模型,在近壁区采用两层壁面模型进行修正,流场的计算结果与实验数据吻合较好。在此基础上,本文数值研究了来流方向对流场结构和流动特性的影响。得出在弯管流场中发生了分离现象,且随着来流侧滑角的增大,分离区范围增大。此外,随着来流从同一侧滑角变换至同一攻角时,横截面的二次流图像中也从具有两个对称主涡变成只具有一个主涡的现象。     

Thermally Developing Forced Convection in a Porous Medium: Circular Duct with Walls at Constant Temperature,with Longitudinal Conduction and Viscous Dissipation Effects

A modified Graetz methodology is applied to investigate the thermal development of forced convection in a circular duct filled by a saturated porous medium, with walls held at constant temperature, and with the effects of longitudinal conduction and viscous dissipation included. The Brinkman model is employed. The analysis leads to expressions for the local Nusselt number, as a function of the dimensionless longitudinal coordinate and other parameters (Darcy number, Péclet number, Brinkman number).     

基于端点白化权函数聚类的水环境质量等级评价分析

为更准确地评价水环境质量,将端点三角白化权函数灰色评估引入到水质综合评价中.针对以往灰色白化权函数评估主要通过测定指标灰聚类系数判定被评价对象的优劣强弱等级进行等级识别评价,对三角白化权函数计算方法进一步扩展,完成多评价对象的准确等级定位及比较排序.将这种方法应用于山东省聊城市东昌湖水水质评价中,经实例计算证明基于三角白化权函数灰色评估评价模型的稳定性、合理性和实用性为水质评价研究方法提供了新的思路和借鉴.     

N—H…X (X = Cl and Br) hydrogen bonds in three isomorphous 3,5‐dichloropyridinium salts

Specific short contacts are important in crystal engineering. Hydrogen bonds have been particularly successful and together with halogen bonds can be useful for assembling small molecules or ions into crystals. The ionic constituents in the isomorphous 3,5‐dichloropyridinium (3,5‐diClPy) tetrahalometallates 3,5‐dichloropyridinium tetrachloridozincate(II), (C₅H₄Cl₂N)₂[ZnCl₄] or (3,5‐diClPy)₂ZnCl₄, 3,5‐dichloropyridinium tetrabromidozincate(II), (C₅H₄Cl₂N)₂[ZnBr₄] or (3,5‐diClPy)₂ZnBr₄, and 3,5‐dichloropyridinium tetrabromidocobaltate(II), (C₅H₄Cl₂N)₂[CoBr₄] or (3,5‐diClPy)₂CoBr₄, arrange according to favourable electrostatic interactions. Cations are preferably surrounded by anions and vice versa ; rare cation–cation contacts are associated with an antiparallel dipole orientation. N—H…X (X = Cl and Br) hydrogen bonds and X …X halogen bonds compete as closest contacts between neighbouring residues. The former dominate in the title compounds; the four symmetrically independent pyridinium N—H groups in each compound act as donors in charge‐assisted hydrogen bonds, with halogen ligands and the tetrahedral metallate anions as acceptors. The M —X coordinative bonds in the latter are significantly longer if the halide ligand is engaged in a classical X …H—N hydrogen bond. In all three solids, triangular halogen‐bond interactions are observed. They might contribute to the stabilization of the structures, but even the shortest interhalogen contacts are only slightly shorter than the sum of the van der Waals radii.