有指定行和向量与列和向量的(0,1,…,r)-矩阵

设Ｕｒ（Ｒ，Ｓ）是所有具有指定行和向量Ｒ与列和向量Ｓ的（０，１，…，ｒ）－矩阵组成的集合，给出了Ｕｒ（Ｒ，Ｓ）的结构矩阵的一些性质，以及Ｕｒ（Ｒ，Ｓ）非空时向量Ｒ与Ｓ之间的关系。     

R717/R404A直接接触凝结制冷循环的(炯)分析

提出一种R717/R404A直接接触凝结制冷系统,通过热力学计算分析了系统蒸发温度、蒸发-过冷器换热温差、主循环过冷液体过冷度、系统中间温度对系统各部分■损率及系统■效率和性能系数(COP)的影响。当蒸发温度升高,系统COP线性提升,同时系统■效率先增加后减少,在-30℃时达到最大值64.4%;当换热温差增加,系统■效率和COP均下降;当过冷度增加,系统■效率和COP均上升;存在最佳中间温度使得系统■效率和COP均达到最大值。系统中压缩机部分的■损率最大,在12.9%—14.4%之间,其次是节流阀和蒸发-过冷器均在10%左右,说明要提升系统性能,应侧重提高压缩机的效率,减少节流损失,同时优化蒸发-过冷器的设计。     

Isofrax(R)和Insulfax(R)生物可溶性纤维的研究

综述生物可溶性纤维的研究进展,介绍矿物纤维对人体健康的影响以及国际上对矿物纤维进行健康分类的主要规范.分析了Unifrax公司研制Insulfrax(R)和Isofrax(R)两种可溶性耐火纤维的基本性能和应用情况.Isofrax(R)和Insulfrax(R)均是绿色环保型隔热材料,在欧美已成功地应用于各种热处理工业中.     

R513A替代R134a应用于螺杆式冷水(热泵)机组的试验研究

为验证R513A替代R134a应用于螺杆式冷水(热泵)机组的可行性,结合R513A制冷剂特性进行机组设计及系统匹配,并对R513A机组和R134a机组性能进行对比试验研究.结果 表明,在相同工况下,R513A螺杆式冷水机组制冷量比R134a机组高2.3％,性能系数COP比R134a机组约低3.2％,综合部分负荷性能系数...     

T(0,1)模态导波在弯管上传播的仿真与实验

由于弯管的几何形状复杂,超声导波在弯管中的传播特性比在直管中复杂。弯管超声导波检测中,衡量其检测有效性的一个重要参数是透过率。通过有限元模拟研究了激励频率、弯曲半径、弯管角度对T(0,1)模态导波透过率的影响。发现:不同激励频率的导波在弯管上有不同的透过率,并且激励频率高的导波由于脉冲宽度小,更易产生新的波前;在不同的弯曲半径和弯曲角度的弯管中,最小透过率的T(0,1)模态导波的频率也各不一样;随弯管角度的变化,信号的透过率呈规律性变化。通过实验验证了不同激励频率下,T(0,1)模态导波透过率和激励频率的关系。在实际检测有弯管段的管道时,需采用多频率检测。     

求解四元数矩阵方程AHXA=B的基于矩阵半张量积的新方法

四元数线性系统在控制理论和工程中有广泛的应用。利用矩阵半张量积对四元数矩阵方程进行研究，提出四元数矩阵的一种实向量表示并研究其性质。结合实向量表示与矩阵半张量积，给出四元数矩阵方程A^HXA=B的极小范数Hermitian解的存在条件及通解表达式，并且给出相应算法。数值实验证明了实向量表示方法的可行性。     

R454B风冷涡旋式冷水(热泵)机组性能分析

对R410A和R454B在风冷涡旋式冷水(热泵)机组上进行性能对比测试，结果表明：在ASHARE额定工况下，R454B充注量约为R410A的83%;R454B制冷量较R410A低1.5%,制冷COP提高4.1%;R454B制热量较R410A低约1.6%～2.3%,制热COP高约3.1%～3.7%。另外，由于R454B排气温度较高，导致压缩机的运行范围略小于R410A。     

C_(60)-甲苯衍生物/类金刚石复合膜的光电性能研究(英文)

报导了 C_(60)－甲苯衍生物 /类金刚石复合膜的荧光光谱和光电导性能。与 C_(60)比较,室温下 观测到 C_(60)－甲苯衍生物峰值位于 460nm的光致发光现象。随掺杂剂碘的加入, C_(60)－甲苯衍生物 的荧光强度递减,但薄膜的光电导性能却增加一个数量级。实验结果还表明,类金刚石膜的复合 会使薄膜的光电导性能略微下降,但类金刚石膜可作为钝化膜使用。     

高效液相色谱法检测(S)-2-氨基丁酰胺盐酸盐的纯度

用高效液相色谱法定量分析(S)-2-氨基丁酰胺盐酸盐的纯度。用Agilent 1100型高效液相色谱仪,色谱柱Xterra C18(5μm,4.6 mm×250 mm),流动相为20%乙腈—80%,缓冲液:1000 mL水+5.0 g庚烷磺酸钠;检测波长为210 nm,流量为0.7 mL?min-1,柱温30℃,对(S)-2-氨基丁酰胺盐酸盐纯度进行定量测定。相对标准偏差0.15%,标准回收率99.8%~100.2%,方法重复性好,定量准确度高。     

真空蒸发制备Cd(Se,S)薄膜及其光学性能研究

利用真空蒸发技术在CdS粉末中掺入不同比例的Se粉末作源,选择合适的工艺条件在玻璃衬底上获得了性能稳定的Cd(Se,S)薄膜,薄膜为纤锌矿结构,具有沿[002]晶向的择优取向.Cd(Se,S)薄膜为n型材料,在可见光范围内具有良好的透过率.随Se成分的增加,薄膜由透明橘黄色变为透明棕红色,吸收限向长波方向移动.     

Microstructure,thermodynamics and compressive properties of AlCrCuNiZrx (x = 0,1) high-entropy alloys

Two high-entropy alloys (HEAs), AlCrCuNiZr_x (x?=?0,1), were prepared by arc melting. The AlCrCuNi alloy consists of a face centered cubic (FCC) phase, a body centered cubic (BCC) phase and an eutectic phase, while the AlCrCuNiZr alloy contains a FCC phase, a BCC phase and an intermetallic phase. The traditional thermodynamic parameters of HEAs were converted into thermodynamic-parameter-functions of composition variable x, including ΔG_mix(x), ΔH_mix(x), ΔS_mix(x), Ω(x), δ(x),Δχ(x) and VEC(x). The thermodynamic-parameter-curves could be obtained through thermodynamic-parameter-functions via Matlab. The thermodynamics of the two alloys were analysed using the thermodynamic-parameter-curves of the AlCrCuNiZr_x (x∈[0 1]) alloys. The addition of Zr to AlCrCuNiZr favours the formation of intermetallic compound, enhances the yield strength, compressive strength and Vickers hardness, but degrades ultimate strain.     

A new iterative order reduction (IOR) method for eigensolutions of large structures

Order reduction is a computationally efficient method to estimate some lowest eigenvalues and the corresponding eigenvectors of large structural systems by reducing the order of the original model to a smaller one. But its accuracy is limited to a small range of frequencies that depends on the selection of the retained degrees of freedom. This paper proposes a new iterative order reduction (IOR) technique to obtain accurately the eigensolutions of large structural systems. The technique retains all the inertia terms associated with the removed degrees of freedom. This hence leads to the reduced mass matrix being in an iterated form and the reduced stiffness matrix constant. From these mass and stiffness matrices, the eigensolutions of the reduced system can be obtained iteratively. On convergence the reduced system reproduces the eigensolutions of the original structure. A proof of the convergence property is also presented. Applications of the method to a practical GARTEUR structure as well as a plate have demonstrated that the proposed method is comparable to the commonly used Subspace Iteration method in terms of numerical accuracy. Moreover, it has been found that the proposed method is computationally more efficient than the Subspace Iteration method. Copyright © 2003 John Wiley & Sons, Ltd.     

Effect of orientational order of tris(8-hydroxyquinolinato)aluminum(III) on electroabsorption

The electroabsorption (EA) spectrum was analyzed in terms of the orientational order of tris(8-hydroxyquinolinato)aluminum(III) (Alq₃) molecules, where the orientational order parameter P_n(cosθ) (θ: the tilt angle of molecule; P_n: nth Legendre polynomial; : thermodynamic average) was used to quantify the anisotropic orientational order of Alq₃. It was shown that the EA intensity is a function of S₁ and S₂ at the modulation frequency ω, whilst it is a function of S₂ at the second-harmonic frequency 2ω. The EA spectrum for the vacuum deposited Alq₃ was obtained from the optical transmittance measurement. The results suggested that the spontaneous polarization of Alq₃ is generated in the evaporated films.     

Estimation of the order of an auto-regressive model

There are no definitive solutions available for the order estimation of the auto-regressive process. First, the performance of the three criteria, namely FPE, AIC and MDL is illustrated. Next, it is indicated that there are possibilities of their performance being improved. The algorithmtri proposed here utilizes three minimum values of any of the conventional loss functions in the FPE, AIC and MDL methods. It also uses three statistics derived from these three minimum values. The estimated order is a rounded weighted average of these six statistics. The algorithm is found to do better in a qualified sense of yielding peakier distribution of the estimated orders when tested for 1000 synthetic models of orders 3, 5 and 7 each. The conclusion drawn is that there are open possibilities of improving upon the conventional order estimators for auto-regressive processes. This means that till axiologically sounder estimators are available one should be ready to use heuristic estimators proposed here.     

Determining the number of zones in a pick-and-sort order picking system

In this study we consider a pick-and-sort order picking system, in which batches of orders are picked simultaneously from different (work) zones by a group of order pickers. After picking, the orders are transported by a conveyor to a next station for consolidation and packing. Packing can only occur when an order has been picked completely. For a given number of workers, each assigned to a single zone, a larger number of zones reduces pick time (since travel time reduces), but increases waiting time for completion at the packing stations, because more partial batches needing assembly arrive at the packing stations. Our aim is to determine the optimal number of zones such that the total (picking and packing) time to complete a batch is minimised. We solve this problem by optimally assigning items to pick routes in each zone. We illustrate the method with data taken from a distribution centre of one of the largest online retailers in The Netherlands.     

非负矩阵Perron根的估计

本文研究非负矩阵Perron根的界值,定义了矩阵有向图的1-path覆盖,利用矩阵的有向图及有向图的1-path覆盖,给出了估计非负矩阵Perron根上、下界的新方法,改进了已有的估计结果,有效提高了估计的精度。     

求解地面运动激励下的部分覆盖约束层阻尼贮液圆柱壳耦振的整合状态传递矩阵法

摘要：基于一般情况下的线弹性薄壳方程和势流理论,考虑被动约束层阻尼（PCLD）的剪切变形的能量耗散和液固耦合相互作用,文中首先导出了PCLD圆柱层合壳的整合一阶矩阵微分方程,该方程的状态向量的每个元素都有明确的物理意义,更方便用于层合壳体在各种边界支承条件的动力学问题的求解。然后通过将流体动压力写成含待求系数的解析形式,借助流固交接条件、新型齐次扩容精细积分法和叠加原理,建立了一种分析该类结构耦振问题的高效率、高精度的半解析半数值方法。通过与无水、两端简支的全覆盖PCLD圆柱壳在轴对称情况下自由振动的解析解结果比较,验证了本文方法的有效性。最后基于文中提出的方法,研究了部分覆盖PCLD贮液圆柱容器在地面运动激励下的动力响应,研究了PCLD厚度、长度、敷设位置以及粘弹芯的复剪切模量模型对减振效果的影响。     

线性矩阵方程(ATXA,BTXB)=(C,D) 的反对称解

利用矩阵对[A，B]的商奇异值分解(QSVD)，建立了线性矩阵方程(A^TXA，B^TXB)=(C，D)反对称解存在的充分必要条件，并给出了通解的表达式，同时导出了此方程的最小二乘反对称解的表达式。     

Matched interface and boundary (MIB) for the implementation of boundary conditions in high‐order central finite differences

High‐order central finite difference schemes encounter great difficulties in implementing complex boundary conditions. This paper introduces the matched interface and boundary (MIB) method as a novel boundary scheme to treat various general boundary conditions in arbitrarily high‐order central finite difference schemes. To attain arbitrarily high order, the MIB method accurately extends the solution beyond the boundary by repeatedly enforcing only the original set of boundary conditions. The proposed approach is extensively validated via boundary value problems, initial‐boundary value problems, eigenvalue problems, and high‐order differential equations. Successful implementations are given to not only Dirichlet, Neumann, and Robin boundary conditions, but also more general ones, such as multiple boundary conditions in high‐order differential equations and time‐dependent boundary conditions in evolution equations. Detailed stability analysis of the MIB method is carried out. The MIB method is shown to be able to deliver high‐order accuracy, while maintaining the same or similar stability conditions of the standard high‐order central difference approximations. The application of the proposed MIB method to the boundary treatment of other non‐standard high‐order methods is also considered. Copyright © 2008 John Wiley & Sons, Ltd.