Application of a composition of generating functions for obtaining explicit formulas of polynomials

Using notions of composita and composition of generating functions, we obtain explicit formulas for the Chebyshev polynomials, the Legendre polynomials, the Gegenbauer polynomials, the Associated Laguerre polynomials, the Stirling polynomials, the Abel polynomials, the Bernoulli Polynomials of the Second Kind, the Generalized Bernoulli polynomials, the Euler Polynomials, the Peters polynomials, and the Narumi polynomials.     

城市老旧居住小区交通环境评价指标与评价方法

定量的评判城市老旧居住小区整体交通环境质量并进而科学有效的提出老旧小区交通环境更新与改善措施,对城市老旧居住小区交通环境进行了调查,明确了老旧居住小区存在的突出交通问题,并提出了城市老旧居住小区交通环境评价的指标体系,包括行人跨路出行指数、无人行道路段长度占比、停车泊位供需比、路内非法停车占比、平均停车步行距离、泊位数量户数比、人均步行空间、无障碍通道、盲道设置比例、非机动车泊位供需比、地面停放车辆数小区面积比、外部穿行交通周转量小区面积比等。并给出了具体指标的计算方法与获得办法。以长沙市四个典型老旧居住小区为例,对评价方法进行了论证,并得到城市老旧居住小区存在的一般问题,包括人车混杂、人车交织现象严重,停车泊位短缺、车辆乱停乱放,交通设施、特别是弱势群体交通设施缺乏。给出的评价指标、评价方法与结论可为城市老旧小区改造更新,特别是其中很重要的交通环境更新提供决策依据。     

Lattice Boltzmann Study on the Motion of Dual Droplets in Microchannels With Contact Angle Hysteresis北大核心CSCD

接触角滞后表现为流体在非理想固体表面上运动时前进接触角和后退接触角不同,是两相流体在润湿表面上流动的重要现象.该文采用改进的伪势格子Boltzmann(LB)多组分模型,并与几何润湿边界条件相结合,研究了两个液滴在具有接触角滞后性微通道表面上的运动行为,主要研究了通道内特征数、通道表面性质以及液滴初始参数的影响.研究结果表明：毛细数的增大有助于液滴的移动,然而并不利于液滴的排出,且毛细数的增加对上游液滴的影响大于其对下游液滴的影响;另一方面,接触角滞后性窗口越大,液滴运动和形变更迟缓,但形变程度更明显,两液滴更早地发生合并,但更晚地排出管道;液滴间距的增加使液滴的运动行为在不同阶段表现为不同的模式,但都导致通道中残留小液滴,使得液滴排出通道的时间增加.研究结果还表明：上游液滴和下游液滴的相对尺寸差距越大,越不利于液滴排出管道.     

Market efficiency of the Post Communist East European stock markets

The stock markets from Post Communist East-European Countries are still considered highly speculative. For this reason, the previously performed tests often infirmed the efficient market hypothesis. However, especially in the past years, different studies revealed an improvement in the level of efficiency. In this context, our paper has tested the predictability of returns based on past records (as a proxy for the weak-form efficiency) for the market index and the most important stocks of 20 East European former communist countries: Bosnia-Herzegovina, Bulgaria, Croatia, Czech Republic, Estonia, Georgia, Hungary, Kazakhstan, Latvia, Lithuania, Former Yugoslav Republic of Macedonia, Moldova, Montenegro, Poland, Romania, Russia, Serbia, Slovakia, Slovenia, and Ukraine, for the period January 2008–December 2010, a period of financial crisis for most of these countries. Various methods for testing were used (unit root tests, runs test, variance ratio test, filter rules test and the January Effect). The tests have revealed that for some assets the efficient market hypothesis cannot be rejected. However, the results have shown that there are serious doubts concerning the stock market efficiency for all the countries in the analyzed period. Moreover, heterogeneity between the results for different countries was revealed. A higher level of market efficiency can suggest to decision-makers the use of passive portfolio management techniques while a lower level of efficiency implies the use of active portfolio management instruments.     

上市公司财务绩效的改进集成评价研究——以26家运输公司为例

为解决以往上市公司集成评价模型中各方法评价结果不一致问题,本文构建了改进集成评价模型。该模型先采用层次分析法、灰色关联度法、因子分析法进行评价,并运用KENDALL-W协和系数法对各评价结果进行事前一致性检验;通过检验后,再分别运用算术平均组合评价模型、Borda组合评价模型和Copeland组合评价模型进行组合评价。为了衡量组合评价与各评价方法的评价结果是否吻合,应用Spearman等级相关系数进行组合评价方法的事后检验,并根据Spearman等级相关系数的大小,选出最优的组合评价方法。最后,对中国26家上市运输公司财务绩效进行了集成评价的实证研究,并以算术平均组合评价模型的标准得分为聚类指标,采用欧氏距离法对26家上市运输公司进行聚类。结果显示:铁路、水路、公路运输各存在一个典型绩优企业,分别是:铁龙物流、北京传媒、海峡股份,四类上市运输公司中铁路上市公司财务绩效最优。     

周期排列抛物形系列沟槽引起的线性水波Bragg共振及共振相位上移北大核心CSCD

该文解析研究了有限个周期排列的抛物形沟槽激发的水波Bragg共振.首先,利用变量替换,先将系数为隐函数的修正缓坡方程(MMSE)转化为系数为显函数的显式方程.然后,构造了修正缓坡方程的Frobenius级数解,并给出了级数解的收敛条件.最后,利用质量守恒的耦合条件,建立了反射系数的解析公式.根据反射系数的解析公式,分析了沟槽个数、沟槽深度与宽度对Bragg共振峰值、共振相位和共振带宽的影响.当沟槽深度和宽度固定而沟槽个数增加时,共振峰值逐渐增大并趋向于1,而共振带宽则逐渐变窄并趋于固定值.当沟槽个数和宽度固定时,Bragg共振峰值随沟槽深度增加而增加.当沟槽个数和深度固定时,Bragg共振反射峰值随沟槽宽度增加而先增后减,预示了沟槽存在某个宽度使得共振峰值达到最大,为Bragg共振反射针对沟槽宽度的优化奠定了理论基础.特别地,前不久在有限个周期排列旋轮线形沟槽上刚刚观察到的Bragg共振反射峰值相位的上移现象,再次在该文考虑的抛物形沟槽上得到确认,表明针对有限周期排列的沟槽地形,Bragg共振反射峰值的相位上移是一个普遍现象.也因此说明,凡是正弦沙纹和周期人工沙坝所激发的Bragg共振反射,其主振相位将会下移,而凡是周期系列沟槽所激发的Bragg共振反射,无论沟槽形状如何,其主振相位都将上移.另外,我们从Bragg共振的原始定义出发,定量地解释了相位上移发生的数学机理.     

Quality rating of a metal matrix-diamondcomposite from its thermal conductivity and electric resistance

The efficiency of hot-pressed diamond-containing composite materials (DCM) for various tool applications is greatly affected by microdefects, namely, the residual porosity of the metal matrix, damaged diamond grains, and imperfect diamond-matrix interfaces. An instrumental evaluation of these microdefects, predetermining the quality of a tool equipped with DCM, is rather difficult due to the small size, the nonstandard shape, and the strong heterogeneity of specimens. Proposed here is an alternative, nondestructive technique of DCM quality rating, which includes the measurement of electric resistance and thermal conductivity of diamond-containing composites and processing the obtained data by the methods of composite mechanics. It exploits the fact that diamond, being a dielectric, possesses an extremely high thermal conductivity, which allows estimating the residual porosity of a sintered metal matrix from the ratio of specific electric resistances, one being measured and another predicted by a theory. These data, in turn, are utilized to predict the thermal conductivity ofDCMwith an imperfect matrix. Matching with experiments, after solving the inverse problem gives the thermal resistance of diamond-matrix interface, which, within the frame work of the given model, simulates the damage of both the diamond grains and their bonds with the matrix. Thus, the numerical rating of quality is given in terms of two dimensionless parameters. The first one, 0 < K < 1, reflects the quality of the sintered metal matrix, whereas the second one, 0 < R <1, is an aggregate measure of the integrity of diamond grains and the perfection degree of composite interfaces. The quite satisfactory agreement observed between the theory and experiment confirms the efficiency of the technique and the reliability of the data obtained. Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 3, pp. 361–374, May–June, 2006.     

汽车企业集团的准时化集中生产配送系统研究

汽车企业集团的准时化集中生产配送是供应链物流一体化的重要环节。实现汽车企业集团的准时化集中生产配送,要明确其目标,做好供应商关系、配送物流的统一运作、基础数据、信息网络、配送中心仓库作业设备的现代化和领导支持六个方面的基础工作;针对我国汽车企业集团的实际,构建准时化集中配送系统的框架及流程;在准时化集中配送系统运作上探讨了包括配送资源的整合、配送中心库区的划分、配送中心库位管理、配送中心库存管理、不同物料配送流程(、6)配送中心信息系统、物料索取系统等七个方面问题。     

物体垂直出入水的非定常空泡数学模型

研究了物体从水下向水面高速运动产生的非定常垂直空泡,建立了出水垂直空泡的数学模型,得到了匀速、空泡压力不变条件下的空泡外形、长度、体积随水深变化的解析解,给出了出水通气空泡发展为超空泡的条件．利用类似的方法建立了水平空泡和入水空泡的数学模型,并对3种空泡进行了比较研究．比较研究的结论是,随物体距水面的水深减小,出水空泡体积自身有增大趋势,空泡不容易发生泄气现象．且要保持出水空泡压力不变,空泡内的气体含量就应该增加（可通过人工通气方式）．入水空泡正好相反,随物体入水深度增加,空泡体积自身有收缩的趋势,并挤压空泡内的气体从环境压力较低的空泡尾部喷射而出,导致空泡内的气体含量减少,空泡压力降低．但是当空泡压力低于环境压力后,空泡尾部又将被环境高压所封闭,气体喷射不出来．随着入水深度继续增加,空泡尾部将重复上述过程,形成周期性的喷射 封闭 喷射 封闭的脉动过程,这个脉动喷射过程将在空泡尾部的流体中形成一连串小气泡,并由于空泡内的压力波动而导致空泡形状发生波动现象．     

Numerical investigation of vacuum-assisted resin transfer moulding (VARTM) within deformable fibre fabrics

The VARTM procedure is a manufacturing step in the production line when building parts made of fibre-reinforced plastics (FRP), such as glass- or carbon fibre-reinforced plastics acronymed GFRP or CFRP, respectively. In the VARTM process, an initially dry (gas-saturated) fibre-fabric is gradually impregnated by resin, where the flow process is, besides the driving injection pressure, governed by the mutual interactions between the fabric, the resin and the ambient air. To predict the mechanical properties of the manufactured structure, simulations are vital. Within the present contribution, the simulation model proceeds from the macroscopic Theory of Porous Media (TPM), which intrinsically accounts for the interplay between the individual components, in particular, the fibre-network, the ambient air and the resin, where the latter two simultaneously percolate through inter-fibrous pore space. The underlying holistic modelling approach allows, on the one hand, for a continuous transition from the fully gas-saturated towards the fully resin-saturated state and, on the other hand, the consideration of the so-called spring-back effect. The presented simulation example investigates the model behaviour within a practically relevant application scenario. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Analysis of the HDG method for the stokes–darcy coupling

In this article, we introduce and analyze a hybridizable discontinuous Galerkin (HDG) method for numerically solving the coupling of fluid flow with porous media flow. Flows are governed by the Stokes and Darcy equations, respectively, and the corresponding transmission conditions are given by mass conservation, balance of normal forces, and the Beavers‐Joseph‐Saffman law. We consider a fully‐mixed formulation in which the main unknowns in the fluid are given by the stress, the vorticity, the velocity, and the trace of the velocity, whereas the velocity, the pressure, and the trace of the pressure are the unknowns in the porous medium. In addition, a suitable enrichment of the finite dimensional subspace for the stress yields optimally convergent approximations for all unknowns, as well as a superconvergent approximation of the trace variables. To do that, similarly as in previous articles dealing with development of the a priori error estimates, we use the projection‐based error analysis to simplify the corresponding study. Finally, we provide several numerical results illustrating the good performance of the proposed scheme and confirming the optimal order of convergence provided by the HDG approximation. © 2017 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 885–917, 2017     

Dissociation effects in hypersonic flow past a circular cone at an angle of attack

The analytical solution to the steady, compressible, non-viscous, inviscid hypersonic flow past a circular cone at an angle of incidence, with an attached Shockwave, in the presence of dissociation of air in the shock layer, has been obtained here under the assumption of thermal equilibrium. Expression for the velocity, pressure, temperature, density, velocity of air, Mach number, pressure, drag and lift coefficients have been obtained both in the shocklayer outside the vortical layer and on the surface of the cone inside the vortical layer.     

季节性供应链零售商补货策略研究——基于牛鞭效应视角

通过建立含有季节性自回归移动平均需求过程的供应链,零售商采用最小均方差预测技术预测提前期需求,分析(R,D)、(R,S)、(R,βS)、(R,γO)和(R,γO,βS)五种补货策略下的牛鞭效应.研究结果表明:(R,γO)补货策略是弱化牛鞭效应的最优补货策略,然而(R,γO)补货策略时出现了反牛鞭效应,无法保证供应链的安全供给.实践中当库存量调节系数和订货量调节系数较大时,(R,βS)补货策略能有效弱化牛鞭效应,当库存量调节系数和订货量调节系数较小时,(R,γO,βS)补货策略能有效弱化牛鞭效应;对于(R,βS)和(R,γO,βS)补货策略,牛鞭效应随着库存平滑系数的增大而增大;对于(R,γO)和(R,γO,βS)补货策略,牛鞭效应随着订货平滑系数的增大而增大;对于(R,S)、(R,βS)和(R,γO,βS)补货策略,牛鞭效应随着订货提前期的增大而增大;对于(R,γO)和(R,γO,βS)补货策略,牛鞭效应随着时刻t的增大而增大,但时刻t增大到一定程度时,牛鞭效应值基本不变.     

El Naschie’s cantorian strings and duality in Weyl–Dirac theory

In the weak-field approximation, some implications of duality in the Weyl–Dirac (WD) theory, using the Gregorash–Papini–Wood approach, are investigated. Any particle is in a permanent interaction with the ‘subquantic level’ (Madelung’s fluid) and, as a result of this interaction, the particle acquires the proper fluctuation curvature and the proper fluctuation energy, respectively. By fixing the fluctuations scale, the quantum fluid orders either by means of bright cnoidal oscillation modes inducing causality, or by means of dark cnoidal oscillation modes inducing acausality, and non-linear effects, respectively. The periodic mode is associated with the undulatory characteristic, and the solitonic one with the corpuscular one. By not fixing the fluctuations scale and keeping the symmetry, the quantum fluid orders like a two-dimensional (2D) lattice of vortices, so that the duality needs coherence. In the compatibility between quantum hydrodynamics in the Madelung’s representation and the wave mechanics, the self-gravitational field of the Weyl–Dirac type physical object is generated. El Naschie’s space–time implies, by means of transfinite heterotic string theory, the masses of nucleons, and, by the gravitational fractional quantum Hall effect, the dispersion of the wave-packet on the particle. The analysis of the fractal dimension of the physical object described by the WD theory shows that the waves, and corpuscle, respectively are 2D projections of a higher dimensional special string in El Naschie’s space–time (El Naschie’s string).     

关于复模态参数的冗余性

生成仿真传递函数是考核模态识别算法和评估模态分析软件的不可缺少的环节．比较可行的3种计算方案表明:若选择将传递函数表示为复模态参数的展开式,则可以自由设定仿真模态的特性,如密频、大阻尼和复模态;然而,即使采用这种格式也不能随意设置一组复模态振型,因为这种格式的表观参数个数大于物理参数个数;故而,若对应的物理参数有意义,那么复模态参数必须满足一组约束关系．通过分析复模态系统的特征值问题,和复模态参数反演物理参数的方程式,给出了复模态参数间的一组非线性冗余约束．讨论了实模态、无阻尼和不完全模态等特殊情形的冗余约束具体形式与独立参数的个数,值得注意的是,对于实模态系统,冗余约束自动满足．给出冗余约束在传递函数矩阵和一列传递函数上的等价形式．这些结果有助于产生仿真传递函数,实施优化型识别算法,以及评估识别结果;还可用来评价残余模态和识别完整性．     

應用正二次微分形式的理論於映照半徑之乘積

<正> §1.設G是z平面上的一個區域,a_1,a_2,…,a_n是G中的n個不同的有限點.G_1,…,G_n是G中的一組不相重叠的單連區域,a_ν∈G_ν(ν=1,2,…,n).又設x_1,x_2,…,x_n是一組正數.設R(a_ν,G_ν)是區域G_ν在a_ν的映照半徑,則R(a_ν,G_ν)≤≤4|a_ν—a_ν′|,(ν’≠ν).因此,當n>1時G_1,G_2,…,G_n儘管變動,     

最坏框架与平均框架下区间[1,1]上带Jacobi权的函数逼近

本文研究最坏框架和平均框架下区间[1,1]上带Jocobi权(1 x)α(1+x)β,α,β1/2的函数逼近问题.在最坏框架下,本文得到加权Sobolev空间BWr p,α,β在Lq,α,β(1 q∞)空间尺度下的Kolmogorov n-宽度和线性n-宽度的渐近最优阶,其中Lq,α,β(1 q∞)表示区间[1,1]上带Jacobi权的加权Lq空间.在平均框架下,本文研究具有Gauss测度的加权Sobolev空间Wr2,α,β被多项式子空间和Fourier部分和算子在Lq,α,β(1 q∞)空间尺度下的最佳逼近问题,得到平均误差估计的渐近阶.我们发现,在平均框架下,多项式子空间和Fourier部分和算子在Lq,α,β(1 q2+22 max{α,β}+1)空间尺度下是渐近最优的线性子空间和渐近最优的线性算子.     

考虑延伸售后保证服务的闭环供应链定价与协调

在一个制造商和一个零售商构成的闭环供应链中,研究了延伸售后保证(Extended Warranty EW)不同提供模式下的供应链定价决策,比较了不同EW提供模式供应链的效率,设计了考虑满意度的收益共享契约协调供应链。研究结果表明:在服务成本相同的分散式决策环境下,零售商提供EW时,零售价较低,批发价也较低,同时销售量、回收率、EW价、各节点成员利润和总利润较高;无论是哪种EW提供模式,相较于集中式决策,分散决策零售价较高,而回收率、EW价和总利润较低。为实现供应链的协调,考虑到各成员的满意度,依据绝对偏离方法,设计收益共享契约。利用数值算例检验了理论结果。     

西安产业转型水平测度及其结构效应分析

以西安市的产业转型升级作为研究对象,首先从转型升级的高度、速度和方向等三个方面进行定量测度,然后采用偏离一份额分析方法对经济增长的结构效应进行分析,结果表明:1995-2015年期间,西安市产业结构非均衡化发展趋势明显,产业转型升级的水平越来越高,三次产业结构得到明显优化.2008年以来,西安市产业结构调整明显,劳动力在三次产业内部再分配的速度较快.第一产业和第二产业均发展滞后,第三产业超前发展,建筑业、金融业和房地产业结构素质较好,其增长率均高于全省平均水平,呈现明显的超前发展趋势.工业、住宿和餐饮业的结构素质较差,竞争能力相对较弱.技术进步效应是西安劳动生产率提高的重要原因.