推广的多变量Bernstein—Kantorovi 多项式在Lp—空间的逼近

关于二元函数 f(x,y)的 Kantorovi 多项式的逼近问题谢敦礼在文中进行了研究,并得到某些结果,本文在引进推广 Bernstein—Kantorovi 多项式概念的基础上,得到两个新定理,它推广和改进了文中的结果。     

边际分析在生产决策中的作用

在企业的经营管理和生产决策中,经常要研究经济函数,例如产品的总成本函数C(q)、总收益函数R(q)和总利润函数L(q),其中q是产品的产量。我们知道,对于一个函数y=f(x),它的平均函数     

应区别“同一个函数”与“相等的函数”两个概念

本文通过分析“y=|x|既是初等函数又不是初等函数”这一矛盾结果,指出了习惯使用的“同一个函数”的概念是导致这一矛盾的原因,并提出了应建立和使用“相等的函数”这一概念的观点。     

具有特征值的两点边值问题的正解

研究测度链T上边值问题[q(t)xΔ(t)]Δ+λf(t,xσ(t))=0,t∈[a,σ(b)]∩T,αx(a)-βxΔ(a)=0,γx(σ(b))+δxΔ(σ(b))=0,其中f:[a,σ(b)]×[0,∞)→[0,∞)是连续的,对f赋予一定的条件,通过应用锥上的不动点定理,得到在λ某个区间上边值问题正解的存在性定理。文中把原有的方程二阶部分从xΔΔ(t)推广到[q(t)xΔ(t)]Δ,这里要求q(t)在[a,σ(b)]上有界,恒正。     

根据定子绕组排列判定电动机的极数

三相异步电机的定子绕组按照一定的规律嵌放在定子槽中,只要观察一下线圈两边所跨过的槽数(即线圈节距y)和定子的总槽数Z,便可根据2ρ≤z/y判定出电动机的极数。当Z与y的比值为偶数时,这个数便是电动机的极数2ρ;当比值为非整数时,最接近这个数的偶数(整数)便是电动机的极数。如遇到有几种节     

设备的四象限区域管理法

要搞好设备管理,必须对设备的状态(好、坏)和状况(在厂、非在厂)了如指掌。我们可借助于平面直角坐标系,采用四象限区域管理法来达到满意的效果。把x 轴作为状态轴,表示设备的好、坏,+为好设备;-为坏设备;把y 轴作为状况轴,+为在厂(矿),-为不在厂(矿)。x 轴与y 轴组成四象限区域,如图1所示:     

YD-800TS仿形铣床的数控改造

一、设备改造前的状态 YD-800TS三头三坐标仿形铣床是我厂1979年从日本引进的,具有三个功能相同的动力头.三头间距550mm;工作台面积800mm×2500mm;工作台行程x向1500mm,y向800mm,z向500mm;主轴到工作台面间距离200～700mm;主轴转速40～2000rpm/min(18级);主轴电机功率交流11kW;进给速度x、y、z三个方向均为10～2000mm/min,无级变速;主轴座(z轴)驱动电机:3kW直流伺服电机,带有制动装置,静摩擦力矩40N*m,工作台(x轴)及床鞍(y轴)分别由2kW直流伺服电机驱动.传动部分采用滚珠丝杠螺母副,导轨是镶钢滚柱结构.     

DK77线切割机床故障分析

DK77线切割机床由主机、接口板、系统电源、床身四部分组成。现就几种故障现象分析如下 :1 x轴响声异常本机床驱动采用三相六拍步进电机控制x、y两坐标运动。检查数控系统A、B、C三相均衡 ,通电时有时x轴能锁住 ,有时锁不住 ,运动时发出“嘎嘎”声。断电后丝杠转动无异常声音 ,测x轴步进电机绕组 ,发现有一相绕组偏大 ,正常应为 8Ω ,更换步进电机后机床正常。2 y轴尺寸不稳查y轴电机绕组正常 ,驱动部分电气原理如图 1。图 1y轴驱动信号灯 (图 1中发光二极管 )A、B、C三相正常 ,加在Y电机上的三相绕组的电压均衡 ,拆下电机仔细检查 ,发…     

HC轧机辊间接触压力分布及辊系变形计算(HC轧机板形控制机能的研究之一)

本文采取整体模型法和分割模型法;以及在计算上采用功的互等定理、影响函数法、迭代法等。对 HC 轧机辊系变形、剪切变形、接触压力、板厚分布等有问进行理论探讨。     

一类泛函脉冲微分方程周期正解的存在性

利用Krasnoselskii不动点定理,讨论一类带参数的泛函脉冲微分方程多个周期正解存在的充分条件,在f(x)和I_k(x) 均为非超线性和非次线性的条件下,得到该类微分方程多个周期正解存在的一些新结果。     

空间[J,ρ]的一些拓扑性质

文献[6]已经证明了 Julia 例外函数集 J,在一致球面收敛的意义下是一个线性闭色。本文在 Julia 例外函数集 J 上引入了距离函数,讨论了距离空间[J,ρ]的一些拓扑性质,得到了正规族理论中,一致有界的连续函数集正规和解析函数集正规这两个定理的抽象形式。     

广义FUZZY映射的不动度定理

本文把通常的 FUZZY 映射推广为广义 FUZZY 映射,并给出了几个广义 FUZZY 射映的不动度定理。所得结果推广了张石生在中第Ⅰ、Ⅱ类 FUZZY 映射的一些结果。     

Closed-form solutions for Wee’s and Martin’s EOQ models with a temporary price discount

In this article, we use closed-form solutions to solve Wee and Yu (1997) deteriorating inventory model with a temporary price discount and Martin’s (1994) EOQ model with a temporary sale price. In Wee and Yu (1997) and Martin’s (1994), the benefits during the temporary price discount purchase cycle are represented by their objective functions. Wee and Yu (1997) and Martin (1994) only used search methods to find approximate solutions. Following the theorems we suggested, you can find closed-form solution directly when there are integer operators involve in an objective function. Using the data of Wee and Yu (1997) and Martin (1994), we can find the results are more quick and more accurate.     

概率度量空间中PUzzy映射的不定点定理

本文给出了概率度量空间 Fuzzy 映射的概念。并且对张石生提出的概率度量空间的第Ⅰ、Ⅱ、Ⅲ类压缩映射进行了 Fuzzy 推广,得出了几个 Fuzzy 映射的不动点定理。     

Bundling of substitutes or complements

The Adams-Yellen two good bundling framework is generalized to allow the goods to be substitutes or complements. General theorems on price change effects are given. A monopolist may find it most profitable to offer the goods only as a bundle, even if they are (imperfect) substitutes, or to not bundle the goods, even if they are complements. If one good is competitively sold, a monopoly producer of the other good can never increase profits by offering his good only as part of a bundle. However, such a monopolist might profitably offer his good in both bundled and unbundled form to price discriminate, even if the two goods are substitutes.     

Supply chain scheduling and coordination with dual delivery modes and inventory storage cost

We study a two-echelon supply chain scheduling problem in which a manufacturer acquires supplies from an upstream supplier and processes orders from the downstream retailers. The supply chain sells a single short-life product in a single season. We consider the scenario where the manufacturer can only accept some of the orders from the retailers due to its supplier's common production time window and its own two common production and delivery time windows. The upstream supplier processes materials and delivers the semi-finished products to the manufacturer within its time window. Then the manufacturer further processes these products to produce finished products and delivers them to the retailers within its two time windows, where one window is for production and normal delivery, and the other is for production and express delivery. Having to store the materials before processing them, the supplier incurs a storage cost, which depends on the order size and storage time. The manufacturer pays the transportation cost for delivering the finished products to the retailers. Due to double marginalization, the performance of the supply chain is sub-optimal. We model the supply chain problem as a flow shop scheduling problem with multiple common time windows. We derive some dominance properties and establish some theorems that help solve the sequencing problems for the orders and eliminate the idle time among the orders. Based on these results, we develop fast pseudo-polynomial dynamic algorithms to optimally solve the problem. We prove that the problem is NP-hard in the ordinary sense only. We develop two practically relevant and robust methods for the supply chain to achieve optimal profit-making performance through channel coordination.     

Measuring the convexity of the cost function

In this paper I argue that, as might be expected, the initial assumption made about the cost function will influence the empirical results obtained regarding the convexity. I show that this expectation is supported empirically by estimating the parameters of two quadratic cost functions. The first is that function which has been traditionally used in the literature. The second is a simplified version of the quadratic cost function where the cost of changing the level of output is dropped since the evidence in the literature suggest that this variable has no significant effect on cost. Using physical product monthly data for 24 industries we find that the conclusion reached regarding the convexity of the cost function depends on the assumption we make regarding the cost function. I further find that the simplified function is consistent with the observed behavior of production and sales while the traditional cost function is inconsistent with that behavior.     

Julia例外函数集的一些性质

本文从正规簇理论出发,证明了1919年由 Julia 定义的 Julia 例外函数,与1926年由 Ostrowski 定义的 Julia 例外函数的等价性,并用 Ostrowski 的定义,证明了 Julia 例外函数集 J,对普通函数的加法和乘法,构成一个交换域,并且 J 中一致球面收敛函数列的极限,也是 Julia 例外函数。