企业需求预测准确性存在的问题及其应对策略(一)

鉴于需求预测在企业经营活动中具有重要地位,且会受到受各种因素影响,本文在对企业实际需求预测的方法、过程、系统、管理等问题进行梳理和分析的基础上,指出了通过优化需求预测方法、完善需求预测系统、改进需求预测管理,可有效控制需求预测和未来市场情况的偏差,从而持续提高需求预测的准确性,促进企业生产、销售的良性运行。     

Variable neighbourhood simulated annealing algorithm for capacitated vehicle routing problems

This article presents the variable neighbourhood simulated annealing (VNSA) algorithm, a variant of the variable neighbourhood search (VNS) combined with simulated annealing (SA), for efficiently solving capacitated vehicle routing problems (CVRPs). In the new algorithm, the deterministic ‘Move or not’ criterion of the original VNS algorithm regarding the incumbent replacement is replaced by an SA probability, and the neighbourhood shifting of the original VNS (from near to far by k← k+1) is replaced by a neighbourhood shaking procedure following a specified rule. The geographical neighbourhood structure is introduced in constructing the neighbourhood structures for the CVRP of the string model. The proposed algorithm is tested against 39 well-known benchmark CVRP instances of different scales (small/middle, large, very large). The results show that the VNSA algorithm outperforms most existing algorithms in terms of computational effectiveness and efficiency, showing good performance in solving large and very large CVRPs.     

在镁表面激光熔覆镁铝合金的研究

这项研究用激光熔覆的方法在纯镁基底上获得了三种成分的镁铝非平衡合金,它们在组织组成、各组分相对量、固溶度等诸方面均不同于相应的平衡合金.在富镁合金中和富铝合金的界面上生成了共晶组织,富铝合金中形成了微晶结构.研究表明了工艺参数对显微组织的影响.腐蚀研究表明富铝合金的腐蚀速率比纯镁的低两个数量级.     

Co基合金激光快速熔凝亚稳组织的结构研究

用ＴＥＭ．ＥＡＤＸ及ＸＲＤ分析研究了激光熔敷Ｃｏ基合金的微观结构，表明枝晶组成相是ｆ．ｃ．ｃＣｏ基亚稳固溶体，枝晶间为富Ｃｒ的复杂面心立方Ｍ２３Ｃ６型碳化物和基体相组成的共晶。枝晶二次臂间距为２～３μｍ。在基体相中生成了大量堆垛层错，螺旋形位错和大角度晶界。晶粒尺寸为１０ｎｍ。随激光扫描速度增大，枝晶二次臂间距减小；晶粒尺寸减小；位错密度增大；共晶区范围明显减小；有形成单一亚稳晶体结构的趋势。     

HRTEM study of new series of oxycarbonitrate superconductors (Cu,C,N)Sr2Ca(n - 1)Cu(n)O(y) (n = 1-6)

Arrangements of Cu and anion groups (CO3 and NO3) in the charge-reservoir (CR) blocks of a series of new oxycarbonitrate superconductors (Cu,C,N)Sr2Ca(n - 1)Cu(n)O(y) (n = 1-6) were examined by means of electron diffraction and high-resolution transmission electron microscopy (HRTEM). The first three members with n = 1-3 [Tc = 33 K (n = 1), 91 K (n = 2), 90 K (n = 3)] show the 4a0-type superstructures with periodic arrangements, [-Cu-X-X-X-Cu-X-X-X-Cu-] (X = CO3, NO3), in the CR blocks. The third member (n = 3) partly contains the 2a0-type of superstructure with [-Cu-X-Cu-X-Cu] in the CR blocks. The fourth member with n = 4 (Tc = 113 K) contains only the 2a0-type of superstructure. The higher members, with n = 5 (Tc = 65 K) and n = 6 (Tc = 52 K), show no evidence of ordering in the CR blocks, suggesting random arrangements of Cu and anion groups.     

蓝牙散射网的数据吞吐量分析

文中建立了散射网下数据分组相互干扰的分析模型,在此基础上得出了蓝牙散射网在进行ACL分组传输时的网络吞吐量。针对不同的跳频方式和网络是否全局时隙同步的四种情况对单一类型的分组发送成功率进行了具体的分析,并进一步得出采用混合分组时的网络最大吞吐量,并得出达到最大吞吐量是应当采用的最佳分组。     

产品电磁兼容性标准及整改措施

本文主要论述电磁兼容(EMC)对产品质量的重要性以及国家军用标准对产品电磁兼容的相关要求,通过分析部分产品电磁兼容检测超标原因,探讨如何提高产品电磁兼容性的有效手段.