基于订单数据分析的共享单车重置调度优化研究

无桩共享单车打破了传统公共自行车基于固定桩点提供骑行服务的限制,但如何重置调度随机分布于整个区域面上的共享单车则成为决策者面临的一大难题,而数据驱动的优化方法则为解决这一问题提供了可能。本文首先通过对居民使用共享单车的订单数据进行深入分析,挖掘用户出行规律,继而界定出区域内共享单车的收车点与放车点;进一步地,借鉴报童模型思想构建放车点单车投放的收益函数,在此基础上建立带取送货的共享单车重置路径规划模型并设计算法进行求解。通过算例测试,本文从重置车辆的最大载重量、单位距离成本、重置车辆里程限制、收车点个数以及收车点所拥有的共享单车数等多角度,为共享单车的重置调度提供有效的决策建议。     

企业所得税诚信纳税单因素分析模型的设计及应用——以山东省外商投资企业为例

外资企业纳税是否诚信将直接影响到我国吸引外资的质量和水平。当前外商投资企业偷逃所得税的情况较为严重,而当前我国关于诚信纳税的理论还不很完善,专门针对所得税诚信纳税的研究更为缺乏。采用规范性分析和实证性分析相结合的方法,以山东省外商投资企业为例进行研究提出所得税诚信纳税单因素分析模型,研究结果表明：在税收弹性大于等于平均税负时企业诚信纳税,诚信纳税度较高;而在税收弹性小于平均税负时企业存在非诚信纳税行为,诚信纳税度较低。     

The Influence of Grandparents in Single‐Mother Families

This article examines whether children living with single mothers benefit when they also live with a grandparent, using data from the 1979 to 2002 waves of the National Longitudinal Survey of Youth merged mother‐child file (N = 6,501). Results indicate that for White children, living with a single mother and a grandparent is associated with increased cognitive stimulation and higher reading recognition scores, compared to living with a single mother alone. For Black children, grandparent coresidence is associated with less cognitive stimulation. Thus, in some instances, living with a grandparent can benefit children, but the pattern of results differs by race.     

Linux操作系统实时性的分析与改进策略

Linux已经成为一个流行的嵌入式操作系统,但在实时应用中有些不足。本文在详细分析Linux实时性的基础上,从双内核结构、定时器的细粒度化、可抢占式内核和实时调度策略等四个方面做了改进,以增强系统的实时性。     

Single,Cohabitating, and Married Mothers’ Time With Children

Utilizing the 2003 and 2004 American Time Use Survey (ATUS), this study examines the relationship between family structure and maternal time with children among 4,309 married mothers and 1,821 single mothers with children less than 13 years of age. Single mothers spend less time with their children than married mothers, though the differences are not large. Marital status and living arrangement differences in time with children largely disappear or single mothers engage in more child care than married mothers after controls for socioeconomic status and other characteristics are introduced. Thus, less maternal time with children appears to be mainly attributable to the disadvantaged social structural location of single mothers rather than different proclivities toward mothering between married and single mothers.     

Multi-phase Algorithms for Throughput Maximization for Real-Time Scheduling

We consider the problem of off-line throughput maximization for job scheduling on one or more machines, where each job has a release time, a deadline and a profit. Most of the versions of the problem discussed here were already treated by Bar-Noy et al. (Proc. 31st ACM STOC, 1999, pp. 622–631; http://www.eng.tau.ac.il/amotz/). Our main contribution is to provide algorithms that do not use linear programming, are simple and much faster than the corresponding ones proposed in Bar-Noy et al. (ibid., 1999), while either having the same quality of approximation or improving it. More precisely, compared to the results of in Bar-Noy et al. (ibid., 1999), our pseudo-polynomial algorithm for multiple unrelated machines and all of our strongly-polynomial algorithms have better performance ratios, all of our algorithms run much faster, are combinatorial in nature and avoid linear programming. Finally, we show that algorithms with better performance ratios than 2 are possible if the stretch factors of the jobs are bounded; a straightforward consequence of this result is an improvement of the ratio of an optimal solution of the integer programming formulation of the JISP2 problem (see Spieksma, Journal of Scheduling, vol. 2, pp. 215–227, 1999) to its linear programming relaxation.     

Preemptive Machine Covering on Parallel Machines

This paper investigates the preemptive parallel machine scheduling to maximize the minimum machine completion time. We first show the off-line version can be solved in O(mn) time for general m-uniform-machine case. Then we study the on-line version. We show that any randomized on-line algorithm must have a competitive ratio m for m-uniform-machine case and ∑_{i = 1}^m1/i for m-identical-machine case. Lastly, we focus on two-uniform-machine case. We present an on-line deterministic algorithm whose competitive ratio matches the lower bound of the on-line problem for every machine speed ratio s≥ 1. We further consider the case that idle time is allowed to be introduced in the procedure of assigning jobs and the objective becomes to maximize the continuous period of time (starting from time zero) when both machines are busy. We present an on-line deterministic algorithm whose competitive ratio matches the lower bound of the problem for every s≥ 1. We show that randomization does not help.     

A dynamic programming approach of finding an optimal broadcast schedule in minimizing total flow time

We study the problem of (off-line) broadcast scheduling in minimizing total flow time and propose a dynamic programming approach to compute an optimal broadcast schedule. Suppose the broadcast server has k pages and the last page request arrives at time n. The optimal schedule can be computed in O(k³(n+k)^k−1) time for the case that the server has a single broadcast channel. For m channels case, i.e., the server can broadcast m different pages at a time where m < k, the optimal schedule can be computed in O(n^k−m) time when k and m are constants. Note that this broadcast scheduling problem is NP-hard when k is a variable and will take O(n^k−m+1) time when k is fixed and m ≥ 1 with the straightforward implementation of the dynamic programming approach. The preliminary version of this paper appeared in Proceedings of the 11th Annual International Computing and Combinatorics Conference as “Off-line Algorithms for Minimizing the Total Flow Time in Broadcast Scheduling”.     

阅读测试中的完成句子题型

文章对清华大学英语水平考试阅读部分的完成句子题型从填几个单词为宜的施考方式这一角度进行了研讨。根据文章的结构和内容,选取各类关键信息加以复述,并从每个复述句中取出三个单词或五个单词,组成A与B两类试题,在四个小班内进行了测试。测试结果应用英语测试法和统计法进行了分析,结果说明取出五个单词的B类试题的难度系数和区分度系数都比取出三个单词的A类试题的小。综合对比A、B两类试题,A类优于B类。     

日本人口的老龄化与看护保险制度的实施

用何种社会养老方式来解决因身体虚弱卧床不起和因疾患导致生活不能自理的老人家庭照料与看护问题 ,是人口老龄化国家所面临的共同问题。日本看护保险制度的实施在解决这个问题上探索出了一条适合自己本国国情之路