Learning and forgetting effects on a group scheduling problem

This paper proposes to investigate learning and forgetting effects on the problem of scheduling families of jobs on a single machine to minimize total completion time of jobs. A setup time is incurred whenever the single machine transfers job processing from a family to another family. To analyze the impact of learning and forgetting on this group scheduling problem, we structure three basic models and make some comparisons through computational experiments. The three models, including no forgetting, total forgetting and partial forgetting, assume that the processing time of a job is dependent on its position in a schedule. Some scheduling rules and a lower bound are derived in order to constitute our branch-and-bound algorithm for searching an optimal sequence. In addition, an efficient and simply-structured heuristic is also built to find a near-optimal schedule.     

Local times of continuous N-parameter strong martingales

Let M be a 4N-integrable, real-valued continuous N-parameter strong martingale. By extending Itô-type formulas for M to a function whose 2Nth derivative is Dirac's δ-distribution, Tanaka-type formulas for M are obtained. They represent local time of M with respect to occupation time scaled by the N-fold product of the Stieltjes measure defined by the quadratic variation of M and its kth derivatives in space, where k ≤ N − 1. Applications of Doob's and Burkholder's inequalities give continuity properties: space time continuity for local time, space continuity for the derivatives. In case N is even, for the continuity of the (N − 1)st derivative an additional condition on M is needed which may have a relation to the existence of local times of M w.r.t. different occupation time scales.     

不同运动负荷对中学生注意集中性影响的实验研究

以16名中学生为研究对象,采用文献资料法、数理统计法和实验法（EP701C——注意力集中测试仪）等多种研究方法,对不同运动负荷对注意集中性进行实验研究。结果显示：安静状态和小、中、大3种运动负荷状态对注意集中性有显著影响,其中,中运动负荷和大运动负荷对注意集中性的影响最为显著,大负荷使“在靶时间”减少而“脱靶次数”增加。     

浙江高等教育的近代变迁

１９世纪末到２０世纪中叶浙江的高等教育变迁经历了发端、发展、提高三个阶段。发端期约在１８９７－１９０３年间，以求是、育英两所新式书院的创办为起点；发展期约在１９０４－１９２６年间，以《癸卯学制》的颁布实施为起点，各种高等专科学校迅速发展，形成了以高等专科学校为主的办学格局；提高期约在１９２７－１９４９年间，以国立浙江大学的创办为起点，经过２０余年的变迁，逐步形成了包含综合性大学、学院、专科学校的多样化格局，并在全国高等教育事业中占有了重要地位。     

Dependence properties and comparison results for Lévy processes

In this paper we investigate dependence properties and comparison results for multidimensional Lévy processes. In particular we address the questions, whether or not dependence properties and orderings of the copulas of the distributions of a Lévy process can be characterized by corresponding properties of the Lévy copula, a concept which has been introduced recently in Cont and Tankov (Financial modelling with jump processes. Chapman & Hall/CRC, Boca Raton, 2004) and Kallsen and Tankov (J Multivariate Anal 97:1551–1572, 2006). It turns out that association, positive orthant dependence and positive supermodular dependence of Lévy processes can be characterized in terms of the Lévy measure as well as in terms of the Lévy copula. As far as comparisons of Lévy processes are concerned we consider the supermodular and the concordance order and characterize them by orders of the Lévy measures and by orders of the Lévy copulas, respectively. An example is given that the Lévy copula does not determine dependence concepts like multivariate total positivity of order 2 or conditionally increasing in sequence. Besides these general results we specialize our findings for subfamilies of Lévy processes. The last section contains some applications in finance and insurance like comparison statements for ruin times, ruin probabilities and option prices which extends the current literature. Anja Blatter was supported by the Deutsche Forschungsgemeinschaft (DFG).     

Single-machine scheduling against due dates with past-sequence-dependent setup times

Recently Koulamas and Kyparisis [Koulamas, C., Kyparisis, G.J., in press. Single-machine scheduling with past-sequence-dependent setup times. European Journal of Operational Research] introduced past-sequence-dependent setup times to scheduling problems. This means that the setup time of a job is proportionate to the sum of processing times of the jobs already scheduled. Koulamas and Kyparisis [Koulamas, C., Kyparisis, G.J., in press. Single-machine scheduling with past-sequence-dependent setup times. European Journal of Operational Research] were able to show for a number of single-machine scheduling problems with completion time goals that they remain polynomially solvable. In this paper we extend the analysis to problems with due dates. We demonstrated that some problems remain polynomially solvable. However, for some other problems well-known polynomially solution approaches do not guarantee optimality any longer. Consequently we concentrated on finding polynomially solvable special cases.     

Optimal sequencing in the presence of setup times for tow/barge traffic through a river lock

Queues of tow/barges form when a river lock is rendered inoperable due to lock malfunction, a tow/barge accident or adverse lock operating conditions. In this paper, we develop model formulations that allow the queue to be cleared using a number of differing objectives. Of particular interest is the presence of different setup times between successive passages of tow/barges through the lock. Dependent on the objective chosen, we are able to show that certain ordering protocols may be used to markedly reduce the sequencing search space for N tow/barges from the order of N! to 2^N. We present accompanying linear and nonlinear integer programming formulations and carry out computational experiments on a representative set of problems.     

谈私家车尾部提示语的语言艺术

私家车尾部提示语是指贴在私家车后风挡玻璃上用简短文字写出的词语或句子。其作用是警告、提示后车驾驶人保持安全车速、车距,防止刮碰或追尾。这些提示语或构思巧妙,或幽默诙谐,或礼貌温情,或短小精悍,在一定程度上起到了制止不文明交通行为的作用。它是都市生活中一种独特的语言艺术表达方式。     

Theoretical assessment of the errors involved in ultrasonic location and sizing of molten weld pools

Ultrasonic transit times may be used to locate the interface between molten weld metal and parent plate as a weld is formed. These transit times will lead to errors in interpretation of the location of the weld interface if account is not taken of the variation of ultrasonic velocity with temperature. We assess the magnitude of these errors using a theoretical model based on the Green's function to obtain the temperature distribution at any time and then convert the temperatures into elastic constants through empirical fits to high temperature data. A ray tracing method and a semi-analytical approach are used to estimate the effects of the changes in elastic constants on the ray paths and transit times. From these theoretical predictions we conclude that the location errors incurred by assuming ultrasonic velocities appropriate to cold metal are less than 0.5 mm for a 3.5 mm radius weld in austenitic steel or in iron. Experimental values tend to be larger than this, possibly suggesting that the solid-liquid interface is not as perfect as in the theoretical model. Under all of the conditions investigated, predicted errors are smaller with compression waves than with shear waves.     

近代以来自然科学发展视域下的上帝观变迁--从终极因到终极关怀

近代以来,自然科学的发展在很大程度上影响了上帝观的变迁。从唯理论、自然神论的上帝观,到康德、施莱尔马赫的上帝观,最后到西美尔和蒂里希的上帝观,上帝观经历了从终极因到终级关怀的理论转变。