Minimizing waiting times in integrated fixed interval timetables by upgrading railway tracks

The integrated fixed interval timetable of a railway network guarantees none waiting times for passengers changing trains. For a periodically served network such a timetable only exists, if and only if the running times of the trains are feasible with a group equation system. If the running times are infeasible with this equation system, there will remain a certain amount of waiting time. A modification of the running times can be achieved by reforming the actual state of certain track segments.In this paper we discuss the cost-benefit between the investigation for reforming track states and the quality of the resulting timetable measured by the remaining waiting times. This leads to a complicated bi-criteria optimization problem. We generate sub-optimal solutions by a hybrid genetic algorithm including fuzzy logic.     

Developing a step-by-step effectiveness assessment model for customer-oriented service organizations

Effectiveness involves more than simple efficiency, which is limited to the production process assessment of peer operational units. Effectiveness incorporates variables that are both controllable (i.e. efficiency) and non-controllable (i.e. perceived quality) by the operational units. It is a fundamental driver for the success of either a for-profit or a non-for-profit unit in a competitive environment that is customer/citizen- and goal-oriented. Additionally, with respect to the short-run production constraints, i.e. the resources available and controllable by the operational units, and the legal status, we go beyond the traditional effectiveness assessment techniques by developing a Modified or “rational” Quality-driven-Efficiency-adjusted Data Envelopment Analysis (MQE-DEA) model. This particular model provides in the short run a feasible effectiveness attainment path for every disqualified unit in order to meet high-perceived quality and high-efficiency standards. By applying the MQE-DEA model a new production equilibrium is determined, which is different from the equilibrium suggested by the mainstream microeconomic theory, in that it takes into account not only the need for operational efficiency but also the customer-driven market dynamics.     

Decision method for the optimal number of logistics service providers with service quality guarantee and revenue fairness

This study investigates the problem that logistics service integrator (LSI) selects the optimal number of its functional logistics service providers (FLSPs) based on the service quality defect guarantee promised by FLSP and the revenue fairness concerns of LSI. This paper introduces a fairness entropy function to establish a new game model for determining the optimal number of FLSPs. Some conclusions about the impact of parameters on the optimal number of FLSPs are proposed with numerical analysis. For example, as the fairness constraints are satisfied, LSI prefers FLSPs who have higher level of business capacity which results a smaller number of FLSPs.     

Developing a mathematical theory of computability which speaks the language of levels

In this paper, we use the modern systems theory to retrace the history of some of the important and interesting philosophical problems. And, based on the discussion, it is shown that the multilevel structure of the nature can be approached by making use of the general systems theory approach started by Mesarovic in the early 1960s. Two difficulties appearing in modern physics are listed, and studied in terms of a new mathematical theory. This theory reflects the characteristic of multilevels of the nature. Some elementary properties of the new theory are listed. Some important and fruitful leads for future research are posed in the final section.     

Some string matching problems from Bioinformatics which still need better solutions

Bioinformatics, the discipline which studies the computational problems arising from molecular biology, poses many interesting problems to the string searching community. We will describe two problems arising from Bioinformatics, their preliminary solutions, and the more general problem that they pose. The first problem is searching for α-helices in protein sequences. This particular instance of the search is based on matching of hydrophobicity/hydrophilicity. We find an algorithm which is linear in the sequence length for fixed helix length and is O(nlogn) for any helix length. The second problem is on matching probabilistic sequences against sequences or against other probabilistic sequences. In both cases we derive efficient formulas to compute scores according to a Markovian model of evolution.     

Convergence of classes of subpramarts and games which become better with time

In this paper local convergence theorems for subpramarts and GBTs (games which become better with time) are presented. These results are also new for Martingales. Global convergence theorems for subpramarts and GBTs are also proved. These theorems are related to the theory of optimal stopping.     

给自己一个更好的职业路径

在IMA（美国管理会计师协会）与中国国家外国专家局（简称外专局）2009年签订战略合作协议后,经过双方共同努力,CMA（美国注册管理会计师认证）资格认证得以在国企和央企迅速铺开,并获得高度认可。2010年10月11日,国资委系统下的200名财务高管,其中许多人都是大型央企的总会计师,将集中参加一个为期一个月的CMA培训班,     

The motion of a railway wheelset

The rolling of a railway wheelset along rails without slipping is investigated taking the creep hypothesis into account. The wheelset is represented by two cones that have a common base, and the rails are represented by two circular cylinders with parallel axes. The kinematic characteristics of the unperturbed rolling motion of the wheelset, which occurs when the centre of mass moves along a straight line, and of the perturbed motion, which occurs when the centre of mass of the wheelset describes a sinusoidal trajectory, are determined. The constraint reactions are found for the motions investigated up to small second-order values of the perturbed variables. When the elastic properties of the material in the contact area are taken into account, the creep hypothesis is used, averaging over the fast variables is employed, and the value of the critical speed, above which the rectilinear rolling of the wheelset becomes unstable, is found using averaged equations. In the latter case a periodic mode with two time intervals when the wheel flanges come into contact with the rails is investigated. The reaction force, the work of the dry friction force, and the moment of the active forces needed to maintain the periodic mode are found at the flange/rail contact point within the dry friction model. The boundaries of the stability regions, the parameters of the periodic mode and the moment of the resistance forces as functions of the problem parameters are determined from the formulae obtained by analytical methods.     

A guarantee as a measure of reliability of polymer structures

The question of a guarantee as a measure of reliability of polymer structures is discussed. The probability that the difference of the values of the strength of structures and limiting load will be greater than zero is taken as the guarantee. It is shown that in the general case the value of the guarantee is a function of time. The general conjectures are illustrated by an example in which the laws of distribution of loads and strength are taken as normal.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 509–513, May–June, 1970.     

More infinity for a better finitism

Elementary Recursive Nonstandard Analysis, in short ERNA, is a constructive system of nonstandard analysis with a PRA consistency proof, proposed in around 1995 by Patrick Suppes and Richard Sommer. It is based on an earlier system developed by Rolando Chuaqui and Patrick Suppes. Here, we discuss the inherent problems and limitations of the classical nonstandard framework and propose a much-needed refinement of ERNA, called ERNA^A, in the spirit of Karel Hrbacek’s stratified set theory. We study the metamathematics of ERNA^A and its extensions. In particular, we consider several transfer principles, both classical and ‘stratified’, which turn out to be related. Finally, we show that the resulting theory allows for a truly general, elegant and elementary treatment of basic analysis.     

Risk assesment of a new high-speed railway

A quantitative risk assessment has been carried out for theconceptual stage of the proposed Channel Tunnel Rail Link (CTRL).The assessment is one of the first for a railway system. Itincludes an integrated computer model. The whole risk modelfor the CTRL from base event data, through fault and event trees,to individual, collective, and societal risks is processed usingLotus 1-2-3 spreadsheets. Variations to the design and operationalassumptions and to the input data can be introduced into themodel, and the effect on risk calculated rapidly. This versatilityis particularly useful because of the early stage of the project.It can be used to assist designers in consideration of possibledesign changes.     

A relaxation algorithm with a probabilistic guarantee for robust deviation optimization

Three measures of robustness (absolute robustness, deviation robustness and relative robustness), whose choice depends on the goals of the decision maker, have been proposed for uncertain optimization problems. Absolute robustness has been thoroughly studied, whereas the others have been studied to less of a degree.     

Heuristics for unequal weight delivery problems with a fixed error guarantee

This paper presents heuristics that are based on optimal partitioning of a travelling salesman tour, for solving the unequal weight delivery problem. The worst case error performance is given as a bound on the worst case ratio of the cost of the heuristic solution to the cost of the optimal solution. A fully polynomial procedure which consists of applying the optimal partitioning to a travelling salesman tour generated by Christofides' heuristic has a worst case error bound of 3.5−3/Q where Q is the capacity limit of the vehicles. When optimal partitioning is applied to an optimal travelling salesman tour, the worst case error bound becomes 3−2/Q.     

On a bulk arrival bulk service infinite service queue

This paper considers an infinite server queue in continuous time in which arrivals are in batches of variable size X and service is provided in groups of fixed size R. We obtain analytical results for the number of busy servers and waiting customers at arbitrary time points. For the number of busy servers, we obtain a recursive relation for the partial binomial moments both in transient and steady states. Special cases are also discussed     

Ramsey families which exclude a graph

For graphsA andB the relationA(B) _r ¹ means that for everyr-coloring of the vertices ofA there is a monochromatic copy ofB inA. Forb (G) is the family of graphs which do not embedG. A familyof graphs is Ramsey if for all graphsBthere is a graphAsuch thatA(B) _r ¹ . The only graphsG for which it is not known whether Forb (G) is Ramsey are graphs which have a cutpoint adjacent to every other vertex except one. In this paper we prove for a large subclass of those graphsG, that Forb (G) does not have the Ramsey property.This research has been supported in part by NSERC grant 69-1325.