Dynamic cell fractionation and transportation using moving dielectrophoresis

This study presents a new cell manipulation method using a moving dielectrophoretic force to transport or fractionate cells along a microfluidic channel. The proposed moving dielectrophoresis (mDEP) is generated by sequentially energizing a single electrode or an array of electrodes to form an electric field that moves cells continuously along the microchannel. Cell fractionation is controlled by the applied electrical frequency, and cell transportation is controlled by the interelectrode activation time. The applicability of this method was demonstrated to simultaneously fractionate and transport Saccharomyces cerevisiae yeast cells, both viable and nonviable, by operating at conditions under which the cells were subjected to positive and negative dielectrophoresis, respectively. Compared to the conventional dielectrophoresis (cDEP and traveling wave dielectrophoresis (twDEP), moving dielectrophoresis allows cells to be separated on the basis of the real part of the Clausius-Mossotti factor, as in cDEP, but yet allows the direct transportation of separated cells without using fluid flow, as in twDEP. This dielectrophoresis technique provides a new way to manipulate cells and can be readily implemented on programmable multielectrode devices.     

Risk assessment in maritime transportation

A review is presented of different approaches to quantify the risk in maritime transportation. The discussion of several accident statistics provides a global assessment of the risk levels and its differentiation in ship types and main types of ship losses. Early studies in the probability of ship loss by foundering and capsizing are reviewed. The approaches used to assess the risk of structural design are addressed. Finally a brief account is given of recent development of using formal safety assessments to support decision making on legislation applicable internationally to maritime transportation.     

Release criteria from hospitals of 131I thyrotoxicosis therapy patients in developing countries--case study

The current release limit, recommended by the International Atomic Energy Agency (IAEA)(1), from hospitals of patients undergoing 131I thyrotoxicosis therapy is approximately 1100 MBq (approximately 30 mCi). Owing to the difference in socio-economic conditions, literacy rate, family system, etc., this release limit may not be applicable in most of the developing countries like Pakistan. Therefore, the prime objective of this case study was to re-evaluate the release criteria for 131I thyrotoxicosis therapy patients by taking into account their lifestyle, economic conditions and other facilities such as availability of private/public transport, etc. In this context, systematic studies were carried out and 50 patients (i.e. 35 outpatients and 15 inpatients) at the Nuclear Medicine Oncology and Radiotherapy Institute (NORI), Islamabad, were studied. Exposure rate at the surface of the body and at a distance of 1 m from the standing patient was measured. Results obtained from this study showed that the dose equivalent delivered by these patients to their family members (particularly children) and general public was higher than annual dose limits recommended by the International Commission for Radiation Protection in their report ICRP Publication 60(2). In the light of this study, it is recommended that the release activity limit of approximately 370 MBq (or dose rate level of approximately 10 microSv h-1 at 1 m from the patient) be adopted instead of approximately 1100 MBq in developing countries like Pakistan.     

Animal transportation networks

Many group-living animals construct transportation networks of trails, galleries and burrows by modifying the environment to facilitate faster, safer or more efficient movement. Animal transportation networks can have direct influences on the fitness of individuals, whereas the shape and structure of transportation networks can influence community dynamics by facilitating contacts between different individuals and species. In this review, we discuss three key areas in the study of animal transportation networks: the topological properties of networks, network morphogenesis and growth, and the behaviour of network users. We present a brief primer on elements of network theory, and then discuss the different ways in which animal groups deal with the fundamental trade-off between the competing network properties of travel efficiency, robustness and infrastructure cost. We consider how the behaviour of network users can impact network efficiency, and call for studies that integrate both network topology and user behaviour. We finish with a prospectus for future research.     

Decision making in hazardous materials transportation

There are presently countless methods of risk analysis/risk assessment to make effective judgments of the safety of the movement of particular cargoes. Two tools to determine the hazard presented by a large quantity of hazardous materials are the “Equivalent Safety Concept” developed by Danahy and Gathy and the “Population Vulnerability Model” developed by Enviro Control, Inc. The Equivalent Safety Concept is a noncomputer technique that develops indexes for cargo hazard, for vessel design, and port safety. These are used to assist in a judgmental decision of authorization of vessel transit. The Population Vulnerability Model is a computer simulation of a cargo spill integrated with census data. The damage to life and property are calculated using the census data and the cargo properties to determine the number of deaths and injuries to personnel and dollar loss from the cargo release. The results and relative hazards calculated using these techniques are compared and analyzed.     

Efficiency and time-cost-tradeoffs in transportation problems

Summary In this paper we introduce several concepts for solving transportation problems with respect to cost as well as time objective. We claim that the construction of the set of all time-cost-efficient solutions is a powerful help for decision making if its cardinality is not too large. We present methods for constructing the so-called time-cost-trade-off-curve in the case where the time and cost coefficients are prespecified and for the case where transportation time can be reduced if some extra payment is made.

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Zusammenfassung Wir diskutieren Konzepte zur Lösung von Transportproblemen unter Kosten- und Zeitzielfunktion. Die Konstruktion aller Zeit-Kosteneffizienten Lösungen erweist sich dabei als eine wertvolle Entscheidungshilfe wenn deren Anzahl überschaubar ist. Wir geben Methoden zur Konstruktion der sogenannten ZeitKosten-Tradeoff Kurve an für den Fall, daß Zeit- und Kostenwerte fest vorgegeben sind und für den Fall, daß die Transportzeit bei gleichzeitiger Erhöhung der Transportkosten reduziert werden kann.

     

Optimized load planning of trains in intermodal transportation

In this paper the problem of load planning for trains in intermodal container terminals is studied. The objective is to assign load units to wagons of a train such that the utilization of the train is maximized, and setup and transportation costs in the terminal are minimized. Contrary to previous approaches additionally weight restrictions for the wagons are integrated into our model. We present three different integer linear programming formulations and test them on some real-world instances. It is shown that even non-commercial MIP-solvers can solve our models to optimality in reasonable time.     

Problems in the rational analysis of transportation safety

Analysis of air traffic control capacity shows the relation between traffic level and risk can be dealt with quantitatively only if units of risk are specified. Measuring risk in terms of fatalities per hour of exposure solves the major problem of how to compare the effects that many different kinds of risk have upon patterns of human activity, but leaves us with a number of unresolved secondary issues. Among these are : incommensurability of certain risks, failure of statistical independence, certain limitations of time-normalization, unequal distribution of costs and benefits, different weighting of voluntary and involuntary risks, liability, cost and value of uncertainty, positive value of some risks, acceptability of unequal risks, difficulty of estimating very small probabilities and threat of the unknown compared to threat of the known. Although these issues arose out of air traffic control studies, they are clearly relevant to risk analyses of many other systems.     

Error analysis and applications in transportation systems

This paper presents an overview of the field of error analysis. Section 1 shows why discussions about human error are relevant for societal safety. With regard to safety research, it is important to predict abnormal events. At the machine side, reliability studies proved their value, but to predict failures in the human factor has been shown to be very difficult. Therefore, problems in how to define the notion of human error (Section 2) and how to classify different types of error (Section 3) are discussed. Some researchers started to use systematical classifications of human error types based on a recent, hierarchical model of human task performance. The outline of the model is presented. Examples of error analysis studies from the field of transportation research (Section 4) provide some basic suggestions on how to reduce error rates. Some conclusions on error control are given in Section 5. The responsibility of managers and system designers in this respect is strongly emphasized.     

Centralized bundle generation in auction-based collaborative transportation

OR Spectrum - In horizontal collaborations, carriers form coalitions in order to perform parts of their logistics operations jointly. By exchanging transportation requests among each other, they...     

Mass transportation mechanism in electric-biased carbon nanotubes

The mass transportation mechanism in electric-biased carbon nanotubes (CNTs) is investigated experimentally. Except for the widely accepted electromigration mechanism, we find out the thermal effect can also induce the mass transportation in the form of thermomigration or thermal evaporation. Moreover, the convincing in situ transmission electron microscope experiment results show the thermal gradient force overrides the electromigration force in most conditions, according to specific parameters of the CNTs and "cargos". A full analysis on the thermal gradient force and electromigration force imposed on the cargos is given, thus our experimental results are well explained and understood.     

Risks of road transportation in a psychological perspective

Transportation systems in the industrialized world require vast amounts of economic and human resources. Most of the risks associated with these systems are due to the frequent use of private cars. This paper gives a review of the literature and psychological facts which may explain why the individual driver and modern society seem willing to accept higher risks in road transportation than in most other activities. Risky driving behavior may depend on (a) a driver's overestimation of his driving skill in a particular situation, (b) his conscious decision to drive under high risk or (c) his failure to perceive risk in a particular situation. It is pointed out that different means must be used in order to affect a change in these factors, mainly, training programs, the spread of information to change drivers' attitudes towards traffic risks, and environmental design changes to subjective risk. In general, empirical research indicates that greater risks are accepted if some kind of control is experienced in a situation and this is especially applicable to driving. Objective and subjective estimates of the riskiness of different elements inherent in road traffic seem to coincide fairly well with regard to a road's physical characteristics. But objective risks are underestimated in relation to speed, black spots, night driving, and narrow roads. The importance of these factors, and of alcohol intoxication and imitative behaviour for risk taking, is discussed. Comparisons of the estimated risks of different transportation systems and other risk sources are discussed. The attribution of the responsibility for an accident is very important for the risks accepted by a society. If the responsibility can be attributed to individual risk takers, as in car driving, society is willing to accept higher risk levels. Finally, the prevailing within-system perspective on risks in road transportation is contrasted with the more important and difficult global perspective which puts the risks of the road transportation system in a societal context.     

振动激励下颗粒物质系统中的波动与输运

颗粒物质在自然界比比皆是,而且他们与人类的生产(如工业、农业、建筑业等)和生活息息相关.在受到振动激励时,颗粒物质会呈现类似流体的行为,例如波动、对流、隆起、及分层等.自上世纪九十年代,对这类现象的研究逐渐成为热门课题.对这些基本现象的深入研究,对人类认识自然、改造自然均具有极其重要的理论与现实意义,并有重要的应用前景.     

Robust bi-level optimization models in transportation science

Mathematical programmes with equilibrium constraints (MPECs) constitute important modelling tools for network flow problems, as they place 'what-if' analyses in a proper mathematical framework. We consider a class of stochastic MPEC traffic models that explicitly incorporate possible uncertainties in travel costs and demands. In stochastic programming terminology, we consider 'here-and-now' models where decisions must be made before observing the uncertain parameter values and the responses of the network users; the objective is to minimize the expectation of the upper-level objective function. Such a model could, for example, be used to derive a fixed toll pricing scheme that provides the best revenue for a given network over a time period, where variations in traffic conditions and demand elasticities are described by distributions of parameters in the travel time and demand functions.We present new results on the stability of globally optimal solutions to perturbations in the probability distribution, establishing the robustness of the model. We also discuss penalization and discretization algorithms, the latter enabling the use of standard MPEC algorithms, and provide many future research avenues.     

产品运输包装可靠性设计

要在运输过程中保护产品免受破坏,就需对产品进行缓冲包装设计,传统的包装设计方法具有明显的局限性.文中基于包装动力可靠性理论提出了一种新的运输包装设计方法,对运输包装可靠性设计的基本思想、设计流程、目标可靠性确定及可靠性校核等问题作了探讨,并从设计思想、流程等角度对新设计方法与传统设计方法进行比较,得出新设计方法设计出的缓冲包装能更好地保护产品.