测量金属导线热导率的新方法

用双臂电桥测量一定温度下铜导线的电阻,进而计算得到铜线的电导率,再根据维德曼-夫兰兹定律得到铜线的热导率.     

A survey of recent research on location-routing problems

The design of distribution systems raises hard combinatorial optimization problems. For instance, facility location problems must be solved at the strategic decision level to place factories and warehouses, while vehicle routes must be built at the tactical or operational levels to supply customers. In fact, location and routing decisions are interdependent and studies have shown that the overall system cost may be excessive if they are tackled separately. The location-routing problem (LRP) integrates the two kinds of decisions. Given a set of potential depots with opening costs, a fleet of identical vehicles and a set of customers with known demands, the classical LRP consists in opening a subset of depots, assigning customers to them and determining vehicle routes, to minimize a total cost including the cost of open depots, the fixed costs of vehicles used, and the total cost of the routes. Since the last comprehensive survey on the LRP, published by Nagy and Salhi (2007), the number of articles devoted to this problem has grown quickly, calling a review of new research works. This paper analyzes the recent literature (72 articles) on the standard LRP and new extensions such as several distribution echelons, multiple objectives or uncertain data. Results of state-of-the-art metaheuristics are also compared on standard sets of instances for the classical LRP, the two-echelon LRP and the truck and trailer problem.     

Computing stable loads for pallets

This paper describes an Integer Programming model for generating stable loading patterns for the Pallet Loading Problem under several stability criteria. The results obtained during evaluation show great improvement in the number of stable patterns in comparison with results reported earlier. Moreover, most of the solved cases also ensure optimality in terms of utilization of a pallet.     

Improved sensitivity of headspace gas chromatography for organic aromatic compounds

Summary The effect of adding an electrolyte and increasing the temperature on the preconcentration of volatile compounds in headspace analysis has been investigated. Quantification of the interactive effects of temperature and addition of salt on the vapor concentration is of interest for the determination of trace organic impurities in pharmaceutical base materials. This study was undertaken to investigate the quantitative effects of the addition of salts alcohols, and acetone, and of increasing the temperature on the vapor concentrations and distribution coefficients of volatile aromatic compounds (benzene, toluene, ando-xylene). It was found that the concentration of aromatic compound residues in the headspace could be increased by adding an inert salt to the water, but this effect was not very significant because of the low orginal solubility of the aromatic compounds in water. The reverse effect can be achieved by use of polar organic additives; this can be explained by the high polarizability of aromatic compounds and their greater solubility in the presence of these solvents. Presented at Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 1–3, 1999.     

Developing an algorithm for compression, multiplexing and enhancement of multiple images

Image compression is one of the important fields that has useful applications in data storage and transmission. In this research a new algorithm is developed and tested for multiple-image compression and enhancement. The algorithm, in addition, is applied to multiple noisy images. Also, the effect of compression ratio on the peak signal to noise ratio (PSNR) is explored by applying different compression ratios. The developed algorithm gives good compression and noise immunity. It can be used for storage/transmission of encrypted and compressed information.     

Interfacial composition, structural parameters and thermodynamic properties of water-in-oil microemulsions

The formation and structural characteristics of water-in-oil microemulsions comprising hexadecylpyridinium chloride (CPC), alkanols (C₄–C₆) and alkanes (C₅, C₈–C₁₀) have been investigated by the method of dilution. The compositions of the surfactant and the cosurfactant in the interfacial region (interphase) of the microemulsion droplets have been determined. The thermodynamics of transfer of the cosurfactants (alkanols) from the continuous oil (alkane) phase to the interface have been evaluated from dilution measurements at different temperatures. The structural parameters, radii of the droplet and the waterpool, aggregation numbers of CPC and the alkanols in the interphase of a droplet, and the nanoparticle density of solution have been estimated assuming monodispersity of the droplets. The thermodynamics and structural parameters have been examined in terms of the chain lengths of the alkanols and alkanes. Received: 12 September 2000 Accepted: 27 October 2000     

Valuation formulae for window barrier options

In this paper we study window barrier options, where a single constant continuously-monitored barrier prevails for a period that commences strictly after the start date of the option and terminates strictly before expiry. We determine valuation formulae within a limited deterministic term-structure in terms of trivariate normal distribution functions. These formulae offer a generalization of the valuation formulae for partial barrier options given by Heynan and Kat.     

Order sequencing on a unidirectional cyclical picking line

A real life order-picking configuration that requires multiple pickers to cyclically move around fixed locations in a single direction is considered. This configuration is not the same, but shows similarities to, unidirectional carousel systems described in literature. The problem of minimising the pickers’ travel distance to pick all orders on this system is a variant of the clustered travelling salesman problem. An integer programming (IP) formulation of this problem cannot be solved in a realistic time frame for real life instances of the problem. A relaxation of this IP formulation is proposed that can be used to determine a lower bound on an optimal solution. It is shown that the solution obtained from this relaxation can always be transformed to a feasible solution for the IP formulation that is, at most, within one pick cycle of the lower bound. The computational results and performance of the proposed methods as well as adapted order sequencing approaches for bidirectional carousel systems from literature are compared to one another by means of real life historical data instances obtained from a retail distribution centre.