Shipping Container Logistics and Allocation

A major shipping company in Hong Kong is faced with several logistical and allocation problems. It needs to find a better way to allocate empty containers that are transported from the Middle East to ports in the Far East, subject to vessel schedules and capacities. It needs to know what to do when the supply of empty containers is less than the demand, and it needs to determine the mix of container types that the company should maintain in the long run. To deal with these challenges, a simulation model of the shipping company's operational activities was developed. Heuristic search was employed to identify the policies that yield the lowest operating cost in terms of leasing, storage, pick-up, drop-off and other charges. What makes the problem difficult is that the forecasts of future export movement as well as the demand for empty containers change continually and the company is faced with the possibility of lost sales if containers are not available when requested by customers. This study provided insights that resulted in substantial savings to the shipping company while increasing customers' satisfaction.     

Economic manufacturing quantity,optimum process mean,and economic specification limits setting under the rectifying inspection plan

Economic manufacturing quantity, process mean, and specification limits setting are three important methods for the inventory and quality control problems. In the imperfect production system, we usually consider the manufacturing quantity for reducing the inventory cost, determine the process level for reducing the production cost, and select the specification limits for screening the products. In this paper, we propose the above integrated model based on the application of rectifying inspection plan for obtaining maximum expected total profit of product. The asymmetric quadratic quality loss function is adopted for measuring the product quality. The sensitivity analyses of parameters are provided for illustration.     

Note on Open Problem

After the announcement in the Vol.23, No.4 issue of JMRE, some progress has been made. Profs Giorgio Letta (Pisa) and Luca Pratelli gave a proof without any use of ch.f. of half of the result, as follows:     

Pre-concentration efficiency of chelex-100 resin for heavy metals in seawater : Part 1. Effects of pH and Salts on the Distribution Ratios of Heavy Metals

The chelating characteristics of Chelex-100 resin were studied for selected heavy metals in seawater medium. The results of batch equilibrium and breakthrough experiments show that the metal-chelating efficiency of the resin is lower in seawater than in freshwater. These differences are caused by the complicated speciation of heavy metals in seawater medium and by the high concentrations of magnesium and calcium present which act as competitors to heavy metal ions. The optimal pH values for column operation are strongly affected by the salt matrix. Careful choice of experimental conditions is necessary to avoid losses of cadmium and manganese from seawater. For better performance, seawater samples should be adjusted to pH 6–7 before loading onto a Chelex-100 column.     

Improved Surface Characteristics and Contact Performance of Epitaxial p-AlGaN by a Chemical Treatment Process

The comparative study of epitaxial 380-run-thick p-Al0.091 Ga0.909 N materials without and with special surface chemical treatment is systematically carried out. After the treatment process, the deep level luminous peak in the 10 K photoluminescence spectrum is eliminated due to the decrease of surface nitrogen vacancy VN related defective sites, while the surface root-mean-square roughness in atomic force microscopy measurement is decreased from 0.395nm to 0.229nm by such a surface preparation method. Furthermore, the performance of surface contact with Ni/Au bilayer metal fihns is obviously improved with the reduction of the Schottky barrier height of 55meV. The x-ray photoelectron spectroscopy （XPS） results show a notable surface element content change after the treatment which is considered to be the cause of the above-mentioned surface characteristics improvement.     

三氟醋酸钆的晶体结构

测定了[Gd(CFCOO)_3·3H_2O]_2的晶体结构属单斜晶系,空间群为P2_1/c.Z=2.晶胞参数a=9.192(3),b=18.890(1),c=9.785(3);β=113.84(2)°.[Eu_(0.1)Gd_(0.9)(CF_3COO))3·3H_2O]_2的光谱构分析表明稀土离子周围的局部对称性可能是C_2(C_s)和C_2h。     

Technical improvements in protein microsequencing

Improved techniques for preparing samples and sequencing reagents have been developed to achieve highly sensitive protein sequencing. These improvements include a new sequencing buffer system which gives extremely low chromatographic background, a method for preparing polybrene, a key chemical in gas-phase protein microsequencing, and techniques for preparing protein samples suitable for microsequencing.     

伯胺N1923负离子混合萃取稀土元素

本文测定了 N 1 9 2 3在p H6 的条件下对三价稀土离子的萃取,实验表 明 N 1 9 2 3作 为中性萃取剂配位于稀土原子,并且有较高的萃取率.分别选用三氯醋酸和硫氰酸根作为 阴离子,对 N 192 3作为萃取剂时两个体系的萃取行为、萃合物组成和配位数进行了测定和比较