Efficiency determinants of container terminals in Latin American and the Caribbean

Extensive use of containerized cargo has caused technological changes in the maritime industry and consequently port transformations. To face these new challenges, port reform processes were designed, coming to Latin America in the 90s. The main objectives were the modernization of ports and the promotion of competition and efficiency. However, there still seems to be potential for improving port efficiency. To assess the potential of this margin, this article analyses the evolution of the efficiency of the main container terminals in Latin America and the Caribbean, and determinants of inefficiency. One question this paper seeks to answer is whether increases in efficiency resulting from port modernization subsequent to reforms in Latin America and the Caribbean have been maintained over time. In addition, and in order to contribute to the definition of economic policies, the main objective of this paper is to analyse the factors that are currently influencing container ports inefficiency – specifically inter-port and intra-port competition. The estimation of a Stochastic Production Frontier shows an average level of technical efficiency of 83% in the 2000–2010 period, and a technological change of 5%. These results show that port efficiency has evolved positively, although affected by the economic crisis. Our findings also indicate that container terminals located in Mercosur countries, and ports with three or four container terminals, are the most efficient, and that transhipment ports are less efficient than other type of ports. According to our findings, LAC decision-makers should consider promoting inter-port competition and strengthening intra-port competition.     

Review of Recent Advances in Non-invasive, Flexi-ble, Wearable Sweat Monitoring Sensors

Wearable health-monitoring devices are novel and integral developments based on smart-textiles. Conventional wearable technology consists of micro-controllers and a variety of electronic devices embedded on the skin, or in-corporated into the apparels, where they act as signal receptors, analytical devices and transmitters of the signals generated from the human body. Invasive methods are currently more commonly practiced where biofluids are obtained by penetrating the body by incision or injection, while in non-invasive methods no such penetrations take place. A critical review of current non-invasive wearable technology, including colorimetric, enzymatic, pH based, electrochemical and conductivity sensors, is presented in this paper along with the challenges and limitations they pose. Additionally, novel techniques of analysis have been explored concluding that a textile-based medium offers higher compatibility for in-tegration of such sensors in comparison to other existing substrates.     

选厂石灰添加自动控制系统的研究

在选厂人工添加石灰不能很好满足浮选工艺要求的前提下，研究了石灰添加自动控制系统。从石灰添加到矿浆pH值的稳定，滞后时间长，控制难度大。选用采样控制器，解决了滞后时间长的问题，获得较好的控制效果，满足了浮选工艺的要求。     

地下采场围岩刚度与强度参数的正交反演方法

应用正交试验设计原理，提出了一种根据地下采场围岩的量测位移，反演确定其刚度参数和强度参数的弹塑性正交反演方法。运用这种方法．并借助于连续介质快速拉格朗日分析技术，反演确定了湖南湘西金矿充填料矿二次回采采场围岩的刚度参数与强度参数，从而为进一步应用数值模拟技术进行采矿方法安全性评价打下了基础。     

Alternative Multi-level Continuous Sampling Plans

In this paper we consider certain continuous sampling plans for which the rules concerning partial inspection depend, in part, on the length of time it takes to decide that the process quality is good enough so that 100% inspection may be suspended (e.g. the time required to find i consecutive items free of defects). These plans are shown to be identical to various existing multi-level continuous plans with respect to many mathematical characterizations. In certain cases these plans may be more desirable or easier to administer in practice.     

A Bayes Sampling Allocation Scheme for Stratified Finite Populations With Hyperbinomial Prior Distributions

When sampling is carried out independently for the K strata of a finite stratified dichotomous population (defectives vs. standard items), and the number Z_i of defectives per stratum sample is observed, the corresponding probability function for X = (X_i , …, x_K ) is the product of hypergeometric functions which depend on the sample sizes n_i , the stratum sizes N_i , and the number of defectives M_i in the stratum (i = 1, …, K). It is assumed that prior information is available about the M_i 's which can be expressed, by suitable choice of the parameters a_i and b_i , as the product of independent hyperbinomial functions.

In each stratum the cost per observation is a known constant. Using squared error loss function, the prior Bayes risk is found for the linear function of interest,

and the optimum allocation of sample sizes is found, the one for which the prior Bayes risk is minimum when the total sampling budget is fixed.     

浅谈现行纺织材料回潮率测定标准的异同

从恒重定义、试验环境、取样、烘验温度与烘验时间、结果计算与数值修约5个方面比较分析了纺织材料回潮率不同测定标准的异同,根据实际提出建议,为企业和相关检测机构提供参考。     

Deviation model based method of planning accuracy inspection of free-form surfaces using CMMs

Measurements of free-form surfaces are performed with the use of numerically controlled CMMs on the basis of a CAD model, which results in obtaining coordinates of discrete measurement points. The local geometric deviation, i.e. the distance of a particular measurement point from the CAD model of the nominal surface, is established for each point. The measurement aims at evaluating the form deviation and thus the greatest deviation of the actual surface from the CAD model. An effective measurement is one in which the probability of locating the greatest deviation is highest with the smallest possible number of measurement points. The present article suggests a method of planning a measurement strategy for objects with free-form surfaces. Repeatability of deterministic deviations on surfaces processed under the same conditions was applied. A CAD model of the product, built on the measurement points, and including the deterministic component of these deviations, was constructed. Effective surface measurements were planned locating the measurement points in the critical areas. The devised model was used for performing the measurement.     

田湾核电厂址事故后果评价中天气取样方案的比较研究

本文基于田湾核电厂址1998年9月1日至1999年8月31日一整年的逐时气象数据、SF6实测扩散参数和评价区(40km×40km)各网格(2km×2km)人口分布等实测资料,对依据秦山、田湾核电厂址和惠安拟选核电厂址多年逐时气象数据统计分析后提出的五个天气取样候选方案,估算了某假想事故在评价区内造成的集体剂量,得到事故集体剂量余补累积概率分布函数(即CCFD曲线)。同时应用整年“逐时滑移”事故释放起始时刻方法计算了事故集体剂量的CCFD曲线,即“标准”CCFD曲线,并将五类天气取样候选方案获得的95%累积概率水平事故集体剂量值与由“标准”CCFD曲线得到的相应值作比较。结果表明,天气取样候选方案四最佳,此方案给出的95%累积概率水平事故集体剂量与由“标准”CCFD曲线得到的相应值的相对偏差仅为3%。     

Bed-Shear Stress Characteristics of a Simple, Prismatic, Rectangular Channel

This paper examines the use of data obtained from large eddy simulations in exploring the instantaneous characteristics of boundary shear stress. The probability density functions (PDF) of the shear stress are shown to be non-Gaussian, whereas the PDF of the shear force per unit length is found to be approximately Gaussian. Conditional sampling is used in order to provide an insight into the average behavior of an extreme shear stress event. Finally, proper orthogonal decomposition illustrates that the behavior of the shear stress is complex and cannot necessarily be attributed to a single major flow event.