一种K值自适应和局部搜索的KNN矩阵修复方法

数据在采集和传输过程中由于多种原因会造成矩阵残缺,因此在数据分析之前需要对残缺矩阵进行修复。常见的KNN修复方法 k值选取不合理,且需在整个矩阵中搜索近邻,影响算法的修复效果。在其基础上提出了一种k值自适应的局部KNN矩阵修复方法,合理考虑了k值的选取和近邻项的搜索范围。实验证明了该方法能有效提高矩阵修复的正确率,且算法的时效性有所提高。     

“Vapor-liquid” equilibrium measurements and modeling for the cyclohexane + n-hexanoic acid binary system

To simulate cyclohexane to cyclohexanol oxidation reactors, the acquisition and modeling of vapor-liquid equilibria of the key components, under the process conditions, are essential. n-Hexanoic acid is a co-product of the reaction. Vapor-liquid equilibrium data are reported for the cyclohexane + n-hexanoic acid binary system at four temperatures: 413, 423, 464 and 484 K. All measurements have been carried out using an apparatus based on the “static-analytic” method, with two ROLSI™ pneumatic capillary samplers. The generated data are successfully correlated using two equations of state, the Peng-Robinson (PR) and the Perturbed Chain Statistical Association Fluid Theory (PC-SAFT). Both models are capable of representing the experimental data, but the PC-SAFT EoS uses less binary interaction parameters.     

GPIB命令的数据结构

针对GPIB命令的结构，提出一种存储GPIB命令的数据结构。根据GPIB命令的层次关系的特点，选择数据结构中“树”的概念来存储GPIB命令结点；并考虑程序实现的效率问题以及管理维护方面的因素，对普通的树进行改造，从而形成特有的“GPIB命令树”，     

用户呼叫数据在移动网络规划中的应用

简要介绍了利用移动网络里的用户呼叫历史记录进行大数据挖掘的方法;通过网络维度对现有2G/3G网络的负荷及忙的区域进行分析;通过用户维度侧重于对网络中的用户终端类型、终端能力、用户分布区域等进行分析;网络维度和用户维度两者相结合的贴近用户的网络价值分析,提高了网络规划和优化的可预见性,为精准化网络建设提供有力支撑。     

Detecting modes of transport from unlabelled positioning sensor data

Global positioning systems (GPS) logs recorded in personal devices contain rich information such as travel patterns, locations of frequent visits and place–event associations. There have been rather successful attempts in detecting the mode of transport from GPS logs such as walking, driving or taking a bus, which has found varied applications. However, the best-known schemes either require tedious manual labelling or pre-training process (or both). We present MoDetect (MD), a unsupervised scheme which eliminates the need of manual labelling and pre-training while attaining equal or greater accuracy compared with the best-known supervised methods. MD can also cater for differences in individual's behaviours, and hence may be more widely applicable than the existing schemes. To achieve this, MD relies on Kolmogorov–Smirnov test which offers a theoretical assurance when computing similarity between segments of records. Our analysis shows that the higher speed modes can be better differentiated through a weighted bootstrapping procedure. We also augment the decisions with reference to the transfer probabilities between different modes at locations identified from the GPS records.     

Enthalpies of Formation of the Tellurites of the Rare Earths Gd, Tb, Dy, Tm and Yb

By using a DSK of the French firm Seteram, the standard enthalpies of formation of 5 tellurites and 5 tetratellurites of the rare earths Gd, Tb, Dy, Tm and Yb were determined for the first time. Three parallel determinations for each sample were compared. The results are very similar, which is an indication of the great reliability of the method used and the correctness of the data obtained. This revised version was published online in July 2006 with corrections to the Cover Date.     

Measurement of multiperiod aggregative efficiency

This article proposes a new method for measuring an aggregative efficiency of multiple period production systems. Every organization or firm generates a time series of data that represent its performances in the resource utilization and output production over multiple periods, and often desires an aggregated measure of efficiency for several periods of interest. Data envelopment analysis (DEA) has become an accepted and well-known approach to evaluating efficiency performance in a wide range of cases. However, most of the DEA studies have dealt primarily with ways to gauge the efficiency of production in only a single period so this efficiency reflects the insufficient or partial performance of multiple period productions. The new method is developed through extensions of the concept of Debreu–Farrell technical efficiency and is applied to evaluating the efficiency of cable TV service units with 3-year data.     

Continuing value in firm valuation by the discounted cash flow model

The discounted cash flow model, like other firm valuation models, proceeds in two periods. For each year in the explicit forecast period, there is an individual forecast of free cash flow. On the other hand, all of the years in the post-horizon period are represented through one single continuing value formula, being the steady-state value of the firm’s productive assets at the horizon. Continuing value is typically derived by applying the Gordon formula to a simple extrapolation of free cash flow at the end of the explicit forecast period. This paper examines the components of continuing value, in particular capital expenditures and tax savings due to depreciation of property, plant and equipment (PPE). The estimation of two somewhat elusive parameters related to capital expenditures, equipment economic life and capital intensity, is discussed. A further analysis indicates that a substantial part of continuing value derives from cash flow associated with already acquired equipment. Also, the error resulting from assuming steady-state rather than lumpy capital expenditures is identified. Implementation issues relating to the explicit forecast period are also commented on.     

A parallel search game

We answer in negative a question of Gál and Miltersen [Proc 30th Int Coll Automata, Languages, and Programming (ICALP) 2003, pp. 332–344] about a combinatorial game arising in the study of time‐space trade‐offs for data structures. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2005