哈希函数在搜索引擎构造中的作用

搜索引擎作为一种独特的信息检索方式,在网络盛行的今天得到了广泛应用。文章从搜索引擎的原理,哈希函数在搜索引擎构造中的作用,以及搜索引擎在实现用户检索信息时所发挥的作用3个角度来阐述哈希函数在信息检索中的作用。     

A robust support vector regression model for electric load forecasting

Electric load forecasting is a crucial part of business operations in the energy industry. Various load forecasting methods and techniques have been proposed and tested. With growing concerns about cybersecurity and malicious data manipulations, an emerging topic is to develop robust load forecasting models. In this paper, we propose a robust support vector regression (SVR) model to forecast the electricity demand under data integrity attacks. We first introduce a weight function to calculate the relative importance of each observation in the load history. We then construct a weighted quadratic surface SVR model. Some theoretical properties of the proposed model are derived. Extensive computational experiments are based on the publicly available data from Global Energy Forecasting Competition 2012 and ISO New England. To imitate data integrity attacks, we have deliberately increased or decreased the historical load data. Finally, the computational results demonstrate better accuracy of the proposed robust model over other recently proposed robust models in the load forecasting literature.     

Forecasting of density functions with an application to cross-sectional and intraday returns

This paper is concerned with the forecasting of probability density functions. Density functions are nonnegative and have a constrained integral, and thus do not constitute a vector space. The implementation of established functional time series forecasting methods for such nonlinear data is therefore problematic. Two new methods are developed and compared to two existing methods. The comparison is based on the densities derived from cross-sectional and intraday returns. For such data, one of our new approaches is shown to dominate the existing methods, while the other is comparable to one of the existing approaches.     

一种基于均值量化的小波域自同步数字音频水印算法

提出了一种基于均值量化的小波域自同步数字音频水印算法。该算法是一种盲检测算法,检测时不需要原始音频信号。算法引入了系数均值量化的思想,音频信号进行小波分解后,对其中的低频系数进行均值量化,嵌入水印;并且引入了嵌入同步信号的思想,利用同步信号来定位水印的嵌入位置,以抵抗平移、裁剪等攻击。实验结果表明该算法具有较强的鲁棒性和抗攻击性。     

Non‐parametric Analysis of Gap Times for Multiple Event Data: An Overview

Multiple event data are frequently encountered in medical follow‐up, engineering and other applications when the multiple events are considered as the major outcomes. They may be repetitions of the same event (recurrent events) or may be events of different nature. Times between successive events (gap times) are often of direct interest in these applications. The stochastic‐ordering structure and within‐subject dependence of multiple events generate statistical challenges for analysing such data, including induced dependent censoring and non‐identifiability of marginal distributions. This paper provides an overview of a class of existing non‐parametric estimation methods for gap time distributions for various types of multiple event data, where sampling bias from induced dependent censoring is effectively adjusted. We discuss the statistical issues in gap time analysis, describe the estimation procedures and illustrate the methods with a comparative simulation study and a real application to an AIDS clinical trial. A comprehensive understanding of challenges and available methods for non‐parametric analysis can be useful because there is no existing standard approach to identifying an appropriate gap time method that can be used to address research question of interest. The methods discussed in this review would allow practitioners to effectively handle a variety of real‐world multiple event data.     

试析AI数据分析技术对零售市场终端监测和反馈的作用

近年来,线下零售企业面临着巨大的挑战,零售市场终端监测和反馈更显意义重大,而AI数据分析技术为终端监测和反馈提供了新思路。本文首先阐述了零售众包模式和流程,指出了关键要素,并重点分析终端监测和反馈过程中,AI数据分析技术的具体作用,包括提升监测数据分析效率、节省市场终端监测成本、加强分析结果的可靠性等。最后,对零售企业商业模式的发展策略展开了探讨,以期为优化零售市场终端监测提供启示与借鉴。     

Projection‐Based Inference in Randomised Clinical Trials

Covariate information is often available in randomised clinical trials for each subject prior to treatment assignment and is commonly utilised to make covariate adjustment for baseline characteristics predictive of the outcome in order to increase precision and improve power in the detection of a treatment effect. Motivated by a nonparametric covariance analysis, we study a projection approach to making objective covariate adjustment in randomised clinical trials on the basis of two unbiased estimating functions that decouple the outcome and covariate data. The proposed projection approach extends a weighted least‐squares procedure by projecting one of the estimating functions onto the linear subspace spanned by the other estimating function that is E‐ancillary for the average treatment effect. Compared with the weighted least‐squares method, the projection method allows for objective inference on the average treatment effect by exploiting the treatment specific covariate–outcome associations. The resulting projection‐based estimator of the average treatment effect is asymptotically efficient when the treatment‐specific working regression models are correctly specified and is asymptotically more efficient than other existing competitors when the treatment‐specific working regression models are misspecified. The proposed projection method is illustrated by an analysis of data from an HIV clinical trial. In a simulation study, we show that the proposed projection method compares favourably with its competitors in finite samples.     

城市生态交通系统评价

基于交通网络、交通体系完善性、交通环境、交通景观和交通文化五个方面提出城市生态交通协同理论体系,以既有的城市交通系统可持续发展评价指标体系为基础,构建了一套城市生态交通评价指标体系。基于BP神经网络建立一个三层的城市生态交通评价模型,选取sigmoid函数作为评价模型的传递函数,traingdx作为训练函数,隐含层单元数确定为16。根据收集到的9个城市生态交通评价指标数据,选取其中5个城市数据作为评价模型的学习样本,建立城市生态交通系统BP神经网络评价模型,并对另外4个城市数据进行一般性检验,验证了BP神经网络在城市生态交通系统评价中的准确性与适用性。     

基于安全散列算法的FPGA加密方法

介绍了一种基于安全散列算法的FPGA加密方法,利用加密型EEPROM可对低成本FPGA芯片加密,可有效防止对FPGA设计的非法拷贝,保护设计者的知识产权。     

50 Years of research on organizing the purchasing function: Do we need any more?

Research on organizing the purchasing function has seen the rise and fall of different topics, for example the buying centre. And although the increasingly strategic role of purchasing still possesses practical challenges to its effective organizational setup, one has to question whether, after 50 years, there really is a need for more research in this specific domain.As starting point to answer the question, 212 articles published since 1962 are reviewed to provide a comprehensive overview of existing insights. Via content analysis, we inductively establish 12 specific research areas dealing with distinct aspects of purchasing organization.Then the need for further research is assessed by combining those findings with relevant business trends that induce practical challenges in each research area and, consequently, also the need for future research. We conclude that almost all research areas will remain relevant in the future, but need an adjustment of their focus.     

基于大数据的计算机网络信息安全防护措施

大数据是基于云计算技术开发的一种集成技术,可以通过分析、计算和处理大量数据信息来实现这些数据的价值。然而,随着大数据时代的到来,现有的计算机网络面临着新的挑战,特别是网络安全问题逐渐浮现,计算机网络带来的安全隐患导致用户个人的隐私受到了威胁,所以有必要加强网络信息安全工作的部署,以尽早遏制这些安全风险,并确保计算机网络的安全运行。     

Internationalization of multi-source feedback systems: a six-country exploratory analysis of 360-degree feedback

In the past few years, few human resource practices have received as much attention as multi-source feedback systems (MSFSs). In the US and Canada, it is estimated that over one-third of organizations are using some form of MSFS and recent surveys show that this practice is still gaining popularity. Concurrently, a substantial amount of literature has focused on the effectiveness of this performance management practice. However, while few would dispute the popularity of MSFS, relatively little has been published on the use of these systems outside North America and thus little is known about their form and effectiveness in international contexts. This paper outlines the results of an international survey of MSFS. Interview data from HR managers and consultants from Argentina, Australia, China, Slovakia, Spain and the UK demonstrate that MSFS are being implemented, in slightly different ways, in each of these six countries. The main challenges in the application of MSFS in these various countries are the communication efforts necessary before and after implementation, and the inherent difficulty in giving and receiving feedback. The results of this study also provide data as to the perceived future of MSFS in each of the countries surveyed.     

The implications of performance feedback research for understanding antisocial work behavior

This paper explores existing performance feedback models and their implications for understanding antisocial behavior at work. We begin with the presentation of a summary model that outlines constructs and relationships common in current feedback models. Then, we discuss what these constructs and relationships suggest about the occurrence of antisocial responses when negative performance feedback is provided. In addition, we use the performance feedback model to identify areas of research that have been ignored in current conceptualizations of antisocial work behavior.     

Trading off learning and performance: Exploration and exploitation at work

Employees are increasingly given control over how they learn, and their choices for training are diverse and varied, yet employees must balance competing demands. On one hand, they are expected to be increasingly efficient in their current job duties – on the other hand, they are expected to develop new skills and competencies that enable them to adapt and respond to changing job demands. Drawing from the organizational learning literature, we propose a model of worker and work characteristics that inform choices between two mindsets related to learning at work. The first mindset is exploration, or the pursuit of learning outside one’s current knowledge domain; the second mindset is exploitation, the refinement/deepening of one’s existing knowledge stock focusing on the task at hand. We further propose that these strategic choices, or trade-offs, influence employee learning and performance in unique ways, with different implications for both routine and adaptive performance. Finally, we incorporate the notions of feedback loops and risk assessments that influence ongoing decisions between exploration and exploitation mindsets. Recommendations for future research and extensions of the theoretical model are also proposed.     

On Two Existing Approaches to Statistical Analysis of Social Media Data

Using social media data for statistical analysis of general population faces commonly two basic obstacles: firstly, social media data are collected for different objects than the population units of interest; secondly, the relevant measures are typically not available directly but need to be extracted by algorithms or machine learning techniques. In this paper, we examine and summarise two existing approaches to statistical analysis based on social media data, which can be discerned in the literature. In the first approach, analysis is applied to the social media data that are organised around the objects directly observed in the data; in the second one, a different analysis is applied to a constructed pseudo survey dataset, aimed to transform the observed social media data to a set of units from the target population. We elaborate systematically the relevant data quality frameworks, exemplify their applications and highlight some typical challenges associated with social media data.     

基于IOS平台的汽车安全驾驶系统

尽管汽车问世已有百余年,驾车体验技术依旧有着明显不足和巨大的改进空间。本文基于现有互联网及云计算技术,结合卫星定位和手机终端设计出一种ISO平台上的车辆故障显示与行驶规范的一体化软件系统;在文中所提出的汽车故障显示系统中,用户可通过智能手机上的故障检测软件发出指令,并经手机蓝牙或USB接口送达汽车故障诊断器。诊断器在通过传感器诊断后,将反馈请求依ISO15031—5协议规定的应用层、数据链路层、物理层等要求转换成相应的信号,再将汽车的诊断信息反馈给智能手机,并进一步通过手机发送给维修站。此外,本文设计的应用软件还具备建议反馈及智能泊车等一系列人性化功能,从而更好提升用户体验。     

Managing multiple forms of employment in the construction sector: implications for HRM

The construction industry is one of the largest and most complex industrial sectors in the UK. The industry's failure to adopt progressive human resource (HR) practices is routinely blamed on the challenges of operating in a fragmented, project‐based environment reliant on subcontracting. This research examines the extent to which existing HR theory accounts for the particular employment context of project‐based organisations operating in volatile markets. Drawing upon case study research from two different divisions within a large contracting firm, this article explores the extent to which different contracting arrangements impinge on attempts to reposition human resource management (HRM) as a strategic function along the business partnering model. Elevating the role of the HR function is found to be difficult to reconcile with the concurrent demands of managing multiple forms of employment arrangements. The research reveals a need for HRM models that account for the specificities of complex, differentiated organisations that operate in multiple environments.     

Evaluating the value of an entrepreneurial city with a spatial hedonic approach: A case study of London

This study assesses the value of a city by using the housing price function with a geographically weighted regression model, including various social, economic, and environmental factors. To assess these values, various specific data scores—such as those related to ethnic groups, green areas, crime rates, education, unemployment rates, number of entrepreneurs, and environmental quality—were considered in a case study of London. The results indicate that some variables such as time to city center and entrepreneurship have a positive impact on the local areas’ value in London, as shown by housing prices, while those related to unemployment have a negative impact. Moreover, although the London city center has benefitted more in terms of value than its outskirts have, a few specific policies related to startups and entrepreneurship have succeeded in connecting these areas to existing companies and entrepreneurs. In general, large cities may be better equipped to promote such startup and entrepreneurship policies under local industry plans for future development.     

网络时代高校图书馆教育职能的转变与创新

从高等教育学的角度,明确高等学校图书馆教育职能的内涵,分析了网络时代高校图书馆面临的机遇与挑战,并讨论了教育职能转变与创新的基本条件与内容,提出了构建基于学科馆员制的高校图书馆教育网络平台的展望。     

Estimation of the change point of a distribution based on the number of failed test items

This paper discusses the family of life distributions with failure rate functions which decrease initially until a change point and remain constant thereafter. The paper focuses on the estimation for the change point of the failure rate function. While point estimation of the change point of the failure rate function has been discussed by some authors, one can hardly find any existing work on the interval estimation of the change point. In this paper, a method for constructing approximate confidence intervals for the change point is proposed. The proposed approximate confidence intervals are based on the number of failed test items at or before a fixed inspection time. Received: September 1999