基于购物网站用户搜索日志的商品词发现

商品词是电子商务领域描述商品的新词。主要介绍基于购物网站用户搜索日志的商品词发现的方法。该方法从搜索日志中提取用户查询,对查询进行分词,采用N元递增分步算法和串频统计,计算候选串的条件概率,选择候选商品词。为了降低人工审核的成本,只对产出商品词的准确率进行评价。利用该方法在手机、面霜和香水三类商品的搜索日志上进行了实验,最高准确率达到92.58%。     

Computing integrals over polynomially defined regions and their boundaries in 2 and 3 dimensions

We use the cylindrical algebraic decomposition algorithms implemented in Mathematica to produce procedures to analytically compute integrals over polynomially defined regions and their boundaries in two and three dimensions. Using these results, we can implement the divergence theorem in three dimensions or the Green's theorems in two dimensions. These theorems are of central importance in the applications of multidimensional integration. They also provide a strong correctness test for the implementation of our results in a computer algebra system. The resulting software can solve many of the two and some of the three dimensional integration problems in vector calculus textbooks. The three dimensional results are being extended. The results in this paper are being included in an automated student assistant for vector calculus.     

A new homotopy perturbation method for solving systems of partial differential equations

In this paper, a new homotopy perturbation method (NHPM) is introduced for obtaining solutions of systems of non-linear partial differential equations. Theoretical considerations are discussed. To illustrate the capability and reliability of the method three examples are provided. Comparison of the results of applying NHPM with those of applying HPM reveal the effectiveness and convenience of the new technique.     

Effect of La2CuO4 electrode area on potentiometric NOx sensor response and its implications on sensing mechanism

The intent of this work is to look at the effects of varying the La₂CuO₄ electrode area and the asymmetry between the sensing and counter electrode in a solid state potentiometric sensor with respect to NO_x sensitivity. NO₂ sensitivity was observed at 500-600 °C with a maximum sensitivity of ∼22 mV/decade [NO₂] observed at 500 °C for the sensor with a La₂CuO₄ electrode area of ∼30 mm². The relationship between NO₂ sensitivity and area is nearly parabolic at 500 °C, decreases linearly with increasing electrode area at 600 °C, and was a mixture of parabolic and linear behavior 550 °C. NO sensitivity varied non-linearly with electrode area with a minima (maximum sensitivity) of ∼−22 mV/decade [NO] at 450 °C for the sensor with a La₂CuO₄ electrode area of 16 mm². The behavior at 400 °C was similar to that of 450 °C, but with smaller sensitivities due to a saturation effect. At 500 °C, NO sensitivity decreases linearly with area.We also used electrochemical impedance spectroscopy (EIS) to investigate the electrochemical processes that are affected when the sensing electrode area is changed. Changes in impedance with exposure to NO_x were attributed to either changes in La₂CuO₄ conductivity due to gas adsorption (high frequency impedance) or electrocatalysis occurring at the electrode/electrolyte interface (total electrode impedance). NO₂ caused a decrease in high frequency impedance while NO caused an increase. In contrast, NO₂ and NO both caused a decrease in the total electrode impedance. The effect of area on both the potentiometric and impedance responses show relationships that can be explained through the mechanistic contributions included in differential electrode equilibria.     

ARMAX modelling of international tourism demand

Box–Jenkins (1970) models are often used to capture the autoregressive moving average of past observations of tourist arrivals from Japan to Taiwan and New Zealand. However, other explanatory variables, such as real income in the origin country, have also affected the demand for international travel. The purpose of this paper is to use the ARMAX model to investigate the dynamic relationship between tourism demand and real income of Japan, and to compare the findings with the single-equation model. Unit root tests and diagnostics are performed before estimating the income elasticity of travel demand by Japan for New Zealand and Taiwan based on seasonally unadjusted quarterly data for 1980(1) to 2004(2). The empirical results of the ARMAX model support the economic theory that the demand for international travel is positively related to income of the origin country.     

美术馆计算机信息网络系统设计

利用当今主流的组网技术、网络安全技术、主机技术及存储备份技术,结合以应用为导向的设计思想,对某市美术馆计算机信息网络系统进行了方案设计。整个设计采用分功能区模块化的设计方法,具有贯穿整体的集成性、扩展性、兼容性。     

基于高斯混合模型的无线局域网定位算法

目标定位是无线局域网提供位置服务的基础。该文围绕无线局域网目标定位中的定位精度和实时性2个QoS指标,对基于RSSI的定位技术进行研究,提出一种基于高斯混合模型的无线局域网定位算法。该算法由离线训练和在线定位2个阶段组成,采用GMM对RSSI进行建模,降低了系统定位误差,并减少了定位阶段的运算量,提高了定位的实时性。仿真实验结果表明,该算法具有较好的定位精度和实时性。     

基于移动终端的WLAN快速切换方案

移动终端在AP间切换产生的时延和抖动严重影响实时业务的质量。通过分析移动终端切换的过程和现有的改进方案,提出一种基于动态域值的扫描触发机制,有效地避免移动终端在静止和AP信号较好条件下的cache更新。在STA上实现基于动态域值触发扫描的分片cache的更新算法,该算法在保证cache及时更新的同时降低每次更新cache的开销且能有效减小切换时延。     

数字湖南农业信息化建设关键策略探索

本文针对湖南省作为国家农村农业信息化试点省份的建设需求为导向,以湖南农业农村信息化项目实施过程中多次基层调研分析为基础,阐述新农村建设在数字湖南中的重要地位,提出以农村政务、医务、商务、物联网应用为纵,农业云服务平台为横,把农村的社会管理、农村电子商务、农村医疗服务、农业物联网等经过资源整合,以互联网的方式构建一个为“三农”提供政务、医务、商务、物联网服务于一体的“四纵一横”综合平台,解决农村基层社会管理、农村民生服务问题,推进湖南的数字化新农村建设。     

数列极限在实际中的应用

数列极限是一类重要的极限,在经济和数学领域中发挥着重要的作用。以举例的方式介绍数列极限在现实生活中的应用,包括几何中计算曲线所围图形的面积．求二次方程的数值解,购房按揭贷款分期还款问题,及连续复利问题。