An empirical study on the influence of pattern roles on change-proneness

Identifying change-prone sections of code can help managers plan and allocate maintenance effort. Design patterns have been used to study change-proneness and are widely believed to support certain kinds of changes, while inhibiting others. Recently, several studies have analyzed recorded changes to classes playing design pattern roles and find that the patterns “folklore” offers a reasonable explanation for the reality: certain pattern roles do seem to be less change-prone than others. We push this analysis on two fronts: first, we deploy W. Pree’s metapatterns, which group patterns purely by structure (rather than intent), and argue that metapatterns are a simpler model to explain recent findings by Di Penta et al. (2008). Second, we study the effect of the size of the classes playing the design pattern and metapattern roles. We find that size explains more of the variance in change-proneness than either design pattern or metapattern roles. We also find that both design pattern and metapattern roles were strong determinants of size. We conclude, therefore, that size appears to be a stronger determinant of change-proneness than either design pattern or metapattern roles, and observed differences in change-proneness between roles might be due to differences in the sizes of the classes playing those roles. The size of a class can be found much more quickly, easily and accurately than its pattern-roles. Thus, while identifying design pattern roles may be important for other reasons, as far as identifying change-prone classes, sheer size might be a better indicator.     

地形对雷达高度计卫星自主导航精度影响分析

以中低轨道卫星为应用背景,对基于星载雷达高度计的卫星自主导航系统展开研究,着重分析了雷达高度计卫星自主导航中的关键因素,即地形起伏对导航精度的影响。根据实际地形的统计特性,并结合导航精度仿真分析的需要,建立了模拟地形的数学模型;对不同地形条件下雷达高度计卫星自主导航系统的导航精度进行了仿真研究,分析了不同的地形条件对雷达高度计卫星自主导航精度的影响。研究的结论对雷达高度计自主导航技术的实际应用将具有重要的参考价值。     

基于S3C2410嵌入式车载定位系统设计

本文从实际应用出发,为嵌入式Linux在车载GPS导航定位系统中的应用研究提供了一种新的设计思路。以ARM处理器S3C2410为硬件核心,在嵌入式Linux操作系统的平台上,基于GPS卫星定位原理,在构建了最小系统的基础上,实现导航定位的功能,设计了LCD显示、GPRS模块等接口电路,完成了车辆定位的系统设计。结合GIS技术创新地运用MiniGUI和MGIS控件,实现了电子地图和定位信息的显示,及车辆实时跟踪和远程监控。     

A combined support vector machine-FCGS classification based on the wavelet transform for Helitrons recognition in C.elegans

Multimedia Tools and Applications - The Helitrons, an important sub-class of the transposable elements (TEs) class II, have been revealed in diverse eukaryotic genomes. They are mobile elements...     

一种基于TMS320 C6713的捷联惯导系统设计

为适应目前捷联惯性导航系统（ SINS）实时性好、速度快、精度高、小型化、低功耗发展需求,设计一种DSP＋FPGA的捷联惯导系统平台,采用FPGA完成传感器数据采集与控制;采用高性能TMS320C6713 DSP为核心处理器完成航姿解算;介绍了FPGA与DSP数据交互关系;DSP程序采用C语言和汇编语言编写,FPGA设计采用VHDL语言描述;实验证明：设计可行,姿态角误差在0.05°范围内,精度符合设计要求。     

基于S3C2410芯片的嵌入式车载GPS定位系统设计

介绍了以三星公司的S3C2410芯片为嵌入式处理器,以嵌入式Linux为操作系统的GPS车载导航系统的设计思想,对硬件的设计和操作系统内核的移植做了详细的说明,最后对G P S接收模块进行了设计。这样的系统设计,性价比高,在车载导航系统中有广泛的应用前景。     

Autonomous navigation during the final ascent of a spacecraft into the geostationary orbit. Autonomous integrated navigation system concept

Journal of Computer and Systems Sciences International - This paper is the first in a series of works devoted to the problems of a spacecraft in the geostationary orbit autonomous operation. The...     

Experimental and numerical study on HDPE/SWCNT nanocomposite elastic properties considering the processing techniques effect

Microsystem Technologies - The aim of this study is to evaluate the elastic properties of high-density polyethylene (HDPE) using single-walled carbon nanotubes (SWCNTs) reinforcements with...     

Effect of physical workload and modality of information presentation on pattern recognition and navigation task performance by high-fit young males

Abstract

Many occupations require both physical exertion and cognitive task performance. Knowledge of any interaction between physical demands and modalities of cognitive task information presentation can provide a basis for optimising performance. This study examined the effect of physical exertion and modality of information presentation on pattern recognition and navigation-related information processing. Results indicated males of equivalent high fitness, between the ages of 18 and 34, rely more on visual cues vs auditory or haptic for pattern recognition when exertion level is high. We found that navigation response time was shorter under low and medium exertion levels as compared to high intensity. Navigation accuracy was lower under high level exertion compared to medium and low levels. In general, findings indicated that use of the haptic modality for cognitive task cueing decreased accuracy in pattern recognition responses.

Practitioner Summary: An examination was conducted on the effect of physical exertion and information presentation modality in pattern recognition and navigation. In occupations requiring information presentation to workers, who are simultaneously performing a physical task, the visual modality appears most effective under high level exertion while haptic cueing degrades performance.     

基于.NET技术动态导航菜单的设计与实现

通过树型菜单,用户可以对资源的结构、类型有直观的了解,但目前很多B/S系统的菜单还是通过代码生成的。为此,基于.NET技术,通过开源项目Peta Poco实现代码,设计并实现了动态导航菜单系统;介绍了数据库设计、算法思想。该技术避免了静态目录树下因数据源经常性改变而频繁修改程序代码的弊端,导航菜单通过数据库进行控制,提高了系统的安全性,使管理变得更加灵活、高效。     

Effects of navigation method on workload and performance in simulated high-speed ship navigation

This study examines mental workload and performance in simulated high-speed ship navigation. Two navigation methods were compared based on an electronic chart display and information system (ECDIS) and a conventional system using paper charts. Twenty naval cadets navigated in high-fidelity simulators through a 50 nautical mile course with varying levels of difficulty. Results showed that ECDIS navigation significantly improved course-keeping performance, but reduced the total amount of communication on the bridge. No differences were observed in subjective workload between groups. Heart rate variability and skin conductance measurements indicated higher workload in conventional navigation, but the differences between groups were not significant.     

交通诱导预测控制仿真研究

将动态交通分配实施过程纳入预测控制框架下以满足实时交通诱导的目的,提出一种交通诱导预测控制算法．该算法是在滚动时域基础上进行的,包括实时交通分配、交通流模拟运行及评价以及进化最佳路径３ 个重要环节．仿真结果表明,交通诱导预测控制是一种良好的计算机控制方法学,其优化过程预先考虑了目前交通分配对未来路网的影响,因而可有效地防范交通拥堵,实现考虑反馈的路网交通流实时分配优化,同时为出行者提供最佳路径．     

组合导航系统在四旋翼无人机上的实现

针对无人飞行器行业的快速发展和导航系统对飞行器的重要性,提出了组合导航系统的融合方案。介绍了捷联惯导系统的原理、姿态算法。通过对惯性传感器进行误差标定和补偿,利用扩展卡尔曼滤波器建立了INS/GPS组合导航系统。仿真实验表明,组合导航系统的工作性能要优于纯惯性导航系统,能够为飞行器提供较高的导航精度。最后,将这种组合导航系统在四旋翼无人飞行器上进行了实现。     

Supporting social navigation on the World Wide Web

This paper discusses a navigation behavior on Internet information services, in particular the World Wide Web, which is characterized by pointing out information using various communication tools. We call this behaviorsocial navigationas it is based on communication and interaction with other users, be it through email, or any other means of communication. Social navigation phenomena are quite common although most current tools (like web browsers or email clients) offer very little support for it. We describe why social navigation is useful and how it can be supported better in future systems. We further describe two prototype systems that, although originally not designed explicitly as tools for social navigation, provide features that are typical for social navigation systems. One of these systems, the Juggler system, is a combination of a textual virtual environment and a web client. The other system is a prototype of a web-hotlist organizer, called Vortex. We use both systems to describe fundamental principles of social navigation systems.     

基于ARM的移动图书导航系统

为改善图书馆繁杂的图书管理工作,在此提出一种基于ARM的移动图书导航终端方案。根据该方案,设计出基于ARM的硬件终端和Qt／Embedded Linux终端导航软件。该导航终端通过获取图书条码或图书题名关键字查询出图书的详细位置信息,为用户提供导航服务。同时,移动导航终端使得图书的寻架与归架简单化,不仅方便了读者而且减少了图书管理人员的工作量。     

浅析基于用户认知语境的个性化导航研究

现代网络的快速发展,使网络上出现了大量的不同形式的信息内容,大量的信息内容通过不同的形式呈现。因此,需要用户自身的习惯偏好和知识环境在信息导航系统中发挥相应的主要作用。从用户个体认知语境作为出发点,通过导航实例对问题进行了深入研究,希望对相关工作人员的工作能够有所帮助。     

Autonomous navigation during the final ascent of a spacecraft into the geostationary orbit. II. Simulation of operation of an integrated autonomous SC navigation and control system

This study continues the series of papers devoted to the approach to solving the problem of autonomous navigation of a spacecraft (SC) in a geostationary orbit at all stages of its lifecycle: final ascent, transfer to the operating longitude, remaining at the operating longitude, removal from the orbit, and burial. In [1], we formulated the concept of autonomous navigation of a spacecraft at the stage of its final ascent to a geostationary orbit. This stage is most complicated from the technical point of view, taking into account the nonlinearity of the applied mathematical models, the influence of uncontrollable factors of various physical nature, and the necessity of the application of promising hardware (electric low-thrust engine, onboard receiver of signals from global navigation satellite systems, intersatellite communication channels, etc.). Taking this into account, the only constructive method for proving the viability and efficiency (taking into account the requirements formulated by the customer who placed the order) of the developed concept of the autonomous navigation at the final ascent stage in the mathematical simulation of this process. The subject of this study is to demonstrate the capabilities of the developed concept of autonomous navigation from the point of view of achieving the required level of reliability and accuracy in solving the navigation problem at the final ascent stage. This demonstration is based on the analysis of the results of imitating the simulation of the process of a spacecraft’s final ascent to a geostationary orbit obtained using the specially developed software complex.     

The influence of spatial resolution enhancement a implied to SSM/I data on pattern recognition

The impact of spatial resolution enhancement on pattern recognition based on SSM/I measurements is evaluated. The instrument ground footprints for the 19, 22 and 37 GHz channels have considerable overlap. An objective technique can be applied to enhance spatial resolution of measurements to the spatial resolution of the 37 GHz channel. The authors utilize a Backus-Gilbert matrix transform approach. Different validation procedures have been performed to demonstrate the effectiveness of the method with the aim to ameliorate the boundary detection on pattern recognition and specially to cloud classification improvement.     

B2C模式电子商务发展的现状与前景分析

本文对B2C模式的各种商务类型进行了评述,分析了当前状况和前景,并且就我国目前B2C模式电子商务发展存在的问题进行了探讨,为此提出了相应的对策.