Solid Edge:从设计软件到设计工具

从"快速响应"用户,到"快鱼吃慢鱼",随着技术和产业加速发展的态势日趋明显,无论哪个行业都对于速度格外重视,但是"快"真能解决所有问题吗?     

分布式系统中一种负载平衡调整算法的研究

1 前言当前,随着计算机网络技术的高速发展,国内外关于分布式系统的研究逐步形成热点。在研究中,出现了大量成型的分布式系统模型。尽管如此,这些系统的实现手段和效率并不令人满意。目前还没有哪个分布式系统能用非常有效的手段和机制来克服由于分布而引起的问题,包括系统潜在的分布并发处理能力、速     

手机端资源信息服务平台UI设计研究——以“哪个班”为例

"哪个班"是一个优秀的本地幼儿教育资源信息服务平台类APP,主要服务对象为0至12岁幼少儿家长。本文旨在通过调查和分析研究,完成哪个班平台的UI优化设计,达到促进宣传推广、稳定用户群的目的。笔者通过调查研究、体验设计、用户反馈、改良设计等环节初步完成两版UI设计,并通过对比国内外前沿的UI设计实例和学科新方法,找到哪个班平台的UI设计在发展过程中要注意避免的问题,并作为进一步设计开发的指南。     

一种判断交叉物体前后景的方法

在计算机图像处理中,常常会出现两个物体在二维影像中有交叉的现象,当两个物体的灰度比较相似时,通常计算机很难辨别出交叉部分属于哪个物体,从而影响物体图像的分割。文章提出了一种通过检测交叉区域,再用模板相关的方法对交叉区域分割的算法,较好地解决了灰度相近物体图像交叉区域分割问题。     

智造:iOS、Android和Windows 8三大移动系统对比

如果你正打算购买一个智能移动终端,例如智能手机或平板电脑,你一定会在i OS、Android和Windows 8三大移动系统之间有所衡量。按照人们的常识和成见,i OS性能流畅、贵气十足,Android开放性高、更为平民化,而Windows 8则在商务领域仍有优势。但是,我们现在的焦点并不是选购个性化的智能移动终端,而是考虑哪个移动系统更适合"智造"应用,哪个移动系统在运行"智造"应用时更为顺畅、稳定和安全。问题不同,答案是否不同呢?     

智造:iOS、Android和Windows 8三大移动系统对比

如果你正打算购买一个智能移动终端,例如智能手机或平板电脑,你一定会在i OS、Android和Windows 8三大移动系统之间有所衡量。按照人们的常识和成见,i OS性能流畅、贵气十足,Android开放性高、更为平民化,而Windows 8则在商务领域仍有优势。但是,我们现在的焦点并不是选购个性化的智能移动终端,而是考虑哪个移动系统更适合"智造"应用,哪个移动系统在运行"智造"应用时更为顺畅、稳定和安全。问题不同,答案是否不同呢?     

架构师接龙 冯大辉vs.王速瑜

技术发展日新月异,固步自封的架构师必然没有前途。各家公司和网站的架构师们一方面固本守元,同时心系窗外,希望能借鉴其他架构师的经验,来增加自己对于架构和技术的理解。"架构师接龙"栏目,以循环提问的方式,邀请业界知名架构师,请他们提出自己的问题,并可指明希望哪个公司或哪个领域的架构师做出回答。当期作答的架构师,接下来可以提出自己的问题,并指明下一个接龙的人或公司。如此循环往复,希望能为广大架构师和读者带来有益的观点和思考。     

双层问题强化应用的代理优化算法

在现实中测试昂贵双层优化问题解通常需要耗费大量的资源,因此在优化此类问题时常用方法是依靠代理模型预先评估问题解的质量,以此来减少所需要进行的实际测试。这种基于代理模型的优化方法的核心步骤为插值,即以代理函数的评估质量为标准决定采用哪个解进行实际测试。研究人员发现对于此类问题常用的全局优化方法在昂贵问题上的表现低于预期。针对这个问题,本文提出了一种基于代理模型的强化应用的双层优化算法,实验表明它在低预算下与预测值插值优化算法比较具有竞争力,在高预算下保持有全局优化的特性,在不同的双层优化问题上能够实现稳定的优化表现。     

在数学教学中引入算法的几个案例

问题的提出 注重信息技术与数学课程的整合是新数学课程的一个重要理念。当前，高中新教材的必修课程中，不管哪个版本都增加了算法这一内容，就体现出这样一个理念。不过，这个内容都是作为单独一章设置的，内容包括介绍赋值语句、循环语句和条件语句，放在了必修课程靠后的位置。现在大家所关心的问题是，     

分布式系统中断点释放算法

本文讨论了在分布式系统中，以进程通讯关系设置断点和回卷原则，提出了一种断点释放算法－断点最小集合算法，以定时地对断点拷贝整理，并给出了该算法的复杂度。由该算法所得到的断点最小集合能够保证系统中无论哪个节点机发生故障，都能使它们回到一致性状态。     

The orthogonal CNN problem

The online CNN problem had no known competitive algorithms for a long time. Sitters, Stougie and de Paepe showed that there exists a competitive online algorithm for this problem. However, both their algorithm and analysis are quite complicated, and above all, their upper bound for the competitive ratio is 10⁵. In this paper, we examine why this problem seems so difficult. To this end we introduce a nontrivial restriction, orthogonality, against this problem and show that it decreases the competitive ratio dramatically, down to at most 9.     

基于事件的社交网络上的双边偏好稳态规划

在基于事件的社交网络中,一个经典的问题是为用户规划其感兴趣的事件.现有的工作仅仅考虑用户的喜好,仅从用户的角度出发,为其安排尽可能感兴趣的事件来参加.然而,从事件主办者的角度出发,他们亦希望为事件安排的用户尽可能有更大的影响力,用户的可靠性尽可能高,以保障事件能够顺利开展,并取得预期的效果.本质上来说,基于事件的社交网络上的规划问题是一个双向选择的问题,而现有的所有工作均未从用户和事件的双边偏好考虑问题.因此,提出一种双边偏好稳态规划问题来解决这种双向选择问题.该问题首次提出,因此现有工作中未有相关算法可供解决该问题.对比之前只考虑用户偏好的规划,在考虑用户和事件双边偏好时,面临着问题更复杂、约束条件更多的困难.因此,提出两种基础算法和一种改进算法来高效、高质量地解决这个问题,并用大量的实验验证所提出算法的高效性和有效性.     

A roadmap of problem frames research

It has been a decade since Michael Jackson introduced problem frames to the software engineering community. Since then, he has published further work addressing problem frames as well as presenting several keynote addresses. Other authors have researched problem frames, have written about their experiences and have expressed their opinions. It was not until 2004 that an opportunity presented itself for researchers in the field to gather as a community. The first International Workshop on Advances and Applications of Problem Frames (IWAAPF'04) was held at the International Conference on Software Engineering in Edinburgh on 24th May 2004. This event attracted over 30 participants: Jackson delivered a keynote address, researchers presented their work and an expert panel discussed the challenges of problem frames.Featuring in this special issue are two extended papers from the workshop, an invited contribution from Jackson in which he positions problem frames in the context of the software engineering discipline, and this article, where we provide a review of the literature.     

A New Well-Solvable Class of PNS Problems

A manufacturing system consists of operating units which convert their input materials into their output materials. In the problem of designing a process network, we have to find a suitable network of operating units which produces the desired products from the given raw materials. If we consider this process network design problem from a structural point of view, then we obtain a combinatorial optimization problem called the Process Network Synthesis or (PNS) problem. It is known that the PNS problem is NP-complete. Here, a new method is presented to reduce the solution of some more difficult PNS problems to the solution of simpler ones, and using this method, a new well-solvable class of PNS problems is established. Received February 12, 1999; revised October 24, 2000     

On Finding the Maximum Feasible Subsystem of a System of Linear Inequalities

Some methods for finding the maximum feasible subsystems of systems of linear inequalities are considered. The problem of finding the most accurate algorithm in a parametric family of linear classification algorithms is one of the most important problems in machine learning. In order to solve this discrete optimization problem, an exact (combinatorial) algorithm, its approximations (relaxation and greedy combinatorial descent algorithms), and the approximation algorithm are given. The latter consists in replacing the original discrete optimization problem with a nonlinear programming problem by changing from linear inequalities to their sigmoid functions. The initial results of their comparison are presented.     

Algorithmic properties of ciliate sequence alignment

We study the problem of optimally partitioning scrambled genes of stichotrichous ciliates into their relevant functional segments, and of aligning scrambled genes with non-scrambled genes. This problem is significantly more difficult than traditional sequence alignment due to the patterns that occur in the scrambled genes. Here, a formal model is created to capture this problem. Then, the inherent complexity of this problem is discussed using the model. We determine that the problem of determining if there is a solution (an alignment) which achieves some minimum score is NP-complete.     

The regular convex cooperative linear quadratic control problem

In this note we consider the cooperative linear quadratic control problem. That is, the problem where a number of players, all facing a (different) linear quadratic control problem, decide to cooperate in order to optimize their performance. It is well-known, when the performance criteria are positive definite, how one can determine the set of Pareto efficient equilibria for these games. In this note we generalize this result for indefinite criteria.     

On the abstraction method for the container relocation problem

The container relocation problem or the blocks relocation problem is a classic combinatorial optimisation problem that occurs in day-to-day operations for facilities that use block stacking systems. A typical place where this problem arises is a container terminal where containers can be stacked vertically in order to utilise the scarce resource of yard surface, thus at times resulting in the unproductive reshuffling moves for containers stacked above the target container for retrieval. Due to the problem class being NP-hard, a number of studies on this topic propose heuristic approaches to solve this problem. There are a few exact methods (search-based algorithms or mathematical programming) proposed for this problem but the feasible problem size of such methods is quite restricted, limiting their practical significance. In this paper, we propose a new insight into reducing the search space of this problem by the abstraction method. Our main contribution to the existing literature is two-fold: the reduction in the search space by the abstraction method and the bidirectional search using the pattern database. Our computational results confirm that our approach enables instances of a near-practical size to be solved optimally within a reasonable computation time.     

A Generalization of a Lower Bound Technique due to Fredman and Saks

{In a seminal paper of 1989, Fredman and Saks proved lower bounds for some important data-structure problems in the cell probe model. In particular, lower bounds were established on worst-case and amortized operation cost for the union-find problem and the prefix sum problem. The goal of this paper is to turn their proof technique into a general tool that can be applied to different problems and computational models. To this end we define two quantities: Output Variability depends only on the model of computation. It indicates how much variation can be found in the results of a program with certain resource bounds. This measures in some sense the power of a model. Problem Variability characterizes in a similar sense the difficulty of the problem. } Our Main Theorem shows that by comparing a model's output variability to a problem's problem variability, lower bounds on the complexity of solving the problem on the given model may be inferred. The theorem thus shows how to separate the analysis of the model of computation from that of the problem when proving lower bounds. We show how the results of Fredman and Saks fit our framework by computing the output variability of the cell probe model and the problem variability for problems considered in their paper. This allows us to reprove their lower bound results, and slightly extend them. The main purpose of this paper though is to present the generalized technique. Received January 25, 1999; revised July 30, 1999.