To De or Not to De？

面对是否对 Java 或 NET 程序反编译或反汇编,很多程序员都难以抉择。技术层面上如何处理?选用怎样的工具?怎样防止自己的程序被反编译或反汇编?法律如何约束程序员的知识产权?窥探其他人的程序是否会带来道德上的谴责?本文作者为您一一解答。     

To innovate or not to innovate?

In this paper, we analyze the evolution of output decisions of adaptive firms in an environment of oligopolistic competition. The firm might either choose to produce one of several existing product variants or try to establish a new product variant on the market. The demand for each individual product variant is subject to a life cycle, but aggregate demand for product variants is constant over time. Every period each firm has to decide whether to produce the product again, introduce a new product variant itself (which generates an initial advantage on that market), or follow another firm and change to the production of an already established product. Different firms have heterogeneous abilities to develop products and imitate existing designs; therefore, the effects of the decision whether to imitate existing designs or to innovate differ between firms. We examine the evolution of behavior in this market using an agent-based simulation model. The firms are endowed with simple rules to estimate market potentials and market founding potentials of all firms, including themselves, and make their decisions using a stochastic learning rule. Furthermore, the characteristics of the firms change dynamically due to “learning by doing” effects. The main questions discussed are how the success and the optimal strategy of a firm depend on the interplay between characteristics of the industry and properties of the firm     

Optimal Cache Memory Exploitation for Continuous Media: To Cache or to Prefetch?

Network continuous-media applications are emerging with a great pace. Cache memories have long been recognized as a key resource (along with network bandwidth) whose intelligent exploitation can ensure high performance for such applications. Cache memories exist at the continuous-media servers and their proxy servers in the network. Within a server, cache memories exist in a hierarchy (at the host, the storage-devices, and at intermediate multi-device controllers). Our research is concerned with how to best exploit these resources in the context of continuous media servers and in particular, how to best exploit the available cache memories at the drive, the disk array controller, and the host levels. Our results determine under which circumstances and system configurations it is preferable to devote the available memory to traditional caching (a.k.a. data sharing) techniques as opposed to prefetching techniques. In addition, we show how to configure the available memory for optimal performance and optimal cost. Our results show that prefetching techniques are preferable for small-size caches (such as those expected at the drive level). For very large caches (such as those employed at the host level) caching techniques are preferable. For intermediate cache sizes (such as those at multi-device controllers) a combination of both strategies should be employed.     

Collaboration in Multi-Robot Exploration: To Meet or not to Meet?

Work on coordinated multi-robot exploration often assumes that all areas to be explored are freely accessible. This common assumption does not always hold, especially not in search and rescue missions after a disaster. Doors may be closed or paths blocked detaining robots from continuing their exploration beyond these points and possibly requiring multiple robots to clear them. This paper addresses the issue how to coordinate a multi-robot system to clear blocked paths. We define local collaborations that require robots to collaboratively perform a physical action at a common position. A collaborating robot needs to interrupt its current exploration and move to a different location to collaboratively clear a blocked path. We raise the question when to collaborate and whom to collaborate with. We propose four strategies as to when to collaborate. Two obvious strategies are to collaborate immediately or to postpone any collaborations until only blocked paths are left. The other two strategies make use of heuristics based on building patterns. While no single strategy behaves optimal in all scenarios, we show that the heuristics decrease the time required to explore unknown environments considering blocked paths.     

Optical Measures: A Design Tool to Attain Truth or Illusion?

The optical measures have often been explained within the conceptual framework provided by Vitruvius: the “true” symmetries are distorted by space. Hence they have to be corrected by optical measures under the “real” conditions of appearance. While scholars have studied the phenomenon of optical measures within a narrowly mathematical framework, the aesthetic implications of Vitruvius’ claim, his ambiguous use of the “truth” and “reality” has hardly been noticed. By situating the phenomenon of architectural proportions within the broader aesthetic discourse on Hellenistic art, this paper shall reveal the paradox of discourse between the optical knowledge and professional power of the architect. Rather than being a means to a quintessential truth or reality, the paper shall demonstrate how indeed optical measures were employed as a means to stylistic ends; that the change in the proportions of temple architecture from the Classical to the Hellenistic age predicates a painterly taste.     

To control or not to control? Parenting behaviours and adolescent online aggression

Non-empirical publications have espoused the importance of monitoring/controlling children’s online and computer activities through monitoring software; however, no empirical research has verified whether this is a viable means for promoting responsible and safe internet use. This study examined the association between parenting behaviours and adolescent online aggression. The sample included 733 adolescents (451 females), between 10 and 18 years, from Western Canada. Participants completed a questionnaire that included questions on internet aggression, and parenting. The parenting questions were modified from Stattin and Kerr’s (2000) questionnaire to better suit the online environment. Results from the univariate least squares factor analysis revealed two distinct factors: (1) Parent Solicitation (parents ask where child is going on the internet), (2) Child Disclosure (child naturally tells parents what they are doing). Hierarchical Linear Regression analysis revealed that having a computer in the bedroom increased the likelihood of engaging in online aggression and that adolescent self-disclosure of online behaviours (and not controlling or monitoring online activities) was negatively associated with online aggression. These findings emphasize the importance of establishing good communication between parents and adolescents rather than investing money on monitoring software and on controlling adolescent internet use.     

An Approach to Representation for Principle Scheme Design

One of the open issues in principle scheme design of mechanical systems is principle representation, which not only outlines the physical principles, but also facilitates the design synthesis. An energy-based approach to represent principle scheme design is proposed. Firstly, an energy interaction model of mechanical systems is established and an intermediate model is derived, in which principle scheme design is transformed into solving the energy functions of system. Then the energy functions are modeled with the language of bond graphs, and principle representation for components is presented. Finally, characteristics of the developed representation approach are analyzed and a design example of gate drive system is given to demonstrate this approach.     

To solve or to observe? The case of problem-solving interactivity within child learning games

We explored whether problem-solving interactivity within an instructional game fosters learning for children aged 8–10 years. Participants (N = 139) studied a biological topic either through a game-based learning environment (in which they solved assigned problems by interacting with a plant model) or from a standard learning environment (in which they observed how the problems were solved in an animation) (i.e., between-subject design). The treatments were equal with regard to learning content and guidance. No between-group differences in learning outcomes were detected (comprehension: d = 0.16; transfer: d = −0.01). Self-rating of enjoyment tended to be higher in the game group (d = 0.32), and when the children could choose between the treatments in a free-choice period, they strongly preferred the interactive game (87.5%). The results suggest that both the interactive and the non-interactive treatments are useful, but their applicability may differ depending on the learning context (e.g., school vs. home).     

To use or not to use? Social media in higher education in developing countries

This research is a response to the universal use of social media by students for academic-related purposes. It bridges a gap in knowledge in relation to the value and use of social media as effective teaching and learning tool in higher education in developing countries. A pre-tested questionnaire survey was self-administered to faculty members in the eight public Egyptian higher institutions offering tourism and hotel management programs. The results showed that social media have a great value for academic-related purposes, particularly as teaching and learning tool; however, the actual use by faculty was at a minimal level. In-depth interviews were conducted to identify the perils, barriers and concerns for the minimal use. Several barriers were identified with some specific to developing countries' context. Nonetheless, there was consensus by faculty that if these barriers were overcome, social media could be developed as an innovative and effective tool for teaching and learning. Implications for researchers and policy makers are discussed.     

To text or not to text? The importance of text messaging among college-aged youth

As the availability, affordability, and popularity of mobile phones has increased in the last decade, text messaging has become one of the primary means of communication among adolescent peer groups. As such, it can be speculated that mobile phones and text messaging have become an integral aspect of the culture of young people today. However, little research has of yet identified how people react to an absence of texting behavior. This study attempts to demonstrate the extent to which people have become reliant upon text messaging to maintain daily relationships with peers, as well as their own self-concept. Frequencies and patterns of alternative behaviors, non-compliance, and anxiety are measured during separate restriction periods among a group of high and low text users, ages 18–23. Results indicate that there was a significant difference between individuals identified as ’high’ and ’low’ text users, although regardless of this distinction, texting emerged as the preferred form of contact among peers within this cohort. A high degree of quantitatively and qualitatively reported anxiety during periods of restriction was also noted, suggesting that this behavior has become an integrated element of daily living for this group.     

To connect or promote?: An exploratory examination of Facebook pages dedicated to moms

Mothers are increasingly using Facebook for a variety of communication functions. As an initial step toward understanding how mothers use Facebook, this exploratory study examines the types of messages mothers receive from Facebook pages solely designated for them. Using a content analysis, twelve Facebook pages and 526 administrators’ posts were analyzed. The majority of pages identified purpose as conversational/ discussion starter, while the majority of administrators’ posts were coded as informational/promotional. The discrepancies between the pages’ and posts’ purpose are considered. Directions for extending the research examining mothers and social networking sites are also suggested.     

Motivating Human–Agent Interaction: Transferring Insights from Behavioral Marketing to Interface Design

The understanding of consumer interaction with online EC Websites is one of the big current challenges for online marketers. The present paper investigates what drives and impedes Net customers to interact with a marketer's websites and, more specifically, with decision support interface systems (DSISs) employed in these sites to assist users when shopping or searching for high-involvement consumer goods. DSIS are considered as a predecessor or partially already integrator of more elaborated agent systems that may be used in future EC environments. It is shown that the design of today's DSISs is sub-optimal for both marketers and consumers, because it fails to motivate user interaction. One reason for this might be that little effort has been made to transfer the insights from consumer behavior to the design of EC user interfaces. The current paper aims to address this gap by proposing a number of new DSIS design principles, all of which are based on insights from traditional marketing search- and perceived risk theory. The main contribution of this paper is that it proposes a design approach for EC Websites that intuitively makes the user model available to the user [Shneiderman and Maes, 36].     

To compete or to take over? An economic analysis of new sellers on e-commerce marketplaces

The rise of e-commerce has inspired entrepreneurs to start their businesses online. E-commerce platforms, such as eBay, Amazon Marketplace, and Taobao, feature low barriers of entry to their sellers, as there is very low cost involved in entering an online marketplace and becoming a seller. In the meantime, we observe that many sellers choose to incur a much higher cost and enter the marketplace by taking over an existing seller’s account. We identify an interesting problem faced by entrants to online marketplaces: should they enter as new or should they take over another seller? Entrants’ decisions are complicated by several factors, including the reputation of the existing seller, the entrant’s capability, and the information asymmetry between the entrant and the incumbent. We develop an economic model to study the interactions between an entrant and an incumbent in an e-commerce marketplace. We discover that reputation plays an important role in the entrant’s competition-takeover decision. Our findings carry useful insights for e-commerce platforms in understanding the impact of entrants on the existing community of sellers.     

To index or not to index: Time–space trade-offs for positional ranking functions in search engines

Positional ranking functions, widely used in web search engines and related search systems, improve result quality by exploiting the positions of the query terms within documents. However, it is well known that positional indexes demand large amounts of extra space, typically about three times the space of a basic nonpositional index. Textual data, on the other hand, is needed to produce text snippets. In this paper, we study time–space trade-offs for search engines with positional ranking functions and text snippet generation. We consider both index-based and non-index based alternatives for positional data. We aim to answer the question of whether positional data should be indexed, and how.We show that there is a wide range of practical time–space trade-offs. Moreover, we show that using about 1.30 times the space of positional data, we can store everything needed for efficient query processing, with a minor increase in query time. This yields considerable space savings and outperforms, both in space and time, recent alternatives from literature. We also propose several efficient compressed text representations for snippet generation, which are able to use about half of the space of current state-of-the-art alternatives with little impact in query processing time.     

To Plan or to Simply React? An Experimental Study of Action Planning in a Game Environment

Many contemporary computer games, notably action and role‐playing games, represent an interesting class of navigation‐intensive dynamic real‐time simulations inhabited by autonomous intelligent virtual agents (IVAs). Although higher level reasoning of IVAs in these domains seems suited for action planning, planning is not widely adopted in existing games and similar applications. Moreover, statistically rigorous study measuring performance of planners in decision making in a game‐like domain is missing. Here, five classical planners were connected to the virtual environment of Unreal Development Kit along with a planner for delete‐free domains (only positive preconditions and positive effects). Performance of IVAs employing those planners and IVAs with reactive architecture was measured on a class of game‐inspired test environments of various sizes and under different levels of external interference. The analysis has shown that planning agents outperform reactive agents if (i) the size of the problem is small or if (b) the environment changes are either hostile to the agent or infrequent. In delete‐free domains, specialized approaches are inferior to classical planners because the lower expressivity of delete‐free domains results in lower plan quality. These results can help to determine when planning is advantageous in games and for IVAs control in other dynamic real‐time environments.     

Is a Unified Methodology for System-Level Design Possible?

This article describes the principles of the design of embedded electronic systems from the perspective of the entire system. By not restricting this perspective to the electrical domain, a more disciplined, unified methodology can lead to more efficient system-level design. In a world where myriad wirelessly interconnected appliances are going to impact our everyday lives and where technology advances are posing fundamental problems at the nanodevice level, the most important challenge will be ensuring safe, secure, and effective design. A unified methodology is an essential ingredient for a successful use of technology in society.     

e-Sports: Playing just for fun or playing to satisfy life goals?

Purposee-Sports is an area of the game scene, in which computer game players specialize in a specific game, form game teams (clans), compete together in tournaments and meet at so-called LAN (Local Area Network) parties. The objective of this study was to compare the different types of e-Sports players from the perspective of their personality traits and explicit motives and to compare e-Sports players with casual players in selected life goals.MethodsA questionnaire assessing life goals (Pöhlmann & Brunstein, 1997) and basic personality traits (Personality inventory KUD, 1986) were administered to 108 e-Sports players and 54 casual computer game players.ResultsIn the group of e-Sports players, only clan leaders significantly differed in life goal power from those who were not members of any clan. Significant differences were also found between e-Sports players and casual players in terms of life goals affiliation and diversion.Conclusionse-Sports seem not only to be about playing computer games, but can also serve as a means of satisfying the need to belong. They do this by creating friendly relationships through membership in game teams and participation in LAN parties, or satisfying the need for power by upholding a position of a game team leader and determining its course of action.     

How to charge for network services – flat-rate or usage-based?

Currently, the Internet service provider market offers two different types of pricing plans. In the USA, the predominant pricing plan is a flat-rate plan. In Europe and Asia, the predominant one is a per-minute pricing plan. Enrolled in such a pricing plan, users have to pay for the connect time to the Internet. Although Internet Service Providers (ISPs) have competed heavily for users in these last few years, they only have focused on trying to offer the lowest price within such pricing plans. A potentially more profitable and sustainable method of doing business would be for ISPs to differentiate themselves by offering more customized pricing plans for certain user groups. An important question then is whether a pricing plan exists that is attractive to users, but also allows ISPs to build a sustainable business. Based on empirical results of the INternet Demand EXperiment (INDEX) project, we discuss a pricing plan for Internet access that appears to be appreciated by Internet users as well as by ISPs. This pricing plan combines the advantages of flat-rate pricing and usage-based pricing. Users will benefit by receiving unlimited access to a basic service with the choice of higher quality of service (QoS) whenever they demand. From the ISPs' perspective, such a pricing plan will help any ISP to focus on certain user groups and to reduce peak network load.     

To var or not to var: how do C# developers use and misuse implicit and explicit typing?

When implicit typing with the “var” keyword was introduced into C#, it prompted contradictory opinions among developers. This paper starts by explaining the difference between implicit and explicit typing and then provides an overview of developers’ opinions and guidelines that are available online. This paper then reports on the results of a study that investigated how C# developers use and misuse implicit and explicit typing. This study involved analyzing the source code of 10 different open-source software projects including more than 16,500,000 lines of code and more than 930,000 variables. This study investigated to what extent developers use a form of typing that affects the readability of a variable’s type and the length of its declaration. It also investigated whether or not there is an adoption of a consistent set of guidelines in general and across each software project. A tool called “Code Analysis and Refactoring Engine for C#” (Care#) was developed and used to conduct the code analysis for this study.