About the Web

ABSTRACT

This article reviews selected magazines and journals of interest to academic librarians that include information about the Web. Reviewed titles include library science titles, general educational titles, and popular titles found on newsstands. The titles reviewed are aimed towards two groups of librarians: those most involved with developing content (such as reference librarians and bibliographers), and those involved with Web design, development, and policy issues.     

Preventive maintenance scheduling for repairable system with deterioration

Maintenance as an important part in manufacturing system can keep equipment in good condition. Many maintenance policies help to decrease the unexpected failures and reduce high operational cost such as conventional preventive maintenance. But these conventional preventive maintenance policies have the same time interval T that may easily neglect system’s reliability, because the system deteriorates with increased usage and age. Hence, this study has developed a reliability-centred sequential preventive maintenance model for monitored repairable deteriorating system. It is supposed that system’s reliability could be monitored continuously and perfectly, whenever it reaches the threshold R, the imperfect repair must be performed to restore the system. In this model, system’s failure rate function and operational cost are both considered by the effect of system’s corresponding condition, which helps to decide the optimal reliability threshold R and preventive maintenance cycle number. Finally, through case study, the simulation results show that the improved sequential preventive maintenance policy is more practical and efficient.     

Multidisciplinary Medical Team Meetings: An Analysis of Collaborative Working with Special Attention to Timing and Teleconferencing

In this paper we describe the process of a multi-disciplinary medical team meeting (MDTM), its functions and operation in colocated and teleconference discussions. Our goal is to identify the elements and mechanics of operation that enhance or threaten the dependability of the MDTM as a “system” and propose technologies and measures to make this system more reliable. In particular, we assess the effect of adding teleconferencing to the MDTM, and identify strengths and vulnerabilities introduced into the system by the addition of teleconferencing technology. We show that, with respect to the system’s external task environment, rhythms of execution of pre-meeting and post-meeting activities are critical for MDTM success and that the extension of the MDTM to wider geographic locations with teleconferencing might disrupt such rhythms thereby posing potential threats to dependability. On the other hand, an analysis of vocalisation patterns demonstrates that despite difficulties related to coordination and awareness in video-mediated communication (evidenced by increased time spent in case discussion, longer turns, decreased turn frequency and near lack of informal exchanges) the overall case discussion structure is unaffected by the addition of teleconferencing technology into proceedings.     

Adaptation and user expertise modelling in AthosMail

This article describes the User Model component of AthosMail, a speech-based interactive e-mail application developed in the context of the EU project DUMAS. The focus is on the system’s adaptive capabilities and user expertise modelling, exemplified through the User Model parameters dealing with initiative and explicitness of the system responses. The purpose of the conducted research was to investigate how the users could interact with a system in a more natural way, and the two aspects that mainly influence the system’s interaction capabilities, and thus the naturalness of the dialogue as a whole, are considered to be the dialogue control and the amount of information provided to the user. The User Model produces recommendations of the system’s appropriate reaction depending on the user’s observed competence level, monitored and computed on the basis of the user’s interaction with the system. The article also discusses methods for the evaluation of adaptive user models and presents results from the AthosMail evaluation.The research was done while the author was affiliated with the University of Art and Design Helsinki as the scientific coordinator of the DUMAS project.     

Implementation strategies for efficient media fragment retrieval

The current Web specifications such as HTML still treat video and audio resources as ‘foreign’ objects on the Web, especially lacking a transparent integration with current Web content. The Media Fragments URI specification is part of various efforts at W3C trying to make media a “first class citizen” on the Web. More specifically, with a Media Fragment URI, one can point to a media fragment by means of a URI, enabling people to identify, share, link, and consume media fragments in a standardized way. In this paper, we propose and evaluate a number of implementation strategies for Media Fragments. Additionally, we present two optimized implementation strategies: a Media Fragment Translation Service allowing to keep existing Web infrastructure such as Web servers and proxies and a fully integrated Media Fragments URI server that is independent of underlying media formats. Finally, we show how multiple bit rate media delivery can be deployed in a Media Fragments aware environment, using our Media Fragments URI server.     

A General Framework for Web Content Filtering

Web content filtering is a means to make end-users aware of the ‘quality’ of Web resources by evaluating their contents and/or characteristics against users’ preferences. Although they can be used for a variety of purposes, Web content filtering tools are mainly deployed as a service for parental control purposes, and for regulating the access to Web content by users connected to the networks of enterprises, libraries, schools, etc. Current Web filtering tools are based on well established techniques, such as data mining and firewall blocking, and they typically cater to the filtering requirements of very specific end-user categories. Therefore, what is lacking is a unified filtering framework able to support all the possible application domains, and making it possible to enforce interoperability among the different filtering approaches and the systems based on them. In this paper, a multi-strategy approach is described, which integrates the available techniques and focuses on the use of metadata for rating and filtering Web information. Such an approach consists of a filtering meta-model, referred to as MFM (Multi-strategy Filtering Model), which provides a general representation of the Web content filtering domain, independently from its possible applications, and of two prototype implementations, partially carried out in the framework of the EU projects EUFORBIA and QUATRO, and designed for different application domains: user protection and Web quality assurance, respectively.     

The gain and pain in taking the pilot seat: learning dynamics in a non immersive virtual solar system

This study describes and analyzes the learning interactions of nine high-school students’ free exploration of a virtual solar system (VSS). The VSS is a non-immersive three dimensional virtual environment based on real NASA planetary images. The computer screen serves as a “spacecraft’s window” for the learner to “fly” between objects, to change the system’s frame of reference and its pace. A systematic analysis of participants’ real-time observable interactions together with what they said revealed that each of them created an unique learning pattern within at least five different dimensions: (1) the cognitive dimension, (2) the affective dimension, (3) the navigation dimension, (4) the interface dimension, and (5) the assistance seeking dimension. The construction of meaning emerged as a non-linear process, which includes transitions between and within these dimensions. Three different styles of learning interactions were identified, suggesting that individual differences might be enhanced due to the unique VSS’ features. Overall, the VSS served as an enriching and motivational learning experience. The design of additional navigation tools and content scaffolding might help participants’ in building a sustained deep scientific understanding.     

Dynamics of a three-module vibration-driven system with non-symmetric Coulomb’s dry friction

In the present paper, a three-module vibration-driven system moving on a rough horizontal plane is modeled to investigate the relation among the system’s steady-state motion, external Coulomb’s dry friction force and internal excitations. Each module of the system represents a vibration-driven system composed of a rigid body and a movable internal mass. Major attention is focused on the primary resonance situation that the excitation frequency is close to the first-order natural frequency of the system. In the case that the external friction is low, the internal excitation is weak and the stick–slip motion is negligible, both methods of averaging and modal superposition are employed to study the steady-state motion of the system. Through a set of algebraic equations, an approximate value of the system’s average steady-state velocity is obtained. Several numerical examples are calculated to verify the validity of the analytical results both qualitatively and quantitatively. It is seen that big quantitative errors will appear if stick–slip motions occur. Then, two mechanisms for the possible stick–slip motions are put forward, which explain the errors on the average steady-state velocity. Numerical simulations verify our analysis on the stick–slip effects and their mechanisms. Finally, to maximize the average steady-state velocity of the system, optimal control problem is studied. It is shown that, in addition to modifying the friction coefficients, the improvement of the system’s efficiency can be provided by changing the initial phase shifts among the three internal excitations.     

Goal-driven risk assessment in requirements engineering

Risk analysis is traditionally considered a critical activity for the whole software system’s lifecycle. Risks are identified by considering technical aspects (e.g., failures of the system, unavailability of services, etc.) and handled by suitable countermeasures through a refined design. This, however, introduces the problem of reconsidering system requirements. In this paper, we propose a goal-oriented approach for analyzing risks during the requirements analysis phase. Risks are analyzed along with stakeholder interests, and then countermeasures are identified and introduced as part of the system’s requirements. This work extends the Tropos goal modeling formal framework proposing new concepts, qualitative reasoning techniques, and methodological procedures. The approach is based on a conceptual framework composed of three main layers: assets, events, and treatments. We use “loan origination process” case study to illustrate the proposal, and we present and discuss experimental results obtained from the case study.     

Two-phase queuing system with a threshold strategy of retrial calls

A two-phase queuing system (QS) has been considered; its first phase is represented by a single-linear system with retrial calls, and the second phase is represented by a multilinear (multiple) unbuffered QS. Queries arrive to the system in the group Markov flow. The system has two operational modes that differ by the strategy of the retrial attempts. Depending on the number of retrial calls, either a decentralized or centralized strategy of retrials is used. A stationary distribution of the system’s state probabilities at the embedded epochs and arbitrary time moments has been found, and formulae for the main characteristics of the system’s productivity have been obtained. Numerical examples are presented.     

A two-phase queuing system with access control and correlated arrival processes

A two-phase queuing system with access control is studied whose first phase consists of an infinite number of servers, while the second one consists of a finite number of servers. To the first phase, a Markovian input flow of queries arrives. On completion of the first-phase service, the customer either leaves the system or is passed to the second phase. In addition, a Markovian input flow of queries that do not require any first-phase service arrives to the second phase. An algorithm for finding a steady-state distribution of the system’s state probabilities is given, and some problems of the system’s paramaters optimization are considered.     

Dynamic simulation of a contact-enhanced MEMS inertial switch in Simulink?

A novel contact-enhanced design of MEMS (micro-electro-mechanical system) inertial switch was proposed and modeled in Simulink^?. The contact effect is improved by an easily realized modification on the traditional design, i.e. introducing a movable contact point between the movable electrode (proof mass) and the stationary electrode, therefore forming a dual mass-spring system. The focus of this paper is limited to a vertically driven unidirectional one for the purposes of demonstration, but this design concept and Simulink^? model is universal for various kinds of inertial micro-switches. The dynamic simulation confirmed the contact-enhancing mechanism, showing that the switch-on time can be prolonged for the dynamic shock acceleration and the bouncing effect can be reduced for the quasi-static acceleration. The threshold acceleration of the inertial switch is determined by the proof mass-spring system’s natural frequency. Since the inertial switches were fabricated by the multilayer electroplating technology, the proof mass thickness were assigned two values, 100 and 50 μm, in order to get threshold levels of 56 and 133 g respectively for the dynamic acceleration of half-sine wave with 1 ms duration. Other factors that influence the dynamic response, such as the squeeze film damping and the contact point-spring system’s natural frequency were also discussed. The fabricated devices were characterized by the drop hammer experiment, and the results were in agreement with the simulation predictions. The switch-on time was prolonged to over 50 μs from the traditional design’s 10 μs, and could reach as long as 120 μs. Finally, alternative device configurations of the contact-enhancing mechanism were presented, including a laterally driven bidirectional inertial switch and a multidirectional one.     

Explanation in Recommender Systems

There is increasing awareness in recommender systems research of the need to make the recommendation process more transparent to users. Following a brief review of existing approaches to explanation in recommender systems, we focus in this paper on a case-based reasoning (CBR) approach to product recommendation that offers important benefits in terms of the ease with which the recommendation process can be explained and the system’s recommendations can be justified. For example, recommendations based on incomplete queries can be justified on the grounds that the user’s preferences with respect to attributes not mentioned in her query cannot affect the outcome. We also show how the relevance of any question the user is asked can be explained in terms of its ability to discriminate between competing cases, thus giving users a unique insight into the recommendation process.     

What the <0.70, 1.17, 0.99, 1.07> is a Symbol?

The notion of a ‘symbol’ plays an important role in the disciplines of Philosophy, Psychology, Computer Science, and Cognitive Science. However, there is comparatively little agreement on how this notion is to be understood, either between disciplines, or even within particular disciplines. This paper does not attempt to defend some putatively ‘correct’ version of the concept of a ‘symbol.’ Rather, some terminological conventions are suggested, some constraints are proposed and a taxonomy of the kinds of issue that give rise to disagreement is articulated. The goal here is to provide something like a ‘geography’ of the various notions of ‘symbol’ that have appeared in the various literatures, so as to highlight the key issues and to permit the focusing of attention upon the important dimensions. In particular, the relationship between ‘tokens’ and ‘symbols’ is addressed. The issue of designation is discussed in some detail. The distinction between simple and complex symbols is clarified and an apparently necessary condition for a system to be potentially symbol, or token bearing, is introduced.     

Making it easier for older people to talk to smart homes: the effect of early help prompts

It is well known that help prompts shape how users talk to spoken dialogue systems. This study investigated the effect of help prompt placement on older users’ interaction with a smart home interface. In the dynamic help condition, help was only given in response to system errors; in the inherent help condition, it was also given at the start of each task. Fifteen older and sixteen younger users interacted with a smart home system using two different scenarios. Each scenario consisted of several tasks. The linguistic style users employed to communicate with the system (interaction style) was measured using the ratio of commands to the overall utterance length (keyword ratio) and the percentage of content words in the user’s utterance that could be understood by the system (shared vocabulary). While the timing of help prompts did not affect the interaction style of younger users, it was early task-specific help supported older users in adapting their interaction style to the system’s capabilities. Well-placed help prompts can significantly increase the usability of spoken dialogue systems for older people.     

Transaction models for Web accessibility

The Web has evolved into a dominant digital medium for conducting many types of online transactions such as shopping, paying bills, making travel plans, etc. Such transactions typically involve a number of steps spanning several Web pages. For sighted users these steps are relatively straightforward to do with graphical Web browsers. But they pose tremendous challenges for visually impaired individuals. This is because screen readers, the dominant assistive technology used by visually impaired users, function by speaking out the screen’s content serially. Consequently, using them for conducting transactions can cause considerable information overload. But usually one needs to browse only a small fragment of a Web page to do a step of a transaction (e.g., choosing an item from a search results list). Based on this observation this paper presents a model-directed transaction framework to identify, extract and aurally render only the “relevant” page fragments in each step of a transaction. The framework uses a process model to encode the state of the transaction and a concept model to identify the page fragments relevant for the transaction in that state. We also present algorithms to mine such models from click stream data generated by transactions and experimental evidence of the practical effectiveness of our models in improving user experience when conducting online transactions with non-visual modalities.     

A Hierarchical Fuzzy Clustering-based System to Create User Profiles

The rapid development of the World Wide Web as a medium of commerce and information dissemination has generated a growing interest of web portal managers in systems able to identify user profiles from the web access logs. The interpretation of these profiles can help re-organize the web portal, e.g., by restructuring the site’s content more efficiently, or even to build adaptive web portals, i.e., portals whose organization and presentation change depending on the specific visitor’s needs. In this paper, we assume that the pages of the web portal have been prearranged in a number of different categories. We introduce a systematic approach to determine a hierarchy of user profiles from the history of users’ accesses to the categories. First, we filter the access log by removing both occasional users and categories of poor interest. Then, we apply an Unsupervised Fuzzy Divisive Hierarchical Clustering (UFDHC) algorithm to cluster the users of the web portal into a hierarchy of fuzzy groups characterized by a set of common interests and each represented by a prototype, which defines the profile of the group typical member. To identify the profile a specific user belongs to, we propose a novel classification method which completely exploits the information contained in the hierarchy. To prove the effectiveness of our approach, we apply the UFDHC algorithm to access log data collected over a period of 15 days and use the classification method to associate a profile with the users defined by access log data collected during subsequent 60 days. Finally, we highlight the good characteristics of our system by comparing our results with the ones obtained by applying a profiling system based on a modified version of the fuzzy C-means.     

An Improved Algorithm for Online Unit Clustering

We revisit the online unit clustering problem in one dimension which we recently introduced at WAOA’06: given a sequence of n points on the line, the objective is to partition the points into a minimum number of subsets, each enclosable by a unit interval. We present a new randomized online algorithm that achieves expected competitive ratio 11/6 against oblivious adversaries, improving the previous ratio of 15/8. This immediately leads to improved upper bounds for the problem in two and higher dimensions as well. A preliminary version of this paper appeared in the Proceedings of the 13th Annual International Computing and Combinatorics Conference (COCOON 2007), LNCS 4598, pp. 383–393.     

Ubiquitous Memories: a memory externalization system using physical objects

In this paper we propose an object-triggered human memory augmentation system named “Ubiquitous Memories” that enables a user to directly associate his/her experience data with physical objects by using a “touching” operation. A user conceptually encloses his/her experiences gathered through sense organs into physical objects by simply touching an object. The user can also disclose and re-experience for himself/herself the experiences accumulated in an object by the same operation. We implemented a prototype system composed basically of a radio frequency identification (RFID) device. Physical objects are also attached to RFID tags. We conducted two experiments. The first experiment confirms a succession of the “encoding specificity principle,” which is well known in the research field of psychology, to the Ubiquitous Memories system. The second experiment aims at a clarification of the system’s characteristics by comparing the system with other memory externalization strategies. The results show the Ubiquitous Memories system is effective for supporting memorization and recollection of contextual events.