Location based mobile computing - a tuplespace perspective

This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2006 IOS PressLocation based or "context aware" computing is becoming increasingly recognized as a vital part of a mobile computing environment. As a consequence, the need for location-management middleware is widely recognized and actively researched. Location-management is frequently offered to the application through a "location API" (e.g. JSR 179) where the mobile unit can find out its own location as coordinates or as "building, floor, room" values. It is then up to the application to map the coordinates into a set of localized variables, e.g. direction to the nearest bookshop or the local timezone. It is the opinion of the authors that a localization API should be more transparent and more integrated: The localized values should be handed to the application directly, and the API for doing so should be the same as the general storage mechanisms. Our proposed middleware for location and context management is built on top of Mobispace. Mobispace is a distributed tuplespace made for mobile units (J2me) where replication between local replicas takes place with a central server (over GPRS) or with other mobile units (using Bluetooth). Since a Bluetooth connection indicates physical proximity to another node, a set of stationary nodes may distribute locality information over Bluetooth connections, and this information may be retrieved through the ordinary tuplespace API. Besides the integration with the general framework for communication and coordination the middleware offers straightforward answers to questions like: Where is node X located? Which nodes are near me? What is the trace of node Y

Total order in opportunistic networks

Opportunistic network applications are usually assumed to work only with unordered immutable messages, like photos, videos, or music files, while applications that depend on ordered or mutable messages, like chat or shared contents editing applications, are ignored. In this paper, we examine how total ordering can be achieved in an opportunistic network. By leveraging on existing dissemination and causal order algorithms, we propose a commutative replicated data type algorithm on the basis of Logoot for achieving total order without using tombstones in opportunistic networks where message delivery is not guaranteed by the routing layer. Our algorithm is designed to use the nature of the opportunistic network to reduce the metadata size compared to the original Logoot, and even to achieve in some cases higher hit rates compared to the dissemination algorithms when no order is enforced. Finally, we present the results of the experiments for the new algorithm by using an opportunistic network emulator, mobility traces, and Wikipedia pages.Peer ReviewedPostprint (author's final draft

A framework for requirements engineering for context-aware services

Context-aware services, especially when made available to mobile devices, constitute an interesting but very challenging domain. It poses fundamental problems for both requirements engineering, software architecture, and their relationship. We propose a novel, reflection-based framework for requirements engineering for this class of applications. The framework addresses the key difficulties in this field, such as changing context and changing requirements. We report preliminary work on this framework and suggest future directions

Safety and Security Analysis of AEB for L4 Autonomous Vehicle Using STPA

Autonomous vehicles (AVs) are coming to our streets. Due to the presence of highly complex software systems in AVs, there is a need for a new hazard analysis technique to meet stringent safety standards. System Theoretic Process Analysis (STPA), based on Systems Theoretic Accident Modeling and Processes (STAMP), is a powerful tool that can identify, define, analyze and mitigate hazards from the earliest conceptual stage deployment to the operation of a system. Applying STPA to autonomous vehicles demonstrates STPA\u27s applicability to preliminary hazard analysis, alternative available, developmental tests, organizational design, and functional design of each unique safety operation. This paper describes the STPA process used to generate system design requirements for an Autonomous Emergency Braking (AEB) system using a top-down analysis approach to system safety. The paper makes the following contributions to practicing STPA for safety and security: 1) It describes the incorporation of safety and security analysis in one process and discusses the benefits of this; 2) It provides an improved, structural approach for scenario analysis, concentrating on safety and security; 3) It demonstrates the utility of STPA for gap analysis of existing designs in the automotive domain; 4) It provides lessons learned throughout the process of applying STPA and STPA-Sec

When outcome expectations become habitual: explaining vs. predicting new media technology use from a social cognitive perspective

This study examined the triadic relationship between expected outcomes, habit strength, and media technology use within the model of media attendance (Larose & Eastin, 2004). Mobile phone users (N = 664) were divided into two groups using a stratified random sampling method. Respondents of group one (n = 334) were surveyed on existing mobile phone use, respondents of group two (n = 310) were surveyed on the intention to use mobile video phone. On the basis of structural equation analysis, the results of this study support the assumption that within the model of media attendance existing media use is more likely to be explained by habit strength, and new media use is more likely to be predicted by outcome expectations

Urban socioeconomic inequality and biodiversity often converge, but not always: A global meta-analysis

It is through urban biodiversity that the majority of humans experience nature on a daily basis. As cities expand globally, it is increasingly important to understand how biodiversity is shaped by human decisions, institutions, and environments. In some cities, research has documented convergence between high socioeconomic status (SES) and high species diversity. Yet, other studies show that residents with low SES live amid high biodiversity or that SES and biodiversity appear unrelated. This study examines the conditions linked to varying types of relationships between SES and biodiversity. We identified and coded 84 case studies from 34 cities in which researchers assessed SES-biodiversity relationships. We used fuzzy-set Qualitative Comparative Analysis (fsQCA) to evaluate combinations of study design and city-level conditions that explain why SES-biodiversity relationships vary city to city and between plants and animals. While the majority of cases demonstrated increased biodiversity in higher SES neighborhoods, we identified circumstances in which inequality in biodiversity distribution was ameliorated or negated by disturbance, urban form, social policy, or collective human preference. Overall, our meta-analysis highlights the contributions of residential and municipal decisions in differentially promoting biodiversity along socioeconomic lines, situated within each city’s environmental and political context. Through identifying conditions under which access to biodiversity is more or less unequal, we call attention to outstanding research questions and raise prospects for better promoting equitable access to biodiversity