Does network quality matter? A field study of mobile user satisfaction

Mobile quality of experience and user satisfaction are growing research topics. However, the relationship between a user’s satisfaction with network quality and the networks real performance in the field remains unexplored.This paper is the first to study both network and non-network predictors of user satisfaction in the wild. We report findings from a large sample (2224 users over 12 months) combining both questionnaires and network measurements. We found that minimum download goodput and device type predict satisfaction with network availability. Whereas for network speed, only download factors predicted satisfaction. We observe that users integrate over many measurements and exhibit a known peak-end effect in their ratings. These results can inform modeling efforts in quality of experience and user satisfaction.     

A demand-driven virtual disk prefetch mechanism for seamless mobility of personal computing environments

In this paper, we propose a demand-driven virtual disk (VD) prefetch mechanism—DPM—to improve the performance of virtual machine (VM) at destination site for mobile personal computing environments. DPM uses an extended CoW (Copy-on-Write) virtual block device to split the traditional monolithic large-sized VD image into multiple small-sized SVD (Software Virtual Disk) images at a basic granularity of a single kind of software. Based on the fine-grained VD splitting, DPM uses an access frequency and dynamic priority-based prefetch target identifying-APTI algorithm to identify the SVDs of the software being used by the user at destination site, and prefetches those SVDs by utilizing P2P transportation mechanism at background. We have built a prototype to realize DPM on Xen virtual machine monitor (VMM). Experiments on the prototype show that DPM can effectively improve the VM performance at an unexpected destination site without any cached VD state, being helpful in achieving seamless mobility of personal computing environments in distributed virtual machine environments.     

Cooperative user–network interactions in next generation communication networks

Next Generation Communication Networks employ the idea of convergence, where heterogeneous access technologies may coexist, and a user may be served by anyone of the participating access networks, motivating the emergence of a Network Selection mechanism. The triggering and execution of the Network Selection mechanism becomes a challenging task due to the heterogeneity of the entities involved, i.e., the users and the access networks. This heterogeneity results in different and often conflicting interests for these entities, motivating the question of how they should behave in order to remain satisfied from their interactions. This paper studies cooperative user–network interactions and seeks appropriate modes of behaviour for these entities such that they achieve own satisfaction overcoming their conflicting interests.     

Optimizations in computing the Duquenne–Guigues basis of implications

In this paper, we consider algorithms involved in the computation of the Duquenne–Guigues basis of implications. The most widely used algorithm for constructing the basis is Ganter’s Next Closure, designed for generating closed sets of an arbitrary closure system. We show that, for the purpose of generating the basis, the algorithm can be optimized. We compare the performance of the original algorithm and its optimized version in a series of experiments using artificially generated and real-life datasets. An important computationally expensive subroutine of the algorithm generates the closure of an attribute set with respect to a set of implications. We compare the performance of three algorithms for this task on their own, as well as in conjunction with each of the two algorithms for generating the basis. We also discuss other approaches to constructing the Duquenne–Guigues basis.     

Human–computer interaction issues for mobile computing in a variable work context

The current paper takes an introspective look at the human–computer interaction (HCI) issues for mobile computing in a variable work context. We catalogue the current research in four major categories. The major findings of our study are following. (1) A majority of HCI issues, about 58%, fall under the category of computer systems and interface architecture implications. (2) 23% of the articles focus on development and implementation issues. (3) 13% of the articles focus on use and context of computer issues. (4) 6% of the articles focus on human characteristics issues. Further, the literature indicates that the field services is a main application of mobile computing (46%) followed by sales force (21%), health care (17%), fieldwork (8%), insurance claims (4%) and journalism (4%).     

Assessment of the atomic mobility in fcc Al–Cu–Mg alloys

Various experimentally measured diffusivities of fcc Al–Mg, Cu–Mg and Al–Cu–Mg alloys available in the literature are critically reviewed in the present work. The first-principles calculations coupled with a semi-empirical correlation is employed to derive the temperature dependence of impurity diffusivity for Mg in fcc Cu. Atomic mobilities for the above fcc alloys are then evaluated as a function of temperature and composition by means of DICTRA (DIffusion Controlled TRAnsformation) software. Comprehensive comparisons between calculated and measured diffusivities show that most of the experimental data can be well reproduced by the presently obtained atomic mobilities. The concentration profiles and diffusion paths are predicted with the mobility parameters in a series of binary and ternary diffusion couples. A good agreement is obtained between experiment and simulation.     

Efficient application scheduling in mobile cloud computing based on MAX–MIN ant system

Combining the advantages of mobile computing and cloud computing, Mobile Cloud Computing (MCC) greatly enriches the types of applications on mobile devices and enhances the quality of service of the applications. Under various circumstances, researchers have put forward several MCC architectures. However, it still remains a challenging task of how to design a reasonable mobile cloud model with efficient application processing structure for some particular environment. This paper firstly presents a Hybrid Local Mobile Cloud Model (HLMCM) with detailed application scheduling structure. Secondly, a scheduling algorithm for HLMCM based on MAX–MIN Ant System is put forward. Finally, the effectiveness and suitability of our proposed algorithms are evaluated through a series of simulation experiments.     

A computational resources scheduling algorithm in edge cloud computing: from the energy efficiency of users’ perspective

The Journal of Supercomputing - Nowadays, research in the field of task offloading not only pays attention to the computing performance of computing nodes, but also pays attention to the impact of...     

Self-report measures for the assessment of human–machine interfaces in automated driving

Cognition, Technology & Work - For a successful market introduction of Level 3 Automated Driving Systems (L3 ADS), a careful evaluation of human–machine interfaces (HMIs) is necessary....     

Impact of hand-assisted viewing on user performance and?learning patterns in virtual environments

The ability to locate, select and interact with objects is fundamental to most Virtual Reality (VR) applications. Recently, it was demonstrated that the virtual hand metaphor, a technique commonly used for these tasks, can also be employed to control the virtual camera, resulting in improved performance and user evaluation in visual search tasks.     

Performance–energy adaptation of parallel programs in pervasive computing

It is meaningful to use a little energy to obtain more performance improvement compared with the increased energy. It also makes sense to relax a small quantity of performance restriction to save an enormous amount of energy. Trading a small amount of energy for a considerable sum of performance or vice versa is possible if the relativities between performance and energy of parallel programs are exactly known. This work studies the relativities by recording the performance speedup and energy consumption of parallel programs when the number of cores on which programs run are changed. We demonstrate that the performance improvement and the increased energy consumption have a linear negative correlation.In addition, these relativities can guide us to do performance–energy adaptation under two assumptions. Our experiments show that the average correlation coefficients between performance and energy are higher than 97 %. Furthermore, it can be found that exchanging less than 6 % performance loss for more than 37 % energy consumption is feasible and vise versa.     

Looking ahead in pervasive computing: Challenges and opportunities in the era of cyber–physical convergence

The physical environment is becoming more and more saturated with computing and communication entities that interact among themselves, as well as with users: virtually everything will be enabled to source information and respond to appropriate stimuli. In this technology-rich scenario, real-world components interact with cyberspace via sensing, computing and communication elements, thus driving towards what is called the Cyber–Physical World (CPW) convergence. Information flows from the physical to the cyber world, and vice-versa, adapting the converged world to human behavior and social dynamics. Indeed humans are at the center of this converged world since information about the context in which they operate is the key element to adapt the CPW applications and services. Alongside, a new wave of (human) social networks and structures are emerging as important drivers for the development of novel communication and computing paradigms. In this article we present some of the research issues, challenges and opportunities in the convergence between the cyber and physical worlds. This article is not a comprehensive survey of all aspects of the CPW convergence. Instead, it presents some exciting research challenges and opportunities identified by members of the journal’s editorial board with a goal to stimulate new research activities in the emerging areas of CPW convergence.     

A benefit–cost perspective of the consumer adoption of the mobile banking system

The present research adopts a benefit–cost perspective to study consumer adoption of the mobile banking services. It is suggested that because of the specific product context of the mobile banking service, such as the difficulty to assess some experiential qualities like the ease of use due to a low trial rate of mobile banking and the inherent risk factor involved in a new financial service technology, models complementary to the technology adoption model may be needed to accommodate these product contexts. In the present research, the benefit–cost framework was employed as an example of the complementary framework to study consumers' adoption of the mobile banking system. The key benefit of mobile banking is convenience, while the key cost is security. A set of ability and risk factors were modelled via structural equation model (SEM) as the antecedents of the benefit and cost of adopting the mobile banking system. The results showed that the empirical data supported most hypothesised relationships among the factors. It is concluded that consumers' new technology adoption behaviour is a complicated phenomenon which may require different models in different product contexts. It is suggested that future research should address the issue of the preconditions and product contexts under which a certain class of models may be most suitable to explain the adoption behaviour.     

Cryptanalysis of a remote user authentication scheme for mobile client–server environment based on ECC

Understanding security failures of cryptographic protocols is the key to both patching existing protocols and designing future schemes. The design of secure remote user authentication schemes based on elliptic curve crypto-graphy (ECC) for mobile applications is still quite a challenging problem, though many schemes have been published lately. In this paper, we analyze an efficient ID-based scheme for mobile client–server environment without the MapToPoint function introduced by He et al. in 2012. This proposal attempts to overcome many of the well known security and efficiency shortcomings of previous schemes, and it also carries a claimed proof of security in the random oracle model. However, notwithstanding its formal security arguments, we show that He et al.’s protocol even cannot attain the basic goal of mutual authentication by demonstrating its vulnerabilities to reflection attack and parallel session attack. Besides these two security vulnerabilities, their scheme also suffers from some practical pitfalls such as user anonymity violation and clock synchronization problem. In addition, we carry out an investigation into their security proof and propose some changes to the scheme so that it can achieve at least its basic security goal, in the hope that similar mistakes are no longer made in the future.     

Evaluation of haptic guidance virtual fixtures and 3D visualization methods in telemanipulation—a user study

Intelligent Service Robotics - This work presents a user-study evaluation of various visual and haptic feedback modes on a real telemanipulation platform. Of particular interest is the potential...