Rifat Shahriyar

Intelligent Mobile Health Monitoring System (IMHMS)

Health monitoring is repeatedly mentioned as one of the main application areas for Pervasive computing. Mobile Health Care is the integration of mobile computing and health monitoring. It is the application of mobile computing technologies for improving communication among patients, physicians, and other health care workers. As mobile devices have become an inseparable part of our life it can integrate health care more seamlessly to our everyday life. It enables the delivery of accurate medical information anytime anywhere by means of mobile devices. Recent technological advances in sensors, low-power integrated circuits, and wireless communications have enabled the design of low-cost, miniature, lightweight and intelligent bio-sensor nodes. These nodes, capable of sensing, processing, and communicating one or more vital signs, can be seamlessly integrated into wireless personal or body area networks for mobile health monitoring. In this paper we present Intelligent Mobile Health Monitoring System (IMHMS), which can provide medical feedback to the patients through mobile devices based on the biomedical and environmental data collected by deployed sensors.

Taking off the gloves with reference counting Immix

Despite some clear advantages and recent advances, reference counting remains a poor cousin to high-performance tracing garbage collectors. The advantages of reference counting include a) immediacy of reclamation, b) incrementality, and c) local scope of its operations. After decades of languishing with hopelessly bad performance, recent work narrowed the gap between reference counting and the fastest tracing collectors to within 10%. Though a major advance, this gap remains a substantial barrier to adoption in performance-conscious application domains. Our work identifies heap organization as the principal source of the remaining performance gap. We present the design, implementation, and analysis of a new collector, RC Immix, that replaces reference countings traditional free-list heap organization with the line and block heap structure introduced by the Immix collector. The key innovations of RC Immix are 1) to combine traditional reference counts with per-line live object counts to identify reusable memory and 2) to eliminate fragmentation by integrating copying with reference counting of new objects and with backup tracing cycle collection. In RC Immix, reference counting offers efficient collection and the line and block heap organization delivers excellent mutator locality and efficient allocation. With these advances, RC Immix closes the 10% performance gap, matching the performance of a highly tuned production generational collector. By removing the performance barrier, this work transforms reference counting into a serious alternative for meeting high performance objectives for garbage collected languages.

Down for the count? Getting reference counting back in the ring

Reference counting and tracing are the two fundamental approaches that have underpinned garbage collection since 1960. However, despite some compelling advantages, reference counting is almost completely ignored in implementations of high performance systems today. In this paper we take a detailed look at reference counting to understand its behavior and to improve its performance. We identify key design choices for reference counting and analyze how the behavior of a wide range of benchmarks might affect design decisions. As far as we are aware, this is the first such quantitative study of reference counting. We use insights gleaned from this analysis to introduce a number of optimizations that significantly improve the performance of reference counting. We find that an existing modern implementation of reference counting has an average 30% overhead compared to tracing, and that in combination, our optimizations are able to completely eliminate that overhead. This brings the performance of reference counting on par with that of a well tuned mark-sweep collector. We keep our in-depth analysis of reference counting as general as possible so that it may be useful to other garbage collector implementers. Our finding that reference counting can be made directly competitive with well tuned mark-sweep should shake the communitys prejudices about reference counting and perhaps open new opportunities for exploiting reference countings strengths, such as localization and immediacy of reclamation.

Fast conservative garbage collection

Garbage collectors are exact or conservative. An exact collector identifies all references precisely and may move referents and update references, whereas a conservative collector treats one or more of stack, register, and heap references as ambiguous. Ambiguous references constrain collectors in two ways. (1) Since they may be pointers, the collectors must retain referents. (2) Since they may be values, the collectors cannot modify them, pinning their referents. We explore conservative collectors for managed languages, with ambiguous stacks and registers. We show that for Java benchmarks they retain and pin remarkably few heap objects: < 0.01% are falsely retained and 0.03% are pinned. The larger effect is collector design. Prior conservative collectors (1) use mark-sweep and unnecessarily forgo moving all objects, or (2) use mostly copying and pin entire pages. Compared to generational collection, overheads are substantial: 12% and 45% respectively. We introduce high performance conservative Immix and reference counting (RC). Immix is a mark-region collector with fine line-grain pinning and opportunistic copying of unambiguous referents. Deferred RC simply needs an object map to deliver the first conservative RC. We implement six exact collectors and their conservative counterparts. Conservative Immix and RC come within 2 to 3% of their exact counterparts. In particular, conservative RC Immix is slightly faster than a well-tuned exact generational collector. These findings show that for managed languages, conservative collection is compatible with high performance.

Controlling remote system using mobile telephony

In modern days, we have to be in touch with various high-tech machineries and equipments to get our jobs done and make our lives easier. Too often these machineries serve very important purposes and sometimes require continuous monitoring. But its not always feasible to be physically near to the system. So, to be in touch with this sort of important systems by not being physically close, we need some sort of remote solution. The remote solution should unleash the restrictions due to physical distance yet provides enough reliability even from distance. Some products are commercially available which allow remote systems controlling through internet which is undoubtedly emerging; yet, it lacks the true sense of real mobility and security, making the remote system controlling a limited term than it is supposed to be. In search of true a remote and adequately secure solution to be really effective and practicable, which can be a better choice to mobile telephony? Mobile phones have become almost an inseparable part of civil lives today. In this paper we introduce the mechanism so that the ordinary services of the mobile phones can be leveraged to communicate with and control the remote systems.

Mining Developer Questions about Major Web Frameworks.

Web frameworks are the de facto way to build web-enabled applications. Stack Overflow, being one of the leading question answering sites available, has become a helpful resource in numerous software engineering research. In this paper, we present a study of common challenges and issues among developers of two major web frameworks namely Laravel and Django by mining questions asked on Stack Overflow. We extracted the issues that the developers are most concerned about. We sorted these issues by popularity and difficulty metrics and observed the contrasting nature of difficulty and popularity. We also noted an exception that installation is a popular issue over both the frameworks and simultaneously it is also difficult to resolve. Besides, we found that about 50% issues are common over both the frameworks. Our findings would help the framework developers to understand better the need of the framework users by focusing most difficult and the most popular issues.

Understanding the software development practices of blockchain projects: a survey

Background: The application of the blockchain technology has shown promises in various areas, such as smart-contracts, Internet of Things, land registry management, identity management, etc. Although Github currently hosts more than three thousand active blockchain software (BCS) projects, a few software engineering research has been conducted on their software engineering practices. Aims: To bridge this gap, we aim to carry out the first formal survey to explore the software engineering practices including requirement analysis, task assignment, testing, and verification of blockchain software projects. Method: We sent an online survey to 1,604 active BCS developers identified via mining the Github repositories of 145 popular BCS projects. The survey received 156 responses that met our criteria for analysis. Results: We found that code review and unit testing are the two most effective software development practices among BCS developers. The results suggest that the requirements of BCS projects are mostly identified and selected by community discussion and project owners which is different from requirement collection of general OSS projects. The results also reveal that the development tasks in BCS projects are primarily assigned on voluntary basis, which is the usual task assignment practice for OSS projects. Conclusions: Our findings indicate that standard software engineering methods including testing and security best practices need to be adapted with more seriousness to address unique characteristics of blockchain and mitigate potential threats.

Multi-objective formulation of MSA for phylogeny estimation (Do phylogeny-aware measures guide towards better phylogenetic tree?)

Multiple sequence alignment (MSA) is a basic step in many analyses in computational biology, including predicting the structure and function of proteins, orthology prediction and estimating phylogenies. The objective of MSA is to infer the homology among the sequences of chosen species. Commonly, the MSAs are inferred by optimizing a single function or objective. The alignments estimated under one criterion may be different to the alignments generated by other criteria, inferring discordant homologies and thus leading to different evolutionary histories relating the sequences. In recent past, researchers have advocated for the multi-objective formulation of MSA, to address this issue, where multiple conflicting objective functions are being optimized simultaneously to generate a set of alignments. However, no theoretical or empirical justification with respect to a real-life application has been shown for a particular multi-objective formulation. In this study, we investigate the impact of multi-objective formulation in the context of phylogenetic tree estimation. Employing multi-objective metaheuristics, we demonstrate that trees estimated on the alignments generated by multi-objective formulation are substantially better than the trees estimated by the state-of-the-art MSA tools, including PASTA, MUSCLE, CLUSTAL, MAFFT etc. We also demonstrate that highly accurate alignments with respect to popular measures like sum-of-pair (SP) score and total-column (TC) score do not necessarily lead to highly accurate phylogenetic trees. Thus in essence we ask the question whether a phylogeny-aware metric can guide us in choosing appropriate multi-objective formulations that can result in better phylogeny estimation. And we answer the question affirmatively through carefully designed extensive empirical study. As a by-product we also suggest a methodology for primary selection of a set of objective functions for a multi-objective formulation based on the association with the resulting phylogenetic tree.

Towards concurrent data structure development with Relaxed Synchronization

Concurrent data structures may introduce a performance and scalability holdup and thus prevent the effective use of parallel hardware. There is a trade-off between scalable performance and precision in implementing concurrent data structures. A remedy to the scalability problem is to relax the interpretation of concurrent data structures. The construal is given by some notion equivalent to the sequential behaviour. The equivalence is determined by a consistency condition, most commonly linearity, and the sequential behaviour is inherited from the sequential version of the data structure (e.g. the sequential behaviour of a concurrent stack is a regular stack). Therefore, relaxing the semantics of a concurrent data structure extents to either weakening the consistency condition or redefining or relaxing its sequential specification. In this paper, we present a framework for relaxing the synchronization of a Stack data structure in a quantitative manner. A fundamental challenge in using relaxed synchronization is guaranteeing that the relaxed program always produces results with a specified quality. We propose a methodology that addresses this challenge in programming with relaxed synchronization. Using our methodology, results that are of the same quality as the original program, can be produced with a speedup in time.

Intelligent depression detection and support system: Statistical analysis, psychological review and design implication

Depression is a familiar psychological disorder caused by a combination of genetic, biological, environmental, and psychological factors. Untreated depression carries a high cost in terms of relationship problems, family suffering, and loss of work productivity. However diagnosis and treatment of depression is difficult due to varied severity, frequency, and duration of symptoms in depressed individuals. In this study, correlation between depression levels and behavioral trends of individuals has been established through a survey involving around 120 undergraduate students. The survey outcome is analyzed from a psychological viewpoint and finally some design implications on an automated system of depression detection and support system have been proposed.