Accessibility evaluation of chats and forums in e-learning environments

Proceedings of: 2013 International Conference on Frontiers in Education: Computer Science & Computer Engineering (FECS'13): WORLDCOMP'13, July 22-25, 2013, Las Vegas, Nevada (USA)Collaborative learning is useful for students in their learning process. Nowadays, most e-learning systems include Computer Supported Collaborative Learning (CSCL) tools like chats and forums; however, are they accessible for everybody? This paper presents a heuristic evaluation of accessibility of two CSCL tools (chat and forum) in four web-based, open-source Learning Content Management Systems (LCMS): Moodle, ATutor, dotLRN and Claroline. The evaluation results show that the CSCL tools evaluated present accessibility barriers which are a handicap for many students who want to use the LCMSs Moreover, some recommendations are offered in order to improve the accessibility of the evaluated tools. Considering these recommendations in the development of the evaluated tools, all students could participate actively in the collaborative tasks proposed by teachersThis research work has been supported by the Regional Government of Madrid under the Research Network MA2VICMR (S2009/TIC-1542) and by the Spanish Ministry of Economy under the project MULTIMEDICA (TIN2010-20644-C03-01)Publicad

Assessment of Response Time for New Multi Level Feedback Queue Scheduler

Response time is one of the characteristics of scheduler, happens to be a prominent attribute of any CPU scheduling algorithm. The proposed New Multi Level Feedback Queue [NMLFQ] Scheduler is compared with dynamic, real time, Dependent Activity Scheduling Algorithm (DASA) and Lockes Best Effort Scheduling Algorithm (LBESA). We abbreviated beneficial result of NMLFQ scheduler in comparison with dynamic best effort schedulers with respect to response time.Comment: 7 pages, 5 figure

A distributed data component for the Open Modeling Interface

As the volume of collected data continues to increase in the environmental sciences, so too does the need for effective means for accessing those data. We have developed an Open Modeling Interface (OpenMI) data component that retrieves input data for model components from environmental information systems and delivers output data to those systems. The adoption of standards for both model component input–output interfaces and web services make it possible for the component to be reconfigured for use with different linked models and various online systems. The data component employs three techniques tailored to the unique design of the OpenMI that enable efficient operation: caching, prefetching, and buffering, making it capable of scaling to large numbers of simultaneous simulations executing on a computational grid. We present the design of the component, an evaluation of its performance, and a case study demonstrating how it can be incorporated into modeling studies

Технологія віртуалізації. Динамічна реконфігурація ресурсів обчислювального кластера

На основании выполненного анализа современных платформ аппаратно-программной виртуализации обоснована целесообразность использования и исследования виртуальных машин на платформе Microsoft Hyper-V R2 в качестве узлов вычислительного кластера. Концепция создания гибких гомогенных архитектур кластерных систем углублена за счет возможности формирования динамически реконфигурируемой кластерной вычислительной системы с использованием механизмов виртуализации платформы Microsoft Hyper-V. Показана актуальность использования аппаратной платформы персональных компьютеров и серверов для реконфигурации ресурсов вычислительных кластеров.На основі виконаного аналізу сучасних платформ апаратно-програмної віртуалізації обґрунтовано доцільність використання і дослідження віртуальних машин на платформі Microsoft Hyper-V R2 як вузлів обчислювального кластера. Концепцію створення гнучких гомогенних архітектур кластерних систем поглиблено за рахунок можливості формування динамічно реконфігурованої кластерної обчислювальної системи з використанням механізмів віртуалізації платформи Microsoft Hyper-V. Показано актуальність використання апаратної платформи персональних комп’ютерів і серверів для реконфігурації ресурсів обчислювальних кластерів.On the basis of performed analysis of modern hardware and software virtualization platforms it is proved the practicability of usage and researching of virtual machines on the Microsoft Hyper-V R2 platform as a compute cluster nodes. The concept of flexible homogeneous cluster architectures construction was expanded with ability of dynamically reconfigurable cluster computing system implementation using Microsoft Hyper-V technology virtualization features. The urgency of hardware platform of personal computers and servers for reconfiguration of the resources of computing clusters is shown

MPI Applications on Grids: A Topology-Aware Approach

Large Grids are build by aggregating smaller parallel machines through a public long-distance interconnection network (such as the Internet). Therefore, their structure is intrinsically hierarchical. Each level of the network hierarchy gives performances which differ from the other levels in terms of latency and bandwidth. MPI is the de facto standard for programming parallel machines, therefore an attractive solution for programming parallel applications on this kind of grids. However, because of the aforementioned differences of communication performances, the application continuously communicates back and forth between clusters, with a significant impact on performances. In this report, we present an extension of the information provided by the run-time environment of an MPI library, a set of efficient collective operations for grids and a methodology to organize communication patterns within applications with respect to the underlying physical topology, and implement it in a geophysics application

A New Multi-core CPU Resource Availability Prediction Model for Concurrent Processes

The efficiency of a multi-core architecture is directly related to the mechanisms that map the threads (processes in execution) to the cores. Determining the CPU resource availability of a multi-core architecture based on the characteristics of the threads that are in execution is the art of system performance prediction. Prediction of CPU resource availability is important in the context of making process assignment, load balancing, and scheduling decisions. In distributed infrastructure, CPU resources are allocated on demand for a chosen set of compute nodes. In this paper, a prediction model is derived for multi-core architectures and empirical evaluations are performed with real-world benchmark programs in a heterogeneous environment to demonstrate the accuracy of the proposed model. This model can be utilized in various time-sensitive applications like resource allocation in a cloud environment, task distribution (determining the order for faster processing time) in distributed systems, and others.Ye

All-Pairs Shortest-Paths for Large Graphs on the GPU

The all-pairs shortest-path problem is an intricate part in numerous practical applications. We describe a shared memory cache efficient GPU implementation to solve transitive closure and the all-pairs shortest-path problem on directed graphs for large datasets. The proposed algorithmic design utilizes the resources available on the NVIDIA G80 GPU architecture using the CUDA API. Our solution generalizes to handle graph sizes that are inherently larger then the DRAM memory available on the GPU. Experiments demonstrate that our method is able to significantly increase processing large graphs making our method applicable for bioinformatics, internet node traffic, social networking, and routing problems

The JVMCSP Runtime and Code Generator for ProcessJ in Java

The modern day advancements in multi-core technologies require programmers to use the right tools and languages to fully harness their potentials. On that front, our endeavor lies in developing a new multipro- cessing programming language. Concurrent or parallel programs can be hard to get right because of locks, monitors, mutexes, etc. One solution is using a CSP based process-oriented language. Process-oriented programming alleviates many of the problems found in thread and lock programming by proper encapsu- lation of data, explicit synchronous message passing, and the ability to verify code to be free of deadlocks and livelocks by using tools like FDR. Therefore, we have developed a new language called ProcessJ (CSP semantics and Java-like syntax) as a way to modernize languages like occam/occam-π which are outdated and only run on certain Linux distributions. ProcessJ is a multi-backend language with a compiler written in Java; and in this thesis, we focus on the JVM backend, which we call the JVMCSP; in particular, we consider code generation, the necessary runtime classes to support concurrency constructs on the JVM, and a simple cooperative non-preemptive scheduler. We also show how to translate ProcessJ source into Java source that makes use of the runtime classes that we have developed

MPI Applications on Grids: A Topology-Aware Approach

Large Grids are build by aggregating smaller parallel machines through a public long-distance interconnection network (such as the Internet). Therefore, their structure is intrinsically hierarchical. Each level of the network hierarchy gives performances which differ from the other levels in terms of latency and bandwidth. MPI is the de facto standard for programming parallel machines, therefore an attractive solution for programming parallel applications on this kind of grids. However, because of the aforementioned differences of communication performances, the application continuously communicates back and forth between clusters, with a significant impact on performances. In this report, we present an extension of the information provided by the run-time environment of an MPI library, a set of efficient collective operations for grids and a methodology to organize communication patterns within applications with respect to the underlying physical topology, and implement it in a geophysics application