Performance improvement of complementary feeders using static transfer switch system

The performance of complementary feeders, running in parallel, can be significantly improved by installing static transfer switches （STSs） at critical locations. We develop the STS control logic, which transfers the critical load from the preferred feeder to the alternate feeder when a voltage sag or a fault occurs on the preferred feeder. A forced commutation technique is proposed and implemented to turn off the preferred feeders＇ thyristor, thus avoiding cross current to flow and minimizing the transfer time. Simulation results show that the forced commutation technique is more effective as compared to the recently proposed time delay technique for STS operation. Two different feeders, namely New Exchange, the preferred feeder, and Sector 1-10/2, the alternate feeder of Islamabad Electric Supply COmpany （IESCO）, Pakistan, have been selected for case studies. The software PSCAD/EMTDC professional package has been used for simulation.     

A noise cross PSD estimator for dual-microphone speech enhancement based on minimum statistics

Some two-microphone noise reduction techniques that work in the frequency domain exploit coherence function between two noisy signals. They have shown good results when noise signals on two sensors are uncorrelated, but their performance decreases with correlated noises. Coherence based methods can be improved when the cross power spectral density （CPSD） of correlated noise signals is available. In this paper, we propose a new method for estimation of the CPSD of the noise, which is based on the minimum tracking technique. Despite the fact that the proposed estimator does not need to implement a voice activity detector （VAD）, its performance is comparable to a CPSD estimator that uses an ideal VAD.     

Evaluation of Oxidative Stress and DNA Damage in Benign Prostatic Hyperplasia Patients and Comparison with Controls

In the present study, oxidative stress and lymphocytic DNA damage in both pre-op and post-op benign prostrate hyperplasia (BPH) patients with age >50 years was evaluated and compared with normal healthy subjects (controls- without any evidence of disease) of the same sex and age group. From December 2007 to November 2009, oxidative stress in 45 BPH patients were evaluated both before (pre-op patients) and after 7 days of surgery (post-op patients) in terms of measurements of plasma levels of (1) various anti-oxidative enzymes, (2) non-enzymatic antioxidants and (3) malondialdehyde which is a product of lipid peroxidation. The lymphocyte DNA damage was also evaluated by single cell alkaline gel electrophoresis in terms of tail length migration in these patients. These values were compared with their respective control subjects of similar sex and age group. The activities of antioxidant enzymes and the levels of antioxidant, reduced glutathione were found significantly decreased (p < 0.05) in serum samples of pre-operative group of BPH patients as compared to the controls. These altered parameters increased significantly (p < 0.05) and returned to their near normal control values, but not up to baseline values, in post operative patients i.e. after the cancer load was decreased by surgery. Lymphocytic DNA damage was found to be significantly increased in pre-op group as compared to controls and was reduced after surgery in post-op group. The present study therefore, shows significantly increased levels of oxidative stress and DNA damage in BPH patients which were reduced after removal of tumour load. Thus oxidative damage plays an important role in prostate tumourogenesis and timely management of oxidative stress can be of importance in preventing the occurrence of BPH.     

如何应对网上短时学习需求高峰——学习成本节约策略研究

对多数开放大学来说,事实上,在许多大学中,总是会出现这样的情况,所有学生要在同一段时间内集中完成一些网上学习活动。这些活动通常造成学生在一定时间内蜂拥上网。由于学生较好的上网时间选择有限,网上学习拥挤高峰情况就会变得很糟。在通常情况下,只有那些最早上网的学生才能获得最佳在线学习机会。在马来西亚开放大学,当学生确认开设科目和占用网络槽口选择会面时间表的时候,往往就会出现网上使用高峰。大多数学生都会尽早赶去上网以确保能在时间安排表中获得网上会面的机会。那些可以利用的信息技术资源与功能,诸如互联网带宽和服务器等无法应付这些短时网络需求高峰。除非这些需求高峰得到满足,否则网络服务的速度将会迅速变慢,最终导致网络使用者排长队等候网络服务。假如可以提供超额的网络容量,要是可能的话,以确保这些短时需求高峰得到满足,那就不可能有成本效应。因为在大多数时间里,这些网络资源都没有得到充分利用。本论文着重探讨一些具有成本效应的方法以应对和满足短时网络高峰的需求。     

Is e-government a way to e-democracy?: A longitudinal study of the Iranian situation

Some scholars have supported e-government as a path to e-democracy, whereas others have been more cautious about the subject. In this article, we review the similarities between the concepts of e-government and e-democracy as well as evaluate e-government initiatives and e-democracy requirements in the case of Iran. We used a longitudinal study at two points in time to evaluate the path from e-government to e-democracy using two different methods: a systematic evaluation based on a checklist and a questionnaire survey. The trend of change in e-government initiatives was positive but low from 2008 to 2009, whereas the trend of change in e-democracy requirements was negative and substantial during the same period. We conclude that an emphasis on e-government as a way to e-democracy is not recommended in countries such as Iran.     

PF-BTS: A Privacy-Aware Fog-enhanced Blockchain-assisted task scheduling

In recent years, the deployment of Cloud Computing (CC) has become more popular both in research and industry applications, arising form various fields including e-health, manufacturing, logistics and social networking. This is due to the easiness of service deployment and data management, and the unlimited provision of virtual resources (VR). In simple scenarios, users/applications send computational or storage tasks to be executed in the cloud, by manually assigning those tasks to the available computational resources. In complex scenarios, such as a smart city applications, where there is a large number of tasks, VRs, or both, task scheduling is exposed as an NP-Hard problem. Consequently, it is preferred and more efficient in terms of time and effort, to use a task scheduling automation technique. As there are many automated scheduling solutions proposed, new possibilities arise with the advent of Fog Computing (FC) and Blockchain (BC) technologies. Accordingly, such automation techniques may help the quick, secure and efficient assignment of tasks to the available VRs. In this paper, we propose an Ant Colony Optimization (ACO) algorithm in a Fog-enabled Blockchain-assisted scheduling model, namely PF-BTS. The protocol and algorithms of PF-BTS exploit BC miners for generating efficient assignment of tasks to be performed in the cloud’s VRs using ACO, and award miner nodes for their contribution in generating the best schedule. In our proposal, PF-BTS further allows the fog to process, manage, and perform the tasks to enhance latency measures. While this processing and managing is taking place, the fog is enforced to respect the privacy of system components, and assure that data, location, identity, and usage information are not exposed. We evaluate and compare PF-BTS performance, with a recently proposed Blockchain-based task scheduling protocol, in a simulated environment. Our evaluation and experiments show high privacy awareness of PF-BTS, along with noticeable enhancement in execution time and network load.     

Student alienation at University level: Psychometric properties and relationship with student’s ICT motives

Education and Information Technologies - The purpose of this article is to develop a context-bound scale on student alienation around core problems experienced by students at the university level....     

Experiencing the community of inquiry framework using asynchronous online role-playing in computer-aided instruction class

Education and Information Technologies - This current study investigates the use of online role-playing, in an online discussion forum, in learning the community of inquiry framework – an...