Robust Power and Subcarrier Allocation for OFDM-based Cognitive Radio Networks Considering Spectrum Sensing Uncertainties

‎In this paper‎, ‎we address power and subcarrier allocation for cooperative cognitive radio (CR) networks in the presence of spectrum sensing errors‎. ‎First‎, ‎we derive the mutual interference of primary and secondary networks affecting each other by taking into account spectrum sensing errors‎. ‎Then‎, ‎taking into account the interference constraint imposed by the cognitive network to the primary user and the power budget constraint of cognitive network‎, ‎we maximize the achievable data rates of secondary users‎. ‎Besides‎, ‎in a multi secondary user scenario‎, ‎we propose a suboptimal but low complexity power and subcarrier allocation algorithm to solve the formulated optimization problem‎. ‎Our numerical results indicate that the proposed power loading scheme increases the cognitive achievable data rates compared to classical power loading algorithms that do not consider spectrum sensing errors‎

Effects of construction delays on construction project objectives

Delays can be defined as the late completion of works as compared to the planned schedule on the contract. Delays can be avoided or minimized only when their causes are identified. When delay occurred in to our project, it will have adverse consequences on project objectives in terms of time, cost and quality. The aim of the study reported in this paper was to identify the effects of delays that could threat project objectives in construction projects. A comprehensive literature review from various sources through books, conference proceedings, the internet, and civil engineering journals was made to carry out the study. According to delay categories that were contractor related, client related, consultant related, labor related and external related, the results of this study identified the six major effects of delay that were time overrun, cost overrun, dispute, arbitration, total abandonment, and litigation. The study also revealed that time and cost overruns were the frequent effects of delay. It is hoped that this study will become the foundation of further research in the area of project delays and mitigation measures

Acute vigabatrin-phenobarbitone-interaction on exploratory behaviour of rats

Vigabatrin (gamma-vinyl GABA) is an irreversible inh:bitor of the enzyme GABA-transaminase (GABA-T) which is responsible for the catabolism of the major inhibitory neurotransmitter gamma- aminobutyric acid (GABA) in the brain. Vigabatrin causes a several fold increase in the levels of brain GABA. The current study investigated further the effects of acute treatment with vigabatrin (100 mgl kg, i.p.) & phenobarbitone sodium (20 mg/kg, i.p.)f alone and in combination, in two rat behavioural models of exploratory activity: the elevated plus-maze model of anxiety and the open field test of locomotor activity. A single injection of vigabatrin or phenobarbitone alone, produced anxiolytic effects in the elevated plus-maze test and increased locomotor activity in the open field test. In contrast, after the concomitant administration of both drugs, the anxiolytic effects were no longer produced in the elevated plus-maze. The increased locomotor activity was also diminished in both tests of exploratory behaviour. These results shed light on the GABA hypothesis of anxiety, insofar as the increased availability of GABA, resulting from either GABA-T inhibition (vigabatrin) or facilitation of GABA-mediated chloride channels (phenobarbitone), seems to result in an increased emotional reactivity which, however, subsequently disappears during combined treatment.peer-reviewe

Analysis of Droplet Train/Moving Substrate Interactions in Ink-Jetting Processes

Ink-jetting technology has been applied to several processes in solid free-form fabrication (SFF) wherein droplets impinge onto a substrate to deposit the build material. Droplet impact behaviour on a surface has been the interest of many researchers; however, few studies have been undertaken to investigate the interaction of droplets with the moving substrate. This paper reports the impact behaviour of the droplets jetted at different frequencies onto a substrate moving over a range of velocities. The phenomena associated with the interaction were classified into three main regimes.Mechanical Engineerin

A new formalism for the estimation of the CP-violation parameters

In this paper, we use the time super-operator formalism in the 2-level Friedrichs model \cite{fried} to obtain a phenomenological model of mesons decay. Our approach provides a fairly good estimation of the CP symmetry violation parameter in the case of K, B and D mesons. We also propose a crucial test aimed at discriminating between the standard approach and the time super-operator approach developed throughout the paper

Developing Mitigation Measures for Delays in Building Construction Projects: A Case Study in the City of Esfahan

Developing mitigation measures are to avoid or minimize the magnitude of adverse consequences of delay causes that could threat the project objectives in terms of time, cost and quality. It is also vital to be aware of mitigation measures within the construction industry. The aim of the study reported in this paper is to develop mitigation measures for delays in building construction projects in the city of Isfahan, Iran. A questionnaire survey was used to carry out the study which was filled out by professional parties such as clients, contractors, architects, project managers, consultants and developers in the construction industry. Feedbacks from respondents gave variety of measures for each cause of delay to mitigate the adverse and disruptive consequences of delay causes in building construction projects in Isfahan. Time and cost overrun were the common negative effects of delays in building construction projects in Isfahan. The study has found that twenty one significant mitigation measures based on the different points of view from respondents of the questionnaire survey, in order to avoid or minimize the causes of delays in building construction projects in Isfahan, it has been proposed that the top six most effective mitigation measures of avoiding or minimizing these delays were further elaborated. This include: considering the clients views while providing designs, setting the project budget according to proper and accurate estimations, efficient and effective project management among the parties in the project, proper selection of competent and capable contractors appropriate for the project, appropriate delegating of project parties regarding to their specialties and skills and also having sufficient knowledge of project environment and project parties before the project starts. It is hope that this finding will be able to address issues and problems of delays in building construction projects in general in Iran

Modified Step Size for Enhanced Stochastic Gradient Descent: Convergence and Experiments

This paper introduces a novel approach to enhance the performance of the stochastic gradient descent (SGD) algorithm by incorporating a modified decay step size based on $\frac{1}{\sqrt{t}}$. The proposed step size integrates a logarithmic term, leading to the selection of smaller values in the final iterations. Our analysis establishes a convergence rate of $O(\frac{\ln T}{\sqrt{T}})$ for smooth non-convex functions without the Polyak-{\L}ojasiewicz condition. To evaluate the effectiveness of our approach, we conducted numerical experiments on image classification tasks using the FashionMNIST, and CIFAR10 datasets, and the results demonstrate significant improvements in accuracy, with enhancements of $0.5\%$ and $1.4\%$ observed, respectively, compared to the traditional $\frac{1}{\sqrt{t}}$ step size. The source code can be found at \\\url{https://github.com/Shamaeem/LNSQRTStepSize}