Pilot Aided Transmissions Technique to Achieve Optimal Effective Capacity Over Imperfect Channel Estimation in Cognitive Radio Networks

In cognitive radio networks, a secondary user (SU) can share the same frequency band with the primary user (PU) as long as the interference introduced to the later is below a predefined threshold. In this paper, the transmission performance in cognitive radio networks is studied assuming imperfect channel estimation, and taking quality of service (QoS) constraints into consideration. It is assumed that the cognitive transmitter can perform channel estimation and send the data at two different rates and power levels depending on the activity of the primary users. The existence of the primary user can be detected by channel sensing. A two-state Markov chain process is used to model the existence of the primary users. The cognitive transmission is also configured as a state transition model depending on whether the rates are higher or lower than the instantaneous rates values. This paper studies the maximum capacity of the cognitive user under the delay constraint. We use the new metric concept of effective capacity of the channel and introduce an optimization problem for rate and power allocation under interference power constraints. An numerical example illustrates the average effective capacity optimization and the impact of other system parameters.&nbsp

Effective Capacity Analysis for Cognitive Networks under QoS Satisfaction

Spectrum sensing and dynamic spectrum access (DSA) techniques in cognitive radio networks (CRN) have been extensively investigated since last decade. Recently, satisfaction of quality-of-service (QoS) demands for secondary users (SU) has attracted great attention. The SU can not only discover the transmission opportunities, but also cognitively adapts the dynamic spectrum access strategies to its own QoS requirement and the environment variations. In this paper, we study how the delay QoS requirement affects the strategy on network performance. We first treat the delay-QoS in interference constrained cognitive radio network by applying the effective capacity concept, focusing on the two dominant DSA schemes: underlay and overlay. We obtain the effective capacity of the secondary network and determine the power allocation policies that maximize the throughput of the cognitive user. The underlay and overlay approaches may have their respective advantages under diverse propagation environment and system parameters. If the cognitive network can dynamically choose the DSA strategy under different environment, its performance could be further improved. We propose a selection criterion to determine whether to use underlay or overlay scheme under the given QoS constraint and the PUs’ spectrum-occupancy probability. Thus, the throughput of the CRN could be increased. Performance analysis and numerical evaluations are provided to demonstrate the effective capacity of CRN based on the underlay and the overlay schemes, taking into consideration the impact of delay QoS requirement and other related parameters

Feasibility Study for Establishing a Restaurant in Jeddah

The primary purpose of this paper is to express an in-depth and comprehensive feasibility study for a gourmet restaurant in Jeddah since a feasibility study is crucial to the success of any business project. This study targets to explore the success of establishing a gourmet restaurant in Jeddah and to answer the question whether this business idea will continue successfully. We propose that the gourmet restaurant will comprise a signature store made brioche bread, as a novel idea. The business type needed, data regarding the gourmet restaurant industry and the history and development of brioche bread are basic information required. The feasibility study contains six categories: business strategy, market feasibility study, technical feasibility study, location and site selection study, social and an environmental feasibility study, and economic feasibility study. The market study addresses the requisite information on demand and supply, as well as the detailed information about competitors. The technical study contains the necessary machinery, production capacity, needed raw material and inputs, computer system(s) and human resources plans. Accordingly and based on quantitative selection criteria, the most suitable site was chosen. This study also identifies the impact on society and environment. The economic feasibility study recognizes the financial resources needed to channelize and operate the business and calculates all the economic performance indicators for the project

Sky Imager-Based Forecast of Solar Irradiance Using Machine Learning

Ahead-of-time forecasting of the output power of power plants is essential for the stability of the electricity grid and ensuring uninterrupted service. However, forecasting renewable energy sources is difficult due to the chaotic behavior of natural energy sources. This paper presents a new approach to estimate short-term solar irradiance from sky images. The~proposed algorithm extracts features from sky images and use learning-based techniques to estimate the solar irradiance. The~performance of proposed machine learning (ML) algorithm is evaluated using two publicly available datasets of sky images. The~datasets contain over 350,000 images for an interval of 16 years, from 2004 to 2020, with the corresponding global horizontal irradiance (GHI) of each image as the ground truth. Compared to the state-of-the-art computationally heavy algorithms proposed in the literature, our approach achieves competitive results with much less computational complexity for both nowcasting and forecasting up to 4 h ahead of time.Comment: Published in MDPI Electronics Journa

Effective Capacity in Broadcast Channels with Arbitrary Inputs

We consider a broadcast scenario where one transmitter communicates with two receivers under quality-of-service constraints. The transmitter initially employs superposition coding strategies with arbitrarily distributed signals and sends data to both receivers. Regarding the channel state conditions, the receivers perform successive interference cancellation to decode their own data. We express the effective capacity region that provides the maximum allowable sustainable data arrival rate region at the transmitter buffer or buffers. Given an average transmission power limit, we provide a two-step approach to obtain the optimal power allocation policies that maximize the effective capacity region. Then, we characterize the optimal decoding regions at the receivers in the space spanned by the channel fading power values. We finally substantiate our results with numerical presentations.Comment: This paper will appear in 14th International Conference on Wired&Wireless Internet Communications (WWIC

CHARACTERIZATION AND ANAEROBIC TREATMENT OF BIOLOGICAL AND PHYSICOCHEMICAL SLUDGE FROM A MOROCCAN DAIRY INDUSTRY

The physicochemical and biological sludge (PCS and BS) from a Moroccan dairy industry, constitute a source of organic matter that is ranging between 50 to 90%. The composition of this sludge is very specific because they were derived from an effluent mixture (milk, orange ...). Assessment of anaerobic digestion for treating these wastes showed the promising results in terms of methane production and organic pollution removal. Indeed, the methane yields were 5.601 and 20.79 mlSTP.gVS-1 gave respectively by BS and PCS for the maximal load (100% of substrate). The total solid and volatile solid reduction reached to 79.63 and 83.60% for BS while it reached 87.064% and 89.161% for PCS for the same load (100% of sludge)

understanding and tackling poverty and vulnerability in mountain livelihoods in the hindu kush himalaya

This chapter critically reviews the existing knowledge on livelihoods, poverty, and vulnerability in the Hindu Kush Himalaya (HKH). Development in mountain areas and the practices of people in these areas are uniquely conditioned by distinct characteristics that we term "mountain specificities". Some of these specificities—such as inaccessibility, fragility, and marginality—constrain development. Others—such as abundant biological diversity, ecological niches, and adaptation mechanisms—present development opportunities for mountain people

Application of heat pipe technology in permanent mold casting of nonferrous alloys

The issue of mold cooling is one, which presents a foundry with a dilemma. On the one hand; the use of air for cooling is safe and practical, however, it is not very effective and high cost. On the other hand, water-cooling can be very effective but it raises serious concerns about safety, especially with a metal such as magnesium. An alternative option that is being developed at McGill University uses heat pipe technology to carry out the cooling.The experimental program consisted of designing a permanent mold to produce AZ91E magnesium alloy and A356 aluminum alloy castings with shrinkage defects. Heat pipes were then used to reduce these defects. The heat pipes used in this work are novel and are patent pending. They are referred to as McGill Heat Pipes.Computer modeling was used extensively in designing the mold and the heat pipes. Final designs for the mold and the heat pipes were chosen based on the modeling results.Laboratory tests of the heat pipe were performed before conducting the actual experimental plan. The laboratory testing results verified the excellent performance of the heat pipes as anticipated by the model.An industrial mold made of H13 tool steel was constructed to cast nonferrous alloys. The heat pipes were installed and initial testing and actual industrial trials were conducted. This is the first time where a McGill heat pipe was used in an industrial permanent mold casting process for nonferrous alloys.The effects of cooling using heat pipes on AZ91E and A356 were evaluated using computer modeling and experimental trials. Microstructural analyses were conducted to measure the secondary dendrite arm spacing, SDAS, and the grain size to evaluate the cooling effects on the castings. The modeling and the experimental results agreed quite well. The metallurgical differences between AZ91E and A356 were investigated using modeling and experimental results. Selected results from modeling, laboratory and industrial trials are presented. The results show a promising future for heat pipe technology in cooling permanent molds for the casting of nonferrous alloys

Etude de l'insertion d'hydrures alcalins dans le graphite

SIGLECNRS T 57974 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc