Packet Relaying Control in Sensing-based Spectrum Sharing Systems

Cognitive relaying has been introduced for opportunistic spectrum access systems by which a secondary node forwards primary packets whenever the primary link faces an outage condition. For spectrum sharing systems, cognitive relaying is parametrized by an interference power constraint level imposed on the transmit power of the secondary user. For sensing-based spectrum sharing, the probability of detection is also involved in packet relaying control. This paper considers the choice of these two parameters so as to maximize the secondary nodes' throughput under certain constraints. The analysis leads to a Markov decision process using dynamic programming approach. The problem is solved using value iteration. Finally, the structural properties of the resulting optimal control are highlighted

Adaptive Modulation in Multi-user Cognitive Radio Networks over Fading Channels

In this paper, the performance of adaptive modulation in multi-user cognitive radio networks over fading channels is analyzed. Multi-user diversity is considered for opportunistic user selection among multiple secondary users. The analysis is obtained for Nakagami-$m$ fading channels. Both adaptive continuous rate and adaptive discrete rate schemes are analysed in opportunistic spectrum access and spectrum sharing. Numerical results are obtained and depicted to quantify the effects of multi-user fading environments on adaptive modulation operating in cognitive radio networks

Protocol Design and Stability Analysis of Cooperative Cognitive Radio Users

A single cognitive radio transmitter--receiver pair shares the spectrum with two primary users communicating with their respective receivers. Each primary user has a local traffic queue, whereas the cognitive user has three queues; one storing its own traffic while the other two are relaying queues used to store primary relayed packets admitted from the two primary users. A new cooperative cognitive medium access control protocol for the described network is proposed, where the cognitive user exploits the idle periods of the primary spectrum bands. Traffic arrival to each relaying queue is controlled using a tuneable admittance factor, while relaying queues service scheduling is controlled via channel access probabilities assigned to each queue based on the band of operation. The stability region of the proposed protocol is characterized shedding light on its maximum expected throughput. Numerical results demonstrate the performance gains of the proposed cooperative cognitive protocol.Comment: Accepted in WCNC 201

Maximum Throughput of a Cooperative Energy Harvesting Cognitive Radio User

In this paper, we investigate the maximum throughput of a saturated rechargeable secondary user (SU) sharing the spectrum with a primary user (PU). The SU harvests energy packets (tokens) from the environment with a certain harvesting rate. All transmitters are assumed to have data buffers to store the incoming data packets. In addition to its own traffic buffer, the SU has a buffer for storing the admitted primary packets for relaying; and a buffer for storing the energy tokens harvested from the environment. We propose a new cooperative cognitive relaying protocol that allows the SU to relay a fraction of the undelivered primary packets. We consider an interference channel model (or a multipacket reception (MPR) channel model), where concurrent transmissions can survive from interference with certain probability characterized by the complement of channel outages. The proposed protocol exploits the primary queue burstiness and receivers' MPR capability. In addition, it efficiently expends the secondary energy tokens under the objective of secondary throughput maximization. Our numerical results show the benefits of cooperation, receivers' MPR capability, and secondary energy queue arrival rate on the system performance from a network layer standpoint.Comment: Part of this paper was accepted for publication in PIMRC 201

Flight evaluations of sliding mode fault tolerant controllers

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordThis paper considers the development of fault tolerant controllers (FTC) and their application to aerospace system. In particular, given the extensive and growing literature in this area, this paper focusses on methods where the schemes have been implemented and flight tested. One thread of the fault tolerant control literature has involved sliding mode controllers. This paper considers a specific class of sliding mode FTC which incorporates control allocation to exploit over-actuation (which is typically present in aerospace systems). The paper describes implementations of these ideas on a small quadrotor UAV and also piloted flight tests on a full-scale twin-engined aircraft

Strut and Tie Modeling for RC Deep Beams under non-Central Loadings

This work aims at presenting detailed procedures companied by numerical examples for analyzing and designing reinforced concrete deep beams that subjected to non-central loadings based on Strut and Tie method (STM). The subjected loadings were moved from the center of the beam span towards the supports reaching the maximum non-centrality could be achieved (after which the beams became ‘not deep’ from ACI 318M-14 point of view). A total of three deep beams with three different types of loadings were taken into considerations; one concentrated force, two concentrated forces and uniformly distributed load. Every specimen had a cross section of 150  400 mm and a total length of 1000 mm. Generally, it was found that moving load from the span center towards one of the supports leads to worth notable decreases in the beam ultimate capacity. Therefore, in the case of one-concentrated force, the ultimate load capacity decreased by 30.2% when left shear span to effective depth ratio (aL/d) decreased from 1.3 to 0.65. While in the cases of two-concentrated forces or uniformly distributed loading, it was found that changing (aL/d) ratio from 1.02 to 0.37 led to decrease the deep beam ultimate capacity by 30.5%

E-Integrated Marketing Communication and its impact on Customers' Attitudes

This study aims to investigate the impact of E-integrated marketing communication (E-IMC) on customers' attitudes toward electronic products. In order to achieve the objectives of the study, the researchers deployed the descriptive analytical approach due to its relevance to this kind of research. The sample was purposive random sample of online customers who are exposed to E-IMC in the context of electronic products in Jordan; 547 questionnaires were distributed, 498 questionnaires were collected back and 455 questionnaires were accepted. The research included two main variables with sub dimensions; E-IMC as the independent variable, customers' attitudes toward electronic products representing the dependent variable.. E-IMC sub dimensions were online advertising (OD), online public relations (OPR) and online sales promotion (OSP. Results revealed that there is a statistically significant relationship between E-integrated marketing communication (E-IMC) and customers' attitudes toward electronic products. In the light of the results, possible managerial implications are discussed  and future research subjects are recommended. Keywords: E-Integrated Marketing Communication (E-IMC), Customers' Attitudes,  Electronic Companies, Jordan

The Impact of the Green Supply Chain Management on Environmental – Based Marketing Performance: Case study Nuqul Group Companies in Jordan

This study aims to investigate “The impact of  the Green Supply Chain Management” (GSCM)  on Environmental – Based Marketing Performance. In order to achieve the objectives of the study, the researchers deployed the descriptive analytical approach due to its relevance to this kind of research. The sample used in this study is the stratified convenience sampling, where the study targeted the top and middle managerial levels from the population, and the targeted managerial levels was made up of (167) employees in the five companies. 125 questionnaires  were distributed for the five companies with  (25) questionnaires for each company. The accepted questionnaire was (96).  The results of the research showed that the elements of the Green Supply Chain Management "Internal Environmental Management, Green Purchasing, Green Information Systems, Cooperation with Customers, Eco-Design and Packaging, and Investment Recovery" practices affect the environmental – based marketing performance. The results showed the most element with significant impact on the environmental – based marketing performance was internal environmental management. Keywords: Green Supply Chain Management, Marketing Performance, Nuqul Group Companies, Jordan

Phosphorus Loss into Ground Water in Paddy Soils as Influenced by Irrigation System and Rate of Added-P

A field experiment was carried out in delta Nile region of Egypt, to elucidate the impact of irrigation system and graded phosphorus fertilizer rates on P loss into ground water in paddy soils (heavy clay soil). Three irrigation system were used: submergence with continuous head of water (about 8 cm), irrigation with saturation percent and discontinous irrigation where soil was irrigated every 7 days. The rate of applied P were 45 and 90 Kg P2O5/acre as super phosphate. Values of dissolved reactive phosphorus (DRP) in ground water increased under saturation and discontinuous irrigation compared to it under submergence condition (e.g.,0.25,0.18 and 0.14 mg P/L, respectively) under 90 Kg P2O5 /ac. and after 15 days of added-P. Accumulation values of DRP in ground water after 105 days at 90 Kg P2O5 /ac. of added-P were 1.18,0.76 and 0.67 mg P/L under saturation, discontinuous and submergence irrigation methods, respectively. The rate of loss for DRP in ground water was the highest under saturation method at 90 Kg P2O5 /ac. ( 0.01 mg P/L/day). Results also showed that, accumulated total phosphorus (TP) at the end of ground water collection (105 days after transplanting) when 90 Kg P2O5 /ac. was added were 2.78,2.18 and 1.69 mg P/L under discontinuous, saturation and submergence irrigation system, respectively. Also, the rate of loss for TP was the highest under discontinuous irrigation condition (0.025 mg P/L). These results indicated that, increasing added phosphorus fertilizer let to increasing P loss into ground water by leaching through the soil profile.In addition, phosphorus loss into ground water was increased with decreasing added water for irrigation in paddy soils (increasing drought regime) and that was not expected

Development of novel formulations to enhance in vivo transdermal permeation of tocopherol

Tocopherol represents a big challenge for transdermal permeation owing to its extreme hydrophobicity and large molecular mass. The aim of the present study was to develop alpha-tocopherol (T) topical formulations and evaluate the ex vivo and in vivo permeation. Franz diffusion cells were used for the ex vivo permeation, and neonatal rats were used for in vivo permeation. Seven gel formulations and 21 liquid formulations were investigated for physical stability, viscosity and permeation of T. Analysis of T was performed by a validated HPLC method using a UV detector.The ex vivo permeation from gel and emulsion formulations was very poor (0.001–0.015 %). The highest permeation was observed from monophasic liquid formulations containing dimethyl sulfuxide (DMSO), tocopheryl polyethylene glycols (TPGs), propylene glycol, ethanol, and 9.5 % T. The in vivo results demonstrated higher retention in the epidermis compared to subcutaneous tissues; 1377 and 1.13 µg g–1, respectively. Increasing T concentration from 4.8 to 9.5 % did not increase the amount permeated or % of T retained. It was concluded that simple solutions of T in presence of DMSO and TPGs are more promising systems for effective transdermal permeation; compared to gel, emulsion or oleaginous systems