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Search Results: 1 - 10 of 19295 matches for " Tara Ali-Yahiya "
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Fractional Frequency Reuse for Hierarchical Resource Allocation in Mobile WiMAX Networks
Ali-Yahiya Tara,Chaouchi Hakima
EURASIP Journal on Wireless Communications and Networking , 2010,
Abstract: We propose a frequency planning based on zone switching diversity scheme for multicell OFDMA mobile WiMAX networks. In our approach, we focus on the use of Fractional Frequency Reuse (FFR) for guaranteeing the quality of service for the different service flows in the system. We investigate an architecture that coordinates the allocation of resources in terms of slots (the basic allocation unit in time and frequency domain in an OFDMA frame) between the Radio Resource Controller (RRC) and the Radio Resource Agent (RRA) which resides in the Base Station (BS). The proposed algorithm attempts to capture three types of diversity, namely, mutual interference diversity, traffic diversity, and selective fading channel diversity. As a consequence, the proposed algorithm for slot allocation makes a trade-off between maximizing overall throughput of the system while guaranteeing the Quality of Service (QoS) requirements for a mixture of real-time and non-real-time service flows under different diversity configurations. Our algorithm is evaluated under various cell configurations and traffic models. The results reveal important insights on the trade-off between cell interference suppression and QoS assurance.
Fractional Frequency Reuse for Hierarchical Resource Allocation in Mobile WiMAX Networks
Tara Ali-Yahiya,Hakima Chaouchi
EURASIP Journal on Wireless Communications and Networking , 2010, DOI: 10.1155/2010/363065
Abstract: We propose a frequency planning based on zone switching diversity scheme for multicell OFDMA mobile WiMAX networks. In our approach, we focus on the use of Fractional Frequency Reuse (FFR) for guaranteeing the quality of service for the different service flows in the system. We investigate an architecture that coordinates the allocation of resources in terms of slots (the basic allocation unit in time and frequency domain in an OFDMA frame) between the Radio Resource Controller (RRC) and the Radio Resource Agent (RRA) which resides in the Base Station (BS). The proposed algorithm attempts to capture three types of diversity, namely, mutual interference diversity, traffic diversity, and selective fading channel diversity. As a consequence, the proposed algorithm for slot allocation makes a trade-off between maximizing overall throughput of the system while guaranteeing the Quality of Service (QoS) requirements for a mixture of real-time and non-real-time service flows under different diversity configurations. Our algorithm is evaluated under various cell configurations and traffic models. The results reveal important insights on the trade-off between cell interference suppression and QoS assurance.
A QoS-Aware Mesh Protocol for Future Home Networks Using Autonomic Architecture
Sethom Kaouthar,Ali-Yahiya Tara,Laga Nassim,Pujolle Guy
EURASIP Journal on Wireless Communications and Networking , 2008,
Abstract: Autonomic networking is an emerging approach for the research community to engineer systems and architectures that will increase the quality of service (QoS) and robustness of future network architectures. In this article, we investigate the key concept of adding a knowledge plane to enable the automated control and management of home resources taking into account wireless mesh topology basis. This new supplementary plane helps to make an intelligent decision to select network paths that have sufficient resources to satisfy the QoS requirements of the admitted connections.
On the Minimization of Handover Decision Instability in Wireless Local Area Networks
Meriem Abid,Tara Ali Yahiya,Guy Pujolle
International Journal of Computer Networks & Communications , 2010,
Abstract: This paper addresses handover decision instability which impacts negatively on both user perception andnetwork performances. To this aim, a new technique called The HandOver Decision STAbility Technique(HODSTAT) is proposed for horizontal handover in Wireless Local Area Networks (WLAN) based onIEEE 802.11standard. HODSTAT is based on a hysteresis margin analysis that, combined with a utilitybasedfunction, evaluates the need for the handover and determines if the handover is needed or avoided.Indeed, if a Mobile Terminal (MT) only transiently hands over to a better network, the gain from usingthis new network may be diminished by the handover overhead and short usage duration. The approachthat we adopt throughout this article aims at reducing the minimum handover occurrence that leads tothe interruption of network connectivity (this is due to the nature of handover in WLAN which is a breakbefore make which causes additional delay and packet loss). To this end, MT rather performs a handoveronly if the connectivity of the current network is threatened or if the performance of a neighboringnetwork is really better comparing the current one with a hysteresis margin. This hysteresis should makea tradeoff between handover occurrence and the necessity to change the current network of attachment.Our extensive simulation results show that our proposed algorithm outperforms other decision stabilityapproaches for handover decision algorithm.
On the Minimization of Handover Decision Instability in Wireless Local Area Networks
Meriem Abid,Tara Ali Yahiya,Guy Pujolle
Computer Science , 2010, DOI: 10.5121/ijcnc.2010.2304
Abstract: This paper addresses handover decision instability which impacts negatively on both user perception and network performances. To this aim, a new technique called The HandOver Decision STAbility Technique (HODSTAT) is proposed for horizontal handover in Wireless Local Area Networks (WLAN) based on IEEE 802.11standard. HODSTAT is based on a hysteresis margin analysis that, combined with a utilitybased function, evaluates the need for the handover and determines if the handover is needed or avoided. Indeed, if a Mobile Terminal (MT) only transiently hands over to a better network, the gain from using this new network may be diminished by the handover overhead and short usage duration. The approach that we adopt throughout this article aims at reducing the minimum handover occurrence that leads to the interruption of network connectivity (this is due to the nature of handover in WLAN which is a break before make which causes additional delay and packet loss). To this end, MT rather performs a handover only if the connectivity of the current network is threatened or if the performance of a neighboring network is really better comparing the current one with a hysteresis margin. This hysteresis should make a tradeoff between handover occurrence and the necessity to change the current network of attachment. Our extensive simulation results show that our proposed algorithm outperforms other decision stability approaches for handover decision algorithm.
Modelling Irrigation and Salinity Management Strategies in the Ord Irrigation Area  [PDF]
Riasat Ali, John Byrne, Tara Slaven
Natural Resources (NR) , 2010, DOI: 10.4236/nr.2010.11005
Abstract: The Ord River Irrigation Area (ORIA) is located within northern Western Australia near the Northern Territory border. Since the beginning of irrigated agriculture in the ORIA the groundwater levels have been continuously rising and are now close to the soil surface in some parts of ORIA in northern Western Australia. The groundwater is now saline throughout most of the ORIA and soil salinity risks are high where the watertables are shallow. This research evaluated irrigation and salinity management strategies for sugarcane and maize crops grown over deep and shallow, non-saline and saline watertables in the ORIA. The LEACHC model, calibrated using field data, was used to predict the impacts of various irrigation management strategies on water use and salt accumulation in the root zone. This study concluded that irrigation application equal to 100% of total fortnightly pan evaporation applied at 14 day intervals was a good irrigation strategy for the maize grown over a deep watertable area. This strategy would require around 11 ML/ha of irrigation water per growing season. Irrigation application equal to 75% of total fortnightly pan evaporation, applied every fortnight during first half of the growing season, and 75% of total weekly pan evaporation, applied on a weekly basis during second half of the growing season, would be the best irrigation strategy if it is feasible to change the irrigation interval from 14 to seven days. This irrigation strategy is predicted to have minimal salinity risks and save around 40% irrigation water. The best irrigation strategy for sugarcane grown on Cununurra clay over a deep watertable area would be irrigation application equal to 50% of the total fortnightly pan evaporation, applied every fortnight during first quarter of the growing season, and irrigation application amounts equal to 100% of total weekly pan evaporation, applied every week during rest of the season. The model predicted no soil salinity risks from this irrigation strategy. The best irrigation strategy for sugarcane over a non-saline, shallow watertable of one or two m depth would be irrigation application amounts equal to 50% of total fortnightly pan evaporation applied every fortnight. In the case of a saline watertable the same irrigation strategy was predicted to the best with respect to water use efficiency but will have high salinity risks without any drainage management.
Managing Computing Infrastructure for IoT Data  [PDF]
Sapna Tyagi, Ashraf Darwish, Mohammad Yahiya Khan
Advances in Internet of Things (AIT) , 2014, DOI: 10.4236/ait.2014.43005
Abstract:
Digital data have become a torrent engulfing every area of business, science and engineering disciplines, gushing into every economy, every organization and every user of digital technology. In the age of big data, deriving values and insights from big data using rich analytics becomes important for achieving competitiveness, success and leadership in every field. The Internet of Things (IoT) is causing the number and types of products to emit data at an unprecedented rate. Heterogeneity, scale, timeliness, complexity, and privacy problems with large data impede progress at all phases of the pipeline that can create value from data issues. With the push of such massive data, we are entering a new era of computing driven by novel and ground breaking research innovation on elastic parallelism, partitioning and scalability. Designing a scalable system for analysing, processing and mining huge real world datasets has become one of the challenging problems facing both systems researchers and data management researchers. In this paper, we will give an overview of computing infrastructure for IoT data processing, focusing on architectural and major challenges of massive data. We will briefly discuss about emerging computing infrastructure and technologies that are promising for improving massive data management.
Editorial
Tara Dehpour,Mani Ali Reza,Shahram Ejtemaeimehr,Dehpour Ahmad Reza
Physiology and Pharmacology , 2006,
Abstract:
Epidemiology of nocturnal enuresis in basic schoolchildren in Aden Governorate, Yemen
Yousef Khalida,Basaleem Huda,Yahiya Mariam
Saudi Journal of Kidney Diseases and Transplantation , 2011,
Abstract: Nocturnal enuresis is a common problem among children and adolescents. Data regarding this problem in schoolchildren in Yemen are scarce. This study was aimed to determine the prevalence of nocturnal incontinence in Aden school going children, describe its severity and identify the relation between nocturnal enuresis with personal and family characteristics. The study was a cross-sectional survey conducted on the public basic schoolchildren in Aden, Yemen, in the period November 2007-April 2009. A random, multistage sample of 890 students was taken from four districts in eight schools and divided into two strata: males and females. Data were obtained by using pre-recoded questionnaire, which was completed by parents. The response rate was 73.7% (656 students); 113 (17.2%) cases of nocturnal enuresis were encountered. Nocturnal enuresis de-creased by age from 31.5% at 6-8 years to 8.7% at 15+ years (P < 0.05). Primary nocturnal enuresis affected 76.1%, of which the majority of children were bedwetting every night. Positive family history of nocturnal enuresis, deeper sleep, daytime enuresis, tea drinking, being non working father or with less education showed significant association with the occurrence of enuresis in the students. Stressful events in the previous 6 months of the study were twice more frequently noted. The study concluded that the prevalence of nocturnal enuresis in Aden public school children and its associated factors are almost comparable with that reported in epidemiological studies from various countries. Health education will encourage the parents to be aware, cope with this problem and seek appropriate medical advice.
(3E,5E)-3,5-Dibenzylidene-1-phenethylpiperidin-4-one
Mohamed Ashraf Ali,Tan Soo Choon,Abdulrahman I. Almansour,Tara Shahani
Acta Crystallographica Section E , 2011, DOI: 10.1107/s1600536811035744
Abstract: In the title compound, C27H25NO, the piperidine ring adopts an envelope conformation with the N atom at the flap position. The two benzylidene-benzene rings are oriented at a dihedral angle of 8.5 (1)°. In the crystal, the molecules are linked into centrosymmetric dimers by pairs of intermolecular C—H...O hydrogen bonds. The dimers are connected via C—H...π interactions involving the phenyl rings.
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