Cooperative Spectrum Sensing Using Random Matrix Theory

In this paper, using tools from asymptotic random matrix theory, a new cooperative scheme for frequency band sensing is introduced for both AWGN and fading channels. Unlike previous works in the field, the new scheme does not require the knowledge of the noise statistics or its variance and is related to the behavior of the largest and smallest eigenvalue of random matrices. Remarkably, simulations show that the asymptotic claims hold even for a small number of observations (which makes it convenient for time-varying topologies), outperforming classical energy detection techniques.Comment: Submitted to International Symposium on Wireless Pervasive Computing 200

Asymptotic Independence in the Spectrum of the Gaussian Unitary Ensemble

Consider a $n \times n$ matrix from the Gaussian Unitary Ensemble (GUE). Given a finite collection of bounded disjoint real Borel sets $(\Delta_{i,n},\ 1\leq i\leq p)$, properly rescaled, and eventually included in any neighbourhood of the support of Wigner's semi-circle law, we prove that the related counting measures$({\mathcal N}_n(\Delta_{i,n}), 1\leq i\leq p)$, where${\mathcal N}_n(\Delta)$represents the number of eigenvalues within$\Delta$, are asymptotically independent as the size$n$goes to infinity,$p$ being fixed. As a consequence, we prove that the largest and smallest eigenvalues, properly centered and rescaled, are asymptotically independent; we finally describe the fluctuations of the condition number of a matrix from the GUE.Comment: 15 page

Evaluation of water use in a rice double cropping system in Malaysia

Irrigated rice all over Asia has been criticized for inefficient water use, but very little information is available to quantify its performance. The quantification or assessment of the inefficiency will give the farmers, managers or schemes and policy makers to come up with remedial measures. In this work, the Besut rice irrigation scheme, located in the Terengganu State of Malaysia was characterized, and its water use (WU) efficiency assessed. The daily rainfall for 48 years and river flows for 45 years were analyzed to identify water excess or shortage throughout the rice-growing season. During the November-January period, 45% of the total annual rains fall. The irrigation water supply could be reduced in the main season (November-April) because of higher rainfall occurrence. Low monthly river flows of 10.5 m3/s and 10.9 m3/s were observed for the Besut barrage and 2.3 m3/s and 2.4 m3/s for the Angga barrage in the months of July and August respectively, characterizing the driest months. The off-season (May-October) crop suffered from water problems during vegetative and reproductive stages because of water shortage in the river. The relative water supply values have been classified into five categories based on results on the indices on irrigation performance. The average water productivity was 0.31 kg/m3 and 0.25 kg/m3 during the main season and off-season respectively. Two WU indices, water productivity (WPI) and adequacy (AI), ranked the performance of the blocks and identified those having problems in water allocation and utilization. These indices revealed that the blocks using more water performed poorly in terms of water productivity. These indices could be used to rectify uneven distribution of water in the scheme

Compliance with standards and immerging issues of household sewage disposal systems in Gampaha Municipality Area in Western Sri Lanka

Urban centers are highly significant with limited space together with the rising urban population. Most of the houses and buildings are attached with some kind of a sewage disposal facility as central sewage disposal systems are limited. Urbanization is expected to create many problems in terms of black water disposal due to limitation of land. A study was done in Gampaha municipality area, an urban center, where there is no central sewage treatment facility. The objectives of the study were to analyze the current situation of the black water disposal system in the study area and to identify the shortcomings of the black water disposal system comparing with the standards. The study was conducted within the urban center in five GN divisions. Random samples of 44 households were selected to represent all the five GN divisions. Selected households were interviewed to collect basic data needed and physical measurements were also taken where necessary. The data categories collected are household information, toilet type and size, desludging interval and distance to nearest well. The code of practice for the design and construction of septic tanks reports that 80% of urban communities use septic tanks for sewage disposal, but this study reveals that only 18% of the population uses septic tanks. Over 82% uses typical soakage pits that are constructed with loosely constructed brick walls and bare bottom open to soil for their sewage disposal. Over 68% of the households have their toilet pits within 15m to the nearest well, which is below the recommended distance. Only 30% of the households comply with over 15m to the nearest well that is recommended for septic tanks. The recommended distance for the soakage pits to the nearest well is 30m and only 9% of the households meet this standard. The black water disposal pits are over sized in general, so that the desludging interval is more than 10 years. Recently constructed houses, due to limitation of space, have reduced the size of the pits reducing the size of desludging interval. The construction and placement of septic tanks or soakage pits in the area have not complied with the standards

Irrigation energy consumption in a tropical lowland rice field

Available and limited water resources are seeing high demand from many sectors such as agriculture, industry and domestic households. In water allocation, the quantification of water in terms of energy used for water supply is more appropriate in terms of economic aspects. This study was undertaken to assess the embodied in irrigation for a lowland tropical rice production system. The irrigation energy requirements for the off and main cropping seasons were estimated based on crop water requirements at different cropping stages. Experimental results indicate that there are significant differences among the irrigation energy requirements of the various cropping stages, with the highest values of 4625.34 MJ ha-1 and 3843.93 MJ ha-1 observed for the mid-season stage in the off-season and main season, respectively. The off-season irrigation energy requirements for the rice variety MR 219 were found to be 32.6%, 26.8%, 20.3% and 271.7% higher than the mainseason for the initial stage, crop development stage, mid-season stage and late-s eason stage, respectively. There is a significant difference in irrigation energy requirement among the seasons and crop growth stages. Crop Water Use Efficiency (CWUE) in the off season (0.26 kg/m3 ) is higher than the CWUE in the main season(0.23kg/m3) which is attributed to better water management and yields during the off season due to water shortage. Irrigation energy productivity (IEP) of rice in the off season and the main season at Tanjong Karang is 0.26 and 0.29, respectively. In terms of irrigation energy spent, the main season shows better performance where a part of irrigation requirement is met by rainfall. Irrigation energy, CWUE and IEP can be used in decision making on the profitability of growing rice in different seasons

Sustainability of rice production: a Malaysian perspective

As Asian rice demand is projected to increase by 30% in 2010, a sustainable approach of rice production has become important. In order to fulfill the rice demand for the growing population and with the target rice self-sufficiency of 65%, Malaysia has to increase its rice productivity. As the attainment of sustainability in rice farming is country and area specific, Malaysia has devised its own ways to achieve this goal within a prescribed time frame. The major problems faced by the rice sector have been identified and step-by-step solutions are sought through policy changes. Rice estates in Malaysia have already proven that commercial rice production is viable, economical and sustainable. FELCRA Seberang Perak, the first and largest rice estate in Malaysia, has proven the sustainability and viability of commercial rice farming by achieving a continuous cropping intensity of 200%. The keywords to sustainable rice production are doubling yields, estatization and private corporate sector investments. The strategies to be devised must include getting investments to make the present non-lucrative business a profitable venture, whilst balancing the country’s social obligation

LPWM expert: An expert system for water management during land preparation in a paddy estate in Malaysia.

Seberang Perak paddy estate, Malaysia, which practices intensive mechanized farming still uses the traditional approach in decision-making. Water management during land preparation, the critical process to be completed within scheduled duration, needs better and quick management decisions for many alternative scenarios. A method proposed to encapsulate specific knowledge available with domain experts and generated through modeling to an expert system (Land Preparation Water Management (LPWM) Expert) is outlined. The LPWM expert consists a database, a model base, a knowledge base and a user interface. Knowledge was gathered through discussions and interviews with domain experts. Collected quantitative data were used in modeling canal flows and water balance to extract knowledge for different possible scenarios. Knowledge base represent extracted knowledge as rules. All the rules in IF-THEN structure and syntax are verified with the help of wxCLIPS debugging capability. The results generated by the LPWM expert are validated with the domain experts. The expert system proposes decisions for many combinations of scenarios considering all the possible variations in rain, irrigation water supply, secondary blocks, sub-estates, cropping seasons and cropping intensity. The LPWM expert is user friendly and efficient where the outputs are supported with graphics

Water use efficiency of potato (Solanum tuberosum L.) under different irrigation methods and potassium fertilizer rates

AbstractThis study was conducted to determine the effect of different irrigation methods and potassium fertilizers on potato yield in the Abu–Graib–Baghdad, Iraq Region, during season 2011–2012. Potato was grown under furrow and drip irrigation methods and three potassium fertilizers rates applied with 0.0, 300 and 600kg K2SO4ha−1. The obtained results indicated that, actual potato evapotranspiration ranged from 357.3 to 511.4mm in the growth season for all treatments. Furrow and drip irrigation methods had no significant effect on tuber yield under the experiential conditions. Potassium fertilizer influenced the tuber yield (P<0.05), and the highest tuber yield was registered for 600kg K2SO4ha−1, reaching 35.23Tha−1and 36.65Tha−1for furrow and drip irrigation, respectively. Water use efficiency increased from 5.129 to 7.379kgm−3 for furrow-irrigated treatments, and from 6.907 to 10.257kgm−3 for drip-irrigated treatments using the above mentioned rate of K-fertilizer

Prevalence of Metallo-β-Lactamase producing Pseudomonas aeruginosa in wound infections in Duhok city, Iraq

Background: Pseudomonas aeruginosa is common pathogen causing nosocomial infection. Acquired drug resistance and Metallo-β-lactamases (MBL) production have recently emerged as one of the most worrisome resistance mechanism that hydrolyze all beta-lactam antibiotics including penicillins, cephalosporins and carbapenems, with the exception of aztreonam. The aim was to find out the prevalence of multi drug resistant (MDR) and Metallo-β-lactamase (MBL) positive isolates of P. aeruginosa in wounds samples which are a serious concern.Methods: Pseudomonas aeruginosa strains were obtained by standard isolation and identification techniques from 307 wound samples of hospital. Strains were then subjected to susceptibility testing for anti-pseudomonas drugs as per Clinical and Laboratory Standards Institute (CLSI) guidelines. Carbapenems resistant strains were selected for the detection of MBL enzyme production by disc potentiation test. Production of MBL was confirmed by enhancement of inhibition zone around imipenem and meropenem discs impregnated with EDTA, as compared to discs without EDTA.Results: Amongst the 71 isolates of P. aeruginosa, 62(87.3%) isolate were imipenem-sensitive, while 9(12.7%) isolates were found to be imipenem resistant and MBL producers. Very high resistance to antibiotics was recorded amongst MBL producers’ P. aeruginosa compared with non-MBL imipenem-sensitive strains.Conclusion: Study indicates that, surveillance for the detection of MBL is necessary. The rapid dissemination of MBL producers is worrisome and necessitates the implementation of proper and judicious selection of antibiotics especially carbapenem.