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44 articles for “lower frequency”
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Research ArticleOpen accessIn the abstractAN EFFICIENT POWER REDUCTION TECHNIQUE IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYSTEM USING TONE RESERVATIONV. Nandalal, S. SophiaIn a basic communication system, the data’s are modulated onto a single carrier frequency. The available bandwidth is then totally occupied by each symbol. This kind of system can lead to Inter-Symbol-Interference (ISI) in case of frequency selective fading. The basic idea of Orthogonal Frequency Division Multiplexing (OFDM) is to divide the available spectrum into several orthogonal sub channels so … …Journal of Computer Science, Vol. 9, Issue 9 · 6 Aug 2013 · 6,475 accessesView PDFCite
Research ArticleOpen accessIn the abstractAnalysis of Fundamental Frequency Contour of Coded Speech Based on Multi-Pulse Based Code Excited Linear Prediction AlgorithmSuphattharachai ChomphanProblem statement: In low-bit-rate speech communication, speech coding deteriorates the characteristics of the coded speech significantly. An important feature of the speech is the fundamental frequency contour which determines the pitch information of the speech. It has been known that pitch information is one of the core parameter of the multi-pulse based code excited linear prediction (MPCELP) speech coder. Therefore … …Journal of Computer Science, Vol. 7, Issue 6 · 14 Jun 2011 · 6,463 accessesView PDFCite
Research ArticleOpen accessIn the abstractEffects of Hyperoxia on Brain Tissue Oxygen Tension in Non-Sedated, Non- Anesthetized Arctic Ground Squirrels: An Animal Model of Hyperoxic StressYilong Ma, Shufen Wu, Lawrence DuffyArctic Ground Squirrels (AGS) are classic hibernators known for their tolerance to hypoxia. AGS have been studied as a model of hypoxia with potential as a medical research model. Problem statement: Their unique resistance to the stressors of low oxygen led us to hypothesize that AGS might also be adaptable to hyperoxia. Approach: This study examined the physiological pattern associated … …American Journal of Animal and Veterinary Sciences, Vol. 6, Issue 1 · 26 Apr 2011 · 8,476 accessesView PDFCite
Research ArticleOpen accessIn the abstractA Preamble-Based Frequency Offset Compensation Scheme in Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing SystemsElnaz Ershadi, Hamidreza BakhshiProblem statement: Combining the properties of Multiple Input Multiple Output (MIMO) systems with those of Orthogonal Frequency Division Multiplexing (OFDM), MIMO-OFDM was considered to be a promising technique in the future of wireless communications. However, its sensitivity to frequency offsets which results in Inter-Carrier Interferences (ICIs) makes it necessary to use an exact frequency offset estimation method for data recovery … …Journal of Computer Science, Vol. 6, Issue 4 · 30 Apr 2010 · 7,574 accessesView PDFCite
Research ArticleOpen accessIn the abstractNoise Control Using Coconut Coir Fiber Sound Absorber with Porous Layer Backing and Perforated PanelRozli Zulkifli, Zulkarnain, Mohd Jailani Mohd NorProblem statement: Noise control was one of the major requirements to improve the living environment. One of the methods to do that is provided by sound absorber. Commonly, multi-layer sound absorbers are applied to absorb broadband noise that was composed of perforated plates, air space and porous material. However, multi-layers sound absorbers effectiveness depends on their construction. This study was … …American Journal of Applied Sciences, Vol. 7, Issue 2 · 28 Feb 2010 · 14,716 accessesView PDFCite
Research ArticleOpen accessIn the abstractDesign and Simulation of Microelectromechanical System Capacitive Shunt SwitchesHaslina Jaafar, Othman Sidek, Azman Miskam, Shukri KorakkottilProblem statement: RF MEMS switch is one of MEMS area that creates devices that have great potential to improve the performance of communication circuits and systems and enables the realization of micro size mechanical switches embedded in electronics devices. The low voltage switches are necessary due to their compatibility of standard IC technology in RF application and microelectronics systems. In … …American Journal of Engineering and Applied Sciences, Vol. 2, Issue 4 · 31 Dec 2009 · 7,718 accessesView PDFCite
Research ArticleOpen accessIn the abstractSolving the Near-Far Problem in Dynamic Frequency Hopping-Optical Code Division Multiple Access using Power ControlW. J.M. Al-galbi, M. Mokhtar, A. F. Abas et al.Problem statement: In this study, a distributed power control algorithm is proposed for Dynamic Frequency Hopping Optical-CDMA (DFH-OCDMA) system. Approach: In general, the DFH-OCDMA can support higher number of simultaneous users compared to other OCDMA techniques. However, the performance of such system degrades significantly as the received power does lower than its minimum threshold. Results: This may obviously occur in … …Journal of Computer Science, Vol. 5, Issue 6 · 30 Jun 2009 · 7,522 accessesView PDFCite
Research ArticleOpen accessIn the abstractThe Frequency of Polymorphisms affecting Lead and Mercury Toxicity among Children with AutismShannon Rose, Stepan Melnyk, Alena Savenka et al.Individual risk of developmental neurotoxicity with exposure to environmentally relevant levels of lead and mercury is likely to be determined by genetic susceptibility factors as well as additive interactions with other environmental pollutants, cumulative dose, and the developmental stage of exposure. The apparent increase in autism diagnosis over the last 15 years has enhanced interest in the possibility that an … …American Journal of Biochemistry and Biotechnology, Vol. 4, Issue 2 · 30 Jun 2008 · 7,524 accessesView PDFCite
Research ArticleOpen accessIn the abstractClassification of Textures by Avoiding Complex PatternsV. V. Kumar, B. E. Reddy, U. S.N. Raju, A. SureshThe present research advocates a new method for texture classification based on primitive patterns. For this, an optimal set of eight simple patterns are selected based on their discrimination. The percentage of frequency of occurrences is computed for these patterns on entire texture image. Textures can be classified by using frequency of occurrences, for complex patterns also. The present research … …Journal of Computer Science, Vol. 4, Issue 2 · 28 Feb 2008 · 6,976 accessesView PDFCite
Research ArticleOpen accessIn the abstractRainfall Depth-Duration-Frequency Relationships for South Carolina, North Carolina, and GeorgiaJ. P. Raiford, N.M. Aziz, A.A. Khan, D.N. PowellThe depth-duration-frequency curves and isopluvial maps for the region encompassing South Carolina, North Carolina, and Georgia were developed using the available rainfall data. The aim was to update the existing intensity-duration-frequency curves in the region and obtain these curves at ungauged sites throughout the region using the newly developed rainfall frequency analysis techniques. A total of 17 durations ranging from … …American Journal of Environmental Sciences, Vol. 3, Issue 2 · 30 Jun 2007 · 7,330 accessesView PDFCite