Improved Energy Detector for Wideband Spectrum Sensing in Cognitive Radio Networks

In this paper, an improved energy detector for a wideband spectrum sensing is proposed. For a better detection of the spectrum holes the overall band is divided into equal non-overlapping sub-bands. The main objective is to determine the detection thresholds for each of these subbands jointly. By defining the problem as an optimization problem, we aim to find the maximum aggregated opportunistic throughput of cognitive radio networks. Introducing practical constraints to this optimization problem will change the problem into a convex and solvable one. The results of this paper show that the proposed improved energy detector will increase the aggregated throughput considerably

Research challenges and delayed gratification in information seeking behavior: a case study of research scholars

This study aims to find out the association between delayed gratification in information seeking behavior of research scholars and the challenges during the process of research. Also, determining how the research scholars face the challenges of the research work. The survey was adopted for data collection through a questionnaire. The sample population of the study is research scholars of three universities in Karnataka (India). The finding of the study indicates that the maximum reported challenge by research scholars during the research process belongs to data collection and the statistical analysis of the data. The minimum challenge belongs to designing the tables and selection of the topic. To find a solution to the challenges, 40 percent of the research scholars declared that they would consult with the guide to get the solution. There is a significant relationship between research challenges including finding the new resources, developing measurement tools, statistical analysis of the data, designing the tables and the dimension of delayed gratification in information seeking behavior

Association of characteristics of delivery and medical conditions during the first month of life with developmental defects of enamel.

BACKGROUND: Developmental defects of enamel (DDE) may be influenced by health problems and illness in children. The aim of the study was to identify the main characteristics of birth (delivery) and adverse medical conditions during the first month of life that may be related to DDE in permanent teeth. METHODS: 1000 schoolchildren between the ages of 9 and 11 years were selected for this cross-sectional study by multistage randomization from four educational zones in Shiraz in 2013. Intraoral examination was used to diagnose DDE according to World Health Organization screening guidelines and the Modified DDE Index. The data on seven birth factors as well as health and nutritional conditions during the first month of life were collected by a questionnaire completed by the parents, and were analyzed with the chi-squared test, Spearman's correlation and binary logistic regression. RESULTS: 469 (48.2%) out of 974 schoolchildren had at least one permanent tooth with DDE. The defects were significantly related with Apgar score at birth <7 (p = 0.003) and illness during the first month (p = 0.035). The frequency of DDE was significantly lower in the third child in families compared to the first and second child (p = 0.005). However, DDE showed no significant relationship with gestational age, delivery type, birth weight, gender or type of feeding during early infancy. CONCLUSIONS: Three associated factors were identified (birth Apgar score, illness during the first month of life, birth order) for DDE in permanent teeth. No specific illness was found to be significantly associated with DDE

Optimal Rate for Irregular LDPC Codes in Binary Erasure Channel

In this paper, we introduce a new practical and general method for solving the main problem of designing the capacity approaching, optimal rate, irregular low-density parity-check (LDPC) code ensemble over binary erasure channel (BEC). Compared to some new researches, which are based on application of asymptotic analysis tools out of optimization process, the proposed method is much simpler, faster, accurate and practical. Because of not using any relaxation or any approximate solution like previous works, the found answer with this method is optimal. We can construct optimal variable node degree distribution for any given binary erasure rate, {\epsilon}, and any check node degree distribution. The presented method is implemented and works well in practice. The time complexity of this method is of polynomial order. As a result, we obtain some degree distribution which their rates are close to the capacity.Comment: 5 pages, to be presented at the 2011 IEEE Information Theory Workshop (ITW 2011), Paraty, Brazil, October, 201

Improvement of Secondary Sedimentation Tanks in the Presence of a Baffle

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Acoustic phonon scattering in a low density, high mobility AlGaN/GaN field effect transistor

We report on the temperature dependence of the mobility, $\mu$, of the two-dimensional electron gas in a variable density AlGaN/GaN field effect transistor, with carrier densities ranging from 0.4$\times10^{12}$ cm$^{-2}$ to 3.0$\times10^{12}$ cm$^{-2}$ and a peak mobility of 80,000 cm$^{2}$/Vs. Between 20 K and 50 K we observe a linear dependence $\mu_{ac}^{-1} = \alpha$T indicating that acoustic phonon scattering dominates the temperature dependence of the mobility, with $\alpha$ being a monotonically increasing function of decreasing 2D electron density. This behavior is contrary to predictions of scattering in a degenerate electron gas, but consistent with calculations which account for thermal broadening and the temperature dependence of the electron screening. Our data imply a deformation potential D = 12-15 eV.Comment: 3 pages, 2 figures, RevTeX. Submitted to Appl Phys Let

PENERAPAN METODE PROFILE MATCHING DALAM REKOMENDASI PEMILIHAN LAPTOP TERBAIK

Laptop merupakan alat yang dapat mempermudah manusia dalam menyelesaikan pekerjaan. Penggunaan laptop harus disesuaikan dengan kebutuhan yang dimiliki, misalnya untuk kebutuhan design, games, IT dan Office. Maka dari itu, Untuk memilih laptop sesuai dengan kebutuhan, tentunya terdapat spesifikasi yang menyesuaikannya. Proses penentuan laptop sesuai dengan kebutuhan ini memiliki kriteria yaitu Prosessor, RAM, VGA, Hardisk, Screen, Battery dan Harga. Akan tetapi, Semakin banyaknya jenis serta merek laptop yang bervariasi saat ini menyebabkan banyak orang kebingungan dalam menentukan laptop sesuai dengan kebutuhan yang mereka miliki. apabila fungsionalitas laptop tidak memenuhi kebutuhan yang dimiliki, dapat menyebabkan error pada laptop. Dari permasalahan tersebut, maka diperlukan sebuah sistem pendukung keputusan dalam memilih laptop sesuai dengan kebutuhan menggunakan metode Profile Matching pada proses perankingan untuk menentukan laptop terbaik. Dari proses perhitungan ini akan di dapatkan sebuah solusi atau hasil rekomendasi laptop terbaik sesuai dengan kebutuhan

A comparative analysis of particle tracking in a mixer by discrete element method and positron emission particle tracking

Characterisation of particle flow using Positron Emission Particle Tracking (PEPT) is based on tracking the position of a single particle in a dynamic system. Recent developments in PEPT have facilitated tracking multiple particles aiming at improvements in data representation. Nevertheless for systems with a wide residence time distribution and/or dead zone, the conditions for getting representative data which could reflect the bulk behaviour of the powders need to be analysed and specified. In the present work, an attempt is made to simulate PEPT experiments for a paddle mixer using Discrete Element Method (DEM), with a view to investigate the effect of increasing the number of tracers on their time-averaged velocity distribution and whether it can represent the data on whole population of particles. The time averaged velocity distribution of the individual tracer particles (resembling simulated PEPT) is obtained and compared with the time averaged data on entire particle population. The DEM results indicate that for the investigated paddle mixer, it takes 251. s for one tracer to travel adequately in all the active space of the system. The instantaneous tracer velocity fluctuates around the average value obtained for all the particles, suggesting that the average tracer velocity is adequately representative of the average particle velocity in the system. The data of the PEPT experiment with one tracer with those of DEM with one tracer are in good agreement; however, DEM simulation suggests that increasing the number of tracers in the paddle mixer system does not influence the average velocity distribution. Furthermore, the velocity for all particles in the DEM shows a smooth distribution with a peak frequency of the velocity distribution that is lower than PEPT and DEM tracer. When tracking a single tracer in DEM or PEPT, it may not be detected to have zero velocity at any instant of time, whilst the data for all particles show that about 0.3% of particles are stagnant

A PMSM current controller system on FPGA platform

Permanent magnet synchronous motor (PMSM) has gained more interest recently in industrial applications. Digital hardware solutions such as field programmable gate arrays (FPGAs) are the most preferred methods for controlling PMSM drivers. This paper presents an implementation of a current control system for PMSM based on FPGA. Encoder-based speed and position detection method has been used in proposed hardware. The whole system has been modeled and simulated in system level using MATLAB/SIMULINK. Hardware architecture for all computational blocks is implemented using Verilog HDL. The hardware architecture has been successfully synthesized and implemented on Altera Cyclone II FPGA. Proposed system architecture and computational blocks are described and system level and RTL simulation results are presented. Simulation results show that the total computation cycle time of implemented system on Altera Cyclone II FPGA is 456ns.Keywords: PMSM, FPGA, Incremental encoder, CORDIC, Hysteresis Current Control