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| 1 | Real-Time Frequency Estimation of Complex GMSK Signal of Green Communications Devices显示文摘Parameter estimation of signals of universal software radio peripheral(USRP) devices is crucial to solve the problem of phase offsets of received signals in distributed beamforming. For systems that will utilize the closed loop feedback algorithm where the receiver needs to send the received signal strength(RSS) values periodically to the beamforming node so as to take advantage of energy conservation, the frequency and phase of these signals should be estimated before smoothening by nonlinear filters. This article presents the estimation of the frequency offsets of a Gaussian minimum shift keying(GMSK) signal from N210 USRP devices in real time by using the Radix-2 fast Fourier transform(FFT) algorithm in GNURadio. For these green communications devices, most of the needed hardware parts have been software defined, thereby reducing the supposed energy consumption. The frequency offsets from reference carrier frequencies of 900 MHz and 2.4 GHz are less than 3 kH z each before the estimation, but the average offsets are 45 Hz and 100 Hz after the estimation, respectively. The high offset value experienced with the 2.4 GHz carrier was due to consistent interference from devices on that same frequency. | Umar Suleiman Dauda NikNoordini NikAbdMalik Mazlina Esa Kamaludin Mohd Yusof Mohd Fairus Mohd Yusoff Mohamed Rijal Hamid | 2016 | Journal of Electronic Science and Technology2016，14，2： | 1 |
| 2 | Fistula-in-Ano complicated by Fournier′s gangrene our experience in North-Eastern region of Nigeria显示文摘 | Abubakar Bakari Nuhu Ali Ibrahim Gadam Bata Gali Chubado Tahir KDT Yawe Adamu Dahiru Baba Mohammed Dauda Wadinga | 2013 | Nigerian Journal of Surgery2013，，2： | 1 |
| 3 | Process Noise Parameters of Beamforming Green Nodes显示文摘Signals arrive out of phase at the intended receiver from collaborative beamforming(CB) nodes due to the instability in the output frequency signals of the universal software radio peripheral's(USRP) local oscillator(LO). These nodes including the target must synchronize their oscillator frequencies for coherent signal reception. In order to do this, frequencies and phases of the signals should be estimated in software defined radio(SDR) and smoothen with nonlinear filters such as the extended Kalman filter(EKF). The process noise parameters of the NI USRP-2920 nodes will have to be calculated and used with the EKF process noise covariance matrix. These nodes are green communication hardware devices where most of the hardware units are now software defined. This article uses the direct spectrum method to obtain the phase noise values at various frequency offsets of the NI USRP-2920 in order to calculate the power spectral density of fractional frequency fluctuation. By applying the power-law noise model to this obtained value, the generated white frequency noise and random walk frequency noise values are q_1=1.93×10^(-21) and q_2=5.86×10^(-18), respectively. | Umar Suleiman Dauda NikNoordini NikAbdMalil Mazlina Esa Kamaludin Mohd Yusof Mohd Fairus Mohd Yusoff Mohamed Rijal Hamid | 2016 | Journal of Electronic Science and Technology2016，14，2： | 0 |
| 4 | Sulfamic acid functionalized slag for effective removal of organic dye and toxic metal from the aqueous samples显示文摘Surface functionalization of blast furnace slag with sulfamic acid(a zwitterion)was performed for the removal of Cr^(3+)and methylene blue dye(MB)from water samples.The slag functionalization process was optimized using Response Surface Methodology Design.Statistical analysis of the parameters that include the sulfamic acid amount(A),reaction time(B),and temperature(C)revealed that(A)increase had a negative effect on the adsorption of both pollutants by the zwitterion slag,whereas(B)and(C)increase presented a positive impact.At the optimum condition of 2 g sulfamic acid amount,50 min reaction time and 37℃ temperature,the prepared slag showed a removal efficiency of more than 90% for both Cr^(3+)and MB.Surface characterization by SEM/EDS,FTIR,XPS and surface area analyser,showed an improvement in surface properties and the incorporation of zwitterionic NH^(2+)and S=O groups of sulfamic acid.Adsorption isotherm and kinetic studies conducted with the zwitterion slag showed the adsorption process was suited to Freundlich isotherm model and pseudo-second-order kinetic model.The thermodynamic study conducted revealed the spontaneity of the process based on the calculated negativeΔG(Gibb’s free energy)values.The prepared zwitterion slag offered easy regeneration with dilute HCl solution and showed a considerable removal(Cr^(3+):65% and MB:80%)for both pollutants even after 3 cycles of usage. | Dauda Mohammed Muhammad HAl-Malack Basheer Chanbasha | 2021 | Chinese Journal of Chemical Engineering2021，34，5： | 0 |
| 5 | The Growth of Sub-Saharan Africa in the 2000s:Estimation of the Contributions of Factor Accumulation and Factor Productivity显示文摘Sustained economic growth is a key source of poverty alleviation and growth that is driven more by productivity than the quantity of factors of production is useful for long-term inclusive growth and poverty reduction,which is needed in Sub-Saharan Africa.The paper sought to investigate the relative roles of capital and labour as factors of production and their productivity in the growth process of Sub-Saharan Africa using annual data from 2000 to 2018.A production function was estimated,following the construction of data for capital stock using the perpetual inventory method.The production function was estimated by applying the instrumental variables(IV)to the two-way fixed effects model,using clustered standard errors.The results show that the share of capital and labour in production were 0.14 and 0.86 respectively.Capital,labour and their productivity contributed 24.7%,51.1%and 24.2%respectively to real GDP growth during the period 2001 to 2018.Further efforts in building the productivity of capital and labour are therefore required in Sub-Saharan Africa.Building good governance,the legal framework,political stability,expanded access to quality education and affordable quality healthcare,greater openness towards technological progress are therefore imperative. | Robert Dauda Korsu Mohamed Ben Omar Ndiaye | 2021 | Economics World2021，9，2： | 0 |
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