A STUDY OF SORPTION OF CADMIUM BY GOETHITE IN AQUEOUS SOLUTION

Investigation has been carried out on the potential of a locally sourced goethite for the removal of cadmium ion from aqueous solutions using batch equilibration technique. The maximum uptake of cadmium is 6.4 ´ 10-2 mg/g-goethite. The sorption kinetics appears to be rapid as equilibrium was attained within a period of 1 hour. The highest sorption capacity was obtained for particle size with diameter (f ) 0.09 mm. Both infrared spectrophotometric and X-ray diffraction (XRD) techniques have also provided evidence for cadmium fixation on to the surface of the goethite. The sorption mechanism appears to follow Langmuir adsorption isotherm model. The Langmuir constants K and Xm (mass of Cd2+ required to form monolayer on the entire surface of the goethite) were 0.096 mg/g-goethite and 0.075 mg/g-goethite, respectively. (Received January 28, 2002; revised April 10, 2002) Bull. Chem. Soc. Ethiop. 2002, 16(1), 1-7

Use of the Steam as Gasifying Agent in Fluidized Bed Gasifier

This work has studied the impact of gasification mediums (air and steam air mixture) on syngas components (H2, CO) and low heating value LHV. This study has been based on previous research and experimental studies conducted in fluidized bed by using air-steam as gasification agent and pine wood chips as feedstock. According to the results of the experiments and discussion, it has been found, that the gas quality is improved with the use of the steam and air mixture. The parameters, with which to achieve the best quality of the produced gas at experimental conditions (ER = 29, Tf1 = 261 °C) are as follows: T101 = 829 °C, 0.67 S/B = 0.67, where hydrogen is increased from 10.48 to 19.68 % and low heating value from 3.99 to 5.53 MJ m–3 and tar is decreased from 1964 to 1046 mg m–3 by increasing S/B from 0 to 0.67 at T101 = 829 °C

The relevance of the school governance body to the effective decolonisation of education in South Africa

Decolonisation of education is understood in this paper as a means of formalising indigenous culture and knowledge within the formal school system. The focus of this paper is to see how the School Governance Body (SGB) can bring about decolonised education for sustainable development. The African societal culture and traditions seem to be misunderstood and side-lined today because of the privilege enjoyed by western values in formal education used to develop African children. The involvement of people at the grass roots who are still endowed with vast knowledge on this cultural heritage should be considered as an option. The South African school system gave room for community participation in the administration and management of schools under the system of School Governing Bodies (SGBs). These bodies have the potential of being a good source of indigenous knowledge and culture to the school system that will make the education more relevant and functional; hence, leading to sustainable development, if it is properly planned and tapped into. For this to happen, there is the need to examine the relevance of the body through close analysis of its composition and strength to assist in the decolonisation of education. This study adopted an ethnography approach of qualitative research. Three rural-based Eastern Cape communities were used where 18 parents participated in the study. Data were gathered through key informant interviews (KII) and focus group discussions (FGD). One of the results is that traditional leaders are part of the SGB, which makes it a good source of indigenous knowledge and traditions. It was recommended that the composition of the members of SGBs should statutorily include a recognised knowledgeable individual (RKI) in the community to make the body a good source of indigenous knowledge

Design And Implementation of Dsp-Based Intelligent Controller For Automobile Braking System

An intelligent braking system has great potential applications especially, in developed countries where research on smart vehicle and intelligent highways are receiving ample attention. The system when integrated with other subsystems like automatic traction control, intelligent throttle, and auto cruise systems, etc will result in smart vehicle maneuver. The driver at the end of the day will become the passenger, safety accorded the highest priority and the journey optimized in term of time duration, cost, efficiency and comfortability. The impact of such design and development will cater for the need of contemporary society that aspires to a quality drive as well as to accommodate the advancement of technology especially in the area of smart sensors and actuators. The emergence of digital signal processor enhances the capacity and features of universal microcontroller. This paper introduces the use of TI DSP, TMS320LF2407 as an engine of the system. The overall system is designed so that the value of inter-vehicle distance from infrared laser sensor and speed of follower car from speedometer are fed into the DSP for processing, resulting in the DSP issuing commands to the actuator to function appropriately

Parameter estimation of multicomponent transient signals using deconvolution and arma modelling techniques

Parameter estimation of transient signals, having real decaying exponential constants, is a difficult but important problem that often arises in many areas of scientific disciplines. The frequency domain method of analysis that involves Gardner transformation and conventional inverse filtering often degrades the quality of the deconvolved data, leading to inaccurate results, especially for noisy data. An improved method that is based on the combination of Gardner transformation, optimal compensation deconvolution, and signal modelling techniques is suggested in this paper. In this method of analysis the exponential signal is converted to a convolution model whose input is a train of weighted delta function that contains the signal parameters to be determined. The resolution of the estimated decay rates is poor if the conventional fast Fourier transform (FFT) algorithm is used to analyse the resulting deconvolved data. Using an autoregressive moving (ARMA) model whose AR parameters are determined by solving high-order Yule–Walker equations (HOYWE) via the singular value decomposition (SVD) algorithm can alleviate this shortcoming. The effect of sampling conditions, noise level, number of components and relative sizes of the signal parameters on the performance of this modified method of analysis is examined in this paper. Simulation results show that high-resolution estimates of decay constants can be obtained when the above signal processing techniques are used to analyse multiexponential signals with varied signal-to-noise ratio (SNR). This approach also provides a graphical procedure for detecting and validating the number of exponential signals present in the data. Some computer simulation results are presented to justify the need for this modified method of analysis

The Impact of Academic Satisfaction as a Mediator on International Conferences

Scientists have lately discovered that the quality of services has a significant influence on academic satisfaction and academic loyalty. Universities in Erbil are competing attract academics by conducting international conferences. The purpose of this study is to evaluate the service quality in international conferences. A statistical analysis was provided based on data collected from 150 responses from academics at Cihan University-Erbil and other universities in the region. A structured questionnaire was conducted by the respondents in order to analyze their general expectations on conference services and the actual service performance they perceived with the conference. The study also assessed the impact of respondents’ past experiences on their expectations. The findings of this study show that we have positive effect between the total effect of (SQ) the independent variable on (CI) the dependent variable is highly significant with (t = 6.02, p< 0.05), also the effect of the mediator variable (AS) was significant with (t = 7.01, p< 0.05), and finally both the independent variable and the mediator variable (SQ) and (AS) have a significant effect on the dependent variable (CI). We found that the meditation effect was partial but not complete effect

Design of intelligent braking system

It is anticipated that a variety of cars with diversified features that include anti-lock braking system (ABS), traction control system (TCS), antiskid Steering, collision warning system (CWS) will be more commercially produced to satis@ the consumer needs in the near future. This is parallel to the trend of current technology of manufhcturing smart cars and the &sires of people who always want to have comfortable and safe ride in their vehicles. Mower this type of vehicles can fit much better into the intelligent highway that Malaysian government is planning to have in the near future. Consequently, there is a need to modify the current conventional braking system so as to make it work automatically. This paper considers the use of intelligent controller to achieve the above objective. To ensure high speed of system response, the DSP controller TMS320C24x with - fuzzy algorithm is used in the implementation of this new device. Results of simulation studies using the MATLAB have demonstrated the feasibility of this new system under investigation

Performance evaluation of the deconvolution techniques used in analyzing multicomponent transient signals

Deconvolution is an important preprocessing procedure often needed in the spectral analysis of transient exponentially decaying signals. Three deconvolution techniques are studied and applied to the problem of estimating the parameters of multiexponential signals observed in noise. Both the conventional and optimal compensated inverse filtering approaches produce data which are further analyzed by SVD-based autoregressive moving average (ARMA) modeling techniques. The third procedure is based on homomorphic filtering and it is implemented by fast Fourier transform (FFT) technique. A comparative study of the performance of the above deconvolution techniques in analyzing multicomponent exponential signals with varied signal-to-noise ratio (SNR) is examined in this paper. The results of simulation studies show that the homomorphic deconvolution technique is most computationally efficient, however, it produces inaccurate estimates of signal parameters even at high SNR, especially with closely related exponents. Simulation results show that the optimal compensation deconvolution technique is indeed a generalized form of the conventional inverse filtering and has the potential of producing accurate estimates of signal parameters from a substantial wide range of SNR data

Africa rising, a narrative for life expectancy gains? Evidence from a health production function

Background: The narrative of Africa Rising has increasingly been called into scrutiny, not just as a debate for economic growth and development, but also as a possible link to the surge in life expectancy on the continent. Theoretically, an increase in economic development tends to result in an increase in public health spending and subsequent better health outcomes. Objective: This paper examines the contribution of economic development and other social determinants to the health status of the African continent and to provide evidence on whether the increase in life expectancy of the past two decades can be largely attributed to the Africa Rising narrative. Methods: We estimated an empirical health production function, with life expectancy gains as the output of the health care system, and various socio-economic, environmental and lifestyle factors as contributory factors. We fitted a generalized least squares model, using panel data from 52 African countries for the period 1995–2014. Findings: The estimation shows that while increases in health care spending contributed to life expectancy gains, urbanization rates and improved water access were the major drivers of life expectancy gains with substantially larger impacts in the past two decades. Conclusions: Overall, the results provide an evidence base for iterating the need to prioritize increasing funding and examine more critically how to improve the efficiency of health spending. It also illustrates potential gains that can be achieved from an inclusive health policy agenda with a broader range of social and economic development issues.publishersversionpublishe

Adaptive dual-comb spectroscopy in the green region

Dual-comb spectroscopy is extended to the visible spectral range with a set-up based on two frequency-doubled femtosecond ytterbium-doped fiber lasers. The dense rovibronic spectrum of iodine around 19240 cm-1 is recorded within 12 ms at Doppler-limited resolution with a simple scheme that only uses free-running femtosecond lasers