UET Peshawar Publications Site (University of Engineering and Technology, Peshawar)
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DEVELOPMENT OF A LOW VOLTAGE AC TO DC CONVERTER FOR MESO AND MICRO ENERGY HARVESTERS
No full textEnergy harvesting is widely used for the operation of wireless sensor nodes. Most of the energy harvesters generated voltage levels are sinusoidal or random in nature, moreover, the output voltage levels these produce are in low (in mV range). For sensor operation, in order to convert this low AC voltage levels into relatively high DC voltage DC, a three stage Cockcroft Walton converter is developed. The paper presents fabrication and characterization of a 3 stage Low Voltage Cockcroft-Walton converter in an area of 5.5 x 3.3 cm2. The converter was capable of converting a minimum AC voltage amplitude of 10 mV with a transformation factor of 6.5. The variation in the input frequency had almost no effect on the DC output voltage of the converter. Upon integration of the converter to different energy harvesters, the converter successfully rectifed the AC or random output voltage signals of the harvesters into corresponding DC voltage
PERFORMANCE ASSESSMENT OF TWO GRAVITY IRRIGATION SYSTEMS BEFORE IRRIGATION MANAGEMENT TURNOVER TO FARMERS
No full textThe government of Pakistan desires to introduce the participatory irrigation management at secondary level to make irrigation system financially viably through farmers participation. The pilot project at Surizai and Pabbi minor of Warsak Gravity Canal was initiated. The study was conducted during May-September, 1998 to evaluate the technical performance of the two minors prior to turnover to the farmers. Regular discharge measurement programme was established by calibrating hydraulic structures during the study period. The results of the study illustrate that the Pabbi and Surizai minors are drawing more water than design discharges. The reliability of irrigation water was fair as the consequence of over drawing of irrigation water by the both minors. The outlets behave as non-proportional due to tempering, change in reference bed level and cross sectional profiles. There was design induced inequity among the outlets of both minors as the sanctioned water allowance (duty ) was not constant for all outlets and actual water allowance was more than the designed water allowance. The inequity also exist in actual water supplies, due to which tail enders were deprived of irrigation water. The analysis of climatic data and actual irrigation supplies at minor level indicate there is scarcity of water, which effect the adequacy of water supplies at minor level. At tertiary level, inadequacy of water is overcome by the farmers by reducing the cropped area and at farm level farmers applied less depth of water than recommended and have developed their own irrigation cycles based on their experiences to avoid crop stresses. The study provide evidence that irrigation management turnover to the farmers' will not lead to improve the performance until the technical changes in physical infrastructures are not incorporated according to the farmers need and capabilities for operation and regulation
KINETICS OF Cr(III) OXIDATION AND SORPTION ON p-MnOz AND a-FeOOH
No full textThe kinetics of oxidation and sorption of Cr(lll) has been studied as a function of temperature and nature of oxidants. The specific rate constant, order of reaction and the energy of activation of both the processes are evaluated. The sorption being fast is accompanied by its subsequent slow oxidation to Cr(VI )
NOISE CONTROL FILTRATION OF LATERAL AND YAW DYNAMICS FOR RAILWAY VEHICLE WHEELSET ON TRACK
No full textThe noise is the fundamental substandard sign of smooth running of the railway vehicle wheelset over the railroad. This disturbance is created deteriorating environment on deranged railway vehicle speed in any direction of basic degree of freedom. In this paper, Brief applicable mathematic is used framed for necessary modeling. The estimation of perturbations for the movement by wheels and velocity of train in lateral and yaw phases are enumerated. Here dual bucy kalman estimator is implemented to decrease the influence of the noise caused due improper ratio of adhesion level upon track. One estimator reduces the overshoot of noise and other to minimize it at lower level of level of error. Further the behavior of lateral and yaw dynamic analysis is observed by implementation of fuzzy inference system through applicable member functions
LIFE CYCLE COSTING AND PAYBACK PERIOD EVALUATION OF A SOLAR THERMAL DESALINATION SYSTEM
No full textWater is important for life and development. About 1.8 billion people will be living in absolute water scarcity by2025.Non availability of safe drinkable water is the major source of diseases in the different regions of the worldespecially remote rural and coastal areas. About 97% of water on earth is comprised of seawater. Desalination ofsaline water is a prominent approach to handle the problem of water scarcity. Conventional desalination technologiescause economic and environmental problems due to their dependency upon fossil fuels. Solar flash desalinationis one of the best desalination techniques in the developing stages. Solar energy, passive vacuum and recovery oflatent heat of condensation make this system a sustainable option for desalination. In this paper, economic analysisof the solar thermal desalination system of saline water is presented. The unit cost of desalinated water is found tobe US$ 0.0147 per litre. The energy and emission payback (EEP) period for vacuum chamber and solar collectorhas also been presented. The energy payback period of solar collector and vacuum chamber are found to be 1.3years and 1.5 years respectively. The emission payback period of solar collector and vacuum chamber are found tobe 1.8 years and 2.1 years respectively
PREDICTING FUTURE TEMPERATURE AND PRECIPITATION OVER PAKISTAN IN THE 21ST CENTURY
No full textThe objective of this study was to analyze projections of changes in mean annual temperature and precipitation over Pakistan for mid-century (2040–2069) and end century (2070–2099) time periods. An open source web tool namely “climate wizard” was used to obtain temperature and precipitation departures projected by three different GCMs under A1B, B1 and A2 emission scenarios. To ensure the maximum possible spatial coverage, a total of 16 climatic stations in Pakistan were selected. Results indicated a temperature departure in the range of 1.3-2.7°C for the mid century period, and a temperature departure in the range of 2.3-5.3°C for the end century period. Among different provinces of Pakistan, Gilgit Baltistan, Northern and Southern Punjab, Khyber Pakhtunkhwa and central Balochistan are likely to be subjected to greatest temperature rise in the coming decades. The projections of precipitation changes over Pakistan by different models show greater variability compared to temperature changes. An increase in precipitation in the range of (1-11%) was projected over Pakistan for the mid century. However, central Balochistan and southern Punjab showed negative precipitation departures ranging from -1 to-11%, thus increasing the likelihood of droughts in these regions. For the end century, positive precipitation departures were projected throughout the country, except Balochistan, Gilgit Baltistan and Southern Punjab, which showed negative departures of (-1 to -19%). With the projected rise in mean annual temperature through Pakistan, several sectors such as agriculture, energy, water supply and health will face serious challenges in the second half of the 21st century. Therefore, preventive and remedial measures are required to minimize the impacts of projected warming by formulating long-term management and control policies for all sectors
TEMPERATURE GRADIENTS: EVALUATION OF THE THEORY OF PHILIP AND DE VRIES (1957)
No full textThe theory of Philip and de Vries ( 1957 ) has been used extensively to describe the transfer of water in response to water-content and temperature gradients. The same theory was evaluated using vertical columns in which there were fluxes both into ( from a water table at 55-cm depth ) and out of the soil ( evaporation to the atmosphere ). The fluxes of water were differentiated. The isothermal vapour flux was negligibly small in all experiments. The thermal vapour flux was found to be negligibly small below a depth of 10 cm but its magnitude at the soil surface increased with decreasing water content and increasing temperature. The isothermal liquid flux contributed significantly to the net soil-water flux except at very low water contents. Thermal liquid flux contributed significantly to the net soil-water flux except at very low contents and was comparable in magnitude to both the isothermal liquid flux and net vapour flux. The downward liquid flux due to gravity was comparable in magnitude to those of the isothermal and thermal liquid fluxes, particularly at high water contents. The Philip and de Vries ( 1957 ) theory predicted close to the measured soil-water flux at very low water contents but over predicted upto a factor of 20 at intermediate and high water contents
PHOTOVOLTAIC FOR RURAL ELECTRIFICATION IN PAKISTAN
No full textThis paper presents a cost comparison for rural electrification of a village through two alternatives, ( i ) a 3 kW Solar Photovoltaic Plant (ii) supply from existing WAPDA network. The comparison shows that it is economically more feasible to supply from Solar Photovoltaic system rather than providing them from the existing power network.This paper presents a cost comparison for rural electrification of a village through two alternatives, ( i ) a 3 kW Solar Photovoltaic Plant (ii) supply from existing WAPDA network. The comparison shows that it is economically more feasible to supply from Solar Photovoltaic system rather than providing them from the existing power network
PARAMETRIC METHOD OF SEPARATING PERIODIC AND STOCHASTIC COMPONENTS
No full textSeries of monthly average discharge have seasonal or periodic components of 12 months in both monthly mean and monthly standard deviation. The basic approach in investigation the periodic character of the time series is based on the assumption that the periodic components are deterministic. Furthermore, a stationary stochastic process is superimposed on them and is described by algebraic equations of time series composition.Parametric approach is used to separate out the periodic deterministic component so as to left with the stationary stochastic component so as to left with the stationary stochastic component. Monthly average discharge data for Swat River at upstream Munda Head Works for the period 1969 to 1983 was analysed to remove periodicity by the parametric approach of fitting the significant harmonics
FLEXURAL BEHAVIOUR OF WHITE CEMENT MARBLE-DUST MICROCONCRETE
No full textTwenty four beams have been cast and tested to determine the flexural behaviour of marble-dust micro-concrete with white cement as bonding material. The study was aimed at finding the strain distribution and redistribution within the cross-section of rectangular beams at different stages of loading up to failure. The final shape of strain diagram was also included in the domain of investigations. The crack pattern and mode of failure for two different sizes of beams were observed. With each beam cubes were cast to find the compressive strength on the day the beams were tested. The compressive strength thus obtained was compared with previous studies. Cubes of pure white cement were also cast and tested to determine the maximum strength that could be achieved and coefficient of shrinkage of pure white cement was also area of interest