UET Peshawar Publications Site (University of Engineering and Technology, Peshawar)
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Model for Fuel Droplet Evaporation in Combustion Chamber of Liquid Propellant Rocket Engines
No full textComplete burning of liquid propellants droplets is very important to get higher specific impulse from liquid rocket engines. Required time must be provided to propellants droplets in combustion chamber for complete combustion. If required time is not provided then there will incomplete combustion of fuel which will reduce characteristic velocity and specific impulse. Combustion in liquid propellant rocket engine is non-premixed diffusion combustion. Combustion takes place in gaseous phase and reaction is very fast. So, the time consumed by a droplet for complete burning is the time taken by a droplet to get evaporate. Through modeling of droplets evaporation in combustion chamber of liquid propellant rocket engine, we can calculate time required for complete evaporation/ burning of propellants droplets and we can provide the required time in combustion chamber at design phase. An analytical mono component model is developed for the droplet evaporation in liquid rocket engine based on heat and mass transfer. The results of the model shows effects of the combustion chamber pressure, temperature, turbulence intensity, fuel droplet initial temperature, chamber diameter, droplet diameter and droplet relative velocity with hot gas on the life of droplet
NON-LINEAR FINITE ELEMENT ANALYSIS OF REINFORCEMENT STEEL BARS
No full textA two noded, unidimensional bar element formulated and implemented as a computer program in FORTRAN for elastoplastic Finite Element Analysis best suited for standard type of materials particularly metals was employed in order to find the strain hardening factor for the experimental data of several hundred reinforcement steel bars which were tested in laboratory. Here in the very first instance experimental yield and ultimate values were prescribed as input data and strain-hardening factor was obtained. Direct iterative procedure was adopted and the post yield behaviour of the material was modeled on the basis of a tangent modulus. The study was aimed at finding the suitability of ELPAS as theoretical tool for mathematical modeling of reinforcement bars manufactured from steel scrap. Since a very wide variation of the strain hardening factor values was observed, statistical analysis in terms of mean, standard deviation and coefficient of variation was performed. This was aimed at investigating further the reliability of such bars when used in R.C. structures based on stochastic approach
CORRELATION MATRIX METHOD FOR SOLVING BUCKLING AND FREE-VIBRATION PROBLEMS OF NONPRISMATIC CIRCULAR ARCHES
No full textThis paper proposes a new matrix method for calculation of critical loads and natural frequencies of circular arches with variable cross-section and arbitrary forms of applied load distribution. A difference from other matrix methods is that the coefficient determination of the corresponding characteristics can be reduced to one of third order, no matter how many elements are discretized in calculation. The essential reason for the important advantage is introduction of correlation matrices associated with discrete nodes into the analysis. The method is applicable to elastic arches of arbitrary geometry
DETERIORATION OF ORDINARY PORTLAND CEMENT AND FLY-ASH BASED GEO-POLYMER CONCRETES DUE TO SULFATE ATTACK UNDER THE ACTION OF SULFURIC ACID AND WASTEWATER
No full textCorrosion in concrete sewers and wastewater treatment plants has been a major problem but this issue has not been resolved satisfactorily yet. Generally, deterioration happens due to sulfuric acid reaction with treatment units and sewer materials. Geo-polymer binders especially fly ash (FA) is an acid resistant and can be used as a substitute binder for sewer construction. This research work highlights the laboratory results of fly ash based geo-polymer concrete and effects on its durability under sulfuric acid exposure. Class ‘F’ fly ash was used in the preparation of samples that were properly cured for 28 days at room temperature. After curing, specimens were immersed in three types of sulfate containing solutions to check corrosion.. These sulfate containing solutions include static sulfuric acid, dynamic wastewater and static wastewater. Samples were tested at 28, 45 and 60 days after immersing in different type of solutions to find the corrosion depth. By visual inspection the corrosion depth and residual compressive strength were observed according to the modified ASTM C267& C39 respectively. Reaction products of gypsum remained on the surface of concrete samples absorbed in diluted sulfuric acid, while reaction products of gypsum were not seen on the surfaces of concrete samples absorbed in static as well as dynamic wastewater. Static wastewater also produced corrosion but in a limited fashion, it causes only surface weathering. The obtained results are strongly confirming that geopolymer concrete samples are showing great resistant to sulfuric acid solution. Moreover, geo-polymer samples were also showing reasonable load carrying capacity after entire section had been neutralized by sulfuric acid
DESIGN OF A MODEL BASED MULTIVARIABLE ROBUST INTELLIGENT POWER CONTROLLER FOR LOAD FOLLOWING OPERATION OF NUCLEAR POWER PLANT
No full textIn this paper, a new Multi-Input Single-Output Robust Intelligent Power Controller (MISO-RIPC) is designed for a Pressurized Heavy Water Reactor (PHWR)-type Nuclear Power Plant (NPP) operating in High Power Steam Pressure Mode (HPSPM) in Pakistan. The proposed MISO-RIPC is a highly nonlinear intelligent controller synthesized based on Adaptive Feed forward Artificial Neural Network (AFANN) and has a 3-20-1 topology with high degree of robustness. An optimization procedure is performed for the selection of optimum number of neurons for highly nonlinear AFANN. A proposed multi-layer neuro controller is evolved as an optimization problem that resolves the nonlinear issues of complex control structure of PHWR-type nuclear power plant based on Real Time Dynamic Transient Data (RTDTD) of steam flows through north and south headers and steam pressure in the steam generator. The training of an intelligent controller is performed by soft computing and parallel tracking of Conventional Reactor Power Controller operating in Steam Pressure Mode (CRPC-SP). A data driven model of PHWR-type nuclear power plant is developed in high power mode using Controlled Auto-Regressive and Integrated Moving Average (CARIMA) technique. The proposed MISORIPC is validated against RTDTD. All design and simulation work is carried out in MATLAB. The dynamic behavior of the proposed MISO-RIPC is evaluated using a very special RTDTD. The performance of proposed intelligent controller is found highly smooth with excellent tractability features. The proposed intelligent controller is found robust based on reverse engineering approach
GPS ASSISTED HANDOFF IN OVERLAPPING IPv6 WLAN WITH MULTIPLE CoA
No full textWith the evolution of wireless networks and the unique features of mobile IPv6 it has become possible to utilize network services at remote location. However the handoff issues due to mobility can lead to serious delays. In this paper we present a unique approach for handoff when mobile node moves into a foreign network. We have utilized GPS (Global Positioning System) for gathering location information and multiple care of addresses handoff assistance
DEVELOPMENT OF FLOOD DISCHARGE MODELS USING GIS
No full textHydrological command of waterway system has been altering beneath the crash of mutually environment disparity and human actions in the overall milieu. With the advent of technology it is now possible to modelthe complete resource allocation of any hydrological network duly integrating both natural and artificialnetworks. Advance applications allow an excellent automated system to monitor, control and manage water allocations to better utilize water resources, minimize wastage and predict hazards. The first step to all of this is to have accurate information of the catchment areas, so that in coordination with concerned departments, modeling and predictions of futuristic results is possible which will yield better decision making leading to fructifying outcome. Physical hydrologic models for drainage areas are significant utensils to hold water assetsmanagement and foresee diverse hydrologic contacts and risks. Indus River is considered as salvation of Pakistan and it is also the largest river of the country. The approximate length of the river is 3180 kilometers and its drainage area exceeds 1165000 km2. Having in view the worth of Indus River and its socio economic implication on Pakistan it was planned to carry out research work on upstream of Terbela from Kachura. The intended approaches of this work were to generate empirical equations based on hydrologic model on a particular reach of the river i.e. from Kachura to Tarbela reservoir and by utilizing GeographicInformation Systems and Remote Sensing means. Also the watershed analysis of the upstream of Indus river basin was performed, thus fashioning an essential tool for running and setting up of water resources for state
INTERNATIONALIZING MANUFACTURING SMEs IN A DEVELOPING REGION: AN EXHAUSTIVE CDA-BASED EXPLORATORY APPROACH
No full text
Internationalization of Small and Medium Enterprises (SMEs) in developing economies is a hybrid strategy where reactive remedies and proactive styles of inward/outward operations is sought by innovative and risk seeking entrepreneurs. Exporting remains the dominant mode of internationalization and entry to foreign markets by SMEs in both developing and developed economies. When data on SMEs attributes and entrepreneur’s characteristic is categorical, single methodology to analyze factors influencing exporting are far from sufficient. A multi-method and exhaustive approach is necessary to explore the adequacy of factors in question. The three methods relevant to categorical data analysis (CDA) in this paper highlights the enabling role of the exploratory factors in understanding the relationship with SME’s exporting. Categorical regression overcomes the limitations of both contingency table method and binary logistic regression in exploring this relationship, and provides substantive space to experiment and investigate the contributory role of export-enabling factors when data size is smal
RESILIENT CHARACTERISTICS OF SUBGRADE SOILS IN SAUDI ARABIA
No full textSubgrade soil samples were collected along major highways of Saudi Arabia. The properties of AASHOTO class A-2-4 soil samples, including resilient modulus, were determined and analyzed. The main purpose was to correlate resilient behaviour with other soil properties. First, resilient modulus was modeled in terms of stress state (deviator and confining stresses). Then, model constants were related by regression equations to soil properties. The developed models can be used to predict resilient modulus values based on soil properties and expected stress state under the pavement
METHODOLOGY FOR POSITIONING MULTIPLE DECOUPLING POINTS IN HYBRID MANUFACTURING SUPPLY CHAIN SYSTEM
No full textManufacturing companies are hard pressed to produce products faster and keep their cost at possible minimum. Manufacturers are always in search to fit their supply chains both internal (within manufacturing) and external to meet the challenge of competitive market. The delivery time is one of the most critical factors which influence management of the supply chain networks and cost of the product. To respond to a given lead time, manufacturing firms need to adjust their supply chain networks and design an effective interface for decoupling points in the supply chain based on the cost to be incurred. In this paper, a modified cost model is proposed for a hybrid supply chain networks of a manufacturing firm which is applied for determining positions for decoupling points in the entire manufacturing supply chain networks. The cost model is useful in evaluating performance of the supply chain in terms of cost for a given delivery lead time and helps draw a line of multiple decoupling points in the networks which is supposed to yield best possible cost. The application of the model has been demonstrated through an example for its usefulness. The results shows effectiveness of the proposed model and leads to recommendations for developing a comprehensive and integrated methodology for designing interface for hybrid manufacturing supply chain networks for quick response to the delivery lead time