UET Peshawar Publications Site (University of Engineering and Technology, Peshawar)
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THE SIMULATION STUDIES OF EXPLOSIVELY FORMED PROJECTILES (EFPS)
No full textThe explosively formed projectile (EFP) attains maximum velocity which attenuates to stable velocity during the flight. Different parameters (pressure, stability, compression etc.) are calculated using liner materials MS, Cu, Al, Fe and Ta at these velocities. For instant Al has highest velocity and shorter time to get stable velocity so it would be useful for large standoff applications and in tandem warhead with contact fuse as a precursor cone where quick response is needed. The Ta EFP has larger diameter because of low thermal softening exponent, high density and larger hardening exponent which indicates its application where wide crater in the target is required. The Fe has diameter very close to Ta that is why, Fe is very economical alternative for same application. The temperature generated within the Ta EFP is highest, so Ta can also beused in the applications where hot fragments are required. The L/D ratio for Cu EFP at stable velocity is highest which supports maximum penetration. The MS is most reliable or stable liner’s material due to minimum divergence. So this material would be effective replacement of Fe in the multiliner EFP with Ta aspenetrator and Fe as stabilization base. The compression and shock pressure generated in MS EFP are highest, which means MS is most shock absorber material. Each liner material has different velocity profiles due to density gradients. The velocity decaying rate of the liner material is inversely proportional to its density means higher the density lower is the decaying rate. Other material parameters also have infinitesimal effect on the velocity decaying rate
IMPACTS OF UNTREATED EFFLUENT MIXING ON SURFACE AND GROUND WATER QUALITY
No full textDuring this research water quality in Ravi River was assessed properly through site surveying and sampling. Untreated effluent from communal and industrial sectors is seriously damaging the surface water quality in Ravi River. Analyses of effluent from Lahore city was showing very high rate of pollutants. During the investigation period the Biological Oxygen Demand (BOD-5) of effluent had been increased from 410 mg/L to 495 mg/L, Chemical Oxygen Demand (COD) from 815 mg/L to 870 mg/L and Total Solids (TS) from 1280 mg/L to 1400 mg/L. This might be due to the fact that there is a rapid growth of urbanization in Lahore City and the municipality conditions are becoming worse day by day. Samples were also collected from selected location along river and as well as groundwater reservoir in the study area. Collected samples were analyzed for different water quality parameters like pH, Total Dissolve Salts (TDS), Electric Conductivity (EC), temperature, hardness, magnesium, calcium, chloride, sulfate etc. Laboratory results of these analyses from selected locations indicates that low flow conditions in Ravi River along with high rate of contaminants are also damaging the ground water sources in the study area. Investigations show that unhygienic condition of Ravi River is seriously increasing the negative impacts on surrounding environment and aquatic life of the river. Proper treatment of communal and industrial wastewater is necessary to improve the surface and ground water conditions in the area studied
HIGH STRAIN RATE DEFORMATION BEHAVIOR OF AISI 420F
No full textAISI 420F is increasingly used as a mould material for injection molding of plastics. High speed machining of Ramax-2 leads to high strain rates at the tool-workpiece interface. The high strain rate response of Ramax-2 is investigated using split Hopkinson pressure bar at strain rates ranging from 3400 s-1 to 4500 s-1. Ramax-2 exhibits a strain rate sensitive behavior showing higher flow stress and strain hardening as compared to quasi-static tests
ASSESSMENT OF RESISTANCE TO RUTTING OF ASPHALTIC MATERIAL USING A WHEEL TRACKER
No full textAsphalt pavement rutting is one of the most common pavement distresses, observed in Pakistan as a consequence of increased tire pressures, slow moving heavy loads and high temperature. Maintenance and rehabilitation costs of flexible pavements are alarmingly high. A laboratory based evaluation of resistance to rutting of six mixes using three asphalt cement types i.e. Polymer modified Asphalt, 60/70 and 40/50 penetration grade was conducted at standard wheel loading of 700+20 Newton on wheel tracker and varying temperature levels i.e. 25, 40, 55oC. Relationships between rutting and factors effecting rutting have beenestablished and ranking of mixes based on regression coefficients were performed. It was revealed from the current study that mixes with coarser gradation and polymer modified asphalt showed better resistance against rutting and obtained a better ranking. Linear trends have been observed between the increase in temperature and rut value
IMPLEMENTATION OF KANBAN SYSTEM AT THE SHOP FLOOR OF A MULTINATIONAL COMPANY
No full textStreamlining and managing flow of material ¡n high volume production lines reduce the cost in terms of reduction of Work-In-Progress (WIP). Kanban system, which acts as a nerve of JIT production, is being used worldwide due to its simplicity and ability to reduce inventories and production lead times. This paper presents a case study of a successful attempt of implementation of Kanban System (KS) at shop floor of a Multi National Tobacco Factory (MNTF). A traditional Push system was replaced by Pull system with the objectives to reduce filter rods and quantity of raw material at workstations. The conversion from PUSH lo KS simplifies the material issuing procedure and benefits the company by reducing lead-time, Work-In-Process and inventory of finished items. The reduction of WIP is estimated about 59% which resulted in 42.99 million Pakistani Rupees (PKR) savings for the company
ON THE INTEGRATION OF A PRODUCTIVITY MODEL INTO AN OPTIMAL PREVENTIVE MAINTENANCE SCHEDULING MODEL
No full textMaintenance productivity measures how efficiently and effectively resources are utilized, while maintenance scheduling is concerned with an orderly arrangement of jobs for maintenance with the aim of restoring facilities for use within the shortest possible time and at the minimum cost. Since both maintenance productivity and maintenance scheduling aim at achieving important maintenance organizational goals, integrating modules from either side would permit measurement of scheduling performance with resource optimization. This paper integrates a productivity model with a maintenance scheduling model in a holistic manner that lakes advantage of the good attributes of each of the models. A binary Gantt charting model for a multi-facility multi-period framework with schedules carried out in contiguous periods is used. The objective is to minimize the total preventive maintenance cost. The productivity model utilized is expressed as output to input ratio. The results obtained reflect the flexibility of integrating these two models. Managers and decision-makers can use the information to decide on the effective utilization of resources. The paper seems to be the first documentation on the issue of integration between productivity and scheduling in a maintenance organization
AN INNOVATIVE METHOD FOR DESIGN OF DISTRIBUTION TRANSFORMER
No full textDistribution transformer ¡s one of the major equipment for electrification of any country. In the case of developing countries, the distribution transformer sector assumes a critical importance in view of the ever increasing its demand. This paper describes a methodology for obtaining cost effective design of distribution transformer. The comparative all day efficiency of a distribution transformer in rainy season has been evaluated
SINGLE CASCADE SIMULATING MOVING BED PROCESS WITH DIFFERENT COLUMNS CONFIGURATION FOR BINARY SEPARATION OF AMINO ACIDS
No full textIn this work, the binary separation of phenylalanine and tryptophan with different chromatographic column configurations was studied. Although the operational flow scheme is important in simulating moving bed (SMB) process, limitations in design of the scheme remain. The non-linear separation system is modeled with the Aspen Chromatography simulator in a four zone SMB on the basis of performance parameters such as purity, enrichment, productivity and yield. In addition, the separation of the binary system is also examined for a modified conventional SMB process, that is, Varicol. Furthermore, we investigated how subdivisions of chromatographic bed in a zone affect the wave dynamics and separation performance. Results of this study can provide guidance in operational flow schemes with different options of chromatographic column configurations for the design of SMB and Varicol processes for this binary separation or for a specific objective in the selected performance parameters
MODELING AND SIMULATION OF A PROPAGATING CRACK AT A BI-MATERIAL INTERFACE UNDER IMPACT LOADING USING LS DYNA
No full textThis paper presents simulation of a propagating crack at a bimaterial interface. The computation simulates dynamic crack propagation experiments conducted on a modified Hopkinson bar. Commercial purity Aluminum and automotive steel 440 WGA are used to constitute a layered bi-material interface. Two configurations are tested, the first with the initial crack in aluminum and the second with the initial crack in steel. The crack tip stress in steel is higher than the crack tip stress in aluminum due to a higher modulus of elasticity of steel. With the initial crack in steel, it is expected that the propagating crack will run out of energy and as it enters aluminum it will get arrested due to crack tip plasticity. In both configurations higher impact velocities led to higher crack initial energies
TYPE I (α) ERROR AND ARL PERFORMANCE OF SHEWHART CONTROL CHART WITH INTERPRETATION RULES
No full textThe Shewhart Ẋ chart is very popular tool in practice usually supplemented with interpretation rules in order to detect the small shifts in the process mean. In this paper an EXCEL spread sheet model for the normal and gamma distributions were developed for the calculations of the type I (α) error and ARL performance of individual and combination of the Shewhart Ẋ control chart with most used seven interpretation rules. The EXCEL spread sheet model was than compared with SIMULA TION model developed in MA TLAB. The results show that the type I (α) error performance can be fairly high for particular rules 1, 4 and 6 when the underlying data is from a gamma distribution rather than normal distribution. It was also observed that the high type I (α) error and low ARL performance of gamma distribution is present when the combinations of rules were used