Latest issue

by R. Brancati, U. Montanaro, E. Rocca, S. Santini, F. Timpone

Vol. 7. n. 4, pp. 583-591

Abstract - This paper is concerned with the analysis of systems with gears. An experimental set-up is presented to study the complex behavior exhibited by this class of dynamical systems, focusing in particular on all those phenomena associated to noisy operation. Specifically, using an appropriate model of the experimental rig, the coexistence of several periodic orbits characterized by different numbers of impacts per period is shown to be a fundamental mechanism in organizing the system dynamics. The system of interest is characterized by helical involute tooth pairs. The presence of damping due to squeeze oil effects is taken explicitly into account. The aim is to uncover the effects of such damping on the complex behavior exhibited by the system. Preliminary two-parameter bifurcation diagrams will be presented together with phase space trajectories to support the analysis.

Keywords: Gear Rattle, Bifurcation, Chaos, Lubrication, NVH, Noise.

by Lincoln Nascimento Ribeiro, Claudia Regina de Andrade, Edson Luiz Zaparoli

Vol. 7. n. 4, pp. 592-598

Abstract - Numerical Simulation of the two dimensional incompressible airflow in an asymmetric diffuser using one commercially available Computational Fluid Dynamics (CFD) code are reported. The subject is to analyze the effect of diffuser angle on the reattachment point of air flow. Results are presented varying diffuser angle from 2 degree to 20 degree. The mathematical model equations (mass conservation and momentum) are solved using finite volume methods (FVM) and a pressure based approach. To get the grid independent, intensive refinement studies were carried out. Results obtained were compared to experimental data presenting a good agreement. The numerical results of this work show that as the diffuser angle elevates, the flow recirculation region also increases. When there are flow recirculation regions, the value of turbulent kinetic energy also increases. Hence, it is possible identify a need for improvement the design of diffuser or other alternatives to reduce the size of recirculation region, reducing the power necessary at the flow machine to realize the work at the diffuser.

Keywords: Diffuser, Incompressible Air Flow, Separation and Reattachment Point.

by F. I. Petrescu, R. V. Petrescu

Vol. 7. n. 4, pp. 599-606

Abstract - The paper presents an original method to increase the efficiency of a mechanism with cam and follower. The distribution mechanisms work with small efficiency for about 150 years; this fact affects the total yield of the internal heat engines. Much of the mechanical energy of an engine is lost through the mechanism of distribution. Multi-years the yield of the distribution mechanisms was only 4-8%. In the past 20 years it has managed a lift up to the value of 14-18%; car pollution has decreased and people have better breathing again. Meanwhile the number of vehicles has tripled and the pollution increased again. Now, it’s the time when we must try again to rise the yield of the distribution mechanisms. This paper treats only two modules: the mechanism with rotary cam and plate translated follower and the mechanism with rotary cam and translated follower with roll.

Keywords: Cam Dimensions, Efficiency, Distribution Mechanism with High Efficiency, Distribution Settings, Distribution Parameters.

by Xu Wang, Han Xiao

Vol. 7. n. 4, pp. 607-624

Abstract - Conversion of vibration energy in a structure, machine or vehicle into electric energy will improve reliability, comfort and energy utilisation efficiency, and can potentially reduce the amplitude of vibration and associated damaging effects. An analytical approach is proposed in combination of frequency analysis and time domain simulation. The main advantage of the approach is its capability to predict harvested resonant power and energy harvesting efficiencies of mechanical systems with built-in piezoelectric material, from a resonant frequency, mechanical damping, external load resistance and piezoelectric material properties regardless of the system size. The approach allows for prediction of output voltage and harvested resonant power from measured field vibration acceleration data. It allows for a parameter study and optimization of piezoelectric vibration energy harvesters. The dimensionless harvested resonant power and energy harvesting efficiency formula developed from this paper are useful for performance evaluation of the vibration energy harvesters ranging from macro to micro scales, even to nano scales. Potential industrial applications would be in ambient vibration energy harvesting analysis for machines or structure systems with built-in piezoelectric material. These systems may include engine torsion vibration absorbers (engine harmonic balancer), vehicle chassis suspension/mounting systems, vehicle power-train suspension/mounting systems, wheels and tyres or vehicle body panels. The harvested electric energy is expected to be used to power electronic devices, self-sustaining micro- and nano-scale sensors, or remote sensing systems including automotive electronics, sensors or wireless sensor nodes.

Keywords: Dimensionless, Frequency Analysis, Piezoelectric, Time Domain Simulation, Vibration Energy Harvesting.

by Eleni C. Douvi, Dionissios P. Margaris, Sotirios D. Lazaropoulos, Stylianos G. Svanas

Vol. 7. n. 4, pp. 625-631

Abstract - The influence of different rain rates on the aerodynamic performance of the NACA 0012 airfoil with a low Reynolds number of 1×10⁵ was investigated. Wind tunnel tests were conducted to determine lift and drag coefficients at various angles of attack in both dry and wet conditions and the results were compared to show the effects of Liquid Water Contents (LWC) at airfoil performance. Four different rainfall rates were simulated by injecting water droplets from commercial rain simulation nozzles upstream of the airfoil model, corresponding to LWCs of 20.548 g/m³, 37.745 g/m³, 41.096 g/m³ and 75.491 g/m³. A computational fluid dynamics code was utilized to gain further knowledge on the flow field. The simulation of rain was accomplished by using the two-phase flow Discrete Phase Model. It was concluded that degradation of aerodynamic performance increases with increasing LWC up to stall angle and stall is delayed for all rain rates. The computational results showed that larger droplets were more susceptible to droplet breakup than smaller droplets and generally breakup near regions with severe pressure gradients, close to the airfoil. The water film height and the location of rivulet formation on the upper surface of the airfoil are also presented.

Keywords: Aerodynamic Characteristics, Airfoil, Liquid Water Content, Rivulet Formation, Water Film.

by S. Syamsuar, E. B. Djatmiko, P. A. Wilson, Erwandi, Subchan

Vol. 7. n. 4, pp. 633-645

Abstract - Many of the Wing In Surface Effect-craft had unstable condition during hydro planing while the positive pitching moment nose up increases. The hump drags on the centre of buoyancy, the aerodynamic lift of the wing on the centre of pressure, the thrust propulsion and weight on the centre of gravity are not in equilibrium condition. The inverse delta wing with shoulder and Clark Y airfoil having wing area 31.75 m² and V-tail configurations are producing the aerodynamic lift. However, the aerodynamic lift will be countered by pitching moment in order to achieve steady level flight within airborne conditions. The adaptive control system will be implemented on the Remote Control model Amphibian configuration to anticipate the porpoising effect during hydro planing on the longitudinal and lateral mode. This control system also maintaining the ground effect on the 0.25 m altitude height to reduce the Pilot workloads. The use of Extended Kalman Filter algorithm is to identify the non-dimensional aerodynamic and hydrodynamic derivative parameters that used together in the observable matrix (4 × 4) dimensions in the real time (t).

Keywords: The Flight Performance, Hydro Planing, Hump Drag, Airfoil, Porpoising Effect.

by P. Thangavel, P. Somasundaram, P. Navaneethakrishnan

Vol. 7. n. 4, pp. 646-651

Abstract - This article represents the possibility usage of hydrocarbon refrigerants in vapour compression refrigeration systems as an alternate to conventional refrigerants like R12 and R134a. Hydrocarbon mixtures (HCMs) are having unique characteristics like eco friendly, better heat transfer, zero ODP and negligible GWP. Suitable safety precautions are to be implemented due to their flammability. Based on the thermo physical properties of the refrigerants, the standard performance parameters like pressure ratio, volumetric efficiency, discharge temperature, condenser heat rejection rate and COP are computed at different temperatures. The mixture of Propane (R290) and Isobutane (R600a) is considered as a refrigerant in this analysis at various mass fractions. The effect of condenser temperature (30°C to 65°C) with evaporator temperature of -10°C shows that the proposed HCMs having low pressure ratio & discharge temperature, higher volumetric efficiency & condenser heat rejection rate as compared to R12 and R134a. The effect of evaporator temperature (-30°C to 0°C) with condenser temperature of 40°C is also computationally analysised and similar performance results were obtained. Pressure ratio of HCMs is about 6.37% and 17.11% lower than R12 and R134a respectively and the volumetric efficiency is enhanced about 1.06% and 2.12%. The condenser heat rejection rate is also improved about 57.86% and 46.49% greater than R12 and R134 respectively. The results also prove that COP of the HCMs is approached very close to R12 and R134a.

Keywords: HCMs, COP, Heat Transfer, Condenser & Evaporator Temperatures.

by Khatir Naima, Abdelkrim Liazid

Vol. 7. n. 4, pp. 652-663

Abstract - This paper deals with the subject of natural gas-Hydrogen blends as alternative fuel for spark ignition engine. First, a brief overview on previous works in this field was presented. Then, a numerical investigation focused on the effect of hydrogen addition on the performances and emissions was also presented. A CFD approach using CONVERGE CFD Code was applied on a direct injection spark ignition engine at low regime and lean mixtures. A detailed chemistry associated with AMR (Adaptive Mesh Refinement) technique was adopted. To illustrate the effect of hydrogen addition to natural gas, three hydrogen fractions are considered 0%, 10% and 18%. The obtained results show that the promotion of the chemical reaction with hydrogen addition is mainly due to the increase of free radicals H, O, OH in the flame as a result of hydrogen addition. Hence, the heat release rate starting is advanced with the increase of hydrogen fraction while the combustion duration decreases. It is observed that the heat release rate and the maximum in cylinder temperature increase when hydrogen is added. Exhaust CO emissions decreases with the increase of hydrogen fraction, while NOx emissions increase. Hydrogen addition could give a great potential to reduce soot formation.

Keywords: Natural Gas, Hydrogen, Mixture, Engine, Combustion, Pollution.

by Talaat A. Ibrahim, Mohamed A. M. Hassan

Vol. 7. n. 4, pp. 664-672

Abstract - This paper presents experimental results of the condensation heat transfer characteristics for pure refrigerants R22 and R134a, binary refrigerant R410A and non-azeotropic mixture R407C on single horizontal smooth and finned tubes. The experiments were conducted at saturated temperature (35 °C and 40 °C), inlet coolant temperature (25 °C and 30 °C) and coolant mass flow rate (100 - 800 kg/h) resulting refrigerant mass flux of 20 – 400 kg/m²s for smooth and finned tubes. For finned tubes, the pitch to height ratio varies from 0.5 to 3.08. Experimental results confirmed that the heat flux and the overall heat transfer coefficient for R22, R134a, R410A and R407C increase when coolant mass flow rate, saturation temperature and fin height increase or as both coolant inlet temperature and fin pitch decrease. The heat flux and the overall heat transfer coefficient for R410A were correlated with the investigated parameters. Comparison among four refrigerants; R410A provides better condensation heat transfer characteristics and it yields higher condensation heat transfer coefficients than those of other refrigerants by 8 to 27%. However, the condensation heat transfer coefficients of R407C are much lower than those of other refrigerants for all investigated parameters. As a replacement of R22, R410A has more advantages than R407C in view of condensation heat transfer characteristics.

Keywords: Condensation Heat Transfer, Smooth and Finned Tubes, R22, R134a, R410, and R407C.

by Watit Pakdee, Cattaleeya Pattamaprom, Sirichai Phanumnuay

Vol. 7. n. 4, pp. 673-678

Abstract - This study investigates how an incomplete tranesterification reaction influences the parameters of quality standards of the produced biodiesel engine performance and exhausts. The parameters evaluated include viscosity, cloud point, acid number and heating value. Biodiesels produced from palm oil were examined in terms of engine performance, where the 3-liter engine with a 4 cylinders 4 strokes, was used. The proportion of methyl ester in biodiesel was varied by adding appropriate amounts of triglyceride. Properties of biodiesel with the methyl ester between 75% and 96.8% by mass were tested against the standard diesel. The engine performance and thermal efficiency when using biodiesels of different qualities were determined under the operating engine speed range between 1,800 and 4,000 rpm. It was found that while the cloud point was raised with methyl ester content the viscosity was decreased. In terms of engine performance, greater proportion of methyl ester provides greater fuel conversion efficiency as well as specific fuel consumption rate. Incomplete conversion of triglyceride to methyl ester, which led to lower methyl ester content, significantly affected the engine performance and emissions. In overall, biodiesel with higher methyl ester content provided better engine performance and exhaust quality.

Keywords: Biodiesel, Palm Oil, Methyl Ester, Triglycerides, Transesterification, Engine Performance, Exhaust Gases.

by Moustafa A. Fouz, Amgad M. Bayoumy Aly, Sohair F. Rezeka

Vol. 7. n. 4, pp. 679-685

Abstract - Some articulated robotic manipulators, such as ED-7220C robotic arm, have most of their actuators located at the robot base. Power is transmitted from the motors via spur gears and timing belts to robot links. Consequently, the motion of robotic links are not related to each other, but related to the base of the robot. This kind of robot designs has many advantages, but the main disadvantage is that the links may collide with each other due to geometric constrains. Collisions consume the operator’s awareness, exertion, and also consume time. Collision avoidance algorithm is developed and presented. A simple GUI is also developed to provide an easy way to drive the robot. The developed algorithm is tested to the robot and shows a good response with zero collision under normal operating conditions.

Keywords: Collision Avoidance, GUI, Robotic Manipulator, Self-Collision.

by V. Chandraprabu, G. Sankaranarayanan, S. Iniyan, S. Suresh, V. Siva

Vol. 7. n. 4, pp. 686-691

Abstract - In the present investigation, nanofluid contains suspension of nanoparticles (Al₂O₃) in water (base fluid) with different concentrations (1%, 2%, 3% and 4% by volume) are prepared. Nanofluid taken as a cold fluid in the condensing unit of air conditioner and the heat transfer rate has investigated. Experimental results emphasis the enhancement of heat transfer rate by 1.77% to 37.35% due to the nanoparticles presence in the cold fluid. Coefficient of heat transfer is increases with increase in volume concentration of nanoparticles in the base fluid.

Keywords: Nanofluid, Condenser, Air Conditioner, Heat Transfer Enhancement.

by M. Ferdows, Shamima Islam, Raushan Ara Quadir

Vol. 7. n. 4, pp. 692-697

Abstract - The problem of Marangoni heat transfer boundary layer flow using water based nanofluid containing nanoparticles including Ag, Cu, Al₂O3 and TiO₂ embedded in a variable viscosity & thermal conductivity medium is analyzed. The governing boundary layer equations (momentum and thermal boundary) are transformed into nonlinear ordinary differential equations by using the appropriate similarity transformations and were solved by using Maple software. Solution of the governing equations are presented for different values of the governing parameter such as the effect of nanoparticle volume fractions, viscosity parameter and conductivity parameter to demonstrate the important influence of these parameters in terms of velocity and temperature as well as surface gradient velocity and temperature gradient.

Keywords: Nanofluid, Boundary Layer, Marangoni Heat Transfer, Viscosity Variable, Thermal Conductivity.

by S. Ravi, R. Subramanian

Vol. 7. n. 4, pp. 698-704

Abstract - Diesel engines are widely used for transportation and power generation due to its better performance, reliability and durability. For the past three decades, there has been a consistent worldwide demand for the diesel fuel and quality, which resulted in degraded engine performance and increased pollutant concentration. At present demand for better diesel fuel is more. Diesel fuel quality can be improved either by better processing or with the use of additives. Additive treated fuel contributes to improve the performance, reduce emissions and gives longer life of the engine. Detergents and dispersant, cleanliness additive, cetane improver, combustion modifier and multifunctional additives are the major groups of additives. Detergent additives effectively prevent the buildup deposits, while dispersant include cleaning and disperse particulate matter in an extremely fine state. Cleanliness additives are organic detergents, to prevent deposits formation in the fuel injection system and maintain the injection system cleanliness over the useful life of the engine. Cetane improvers control the ignitability of diesel fuel, when it is sprayed into the combustion chamber and reduce the ignition delay period for the fuel. Combustion modifier is a group of metallic or ash containing additive, which is added in the fuel with a level of parts per million. The objective of the present paper is to give an overview about performance and emission of the combustion improving diesel fuel additives.

Keywords: Cetane Number, Diesel Engine, Fuel Additives, Oxides of Nitrogen, Particulate Matter.

by L. Karikalan, M. Chandrasekaran, K. Sudhagar

Vol. 7. n. 4, pp. 705-715

Abstract - The rising energy needs resulting from increased claim and diminishing supply, alternative energy sources are receiving more attention. In addition, the increasing global concern has caused to focus on the oxygenated diesel fuels because of the environmental pollution from internal combustion engines. Vegetable oils possess almost the same heat values as that of diesel fuel with inherently high viscosity. Vegetable oil is easily available, renewable fuel with short carbon cycle period and is environment friendly. These are the triggering factors for research all over the world to consider vegetable oils and their derivatives as alternative to petroleum diesel. Researchers experimented that vegetable oil fuelled engine power output and fuel consumption are comparable to diesel when fuelled with vegetable oil and its blends and produce less carbon monoxide (CO), unburned hydrocarbon (HC), and particulate emissions compared to mineral diesel fuel but higher NOx emissions than that of pure diesel fuel. This paper reviews the various production techniques, properties of vegetable oil and its biodiesel along with the challenges faced and experiments carried out by various researchers around the world.

Keywords: Vegetable Oil, Biodiesel, Combustion, Performance and Emissions.

by M. A. Fairuz, M. R. M. Hafiezal, R. Hussin, S. A. Adam, A. F. Aiman

Vol. 7. n. 4, pp. 716-720

Abstract - The demand of high accuracy aerospace parts become important which is reflected by the machining process performances. Inconel 718 is a well-known superalloy in aerospace industries especially in turbine fabrication. The aim of this research is to study the performance of Wire-EDM process in term of material removal rate (MRR) and surface roughness. The constraints of the research focused to five parameters; pulse duration, pulse interval, peak current, servo voltage and flushing pressure. The relationship between MRR and surface roughness is presented which exhibit the behavior of the WEDM process. The MRR is calculated based on the measurement of kerf width and time. Surface roughness is measured using surface roughness tester in mean arithmetic roughness (Ra). The experiment data are analyzed using ANOVA in Response Surface Methodology (RSM). The result shows that the most significant parameter is pulse duration.

Keywords: Wire Electrical Discharge Machining, Response Surface Methodology.

by M. S. Hussin, M. F. M. A. Hamzas, Z. A. Zailani, A. B. Sanuddin

Vol. 7. n. 4, pp. 721-726

Abstract - This thesis documents a research on continuously improvement of process in EUROSPAN Furniture Sdn Bhd. The process improvement focused on dining table’s assembly line. High products variety and flexibility becomes the main challenges of production floor. As to improve the productivity, there are few factors have been considered in this thesis; redesign of workflow layout, labor utilization and continuous flow. Line balancing had been used to analyze the utilization of the current state pull system. Several techniques have been suggested such as 5Why’s analysis, line balancing and Single Minute Exchange of Die (SMED) in order to eliminate and minimize non-value added activities and to enhance the new work cell production. Results indicated manpower has been effectively reduced by 30% in the new production system and the productivity has increased successfully by 45%. The effectiveness of the new system in this study gave positive impact on productivity, flexibility and production utilization.

Keywords: Assembly Line, Products Variety, Pull System, Non Value Added, Work Cell Production.

by M. S. Bahari, A. B. Sanuddin, I. K. Marlina

Vol. 7. n. 4, pp. 727-733

Abstract - This paper presents the investigation of the effect of fused deposition modeling (FDM) parametric processes on the tensile strength of the developed acrylonitrile butadiene styrene (ABS) compliant prototype. The prototype is produced using prodigy plus FDM machine with Insight 7.2 software. Four essential process parameters include layer thickness, part interior style, raster width, and raster angle are considered. The effect of these parameters on the tensile strength of ABS prototype is studied. Experiments are conducted in accordance with Taguchi’s design of experiment with three levels for each factor. The tensile strength of the models is tested using universal testing machine (UTM). The results are statistically analyzed using analysis of variance (ANOVA) in order to determine the optimal parameter which affects the tensile strength characteristic significantly. From the analysis, it was found that the part interior style parameter affects the tensile strength performance more greatly than others.

Keywords: Rapid Prototyping, Fused Deposition Modeling, Taguchi Method, Tensile Strength.

by Prasanta K. Sinha, A. K. Biswas, B. Majumdar

Vol. 7. n. 4, pp. 734-739

Abstract - In the present investigation the distribution of mean velocity, static pressure and total pressure are experimentally studied on a C-shape diffuser of 40° angle of turn with an area ratio of 1.284 and centerline length was chosen as three times of inlet diameter. The experimental results then were numerically validated with the help of Fluent and then a series of parametric investigations are conducted with same centre line length and inlet diameter but with different area ratios varying from 1.25 to 2.0 and angle of turn 30° to 75°. The measurements were taken at Reynolds number 2.25 × 10⁵ based on inlet diameter and mass average inlet velocity. Predicted results of coefficient of mass averaged static pressure recovery (48%) and coefficient of mass averaged total pressure loss (12%) are in good agreement with the experimental results of coefficient of mass averaged static pressure recovery (45%) and coefficient of mass averaged total pressure loss (11%) respectively. Standard k-ε model in fluent solver was chosen for validation. From the parametric investigation it is observed that for the increase in area ratio from1.25 to 2.0, static pressure recovery increases sharply but with the increase of angle of turn pressure recovery decreases steadily. The coefficient of total pressure loss almost remains constant with the change in area ratio and angle of turn for similar inlet conditions.

Keywords: C-Shape Diffuser, k-ε Model, Fluent Solver, Five-Hole Probe.

by M. S. Hussin, A. B. Sanuddin, Z. A. Zailani, M. F. M. A. Hamzas

Vol. 7. n. 4, pp. 740-744

Abstract - The Air Remover Fan is a device that base on process of solving a temperature problem inside a car during parked under the direct sunlight or open area for a long period. When a car is parked for certain period in this condition, the temperature inside the car cabin will be high from the ambient temperature. Sometimes the temperature inside the car will be double from the ambient temperature. To solve this problem, the Air Remover Fan is introducing as a device to reduce the hot temperature air inside the car. The device is operate by using the temperature sensor which is it automatically operates when the sensor detect the 33°C temperature and the system will allow the fan to suck the hot air inside the car cabin to the outside through the car boot. The improvement of product will be focusing in designing the fan blade which is to choose the best selection of fan blade design, find the correct angle of the fan and fan casing which is to get the best design for ‘Air Remover Fan’.

Keywords: Air Remover Fan, Automatic Solar-Powered Car Ventilator.

by M. S. Hussin, Z. A. Zailani, M. F. M. A. Hamzas, A. B. Sanuddin

Vol. 7. n. 4, pp. 745-749

Abstract - The purpose of this study is to investigate the core thickness undersized problem which is very common with honeycomb core cutting. These defects occur during the honeycomb core cutting by using core block saw machine. There are number of variable causes of the defect. The author is use statistical approach to identify critical variable causing of this defect. There are use two method of the quality tool such as Ishikawa Diagram and also Five Why Method. However the revolutionary read of core thickness undersized is collected to analyze. Minitab software is used for the analysis propose and certain improvement are suggested.The defect is occurred during the during the core block saw cut the core block to be a slicing.

Keywords: Core Thickness, Composite Panels, Undersized.

by Sanaa Ali Hamza, ErryYulian T. Adesta

Vol. 7. n. 4, pp. 750-756

Abstract - The role of Feasibility Assessment (FA) is critical for Cellular Manufacturing (CM) that based on Group Technology (GT) concept, particularly during the design phase. The results may be used in decision making process to decide whether or not job shop may be converted into CM. Through FA some procedures are followed to identify the right predicted cells number that leads to create effective CM. In this article two methods of predicting a number of cells have been examined. The first method is supported by the number of machines in the incidence matrix and the pre-determinable maximum number of machines in each machine cell. The second method was based on Rogers and Tanimoto Similarity Coefficient and Eigenvalues of the Similarity Coefficient Matrix. Ten data sets selected from literatures are used to test these two methods. The results show that the first method is less accurate, depends on trial and error, and has multi values where most of those values are not integers. On the contrary, the second method is very accurate, has only one solution which is an integer value. Therefore it may be considered as a more efficient method. Furthermore, this study suggested an efficient and logical sequence of these two methods in order to identify the performance of the existing methods that are used in solving cell formation problems.

Keywords: Cellular Manufacturing, Feasibility Assessment, Similarity Coefficients, Cell Formation, Eigenvalues.

by Subhasish Das, Biprodip Mukherjee, Asis Mazumdar

Vol. 7. n. 4, pp. 757-766

Abstract - With the increase demand of water in an urban area it becomes necessary to increase the capacity of the water pipeline networks by keeping the pipes and valves elements unchanged as it is very difficult work to change those in an urban area due to inaccessibility. This paper presents a study on characteristics of mainly hammer head at increased flow demand in pipeline networks using HAMMER software. For modeling the pipeline distribution networks, the parameters of the pipes, junctions and other elements were inserted in the above software according to the layout of distribution network of Dhapa water treatment plant, Kolkata Municipal Corporation, West Bengal, India. The flow capacity of the pipeline networks were increased in the order of 25 percent, 50 percent, 75 percent and 100 percent more than the existing flow capacity of the above networks and the transient analyses were done accordingly. Increasing trends of hammer head, pressure and circumferential stress with respect to increased flow demand were observed for all the zones which satisfy the basic equation for water hammer theoretically. It was also checked whether the pipes are safe for taking the load of increased flow demand.

Keywords: Flow Demand, Hoop Stress, Pipeline Network, Transient Analysis, Water Hammer.

by Suleiman M. Obeidat, Wisam M. Abu Jadayil, Nabeel F. Mandahawi

Vol. 7. n. 4, pp. 767-773

Abstract - Realizing the nature of the manufacturing process used to make a part can help determine the locations and the optimum number of inspection points. Face and End milling processes are used in this work to produce plates and sheets. A Finite Element Analysis (FEA) model has been developed for cutting of flat plates. That model helps minimizing the number of inspection points. That model suggests that maximum error is in the regions near the center of the plates and sheets. Experiments have been conducted to verify the model. Four pieces of flat plates and two sheets have been made then inspected using coordinate measuring machine (CMM). The experiments showed that the reduction in number of inspection point, in face milled flat plates, reached to about 95.5% compared to the number of population points with a difference in tolerance of about 2.8%. Also, the results showed that the reduction in the number of points, in end milled sheets, reached to 95.6% with a percentage difference in the tolerance of about 7.1%.

Keywords: Inspection of Flat Plates, Critical Sampling Points, Workpiece Deflection, CMM.

by J. Ju, Y. S. Wang, Y. F. Xing, G. Q. Shen, H. Guo

Vol. 7. n. 4, pp. 774-782

Abstract - Based on a sample vehicle, a whole procedure for objective sound quality evaluation (SQE) of interior noise is conducted in this paper. Typical vehicle interior noises under different working conditions are measured at both the driver and rear passenger seats. The traditional A-weighted sound pressure level (SPL) and some psychoacoustical indices, such as loudness, sharpness and roughness of the measured noise signals are investigated. A new roughness model combined by the Aures’ and Daniel’s models for nonstationary vehicle noises are performed by Matlab programming and verified by the commercial software. In view of the calculated results, the loudnesses at the positions of the front and the rear passengers show in different changing patterns with the vehicle speed increasing; the sharpness heard by the rear passenger is always lower than that by the driver; and the roughness at the front passenger place (higher than the rear ones) can be mainly attributed to the speed changing components during vehicle accelerating. The conclusions drawn in this paper are very useful for acoustical design and improvement of the sample vehicle. And the presented SQE procedure may be possibly extended and used for SQE of other vehicles or products in engineering.

Keywords: Vehicle, Interior Noise, Psychoacoustical Index, Sound Quality Evaluation (SQE).