Feasibility study of vacuum technology integrated fused deposition modeling to reduce staircase effect

Fused deposition modeling (FDM) is currently one of the most used AM technologies and has been around in various industries since its tremendous offering. Most semi-molten layered thermoplastic surface often uneven, which lead to rough and poor surface finish. The FDM process involves temperature gradient since the material extrude was in a semi-molten state. The thermal stresses present and affect the surface quality. This paper proposes an idea of using vacuum technology to reduce the “staircase effect” parts printed. The FDM machine remains in a rectangular acrylic chamber, an oil-flooded-vacuum pump connected will absorb the air inside the chamber until desire pressure while printing object. Mitutoyo SJ-301 portable surface roughness tester and optical microscope used to analyze the quality of surface finish. Result reveal with vacuum technology, improve 9% from normal print.Keywords: fused deposition modeling; simulation; vacuum technology; surface finis

Analysis awkward posture at food production activity using RULA assessment

If the workers continuously perform the activities throughout the working hours, they may experience prolonged standing which creates fatigue and causes an occupational hazard which includes slips and falls. The goal of this study was to identify awkward postures during food production activities. 40 workers with minimum of 1 year experience working in food production were involved. The comfort level was measured using Rapid Upper Limb Assessment and Computer-Aided Three-Dimensional Interactive Application software analysis, expressed in scoring level. Critical activities grilling meat, frying, dish cloth and wash utensil at food production contributed to high RULA score of 7. The specific working postures have to be identified among food production workers. This study can provide a preliminary data to determine the correct working postures for food production workers.Keywords: working position; food production; awkward posture; RULA score, fatigue and standin

Vacuum fused deposition modelling system to improve tensile strength of 3D printed parts

Functional parts require high a level of strength and the current Fused Deposition Modelling (FDM) cannot be fully utilized as the end used parts. The poor mechanical strength is caused by the incomplete layer bonding during the printing process. In the printing process, the interlayer bonding is made too quick thus the layers are not fully fused together causing the reduced tensile strength. This paper presents a possible solution to this problem by incorporating vacuum technology in FDM system to improve tensile strength of 3D printed specimens. In this study, a desktop FDM machine was placed and operated inside a low pressure vacuum chamber. The results obtained show an improvement of 12.83 % of tensile strength compared to the standard specimen. This paper concludes that the low pressure environment is useful in reducing the heat loss due to convection of air, hence directly improves the specimen’s tensile strength.Keywords: additive manufacturing; fused deposition modelling; vacuum system; mechanical strength

Key performance indicators for measuring sustainability in health care industry in Malaysia

The health care industry in Malaysia was the fastest-growth industry over the past few years. In today’s competitive business environment, companies focus on improving sustainability to reduce cost and improve well-being of the environment and society. However, there are limited published studies on the evaluation of sustainability performance for the healthcare sector. This paper aims to formulate a list of key performance indicators (KPI) for the sustainability performance. First, a literature study of KPIs from various industries was carried out. Next, an in-depth meeting was conducted to gain insights and feedbacks with the management of a private hospital. Finally, a set of 70 KPIs which can be used for measuring sustainability performance in health care industry was developed. These 70 KPIs were used to design a questionnaire which is then distributed to the private hospital.Keywords: key performance indicators; sustainability; health care industr

A numerical analysis of condenser performance of a seawater desalination system

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 31).This thesis presents the numerical analysis of three type condensers for desalination of seawater system. The condensers that were analyzed were a finned tube condenser that was built in Malaysia desalination plant, a cooling tube condenser in Jordan, and a common plate finned tube condenser. The goal of the analysis is to observe the thermal performance parameters of a condenser such as heat and mass transfer coefficient, surface effectiveness and condensate flow rate. The parameters that were changed in the analysis were the face velocity of air, the water velocity, and the number of rows of tubes. The numerical analysis was done based on basic heat exchanger analysis using e-NTU method for a dry case, and using a j-factor correlation that was developed by McQuiston for studying the wet case. Results from the basic heat exchanger analysis showed the air humidity ratio profile and temperature profile of air and water at the outlet of the condenser. The exit air temperature and humidity ratio were inversely proportional to the length of the condenser, whereas the temperature of the water at the outlet was proportional to the length of the condenser. Results from the j-factor correlation method show that the heat and mass transfer coefficient of the system increased when the number of rows of tubes, face velocity and water velocity increased. Similarly, the analysis showed that the condensate flow rate was highly influenced by the face velocity. In addition, the surface effectiveness was inversely proportional to the face velocity.by Hassan Mohamed.S.B

Experimental Analysis On Parameters Affecting The Material Removal Rate In Wire Electrical Discharge Turning Using The Taguchi Method

Wire electrical discharge turning (WEDT) allows success in the machining of advanced materials, particularly for the cylindrical shape components used in the metrology, medical and aerospace field. Using WEDT technology, the micro dimension of geometrical features can be machined without constraints on difficult-to-machine electrically conductive materials. The high precision with large aspect ratio machining capability make WEDT valuable. The correct machining parameter selection is the most important aspect to take into consideration when machining by WEDT. Therefore, the purpose of this study was to rank, determine and optimise the machining parameters that affect the material removal rate (MRR) in WEDT process. As WEDT has as much as eleven control parameters in this study, representing a large number of machining, the Taguchi L-12 orthogonal array was used to obtain the required data with a minimum number of experiments. By using similar experimental data, the regression equation was developed to represent as fitness function for optimisation by genetic algorithm (GA). It was found that by selecting the fast feed of workpiece to machining zone, the faster material was removed and moreover, it dominated other machining parameters. The optimised parameters yield 1.398 mm³/min as the maximum value predicted for MRR recommended by GA

Crushing behaviour of plain weave composite hexagonal cellular structure

The tradition of fibre composite materials in energy absorbing tube applications has gained interest in structural collisions in the composite materials industry. Thus, the subject of this work is the experimental investigation to understand the effects of the failure initiator at the specimen’s edge, causing the increase in the specific absorbed energy (SEA), as well as the influence of the cellular structure composed of cells with small hexagonal angle exhibited high energy absorption capability. An extensive experimental investigation of an in plane crashing behavior of the composite hexagonal cellular structure between platen has been carried out. The cellular structure composed of hexagonal cells with angles varying between 45 and 60°. The materials used to accomplish the study are the plain weave E-glass fabric as a reinforcement and the epoxy resin system as a matrix. Furthermore, the specific energy absorption increases as the hexagonal angle increases

The Effects Of Dry And Chilled Air On Tool Wear Behavior During Face Milling Of Inconel 718

Tool wear is one of the important criteria during the cutting process. It is mostly caused by the machining parameters, namely; cutting speed, feed rate, depth of cut, cooling condition, etc. This paper presents the behavior of cutting tool during dry and chilled air condition of face mill with the cutting speed of 20 to 40 m/min, the feed rate of 0.1 to 0.2 mm/tooth and axial depth of 0.1 mm. The analysis of variance (ANOVA) is applied to identify the significance of these factors effect on tool performance, later the mathematical model for the tool life prediction was developed. The investigation revealed that the cutting speed, feed rate dominating wear rate whilst the chilled air found to be marginally significant. Finally, the optimum condition for machining parameter for greater tool life can be obtained by the combination cutting speed of 20 m/min, the feed rate of 0.1 mm/tooth under chilled air condition. Implementation of chilled air contributed 7% improvement with 45 min compared to a dry condition. The study exhibited the round type insert of dry face milling is more prone to rapid flank wear than chilled air with no BUE appearance on the tool cutting edge

The geology and geophysics of Kuiper Belt object (486958) Arrokoth

The Cold Classical Kuiper Belt, a class of small bodies in undisturbed orbits beyond Neptune, are primitive objects preserving information about Solar System formation. The New Horizons spacecraft flew past one of these objects, the 36 km long contact binary (486958) Arrokoth (2014 MU69), in January 2019. Images from the flyby show that Arrokoth has no detectable rings, and no satellites (larger than 180 meters diameter) within a radius of 8000 km, and has a lightly-cratered smooth surface with complex geological features, unlike those on previously visited Solar System bodies. The density of impact craters indicates the surface dates from the formation of the Solar System. The two lobes of the contact binary have closely aligned poles and equators, constraining their accretion mechanism

Burden and risk factors for Pseudomonas aeruginosa community-acquired pneumonia:a Multinational Point Prevalence Study of Hospitalised Patients

Pseudornonas aeruginosa is a challenging bacterium to treat due to its intrinsic resistance to the antibiotics used most frequently in patients with community-acquired pneumonia (CAP). Data about the global burden and risk factors associated with P. aeruginosa-CAP are limited. We assessed the multinational burden and specific risk factors associated with P. aeruginosa-CAP. We enrolled 3193 patients in 54 countries with confirmed diagnosis of CAP who underwent microbiological testing at admission. Prevalence was calculated according to the identification of P. aeruginosa. Logistic regression analysis was used to identify risk factors for antibiotic-susceptible and antibiotic-resistant P. aeruginosa-CAP. The prevalence of P. aeruginosa and antibiotic-resistant P. aeruginosa-CAP was 4.2% and 2.0%, respectively. The rate of P. aeruginosa CAP in patients with prior infection/colonisation due to P. aeruginosa and at least one of the three independently associated chronic lung diseases (i.e. tracheostomy, bronchiectasis and/or very severe chronic obstructive pulmonary disease) was 67%. In contrast, the rate of P. aeruginosa-CAP was 2% in patients without prior P. aeruginosa infection/colonisation and none of the selected chronic lung diseases. The multinational prevalence of P. aeruginosa-CAP is low. The risk factors identified in this study may guide healthcare professionals in deciding empirical antibiotic coverage for CAP patients