In-Situ Preheating in Hybrid Layered Manufacturing for Tooling Elements

Solidification cracking of hard materials such as H13 tool steel is one of the major problems in metal based Additive Manufacturing (AM) processes. Hybrid Layered Manufacturing (HLM) is one of the metal based AM process which uses Metal Inert Gas (MIG) cladding for addition and CNC milling for subtraction of material. In this work, an in-situ induction heating based preheating system has been developed to solve the solidification cracking problem. The Tungsten Inert Gas (TIG) and Induction heating methods are compared and it has been found that the induction based preheating system can produce better microstructure and sound products. In the experimental procedure, before deposition of a layer the prebuild layer is preheated up to 350-5000C. Also the effect of in-situ preheating on the microstructure of the deposited layers have been studied using Scanning Electron Microscope (SEM).Mechanical Engineerin

Additive Manufacturing of Directionally Heat Conductive Objects

Purpose: Directionally Heat Conductive (DHC) objects are also known as thermal cables. DHC objects used in cooling solid state devices as large heat sinks. This paper presents Additive manufacturing (AM) as a new method for realization of DHC objects. AM can produce DHC objects accurately, rapidly and economically. Design/Methodology/Approach: It is very hard to realize DHC objects through conventional manufacturing. The authors describe the realization of metallic DHC objects using their AM process called Hybrid Layered Manufacturing (HLM). HLM, which uses GMAW deposition, can, in principle, produce DHC out of any metal for which welding wire is available. . Differential conductivity in HLM is achieved by appropriately distributing the air gaps among the beads. The air gap distribution depends on the layer thickness and step over increment. Findings: The authors have demonstrated the ability of HLM to produce DHC objects for Al alloy 4043. The thermal conductivity achieved on two orthogonal directions was 100.496 and 129.740 W m-1 K-1 as against 163 W m-1 K-1 for solid metal. These are significant variations. Research Limitations/Implications: HLM realize near net shape of DHC objects, further post processing namely machining is required. Originality Value: AM Specifically HLM for realization of DHC objectsMechanical Engineerin

Multiscale and spatial analysis of the effect of Indian forest patterns on large mammal distributions

International audienc

Etiology of blood culture isolates among patients in a multidisciplinary teaching hospital in Kuala Lumpur

Bloodstream infections are an important cause of morbidity and mortality among hospitalized patients and the surveillance of etiological agents in these infections is important for their prevention and treatment. Data on common organisms isolated from blood cultures from Malaysia are limited, and our aim was to identify the common bloodstream isolates in hospitalized patients at the University of Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia. A retrospective analysis was conducted over a 1-year period from January to December 2004 by reviewing laboratory reports of patients from the UMMC. The clinical significance of the isolates was not analyzed. Coagulase-negative staphylococci were the most common organisms isolated, accounting for 33.0% of the total blood culture isolates, followed by Staphylococcus aureus (10.4%) and Escherichia coli (9.7%). The incidence of methicillin-resistant S. aureus, and extended-spectrum beta-lactamase-producing E. coli and Klebsiella spp. bacteremia was low (2.3% and 1.8% of total isolates, respectively). Non-albicans Candida were the most common fungal isolates. Conclusions: The high number of coagulase-negative staphylococci should motivate clinicians and microbiologists to re-examine blood culture techniques in our institution. We recommend that further studies be carried out to establish the true significance of this organism among blood culture isolates

Rapid Prototyping of EPS Pattern for Complicated Casting

In Rapid Prototyping (RP) process the 3D object is approximated into several 2D slices. All these slices are of a uniform thickness hence called uniform slicing of zeroth order approximation. Such a system always suffers with the staircase defects. Very thin slices have to be used to minimize these defects, which increase the production time. In this work, a RP system called Segmented Object Manufacturing (SOM) is used to produce the Expanded Polystyrene (EPS) pattern, which uses adaptive slicing with higher order approximation. This system uses the concept of visible slicing in which a complicated object is produced by converting it into the accessible (visible) segments. This is a hybrid system for producing EPS patterns which utilizes the advantages from subtractive and additive processes. These EPS patterns found their application in Evaporative Pattern Casting (EPC). EPS bracket is produced by SOM machine to prove the capability of the system.Mechanical Engineerin

Tsukamurella tyrosinosolvens intravascular catheter-related bacteremia in a haematology patient: a case report

Tsukamurella spp. are a rare but important cause of intravascular catheter-related bacteremia in immunocompromised patients. The organism is an aerobic, Gram-positive, weakly acid-fast bacillus that is difficult to differentiate using standard laboratory methods from other aerobic actinomycetales such as Nocardia spp., Rhododoccus spp., Gordonia spp., and the rapid growing Mycobacterium spp. We report a case of Tsukamurella tyrosinosolvens catheter-related bacteremia in a 51-year-old haematology patient who responded to treatment with imipenem and subsequent line removal. 16srRNA sequencing allowed for the prompt identification of this organism

5-Axis Slicing Methods for Additive Manufacturing Process

In metallic Additive Manufacturing (AM) processes such as Hybrid Layered Manufacturing (HLM), it is difficult to remove the support material used for realizing the overhanging/undercut features. Multi-axis kinematics can be used to eliminate the requirement of the support mechanism. In this work, two slicing methods have been proposed which utilize the benefits of multi-axis kinematics to eliminate the support mechanism. In the first method, planar slicing is used and the overhanging/undercut features are realized while keeping the growth of the component in the conventional Z-direction. In the second method, non-planar slicing is used, and the growth of the component need not necessarily be in the Z-direction; it can also be conformal to the selected feature of the component. Both these methods are explained through a case study of manufacturing an impeller by the HLM process.Mechanical Engineerin