Morphing Based Approach for Process Planning for Fabrication of Geometries and the Control of Material Composition

The inherent limitation of most of the solid freeform fabrication is the deposition in form of layers. Artificial imposition of the process for the desired geometric morphology and the functional gradience of material limits the accuracy of the workpiece. Mathematical morphing of geometry and the material gradience allows a smooth variation across the part geometry and the material composition of the part. The paper describes a framework for process planning and implementation of fabrication of geometries and control of the material composition. Simulation results for the suggested approach are described in the paper.Mechanical Engineerin

An Investigation of Gas-Powder Flow in Laser-Based Direct Metal Deposition

Laser-Based Direct Metal Deposition (LBDMD) is a blown-powder laser deposition process which can produce fully-dense and metallurgicaly sound parts by a layered manufacturing method. Since a deposition head equipped with discontinuous radially symmetric nozzles has the potential to be tilted without influence of the gravity on the powder stream shape, it can be used for multi-axis deposition. The shape of the gas-powder stream with respect to the shape of laser beam and the size of the molten pool, have a large influence on the size and shape of the buildup. They determine the geometrical accuracy and the surface quality of the buildup. This paper examines gas-powder flow from radially symmetric nozzles using computational fluid dynamics method. For verification purpose the powder flow was investigated by a visualization method and powder concentration distribution was analyzed using image processing technique. The obtained results are in good agreement with numerical model.Mechanical Engineerin

Modeling and Verification of Error Propagation in Integrated Additive/Subtractive Multi-Directional Direct Manufacturing

Integrated additive-subtractive manufacturing, when applied in the framework of SolidFreeform-Fabrication (SFF) allows the fabrication of functional parts on single platform, directly from its computer model. Reduction in process complexity and total processing steps is ensured by multi-directional material deposition and machining. However, due to shift in the datum location in reorientation steps and sequential addition of material in the form of layers, the CAD process intent is not exactly replicated. This leads to inclusion of dimensional errors. Machining in order to eliminate the errors as frequent as layer deposition is highly expensive and can be avoided by estimation of errors and varying process parameters, and/or performing machining after a set of layers are deposited. This paper proposes a state space model for modeling the error propagation due to linear as well as angular variation in the datum. The model is based on identification of possible sources of error, mechanism of error inclusion and influence of process parameters. An experiment performed to determine parameters of error modeling has been reported.Mechanical Engineerin

Mechanism for Determination of G-factors for Solid Freeform Fabrication Techniques Based on Large Heat Input

A major class of Solid Freeform Fabrication (SFF) methods for metal deposition are based on large heat input. The geometry and microstructural properties of the deposition depend primarily on the heat input and the subsequent distribution at the substrate. On one hand the insufficient heat may lead to the inadequate melting of the metal, on the other hand overheating and heat accumulation leads to the overmelting, resulting in the deformation of the build up geometry. The heat distribution is governed by the available heat sink . For a better control of the process, the estimation of heat sinks and the subsequent control of the energy input allows a better control of the process. A parameter G-factor that estimates the heat sink based on the local geometry of a part has been introduced. The estimation of G-factor is based on the simulation and the experimental results. Also a mechanism to determine the G-factor for various substrate geometries has been introduced.Mechanical Engineerin

Thermo-structural Finite Element Analysis of Direct Laser Metal Deposited Thin-Walled Structures

Multilayer direct laser metal deposition is a fabrication process in which the parts are fabricated by creating a molten pool into which particles are injected. During fabrication, a complex thermal history is experienced in different regions of the build, depending on the process parameters and part geometry. The thermal history induces residual stress accumulation in the buildup, which is the main cause of cracking during the fabrication. The management of residual stress and the resulting distortion is a critical factor for the success of the process. A thermostructural finite element model (FEM) of the process is developed, and the analysis reveals different patterns of residual stress in the thin-walled structures depending on the deposition strategy and the geometry of the structures. The residual stress patterns obtained from finite element analysis (FEA) are in good agreement with the experimental results.Mechanical Engineerin

Process Planning for Solid Freeform Fabrication Based on Laser-Additive Multi-axis Deposition

This paper describes a new approach for rapid prototyping based on volumetric skeletonization. Contrary to most of the popular techniques for Solid Freeform Fabrication (SSF) based on 2-1/2 -axis layering as planar slices, this approach suggests the growth of the component along all three coordinate axes. While this approach offers many advantages in terms of the elimination of the support structures for the reduction of the staircase effects and the elimination of various post processes for the functional parts, this approach also offers challenges towards process planning. For various complicated shapes it may not be possible to generate the required shape using this approach; however, a hybrid approach which also incorporates the deposition by layers, may offer an optimum solution. Preliminary results are based on the successful laser-based additive deposition along multiple g-vectors. The material properties and the problems of possible porosities are still to be investigated. Advantages, process planning, applications, experimental results, and the challenges of this new method are the subject of this paper.This work was financially supported by THECB (Texas Higher Education Coordinating Board) Grants 003613-0022-1999 and 003613-0016-2001, NSF (National Science Foundation) Grants DMI-9732848 and DMI-9809198 and by the US Department of Education Grant P200A80806-98.Mechanical Engineerin

Role of Process Alignment and End User Participation in Successful Implementation of E-Government Programs: Perspective of Different Stakeholders

In recent years, a number of developing countries have launched e-government programs, and several development agencies and governments have identified e-government implementation as a key policy priority. Driven by the success of a few projects in improving delivery of services to citizens and businesses, an increasing number of governments are making ICT investments in the public sector. Alignment of departmental processes in government and active participation of employee of government departments as well of participation and cooperation of government department’s users play vital role of success in such programs. Therefore, the major objective of the paper is to understand the role of process alignment and end user participation in success of e-government programs from the important stakeholders perspective; leaders, government departments as users, nodal IT agencies, and IT vendor organization. The research findings are based on survey carried out with 152 stakeholders in all categories through a questionnaire targeted in northern states in India

Anaesthetic management of emergency exploratory laparotomy for ruptured ectopic pregnancy in a patient with Ebstein’s anomaly and Wolff-Parkinson-White syndrome: a challenge for the anaesthesiologists

Ebstein's anomaly (incidence 1:110,000) is characterized by the downward displacement and elongation of the tricuspid valve with poorly contractile right ventricle, an enlarged right atrium along with tricuspid regurgitation. It has shown particular association with Wolf-Parkinson-White syndrome (up to 20 % of patients). Wolff-Parkinson-White syndrome (WPW syndrome) is a rare cardiac anomaly characterised by aberrant conduction pathway between atria and ventricles. Here we describe the successful management of a patient with Ebstein’s anomaly and co-existing WPW syndrome, who presented in our institute with ruptured ectopic pregnancy and was posted for emergency exploratory laparotomy. The anaesthetic management of these patients is very challenging as they can develop life threatening tachyarrthmias like atrial fibrillation (AF) and paraoxysmal supraventricular tachycardia (PSVT)

Presentation and Management of Soft-Tissue Foreign Bodies in a Teaching Hospital of Western Nepal

Introduction: Accidental penetrating injuries with foreign bodies are a common presentation in hospital's emergency rooms. If missed, these bodies can remain dormant or result in a wide range of complications. This study evaluated the characteristics of patients, presentation and management who suffered foreign body embedded in soft tissue at a teaching hospital of Western Nepal.   Methods: The study was conducted at Department of Orthopaedics, Lumbini Medical College Teaching Hospital from September 2013 to August 2015. All cases confirmed to have a foreign body in soft tissue were enrolled. Surgical exploration with removal of foreign body was carried in operating room under tourniquet control. The patient demographics, cause of injury, nature of foreign body, occupation of the patient, diagnostic yield of radioimaging, procedures undertaken for retrieval of foreign body, and complications were  recorded. All patients were followed-up up to five months.   Results: Total 28 patients, nine (32.1%) males and 19 females (67.9%) were observed. The mean age was 35.6 yr (SD=11.1). Housewives (n=14, 50%) were the common sufferers. Most of our patients (n=17, 60.7%) presented two weeks after injury. Accidental prick while cutting grass or tree was the common mode (n=13, 46.3%) of injury and among foreign bodies, wooden or vegetative were the commonest (n=19, 67.9%) observed. Among the extremities, hand (n=10, 35.7%) and foot (n=5, 17.9%) were commonly affected. All patients had successful surgical exploration and retrieval of the foreign bodies under anesthesia and tourniquet control in operating room. Image intensifier was employed in seven cases to locate the foreign bodies per-operatively. Wound infection developed in 14.2% (n=4) of patients, all of whom were managed successfully with oral antibiotics. None of the patients required re-hospitalization. All patients were fine at final five months follow up.   Conclusion: Managing foreign body embedded in the soft tissue are challenging. Surgical exploration under tourniquet control suffice a definitive management. At times, image intensifier is required to locate the foreign body

Offshoring ERP Implementations: Critical Success Factors in Swiss Perspective

Enterprise Resource Planning (ERP) applications are changing the way businesses are run. IT Offshoring is changing the way IT Organizations are run. However, both ERP implementations and IT offshoring are fraught with risks. When both ERP implementation and IT offshoring happen together, the risks get even more pronounced. The paper presents the critical susses factors of offshoring ERP implementation which are common in ERP as well as in offshoring case. The study is carried out with the sample interviews conducted in Switzerland. The findings revels that eight factor are critical while considering offshoring ERP implementation, namely customer interaction skills, business process skills, ERP package skills, scalability, language, project management, choice of work to be offshored, personnel split between onsite/offshore are. We used semi-structured open ended interviews with interpretive analysis for identifying the factors