Innovative Foundry Technology and Material Using Fused Deposition Modeling and Polylactic Acid Material in Sand Casing

In sand casting, Fused Deposition Modeling (FDM) printing by using Poly Lactic Acid (PLA) filament is one of the innovative foundry technologies being adopted to substitute traditional pattern making. Several literatures have reported the influence of process parameters such as raster angle and print speed on some mechanical properties of FDM-printed, PLA-prototypes used in other applications. This study investigated the effects of interior fill, top solid layer, and layer height on the compressive strength of rapid patterns for sand casting application. Different values of the process parameters were used to print the pre-defined samples of the PLA-specimens and a compression test was performed on them. The coupled effects of the process parameters on compressive strength were investigated and the optimum values were determined. Interior fill of 36%, layer height of 0.21 mm and top solid layer of 4 were found to produce a FDM-printed, PLApattern that sustained a compaction pressure of 0.61 MPa. A simulation analysis with ANSYS® to compare failure modes of both experiment and model shows a similarity of buckling failure that occurred close to the base of each specimen

Laminar Forced Convective Heat Transfer and Fluid Flow in a Finned Cylindrical Annulus

The purpose of this paper is to numerically investigate the effects of some geometric parameters and flow variables on heat transfer augmentation in annuli with equi-spaced internal longitudinal fins along the external walls. A fully developed flow and a constant thermal boundary condition of uniform heat flux at the walls of the pipe were assumed. Continuity, momentum and energy transport equations were adopted for the solutions of the problem. A Q-BASIC code was written based on the finite difference scheme generated. Numerical experiments were conducted to ascertain the effects of Reynolds number Re, radius ratio, R.R, Prandtl number Pr, fin height H, and pipe inclination, on the rate of heat transfer and fluid flow. The results obtained show that for 50 ≤ Re ≤ 500, total Nusselt number NuT increases with increase in Re while for Re > 500, there was no significant increase in NuT. Nusselt number, average velocity and bulk temperature of the fluid increase with increasingin the range 0° ≤ ≤ 75° but for the range 75°≤  ≤ 90°  the effect is negligible. For R.R > 0.6, the heat transfer was observed to be almost independent of R; therefore for economic purposes, heat exchangers similar to the configuration studied should be run at a low pumping power. A numerical study was done to validate the program by test running it for the finless annuli for similar boundary conditions; the results obtained in the present work show the same trend as that of Kakac and Yucel

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

Production-Distribution and Transportation Planning in Flexible Multi-Echelon Supply Chains

We develop a model for production-distribution and transportation planning in flexible multi echelon supply chains. When solved, the model produces the optimal quantity of each product to be produced at each plant in each period, transported from each plant to each distribution centre (DC) in each period, shipped from each DC to each retailer in each period, transported directly from some plants to some retailers in each period, kept in inventory at each plant and at each DC in each period, and subcontracted at each DC in each period. It also produces the optimal amount of extensions needed at each DC. The model provides two ways for shipping finished goods to retailers, namely: shipments from plants to retailers via the DCs, and direct shipment from plants to retailers. Three sets of numerical examples were given to test and illustrate the model. The first set of numerical examples show that the model works very well and that it produces good results. The second set show that using a single model to optimize all SC key components simultaneously can greatly enhance supply-chain efficiency. The third set of examples involve small-, medium-, and large-scale problems whose numbers of variables and constraints range from 2791 to 59591 and 1121 to 11306 respectively. The results of the solutions to the problems show that our model will produce good results if applied to any real world SC problem of any size – small, medium, or very large. The results also show that the CPLEX optimizer will be useful for solving the model if applied to solve real world large-scale SC problems

Scheduling of projects under the condition of inflation

This paper (see also [4]) develops a linear programming (LP) model for an efficient scheduling and management of big projects. The model has an inflation factor as one of its major features and incorporates an extensive modification of existing project scheduling models. The paper includes numerical examples to demonstrate the usefulness of the model and the consequences of excluding inflation factor during project cost-estimation, planning and scheduling in an environment of high inflation. By transforming the variables of the LP model, a new model with fewer constraints is obtained, thereby reducing the amount of effort required to find an optimal solution.cost model project management LP inflation

Supplier Selection: Impact of Multi-Tier Supplier Visibility

This paper addresses the practice of maintaining lower-tier supplier visibility (LTSV) whereby an Original Equipment Manufacturer (OEM) may select its first-tier suppliers by taking into account the performance and capabilities of their lower-tier suppliers. The paper divides the participating companies into LTSV and non-LTSV firms, depending on whether they maintain lower-tier visibility on their suppliers or not, respectively. Then, with respect to four types of suppliers (strategic, custom, collaborative, and commodity), the paper examines the importance of several evaluation criteria for LTSV and non-LTSV firms. Three research issues were addressed. The first examines the decreasing order of importance of the evaluation criteria for LTSV firms and non-LTSV firms. The second examines whether LTSV firms have significantly different expectations of some of the evaluation criteria compared to non-LTSV firms. The third explores whether the significant differential expectations, if they exist, are maintained for a given evaluation criterion across all types of supplier segments. The findings constitute recommendations for good practice especially for companies seeking multi-tier supplier visibility

Definition, Assessment, Health Consequences and Management of Equine Obesity: A Review

Obesity is a state of abnormal or excessive fat accumulation. Obesity in horses increases the risk of developing a variety of health issues such as: insulin dysregulation (ID), reduced athleticism, colic, abnormal reproductive performance, laminitis, endotoxaemia, diabetes mellitus, hyperlipaemia, impaired thermoregulation, pituitary pars intermedia dysfunction, and osteochondrosis. Obesity is a significant health and welfare issue in horses that may go unreported or unnoticed due to a caregiver’s (owner) neglect. Weight gain occurs when a horse’s energy consumption exceeds his or her physical energy needs. Obesity is best assessed via necropsy or upon in vivo assessment with deuterium oxide administration, although this is not feasible in a clinical environment. In practice, obesity is assessed by: body condition scoring, cresty neck scoring, ultrasono graphic assessment, morphometric measurements, or biochemical indicators in the blood. Dietary and exercise programs are the primary means of controlling equine obesity. Pharmacologic assistance (levothyroxine sodium and metformin hydrochloride), being a secondary approach, may be effective in some cases. Management involves a long-term plan that requires the horse’s caregiver’s effort and discipline, as well as the support and supervision of their veterinarian. This paper outlines the assessment, health consequences, and management of equine obesity