Design and Analysis of an Ergonomic-Automated Adjustable Drafting Table
Authors :
Abstract : Most of the students in engineering departments, especially architecture department, spend a lot of time while working on the drafting tables. As a result, they suffer from discomfort, back and neck pain because of the fixed dimension of the tables, which make it incompatible with their body dimensions. The present study is aimed to design an ergonomic-automated adjustable drafting table based on the anthropometric data of a randomly sample of 60 engineering students; 30 males and 30 females from engineering’s college in Applied Science Private University, Jordan. The recommended drafting table’s dimensions were the following: adjustable table height is 67 ± 8 cm, adjustable table width is 152 ± 15 cm, table depth is 84 cm and adjustable desktop angle is 0 - 45 ºand. Then an automated drafting table with three flexible joints was designed, constructed and operated based on mechanical design of power screws and electrical design circuits. A survey was conducted to test and validate the proposed drafting table by using a six-question questionnaire on a sample of 40 engineering students. Hypothesis testing, one sample T- test was used to analyze the data by using Minitab 16 statistical software. As a result, students prefer the proposed design which has adjustable height, width and desk top inclination with automated mechanism more than the current fixed one. So the musculoskeletal disorder in the affected parts of the body will be decreased.
Keywords : anthropometry, automation, Ergonomics,drafting table design
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Technical and Economic Viability Assessment of Different Photovoltaic Grid-Connected Systems in Jordan
Authors :
Abstract : In this work, the technical and economical evaluation of the application of different Photovoltaic (PV) on grid systems was studied based on experimental results and theoretical models. Six types of 20 kWp PV grid-connected systems working at Applied Science Private University, Jordan were involved in study. The Six types of different PV systems studied were: Poly-Crystalline South directed (Poly S), Mono-Crystalline South directed (Mono S), Mono-Crystalline East West directed (Mono EW), Poly-Crystalline East West directed (Poly EW), Thin-Film directed to the south, and a Concentrated PV type with automatic two axes tracking (Con Tracker). For the 20-kWp grid connected systems, the yearly production, the yearly savings, the initial investment costs and the Operating & Maintenance (O&M) costs were estimated, evaluated and compared to get the most beneficial investments by using different economical methods. Con Tracker system presented the most feasible system with higher Net Present Value (NPV) (71733.06 JD), Internal Rate of Return (IRR) (45%), and short Payback Period (PBP) (3 years) than those values of Thin-Film with NPV (42638.15 JD), IRR (37%) and PBP (3 years), Poly S with NPV (44887.23 JD), IRR (34%) and PBP (3 years), Mono S with NPV (48267.89 JD), IRR (33%) and PBP (3 years), Mono EW with NPV (40998.52 JD), IRR (29%) and PBP (4 years), finally Poly EW with NPV (35793.14), IRR (28%) and PBP (4 years).
Keywords : Technical assessment
,Economic assessment,
Photovoltaic systems
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Semi-Spherical Solar Oven with Automated Programmed Single Axis Sun Following System
Authors :
Abstract : n this work, a semi-spherical solar oven with auto programmed single-axis sun following system is laid out, built and operated to keep the solar rays vertical to the face of the semi-spherical oven. This system uses the programming open loop method of control. Reflecting mirrors were used to concentrate the sunlight into the focal point in the pot for cooking food.
The system has experimented under Jordanian climatic conditions. The experimentation results in typical spring days from 9:30 AM to 2:30 PM show that this system can raise the inside temperature of the pot with a water volume of 2.5 litres from 26 C⁰ to 97 C⁰ during 30 minutes. This type of solar oven was used for the preparation of different meals as well as heating water.
Keywords : semi-spherical solar oven, single-axis sun following system, programming control
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