Fused Deposition Modelling (FDM) has been becoming a widely used additive layer-by-layer manufacturing process, is used to produce complex geometries in a short period without tooling or human involvement. One of the challenging problems of FDM products is the surface roughness. In this article, a slurry was applied to the surface of FDM Polylactic Acid (PLA) products to enhance the surface roughness. The developed technique lessens the asperities of the surface and makes it softer. The controllable factors are layer thickness, building orientation, and slurry impact angle. Experimentally, a test rig was utilized to investigate the effect of the three factors on surface roughness. Numerically, an Adaptive Neuro-fuzzy Interference System (ANFIS) was developed to map roughness with the contributing factors. The results showed that the effect of slurry gave a good surface quality and the surface roughness …
In this research, we utilize image processing to analyze surfaces acquired from slurry-erosion tests carried out on AISI 5117 steel at various velocities and impact angles of 30 deg and 90 deg. The fractal and wavelet decomposition transform are two analysis tools that are particularly promising in this regard. These can be used to extract metrics that characterize slurry erosion in the same way that erosion rate is characterized. The study found that for a higher velocity of 15 m/s and a 30-deg impact angle, the fractal value was larger, irrespective of magnification. The fractal value is also in a positive linear regression with magnification. The extracted features of wavelet analysis were not distinctive for slurry-erosion behavior. The role of impact velocity in creating erosion damage is related to the variety of erosion mechanisms that are dependent on the particles’ kinetic energy. Microscopic examinations of …
This paper introduces a case study methodology to decrease variability in quality measures and optimise control parameters in a cement-bags company. A lack of supervision is observed in the company which gives a negative impact on quality by increasing the number of defective bags with time without taking any action. The statistical process control (SPC) techniques, process capability measures, and analysis of variance (ANOVA) are used to reduce the high variability in production and the defective bag ratio. Moreover, an approach is developed to find and eliminate the resulted causes of variation in the production process. Multiple linear regression analysis is conducted for each variable characteristic to determine the best working conditions by which the production process improves.
Outpatient chemotherapy clinics (OCCs) are a crucial medical units where cancer is diagnosed, and treatment is provided. However, they face planning and scheduling challenges. In this paper, two problems in OCCs are addressed: how to accurately compute the utilisation of the nurses, and the patient appointment scheduling problem. An agent-based simulation is used to simulate the nurse activities and thus the nurse utilisation is computed. A discrete event simulation model is developed to evaluate the performance of the current patient appointment practice. However, the resulted nurse utilisation could not be accurately computed. Therefore, a hybrid discrete event and agent-based simulation model is developed to simulate the whole system including the nurse activities. Moreover, the proposed simulation model is used to determine the best patient appointment scenario. The results can be used to accurately …
This paper is aimed at improving the reliability and security of radial distribution system supported by wind turbine generators (WTGs) and superconducting magnetic energy storages (SMESs). For reliability indices assessment, the load-oriented indices including energy not supplied (ENS) and average energy not supplied (AENS) as well as the customers-oriented indices including system average interruption duration index (SAIDI), system average interruption frequency index (SAIFI), customer average interruption duration index (CAIDI), and average service unavailability index (ASUI) are evaluated. Network security index (NSI) is also addressed, which refers to the risk level for current flow in the lines prior reaching to extremis. A multi-objective function is composed and formulated in order to simultaneously minimize ENS, SAIFI, SAIDI, ASUI, and NSI as indices which characterize the performance of distribution
Voltage sag represents one of the most significant features of power quality in operation of distribution systems. The voltage sag throughout the distribution system caused by simultaneous start-up of water-pumping motors represents a problem, which negatively affects the power quality of the distribution system. The present research work investigates mitigation of voltage sag in a real Egyptian distribution system during simultaneous start-up of many connected water-pumping motors by using superconducting magnetic energy storage (SMES) unit. This calls for a transient analysis of the real distribution system using MATLAB package in order to follow up the temporal variation of the system voltage-profile during motors' start-up. A fuzzy-logic (FL) control strategy of SMES unit is adopted to compose of cascaded control a six-pulse pulse-width modulation (PWM) voltage source converter (VSC) and two-quadrant DC
