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 

Recently, renewable distributed generation (DG) systems have emerged to improve the power system security and reliability while reducing the environmental incompatibility of fossil fuel power plants. DG could operate either as a standalone and/or as a grid‐connected power system. The interfacing circuits of DG and their controls have to comply with utility quality regulations and afford a seamless transition from online to offline and vice versa. This article advises a simple and robust control scheme for a modular multilevel converter (MMC) that interfaces with a photovoltaic (PV) generator. The proposed control method ensures high‐quality output voltage/current waveform in online and/or offline operating modes. Moreover, the proposed control provides a seamless and swift transition from standalone to grid‐connected and vice versa. The exhibited control scheme is simulated with MATLAB/Simulink. Real‐time …

This paper presents a new approach of energy management for a fuel cell electric vehicle traction system. This system includes a supercapacitor, a traction battery of valve-regulated sealed lead–acid type, a high-performance permanent magnet traction system, and a power electronics converter. Special attention was placed on the coordination for managing the flow of energy from several sources to treat the concerns of prolonged electric vehicle mileage and battery lifetime for drivetrains of electric vehicles. Connection to a supercapacitor in parallel with the electric vehicle’s battery affects electric vehicle battery lifetime and its range. The paper used a study case of an all-electric train, but the used methods can be applied on hybrid or electric train cases. Fuzzy logic control and proportional integral control methods were used to control the electric vehicle system. The results of these two control methods were examined and compared. The simulation results were compared between the proposed electric vehicle system and the traditional system to show the effectiveness of the proposed method. Comparison of waveforms was made with and without the supercapacitor. The proposed optimized energy management strategy could improve the overall performance of the hybrid system and reduce the power consumption.

Recently published CMOS optical receivers consist of a limited-bandwidth first-stage transimpedance amplifier (TIA) followed by an equalizer. Limiting the TIA’s bandwidth improves the gain and reduces the noise but introduces a significant inter-symbol interference (ISI) that is dealt with by the subsequent equalizer. Continuous-time linear equalizer (CTLE) is a commonly used equalizer in both electrical and optical links. However, recent research reported different findings about CTLE-based optical receivers. Some research papers concluded that CTLEs boost high-frequency noise compared to a full-bandwidth design. Other publications reported that high-frequency noise remains unaffected while white noise is significantly reduced. This work aims to solve this discrepancy by presenting an accurate analysis for CTLE-based optical receivers considering noise, gain, and jitter. We show that the noise performance depends on the pole/zero locations of the limited-bandwidth (LBW)-TIA and the follow-on equalizer. A properly designed CTLE-based receiver achieves a 2.5× higher gain and a 1.74× better noise than the full-bandwidth design. The CTLE is also compared to the well-known decision feedback equalizer (DFE). The noise performance of the CTLE-based receiver lies between that of finite and infinite impulse response DFE-based receivers but achieves better gain than both architectures.