Papers by Dr. Eng. Medhat youssef
Fossil-fuel pollutants being pumped from internal combustion engine vehicles have a major threat ... more Fossil-fuel pollutants being pumped from internal combustion engine vehicles have a major threat to our climate and our health. Electric vehicles have been proposed as alternatives to conventional vehicles and are considered as one of the pillar of eco-friendly solutions to overcome the problem of global pollution and radiations due to greenhouse gases. Generally fuel cells are low-voltage high-current sources and their output voltages are sensitive to changes in the loads, therefore integrating them with the high voltage of the DC-link of electric vehicles’ traction drives represents a major challenge for vehicle designers. Boost DC/DC converters are commonly used to interface the elements in the electric power-train, hence the objective of this paper is to design an appropriate boost DC/DC converter structure to manage the energy transfer from the fuel cell stack to the DC-bus based on high efficiency range. A multi-phase interleaved boost DC/DC converter structure is proposed, wh...
The Egyptian Journal of Hospital Medicine, 2021
Background: Polytrauma is a leading cause of death globally and usually involving young victims. ... more Background: Polytrauma is a leading cause of death globally and usually involving young victims. Takotsubo cardiomyopathy (TCM) is a serious clinical presentation of myocardial dysfunction characterized by acute, transient, and reversible heart failure syndrome owing to regional wall abnormalities of the ventricular myocardium associated with ECG changes and rising of myocardial biomarkers in the absence of cardiac condition causing the temporary ventricular dysfunction. Objective: To detect the prevalence of stress cardiomyopathy among polytrauma patients attending to Emergency Hospital Mansoura University. Patients and methods: The current study was a cross sectional study conducted on 500 patients who attended to Emergency Department, Emergency Hospital Mansoura University, suffering from polytrauma within the period from August 2019 to August 2020. Results: Prevalence of cardiomyopathy among the studied trauma patients was 4.4%. Mode of trauma (either blunt or penetrating) had n...
The Lancet, 2021
Background 80% of individuals with cancer will require a surgical procedure, yet little comparati... more Background 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494.
World Smart materials such as piezoelectric actuators possess useful properties especially in the... more World Smart materials such as piezoelectric actuators possess useful properties especially in the field of micropositioning. Tracking control accuracy of these systems is limited due to its inherent hysteresis nonlinearity. Designing a precise tracking controller for a piezoelectric actuator with hysteresis nonlinearity is our purpose in this paper. A Bouc-Wen model is used to describe the hysteresis behavior of the actuator. Multi-parameter-optimization techniques are used twice in this paper; first for obtaining a linear model equivalent to the overall nonlinear actuator model, and second for tuning the gains of the PID controller for suppressing the tracking errors and hence getting precision tracking. Several advantages are gained on solving parameter optimization problems using computers; neither reliance on intuition nor experience in control is required, in addition to producing a satisfactory system response with optimal use of effort and time, high convergence speed, high approximation accuracy, high efficiency, and suitability for many kinds of goal functions. Simulation results performed on the nonlinear system verify the efficiency of the proposed method.
Engineering and Applied Sciences
Projects delivering on time and budget is still complex. This study presents actual project perfo... more Projects delivering on time and budget is still complex. This study presents actual project performance comparisons of the Design-Bid-Build "DBB" and Design-Build "DB" systems into Libyan projects. By analyzing 124 projects delivered by two methods and two types of companies (local and foreign) to provide objective comparison of cost and schedule performance. The results show that average DB cost was about 1.45 times larger than DBB. The project achieved by local and foreign companies, average cost overrun for DBB was 34%, and 26% respectively, Whilst only 10% and 0% for DB for local and foreign companies. The average time extension by local and foreign companies for DBB was 39.8%, and 43%, whilst only 32% and 0% for DB for local and foreign companies. DB projects executed by foreign company had little change order than DBB. This paper compares two project delivery systems, namely Design-Bid-Build and Design-Build, as well as two types of construction companies, local and foreign. Data for 124 projects were collected from Libyan Audit Bureau. In terms of the construction time and cost, the paper concludes that the foreign companies did a better job than the local companies. Also, provides quantitative data to support the delivery system selection with understanding its performance criteria.
IOP Conference Series: Materials Science and Engineering
The use of the Fly-by-Wire (FBW) systems for flight control of aeronautical vehicles has increase... more The use of the Fly-by-Wire (FBW) systems for flight control of aeronautical vehicles has increased steadily in the recent years. Such systems use electro-hydraulic servo-actuators to position the manoeuvring surfaces of airplanes or movable thrust vector controls of space vehicles. The marriage between electronics and hydraulic power systems has led to many powerful and precise control systems, saving much energy and money. This paper deals with the motion control of aircraft integrated electro-hydraulic servo-actuator (ISA) via development of a detailed nonlinear mathematical model and a computer simulation program using MATLAB/SIMULINK package. The ISA mainly consists of two separate active hydraulic power systems, used to supply the ISA with the required power. The studied ISA incorporates two electro-hydraulic servo-valves, a twin-symmetrical-hydraulic actuating cylinder, and a smart design of built in directional control valves with a feedback system. The output linear motion of the actuating cylinder of the ISA is presented and controlled by obtaining the transient response of the ISA. A classical PID controller is designed and tuned by Zeigler-Nichols method according to the Integral Square Error (ISE) criteria to minimize the difference between the obtained system output feedback and the desired set input by adjusting the system control parameters. The system stability and precision requirements are insured by applying the tuned PID controller.
Journal Européen des Systèmes Automatisés
The Fly-By-Wire (FBW) system is a computer-based flight control system that replaces the mechanic... more The Fly-By-Wire (FBW) system is a computer-based flight control system that replaces the mechanical link between the pilot's cockpit controls and the moving surfaces by much lighter electrical wires. This concept is applied in the electro-hydraulic servo systems. In the present work, a detailed non-linear mathematical model of an aircraft integrated servo actuator (ISA) is developed and a computer simulation program is built using MATLAB / SIMULINK package. The ISA mainly consists of two separate active hydraulic power systems, used to supply the ISA with the required power. The studied ISA incorporates two electro-hydraulic servo-valves, a twin-symmetrical-hydraulic actuating cylinder, and a smart design of built-in directional control valves with a feedback system. The output linear motion of the actuating cylinder of the ISA is presented and its transient response is analyzed. A classical PID and modified PI-D controllers are designed and tuned by Zeigler-Nichols method according to the Integral Square Error (ISE) criteria to minimize the difference between the obtained system output feedback and the desired set input by adjusting the system control parameters. The comparative study between the two types of controllers show that the modified PI-D controller has better response than basic one and slower in the presence of disturbance.
The International Conference on Applied Mechanics and Mechanical Engineering
Electro-hydraulic system technology is employed in many modern control systems including aircraft... more Electro-hydraulic system technology is employed in many modern control systems including aircrafts and missile flight control systems. These systems used to position the control surfaces of the flying vehicles with high controllability and accurate action. Pilot or autopilot commands are translated into electrical position commands to the electro-hydraulic control system (EHCS). This study is based upon the development of a detailed nonlinear mathematical model of the EHCS and a computer simulation program using MATLAB/SIMULINK package. The EHCS mainly consists of two systems; main and secondary with two separate active hydraulic power supply systems, used to supply the EHCS with the required power. The studied EHCS incorporates two electro-hydraulic servo-valves and a smart design of built-in direct operated directional control valves, controlled by electrical solenoids. The EHCS is designed with smart capability to override the possible problems of failure in the hydraulic power supply systems or in the servo-valves. The transient response is obtained by the simulation program using the solver of ode23s (stiff/Mod. Rosenbrock) method. A comparison between the dynamic responses of the EHCS is presented in different modes of failure. The simulation results show that this EHCS is capable to provide a continued safe flight even when experiencing a certain component failure or a combination of failures.
General Authority for Educational Buildings (GAEB) in Egypt is responsible for new construction a... more General Authority for Educational Buildings (GAEB) in Egypt is responsible for new construction and maintenance of the educational building [1]. According to the Sixth FiveYears Plan in Egypt, the program of educational structures includes new construction of about 2915 schools, with 39.8 thousand classes. Also, maintenance works for buildings about 1250 schools. These works needs a high budget but the available budget is less than the required budget. Therefore, GAEB should apply optimization techniqes to save cost and optimize the benefit from the avaliable budget with the same quality level or more. This paper aims to apply value engineering technique on educational building to maximuize the utiltization of the available constructuion and maintenace budget. In this paper value engineering technique, is applied on a model of primary school. The paper suggested that GAEB should construct a value engineering department included in its organization structure. Finally it draws overall...
Uploads
Papers by Dr. Eng. Medhat youssef