Sharif Digital Repository

Properly adjusting the trim angle during the craft speed up, plays an important role in easily passing through the resistance hump and to reach final speed in minimum possible time. Present study tries to reply to this question that how the angles applied to a trimmable drive system and trim tab of the planing craft should be changed during speed up from rest, to craft reach a final speed in minimum time. This is a time-optimal control problem with the drive and trim tab angles as its control variables. To solve this problem a 3-DOF dynamic model is developed here rely on empirical data and relations. For the propulsion system operation of propeller, drive and engine altogether are taken... 

Drug administration using infusion pumps can find application in treating patients with arrhythmias. These pumps can obviate the need to use drugs several times a day and automatically adapt the dosage to patient situation. Considering the importance of administration of right dosage, a perfect-controlled pump is needed to approach this goal. This paper focuses on controlling Atrial fibrillation (AF) arrhythmia. The abnormal heart rhythm that affects RR interval sequence and there have been some attempts to model these effects. One of these models is proposed by Cohen and colleges. Searching through the variables of this model, selecting the potential control variable (the one that its... 

Austempered ductile iron (ADI) is one of the most widely used types of ductile iron produced by austempering heat treatment. ADI heavy section parts are employed in different industries owing to their unique mechanical properties. Cooling rate in thick parts is significantly low, so heavy section ductile iron parts should have an adequate austemperability for preventing pearlite formation in the middle of the casting. In order to achieve the proper austemperability and fully ausferritic structure, alloying elements like nickel are added to the melt. The objective of this work is to study the role of austempering parameters on nickel alloyed ADI specimens fabricated from 75-mm-thick Y-block.... 

Reducing the renewable energy costs is necessary for the competition with the fossil energies and control strategies have great impact on the efficiency of wind machines. In the wind turbine industry, a practical approach is to maximize the energy capture of a wind machine by optimizing the power coefficient in the under-rated situations. In this paper, with the main objective of maximizing the energy capture in the second region, four different control strategies are compared in the presence of uncertainties. The proposed control methods are compared based on their power capture and robustness against probable uncertainties in the structural and environmental parameters. A two-mass... 

This paper presents a general integrated procedure of fabricating a Hybrid Electric Motorcycle (HEM). Firstly, a simple model designed and simulated using ADVISOR2002 and the proposed model is exported to MATLAB/SIMULINK. Secondly, the controller schematic and its optimized control strategy are described. In addition, the ratings of the components including the batteries, electric motor, and internal combustion engine (ICE) are calculated based on the design. A 125 cc ICE motorcycle is selected for conversion to HEM. A brushless DC (BLDC) motor assembled in front wheel as accessory propellant. The nominal powers are 8.2 kW at 8500 rpm and 500 W for the ICE and BLDC respectively. The original... 

STUDY DESIGN.: An experimental design to investigate activation patterns of trunk muscles during multidirectional exertions. OBJECTIVES.: To evaluate trunk muscle activation patterns in varying directions and moment magnitudes during an isometric task, and to investigate the effects of angle and level of isometric exertion on the electromyography (EMG) variability of trunk muscles in upright posture. SUMMARY OF BACKGROUND DATA.: Few studies have investigated trunk muscle activation patterns in multidirectional exertions with different moment magnitudes. METHODS.: A total of 12 asymptomatic male subjects were participated in the study. The EMG activity of 10 selected trunk muscles was... 

This paper presents a fuzzy based modified artificial bee colony (MABC) algorithm to solve discrete optimal power flow (OPF) problem that has both discrete and continuous variables considering valve point effects. The OPF problem is formulated as a multi-objective mixed-integer nonlinear problem, where optimal settings of the OPF control variables for simultaneous minimization of total fuel cost of thermal units, total emission, total real power losses, and voltage deviation are obtained. The proposed approach is applied to the OPF problem on IEEE 30-bus and IEEE 118-bus test systems. The performance and operation of the proposed approach is compared with the conventional methods. The... 

Sit to stand (STS) task requires variability of all body segments to achieve the stability of the important control variables (i.e., center of mass (CM) and head positions). In this study, the possible differences in the variability patterns of various body segments were investigated between 11 chronic low back pain (LBP) and 12 control subjects during STS task through two types of variability analyses; first by calculating the variability of seven limb angles, CM and head positions across 15 trials and second by principal component analysis (PCA) of seven limb angles. Participants performed the task at 3 postural difficulty levels: rigid surface, open eyes (RO), rigid surface, close eyes... 

This paper presents the design and part-load operation of a molten carbonate-micro gas turbine (MCFC/MGT) hybrid system (HS), and proposes a multiloop control strategy for the HS. A mathematical model of the system is introduced. Then, the structure of process is changed and the performance of HSs at part-load operation is studied. The novelty includes utilizing some part of the main fuel instead of auxiliary fuel in the combustion stage. The results show that the new configuration has more efficiency (about 63%). In order to keep the operating system within safe limits, variables of the control system are determined. Those controlled variables are as follows: stack temperature, fuel... 

The characteristics of postural sway were assessed in quiet standing under three different postural task conditions in 14 patients with nonspecific chronic low back pain and 12 healthy subjects using linear and nonlinear center of pressure parameters. The linear parameters consisted of area, the mean total velocity, sway amplitude, the SD of velocity, and the phase plane portrait. The nonlinear parameters included the Lyapunov exponent, sample entropy, and the correlation dimension. The results showed that the amount of postural sway was higher in the patients with low back pain compared with the healthy subjects. Assessing the nonlinear parameters of the center of pressure showed a lower... 

Wind turbines are generally controlled for the objectives of the turbine protection and generation of the acceptable power for the utility grid. In this paper, a nonlinear multivariable model of the wind turbine with a DFIG generator is considered. The rotor speed and the d-axis rotor current, as the controlled variables, are controlled via manipulation of the two generator voltages, as the control signals. Two robust control strategies including the sliding mode control and H∞ robust control, designed via μ-synthesis based on DK-iteration algorithm, are presented for switching between various operating modes. Development of an acceptable dynamic model and two innovative control strategies... 

Reducing the renewable energy costs is necessary for the competition with the fossil energies and control strategies have great impact on the efficiency of wind machines. In the wind turbine industry, a practical approach is to maximize the energy capture of a wind machine by optimizing the power coefficient in the under-rated situations. In this paper, with the main objective of maximizing the energy capture in the second region, four different control strategies are compared in the presence of uncertainties. The proposed control methods are compared based on their power capture and robustness against probable uncertainties in the structural and environmental parameters. A two-mass...