2018-07-21T14:28:47Z
http://jsfm.shahroodut.ac.ir/?_action=export&rf=summon&issue=30
مکانیک سازه ها و شاره ها
2251-9475
2251-9475
1391
2
3
An approximate model for slug flow heat transfer in channels of arbitrary cross section
محمد
کلته
عباس
عباسی
مجید
بهرامی
In this paper, a novel approximate solution to determine the Nusselt number for thermally developed, slug (low-prandtl), laminar, single phase flow in channels of arbitrary cross section is presented. Using the Saint-Venant principle in torsion of beams, it is shown that the thermally developed Nusselt number for low-prandtl flow is only a function of the geometrical parameters of the channel cross section, i.e., area, perimeter and non-dimensional polar moment of inertia. The new proposed model is compared with the existing numerical results for elliptic, rectangular, regular polygonal, flat plate, isosceles triangular, equilateral triangular and circular sector channels. The model predicts the Nusselt number for the above mentioned channels within the about 10% or better with the exception of the circular sector in very small aspect ratios. The new model is expected to be accurate for other singly connected channels and can be used to determine the fully developed turbulent Nusselt number for liquid metal flows. Finally, the proposed model is used to determine the slug flow Nusselt number for unavailable geometries in the literature such as rhombic, circular segment, annular sector channel as well as rectangular channel with semicircular ends.
Nusselt number
Laminar
Slug
Arbitrary Cross Section
Approximate Model
2012
09
22
1
7
http://jsfm.shahroodut.ac.ir/article_69_c8d0a7ec8becc0124411a7260c94801e.pdf
مکانیک سازه ها و شاره ها
2251-9475
2251-9475
1391
2
3
One-Dimensional design of a three-stage axial compressor with Its 3D numerical simulation
محسن
به نیا
مهدی
نیلی احمدآبادی
The purpose of this study is to design a three-stage axial compressor with identical pressure ratio which makes an adequate pressure ratio and efficiency in design point conditions with rotational velocity of 38000rpm and mass flow rate of 3.2kg/s. First of all, considering some restrictions such as Dehaller number more than 0.7 in all sections of the stator and the rotor, and relative Mach number less than 0.8 at the tip of the rotor blade [1], one dimensional design is performed. In this design, blade base diameter is considered the same in all stages, regarding shaft diameter. In order to reduce casing diameter, inlet guide vanes are utilized so that the relative Mach number at the tip of the first stage rotor blade decreases. Therefore, the design of the rotor blades and the stator are based on reaction coefficient of 0.5. According to calculated input and output angles, adequate profile for each section is selected from NACA-Mellor diagrams. The output of the one dimensional design program is calculation of all the geometric parameters including blades input and output angles, blades length and diameter, solidity coefficient, number of blades and installation angle at three different sections of hub, mid and tip in compliance with the constraints. Thus, the three-dimensional shape of the blades is created. To investigate the performance of the designed compressor at design point, an appropriate grid is selected on the three-dimensional geometry of the compressor and the three-dimensional numerical solution is obtained using a full Navier-Stokes program.
Axial compressor
One dimensional design
Numerical simulation
Dehaller
2013
08
26
9
17
http://jsfm.shahroodut.ac.ir/article_152_b996920cc1cf6d46e1e86a8d79eadcf2.pdf
مکانیک سازه ها و شاره ها
2251-9475
2251-9475
1391
2
3
On the natural convective heat transfer from a cold horizontal cylinder over an adiabatic surface
محمد هادی
صداقت
محمود
یعقوبی
محمد جواد
مغربی
A steady two-dimensional laminar free convection heat transfer from a cold horizontal isothermal cylinder located above an adiabatic floor is studied both experimentally and numerically. In the experimental measurements the effects of cylinder distance from horizontal floor to its diameter (L/D) on heat transfer coefficient is studied for Rayleigh numbers of 3×105 and 6×105. Computations are made using OpenFOAM (an open source ) code for wide range of Rayleigh numbers from 104 to 106 and comparisons are made with the corresponding experimental measurements. Flow stream lines and isothermal lines are plotted for different cylinder relative positions. Results indicate that cold plume flows downstream and strikes to the horizontal floor and moves horizontally away from cylinder over the horizontal floor. The finite space between cylinder and floor makes the flow different from those cylinders surrounded by an infinite medium. Results also indicate that variation of average heat transfer coefficient of the cold cylinder is highly affected by L/D. A new correlation for estimation of convection heat transfer for a single horizontal cylinder placed over an adiabatic floor is also developed.
Free Convection
laminar flow
cold horizontal cylinder
adiabatic floor
OpenFOAM
2013
01
14
19
28
http://jsfm.shahroodut.ac.ir/article_93_be16c4dd5fe5fd1d0b095e754aff9c3a.pdf
مکانیک سازه ها و شاره ها
2251-9475
2251-9475
1391
2
3
A rule-based evaluation of ladder logic diagram and timed petri nets for programmable logic controllers
علی اکبر
پویان
زینب
مزینانیان
رضا
شمس
This paper describes an evaluation through a case study by measuring a rule-based approach, which proposed for ladder logic diagrams and Petri nets. In the beginning, programmable logic controllers were widely designed by ladder logic diagrams. When complexity and functionality of manufacturing systems increases, developing their software is becoming more difficult. Thus, Petri nets as a high level specification language were offered. Rule-based approach tends to a unified measurement for both ladder logic diagrams and Petri nets. The proposed approach is performed in three levels and its complexity increases level by level. We have shown that, when the levels are more complex, Petri nets are more tractable and more verifiable. Moreover, it can be concluded that Petri nets are superior to ladder logic diagrams. This feature enhances the verifiability of modeled systems. The proposed approach a net system control model, which can be directly compiled to a executable control code for designing and analysis of complex manufacturing systems.
Ladder logic diagram
Petri net
Timed Petri net
Programmable logic controllers
Manufacturing systems
2013
08
26
29
34
http://jsfm.shahroodut.ac.ir/article_153_a0858c4637634929baa8600cfda5ba11.pdf
مکانیک سازه ها و شاره ها
2251-9475
2251-9475
1391
2
3
Optimal discrete-time control of robot manipulators in repetitive tasks
محمد مهدی
فاتح
مریم
بلوچ زاده
Optimal discrete-time control of linear systems has been presented already. There are some difficulties to design an optimal discrete-time control of robot manipulator since the robot manipulator is highly nonlinear and uncertain. This paper presents a novel robust optimal discrete-time control of electrically driven robot manipulators for performing repetitive tasks. The robot performs repetitive tasks by tracking a periodic trajectory. The proposed controller includes a discrete linear quadratic controller and a time-delay controller. To apply the discrete linear quadratic controller, a novel nominal model is obtained for the robotic system which is discrete, linear, and time-invariant. Then, nonlinearities and uncertainties of the robotic system are compensated by the robust time-delay controller. The proposed control law is verified by stability analysis and its effectiveness is illustrated by simulations. Recently, time-optimal and minimum-norm discrete repetitive control of robot manipulators has been proposed. Compared with it, the proposed control has an advantage of being free from manipulator dynamics, thus it is simpler, more robust, and less computational with smoother control efforts.
Optimal discrete repetitive control
Discrete linear quadratic control
Time-delay control
robot manipulators
2013
01
14
35
44
http://jsfm.shahroodut.ac.ir/article_91_3f810b60565b9471d15a3d64c4dc1e82.pdf
مکانیک سازه ها و شاره ها
2251-9475
2251-9475
1391
2
3
Eliminating chattering phenomenon in sliding mode control of robot manipulators in the joint space using fuzzy logic
محمد
ویسی
محمد رضا
سلطانپور
In industrial robotic manipulator, due to the presence of quite nonlinear dynamic and structural and nonstructural uncertainties, a precise model is not easily obtained. As a result, designing a controller with a suitable function based on system model is a challenging issue. Sliding mode control is a robust control with numerous applications which can overcome the aforementioned uncertainties. However, this control method has several defects such as chattering in input control in implementing stage. In this article, Fuzzy sliding mode control based on TSK method for controlling manipulator position tracking is suggested. This control method not only has advantages of sliding mode but also it has no chattering control effect in implementation process. To exhibit the function of sliding mode control, a case study is implemented on a robot manipulator with two revolute joints. The mathematical proofs and the simulation results reveal the desirable efficiency of Fuzzy sliding mode control.
بازوی ربات
فضای مفصلی
عدم قطعیت
کنترل مدلغزشی فازی
روش TSK
2013
07
26
45
54
http://jsfm.shahroodut.ac.ir/article_154_31799f7df737c7f3d98c2418a0144e52.pdf
مکانیک سازه ها و شاره ها
2251-9475
2251-9475
1391
2
3
Optimal power management of fuel cell hybrid vehicles
امین
حاجی زاده
This paper presents a control strategy developed for optimizing the power flow in a Fuel Cell Hybrid Vehicle structure. This method implements an on-line power management based on the optimal fuzzy controller between dual power sources that consist of a battery bank and a Fuel Cell (FC). The power management strategy in the hybrid control structure is crucial for balancing between efficiency and performance of hybrid systems. For optimization of fuzzy control strategy, the Particle Swarm Optimization (PSO) algorithm has been considered to determine the battery’s state of charge and fuel cell power in maximum efficiency operating point. The fuel cell hybrid vehicle includes battery and fuel cell and its power train system include an Electric Motor (EM) and power electronic converters. Simulation results of hybrid system illustrate improvement in the operation efficiency of the fuel cell hybrid vehicle and the battery’s state of charge (SOC) and fuel cell utilization factor have been maintained at a reasonable level.
fuel cell
Battery
Hybrid Vehicle
fuzzy control
PSO
Optimization
2012
09
22
55
62
http://jsfm.shahroodut.ac.ir/article_68_f98a84ff627d9c555a0147f2c22624e9.pdf
مکانیک سازه ها و شاره ها
2251-9475
2251-9475
1391
2
3
Using neural networks to predict road roughness
سید علی
سلیمانی ایوری
امین
صاحبی
When a vehicle travels on a road, different parts of vehicle vibrate because of road roughness. This paper proposes a method to predict road roughness based on vertical acceleration using neural networks. To this end, first, the suspension system and road roughness are expressed mathematically. Then, the suspension system model will identified using neural networks. The results of this step show that the neural networks model of suspension system will be well. The mean and max errors are 0.0013% and 0.0012, respectively. Finally, the inverse suspension system model is extracted by using neural networks to determine the relationship between road roughness and vibration or displacement. Using this step to predict the road quality. In this step, the mean error is 2.1% and max error is 0.028. Therefore, the results show that the proposed method can be used to identify the suspension system, inverse suspension system and predict the quality of roads.
پیشگویی ناهمواری جاده
شبکه عصبی
سیستم تعلیق
مدلسازی
2013
01
14
63
69
http://jsfm.shahroodut.ac.ir/article_92_79667454bbd33ff5ab5759013512e973.pdf
مکانیک سازه ها و شاره ها
2251-9475
2251-9475
1391
2
3
Optimal intelligent control for glucose regulation
مهدی
سیاهی
علیرضا
الفی
داوود
نظری مریم آبادی
محمدحسن
خوبان
This paper introduces a novel control methodology based on fuzzy controller for a glucose-insulin regulatory system of type I diabetes patient. First, in order to incorporate knowledge about patient treatment, a fuzzy logic controller is employed for regulating the gains of the basis Proportional-Integral (PI) as a self-tuning controller. Then, to overcome the key drawback of fuzzy logic controller, i.e., the lack of systematic methods to define fuzzy rules and fuzzy membership functions, fuzzy PI controller are optimised by Particle Swarm Optimization with Linearly Decreasing Weight (LDW-PSO) algorithm, which is a novel evolutionary computation technique. Simulation results show the effectiveness of the proposed optimal fuzzy PI controller in terms of accuracy and time margin. This paper introduces a novel control methodology based on fuzzy controller for a glucose-insulin regulatory system of type I diabetes patient. First, in order to incorporate knowledge about patient treatment, a fuzzy logic controller is employed for regulating the gains of the basis Proportional-Integral (PI) as a self-tuning controller. Then, to overcome the key drawback of fuzzy logic controller, i.e., the lack of systematic methods to define fuzzy rules and fuzzy membership functions, fuzzy PI controller are optimised by Particle Swarm Optimization with Linearly Decreasing Weight (LDW-PSO) algorithm, which is a novel evolutionary computation technique. Simulation results show the effectiveness of the proposed optimal fuzzy PI controller in terms of accuracy and time margin
Type 1 diabetes
Bergman Model
Fuzzy Logic Control
Particle Swram Optimization
PI Controller
2012
09
22
71
79
http://jsfm.shahroodut.ac.ir/article_67_4083a7eb38a033a09dd000ff3d20097b.pdf