
text
article
2008
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Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
1
2
http://sjme.journals.sharif.edu/article_20477_8ab664300d9ced02f54387b0135a16b4.pdf
SURFACE REACTIONS IN ALUMINUM DUST COMBUSTION AND BURNING TIME
A.
Frdad
Dept. of Mechanical Engineering
Iran University of Science and Technology
author
M.
Bidabadi
Dept. of Mechanical Engineering Iran University of Science and Technology
author
M.
Sedighi
Dept. of Aroospace Engineering Air University
author
S.
Khosravi
Dept. of Mechanical Engineering Iran University of Science and Technology
author
text
article
2008
per
Contrary to popular theories of the past, often in the ignition of aluminum vapor phase (gas reaction gas) would imagine, recent research suggests that some solid phase combustion reaction conditions effective role in advancing the process gas is combustible. To determine the role combustion of metal particles There are many ways. One of these methods of ignition time, and time changes with changing particle diameter, and its sensitivity to the amount of oxygen. experiments showed that the sizes below 50 microns, the role of gas solid reactions stronger than the gas phase reaction is gas.
Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
87
91
http://sjme.journals.sharif.edu/article_5661_366ab80e27b987daa30354a7da704b97.pdf
STATIC BUCKLING OF CIRCULAR CYLINDRICAL PIEZOELECTRIC SHELLS BASED ON HIGHER ORDER THEORIES
M.
Shariyat
Dept. of Mechanical Engineering Khaje Nasir Toosi University
author
A.
Yaghootian
Dept. of Mechanical Engineering Khaje Nasir Toosi University
author
text
article
2008
per
In this paper, static buckling of piewelectric cylin drieal shells is investigated using a higher order the ory. Thus, in contrast to the classieal theory, trans verse shear stresses are also considered . The pro posed fonnulations can be used for both thin and thick shells. Influences of the initial deformat ions, that are assumed to be in the radial direction, are considered in the formulations. Sinee a Hermition element is used in the present analysis, displacement based, as well as stress based, boundary conditions can be applied. Finally, influence of the applied eleetrical potential on the inner and outer surfaces of the piezoelectric cylindrical shell is investigated on the buckling load.
Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
93
100
http://sjme.journals.sharif.edu/article_5662_a3499daccfc323805d71a0d7a6ca49f3.pdf
A NEURAL NETWORK BASED ACCELERATION TECHNIQUE OF GENETIC ALGORITHM CONVERGENCE IN AERODYNAMIC DESIGN OPTIMIZATION
N.
Foladi
Dept . of Aerospace Engineering Amir Kabir University
author
A.
Jahangiriyan
Dept . of Aerospace Engineering Amir Kabir University
author
text
article
2008
per
Wing section optimization is aceomplished using a combined strategy consisting of a genetic algorithm (GA ) and an artificial neural network (A::..r:K) . A real coded genetic algmi.t hm is utilized for an op timum search in design space. The numerical so lution of inviscid flow governing equations is used for evaluation of the design candidates. In order to red uce the number of these
time consuming eval uations required by GA, every M generat ion, all chromosomes fitness are trained to a neural net work. Then, a control based genetic local search is handled by AX':\ as a fitness estimator to find new promising regions in design space. It is demon strated that this approach could save considerable computational time in application fields, such as
aerodynamic design . Results are presented for a constrained optimization of an airfoil at transonic flow conditions. The PARSEC method of airfoil generator and unstructured grid movement tech nique are used in this work. Event ually, optimum airfoil geometry is achieved by about 50% less com putational effort compared with the conventional GA method.
Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
101
107
http://sjme.journals.sharif.edu/article_5663_e1154e10a2dc3568232f344e5eb6e1d3.pdf
NUMERICAL INVESTIGATION OF INLET BAFFLE FEATURES EFFECTS ON THE HYDRAULIC PERFORMANCE OF PRIMARY SETTLING TANKS
A.
Tamayol
Dept. of Mechnical Engineering Sharif University of Technology
author
B.
Firoozabadi
Dept. of Mechnical Engineering Sharif University of Technology
author
text
article
2008
per
Cireulation is created in some parts of the settling tanks . It can increase the mi.x.ing level, deerease the effective settling and ereate short circuiting from in let to outlet. All the abovementioned phenomena act in such a way to deerease the tank's hydraulic ef ficiency, which quantitatively shows how flow within the tank is uniform and ealm . So, the main objee tive of the tank design process is to avoid form ing a circulation zone, which is known ar.;; the dead zone. Prediction of the flow field and size of the recireulation zone is the first step in the design of settling tanks. In this paper, while the FTC (Flow Through Curve) was introdueed, by using the Rl\G k E turbulence model, the effects of inlet position on the hydraulic perfor mance of primary settling tanks were investigated . The ba.ffie presence effeet was also studied. Results show that the R.\.G kt turbulence model ean predict the curvat ure of streamlines correctly. It is also shown that the inlet ba.ffie is not useful for the present easestudy rutd reduces its performance.
Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
109
114
http://sjme.journals.sharif.edu/article_5664_01b9ee82e6b603fe14bd88476f9b08a7.pdf
COSMPARING FULL AND REDUCED METHANE KINETIC MECHANISMS IN NUMERICAL MODELING OF POROUS BURNERS
M.
Khosravy Elhossaini
Dept . of Mechanical Engineerin g, faculty of Engineering Tarbiat Modares University
author
M.
Marefat
Dept . of Mechanical Engineerin g, faculty of Engineering Tarbiat Modares University
author
K.
Mazaheri
Dept . of Mechanical Engineerin g, faculty of Engineering Tarbiat Modares University
author
text
article
2008
per

Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
115
126
http://sjme.journals.sharif.edu/article_5665_ef169c0b6674b65976cc603bbeddfcd7.pdf
AN ANALYTICAL MODEL FOR EXPANSION AND DEPOSITION OF CHARGED SPRAY DROPS
R.
Jahannama
Dept . of Research Affairs, Engineering
esearch Institute inistry of JahadAgriculture
author
text
article
2008
per
An analytical model is developed accounting for the expansion of an electrically charged spray, further to its temporal deposit ion on a target . The model ern ploys the Gauss law to determine the electric field that arises from the charged spray, bounded by an earthed control surface. This, in turn, provides the electli.e force field acting on the spray drops, leading to the spray transient c.oncentration . The c.oncen tration field, in combination with the electric field, results in a theoretic.al relat ion, which represents a deposition time constant as an index of the d1arg ing effect . The dependence of the time constant on a drop electli.c charge approves the positive role of a charged spray on improvement of the deposit ion within a shorter time interval . Although an increase in the spray concent ration, as well as the use of larger drops, also enhance the deposition, this en hancement indirectly stems from an increase in the drop charge, which occurs due to those fa.c.,t.ors. The results obtained from the model are also verified against the direct solution of the Poisson equation.
Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
127
136
http://sjme.journals.sharif.edu/article_5666_f64b436a46184e61568c2d23cd6a7016.pdf
DEVELOPMENT OF A NEW METHOD FOR DESIGN OF ADAPTIVE LEADLAG CONTROLLERS
A.
Nassirharand
Faculty of Aerospace Engineering Shahid Beheshti University
author
H.
Karimi
Dept. of Aerospace Engineering Khaje Nasir Toosi University of Technology
author
text
article
2008
per
A new method for the design of selftuning adap tive leadlag compensators is developed . The appli cation of this method to a nonlinear robot system, where a linear control theory has not been success ful, is presented . The selftuning block uses a set of linear algebraic equations to solve for compen sator paramet ers. This control strategy takes into account the nonlinear terms of the system and the application of this method reduces the manufactur ing costs of automatic control systems that have high accurae.y and perform ance.
Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
137
142
http://sjme.journals.sharif.edu/article_5667_2696a25ddd94a29cbf0a7356add2b676.pdf
NUMERICAL SIMULATION OF INVISCID FLOW AROUND HOVERING HELICOPTER ROTO UNSING UPWIND SCHEME ON UNSTRUCTURED MESHES
K.
Hejranfar
Dept. of Aerospace Engineering Sharif University of Technology
author
S. M.
Mohanunadi
Dept. of Aerospace Engineering Sharif University of Technology
author
text
article
2008
per
This paper presents an upwind solution of compress ble inviscid fl.owfield around a helicopter rotor in hover, using Roe's scheme on unstruct ured tetrahe dral meshes. Higher order differences are computed using a highorder :Yionotone upstream Centered Conservat ion Law (MUSCL) method . The numer ical algorithm utilizes an explicit time integration scheme and the solution is accelerated by apply ing the implicit residual smoothing at every stage of time integrat ion. To demonstrate the solution aceuracy, the numerical simulations of the fl.owfield around an isolated helicopter rotor , in hover, for two operating conditions of subsonic and transonic tip vfach numbers of 0.44 and 0.877, with a blade pitch angle of 8 deg, are performed . The present results for aerodynamic characteristies, including the pres sure distributions at different sections of the blade, are compared with numerical and experimental re sults. The effec.ts of the spatial solution accuracy of the numerical method on the fl.owfield character istics and aerodynamic results of the rotor are also studied.
Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
143
154
http://sjme.journals.sharif.edu/article_5668_1331bd4e33cc670c1aa9a0f33a7a5a3c.pdf
ANALYSIS OF EFFECTIVE PARAMETERS ON A ROTARY DESICCANT WHEEL PERFORMANCE
H.
Pahlavanzadeh
Dept . of Chemical Engineering Tarbiatmodares University
author
A.H.
Zamzamian
Dept . of Chemical Engineering Tarbiatmodares University
author
M.R.
Omidkhahnasrin
Dept . of Chemical Engineering Tarbiatmodares University
author
text
article
2008
per
Input wet air or process air is dried in a rotary dehumidifier, using solid desiccant particles that area means to the dehumidification of indoor air. The humidity amount on the surface of the desiccant is increased during the dehumidification process and is adsorbed by a regenerat ion air stream, which is ultimately exhausted to an1bient .In this study, the effect of the Ackermann heat transfer correction factor was investigated by using mathematical modeling of a solid desiccant wheel, as well as mass, energy and moment um balances on air and wet solid particles of the desiccant for the process and regeneration of an air stream. The re sults indicated that the dehumidific.a.t ion rate, along\Vith the desicc.a.nt wheel is dependent on humidity ratio, air velocity and the mass aitd heat transfer from the air stream to the desiecant bed and the Ackermann correction fa.c.tor. By increasing the in put air relative to the humidity and temperature by more thait 50% and 95°C, the respectively, the ack ermann factor correets the heat transfer
coefficient by up to 4%. The comparison between the ainmmt of humidity ratio, exit aitd inlet tem perature and air stream velocity, in the adsorption part of the ro tary desiccant wheel showed that the velocity of the exit air strean1 from the wheel is increased, due to the variation of humidity, temperature and pressure depletion. This mathemat ical model is also capable of depicting the details of superficial humidity and the temperature of the air stream into the desicc.a.nt wheel channels in both adsorpt ion and regeneration parts, as periodic: profiles.
Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
155
162
http://sjme.journals.sharif.edu/article_5669_a182b73bd6ca48938a057f33960880fa.pdf
CALCULATION OF THE HYDRODY NAMIC COEFFICIENTS OF TWODIMENSIONAL SHIP SECTIONS
D.
Tahvildarzadeh
Dept. of Mechanical Engineering Sharif University of Technology
author
M.S.
Seif
Dept. of Mechanical Engineering Sharif University of Technology
author
text
article
2008
per
In this paper, a calculation method of hydrody namic. coefficients of twodimensional ship sections for heave and sway motions, in cases of deep wa ter and zerofonvard speed, are discussed . In this method, seetions ean be in different geometrical shapes. For this purpose, a potential solution with multi pole expansion aitd twoparaineter Lewis con formal mapping, has been used. Using this method, a code is developed that is capable of calculating addedmass and dainping coefficients of cross  see tions. Also, the results of the code for circular, tri angular and rectangu lar sections are in good agree ment with experiments . Therefore, the developed code can be used for hydrodynam ic calculations of ships with any arbitrary hull form.
Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
163
170
http://sjme.journals.sharif.edu/article_5670_522dcf9dbfce6bb16ac14aa8d325b63d.pdf
INVESTIGATION OF SCALE EFFECT CORRECTION FACTOR IN SHIP RESISTANCE MODEL TEST
M.
Karimirad
Dept . of Mechanical Engineering Sharif University of Technology
author
M.
Askari
Dept . of Mechanical Engineering Sharif University of Technology
author
M.
Seif
Dept . of Mechanical Engineering Sharif University of Technology
author
text
article
2008
per
In small towing tanks , due to tank and model dimension limitations, tests has been perfomLed atlow Reynolds number and lan1inar flow regimes. In this condition, flow momentum is low and as are sult, the probability of flow separation is high. This has been resulted to a difference in flow behavior around the model and prototype. Therefore the scale effect in model testing cannot be avoided, which will be grater in small towing tanks . For eorrec.tion of results in all towing tanks, the seale effec.t correction factor has been used. This paper is a result of tests done on a model of a 35000 tons Produet Carrier. Tests have been done with and without a turbulent simulator and the scale c.orrec.tion fac.tor for both conditions has been evaluated. Results show that, without a turbu lent simulator, this factor approximate ly has been changed linearly. And, in the case of using a turbu lent simulator, the amount of this factor decreased extremely and varied nonlinearly.
Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
171
176
http://sjme.journals.sharif.edu/article_5671_4cb893d15c268cbe5d59b1cae91b9952.pdf
ACCURATE SHOCK CAPTURING BY SELECTION OF A SUITABLE ARITIFICAL VISCOSITY
H.R.
Anbarlooei
Dept . of Mechanical Engineering Tarbiat Modares University
author
K.
Mazaheri
Dept . of Mechanical Engineering Tarbiat Modares University
author
S.
Borji
Dept . of Mechanical Engineering Iranian,niversity of Science and Technology
author
text
article
2008
per
The addition of a fictitious term, artificial viscosity, into the inviscid Euler equations of fluid dynamics, in order to automatically ''capture" shock waves, is, perhaps, the oldest numerical device in the rel atively new field of r.omputational physics and me chanics. Many different functional forms for artificial viscosity have been proposed. These forms eontain problemsensitiveconstants that are often set in a somewhat arbitrary manner . The purpose of this work is to choose a suitable fomL to remove
as many of these arbitrary constants as possible.For this purpose, a form presented by Caramana is seleeted. This form has some important proper ties, namely1 dissipativity, Galilean invarianee, abil ity to distinguish between shock waves, adiabatic compression and turning off completely for rigid mot ion. Properties are enforced to this form by use of a limiter. :'\umerical results show more ac. curate shock wave capturing in nonplanar spaces, especially in the convergent cases, than in the other forms of artificial viscosity.
Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
177
186
http://sjme.journals.sharif.edu/article_5672_63b059ec0eaff865b3f4cf47a45adad5.pdf
NUMERICAL ANALYSIS OF A GEOTHERMAL SNOWMELTING SYSTEM ON A TYPICAL BRIDGE
S.
Porkhial
Islamic Azad University  Karaj Unit.
author
0.
Asgari
Dept. of Mechanical Engineering Sharif University of Technology
author
M.R.
Shirzadi
Dept. of Mechanical Engineering Khaje Nasir Toosi University of Technology
author
text
article
2008
per
A geothermal snow melting system consists of hydronic tubes embedded at critic.al points of roads, highways and bridges. A fluid can be heated by using a ground source heat pump system (GSHP) and circulated through the embedded pipes to prevent freezing conditions on the surface. The goal of this paper is to find practical techniques to de crease the operation time of heat pumps to save en ergy. This paper consists of a 2D parametric simu lation of a typical bridge, considering the weather of Tehran.This imulation contains different paramet ric. inputs, like physical propert ies and geographical conditions.One important c.haracterist ic. of this pa per is the c.onsideration of different layers and ma terials in the bridge.
Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
187
193
http://sjme.journals.sharif.edu/article_5673_140de462f4f6968405f6c4bcfaae93ea.pdf

text
article
2008
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Sharif Journal of Mechanical Engineering
Sharif University of Technology
26764725
دوره 23
v.
40.2
no.
2008
169
200
http://sjme.journals.sharif.edu/article_20478_4ae3ae54aad4f871c8beef9cfefc216a.pdf