eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2005-08-01
18
3
219
228
71588
The Effect of Added Mass Fluctuation on Heave Vibration of TLP
A. A. Golafshani
golafshani@sharif.edu
1
M.S. Seif
seif@sharif.edu
2
M. R. Tabeshpour
tabesh_mreza@yahoo.com
3
Civil Engineering, Sharif University of Technology
Mechanical Engineering, Sharif University of Technology
Mechanical Engineering, Sharif University of Technology
The resulting motion in waves can be considered as a superposition of the motion of the body in still water and the forces on the restrained body. In this study the effect of added mass fluctuation on vertical vibration of TLP in the case of vibration in still water for both free and forced vibration subjected to axial load at the top of the leg is presented. This effect is more important when the amplitude of vibration is large. Also this is important in fatigue life study of tethers. The structural model used here is very simple. Perturbation method is used to formulate and solve the problem. First and second order perturbations are used to solve the free and forced vibration respectively.
https://www.ije.ir/article_71588_aa1c8eacde6afcf2c8b5bc76866343d3.pdf
Added Mass Fluctuation
Wave
TLP
Heave Vibration
Perturbation Method
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2005-08-01
18
3
229
238
71589
Evaluation of Rough Set Theory for Decision Making of rehabilitation Method for Concrete Pavement
M. Arabani
arabani@guilan.ac.ir
1
Civil Engineering, University of Guilan
In recent years a great number of advanced theoretical - empirical methods has been developed for design & modeling concrete pavements distress. But there is no reliable theoretical method to be use in evaluation of conerete pavements distresses and making a decision about repairing them. Only empirical methods is used for this reason. One of the most usual methods in evaluating concrete pavements distresses is to determine the PCI of the Pavement Condition Index. As a result of large number of variables and complicated decision - making algorithm using the information obtained in this method, may have some difficulties. Presenting an analytic -theoretical method mixed with the PCI method may be the bases for the development of a theoretical empirical method in evaluation of concrete pavements distresses & can remove the diffculties.The present paper describes a method of applying the rough set theory for evaluation of reinforced concrete highway pavements distresses in PCI method to extract the minimal decisian algorithm and selecting the best suitable method of rehabilitation. The significance of the conditional attributes retained in the minimal decisian algorithmis evaluated, and a method of deriving rules from the algorithm for the constraction of expert system is described. The result of this procedure shows the high reliability of this method, using the minimum necessary informations.
https://www.ije.ir/article_71589_d8189a5b06fa079fc6057dfc2abee511.pdf
Concrete pavements
Rough Set
Pavement distress
pavement management
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2005-08-01
18
3
239
252
71590
Sensitivity Analysis of Parameter Hanges in Nonlinear Hydraulic Control Systems (RESEARCH NOTE)
H. Ajam
hajam@hamoon.usb.ac.ir
1
S. Farahat
farahat@hamoon.usb.ac.ir
2
Mechanical Engineering, University of Sistan & Baluchestan
Mechanical Engineering, University of Sistan & Baluchestan
.
https://www.ije.ir/article_71590_0e079b10a00f492abfae63f1af23d309.pdf
Sensitivity analysis
Nonlinear systems
Hydraulic Control Systems
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2005-08-01
18
3
253
261
71591
Effects of Slip Condition on the Characteristic of Flow in Ice Melting Process
A. Nouri Borujerdi
anouri@sharigf.edu
1
M. Rad
rad@sharif.edu
2
A. Raoufpanah
a_raoufpanah@yahoo.com
3
Mechanical Engineering, Sharif University of Technology
Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
, Islamic Azad University
In this paper a laminar flow of water on an ice layer subjected to a slip condition is considered numerically. The paper describes a parametric mathematical model to simulate the coupled heat and mass transfer events occurring in moving boundary problems associated with a quasi steady state steady flow process. The discretization technique of the elliptic governing differential equations of mass, momentum and energy is based on the control volume finite difference approach and enthalpy method. the results illustrate, the distribution of heat transfer coefficient, ice melting thickness, slip velocity at solid moving boundary and boundary layer thickness for some values of slip velocity coefficient , Cu.
https://www.ije.ir/article_71591_1d52c194c112bea65766fa6aac4064ea.pdf
Slip velocity
Moving Boundary
Melting
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2005-08-01
18
3
263
271
71592
Controllable Multi-Server Queue with Balking (TECHNICAL NOTE)
Pankaj Sharma
sharma_ibspankaj@rediffmail.com
1
G. C. Sharma
gokulchandra@sancharnet.in
2
Madhu Jain
drmadhujain@yahoo.co.in
3
Mathematics, Noida International University, India
Mathematics, I.B.S, AGRA
Department Of Mathematics, IIT Roorkee,Roorkee,India
https://www.ije.ir/article_71592_12227ecd1f70d5a42642edb3798b319a.pdf
Controllable queue
multi
Server
Markov chain
Bivariate Poisson distribution
Balking
Additional Server
Queue Size
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2005-08-01
18
3
273
284
71593
The Finite Horizon Economic Lot Scheduling in Flexible Flow Lines
B. Karimi
b.karimi@aut.ac.ir
1
S. M. T. Fatemi Ghomi
fatemi@aut.ac.ir
2
S. A. Torabi
satorabi@ut.ac.ir
3
Industrial Engineering, Amirkabir University of Technology
Industrial Engineering, Amirkabir University of Technology
School of Industrial Engineering, University of Tehran
This paper addresses the common cycle multi-product lot-scheduling problem in flexible flow lines (FFL) where the product demands are deterministic and constant over a finite planning horizon. Objective is minimizing the sum of setup costs, work-in-process and final products inventory holding costs per time unite while satisfying the demands without backlogging. This problem consists of a combinatorial part (machine assignment and sequencing sub-problems) and a continuous part (lot sizing and scheduling sub problems). To account for these two elements, a new mixed integer nonlinear program (MINLP) is developed which simultaneously determines machine allocation, sequencing, lot-sizing and scheduling decisions. In order to reduce computational complexity, instead of solving this MINLP directly, we propose an efficient enumeration method to determine optimal solution of the model. Moreover, the performance of the proposed method is evaluated by some numerical experiments. Two other applicable cases (zero setup costs and Lot streaming) are studied and required modifications in the model formulation and the solution method are described. Finally, a case example in a PCB assembly system is presented to illustrate applicability of the mathematical model and the proposed solution method.
https://www.ije.ir/article_71593_e8ba1dbfe82ee2fe513ec9f1fff07a7a.pdf
Lot
scheduling
Flexible Flow Line
Common cycle approach
Finite horizon
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2005-08-01
18
3
285
293
71594
The Effects of Potassium Promoter on the Syngas Conversion of Cobalt Catalysts (TECHNICAL NOTE)
M. Khoshnoodi
khosh@hamoon.usb.ac.ir
1
R. Akhavan
akhvan1970@yahoo.com
2
H. Atashi
h.ateshy@hamoon.usb.ac.ir
3
Chemical & Petroleum Engineering, University of Sistan & Baluchestan
Chemical & Petroleum Engineering, University of Sistan & Baluchestan
Chemical Engineering, Sistan & Blochestan university
The effects of potassium promoter for production of heavy hydrocarbons from syngas with silica- supported cobalt catalysts has been studied. After preparing the catalysts in accordance with the sol-gel method, they were subjected to various tests by using a small steely micro-reactor and capable of operating in diversified situations, such as stable temperature range, flow rate, space velocity, etc. Thorough observations revealed that the conducive situations can be achieved by the ratio of H2/CO=2 with a temperature of 220 ºC, whereas the flow rate of CO and N2 components must be equal about 35 ml/min.
https://www.ije.ir/article_71594_934de2b8a2a129423c28d42c1d80ab1d.pdf
Fischer
Tropsch
Synthesis
Olefin
Synthesis gas
Cobalt catalyst
Promoter
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2005-08-01
18
3
295
300
71595
Infiltration of Porous Zircon Preforms With Alumina Precursor (TECHNICAL NOTE)
T. Ebadzadeh
t.ebadzadeh@merc.ac.ir
1
Ceramic Department, Materials and Energy Research Center
A process is described which involves infiltration of aluminum nitrate into partially sintered (porous) zircon bodies. Infiltration kinetics were studied using infiltration curves with two distinct regions. The final infiltrated samples were sintered at 1600 °C for 2 h and yielded specimens containing the tetragonal zirconia.The experimental results show that in spite of the similar porosity of the infiltrated preform and of pure zircon sintered at 1600 °C, the former has a higher flexural strength and fracture toughness due to the incorporation of the ZrO2 particles and the elongated mullite grains resulting from the infiltration and subsequent heating of the preform.
https://www.ije.ir/article_71595_8e0a8f1fca77aa67017354dc89e1d631.pdf
Infiltration
Al2O3 precursor
Zircon
Mullite
Mechanical properties
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2005-08-01
18
3
301
318
71596
A Reliable and Economically Feasible Automatic Meter Reading System Using Power Line Distribution Network (TECHNICAL NOTE)
S. K. Wong
hasnomail@ije.ir
1
M. Moghavvemi
mahmoud@um.edu.my
2
Electerical Engineering, University of Malaya
Electerical Engineering, University of Malaya
Automatic Meter Reading (AMR) is the remote collection of consumption data from customer’s utility meters over telecommunications, radio, power line and other links. AMR provides water, electric and gas utility−service companies the opportunities to streamline metering, billing and collection activities, increase operational efficiency and improve customer service. Utility company uses technologies that were developed several decades ago with the majority of the meters being read visually. With manual readings, considerable time is used to physically check out each unit. AMR becomes a viable option to overcome this problem of time wastage to obtain the meter readings. There are many different forms of communication links that can be utilized as the communication medium in an AMR system. One such link is the power line carrier or PLC. The advantages of using the PLC as the communication medium are readily apparent since the power line network is the property of the utility company and its infrastructure is already there. However, power lines are never meant for communication and creates much noise and therefore, various modifications has to be made to make the PLC suitable to be the AMR communication channel. The AMR system consists of three major components: the meter interface module, communications system, and data concentrator. This paper details a feasibility study on the creation of a robust bi-directional/two-way communication system between an electricity meter and a distant control unit (data concentrator) over the low voltage (LV) distribution grid. Basic functions of the AMR system include the provision for remote connection and disconnection of meter and fraud detection features at both the meter interface and the data concentrator. As a support system to the entire AMR, batteries are utilized. They are especially important in the cases of power failures. Lithium-ion batteries are the type of batteries that are used as these batteries tend to last longer than most other batteries. The main advantage of this system is that it is a low cost system that produces very encouraging results and it can be implemented upon existing electro-mechanical meters without the need of purchasing new meters. With many existing meters being the electromechanical meters, the need for a high-cost, large-scale implementation of new electronic device meters to enable implementation of the AMR system is unnecessary. The cost of implementation is low and the benefits, especially economically, that it brings to the utility company are immense.
https://www.ije.ir/article_71596_f0f559a9a8509c41264ca3c54df4a860.pdf
Atomatic metro reading
Control Unit
Power line
Distribution network