Search for: stacking
0.009 seconds
Total 74 records

    Thermal considerations on the design and operation of lens ducts

    , Article Optics and Laser Technology ; Volume 35, Issue 6 , 2003 , Pages 415-423 ; 00303992 (ISSN) Golnabi, H ; Sharif University of Technology
    In this paper, heat effects due to powerful pump beam in the lens duct delivery system is investigated and subsequent thermal effects are described. Temperature raise in the device, thermal loading, and material considerations for the lens ducts fabrication are reported. For an absorbed intensity of 10 W/cm2 in a 4 cm-long lens duct, the temperature difference between the midpoint and its faces, for a lens duct made from borosilicate is 7.05°C, for sapphire 4.01°C, and for synthetic fused silica is the smallest value of 0.54°C. For a typical absorbed intensity of 1.4 W/cm2 in a 4 cm-long lens duct, with a steady-state time constant of 120 s, the fractional thermal loading is 1.98% for BK-7,... 

    Evaluation of the role of deformation twinning in work hardening behavior of face-centered-cubic polycrystals

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 39, Issue 2 , 2008 , Pages 294-303 ; 10735623 (ISSN) Hamdi, F ; Asgari, S ; Sharif University of Technology
    Results of an investigation on the evolution of microstructure during simple compression testing of two face-centered-cubic (fcc) polycrystals, IN625 superalloy and 316L stainless steel, are reported and a review on the existing data related to the uniaxial deformation of fcc polycrystals is presented. It is found that while a number of fcc polycrystals show linear hardening behavior, the evolution of the underlying microstructure may be quite different. It is argued that, in contrast to the current belief, deformation twinning may not be the sole cause of linear hardening in low stacking fault energy (SFE) fcc polycrystals. It is suggested that, due to the requirement of slip system change... 

    A dynamic-reconfigurable architecture for protocol stacks of networked systems

    , Article 31st Annual International Computer Software and Applications Conference, COMPSAC 2007, Beijing, 24 July 2007 through 27 July 2007 ; Volume 1 , 2007 , Pages 609-612 ; 07303157 (ISSN) ; 9780769528700 (ISBN) Niamanesh, M ; Jalili, R ; Sharif University of Technology
    This paper proposes a software framework for dynamic-reconfigurable protocol stack. The framework presents mechanisms andan algorithm/or all required phases for reconfiguration of a running protocol component that include freezing the component in a safe state, changing the component, and state transfer to a new component. Considering that every running protocol component communicates with at least one peer component in another system, we perform the reconfiguration with respect to the peer component. © 2007 IEEE  

    Design and implementation of a dynamic-reconfigurable architecture for protocol stack

    , Article 2nd IPM International Symposium on Fundamentals of Software Engineering, FSEN 2007, Tehran, 17 April 2007 through 19 April 2007 ; Volume 4767 LNCS , 2007 , Pages 396-403 ; 03029743 (ISSN); 9783540756972 (ISBN) Niamanesh, M ; Sabetghadam, S ; Rahaghi, R. Y ; Jalili, R ; Sharif University of Technology
    Springer Verlag  2007
    Future communication and computation devices require mechanisms for on-the-fly reconfiguration in their protocol stack to operate in different situations and networks. This paper proposes a component-based framework for dynamic-reconfigurable protocol stack. Considering that every running protocol component communicates with at least one peer component, unlike related work our framework supports synchronous reconfiguration of two peer protocol components in two communicating protocol stacks. © Springer-Verlag Berlin Heidelberg 2007  

    Dependency modeling of steady state grain size on the stacking fault energy through severe plastic deformation

    , Article Materials Letters ; Volume 159 , November , 2015 , Pages 410-412 ; 0167577X (ISSN) Parvin, H ; Kazeminezhad, M ; Sharif University of Technology
    Elsevier  2015
    Recent investigations have shown that the steady state grain size of severely deformed materials is dependent on the stacking fault energy. In this paper, a model is presented to investigate such a dependency which uses thermodynamics based calculations. The present model shows that the relationship between the steady state grain size and the stacking fault energy of material is in power law form, directly. Furthermore, the model shows that the steady state grain size has an exponential relationship with the self-diffusion activation energy and a decrease in the self-diffusion activation energy increases the steady state grain size. The model predictions are in good agreement with the... 

    The Study of Heat Treatment Effect after Cold Work on MP35N Superalloy Hardenability

    , M.Sc. Thesis Sharif University of Technology Jazayeri, Ali Asqar (Author) ; Asgari, Sirous (Supervisor)
    MP35N superalloy is a Co-Ni based superalloy with significant work hardening and strengthening properties. In this study secondary hardening in this alloy is investigated by different transmission electron microscopy techniqes. Images of the transmission electron microscope revealed a high density of dislocations and deformation twins in the cold work samples. There were no evidence of any Co3Mo precipitation or hcp martensitic phase in the cold worked samples. Performed study on aged sample showed wide distribution of stacking fault by traditional techniqes and Weak Beam. On the other hand, information which was concluded of STEM method with HAADF detector, exhibits the entrance of heavy... 

    Modeling the Effect of Stacking Fault Energy on Severe Plastic Deformation of Metals

    , M.Sc. Thesis Sharif University of Technology Parvin, Hooman (Author) ; Kazeminezhad, Mohsen (Supervisor)
    Nowadays, modeling the deformation behavior of materials is an indispensable tool to describe the evolutions of microstructure and mechanical properties of materials during deformation. As previous investigations have shown, the dislocation density is the most appropriate parameter for investigating the deformation behaviour of materials. In present research, considering the effect of stacking fault energy (SFE), the deformation behavior is investigated. In this regard, at first a thermodynamics based modeling of deformation is presented. Previous studies have shown that due to heterogeneous distribution of dislocations during severe plastic deformation, it is needed to use multi-variable... 

    Mixture of mlp-experts for trend forecasting of time series: A case study of the tehran stock exchange

    , Article International Journal of Forecasting ; Volume 27, Issue 3 , 2011 , Pages 804-816 ; 01692070 (ISSN) Ebrahimpour, R ; Nikoo, H ; Masoudnia, S ; Yousefi, M. R ; Ghaemi, M. S ; Sharif University of Technology
    A new method for forecasting the trend of time series, based on mixture of MLP experts, is presented. In this paper, three neural network combining methods and an Adaptive Network-Based Fuzzy Inference System (ANFIS) are applied to trend forecasting in the Tehran stock exchange. There are two experiments in this study. In experiment I, the time series data are the Kharg petrochemical company's daily closing prices on the Tehran stock exchange. In this case study, which considers different schemes for forecasting the trend of the time series, the recognition rates are 75.97%, 77.13% and 81.64% for stacked generalization, modified stacked generalization and ANFIS, respectively. Using the... 

    DRAPS: a framework for dynamic reconfigurable protocol stacks

    , Article Journal of Information Science and Engineering ; Volume 25, Issue 3 , 2009 , Pages 827-841 ; 10162364 (ISSN) Niamanesh, M ; Jalili, R ; Sharif University of Technology
    Forthcoming networked systems require mechanisms for on-the-fiy reconfiguration in their protocol stacks to be able to operate in different situations and networks. Since every protocol in a protocol stack has at least one peer protocol in another system, dynamic reconfiguration of a protocol raises the need for reconfiguration in the peer stack. For an assured dynamic (run-time) reconfiguration, executions of two peer protocols are stopped in a safe state, new protocols are initialized, and stacks switch to the new protocols at the same time. This paper proposes a software framework for dynamic reconfiguration of two communicating protocol stacks. A distributed algorithm is implemented in... 

    Acousto-refrigerator with an adjustable mechanical resonator

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 21, Issue 2 , 2008 , Pages 183-196 ; 1728-144X (ISSN) Amjadi, A ; Abolhassani, M. R ; Jafari, S. B ; Sharif University of Technology
    Materials and Energy Research Center  2008
    Thermoacoustics describes energy conversion processes, activated by interaction temperature oscillation, accompanying the pressure oscillation in a sound wave, with solid boundaries. In ordinary experience this interaction of sound and heat cannot be observed, because of the very low temperature differences, but under suitable conditions, it can be emphasized and amplified to create remarkable thermodynamic effects such as, steep thermal gradients, powerful convective heat fluxes, and strong sound fields. We designed and constructed a simple thermoacoustic refrigerator with an adjustable mechanical resonator, coupled with the acoustic resonator. Our experimental data showed about % 10... 

    Strain hardening mechanisms in aged AEREX350 superalloy

    , Article Materials Science and Engineering A ; Volume 398, Issue 1-2 , 2005 , Pages 204-208 ; 09215093 (ISSN) Najafi, H ; Asgari, S ; Sharif University of Technology
    In this paper, results of an investigation on strain hardening mechanisms of aged AEREX350 alloy during room temperature compression testing are reported. TEM studies were conducted on commercial samples aged at 850 °C both before and after deformation in a strain range of 0.15-0.27. It was found that only coherent γ′ precipitates with L12 structure formed in these samples prior to deformation. TEM studies also showed twin intersections in the deformed samples. Based on these observations, it is suggested that the high strain hardening rate of the aged material in this strain range is mainly related to the formation of intersecting deformation twins. This is attributed to the decrease in the... 

    Influence of stacking fault energy and short-range ordering on dynamic recovery and work hardening behavior of copper alloys

    , Article Scripta Materialia ; Volume 62, Issue 9 , May , 2010 , Pages 693-696 ; 13596462 (ISSN) Hamdi, F ; Asgari, S ; Sharif University of Technology
    True stress vs. true strain responses of Cu-6 wt.% Al and Cu-12 wt.% Mn alloys are presented. While Cu-6 wt.% Al alloy shows the typical mechanical response of low stacking fault energy alloys, the Cu-12 wt.% Mn alloy behaved similarly to medium to high stacking fault energy alloys. These findings clearly show that while short-range ordering triggers slip planarity, it has a minor effect on total dynamic recovery of these copper alloys  

    Toward A Safe, Assured, and Dynamic Communication Protocol Stack

    , Ph.D. Dissertation Sharif University of Technology Niamanesh, Mahdi (Author) ; Jalili, Rasool (Supervisor)

    Study of Temperature and Stress Effects on Phase Transformation in MP35N

    , M.Sc. Thesis Sharif University of Technology Shaker Ardakani, Morteza (Author) ; Asgari, Sirous (Supervisor)
    Many Investigations have been carried out on high work hardening, strengthening and secondary hardening of MP35N superalloy. In this study, behavior of MP35N under uniaxial hot compression at 600 °C with true strain of 0.05, 0.10, 0.16 and 0.22 was investigated. After calculating on stress- true strain curve, work hardening rate versus strain come out. Serrated flow has been seen in all mentioned strains. In TEM investigation on these samples, dislocations array with extended faults and micro twinning have been seen. According to Suzuki mechanism with solute partitioning and diffusion of solute, stacking fault extended. Uninterrupted separations and combinations of partial dislocations lead... 

    A Solution Recommender for Exceptions in an Integrated Development Environment

    , M.Sc. Thesis Sharif University of Technology Amintabar, Vahid (Author) ; Heydarnoori, Abbas (Supervisor)
    Exceptions are an indispensable part of a software development process. Developers usually rely on imprecise results from a web search to resolve the exceptions. More specifically, they manually design a query based on the information indicated by the exception message and the stack trace of that exception. Afterwards, they choose and adapt a solution from the web search results. In this scenario, there is a gap between the development environment and web browsers. Moreover, manual search is very time consuming and a lot of useful information from the code is lost. In this thesis, we introduce Exception Tracer, an Eclipse plugin that helps developers find solutions of exceptions. Exception... 

    Improving Answers in the Stack Overflow Q & A Website

    , M.Sc. Thesis Sharif University of Technology Tavakkoli, Mohammad Reza (Author) ; Heydarnoori, Abbas (Supervisor)
    In recent years, most of the programmer’s problems are solved using Q&A websites, e.g. Stack Overflow. Since the number of users, questions and answers in these websites are rapidly increasing, manually moderating and enhancing the quality of the posts (specially the answers) seems to be impossible. Despite the various studies on issues with Q&A websites and facilitating their use, there has been no studies on the field of improving the quality of answers. In this study, we intend to provide an appropriate solution to enhance the problem of low-quality answers. In order to demonstrate the proposed approach, we recommend a tool called StImp, which is a plugin for Eclipse. Using this plugin,... 

    A Comparative Approach between Deep Learning and MLE for Monitoring Multivariate Processes with Chaotic Trends

    , M.Sc. Thesis Sharif University of Technology Rahimi Movassagh, Maryam (Author) ; Akhavan Niaki, Taghi (Supervisor)
    There are a variety of multivariate industrial processes in real world problems. It seems to be necessary to control them through strong tools such as control charts. One of the state-of-the-art methods to monitor processes is neural network. Neural networks are data processing systems inspired by human brain and they are capable of processing data with a variety of small processors working in parallel forming an integrated network to solve a problem. Chaotic models, one of the states of being out of control, are deterministic non-linear models which have extremely complex behavior under determined assumption. Researches have shown neural networks have excellent performance in such systems.... 

    Performance Analysis of Thermoacoustic Prime Mover

    , M.Sc. Thesis Sharif University of Technology Sadeghizadeh, Zahra (Author) ; Ghorbanian, Kaveh (Supervisor)
    Traveling wave thermoacoustic prime mover is studied in this project. For this purpose, based on one dimensional thermoacoustic equations, thermoacoustic flow is modeled in each segment of thermoacoustic systems. Since regenerator is the most important segment in a traveling wave thermoacoustic prime mover, modeling of the flow in regenerator is considered as the primary motivation for this research. In order to model the thermoacoustic engines, governing 1D relations are simplified and developed. Moreover, to solve equations in regenerator, tortuous geometry of regenerator is approximated with the stack consisting of circular pores. Therefore, in this research stack relations has been used... 

    Design,Build and Test a Lab-Scale Thermoacoustic Prime Mover

    , M.Sc. Thesis Sharif University of Technology Gholinejad Lindi, Abbas (Author) ; Ghorbanian, Kaveh (Supervisor)
    Acoustic science and it’s applications in thermodynamic, cause the new achievements in different field of scientific and industrial. Thermoacoustic is a new technique of acoustic that analyzes the thermodynamic fluctuations related to time and displacement. In other word, thermoacoustic is a field of transformation between acoustic energy and thermal energy. Thermoacoustic devices Include refrigeration equipment, motors, pumps, heat or a combination of these devices that are used to transfer and convert acoustic energy to thermal energy. The thermoacoustic systems that their functions are based on the interaction between acoustic wave and gas particle that does exist it’s around are new... 

    Feasibility and Performance Analysis of a Thermoacoustic Heat Pump

    , M.Sc. Thesis Sharif University of Technology Askari, Rasoul (Author) ; Ghorbanian, Kaveh (Supervisor)
    Thermoacoustics deals with the conversion of heat energy into sound energy and vice versa. This new and emerging technology has a strong potential towards the development of sustainable and renewable energy systems by utilizing waste heat or solar energy. Although thermoacoustic devices are simple to fabricate; however, the design process is very challenging. The thermoacoustic phenomenon is discovered over a century ago; nevertheless, the rapid advancement in this field occurred during the past three decades when the theoretical understanding of the phenomenon is developed along with the prototype devices. There are several advantages of heat engines and refrigerators based on...