Atmospheric optical CDMA via optical orthogonal codes

, Article IEEE Transactions on Communication ; Vol.54, No.9, PP. 1614-1623, September 2006 Jazayerifar, M ; Salehi, J. A ; Sharif University Of Technology

Abstract

We propose and consider using a class of multiple-access sequences, namely, optical orthogonal codes (OOCs) in atmospheric optical code-division multiple-access systems. We obtain analytical solutions to the error probability for various channel models using positive-intrinsic-negative diode and avalanche photodiode photodetectors. In our analysis, the effects of atmospheric turbulence, ambient light, thermal noise, and multiuser interference are considered, in the context of a semiclassical photon-counting approach. The performance of the systems taking advantage of space diversity and error-correcting codes are also evaluated. Two common and widely used optical modulations, on-off keying...

Transmission of multiband OFDM and impulse radio ultrawideband signals over single mode fiber[electronic resource]

, Article IEEE Journal of Lightwave Technology ; Vol. 26, No. 15, PP. 2594-2603, August 2008 Jazayerifar, M ; Cabon, B ; Salehi, J. A ; Sharif University Of Technology

Abstract

In this paper we examine the transmission of two types of ultra-wideband (UWB) signals, multiband orthogonal frequency division multiplexing (MB-OFDM) and impulse radio ultra-wideband (IR-UWB), over single mode fiber at 1550 nm. In order to investigate the impact of optical components such as laser diode, external modulator and single mode fiber on UWB signals, we develop mathematical models for these components. These models are experimentally verified and corresponding numerical parameter values are obtained by experiment. Using these models we discuss the transmission of two types of UWB signals over single mode fiber. A new figure of merit namely distortion factor is defined. Using...

Atmospheric optical CDMA communication systems via optical orthogonal codes

, Article IEEE Transactions on Communications ; Volume 54, Issue 9 , 2006 , Pages 1614-1623 ; 00906778 (ISSN) Jazayerifar, M ; Salehi, J. A ; Sharif University of Technology

2006

Abstract

We propose and consider using a class of multiple-access sequences, namely, optical orthogonal codes (OOCs) in atmospheric optical code-division multiple-access systems. We obtain analytical solutions to the error probability for various channel models using positive-intrinsic-negative diode and avalanche photodiode photodetectors. In our analysis, the effects of atmospheric turbulence, ambient light, thermal noise, and multiuser interference are considered, in the context of a semiclassical photon-counting approach. The performance of the systems taking advantage of space diversity and error-correcting codes are also evaluated. Two common and widely used optical modulations, on-off keying...

Optical Transmission of UWB Signals

, Ph.D. Dissertation Sharif University of Technology Jazayerifar, Mahmoud (Author) ; Salehi, Javad (Supervisor)

Abstract

In this thesis we examine and study the transmission of Ultra Wide Band (UWB) signals over single mode fiber in a radio over fiber system. We begin by developing mathematical model for the key optical components employed in radio over fiber systems. The authenticity of these models is verified with experimental results. Following the above models as well as experiment results, the transmission of UWB signals over optical fiber is investigated. The impact of limited operating bandwidth and nonlinearity of the electrical to optical transfer function on UWB signals is examined. Two types of UWB signals, namely, multi-band orthogonal frequency division multiplexing (MB-OFDM) and impulse radio...

Analytical study of binary differential impulse radio-ultra wide band over single-mode fibre systems using two receiver structures

, Article IET Communications ; Volume 3, Issue 2 , 2009 , Pages 309-320 ; 17518628 (ISSN) Jazayerifar, M ; Salehi, J. A ; Cabon, B ; Sharif University of Technology

2009

Abstract

A binary differential impulse radio-ultra wide band (IR-UWB) communication scheme over a single-mode optical fibre is examined. For a receiver structure, the conventional electrical receiver as well as an optical receiver structure, which is similar to the optical receiver used for digital, optically phase-modulated differential phase shift keying, are considered. The optical receiver can alleviate the IR-UWB receiver implementation challenges and it is studied for the first time in the context of IR-UWB. Considering various important noises, for example, phase noise, laser intensity noise, thermal noise and shot noise, analytical expressions for the error probability of the aforementioned...

Transmission of multi-band OFDM and impulse radio ultra-wideband signals over single mode fiber

, Article Journal of Lightwave Technology ; Volume 26, Issue 15 , 2008 , Pages 2594-2603 ; 07338724 (ISSN) Jazayerifar, M ; Cabon, B ; Salehi, J. A ; Sharif University of Technology

2008

Abstract

In this paper we examine the transmission of two types of ultra-wideband (UWB) signals, multiband orthogonal frequency division multiplexing (MB-OFDM) and impulse radio ultra-wideband (IR-UWB), over single mode fiber at 1550 nm. In order to investigate the impact of optical components such as laser diode, external modulator and single mode fiber on UWB signals, we develop mathematical models for these components. These models are experimentally verified and corresponding numerical parameter values are obtained by experiment. Using these models we discuss the transmission of two types of UWB signals over single mode fiber. A new figure of merit namely distortion factor is defined. Using this...

Optimum power allocation in parallel poisson optical channel

, Article 2009 10th International Conference on Telecommunications, ConTEL 2009, Zagreb, 8 June 2009 through 10 June 2009 ; 2009 , Pages 285-288 ; 9789531841313 (ISBN) Alem Karladani, M. M ; Sepahi, L ; Jazayerifar, M ; Kalbasi, K ; Sharif University of Technology

2009

Abstract

In this paper we investigate the Shannon capacity of single and parallel Poisson channels in different scenarios. At first, by examining the capacity equation of the single Poisson channel, the minimum average power that maximizes the capacity is found. Then, applying the method of Lagrange multipliers on the capacity expression of the parallel Poisson channel, we obtain the optimum power allocation maximizing the parallel Poisson channel capacity

Optimum receiver design for transmitted-reference signaling [electronic resource]

, Article IEEE Transactions on Communications ; May 2010, Volume 58, Issue 5, P.1589-1598 Farhang, M. (Mahmoud) ; Salehi, J. A ; Sharif University of Technology

Abstract

Autocorrelation receiver (AcR) is usually used as the general receiver for transmitted reference (TR) communication systems on a quite intuitive basis. In this paper, we apply the principle of statistical invariance to obtain the optimum TR receiver on a decision-theoretic basis, and it is shown that the autocorrelation receiver is optimal only in a special case. Performance of the optimum receiver and the suboptimum AcR for some important modulation schemes is also evaluated. The results imply that allocating a part of the transmitted energy and bandwidth to reference pulses would not help improve the performance of the system and the optimal performance might be achieved via much simpler...

The Feasibility Study of Micronized Powder Plant for Exporting (UNIDO METOD)

, M.Sc. Thesis Sharif University of Technology (Author) ; Hooshmand, Mahmoud (Supervisor)

Abstract

This thesis deals with the development of a hypothetical micronized powder factory and trying to test and engage in this hypothetical development of the following plant, it considers following factors:
1-Domestic & International market
2-Plant location
3-Plant design & development
a.machinery
b.technology & equipment
c.human resource
d.environment
e.packing
4-raw material
5-shipping & transport
To evaluate above factors the UNIDO methodology is used in this research work. The UNIDO methods are using a process by which feasibility studies of production facilities or plant are base on. After reviewing a variety of factors, ranging from financial...

Evaluating the Leanness and Agility Indexes of S.G.S Co

, M.Sc. Thesis Sharif University of Technology Lotfi, Maryam (Author) ; Houshmand, Mahmoud (Supervisor)

Abstract

In this research ,lean and agile indexes in S.G.S Co. are evaluated. This company is the first company in engineering and supplying automotive parts as well as the first supply chain management and organization of Saipa Group. In the part of evaluating the lean management level it is the developed model of the suggested approach by Jackson “implementing a lean management system” (Jackson, 1996). As S.G.S is engaged in servicing activities not in production, we have changed some factors in Jackson's methodology. Different with the last model, we got the results and used AHP method for getting the level in each key. Finally by using another AHP the lean index of the S.G.S Co. was identified....

, M.Sc. Thesis Sharif University of Technology Kelaretaghi, Naghi (Author) ; Hesaraki, Mahmoud (Supervisor)

Abstract

Our problem is to evaluation state and form of a tracer passing through the vessel. Using this method, we can identify the effect of during used in some defected parts of body. This evaluation leads to in solving a Laplace equation with mixed boundary condition. Separating that problem, we reach to a collection of algebraic and linear equations. Solving this system, we approximate coefficients of the solution with a series the existence and uniqueness of and analytic solution has been proved using the Eigen functions finally, using numerical algorithms, we have interpreted the analytical solutions.

An optimal Liouville-Type Theorem for Radial Entire Solutions of the Porous Medium Equation with Source

, M.Sc. Thesis Sharif University of Technology Ansari, Hajar (Author) ; Hesaraki, Mahmoud (Supervisor)

Abstract

In this thesis , we consider nonnegative (continuous) weak solutions of the porous medium equation with source , u_t-∆u^m=u^p, and p>m>1 .
Assume that, m>1 and 1< p/m u_t-∆u^m=u^p,xϵR^n ,tϵR
has no nontrivial, bounded radial solutions u≥0 .
In one space-dimensional, the conclusion of the result mentioned above remains true without the assumption of the radial symmetry. The proof is based on the intersection-comparison arguments , zero number argum- ents and a key step is to show the...

A Novel Framework to Enable STEP-NC Extension of Tool Library Based on Cloud Manufacturing Paradigm

, M.Sc. Thesis Sharif University of Technology Alavian, Pooya (Author) ; Houshmand, Mahmoud (Supervisor)

Abstract

ISO 10303 Standard also known as STEP, is an standard in the domain of mechanical manufacturing that describes data relating to drawings, design, machining, process planning, engineering and other aspects of product which all together can describe the entire life cycle of products. However, as this standard is newly born and developing these data models are expensive and time consuming, so far, no data model for description of cutting tools is developed. In this project we study the STEP parts and protocols to understand how data is stored. We study EXPRESS Modeling language, the language developed as part of the STEP standard which is the official language of data modeling in STEP. And use...

Nonhomogeneous Boundary Value Problems for some Nonlinear Equations with Singular Ø-Laplacian

, M.Sc. Thesis Sharif University of Technology Jannat, Farzaneh (Author) ; Hesaaraki, Mahmoud (Supervisor)

Using Axiomatic Design Approach and Conventional Methods to Optimize Process Planning of Cylindrical Parts in ServoHydraulic Pouya Co

, M.Sc. Thesis Sharif University of Technology Rokh, Hoda (Author) ; Houshmang, Mahmoud (Supervisor)

Abstract

Decision making is one of the most critical issues in engineering field. The Axiomatic Design is recently known as one of the most robust tools for decision making task. Axiomatic design is a engineering theory that provides a systematic framework for decision making using two axioms. These two axioms called Independence and Information axioms are both used to do the task.In this thesis, the information axiom is used to select the best machine (operation) for manufacturing cylindrical parts. To do that, three criteria including surface roughness, dimensional accuracy and cost have been chosen.Finally a comparison to the result of this methodology and the result of Analytical Hierarchy...

Using Data Mining in Production Information Systems

, M.Sc. Thesis Sharif University of Technology Alishahi, Mohammad (Author) ; Hooshmand, Mahmoud (Supervisor)

Abstract

Nowadays, because of high volume and growth of data in industrial organizations and productive factories, registration and storing of data have forgotten manual and tradition styles for which using automation and mechanized machinery and systems has been a necessary task. In order to reach to this revolution, need to some tools, facilities and methods which can fulfill this requirement is felt strongly. Therefore, high volume of data is considered as an advantage because based on precise analysis it is possible to make logical management decisions with less risk. During last years, statistical and numerical methods and simulation were used to discover knowledge and information when one of...

Existence and Uniqueness of Solution for Two Free Boundary Problems Modelling Tumor Growth

, M.Sc. Thesis Sharif University of Technology Esmaili, Sakine (Author) ; Hesaaraki, Mahmoud (Supervisor)

Abstract

This thesis is based on articles [18,15]. Zhao [18] has studied a free boundary problem modeling the growth of tumors with drug application. In this model live cells are two kindes: proliferative cells and quiescent cells. This model consists of two nonlinear second-order parabolic equations describing the diﬀusion of nutrient and drug concentration, and three nonlinear ﬁrst-order hyperbolic equations describing the evolution of proliferative cells, quiescent cells and dead cells. He has proved that this free boundary problem has a unique global solution. Tao and Chen [15] have studied another free boundary problem modelling the growth of an avascular tumour with drug application. The...

Integration of Design and Manufacturing Systems Using Neutral Data Structure

, Ph.D. Dissertation Sharif University of Technology Mokhtar, Alireza (Author) ; Hooshmand, Mahmoud (Supervisor)

Abstract

In competitive environment of quick market changes, developing an interoperable manufacturing system is a necessity. Process planning as a connection link between design and manufacturing, has never been able to integrate these up/down stream activities and in spite of employing computer systems, CAPP’s information has been managed in an isolated manner. To realize interoperability, the exchange of part and product data must be independent of their platforms. There are two basic approaches for this purpose: i) Utilizing interface and ii) Utilizing neutral formats. STEP (Standard for the Exchange of Product data) plays a significant role as a neutral data model to integrate design,...

Design and Implementation of a Tunable Frequency Channelizer on FPGA

, M.Sc. Thesis Sharif University of Technology Safaeian, Ramin (Author) ; Tabandeh, Mahmoud (Supervisor)

Abstract

Nowdays, many of communication systems working together. The fist part of each communication system is related to separating a desired part of system input signal. This is called channelisation. Channelization is a process where single, few, or all channels from a certain frequency band are separated for further processing. The separation of single channel is usually done by down-conversion followed by filtering and optional sample-rate conversion. A straightforward implementation for multi channel sepration, which is also the traditional implementation of wideband channelizer, is to simply use a single-channel channelizer for each channel. A few applications require that an input signal be...

A Novel System to Enable Interoperability Among Distributed CAM Software Packages and CNC Machining Post Processors

, M.Sc. Thesis Sharif University of Technology Hosseini, Ali (Author) ; Houshmand, Mahmoud (Supervisor)

Abstract

Today’s businesses strategies are changing from traditional point of view to globalization and distributed enterprise. Companies have to consider flexibility in term of quantity and variety. They have to manage and organize the product development chain where low cost resources are available. Therefore, enterprises and companies should facilitate the flow of information and increase the interoperability between distributed agents. The main information flow occurs in CAD/CAM/CNC chain. Information flow at the end of the chain has always been the main obstacle to enable interoperability. Old Standards for programming CNC machine tools are the main problem to exchange data and facilitate...