Modified carrageenan. 5. Preparation, swelling behavior, salt- and pH-sensitivity of partially hydrolyzed crosslinked carrageenan-graft-polymethacrylamide superabsorbent hydrogel [electronic resource]

, Article Polymers for Advanced Technologies ; Volume 15, Issue 11, pages 645–653, November 2004 Pourjavadi, A. (Ali) ; Sadeghi, M ; Hosseinzadeh, H

Abstract

The polysaccharide, kappa-carrageenan (κC) was chemically modified to achieve a novel superabsorbent hydrogel via graft copolymerization of methacrylamide (MAM) onto the substrate followed by alkaline hydrolysis. Ammonium persulfate (APS) and N,N′-methylene bisacrylamide (MBA) were used as a free-radical initiator and a crosslinker, respectively. The saponification reaction was carried out using sodium hydroxide aqueous solution. Either κC-g-PMAM or hydrolyzed κC-g-PMAM (PMAM: polymethacrylamide) was characterized by FT-IR spectroscopy. The effect of grafting variables (i.e. concentration of MBA, MAM, and APS) and alkaline hydrolysis conditions (i.e. NaOH concentration, hydrolysis time and...

Modified carrageenan. 4. Synthesis and swelling behavior of crosslinked kappa C-g-AMPS superabsorbent hydrogel with antisalt and pH-responsiveness properties [electronic resource]

, Article Journal of Applied Polymer Science ; Vol.98, No.1, 255-263, 2005 Pourjavadi, A. (Ali) ; Hosseinzadeh, H ; Mazidi, R

Abstract

To synthesize a novel biopolymer-based superabsorbent hydrogel, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) was grafted onto kappa-carrageenan (KC) backbones. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator, N,N,N',N'-tetramethyl ethylenediamine (TMEDA) as an accelerator, and N,N'-methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for KC-g-AMPS formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The affecting variables on swelling capacity, i.e., the initiator, the crosslinker, and the monomer concentration, as well as reaction temperature,...

Partially hydrolyzed crosslinked alginate-graft-polymethacrylamide as a novel biopolymer-based superabsorbent hydrogel having pH-responsive Properties [electronic resource]

, Article Macromolecular Research ; January 2005, Volume 13, Issue 1, pp 45-53 Pourjavadi, A. (Ali) ; Aminfazl, M. S ; Hosseinzadeh, H

Abstract

In this study, a series of highly swelling hydrogels based on sodium alginate (NaAlg) and polymethacrylamide (PMAM) was prepared through free radical polymerization. The graft copolymerization reaction was performed in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator andN,N′-methylenebisacrylamide (MBA) as a crosslinker. The crosslinked graft copolymer, alginate-graft-polymethacrylamide (Alg-g-PMAM), was then partially hydrolyzed by NaOH solution to yield a hydrogel, hydrolyzed alginate-graft-polymethacrylamide (H-Alg-g-PMAM). During alkaline hydrolysis, the carboxamide groups of Alg-g-PMAM were converted into hydrophilic carboxylate anions. Either the...

ECG beat classification based on a cross-distance analysis

, Article 6th International Symposium on Signal Processing and Its Applications, ISSPA 2001, Kuala Lumpur, 13 August 2001 through 16 August 2001 ; Volume 1 , 2001 , Pages 234-237 ; 0780367030 (ISBN); 9780780367036 (ISBN) Shahram, M ; Nayebi, K ; Sharif University of Technology

IEEE Computer Society 2001

Abstract

This paper presents a multi-stage algorithm for QRS complex classification into normal and abnormal categories using an unsupervised sequential beat clustering and a cross-distance analysis algorithm. After the sequential beat clustering, a search algorithm based on relative similarity of created classes is used to detect the main normal class. Then other classes are labeled based on a distance measurement from the main normal class. Evaluated results on the MIT-BIH ECG database exhibits an error rate less than 1% for normal and abnormal discrimination and 0.2% for clustering of 15 types of arrhythmia existing on the MIT-BIH database. © 2001 IEEE

Material Ordering in a Deterministic Time-Phased Demand Environment with All-Units Discount in Purchasing

, Ph.D. Dissertation Sharif University of Technology Mirmohammadi, Hamid (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

More than 60% of sales account for materials, and so the roles and responsibilities of the material managers have been recognized as more important within a firm or in a large scale project than before. However, in many purchasing situations, different considerations conflict with one another. In these situations material planning plays an essential role in the total cost minimization process. Here, the optimal material ordering policy for an item in a deterministic time-phased demand environment with all-units discount in purchasing is considered. Based on proven properties of the optimal order policy, a tree search procedure is designed to construct sequences of orders in the optimal...

Feasibility study of Foam Concrete production

, M.Sc. Thesis Sharif University of Technology Koohestani, Mostafa (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

Foam concrete is a new covering layer that can be used for several purposes in civil constructions and because of its unique physical specifications, produces a light concrete in which is isolated against thermal conductivity ,with required strength and favorite quality.This cover is made of cement , sand ,water and foam(chemical substance that produces foam) . The foam is mixed with water in a special machine (mixer) with a high speed centrifugal rotation and produces very small stable bubbles called foam. While cement and sand are mixed in special mixer, makes a fluent concrete that can be used in place, metallic or plastic molds. After dehydration, in accordance with percentage of...

Identify and Assessment of Project's Risks Based on PMBOK's Standard - Case Study: Construct an Aquaculture Site in Abadan

, M.Sc. Thesis Sharif University of Technology Kamaei, Amin (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

Risk is an uncertain event or condition that, if it occurs, has a positive or negative effect on a project’s objectives. Identification and assessment of risk in a measurable way are so important for project managers to decide better. This thesis studies how to identify and assess the project’s risks in Fishery industry based on the Project management body of knowledge (PMBOK 2008) as a global standard. Constructing an aquaculture site in Abadan city has some risks which are identified in the first steps of the study and in the following steps these risks will be prioritized by the use of qualitative analysis and figured out which risks have major effects on projects objectives. In last step...

Optimization Shop Area in Construction Projrect

, M.Sc. Thesis Sharif University of Technology Raissi, Asghar (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

Resource investment problem is one of problems in project scheduling which concerns with gaining minimum cost for accomplishing a project in a given time. Tardiness permitted with penalty cost makes this problem close to real world. This dissertation studied constraint of resources by restricted resources and tried to gain optimal level of restricted resource and middle resources start and finish time. This problem also permits tardiness with penalty cost. In construction projects, beside renewable and Non-renewable resources, there are workshops in which part of the work to carry out an activity, is done. These workshops include welding workshops and forming workshops in piping projects,...

A Project Portfolio Selection Method for Iranian Private Construction Companies

, M.Sc. Thesis Sharif University of Technology Hamdieh, Hosna (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

The construction industry is one of the main industries in Iran, and plays a fundamental role in Iran’s economy, because construction has impact on most of other industries by its vast value chain. Selecting right sets of projects is considerably crucial for construction organizations to successfully achieve their competitive advantages and corporate strategies. Due to limited resources and dynamic changes in Iran’s construction business environment, this kind of selection is quite challenging for construction organizations. Beside’s over hundreds of selection tools, techniques, and complex selection frameworks were developed or recommended by academics and practitioners to smooth the...

Scheduling on Parallel Machines with Preemption and Transportation Delays using a Particle Swarm Optimization (PSO)-Based Algorithm

, M.Sc. Thesis Sharif University of Technology Shams, Hesam (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

This research deals with the problem of scheduling independent preemptive jobs on identical parallel machines, to minimize the total completion time (makespan). The transportation of an interrupted job from a machine to another machine requires considering a constant transportation delay i.e., Pm|prmp(delay)| Cmax. This delay is called transportation delay. We propose a Mixed Integer Linear Programming formulation for the research problem in case of two machines i.e., P2|prmp(delay)| Cmax. Since the research problem is shown to be NP-hard, a particle swarm optimization (PSO) algorithm is applied to solve the problem approximately. Based on the frequency of using local search procedure, three...

Designing an Algorithm for the Resource Investment Problem Considering Calendar

, M.Sc. Thesis Sharif University of Technology Parvizi, Saeed (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

Project scheduling problems can be divided into different categories which one of the most important of them is resource investment problem. In this problem we are faced with a time limit for completion but resources are available unlimitedly and can be allocated to the project by specific cost. One of the most important constraints in real problems is the times that resources are available. In this research, resource investment problem considering calendar for resources has been investigated. Since resource investment problem is NP-Hard, after a brief overview of the different solutions, we used genetic algorithm to solve this problem. For this purpose, after determining chromosome...

Presentation of a Model and Solving the Problem of Project Portfolio Selection Based on Project Scheduling using Two-Level NSGAII

, M.Sc. Thesis Sharif University of Technology Jafari, Hossein (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

This project aims to study a situation in which several projects must be selected. The decision makers should select a subset of these projects taking into account the limitation of resources and scheduling. Project selection models generally do not consider schedule of project activities as part of selection process. On the other hand, except the cases where only one project is under process in each period, prioritizing the selected projects is not optimal not considering their scheduling. Projects scheduling in project activities level may increase the complexity of decision making for portfolio selection and expand the area of search for selection of projects portfolio. Therefore, all the...

Optimization of Process Plant Layout and Pipe Routing

, M.Sc. Thesis Sharif University of Technology Mehrizi, Rahil (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

Process plants such as refineries and petrochemical plants are complex facilities consisting of equipment, piping systems, instruments, electrical systems, computers, and control systems. Process units design is mostly based on designer`s experience and design general criteria and standards. Using mathematical methods to optimize the design may have an effective role in cost reduction and it would give the designer some general view in case that the exact design is not applicable.
Optimization of Process units is described in this study. This optimization includes the exact location of each equipment, nozzle, pipe rack and also pipe route layouts. Mixed integer linear programming (MILP)...

Exact and Metaheuristic Solution of Multi-skilled Project Scheduling Problem Considering Learning and Forgetting Effects on the Performance of Project Members

, M.Sc. Thesis Sharif University of Technology Mehmanchi, Erfan (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

The multi-mode resource-constrained project scheduling problem is one of the most complex and most widely used problems in the project scheduling knowledge area and operations research science. Recently, a new type of this problem which is called multi-skilled project scheduling problem has been introduced in the literature. The aim of MSPSP is to schedule the activities regarding the precedence relationships and multi-skilled human resource constraints in such a way that the need of each activity to a subset of skills should be met by the qualified employees. In this thesis, in addition to taking the constraints of the standard problem into account, we consider a state in which the...

Linear-Differential Cryptanalysis of Word-Reduced Variants of Cubehash

, M.Sc. Thesis Sharif University of Technology Javid, Sahand (Author) ; Khazaei, Shahram (Supervisor)

Abstract

In this thesis, first we will have a brief review on hash functions and related concepts.Then, we will descibe the hash function, Cubehash, which is one of the competitors in the competition held by NIST for selecting SHA-3 standard. Next, we will describe an attack based on linearization of differential paths in hash functions and apply this attack on Cubehash. At the end, we will discuss the results of this attack on Cubehash

Optimization of Construction Workshop Activities in A Piping Process

, M.Sc. Thesis Sharif University of Technology Safarzadeh, Soroush (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

Piping process is the most important part of industries projects which pay attention to construction and installation of industrial pipelines and its facilities. In the meantime, due to increasing demand of industrial units to construction and development projects, planing and scheduling the piping is necessary. We review and discuss various aspects of the piping process, optimization process and the related scheduling literature that is called Flexible Job Shop Scheduling Problem. Then, to solve the problem, considering the real world assumptions, a mathematical model, is developed and a heuristic algorithm is introduced. Also, in order to determine an appropriate bound for the optimal...

Measure the Project Progress with Standard Weight Factors and Calculate the Project Performance

, M.Sc. Thesis Sharif University of Technology Yarmohammadi, Ali (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

One of the methods that we used today to manage project are calculating project progress. By which we can calculate the actual progress of project by comparison the actual plan with the schedule plan. If the actual progress,measured with less error, then the control of project done with high accuracy.Project progress are calculated in control account. For this reason, if the number of control account increased, the accuracy of the calculation increased and on the other hand whatever this control account increase the amount of time used to collect information also increases. In this study, we are looking to create mathematical model that in addition increases the accuracy of measurement,also...

Privacy Preserving Data Mining

, M.Sc. Thesis Sharif University of Technology Javar, Zahra (Author) ; khazaei, Shahram (Supervisor)

Abstract

Increasing use of new data technologies have made data collection possible in large scales. Practicallity of the data relies upon the extraction of meaningful knowledge.Data mining is a solution to this problem. One of the new areas in data mining is consideration of the concern of privacy alongside the usefulness of the mining results.Main goal of privacy preserving data mining is to develop data mining models which only extract the useful knowledge. In recent years, many researches have been done in this area. Since the literature and notation of these published works vary, a survey would help to better understand these concepts. This thesis tries to explain, analyse,unify and categorize...

Risk Action Plans’ Cost Optimization by Considering Risks’ Interdependency

, M.Sc. Thesis Sharif University of Technology Roshan, Razieh (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

Risk management, one of the knowledge areas in project management, plays a key role in the success of projects in today’s unstable situation. The massive cost reduction achieved by risk management can manifest its importance even more in huge construction projects in gas and oil industry such as developments of power plants and petrochemical complexes. In this research, the effect of considering the correlation between risks and consequently the effect of risk action plans on other risks in their execution cost reductions has been demonstrated. A questionnaire has been designed, many experts have been interviewed, and using statistical methods, the risks’ interdependencies have been...

Cryptographic Hash Functions from Expander Graphs

, M.Sc. Thesis Sharif University of Technology Zarei, Afshin (Author) ; khazaei, Shahram (Supervisor)

Abstract

A hash function maps efficiently every finite length string to a fixed one. The output represents the entire content of the input, similar to digital fingerprint of input text. In order to be able to use a hash function in cryptography, it should be hard to find two distinct inputs with the same output (collision), because finding a collision in hash functions leads to malicious attacks on many security systems.We say a hash function is provably collision resistant, if finding a collision can be reduced to the known hard problems. Family of MD hash functions are one of the most famous applied hash functions which are considerably used in industrial applications. However, they are not...