Sharif Digital Repository

Agile software development methodologies have been greeted with enthusiasm by many software developers, yet their widespread adoption has also resulted in closer examination of their strengths and weaknesses. While analyses and evaluations abound, the need still remains for an objective and systematic appraisal of Agile processes specifically aimed at defining strategies for their improvement. We provide a review of the strengths and weaknesses identified in Agile processes, based on which a Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis of the processes is performed. We suggest this type of analysis as a useful tool for highlighting and addressing the problem issues in Agile... 

Login section is one of the most important parts of each system. This section is usually achieved through a username-password entering method. Since in these methods, user's security relays on how strong the password is, accordingly it is important how the password is provided. There are lots of different approaches in this regard which can be categorized in two main subgroups: Static and Dynamic passwords. Dynamic passwords are taking the lead in password generation context, since static password approaches suffer from some disadvantages like their vulnerability to easily get cracked, high possibility of oblivion and etc. In this paper, we introduce a novel dynamic password providing idea,... 

In this article, a new method for solving multidimensional population balance (PB) equations for agglomeration is presented. First, discretized 2-dimensional PB (DPB) is derived and by applying probability approach, this method is extended to n-dimensional PB. The discretization of size intervals is in the form of v(j) = 2j-i v(i) and the volume based PB is used. Because of conservative nature of volume, all internal coordinates are converted to some independent volumes. A simple and clear procedure for solving multidimensional PB is proposed using probability concept. In addition, various types of birth and death mechanisms involved in PB are analyzed separately. Moreover, results of... 

The integrity of decentralized controllers with integral action, with respect to loop failures, has been researched relatively well. Important results have been found, with respect to the Relative Gain Array (RGA). However, less has been done on the treatment of the integrity of uncertain systems. This paper builds on the more-recent progress on the analysis of uncertain systems and presents new conditions for the integrity of closed-loop systems. The developed Integral Controllable (IC), Integral Controllable with Integrity (ICI), and Decentralized Integral Controllability (DIC) conditions are derived using a model of uncertainties that allows both unstructured and structured independent... 

In transition from concept design to detail design, designers and engineers need to find specific materials to optimize performance of the systems. The large number of materials and the wide range of manufacturing processes cause engineers always to seek new materials selection methods. In this research work a new method so called QFD method, which employs materials indices, is introduced. The method enjoys a combination of Ashby's materials selection concepts with the Quality Function Deployment (QFD) tool. The QFD method, which is modified here to fit the materials selection field, provides the designer with the required weighting factors for the material indices. Incorporation of House of... 

In many cases, multiple-fault diagnosis of plant-wide systems based on steady-state data is impossible. To solve this problem, a new diagnosis strategy based on neural networks has been proposed. In the suggested framework, the neural network is used as the diagnoser trained by a hybrid set of steady and dynamic characteristic data of the system. The dynamic characteristic data include overshoot and undershoot values of measured variables and their corresponding occurrence times. To evaluate its performance, the proposed scheme was used in the diagnosis of the concurrent faults of the Tennessee Eastman (TE) process. Various combinations of concurrent faults were considered in this... 

Side weirs are widely used for level control and flow regulation in hydraulic engineering applications such as irrigation, land drainage, and sewer systems. These hydraulic structures allow a part of the flow to spill laterally when the surface of the flow in the main channel rises above the weir crest. The supercritical flow over a side-weir is a typical case of spatially varied flow with decreasing discharge. This study is aimed at investigating the variations of specific energy along the side-weir using experimental results. Some diagrams have been presented in terms of dimensionless ratio of diverted discharge to total discharge. These diagrams which can be used in the design of side... 

Labyrinth side weir is one type of weirs, which can be used when the length of opening is limited. One of the advantages of labyrinth side weir is to increase the effective length of weir perpendicular to the flow and, therefore, diverting more discharge with the same flow depth and weir geometry (opening and height). Discharge coefficient should be determined to investigate the weir performance and estimate the discharge passing over the weir. In this paper, hydraulic performance of labyrinth side weir with asymmetric geometry has been experimentally studied. The change to the geometry of ordinary labyrinth side weirs causes an increase in the effectiveness of the length of weir as being... 

Fiber/matrix debonding at the free surface of unidirectional composites deteriorates their performance and ultimately reduces the working life of these materials. Identifying the source, controlling the propagation and elimination of the damages has been the subject of many research attempts. The results show that the singular radial thermal residual stress at the fiber/matrix interface on the free surface of composites is the main reason for initiation of the debonding. Also, it has been experimentally and numerically proven that a thin layer of matrix-like cover on the free surface could highly help in elimination and/or reduction of the damage. However, the results were limited to the... 

Due to the enlargement and complexity of software systems and the need for maintenance and update, success of systems depends strongly on their architecture. Software architecture has been a key element in software development process in two past decades. Therefore, choosing the correct architecture is a critical issue in software engineering domain, with respect to the extremely extension of architecturedriven designs. Moreover, software architecture selection is a multi-criteria decision-making problem in which different goals and objectives should be considered. In this paper, a Decision Support System (DSS) has been designed which provides software architects with more precise and... 

Governments in developing countries have invested in institutions of higher learning in order to develop homegrown, high technology products. Among these, the National University of Malaysia (Universiti Kebangsaan Malaysia), recognized as a Research University, is actively involved in projects related to medical technology through its various faculties. The net result of these activities is impressing from the point of view of patents and publications, but unfortunately not yet in terms of commercialization. This paper starts by presenting the main obstacles towards the objective of bringing a laboratory prototype to the market in the context of Malaysia. Then, a framework is presented... 

Development of technology has made possible the invention of innovative and modern methods to partially solve the problems caused by traffic congestion through decreasing the need for physical transportation; one such method being telecommuting. Although, research has been conducted to model employees' and employers' attitude towards telecommuting at micro levels, few predictions have been reported regarding its aggregate demand at the macro level of a city, generally because of the complexity and multi-dimensionality of the subject. In this paper, an approach for the estimation of potential aggregate telecommuting demand is proposed to partly fill the gap in the literature; and applied for... 

Estimating Origin-Destination matrix, named O-D matrix or ODM, is an important issue in transportation planning. Due to need to survey movements on the network, estimating ODM is usually considered as a high-cost measure in transportation planning. In this research work, a two-stage procedure, including solving routing problem and minimizing the difference between observed and estimated traffic volumes on the network, has been developed to estimate the O-D matrix elements. At the first stage, routing problem is solved to determine paths while in the second stage an absolute error function has been defined to determine the number of trips from each origin to destination pairs. The procedure... 

The need for service passenger cars, like taxies and governmental vehicles, to work in central Tehran that can produce less emission has been the main drive behind this research. A series hybrid pneumatic vehicle based on Iran manufactured Samand Passenger car was developed using commercially available components. The idea is to use as much standard parts as possible to reduce the development and manufacturing costs of the developed hybrid car. The vehicle space and weight limitations and the fixed geometry have been the main constraint in adoption of the components. The calculations show that the designed vehicle succeeds to satisfy the requirements set by driving cycle, but requires... 

This article studies effects of webpage layout in an online retailer on buyer behavior towards new products and is a sequel to a study performed by authors in department stores. Webpage layout -in terms of parameters which influence buyer behavior- is formulated by two variables; pattern of prices and pattern of popularity. A novel method based on above-mentioned study, has been developed to measure these two factors, so that they can be compared against retailer sales statistics. Investigating this relationship helps both online retailers and marketing agents to better understand effect of webpage layout in promoting a newly developed product. Results show that correlation between price... 

This article studies effects of store layout in a department store on buyer behavior towards new products. Shelf layout -in terms of parameters which influence buyer behavior- is formulated by two variables; pattern of prices and pattern of popularity. A novel method based on previous works of authors has been developed to measure these two factors, so that they can be compared against shares of department sales statistics. Investigating this relationship helps both retailers and marketing agents to better understand effect of shelf layout in promoting a newly developed product. Results show that correlation between price difference and department share is strong. There is also a weaker... 

Tethered airborne wind energy systems are among emerging renewable energy technologies in recent years. These systems can harness greater power densities at higher altitudes with lower costs of installation and energy production in comparison with those from conventional ground-based energy harnessing technologies. A Buoyant Airborne Turbine (BAT) as a flying aerostat has a horizontal axis wind turbine within its shell and can elevate up to 600m. There are a number of pertinent parameters such as BAT configurations/component dimensions or its aerodynamic characteristics that impact the system total power performance. Identifying the optimum values of these parameters by conducting... 

Considering their special features and numerous applications, sensor networks are noticed so much nowadays. A sub-group of these applications is underwater sensor networks, which encounter some challenges like reliable transportation, routing, MAC, positioning, limited bandwidth, high and variable propagation delay, defective underwater channels and low battery capacity. Acoustic technologies are a particular technology which can make strong underwater communications for Civilian and military applications. These networks are used in oceans for environmental monitoring, under sea discovery, unexpected events prevention, ships assisting, tactical monitoring and naval mine detection, but there... 

Small and medium break LOCA accidents at low pressure and under low velocity conditions have been studied in the TTL-2 Thermo-hydraulic Test Loop, experimentally. TTL-2 is a thermal hydraulic test facility which is designed and constructed in NSTRI to study thermal hydraulic parameters under normal operational and accident conditions of nuclear research reactors. A nodalization has been developed for the TTL-2 and experimental results have been compared with RELAP5/MOD3.2 results. The considered accidents are a 25% and 50% cold leg break without emergency core cooling systems. Results show good agreement between experiments and RELAP5/MOD3.2 results. This research provides experimental data... 

Information systems are expected to satisfy increasingly ambitious requirements, while reducing time-to-market has become a primary objective. This trend has necessitated the advent of development approaches that are better equipped and flexible enough to cope with modern challenges. Model-Driven Architecture (MDA) and Situational Method Engineering (SME) are approaches addressing this requirement: MDA provides promising means for automating the software process, and revitalizes the role of modeling in software development; SME focuses on project-specific methodology construction, mainly through assembling reusable method fragments (process patterns) retrieved from a method base. We provide...