Sharif Digital Repository

Recent enhancements in computer aided design and manufacturing have made dentistry workflow more effective. Dental products are highly customized and personalized for patients. So, they require manufacturing processes for flexibility and agility and fulfilling requirements like quality, delivery time and cost. Various types of scanners, design software and production devices are used by stakeholders in digital dentistry. Also, other stakeholders such as dentists, dental surgeons and lab technicians work together to respond to patient demands to produce the required products while they are distributed in different geographical locations. This paper introduces a new practical and... 

Dentistry technology has been developed drastically during past two decades and the application of software and automated digital equipment have been proposed to have the most influence. Digital dental workflow includes four phases: scan, design, production planning and production which in each of the phases, the various software packages and digital devices are required. In addition, workflow in dentistry requires intensive cooperation among dentists, dental laboratories, technicians, imaging and production centres. This paper has developed anovel platform for digital dentistry, which facilitates the interoperability among different digital components and improves digital workflow in... 

In recent years, with the growth of software engineering, agile software development methodologies have also grown substantially, replacing plan-driven approaches in many areas. Although prominent agile methodologies are in wide use today, there is no method which is suitable for all situations. It has therefore become essential to apply Situational Method Engineering (SME) approaches to produce agile methodologies that are tailored to fit specific software development situations. Since SME is a complex process, and there is a vast pool of techniques, practices, activities, and processes available for composing agile methodologies, tool support-in the form of Computer Aided Method... 

Nowadays, many second/foreign language (L2) academic writing instruction programs place a high premium on pre-writing strategies. The current study examined the effect of software-supported concept mapping on lexical diversity (LD) of English learners' argumentative essays within a process writing framework. Additionally, the relationship between the learners' LD and their overall writing quality was investigated. To this end, 53 university English as a foreign language (EFL) undergraduates were assigned to a computer-aided concept mapping (CACM) and a traditional outlining condition over a span of seven weeks. The CACM group was instructed through the graphic organizer software... 

The effects of powder particle size on the densification and microstructure of iron powder in the direct laser sintering process were investigated. Iron powders with particle sizes ranging from 10 to 200 μm were used. It was found that the sintered density increases as the laser energy input is increased. There is, however, a saturation level at which higher density cannot be obtained even at very intensive energy input. This saturation density increases as the size of the iron particles decreases. Meanwhile fine powders with narrow particle size distributions have a tendency toward agglomeration, and coarse powders with broad particle size distributions have a tendency toward segregation,... 

A methodology for analysis and synthesis of lowpass sigma-delta (∑Δ) converters is presented in this paper. This method permits the synthesis of ∑Δ modulators employing continuous-time filters from discrete-time topologies. The analysis method is based on the discretization of a continuous-time model and using a discrete simulator, which is more efficient than an analog simulator. In our analysis approach, the influence of the sample and hold block and non-idealities of the feedback DAC can be systematically modeled by discrete-time systems. Finally, a realistic design of a second-order ∑Δ modulator with a compensation of the non-ideal behavior of the DAC is given. Moreover, simulation... 

This article describes an automatic reactor power control system for VVER-1000 reactor and reports simulation analysis results for a typical daily load follow operation. The associated reactor control algorithm is called `mode G' that uses a heavy-worth bank (H-bank) dedicated to axial power shape control and the light-gray banks (G-banks) for reactor power change and reactivity compensation. The simulation results for daily load follow operation in three burnup states of first cycle illustrate that the load follow capability of VVER-1000 reactors using this algorithm will be improved  

Computer-Aided Diagnosis (CAD) systems are widely used for detection of various kinds of abnormalities in mammography images. Masses are one type of these abnormalities which are mostly characterized by their margin and shape. For classification of masses proper features are needed to be extracted. However, the number of well-known features for describing margin is much fewer than geometrical, shape, and textural ones. In addition, most of the existing margin features are highly dependent on segmentation accuracy. In this work, new features for describing margin of masses are presented which can handle inaccuracies in segmentation. These features are obtained from a set of waveforms by... 

In this research, a web-based simulator is developed, which can be used for generating image sequences of moving spermatozoa cells. It can be used for assessment of multiple object tracking algorithms, especially Computer Aided Sperm Analysis (CASA) systems. The developed software has many useful parameters such as blurring images or adding noise and it also gives full control of sperm counts and types. To illustrate performance of the developed simulator, three parameters (spermatozoa population, standard deviation of Gaussian blur filter and noise intensity) have been swept and the results of three different multiple object tracking algorithms were compared as an application of this... 

Lumbar disc diseases are the commonest complaint of Lower Back Pain (LBP). In this paper, a new method for automatic diagnosis of lumbar disc herniation is proposed which is based on clinical Magnetic Resonance Images (MRI) data. We use T2-W sagittal and myelograph images. Our method uses Otsu thresholding method to extract the spinal cord from MR images of Lumbar disc. In the next step, a third-order polynomial is aligned on the extracted spinal cords, and in the end of preprocessing step all the T2-W sagittal images are prepared for extracting disc boundary and labeling. After labeling and extracting a ROI for each disc, intensity and shape features are used for classification. The... 

A finite element analysis of a double layered shell with a circular hole is carried out with the computer aided engineering software Abaqus (Dassault Systèmes, FR). The model proposed has been used to perform a stress analysis on three pipes with different sized hole. Moreover, thermal expansion has been implemented in the testing. For the purpose of the research, the elastic properties of the materials have been considered and the results compared with the ones previously published in literature. The outcome of the investigation will benefit towards the design of optimal and sustainable pipes with circular cut outs  

A new computer-aided diagnosis (CAD) system for detecting malignant melanoma from dermoscopy images based on a fixed grid wavelet network (FGWN) is proposed. This novel approach is unique in at least three ways: (i) the FGWN is a fixed WN which does not require gradient-type algorithms for its construction, (ii) the construction of FGWN is based on a new regressor selection technique: D-optimality orthogonal matching pursuit (DOOMP), and (iii) the entire CAD system relies on the proposed FGWN. These characteristics enhance the integrity and reliability of the results obtained from different stages of automatic melanoma diagnosis. The DOOMP algorithm optimises the network model approximation... 

Acute lymphoblastic leukemia is one of the most common hematologic malignancies among children, caused by uncontrolled growth of leukocytes. Since the main hallmarks of the disease is not specific, a considerable number of patients have been being misdiagnosed. Early diagnosis of the disease is usually made by morphological investigation of leukocytes under microscope. In light of the facts that decrease in cytoplasm-to-nucleus ratio is one of the main indicators of cancerous cells, and an accurate segmentation phase will lead to extraction of representative features, segmentation step is acknowledged as being crucial in design of a computer aided diagnosis (CAD). Previous researches have... 

The Atmospheric Lifetime (ALT) of a compound represents the potential for the atmospheric accumulation of chemicals. Chemicals with a long lifetime are more resistant to natural decomposition and remain in the environment for a longer period. Minimum Ignition Energy (MIE) is one of the most important properties when evaluating hazardous chemicals. Despite the significance of these environment and safety-related properties, currently, there are no group contribution (GC) models that enable their predictive modeling. The present research aims at filling this gap. To this end, experimental data were collected from literature and the GC model parameters were estimated using the weighted... 

The emergence of agile software development methodologies, and the sheer number of the variants introduced, has raised the need for evaluation and comparison efforts, mostly in order to facilitate the selection or engineering of an agile methodology aimed at a specific software development situation. But existing evaluation frameworks and comparison tools do not satisfy all the needs of project managers and method engineers. The principal objectives of this paper are to introduce a fundamental basis for evaluation frameworks that target existing challenges, and also to evaluate existing evaluation frameworks in order to identify their shortcomings. To this aim, we have proposed an evaluation... 

This paper presents a SEU-mitigative placement and route of circuits in the FPGAs which is based on the popular placement and route tool The tool is modified so that during placement and routing, decisions are taken with awareness of SEU-mitigation and no redundancies during the placement and routing are used but the algorithms are based on the SEU avoidance. We have investigated the effect of this tool on several MCNC benchmarks and the results of the placement and routing have been compared to the traditional one. The evaluations of results show that placement and routing can decrease the SEU rate of circuits implemented on FPGAs about 22%. However, it increases critical path delay and...