Sharif Digital Repository

Today's world needs new methods to deal with and analyze the ever-increasingly generated data streams. Two of the most challenging aspects of data streams are (i) concept drift, i.e. evolution of data stream over time, which requires the ability to make timely decisions against the high speed of receiving new data; (ii) limited memory storage and the impracticality of using memory due to the large amount of data. Clustering is one of the common methods to process data streams. In this paper, we propose a novel, fully-online, density-based method for clustering evolving data streams. In recent years, a number of methods have been proposed, which also have the ability to cluster data streams.... 

Vigorous debates have taken place within and between many countries about regulatory policy regimes covering the assessment and approval of genetically modified (GM) crops. In Iran, a very vigorous and hotly contested policy debate concerning legislation covering GM crops occurred between 2004 and 2009, but it was confined within government circles with almost no public discussion. This paper analyses the Iranian policy-making process in the period 2006-9. It explains how and why a stalemate arose in disputes between ministries and departments. The chosen analytical framework draws mainly on the regulation of technological risks and the analysis of public policy-making. It deploys the... 

In this study, a new passive method suitable for geolocating low probability of intercept (LPI) radars is introduced. The method uses two electronic support receivers placed on a fast moving platform (e.g., an airplane or a satellite). The proposed method has a high processing gain, which makes it highly suitable for very weak LPI signals. The method processing gain was analytically derived and illustrated with simulation to determine if the proposed method can detect LPI radars in much lower SNRs compared to regular time-frequency LPI detection methods. Also, the resolution of the proposed method in both range and cross-range directions in radar location finding was analyzed. The results... 

The process of preparing and enacting a bio1safety law in Iran lasted more than a decade. This paper examines the process of biosafety policy-making in Iran in relation to the Cartagena Protocol on Biosafety (CPB) and to domestic Iranian factors. While some scholars argued that the CPB would be influential in developing countries, our findings indicate that it was not particularly important in Iranian biosafety legislation. This paper outlines the internal Iranian political processes, which initially envisaged a very precautionary approach, but which concluded with a biosafety law designed to promote the adoption of these technologies. Reference will be made to the changing influence of... 

In this paper, we propose a novel density-grid-based method for clustering k-dimensional data. KIDS, an acronym for K-dimensional Ink Drop Spread, detects densely-connected pieces of data in k-dimensional grids. It enables one to simultaneously exploit the advantages of fuzzy logic, as well as both density-based and grid-based clustering. In the proposed method, the k-dimensional data space is divided into different cells. Input data records are mapped to the cells. The data points are then spread in the k-dimensional cells, just like what happens to ink drops in water. So the cells adjacent to the data cells also represent the data. Eventually, the impacts of all data grid cells are... 

Maintaining of concrete gravity dams in good conditions as one of the important infrastructures is significant concern for dam owners. These dams should able to continue their function after a disaster such as earthquake. But most of them are aged dams with some located near faults. Indeed, there are some concerns regarding the performance of these dams under the effect of seismic loads. In recent years some criteria about linear performance of these dams have been developed. But the same cannot be said about nonlinear behavior of these dams, which seem to lack well-developed criteria. In this paper we shall try to illustrate seismic fragility curves for concrete gravity dams by using... 

The evolution of innovation system literature is scrutinized to delineate the conceptual trends over the past 30 years. We applied the Sigma index which is supposed to include not only the frontier contributions in the field but also the intellectual bases conveying transformative concepts. Our examination shows that after the establishment of the National Innovation System (NIS)as a principal framework, Regional IS literature emerged as a main branch during the period of 2002–2007, while Technological IS developed as the second main branch from 2007 to 2012. Surprisingly, Sectoral IS has not yet generated a separate constellation, whereas the period after 2012 mainly witnessed the emergence... 

Social enterprises are organisations comprised of two conflicting logics: social and commercial. However, simultaneous commitment to both logics often leads to tensions, making social enterprises fragile organisations at the risk of mission drift. The extant literature on hybridity highlights two important overall strategies–integration and differentiation - for managing tensions. However, integration or differentiation alone can create additional problems, which is especially true in the case of differentiation, creating a situation comparable to black and white, with a salient faultline and heated conflicts. In this inductive qualitative case study, responding to the recent call in the... 

This study draws a historical picture of conceptual linkages of innovation systems (IS) and global value chains (GVC). We used a co-citation technique to map the evolution of these two fields since 1990. We highlighted the connecting nodes over the past three decades. The first decade witnessed a connection between national innovation systems (NIS) and GVC, mediated by regional studies related to industrial clusters and district-based innovation. The tradeoff between tacit sticky local and codified transferable global knowledge and innovation and learning's importance in upgrading in GVC generated two new routes in the second decade. In the last decade, although these routes are retained,... 

To enhance impedance bandwidth of spherical Microstrip antenna with annular-circular patch, an air gap layer between antenna ground and substrate layer has been employed. The principle purpose of this work is to consider the effect of such layer on the impedance bandwidth and, consequently, antenna performance. To provide circular polarization, we have applied anisotropic uniaxial crystal as a substrate in spherical Microstrip antenna. Evaluating the impact of air gap layer on radiation pattern of spherical Microstrip antenna with annular-circular patch via CST program is the other goal of this correspondence for three types of substrate materials, anisotropic negative uniaxial crystal,... 

This manuscript presents a framework to develop vector error correction (VEC) models applicable to forecasting the short- and long-run movements of the average hourly earnings of construction labor, which is an essential predictor of the construction labor costs. These models characterize the relationship between average hourly earnings and a set of explanatory variables. The framework is applied to develop VEC forecasting models for the average hourly earnings of construction labor in the USA based on the identified variables that govern its movements, such as Global Energy Price Index, Gross Domestic Product, and Personal Consumption Expenditures. More than 150 candidate VEC models were... 

Niosomes are vesicles formed mostly by nonionic surfactant and cholesterol incorporation as an excipient. The drug entrapment efficiency of niosomal vesicles is particularly important and depends on many parameters. Changing the effective parameters to have maximum entrapment efficiency in the laboratory is time-consuming and costly. In this study, a machine learning framework was proposed to address these problems. In order to find the most critical parameter affecting the entrapment efficiency and its optimal value in a specific experiment, data were first extracted from articles of the last decade using keywords of niosome and thin-film hydration method. Then, deep neural network (DNN),... 

Objectives: The purpose of this paper is to describe the development and evaluation of a new medial linkage reciprocating gait orthosis (MLRGO) that incorporates a reciprocal mechanism and is sensitive to pelvic motion to potentially assist paraplegic patients to walk and provide functional independence. Case description and methods: The new orthosis was constructed and tested by a 20-year-old female paraplegic subject with transverse myelitis at T10 level, who was 4 years post injury and had also been an isocentric reciprocating gait orthosis (IRGO) user for 2 years. She received gait training for 12 weeks before undertaking gait analysis, and also completed a questionnaire that was... 

In most image retrieval systems, images include various high-level semantics, called tags or annotations. Virtually all the state-of-the-art image annotation methods that handle imbalanced labeling are search-based techniques which are time-consuming. In this paper, a novel coupled dictionary learning approach is proposed to learn a limited number of visual prototypes and their corresponding semantics simultaneously. This approach leads to a real-time image annotation procedure. Another contribution of this paper is that utilizes a marginalized loss function instead of the squared loss function that is inappropriate for image annotation with imbalanced labels. We have employed a marginalized... 

The goal of robust parameter estimation is developing a model which can properly fit to data. Parameter estimation of a geometric model, in presence of noise and error, is an important step in many image processing and computer vision applications. As the random sample consensus (RANSAC) algorithm is one of the most well-known algorithms in this field, there have been several attempts to improve its performance. In this paper, after giving a short review on existing methods, a robust and efficient method that detects the gross outliers to increase the inlier to outlier ratio in a reduced set of corresponding image points is proposed. It has a new hypothesis and verification scheme which... 

The goal of robust parameter estimation is developing a model which can properly fit to data. Parameter estimation of a geometric model, in presence of noise and error, is an important step in many image processing and computer vision applications. As the random sample consensus (RANSAC) algorithm is one of the most well-known algorithms in this field, there have been several attempts to improve its performance. In this paper, after giving a short review on existing methods, a robust and efficient method that detects the gross outliers to increase the inlier to outlier ratio in a reduced set of corresponding image points is proposed. It has a new hypothesis and verification scheme which... 

The pharmaceutical industry is facing enormous challenges due to high drug attribution rates. For the past decades, novel methods have been developed for safety and efficacy testing, as well as for improving early development stages. In vitro screening methods for drug-receptor binding are considered to be good alternatives for decreasing costs in the identification of drug candidates. However, these methods require lengthy and troublesome labeling steps. Biosensors hold great promise due to the fact that label-free detection schemes can be designed in an easy and low-cost manner. In this paper, for the first time in the literature, we aimed to compare the potential of label-free optical and... 

Laser assisted machining (LAM) is a promising technology for machining hard to cut materials. In most experimental cases, LAM is undergone in two stages; first, the temperature at the material removal point (Tmr) is tuned by adjusting laser parameters and next, the cutting tool is engaged. Introduction of highly localized heat energy to the workpiece makes the modeling of this process very complicated. Hence, an analytical model for the first stage of the process - rather than multiple experiments or FE modelling - would be beneficial. This article presents an analytical solution to the transient, temperature field in a rotating cylinder subject to a localized laser heat source. The... 

Modeling of the laser-assisted machining (LAM) process requires an accurate estimate of the surface absorption coefficient. In addition to the laser type and material properties, this parameter is dependent on the state of the process in terms of surface quality, texture, oxidation state, and temperature change during the machining process. In this article, two methods are presented for calculating this coefficient based on the surface temperature obtained from measurement by a pyrometer and an analytical model of the process. In the first method, the pyrometer is fixed on a lathe bed while in the second method, a co-moving pyrometer is used. Temperature measurements in both methods are...