Sharif Digital Repository

A novel closed form expression is derived for spatial Green's functions of microstrip structures by expanding the spectral Green's function into a Gaussian series. This innovative method is called the Gaussian Green's function (GGF) method due to the Gaussian form in the closed form Green's function representation. The main advantage of the GGF method lies in its precision as well as rapid convergence. To demonstrate the versatility of this method, the current distribution of a microstrip antenna is achieved via the combination of the method of moments (MoM) and GGF method. It is shown that this method can be computationally very efficient with less than 1% error compared to the numerical... 

Sophisticated surgeons are widely indicating the use of surgical robots in order to reject human error, increase precision, and speed. Among well-known robotic mechanisms, parallel robots are broadly more investigated regarding their special characters as higher acceleration, speed, and accuracy, and less weight. Specific surgical procedures confine, and restrict their workspace, while controlling and validating the robots are complicated regarding to their complex dynamic. To this end, in this paper, a 6-DOF robot, with rotary manipulators, is designed and controlled. Addressing nonlinearity of parallel robots, an innovative methodology is formulated to robustly penalize the error of... 

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... 

This study aims to find the differences between national and international relationships in Iran and Switzerland’s Nanoscience research between 2008–2015. The results show significant differences some of which are attributed to the general dichotomy of developed-developing countries like stronger University-Industry-Government relations in Switzerland; but others are not, especially those pertaining to bilateral relations. In summary, the Government-Industry relations in Switzerland are generally closer in this field because the emerging characteristics of Nanoscience call for more state intervention, even in the context of developed countries. Greater Government-University relations in Iran... 

The performance is presented of the reconstruction and identification algorithms for electrons and photons with the CMS experiment at the LHC. The reported results are based on proton-proton collision data collected at a center-of-mass energy of 13 TeV and recorded in 2016-2018, corresponding to an integrated luminosity of 136 fb-1. Results obtained from lead-lead collision data collected at √sNN=5.02 TeV are also presented. Innovative techniques are used to reconstruct the electron and photon signals in the detector and to optimize the energy resolution. Events with electrons and photons in the final state are used to measure the energy resolution and energy scale uncertainty in the... 

Now we are able to offer numerous softwares for mobile phones after the advances in mobile phone industry. Most of these softwares should be bought in order that we can use them. Some of these softwares are sharewares and after buying them you have to insert a serial number given by the manufacturing company in order to activate the software. But the crackers reproduce them illegally by cracking the software. One of the tactics used by crackers for finding the serial number of the softwares is brute force attacks. In this paper a method based on CAPTCHA (Completely Automated Public Turing Test to tell Computer and Humans Apart) is proposed for solving this problem. In this method while... 

In this study, a real-time exible modular modeling approach to simulating the dynamic behavior of gas turbine engines based on nonlinear thermodynamic and dynamic laws is addressed. The introduced model, which is developed in the Matlab-Simulink environment, is an object-oriented high-speed real-time computer model and is capable of simulating the dynamic behavior of a broad group of gas turbine engines due to its modular structure. Moreover, a Kalman lter-based model tuning procedure is applied to decrease the modeling errors. Modeling errors are de ned as the mismatch between simulation results and available experimental data. This tuning procedure is an underdetermined estimation problem,... 

Disease association study is of great importance among various fields of study in bioinformatics. Computational methods happen to be advantageous specifically when experimental approaches fail to obtain accurate results. Haplotypes are believed to be the most responsible biological data for genetic diseases. In this paper, the problem of reconstructing haplotypes from error-containing SNP fragments is discussed For this purpose, two new methods have been proposed by a combination of k-means clustering and particle swarm optimization algorithm. The methods and their implementation results on real biological and simulation datasets are represented which shows that they outperform the methods... 

Traffic assignment problem (TAP) is traditionally defined without side constraints. Although introducing the side constraints into the TAP is used as a way of refining the applied assignment models, it brings some computational difficulties preventing the refined model to be applicable in the real-case problems. In this paper an iterative solution algorithm is developed for TAP with linear side constraints. This method is based on implicitly considering the side constraints by means of adding a dynamic penalty function (DPF) to the link travel times. Each of the iterations of the algorithm is reduced to an unconstrained assignment followed by updating the penalty functions. The unconstraint... 

The purpose of this study is to apply managerial economics and methods of decision analysis to study the optimal pattern of innovation activities for development of new energy technologies in developing countries. For this purpose, a model of energy research and development (R&D) planning is developed and it is then linked to a bottom-up energy-systems model. The set of interlinked models provide a comprehensive analytical tool for assessment of energy technologies and innovation planning taking into account the specific conditions of developing countries. An energy-system model is used as a tool for the assessment and prioritization of new energy technologies. Based on the results of the... 

The paper presents further experiments with an extended version of a comprehensive model for assessment of energy technologies and research and development (R&D) planning to evaluate the impact of innovation programs on development of Iranian electricity-supply system. This analytical instrument is a model of energy R&D resource allocation with an explicit perspective of developing countries which has been linked to a bottom-up energy-systems model. Three emerging electricity generation technologies of solar PV, wind turbine and gas fuel cell are considered in the model and the impact of innovation programs on cost-reducing innovation for them is examined. The main results provided by the... 

This paper presents a hybrid QR decomposition (QRD) design that reduces the number of computations and increases their execution parallelism by using a unique combination of Multi-dimensional Givens rotations, Householder transformations and conventional 2-D Givens rotations. A semi-pipelined semi-iterative architecture is presented for the QRD core, that uses innovative design ideas to develop 2-D, Householder 3-D and 4-D/2-D configurable CORDIC processors, such that they can perform the maximum possible number of vectoring and rotation operations within the given number of cycles, while minimizing gate count and maximizing the resource utilization. Test results for the 0.3 mm 2 QRD chip,... 

Next generation wideband and ultra-wideband radar antenna arrays need efficient true-time delay networks for array control. Following the great interest for optical control of antenna array beam steering, performance analysis of optical beam-formers is a must. In this paper signal to noise ratio and dynamic range of simple optical beamforming structures with components off the shelf are investigated theoretically. Especially the effects of certain power combining components such as arrayed wave guide gratings, broadband passive optical combiners and microwave combiners inspected. It turns up that an efficient microwave combiner would surpass the optical combiners in both SNR and dynamic... 

Organisational commitment is suggested as a remarkable variable in shaping employees’ attitudes toward knowledge management practices. Customer trust in services is established during a long-time relationship with a firm and improves the accuracy of information shared with employees. To put it in other words, customer trust is what a service company needs to maintain its competitive advantage. On the other hand, high employee turnover reflects a substantial loss of knowledge. In the present study, the impact of organisational commitment on employees’ retention, knowledge acquisition, and sharing was examined regarding the moderating roles of leader-member exchange and innovation climate. The... 

There has been a multitude of techniques proposed for identifying vulnerabilities in software. Forcing a program into a vulnerable state has become increasingly unscalable, given the size of the programs and the number of possible execution states. At the same time, techniques that are looking for vulnerability signatures are marred with weak and incomplete signatures. This is not to say that such techniques have failed to identify previously unknown vulnerabilities in the code. However, they have inherent weaknesses, which result in identifying vulnerabilities that are limited in type and complexity. We propose a novel technique to extract succinct vulnerability-relevant statements... 

Gelcasting is a novel forming method in fabricating complex three dimensional ceramic parts, and has many parameters and characteristics required to be specified. Up to now, few articles have been published on determination of the idle time of gelation precisely. In this work the chemorheology of gelation in aqueous solution of acrylamide and N, N′ methylenebisacrylamide monomer, and zirconia (PSZ) suspensions of this solution was investigated. As the viscosity of gel system increases abruptly in gelation point, idle time can be determined precisely by measurement of viscosity against time. Idle time can also be determined through temperature measurement against time since the reaction of... 

The consequences of road accidents are significant for drivers and society. The connected vehicle system (CVS) is a promising technology that can improve road safety by warning drivers of traffic hazards. Broad implementation of the CVS could mitigate the harmful consequences of road accidents. Widespread implementation requires schemes that can promote the pervasive adoption of the system by drivers. This study proposes the innovative idea of implementing the CVS in usage-based insurance (UBI) as a measurement probe and modeling drivers' acceptance of the new UBI scheme. This study developed a random effect logit model demonstrating that the drivers of cheaper vehicles and middle-age... 

Complex product systems (CoPS) industries largely contribute to industrial development, economic growth and creation of national wealth in both developed and developing economies. CoPS also show a number of specific characteristics as a distinctive category of industrial products in comparison with mass-produced consumer goods. These aspects have attracted the attention of scholars to study CoPS over the last two decades, resulting in a fairly extensive body of literature on the subject. However, there is a further need to connect research findings in this area, to illustrate a macro view of the development in the field, explore common themes, and identify possible paths into the future.... 

Outsourcing as a useful strategy in the industry can be integrated into scheduling problems. Moreover, batch outsourcing is a practical assumption owing to the logistics issues for transferring the parts between the manufacturer and the subcontractors. However, this assumption is rarely addressed in the scheduling literature. In this paper, a novel single machine scheduling problem with the option of batch outsourcing is studied. The objective is to minimize the sum of the total completion time of the jobs and the total outsourcing cost. To solve the problem, first, two mixed-integer linear programming (MILP) models, named MP1 and MP2, are developed, which respectively use a straightforward... 

Various methods are used in thermal power plants to adjust the superheated or reheated steam temperature to a pre-determined set point, including flue gas recirculation, using tilting burners and spray of water from discharge of feed water pump, etc. In this paper, an innovative method is presented to control the reheater temperature by tapping water from an interstage of the feed water pump to control reheater temperature at the Bisotoun Power Plant (a steam cycle based power plant in the western Iran). The spray water for the superheaters is secured from the discharge of feed water pump, but interstage water, instead of gas recirculation or using tilting burner, is used to control the...