Sharif Digital Repository

This brief introduces a modified backprojection algorithm to compensate the effect of redundancy of captured data in spatial-fourier or k-space domain for multi-static millimeter-wave imaging. The data measured by each transmitter-receiver pair is explained in k-space domain and the redundancies are determined. Such redundancies act as an undesirable filter that distorts the appearance of the resulting image. Our goal is to modify SAR backprojection algorithm to address this problem, where extensive simulation and experimental results are also provided. Our measurements show a significant improvement in the overall quality and edge preservation in the reconstructed image of objects under the... 

This paper focuses on an efficient approach for designing multi-static arrays for millimeter-wave imaging, based on the k -space or Fourier-spatial domain characteristic of imaging systems. Our goal is to decrease the redundancy of the data measured by each antenna and to improve the resolution of the reconstructed image. The proposed technique is based on determining the role of each transmitter and receiver, in collecting the data from each voxel of the target in k -space domain and then rotating the transmitters' beams to measure the desirable information. The effect of non-uniform redundant k -space domain frequency samples that act as an undesirable filter is compensated using a... 

This article focuses on analyzing the aliasing artifact in millimeter-wave imaging systems, with a special focus on multistatic arrays. The current framework to analyze the behavior of multistatic structures is based on the effective aperture concept. Based on this framework, an equivalent monostatic array, approximating the position of each transmitter-receiver pair by its midpoint, is used to quantify the response and efficiency of the system. Although this framework helps to simplify the study of the complex characteristics of multistatic arrays, it suffers from vital deficiencies. Especially, it fails to describe the aliasing artifacts, seen in the image of some sparse multistatic... 

In this study, a thorough analysis of image reconstruction in an active millimetre-wave (MMW) cylindrical imaging system is performed. To improve the system's performance in terms of the total cost as well as the coupling effect, sparse multistatic arrays are desired. Nevertheless, the existing reconstruction methods fail to operate in sparse multi-static antenna-array systems. Therefore, to address these shortcomings, in this study, at first, the existing MMW mono-static cylindrical image reconstruction methods are modified in both single-frequency and wideband reconstruction platforms. Moreover, in order to further improve the image quality and the system cost, a sparse multi-static... 

In this research, Magnesia Spinel refractories were formulated by using sintered magnesia, Tabular and Calcined Alumina and sintered Spinel. The grain size distribution of raw materials was modified, using the Andreessen equation. In order to improve the physical and mechanical properties and corrosion resistance of specimens, none stabilized Zirconia was added to the system. The pressed samples were sintered at 1700°C and the properties were evaluated at room and high temperatures. The formed phases and resultant microstructure were also, analyzed by XRD and SEM. The corrosion test was conducted in two parts. First, the depth of corrosion was measured in two zone, within 0-1mm and 1-2 mm... 

Introduction: Given the high prevalence of low back pain in manual handling activities, its known relationship with spinal loads, and the role of muscular fatigue and the body’s adaptive mechanisms to counteract fatigue, this study investigated the effect of repetitive lifting tasks on trunk muscular fatigue and the kinematics of the spine and load-in-hand. Material and Methods: Eighteen male volunteers lifted a box from the floor to their waist height at a pace of ten lifts per minute until they could no longer continue the task and reported the highest level of exhaustion. Kinematic data and muscle electromyographic activity were simultaneously recorded using a motion capture system and an... 

Objective: Spine kinematics, kinetics, and trunk muscle activities were evaluated during different stages of a fatigue-induced symmetric lifting task over time. Background: Due to neuromuscular adaptations, postural behaviors of workers during lifting tasks are affected by fatigue. Comprehensive aspects of these adaptations remain to be investigated. Method: Eighteen volunteers repeatedly lifted a box until perceived exhaustion. Body center of mass (CoM), trunk and box kinematics, and feet center of pressure (CoP) were estimated by a motion capture system and force-plate. Electromyographic (EMG) signals of trunk/abdominal muscles were assessed using linear and nonlinear approaches. The L5-S1... 

Objective: Spine kinematics, kinetics, and trunk muscle activities were evaluated during different stages of a fatigue-induced symmetric lifting task over time. Background: Due to neuromuscular adaptations, postural behaviors of workers during lifting tasks are affected by fatigue. Comprehensive aspects of these adaptations remain to be investigated. Method: Eighteen volunteers repeatedly lifted a box until perceived exhaustion. Body center of mass (CoM), trunk and box kinematics, and feet center of pressure (CoP) were estimated by a motion capture system and force-plate. Electromyographic (EMG) signals of trunk/abdominal muscles were assessed using linear and nonlinear approaches. The L5-S1... 

In this paper, a new algorithm for solving the shortest loop design problem is presented. The shortest loop design problem is to find the shortest loop for an automated guided vehicle covering at least one edge of each department of a block layout. In this paper, first it is shown that this problem can be represented as a graph model. The properties of the presented model enable us to design a meta-heuristic based on ant colony system algorithm for solving the shortest loop design problem. Computational results show the efficiency of our algorithm in compare to the other techniques  

In a series of articles, Asbjorn Steglich-Petersen and Nick Zangwill argue that, since propositional attitude (PA) ascription judgements do not behave like normative judgements in being subject to a priori normative supervenience and the Because Constraint, PAs cannot be constitutively normative.1 I argue that, for a specific version of normativism, according to which PAs are normative commitments, these arguments fail. To this end, I argue that commitments and obligations should be distinguished. Then, I show that the intuitions allegedly governing all normative judgements do not even purport to hold for commitment-attributing judgements. Copyright © Canadian Philosophical Association 2020  

A number of philosophers have argued that there is a basic problem in the no-guidance argument against content normativism. The problem is that the argument restricts the essential normativity of intentional states to the formation of these states being guided by certain norms. But it is suggested that the essential norm-governedness of intentional states can be equally plausibly construed as the assessability of these states by norms, which does not imply complying with them. Although I concur with the problem diagnosed in the no-guidance argument, I take issue with the alternative conception of normativity which is put forward. In its stead, I argue that considering intentional states as... 

A number of philosophers have argued that there is a basic problem in the no-guidance argument against content normativism. The problem is that the argument restricts the essential normativity of intentional states to the formation of these states being guided by certain norms. But it is suggested that the essential norm-governedness of intentional states can be equally plausibly construed as the assessability of these states by norms, which does not imply complying with them. Although I concur with the problem diagnosed in the no-guidance argument, I take issue with the alternative conception of normativity which is put forward. In its stead, I argue that considering intentional states as... 

Abraham’s Dilemma is the conjunction of three jointly inconsistent propositions: (i) God’s commands are never morally wrong, (ii) God has commanded Abraham to kill his innocent son, and (iii) killing innocent people is morally wrong. Drawing on an overlooked point from the Qur’an regarding the content of the command as well as a conceptual analysis of intentional action, this paper proposes a novel solution to the dilemma by discarding proposition (ii) in a new way. Current approaches to rejecting proposition (ii) tend to appeal to epistemic failure on the side of Abraham. In my approach, which draws on the so-called accordion effect in intentional action, God’s command is interpreted in... 

In what sense can one claim that intentional explanations are essentially normative, given that people’s actions and thinking are replete with various irrationalities, yet are still pretty well explained by this explanatory framework? This article provides a novel response to this enduring objection. First, following Brandom, it is suggested that, to understand the normativity of intentional states, we should countenance and distinguish between two normative categories of commitment and entitlement, only the former of which is argued to be essential for intentional explanations. Conflating these two normative dimensions is noted to be one of the main sources of the objections leveled against... 

Abraham’s Dilemma is the conjunction of three jointly inconsistent propositions: (i) God’s commands are never morally wrong, (ii) God has commanded Abraham to kill his innocent son, and (iii) killing innocent people is morally wrong. Drawing on an overlooked point from the Qur’an regarding the content of the command as well as a conceptual analysis of intentional action, this paper proposes a novel solution to the dilemma by discarding proposition (ii) in a new way. Current approaches to rejecting proposition (ii) tend to appeal to epistemic failure on the side of Abraham. In my approach, which draws on the so-called accordion effect in intentional action, God’s command is interpreted in... 

In what sense can one claim that intentional explanations are essentially normative, given that people’s actions and thinking are replete with various irrationalities, yet are still pretty well explained by this explanatory framework? This article provides a novel response to this enduring objection. First, following Brandom, it is suggested that, to understand the normativity of intentional states, we should countenance and distinguish between two normative categories of commitment and entitlement, only the former of which is argued to be essential for intentional explanations. Conflating these two normative dimensions is noted to be one of the main sources of the objections leveled against... 

Waterflooding has been regarded as an efficient method for pressure maintenance of oil reservoirs. x Improved techniques such as Smart Water flooding as a new EOR/IOR process has gained more momentum based on the recent research activities in this field and the reduction of oil price. Despite many efforts on achieving the governing mechanisms of Smart Water flooding in many individual fields, most of data are sparse and more possible mechanisms which explains all the interactions yet to be introduced. This experimental study used a systematic laboratory framework which is based on seawater treatments at fixed ionic strength to eliminate the ionic strength effects, NaCl considered as the... 

Neglecting actuator dynamics in control of rigid manipulators can degrade performance and stability of the system. However, consideration of actuator dynamics usually requires measurement of joint torque or armature currents. In this paper, we present an adaptive controller for motion tracking of an n-DOF manipulator without using joint torque measurement. Semi-global convergence of motion and torque tracking errors to zero is proven. We show that the use of non-minimal representation of manipulator dynamics significantly simplifies its linear parametrization. Simulation example shows that avoiding joint torque measurement reduces system sensitivity to sensor failure and noise  

In this paper, the production of lactic acid from deproteinized whey, using immobilized Lactobacillus casei on wood chips is investigated. The immobilization process was considered on various supports like wood chips, brick particle and porous glass by adsorption and on eggshell with glutaraldehyde by covalent bonding. Wood chips demonstrated the highest adsorption among all the supports and, therefore, was chosen as the best support for production. Batch production was studied at four temperatures and three different pH after five days. The highest concentration of lactic acid (16 g/1) was observed at T = 28°C and pH = 5.5. The optimum condition of temperature and pH for the continuous... 

This study aimed to investigate the leadership roles of subsidiary board chairpersons (SBCs). To this end, the study focused on the effect of the context of the parent company on the roles of SBCs in enhancing board effectiveness. This can be a response to the call for further investigation on the role of contextual and institutional factors in board effectiveness. An embedded multiple-case study design was used to compare the leadership role of chairpersons of the two groups of boards with high and low effectiveness in a corporation assessed via a multi-source appraisal method. Based on a series of interviews, we compared the mechanisms that differentiated the two groups of boards. Managing...