Sharif Digital Repository

In this paper, we investigate the problem of detecting and monitoring changes (abnormality) in molecular communication (MC), using the quickest change detection (QCD) schemes. The objective is to watch an environment using a sensor network and make decisions on the time and location of changes based on the received signals from sensors in the fusion center (FC). Such assumptions call for considering spatial and temporal correlations among sensors' transmitting signals. We use the framework of Partially Observable Markov Decision Processes (POMDPs) based on non-homogeneous Markov models. The metric in detection (stopping-time) scenario is to minimize the delay of announcing an abnormality... 

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... 

Proper modeling of the human arm dynamic, as it interacts with telemanipulation and haptic systems, is important in enhancing the transparency of these systems. In this article, we introduced an adaptive identifier to estimate the impedance characteristic of a human operator as it interacts with a single translational degree of freedom mechanism. The five parameter model, including an extra spring and damper for a better approximation of the dynamic behavior of human arm, has been used. Since the impedance characteristic of human arm differs from one individual to another, it is important to estimate these parameters for each individual and update the controller to enhance the transparency... 

In this paper, we follow two control tasks in a leader following frame with undirected network and local communications. As the first goal, distributed behavioral imitation, which is necessary to fit agents with complicated motion equations in kinematic frames, is discussed. Providing real agents with behavioral controller makes them capable to act as a kinematic particle. The second goal is to design an active leading strategy for the LA to move the group on a predefined path. Both problems can be mathematically modeled in an affine form, which is the reason behind using a unique adaptive controller to solve them. The controller is based on a neuro-fuzzy structure with critic-based leaning... 

Human bodies use the electrical currents to make the muscles move. Disconnection of the electrical signals between the brain and the muscles as a result of spinal cord injuries, causes paralysis below the level of injury. Functional electrical stimulation (FES) is used to stimulate the peripheral nerves of the disabled limbs. The level of these electrical signals should be selected so that the desired tasks are done successfully. Applying the appropriate controller which can result a human like behaviour and the accomplishment of the desired tasks has become a significant research area. In this paper, the multi-input multi-output (MIMO) musculoskeletal model of human arm with six muscles is... 

In the present research the aging behavior of Al6061 alloy and Al6061/SiCp composite fabricated by powder metallurgy method was investigated. The solution treatment of the samples were carried out at 527°C for 2, 3and 4 h followed by aging at 180°C for different aging times between 1 and 10 h. The existence of SiC particles led to increasing the peak hardness of the composite. The peak hardness of the composite took place at shorter times than that of the 6061 alloy for the samples solution treated for 3and 4 h, but took place at longer times for the samples solution treated for 2 h. The optimum solution treating time was about 3 h for both the composite and the 6061 alloy that led to the... 

Driving behavior recognition is a notable topic in travel safety, as transportation and insurance companies could adopt effective tools to detect unsafe driving and internalize the associated costs. Different driving events and the related severity must be detected to distinguish abnormal behaviors. The global positioning system (GPS) provides useful information regarding the location of the vehicle at any time and is vastly used in various devices such as smartphones and GPS trackers. Other sensors, on the other hand, provide complementary valuable information but their implementation requires extra costs and more complex and intensive algorithms. We developed a threshold-based algorithm to... 

The researches on environmental and sustainability are an active topic, especially in the waste management. As such, the hazardous waste optimization is an active research topic in developing countries which may be integrated with carbon emissions and green subjects. This grand challenge motivates the current research to contribute a new multi-objective optimization model to address the green hazardous waste location-routing problem. The proposed multi-objective optimization model establishes four objectives simultaneously for the first time. In addition to the total cost and the greenhouse gas emissions of the transportation systems as the two main objectives, another objective function... 

Social media platforms thrive upon the intertwined combination of user-created content and social interaction between these users. In this paper, we aim to understand what early user activity patterns fuel an ultimately durable user lifespan. We do so by analyzing what behavior causes potentially durable contributors to abandon their "social career"at an early stage, despite a strong start. We use a uniquely processed temporal dataset of over 6 billion Reddit user interactions on covering over 14 years, which we make available together with this paper. The temporal data allows us to assess both user content creation activity and the way in which this content is perceived. We do so in three... 

The time headway of vehicles is an importan microscopic traffic flow parameter which affects the safety and capacity of highway facilities such as freeways and multi-lane highways. The present paper intends to provide a report on the results of a study aimed at investigating the effect of the lane position on time headway distributions within the high levels of traffic flow. The main issue of this study is to assess the driver's behavior at different highway lanes based on a headway distribution analysis. The study was conducted in the city of Isfahan, Iran. Shahid Kharrazi six-lane highway was selected for collecting the field headway data. The under-study lanes consisted of passing and... 

Driving simulators can provide safe real-world driving conditions that may help researchers study driving behavior; however, driving simulator sickness (DSS) has been recognized as one of the most frequent challenges associated with using driving simulators. The DSS issue may affect the validity and reliability of results obtained during the driving simulator experience. Therefore, it is necessary to understand the potential consequences of DSS in the virtual environment of a driving simulator. The goal of this study is to analyze DSS symptoms among participants of a driving simulator by their demographics. The samples of four simulator studies were combined, including a total of 259... 

Due to international competition and strict limitations of standards regarding the noise level, investigation of gear vibration is of great importance. In this paper, nonlinear oscillations of spur gear pairs including the backlash nonlinearity is studied. Dynamic system is described through the classical single degree of freedom (SDOF) model in terms of dynamic transmission error (DTE). Using multiple scale method, forced vibration responses of the gear system including primary, super-harmonic and sub-harmonic resonances are investigated. In each case, the jump phenomenon and stability analysis are studied. In addition, the effect of dynamic and manufacturing parameters of the gear system... 

This paper presents a double input-double output bilateral low-pass equivalent amplifier behavioral model that takes into account input source and output load termination mismatches. The model is intended for the system-level simulation of amplifier chains subjected to wideband modulated signals, since it can predict the device's input and output scattered waves and their memory effects, in a wide range of voltage standing wave ratios (VSWR). In addition, the model extraction methodology, and its associated laboratory test bench are discussed, noting the limitations of conventional setups for behavioral model extraction and validation. The model is validated comparing the predicted and... 

Open and autonomous environments, such as peer to peer networks or many social networks, are efficient only if cooperation among nodes is ensured. In order to ensure cooperative behavior, we have added a new node type to the system, called inspector and used game theoretical tools to analyze the system. Inspectors punish both misbehaving nodes as well as nodes who provide dishonest ratings about other peers. Analyzing the proposed inspection game ensures that corruption of inspectors and misbehavior of nodes is bounded. The game enables the system designer to set the amount of corruption that is allowed according to the budget  

The control signal magnitude and energy are among the limiting and therefore important factors to be addressed in the practical applications of a synchronization scheme. In this paper, we present an algorithm to find control parameters in an active sliding mode controller in order to reduce the control effort in synchronizing non-identical chaotic systems. We also determine uncertainties bound on the systems dynamics for which the calculated control parameters still guarantee the occurrence of the sliding motion of the error states. The proposed controller was practically applied on an experimental setup, consisting of two chaotic circuits, which resembles Chen and Lu systems behavior.... 

This work presents a behavioral model for non-ideal effects in a novel Hybrid time-interleaved digital to analog converter (TIDAC). In Hybrid DACs, both ΔΣ and Nyquist structures are used. In this work, in the Nyquist path, the 2-time-interleaving technique is used and in the ΔΣ path, a new structure is proposed to reduce the critical path in the TI delta-sigma modulator (DSM). In conventional TIDSM, adding each channel to the structure leads to increasing the critical path as one full-adder. This, in turn, decreases the speed of modulator since a single feedback loop is utilized to compute the running sum of the input signals. In this work, a new type of poly-phase decomposition is... 

When natural disasters happen, relief logistic centers (RLCs) and the quality of their services become absolutely important. In other words, choosing proper locations for RLCs has a direct impact on operating costs and timeliness of responses to the rising demands. This paper aims at proposing a decision support system for prioritizing RLC's locations to facilitate providing emergency helps when natural disasters occur. The present study, focuses on considering availability, risk, technical issues, cost and coverage in locating RLCs. It is assumed that applying analytic hierarchy process (AHP) can facilitate the problem of locating these centers. The most important step in this process is... 

Road traffic crashes have become an important public health problem. By studying the statistics of heavy vehicle crashes in the world, it becomes obvious that although heavy vehicle drivers experience fewer crashes than private car drivers, a large percentage of heavy vehicle crashes leads to death. So, it is important to identify the driving characteristics of heavy vehicle drivers. In this study, 474 Iranian truck drivers were interviewed face to face. Response rate of the survey was 80%, the participants who answered the questions on two behavioral questionnaires: Driver Behavior Questionnaire (DBQ) and Attention-Related Driving Error Scale (ARDES). Also, two sleep assessing... 

In this research, the nonlinear elastic behavior of human extensor apparatus was investigated. To this goal, firstly the best material parameters of hyperelastic strain energy density functions consisting of the Mooney–Rivlin, Ogden, invariants, and general exponential models were derived for the simple tension experimental data. Due to the significance of stress response in other deformation modes of nonlinear models, the calculated parameters were used to study the pure shear and balance biaxial tension behavior of the extensor apparatus. The results indicated that the Mooney–Rivlin model predicts an unstable behavior in the balance biaxial deformation of the extensor apparatus, while the... 

Some known phenomena which cause a buried steel pipeline to fail are large ground motion and landside. Thus, many researchers have studied pipelines behavior against those phenomena with simplified assumptions in which effects of interaction between soil and pipe are not considered as well. In this study, the behavior of a pipe through Normal and Strike slip faults and contact between them are simulated close to reality with the powerful software of ABAQUS. The results from a parametric analysis on effects of those faults on buried steel pipelines show that increasing the angle between the pipe axis and fault plane (up to 90°), as well as the pipe thickness, and decreasing the burial depth...