Sharif Digital Repository

This paper describes a study on the usage of ultrasound to measure the grasping force components when elastic fingers of a robot grasp an object. The ultrasonic sensor embedded in the soft finger accurately measures the echoes timing lag and amplitude that give information about the amount and directions of the grasping force components. The experimental results indicate good sensitivity of the proposed soft finger to both normal and tangential components of the grasping force  

Optical measurement of voltage because of its excellent advantages is studied by several research groups. In this paper, two optically voltage measurement method based on periodic structure have been introduced. First one is based on Bragg reflection effect. The coefficient of reflection from a periodic layered medium depends on properties of periodic structure. In this work a periodic structure on LiNbO3 substrate was considered and under a high voltage electric field perpendicular to surface of layers, refractive indices of substrate have been changed. Performance of reflection versus applied electric field was calculated. Second method was based on Guided-mode resonance effect. Guided... 

One of the major goals of Artificial Life is to know 'life-as-it-could-be'. Several platforms for ALife simulations are presented but not all are suitable for every cognitive study in ALife. Platforms designed for studying the origin of life are based on a world of simple rules and simple objects, capable of producing complex organisms. But such worlds are not suitable for cognitive studies focused on complex behaviors, because they are too slow for emergence and simulation of such behaviors. A platform called Zamin is presented, which is believed to be fast, expandable, realistic, and suitable for cognitive simulations aimed to study the emergence of complex behaviors. © Springer-Verlag... 

Density functional theory calculations are utilized for probing the effect of doping Al, Ga, and Zn atoms on the sensing performance of a C60 fullerene in detecting the dichlorosilane (DS) gas. We predicted that the interaction of pure C60 with DS is physisorption, and the sensing response (SR) of C60 is 8.6. The adsorption energy of DS changes from − 21.4 to − 84.4, − 86.7, and − 90.7 kJ/mol, by doping the Al, Ga, and Zn metals, respectively. Also, the corresponding SR meaningfully rises to 33.7, 52.3, and 92.9, indicating that the Zn transition metal much more increases the sensitivity of fullerene compared to the Al and Ga metals. Our theoretical results further support the fact that the... 

The necessity of research in food and nutrition and the emergence of diabetes mellitus call for fast and efficient glucose detection. Here, series of highly sensitive non-enzymatic photoelectrochemical glucose sensor based on engineered titanium dioxide nanotube arrays has been synthesized using a simple electrochemical approach to tune nanotubes morphology in a way that the highest sensitivity factor (525.5 µAmM−1cm−2) and saturation concentrations (0.18 mM) achieved in the photoelectrochemical sensor. The formation of oxygen-rich titanium oxide was confirmed by several techniques. Dependent on the growth condition, nanotube length changed from 1.9 to 8.4 µm while their inner diameter... 

Assessment of respiratory volume is extensively performed in clinical applications in order to assess the cases of respiratory illness and the progression of the respiratory syndromes. Respiratory plethysmography is employed to determine the changes of chest volume to monitor breathing. A wearable respiration measuring system has been introduced to detect volume variations of chests. The system consists of a flexible sensor, stretchable cloth and electrical board. The flexible sensor, which measures electrical voltage produced by extension movements, is installed inside the shirt and nearly contacts the chest. The system can be used everywhere and be self-applied by patients. The main... 

Using simultaneous photoplethysmogram (PPG) and pulse transducer signals from the same finger, a high correlation (Mean: 98.6, STD: 1) is obtained between the AC part of the PPG and estimated volume changes (after normalization). These results point to the fact that in the resting fingertip, PPG signal variations are only due to volume changes and that blood density does not change thus has no contribution  

The wireless sensor networks include a lot of sensor nodes with a limited energy distributed in a limited geography area. One of the important issues in these networks is the increased longevity of a network. In a wireless sensor network a long connecting distance between sensors and sink uses a lot of energy and decreases the longevity of network. Since clustering can decrease requirement of using energy for wireless sensor networks, we are following an intelligent technique for forming and managing clusters in this article. With clustering wireless sensor network and using a genetic algorithms we can decrease the connecting distance a little, so the longevity of network will be more. The... 

The problem of surveillance for intrusion detection in a camera sensor network is addressed in this paper. In order to save limited resources, a sensing task should involve just the right number of sensors. For a wide enough coverage area random and uniform distribution can be applied. We propose a novel method which allows reduction of number of sensors and guarantees a desired surveillance against aerial intrusion. Enhancement of the method is also offered to further reduce the number of sensors and improve the performance. ©2008 IEEE  

Design and operation of a double-fiber sensor for displacement measurements are reported in this study. In this arrangement, one fiber transmits the laser light to the target and the second one receives the light reflected off the target and transmits to a photodetector. Utilizing inexpensive plastic optical fibers offers advantages such as higher reflexability and more robustness at a reasonable cost, which are required for some applications. The novelties of the reported design are compactness of the fiber probe, flexibility, long dynamic range (22 mm), and it is possible to use the source and the detector at the same side. The displacement of the target causes the intensity modulation and... 

Molecular structural mechanics is implemented to model the vibrational behavior of defect-free single-layered graphene sheets (SLGSs) at constant temperature. To mimic these two-dimensional layers, zigzag and armchair models with cantilever and bridge boundary conditions are adopted. Fundamental frequencies of these nanostructures are calculated, and it is perceived that they are independent of the chirality and aspect ratio. The effects of point mass and atomistic dust on the fundamental frequencies are also considered in order to investigate the possibility of using SLGSs as sensors. The results show that the principal frequencies are highly sensitive to an added mass of the order of 1 0-... 

In this work, we have examined the problem of distributed consensus averaging over senor networks from a novel point of view considering the need for security. We have proposed a method for incorporating privacy into the scalable average consensus mechanisms. Our proposed method, Random Projections Method (RPM), is lightweight and transparent since it is not based on cryptography and does not require any change in the fusion system. RPM is based on introducing a simple, yet effective pre-fusion algorithm. We mathematically derived the correctness of RPM and analyzed its effect on convergence of the system through simulation. Robustness of RPM against honest-but-curious adversaries is... 

In a distributed algorithm several processing nodes communicate with each other and incorporate in order to reach a common goal. Each unit has its own locally-observed environment while it can either help or mislead other units when sharing its information. This could be either intentional or simply due to the observation noise. Previous works mainly focus on locating the agents properly and assigning weights based on stationary environment in order to minimize the impact of noisy nodes. We, however, propose a method capable of assigning combination weights in accordance with momentary performance of the neighboring nodes. In order to demonstrate this capability, the proposed algorithm has... 

In this paper a combination of routing and power management within the context of wireless Ad-hoc Sensor Networks is considered. Using lower layer information (e.g. collision that is considered in MAC layer) is another novel concern which is used in routing decisions. More specifically in this paper we introduce a cross-layer design in which each node dynamically chooses the number of its neighbors and adjusts its power just enough to reach its farthest determined neighbor. In this algorithm the power of transmission and collision are used as metrics for routing and the number of neighbors in which the total energy consumption in data transmission will be the minimum is selected. © 2005 IEEE... 

Flooding algorithm is one of the most significant algorithms used in sensor networks. Although simple, this algorithm causes a large amount of energy and bandwidth to be wasted. The most important application of flooding is RREQ flooding in initial step of most routing algorithms. Although simple, this algorithm causes a large amount of energy and bandwidth to be wasted. Most previous efficient flooding algorithms use location information which is impossible for simple node in sensor network. Some others are not suitable for RREQ flooding due to eliminating redundant retransmissions. We present a modified flooding that simultaneously decreases energy consumption as well as network delay.... 

This paper proposes a new medium-access control (MAC) protocol designed for wireless sensor networks. A wireless sensor network is an array of large number of sensors interconnected by a multi-hop ad-hoc network. The fundamental objective for sensor network is low-power consumption while latency is usually less important. This characteristic of sensor network motivates different MAC laver design from the conventional wireless network to reduce power consumption. In this paper novel algorithm based on distributed mediation device (DMD) protocol has been introduced that utilized distributed node scheduling strategy to dramatically increase energy saving principally in intermediate devices... 

This paper proposes a new method to improve accuracy and real-time performance of inertial joint angle estimation for upper limb rehabilitation applications by modeling body acceleration and adding low-cost markerless optical position sensors. A method based on a combination of the 3D rigid body kinematic equations and Denavit-Hartenberg (DH) convention is used to model body acceleration. Using this model, body acceleration measurements of the accelerometer are utilized to increase linearization order and compensate for body acceleration perturbations. To correct for the sensor-to-segment misalignment of the inertial sensors, position measurements of a low-cost markerless position sensor are... 

This paper proposes a decentralized algorithm to organize an ad-hoc sensor network into clusters. Each sensor operates independently, monitoring communication among others. Those sensors which have many neighbors that are not already part of a cluster are likely candidates to creating a new cluster by declaring themselves to be a new cluster-head. The Clustering Algorithm via Deadline Timer (CADT) provides a protocol whereby this can be achieved and the process continues until all sensors are part of a cluster. Because of the difficulty of analyses simplified models are used to study and abstract its performance. A simple formula to estimate the number of clusters which will be formed in an...