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Search Results: 1 - 10 of 439 matches for " Hamidreza Kamrani "
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Synthesis and Characterization of Copper Nanoparticles by Bis-(Acetylacetonato)-Copper (II) Using Nonionic Surfactants and the Effect of Their Structures on Nanoparticles Size and Yield  [PDF]
Hamidreza Kamrani
Open Journal of Inorganic Non-metallic Materials (OJINM) , 2018, DOI: 10.4236/ojinm.2018.82002
Abstract: Between all precursors of copper complex, bis-(acetylacetonato)-copper (II) and bis-oxalate copper (II) with very close structures are two of the best representatives for copper nanoparticles synthesis. In this research, only bis-(acetylacetonato)-copper (II) in presence of some effective non-ionic surfactants such as Triton X-100, Dodecylamine, Tween 80 and also triphenylphosphine as a reducing agent via thermal decomposition process was used for copper nanopaticles synthesis. Two shif-base E19 and E22 complexes were also used for the investigation of these kinds of shif-base complexes capabilities by this method as precursors and all results were compared with each other. Between all surfactants, Triton X-100 gave the best yield with the largest grains. The techniques used for characterization of copper nanoparticles were TEM, EDX, FT-IR and XRD. TG-DTA and CV were used for characterization of bis-(acetylacetonato)-copper (II) complex.
Real-Time Internet-Based Teleoperation  [PDF]
Ehsan Kamrani
Intelligent Control and Automation (ICA) , 2012, DOI: 10.4236/ica.2012.34041
Abstract: Internet-based teleoperation employs robots and internet a two breakthrough technologies to manipulate robots from distance for different applications. Variable and unknown time delay dynamics of internet is the main obstacle for realtime teleoperation via internet. In this paper the internet delay dynamics and its characteristics have been studied based on the measurement in different nodes. Then a black-box model for end-to-end internet delay dynamics has been developed using system identification and Auto-Regressive eXogeneous (ARX) model. Our experimental studies show a regular periodic behaviour in long-term intervals of internet delay variation and also confirm the accuracy and reliability of our theoretical and modelling derivations. This paper also introduces a novel multivariable control method for real-time telerobotic operations via Internet. Random communications delay of the Internet can cause instability in realtime closed-loop telerobotic systems. When a single identification model is used, it will have to adapt itself to the operating condition before an appropriate control mechanism can be applied. Slow adaptation may result in a large transient error. As an alternative, we propose to use a Multiple Model framework. The control strategy is to determine the best model for the current operating condition and activate the corresponding controller. We propose the use of Multi-Model Adaptive Control Theory and Multivariable Wave prediction method to capture the concurrency and complexity of Internet-based teleoperation. The results confirm the efficiency of the proposed technique in dealing with constant and variable delay dynamics of internet.
Extracting the Prevailed Patterns in Recognizing the Picture by the Human Vision
Ehsan Kamrani
International Journal of Advanced Robotic Systems , 2010,
Abstract: We have tried to present the most matched approaches with which the vision dose through numerous studying the segment fields and recognizing the picture. Here we define external pictures features as the prevailed picture features and then extract the locust point of minus decline and among these points. Of minus decline and among these points we have defined the points which match with the human vision specifications according to the defined factors in this research such as clarification sharpness roundness and adjacency and used them as copied systems. We have reviewed our proposed patterns for truth, correctness and validity through performing two empirical tests.
Fully On-Chip Integrated Photodetector Front-End Dedicated to Real-Time Portable Optical Brain Imaging  [PDF]
Ehsan Kamrani, Frederic Lesage, Mohamad Sawan
Optics and Photonics Journal (OPJ) , 2012, DOI: 10.4236/opj.2012.24037
Abstract:

Optical brain imaging using functional near infra-red spectroscopy (fNIRS) offers a portable and noninvasive tool for monitoring of blood oxygenation. In this paper we have introduced a new miniaturized photodetector front-end on achip to be applied in a portable fNIRS system. It includes silicon avalanche photodiodes (SiAPD), Transimpedance amplifier (TIA) front-end and Quench-Reset circuitry to operate in both linear and Geiger modes. So it can be applied for both continuous-wave fNIRS (CW-fNIRS) and also single-photon counting. Proposed SiAPD exhibits high-avalanche gain (>100), low-breakdown voltage (<12 V) and high photon detection efficiency accompanying with low dark count rates. The proposed TIA front-end offer a low power consumption (<1 mW), high-transimpedance gain (up to 250 MV/A), tunable bandwidth (1 kHz - 1 GHz) and very low input and output noise (~few fA/√Hz and few μV/√Hz). The Geiger-mode photon counting front-end also exhibits a controllable hold-off and rest time with an ultra fast quench-reset time (few ns). This integrated system has been implemented using submicron (0.35 μm) standard CMOS technology.

Study on the Effects of Work Teams on Human Resources Excellence  [PDF]
Ebrahim Kalani, Ehsan Kamrani
Journal of Human Resource and Sustainability Studies (JHRSS) , 2017, DOI: 10.4236/jhrss.2017.51002
Abstract: The conception and use of work teams have been one of the main subjects of management researches for the last few decades and in the past years many developments have happened in the kinds and usage of them, which have improved the condition of organizations and human resources management. Our objective in this paper is to observe the formation of work teams and how they affect human resources excellence. Finding new and creative solutions for todays intricate situations is becoming more and more difficult and employees can’t solve them on their own anymore and this shows and bolds the importance of teamwork and forming work teams. The main objective however in this paper is to evaluate the effect of 5 main characteristics of work teams (which are team structure, leadership, control, mutual support and communication) on the 3 main characteristics of human resources excellence (which are delegation, motivation and team work) in Torang Darya Shipping Company. To do so, 200 personnel at the department were randomly selected from 450 personnel by Cochran sample size formula and answered to the research made questionnaire derived from[1][2] and[3]. The content validity of the questionnaire has been confirmed by the experts and academicians and the reliability has also been confirmed
Pathology of Barriers to Sharing Knowledge in Project Management and Ranking Them by AHP Method  [PDF]
Ebrahim Kalani, Ehsan Kamrani
Journal of Human Resource and Sustainability Studies (JHRSS) , 2017, DOI: 10.4236/jhrss.2017.51007
Abstract: Although knowledge management is a necessary part of strategic development of organizations, resources and improvement in competition, since it is always seen just as a temporary solution, most of related experiences have faced failure. Moreover since projects are mostly temporary and after they are done some of the main team members leave the company, this means the knowledge goes with them so this will cost future projects more money and time. In the present study we will try to find the main barriers for knowledge transmission and to rank them by statistical method of Analytic Hierarchy Process (AHP). In the end it comes to conclusion that despite the existence of the Project Management Body of Knowledge (PMBOK), it has been overlooked. The main barriers are the lack of organizational culture of preserving and sharing the knowledge and lack of trust and appreciation for using it throughout the company.
Fabrication and Studying the Mechanical Properties of A356 Alloy Reinforced with Al2O3-10% Vol. ZrO2 Nano-particles through Stir Casting  [PDF]
Mohsen Hajizamani, Hamidreza Baharvandi
Advances in Materials Physics and Chemistry (AMPC) , 2011, DOI: 10.4236/ampc.2011.12005
Abstract: Al2O3-ZrO2 with a high level of hardness and toughness is known as ceramic steel. Due to its unique properties it can be used as a reinforcement in fabrication of metal matrix composites. In this study, nanoparticles of Al2O3-10% ZrO2 with an average size of 80 nm were used to fabricate Al matrix composites containing 0.5, 1, 1.5 and 2 wt.% of the reinforcement. The fabrication route was stir casting at 850?C. There is no report about usage of this reinforcement in fabrication of composites in the literature. The microstructures of the as-cast composites were studied by scanning electron microscope (SEM). Density measurement, hardness and tensile properties were carried out to identify the mechanical properties of the composites. The results revealed that with increasing the reinforcement content, density decreased while yield, ultimate tensile strength and compressive strength increased. Also, hardness increased by increasing the reinforcement content up to 1 wt.% Al2O3-10% ZrO2 but it decreased in the samples containing higher amounts of reinforcement.
Training Based Channel Estimation in MIMO-OFDM Systems  [PDF]
Maryam Imani, Hamidreza Bakhshi
Communications and Network (CN) , 2012, DOI: 10.4236/cn.2012.41008
Abstract: OFDM combined with the MIMO technique has become a core and attractive technology in future wireless communication systems and can be used to both improve capacity and quality of mobile wireless systems. Accurate and efficient channel estimation plays a key role in MIMO-OFDM communication systems, which is typically realized by using pilot or training sequences by virtue of low complexity and considerable performance. In this paper, we discuss some methods for channel estimation based training symbols in MIMO-OFDM systems. The results confirm the superiority of the represented methods over the existing ones in terms of bandwidth efficiency and estimation error.
The Tight Bound for the Number of Pilots in Channel Estimation for OFDM Systems  [PDF]
Maryam Imani, Hamidreza Bakhshi
Communications and Network (CN) , 2012, DOI: 10.4236/cn.2012.42019
Abstract: Coherent detection in OFDM systems requires accurate channel state information (CSI) at the receiver. Channel estimation based on pilot-symbol-assisted transmissions provides a reliable way to obtain CSI. Use of pilot symbols for channel estimation, introduces overhead and it is desirable to keep the number of pilot symbols as minimum as possible. This paper introduces a new tight bound for the number of pilots in channel estimation using adaptive scheme in OFDM systems. We calculate the minimum number of necessary pilots using two approaches. The first approach for the number of pilots is obtained based on Doppler frequency shift estimation and the second approach is acquired based on channel length estimation using second order statistics of received signal. Finally we obtain the tight bound for the number of pilots using attained values.
Efficient hemodynamic states stimulation using fNIRS data with the extended Kalman filter and bifurcation analysis of balloon model  [PDF]
Ehsan Kamrani, Armin N. Foroushani, Mohsen Vaziripour, Mohamad Sawan
Journal of Biomedical Science and Engineering (JBiSE) , 2012, DOI: 10.4236/jbise.2012.511076
Abstract: This paper introduces a stochastic hemodynamic system to describe the brain neural activity based on the balloon model. A continuous-discrete extended Kalman filter is used to estimate the nonlinear model states. The stability, controllability and observability of the proposed model are described based on the simulation and measurement data analysis. The observability and controllability characteristics are in- troduced as significant factors to validate the preference of different hemodynamic factors to be considered for diagnosis and monitoring in clinical applications. This model also can be efficiently applied in any monitoring and control platform include brain and for study of hemodynamics in brain imaging modalities such as pulse oximetry and functional near infrared spectroscopy. The work is on progress to extend the proposed model to cover more hemodynamic and neural brain signals for real-time in-vivo application.
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