AMIRKABIR
Year:2005 | Volume:16 | Issue:62-A|Papers Count:11

The information content of a single image is mainly limited by the spatial and spectral resolution of the imaging system. Current imaging systems offer a trade-off between high spatial and high spectral resolutions. No single system offers both of these characteristics. In order to obtain the both characteristics in a single image, that is high spatial and spectral resolutions, a technique image fusion can be employed. Image fusion can incorporate the processing principles of human vision. This paper presents a multi resolution data fusion scheme, based on visual channels image decomposition In this method, there is no need to resample images, which is an advantage over IHS, PCA, Brovey and wavelet methods, it can perform in any aspect ratio between the panchromatic image and multi-spectral images' pixels. The sampling procedure degrade the spectral features of the multi-spectral images in any image merging method, so, it is important to avoid the re-sampling process as much as possible.

Considering wide applications of Ti alloys in medicine as medical implants, attentions are focused on surface properties of these alloys and their behavior in body fluid. In present research, the interaction of pulsed Nd: YAG laser with Ti6Al4V and its effects on surface properties are evaluated. The results indicate that irradiation of Ti6Al4V with Nd: YAG laser under optimum conditions have a number of considerable advantages including increasing corrosion resistance, surface hardness and reduction of vanadium. Modeling of osteoblast cells adhesion to Ti6Al4V and its dependency on stress, temperature, time and surface microstructure are also studied.

Optimal capacitors placement in distribution systems for power loss reduction, releasing kVA of equipments and voltage profile improvement is one of the efficient methods for distribution system operation. In this paper, a novel method for simultaneous allocation of fixed and switch able capacitors in distribution systems with varying load is presented. In this method network configuration, load as fuzzy in multi levels and economical data are used as input data. Then using genetic algorithm, fixed and switch able capacitors are allocated simultaneously. The proposed method was tested and compared with other methods in many cases with satisfactory results.

In this article, a novel method is presented to experimentally determine the stiffness of sensed objects using surgical tools of minimally invasive surgery. To evaluate this mechanical property, which has numerous applications in the field of biomedical engineering, a custom-made tactile sensor was designed and tested. This sensor consists of two separate parts, i.e., a rigid cylindrical section and an annular hollow section made of foam. As a representative application of the constructed sensor, we integrated it with an endoscope grasper and tested the resulting tool. To analyze the performance of the designed grasper, a theoretical model is presented and the experimental data are compared with the proposed model. Keeping the applied forces in the range of one-tenths to one Newton, the resulting error was about twenty percent in estimating the modulus of elasticity of the tested objects. In this research work, for the first time, an endoscope grasper is constructed, which has the capability of estimating the modulus of elasticity.

This work proposes a statistical approach for estimating blood brain barrier permeability. The statistical model simulates crossing of contrast agent according to permeability and lesions of blood brain barrier (BBB). It considers crossing of contrast agent through the capillary and BBB as intrinsically statistical processes and simulates it by Monte Carlo method. We extract real arterial input function (AIF) from magnetic resonance images (MRI) and consider it as input to the model. We then derive the concentration of contrast agent as a function of time in the extra vascular space for abnormal capillary and different permabilities. Next, the real data is extracted from each pixel of rat brain. The curves of simulated and the real data of rat brain are compared and permeability map of rat brain is obtained. The results of analytical method are compared to Monte Carlo simulation results. Because of error, permabilities estimated by the two methods are different. The advantages and error source of each method are explained. The main advantage of Monte Carlo simulation is its use of real data directly. It does not need curve fitting to real data, therefore, it is accurate and easy to use.

Nowadays different equipment is used to measure bone mineral density. The physics of these systems are based on the interaction between x-ray or ultrasound beams with bone. Ultrasound has been used to measure bone characteristics such as speed of sound (SOS), broadband ultrasound attenuation (SUA) and stiffness. In order to construct an ultrasonic bone densitometry system, although complex but more acceptable, immersion method has been implemented. Two transducers one as transmitter and another as receiver are employed. Using an AID converter, the received signal is converted to digital data and transfer to a PC via serial port for signal post processing. To achieve the best accuracy and reduce calculation errors, data acquisition can be performed up to 100 times for each patient. At each burst, time interval between pulse  transmission and reception is measured and by using the time of flight (TOF) technique and having heel width, the average speed of sound in bone can be calculated. SOS is proportional to tissue density and elasticity. In normal bones, SOS is higher than in cancellous and osteoporosis bones. The amount of attenuation in transmitted ultrasound beam can be calculated from received signal spectrum. Using FFT computation of transmitted and received signal and calculation the received signal spectrum to transmitted signal spectrum ratio in the band frequency of 200KHz to 600KHz, variation of BUA against frequency can be drawn. The slope of this curve in the propriety band frequency is proportional to the bone density. To display and process the obtained data, and to present the computed parameters, using appropriate algorithm, a software is developed. For osteoporosis diagnosis, these parameters are compared to the one taken from statistical samples of the Iranian society.

Accurate modeling of ferromagnetic materials is very important in optimal designing of electromagnetic systems. In this paper, a new approach, considering hysteresis for all elements of ferromagnetic material (in the finite element modeling), has been presented. Finite Element Method (FEM) was used for field solution and scalar Preisach model was used for hysteresis modeling. Proposed method benefits from less computational effol1s and accurate prediction of core loss over the core area. With knowing the loss distribution, an accurate thermal analysis is applicable. Proposed method has been verified on a typical system. The computational results are in close agreement with experimental ones.

During past few years, Fuzzy Logic Controllers have found many applications in different area of engineering. In this paper, we present the applications of these controllers in the traffic management of different communication network technology including Asynchronous Transfer Network and Internet Protocol. Different fuzzy controllers. will be proposed for different traffic management mechanisms including buffer management, Active Queue Management, traffic policing, traffic metering, scheduling, Usage Parameter Control and Call Admission Control. Based on simulation results, it can be seen that all proposed fuzzy controllers demonstrate better performance in comparison with traditional mechanisms.

With the increasing of non-linear loads in electric power system, power quality distortion has become a serious issue in recent years. In pulp and paper industries, due to presence of concentrated high power nonlinear loads such as electric drives, this problem is a greater concern. In this paper, power quality problems such as voltage sag and swell in Mazandaran Wood and Paper Industries (MWPI) are presented. Using actual data, the interaction of these voltage transients on behavior of the main production line motor drive is investigated. With simulation by Matlab software, the effects of different kinds of voltage sag on speed, torque, and current of motor are analyzed.

The generalized wave model (GWM) representation of singular 2-D systems has been recently introduced. Based on this index-dependent Model, the general response formula is derived to express the global state of the model solely as a function of inputs and boundary conditions within the admissible subspace. The notion of global asymptotic stability of the GWM is defined and sufficient conditions for stability of the model are obtained which guarantee local stability of the original singular 2-D model.