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Electrical and Electronics Engineering, 2007. ICEEE 2007. 4th International Conference on

Date 5-7 Sept. 2007

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Displaying Results 1 - 25 of 106
  • Modeling Chromatic Pupillary Responses in Healthy People

    Page(s): 57 - 60
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2418 KB) |  | HTML iconHTML  

    We propose a model to determinate pupillary changes due to chromatic stimulus. The pupillary diameters (PD) from 44 subjects with normal vision of colors were measured. These PD were elicited by 26 different chromatic stimuli (from 400 to 650 nm). The proposed model establishes the pupillary behavior for different colors. To determinate this model, we consider the characteristics of the subject (age and gender), stimulus (luminance and wavelength) as the diameter of their pupil (for white stimulus). With our approach the maximum coefficient of correlation obtained was of 1.0 in 90% of the cases analyzed (PD measured and calculated). This proposed model is the first all over the world. View full abstract»

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  • Epoch Parameterization by Gabor Atom Density in Experimental Epilepsy

    Page(s): 61 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2094 KB) |  | HTML iconHTML  

    An Electrocorticogram (ECoG), during an epilepsy episode can change dramatically from the normal state into a high amplitude low frequency signal and suddenly return to the normal sate. It is possible to identify some stages in the epilepsy seizure, the most representative of them: basal, preictal, ictal and posictal. ECoG are highly non periodical signals, so they are analyze with T-F algorithms, in order to follow up its frequency evolution through the seizure stages. Each seizure stage has different frequency components and they show up at different time. Experimental epilepsy produce by kindling model in rats is used; signals are recorded at cortex level. The ECoG is decompose by means of the Matching Pursuit algorithm into Gabor atoms, so the Gabor Atom Density could be a measure of the epoch, which tell us if an epoch from an ECoG belong to one of the four seizure stages. View full abstract»

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  • Assistant System for Locking Intramedullary Nails Used to Repair Fractures of the Long Bones

    Page(s): 65 - 67
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3765 KB) |  | HTML iconHTML  

    Every year, more than 492,000 orthopedic surgeries are performed throughout the world to repair fractures of the long bones. The most commonly used method of repair is closed intramedullary nailing. According to surgeons, the most difficult task of this method is the distal locking of the nail. This work proposes a new system for locating the holes of intramedullary nails used for these fractures. The proposed method uses permanent magnets and magnetic sensors to locate on the bone the exact drill point with which to secure the nail. The method is developed with the intention of reducing the large doses of radiation to which surgeons and patients are exposed when applying traditional nailing methods. The system is portable and runs on batteries, so it is totally autonomous, easy to use and very reliable. View full abstract»

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  • A Hands Gesture System Of Control For An Intelligent Wheelchair

    Page(s): 68 - 71
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2448 KB) |  | HTML iconHTML  

    When an unfortunate event affects the motor capacity of a person, it is necessary to use devices like wheelchairs that offer a means o displacement for patients with motors problems of the lower limbs. Some patients that cannot manipulate the wheelchair with their arms due to a lack of force or psychomotor problems in the superior members, request electric wheelchairs, frequently manipulated with joysticks; however the joystick manipulation is even not practical and frequently it must be handle with the mouth. The present article presents the partial results in the development of a wheelchair controlled by an intuitive interface, where the instructions are given by hand gesture instructions. The advances are presented in the realization of the control software using a Webcam and some distances and presence sensors controlled by a PIC microcontroller that establishes the communication with a program developed in Labview. View full abstract»

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  • Dispersion of Ratios of Ventricular Repolarization Intervals in Normal Subjects and Old Myocardial Infarction Patients

    Page(s): 72 - 74
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2259 KB) |  | HTML iconHTML  

    We evaluate the dispersions in ratios of ventricular repolarization intervals, in order to determine whether they improve the separation between 10 normal subjects and 10 patients with old myocardial infarction compared with dispersion of ventricular repolarization intervals. All the ratios dispersions were larger in OMI patients than in normal subjects and the best separation between groups was obtained with the dispersions of ratios Tpe/JT and Tpe/QT. These novel indices could improve the identification of post-MI patients with risk of malign ventricular arrhythmias. View full abstract»

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  • Development of lead-free (Bi1/2Na1/2) BaTiO3 Piezoelectric Ceramics for Clinical Applications in Ultrasound

    Page(s): 75 - 78
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1275 KB) |  | HTML iconHTML  

    The present paper provide a method to obtain lead-free piezoelectric ceramics based on bismuth sodium titanate (Bi1/2Na1/2)BaTiO3 (BNBT), as well as the characterization of these, the elaboration consists from the dust mixture to the sinterized the pieces in a furnace, the BNBT systems had been studied for its dielectrics and piezoelectric properties, the characterization consists of determining the Curie temperature and resonance frequency. BNBT ceramics present similar characteristics to those of the PZT ceramics. Because of its high frequency of resonance they can be used in biomedical applications, concretely in ultrasound applications. View full abstract»

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  • Pupillary response interpretation to white noise audible stimuli

    Page(s): 79 - 81
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1490 KB) |  | HTML iconHTML  

    This paper is focused to analyze the pupillary responses elicited by an audible stimulus (white noise). The stimulus durations were 150 ms, 250 ms and 2 s. And each one was applied twice, at 5 s and 15 s. The test was performed on photopic conditions in 5 men subjects from 25 years old to 29 years old. View full abstract»

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  • Developrnent of an Educational Simulator and Graphical User Interface for Diabetic Patients

    Page(s): 82 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3043 KB) |  | HTML iconHTML  

    This paper presents an educational simulator and graphical user interface for type 1 diabetes patients. The educational simulator is conformed by three mathematical models which describe the glucose-insulin dynamics using a compartmental model, with additional equations to reproduce aerobic exercise, gastric glucose absorption by the gut, and subcutaneous insulin absorption. Moreover, multiple daily doses and continuous insulin infusions can be simulated in order to implement an intensive insulin therapy. The mathematical models, integration methods and insulin dosing strategies were implemented in Java programming language. As a result, the Java Educational Diabetes Management Advisor (JEDMA) shows the influence of exercise periods, food intakes, and intensive insulin therapies on the glucose concentrations. View full abstract»

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  • CT-Projections Hardware Raw Data Acquisition System for Image Reconstruction

    Page(s): 86 - 89
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (8604 KB) |  | HTML iconHTML  

    Computer tomography (CT) is a very competitive medical imaging field, where worldwide manufactures are constantly improving the state of the art investing huge amounts of money to assure sales. Therefore, warranties and maintenance contracts avoids hospital and university research labs in Latin America to have information access and to perform research experiments where CT hardware and software are involved. Despite this, university CT research labs are important to exist in order to create the "know-how" and to preserver the knowledge. This paper addresses important issues to create CT scanner experiments using donated equipment out of commercial companies support that not only take advantage of the hardware-software state of the art but in addition the experiments are used to improve the universal knowledge in the reconstruction algorithms field. One particular example is described where CT raw data is acquired and then parallel programming will be applied to obtain CT images at very low cost, improving quality and reducing reconstruction time. View full abstract»

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  • Design of a Transcutaneous Electrical Stimulator to Avoid the Postoperative Intestinal Effects

    Page(s): 90 - 93
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2481 KB) |  | HTML iconHTML  

    The postoperative intestinal obstruction is an illness characterized by a partial or complete interruption of the intestinal transit, due to adhesions that appear thus a surgical abdominal intervention in 88% of the cases. The 42% of these cases must undergo a surgical experience for the liberation of the adhesions. Unfortunately, whether the adhesions are excised, an inflammatory process will begin; which is the base for the genesis of new adhesions, creating a vicious circle very difficult to interrupt. Therefore, a different treatment for the intestinal postoperative obstruction is proposed by establishing this hypothesis: "After an abdominal intervention; if an electrical stimulation therapy was applied to return the motility of the small bowel, the adhesive growth would be prevented?". Hence, a transcutaneous electrical stimulator was developed for recovering gastrointestinal motor activity; with perspectives to find a new treatment for the prevention of postoperative effects. The constructed electrical stimulator was tested on two male dogs, and the obtained results were successful. The contraction of the small intestine was achieved by the applied electrical stimulation therapy. The outcomes are not completely successful and the transcutaneous electrical stimulator validation has not been accomplished; but whether this idea was reliable, a new method would be found for the treatment of adhesions small bowel obstruction. View full abstract»

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  • Electrocardiograph of Twelve Derivations, Low Current Consumption, Powered and Communicated for USB

    Page(s): 94 - 97
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5235 KB) |  | HTML iconHTML  

    In this work we present the design and construction of a system for electrocardiography of twelve derivations, low power, suministred by Universal Serial Bus (USB) port, at same time the EKG signal is monitored in this port, the system consists on a circuit of three simultaneous channels that register the electric activity of the patient's heart in twelve derivations by a 10 terminals cable. The initial amplification is made using the instrumentation amplifier AD 620, continues with a filter of 0.05 Hz in low frequencies and 120 Hz for high frequencies. Once carried out this process the final amplification is made, the electric isolation is by magnetic type, the USB communications are made using a commercial acquisition data system (ADS) model USB-1208 FS that has a resolution of 12 Bits, the program and the control interface for the data acquisition and display of signals coming from the USB port, was developed for the Windows XP operating system, and it was written in DELPHI 7.0 language, the system is powered with 5 V, demands 25 mA, has a CMRR 97dB, input dynamic range of 4 mVplusmn5% and bandwith of 0.05 Hz at 120 Hz, that which make it appropriate to clinical diagnostic. View full abstract»

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  • On-line Simulation Tool for the Design and Analysis of Lower-limb Prosthetic Devices

    Page(s): 98 - 101
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4030 KB) |  | HTML iconHTML  

    This paper presents a new and practical simulation interface to design and analyze lower-limb prosthetic devices. The proposed tool simulates the gait of a lower limb amputee using a desired prosthetic device. It allows the analysis of simple passive devices or the testing of control algorithms for active prostheses. The results presented in this paper correspond to the use of this tool to test a Fuzzy Controller specially designed for an active transfemoral prosthesis. To validate the tool, the simulation results are compared with "real-life" experiments. View full abstract»

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  • An Efficient Architecture for Detection of Layered Space-Time Block Codes Based on QR Decomposition

    Page(s): 102 - 105
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2629 KB) |  | HTML iconHTML  

    A new architecture for detection of linear dispersion space-time codes (LDSTBC) over Rayleigh fading channels is presented. The LDSTBC scheme consists of one Alamouti space-time block code unit, plus two more antennas operating as two layers of V-BLAST in the transmitter. The LDSTBC receiver can operate with three or more antennas simultaneously. The proposed receiver is based on an ordered successive interference cancellation (OSIC) scheme and the QR decomposition, which leads to a suitable hardware implementation. It was designed for the zero-forcing (ZF) criterion; reduced complexity is achieved by means of an adequate rearrangement of the channel matrix elements. The detection scheme proposed is evaluated and compared with other similar reported proposals, assuming a channel without spatial correlation. View full abstract»

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  • Digital Channel Modeling through Chaotic Generators

    Page(s): 106 - 109
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5431 KB) |  | HTML iconHTML  

    Recently, digital channel modeling through chaotic generators has attracted strong interest at literature. Many of them refer to the generation of error detected time series from where we can obtain channel's statistics. In this paper we present a complete modeling of the error-gap distribution (EGD) statistic that helps us to know how the errors are distributed through the channel. Our principal aim was to generate error time series with statistics properties similar to those that we can obtain from a reference model, such as Markov chains based models. Under these considerations, we implemented these algorithms of error time series generation in a digital signal processor (DSP) using as reference three models of real digital channels from literature. View full abstract»

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  • Distributed Power Control Algorithms in the Uplink of Wireless Systerns

    Page(s): 110 - 113
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2804 KB) |  | HTML iconHTML  

    In this paper, the problem of power control in wireless systems using a distributed approach is analyzed. The uplink of a direct-sequence code-division multiple-access communication (DS-CDMA) system is studied in this work. The power control strategies are derived using classical design approaches (PID and dead-beat). It is concluded that the uplink channel variations do not destroy the stability of the feedback structures. However, the delays in the closed-loop paths can severely affect the stability and performance of the resulting feedback schemes. As a result, the control laws have to be selected according with the expected transmission delays in order to maximize the resulting performance. Simulation results are presented to compare the control algorithms using a standard single-step power correction approach. View full abstract»

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  • Sampling Reconstruction Procedure for a Markovian Gaussian Nonstationary Process in the presence of Jitter

    Page(s): 114 - 117
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2079 KB) |  | HTML iconHTML  

    The present work provides the conditional mathematic expectation rule in order to analyze the sampling reconstruction procedure of a Nonstationary process in the presence of jitter. Beta function is studied as a representation of jitter distribution. The sampled process is Markovian Gaussian. The error reconstruction function is investigated for nonstationary regime. View full abstract»

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  • Frequency Offset Estimation and Compensation Using Superimposed Training

    Page(s): 118 - 121
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2980 KB) |  | HTML iconHTML  

    We propose in this paper some methods to estimate and compensate for the harmful carrier frequency offset that could be present in pass-band wireless communications. Although there are efficient methods to estimate the frequency offset when training sequences are employed, our method exploits instead the presence of an implicit/superimposed training sequence. Implicit training schemes have been proposed before for the channel estimation task but they all assume a data communication link free of any frequency offset and they all fail in the case when this offset exists. It is therefore mandatory to estimate and compensate for this offset before proceeding to use the channel estimation methods already available in the open literature as a previous step for the ultimate goal of data recovery. View full abstract»

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  • HAP-Based Monitoring of the Emissions Produced by Terrestrial Microwave Systems

    Page(s): 122 - 125
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3212 KB) |  | HTML iconHTML  

    A new alternative in the context of radio monitoring is presented in this paper. The proposed approach is to use high altitude platforms (HAP) as monitoring stations provided their relatively large coverage and moderate path loss. Emissions produced by point-to- point links of terrestrial microwave stations located in Mexico City are simulated in order to illustrate the feasibility of HAP as monitoring station. Both free space and rain conditions are considered. Obtained results show that a mobile HAP represents a very attractive alternative for monitoring purposes, not only due to the acceptable reception levels, but also for its potential implementation in practice. View full abstract»

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  • Improved Carrier Frequency Offset Estimation using Data-Dependent Superimposed Training

    Page(s): 126 - 129
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2872 KB) |  | HTML iconHTML  

    rdquoWe address the problem of carrier frequency offset (CFO) estimation within the Data Dependent Superimposed Training (DDST) framework for channel estimation. A CFO estimator was recently developed for DDST, which uses two different data dependent training sequences, one for CFO estimation and other for channel estimation. Here, we propose a CFO estimation scheme which combines the estimates using both the data-dependent training sequences to improve the performance. Finally, simulations are presented that verify the theoretical developments. View full abstract»

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  • 160 Gb/s XOR Gate Using Bulk SOA Turbo-Switched Mach-Zehnder Interferometer

    Page(s): 134 - 137
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2705 KB)  

    A modified Mach-Zehnder interferometer is proposed to carry out photonic XOR operation between optical data streams. It consists of the synthesis of a differential scheme and the recently demonstrated turbo-switch. Simulations utilizing a sophisticated bulk semiconductor optical amplifier dynamical model indicate practically error-free operation at 160 Gb/s. A comparison of the proposed structure with a state-of-the-art XOR gate shows outperformance of the former in terms of Q-factor, thus positioning the new device as a very attractive alternative design for logic XOR functionality. Application as ultra-fast processing element on forthcoming optical telecommunication networks is foreseen. View full abstract»

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  • Distributed Power Control Performance in DS-CDMA Systems with Adaptive Quantization

    Page(s): 138 - 141
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2916 KB) |  | HTML iconHTML  

    One practical constraint imposed on closed-loop power control algorithms for a direct-sequence code-division multiple-access communication (DS-CDMA) system is the limited amount of feedback information. This paper proposes a closed-loop power control scheme with adaptive quantization on the basis of the number of power command bits. Adaptive quantization is used on the hypothesis that the quantization sensitivity can be defined as a function of the standard deviation of the reference error signal, while maintaining the feedback number of bits constant. Simulation results are presented to illustrate the performance of a distributed power control (DPC) scheme with adaptive quantization, using a classic proportional integral derivative (PID) power update. Moreover, the performance of the DPC algorithm with fixed quantization is also presented. Finally, both schemes are compared with the standard single-step power correction scheme. View full abstract»

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  • Linear Dispersion Codes Generation from Hybrid STBC-VBLAST Architectures

    Page(s): 142 - 145
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2733 KB) |  | HTML iconHTML  

    Hybrid MIMO systems are defined as a combination of architectures designed to achieve both multiplexing gain (such as VBLAST), and diversity gain, (such as STBC). In these systems the detection can be performed with an ordered successive interference cancellation (OSIC) based on SQRD algorithm, in which the layers with diversity are decoded first. In this paper we introduce a new way to represent hybrid systems, in which the detection process is carried out in a unified manner for both spatial and diversity transmitted symbols, using an OSIC algorithm, but symbol by symbol, just as single VBLAST systems performs. We show that within this approach, linear dispersion (LD) coding has been actually generated, that allows the use of LD theory to determine the performance achieved by the hybrid system. Therefore a bridge between hybrid systems and LD codes has been established. View full abstract»

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  • Multi-Class Support Vector Machines for Large Data Sets via Minimum Enclosing Ball Clustering

    Page(s): 146 - 149
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2826 KB) |  | HTML iconHTML  

    Support vector machines (SVM) for binary classification have been developed in a broad field of applications. But normal SVM algorithms are not suitable for classification of large data sets because of high training complexity. This paper introduces a novel two-stage SVM classification approach for large data sets: minimum enclosing ball (MEB) clustering is introduced to select the training data from the original data set for the first stage SVM, and a de-clustering technique is then proposed to recover the training data for the second stage SVM. Then we extend binary SVM classification to case of multiclass. The novel two-stage multi-class SVM has distinctive advantages on dealing with huge data sets. Finally, we apply the proposed method on several benchmark problems, experimental results demonstrate that our approach have good classification accuracy while the training is significantly faster than other SVM classifiers. View full abstract»

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  • Qubits structure and coherence in a one-way quantum computer

    Page(s): 150 - 152
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1765 KB) |  | HTML iconHTML  

    Present days efforts for building up an operative quantum computer made of silicon soon they will take shape. One of the main challenges to this task is to implement qubit coherence in a practical way. We make emphasis in some physical characteristics (such as the structure) of the basic components (qubits) of a silicon one-way quantum computer which can be exploited in order to implement qubit coherence. Altogether with this, we introduce form factors (accounting for the qubit structure), and calculate times of coherence. It is found that the nuclei states last longer than their electronic counterpart. However, this stability of nuclei qubits limits the speed at which the computer can carry out instructions and process the information. View full abstract»

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  • A method for designing CNN templates

    Page(s): 153 - 156
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2231 KB) |  | HTML iconHTML  

    Cellular neural networks (CNN) are very useful for image processing tasks [1],[2]. One problem with CNN networks is the lack of a programming method to realize a processing task. The cloning templates entirely specifies the programming of a CNN net. There are a lot of cloning templates for several tasks [3]-[4], got by mathematical analysis or heuristically [4]-[9]. However for some specific tasks is very difficult to find the correct templates. In this paper a procedure for finding cloning templates for image processing tasks is described, using a gradient method. A set of CNN templates obtained using the proposed procedure is shown. View full abstract»

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