INTERNATIONAL JOURNAL OF ENGINEERING
Year:2013 | Volume:26 | Issue:3 (TRANSACTIONS C: ASPECTS)|Papers Count:12

This paper presents both, the design and development of a monitoring and control system via web for a closed microalgae crop and the results that were obtained using the strain Haematococcus pluvial is. The research was done at Universidad de La Sabana (Colombia) and it aimed at quantifying the growth kinetics associated with the increment of biomass and the development of red pigment inside the cells when exposed to different wavelengths (l), constant temperatures, agitation and cycles of light/darkness over the crop. It was found that for short wavelengths (470nm-blue light) the cell size, the quantity of red pigment and the growth kinetics were higher than the crop illuminated with green light (525nm). All of the above was established thanks to SICOMOAL system which allowed real time control and monitoring without human interference. This increases the reliability of the bioprocess data and gains more efficiency in this kind of research.

There are different schemes for streamed audio video (AV) IPTV content across mobile WiMAX to reduce packet loss and latency. The objective of this paper is to verify the effectiveness of forward error correction (FEC) techniques and to suggest the techniques for robustness problems and to analyze the issues either due to AV coding encoding or due to access network. The paper concentrates on handoff and handover delay, mobile WiMAX downlink burst mapping and the reliability of IPTV over LTE system.

Question and answering service is one of the popular services in the World Wide Web. The main goal of these services is to find the best answer for user's input question as quick as possible. In order to achieve this aim, most of these use new techniques foe question matching. We have a lot of question and answering services in Persian web, so it seems that developing a question matching model might be useful. This paper introduces a new question matching model for Persian. This model is based on statistical language model and employs generalized bigram and trigram model. We also describe some results regarding the employment of natural language processing in question matching model. Most of the Q & A services have large number of questions and answers, hence we considered an optimized implementation for the model. We evaluated our model with Rasekhoon question and answering archive which contains about 18000 pairs of questions and answers. The results showed the improvement of precision and recall measures through using this model.

The investigation presented in this paper is a novel method in question answering (QA) that enables a QA system to gain performance through reuse of information in the answer to one question to answer another related question. Our analysis shows that a pair of question in a general open domain QA can have embedding relation through their mentions of noun phrase expressions. We present methods for recognition of embedding property between a pair of questions by focusing on the techniques applied to match noun phrase mentions in the questions. We then take advantage from the discovery of embedding relationship and extract referent named entities corresponding to the noun phrase expression that are present in the answer of one question. The named entities will then be used as significant terms in the query generation phase of the QA system to retrieve more pertinent answers. Finally, we discuss on data set resources and system evaluation.

An important problem in nonlinear science is estimation of unknown parameters in Loranz chaotic system. Clearly, the parameter estimation for chaotic systems is a multidimensional continuous optimization problem, where the optimization goal is to minimize mean squared errors (MSEs) between real and estimated responses for a number of given samples. The Bees algorithm (BA) is a new member of meta-heuristics. BA tries to model natural behavior of honey bees in food foraging. This paper focuses on using the BA to solve this problem. Simulation results demonstrate the merit, effectiveness and robustness of BA.

The design of a novel volcano smoke antenna for UWB indoor applications is presented. The design method is based on a general description for the geometry of UWB monopole antennas which is capable of producing most possible shapes for these antennas. It is also compatible with different optimization methods. In addition to a volcano smoke antenna, this method is used to design two optimized monopole antennas with flat and shaped grounds. The optimization of antennas is carried out by applying a hybrid procedure which begins with a GA global search and completes with a local search. The optimization process aims at minimizing the reflection coefficient of antennas over the operating band while reducing the time-domain distortion of radiated pulses. For Shaped ground and volcano smoke antennas, the reduction of variations in the energy pattern has been added to the optimization goals. The numerical results show the reliability and effectiveness of the whole process. These results also show considerable improvement regarding the size and operational characteristics of the antenna in comparison with similar antennas reported in the literature. The operational characteristics of shaped ground and volcano smoke antennas show that by shaping the ground, better performance could be achieved with smaller radiating elements and ground planes.

Diversity combining techniques play an important role in combating the destructive effects of channel fading in wireless communication systems. In this work, we present a blind diversity combining technique for Rayleigh flat fading channels based on Hammerstein type filters. We show that the performance of this technique is very close to ideal MRC system which is accepted as an optimum receiver over fading channels in presence of AWGN. This is a valuable result especially because higher bandwidth efficiency is also achieved as compared with MRC. We also show that in our proposed technique the variation of the combiner output values around the values of transmitted symbols is less than the corresponding variation in MRC system. Hence, for soft decision applications it is superior to MRC technique.

This paper presents the performance of multi-phase voltage source inverter (VSI) with simple PWM switching techniques, namely the harmonic injection and offset injection method. The technique discussed in this paper is easy to implement and avoid complicated controlling algorithm adapted in SVPWM technique. The generalized switching techniques are proposed in this paper. A generalized algorithm suitable for odd number of phases is developed in Matlab/Simulink environment and discussed in detail for both the switching methods. The performance of the 5, 7 and 9-phase VSI is studied with the above-said switching methods. The results of the simulation are presented for different modulation indices and a comparison in terms of fundamental voltage and THD identifies the better scheme suitable for multi-phase inverter fed drives.

In this paper, analytical analysis of capacitive pressure sensor with clamped diaphragm is presented. Mechanical and electrical properties of the sensor are theoretically analyzed based on theory of thin plates with small deflection and the results are evaluated using finite element analysis. The central deflection and capacitance values under uniform external pressure are calculated. Comparison of theoretical results shows good agreement with finite element analysis. The results indicate that the mathematical model has a high accuracy to determine the sensor behaviors.

In this work, a low power, low voltage and high gain operational amplifier is proposed. For this purpose, a negative resistance structure is used in parallel with output to improve the achievable gain. Because of using self cascode transistors in the output, the proposed structure remains approximately constant in a relatively large output voltage swing causing an invariable gain. To evaluate the proposed method an op amp was designed in 0.18mm CMOS technology. The simulation results showed a gain of 84dB, unity gain bandwidth of 12.45MHz and phase margin of 81 degree, with 1V power supply and 1pF load capacitor.

The Dynamic Voltage Restorer (DVR) is a commercially available, popular device to eliminate voltage sags and swells in the distribution lines. Its basic function is to inject the voltage difference (difference between the pre-sag and sag voltage) to the power line and maintains the pre-sag voltage condition in the load side. The efficiency of the DVR depends on the performance of the efficiency control technique involved in switching the inverters. Z-source inverters are recent topological options proposed for buck–boost energy conversion with a number of possible voltage- and current-type circuitries. Common feature noted is their inclusion of an LC impedance network, placed between the dc input source and inverter bridge. This impedance network allows the output end of a voltage-type Z source inverter to be shorted for voltage boosting without causing a large current flow and the terminal current of a current-type inverter to be interrupted for current boosting without introducing over voltage oscillations to the system. Therefore, Z-source inverters are, in effect, safer and less complex and can be implemented using only passive elements with no additional active semiconductor needed. This paper presents a selective harmonic elimination using flying capacitor connection in Z-source inverter. Closed loop control for a simple system is modeled and simulated using MATLAB software. The simulation results are presented to demonstrate the effectiveness of the proposed DVR system.

Multi-supply voltage design using Cluster Voltage Scaling (CVS) is an effective way to reduce power consumption without performance degradation. One of the major issues in this method is performance and power overhead due to insertion of Level Converting Flip-Flops (LCFF) at the interface from low supply to high-supply clusters to simultaneously perform latching and level conversion. In this paper, an improved version of clocked pseudo-NMOS LCFF called Clock Branch Sharing pseudo-NMOS LCFF has been proposed, which combines the Conditional Discharge technique, pseudo-NMOS technique and Clock Branch Sharing technique. Based on Simulation results, the proposed flip-flop exhibits up to 32.5% delay reduction and saves power up to 8.1% as compared to clocked pseudo-NMOS LCFF.