S. S. Jamuar

FGMOS based wide range low voltage current mirror and its applications

Low voltage current mirror (LVCM) based on floating gate MOSFET (FGMOS) has been presented in this paper. The LVCM has output current range of 100 nA to 500 /spl mu/A, high output resistance (1.35 M/spl Omega/ at 500 /spl mu/A), high bandwidth (500 MHz) and low input compliance voltage (0.4 V at 20 /spl mu/A input current and 0.6 V at 300 /spl mu/A input current). The LVCM design has been verified using P-Spice for 0.5 /spl mu/m technology and the error in current transfer is observed to be less than /spl plusmn/0.1%. Simulations have also been carried out for p-type LVCM and bipolar LVCM.

Robust speech recognition using harmonic features

In this study, the authors propose a speech recognition system using harmonic structure related information to detect harmonic features in noisy environment. The proposed algorithm first extracts the harmonic components contained inside the speech signals using sine function convolution. By setting the frequency of the sine function as equal to the fundamental frequency of speech signals, harmonic components can be extracted out. The reconstructed signal obtained by summing up the extracted harmonic components is found to have a high degree of correlation with the original signal. The extracted frame energy measure of the harmonic components has been further processed to become dynamic harmonic features and then used together with the European Telecommunications Standards Institute (ETSI) front-end processed mel-frequency cepstral coefficients (MFCC) feature or the perceptual linear prediction (PLP) feature in the speech recognition system. The proposed enhanced speech recognition system shows a better recognition rate over the ETSI front-end processed MFCC (or PLP)-based speech recognition system.

Performance Analysis of TCP with Delayed Acknowledgments in Multi-hop Ad-hoc Networks

The acknowledgment strategy has great potential to increase TCP throughput when it runs over 802.11 MAC protocol. In particular, TCP acknowledgments (ACK) carry out an extensive number of medium accesses as they compete in the same route as data packets for media. In this paper, we first propose a dynamic TCP-MAC interaction strategy which tries to reduce the number of induced ACKs by monitoring the channel condition. To this end, the total collision probability collected along the path from sender to receiver in MAC layer has been used to properly set the number of delayed ACKs (DA) in TCP. Based on the estimated collision probability, TCP sender dynamically adjusts itself to the channel condition by delaying less ACKs in high traffic conditions and more ACKs in low traffic conditions. The simulation results show a throughput improvement up to 15% over the existing method called Dynamic Adaptive Acknowledgment (TCP-DAA) and much more over the regular TCP in different scenarios dealing with a dynamic loss rate. In addition, we show that our proposed strategy does not always benefit from a fixed delay policy along with a fixed congestion window size. In fact, the optimal number of delayed ACKs is based on the path length of a TCP connection and a large delay window may solely improve TCP throughput in short ranges with less number of flows. However, in a longer path congestion window limit provides more throughput gain.

A low voltage current mirror based on quasi-floating gate MOSFETs

A low voltage current mirror based on quasi-floating gate MOSFET (QFGMOS) is presented. The use of QFGMOS eliminates the limitations associated with floating-gate MOSFET (FGMOS) structures like increased silicon area, initial charge trapped in the floating gates and gain-bandwidth product degradation. The proposed current mirror based on QFGMOS has a current range up to 500 µA with offset of 10 pA, exhibits high bandwidth of 640 MHz, input resistance of 480 Ω, output resistance of 1.67 GΩ, unity current transfer ratio and dissipates 1.5 mW power. A resistive compensation has also been employed to increase the bandwidth up to 1.3 GHz.

COMBINE HARVESTER INSTRUMENTATION SYSTEM FOR USE IN PRECISION AGRICULTURE

A crop yield and field performance mapping system for New Holland TC-56 rice combine harvester (RCH) for precision agriculture applications has been developed using LabVIEW. A Dewe-2010 PC data acquisition system has been used as a core unit to collect and store the real time field data from different sensors and a differential global positioning system to determine the exact latitude, longitude, and altitude of RCH. Modular software allows programming flexibility in developed hardware. The spatial information has been measured and recorded in real time field testing. Sensors have been calibrated in a laboratory under specific conditions, and excellent measurement linearity has been obtained for most of parameters. The crop and yield performance maps have been obtained in real time from the field tests conducted in Malaysia. These maps will be used in precision agriculture to improve areas of low yield and to improve productivity of rice.

Development and Simulation of Biochemical Reactor by Using MATLAB

This research, an attempt has been made to develop and simulate a process model to describe the biochemical process. Three important parameters that are desired to be controlled in the biochemical reactor are pH, dissolved oxygen (DO) and temperature. In earlier process model presented in literature, the effect of pH and DO change during process implementation is not taken into account. In this research, the biochemical reactor model was modified to include the effect of pH and DO with temperature. The new model contains those three parameters, which are mentioned before. The biochemical reactor model was implemented in MATLAB Ver 7.5 by using an S-function.

Bioreactor profile design and optimization for ethanol production

Ethanol is an alternative energy source being used now a daysto replace diesel and petrol. By fermentation of glucose using Saccharomyces yeasts under a controlled environment, ethanol is produced. The temperature, dissolved oxygen (DO) and pH in bioreactor must follow desired profiles to give optimum yield. In this paper the process model for yeast fermentation has been described in terms of temperature, pH and dissolved oxygen. The temperature in bioreactor has been controlled by using nonlinear Autoregressive - moving average (NARMA) neuro controller. The two degree of freedom (2DOF) PID controllers have been used for pH and dissolved oxygen control. Levenberg-Marquardt training algorithm has been used to train NARMA neuro controller. The 2DOF-PID controllers have been tuned by MATLABs auto tune feature along with manual tuning. Random profile variations have been used for simulation to study the dependence of ethanol on process parameters. An overall increase was noted in the production of ethanol. The performance of the controllers for following desired random profiles has also been shown in contrast with prior researches. The performance of the controllers for following the desired random profiles has shown overall improvement in controlling the process.

A Novel Ternary CDMA Code for TPSK Modulation Scheme

In code division multiple access (CDMA), two or more chips are grouped together to form symbols and each symbol is transmitted during the symbol period. The phase shift keying (PSK) modulation techniques map the digital baseband data into two or more possible signals by varying the phase of a radio frequency (RF) carrier. The recently proposed PSK scheme called ternary PSK (TPSK) scheme can convey three possible symbols. In this paper, a novel ternary based CDMA sequence so-called large area synchronous even ternary (LAS-ET) sequence is introduced to increase spectrum efficiency in TPSK scheme. Its sequence duty ratio and cross-correlation are analyzed. The performance analysis of this sequence is compared with the large area synchronous (LAS) sequence in term of symbol error rate and chip error rate (CER) over various channel models. It is shown that TPSK scheme in LAS-ET sequence outperforms LAS sequence in terms of CER evaluation. At the same time, the spectrum efficiency is doubled when a pair of chips in LAS-ET sequence is mapped into one symbol.

Improved FGMOS-based low-voltage voltage follower

The use of floating-gate MOSFETs (FGMOS) in designing low-voltage analog circuits is presented. A FGMOS based low-voltage voltage follower and its use in CCII structures is presented. Working of such CCII structures is ascertained by using them in current-mode and voltage-mode band-pass simulated filters.