A comparative study between x-rays and gamma-rays irradiation on electrical characteristics of bipolar junction transistors (BJTS)

Irradiation impact of gamma rays and X-rays on bipolar junction transistors (BJTs) in terms of electronic excitation due to transfer of energy and subsequent ionization, as well as energy transfer to atomic nuclei is studied using in-situ method. Comparison is made on the electrical characteristics of the devices under test (DUT) for various collecting current at two different operating mode. Both temporary and permanent damages in DUTs are found to be induced by energy transfer from the irradiation by gamma-rays and X-rays, depending upon total dose absorbed and current drive. Increased probability of recombination, due to creation of electron–hole pairs at the base region is found to be the most significant radiation damage in BJTs, as it leads to decrease in electron flux reaching the collector region

A new multistage lattice vector quantization with adaptive subband thresholding for image compression

Lattice vector quantization (LVQ) reduces coding complexity and computation due to its regular structure. A new multistage LVQ (MLVQ) using an adaptive subband thresholding technique is presented and applied to image compression. The technique concentrates on reducing the quantization error of the quantized vectors by "blowing out" the residual quantization errors with an LVQ scale factor. The significant coefficients of each subband are identified using an optimum adaptive thresholding scheme for each subband. A variable length coding procedure using Golomb codes is used to compress the codebook index which produces a very efficient and fast technique for entropy coding. Experimental results using the MLVQ are shown to be significantly better than JPEG 2000 and the recent VQ techniques for various test images

Multiple Description Coding Using A New Bitplane-LVQ Scheme.

In this paper, a novel Bitplane-LVQ technique to compress subbands bitplane coefficients is proposed for multiple description coding (MDC) system

Optical Fiber Bending Detection on Long Distance OPGW using OTDR

In Malaysia, thousands of kilometers of Optical Ground Wire (OPGW) have been installed by a utility company. For long distance fiber cable, there is a possibility of optical fiber to bend with very small radius especially in joint closures which caused optical power to attenuate. This attenuation is known as ‘bend losses. Bend loss increases the total power attenuation of optical fiber. In addition, for long distance fiber cable, it is important to avoid any extra loss as the fiber itself attenuates 0.2 to 0.35 dB/km and splice loss about 0.1 dB each. Hence, in this study, the method of detecting bend loss as well as optical fiber bending is presented. The result of this study is expected to allow fiber industry players to determine the exact location and proper rectification can be done to solve bend loss problem

Study: The Performance FFT and Wavelet Packet of OFDM Systems from through Demonstrated Numerical Examples

A major goal of the next-generation wireless communication systems is the development of a reliable highspeed wireless communication system that supports high user mobility. Multi-Carrier Modulation (MCM) technique is an attractive approach for high-speed digital radio communication systems in order to achieve a high spectral efficiency and to combat the frequency selectivity of the channel. Orthogonal frequency division multiplexing (OFDM) is a kind of MCM techniques. As proven by the success of OFDM, multicarrier modulation has been recognized as an efficient solution for wireless communications. Waveform bases other than sine functions could similarly be used for multicarrier systems in order to provide an alternative to OFDM. Wavelet Packet Modulation (WPM) was proposed as one of the multicarrier transmission methods like OFDM. Since it is a multicarrier transmission method. In this paper, we study the performance of FFT-OFDM and wavelet Packet (WP)- OFDM from through demonstrated numerical examples, and evaluation of FFT-OFDM and DWPT-OFDM in AWGN channel , Flat fading channel and Selective Fading Channel

Development of Seebeck-Coefficient Measurement Systems Using Kelvin-Probe Force Microscopy

Thermoelectric device is investigated by a number of researchers in order to enhance the thermoelectric efficiency. It is known that the efficiency can be improved by quantum effect. However, it is difficult to measure the thermoelectric characteristics of nanometer-scale structures. Thus a new measurement method is expected to be developed. We propose to apply Kelvin-probe force microscopy (KFM) to characterization of thermoelectric materials. KFM can locally observe surface potential of Fermi energy of a sample without touching the sample surface. In the present paper, we estimate the Seebeck coefficient of thin Si-on-insulator layers using KFM

Factors affecting endoglucanase production by Trichoderma reesei RUT C-30 from solid state fermentation of oil palm empty fruit bunches using Plackett-Burman design

A study was conducted to screen parameters affecting the production of endoglucanase by Trichoderma reesei RUT C-30 on solid state fermentation of oil palm empty fruit bunch using the Plackett-Burman design. Factors involved in the screening process were peptone concentration, urea concentration, ammonium sulfate concentration, calcium nitrate concentration, yeast extract concentration, tween 80 concentration, pH, incubation time, initial moisture content, inoculum size and substrate amount. Through analysis of variance (ANOVA), it was found that initial moisture content (p= 0.001), incubation time (p= 0.001), inoculum size (p= 0.032) and ammonium sulfate concentration (p= 0.023) have been recognized as significant factors affecting endoglucanase activity in solid state fermentation (SSF) of oil palm empty fruit bunch (OPEFB) by T. reesei RUT C-30. The model established from the ANOVA analysis have a significant value of Pmodel>F= 0.0008 and R2 of 0.9132. The preoptimized media showed 2.6 fold increased of endoglucanase activity.Key words: Cellulase, oil palm empty fruit bunches, solid state fermentation, Trichoderma reesei RUT C-30, Plackett-Burman design

Impact of physico-chemical parameters on the physiological growth of Arthrospira (Spirulina platensis) exogenous strain UTEXLB2340

Spirulina platensis is an attractive human food supplement, animals feed and of numerous medicinal uses. The effect of physico-chemical factors on the physiological growth rates as optical densities (O.D.) of S. platensis strain (UTEXLB2340) were investigated. Experiments were conducted at different pH levels, light intensities, and temperature regimes, and monitored for 20 days. The half concentration of Zarrouk media was found to be suitable for cultivation of this strain under indoor (1.14 O.D.) and outdoor conditions (0.99 O.D.). The nitrogen source sodium nitrate (2.5 gl-1) can be replaced by inexpensive and low concentration of urea fertilizer (0.12 gl-1). The growth rates of this strain were optimum at light intensities of 1500 to 2500 lux of continuous light (0.99 to 1.71 O.D.) or 2500 lux of intermittent light (1.32 O.D.). The optimal growth was recorded at lower pH 7 to 8 (1.19 to 1.76 O.D.), and temperature of 25 to 35°C (1.13 to 1.71 O.D.). Therefore, this microalga can be cultivated for commercial uses in the available natural ponds where the average temperature reached 30°C and light intensities fluctuated between 1000 to 4000 lux in the morning, 12,000 to 22,000 lux midday, and 7000 to 10,000 lux in the noon.Keywords: Arthrospira (Spirulina) platensis, indoor and outdoor cultures, light intensity, pH, sodium nitrate, temperature, urea.African Journal of Biotechnology Vol. 12(35), pp. 5458-546