Nondestructive and noncontact dielectric measurement methods for transformer oil using free-space microwave measurement system in 19 25 GHz frequency range

Nondestructive, noncontact and real time evaluation of dielectric properties of low-loss liquids are important for applications such as service-aged transformer oil, biomedical, remote sensing and design of radar absorbing material. Free-space methods were developed to measure dielectric properties of low-loss liquids at microwave frequencies. Metal-back method was developed for Freespace Microwave Measurement system (FSMM). The purpose of this research is to measure the dielectric properties of transformer oil by using free-space microwave measurement system between 18 – 26 GHz (K-band), to compare measured results with published results for transformer oil and to collect the variation values of dielectric properties in microwave frequency between 18GHz to 26GHz (k-band). FSMM system consists of spot focusing horn lens antennas, mode transitions, coaxial cables and vector network analyzer (VNA). Dielectric constants and loss factors were measured for new transformer oil and all results close agreed with published data. It is observed that metalback method is suitable for dielectric measurement of transformer oil

Detection Of Defects On Weld Bead Through The Wavelet Analysis Of The Acquired Arc Sound Signal

Recently, the development of online quality monitoring system based on the arc sound signal has become one of the main interests due its ability to provide the non-contact measurement. Notwithstanding, numerous unrelated-to-defect sources which influence the sound generation are one of the aspects that increase the difficulties of applying this method to detect the defect during welding process. This work aims to reveal the hidden information that associates with the existence of irregularities and porosity on the weld bead from the acquired arc sound by applying the discrete wavelet transform. To achieve the aim, the arc sound signal was captured during the metal inert gas (MIG) welding process of three API 5L X70 steel specimens. Prior to the signal acquisition process, the frequency range was set from 20 Hz to 10 000 Hz which is in audible range. In the next stage, a discrete wavelet transform was applied to the acquired sound in order to reveal the hidden information associated with the occurrence of discontinuity and porosity. According to the results, it was clear that the acquired arc sound was not giving an obvious indication of the presence of defect as well as its location due to the high noise level. More interesting findings have been obtained when the discrete wavelet transform (DWT) analysis was applied. The analysis results indicate that the level 8 of the approximate and detail wavelet coefficient have given a significant sign associated with the presence of irregularities and porosity respectively. Moreover, despite giving the information on the surfaces pores, the detail wavelet coefficient was found to give a clear indication of the sub-surface porosity formation during welding process. Hence, it could be concluded that the hidden information with respect to the occurrence of discontinuity and porosity on the weld bead could be obtained by applying the discrete wavelet transfor

Analysis of crown spectral characteristic and tree species mapping of tropical forest using hyperspectral imaging.

Airborne hyperspectral remote sensing in Malaysia is relatively new. The advantage of hyperspectral remote sensing over satellite remote sensing is its ability to take high spatial resolution images. In this study, hyperspectral data were used for classification of individual tree crowns in a tropical rainforest. Field spectroradiometer and airborne hyperspectral reflectance spectra (288 bands, 500-850 nm) were acquired from eight species of emergent tree crown in Gunung Stong Forest Reserve, Kelantan, Peninsular Malaysia. Analyses focused on tree crown spectra in a 5 ha plot. Firstly, the spectral characteristic of the tree crown was developed. Next, spectral-based species classifications were performed using spectral angle mapper (SAM) classifiers. Optimal regions of the spectrum for species discrimination varied with scale. Near-infrared (700-850 nm) bands were consistently important regions across all scales. However, the band in the visible region (537-700 nm) was also important at crown scales. This study concluded that high spectral and spatial resolution imagery acquired over tree crown canopy of tropical forest has substantial potential for individual tree species mapping

Identification of Phytophthora spp. from perennial crops in Malaysia, its pathogenicity and cross-pathogenicity

Phytophthora is one of the most important plant pathogens of perennial crops in the tropics. This study characterised the pathogen(s) responsible for cocoa black pod rot, rubber pod rot and durian stem canker. Eighteen Phytophthora isolates were collected from several states in Malaysia, namely Pahang, Johor and Selangor. A total of 12 Phytophthora palmivora and six Phytophthora nicotianae isolates were isolated and identified based on the morphological and molecular characteristics. Internal transcribed spacer (ITS) sequences enabled Phytophthora identification to species level. Inoculation of 18 isolates on detached leaves and unripen cocoa pods successfully demonstrated the progressive development of lesions on its original host. Lesions were also observed in all wounded detached leaves of young durian (clone D24) and rubber (clone RRIM600) and unripen cocoa pods (clone BAL244) regardless of host and isolates. Phytophthora isolates from durian (DSCI) and rubber (R4A) used to inoculate cocoa pods exhibited lesion sizes of 11.6±0.75 and 9.6±0.64 mm, respectively. However, Phytophthora isolates from cocoa (CPR25) developed a longer length of lesion of 18.6±0.47 mm. On durian leaves, Phytophthora isolate from rubber (R4A) and cocoa (CPR25) recorded 11.73±1.04 and 5.22±0.57 mm length of lesion while Phytophthora isolates from durian (DSCB4) produced 13.13±1.29 mm lesion on its native host. Isolates from cocoa (CPR22) and durian (DSCE3) infected rubber leaves with 3.74±0.48 and 2.55±0.31 mm length of lesion, in comparison to rubber isolates (R1B) with 5.43±0.23 mm length of lesion. Differences in the length of lesion demonstrated higher level of virulence on the native host

An Engineering Ethics Case Study Review: Petrobras P-36 Accident

In 2001, the world largest oil production in the coast of Brazil was sank due to the series of explosions. This accident claimed 11 lives of crew members and 1 of 4 main support columns affected and lame. The purpose of this case study is to learn from previous experience about the engineering failure from engineering ethics viewpoints which cover the responsible of an engineer to keep safety of people around and maintain of environmental care

Modified EDF Goodness of Fit Tests for Logistic Distribution under SRS and RSS

Modified forms of goodness of fit tests are presented for the logistic distribution using statistics based on the empirical distribution function (EDF). A method to improve the power of the modified EDF goodness of fit tests is introduced based on Ranked Set sampling (RSS). Data are collected via the Ranked Set Sampling (RSS) technique (McIntyre, 1952). Critical values for the logistic distribution with unknown parameters are provided and the powers of the tests are given for a number of alternative distributions. A simulation study is presented to illustrate the power of the new method

A putative probiotic isolated from hatchery reared juvenile Penaeus monodon

Probiotic is considered as a remedy to solve disease problem in shrimp aquaculture. Shrimp body and environment bacterial flora are recommended as reliable source for extracting of beneficial bacteria. Therefore, 5000 pieces of post larvae of Penaeus monodon were distributed equally in 4 tanks in probiotic and antibiotic free condition up to juvenile. Then microbiological samples from digestive system, muscles, body surface, rearing water and tank sediment were inoculated onto the selective media plates. Incident of total bacteria, Vibrio, Pseudomonas and Entrobacteriaceae were evaluated in different body parts and rearing environment of shrimp. The highest bacteria count for total bacteria, Vibrio, Pseudomonas was occurred in sediment followed by digestive system. No Entrobacteriaceae was observed from all samples. Isolated bacteria were identified and placed in 7 genera consisted of Vibrio, Shewanella, Burkholderia, Clavibacter, Staphylococcus, Brevibacterium, Corynebacterium, while one genus remained unidentified. Genus Shewanella exhibited highest frequent bacteria in digestive system of P. monodon which may be indicated its ability to colonization in digestive system. Shewanella algae was selected from whole isolated bacteria as candidate probiotic via well plate diffusion technique and cross streak antagonistic test against Vibrio harveyi, V. parahaemolyticus and V. alginolyticus. It was able to digest lipid and protein in tributyrin agar and skim milk agar

Numerical evaluation of thermo-hydraulic performance in fin-and-tube compact heat exchangers with different tube cross-sections

This study examined numericallythe Thermal-hydrodynamic properties of airflow in the fin-and-tube compact heat exchangers (FTCHEs) with considering different shapes of tubes in lowReynoldsnumbers. The influence of applying flat, oval and circular tube adjustments on the thermal and hydraulic characteristics of air flow were analyzed on the in-line tube arrangements. Establishing standard conditions, the study compared different geometries based on circular tubes of 10.459 mm diameter tubes with 25.4 mm longitudinal pitches and 25.4 mm transverse pitches. The other geometries of tubes were assumed in a stable and constant state preparing the same heat transfer surface area per unit volume as that of the nominal case. The results showed that the FTCHE with flat tubes gives the best area goodness factor (j/f) with in a certainrange of Reynoldsnumbers. In addition, FTCHE with flat tubes shown the best thermo-hydraulic performance and a significant augmentation of up to 10.83% and 35.63% in the average area goodness factor achieved accompanied by a decrease in the average friction factor of 17.02% and 43.41% in the flat tube case compared to the oval and circle tube shapes, respectively. It is concluded that the average area goodness factorfor the oval tube is about 25.04% higher than that of the circular tube, while the average friction factor for the oval tube is about 26.9% lower than that of the circular tube. This means that the flat tube has a better-combined thermal-hydraulic performance than the oval and circle tube

Digestion of rice straw and oil palm fronds by microflora from rumen and termite bacteria, in vitro.

The digestion and Volatile Fatty Acid (VFA) production from rice straw and oil palm fronds by cellulolytic bacteria isolated from the termite Coptotermes curvignathus were investigated. The bacteria were Acinetobacter strain Raminalimon, Enterobacter aerogenes strain Razmin C, Enterobacter cloacae strain Razmin B, Bacillus cereus strain Razmin A and Chryseobacterium kwangyangense strain Cb. Acinetobacter strain Raminalimon is an aerobic bacterium, while the other species are facultative anaerobes. There were significant differences (p<0.05) among the bacteria for Dry Matter (DM) lost and acetic acid production from rice straw and Acinetobacter strain Raminalimon showed the highest activity. The facultative bacteria C. kwangyangense strain Cb (cfu mL(-1) 231 x 10(-6), OD: 0.5), E. cloacae (cfu mL(-1) 68 x 10(-7), OD: 0.5) and E. aerogenes (cfu mL(-1) 33 x 10(-7), OD: 0.5) were used for digestion study with the rumen fluid microflora. The in vitro gas production technique was applied for the comparative study and the parameters measured were pH, gas (volume), dry matter lost, acetic acid, propionic acid and butyric acid concentrations. pH was not significantly (p<0.05) different among the five treatments. The bacterium C. kwangyangense strain Cb showed the highest activity (p<0.05) for DM lost, acetic acid, propionic acid and butyric acid production from rice straw when compared to the other bacterial activities. There was no significance (p<0.05) difference between the three bacteria for the dry matter lost of oil palm fronds but the production of Volatile Fatty Acids (VFA) was significantly (p<0.05) high in the treatment which was inoculated with C. kwangyangense strain Cb. The Gen Bank NCBI/EMBL accession numbers for the bacterial strains are EU332791, EU305608, EU305609, EU294508 and EU169201

Influence of modified air on combustion characteristics in meso-scale vortex combustor

The need to supply power for miniaturized mechanical devices opens exciting new opportunities for combustion, especially in the field of micro-power generation. Because of the need for power supply devices with high-specific energy (small-size, low weight, long duration) and power. Meso/micro scale combustion has been considered as a potential solution for many small-volumes and energy demanding systems, such as power supplies for portable device. In this study the structure of turbulent diffusion flames in a meso scale combustor with different oxygen concentration has been investigated using a new design of vortex combustor. Methane gas was used as a fuel. Numerical investigations have been performed on the temperature distribution, swirl number, heat loss, and emitter efficiency in vortex combustion. The results have been obtained for various O2 concentrations in the air as oxidizer. The results shows that thermal flame behaves depend strongly on the oxygen content in the oxidizer. When the oxygen concentration increases from 15% to 30%, the flame temperature of the meso-combustion rises in all cases. Emitter efficiency is very high in the meso-combustor with high O2 concentration in oxidizer