Direct Measurement of Circulation Using Ultrasound

Ultrasound time-of-flight methods employing counter-propagating ultrasonic pulses are utilized for the direct measurement of circulation in vortical flows. Two schemes are described here which involve either a single straight path or a closed path. Both techniques are shown to result in time differences, between the counter-propagating pulses around the path, linearly proportional to the circulation enclosed by the ultrasound path. The ultrasound methods of circulation measurement do not require calibration constants and can be non-invasive. The reliability of the closed path ultrasound method was assessed by comparing the measured circulation values with those calculated from the lift measurements of a NACA 0012 airfoil. Two examples are also presented where the closed path ultrasound method has been applied to the flow over a delta wing and a free-surface vortex in a cylindrical tank

Ultrasonic Beam Propagation in Turbulent Flow

A study was conducted to examine how a coherent sound burst, such as those used in an ultrasonic flowmeter, crosses a turbulent flow field. Many ultrasonic flowmeters use a time of flight method to determine the mean flow. This measurement method sends sound waves at some angle across a velocity field between two transducers, and the time required for the sound burst to cross this distance is measured on the order of nanoseconds. The system then reverses so that the sound wave burst is sent in the opposite direction. Knowing the distance traveled, the local average sound speed, and the back and forth travel times, the integrated velocity along the sound path can be computed. By using average values for distance and time, an average flowrate may be determined. To perform this analysis, data from several velocity fields were used to determine how a coherent sound burst would travel across the field. Comparisons of the infinitely thin case and the finite thickness case are performed. The study focused on using a modified ray trace method on a velocity field data set obtained using PIV

Circular polarization folded reflectarray antenna for 5G applications

Fifth-generation (5G) is a wireless connection built specifically to keep up with the rapid increase of devices that need a mobile internet connection. A system working on 5G band can provide higher bandwidth and faster data rate as compared to fourth-generation (4G) band. Thus, an antenna with higher gain and lower profile is required to support this system. On the other hand, the performance of circular polarization antenna is better than linear polarization antenna due to its ability to accept wave from different direction. In this project, a low profile circular polarization folded reflectarray antenna with operating frequency of 28 GHz is presented. This project is divided into two parts. In the first part, a linear polarization folded reflectarray antenna is designed. In this second part, a meander lines polarizer is used to convert the linear polarization antenna to circular polarization antenna. The antenna is fed by a linear polarized waveguide. Each radiating element of the antenna is in rectangular shape. The size of the radiating elements are selected according to obtain required phase delay to form a planar phase front in the far-field distance. Both of the antennas are simulated by using Computer Simulation Technology (CST) software. Finally, the results shows excellent performances with 16.81dB directivity and 1.49dB axial ratio at 28GHz. Thus, the antenna is very suitable for 5G applications

A kinetic study of enzymatic hydrolysis of oil palm biomass for fermentable sugar using polyethylene glycol (PEG) immobilized cellulase

In this work, enzymatic hydrolysis by cellulase in a soluble and an immobilized form was studied to convert lignocellulosic oil palm empty fruit bunch (EFB) biomass into fermentable sugars as a feedstock for bioethanol production. The cellulase was covalently immobilized with activated and functionalized polyethylene glycol (PEG) via glutaraldehyde coupling method. As a whole, the immobilized cellulase displayed 50 higher efficiency over free cellulase, in reducing sugar recovery during hydrolysis reactions at pH of 4.8 and temperature of 50°C. From the kinetic study, it showed that Michaelis constant (Km) and limiting velocity (Vmax) of immobilized cellulase were 179.2 mg/ml and 33.5 mg/ml.min respectively, comparable with the value for free cellulose, 171.8 mg/ml and 34.5 mg/ml.min respectively. This result could be attributed to the effect of PEG on the binding cellulase to substrate desorb substrates, and enables free interaction of cellulase to hydrolyse cellulose maximally

Isolation and characterization of an acrylamide-degrading Bacillus cereus

Several local acrylamide-degrading bacteria have been isolated. One of the isolate that exhibited the highest growth on acrylamide as a nitrogen source was then further characterized. The isolate was tentatively identified as Bacillus cereus strain DRY135 based on carbon utilization profiles using Biolog GP plates and partial 16S rDNA molecular phylogeny. The isolate grew optimally in between the temperatures of 25 and 30°C and within the pH range of 6.8 to 7.0. Glucose, fructose, lactose, maltose, mannitol, citric acid and sucrose supported growth with glucose being the best carbon source. Different concentrations of acrylamide ranging from 100 to 4000 mg l-1 incorporated into the growth media shows that the highest growth was obtained at acrylamide concentrations of between 500 to 1500 mg l-1. At 1000 mg l-1 of acrylamide, degradation was 90% completed after ten days of incubation with concomitant cell growth. The metabolite acrylic acid was detected in the media during degradation. Other amides such as methacrylamide, nicotinamide, acetamide,propionamide and urea supported growth with the highest growth supported by acetamide, propionamide and urea. Strain DRY135,however, was not able to assimilate 2-chloroacetamide. The characteristics of this isolate suggest that it would be useful in the bioremediation of acrylamide

Visual performance and motorcycle safety-related impacts of various high beam headlight intensities

In Malaysia, the three main types of motorcycle accidents include collision with passenger cars, collision with other motorcycles and single-motorcycle accidents. An accident may occur due to the lack of road design consistency and visibility where most drivers make more errors in the absence of geometric features. One of the most important barriers to the more frequent use of high beam headlight is the length of visibility of the headlight beam in relation to the stopping distance of a vehicle. Furthermore, it is crucial to evaluate the current limits on the luminous intensity of high beam headlights that is considered visible for a driver to come to a stop. Therefore, this first stage study summarizes and investigates the stopping sight distances, braking distances that allow for the evaluation of the vehicle's performance to increase the capability of both the driver and vehicle with regard to safety. A total of ten experiments were carried out with a passenger car, the Perodua Myvi, on a road within a local university. The results found that Stopping Sight Distance (SSD) could be used to determine the SSD graph by considering the velocity (v0), driver’s perception reaction time (tR), coefficient of breaking friction (fT), gravitational constant (g), deceleration rate (a) and roadway grade (G). The study also concludes that SSD could be used to determine the SSD graph by considering the velocity (v0), driver’s perception reaction time (tR), coefficient of breaking friction (fT), gravitational constant (g), deceleration rate (a) and roadway grade (G). Ultimately, the study also indicates that the time to switch to hi-beam (Automatic High Beam – AHB) is at SSD distance (meter or second)

Wideband Frequency Selective Surface Based Transmitarray Antenna at X-Band

In this paper, a wideband multilayer transmitarray antenna is designed for Ku frequency band. The unit cell is designed at 12GHz using frequency selective surface structure. Double square ring with center patch based multilayer unit cell is simulated. The effect of substrate thickness variation on transmission coefficient magnitude and phase range is discussed. The horn antenna designed at X-band will be used as feed source for transmitarray antenna. Transmitarray simulation results show wide impedance bandwidth from 10 to 13GHz. Wide gain bandwidth of 1.975GHz with peak gain of 18.96dB is achieved. The proposed transmitarray design will find applications in high gain, directional, low profile antennas for X-band communication systems

Face and content validity for the special education leadership (Integration) questionnaire In Malaysia

The validity of the face and content of a constructed set of questionnaires is very important in determining its validity and applicability. Each questionnaire that is constructed needs to go through this validity process to strengthen the strength of the questionnaire. The need in carrying out this validity is to meet the requirements ofthe objectives of the study as well as the integrity of an item constructed. This situation is very important in constructing a set of questionnaires related to special education leadership in scope in Malaysia. Therefore, this study was conducted to detail the face and content validity requirements conducted on the questionnaire related to special education leadership in Malaysia. The findings of this study can help subsequent researchers in determining the correct process in doing face and content validity

The effects of conventional and microwave heating techniques on extraction yield of orthosiphon stamineus leaves

The heating technique in a solid-liquid extraction system plays a significant role in the design and economic potential for the extraction of active components from herbs. This paper focused on the effects of extraction parameters such as ratio of sample to solvent, temperature and time of processing on the extraction yield of Orthosiphon stamineus leaves in conventional and microwave heating extraction techniques. The extracts were concentrated and dried using a rotary evaporator and freeze dryer in order to relate the yield to the processing parameters quantitatively in both heating techniques. The analysis results revealed that the processing parameters; ratio of sample to solvent, temperature and time of extraction had essential effects on the extraction yield of Orthosiphon stamineus leaves. Microwave heating extraction produced a comparable yield to conventional heating extraction with a relatively small deviation of approximately 2.8 % in average. Furthermore, microwave heating extraction reduced processing time, where this technique required about 25 % of the conventional heating time in heating up the extraction mixture to set-point temperature (60 ºC). This study concludes that microwave heating extraction, which is a green technology, has great potential in reducing the carbon foot print due to a shorter processing time and reduced energy consumption (~77 % less) compared to conventional heating extraction

Predictor of academic performance: personality traits and catechol-O-methyltransferase polymorphisms

Personality traits and genetics are important factors in determining academic performance. Although there have been studies on the association between genetics and academic performance, there is limited data on the effect of personality traits and the catechol-O-methyltransferase (COMT) rs4680 polymorphism on academic performance, particularly among university students in Malaysia. The objective of this study was to correlate the relationship between personality traits, COMT rs4680 polymorphism, and academic performance among health sciences undergraduate students at a Malaysian university. The research design was a correlational study where 221 students were recruited based on the convenient sampling approach. The demographic and international personality item pool (IPIP) questionnaires were administered online, whereas the COMT rs4680 single nucleotide polymorphism (SNP) was determined using a tetra-primer allele-specific polymerase chain reaction (PCR). From the IPIP results, the conscientiousness trait was positively and significantly correlated with academic performance (r=0.141, p=0.036). Participants with homozygous Met/Met allele of the COMT rs4680 polymorphism tended to perform better in academics (p=0.009) as compared to participants with homozygous Val/Val and heterozygous Val/Met alleles. As a conclusion, students with a higher conscientiousness score and carriers of the homozygous Met/Met allele of COMT rs4680 showed better academic performance