A two-component CFD studies of the effects of H2, CNG, and diesel blend on combustion characteristics and emissions of a diesel engine

Numerical simulations were conducted on a Ricardo Hydra diesel engine which is single cylinder engine and uses direct injection method. This study was performed by using a two-dimensional CFD code to examine the combustion characteristics and emissions of a diesel engine in diesel-CNG and diesel-H2 dual-fuel operations, as well as in the diesel-CNG-H2 tri-fuel operation at various air-fuel ratios. The results indicate that the peak in-cylinder pressure and peak temperature were increased with the addition of gaseous fuels at low and medium values of exceeds air. Compared with Diesel-H70-N30 for tri-mode and Diesel-H2 for dual mode, it is observed that there were no effects on the peak temperature at high exceed air. At 2.4 exceed air, the peak pressure increases by means of adding the limit value of hydrogen, such as H30-N70 and H50-N50, to CNG and it begins to decrease with H70-N30 and H2-Diesel operations. Diesel-H2-CNG operations decrease CO/CO2 emissions compared with Diesel-CNG operation and decrease NO emission compared with Diesel-H2 operation at every exceed air. The reduction in CO/CO2 emissions was suggested at high hydrogen fraction in CNG (H70-N30) with all exceeds air whereas low hydrogen fraction in CNG (H30-N70) can repress uncontrolled hydrogen combustion and further limit the increment of NO emission

Aqueous foams stabilized with silica nanoparticle and alpha olefin sulfonates surfactant

Carbon dioxide (CO2) foams have been introduced to improve mobility of CO2 in CO2 flooding. However, using surfactant alone to stabilize CO2 foam has potential weaknesses such as high surfactant retention in porous media and the foam is thermodynamically unstable for a long-term. Nanoparticle has been an alternative in stabilizing CO2 foam longer. This study aims to analyze CO2 foam stability at varying concentrations of surfactant, silica nanoparticle (SNP) and brine. The additions of SNP in anionic surfactant of alpha olefin sulfonates (AOS)-water and in AOS-brine towards foam stability were demonstrated in this study. CO2 foam stability was measured through the foam height observation and bubble size analysis. The performance of SNP and AOS suspensions in stabilizing foam were observed at different concentrations of AOS (0.1, 0.3 and 0.5 wt%), SNP (0.1, 0.3 and 0.5 wt%) and brine (0.1, 1 and 5 wt%). The results revealed that the CO2 foams were most stable at 0.3 wt% SNP suspension in 0.5 wt% AOS-water. It was found that the most stable foams formed at concentration of 1 wt% of brine. Smaller and uniform bubble size has been produced at 0.3 wt% SNP in 0.5 wt% AOS solution. Thus, concentrations of surfactant, SNP and brine have significant effects on CO2 foam stability

High velocity impact response of Kevlar-29/epoxy and 6061-T6 aluminum laminated panels

The high velocity impact response of composite laminated plates has been experimentally investigated using a nitrogen gas gun. Tests were undertaken on sandwich structures based on Kevlar-29 fiber/epoxy resin with different stacking sequence of 6061-T6 Al plates. Impact testing was conducted using cylindrical shape of 7.62 mm diameter steel projectile at a range of velocities (180–400 m/s) were investigated to achieve complete perforation of the target. The numerical parametric study of ballistic impact caused by same conditions in experimental work is undertaken to predict the ballistic limit velocity, energy absorbed by the target and comparison between simulation by using ANSYS Autodyn 3D v.12 software and experimental work and study the effects of shape of the projectile with different (4, 8 and 12 mm) thicknesses on ballistic limit velocity. The sequence of Al plate position (front, middle and back) inside laminate plates of composite specimen was also studied. The Al back stacking sequence plate for overall results obtained was the optimum structure to resist the impact loading. The results obtained hereby are in good agreement with the experimental (maximum error of 3.64%) data where it has been shown that these novel sandwich structures exhibit excellent energy absorbing characteristics under high velocity impact loading conditions. Hence it is considered suitable for applications of armor system

Temperature and heat flux measurement techniques for aeroengine fire test: a review

This review is made of studies whereby some types of fire test measuring instrument were compared based on their mode of operation, sensing ability, temperature resistance and their calibration mode used for aero-engine applications. The study discusses issues affecting temperature and heat flux measurement, methods of measurement, calibration and uncertainties that occur in the fire test. It is found that the temperature and heat flux measurements of the flame from the standard burner need to be corrected and taken into account for radiation heat loss. Methods for temperature and heat flux measurements, as well as uncertainties analysis, were also discussed

Developmental research of sustainable technologies to minimise problematic road embankment settlements

Challenging, problematic and non-uniform ground conditions are a night mare to geotechnical engineers tasked with the design and construction of buildings and transport infrastructure. These often suffer undesirable structural settlements. Designing within the current understanding of geotechnics; settlement in peat and organic soils need to be recognised to include the known “primary and secondary consolidation characteristics” and the lesser known “tertiary consolidation phase”. These eventually contribute cumulatively to the consequential uneven and hazardous “bumpy road” surfaces. Undulating flexible road pavements result primarily from the transference of the heavy self-weight of the embankment fill to yielding and non-uniform subgrade. The adoption of conventional design/repair methods such as pile, vertical drain, soil replacement and soil stabilisation are expensive and inappropriate in very soft ground conditions. These then lead to unjustifiably high and repetitive maintenance costs. There being no one quick fix solution for all; pragmatic research must necessarily identify the best/progressively improved practical and sustainable solution. A viable solution is to develop criteria and explore the concept of a “masonry arch bridge structure/lintel-column structure” and adopting sustainable materials through pragmatic searching for appropriate recyclable waste materials. This will lead to the basis for a sustainable, innovative, strong, stiff, permeable composite mat structure that can be used on soft and/or yielding ground conditions. Conceptual lightweight fill technology including the popularly used expanded polystyrene (EPS) and the innovative composite mats recently being developed by the research team are outlined

Study of the antitumor activity of the combination baicalin and epigallocatechin gallate in a murine model of vincristine-resistant breast cancer

Background: Breast cancer is one of the primary causes of death in women worldwide. Yearly, a quarter of cancer cases in women are breast cancer. The problem is aggravated by the emergence of chemotherapeutic resistance. One of the practices to overcome this problem is using natural products along with chemotherapy. Epigallocatechin Gallate (EGCG) is the main efficient catechin in green tea. Baicalin is the main active chemical constituent of Scutellaria baicalensis. Both natural products have anti-cancer and improving resistance activities. Therefore, a combination of EGCG and baicalin may afford a possible way out to overcome chemotherapeutic resistance. Methods: EGCG and baicalin were tested on Vincristine-sensitive (EMT-6/P) and Vincristine-resistant (EMT-6/V) mouse mammary cell lines. Antiproliferative and apoptotic effects were assessed for EGCG, baicalin, their combination, and Vincristine in vitro using MTT and caspase-3 assays. An in vivo study was conducted to assess the effect of EGCG, baicalin, their combination, vincristine, vincristine along with the combination in both EMT-6/P and EMT-6/V mouse mammary cell lines. The safety profile was also considered using liver enzymes and creatinine assays. Results: in vitro, EGCG and baicalin had synergistic effects in both cell lines. The combination of baicalin and EGCG as 140 and 100 µM respectively, caused an apoptotic effect higher than the single treatment of baicalin 175 µM or EGCG 125 µM, in vincristine-resistant cell lines. In vivo, the combination along with vincristine significantly enhanced the reduction of tumour size in mice implanted with EMT-6/P and EMT-6/V cell lines. According to the safety profile, the combinations of EGCG and baicalin are safe. Conclusion: The combination of baicalin and EGCG can be optimistic in improving vincristine-resistant cells to treatments

Lecture-Centred or Student-Centered: A Case Study in a Public University

This study is aimed to investigate the current practice of teaching methods among lecturers in Universiti Teknologi Malaysia. A total of 357 lecturers participated in this study. The result showed that the general practice was influenced by lecturer’s field and years of teaching experience, not gender, qualification and designation. Comparing the specific teaching methods applied in three fields, it found that lecturers in science and technology used lecture and discussion much more frequently than those from engineering and social science. Among the six specific teaching methods, discussion and lecture were the most frequently used teaching method, which is scored significantly higher than the other four teaching methods. However, an interesting finding was reported  when  lecturers were asked to rate their preference in the six specific teaching methods.  Lecture was rated at the lowest level of preference but it was reported as one of the most frequently used teaching method. It may imply the changes on lecturers’ perspectives. Discussion method obtained the highest preference score, which is also applied frequently in current teaching practice. Keywords: general teaching practice, teaching method, lecture

Dam Break Analysis of Batu Dam using Hec-Ras

Dam is commonly built in Malaysia as it provides benefits to the local population, mainly agricultural activity and flood control measures. However, its massive potential energy reservoir would impose risk of sudden containment breach leading to loss of life and property at inhabited downstream area. Simulations of dam break events are crucial to characterizing and reducing threats due to potential dam failures. In all post-event natural disasters, where most structural countermeasures have been lost, the preparation of a smoother evacuation mechanism remains the most critical prevention tool for successful evacuation planning. The urgency of designing an appropriate emergency planning is important in response to the disaster. To perform a dam break analysis, hydraulic modeling is required, which involves routing the inflow flood through a reservoir, estimating dam breach characteristics, and downstream routing/modeling issues. The HEC-RAS (River Analysis System) software is commonly used for dam break studies. The software provides information on how to perform a dam break analysis, including the unique hydraulic modeling aspects that are required. Batu dam has the highest percentage of the population at risk (PAR) and most likely exposed to the flood disaster due to dam break. From flood boundary maps, it was estimated that 78% of residential areas would be affected if a dam break disaster occurs. From the simulation, the maximum depth can reach up to 18m with an estimated flow speed between 0.2 – 3m/s. At these depth and flow speed, people may lose strength and unable to control themselves in flood and would cause death and injury. Flood arrival time took 15 to 22 hours for flooding to arrive downstream with a maximum flood depth of 5.07m at Persiaran Jasa Utama and the highest depth of 12.62m at Kampung Baru Batu Caves with flood velocity between 1.60m/s to 1.46m/s. Analysis and simulation of embankment dam breach events and the resulting floods are crucial for distinguishing and mitigating dangers from potential dam failures. Accurate forecast of inundation levels and the time of flood wave arrival at downstream key places is required for the development of effective emergency response plans

Three dimensional numerical investigations on the heat transfer enhancement in a triangular facing step channels using nanofluid

In this paper, laminar flow for the distilled and SiO2-water nanofluid flow and heat transfer were numerically investigated in three-dimensional triangular facing-step channel. The nanoparticle volume fraction and Reynolds number considered are in the range of 0-1% and 100-1500, respectively. Numerical solutions are obtained by using finite difference method to solve the governing equations. The effects of the volume fraction of nanoparticle, triangular facing-step channel amplitude height, wavelength and Reynolds number on local skin-friction coefficient, average Nusselt number and enhancement of heat transfer are presented and discussed. The results show that the Nusselt number and friction coefficient increases as the amplitude height of triangle channel increases. As the nanoparticle volume fraction increases, the Nusselt number is also found to be significantly increased, accompanied by only a slight increase in the friction coefficient. In addition, it is found that the heat transfer enhancement mainly depends on the amplitude height of the triangle wall, nanoparticle volume fraction and Reynolds number rather than the wavelength

Influence of cut-out hole on multi-layer Kevlar-29/epoxy composite laminated plates

This paper presented the effect of cutout hole on multi layer of Kevlar-29/epoxy composite laminated plates this effect occurred and fiber orientation angle. An experimental procedure was developed to study the performance of these effects under quasi-static compressive and tensile load using a servo-hydraulic testing machine. The work involved investigation on the variety of orientation angles of Kevlar-29 fiber. The ultimate load of failure for each Kevlar-29/epoxy laminated plates had been determined and specified the optimum angle orientation and the load reduction due to the effect of fiber orientation angle (+45°/−45°) was low in the case for compared (0°/90°) orientation angle of fiber. To simulate this problem the researcher used Explicit Mesh for AUTODYN under ANSYS-12.1 software, where the researcher found that the results obtained via this simulation agreed reasonably well with the experimental results and the maximum difference between the experimental conditions and the simulation was 5.8%