Diesel engines is an internal combustion engine with high thermal efficiency,which also uses biodiesel fuel,an environmentally friendly,non-toxic,and low sulfur content.Biodiesel has been around for a long time due to...Diesel engines is an internal combustion engine with high thermal efficiency,which also uses biodiesel fuel,an environmentally friendly,non-toxic,and low sulfur content.Biodiesel has been around for a long time due to its similar characteristics to diesel fuels which has limited availability.However,several disadvantages are associated with biodiesel,such as poor volatility and high viscosity,which reduces engine performance.Therefore,this study was carried out to improve the diesel engine performance by mixing biodiesel with ecodiesel(ED),an additive produced from natural ingredients that is dissolvable in biodiesel.The biodiesel fuel properties used are density 860 kg/m3,dynamic viscosity 4.50E-06 m2/s,cetane number 45,and flashpoint 52°C.The results showed that biodiesel-ED mixture could improve engine performance and the optimum performance was at a speed of 3000 rpm on 43.30(kW),124.93(N.m)of the engine torque,and 2.45E–5(kg/kW.s)of the specific fuel consumption.According to paired sample t-test,the difference in the engine performance is only experienced in the torque,which has a significant increase in the composition of the biodiesel+ED by 0.07 gr mixture.展开更多
AIM: To assess the frequency of visualization, position and diameter of normal appendix on 128-slice multidetector computed tomography(MDCT) in adult population.METHODS: Retrospective cross sectional study conducted a...AIM: To assess the frequency of visualization, position and diameter of normal appendix on 128-slice multidetector computed tomography(MDCT) in adult population.METHODS: Retrospective cross sectional study conducted at Radiology Department, Dallah Hospital, Riyadh, Saudi Arabia from March 2013 to October 2013. Non-enhanced computed tomography scans of abdomen and pelvis of 98 patients presenting with hematuria(not associated with abdominal pain, fever or colonic disease) were reviewed by two radiologists, blinded to patient history. The study group included 55 females and 43 males with overall mean age of 54.7 years(range 21 to 94 years). The coronal reformatted images were reviewed in addition to the axial images. The frequency of visualization of appendix was recorded with assessment of position, diameter and luminal contents.RESULTS: The appendix was recorded as definitely visualized in 99% of patients and mean outer-to-outer diameter of the appendix was 5.6 ± 1.3 mm(range 3.0-11.0 mm).CONCLUSION: MDCT with its multiplanar reformation display is extremely useful for visualization of normal appendix. The normal appendix is very variable in its position and diameter. In the absence of other signs, the diagnosis of acute appendix should not be made solely on outer-to-outer appendiceal diameter.展开更多
In the previous experimental work, a new technology system for wood pyrolysis was developed to aim at mitigating climate change, global warming, and energy crisis as well as enhancing low electrification in rural area...In the previous experimental work, a new technology system for wood pyrolysis was developed to aim at mitigating climate change, global warming, and energy crisis as well as enhancing low electrification in rural areas in developing countries. The new technology system equipped with a pre-vacuum chamber requires low cost and less maintenance. However, large wood pyrolysis in the pre-vacuum chamber is rather complicated. To obtain a good understanding of the previous experimental results, a numerical analysis taking account of heat-mass transfer and chemical reaction is carried out. Two-step general reaction model is proposed for the numerical analysis. The first stage is volatile and char formation from the wood pieces and the second state is decomposition of the volatile to five species including vapor of tar. In this analysis, chemical formulae of the volatile and the tar are successfully identified hypothetically. The results obtained by this numerical analysis can explain the experimental results reasonably and provide useful information about time evolution of volatile formation, temperature change in pre-vacuum chamber with time, and species mole concentration decomposed from the volatile.展开更多
Climate change, global warming, and energy crisis are critical issues to be solved urgently in a global framework. Alternative energy and renewable energy technologies must be quickly developed to be substituted for f...Climate change, global warming, and energy crisis are critical issues to be solved urgently in a global framework. Alternative energy and renewable energy technologies must be quickly developed to be substituted for fossil fuels like oil, gases, and coal. USA, UE, and Japan invested huge budgets to develop biomass renewable energy technology. Their target is to develop a commercial base large-scaled plant. On the other hand, in developing countries, especially in rural areas, people who can access electricity is still less than 70%, To decelerate or prevent global warming and improve electrification in rural areas, a new technology for wood pyrolysis, which requires low manufacturing cost and less maintenance, and of which gases are directly applicable to the gas engine generator, is developed in a laboratory scale. This paper reports the performance of this new plant and effects of several parameters on the performance. It is concluded that the new technology is quite feasible in rural areas, and upgrading of the plant is easily possible.展开更多
文摘Diesel engines is an internal combustion engine with high thermal efficiency,which also uses biodiesel fuel,an environmentally friendly,non-toxic,and low sulfur content.Biodiesel has been around for a long time due to its similar characteristics to diesel fuels which has limited availability.However,several disadvantages are associated with biodiesel,such as poor volatility and high viscosity,which reduces engine performance.Therefore,this study was carried out to improve the diesel engine performance by mixing biodiesel with ecodiesel(ED),an additive produced from natural ingredients that is dissolvable in biodiesel.The biodiesel fuel properties used are density 860 kg/m3,dynamic viscosity 4.50E-06 m2/s,cetane number 45,and flashpoint 52°C.The results showed that biodiesel-ED mixture could improve engine performance and the optimum performance was at a speed of 3000 rpm on 43.30(kW),124.93(N.m)of the engine torque,and 2.45E–5(kg/kW.s)of the specific fuel consumption.According to paired sample t-test,the difference in the engine performance is only experienced in the torque,which has a significant increase in the composition of the biodiesel+ED by 0.07 gr mixture.
文摘AIM: To assess the frequency of visualization, position and diameter of normal appendix on 128-slice multidetector computed tomography(MDCT) in adult population.METHODS: Retrospective cross sectional study conducted at Radiology Department, Dallah Hospital, Riyadh, Saudi Arabia from March 2013 to October 2013. Non-enhanced computed tomography scans of abdomen and pelvis of 98 patients presenting with hematuria(not associated with abdominal pain, fever or colonic disease) were reviewed by two radiologists, blinded to patient history. The study group included 55 females and 43 males with overall mean age of 54.7 years(range 21 to 94 years). The coronal reformatted images were reviewed in addition to the axial images. The frequency of visualization of appendix was recorded with assessment of position, diameter and luminal contents.RESULTS: The appendix was recorded as definitely visualized in 99% of patients and mean outer-to-outer diameter of the appendix was 5.6 ± 1.3 mm(range 3.0-11.0 mm).CONCLUSION: MDCT with its multiplanar reformation display is extremely useful for visualization of normal appendix. The normal appendix is very variable in its position and diameter. In the absence of other signs, the diagnosis of acute appendix should not be made solely on outer-to-outer appendiceal diameter.
文摘In the previous experimental work, a new technology system for wood pyrolysis was developed to aim at mitigating climate change, global warming, and energy crisis as well as enhancing low electrification in rural areas in developing countries. The new technology system equipped with a pre-vacuum chamber requires low cost and less maintenance. However, large wood pyrolysis in the pre-vacuum chamber is rather complicated. To obtain a good understanding of the previous experimental results, a numerical analysis taking account of heat-mass transfer and chemical reaction is carried out. Two-step general reaction model is proposed for the numerical analysis. The first stage is volatile and char formation from the wood pieces and the second state is decomposition of the volatile to five species including vapor of tar. In this analysis, chemical formulae of the volatile and the tar are successfully identified hypothetically. The results obtained by this numerical analysis can explain the experimental results reasonably and provide useful information about time evolution of volatile formation, temperature change in pre-vacuum chamber with time, and species mole concentration decomposed from the volatile.
文摘Climate change, global warming, and energy crisis are critical issues to be solved urgently in a global framework. Alternative energy and renewable energy technologies must be quickly developed to be substituted for fossil fuels like oil, gases, and coal. USA, UE, and Japan invested huge budgets to develop biomass renewable energy technology. Their target is to develop a commercial base large-scaled plant. On the other hand, in developing countries, especially in rural areas, people who can access electricity is still less than 70%, To decelerate or prevent global warming and improve electrification in rural areas, a new technology for wood pyrolysis, which requires low manufacturing cost and less maintenance, and of which gases are directly applicable to the gas engine generator, is developed in a laboratory scale. This paper reports the performance of this new plant and effects of several parameters on the performance. It is concluded that the new technology is quite feasible in rural areas, and upgrading of the plant is easily possible.