Research on dual-fuel(DF)engines has become increasingly important as engine manufacturers seek to reduce carbon dioxide emissions.There are significant advantages of using diesel pilot-ignited natural gas engines as ...Research on dual-fuel(DF)engines has become increasingly important as engine manufacturers seek to reduce carbon dioxide emissions.There are significant advantages of using diesel pilot-ignited natural gas engines as DF engines.However,different combustion modes exist due to variations in the formation of the mixture.This research used a simulation model and numerical simulations to explore the combustion characteristics of high-pressure direct injection(HPDI),partially premixed compression ignition(PPCI),and double pilot injection premixed compression ignition(DPPCI)combustion modes under a low-medium load.The results revealed that the DPPCI combustion mode provides higher gross indicated thermal efficiency and more acceptable total hydrocarbon(THC)emission levels than the other modes.Due to its relatively good performance,an experimental study was conducted on the DPPCI mode engine to evaluate the impact of the diesel dual-injection strategy on the combustion process.In the DPPCI mode,a delay in the second pilot ignition injection time increased THC emissions(a maximum value of 4.27g/(kW·h)),decreased the emission of nitrogen oxides(a maximum value of 7.64 g/(kW·h)),increased and then subsequently decreased the gross indicated thermal efficiency values,which reached 50.4%under low-medium loads.展开更多
Objective： This study was done to compare between the effect of preoperative radiotherapy and postoperative radiotherapy in treatment of resectable rectal carcinoma. The primary endpoints are local recurrence rate, o...Objective： This study was done to compare between the effect of preoperative radiotherapy and postoperative radiotherapy in treatment of resectable rectal carcinoma. The primary endpoints are local recurrence rate, overall survival （OS） and disease free survival （DFS）. The secondary endpoints are to evaluate down-staging, treatment toxicity, and ability to do sphincter preservation, aiming at choosing the optimal treatment modality. Methods： This study included 100 patients with resectable rectal carcinoma who presented to Surgical Gastro Entrology Center and Clinical Oncology and Nuclear Medicine Department, Mansoura University during the period between January 2007 and September 2009. The included patients were randomized in two groups; group h 50 patients received preoperative radiotherapy and group Ih 50 patients received post- operative radiotherapy. Concurrent 5-fluorouracil-based chemotherapy was given to all patients. Two major types of surgery were done： abdomino-perineal resection with a permanent colostomy and low anterior resection with colorectal or coloanal anastomosis. Results： Preoperative radiotherapy resulted in pathologic complete response in 3 patients. T down-staging occurred in 18 out of 50 patients （36%） with statistically significant difference （P = 0.008）. N down-staging occurred in 10 out of 24 patients. Sphincter preservation was more in group I. Delayed wound healing was the most common postoperative complication in group I with no significant difference. After a median follow up of 18 months, local recurrence rate and distant metastasis were higher in group I1. The 2-year disease free survival was 72% and 60% in group I and II respectively with no statistically significant difference between both groups. Conclusion： This study concluded that preoperative radiotherapy is better than postoperative radiotherapy as regard local control, sphincter preservation with higher disease free survival and overall survival. No difference in treatment toxicity between both groups.展开更多
Due to high price of Straight Vegetable Oil （SVO） for bio-diesel production, the use of Waste Cooking Oil （WCO） will be cost effective. Furthermore, utilization of WCO will refrain waterways pollution and endanger...Due to high price of Straight Vegetable Oil （SVO） for bio-diesel production, the use of Waste Cooking Oil （WCO） will be cost effective. Furthermore, utilization of WCO will refrain waterways pollution and endanger ecosystem. In Malaysia, more than 50-tone of WCO from various sources was produced every day. This study evaluates combustion performance and exhaust emission characteristics of several WCOs with different sources. Modification on fuel properties has been done to improve the combustion and exhaust emission of using WCO as diesel fuel. Regular diesel fuel also has been used for comparison in the test. A 0.6 liter, single-cylinder, air-cooled direct injection diesel engine was used to perform this experiment. Experiment was done at variable engine loads at constant speed.展开更多
基金Project(2017YFE0102800)supported by the National Key R&D Program of ChinaProject(19JCYBJC21200)supported by the Tianjin Natural Science Foundation,China。
文摘Research on dual-fuel(DF)engines has become increasingly important as engine manufacturers seek to reduce carbon dioxide emissions.There are significant advantages of using diesel pilot-ignited natural gas engines as DF engines.However,different combustion modes exist due to variations in the formation of the mixture.This research used a simulation model and numerical simulations to explore the combustion characteristics of high-pressure direct injection(HPDI),partially premixed compression ignition(PPCI),and double pilot injection premixed compression ignition(DPPCI)combustion modes under a low-medium load.The results revealed that the DPPCI combustion mode provides higher gross indicated thermal efficiency and more acceptable total hydrocarbon(THC)emission levels than the other modes.Due to its relatively good performance,an experimental study was conducted on the DPPCI mode engine to evaluate the impact of the diesel dual-injection strategy on the combustion process.In the DPPCI mode,a delay in the second pilot ignition injection time increased THC emissions(a maximum value of 4.27g/(kW·h)),decreased the emission of nitrogen oxides(a maximum value of 7.64 g/(kW·h)),increased and then subsequently decreased the gross indicated thermal efficiency values,which reached 50.4%under low-medium loads.
文摘Objective： This study was done to compare between the effect of preoperative radiotherapy and postoperative radiotherapy in treatment of resectable rectal carcinoma. The primary endpoints are local recurrence rate, overall survival （OS） and disease free survival （DFS）. The secondary endpoints are to evaluate down-staging, treatment toxicity, and ability to do sphincter preservation, aiming at choosing the optimal treatment modality. Methods： This study included 100 patients with resectable rectal carcinoma who presented to Surgical Gastro Entrology Center and Clinical Oncology and Nuclear Medicine Department, Mansoura University during the period between January 2007 and September 2009. The included patients were randomized in two groups; group h 50 patients received preoperative radiotherapy and group Ih 50 patients received post- operative radiotherapy. Concurrent 5-fluorouracil-based chemotherapy was given to all patients. Two major types of surgery were done： abdomino-perineal resection with a permanent colostomy and low anterior resection with colorectal or coloanal anastomosis. Results： Preoperative radiotherapy resulted in pathologic complete response in 3 patients. T down-staging occurred in 18 out of 50 patients （36%） with statistically significant difference （P = 0.008）. N down-staging occurred in 10 out of 24 patients. Sphincter preservation was more in group I. Delayed wound healing was the most common postoperative complication in group I with no significant difference. After a median follow up of 18 months, local recurrence rate and distant metastasis were higher in group I1. The 2-year disease free survival was 72% and 60% in group I and II respectively with no statistically significant difference between both groups. Conclusion： This study concluded that preoperative radiotherapy is better than postoperative radiotherapy as regard local control, sphincter preservation with higher disease free survival and overall survival. No difference in treatment toxicity between both groups.
文摘Due to high price of Straight Vegetable Oil （SVO） for bio-diesel production, the use of Waste Cooking Oil （WCO） will be cost effective. Furthermore, utilization of WCO will refrain waterways pollution and endanger ecosystem. In Malaysia, more than 50-tone of WCO from various sources was produced every day. This study evaluates combustion performance and exhaust emission characteristics of several WCOs with different sources. Modification on fuel properties has been done to improve the combustion and exhaust emission of using WCO as diesel fuel. Regular diesel fuel also has been used for comparison in the test. A 0.6 liter, single-cylinder, air-cooled direct injection diesel engine was used to perform this experiment. Experiment was done at variable engine loads at constant speed.
