Oil and gas exploration in the Niger Delta region of Nigeria began some fifty four （54） years ago. Since the early sixties till now, oil from this region of the Nigeria has been the major foreign exchange earner for...Oil and gas exploration in the Niger Delta region of Nigeria began some fifty four （54） years ago. Since the early sixties till now, oil from this region of the Nigeria has been the major foreign exchange earner for the sustenance of the economy. Unfortunate to note is the fact that since oil exploration and exploitation began in the country in the Niger Delta, the region had not been at peace. The region had suffered all forms of environmental degradation resulting from crude oil spillage and gas flares. The peoples＇ source of livelihood has been destabilized thereby leading to high rate of poverty, social crises/conflict and involuntary migration of people for both security and succour. The people of the region are thus in severe pains and risk of extermination should the present trend of environmental degradation and negligence persist. Thus, this paper addresses the plight of the Niger Delta as a case study of the effect of environmental degradation on human vulnerability. It is believed that continuous existence of the Niger Delta people as a social sect is dependent on how prompt efforts are made to combat the environment nuisance in the region.展开更多
It is one of the most efficient ways to greatly improve aero-engines' performance by utilizing vaneless counterrotating turbine(VCRT) technology.To supply sufficient power,VCRT turns to be high Mach number,large f...It is one of the most efficient ways to greatly improve aero-engines' performance by utilizing vaneless counterrotating turbine(VCRT) technology.To supply sufficient power,VCRT turns to be high Mach number,large flow angle at high-pressure turbine(HPT) rotor exit,and low blade camber angle,which increase difficulties to turbine design.As the axial velocity ratio of HPT rotor is much larger than the conventional ones,the optimal selection of VCRT velocity triangles based on theoretical analysis is developed,and how the efficiency varied by HPT stator/rotor exit flow angle is also figured out.The key points to design a high efficient practicable VCRT are to select velocity triangles that are characterized by low flow coefficient,high outlet flow angle and large axial velocity ratio of HPT rotor.Meanwhile,performance comparison between convergent blade and convergent-divergent blade shows the latter is more appropriate for VCRT.展开更多
文摘Oil and gas exploration in the Niger Delta region of Nigeria began some fifty four （54） years ago. Since the early sixties till now, oil from this region of the Nigeria has been the major foreign exchange earner for the sustenance of the economy. Unfortunate to note is the fact that since oil exploration and exploitation began in the country in the Niger Delta, the region had not been at peace. The region had suffered all forms of environmental degradation resulting from crude oil spillage and gas flares. The peoples＇ source of livelihood has been destabilized thereby leading to high rate of poverty, social crises/conflict and involuntary migration of people for both security and succour. The people of the region are thus in severe pains and risk of extermination should the present trend of environmental degradation and negligence persist. Thus, this paper addresses the plight of the Niger Delta as a case study of the effect of environmental degradation on human vulnerability. It is believed that continuous existence of the Niger Delta people as a social sect is dependent on how prompt efforts are made to combat the environment nuisance in the region.
基金carried out under contract for the National Natural Science Foundation of China as part of the Free Application Project (No. 50776003)
文摘It is one of the most efficient ways to greatly improve aero-engines' performance by utilizing vaneless counterrotating turbine(VCRT) technology.To supply sufficient power,VCRT turns to be high Mach number,large flow angle at high-pressure turbine(HPT) rotor exit,and low blade camber angle,which increase difficulties to turbine design.As the axial velocity ratio of HPT rotor is much larger than the conventional ones,the optimal selection of VCRT velocity triangles based on theoretical analysis is developed,and how the efficiency varied by HPT stator/rotor exit flow angle is also figured out.The key points to design a high efficient practicable VCRT are to select velocity triangles that are characterized by low flow coefficient,high outlet flow angle and large axial velocity ratio of HPT rotor.Meanwhile,performance comparison between convergent blade and convergent-divergent blade shows the latter is more appropriate for VCRT.
