China’s electric power industry as a basic industry, plays an important role in the longterm, sustained and healthy development of the whole national economy. China’s electric power industry attained great achieveme...China’s electric power industry as a basic industry, plays an important role in the longterm, sustained and healthy development of the whole national economy. China’s electric power industry attained great achievement in technology and economical results during the past eight years from 1987-1995. The total national installed generating capacity increased from 102.897 GW in 1987 to more than 200 GW in March, 1995.展开更多
With respect to the crest spillway with large unit discharge and low Froude number, the hydraulics of the slit-type energy dissipater at the outlet should be noticed due to the complicated flow regimes. In the present...With respect to the crest spillway with large unit discharge and low Froude number, the hydraulics of the slit-type energy dissipater at the outlet should be noticed due to the complicated flow regimes. In the present paper, some issues about hydraulic characteristics were experimentally investigated by means of five slit-type outlets and four tetrahedrons, including the flow choking, impact to river banks and jet trajectory. The main findings are as follows. The critical Froude number for the flow choking decreases with increasing outlet width of the slit-type energy dissipater. If the flow Froude number is expressed by the parameters just before this energy dissipater, the tetrahedron placed inside the side wall of the outlet could efficiently avoid the flow impact to the river bank of same side, and compared with the jet trajectory of the slit-type energy dissipater, the outlet with tetrahedron has different trajectory trend, i.e., the distance of the jet trajectory decreases with the increase of the water head due to special form of the outlet tetrahedron.展开更多
Introduction to HEC Harbin Electric Machinery Company Limited (HEC) is a pivotal company that produces large electric machinery and accessorial control equipment in China. The hydro units made by HEC have
Sutong Bridge is a cable-stayed bridge with a steel box girder and a main span of 1 088 m.The steel box girder of main span includes five portions:back span large unit,large block of pylon,standard girder,back span cl...Sutong Bridge is a cable-stayed bridge with a steel box girder and a main span of 1 088 m.The steel box girder of main span includes five portions:back span large unit,large block of pylon,standard girder,back span closure girder and middle span closure girder.Each back span large unit is fabricated by welding several deck segments together in factory,and is erected by floating crane.As navigational clearance of the main bridge is high,the traditional truss lifting device can't satisfy the requirement of domestic lifting cranes for this kind of lifting height and weight.Hence,a kind of lighter lifting device for the erection of back span large units was accepted for this bridge.In this paper,the design and use of this lifting device is introduced.The upper structure used lifting gantry to install the standard girder segment by cantilever method.Because the bridge's navigation clearance is high,and the girder segment is wide and heavy,the meteorology and hydrology condition of the bridge district is abominable,and the requirements of long cable girder side pull-in,structure and performance propose high request to the lifting gantry.In this paper,the design and use key point of long cable pull-in angle adjustment device integrate into lifting gantry is introduced.展开更多
Pullets often raised in cage system from week 1 to week 13 in China,when transferred to aviary system after,there will be a problem with adapt.A large cage aviary unit(LCAU)system was developed,which allocated with fa...Pullets often raised in cage system from week 1 to week 13 in China,when transferred to aviary system after,there will be a problem with adapt.A large cage aviary unit(LCAU)system was developed,which allocated with facilities such as ramps to help cage reared hens to adapt to the multi-tier space.To investigate hens’adaptability to the new system,space use over time in the LCAU system during the first 10 days after hens transferred were recorded,instantaneous scan sampling and continuous focal sampling were used to assess the behavior difference of hens between the LCAU and conventional cage(CC)systems.On the first day of arrival,10.03% of hens reached the second tier(S2)and the third tier(S3)of the aviary.During the observation period,an average of 2.42% of hens climbed and stayed at the upper tiers every day.Space allowance on floor of the first tier(S1)increased from 444.62 cm^(2)/hen(91 d)to 586.32 cm^(2)/hen(100 d),which was more than 540 cm^(2)/hen in the CC system.Comfort behaviors in the LCAU system were significantly more than in the CC system(p<0.01)and hens performed more comfort behaviors with the increase of days after transferred.Hens ate and drank less in the LCAU system in the beginning,however,with the increasing use of upper space,hens ate and drank more and more in the LCAU system during the 10 days after transferred from CC system.Consequently,there were no difference of feed behavior between the CC and LCAU systems(p>0.05)on the last 5 days of the whole observing period.The results indicated that hens gradually learned to use the 3-dimensional space in the initial settling-in period and,gained a good welfare condition in LCAU system.Further studies are needed to investigate the three-dimensional preferences and behavior expression in difference period to bridge the gap in knowledge of space use capacity among adult laying hens.展开更多
文摘China’s electric power industry as a basic industry, plays an important role in the longterm, sustained and healthy development of the whole national economy. China’s electric power industry attained great achievement in technology and economical results during the past eight years from 1987-1995. The total national installed generating capacity increased from 102.897 GW in 1987 to more than 200 GW in March, 1995.
基金Project supported by the National Natural Science Foundation of China(Grant No.51179056)
文摘With respect to the crest spillway with large unit discharge and low Froude number, the hydraulics of the slit-type energy dissipater at the outlet should be noticed due to the complicated flow regimes. In the present paper, some issues about hydraulic characteristics were experimentally investigated by means of five slit-type outlets and four tetrahedrons, including the flow choking, impact to river banks and jet trajectory. The main findings are as follows. The critical Froude number for the flow choking decreases with increasing outlet width of the slit-type energy dissipater. If the flow Froude number is expressed by the parameters just before this energy dissipater, the tetrahedron placed inside the side wall of the outlet could efficiently avoid the flow impact to the river bank of same side, and compared with the jet trajectory of the slit-type energy dissipater, the outlet with tetrahedron has different trajectory trend, i.e., the distance of the jet trajectory decreases with the increase of the water head due to special form of the outlet tetrahedron.
文摘Introduction to HEC Harbin Electric Machinery Company Limited (HEC) is a pivotal company that produces large electric machinery and accessorial control equipment in China. The hydro units made by HEC have
基金National Science and Technology Support Program of China(No.2006BAG04B0)
文摘Sutong Bridge is a cable-stayed bridge with a steel box girder and a main span of 1 088 m.The steel box girder of main span includes five portions:back span large unit,large block of pylon,standard girder,back span closure girder and middle span closure girder.Each back span large unit is fabricated by welding several deck segments together in factory,and is erected by floating crane.As navigational clearance of the main bridge is high,the traditional truss lifting device can't satisfy the requirement of domestic lifting cranes for this kind of lifting height and weight.Hence,a kind of lighter lifting device for the erection of back span large units was accepted for this bridge.In this paper,the design and use of this lifting device is introduced.The upper structure used lifting gantry to install the standard girder segment by cantilever method.Because the bridge's navigation clearance is high,and the girder segment is wide and heavy,the meteorology and hydrology condition of the bridge district is abominable,and the requirements of long cable girder side pull-in,structure and performance propose high request to the lifting gantry.In this paper,the design and use key point of long cable pull-in angle adjustment device integrate into lifting gantry is introduced.
基金The authors wish to acknowledge the financial support of the Beijing Science&Technology Commiittee Special Project(Z171100002217018)China Agricultural Research System(CARS-40)Natural Science Foundation of China(31601981).
文摘Pullets often raised in cage system from week 1 to week 13 in China,when transferred to aviary system after,there will be a problem with adapt.A large cage aviary unit(LCAU)system was developed,which allocated with facilities such as ramps to help cage reared hens to adapt to the multi-tier space.To investigate hens’adaptability to the new system,space use over time in the LCAU system during the first 10 days after hens transferred were recorded,instantaneous scan sampling and continuous focal sampling were used to assess the behavior difference of hens between the LCAU and conventional cage(CC)systems.On the first day of arrival,10.03% of hens reached the second tier(S2)and the third tier(S3)of the aviary.During the observation period,an average of 2.42% of hens climbed and stayed at the upper tiers every day.Space allowance on floor of the first tier(S1)increased from 444.62 cm^(2)/hen(91 d)to 586.32 cm^(2)/hen(100 d),which was more than 540 cm^(2)/hen in the CC system.Comfort behaviors in the LCAU system were significantly more than in the CC system(p<0.01)and hens performed more comfort behaviors with the increase of days after transferred.Hens ate and drank less in the LCAU system in the beginning,however,with the increasing use of upper space,hens ate and drank more and more in the LCAU system during the 10 days after transferred from CC system.Consequently,there were no difference of feed behavior between the CC and LCAU systems(p>0.05)on the last 5 days of the whole observing period.The results indicated that hens gradually learned to use the 3-dimensional space in the initial settling-in period and,gained a good welfare condition in LCAU system.Further studies are needed to investigate the three-dimensional preferences and behavior expression in difference period to bridge the gap in knowledge of space use capacity among adult laying hens.
