Space charge accumulation in the insulation layer of high-voltage direct current(HVDC)cable is one of the key factors restricting the development of HVDC cable.The inner semi-conductive layer as an important structure...Space charge accumulation in the insulation layer of high-voltage direct current(HVDC)cable is one of the key factors restricting the development of HVDC cable.The inner semi-conductive layer as an important structure of cable will affect the charge accumu-lation characteristics in the insulation layer.This work intends to explore the method of modifying the semi-conductive layer with graphene,to suppress charge accumulation in the insulation layer.First,the semi-conductive layer with different contents of Graphene(G)and carbon black(CB)are prepared.Second,the morphology and surface roughness of the cross section are analysed.Further,the effects of the semi-conductive layer on space charge accumulation of the insulation layer are studied by pulsed electro-acoustic method and thermal stimulation depolarisation current method.The experimental re-sults show that a moderate amount of graphene replacing CB can effectively reduce charge accumulation in the insulation layer and inhibit positive temperature coefficient(PTC)effect at the same time.The surface roughness of specimens decreases with the increase of G content from 0 to 3 phr(parts per hundreds of resin),when the CB content decreases from 25 to 10 phr,the surface roughness of specimen increases.The resistivity test shows that doping G can significantly inhibit the PTC effect of the semi-conductive layer.The volume resistivity of the semi-conductive layer decreases with the increase of G content and CB content.In addition,charge accumulation of the insulation layer rises and then drops under the action of the semi-conductive layer.展开更多
The annual rainfall is low and the fresh water resources are scarce for the rainfed farming in dry zone of northern China,which seriously affects the sowing and growth of spring corn. In order to solve this problem,th...The annual rainfall is low and the fresh water resources are scarce for the rainfed farming in dry zone of northern China,which seriously affects the sowing and growth of spring corn. In order to solve this problem,the technology of ridge-mulching and side-sowing of spring corn is put forward,the supporting compound operation seeder is developed,and the effect of different speed on the quality of sowing is tested and analyzed. Under the test conditions described in this paper,the seeding operation with a high speed( up to 6 km/h) can be realized,and the quality of the seeding operation can meet the requirements of the national standards. The application of this machine can solve the problem of " drought damage at the booting stage" for spring corn,thereby realizing the deep fusion of farming machine and agronomy in dry farming of northern China,and achieving the integration of farming machine and agronomy.展开更多
An expression vector pACⅢ containing the chimeric gene HAV- VP3P1 and HCV-C gene has been constructed and transferred to C. reinhardtii by the biolistic method. The trans-formants have been identified by PCR, Souther...An expression vector pACⅢ containing the chimeric gene HAV- VP3P1 and HCV-C gene has been constructed and transferred to C. reinhardtii by the biolistic method. The trans-formants have been identified by PCR, Southern-blotting, Northern-blotting and Western-blotting assays after selecting on resistant medium and incubating in the dark. The results展开更多
基金National Natural Science Foundation of China,Grant/Award Number:51907095State Key Laboratory of Electrical Insulation and Power Equipment,Grant/Award Number:EIPE21213。
文摘Space charge accumulation in the insulation layer of high-voltage direct current(HVDC)cable is one of the key factors restricting the development of HVDC cable.The inner semi-conductive layer as an important structure of cable will affect the charge accumu-lation characteristics in the insulation layer.This work intends to explore the method of modifying the semi-conductive layer with graphene,to suppress charge accumulation in the insulation layer.First,the semi-conductive layer with different contents of Graphene(G)and carbon black(CB)are prepared.Second,the morphology and surface roughness of the cross section are analysed.Further,the effects of the semi-conductive layer on space charge accumulation of the insulation layer are studied by pulsed electro-acoustic method and thermal stimulation depolarisation current method.The experimental re-sults show that a moderate amount of graphene replacing CB can effectively reduce charge accumulation in the insulation layer and inhibit positive temperature coefficient(PTC)effect at the same time.The surface roughness of specimens decreases with the increase of G content from 0 to 3 phr(parts per hundreds of resin),when the CB content decreases from 25 to 10 phr,the surface roughness of specimen increases.The resistivity test shows that doping G can significantly inhibit the PTC effect of the semi-conductive layer.The volume resistivity of the semi-conductive layer decreases with the increase of G content and CB content.In addition,charge accumulation of the insulation layer rises and then drops under the action of the semi-conductive layer.
基金Supported by Project of Bohai Granary in Hebei Province(2013BAD05B0504)Science and Technology Innovation Project of Hebei Academy of Agriculture and Forestry Sciences(F17C10007-4)
文摘The annual rainfall is low and the fresh water resources are scarce for the rainfed farming in dry zone of northern China,which seriously affects the sowing and growth of spring corn. In order to solve this problem,the technology of ridge-mulching and side-sowing of spring corn is put forward,the supporting compound operation seeder is developed,and the effect of different speed on the quality of sowing is tested and analyzed. Under the test conditions described in this paper,the seeding operation with a high speed( up to 6 km/h) can be realized,and the quality of the seeding operation can meet the requirements of the national standards. The application of this machine can solve the problem of " drought damage at the booting stage" for spring corn,thereby realizing the deep fusion of farming machine and agronomy in dry farming of northern China,and achieving the integration of farming machine and agronomy.
文摘An expression vector pACⅢ containing the chimeric gene HAV- VP3P1 and HCV-C gene has been constructed and transferred to C. reinhardtii by the biolistic method. The trans-formants have been identified by PCR, Southern-blotting, Northern-blotting and Western-blotting assays after selecting on resistant medium and incubating in the dark. The results
