Magnetic-liquid double suspension bearing(MLDSB)is a new type of suspension bearing based on electromagnetic suspension and supplemented by hydrostatic supporting.Without affecting the electromagnetic suspension force...Magnetic-liquid double suspension bearing(MLDSB)is a new type of suspension bearing based on electromagnetic suspension and supplemented by hydrostatic supporting.Without affecting the electromagnetic suspension force,the hydrostatic supporting effect is increased,and the real-time coupling of magnetic and liquid supporting can be realized.However,due to the high rotation speed,the rotor part produces eddy current loss,resulting in a large temperature rise and large ther-mal deformation,which makes the oil film thickness deviate from the initial design.The support and bearing characteristics are seriously affected.Therefore,this paper intends to explore the internal effects of eddy current loss of the rotor on the temperature rise and thermal deformation of MLDSB.Firstly,the 2D magnetic flow coupling mathematical model of MLDSB is established,and the eddy current loss distribution characteristics of the rotor are numerically simulated by Maxwell software.Secondly,the internal influence of mapping relationship of structural operating parameters such as input current,coil turns and rotor speed on rotor eddy current loss is revealed,and the changing trend of rotor eddy current loss under different design parameters is explored.Thirdly,the eddy cur-rent loss is loaded into the heat transfer finite element calculation model as a heat source,and the temperature rise of the rotor and its thermal deformation are simulated and analyzed,and the influ-ence of eddy current loss on rotor temperature rise and thermal deformation is revealed.Finally,the pressure-flow curve and the distribution law of the internal flow field are tested by the particle image velocimetry(PIV)system.The results show that eddy current loss increases linearly with the in-crease of coil current,coil turns and rotor speed.The effect of rotational speed on eddy current loss is much higher than that of coil current and coil turns.The maximum temperature rise,minimum temperature rise and maximum thermal deformation of the rotor increase with the increase of eddy current loss.The test results of flow-pressure and internal trace curves are basically consistent with the theoretical simulation,which effectively verifies the correctness of the theoretical simulation.The research results can provide theoretical basis for the design and safe and stable operation of magnetic fluid double suspension bearings.展开更多
Objective The aim of this study was to investigate macular perfusion changes and ganglion cell complex(GCC)loss in patients with unexplained visual loss following vitrectomy and silicone oil(SO)tamponade,and to evalua...Objective The aim of this study was to investigate macular perfusion changes and ganglion cell complex(GCC)loss in patients with unexplained visual loss following vitrectomy and silicone oil(SO)tamponade,and to evaluate the correlation between retinal blood flow and GCC loss using optical coherence tomography angiography(OCTA)and optical coherence tomography(OCT).Methods This retrospective study included seven eyes(seven patients)with unexpected visual loss after vitrectomy and SO tamponade.OCTA was used to evaluate the alterations in retinal vessel density(VD)in the superficial capillary plexus(SCP),deep capillary plexus(DCP),and radial peripapillary capillary plexus(RPCP).OCT was used to measure the thickness of GCC and retinal nerve fiber layer(RNFL).Medical records of patients were reviewed.Results Quantitative analysis of OCTA images revealed a significant reduction in SCP VD in the affected eyes compared with the controls(all sections P<0.05).No difference was found in GCC thickness,but FLV(focal loss volume)and GLV(global loss volume)were significantly higher in the affected eyes(both P<0.001).SCP VD was inversely correlated with FLV and GLV.Conclusions Silicone oil-related severe visual loss was associated with superficial retinal microvasculature damage and ganglion cell apoptosis.展开更多
CNOOC Limited,of which China National Offshore Oil Corporation(CNOOC)is the parent,recently posted its first-ever half-year loss as the plunge of crude oil prices destroy the profit at China’s biggest offshore oil an...CNOOC Limited,of which China National Offshore Oil Corporation(CNOOC)is the parent,recently posted its first-ever half-year loss as the plunge of crude oil prices destroy the profit at China’s biggest offshore oil and gas producer.The company swung to a 7.74 billion yuan(USD1.16billion)loss in the January-June period,compared to a展开更多
目的研究中药挥发油透皮促渗苷类成分效果与对经皮水分散失量(Transepidermal water loss,TEWL)的相关性。方法采用HPLC法测定3种苷类成分(栀子苷、龙胆苦苷、芍药苷)的含量及油水分配系数,采用改良Franz扩散池法以离体SD大鼠腹部皮肤...目的研究中药挥发油透皮促渗苷类成分效果与对经皮水分散失量(Transepidermal water loss,TEWL)的相关性。方法采用HPLC法测定3种苷类成分(栀子苷、龙胆苦苷、芍药苷)的含量及油水分配系数,采用改良Franz扩散池法以离体SD大鼠腹部皮肤为透皮吸收屏障进行体外透皮实验,考察高良姜、干姜、薄荷、胡椒和吴茱萸5种中药挥发油对3种苷类成分的体外透皮促渗效果,采用经皮水分散失量评价5种中药挥发油对大鼠皮肤屏障功能的影响,通过相关性分析考察中药挥发油透皮促渗苷类成分效果与其对皮肤屏障功能影响之间的相关性。结果高良姜油、干姜油、薄荷油、胡椒油能促进3种苷类成分的透皮吸收,也能显著降低大鼠的皮肤屏障功能,相关性分析结果表明中药挥发油对苷类成分的透皮促渗效果与其对皮肤经皮水分散失量的影响显著相关。结论TEWL为中药挥发油透皮促渗剂的快速筛选提供了一种简便快捷的在体评价方法。展开更多
基金the Natural Science Foundation of Hebei Province(No.E2020203052)the S&T Program of Hebei(No.236Z1901G).
文摘Magnetic-liquid double suspension bearing(MLDSB)is a new type of suspension bearing based on electromagnetic suspension and supplemented by hydrostatic supporting.Without affecting the electromagnetic suspension force,the hydrostatic supporting effect is increased,and the real-time coupling of magnetic and liquid supporting can be realized.However,due to the high rotation speed,the rotor part produces eddy current loss,resulting in a large temperature rise and large ther-mal deformation,which makes the oil film thickness deviate from the initial design.The support and bearing characteristics are seriously affected.Therefore,this paper intends to explore the internal effects of eddy current loss of the rotor on the temperature rise and thermal deformation of MLDSB.Firstly,the 2D magnetic flow coupling mathematical model of MLDSB is established,and the eddy current loss distribution characteristics of the rotor are numerically simulated by Maxwell software.Secondly,the internal influence of mapping relationship of structural operating parameters such as input current,coil turns and rotor speed on rotor eddy current loss is revealed,and the changing trend of rotor eddy current loss under different design parameters is explored.Thirdly,the eddy cur-rent loss is loaded into the heat transfer finite element calculation model as a heat source,and the temperature rise of the rotor and its thermal deformation are simulated and analyzed,and the influ-ence of eddy current loss on rotor temperature rise and thermal deformation is revealed.Finally,the pressure-flow curve and the distribution law of the internal flow field are tested by the particle image velocimetry(PIV)system.The results show that eddy current loss increases linearly with the in-crease of coil current,coil turns and rotor speed.The effect of rotational speed on eddy current loss is much higher than that of coil current and coil turns.The maximum temperature rise,minimum temperature rise and maximum thermal deformation of the rotor increase with the increase of eddy current loss.The test results of flow-pressure and internal trace curves are basically consistent with the theoretical simulation,which effectively verifies the correctness of the theoretical simulation.The research results can provide theoretical basis for the design and safe and stable operation of magnetic fluid double suspension bearings.
基金supported by Capital Medical University Affiliated Beijing Tongren Hospital Key Medical Development Plan[trzdyxzy201801].
文摘Objective The aim of this study was to investigate macular perfusion changes and ganglion cell complex(GCC)loss in patients with unexplained visual loss following vitrectomy and silicone oil(SO)tamponade,and to evaluate the correlation between retinal blood flow and GCC loss using optical coherence tomography angiography(OCTA)and optical coherence tomography(OCT).Methods This retrospective study included seven eyes(seven patients)with unexpected visual loss after vitrectomy and SO tamponade.OCTA was used to evaluate the alterations in retinal vessel density(VD)in the superficial capillary plexus(SCP),deep capillary plexus(DCP),and radial peripapillary capillary plexus(RPCP).OCT was used to measure the thickness of GCC and retinal nerve fiber layer(RNFL).Medical records of patients were reviewed.Results Quantitative analysis of OCTA images revealed a significant reduction in SCP VD in the affected eyes compared with the controls(all sections P<0.05).No difference was found in GCC thickness,but FLV(focal loss volume)and GLV(global loss volume)were significantly higher in the affected eyes(both P<0.001).SCP VD was inversely correlated with FLV and GLV.Conclusions Silicone oil-related severe visual loss was associated with superficial retinal microvasculature damage and ganglion cell apoptosis.
文摘CNOOC Limited,of which China National Offshore Oil Corporation(CNOOC)is the parent,recently posted its first-ever half-year loss as the plunge of crude oil prices destroy the profit at China’s biggest offshore oil and gas producer.The company swung to a 7.74 billion yuan(USD1.16billion)loss in the January-June period,compared to a
文摘目的研究中药挥发油透皮促渗苷类成分效果与对经皮水分散失量(Transepidermal water loss,TEWL)的相关性。方法采用HPLC法测定3种苷类成分(栀子苷、龙胆苦苷、芍药苷)的含量及油水分配系数,采用改良Franz扩散池法以离体SD大鼠腹部皮肤为透皮吸收屏障进行体外透皮实验,考察高良姜、干姜、薄荷、胡椒和吴茱萸5种中药挥发油对3种苷类成分的体外透皮促渗效果,采用经皮水分散失量评价5种中药挥发油对大鼠皮肤屏障功能的影响,通过相关性分析考察中药挥发油透皮促渗苷类成分效果与其对皮肤屏障功能影响之间的相关性。结果高良姜油、干姜油、薄荷油、胡椒油能促进3种苷类成分的透皮吸收,也能显著降低大鼠的皮肤屏障功能,相关性分析结果表明中药挥发油对苷类成分的透皮促渗效果与其对皮肤经皮水分散失量的影响显著相关。结论TEWL为中药挥发油透皮促渗剂的快速筛选提供了一种简便快捷的在体评价方法。
