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The layout environments of the extra-high voltage (EHV) submarine cable are complex and changeable,and the ampacity of the EHV submarine cable varies under different layout environments. Therefore,it is essential to analyze the ampacity of the EHV submarine cable in typical layout environments. In this paper,a steady-state thermal circuit model for the alternating current (AC) 500 kV cross linked polyethylene (XLPE) EHV submarine cable based on IEC 60287 standard is established,and the influences of layout sections,layout methods,environment temperatures,and layout depths on the ampacity of EHV submarine cable are studied. The results of the steady-state thermal circuit model are verified by a multi-physical field finite element model. It is found that the landing section of the submarine cable is the bottleneck section of ampacity of the whole line. When the submarine cable in the landing section is laid by pipeline method,the ampacity is about 150 A lower than that by the direct burial layout method.The ampacity of submarine cable decreases with the environment temperature and the layout depth. The finite element calculation results verify the accuracy of the results of the steady-state thermal circuit model.

The spatial–temporal distribution of reactive oxygen species (ROS) in human tissue is critical for the medical applications of cold plasma jet as it reflects the therapeutic range of cold plasma jet, but the mechanism for its formation is still unclear. To this end, KI-starch reagent was used to visualize the surface distributions of ROS on the model human tissues treated by a He + O2 plasma jet in this paper. It was found that the surface distribution of ROS was divided into two parts by a small donut-shaped of un-colored area. This un-colored area was resulted from the color fading of the model tissue, which might be induced by the AC electric field of the plasma jet and the plasma-generated reductive species. The colored area and the un-colored area had different trends with the working gas flow rate and the model tissue conductivity. The un-colored area increased with the expansion of the plasma plume and shrank with the increasing model tissue conductivity. [ABSTRACT FROM AUTHOR]

Vacuum circuit breakers (VCBs) are widely used to protect medium-voltage (MV) power distribution circuits. Since [SF.sub.6] gas is specified as a global warming gas, VCBs are stepping into a higher voltage sector to protect power transmission circuits. Axial magnetic field (AMF) contacts are widely used in vacuum interrupters. In this paper, we propose a concept of critical radius of AMF contacts. When coil width and coil height are fixed, the axial magnetic flux density increases first with increasing contact diameter. Then, it reaches a maximum value. Thereafter, the axial magnetic flux density decreases. The contact radius corresponding to the maximum axial magnetic flux density is critical radius. The concept of critical radius is validated by coil-type AMF contacts and slot-type AMF contacts in MV vacuum interrupters with finite-element analysis. Critical radius is only related to contact geometry parameters and the current has no influence on critical radius. Critical radius increases with increasing contact gap, coil width, coil height, and thickness of the contact plate. In high-voltage AMF vacuum interrupters, axial magnetic flux density per kiloampere increases with increasing contact diameter since the critical radius is typically high with a high contact gap and it is in the rising branch. In an MV AMF vacuum interrupter, interrupting capacity could increase with an increase of the contact diameter with a different rising rate before and after the critical radius. This is expected to be experimentally validated. Index Terms--Axial magnetic field (AMF), vacuum circuit breakers (VCBs), vacuum interrupters.

We compared vacuum arc behaviors of three slottype axial-magnetic-field (AMF) contacts at two fixed contact gaps using high-speed digital photography and arc-voltage measurements. Solid angle is subtended by anode at the center of cathode or the ratio of the anode diameter to the gap length (D/g). With Coupled influence of the AMF, we observed that with the D/g ratio 48 mm/14 mm, the arc kept in low current modes until higher current compared with the DIg ratio 48 mm/8 mm case. With the D/9 ratio 58 mm/14 mm, the arc-mode transitions with the increase of current were similar as the D/g ratio 58 mm/8 mm case. However, with the D/g ratio 66 mm/14 mm, the arc became high current modes at lower current compared with the D/g ratio 66 ram/8 mm case. Correspondingly, with the D/g ratio 48 mm/ 14 mm, arc voltages at current peaks were close to the D/g ratio 48 mm/8 mm case, whereas arc voltages at current peaks with the D/g ratio 58 mm/14 mm were close to that of the 58 mm/ 8 mm case. However, with a contact diameter of 66 mm, the arc voltages with the D/g ratio 66 mm/14 nun were higher than the 66 mm/8 mm case. The arcs with the D/g ratio 66 mm/8 mm were more diffuse than the 48 ram/8 mm case. Moreover, the arcs with the D/g ratio 66 mm/14 mm were also more diffuse than the 48 mm/14 mm case when the current peak was 17.8 kA and above. The relationship between interrupting capacity of vacuum interrupters with the slot-type AMF contacts could be expressed as I = k x (D/g) + b, where k and b are constants. Index Terms--Are modes, arc voltage, axial magnetic field (AMF), vacuum arcs, vacuum interrupter.

Objective: To explore the different imaging manifestations of osteonecrosis of the femoral head (ONFH) and their correlation with the occurrence of pain during the peri-collapse period., Methods: The 372 patients (624 hips) with ONFH in the peri-collapse stage who were admitted between December 2016 and October 2019 and met the selection criteria were selected as the research objects. Among them, there were 270 males and 102 females, with an average age of 35.3 years (mean, 15-65 years). There were 120 cases of unilateral hip and 252 cases of bilateral hips. There were 39 cases (39 hips) of traumatic ONFH, 196 cases (346 hips) of hormonal ONFH, 102 cases (178 hips) of alcoholic ONFH, and 35 cases (61 hips) of idiopathic ONFH. Among them, there were 482 hips with pain symptoms and 142 hips without pain. The pain duration was less than 3 months in 212 hips, 3-6 months in 124 hips, 6-12 months in 117 hips, and more than 12 months in 29 hips. According to the Association Research Circulation Osseous (ARCO) staging, the ONFH was rated as stage Ⅱ in 325 hips and stage Ⅲ in 299 hips. The patients were grouped according to ONFH etiology and ARCO staging, and hip joint pain and X-ray film (crescent sign and cystic changes), CT (subchondral bone fractures and cystic changes), and MRI (bone marrow edema, joint effusion, and subchondral hypointensity zone) were compared. Spearman rank correlation was used to determine the correlation between ONFH pain duration and X-ray film, CT, and MRI imaging manifestations., Results: There were significant differences ( P <0.05) between ONFH patients with different etiologies in crescent sign on X-ray film, subchondral bone fracture on CT, and joint effusion on MRI. And there were significant differences ( P <0.05) between ONFH patients with different ARCO stages in hip pain duration and all imaging manifestations. Correlation analysis showed that the pain duration of ONFH patients was correlated with all imaging manifestations ( P <0.05). The cystic change on CT was correlated with the subchondral hypointensity zone and joint effusion grade on MRI, and subchondral hypointensity zone and joint effusion grade on MRI were also correlated ( P <0.05)., Conclusion: The cystic changes, subchondral hypointensity zone, and joint effusion are closely related to the collapse of the femoral head and hip pain in patients with ONFH in the peri-collapse stage. The above-mentioned signals in stage Ⅱ ONFH indicate the instability of the femoral head, which is to predict the development of ONFH and the rational choice of hip-preserving treatment methods provides a basis.