硅锥场发射阴极电热状态的数值模拟

用有限差分法求解相互耦合的电流连续方程和导热方程 ,对硅锥阴极的电热状态进行了数值模拟。模拟中采用了与温度、电场相关电导率模型以及和温度相关的热导率模型。模拟的结果表明 ,锥体顶端的电位变化比较突出 ,在较小的电流下其内部电场即可以达到临界场强 ,使载流子漂移速度开始饱和 ,并表现出饱和的发射特性。在尖锥顶端内部电场达到临界场强直至发生碰撞电离时 。

铝电解槽阴极母线电热状态研究

系统研究了不同因素对铝电解槽母线电热状态的影响。研究表明,对于电流密度较低的铸造大母线,表面积大小对压降和母线温度影响很小,但环境温度对二者影响明显;母线横断面尺寸相同时,电流密度提高,压降加速升高;阴极软带压降和温度受电流密度和钢棒传热的共同影响;软带厚度越大,钢棒传热越起主导作用。

Electricity Storage With High Roundtrip Efficiency in a Reversible Solid Oxide Cell Stack

We theoretically investigate the electricity storage/generation in a reversible solid oxide cell stack. The system heat is for the first time tentatively stored in a phase-change metal when the stack is operated to generate electricity in a fuel cell mode and then reused to store electricity in an electrolysis mode. The state of charge （H2 frication in cathode） effectively enhances the open circuit voltages （OCVs） while the system gas pressure in electrodes also increases the OCVs. On the other hand, a higher system pressure facilitates the species diffusion in electrodes that therefore accordingly improve electrode polarizations. With the aid of recycled system heat, the roundtrip efficiency reaches as high as 92% for the repeated electricity storage and generation.

Status in quo and future of geothermal energy in China

Energy saving and CO2 emissions reduction are critical tasks currently,and great effort has been made by Chinese government. Renewable energy consumption and CO2 emissions and reduction plan in China are introduced in this paper. Analysis is also made on present status and prospect of geothermal power generation and direct use in China respectively. Now,there is a new understanding of geothermal resources,and hot dry rock,considered as the future of geothermal resources,is likely used to generate electricity.

Thermodynamic analyses and optimization for thermoelectric devices:The state of the arts

Thermoelectric effect is the most efficient way to convert electric energy directly from the temperature gradient. Thermoelectric effect-based power generation, cooling and heating devices are solid-stated, environmentally friendly, reliable, long-lived, easily maintainable, and easy to achieve miniaturization and integration. So they have unparalleled advantages in the aerospace, vehicle industry, waste heat recovery, electronic cooling, etc. This paper reviews the progress in thermodynamic analyses and optimizations for single- and multiple-element, single- and multiple-stage, and combined thermoelectric generators, thermoelectric refrigerators and thermoelectric heat pumps, especially in the aspects of non-equilibrium thermodynamics and finite time thermodynamics. It also discusses the developing trends of thermoelectric devices, such as the heat sources of thermoelectric generators, multi-stage thermoelectric devices, combined thermoelectric devices, and heat transfer enhancement of thermoelectric devices.

Stretchable electrothermochromic fibers based on hierarchical porous structures with electrically conductive dual-pathways

Stretchable color-changing fibers are urgently demanded for smart textiles/clothing due to their perfect implantability,permeability of vapor and heat,and flexibility/stretchability.Herein,stretchable electrothermochromic fibers were fabricated with unconventional stretchable conductive fibers as core layers and thermochromic coatings as shell layers.In the stretchable conductive fibers,hierarchical porous structures with percolative one-dimensional(1 D)conductive networks were constructed through phase inversion of carbon nanotube/polyurethane(CNT/PU)solutions.With the deposition of silver nanoparticles(AgN Ps)on the surface of micro-pores,electrically conductive dual-pathways consisting of0 D AgN Ps and 1 D CNTs were formed to significantly enhance the electric conductivity and thus improve the electrothermal performance of the fibers.More importantly,because of the connective CNTs and AgN Ps,such dual-pathways ensured the electron transport under the stretching state,preventing the sharp decay of conductivity and electrothermal performance.Through the continuous wet-spinning method,the stretchable conductive fibers can be easily obtained with the length up to several meters.At last,stretchable electrothermochromic fibers were prepared with two color-changing modes and implanted into textile perfectly,advancing their applications in wearable display and military adaptive camouflage of smart clothing.

Effect of electroacupuncture on muscle state and infrared thermogram changes in patients with acute lumbar muscle sprain

OBJECTIVE:To observe the effect of electroacupuncture(EA) on force-displacement value(FDV)of muscle state and the temperature index of infrared thermogram in patients with acute lumbar muscle sprain.METHODS:Patients with acute lumbar muscle sprain were randomly divided into a medication group and an EA group.The medication group(n-60) were treated with diclofenac sodium dual release enteric-coated capsules,75 mg per day for 7days.The EA group(n = 60) received EA at bilateral Houxi(SI 3),Jiaji(EX-B2),and Ashi points,at 20-30 mm depth and 10-25 Hz frequency for 20 min daily for 7 days.Muscle states were determined by measuring FDVs of the bilateral lumbar muscle with a Myotonometer fast muscle state detector.The temperature index of the lumbar skin was measured before and after treatment with a Fluke Ti30 non-refrigerated focal plane infrared thermal imaging detector.RESULTS:There were no significant pre-treatment differences between the medication group and the EA group in mean FDV(P = 0.052) or temperature index of the lumbar skin(P = 0.25).The cure rate was 63.3%in the EA group and 53.3%in the medication group.The total efficacy in the EA group(93.3%) was not significantly different from that in the medication group(86.6%,P = 0.204).After treatment,the mean FDV of the lumbar muscle significantly increased in both groups(P < 0.05 for both groups);the FDV increase in the EA group was significantly higher than in the medication group(P = 0.015).The temperature index was also significantly increased in both groups(P < 0.05 for both groups);the infrared thermogram in the EA group indicated significantly greater recovery compared to the medication group(P = 0.026).CONCLUSION:Both EA and diclofenac sodium markedly improved acute lumbar sprain,but EA better improved the rehabilitation and regeneration of FDVs and temperature index of infrared thermogram of the muscle.