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1. chinaXiv:202001.00047 [pdf]
Review of the high-power vacuum tube microwave sources
徐伟业Subjects: Electronics and Communication Technology >> Electron Technology
| Since the first vacuum tube (X-ray tube) was invented by Wilhelm Röntgen in Germany, after more than one hundred years of development, the average power density of the vacuum tube microwave source has reached the order of 108 [MW][GHz]2. The maximum power density record was created by the Free Electron Lasers. In the high-power microwave field, the vacuum devices are still the mainstream microwave sources for applications such as scientific instruments, communications, radars, magnetic confinement fusion heating, microwave weapons, etc. The principles of microwave generation by vacuum tube microwave sources include Cherenkov or Smith-Purcell radiation, transition radiation, and Bremsstrahlung. In this paper, the vacuum tube microwave sources were reviewed in order according to the three radiation principles. Among them, the Vircators can produce 22 GW output power in P-band. Vacuum tubes that can achieve continuous-wave operation include Traveling Wave Tubes, Klystrons, Free Electron Lasers, and Magnetrons, with output power up to 1MW. Vacuum tubes that can generate frequencies of the order of 100 GHz and above include Klystrons, Traveling Wave Tubes, Gyrotrons, Backward Wave Oscillators, Magnetrons, Surface Wave Oscillators, Free Electron Lasers, Orotrons, etc. Gyrotrons are very attractive in the millimeter wave and THz fields. The Gyrotrons can output power at the MW level with 3000s pulse width at millimeter wavelengths. |
2. chinaXiv:202001.00062 [pdf]
李杰彪; 苏锐; 周志超; 郭永海; 季瑞利; 张明; 王洪斌Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
| 地下水补给研究是高放废物深地质处置库选址和场址评价的重要研究内容之一。甘肃北山地区是我国高放废物地质处置库场址首选预选区，为查明该区地下水补给特征，基于环境示踪剂氯查明了北山地区浅部地下水补给量。结果表明：（1） 总体而言，氯质量平衡方法在北山地区应用效果较好。（2） 基于包气带的氯质量平衡方法计算得出的浅部地下水垂向补给量在渗透性较大的沟谷盆地中为0.07~2.03 mm·a-1，平均值约1.0 mm·a-1。（3） 基于饱和带的氯质量平衡方法计算得出北山地区浅部地下水多年平均入渗补给量为0.25 mm·a-1，不足多年平均降水量的0.5%。相关结果可为我国高放废物地质处置库选址和场址评价提供依据。 |
submitted time 2020-01-06 From cooperative journals:《干旱区地理》 Hits315， Downloads30， Comment 0
3. chinaXiv:201911.00009 [pdf]
胡锦文Subjects: Physics >> Geophysics, Astronomy, and Astrophysics
| 在洛伦兹破缺模型中，彩虹模型通常被讨论，因为彩虹模型可以使一个粒子的能量有一个极限，而不是由洛伦兹变换中得到的无限大，这在量子引力理论中被认为是必要的。然而,本文表明一开始并没有必要限制光速是一个常数,当我们约定如下三个原则:(1)我们可以用校准的时钟定义整个空间的同时性,(2)时空是均匀的,空间各向同性和(3)所有的惯性系统是等价的。基于上述三原则,我们可以构造一个通用坐标变换来满足惯性系统的对称性，并可以在惯性系统之间构建一个non-Lorentz变换使得粒子的能量有一个极限值,就像和彩虹模型一样。 此外，在最近的论文中，作为一种超高能量尺度的测试，彩虹模型被用来研究伽马射线爆发，如GRB 160509A事件，它强烈地表明了光速的变化与光子能量之间存在线性关系。所以我们也分析了同样的事件，我们发现我们的模型也支持彩虹模型的结论，我们的模型和彩虹模型之间有一定的相关性。最后，我们简要讨论了如何在未来的高能粒子实验中验证这两个模型。 |
4. chinaXiv:201910.00053 [pdf]
Effects of biochar on water movement characteristics in sandy soil under drip irrigation
PU Shenghai; LI Guangyong1; TANG Guangmu; ZHANG Yunshu ; XU Wanli; LI Pan; FENG Guangping; DING FengSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
| Biochar addition can improve the physical and hydraulic characteristics of sandy soil. This study investigated the effects of biochar on water holding capacity and water movement in sandy soil under drip irrigation. By indoor simulation experiments, the effects of biochar application at five levels (0%, 1%, 2%, 4% and 6%) on the soil water retention curve, infiltration characteristics of drip irrigation and water distribution were tested and analyzed. The results showed that biochar addition rate was positively correlated with water holding capacity of sandy soil and soil available water. Within the same infiltration time, with an increasing amount of added biochar, the diffusion distance of the horizontal wetting front (HWF) tended to decrease, while the infiltration distance of vertical wetting front (VWF) initially declined and then rose. The features of wetted bodies changed from "broad-shallow" to "narrow-deep" type. The relationship between the transport distances of HWF and VWF and the infiltration time was described by a power function. At the same distance from the point source, the larger the amount of added biochar, the higher the soil water content. Biochar had a great influence on the water content of the layer with biochar (0–200 mm) and had some effects at 200–250 mm without biochar; but it had less influence on the soil water content deeper than 250 mm. For the application rate of biochar of 4%, most water was retained within 0–250 mm soil layer. However, when biochar application amount was high (6%), it would be helpful for water infiltration. During the improvement of sandy soil, biochar application rate of 4% in the plow layer had the best effect. |
submitted time 2019-10-26 From cooperative journals:《Journal of Arid Land》 Hits1724， Downloads176， Comment 0
5. chinaXiv:201910.00072 [pdf]
段德龙Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
| 为解决量子力学物理诠释的根本分歧，证明爱因斯坦对于量子力学的预测本文对海森堡不确定性（原理）关系式的数学形式进行概率分析；从个体基元过程的角度对海森堡与玻尔的电子单狭缝位置测定思想实验和爱因斯坦光子箱思想实验进行了重新检视。在数学上通过对概率分布及全概率空间的分析得到了不确定性关系被破坏的结果；对海森堡与玻尔的电子单狭缝位置测定思想实验和爱因斯坦光子箱思想实验进行的重新检视，获得了玻尔与海森堡原有论证不成立的结论。因篇幅所限未就纠缠作进一步的分析。在演绎（数学上的概率分析）与归纳（物理上的思想实验）两个方面，本文都获得了海森堡不确定性关系不成立的结果，证明了量子力学正统诠释难以保持其理论的自洽与逻辑一贯性 |
6. chinaXiv:201607.00046 [pdf]
Exact Solution for Three-Dimensional Ising Model
Zhang, DegangSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
| Three-dimensional Ising model in zero external field is exactly solved by operator algebras, similar to the Onsager's approach in two dimensions. The partition function of the simple cubic crystal imposed by the periodic boundary condition along both $(0 1 0)$ and $(0 0 1)$ directions and the screw boundary condition along the $(1 0 0)$ direction is calculated rigorously. In the thermodynamic limit an integral replaces a sum in the formula of the partition function. A order-disorder transition in the infinite crystal occurs at a temperature $T=T_c$ determined by the condition: $\sinh\frac{2J}{k_BT_c}\sinh\frac{2(J_1+J_2)}{k_BT_c}=1$, where $(J_1 J_2 J)$ are the interaction energies in three directions, respectively. The analytical expressions for the internal energy and the specific heat are also given. It is also shown that the thermodynamic properties of 3D Ising model with $J_1=J_2$ are connected to those in 2D Ising model with the interaction energies $(J_1 J_{2D})$ by the relation $(\frac{J_{2D}}{k_BT})^*=(\frac{J}{k_BT})^*-\frac{J_1}{k_BT}$, where $x^*=\frac{1}{2}{\rm ln coth} x={\rm tanh}^{-1}(e^{-2x})$. |
submitted time 2019-09-12 Hits5032， Downloads1376， Comment 0
7. chinaXiv:201909.00120 [pdf]
李淑霞; 刘亚斌; 钟鹏; 余冬梅; 胡夏嵩; 杨幼清Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
| 以西宁盆地长岭沟流域自建试验区为研究区，筛选出适宜当地气候条件下生长的2种灌木植物柠条锦鸡儿(Caragana korshinskii Kom.)、霸王〔Zygophyllum xanthoxylon (Bunge) Maxim.〕和2种草本植物细茎冰草(Agropyron trachycaulum cv. Slender)、紫花苜蓿(Medicago sativa Linn.)作为试验供试种，在试验区对4种植物采用单一种植和组合种植方式，探讨2种种植条件下植物根系在边坡地表以下垂直方向土体中K+、Ca2+、Na+、Mg2+、SO42-、Cl-、HCO3-、CO32-等8种易溶盐离子含量及其变化特征，评价了区内2种草本和2种灌木植物降低边坡土体盐分的能力。结果表明：单一种植细茎冰草、紫花苜蓿、柠条锦鸡儿、霸王对边坡土体中SO42-、Ca2+、Na+具有显著降低作用，草本与灌木组合Ⅰ(柠条锦鸡儿+紫花苜蓿+细茎冰草组合)和草本与灌木组合Ⅱ(霸王+紫花苜蓿+细茎冰草组合)对边坡土体中SO42、Ca2+、Mg2+、K+、Na+表现出显著降低作用；紫花苜蓿的降盐效果相对较为显著、其次为柠条锦鸡儿和细茎冰草，霸王的降盐效果不及前者显著；草本与灌木组合Ⅱ的降盐效果相对显著于草本与灌木组合Ⅰ。 |
submitted time 2019-09-09 From cooperative journals:《干旱区研究》 Hits3237， Downloads156， Comment 0
8. chinaXiv:201907.00026 [pdf]
Exact Solution of Quantum Rabi Model
Degang ZhangSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.
| Quantum Rabi model is exactly solved by employing the parameter-dependent unitary transformation method in the Bargmann space. The complete energy spectrum consists of two double-fold sub-energy spectra. The eigenvalue is determined by the parameter in the unitary transformation, which satisfies a highly nonlinear equation. Such the energy spectrum completely coincides with that obtained in the occupation number representation [D. Zhang, chinaXiv:201708.00168]. |
9. chinaXiv:201907.00002 [pdf]
Tiege ZhouSubjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties
| P. W. Anderson raised an important question in 2007: Is There Glue in Cuprate Superconductors? The author believes that the change of the electron clouds of ions is the glue in cuprate superconductors. The change of the electron clouds of the ions in the parent structure of the layered high-temperature superconductors CaCuO2 has been studied by the first-principles calculations. The electron clouds of Cu2+ and O2- ions change obviously under electric fields. It is also found, for the first time, the characteristic frequencies of the change of the electron clouds are 250 meV, 360 meV, and 100 meV, respectively, for the modes observed. The frequencies are low and close to that of lattice vibrations, indicating the change of the electron cloud of ions can be the electron-pairing medium in cuprate superconductors. |
10. chinaXiv:201906.00024 [pdf]
Tiege ZhouSubjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties
| It is proposed that the electron-pairing medium of the iron-based superconductors may be the orbital fluctuation of the transition metal ions. But the characteristic frequency of the orbital fluctuation has not been given. For the first time, the author has calculated the real-time evolution of the electron clouds of transition metal ions in BaFe2As2 under excitations by the time-dependent density functional theory (TDDFT). There are different modes of fluctuations. The characteristic frequencies are 150 meV, 160 meV, 250 meV, and 200 meV, respectively, for the modes the author observed. The results are unexpected, because the general view is that the change of the electron density is very quick, and the frequency is much higher than the lattice vibration. The frequencies the author obtained are close to that of the lattice vibration in conventional superconductors at normal and high pressures, indicating the orbital (or electron cloud) fluctuation can by the electron pairing medium. Based on the calculation results, the author proposed a new electron pairing mechanism. |
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