- Nuclear Physics(791)
- General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.(563)
- The Physics of Elementary Particles and Fields(261)
- Physics(146)
- Condensed Matter: Structural, Mechanical and Thermal Properties(88)
- Interdisciplinary Physics and Related Areas of Science and Technology(29)
- Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics(20)
- Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties(20)
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Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Efficient agricultural water use is crucial for food safety and water conservation on a global scale. To quantitatively investigate the agricultural water-use efficiency in regions exhibiting the complex agricultural structure, this study developed an indicator named water footprint of crop values (WFV) that is based on the water footprint of crop production. Defined as the water volume used to produce a unit price of crop (m3/CNY), the new indicator makes it feasible to directly compare the water footprint of different crops from an economic perspective, so as to comprehensively evaluate the water-use efficiency under the complex planting structure. On the basis of WFV, the study further proposed an indicator of structural water-use coefficient (SWUC), which is represented by the ratio of water-use efficiency for a given planting structure to the water efficiency for a reference crop and can quantitatively describe the impact of planting structure on agricultural water efficiency. Then, a case study was implemented in Xinjiang Uygur Autonomous Region of China. The temporal and spatial variations of WFV were assessed for the planting industries in 14 prefectures and cities of Xinjiang between 1991 and 2015. In addition, contribution rate analysis of WFV for different prefectures and cities was conducted to evaluate the variations of WFV caused by different influencing factors: agricultural input, climatic factors, and planting structure. Results from these analyses indicated first that the average WFV of planting industries in Xinjiang significantly decreased from 0.293 m3/CNY in 1991 to 0.153 m3/CNY in 2015, corresponding to an average annual change rate of –3.532%. WFV in 13 prefectures and cities (with the exception of Karamay) has declined significantly during the period of 1991–2015, indicating that agricultural water-use efficient has effectively improved. Second, the average SWUC in Xinjiang decreased from 1.17 to 1.08 m3/CNY in the 1990s, and then declined to 1.00 m3/CNY in 2011–2015. The value of SWUC was highly consistent with the relative value of WFV in most prefectures and cities, showing that planting structure is one of the primary factors affecting regional agricultural water-use efficiency. Third, the contribution rate of WFV variations from human factors including agricultural input and planting structure was much more significant than that from climatic factors. However, the distribution of agricultural input and the adjustment of planting structure significantly differed among prefectures and cities, suggesting regional imbalances of agricultural development. This study indicated the feasibility and effectiveness of controlling agricultural water use through increasing technical input and rational selection of crops in the face of impending climate change. Specifically, we concluded that, the rational application of chemical fertilizers, the development of the fruit industry, and the strict restriction of the cotton industry should be implemented to improve the agricultural water-use efficiency in Xinjiang. |

submitted time
2020-10-20
From cooperative journals:《Journal of Arid Land》
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REBCO短样经热处理后的临界电流能力测试与性能退化情况分析

Lang Qin; QL Wang; Lei Wang; HB Sun; JH LiuSubjects: Physics >> Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics

REBCO超导磁体制作过程中，需要使用桥接连接相邻的双饼，桥接部位REBCO带材经过高温焊接过程，性能可能发生退化。本论文对REBCO材料性能退化进行了实际测试，并简单介绍了其原因。实验通过高温热处理来模拟REBCO带材桥接时的高温过程，获得了经过不同温度与时长热处理后的REBCO短样，并在液氮条件下进行了临界电流能力测试，与未经热处理的REBCO带材进行对比，分析了几种带材性能退化的程度及在实际磁体组装中的影响。本论文的结论能够对REBCO带材的处理、接头的工艺和磁体的制作起到一定积极作用。 |

Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

[目的] 分析解决不确定性原理及量子理论在物理诠释方面的分歧。 [方法] 对海森堡不确定性原理数学关系式的原始推导、物理涵义以及爱因斯坦光子箱思想实验进行了重新检视分析，并考察了不同作用图景下该关系式的极限。 [结果] 在电磁作用图景下，通过对量子力学量的统计分布及其全概率空间的分析，首次获得了非统计诠释下的不确定性关系式在数学上被破坏的结果；利用傅里叶变换，导出了虚拟作用图景下相应共轭力学量的标准差约束关系式；通过考察电磁作用图景、引力作用图景以及虚拟作用图景所构成的集合，率先得到了微观量子客体力学状态的确定性判则；经过对爱因斯坦光子箱思想实验的重新检视分析，证伪了玻尔在索尔维会议上的论证结论。 [局限]未分析量子纠缠。 [结论] ①非统计诠释存在逻辑矛盾，不确定性关系、现行量子力学理论仅在统计诠释下，才能对微观量子客体在电磁作用图景中的力学状态作出恰当的描述；② 确定性判则显示，微观粒子的力学状态具有客观确定性，其波函数是对电磁作用图景下的微观粒子力学状态统计呈现相的表述；量子力学非统计诠释所指称的个体几率性实质是微观粒子与作用图景之间互作用统计呈现相的概率反映。 |

submitted time
2020-09-28
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A study of a scalar field probes micro space-time

Jian-Bo Deng; Miao-Yi Deng; Qi-Qi FanSubjects: Physics >> The Physics of Elementary Particles and Fields

In this work, we try to find a way to describe the physical law of micro-world under the frame of a space-time theory. By introducing a scalar field D(x), we rewrite the action of conventional field theory and the Lagrangian describing the motion of the particle, where a modified space-time relation is obtained. To prove the correctness of this attempt, we derive the Klein-Gordon equation by the Hamilton-Jacobi method in four dimensional form. |

Note on anomalies in field theories

刘昌勇Subjects: Physics >> The Physics of Elementary Particles and Fields

In this note, we investigate the anomalies in field theories. The results of the anomalies through Feynman diagrams calculation are multi-valued function. These single-valued branches of multi-valued function are related to the bound states of neutral pseudoscalar mesons. Adding these bound state contributions, we obtain a new anomaly free condition that all the external particles are on-shell and find the non-perturbative mass spectrum of neutral pseudoscalar mesons. We also discuss the anomaly in 2 dimensional QFT. |

Shadows of rotating Hayward-de Sitter black holes with astrometric observables

Peng-Zhang He; Qi-Qi Fan; Hao-Ran Zhang; Jian-Bo DengSubjects: Physics >> Geophysics, Astronomy, and Astrophysics

Motivated by recent work on rotating black hole shadow [Phys. Rev. D101, 084029 (2020)], we investigate the shadow behaviors of rotating Hayward-de Sitter black hole for static observers at a finite distance in terms of astronomical observables. This paper uses the newly introduced distortion parameter in [arXiv:2006.00685] to describe the shadow's shape quantitatively. We show that the spin parameter would distort shadows and the magnetic monopole charge would increase the degree of deformation. At the same time, the distortion could be relieved because of the cosmological constant and the distortion would increase with the distance from the black hole. Besides, the spin parameter, magnetic monopole charge and cosmological constant increase will cause the shadow to shrink. |

The cosmological constant from space-time discreteness

Qi-Qi Fan; Cong Li; Hao-Ran Zhang; Peng-Zhang He,; Jian-Bo DengSubjects: Physics >> The Physics of Elementary Particles and Fields

We regard the background of space-time as a physical system composed of discrete volume elements at the Planck scale and get the internal energy of space-time by Debye model. A temperature-dependent minimum energy limit of the particles is proposed from the thermal motion part of the internal energy. As decreases of the temperature caused by the expansion of the universe, more and more particles would be "released" because of the change of the energy limit, we regard these new particles as a source of dark energy. The minimum energy limit also leads to a corrected number of particles in universe and a modified conservation equation. According to the modified conservation equation, an effective cosmological constant consistent with its observed value is obtained. |

On the description of particle system motion

吴峰Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Based on the concepts of infinitesimal and super real time-space composed of monads, the equations describing the particle flow are proposed. After the initial conditions are given, the state of the particle system at any time can be obtained by solving these equations. The physical properties of the granular matter, such as the moving velocity, the rotation angle, the angular velocity of rotation, the temperature, the pressure, the density, the mass, etc. at any time and space position are obtained. It is also to obtain that the translational motion is not dependent on rotation motion ofthe particles and can be separately analyzed. For a stationary particle system, theconditions that must be met by the force and force moment on the particles in thesystem are given. On this basis, the properties of the granular matter at rest can befurther explored for. |

Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

实验测量表明体心立方固溶体 约在 2.0 at.% Mn发生相变，但这一相变的机制，相变前后铁锰体系的物理性质变化至今仍不清楚。本文通过密度泛函计算，揭示了这一相变是一种同构相变，并阐明了相变机制和相变前后物理性质的变化。 |

Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Regulation of leaf gas exchange plays an important role in the survival of trees and shrubs under future climate change. However, the responses of leaf water potential and gas exchange of shrubs in semi-arid areas to the precipitation alteration are not clear. Here, we conducted a manipulated experiment with three levels of precipitation, i.e., a control with ambient precipitation, 50% above ambient precipitation (irrigation treatment), and 50% below ambient precipitation (drought treatment), with two common shrubs, Salix psammophila C. Wang & C. Y. Yang (isohydric plant, maintaining a constant leaf water potential by stomatal regulation) and Caragana korshinskii Kom. (anisohydric plant, having more variable leaf water potential), on the Chinese Loess Plateau in 2014 and 2015. We measured the seasonal variations of predawn and midday leaf water potential (?pd and ?md), two parameters of gas exchange, i.e., light-saturated assimilation (An) and stomatal conductance (gs), and other foliar and canopy traits. The isohydric S. psammophila had a similar An and a higher gs than the anisohydric C. korshinskii under drought treatment in 2015, inconsistent with the view that photosynthetic capacity of anisohydric plants is higher than isohydric plants under severe drought. The two shrubs differently responded to precipitation manipulation. ?pd, An and gs were higher under irrigation treatment than control for S. psammophila, and these three variables and ?md were significantly higher under irrigation treatment and lower under drought treatment than control for C. korshinskii. Leaf water potential and gas exchange responded to manipulated precipitation more strongly for C. korshinskii than for S. psammophila. However, precipitation manipulation did not alter the sensitivity of leaf gas exchange to vapor-pressure deficit and soil moisture in these two shrubs. Acclimation to long-term changes in soil moisture in these two shrubs was primarily attributed to the changes in leaf or canopy structure rather than leaf gas exchange. These findings will be useful for modeling canopy water-carbon exchange and elucidating the adaptive strategies of these two shrubs to future changes in precipitation. |

submitted time
2020-06-22
From cooperative journals:《Journal of Arid Land》
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