分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-09
摘要: We compute the Casimir energy of the photon field in a static de Sitter space and find it to be proportional to the size of the horizon, the same form of the holographic dark energy. We suggest to make metamaterials to mimic static de Sitter space in laboratory and measure the predicted Casimir energy. Crown
分类: 材料科学 >> 材料科学(综合) 提交时间: 2017-05-09
摘要: The high frequency vibration analysis of a composite laminate plate structure subjected to impact loads was investigated by using method of energy finite element analysis (EFEA). The time and space averaged energy density was used as the primary variable to form the governing differential equations. The multilayer laminate plate is simplified to be equivalent isotropic plate using the average concept, such as the average damping loss factor and the average group speed. The global system of EFEA equations can be solved numerically and the energy density distribution within the whole system can then be obtained. The EFEA numerical results for composite laminate plate structure are validated through comparison with those of very dense conventional finite element analysis (FEA).
分类: 物理学 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: By extending the minimum spanning tree (MST) clusterization algorithm for the binding energy cut, the isospin asymmetry dependence of directed flow for isospin sensitive isobar pairs (neutrons-protons, 3H-3He) is studied from low towards high incident energies. The modified clusterization method (MSTB) has the advantage to identify the fragments at quite early time. It enhances (reduces) the production of free nucleons (fragments) over MST method. The directed flow of isobaric pair 3H-3He is more sensitive towards isospin asymmetry caused by MSTB than isobaric pair n-p. This sensitivity becomes quite strong towards the high incident energy and neutron-rich reaction system. In conclusion, the inclusion of binding energy in clusterization method for the flow studies has been uniquely important for understanding the isospin physics, especially for high density behavior of symmetry energy.
分类: 能源科学 >> 储能技术 提交时间: 2018-11-14
摘要: A compact Janus membrane, which consists of sulfonated polystyrene and quaternized polystyrene, is used as the separator to assemble a novel carbon-based supercapacitor. The aqueous acidic and alkaline electrolyte solutions can be simultaneously used in one supercapacitor device. The carbon-based aqueous supercapacitor can not only run at a high cell voltage of 2.2 V, but also deliver a specific energy of 20.06 Wh kg-1. Moreover, such a supercapacitor with specific energy of 40-50 Wh kg-1 can be predicted after further optimization.
分类: 地球科学 >> 空间物理学 提交时间: 2017-01-22
摘要: By use of the global PPMLR Magnetohydrodynamics(MHD) model, a serial of quasi-steady-state numerical simulations were conducted to examine the modulation property of the interplanetary magnetic field clock angle theta on the solar wind energy input into the magnetosphere. All the simulations can be divided into seven groups according to different criteria of solar wind conditions. For each group, 37 numerical examples are analyzed, with the clock angle varying from 0�to 360�with an interval of 10� keeping the other solar wind parameters(such as the solar wind number density, velocity, and the magnetic field magnitude) unchanged. As expected, the solar wind energy input into the magnetosphere is modulated by the IMF clock angle. The axisymmetrical bell-shaped curve peaks at the clock angle of 180� However, the modulation effect remains invariant with varying other solar wind conditions. The function form of such an invariant modulation is found to be sin(0/2)2.70 + 0.25.
分类: 能源科学 >> 能源(综合) 提交时间: 2024-03-28
摘要: With rapidly increasing consumption of energy, shipping industry has imposed a huge burden on the marine environment. It is a general trend to increase the use of renewable energy on ships to improve the ship sustainability. This article summarized the current development and application of solar energy, wind energy and fuel cell in ship power systems. Furthermore, in order to investigate the advantages of sustainable design for the ships, for the first time, a hybrid PV, wind and fuel cell energy system was established for an oil tanker, and the economic and environmental analyses of the hybrid system were performed. The analysis results demonstrate that the optimal hybrid energy system can reduce 151,467kg emission of CO2 and provide 2.92% electricity for the ship gird per year.
分类: 物理学 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: Isospin-dependent Quantum Molecular Dynamics model (IQMD) has been applied to investigate the Pygmy Dipole Resonance (PDR) and Giant Dipole Resonance (GDR) in Ni isotopes by Coulomb excitation. By Gaussian fitting to the photon emission spectra, the peak energies and strengths of PDR and GDR are extracted. Their sensitivities to impact parameter, incident energy and the symmetry energy are discussed. By the comparison of energy-weighted sum rule (EWSR) with the data and other calculations for 68Ni, the parameters of density-dependence of symmetry energy in the IQMD are constrained. In addition, the N/Z dependence of PDR and GDR parameters of Ni isotopes are investigated, and the results that the EWSR increases linearly with the N/Z are obtained.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 分类: 物理学 >> 地球物理学、天文学和天体物理学 提交时间: 2023-03-25
摘要: In this article, based on the wave equation established in the first part of this series, I have studied the evolution of the energy density of the universe from the initial moment to the present, and found that there is still residual energy of the initial energy of the universe, which appears in the form of vacuum energy. The residual energy is the simplest explanation for dark matter. The calculations show that the present average energy of each momentum mode in the residual energy is of the order of 10^{-3} eV, which is approximately 3 to 5 times the averaged energy of photons in the cosmic microwave background.
分类: 物理学 >> 核物理学 提交时间: 2016-09-13
摘要: The knee phenomenon of the cosmic ray spectrum, which plays an important role in studying the acceleration mechanism of cosmic rays, is still an unsolved mystery. We try to reconcile the knee spectra measured by ARGO-YBJ and Tibet-III. A simple broken power-law model fails to explain the experimental data. Therefore a modified broken power-law model with non-linear acceleration effects is adopted, which can describe the sharp knee structure. This model predicts that heavy elements dominate at the knee.
分类: 物理学 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature, asym/T, for the heavy-ion reactions near the Fermi energy region, based on the modified Fisher Model (MFM). This method is applied to the primary fragments of the Anti-symmetrized Molecular Dynamics (AMD) simulations for the reactions of 40Ca + 40Ca at 35 MeV/nucleon. The density and the temperature at the fragment formation stage are extracted using a self-consistent method.
分类: 物理学 >> 凝聚态:结构、力学和热性能 提交时间: 2017-03-26
摘要: The beam energy is measured in e+e- collision by using Compton Backscattering. The uncertainty of this measurement process is studied by virtue of analytical formulas, and the special effects of variant energy spread and energy drift on the systematic uncertainty estimation are also studied with Monte Carlo sampling technique. These quantitative conclusions are especially important for understanding the uncertainty of beam energy measurement system.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-09
摘要: We investigate the implications of the entropic force formalism proposed by Verlinde. We show that an UV/IR relation proposed by Cohen et al., as well as an uncertainty principle proposed by Hogan can be derived from the entropic force formalism. We show that applying the entropic force formalism to cosmology, there is an additional term in the Friedmann equation, which can be identified as holographic dark energy. We also propose an intuitive picture of holographic screen, which can be thought of as an improvement of Susskind's holographic screen.
分类: 生物学 >> 植物学 >> 植物生态学和植物地理学 提交时间: 2016-05-04
摘要: Switchgrass-derived ethanol has been proposed as an alternative to fossil fuels to improve sustainability of the US energy sector. In this study, life cycle analysis (LCA) was used to estimate the environmental benefits of this fuel. To better define the LCA environmental impacts associated with fertilization rates and farm-landscape topography, results from a controlled experiment were analyzed. Data from switchgrass plots planted in 2008, consistently managed with three nitrogen rates (0, 56, and 112kg N ha1), two landscape positions (shoulder and footslope), and harvested annually (starting in 2009, the year after planting) through 2014 were used as input into the Greenhouse gases, Regulated Emissions and Energy use in transportation (GREET) model. Simulations determined nitrogen (N) rate and landscape impacts on the life cycle energy and emissions from switchgrass ethanol used in a passenger car as ethanolgasoline blends (10% ethanol:E10, 85% ethanol:E85s). Results indicated that E85s may lead to lower fossil fuels use (58 to 77%), greenhouse gas (GHG) emissions (33 to 82%), and particulate matter (PM2.5) emissions (15 to 54%) in comparison with gasoline. However, volatile organic compounds (VOCs) and other criteria pollutants such as nitrogen oxides (NOx), particulate matter (PM10), and sulfur dioxides (SOx) were higher for E85s than those from gasoline. Nitrogen rate above 56kg N ha1 yielded no increased biomass production benefits; but did increase (up to twofold) GHG, VOCs, and criteria pollutants. Lower blend (E10) results were closely similar to those from gasoline. The landscape topography also influenced life cycle impacts. Biomass grown at the footslope of fertilized plots led to higher switchgrass biomass yield, lower GHG, VOCs, and criteria pollutants in comparison with those at the shoulder position. Results also showed that replacing switchgrass before maximum stand life (1020years.) can further reduce the energy and emissions reduction benefits.
分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-29
摘要: The Ultrahard X-ray Multifunctional Application Beamline (BL12SW) is one of the Phase-II Beamline Projects at the Shanghai Synchrotron Radiation Facility. The primary X-ray techniques used at the beamline are high-energy X-ray diffraction and imaging using white and monochromatic light. The main scientific objectives of ultrahard X-ray beamline are focused on two research areas. One is the study of the structural properties of Earth’s interior and new materials under extreme high-temperature and high-pressure conditions, and the other is the characterization of materials and processes in near-real service environments. The beamline utilizes a superconducting wiggler as the light source, with two diamond windows and SiC discs to filter out low-energy light (primarily below 30 keV) and a Cu filter assembly to control the thermal load entering the subsequent optical components. The beamline is equipped with dual monochromators. The first was a meridional bending Laue monochromator cooled by liquid nitrogen, achieving a full-energy coverage of 30–162 keV. The second was a sagittal bending Laue monochromator installed in an external building, providing a focused beam in the horizontal direction with an energy range of 60–120 keV. There were four experimental hutches: two large volume press (LVP) experimental hutches (LVP1 and LVP2) and two engineering material (ENG) experimental hutches (ENG1 and ENG2). Each hutch was equipped with various near-real service conditions to satisfy different requirements. For example, LVP1 and LVP2 were equipped with a 200-ton DDIA press and a 2000-ton dual-mode (DDIA and Kawai) press, respectively. ENG1 and ENG2 provide in-situ tensile, creep, and fatigue tests as well as high-temperature conditions. Since June 2023, the BL12SW has been in trial operation. It is expected to officially open to users by early 2024.
分类: 生物学 >> 植物学 >> 植物生态学和植物地理学 提交时间: 2016-05-04
摘要: Planting the perennial biomass crop Miscanthus in the UK could offset 213Mtoileq.yr1, contributing up to 10% of current energy use. Policymakers need assurance that upscaling Miscanthus production can be performed sustainably without negatively impacting essential food production or the wider environment. This study reviews a large body of Miscanthus relevant literature into concise summary statements. Perennial Miscanthus has energy output/input ratios 10 times higher (47.32.2) than annual crops used for energy (4.70.2 to 5.50.2), and the total carbon cost of energy production (1.12gCO2-Ceq.MJ1) is 2030 times lower than fossil fuels. Planting on former arable land generally increases soil organic carbon (SOC) with Miscanthus sequestering 0.72.2MgC4-Cha1yr1. Cultivation on grassland can cause a disturbance loss of SOC which is likely to be recovered during the lifetime of the crop and is potentially mitigated by fossil fuel offset. N2O emissions can be five times lower under unfertilized Miscanthus than annual crops and up to 100 times lower than intensive pasture. Nitrogen fertilizer is generally unnecessary except in low fertility soils. Herbicide is essential during the establishment years after which natural weed suppression by shading is sufficient. Pesticides are unnecessary. Water-use efficiency is high (e.g. 5.59.2gaerial DM (kgH2O)1, but high biomass productivity means increased water demand compared to cereal crops. The perennial nature and belowground biomass improves soil structure, increases water-holding capacity (up by 100150mm), and reduces run-off and erosion. Overwinter ripening increases landscape structural resources for wildlife. Reduced management intensity promotes earthworm diversity and abundance although poor litter palatability may reduce individual biomass. Chemical leaching into field boundaries is lower than comparable agriculture, improving soil and water habitat quality.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2020-09-06
摘要: 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.
分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2024-02-27
摘要: The energy storage and conversion found in ferroelectrics realize through polar domain and domain wall microstructures resulted in complex polar topologies or within transformations from macro/micro domain to nano domain. The physical models are adopted with basic domains and domain walls including 90o, 180o, 71o and 109o classified into two categories of 180o and α-angle, and are reconstructed with equivalent circuits simplified according to the reported patterns. Although electrical energy is known to be maintained by the balance of charging and loss, the effect of circuits on microstructure has been rarely explored because of the relative paucity of patterns implemented experimentally for domain and domain wall. And here the diagrammatic sketches of vortex pattern and transformation into nano domain are designed and derived into their respective formulas of total capacitance and energy density with crucial structural features. The findings reveal novel mechanisms on energy storage by microstructures that can be used to propose effective creation strategies even in designing modern measure equipment.
分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2024-01-17
摘要: A 20-kiloton liquid scintillator detector is designed in the Jiangmen Underground Neutrino Observatory (JUNO) for multiple physics purposes, including the determination of the neutrino mass ordering through reactor neutrinos, as well as measuring supernova neutrinos, solar neutrinos, and atmosphere neutrinos to explore different physics topics. Efficient reconstruction algorithms are needed to achieve these physics goals in a wide energy range from MeV to GeV. In this paper, we present a novel method for reconstructing the energy of events using hit information from 3-inch photomultiplier tubes (PMTs) and the OCCUPANCY method. Our algorithm exhibits good performance in accurate energy reconstruction, validated with electron Monte Carlo samples spanning kinetic energies from 10~MeV to 1~GeV.
分类: 物理学 >> 核物理学 提交时间: 2023-12-28
摘要: The High Energy Photon Source (HEPS) is the first fourth-generation synchrotron light source building in China. Its injector consists of a Linac and a full energy booster. The booster captures the electron beam from the Linac and further increases its energy to the same as that required by the storage ring. The full-energy beam could be injected to the storage ring directly or after high-energy accumulation. On November 17, 2023, it was demonstrated that key parameters of the booster successfully reached corresponding target values. These milestone results were accomplished based on many contributions, including nearly a decade of physics design, years of development and installation of equipment, as well as months of beam commissioning. As measured at the extraction energy of 6 GeV, the averaged beam current and emittance reached 8.57 mA with 5 bunches and 30.37 nm.rad with a single-bunch charge of 5.58 nC, compared with the corresponding target values of 6.6 mA and 35 nm.rad, respectively. This paper presents the physics design, equipment development and installation, and commissioning process of the HEPS booster.
分类: 物理学 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: The theoretical model and the numerical analyses on the Gibbs-free-energy of the association states of amphiphilic molecules in nanoconfined aqueous solutions are presented in detail. We exhibit the continuous change of the Gibbs-free-energy trend, which plays a critical role in the association states of the system transforming from the dispersion state, through the reversible state, and finally to the aggregation state in amphiphilic molecule solutions. Furthermore, for the reversible state, we present the difference in the free-energy barrier heights of the dispersion state and aggregation state, resulting from the competition between the entropy, which makes the solute molecules evenly disperse in the solution and the energy contribution driving the amphiphilic molecules to aggregate into a larger cluster. These findings provide a comprehensive understanding of confinement effects on the solute association processes in aqueous solutions and may further improve the techniques of material fabrication.