Space-time Evolution Research Articles

Thermodynamics of phase transition in Reissner–Nordström–de Sitter spacetime

The Reissner-Nordstrm̈-de Sitter (RN-dS) spacetime can be considered as a thermodynamic system. Its thermodynamic properties are discussed that the RN-dS spacetime has phase transitions and critical phenomena similar to that of the Van de Waals system or the charged AdS black hole. The continuous phase transition point of RN-dS spacetime depends on the position ratio of the black hole horizon and the cosmological horizon. We discuss the critical phenomenon of the continuous phase transition of RN-dS spacetime according to Landau theory of continuous phase transition, that the critical exponent of spacetime is same as that of the Van de Waals system or the charged AdS black hole, which have universal physical meaning. We find that the order parameters are similar to those introduced in ferromagnetic systems. Our universe is an asymptotically dS spacetime, thermodynamic characteristics of RN-dS spacetime can help us understand the evolution of spacetime and provide a theoretical basis to explore the physical mechanism of accelerated expansion of the universe.

Timing control of impulse self balancing latch opening of expansion wave gun

Aiming at the problem of accurate latch opening control of expansion wave gun automatic gun, the mathematical model of accurate latch opening time is established, the travel curve of projectile and expansion wave, the velocity curve of projectile and expansion wave are studied, and the occurrence time of expansion wave and the time close to projectile are simulated and analyzed; The time-space evolution relationship between expansion wave velocity and local sound velocity, projectile velocity and gas velocity is simulated; The average pressure time curve and chamber resultant force curve of the two launch modes are compared and analyzed. After the projectile moves for 2.7ms, the chamber pressure and chamber resultant force of expansion wave launch are significantly reduced; The dynamic model of inertial latch opening is established; The changes of projectile initial velocity and recoil force under different latch opening times are studied. The test shows that the recoil force and recoil distance are greatly reduced when the projectile initial velocity decreases very weakly, which shows that the simulation calculation of latch opening time is accurate.

Full higher-dimensional analysis of moduli oscillation and radiation in expanding universe

We investigate effects of the radiation and the moduli oscillation around the stabilized values on the evolution of a 6-dimensional spacetime compactified on S2. In order to see the transition from the 5-dimensional space to the 3-dimensional one, we develop a procedure to pursue the spacetime evolution with appropriate approximations, which is valid until the spacetime behaves like 4-dimensional. In the case that the moduli stabilization process cannot be described in the context of the 4-dimensional effective theory, it takes quite a long time for the moduli oscillation to dominate the total energy density, in contrast to the conventional result obtained by the 4-dimensional effective theory approach. We also found that even if the moduli are set at the stabilized values, they start to oscillate due to the pressure in the extra space S2 in some cases.

Study on dust distribution in a highway tunnel during the full-face excavation with Drilling-Blasting method

Dust problem is serious in a highway tunnel during the full-face excavation, particularly after blasting of tunnel face. In order to solve the problem of dust pollution after blasting effectively, this study investigated the space–time evolution law of dust and inhalable particles within 100 s after blasting under blowing ventilation. First, the Euler-Lagrange method is used to simulate the coupled motion of air and dust. Then, the influences of air velocity on the distribution of dust and inhalable particles are considered, and the simulation results are verified by field measured data. The present study indicated that the heavier particles in the dust produced by blasting of tunnel face are deposited at the bottom of wind-return side in front of duct. The inhalable particles which particle size less than or equal to 10 μm are more uniformly dispersed in the whole tunnel space, and the higher the air velocity, the shorter the time required for the process. In addition, by analyzing and fitting the particle moving distance along the length of tunnel, the approximate time required for dust to migrate to a certain location can be predicted. The prediction of space–time evolution law of dust and inhalable particles in this study can provide some guidance for practical engineering cleaner production.

Time-space evolution of Iberian Pyrite Belt igneous activity: Volcanic and plutonic lineaments, geochronology, ore horizons and stratigraphic constraints

The volcanism in the Iberian Pyrite Belt migrated from the present day west/southwest to the east/northeast during Devonian/Carboniferous times. Evidence is here discussed based in U-Pb zircon ages of felsic volcanic and plutonic rocks, bounded by enclosed sediments and their biostratigraphic ages, together with hosted massive sulphides deposits and associated plutonic counterparts.Volcano-Sedimentary Complex rocks define several volcanic axes, or lineaments, with the general NW-SE to WNW-ESE belt trending orientation. The usage of all the available data from high-resolution stratigraphy, geology and geophysics lead to establishment of eleven main volcanic axes, nine with zircon U-Pb radiometric ages (166 samples).In this research, we reinforce a previous inter-axes volcanic evolutionary trend, but we also suggest an intra-axis evolutionary trend of the IPB igneous activity with time. This means the basin igneous activity also evolved along most of the volcanic and plutonic lineaments, from west/northwest to east/southeast.Successive weighted average ages for each axis (SW to NE) and opposite end-point sample ages for each axis (NW/W to SE/E) are presented. Similar trends are found with felsic volcanic rocks, subvolcanic and plutonic rocks and even massive sulphide ages correspond to the regional trend corroborating the proposed geological framework.Siliciclastic sediments and lower VSC sequences (sediments, felsic volcanic rocks and massive sulphides) show a comparable age trending evolution although upper VSC sediments seem to be contemporaneous across the province. Older ages, from zircon U-Pb and from associated reworked palynomorph in the sediments, show a long-lasting age distribution along most Devonian times, suggesting the IPB evolved since Lochkovian times (Lower Devonian). Therefore, we propose the IPB inter-axes evolution could be related with a NE-direction plate motion (present-day location) over a heat source, while intra-axes are probably due to the collisional/compressive tectonic interaction of South Portuguese – Ossa-Morena zones tectonic setting.

Hydrodynamic fluctuations and ultra-central flow puzzle in heavy-ion collisions

One of the long-standing problems in the field of high-energy heavy-ion collisions is that the dynamical models based on viscous hydrodynamics fail to describe the experimental elliptic flow v2 and the triangular flow v3 simultaneously in ultra-central collisions. The problem, known as the ultra-central flow puzzle, is specifically that hydrodynamics-based models predict the flow ratio of the two-particle cumulant method v2{2}/v3{2}>1 while v2{2}/v3{2}∼1 in the experimental data. In this Letter, we focus on the effects of hydrodynamic fluctuations during the space-time evolution of the QGP fluid on the flow observables in the ultra-central collisions. Using the (3+1)-dimensional integrated dynamical model which includes relativistic fluctuating hydrodynamics, we analyze the anisotropic flow coefficients vn{2} in 0–0.2% central Pb+Pb collisions at sNN=2.76TeV. We find that the hydrodynamic fluctuations decrease the model overestimate of v2{2}/v3{2} from the experimental data by about 19% within the present setup of η/s=1/2π. This means that the hydrodynamic fluctuations qualitatively have an effect to improve the situation for the puzzle, but the effect of the hydrodynamic fluctuations alone is quantitatively insufficient to resolve the puzzle. The decrease of the ratio largely depends on the shear viscosity η/s, which calls for future comprehensive analyses with, for example, a realistic temperature-dependent viscosity.

Effects of the QCD critical point on the spectra and flow coefficients of hadrons

The space-time evolution of the hot and dense fireball of quarks and gluons produced in ultrarelativistic heavy-ion collisions at nonzero baryonic chemical potential and temperature has been studied by using relativistic dissipative hydrodynamics. For this purpose, a numerical code has been developed to solve the relativistic viscous causal hydrodynamics in ($3+1$) dimensions with the inclusion of QCD critical point ($CP$) through the equation of state and scaling behavior of transport coefficients. We compute the transverse momentum spectra, directed and elliptic flow coefficients of pions and protons to comprehend the effect of $CP$ on these observables. It is found that the integration over the entire space-time history of the fireball largely obliterates the effects of $CP$ on the spectra and flow coefficients for the event averaged initial conditions considered here.

Process analytical technology as in-process control tool in semi-continuous manufacturing of PLGA/PEG-PLGA microspheres

Nowadays, among 3rd generation drug delivery systems, biodegradable polymeric based long-acting injectable depot has achieved tremendous success in clinical application. So far, there have been two dozen of commercial products of Poly (lactic-co-glycolic acid) microspheres available in the market. Recently, continuous manufacturing concept has been successfully applied on oral solid formulation from buzzword to reality. However, the polymeric injectable microspheres are still stayed at batch manufacturing phase due to the lack of understanding of knowledge matrix. In this study, micro-mixer as a plug-and-play emulsification modules, Raman spectroscopy and focused beam reflectance measurement as real-time monitoring modules are integrated into a novel semi-continuous manufacturing streamline to provides more efficient upscaling flexibility in microspheres production. In this end to end semi-continuous manufacturing process, amphiphilic block polymer monomethoxy-poly (ethylene glycol) modified PLGA (mPEG-PLGA) was used for encapsulating Gallic acid. Additionally, with guarantee of good robustness, the correlation relationship between critical process parameters, critical material attributes and critical quality attributes were investigated. The time-space evolution process and mechanism for formation of PEG-PLGA microsphere with particular morphology were elaborated. Altogether, this study firstly established semi-continuous manufacturing streamline for PLGA/PEG-PLGA microspheres, which would not only lower the cost of production, narrow process variability and smaller equipment/environmental footprint but also applied in-process control (IPC) and QbD principle on complicated production process of microspheres. Therefore, this study build confidence in the industrial development of PLGA/PEG-PLGA microspheres and establish best practice standards, which might be a quantum leap for developing PLGA microspheres in the future.

Time–Space Evolution of the Groningen Gas Field in Terms ofb-Value: Insights and Implications for Seismic Hazard

AbstractThe Groningen gas field, located in the northeast of The Netherlands, is the Europe’s largest onshore gas field. It was discovered in 1959 and production started in 1963: Continuous production leads to reservoir compaction and subsidence, gradually loading preexisting fault and induced seismicity that started about 30 yr into the production. The seismic hazard and risk related to the induced seismicity is determined not only for the rate of activity, but it is also equally influenced by the relative size distribution of the seismicity—the b-value. I reanalyze the spatial and temporal evolution of the b-value in the field using an alternative approach to overcome magnitude in completeness heterogeneity, and link it to the evolution of fault loading and subsidence. Spatial variations of b-values are found to vary between 0.61 and 1.3, with the lowest observed values observed in the location of the 2012 M 3.6 Huizinge earthquake. In the last 10 yr, the mapped b-values are more homogeneous throughout the field. The spatial and temporal evolution of the b-value in the field in this study is shown to be quite complex, and systematically linked it to the evolution of fault loading, absolute compaction, and the rate of compaction—an important finding that offers new insights into hazard reduction and mitigation strategies of extraction relation-induced seismicity. Compaction rates below 2 mm/yr are not correlated to seismicity above M 2.0 in the history of the field, suggesting that low-volume production may be safer than that previously assumed.

Transition from breccia pipe to stratabound mineralization in Mississippi Valley-type hydrothermal systems: The Nayongzhi Zn-Pb deposit, world-class Sichuan−Yunnan−Guizhou triangle, South China

Unraveling the time-space evolution of Mississippi Valley-type (MVT) hydrothermal systems is critically important for understanding ore genesis and exploration. We studied a complete mineral system from conduit-filling to tail-end facies in the world-class Sichuan−Yunnan−Guizhou triangle, South China, via field geology, mineralogy, fluid inclusions, and in situ sulfide S-Pb isotopes to propose an integrated model for the evolution of MVT hydrothermal systems. Geological mapping shows that the mineralization transitions from breccia pipe to stratabound style: high-grade ores occur mainly as open-space infill associated with F12 fault (fluid conduit), while low-grade evaporite-related replacement ores developed distal from the fault. The δ34S value in hydrothermal sulfides shows a wide range (+3.6‰ to +27.9‰), with significant intragrain variation (up to +12.8‰), which suggests a mixture of 34S-rich sulfur produced by thermochemical sulfate reduction of evaporite within the ore host and 32S-rich sedimentary/diagenetic pyrite. In situ sulfide Pb ratios decrease away from the F12 fault, which indicates that metals were sourced from different degrees of mixing between the Proterozoic metamorphic basement and wall rocks. Fluid-inclusion microthermometric data identify two distinct fluids: a hotter (>155 °C), more saline (>18 wt% NaCl equivalent), and metal-rich fluid with a cooler (<90 °C), low-salinity (<4 wt% NaCl equivalent), and reduced sulfur-rich fluid. The mixing of two fluids was responsible for precipitating the high-grade ores near the F12 fault, and the acid-producing (H+) process created new space for stratabound ore distal to the fault. This study highlights that fluid mixing is critical for efficient sulfide accumulation, and the metal zoning pattern provides guidelines for exploration.

Failure mechanism analysis for tunnel construction crossing the water-rich dense fracture zones: A case study

For deep tunnel crossing the fracture zones with water-rich strongly weathered granite, water inrush and collapse disasters occur frequently. Based on a high-risk tunnel under construction, this research tests and analyzes the engineering properties and the spatial distribution characteristics of unfavorable geological structures through the innovative comprehensive unfavorable geological exploration technology composed of UAV with lidar-high power geophysical prospecting technology-TSP advances geological prediction test. Then the space–time evolution law of tunnel vault settlement is analyzed and the exploration results of unfavorable geology is checked out based on the tunnel field test. Then, the fluid–solid coupling numerical calculation model for deep-buried tunnel crossing the densely distributed fracture zones with rich water by three benches seven steps method is established. It is found, under the influence of coupling disturbance of multiple fracture zones, the plastic zone area of the surrounding rock increases sharply, which is 4–5 times of the plastic zone area in the stable tunnel sections. And the pore water pressure in the surrounding rock will fluctuate more significantly when crossing the fracture zone with the larger mileage stake number (the larger the serial number), the pore water in the surrounding rock will flow more rapidly, and high-pressure pore water in the rock mass at the far end is more likely to converges into the tunnel arch foot and the lower part. Compared with other excavation parts, tunnel upper bench and tunnel face will become the main water gushing positions during tunnel construction, which are the best positions for the tunnel directional advance drainage. Advance small conduits grouting shall be carried out at the tunnel vault, and secondary grouting shall be carried out at the tunnel vault, and accurate grouting shall be carried out at the tunnel arch foot and the lower position, which can effectively reduce the occurrence of tunnel disasters such as tunnel collapse, mud inrush and water inrush.

Study on Space–Time Evolution Law and Mechanism of Instability Failure of Deep High-Stress Overburden Rock

In order to explore the fracture law and structural evolution characteristics of overlying strata in deep high-stress mining, according to the geometric characteristics and mechanical causes of overlying strata in different mining stages of the stope, four stages of overlying strata structure model are established and analyzed in turn. According to the characteristics of the overburden load transfer path in the deep high-stress stope, the fracture law and macroscopic mechanical response of overburden are analyzed by MATLAB and PFC2D numerical simulation method. The evolution model of overburden structure and load transfer in ‘four stages and three modes’ of the deep high-stress stope is constructed, and the stage fracture effect of ‘beam, plate and arch’ is put forward. The results show that the overburden rock is a fixed beam structure before the initial weighting. After the initial weighting, it evolves into a plate structure with three sides fixed and one side simply supported. After the periodic weighting, the overburden rock structure further evolves into a plate structure with one side fixed and three sides simply supported. After full mining, the overburden rock forms an arch structure, and the load is transmitted by the beam–plate–arch path. The findings of the study provide an important basis for exploring the nature of overburden transport and load transfer in deep high-stress quarries and strengthening overburden prevention and control.

Indeterminacy in Classical Cosmology with Dark Matter

We describe a case of indeterminacy in general relativity for homogeneous and isotropic cosmologies for a class of dark energy fluids. The cosmologies are parametrized by an equation of state variable, with one instance giving the same solution as Norton’s mechanical dome. Our example goes beyond previously studied cases in that indeterminacy lies in the evolution of spacetime itself: the onset of the Big Bang is indeterminate. We show further that the indeterminacy is resolved if the dynamics is viewed relationally.

Bibliometric Analysis of Forestry Research in Mexico Published by Mexican Journals

There is scarce research assessing the productivity of scientific articles on forestry topics. The objective of this study was to analyze the scientific production on forestry topics that originated in Mexico and were published in Mexican journals from 1996 to 2019 and to identify the causes that determine the impact factor of such publications and the space-time evolution of forestry research in Mexico. In addition, to analyze whether researchers tend to publish in journals published by their affiliation institutions. The study considered 2384 scientific articles from seven journals belonging to category VI of Biotechnology and Agricultural Sciences listed in the Journals Classification System by the National Council of Science and Technology that publishes forestry topics. Bibliometric indicators were generated through text mining and analysis of co-authorship networks. It was found that forestry research in Mexico from 1996 to 2019 presented exponential growth in the number of publications. Forestry scientific production was concentrated in the center of the country. It was dominated by researchers from three of 122 institutions: Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (13.88%), Colegio de Postgraduados (12.50%), and Universidad Autonoma Chapingo (10.44%). The journals with the highest number of publications were: Revista Mexicana de Ciencias Forestales (26.51%), Revista Chapingo Serie Ciencias Forestales y del Ambiente (20.34%), and Madera y Bosques (18.88%). Results show that forestry researchers in Mexico published mostly in journals edited by their affiliation institutions, which restricts constructive criticism of peer review and increases academic endogamy. Also showed the need to generate more forestry research for the southeast of the country on topics such as climate change, carbon capture, forest biometry, and remote perception, which are relevant aspects when we consider that no published research evaluated the development of the forestry sector in Mexico.

Revealing the dynamics of ultrarelativistic non-equilibrium many-electron systems with phase space tomography

The description of physical processes with many-particle systems is a key approach to the modeling of numerous physical systems. For example in storage rings, where ultrarelativistic particles are agglomerated in dense bunches, the modeling and measurement of their phase-space distribution is of paramount importance: at any time the phase-space distribution not only determines the complete space-time evolution but also provides fundamental performance characteristics for storage ring operation. Here, we demonstrate a non-destructive tomographic imaging technique for the 2D longitudinal phase-space distribution of ultrarelativistic electron bunches. For this purpose, we utilize a unique setup, which streams turn-by-turn near-field measurements of bunch profiles at MHz repetition rates. To demonstrate the feasibility of our method, we induce a non-equilibrium state and show that the phase-space distribution microstructuring as well as the phase-space distribution dynamics can be observed in great detail. Our approach offers a pathway to control ultrashort bunches and supports, as one example, the development of compact accelerators with low energy footprints.

Formation, evolution, and enhancement mechanisms of mixed temperature gradient during interfacial solar vapor generation

The solar evaporator, which generates a mixed temperature gradient (MTG) in the process of solar-driven interfacial water evaporation (SIWE), has shown great application potential in clean water production. It is also expected to provide a more comprehensive understanding to shed light on the formation, evolution, and enhancement mechanisms of the MTG. Herein, the space-time evolution of the solar absorber temperature and the evaporation performance in the column solar absorber are studied through a three-dimensional and multi-physical model coupling heat transfer and water transport. The results will demonstrate not only the temperature distribution during the SIWE process but the interface between positive temperature gradient (PTG) and negative temperature gradient (NTG). Moreover, the relationship between evaporation rate and light intensity, bulk water temperature, and environment humidity will be investigated. Importantly, the contributions of solar heating, PTG, NTG, and environment heating to the total evaporation rate will be quantitatively analyzed. Finally, based on the above results, the formation conditions, evolution characteristics, and enhancement mechanisms of MTG will be revealed. This paper will provide theoretical guidance for the successful construction and operation of an MTG evaporator for SIWE acceleration.

Time-Varying Topology Model for Dynamic Routing in LEO Satellite Constellation Networks

With the characteristics of low-latency, seamless coverage and high bandwidth, the Low Earth Orbit (LEO) satellite network has been the promising technology for the sixth-generation mobile communication (6G) networks, especially, the inter-satellite link can improve the flexibility of inter-satellite networking and routing. However, in the existing works, since the impact of link attributes on the satellite topology has not been well investigated, it is difficult to avoid the loss of topology information for the transmission path selection, which may aggravate the unreliability of routing path. In this paper, we propose a novel time-varying topology model for the LEO satellite network, to improve the adaptability of the satellite routing. Firstly, the weighted time-space evolution graph based on the link attributes is established to construct the time-varying topology model of LEO satellite networks. Then, the utility function of the link attributes is modelled and the multi-attribute decision-making is introduced to calculate the weight of each link attribute for the quantification of the link utility. Finally, based on the topology model, the inter-satellite link utility-based dynamic routing algorithm is proposed to improve the adaptability of satellite routing. The simulation results demonstrate that the proposed routing algorithm outperforms the existing routing algorithms in terms of packet drop rate, end-to-end delay and throughput.

Analysis of the Spatial-Temporal Evolution of Urbanization Quality in Zhejiang Province, China

Taking cities in Zhejiang Province of China from 2011 to 2020 as the research object, a multi-dimensional urbanization quality evaluation index system was constructed using the comprehensive analysis method, and the urbanization quality of 11 cities in Zhejiang Province was quantitatively measured using the entropy weight method. The system classification and time-space evolution analysis were carried out using ArcGIS software (Environmental Systems Research Institute, Inc., RedLands, CA, USA) to comprehensively study the evolution characteristics and influencing factors of the urbanization quality of cities in Zhejiang Province. This study provides a reference for local governments to formulate feasible urbanization development strategies and policies to promote the high-quality development of urbanization and for the construction of new urbanization in other provinces and cities.

Low- pT direct-photon production in Au+Au collisions at sNN=39 and 62.4 GeV

The measurement of direct photons from Au+Au collisions at sNN=39 and 62.4 GeV in the transverse-momentum range 0.4<pT<3Gev/c is presented by the PHENIX collaboration at the BNLRelativistic Heavy Ion Collider. A significant direct-photon yield is observed in both collision systems. A universal scaling is observed when the direct-photon pT spectra for different center-of-mass energies and for different centrality selections at sNN=62.4 GeV is scaled with (dNch/dη)α for α=1.21±0.04. This scaling also holds true for direct-photon spectra from Au+Au collisions at sNN=200 GeV measured earlier by PHENIX, as well as the spectra from Pb+Pb at sNN=2760 GeV published by ALICE. The scaling power α seems to be independent of pT, center of mass energy, and collision centrality. The spectra from different collision energies have a similar shape up to pT of 2 Gev/c. The spectra have a local inverse slope Teff increasing with pT of 0.174±0.018Gev/c in the range 0.4<pT<1.3Gev/c and increasing to 0.289±0.024Gev/c for 0.9<pT<2.1Gev/c. The observed similarity of low-pT direct-photon production from sNN=39 to 2760 GeV suggests a common source of direct photons for the different collision energies and event centrality selections, and suggests a comparable space-time evolution of direct-photon emission.9 MoreReceived 24 March 2022Accepted 21 October 2022DOI:https://doi.org/10.1103/PhysRevC.107.024914©2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasPhoton, lepton & quark productionRelativistic heavy-ion collisionsTechniquesHadron collidersNuclear Physics

Study on the Coupling Coordination between Ecological Environment and High-Quality Economic Development in Urban Agglomerations in the Middle Reaches of the Yangtze River

The ecological environment is the basis of high-quality economic development, and the coordinated development of the two is of great significance for promoting regional sustainable development. This study takes 31 cities in the middle reaches of the Yangtze River as samples, constructs an evaluation index system of the ecological environment (EE) and high-quality economic development (HQED), and uses a comprehensive evaluation method and a coupling coordination degree model to determine the development level, coupling coordination relationship, interaction coordination relationship and space-time evolution characteristics of the two. The results show that: (1) In the sample period, the overall level of EE and HQED increased simultaneously, but the two indexes of each city showed obvious heterogeneity. (2) EE and HQED have a coupling coordination relationship; the coupling degree (CD) is in a high coupling stage, and the coupling coordination degree (CCD) is in a good and moderate coordination state. (3) In the interactive coordination relationship, the CCD sequence of subsystems is coordinated development > shared development > innovative development > open development, and pressure subsystem > response subsystem > status subsystem. This study provides a new evaluation perspective for EE and HQED and puts forward suggestions for their coupling and coordinated development.