Physical Evolution Research Articles

Physical, chemical and morphological evolution of incipient soot obtained from molecular dynamics simulation of acetylene pyrolysis

Incipient soot particles obtained from a series of reactive molecular dynamics simulations were studied to understand the evolution of physical, chemical, and morphological properties of incipient soot. Reactive molecular dynamics simulations of acetylene pyrolysis were performed using ReaxFF potential at 1350, 1500, 1650, and 1800 K. A total of 3324 incipient soot particles were extracted from the simulations at various stages of development. Features such as the number of carbon and hydrogen atoms, number of ring structures, mass, C/H ratio, radius of gyration, surface area, volume, atomic fractal dimension, and density were calculated for each particle. The calculated values of density and C/H ratio matched well with experimental values reported in the literature. Based on the calculated features, the particles were classified in two types: type 1 and type 2 particles. It was found that type 1 particles show significant morphological evolution while type 2 particles undergo chemical restructuring without any significant morphological change. The particle volume was found to be well-correlated with the number of carbon atoms in both type 1 and type 2 particles, whereas surface area was found to be correlated with the number of carbon atoms only for type 1 particles. A correlation matrix comparing the level of correlation between any two features for both type 1 and type 2 particles was created. Finally, based on the calculated statistics, a set of correlations among various physical and morphological parameters of incipient soot was proposed.

Analysis of the Influence of Analytical Mechanics Concept on the Development of Modern Physics

Physics has undergone development over time, one of which is through modern physics that studies the behavior of matter and energy at the atomic and subatomic particle scale using the concept of analytical mechanics to explain phenomena on a microscopic scale. The purpose of this article is to investigate the influence of analytical mechanics on the advancement of modern physics using a qualitative literature review approach. The literature review involved gathering information related to the study of mechanics and modern physics. The analysis results indicate that analytical mechanics such as Lagrangian and Hamiltonian have influenced the progress of modern physics significantly. This analytical mechanics has made a substantial contribution to modern physics by providing strong theoretical concepts, aiding theoretical research, enabling the analysis of complex physical phenomena, and offering practical applications across various scientific fields. The conclusion drawn from this analysis is the significant theoretical impact of analytical mechanics on the development of modern physics.

Physical field regulation of magnesium alloy wheel formed by backward extrusion process with multi-stage variable speed

To reduce the tonnage required during the forming process of magnesium (Mg) alloy wheels by backward extrusion (BE) and refine the grains at the wheel bottom, the multi-stage variable (MSV) speed process is proposed based on the characteristics of Mg alloy wheels formed by BE. A numerical model for the BE process of Mg alloy wheels using the Defrom-3D was constructed, and the effects of constant speed and MSV speed processes on the physical fields and DRXed grain size evolution during the forming of Mg alloy wheels were investigated. Lastly, the simulation results were indirectly verified by industrial trial production. The results show that constant speed extrusion has a small effect on the effective stress, but a large effect on the wheel temperature distribution, where the forming speed of the upper rim plays a decisive role in the final temperature distribution of the wheel. MSV speed process is used to regulate the physical field evolution during wheel forming based on the effect of constant speed on the physical field of the wheel. With the high-speed forming of the rim and low-speed forming of the upper wheel rim (9-9-1 mm/s), the temperature and effective stress distribution of the wheel blank are reasonable while reducing the forming tonnage and refining the grains at the wheel bottom.

Urban Geomorphology Methods and Applications as a Guideline for Understanding the City Environment

Cities all over the world have developed on different geological-geomorphological substrates. Different kinds of human activities have operated for millennia as geomorphic agents, generating numerous and various erosion landforms and huge anthropogenic deposits. Considering the increasing demand for land and the expansion of the built-up areas involving and disturbing any kind of natural system inside and surrounding the actual urban areas, it is not negligible how important the dynamics of the urban environment and its physical evolution are. In this context, this manuscript addresses insights into eight case studies of urban geomorphological analyses of cities in Italy, Greece, and Brazil. The studies are based on surveying and mapping geomorphological processes and landforms in urban areas, supporting both geo-hazard assessment, historical evolution, and paleomorphologies, as well as disseminating knowledge of urban geoheritage and educating about the anthropogenic impact on urban sustainability. We hypothesize that urban geomorphological analysis of several case studies addresses the physical environment of modern cities in a multi-temporal, multidisciplinary, and critical way concerning global changes. Thus, this study aims to illustrate and propose a novel approach to urban geomorphological investigation as a model for the understanding and planning of the physical urban environment on a European and global scale.

ANALISIS TREND PENELITIAN PENGEMBANGAN PADA PEMBELAJARAN FISIKA DI INDONESIA

The purpose of this research is to map the trends in physics education development research in Indonesia. The research method used in this study is qualitative descriptive research. The data collection technique used in this research is documentation. The data analysis technique used is qualitative descriptive in the form of data reduction, data display, and conclusion drawing. The results of the research show that there are 689 article titles on development research in the field of Physics. The current trend in development research is the development of electronic-based media and assessment instruments, using both PCs and Android applications. The most widely used development research models are 4D, ADDIE, and Brog & Gall. Development research has also focused on high-level thinking skills, as evidenced by the appearance of keywords related to critical thinking in physics development research. Future development research can focus on the use of technology, such as Augmented Reality, Virtual Reality, Android applications, and the use of AI.

Past and future of the Arctic sea ice in High-Resolution Model Intercomparison Project (HighResMIP) climate models

Abstract. We examine the past and projected changes in Arctic sea ice properties in six climate models participating in the High-Resolution Model Intercomparison Project (HighResMIP) in the Coupled Model Intercomparison Project Phase 6 (CMIP6). Within HighResMIP, each of the experiments is run using a reference resolution configuration (consistent with typical CMIP6 runs) and using higher-resolution configurations. The role of horizontal grid resolution in both the atmosphere model component and the ocean model component in reproducing past and future changes in the Arctic sea ice cover is analysed. Model outputs from the coupled historical (hist-1950) and future (highres-future) runs are used to describe the multi-model, multi-resolution representation of the Arctic sea ice and to evaluate the systematic differences (if any) that resolution enhancement causes. Our results indicate that there is not a strong relationship between the representation of sea ice cover and the ocean/atmosphere grids; the impact of horizontal resolution depends rather on the sea ice characteristic examined and the model used. However, the refinement of the ocean grid has a more prominent effect compared to the refinement of the atmospheric one, with eddy-permitting ocean configurations generally providing more realistic representations of sea ice area and sea ice edges. All models project substantial sea ice shrinking: the Arctic loses nearly 95 % of sea ice volume from 1950 to 2050. The model selection based on historical performance potentially improves the accuracy of the model projections and predicts that the Arctic will turn ice-free as early as 2047. Along with the overall sea ice loss, changes in the spatial structure of the total sea ice and its partition in ice classes are noticed: the marginal ice zone (MIZ) will dominate the ice cover by 2050, suggesting a shift to a new sea ice regime much closer to the current Antarctic sea ice conditions. The MIZ-dominated Arctic might drive development and modification of model physics and parameterizations in the new generation of general circulation models (GCMs).

The primary abundance of chondrules in CI chondrites

CI chondrites are the most significant extra-terrestrial samples for estimating the composition of primordial materials in the Solar System. However, CIs lose many primary features because of heavy parent body aqueous alteration. However, CI and CI-related Ryugu particles contain small amounts of relict anhydrous minerals, indicating primary occurrences of chondrules and refractory inclusions. In this study, we estimated the primordial abundance of chondrules in CIs from calculations of the bulk major element compositions. The constraints for the calculation were as follows: 1) CI chondrites primarily comprised chondrules, refractory inclusions, opaque minerals, and a matrix similar to other carbonaceous (C) chondrites. 2) The chemical compositions of these components were similar to those of the unaltered C chondrites. 3) The primary matrix composition of the CI was close to the mean bulk composition. 4) The alteration occurred isochemically. We used the mean major elemental compositions of chondrules and refractory inclusions in an almost unaltered chondrite, Y-81020, CO3.05. Our results were within the range of previously reported CI bulk chemical compositions in the case where chondrule abundances are ≲10 wt%. We also calculated the bulk chemical composition of Tagish Lake, ungrouped C2, which primarily contained ≲20 wt% chondrules. The CI chondrites and Tagish Lake were formed in the outer Solar System. The low primary abundance of chondrules in CIs is closely related to the formation conditions of chondrules in such regions. We suggest that dust with abundant ice and minor chondrules accreted onto the parent bodies of the CI and Tagish Lake in the outer Solar System. Primordial chondrule abundance is the key to clarifying the physical and chemical conditions and evolution of the early Solar System.

Topologically influenced terahertz emission in Co2MnGa with a large anomalous Hall effect

The terahertz (THz) spectral zone is one of the most exciting but least explored domains of the electromagnetic spectrum. To extend the applicability of THz waves, the present objective is to develop an efficient, compact, durable, and low-cost THz emitter source. A spintronic THz emitter consisting of a ferromagnetic/nonmagnetic bilayer heterostructure is a promising innovation that can provide an alternative solution/replacement for conventional THz emitters. To further develop these spin-based THz emitters, we demonstrate an efficient and strong THz emission from a single layer of Co2MnGa with a large anomalous Hall effect (AHE) influenced by its Weyl semimetallic nature. Strong correlations among the THz emission, AHE, and chemical ordering of the full Heusler crystal structures for Co2MnGa are shown. Based on proper structural and chemical design, the topological nature of this material facilitates systematic optimization. Our initial findings provide a new design concept for the topological influences on spin-based THz emitters, and these emitters are expected to facilitate the further development of the intriguing Weyl physics.

Multi-scale analysis of the chemical and physical pollution evolution process from pre-co-pollution day to PM2.5 and O3 co-pollution day

PM2.5 and O3 are two of the main air pollutants that have adverse impacts on climate and human health. The evolution process of PM2.5 and O3 co-pollution are of concern because of the increased frequency of PM2.5 and O3 co-pollution days. Here, we examined the chemical coupling and revealed the driving factors of the PM2.5 and O3 co-pollution evolution process from cleaning day, PM2.5 pollution day, or O3 pollution day, applied by theoretical analysis and model calculation methods. The results demonstrate that PM2.5 and O3 co-pollution day frequently occurred with high concentrations of gaseous precursors and higher sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR), which we attribute to the enhancement of atmospheric oxidation capacity (AOC). The AOC is positively correlated with O3 and weakly correlated with PM2.5. In addition, we found that the correlation coefficients of PM2.5-NO2 (0.62) were higher than that of PM2.5-SO2 (0.32), highlighting the priority of NOx controlling to mitigate PM2.5 pollution. Overall, our discovery can provide scientific evidence to design feasible solutions for the controlling PM2.5 and O3 co-pollution process.

Co-evolution of early Earth environments and microbial life.

Two records of Earth history capture the evolution of life and its co-evolving ecosystems with interpretable fidelity: the geobiological and geochemical traces preserved in rocks and the evolutionary histories captured within genomes. The earliest vestiges of life are recognized mostly in isotopic fingerprints of specific microbial metabolisms, whereas fossils and organic biomarkers become important later. Molecular biology provides lineages that can be overlayed on geologic and geochemical records of evolving life. All these data lie within a framework of biospheric evolution that is primarily characterized by the transition from an oxygen-poor to an oxygen-rich world. In this Review, we explore the history of microbial life on Earth and the degree to which it shaped, and was shaped by, fundamental transitions in the chemical properties of the oceans, continents and atmosphere. We examine the diversity and evolution of early metabolic processes, their couplings with biogeochemical cycles and their links to the oxygenation of the early biosphere. We discuss the distinction between the beginnings of metabolisms and their subsequent proliferation and their capacity to shape surface environments on a planetary scale. The evolution of microbial life and its ecological impacts directly mirror the Earth's chemical and physical evolution through cause-and-effect relationships.

Temperature response and chemical reactions of energetic materials under thermal radiation and heat conduction

Thermal radiation from a high-temperature source is the primary cause of energetic material explosions. However, current research cannot meet the need to prevent thermal radiation-caused explosions. This paper proposes a novel numerical calculation model for temperature response and the chemical reaction of energetic materials under thermal radiation based on the physical mechanisms and evolution of the thermal effect during the chain explosion accident. This model is essential for rapidly evaluating the effect of thermal radiation in chain explosion accidents. The numerical model in this study efficiently obtained the thermal response of energetic materials under thermal radiation, as well as the critical conditions for energetic material explosion under thermal radiation. The results reveal that heat conduction is difficult to cause the explosion of ammonium nitrate, but thermal radiation can. The critical temperature of explosion for ammonium nitrate is 1668 K, the critical duration is 15.93 s, and the critical distance is 7.85 m. The temperature, duration, and radiation distance of the heat source are crucial factors that induce the ammonium nitrate explosion. Firefighters must cover and protect ammonium nitrate within 7200 s and 15.93 s, respectively, when the external heat flow absorbed by the material is 2.688 kW/m2 and 28 kW/m2. The model proposed in this paper can predict the effect of thermal radiation once the heat source parameters are known. Besides, combined with machine learning, the model can also predict the heat source parameters once the parameters of the thermal radiation effect are known. Compared with the current numerical models to evaluate the effect of thermal radiation, the numerical model presented in this paper can evaluate the effect of thermal radiation in engineering more efficiently and has broad application prospects.

Kinetics of pyrolysis and Computational Fluid Dynamics modeling of low metamorphic coal

AbstractThis study explores the low‐temperature pyrolysis kinetic of low metamorphic grade coal from Northern Shaanxi, utilizing Fourier transform infrared (FT‐IR) spectroscopy to analyze the characteristics of various functional groups over a 293–1023 K temperature range. A kinetic model, correlating with the pyrolysis behaviors of these groups, was developed through thermal analysis kinetics. Computational fluid dynamics (CFD) technology simulated the furnace's flow dynamics, allowing an examination of the physical field alterations and functional group evolution during pyrolysis. Results showed that the pyrolysis kinetic functions for aromatic C–H, C=C, C–O, and •OH, along with temperature, pressure, and velocity fields, were successfully integrated into the simulation. This integration provided detailed insights into the temperature profile, pressure distribution, flow velocities, and functional group distribution in the furnace. Aliphatics, exhibiting the largest mass fraction and wide pyrolysis temperature range, and •OH radicals with the highest activation energy were concentrated in the furnace's pyrolysis zone center. C=C's distribution was influenced by aromatic C–H and aliphatics, showing a complementary pattern. The oxygen‐containing groups C–O and C=O had similar pyrolysis mechanisms and uniform distribution. The functional groups' mass fractions were ranked from highest to lowest as follows: aliphatics > •OH > aromatic C–H > C–O > C=C > C=O.

An approach to the effects of stellar rotation on the theoretical apsidal motion constants. Calculations from 0.40 M_sol to 25.0 M_sol

The most reliable sources for determining absolute stellar parameters are the double-lined eclipsing binary systems. Some of these systems also show apsidal motion, characterized by the variable log k$_2$. This point grants us the possibility of investigating the stellar interior, specifically the degree of stellar mass concentration. The first studies carried out about four decades ago on this topic showed appreciable discrepancies not only with respect to the comparison between the observed absolute dimensions and their theoretical counterparts, but mainly concerning the degree of mass concentration through the analysis of their apsidal motions. Fortunately, this scenario has been gradually improving with the advances in the quality of observational techniques and advances in the input physics of the evolutionary stellar models (e.g. opacities, thermonuclear reactions, equations of state, numerical techniques). These new developments in the input physics has improved the comparison between observations and the values predicted by theory, including the apsidal motion rates. This progress has lead us to investigate second-order effects such as rotation and dynamic tides. In this paper we deal with the effects of rotation on the degree of mass concentration. The stellar models were calculated using the MESA package. The mass range studied here was 0.40 to 25.0 M$_ odot $ for a generic chemical composition characterized by X = 0.70 and Z = 0.02. The present models were computed without taking into account core overshooting in order to highlight the effects of rotation. Each model was followed from the pre-main sequence until the central hydrogen content is of the order of or less than 0.03, covering the range of masses and evolutionary status of the double-lined eclipsing binaries showing apsidal motion. Regarding the calculation of the internal structure coefficients bf we integrated the Radau equation using the fifth-order Runge-Kutta method and a tolerance level of 10$^ $. As an auxiliary tool, homology transformations have been used to explain, qualitatively, how the equation of state, thermonuclear reactions, and convection impact the degree of mass concentration of the models. In our past studies on the effects of rotation on log k$_2$ an average correction was used for all models together. For this a small range of masses (2.0, 7.0, 15.0 M$_ odot $) has been used. In the present paper the corrections due to the effects of rotation in log k$_2$ are presented for each mass individually and for three evolutionary phases. This point is particularly important bf given that these corrections show a clear dependence on the mass and on the evolutionary status. Such corrections can be easily introduced into the theoretical calculation of apsidal motion rates through a linear equation. A typical correction due to the rotation effects is of the order of -0.03 in log k$_2$.

Physical and mechanical characteristics deterioration and crack evolution of sandy mudstone in an open-pit mine under multiple freeze–thaw cycles

In open-pit mines located in cold regions north of the 38°N latitude, there are significant freeze–thaw phenomena in slope rocks. This study conducted freeze–thaw cycle tests, considering the number of freeze–thaw cycles and the freezing temperature, on sandy mudstone commonly found in the slopes of open-pit mines. The investigation focused on the effects of freeze–thaw cycles on the physical and mechanical properties and acoustic emission (AE) characteristics of sandy mudstone. The results show that, with an increase in the number of freeze–thaw cycles and a decrease in freezing temperature, the sandy mudstone specimens exhibit nonlinear exponential changes in mass loss rate, P-wave velocity loss rate, peak strain, uniaxial compressive strength (UCS) and elastic modulus, and the amplitude of these changes gradually decreases. The stress–strain curves of specimens shift gradually from apparently brittle to plastic. Simultaneously, the microstructure changes from dense to loose, the micro surface transitions from flat to rough, and cracks and pore defects gradually develop. The peak AE ringing counts, cumulative AE ringing counts, crack initiation stress, and crack damage stress of the specimens all decrease with an increase in the number of freeze–thaw cycles and a decrease in freezing temperature. This suggests a shift from brittle failure to ductile failure. However, the ratio of crack initiation stress and crack damage stress to peak stress does not vary significantly with the number of freeze–thaw cycles and freezing temperature.

Study on the productivity and mechanism of physical field evolution of enhanced geothermal systems under different working fluid types and properties

The injected working fluid conditions directly affect the heat generation efficiency of a stimulated hot dry rock reservoir. Taking exploration well GR1 in the Gonghe Basin of Qinghai as the research object, a stochastic discrete fracture reservoir model was established around the main injection channel, and the productivity variation pattern of the enhanced geothermal system (EGS) and the spatiotemporal evolution mechanism of the reservoir fields were analyzed for CO2 and H2O working fluids. The interaction mechanism between the upper and lower rock formations and the reservoir during the heat mining process was discussed. This study obtained the following findings: (1) when the working fluid was CO2, after 20 years of heat recovery, the injection flow rate, output flow rate, and heat generation efficiency with a working fluid temperature of 60 °C reached 1.22 times, 1.18 times, and 1.92 times those with a working fluid temperature of 35 °C, respectively. The average subsidence and average geostress with the working fluid temperature of 60 °C were low, at only 90.61% and 95.96% of those with the working fluid temperature of 35 °C, respectively. However, high-temperature fluid injection increased flow loss. The changes in the various laws of H2O-EGS were similar to those of CO2-EGS. (2) When the working fluid temperature was 35 °C, after 20 years of heat recovery, the output flow rate and heat generation efficiency with the CO2-EGS reached 12.66 times and 1.28 times those with the H2O-EGS, respectively. However, the flow loss, average subsidence, and average geostress were higher with the CO2-EGS, reaching 6.58 times, 1.14 times, and 1.06 times those with the H2O-EGS, respectively. The patterns in these parameters observed at the other temperatures were similar to those observed at 35 °C. (3) The temperature decrease of the cushion layer was higher than that of the caprock, while the subsidence of the caprock was higher, and this phenomenon was more obvious when the working fluid temperature was lower. The conclusions obtained have important reference significance for the rational selection of working fluids.

Analysis of Learning Media Needs for Physics of Motion Course Based on Android Platform

Teaching and learning activities in the post-pandemic educational environment are already underway in both schools and universities. However, there are also those who still apply a hybrid learning system, one of which is the learning system at Indraprasta PGRI University which still applies a hybrid learning system, namely the physics of motion course. Utilizing Android-based learning media can enjoy learning experiences, facilitating access to various educational resources. It is important to know the needs of students and educators in the process of learning physics of motion to improve the quality of learning, namely by conducting a needs analysis. The aim of this research is to determine the importance of the need for Android-based motion physics learning media. The method used in the research is exploratory descriptive research. From the results of observations and interviews conducted with several motion physics lecturers and observing learning activities in class, the methods used in learning still use classical methods. Learning the physics of motion using Matlab requires a video guide so that it is easy for students to understand. From the results of filling out the questionnaire via a questionnaire, it can be concluded that the results of the analysis of students' needs for Android learning media in the physics of motion course showed that 88.31% answered that they agreed with the development of an Android-based motion physics learning application. So it can be concluded that the development of Android-based motion physics learning media is needed by Informatics Engineering students at Indraprasta PGRI University.

Thermal annealing gradient tailoring on ammonium nitrate-capped CdS nanospheres synthesized via green precipitation

This study explores the impact of thermal annealing gradients on the physical properties and structural evolution of cadmium sulphide (CdS) nanospheres capped with ammonium nitrate as a modifier, which were fabricated through precipitation and subsequent annealing within 160–480 °C temperature range. The properties were characterized using X-ray diffraction (XRD), ultraviolet–visible (UV–Vis), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques The XRD results show that the present CdS exhibits superior crystallinity compared to pure CdS without capping, transitions from a cubic to a hexagonal phase structure, and increases in crystallite size and crystallinity with increasing temperature. The FTIR spectra postulate that a vibrational band presence evidences ammonium nitrate capping on CdS, with another distinct band that represents CdS in the lower wavenumber region, both intensifying at elevated temperatures. The UV–Vis analysis reveals that CdS exhibits strong ultraviolet (UV) absorption suitable for effective photoreaction under UV light and has a broader band gap compared to bulk CdS. SEM images show an extensive distribution of homogeneous nanospheres over the surface, with increased growth in size when capped with ammonium nitrate and at higher temperatures. As validated by TGA and DSC results, CdS with a smaller crystallite size improves thermal stability and energy transfer, as evidenced by reduced weight loss and a lower endothermic temperature, respectively. Varying the annealing temperature with ammonium nitrate capping can improve the structural and physical properties of CdS, which are beneficial for varied applications such as optoelectronics, energy storage, and photocatalysts.

Temperature and magnetic field dependences of transport properties of Bi2(Te1-xSex)3 thin films

V2VI3-based materials are the best materials for thermoelectric cooling devices. Interest in studying the transport properties of V2VI3 thin films has increased after it was found that V2VI3 belong to the class of topological insulators. In this work, the dependences of electrical conductivity, Hall coefficient, charge carrier mobility on magnetic field and temperature of Bi2(Te0.9Se0.1)3 films with thicknesses 48 and 130 nm were measured and interpreted. The transport properties in the thin-film and bulk states were compared. The boundaries between weak and strong magnetic fields were determined. The obtained results are important for solid-state physics development and practical applications.

Two Ubiquitous Radiative States Observed across the High Latitudes

Abstract Previous studies have shown the Arctic exhibits two preferred radiative states, one that is regarded as “radiatively opaque” and the other as “radiatively clear”; this presents as bimodality in the surface longwave flux distributions. How frequently these two states occur and what causes them to persist has significant implications for the polar climate. Furthermore, in the presence of multimodality, evaluating models based solely on their ability to resolve the mean and variance of a distribution can lead to a poor representation of the physical evolution of our climate. This study takes a holistic view of this bimodal behavior, seeking to understand to what degree the high latitudes of both hemispheres reside in distinct radiative states. Even when separated into climatologically distinct subregions, many polar regions exhibit bimodality in their longwave flux distributions not observed at lower latitudes, suggesting that the existence of these two states is both common in and unique to polar regions. Bimodality arises due to a tendency for the atmosphere to alternate between transmissive or opaque clouds, with surface longwave radiative effects of approximately 0 and 75 W m−2 (relative to clear-sky values), respectively. Clouds need not contain liquid to lead to the opaque state, as is typically assumed. The presence of solely ice clouds can cause bimodality to arise in downwelling longwave flux distributions. While some regions do not explicitly exhibit multimodal surface longwave radiation distributions, it is found that similar cloud states exist but in disproportionate frequencies. Significance Statement Radiation plays an important role in shaping the Arctic and Antarctic climates. Several Arctic expeditions have found that certain regions flip between having a very large energy deficit (“transmissive”) to relatively small energy deficit (“opaque”). The former allows for surface cooling and promotes the formation of ice, while the latter hinders such behavior. This study utilizes satellite observations to understand if this behavior is consistent across the Arctic and Antarctic. Understanding the frequencies of these two states is increasingly important within the context of our rapidly changing climate, and by uncovering the fundamental processes which lead to them, we may be able to model how they will change in the future.

Tokyo as an Olympic city across modern history: planning culture as the intangible heritage from a century of hosting the Olympic and Paralympic Games

ABSTRACT Chosen three times as the host city for the Summer Olympic Games (1940, 1964 and 2020), Tokyo's city layout is historically linked to the Olympics. Including the bid project for the 1960 and the 2016 Games, Tokyo has presented five Olympic projects, each time with five different urban visions which enlighten the nature of the past and present political Japanese regimes. The recurrence of the Olympic Games in the planning and growth of Tokyo leads to the idea of a major influence of the Olympics both on the physical evolution of the urban structure but also on that, immaterial, of its planning culture – or, in other words, on the representations, imaginary and practices of the institutional stakeholders of Tokyo's urban fabric. The aim of the paper is therefore double. First, it analyses each urban vision of the Games of 1940, 1964 and 2020. Secondly, it analyses the influence of each Olympic project on greater Tokyo's urban planning and regional development, as well as the influence of each Olympiad on the following ones. Doing that, the paper discusses the formalization of a planning culture through organizing the Olympics on the long run in Tokyo.