Unified Relationship Research Articles

BGFlow: Brightness-guided normalizing flow for low-light image enhancement

Low-light image enhancement poses significant challenges due to its ill-posed nature. Recently, deep learning-based methods have attempted to establish a unified mapping relationship between normal-light images and their low-light versions but frequently struggle to capture the intricate variations in brightness conditions. As a result, these methods often suffer from overexposure, underexposure, amplified noise, and distorted colors. To tackle these issues, we propose a brightness-guided normalizing flow framework, dubbed BGFlow, for low-light image enhancement. Specifically, we recognize that low-frequency sub-bands in the wavelet domain carry significant brightness information. To effectively capture the intricate variations in brightness within an image, we design a transformer-based multi-scale wavelet-domain encoder to extract brightness information from the multi-scale features of the low-frequency sub-bands. The extracted brightness feature maps, at different scales, are then injected into the brightness-guided affine coupling layer to guide the training of the conditional normalizing flow module. Extensive experimental evaluations demonstrate the superiority of BGFlow over existing deep learning-based approaches in both qualitative and quantitative assessments. Moreover, we also showcase the exceptional performance of BGFlow on the underwater image enhancement task.

Breaking down barriers: creating a community of learning development at the University of St Andrews

This presentation outlined a collaboration that delivered an integrated in-sessional academic and learning development provision for students at the University of St Andrews. Staff from the student learning development team in the Centre for Educational Enhancement and Development, and the Academic English Service, situated in the International Education Institute, partnered to bring previously segregated provisions together for academic year 2023/24. Historically both units have provided separate in-sessional one-to-one tutorials dictated by students’ first language or stage of study, but with overlap in some skills areas such as writing development. Each service had different parameters in terms of who could access the tutorials and how often they could do so. Due to the restrictions of each provision, and the siloed nature of the services, we identified that students were often not accessing the most appropriate form of tutorial, and that some tutorials were not being used to best effect. The provision has been reimagined to proffer a new Academic Development Community with the aim of creating a more effective and inclusive resource. This presentation unpicks motivations for pursuing a unified service and reflects on the changes made. The session shared the results of qualitative and quantitative student feedback on the newly aligned provision, and the perceptions of focus group participants on the unified service and relationship with contributing units. Combining the feedback collected thus far with our own professional reflections we explored the outcomes of these changes, as well as the challenges encountered in our collaborative approach. We concluded by sharing the future directions of this collaboration.

Minimum velocity for impact ejecta to form secondaries on terrestrial bodies

The minimum velocity (v) for impact ejecta to form secondary craters (secondaries) remains enigmatic, but it is a crucial parameter in untangling the fate of impact ejecta on planetary surfaces. By cataloging the distances (L) of the nearest secondaries from centers of various-sized (D) primary craters (primaries) on the Moon, Mars and Mercury, we find that v can be as small as ~25 m/s, and an unified power-law relationship of L = 1.86D0.93 (both in meters) works for both simple and complex craters, regardless of different surface gravity and target properties. This relationship also successfully predicts occurrences of secondaries formed by craters on Venus. The constraint on v explains the common concurrences of structural disturbances in crater walls and continuous ejecta deposits caused by landing of cogenetic ejecta, suggesting that ejecta forming self-secondaries do not need near-vertical ejection angles and tertiary craters should be abundant on terrestrial bodies.

Study on the permeability and capillary pressure of spiral woven mesh for flat-plate heat pipes

Due to its excellent capillary characteristics, spiral woven mesh is widely used as the wick structure in ultra-thin flat-plate heat pipes. The performance of these heat pipes surpasses that of conventional ones using sintered powder or multi-layer mesh structures. However, precise quantitative studies on the permeability and capillary pressure characteristics of this unique porous structure are lacking. In this work, we systematically investigated its permeability and capillary pressure, as well as their relationship with the structure. Based on experimental results, we demonstrated that numerical simulation of periodic microelements and subsequent area weighting can accurately predict the permeability of actual structures. Additionally, a parametric study was conducted, yielding a unified empirical relationship between permeability and the structural parameters. In the part of capillary pressure, U-shape tube gravity method was utilized and the relationship between capillary pressure and structure was also disclosed. This study will provide reliable data and theoretical guidance for calculating the capillary limit in heat pipes using spiral woven mesh as the wick.

Unified closure relationship for slug liquid holdup

AbstractSlug flow is a common flow pattern in pipes operating with gas–liquid mixtures. The slug flow's periodic behaviour affects the performance of multiphase transportation systems, which is generally predicted using mechanistic models. Mechanistic models are based on one‐dimensional mass and momentum conservation equations and require additional relationships to define a complete system of equations. These additional equations are usually called closure relationships. The slug liquid holdup () is one of the required closure relationships. In this paper a unified closure model for is proposed considering the energy balance and the interaction between inertial, gravitational, viscous, and surface tension forces. The model parameters' behaviour is described as a function of a new dimensionless number. The experimental data analysis shows that this number can quantitatively define two flow categories: ‘low viscosity flow’ and ‘medium/high viscosity flow’. Slug liquid holdup changes its behaviour in these regions due to the predominance of inertial–surface tension forces or gravitational–viscous forces, respectively. The proposed closure performs better than the existing mechanistic and empirical models.

A unified thermo-mechanical bounding surface model for saturated clay and sand

To accurately predict soil thermal effects is of great importance for simulations of complex boundary value problems such as the energy foundations and nuclear waste disposal. Existing thermo-mechanical constitutive models only account for clay, and cannot simulate the sand’s behaviour under thermo-mechanical conditions. In this study, a unified thermo-mechanical bounding surface (UTMBS) model is proposed for saturated clay and sand. Based on the thermal effects on the isotropic compression line, the model proposes a new unified thermal softening relationship and a plastic modulus for clay and sand, with the thermal cyclic behaviour replicated by a memory surface. The unified model considers the thermal effects on the critical state line and the shape of the bounding surface, accounting for both drained and undrained shearing of clay and sand at different temperatures. In addition, the non-linear elasticity relationship represents the hysteresis loops of the stress–strain relationship in the mechanical cycles. The performance of the proposed model is evaluated against existing experimental results for clay and sand in terms of their thermal cyclic behaviour, drained/undrained triaxial compression, and mechanical cyclic behaviour at different temperatures. It is evident that the UTMBS model is able to simulate various thermo-mechanical behaviours of clay and sand.

Insights on phase speed and the critical Reynolds number of falling films.

We revisit the studies of gravity-driven viscous falling films with and without imposed shear stress to provide new perspectives on phase speed and the critical Reynolds number for surface instability. We use the traditional long-wave expansion technique implemented for investigating the linear stability analysis [C.S. Yih, Phys. Fluids 6, 321 (1963)0031-917110.1063/1.1706737]. The principal purpose is to create a unified relationship between the leading-order phase speed and the critical Reynolds number that will hold for falling films on impermeable substrates with or without shear stress acting at the liquid film surface. The analytical result demonstrates that the critical Reynolds number for the onset of surface instability is [5/(2c_{0})]cotθ, where c_{0} is the leading-order phase speed of the surface mode and θ is the angle of inclination with the horizontal. Clearly, the critical Reynolds number of the surface mode is explicitly dependent on the leading-order phase speed. Furthermore, we reveal that the basic parallel flow with or without imposed shear stress is linearly unstable to infinitesimal disturbances if the modified Reynolds number, Re_{M}=(Rec_{0}/cotθ)[ReistheReynoldsnumber,andθ≠π/2], is greater than its critical value of 5/2, which is independent of the shear stress applied at the film surface. In addition, it is demonstrated that Re_{M} controls the surface instability in the long-wave regime for both shear-imposed and non-shear-imposed film flows.

Footprints in an urban array model under multiple wind directions: A wind tunnel experiment investigation

This study investigates the footprint distributions at various measurement positions in an urban array model, considering two incident wind directions, 22.5° and 45°, by a wind tunnel experiment. The airflow velocity and tracer concentration are simultaneously measured by an X-probe hot wire anemometer and a flame ionization detector, respectively, to assess the vertical flux of tracer gas. The experiment findings reveal a unified relationship between footprint distributions and measurement heights, as well as pronounced heterogeneity in footprints across horizontal positions in the urban model. The concentration footprints in both wind directions exhibit local patterns, primarily influenced by the local canopy vortex between buildings, and global patterns, arising from the large-scale building configuration within the urban model. Notably, the local pattern demonstrates a significant spanwise tilt in the 22.5° case and wave-like propagation along the streamwise direction in the 45° case, while the global pattern, characterized by contour lines developing along rows of blocks, remains consistent across both scenarios. Moreover, the flux footprint has constrained source areas compared to the concentration footprint, with its peak coinciding with areas exhibiting local patterns, where turbulent flux contribution exceeds 70%. These findings emphasize the importance of predicting the dispersion driven by local canopy vortex in the numerical modeling of urban footprint applications.

Research on differential game of platform corporate social responsibility governance strategy considering user and public scrutiny.

The development of digital technology and the sharing economy has extended corporations' innovative activities beyond the corporation's boundaries, so it has become more urgent to govern the lack of social responsibility and alienation of platform corporations from the perspective of social agents. First, the platform's CSR classification and social responsibility governance's main content are analyzed in this research. Then, this study uses government agencies, platform corporations, users, and the public as governance subjects and compares governance decisions with and without public and user oversight. Finally, the optimal balance strategy for each governing subject, the optimal trajectory of governance volume, and the trajectory of total revenue are obtained. The study found that: 1) Public and user supervision can improve the governance volume while encourage the governance motivation of government agencies and platform corporations. 2) The level of user supervision effort has a greater impact on the total governance revenue than public supervision. 3) The revenue of the system and the governance volume are greater in a centralized decision-making process, indicating that those involved should co-operate in governance based on the principle of mutual benefit. 4) The platform corporation has an incompatible but unified relationship between its social duty and financial success.

Gravitationally induced unified relation among duality, coherence, steering, and maximal average fidelity

Recently, numerous measures have been proposed for quantifying the quantumness of a given system, and the existence of intrinsic connections among quantum resource measures has been proven. Here, we study the unified relationship between duality, first-order coherence, three-setting linear steering inequality, and maximum average fidelity between two masses due to gravity. Under gravitational inducement, an equivalent relationship was identified between the first-order coherence and duality. The coherence of a system can be controlled by adjusting arm lengths and the distance between the arms of an interferometer. In most cases, the first-order coherence of a system cannot be maximised. Furthermore, a trade-off relationship between gravitationally induced duality and steering violations was derived. We can adjust the arm length and distance between the arms of the interferometer such that the steering violation reaches its maximum at phase π\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi $$\\end{document}. The results show that the value of the steering violation is always greater than 1; that is, the state of the system is steerable. In addition, we explored the intrinsic relationship between duality and the maximal average fidelity due to gravity. In most cases, the maximum average fidelity of the system is greater than 2/3, indicating that the state is useful for quantum teleportation. These results are important for investigating the intrinsic relationships among various quantum resources within the framework of gravity.

Investigation of REV scale and anisotropy for 2D permeable fracture Networks: The role of geological entropy

To investigate the intrinsic association between geometrical properties and permeability of anisotropic fractured media, a methodology of geological entropy is applied to anisotropic fracture networks for the evaluation of seepage fields. By integrating the synthetic effect of fracture geometrical parameters (e.g., trace length, spacing, dip angle, and aperture), the global connectivity of fracture networks is quantified by the entropy scale (Hs), while the directional entropy scale (Hs,α) is used to characterize the local geometrical anisotropy in arbitrary orientations. A series of hydraulic representative elementary volumes (REVs) of fracture patterns with various geometrical properties are acquired based on continuum analysis. The permeability in the continuum scale is obtained from steady-state flow simulations. Sensitivity analyses are performed to understand the geometrical dependence of permeability parameters regarding entropy indices. It is found that a systematic increase in trace length, spacing, and dip angle is correlated with an increase, decrease, and equilibrium in entropy, respectively, which corresponds to a change in hydraulic REV sizes that can be expressed as a power-law function related to the Hs. Moreover, Hs,α can well explain the permeability anisotropy resulting from the spatial order of fracture networks, and a unified mathematical relationship for the effective permeability coefficients in arbitrary orientations versus the Hs,α is proposed, independent of variations in fracture patterns and scales. The results indicate that geological entropy, related to the geometrical properties and spatial distribution of fractures, is appropriate to characterize the permeability of anisotropic systems.

Unconfined Compressive Strength of Cement-Stabilized Qiantang River Silty Clay.

Cement-stabilization of weak and soft soils is an efficient way for ground improvement. Traditional Portland cement remains the most popular cementitious material in practice, and thus, a proper dosage design of cement-stabilized soil is of practical interest to meet the sustainable engineering requirements and to remedy environmental concerns. Based on the unconfined compression test of cement-stabilized Qiantang River silty clay, the effects of cement content, mixing moisture content, mixing-water-to-cement ratio, and curing time on the unconfined compressive strength were investigated. The results show that the mixing-water-to-cement ratio can comprehensively characterize the effects of cement content and water content on the unconfined compressive strength of the cement-stabilized clay. A prediction method for the unconfined compressive strength of cement-stabilized Qiantang River silty clay has been proposed with considerations for mixing-water-to-cement ratio and curing time. By comparing the experimental data of the present study with the existing literature data, it is found that there is a unified relationship between the unconfined compressive strength and the mixing-water-to-cement ratio of cement-stabilized Qiantang River silty clay, kaolin, Singapore marine clay, and Bangkok clay under the same curing time. The prediction method recommended by the standard may overestimate the unconfined compressive strength of cement-stabilized Qiantang River silty clay cured for 90 days.

Heterogeneous binding of polymers on curved nanoparticles.

Unraveling protracted polymer binding on curved surfaces of nanoparticles (NPs) is important for the fabrication of multifunctional nanostructures in cutting-edge research disciplines such as directional self-assembly and nanomedicine. By using our newly developed Integral of First-passage Times (IFS), we demonstrate a curvature-dependent heterogeneous binding of polymers on curved NPs, not only in terms of the binding dynamics but also in terms of the final adsorption densities. The highly curved surfaces on NPs can adsorb larger density polymers with binding kinetics that are faster than those on less curved areas, which is consistent with recent experimental observations. In particular, the spherical corners on cubic NPs with a radius of R = 3.0 nm can adsorb polymers at a density 4.1 times higher than those on planar surfaces and 1.7 times higher than those on rod edge surfaces. A unified relationship between adsorption densities and surface curvatures is proposed to collapse all the data onto one master curve. The findings demonstrate a heterogeneous binding of polymers on curved NPs, providing effective guidelines for the rational design of functional nanostructures in different applications.

Aesthetic gene and prospect of garden city from the perspective of Chinese dream

This study aims to delve into the impact of the Chinese Dream ideology on the development and aesthetic characteristics of park cities. Building upon their dialectical and unified relationship, it seeks to predict the evolutionary trajectory of urban modernization and methods to enhance residents' quality of life. Focusing on domestic cases of park city construction, the research employs innovative approaches such as on-site investigations, semi-structured interviews, and literature reviews. A distinctive contribution of this study is the introduction of the concept of "aesthetic genes," which is used to describe and interpret aesthetic elements and cultural features within park cities from five different perspectives. Furthermore, the research offers profound analyses from four distinct viewpoints regarding the future prospects of park city development in the new era. By organically integrating the Chinese Dream ideology with the concept of park cities, this study provides valuable theoretical insights and practical guidance in the fields of sustainable park city construction and urban aesthetics research.

Using an age-grouped Gaussian-based two-step floating catchment area method (AG2SFCA) to measure walking accessibility to urban parks: With an explicit focus on elderly

Rapid population aging has raised the number of elderly residents dramatically, calling out the challenge to provide elders with sufficient and equal urban park spaces in cities with limited land use. Ensuring elders have matched accessibility to urban parks is essential for social sustainability. This study introduces an age-grouped Gaussian-based two-step floating catchment area method (AG2SFCA) to more accurately reflect the urban park accessibility of the elderly and to explore the influence of population aging on residents' accessibility evolution. The applicability and rationality of AG2SFCA are demonstrated through the case study in the Chengdu city center. The results indicate that most elders' urban park accessibility and overall horizontal equity level are overestimated in the previous adjuted 2SFCA approach. There is no unified relationship between residents' accessibility and the population aging condition in their community. However, residents' accessibility is related to the overall aging level of society. Even in the urban core of Chengdu, many elders still have no access to urban parks. The high proximity can help elders maintain their matched accessibility to urban parks despite an aging population. This study enriches the application of 2SFCA-style models and helps provide empirical support to governments, urban planners, and facility operators for targeted decision-making.

Strategic guidelines for the development of forest industry of Ukraine in the post-war period

This research presents the peculiarities of the formation of a modern strategy for the development of forest industry in Ukraine. It was determined that the implementation of strategic management in the postwar period should be based on ensuring the balance of forest use. In order to increase the role of forest resources in the share of national wealth, it is necessary to move to such a model of forest use, which would ensure the proper profit of forest enterprises in a unified relationship, minimize the destructive impact on forest resources, and also ensure the appropriate level of environmental and economic security for the state. A comprehensive scientific assessment of the institutional aspects of economic relations in the context of the existing vector and conditions of development of the forestry industry of Ukraine, including the strategic guidelines approved by the State Forest Management Strategy until 2035, was carried out. The modern features of forest use caused by military operations in Ukraine are revealed. And the algorithm of their further development at different levels of the economic hierarchy is also substantiated. Conceptual approaches to the post-war management of forest resources of Ukraine in the conditions of climatic changes observed in recent decades, as well as in accordance with modern climate-oriented strategies in the world, approved at the summit in Glasgow in 2021, are outlined. Attention is paid to ways of counteracting the destructive impact of climate change on the forestry complex, as well as to the problematic issues of reforestation technologies, afforestation and forest care in order to adapt them to modern climate changes. It has been proven that the main task of state policy in the field of forest resource management is to ensure effective and proper protection, balanced use and formation of forest reproduction mechanisms, as well as the availability of appropriate tools. It was also noted that at the local levels, the implementation of the approved strategy for the development of forestry requires a comprehensive approach to individual areas of innovative activity in the forestry industry. It was found that the appropriate level of implementation of the set of specified measures creates favorable conditions for the effective implementation of the provisions of the approved normative legal acts regarding the use and reproduction of forests in Ukraine.

Towards a Communicative City: Applying a New Framework for Understanding Communication and City

Since the Industrial Revolution, with the productivity change brought by technology and modern mass media, the distance between time and space has been shortened and the imagined "urbancommunity" has been brought about. Newspapers, television and other mass media can not only have information functions, but also unite and connect people into a whole through the communication network, thus promoting the integration of urban communities. However, with the development of the internet and the explosive growth of urban population, the rise of individualism has made the connection of traditional urban society declared unorganized, and the traditional mass media has also lost its unified integration ability (Bruhn, 2011:8). The city has fallen into an unprecedented communication crisis, and the construction of a coordinated and unified relationship between different individuals has become anurgent problem to be solved. In other words, the global expansion of the modernization process has led to the fragmentation of society, and people find themselves in a modern world that has lost contact with the roots of communicability.

Critical firing conditions for titanium alloys by molten droplet ignition

Reliable service of indispensable titanium alloys in aeroengines is limited by titanium fire with unclear critical conditions. In this study, critical conditions in the form of parameter phase diagrams for secondary burning were determined by molten droplet ignition. Finite element analysis (FEA) reveals that the molten droplet size (R0), relative oxygen content (Pr), and initial temperature (T0) significantly affect titanium fire following power exponential laws. In addition, Pr and T0 affect ablation synergically, and a unified empirical relationship for critical ablation of titanium alloy is established. Furthermore, the critical T0 of a typical TC4 alloy under 20% Pr is higher than 973 K, which explains the reliable service performance of TC4 alloy at ≤ 873 K in compressors in commerical air engines. In addition, the critical empirical conditions are consistent with the FEA results, and the deviation occurs due to oxidation at T0 ≥ 673 K. Moreover, the ablated TC4 alloy can be divided into five characteristic zones, and loose and porous oxide scales are formed at the front of the titanium fire. The present study points the way towards long-lifetime services of TC4 alloys through sound titanium fire protection strategies.

Theoretical Foundation of the Linear Relationship between the Midlatitude Eddy Heat Flux and Fall-to-Spring Polar Ozone Buildup

Abstract It has been demonstrated that there is a globally unified linear relationship between the interannual variations of the fall-to-spring polar ozone accumulation and the winter-mean poleward eddy heat flux on the 100 hPa pressure surface. The foundation of this relationship is investigated using time-slice experiments on a chemistry–climate model with two levels of ozone-depleting substances (ODSs). The features of the transport field are interpreted by decomposing the horizontal ozone flux caused by the residual circulation into contributing processes including the eddy heat flux with the aid of the transformed Eulerian-mean momentum equation followed by rearrangement of terms. The linear relationship between the interannual variations of the fall-to-spring ozone buildup integrated poleward and above a reference point Pref on a meridional plane and the poleward eddy heat flux during the corresponding period at Pref is realized for each hemisphere implying that the interhemispheric unification should be treated with caution. This relationship is interpreted using the fact that the interannual variation of poleward ozone transport in the upper stratosphere is captured well by the vertical convergence of the constituent-based Eliassen–Palm (EP) flux (), which is defined as the product of the constituent (ozone) mixing ratio and EP flux. The eddy momentum flux contributes to the meridional ozone transport in combination with the eddy heat flux in the form of the divergence of , although it is not responsible for realizing the linear relationship. The dependence of the linearity on the location of Pref and ODS levels is discussed.

Evolution of breakout force with operation period for deeply embedded spudcan in clay

The extraction of spudcan foundation in clay can often be difficult and time-consuming considering the large pull-out force required to overcome the breakout resistance. This is particularly an issue for long operation periods, during which the dissipation of excess pore pressure in the soil will increase the base suction and undrained shear strength of soil. This paper investigates the spudcan breakout force in clay deposits through a coupled pore fluid-effective stress large deformation finite element approach. The complete process of spudcan installation, operation and removal is simulated. The numerical approach is verified against existing centrifuge test results. A good agreement can be obtained between the numerical and experimental results in terms of normalised breakout force and operation period. A series of parametric study is then carried out to explore the effects of installation depth, operational load and soil parameters. Based on the numerical results, a unified relationship can be established between the dimensionless forms of breakout force and operation period, for which a simple algebraic expression is proposed for the convenient assessment of breakout force recovery.