The boundary delineation of the urban-rural fringe (URF) is the basic work of fine planning and governance of cities, which plays a positive role in promoting the process of global sustainable ...development and urban and rural integration. In the past, the delineation of URF had shortcomings such as a single selected data source, difficulty in obtaining data, and low spatial and temporal resolution. This study combines Point of Interest (POI) and Nighttime Light (NTL) data, proposes a new spatial recognition method of URF according to the characteristics of urban and rural spatial structure, and conducts empirical analysis with Wuhan as the research object, combining the information entropy of land use structure, NDVI, and population density data to verify and compare the delineation results and field verification was conducted for typical areas. The results show that (1) the fusion of POI and NTL can maximize the use of the characteristics of the differences in facility types, light intensity, and resolution between POI and NTL, compared with the urban-rural fringe boundary identified by POI, NTL or population density data alone, and it is more accurate and time-sensitive; (2) NPP and POI (fusion data of Suomi NPP-VIIRS and POI) can quantitatively identify potential central area and multi-layer structure of the city. It fluctuates between 0.2 and 0.6 in the urban core area of Wuhan and between 0.1 and 0.3 in the new town clusters, while in the URF and rural areas drops sharply to below 0.1; (3) the urban-rural fringe area of Wuhan covers a total area of 1482.35 km
, accounting for 17.30% of the total area of the city. Its land use types are mainly construction land, water area, and cultivated land, accounting for 40.75%, 30.03%, and 14.60% of the URF, respectively. Its NDVI and population density are at a medium level, with values of 1.630 and 2556.28 persons/km
respectively; (4) the double mutation law of NPP and POI in urban and rural space confirms that the URF exists objectively as a regional entity generated in the process of urban expansion, provides empirical support for the theory of urban and rural ternary structure, and has a positive reference value for the allocation of global infrastructure, industrial division, ecological function division, and other researches.
Rational delineation of urban–rural boundaries is a foundational prerequisite for holistic urban and rural development planning and rational resource allocation. However, using a single data source ...for urban–rural boundaries yields non-comprehensive results. To address this problem, the present study proposes a method for extracting urban–rural boundaries using multiple sources such as population data, nighttime light data, land use, and points of interest (POI) data. Considering Guizhou Province for a case study, this study presents a two-step method for identifying urban–rural boundaries. First, the random forest model was combined with the dasymetric mapping method to obtain the province’s population spatialization data with a 30-m resolution. Second, based on the spatialized population, the urban–rural boundary for Guizhou Province in 2020 was extracted using the breaking point method. This method comprehensively integrated the benefits of various data and judiciously extracted the boundaries of the main urban areas and small and medium-sized towns of each city in the study province at the same spatial scale. The stratified random sampling method revealed an average overall accuracy of 88.05%. The proposed method has high universality and application value and can be useful for accurate and practical identification of urban–rural boundaries.
The relevance. Diffusers, either as nozzles or constituent elements, are frequently used in many mechanisms and machines. In this regard, the study of viscous fluid flow in diffusers aims to discover ...patterns of changes in the flow's hydrodynamic parameters, allowing better understanding of the nature of flow as a function of Reynolds number. Following the results of the analysis of the study, conditions for the proper construction of the mechanism unit, ensuring its reliable and durable operation will be revealed. The main aim of this study is to determine the velocity profiles in the flat diffuser for a viscous incompressible fluid by integrating the simplified Navier–Stokes differential equations under the established initial and boundary conditions, as well as the bifurcation point's dependence on the opening angle and Reynolds number of the diffuser. Objects: a flat diffuser in which viscous incompressible fluid moves. At the same time, revealing the patterns of changes of the hydrodynamic parameters of the flow is of defining value when choosing the structural dimension of devices and mechanisms, the main part of which is the flat diffuser. Methods. To reveal the patterns of changes of the hydrodynamic parameters of the flow in a flat diffuser, the study is based on the fundamental nonlinear differential equations of viscous fluid mechanics, which in a general case are not subject to an exact mathematical solution. For integration in the nonlinear differential equations, due to the smallness, the nonlinear-convective terms are neglected, and the inertial terms are also partially simplified. Such a simplification is justified if the velocities are very small or if the dynamic coefficient of viscosity of the fluid is very large. A method for solving the boundary value problem was developed, and regularities for changing the flow parameters were obtained. According to the derived regularities, graphs of the change in velocity, pressure and shear stresses on the wall of the fixed channel were plotted and the coordinates of the separation point were determined. Results. Depending on the angle of the diffuser opening and the Reynolds number, a general solution of the approximating Navier–Stokes equations was given. In accordance with the nature of the motion, the boundary conditions of the problem were established and the boundary value problem was stated. A method for integrating a boundary value problem was developed, and regularities for the change in velocities along the length of the diffuser were obtained for a parabolic distribution of velocities in the inlet sections. Graphs of the change in radial velocities along the length and at a fixed value of the opening angle were constructed, a flow pattern and the transition of a single-mode flow to multimode operation were obtained. For a fixed opening angle and Reynolds number, the conditions for flow separation from a fixed wall were derived, where the flow velocity changes the sign.
In this paper we consider the modelling of nonlinear wave transformation by means of weakly nonlinear Boussinesq models. For a given couple linear dispersion relation-linear shoaling parameter, we ...show how to derive two systems of nonlinear PDEs differing in the form of the linear dispersive operators. In particular, within the same asymptotic accuracy, these operators can either be formulated by means of derivatives of the velocity, or in terms of derivatives of the flux. In the first case we speak of amplitude-velocity form of the model, in the second of amplitude-flux form. We show examples of these couples for several linear relations, including a new amplitude-flux variant of the model of Nwogu (J. Waterway, Port, Coast. Ocean Eng. 119, 1993). We then show, both analytically and by numerical nonlinear shoaling tests, that while for small amplitude waves the accuracy of the dispersion and shoaling relations is fundamental, when approaching breaking conditions it is only the amplitude-velocity or amplitude-flux form of the equations which determines the behaviour of the model, and in particular the shape and the height of the waves. In this regime we thus find only two types of behaviours, whatever the form of the linear dispersion relation and shoaling coefficient. This knowledge has tremendous importance when considering the use of these models in conjunction with some wave breaking detection and dissipation mechanism.
•The impact of the nonlinear form of enhanced Boussinesq equations is studied in regions close to wave breaking.•Given a linear dispersion/shoaling relation, we recall how to build two models: in velocity or in flux form.•A new model is derived in the study, equivalent in the linearized case to the one of (Nwogu, J. Waterw. Port. C.-ASCE 1994).•Close to breaking we find that only the velocity or flux form impacts wave shapes.•This knowledge has tremendous importance when using these models with added breaking detection and dissipation mechanisms.
The conservation of paintings on canvas is closely associated with the understanding of their physico-mechanical properties. Using mechanical testing is essential when developing tools to assess the ...level of vulnerability and risks of mechanical degradation in paintings. This paper addresses a series of studies highlighting the need of a systemic approach to decision-making for structural treatments.
The conservation of paintings on canvas is closely associated with the understanding of their physico-mechanical properties. Using mechanical testing is essential when developing tools to assess the ...level of vulnerability and risks of mechanical degradation in paintings. This paper addresses a series of studies highlighting the need of a systemic approach to decision-making for structural treatments.
Cracking is one of the main causes requiring replacement of asphalt pavement, but the traditional mix design methodologies do not require testing of asphalt mixture cracking resistance. Two cracking ...tests, Thermal Stress Restrained Specimen Test (TSRST) and Semi-Circular Bending (SCB), were evaluated in this study to determine their suitability for adapting as part of mixture type testing and quality control protocol. Eight different mixtures were used to evaluate the test methods, having a wide range of maximum aggregate size, mix type, binder grade and target application. Half of the mixtures were plant-produced, while the other half were laboratory-produced. The results showed that TSRST is the preferred method for mix design because of smaller result variability and better distinguishing between the different mixtures. At the same time, a reasonable correlation exists between TSRST and SCB tests. This makes it possible to use the simpler SCB test for pre-screening samples to further test using the TSRST. The equivalent ageing protocol is a pre-requisite to be able to compare the test results. The fraass breaking point, a measure of bitumen low-temperature cracking resistance, did not provide good correlation with either of the mixture cracking tests.
This paper deals with the first analysis of the neutron and gamma time series measured with organic scintillators from plutonium samples by using information measures. Fast neutron detection with ...organic scintillators has been widely used for various nuclear safeguards applications and homeland security. One of the significant attributes of special nuclear materials (SNM) is the high multiplicity events in a short period of time. The time distributions of neutron and gamma-rays events for the plutonium metal plates designed as fuel plates for the Idaho National Laboratory (INL) Zero Power were measured with the Fast Neutron Multiplicity Counter (FNMC) consisting of 8 EJ-309 liquid scintillators and 8 stilbene detectors. Since the neutron correlated counts within the coincidence window of 40 ns are related to 240Pu effective mass of plutonium metal plates, it is of interest to investigate the randomness of the measured neutron and gamma-rays events. To access such information, we resort to complexity measures in the hope of being able to connect complexity values with the reliability of detection. That was done through (i) application of Kolmogorov complexity (KC) and its derivatives Kolmogorov spectrum and its highest value (KCM) and running complexity (RKC) and (ii) establishing the “breaking point” after which there exists a sharp drop in the running Kolmogorov complexity of the neutron and gamma-rays time series. It was found that the complexity of all the time series detected from the sample with 5, 9, 11, 13, and 15 plutonium plates had the high almost identical values of KC while the sample with 3 plates had by one-third smaller KC values than all the others. These calculations were supplemented by the Lypaunov exponents for a time series and the National Institute of Standards and Technology (NIST)tests. The low KC values can be addressed to the different sources of uncertainties in measuring procedure with the sample consisting of three plates. The complexity measures applied in this study are capable of revealing aspects of information that would otherwise remain hidden to the one-off complexity estimate.
•Time series from the plutonium samples measured with organic scintillators.•Time series investigated by application of Kolmogorov complexity and its derivates.•Establishing the “breaking point” in the running Kolmogorov complexity.•Time series measured either by 8 or 16 detectors show nearly the same randomness.•Scintillators reliably measured the neutron and gamma events on a nanosecond scale.
In this paper, we investigate how many convergence orders of discontinuous Galerkin (DG) method for numerically solving neutral delay differential equations (NDDEs). Although discontinuous behaviour ...may occur in the derivatives of the exact solution at every breaking point, it is shown that the convergence order of the p-degree DG solution at the mesh points and characteristic points can achieve
and
, respectively. Numerical examples are also reported to confirm the theoretical results.
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