Distribution Characteristics Research Articles

Analysis of seismic damage and seismic capacity of the structure of the ultrahigh pagoda

AbstractThe Chongwen Pagoda is the tallest masonry pagoda in China, with numerous openings inside the pagoda body. It is prone to damage during earthquakes, and the patterns of damage are complex. In order to scientifically analyze the dynamic performance, earthquake damage patterns, and mechanisms of the pagoda structure, on‐site dynamic testing was conducted to obtain the dynamic characteristics of the structure. A numerical model was established using Abaqus finite element software to calculate the dynamic characteristics of the structure. The results were compared with the testing results and showed a close agreement. El‐Centro earthquake wave, Taft earthquake wave, and Lanzhou artificial earthquake wave were selected as earthquake inputs based on site conditions, simulating frequent earthquakes, fortification earthquakes, and rare earthquakes with a magnitude of 9. The dynamic response of the pagoda structure was calculated, and the relationship between acceleration amplification factor, interstorey displacement, and interstorey displacement angle with floor height was analyzed. The seismic damage to the structure and the distribution of primary tensile stresses were studied, revealing the seismic damage mechanisms and the distribution characteristics of vulnerable areas in the Chongwen Pagoda. The research results provide references for the seismic assessment of this ancient pagoda.

Microplastics occurrence and distribution characteristics in mulched agricultural soils of Guizhou province

Microplastics pollution in agricultural soil is increasingly recognized, but the specific situation varies with geography, climate conditions, and farming practices. The karst landscape, a typical geomorphology in China, demands a deeper understanding of microplastics pollution in such areas. This research zeroes in on Guizhou, a province known for its karst formations, by collecting soil samples from the mulched cultivation layer in ten counties and cities. The study employed metallographic microscopy, scanning electron microscopy (SEM-EDS), and Fourier-transform infrared spectroscopy (FT-IR) to analyze the presence and distribution of microplastics. Results show that polyethylene is the predominant component of microplastics in the mulched agricultural soils of Guizhou, primarily existing as irregular fragments in black, transparent, and translucent forms, with diameters of 40 ~ 120 μm and rough surfaces marked by significant erosion. The concentration of microplastics varies from 143.28 to 3,283.46 items/kg, averaging 1,150.60 ± 647.86 items/kg. The majority of particles accounting for 64.79% are sized between 10 ~ 100 μm. A highly significant positive correlation (p < 0.001) is found between mulching duration and microplastics concentration, indicating that prolonged mulching increases microplastics accumulation in farmlands. Additionally, crop type, irrigation method, and soil type also influence microplastics concentration. This study highlights the escalating issue of microplastics pollution in China’s karst regions, underscoring the need for attention.

Geographical Evaluation of Real Estate Services Offices in the City of Abha - Saudi Arabia, A Geographical Study using Geographic Information Systems (GIS)

Service geography is one of the branches of applied geography that has emerged as an applied intellectual interest to engage with the immediate direct needs of both urban and rural communities. The importance of studying services is due to their connection to economic planning, so geographical interest in them increases, as applied geography is based on a specific approach and philosophy of relevance or social benefit that focuses on the application of geographical knowledge and skills. To come up with solutions to real-world social, economic and environmental problems. The study focused on the use of geographic information systems in analyzing the geographic calendar of rental offices in the city of Abha, relying on the most important applied aspects of geographic information systems represented in spatial analysis. To reveal the characteristics of the spatial distribution of rental offices and their distribution pattern, and to evaluate the efficiency of their distribution according to the local standard. The study came out with a number of results and recommendations, and also verified the hypotheses assumed by the researchers.

Evaluating the Efficiency of Spatial Distribution of ATM Machines in Abha City using Geographical Information Systems

This study aims to use geographic information systems to analyze the spatial distribution of ATMs in Abha city. This is based on the most important applied aspects of geographic information systems, namely spatial analysis, to reveal the characteristics of the spatial distribution of ATMs and their distribution pattern, and to evaluate the efficiency of their distribution according to spatial variables. The study came out with a number of results and recommendations, the most important of which is increasing the number of ATMs in high-density neighborhoods that are deprived of service, which reduces the pressure on them, in a way that ensures their sustainability, and in a manner that is proportional to both the area and the number of residents in the city's neighborhoods.

Transient pressure characteristic investigation and performance analysis of a novel three-port gas pressure dividing (GPD) device

The wave-rotor based gas pressure dividing (GPD) is a novel concept to allocate and utilize the pressure energy of gases, presenting significant potential in engineering fields. However, studies about GPD devices are rare, and related mechanism analysis and performance investigations are almost blank. In this study, an experimental platform upon a novel three-port GPD device is established. The transient pressure distribution characteristics in passages of GPD wave rotor are determined experimentally with the customized pressure acquisition system. Besides, the effects of rotation speed, compression ratio (β), and expansion ratio (α) on the pressure dividing performance of the GPD device are systematically examined via experiments and numerical simulations. The results indicate that the interaction of shock waves and expansion waves in passages can enable the medium-pressure gas to divide into high-pressure and low-pressure gases. The rotation speed of 2340 rpm is optimized, determining the greatest gas compression and expansion. The compression ratio increase can improve the compression efficiency and reduce the expansion depth, while the expansion ratio increase can present an opposite regulation. The flow rate efficiency of LP port is decreased with the compression ratio and expansion ratio increase.

Spatial and Temporal Evolution Characteristics of the Ecosystem Service Value along the Beijing–Hangzhou Grand Canal

The study of the spatiotemporal evolution characteristics of ecosystem service values (ESVs) is an important basis for the coordinated development of the regional nature, economy, and society and the optimization of the ecological environment. The ecological zone is an important component of the Beijing–Hangzhou Grand Canal cultural belt. Ecosystem services are a concrete manifestation of land use structure and function. A thorough study of the value of ecosystem services in areas along the Beijing–Hangzhou Grand Canal is important for promoting the long-term and stable sustainable development of the regional economy. Based on a revised equivalent factor table, this study selected land use data from 1991, 2006, and 2021 to analyze the temporal and spatial evolution characteristics of ESVs along the Beijing–Hangzhou Grand Canal. The results show that (1) the ESVs along the Grand Canal first increased and then decreased from 1991 to 2021. The reason for this is the change in land use along the Beijing–Hangzhou Grand Canal. Specifically, the conversion of land use types from farmland to water areas contributed to the increase in the value of ecosystem services, while the conversion of farmland and grassland into construction land led to a decrease in the service value of the region. (2) the value of individual ecosystem services along the Beijing–Hangzhou Grand Canal from 1991 to 2021 varied greatly. The ESV provided by hydrological regulation was the largest and the ESV provided by maintenance nutrients was the smallest. (3) the areas along the Beijing–Hangzhou Grand Canal exhibited a specific pattern in terms of the value of ecosystem services, with the regions centered in Beijing and Tianjin showing relatively low values, while the middle section of the Grand Canal demonstrated relatively high ESV. According to the spatial and temporal distribution characteristics and the leading factor for the changes in ESVs, appropriate policies can be formulated in respective regions to implement ecological protection and land use planning, thereby providing a reference for the adaptation and restoration strategies of the ecosystem along the Grand Canal.

The focus on addressing vegetation risks in China should shift from the western past to the eastern future

Actively addressing the negative effects of global climate change on vegetation has always been a hot topic of academic concern. How to accurately and comprehensively assess the vegetation risk due to climate change has been rarely reported. By comprehensively considering three dimensions—species structure (species richness), carbon sequestration function (Net Primary Production, NPP), and physiological processes (transpiration)—and based on the prediction of the future distribution characteristics of 3,370 plant species in China, this study quantified the vegetation risk and its driving mechanisms under different Shared Socioeconomic Pathways. The composite index of vegetation risk decreased to the west of the Hu Huanyong Line (NT and QTP regions) but increased to the east (NE and ST regions), with the magnitude of increase growing with the intensification of emission scenarios. In the 2070 s, the proportion of high risk and extremely high-risk areas in the east increased from 14.5 % under SSP126 to 50.0 % under SSP585. NPP and transpiration generally show an increasing trend, and species richness changes similarly to vegetation risk. In the 2070 s under SSP585, 39.2 % of QTP areas see a species richness increase over 50 %, while 33.0 % of ST areas experience a decrease over 30 %. The increase in vegetation risk in the NE region is driven by increased soil moisture, while in the ST region, it is mainly due to decreased runoff and SPEI. Therefore, China should actively respond to the risk of vegetation degradation in the east due to future climate change.

Distribution Characteristics and Genesis Mechanism of Ground Fissures in Three Northern Counties of the North China Plain

Distribution Characteristics and Genesis Mechanism of Ground Fissures in Three Northern Counties of the North China Plain

Formation mechanism of deep to ultra-deep carbonate reservoir: a case study of the Ediacaran Dengying Formation, Penglai area, Sichuan Basin

The formation of high-quality deep to ultra-deep carbonate reservoirs presents a topic worthy of thorough exploration. Focusing on the Ediacaran (Sinian) Dengying Formation in the Penglai area of the Sichuan Basin, we analysed genesis mechanisms of deep to ultra-deep marine carbonate reservoirs through drilling/logging, seismic data and analytical tests, which showed the dolomite reservoir primarily consists of secondary solution pores and cavities, exhibiting characteristics of vertical overlap and horizontal continuous distribution. The microbial mound beach, which represents the main dominant facies type within the reservoir, can be categorised into three types: high-quality reservoir, medium-quality reservoir and poor reservoir. The reservoir has undergone five stages: syngenetic to quasi-syngenetic, shallow burial, supergene, burial and deep burial adjustment stages. It is postulated that the development of deep to ultra-deep carbonate reservoirs is governed by sedimentary facies, with the type and structure of carbonate influencing the development and evolution of reservoir pores. Multiphase diagenetic fluids further modify and enhanced the properties of the reservoirs. Deep and ultra-deep carbonate reservoirs exhibit strong heterogeneity, and high-quality reservoirs are characterised by multi-factor joint control and multi-stage composite genesis. The lithological and structural–lithological traps associated with them commonly cluster in large areas so effective identification of favourable sedimentary facies and reservoirs is crucial for predicting deep to ultra-deep carbonate reservoirs, characterising traps and improving the success rate of drilling.

Analysis of the spatio-temporal distribution of Chinese professional football clubs and influential factors based on empirical evidence of clubs

The frequent relocation of professional football clubs is a phenomenon unique to Chinese professional football, which has long attracted extensive attention from policy makers and scholars. Using data on spatial geography and competitive levels between 1994 and 2021, this research explores the spatial distribution and migration characteristics of top professional football clubs in China, in which GIS spatial analysis and exploratory spatial data analysis (ESDA) were used to analyze the influence of the regional economic, demographic, and developmental levels of the sports industry and institutional supply on the distribution and migration of clubs. The results indicate the following: (1) the overall spatial distribution of professional football clubs in China shows the pattern of “more in the east and less in the west”, and the degree of club concentration gradually increases over time; (2) the migration frequency and downward migration of professional football clubs in China gradually decreased during the period of C League and CSL, and the overall situation tends to be stable; and (3) in the early stages of development of professional leagues, changes in ownership and local policy supply had a significant impact on the distribution and migration of professional clubs. As time progressed, the top-down design of institutional arrangements changed, and the regional economic, demographic, and developmental levels of the sports industry gradually became the essential determinants of the distribution and migration of professional football clubs. In the future, Chinese professional football clubs should focus on rationalizing the advantages of the regional economy, demography, and sports industry as well as reducing their reliance on short-term resources, such as corporate investment and policy benefits.

Occurrence characteristics, source analysis and ecological risk of PFASs in different cultivated soil at an urban scale in Yangtze River Basin

Per- and polyfluorinated substances (PFASs) contaminates the arable soil through multiple paths, and poses a threat to both farmland ecosystems and human health. In this study, the potential sources and distribution characteristics of 12 legacy PFASs in the soil and rivers for irrigation purposes were investigated in farmland systems, and the risks posed by PFASs to earthworm and aquatic organisms were also assessed. Based on field investigations in Yangtze River Basin, we found long-chain perfluoroalkyl carboxylic acids (PFCAs) were the major contaminants in arable soil and rivers for irrigation purposes, with PFOA (Perfluorooctanoic acid) being the most dominant monomer. Concentration levels of PFASs in arable soil were strongly related to land use types, the average concentration of PFASs (341.18 ± 600.19 ng/g) in the paddy fields was 100-fold higher than that of dry fields (3.79 ± 4.11 ng/g). Source apportionment revealed that PFASs detected in paddy fields were mainly associated with industrial effluents, domestic sewage, and irrigation water. In rivers for irrigation purposes, higher PFASs contamination were primarily distributed in industrial areas, such as plastic processing, paper, textile and electronics factories. The PFASs in the irrigation river water posed a low-medium risk to daphnia and fish, while the PFASs (PFOA and perfluorododecanoic acid (PFDoDA)) in soil posed a medium-high risk to earthworms. These results provided insights that sewage irrigation caused serious pollution of PFASs in the agricultural environment, should be paid more attention.

Distribution law of Chang 7 Member tight oil in the western Ordos Basin based on geological, logging and numerical simulation techniques

Abstract Fine characterization of oil plane distribution in highly heterogeneous tight sandstone is a prerequisite for efficient reservoir development. This study systematically evaluated the distribution characteristics of tight oil in the Chang 7 Member of the Western Ordos Basin using a large number of experimental tests, logging interpretation, and 3D modelling methods. The logging interpretation models of shale content, porosity, permeability, and oil saturation were constructed, and the effective reservoir was identified by establishing the intersection identification pattern of reservoir acoustic wave time difference and deep lateral resistivity. The 3D numerical simulation results showed that the tight oil is distributed between injection and production wells. The areas with high tight oil content are mainly distributed along the WE direction, and a series of high remaining oil zones are formed locally. Under the influence of long-term injection and production, a high permeability zone will be formed between wells, which is similar to a high-speed channel and will be flooded quickly, and a banded remaining oil retention zone will be formed around it. For the horizontal well flooding area, the water flooding range of the water injection well is small, and a large amount of remaining oil is enriched between water injection wells. Finally, the classification standard of the remaining oil in the Chang 72 sub-member of the study area is proposed, and then, the strategy of adopting different development and adjustment schemes according to different types of reservoirs is formed.

Spatial and temporal analysis and forecasting of TB reported incidence in western China

ObjectiveTuberculosis (TB) remains an important public health concern in western China. This study aimed to explore and analyze the spatial and temporal distribution characteristics of TB reported incidence in 12 provinces and municipalities in western China and to construct the optimal models for prediction, which would provide a reference for the prevention and control of TB and the optimization of related health policies.MethodsWe collected monthly data on TB reported incidence in 12 provinces and municipalities in western China and used ArcGIS software to analyze the spatial and temporal distribution characteristics of TB reported incidence. We applied the seasonal index method for the seasonal analysis of TB reported incidence and then established the SARIMA and Holt-Winters models for TB reported incidence in 12 provinces and municipalities in western China.ResultsThe reported incidence of TB in 12 provinces and municipalities in western China showed apparent spatial clustering characteristics, and Moran’s I was greater than 0 (p < 0.05) over 8 years during the reporting period. Among them, Tibet was the hotspot for TB incidence in 12 provinces and municipalities in western China. The reported incidence of TB in 12 provinces and municipalities in western China from 2004 to 2018 showed clear seasonal characteristics, with seasonal indices greater than 100% in both the first and second quarters. The optimal models constructed for TB reported incidence in 12 provinces and municipalities in western China all passed white noise test (p > 0.05).ConclusionsAs a hotspot of reported TB incidence, Tibet should continue to strengthen government leadership and policy support, explore TB intervention strategies and causes. The optimal prediction models we developed for reported TB incidence in 12 provinces and municipalities in western China were different.

Quantifying laser irradiation-induced temperature field of particle reinforced metal matrix composites

While particle-reinforced metal matrix composites (PMMCs) are composed of particles and matrix with distinctly different thermomechanical properties, the thermal differences and coupled interactions between individual phases greatly determine the thermal characteristics of PMMCs under laser irradiation. In this work, we quantify the temperature evolution characteristics within SiCp/Al under laser irradiation by microstructural thermal finite element simulations and experimental investigation. Specifically, a 2D thermophysical FE model of laser-SiCp/Al interaction for the two-phase PMMCs material under laser irradiation is developed, which incorporates the temperature-dependent thermophysical properties of particles, matrix and interfaces, along with the considerations of the shape and distribution characteristics of particles, as well as the comprehensive thermal conditions. Furthermore, a 3D equivalent thermal FE model for experimental validation of predicted laser-induced temperature of SiCp/Al is developed, based on the derived equivalent properties. Meanwhile, an in-situ temperature measurement system is constructed for exploring temperature evolution characteristics during the on-going laser irradiation process, which validates a derivation of 1.7 % of predicted temperature by the equivalent thermal FE model. Finally, the impact of laser processing parameters on the temperature field of SiCp/Al is addressed. These findings provide valuable insights for understanding the thermal mechanisms of PMMCs under laser irradiation, and also the parameter optimization for laser processing of PMMCs.

Numerical study of gas pocket distribution and pressurization deterioration mechanism in a centrifugal pump

In the event of a loss-of-coolant accident at a nuclear power plant, a large amount of steam enters the main pump, causing the pump's pressurization to deteriorate or even fail. To reveal the deterioration mechanism of the pump performance, the gas-liquid distribution characteristics in the centrifugal pump were studied by using structured grids and the Eulerian-Eulerian model. Based on the dimensional analysis method, a predictive correlation for bubble size was established, which included factors such as inlet gas volume fraction (IGVF), rotational speed, liquid flow rate, and impeller geometric parameters. When the predictive correlation is applied to the numerical simulation, the numerical two-phase pressurization agrees well with that obtained from the experiment. As the IGVF increases, the gas begins to accumulate at the impeller inlet under the effect of the pressure gradient force. Due to the large increase in liquid velocity, the gas begins to accumulate from the middle of the diffuser flow channel. The area occupied by the gas pocket in the impeller loses its pressurization capability. The pressure vortex formed at the inlet of the channel causes the diffuser to lose its pressurization capacity. An increase in rotational speed and a decrease in liquid flow rate can effectively prevent the formation and development of gas pockets in the impeller.

Imaging endolymphatic space of the inner ear in vestibular migraine

BackgroundVestibular migraine (VM), the most frequent episodic vertigo, is difficult to distinguish from Ménière’s disease (MD) because reliable biomarkers are missing. The classical proof of MD was an endolymphatic hydrops...

Two-sided matching theory-based second-hand house transaction evaluation and recommendation by the modified PLC-DEMATEL method

To enhance the two-sided matching efficiency in a multi-source heterogeneous environment, this paper takes the randomness and unstructured features of the online comments into consideration, and proposes a new matching mechanism by introducing the complex information representation tool. Firstly, the concept of the probabilistic linguistic normal cloud (PLNC) model is introduced to preserve information cohesion and characteristic distribution. Next, the basic operation laws and corresponding operators are given. Then, an innovative maximum boundary concept skipping the indirect approach is presented to update the similarity degree and distance measures, also the correlation coefficient. Furthermore, for the multi-indicator systems with interactions, the peer experts are invited to evaluate the relationship between indicators, a modified algorithm based on the Decision-Making and Trial Evaluation Laboratory (DEMATEL) method is applied to obtain the subjective weights of indicators. After that, a whole matching process and a correlation coefficient cluster method-based recommendation algorithm are presented. A case study is provided to illustrate the method, wherein a new indicator system is constructed by analyzing the correlation of multiple indicators based on online linguistic evaluations. The random forest model is combined to obtain the objective weights and balance its reliability. Finally, sensitivity analysis and comparative analysis are employed to validate the effectiveness and applicability.

Optical beam spread in seawater

We study the spatial and angular distribution of light in a narrow stationary beam propagating in a medium like seawater. For a power-law parametrization of the seawater phase function, using radiative transfer analysis, we derive analytical expressions that determine the radiance distribution in the medium. Both the case of intermediate source–receiver distances, where absorption only begins to affect spreading of the beam, and the asymptotic regime of beam propagation are examined. For the main characteristics of the radiance distribution (the total power, the variance of the angular and radial distributions), scaling relations involving the inherent optical parameters of seawater are found. To validate the expressions obtained we carry out Monte Carlo simulation for commonly adopted seawater scattering models (of Petzold and Morel et al) and their analytical parameterizations. For optical parameters typical to seawater, the predicted analytical laws are in excellent agreement with the results of the Monte Carlo computations.

Disaster mechanism of large-diameter shield tunnel segments under multi-source load coupling: A case study

The deflection squeezing of the shield shell and the eccentric jack thrust significantly impact the segment dislocation and damage. Based on summarizing the derivative relationship between engineering factors and disasters, this study established a 3D numerical calculation model under the multi-source load coupling. Then, this study explored the displacement and dislocation distribution of segments, as well as their derivative relationship with bolt failure. Furthermore, this study analyzed the spatial distribution and evolution characteristics of segment damage. Further revealing the disaster mechanism and proposing the engineering treatment measures. The research results indicate that as the deflection angle increases, the vertical relative compression deformation of the segment that is detaching from the shield tail (segment-DFST) becomes more significant. The plastic strain of the internal bolts inside the two segments in direct contact with the shield shell is mainly related to the radial and longitudinal dislocation. The increase in the deflection angle will lead to a more significant increase in the adjacent dislocation on both sides and the internal dislocation. The plastic strain of the internal bolts of the segment that is completely in the shield shell (segment-CSS) is more influenced by joint opening and longitudinal dislocation under the lower eccentric compression (LEC) state. The plastic strain of the internal bolts in segment-DFST is more influenced by radial dislocation and joint opening under the LEC state. The tension damage of the segments mainly occurs on both sides of the circumferential joint and the lower part of the segment-CSS. The compression damage of the segments is mainly distributed at the top and bottom of the segment-CSS. The eccentric distribution of jack thrust has the most significant impact on the block damage of the lower part of the segment-CSS. With the increase of the deflection angle, the compression damage and distribution range of the blocks at the bottom of the segment-DFST increase sharply. The compression damage and distribution range of the segment-CSS gradually spread from the upper and lower parts to the middle of the segment. The increase in deflection angle will promote the influence of the thrust in LEC state on the compression damage of the lower block of the segment-CSS, and on the tension damage of the upper block of the segment- DFST.

Exploration of Geographical Environmental Factors Influencing Regional Population Mortality Patterns inChina.

The regional population mortality patterns in China exhibit substantial geographical distribution characteristics. This paper aims to explore the impact and mechanisms of geographical environmental factors on regional population mortality patterns. This study first utilized the data from China's Seventh Population Census to obtain mortality patterns for the 31 provincial-level administrative regions. Subsequently, a functional regression method was employed to explore the geographical environmental driving factors of regional mortality patterns. The study provides a detailed explanation of the mechanisms and marginal contributions of key geographical environmental factors at different age groups. (1) The impact of geographical environmental factors on mortality patterns shows distinct phased characteristics. Mortality patterns before the age of 40 years are hardly influenced by geographical environmental factors, with a noticeable impact beginning at ages 40-69 years and reaching the maximum influence after the age of 70 years. (2) In mortality patterns at ages 40-69 years, average altitude have the most substantial impact, followed by extreme low-temperature days and PM2.5 concentration. In mortality patterns at ages 70-94 years, high-temperature days have the greatest influence, followed by the impact of SO2 concentration. (3) In comparisons based on gender, socioeconomic factors, and geographical environmental factors, gender and urban-rural differences have the most significant impact on regional population mortality patterns, followed by the influence of other socioeconomic factors, with geographical environmental factors having a relatively smaller impact.