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Article
Publication date: 21 August 2017

Liang Liu, Bin Chen, Wangchun Jiang, Lingnan He and Xiaogang Qiu

WeChat is the largest acquaintance social networking platform in China, in which users can view and reshare web pages shared by friends. This paper aims to analyze the…

Abstract

Purpose

WeChat is the largest acquaintance social networking platform in China, in which users can view and reshare web pages shared by friends. This paper aims to analyze the spatio-temporal dynamics of web pages diffused in WeChat and advice on commercials.

Design/methodology/approach

A large number of web pages diffused in WeChat are collected and exclusively divided into four categories according to their titles, including advertisements, news bulletins, holiday greetings and emotional essays. For each web page, an information cascade (tree structure) is constructed to describe the diffusion trace. Based on the categories, the spatio-temporal popularity is characterized; the topological, temporal and spatial properties are examined; and the spatio-temporal diffusion velocity is explored.

Findings

Through comparative analysis, different categories of pages show diversity. For spatio-temporal popularity, there is no significant difference in cascade size; holiday greetings usually last for a relatively short time on average; emotional essays are more likely to spread to more provinces. For topological, temporal and spatial characteristics, the diffusion process of advertisements is more likely to be broadcasting than other categories; news bulletins and holiday greetings have an obvious bursty; the number of viewing behavior decreases from east to west in general. For spatio-temporal diffusion velocity, emotional essays diffuse the fastest in topological and spatio-temporal dimensions.

Originality/value

These findings contribute to promoting products and providing support for data driven modeling of information diffusion and human activity in spatio-temporal dimensions.

Details

Information Discovery and Delivery, vol. 45 no. 3
Type: Research Article
ISSN: 2398-6247

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Book part
Publication date: 18 January 2022

Arnab Bhattacharjee, Jan Ditzen and Sean Holly

The authors provide a way to represent spatial and temporal equilibria in terms of error correction models in a panel setting. This requires potentially two different…

Abstract

The authors provide a way to represent spatial and temporal equilibria in terms of error correction models in a panel setting. This requires potentially two different processes for spatial or network dynamics, both of which can be expressed in terms of spatial weights matrices. The first captures strong cross-sectional dependence, so that a spatial difference, suitably defined, is weakly cross-section dependent (granular) but can be non-stationary. The second is a conventional weights matrix that captures short-run spatio-temporal dynamics as stationary and granular processes. In large samples, cross-section averages serve the first purpose and the authors propose the mean group, common correlated effects estimator together with multiple testing of cross-correlations to provide the short-run spatial weights. The authors apply this model to the 324 local authorities of England, and show that our approach is useful for modeling weak and strong cross-section dependence, together with partial adjustments to two long-run equilibrium relationships and short-run spatio-temporal dynamics. This exercise provides new insights on the (spatial) long-run relationship between house prices and income in the UK.

Details

Essays in Honor of M. Hashem Pesaran: Panel Modeling, Micro Applications, and Econometric Methodology
Type: Book
ISBN: 978-1-80262-065-8

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Article
Publication date: 15 October 2019

Zhenzhen Zhao and Jiandi Feng

The purpose of this paper is to analyze the characteristics of spatio-temporal dynamics and the evolution of land use change is essential for understanding and assessing…

Abstract

Purpose

The purpose of this paper is to analyze the characteristics of spatio-temporal dynamics and the evolution of land use change is essential for understanding and assessing the status and transition of ecosystems. Such analysis, when applied to Horqin sandy land, can also provide basic information for appropriate decision-making.

Design/methodology/approach

By integrating long time series Landsat imageries and geographic information system (GIS) technology, this paper explored the spatio-temporal dynamics and evolution-induced land use change of the largest sandy land in China from 1983 to 2016. Accurate and consistent land use information and land use change information was first extracted by using the maximum likelihood classifier and the post-classification change detection method, respectively. The spatio-temporal dynamics and evolution were then analyzed using three kinds of index models: the dynamic degree model to analyze the change of regional land resources, the dynamic change transfer matrix and flow direction rate to analyze the change direction, and the barycenter transfer model to analyze the spatial pattern of land use change.

Findings

The results indicated that land use in Horqin sandy land during the study period changed dramatically. Vegetation and sandy land showed fluctuating changes, cropland and construction land steadily increased, water body decreased continuously, and the spatial distribution patterns of land use were generally unbalanced. Vegetation, sandy land and cropland were transferred frequently. The amount of vegetation loss was the largest. Water body loss was 473.6 km2, which accounted for 41.7 per cent of the total water body. The loss amount of construction land was only 1.0 km2. Considerable differences were noted in the rate of gravity center migration among the land use types in different periods, and the overall rate of construction land migration was the smallest. Moreover, the gravity center migration rates of the water body and sandy land were relatively high and were related to the fragile ecological environment of Horqin sandy land.

Originality/value

The results not only confirmed the applicability and effectiveness of the combined method of remote sensing and GIS technology but also revealed notable spatio-temporal dynamics and evolution-induced land use change throughout the different time periods (1983-1990, 1990-2000, 2000-2010, 2010-2014, 2014-2016 and 1983-2016).

Details

Sensor Review, vol. 39 no. 6
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 18 April 2016

Valery Gitis, Alexander Derendyaev and Arkady Weinstock

This paper aims to describe two Web-based technologies of geographic information systems (GIS) to be used in monitoring and analysis of environmental processes, proposed…

Abstract

Purpose

This paper aims to describe two Web-based technologies of geographic information systems (GIS) to be used in monitoring and analysis of environmental processes, proposed by the authors. The technologies analyze the temporal aspect of the process together with the spatial aspect, which defers them from most other works on environmental processes, as these are usually limited either to spatial statistics or to temporal statistics. The approach is instrumental in dynamically finding the relationships between the processes and predicting critical incidents.

Design/methodology/approach

Often, the study of natural processes is limited to the analysis of their spatial properties presented by individual time series. The principal idea of this approach consists in supplementing this traditional analysis with the analysis of time fields. In this way, the authors are able to analyze temporal and spatial properties of environmental processes together.

Findings

The paper presents two technologies which provide the analysis of spatial and temporal data obtained in natural environment monitoring. The discussed spatio-temporal data mining methods are shown to enable the research into environmental processes, and the solution of practical issues of critical situation forecasts.

Originality/value

The paper discussed Web-based GIS technologies for the analysis of the temporal aspect of the environmental process together with the spatial aspect. Application examples demonstrate the ability of this approach to find the relationships in dynamics of the processes and to predict critical incidents.

Details

International Journal of Web Information Systems, vol. 12 no. 1
Type: Research Article
ISSN: 1744-0084

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Article
Publication date: 10 July 2019

Abbas Ghasemi and Xianguo Li

This study aims to investigate the cross-sectional reshaping in transitioning/starting rectangular jets of aspect ratio 2 under various inlet perturbation conditions at…

Abstract

Purpose

This study aims to investigate the cross-sectional reshaping in transitioning/starting rectangular jets of aspect ratio 2 under various inlet perturbation conditions at the Reynolds number of Re = UDh/v = 17,750.

Design/methodology/approach

Large eddy simulation results compared with the phase-locked particle image velocimetry data exhibit the cross-sectional jet deformations from rectangular to rounder shapes. Inflow velocity oscillations are introduced at the fundamental frequency associated with the Kelvin–Helmholtz instability characterized by the spectral analysis of the hotwire data and the linear stability predictions.

Findings

The initially rectangular cross-section of the jet reshapes into the rounder geometries with increased downstream distance while the edges of the jet become distorted due to the shear layer instability more significantly observed near the high curvature corners. The different expansion rates in the longer and shorter edges of the jet and the consequent cross-sectional reshaping are found to be sensitive to small levels of random inlet perturbations. In addition, introducing controlled sinusoidal oscillations results in the formation of more organized trailing shear layer where the stronger vortex rings go through the curvature-induced deformations.

Originality/value

Spatio-temporal study of vortex dynamics in transitioning rectangular jets reveals important information about the effect of the controlled jet forcing on local entrainment. Dynamics of the leading vortex dominates the entrainment in transitioning jets which are commonly used in practical applications. Near-field entrainment is also promoted proportional to the amplitude of the controlled inlet oscillations within the trailing vortex rings.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 7
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 10 September 2018

Prem Chhetri, Jonathan Corcoran, Shafiq Ahmad and Kiran KC

The purpose of this paper is twofold: first is to examine the changing spatio-temporal patterns and regional trends in residential fires; and second is to investigate the…

Abstract

Purpose

The purpose of this paper is twofold: first is to examine the changing spatio-temporal patterns and regional trends in residential fires; and second is to investigate the likely association of fire risk with seasons, calendar events and socio-economic disadvantage.

Design/methodology/approach

Using spatial analytic and predictive techniques, 11 years of fire incident data supplied by the Queensland Fire and Emergency Services are mapped and analysed.

Findings

The results show significant spatial and temporal variability in the distribution of residential fires. Residential fire incidents are more likely to occur in the inner city and across more disadvantaged areas. Mapped outputs show some areas in Brisbane at a higher risk of fire than others and that the risk of fire escalates at specific times of the year, in neighbourhoods with a higher disadvantage, during major sporting events and school holidays. The residential fires showed strong seasonal periodicity. There is a continuous yet gradual increase in the number of fire incidents recorded for all five sub-regions within SEQ. Sunshine Coast experienced the highest upward trend whereas Toowoomba and West Moreton show the lowest increase.

Originality/value

This study provides an empirical basis to guide future operational strategies through targeting high fire risk areas at particular times. This, in turn, will help utilise finite resources in areas where and when they need and thus enable minimise emergency management costs.

Details

Disaster Prevention and Management: An International Journal, vol. 27 no. 5
Type: Research Article
ISSN: 0965-3562

Keywords

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Book part
Publication date: 22 September 2015

Sébastien Rioux

Recent decades have witnessed great interest in Leon Trotsky’s idea of uneven and combined development (UCD) by Marxist scholars of International Relations (IR). A…

Abstract

Recent decades have witnessed great interest in Leon Trotsky’s idea of uneven and combined development (UCD) by Marxist scholars of International Relations (IR). A burgeoning literature has argued that one interpretation, Justin Rosenberg’s U&CD, resolves the question of ‘the international’ by offering a single, non-Realist theory capable of uniting both sociological and geopolitical factors in the explanation of social change across history. Evaluating this claim, this paper argues that the transhistorical ways in which U&CD has been developed reproduce, reaffirm and reinforce some of the more important shortcomings of Realist IR. I develop my argument through an internal critique of Rosenberg’s conception of U&CD, which, I argue, is illustrative of larger shortcomings within the literature. I conclude that the political and geopolitical economy of UCD and their dynamics must be grasped through the specific social and historical relations in which they are immersed.

Details

Theoretical Engagements in Geopolitical Economy
Type: Book
ISBN: 978-1-78560-295-5

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Article
Publication date: 6 July 2020

Mengsi Cai, Ge Huang, Yuejin Tan, Jiang Jiang, Zhongbao Zhou and Xin Lu

With the development of global food markets, the structural properties of supply chain networks have become key factors affecting the ability to evaluate and control…

Abstract

Purpose

With the development of global food markets, the structural properties of supply chain networks have become key factors affecting the ability to evaluate and control infectious diseases and food contamination. The purpose of this paper is to describe and characterize the nationwide pork supply chain networks (PSCNs) in China and to demonstrate the potential of using social network analysis (SNA) methods for accessing outbreaks of diseases and contaminations.

Design/methodology/approach

A large-scale PSCN with 17,582 nodes and 49,554 edges is constructed, using the pork trade data collected by the National Important Products Traceability System (NIPTS) in China. A network analysis is applied to investigate the static and dynamic characteristics of the annual network and monthly networks. Then, the metric maximum spreading capacity (MSC) is proposed to quantify the spreading capacity of farms and estimate the potential maximum epidemic size. The structure of the network with the spatio-temporal pattern of the African swine fever (ASF) outbreak in China in 2018 was also analysed.

Findings

The results indicate that the out-degree distribution of farms approximately followed a power law. The pork supply market in China was active during April to July and December to January. The MSC is capable of estimating the potential maximum epidemic size of an outbreak, and the spreading of ASF was positively correlated with the effective distance from the origin city infected by ASF, rather than the geographical distance.

Originality/value

Empirical research on PSCNs in China is scarce due to the lack of comprehensive supply chain data. This study fills this gap by systematically examining the nationwide PSCN of China with large-scale reliable empirical data. The usage of MSC and effective distance can inform the implementation of risk-based control programmes for diseases and contaminations on PSCNs.

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Article
Publication date: 10 December 2019

Eric Goncalves Da Silva and Philippe Parnaudeau

The purpose of this paper is to quantify the relative importance of the multiphase model for the simulation of a gas bubble impacted by a normal shock wave in water. Both…

Abstract

Purpose

The purpose of this paper is to quantify the relative importance of the multiphase model for the simulation of a gas bubble impacted by a normal shock wave in water. Both the free-field case and the collapse near a wall are investigated. Simulations are performed on both two- and three-dimensional configurations. The main phenomena involved in the bubble collapse are illustrated. A focus on the maximum pressure reached during the collapse is proposed.

Design/methodology/approach

Simulations are performed using an inviscid compressible homogeneous solver based on different systems of equations. It consists in solving different mixture or phasic conservation laws and a transport-equation for the gas volume fraction. Three-dimensional configurations are considered for which an efficient massively parallel strategy was developed. The code is based on a finite volume discretization for which numerical fluxes are computed with a Harten, Lax, Van Leer, Contact (HLLC) scheme.

Findings

The comparison of three multiphase models is proposed. It is shown that a simple four-equation model is well-suited to simulate such strong shock-bubble interaction. The three-dimensional collapse near a wall is investigated. It is shown that the intensity of pressure peaks on the wall is drastically increased (more than 200 per cent) in comparison with the cylindrical case.

Research limitations/implications

The study of bubble collapse is a key point to understand the physical mechanism involved in cavitation erosion. The bubble collapse close to the wall has been addressed as the fundamental mechanism producing damage. Its general behavior is characterized by the formation of a water jet that penetrates through the bubble and the generation of a blast wave during the induced collapse. Both the jet and the blast wave are possible damaging mechanisms. However, the high-speed dynamics, the small spatio-temporal scales and the complicated physics involved in these processes make any theoretical and experimental approach a challenge.

Practical implications

Cavitation erosion is a major problem for hydraulic and marine applications. It is a limiting point for the conception and design of such components.

Originality/value

Such a comparison of multiphase models in the case of a strong shock-induced bubble collapse is clearly original. Usually models are tested separately leading to a large dispersion of results. Moreover, simulations of a three-dimensional bubble collapse are scarce in the literature using such fine grids.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 22 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 5 July 2019

Mirjana Pejic Bach, Emil Tustanovski, Andrew W.H. Ip, Kai-Leung Yung and Vasja Roblek

System dynamics is a whole-system modelling and learning approach, useful for tackling non-linear problems, such as sustainable urban development. The purpose of this…

Abstract

Purpose

System dynamics is a whole-system modelling and learning approach, useful for tackling non-linear problems, such as sustainable urban development. The purpose of this paper is to review system dynamics applications in the simulation of sustainable urban development over a period from 2005 to 2017.

Design/methodology/approach

The analysis reveals that the number of applications of system dynamics modelling in the area of urban sustainable development increased in the analysed period. Research has changed its focus from the modelling of environmental problems to more complex models, portraying the multidimensional socio-economic processes that have an impact on the sustainability of urban development. Analysed case studies most often use the behaviour reproduction test for model validation, but without a unified approach. In most cases, modelling has been done in China, Germany and the USA, while urban development in the Eastern European countries, Africa and Latin America has not often been investigated. This paper indicates the knowledge gaps and suggests future research directions.

Findings

Papers that report the use of system dynamics modelling reveal a wide range of applications in urban sustainability. The analysis shows significant emphasis on environmental problems, while the interest for modelling social problems has been increasing during the last several years. Most of the modelled problems examine the sustainability of resources (land, water) and waste management, which are used for insights into the reasons for the system behaviour, forecasting future behaviour and policy testing.

Originality/value

The presented models were developed in most cases for the purpose of understanding the phenomena examined, as well as the future use of the models in policy planning. This brings us back to the need for greater stakeholder involvement, not only in the initial phase, but also during the whole modelling process, which could increase understanding, use and ownership of the models in the future, and thus increase their practical application.

Details

Kybernetes, vol. 49 no. 2
Type: Research Article
ISSN: 0368-492X

Keywords

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