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The variation principle widely used in structural dynamics analysis allows us to transform the differential equation of the boundary value problem into a functional with extreme value. In recent years, it has been applied to the band-gap analysis of periodic structures. However, for periodic beam-plate composite structures with periodic and ordinary boundaries, it is relatively difficult for the traditional energy methods, such as the Rayleigh–Ritz method, to construct the displacement functions that satisfy boundary conditions. Hence, a hybrid solution is proposed in this paper to account for various boundary conditions of the periodic beam-plate composite structure. Specifically, the displacement functions constructed by the plane wave series can automatically satisfy the periodic boundary conditions. With the ordinary boundaries modeled by artificial springs, the spectral functions conforming to arbitrary boundary conditions are used to represent the displacement functions. The proposed solution is used to solve the band-gap problems of CRTS-III and CRTS-II slab ballastless tracks in China, and the accuracy of the solution is verified by comparing the calculated results with numerical simulations. In addition, through band-gap formation mechanism analysis, the frequency range of propagating flexural waves in each track component is accurately evaluated, which provides a theoretical basis for refined structural vibration reduction in the future. The solution proposed in this paper is flexible and convenient, which can be extended to a more complex band-gap analysis of periodic structures. [ABSTRACT FROM AUTHOR]

Zhao, J.; Wang, D., and Gu, H., 2015. Numerical simulation of dual laterolog in cavernous carbonatite reservoir. The cavernous reservoir has become one of the main carbonate reservoirs for stable and increasing production. The degrees and the types of fillings materials are the key factors which affect the characteristics of accumulation and flowage. However, due to the complexity of fillings in the caves, the response laws of logging of the cavernous reservoir can not be understood clearly and its effective evaluation has been severely hampered. This paper uses for the first time numerical simulation to study the responses in the curve of dual lateral log of cavernous reservoir. By establishing a continuous equation of the dual lateral log and its boundary factors and using the electric field superimpose principle, a finite element method is used to study the cave size, different filling agents and degrees are simulated. The result indicates that the size, filling agents and degrees show a clear response, and they have a clear correspondence. Summarizing and analyzing the response laws on the dual lateral logging curves of the cavernous reservoir can provide theoretical evidence for the logging evaluation of the carbonate cavernous reservoir. [ABSTRACT FROM AUTHOR]

In this paper, an actual landslide process that occurred in Southern China is simulated by a continuum approach, the particle finite element method (PFEM). The PFEM attempts to solve the boundary-value problems in the framework of solid mechanics, satisfying the governing equations including momentum conservation, displacement-strain relation, constitutive relation as well as the frictional contact between the sliding mass and the slip surface. To warrant the convergence behaviour of solutions, the problem is formulated as a mathematical programming problem, while the particle finite element procedure is employed to tackle the issues of mesh distortion and free-surface evolution. The whole procedure of the landslide, from initiation, sliding to deposition, is successfully reproduced by the continuum approach. It is shown that the density of the mass has little influence on the sliding process in the current landslide, whereas both the geometry and the roughness of the slip surface play important roles. Comparative studies are also conducted where a satisfactory agreement is obtained. [ABSTRACT FROM AUTHOR]

This paper describes the performance of the Regional Atmospheric Modeling System (RAMS) in simulating a winter drought event, based on two different forcing datasets. We ran EC (ERA-Interim reanalysis data as initial and lateral boundary forcing conditions) and FNL (NCEP-FNL reanalysis data) simulations for the 2008/2009 winter drought event to quantify the impact of any uncertainty in the different initial and lateral boundary forcing data on regional model outputs. The response of the winter mean atmospheric states to the variations in the initial and lateral boundary conditions was investigated on the basis of these simulation results. The spatio-temporal features of precipitation from the EC and FNL runs closely resembled those measured from the Global Summary Of the Day (GSOD) observations, although the EC run data outperformed the FNL run data in both their spatial distribution patterns and precipitation values. The water vapor flux values explain how the differences in the precipitation values between the EC and the FNL runs were generated, whereas temperature values were not sensitive to any changes in forcing data. The model results from these runs also slightly overestimated temperature on both spatial and temporal scales. For the tropospheric atmospheric data recorded at the Fuyang Meteorological Station in Anhui Province, neither the time series nor the statistical analyses showed any evidence of superiority between the two different driver datasets compared with radiosonde data. However, on closer inspection, the influence of different initial and lateral boundary conditions on modeling the tropospheric atmospheric data appeared to be evident. [ABSTRACT FROM AUTHOR]

With rapid development of China's economics, the regional industrial transfer behavior becomes more active. Different from international industrial transfer, the main body of China's regional industrial transfer also includes government participation not just enterprise. As such, this paper discusses the evolutionary mechanism of regional industrial transfer in Chinese context, based on sustainable development under the transformation of industry upgrading. This paper first extended a basic dynamic evolutionary game model of regional industrial transfer behavior and analysis the evolutionarily stable strategies, then further developed an evolutionary game model considering the government's incentives, numerical examples and simulation also provided evidence to theoretical results. The results show that the evolutionary stable strategies are affected by the initial input costs, excess profits and the ratio of profit distribution. Moreover, the system will evolve to different equilibriums under different boundary conditions. Furthermore, more effective incentive mechanism of government can increase the probability of the implementation of regional industrial transfer. [ABSTRACT FROM AUTHOR]

This paper presents a numerical modeling study of tidal effects on groundwater dynamics of a multi-layered estuary aquifer system. In this study, to generalize the tidal loading effects on the confined aquifer, we used equivalent tidal loading boundary condition based on existing analytical solutions for the confined aquifer in a three-dimensional numerical model and then good simulated result was obtained. Using the numerical model, the tide-induced groundwater level and confined groundwater discharge dynamics were discussed and the following conclusions were obtained. The combined action of sea tide and river tide can enhance the tidal response of groundwater level in the aquifer system, especially for the confined groundwater. The river tidal effect is more significant in the areas away from coastline. Although the confined aquifer is separated by a layer of clay from the ocean, because of the tidal loading effects, the confined groundwater discharge also changes periodically displaying a negative correlation with the tide level fluctuations like the unconfined groundwater discharge. Using linear functions that express the relationship between the mean confined groundwater flux and sea tide level, the confined groundwater flux through the tidal loading boundaries can be approximately estimated. When the sea tide level is higher than 4.4 m, there would be a risk of seawater intrusion into the confined aquifer in the study area. This case study is useful for numerical studying of tidal effects on groundwater resource dynamics in a coastal multi-layered estuary aquifer system. [ABSTRACT FROM AUTHOR]

Catastrophic landslides and flowslides usually occur at large waste dumps. Compared to normal slopes, waste dumps have unique topographical conditions and material properties that cause considerable challenges associated with hazard prediction and mitigation. This paper describes one of the largest and highest waste dumps in China, the Zhujiabaobao waste dump, which covers an area of 4 km2 and has a volume of 30,000 × 104 m3 mine waste. A field investigation in April 2016 indicated that the waste dump was unstable. To assess the stability of the slope and predict its hazard scale, the authors use a 3D slope model based on a discrete element method to achieve it. The model is first constructed based on field investigations, including reconnaissance, as well as geomorphological analysis and laboratory experiments. Then, the strength reduction technique is used to calculate the safety factor of a slope. The results show that the safety factor of the slope is 2.3, and compared to the normal limit equilibrium method, the safety factor calculated by the DEM simulation is more accurate and approximately about 15% larger, because it considers more realistic boundary conditions and material properties. During the calculation of the safety factor, the corresponding run-out process can be presented as well. The simulation shows that sliding masses at different parts have different mobility performances, which the upper and front particles presenting the potential to move farther and faster during the run-out process due to force conditions. Additionally, the proposed method shows that topography is a crucial factor for mass movement that requires special attention for the prevention and prediction of landslide hazards. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates numerical method for predicting wind field and pollutant dispersion in an urban area with crowded buildings and heavy traffic. Large eddy simulation is employed in numerical computation with Lagrangian dynamic model to close the subgrid scale stress. The fine grids are required in numerical simulation of micro-atmospheric flows in an urban area with crowded and complex building-streets. To realize the numerical simulation on available computer resources a domain decomposition method and a combined model for the building-street layout are proposed that the computed domain of an urban area is decomposed into a central area, where the pollution is the major concern and a surrounding region where the pollutant distribution is not concerned. The combined flow model is proposed for the complex building-street layout that the fine grid mesh and exact flow boundary conditions are prescribed in the central area while the buildings are treated as roughness elements in the surrounding region where the coarse grids are used. The proposed numerical method is applied to simulate the wind field and pollutant dispersion from vehicle exhaust in the Rua Do Campo area of Macau (referred to the site hereafter). The wind speed and temperature fields are computed from 7 am on September 6 2005 to 7 am of the next day and the pollutant concentration field is computed from 7 am to 6 pm on September 6 2005. The results show fairly good agreement with the field observation. The wind field and pollutant concentration distribution are demonstrated in the site by proposed combined model and they are compared with those computed by drag element model in whole computational domain. The results show that the combined model is an appropriate method for predicting wind field and pollutant dispersion in the crowded building area. The paper also reveals the relevance of buoyancy effect in the prediction of urban atmospheric environment. [Copyright &y& Elsevier]

When using the finite element method to analyze seismic soil-structure interaction (SSI) problem on rigid bedrock, several methods have been developed to input earthquake on the lateral boundary of finite element model. These boundary conditions include the free boundary, the viscous-spring (VS) boundary, the tied degrees of freedom (TDOF) boundary and the free-field loading combined viscous-spring (FFL-VS) boundary. Their accuracy and location should be investigated. In this paper, the formulations and ABAQUS implementations of these boundaries are given. The accuracy properties of these boundaries are then compared by numerical examples including the free-field and SSI problems. The comparison studies indicate that the free and VS boundaries failed to reproduce the free-field and SSI responses when a relatively small size SSI model is employed. The TDOF and FFL-VS boundaries can simulate the exact free-field response and have good performances in seismic SSI analyses. The FFL-VS boundary is more accurate than the TDOF boundary. The appropriate locations for the TDOF and FFL-VS boundaries depend on the SSI model. A simplified approach is developed for appropriate boundary location. This approach is applicable to the FFL-VS boundary but not to the TDOF boundary due to the former more accurate than the latter. [ABSTRACT FROM AUTHOR]

This paper quantitatively investigates groundwater-seawater interactions and explores the annual variations and spatial distributions in submarine groundwater discharge (SGD) and seawater intrusion (SWI) in the Bohai Sea coastal zone in Tianjin, China. A three-dimensional finite element model, FEMWATER in the GMS environment, is developed to simulate density-dependent flow and transport in coastal groundwater aquifers. A sensitivity analysis is used to explore how the model output varies with the hydrogeological parameters and boundary conditions. The results suggest that both SGD and SWI occur across the sea-aquifer interface. Along the modeled 45 km stretch of coastline, the annual SGD and SWI rates are 4.23 × 10 7 m 3 /yr and 0.86 × 10 7 m 3 /yr, respectively. The results also indicate that SGD is highest in the winter and lowest in the summer, and SWI exhibits the opposite trend. This change in flow direction across the sea-aquifer interface corresponds to seasonal changes in sea level. SGD mainly occurs in the southern and northern parts of the study area, and SWI primarily occurs in the central part. The results of the sensitivity analysis suggest that the SGD and SWI model outputs are most sensitive to sea level and the hydraulic conductivity in the top layer. [ABSTRACT FROM AUTHOR]

This paper presents an algorithm for the estimation of open boundary conditions (OBCs) which force tides in the interior region by an adjoint data assimilation approach. Assuming that OBCs are position dependent, OBCs can be approximated by linear interpolation among values at certain independent points (IPs). Twin experiments are performed to examine the sensitivity of the model to the IP distribution and interpolation radius. It is proved that the prescribed OBCs can be well recovered with appropriate number of IP and interpolation radius. In the Bohai Sea model domain with horizontal resolution of 10'x10', the appropriate number of IP is 3 and the interpolation radius is 60'. In the practical experiment, the M2 constituent in the Bohai Sea is simulated by assimilating the T/P data and tidal gauge data. The mean absolute errors in amplitude and phase are 5.0 cm and 5.7°, respectively, and the cochart obtained shows the character of M2 constituent in the Bohai Sea. [ABSTRACT FROM AUTHOR]

Abstract: Greening is a useful mitigation strategy for planners mainly from a visual perspective. For high-density urban living environment such as Hong Kong, urban greening helps cooling the air and providing shade; it also helps lowering building energy consumption by providing a better outdoor boundary condition. Many researchers have also suggested that greening may be employed as a strategy for combating the ill effects of urban Heat Island (UHI). Working towards a set of better greening guidelines for urban planners, the current paper first provides a comprehensive review of planning with urban greening. It then describes parametric studies that have been conducted to investigate the preferred location, amount, and types of vegetation for urban planning. The parametric studies employed the numerical model ENVI-met, verified using field measurements, to simulate 33 cases with different combinations of factors. For benefiting urban activities, ambient air temperatures at the pedestrian level are compared among different greening strategies and building heights. For a city such as Hong Kong, which has a high building-height-to-street-width (H/W) ratio, the present study reveals that roof greening is ineffective for human thermal comfort near the ground. Trees are also suggested to be more effective than grass surfaces in cooling pedestrian areas. The amount of tree planting needed to lower pedestrians level air temperature by around 1°C is approximately 33% of the urban area. The present study allows urban planners to identify more precisely the greening principles, amount and policies necessary for better urban living environment in high-density cities. [Copyright &y& Elsevier]

Purpose – This study aimed to examine the boundary conditions under which teaching‌‌–research conflict influences university teachers'‌‌‌ job burnout. Methods – Data from 487 teachers of three universities in China were analyzed with structural equation modeling and other statistical approaches.‌ Findings – (a) Teaching–research conflict was positively linked to job burnout; (b)‌‌ perceived supervisory support (PSS) moderated the effect of teaching–‌research conflict on job burnout, and (c) psychological capital (PsyCap) moderated the effect of teaching–research conflict on job burnout. Implications – Universities should manage to increase teachers' PSS and PsyCap so as to buffer the effect of role conflict on job burnout. Originality/value –‌‌‌ Our findings stress the importance of PSS and PsyCap as important external and internal resources and offer new insights on the boundary conditions of teaching–research conflict influencing teachers' job burnout. [ABSTRACT FROM AUTHOR]

Given that in order to predict the economic growth of a country, the dynamics of its GDP should be considered, and the forecast itself should be made taking into account the difference between actual and estimated figures, the article discusses the problems of GDP management and its optimal distribution. The use of averages to determine economic parameters is also analyzed. The correspondence of the regression formula and the Cauchy boundary value problem is considered. The problem of managing the GDP components to obtain the necessary characteristics of GDP growth is solved using Pontryagin Maximum Principle. As an example, several options of the optimal GDP distribution (constant prices, national currency) for China in 2016-2020 are considered. Numerical results are reported and adjusted for the discount factor. Based on the calculations, it is shown that in 2017-2018, GDP increases and in 2019-2020 it decreases. [ABSTRACT FROM AUTHOR]

Two-dimensional tidal open boundary conditions of the M constituent in the Bohai and Yellow Seas (BYS) have been estimated by assimilating T/P altimeter data. During inversion, independent point (IP) strategy was used, in which several IPs on the open boundary is assumed, values at these IPs can be optimized with an adjoint method, and those at other grid points are determined by linearly interpolating the values at IPs. The reasonability and feasibility of the model are tested by ideal twin experiments. In the practical experiment (PE) after assimilation, the cost function may reach 1% or less of its initial value. Mean absolute errors in amplitude and phase can be less than 5 cm and 5°, respectively, and the obtained co-chart can show the character of the M constituent in the BYS. The results of the PE indicate that using only two IPs on the open boundary can yield better simulated results. [ABSTRACT FROM AUTHOR]

A high-resolution hybrid data assimilative (DA) modeling system is adapted to study the M barotropic tidal characteristics and dynamics in the Bohai and Yellow Seas. In situ data include tidal harmonics extracted from both coastal sea level and bottom pressure observations. The hybrid DA system consists of both forward and inverse models. The former is three-dimensional, finite-difference, nonlinear Regional Ocean Modeling System (ROMS). The latter is a three-dimensional, linearized, frequency-domain, finite-element model TRUXTON. The DA system assimilates in situ observations via the inversion of the barotropic tidal open boundary conditions (OBCs). Model skill is evaluated by comparing misfits between the observed and modeled tidal harmonics. The assimilation scheme is found effective and efficient in correcting the tidal OBCs, which in turn improves ROMS tidal solutions. Up to 50% reduction of model/data misfits is achieved after data assimilation. M co-tidal maps constructed from the posterior (data assimilative) ROMS solutions agree well with observational analysis of (Fang et al. ). Detailed analyses on tidal mixing, residual current, energy flux, dissipation, and momentum term balance dynamics are performed for M constituent, revealing complex M tidal characteristics in the study region and the important role of coastal geometry and topography in affecting regional tidal dynamics. [ABSTRACT FROM AUTHOR]

The Beijing 2008 Olympics Research and Development Project (B08RDP), initiated in 2004 under the World Meteorological Organization (WMO) World Weather Research Programme (WWRP), undertook the research and development of mesoscale ensemble prediction systems (MEPSs) and their application to weather forecast support during the Beijing Olympic Games. Six MEPSs from six countries, representing the state-of-the-art regional EPSs with near-real-time capabilities and emphasizing on the 6-36-h forecast lead times, participated in the project. The background, objectives, and implementation of B08RDP, as well as the six MEPSs, are reviewed. The accomplishments are summarized, which include 1) providing value-added service to the Olympic Games, 2) advancing MEPS-related research, 3) accelerating the transition from research to operations, and 4) training forecasters in utilizing forecast uncertainty products. The B08RDP has fulfilled its research (MEPS development) and demonstration (value-added service) purposes. The research conducted covers the areas of verification, examining the value of MEPS relative to other numerical weather prediction (NWP) systems, combining multimodel or multicenter ensembles, bias correction, ensemble perturbations [[initial condition (IC), lateral boundary condition (LBC), land surface IC, and model physics]], downscaling, forecast applications, data assimilation, and storm-scale ensemble modeling. Seven scientific issues important to MEPS have been identified. It is recognized that the daily use of forecast uncertainty information by forecasters remains a challenge. Development of forecaster-friendly products and training activities should be a long-term effort and needs to be continuously enhanced. The B08RDP dataset is also a valuable asset to the research community. The experience gained in international collaboration, organization, and implementation of a multination regional EPS for a common goal and to address common scientific issues can be shared by the ongoing projects The Observing System Research and Predictability Experiment (THORPEX) Interactive Grand Global Ensemble-Limited Area Models (TIGGE-LAM) and North American Ensemble Forecast System-Limited Area Models (NAEFS-LAM). [ABSTRACT FROM AUTHOR]

A single-model, short-range, ensemble forecasting system (Institute of Atmospheric Physics, Regional Ensemble Forecast System, IAP REFS) with 15-km grid spacing, configured with multiple initial conditions, multiple lateral boundary conditions, and multiple physics parameterizations with 11 ensemble members, was developed using the Weather and Research Forecasting Model Advanced Research modeling system for prediction of stratiform precipitation events in northern China. This is the first part of a broader research project to develop a novel cloud-seeding operational system in a probabilistic framework. The ensemble perturbations were extracted from selected members of the National Center for Environmental Prediction Global Ensemble Forecasting System (NCEP GEFS) forecasts, and an inflation factor of two was applied to compensate for the lack of spread in the GEFS forecasts over the research region. Experiments on an actual stratiform precipitation case that occurred on 5-7 June 2009 in northern China were conducted to validate the ensemble system. The IAP REFS system had reasonably good performance in predicting the observed stratiform precipitation system. The perturbation inflation enlarged the ensemble spread and alleviated the underdispersion caused by parent forecasts. Centering the extracted perturbations on higher-resolution NCEP Global Forecast System forecasts resulted in less ensemble mean root-mean-square error and better accuracy in probabilistic quantitative precipitation forecasts (PQPF). However, the perturbation inflation and recentering had less effect on near-surface-level variables compared to the mid-level variables, and its influence on PQPF resolution was limited as well. [ABSTRACT FROM AUTHOR]