Three-dimensional Building Damage Simulation Based on GIS

GIS technology has been applied to building damage analysis around the world. However, most previous studies focused on the application of 2-D GIS technology, and the results from traditional earthquake damage prediction are displayed in 2-D figures and charts, which is incapable of demonstrating the 3-D spatial characteristics of buildings. Taking brick-concrete building as an example, we study the characteristics of building damage, and effectively combine the information of building textures and earthquake damage. Then, we apply Google SketchUp techniques to create building models and display them with seismic damage texture in the ArcGIS Engine software development environment. In this paper we propose a solid idea for 3-D simulation of earthquake damage, which is helpful in earthquake damage prediction, virtual emergency rescue practice and earthquake knowledge education.

Growth simulation of Fraxinus chinensis stands damaged by Hyphandria cunea in Beijing area

Hyphandria cunea is an insect that can damage hundreds of plants in its larval phase and needs to be placed under quarantine at an international level. Its hosts involve 600 plant species, including forest and fruit trees, shrubs, crops, vegetables, weeds and others. In 2006, we surveyed two Fraxinus chinensis Roxb stands, damaged to different degrees, after the invasion of H. cunea in the Changping district of the Beijing area. Given our survey of individual trees and investigation of bio-environmental factors, we pro-vide a preliminarily simulation of the growth situation of F. chinensis stands, damaged by H. cunea, by using the Forest Vegetation Simulator software （FVS）, which is supported by the ＂948＂ project from the State Forestry Administration of China. The results will provide a valuable reference in forecasting the effect of H. cunea and other invasive pests in China on forest ecological values.

Region-dependent micro damage of enamel under indentation

The objective of this investigation is to explore the region-dependent damage behavior of enamel, as well as to develop a good understanding of the deformation mech- anisms of enamel with numerical modeling. Nanoinden- tation experiments have been performed to investigate the load-penetration depth responses for outer and inner enamel. Results show that the unloading curve does not follow the loading curve, and degradation of stiffness in the unloading curve is observed. Based on the experimental data, a physi- cal quantity, the chain density in protein, has been introduced to the Drucker-Prager plastic model. Numerical simulations show that the simulated load-penetration depth curves agree with the experiments, and the stiffness degradation behav- iors of outer and inner enamel are captured by the numerical model. The region-dependent damage behavior of enamel could be revealed by the numerical model. The micro dam- age affected area at inner enamel is larger than that at outer enamel, indicating that the inner enamel experiences more micro damage than the outer one. Compared with its outer counterpart, the inner enamel which is rich in organic protein could break more internal protein chains to dissipate energy and to enhance its resistance to fracture accordingly.

Growth and yield responses to simulated hail damage in drip-irrigated cotton

The frequent occurrence of hailstorm in Xinjiang affects cotton(Gossypium hirsutum L.)production and causes enormous economic loss.The indeterminate growth habit of cotton allows for varying degrees of recovery and yield when different hail damage levels occur at different stages,which brings inconvenience to agricultural insurance claims and post-damage management.Therefore,this study aimed to elucidate cotton recovery and yield responses to different levels of simulated hail damage at different growth stages.Four levels of hail damage(0,30,60,and 90%)were simulated every 15 d from the five-leaf stage to the boll opening stage in 2018 and 2019,for a total of six times(Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅴ,and Ⅵ).The results showed that seed cotton yield decreased as the damage level increased and yield reduction increased when the damage was applied to older plants(for 30,60 and 90% damage levels,yield reduction was 9-17%,22-37% and 48-71%,respectively).One possible reason was that the leaf area index and leaf area duration of plant canopy decreased after hail damage,resulting in a reduction in the accumulation of above-ground biomass.However,when hail damage occurred before bloom,due to the indeterminate growth habit of cotton,the vegetative organs produced a strong compensation ability that promoted the bud development.The compensation ability of vegetative organs decreased when hail damage occurred after bloom and the recovery time was too short to promote new boll maturity.As the first study to understand the recovery of cotton after hail damage,it analyzed the leaf area index,leaf area duration,above-ground biomass accumulation and yield,rather than the yield alone.The findings are of great importance for cotton production as they inform decisions about post-damage management practices,yield forecasts and insurance compensation.

Mechanism on simulation and experiment of pre-crack seam formation in stope roof

The pre-crack blast technology has been used to control the induction caving area in the roof. The key is to form the pre-crack seam and predict the effect of the seam. The H-J-C blast model was built in the roof. Based on the theories of dynamic strength and failure criterion of dynamic rock, the rock dynamic damage and the evolution of pre-crack seam were simulated by the tensile damage and shear failure of the model. According to the actual situation of No. 92 ore body test stope at Tongkeng Mine, the formation process of the pre-crack blast seam was simulated by Ansys/Ls-dyna software, the pre-crack seam was inspected by a system of digital panoramic borehole camera. The pre-crack seam was inspected by the system of digital panoramic borehole in the roof. The results of the numerical simulation and inspection show that in the line of centers of pre-hole, the minimum of the tensile stress reaches 20 MPa, which is much larger than 13.7 MPa of the dynamic tensile strength of rock. The minimum particle vibration velocity reaches 50 cm/s, which is greater than 30-40 cm/s of the allowable vibration velocity. It is demonstrated that the rock is destroyed near the center line and the pre-crack is successfully formed by the large diameters and large distances pre-crack holes in the roof.

Investigation on damage mechanism of compressor blades in turboshaft engine induced by ice impacts at various locations

Ice causes impact damage to different positions of the compressor blade,destroys the structural integrity of the rotor structure,and then causes unbalanced failure and even causes nonlinear vibration accidents such as collision and friction,which affects the execution of helicopter tasks.To investigate the influence of impact position on the damage form and dynamic response of blades during ice impact,a dynamic model by finite element-smooth particle fluid dynamic coupling method is created.The ice impact damage experiment of the TC4 plate based on the air gun experimental platform was carried out to verify the reliability of the simulation model.The damage of compressor blades impacted by ice from different positions under static and design speed of 45000 r/min is analyzed.The research results indicate that under static conditions,the damage caused by ice impact from the leading edge blade tip to the leading edge blade root first increases and then decreases,with the maximum damage occurring at the 66.7%blade height position on the leading edge.At the design speed,the closer the impact locations are to the leaf tip,the greater the damage is,and the plastic damage,equivalent stress,and kinetic energy loss of the ice impact are lower than the blade static condition.The research conclusion can provide theoretical reference and data support for the design of structural strength and protection of compressor blades in turboshaft engines.

Numerical simulation of damage in high arch dam due to earthquake

Based on the assumption that concrete is macroscopic homogeneous,the cracking evolution process and damage mode of high arch dams are studied in consideration of the heterogeneity of concrete in mesos-cale.The bilinear damage evolution model and the damage evolution model expressed in power function with descending section are adopted to combine with the Mohr-Coulomb criterion with tension cut-off to investigate the crack development and fracture mode of high arch dams under the action of an earthquake.The analysis result of a high arch dam in China under design shows that cracks that take place in concrete are caused by excessive tensile stress.The cracks initiate at the middle of the dam top and distribute at the upper half of the dam while the rest of the parts remain intact.This conclusion agrees with the model test result.

Study on CAD Data Interface to Geometry Description System

The basic way and method to apply the equipment s CAD data to a geometry description system(GDS) are presented,and its interface to GDS is set up.The basic function,flow and implementation technique of the interface are analyzed.Special computer software is programmed,and an application example is given also.The research results indicate that this interface can assist to derive desired data from the CAD data,and provide powerful technical support for the development of a practical data transferring interface.

Static-based early-damage detection using symbolic data analysis and unsupervised learning methods

A large amount of researches and studies have been recently performed by applying statistical and machine learning techniques for vibration-based damage detection. However, the global character inherent to the limited number of modal properties issued from operational modal analysis may be not appropriate for early-damage, which has generally a local character. The present paper aims at detecting this type of damage by using static SHM data and by assuming that early-damage produces dead load redistribution. To achieve this objective a data driven strategy is proposed, consisting of the combination of advanced statistical and machine learning methods such as principal component analysis, symbolic data analysis and cluster analysis. From this analysis it was observed that, under the noise levels measured on site, the proposed strategy is able to automatically detect stiffness reduction in stay cables reaching at least 1%.