颜面不对称三维评价方法的研究进展

面部对称性评价是正畸、口腔、整形外科等研究颜面部美观相关学科所关注的热点。尽管国内外学者借助各种新兴技术与手段开展了很多有关颜面对称性评价的研究,但由于其内容和方法的复杂性以及个人评价的主观性,目前颜面不对称的评判仍尚未建立统一的标准。颜面不对称涉及面部长宽高三个方向的改变,属复杂的牙颌面畸形,其早期发现及精确评价尤为重要,临床上除了必要的牙颌面检查,还需配合相应的辅助手段来评价颜面不对称。本文通过对目前常用的三维评价方法进行总结归纳,按照评价手段将颜面不对称评价方法分为三维测量的定性分析、定量分析、动态分析、数理分析、人工智能分析等5大类方法。通过分析总结各类方法的临床应用特点、优势及局限性,发现虽然每种方法的精确度、评价范围、诊断性质、计算方法等均有不同,但随着三维测量技术的不断发展,三维评价方法将会越来越客观、精准、便捷,成为评价颜面部不对称的主流方法。

Three-dimensional stability analysis of anisotropic and non-homogeneous slopes using limit analysis

A method of three-dimensional loaded slope stability for anisotropic and nonhomogeneous slopes was presented based on the upper-bound theorem of the limit analysis approach. The approach can be considered as a modification and extension of the solutions. The influences of friction angle, anisotropy factor, nonhomogeneous factor, slope angle, ratio of width to depth, and load on the slope crest were investigated. The results show that solutions are suitable to deal with the purely cohesive soils and frictional/cohesive soils, isotropic and anisotropic, homogeneous and nonhomogeneous, loaded and unloaded cases.

Three-dimensional stability of landslides based on local safety factor

Unlike the limit equilibrium method(LEM), with which only the global safety factor of the landslide can be calculated, a local safety factor(LSF) method is proposed to evaluate the stability of different sections of a landslide in this paper. Based on three-dimensional(3D) numerical simulation results, the local safety factor is defined as the ratio of the shear strength of the soil at an element on the slip zone to the shear stress parallel to the sliding direction at that element. The global safety factor of the landslide is defined as the weighted average of all local safety factors based on the area of the slip surface. Some example analyses show that the results computed by the LSF method agree well with those calculated by the General Limit Equilibrium(GLE) method in two-dimensional(2D) models and the distribution of the LSF in the 3D slip zone is consistent with that indicated by the observed deformation pattern of an actual landslide in China.

Three-dimensional analysis of slopes reinforced with piles

Based on the upper bound of limit analysis, the plane-strain analysis of the slopes reinforced with a row of piles to the 3D case was extended. A 3D rotational failure mechanism was adopted to yield the upper bound of the factor of safety. Parametric studies were carried out to explore the end effects of the slope failures and the effects of the pile location and diameter on the safety of the reinforced slopes. The results demonstrate that the end effects nearly have no effects on the most suitable location of the installed piles but have significant influence on the safety of the slopes. For a slope constrained to a narrow width, the slope becomes more stable owing to the contribution of the end effects. When the slope is reinforced with a row of piles in small space between piles, the effects of group piles are significant for evaluating the safety of slopes. The presented method is more appropriate for assessing the stability of slopes reinforced with piles and can be also utilized in the design of plies stabilizing the unstable slopes.

Failure mechanism and stability analysis of the Zhenggang landslide in Yunnan Province of China using 3D particle flow code simulation

Based on the principle of 3D particle flow code,a numerical landslide run-out model is presented to simulate the failure process of the Zhenggang landslide(in southwestern China) under the effect of water after a rainfall.The relationship between the micro-mechanical parameters and the macro-shear strength of the grain material is determined through numerical calibrations.Then the rainfall effect is considered in numerical simulations and rain-induced sliding processes are performed,which help us to discuss the mechanism of deformation and failure of this landslide together with field observations.It shows the Zhenggang landslide would most likely be activated in Zone I and would gain momentum in Zone II.In order to prevent the potential disaster,a tailing dam is advised to be designed about 175 m downstream from the current landslide boundary of Zone II.Verified by field observations,the presented landslide model can reflect the failure mechanism after rainfall.It can also provide a method to predict the potential disaster and draft disaster prevention measures.

3D stability analysis method of concave slope based on the Bishop method

In order to study the stability control mechanism of a concave slope with circular landslide, and remove the influence of differences in shape on slope stability, the limit analysis method of a simplified Bishop method was employed. The sliding body was divided into strips in a three-dimensional model, and the lateral earth pressure was put into mechanical analysis and the three-dimensional stability analysis methods applicable for circular sliding in concave slope were deduced. Based on geometric structure and the geological parameters of a concave slope, the influence rule of curvature radius and the top and bottom arch height on the concave slope stability were analyzed. The results show that the stability coefficient decreases after growth, first in the transition stage of slope shape from flat to concave, and it has been confirmed that there is a best size to make the slope stability factor reach a maximum. By contrast with average slope, the stability of a concave slope features a smaller range of ascension with slope height increase, which indicates that the enhancing effect of a concave slope is apparent only with lower slope heights.

Time-variant reliability analysis of three-dimensional slopes based on Support Vector Machine method

In the reliability analysis of slope, the performance functions derived from the most available stability analysis procedures of slopes are usually implicit and cannot be solved by first-order second-moment approach. A new reliability analysis approach was presented based on three-dimensional Morgenstem-Price method to investigate three-dimensional effect of landslide in stability analyses. To obtain the reliability index, Support Vector Machine （SVM） was applied to approximate the performance function. The time-consuming of this approach is only 0.028% of that using Monte-Carlo method at the same computation accuracy. Also, the influence of time effect of shearing strength parameters of slope soils on the long-term reliability of three-dimensional slopes was investigated by this new approach. It is found that the reliability index of the slope would decrease by 52.54% and the failure probability would increase from 0.000 705% to 1.966%. In the end, the impact of variation coefficients of c andfon reliability index of slopes was taken into discussion and the changing trend was observed.

Application of FLAC3D in supporting engineering of deep foundation ditch

Based on the design principles of economic rationality and safety,multiple-pivot pile anchorage approach was used as the supporting engineering of a tall building with a deep foundation ditch.The designs,such as anchor arm,single pile and the whole,were set up in accordance with the calculations of the internal force from the equivalent beam and Yamagata Kunio methods.Moreover,the rationality of the design was estimated using the stability checks.FLAC3D was used for calculating the accuracy of the design.Using FLAC3D to simulating ditch cutting and supporting processes can obtain the equivalent results as the theory analysis in the displacement of ditch surrounding wall,the stress field and stress distribution.

3D-QSAR and action mechanism of potential dual inhibitors towards AP-1 and NF-κB

Three-dimensional quantitative structure-activity relationship （3D-QSAR） and docking studies of a series of novel dioxopyrrolinyl-amino-pyrimidine derivatives, which are potential dual inhibitors mediating a transcriptional activation towards protein-1 （AP-1） and nuclear factor kappa B （NF-κB）, have been carried out. The QS, AR models established by comparative molecular field analysis （CoMFA） and comparative molecular similarity index analysis （CoMSIA） show a good predictive ability with cross-validated coefficients q2 of 0.644 and 0.636, respectively. The docking result shows that there are quite lower average values of the flexible and rigid energy scores on the selected binding sites, meanwhile, it further shows that the binding sites just fall on the joint regions between AP-1 （and NF-κB） and DNA. The reason that these analogues have inhibition function towards AP-I and NF-κB is that their existence on these joint regions can effectively prevent free AP-I and NF-κB from binding to DNA. These results can offer a valuable theoretical reference to the pharmaceutical molecular design as well as the action mechanism analysis.

Three-Dimensional Stability Analysis of Excavation Using Limit Analysis

The theory of limit analysis is presented for a three-dimensional stability problem of excavation. In frictional soil, the failure surface has the shape of logarithm helicoid, with the outline profile defined by a log- spiral curve. The internal dissipation rate of energy caused by soil cohesion and gravity power of the failure soil is obtained through theoretical derivation. By solving the energy balance equation, the stability factor for the excavation is obtained. Influence of the ratio of width to height, the slope angle, and the top angle on the stability is examined. Numerical results of the proposed algorithm are presented in the form of non dimensional graph. Examples illustrate the practical use of the results.

Finite element analysis for inclined wellbore stability of transversely iso-tropic rock with HMCD coupling based on weak plane strength criterion

The finite element analysis(FEA) technology by hydraulic-mechanical-chemical-damage(HMCD) coupling is proposed in this paper for inclined wellbore stability analysis of water-sensitive and laminated rock, developed basing on the recently established FEA technology for transversely isotropic rock with hydraulic-mechanical-damage(HMD) coupling. The chemical activity of the drilling fluid is considered as phenomenological hydration behavior, the moisture content and parameters of rock considering hydration could be determined with time. The finite element(FE) solutions of numerical wellbore model considering the chemical activity of drilling fluid, damage tensor calculation and weak plane strength criterion for transversely isotropic rock are developed for researching the wellbore failure characteristics and computing the time-dependent collapse and fracture pressure of laminated rock as shale reservoirs. A three-dimensional FE model and elastic solid deformation and seepage flow coupled equations are developed, and the damage tensor calculation technology for transversely isotropic rock are realized by introducing effect of the hydration and the stress state under the current load. The proposed method utilizing weak plane strength criterion fully reflects the strength parameters in rock matrix and weak plane. To the end, an effective and reliable numerically three-step FEA strategy is well established for wellbore stability analysis. Numerical examples are given to show that the proposed method can establish efficient and applicable FE model and be suitable for analyzing the timedependsolutions of pore pressure and stresses, and the evolution region considering the hydration surrounding wellbore,furthermore to compute the collapse cycling time and the safe mud weight for collapse and fracture pressure of transversely isotropic rock.

3D-QSAR and docking studies on 2-arylbenzoxazole and linker-Y transthyretin amyloidogenesis inhibitors

Transthyretin(TTR),a plasma protein with a tetramer structure,could form amyloid fibril associated with several human diseases through the dissociation of tetramer and the misfolding of monomer.These amyloidogenesis can be inhibited by small molecules which bind to the central channel of TTR.A number of small molecules like 2-arylbenzoxazoles(ABZ)analogues are proposed as promising therapeutic strategy to treat amyloidosis.In this work,comparative molecular field analysis(CoMFA)and comparative molecular similarity indices analysis(CoMSIA)three-dimensional quantitative structure-activity relationship(3D-QSAR)and docking studies were performed on series of 2-arylbenzoxazoles(ABZ)and linker-Y analogues to investigate the inhibitory activities of TTR amyloidogenesis at atomic level.Significant correlation coefficients for ABZ series(CoMFA,r2=0.877,q2=0.431;CoMSIA,r2=0.836,q2=0.447)and those for linker-Y series(CoMFA,r2=0.828,q2=0.522;CoMSIA,r2=0.800,q2=0.493)were obtained,and the generated models were validated using test sets.In addition,docking studies on 6 compounds binding to TTR were performed to analyze the forward or reverse binding mode and interactions between molecules and TTR.These results from 3D-QSAR and docking studies have great significance for designing novel TTR amyloidogenesis inhibitors in the future.