Postoperative Disc Wedging in Adolescent Idiopathic Thoracolumbar/Lumbar Scoliosis:a Comparison of Anterior and Posterior Approaches

Objective To evaluate the different influences of anterior and posterior correction and fusion approaches upon disc wedging in adolescent idiopathic thoracolumbar/lumbar scoliosis.Methods The retrospective study was conducted with the medical records and radiographs of adolescent idiopathic thoracolumbar/lumbar scoliosis patients that underwent anterior(group A) or posterior(group B) correction and fusion surgery from December 1998 to May 2008.The correction of the main curve and changes of the disc wedging were analyzed.Results Fifty-three patients were included,26 in group A and 27 in group B.The mean coronal Cobb angles of the main curve in group A and group B were significantly corrected after surgery(P<0.05),with an average correction rate of 75.2% and 88.2%,respectively.Upon final follow-up,the coronal Cobb angles of the two groups were 18.9°±11.1° and 7.7°±5.6°,respectively,with an average correction loss of 6.8°±6.5° and 2.7°±3.3°,respectively.The coronal Cobb angle after operation and at final follow-up,and the correction rate were significantly better in group B than those in group A(P<0.05),while the coronal Cobb angle loss in group A was greater than that in group B(P<0.05).The disc wedging before operation,after operation,and at final follow-up were 3.2°±3.0°,5.7°±3.0°,and 8.6°±4.4° in group A,and 2.4°±3.2°,3.3°±3.4°,and 3.7°±3.6° in group B,respectively.Postoperative disc wedging was significantly larger compared with preoperative measurements in group A(P<0.05),but not in group B(P>0.05).The difference between disc wedging at final follow-up and that after surgery was significant in group A(P<0.05),but not in group B(P>0.05).Between the two groups,group A had larger disc angles after operation and at final follow-up(P<0.05),and a greater loss of disc angle(P<0.05).Conclusion For adolescent idiopathic thoracolumbar/lumbar scoliosis,posterior approach using all pedicle screws might produce a better result in terms of disc wedging compared with anterior approach.

Transient dynamic analysis and comparison on wedging processes of overrunning clutches with different contact surfaces

The effects of contact surface on dynamic wedging behavior of the roller and inner-ring of the overrunning clutch in a dual-turbine torque converter were investigated to reveal the friction self- locking mechanism and dynamic process. Planar strain clutch models including roller, inner-ring and outer-ring were built, and transient wedging process was analyzed with an explicit dynamics meth- od. The modeling of stress and strain distribution and variation of two kinds of contact surfaces show that there are three stages named slipping, wedging and binding respectively during whole wed- ging process. Meanwhile the geometric structures of contact surfaces greatly influence the peak stress and strain distribution of the wedging process of the roller and inner-ring. The load bearing performance of contact surfaces with logarithmic spiral curve is better than that with straight line. Our study provides theoretical foundation for design and further optimization of wedging contact surface of an overrunning clutch in a dual-turbine hydrodynamic torque converter.

Genetic Analysis of Structural Styles in the Makran Accretionary Wedge–Insight from Physical Simulations

The Makran accretionary wedge has the smallest subduction angle among any accretionary prism in the world. The factors controlling the spacing and morphological development of its deep thrust faults, as well as the formation mechanism of shallow normal faults, remain unclear. Meanwhile, the factors affecting the continuity of plane faults must be comprehensively discussed. Clarifying the development characteristics and deformation mechanisms of the Makran accretionary wedge is crucial to effectively guide the exploration of gas hydrate deposits in the area. This study aims to interpret seismic data to identify typical structures in the Makran accretionary wedge, including deep imbricate thrust faults, shallow and small normal faults, wedge-shaped piggyback basins, mud diapirs with fuzzy and disorderly characteristics of reflection, décollements with a northward tilt of 1° – 2°, and large seamounts. Physical simulation-based experiments are performed to comprehensively analyze the results of the plane, section, and slices of the wedge. Results reveal that the distances between and shapes of thrust faults in the deep parts of the Makran accretionary wedge are controlled by the bottom décollement. The uplift of the thrust fault-related folds and the upwelling of the mud diapirs primarily contribute to the formation of small normal faults in the shallow part of the area. The mud diapirs originate from plastic material at the bottom, while those that have developed in the area near the trench are larger. Seamounts and mud diapirs break the continuity of fault plane distribution.

Failure mechanism and simulation for long run-out of the catastrophic rock landslide in the Shanyang Vanadium Mine,China

On 12th August 2015,a massive rapid long run-out rock landslide occurred in the Shanyang Vanadium Mine in Shaanxi Province,China,which claimed the lives of 65 miners.No heavy rainfalls,earthquakes,and mining blasts were recorded before the incident.Therefore,the failure mechanism and the cause of the long run-out movement are always in arguments.In this paper,we conducted a detailed field investigation,laboratory tests,block theory analysis,and numerical simulation to investigate the failure and long run-out mechanisms of the landslide.The field investigation results show that the source material of the rock landslide is a huge dolomite wedge block bedding on siliceous shale layers.Uniaxial compression tests indicate that the uniaxial compression strength of the intact dolomite is 130-140MPa and the dolomite shows a brittle failure mode.Due to the progressive downward erosion of the gully,the dolomite rock bridge at the slope toe became thinner.As the compression stress in the dolomite bridge increased to surpass its strength,the brittle failure of the bridge occurred.Then huge potential energy was released following the disintegration of the landslide,which led to the high acceleration of this rock landslide.The 3D discrete element simulation results suggest that the low intergranular friction contributes to the long run-out movement of this rock landslide.

Regulation of Pore Structure and Hightemperature Fracture Behavior of CACbonded Alumina-Spinel Castables Based on Hydration Design

The lamellar hydrates of CAC were designed with the introduction of nano CaCO_(3)or Mg-Al hydrotalcite(M-A-H),and the effects on the green strength,pore structures,and high-temperature fracture behavior of alumina-spinel castables were investigated.The results show that nano CaCO_(3)or M-A-H stimulates rapidly the hydration of CAC and the formation of lamellar C_(4)AcH_(11)or coexistence of C_(2)AH_(8)and C_(4)AcH_(11)at 25℃.The formation of lamellar hydrates can contribute to a more complicated pore structure,especially in the range of 400-2000 nm.Meanwhile,the incorporation of well-distributed CaO or MgO sources from nano CaCO_(3)or M-A-H also regulates the distribution of CA_(6)and spinel(pre-formed and in-situ).Consequently,the optimized microstructure and complicated pore structure can induce the deflection and bridging of cracks,thus facilitating the consumption of fracture energy and enhancing the resistance to thermal stress damage.

Integrated simulation and monitoring to analyze failure mechanism of the anti-dip layered slope with soft and hard rock interbedding

The significant difference between the mechanical properties of soft rock and hard rock results in the complexity of the failure mode of the anti-dip layered slope with soft and hard rock interbedding.In order to reveal the landslide mechanism,taking the north slope of Fushun West Open-pit Mine as an example,this paper analyzed the failure mechanism of different landslides with monitoring and field surveys,and simulated the evolution of landslides.The study indicated that when the green mudstone(hard rock)of the anti-dip slope contains siltized intercalations(soft rock),the existence of weak layers not only aggravates the toppling deformation of anti-dip layered slope with high dip,but also causes the shear failure of anti-dip layered slope with stable low dip.The shear failure including subsidence induced sliding and wedge failure mainly exists in the unloading zone of the slope.Its failure depth and failure time were far less than that of toppling failure.In terms of the development characteristics of deformation,toppling deformation has the long-term and progressive characteristics,but shear failure deformation has the abrupt and transient characteristics.This study has deepened the understanding of such slope landslide mechanism,and can provide reference for similar engineering.

Comparative Study of the Rock-breaking Mechanism of a Disc Cutter and Wedge Tooth Cutter by Discrete Element Modelling

The operation of a shield tunnel boring machine(TBM)in a high-strength hard rock stratum results in significant cutter damage,adversely affecting the thrust and torque of the cutter head.Therefore,it is very important to carry out the research on the stress characteristics and optimize the cutter parameters of cutters break high-strength hard rock.In this paper,the rock-breaking performance of cutters in an andesite stratum in the tunnel of Qingdao Metro Line No.8 was investigated using the discrete element method and theoretical analysis.The rock-breaking processes of a disc cutter and wedge tooth cutter were simulated by software particle flow code PFC^(3D),and the rock-breaking degree,stress of the cutter,and rock-breaking specific energy were analyzed.The rock damage caused by the cutter in a specific section was divided into three stages:the advanced influence,crushing,and stabilizing stages.The rock-breaking degree and the tangential and normal forces of the wedge tooth cutter are larger than that of the disc cutter under the same conditions.The disc cutter(wedge tooth cutter)has the highest rock-breaking efficiency at a cutter spacing of 100 mm(110 mm)and a penetration depth of 8 mm(10 mm),and the rock-breaking specific energy is 11.48 MJ/m^(3)(12.05 MJ/m^(3)).Therefore,two types of cutters with different penetration depths or cutter spacing should be considered.The number of teeth of wedge tooth cutters can be increased in hard strata to improve the rock-breaking efficiency of the shield.The research results provide a reference for shield cutterhead selection and cutter layout in similar projects.

Computational Analysis of Surface Pressure Distribution over a 2D Wedge in the Supersonic and Hypersonic Flow Regimes

The complex fluid-dynamic instabilities and shock waves occurring along the surface of a two-dimensional wedge at high values of the Mach number are studied here through numerical solution of the governing equations.Moreover,a regression model is implemented to determine the pressure distribution for various Mach numbers and angles of incidence.The Mach number spans the interval from 1.5 to 12.The wedge angles(θ)are from 5°to 25°.The pressure ratio(P2/P1)is reported at various locations(x/L)along the 2D wedge.The results of the numerical simulations are compared with the regression model showing good agreement.

Gastric inflammatory myofibroblastic tumor, a rare mesenchymalneoplasm: A case report

BACKGROUND The inflammatory myofibroblastic tumor(IMT)is a rare mesenquimal tumor of doubtful biological behaviour.It’s characterised for affecting mainly children and young adults,although it can appear at any age,being the lungs the primary affected organ(in children it represents 20%of all primary pulmonary tumors).CASE SUMMARY We present the case of a 45 year old woman,with a computed tomography(CT)finding of injury on the anterior surface of the fundus/gastric body and a solid perigastric injury of 12 mm in the ecoendoscopy.The case is presented in the tumor committee deciding to perform a laparoscopic wedge resection.The histological diagnosis was a IMT.The diagnosis is based on imaging tests like the abdominal CT,abdominal ecography and the ecoendoscopy but to confirm the diagnosis a pathological study is necessary.CONCLUSION Due to the unpredictable nature of this tumor,surgical resection is the best therapeutic option.

线电极磨削系统电极丝恒张力模糊控制研究

针对自主设计的一种新型WEDG系统走丝机构,提出了采用模糊控制的方法实现电极丝的恒张力控制。首先分析了该新型WEDG系统走丝机构的工作原理,建立了系统的走丝机构控制模型。在此基础上,基于模糊控制理论,根据张力反馈对送丝轮的转速进行闭环控制,最终实现了电极丝的恒张力控制。基于该WEDG系统进行了微小工具电极的加工实验。结果表明,该WEDG系统走丝稳定、张力恒定,能够以很高的效率制作出直径小(直径小于10μm)、几乎没有锥度的工具电极,很好地满足了的微细电火花加工机床微小工具电极的制作需要。

An Improved Angle Polishing Method for Measuring Subsurface Damage in Silicon Wafers

We present an improved angle polishing method in which the end of the cover slice near the glue layer is beveled into a thin,defect-free wedge,the straight edge of which is used as the datum for measuring the depth of subsurface damage. The bevel angle can be calculated from the interference fringes formed in the wedge. The minimum depth of the subsurface damage that can be measured by this method is a few hundred nanometers. Our results show that the method is straightforward, accurate, and convenient.

Stability of undercut space in fragment orebody based on key block theory

Undercut is one kind of important spaces to place the mining blocks in the mass underground mining. This structure is also used as a compensation space during blasting. In the process of underground mining in the fragment orebody, it is important and critical to analyze the stability and blockage of the three-dimensional wedges created around the undercut space. The wedge stability is mainly controlled by factors including geometry （i.e., the size, shape and spatial location of the wedge and undercut）, the strength （shear and tensile） of the discontinuities that created the wedge, and the stress distribution within the rock mass. The Unwedge software was used to conduct the orthogonal simulation tests （three factors and five levels） that considered different cross sections, trends, and plunges of the undercut space. The results demonstrate that the control value of the safety factor of wedge is set to be 1.2. The optimal parameters are determined in the undercut space, such as the blasting fragmentation, orientation of the fluid flow, and the equipment gradeability;the wedge stability can be evaluated in the light of the block images and continuous falling;the stability of the key block meets the needs of the undercut space, the parameters gained are reasonable and optimal. Cross section is 27°, trend is from 315°to 325°（it is 320°at in-suit test） and plunge is 5°.

Joint inversion of P-wave velocity and Vp–Vs ratio: imaging the deep structure in NE Japan

A new inversion scheme is presented to obtain three-dimensional images of P-wave velocity（Vp） and P–S-wave velocity ratio（Vp/Vs） using P- and S-phase pairs, i.e., the same source–receiver pairs for the P- and S-wave arrival-time data. The S-wave velocity（Vs） was separately inverted using the S-phase arrival times. The earthquake hypocenters were simultaneously relocated in the joint inversion. The method considers the Vp/Vs anomaly as a model parameter in the inversion. The proposed method thus provides a more robust calculation of the Vp/Vs anomaly than the conventional method of dividing Vp by Vs. The method also takes into account the ray path difference between P- and S-waves, and hence yields a less biased Vp–Vs ratio than the method of inverting S–P-wave data for Vp and Vp/Vs anomalies under the assumption of identical P and S ray paths. The proposed method was used to image the crust and upper mantle in northeastern（NE） Japan taking advantage of a large number of high-quality arrival times of P- and S-wave source–receiver pairs. The inverted structures suggest that the subducting slab of the Pacific plate is an inclined zone of high-Vp and Vs anomalies with low Vp/Vs perturbation. The mantle wedge is characterized by low-Vp, low-Vs, and high-Vp/Vs anomalies at shallow depths beneath active volcanoes. These features are also observed at greater depths in the back-arc region. Although these features have been previously reported, the Vp/Vs anomaly pattern obtained in this study shows much less scatter and is much better correlated with the seismic velocity perturbation patterns than previous studies. The proposed method can be used, in conjunction with velocity anomaly patterns, to quantify thermal processes associated with plate subduction.

Contrast of Seismic Reflection Characteristics of Gas Hydrate Distribution between Northeast SCS Slope and Hengchun Ridge

By analyzing and interpreting the newly acquired seismic profile supported by the national 973 Program and synthesizing the data with other geologic ＆ geographic information, we draw conclusions as follows, a） Two seismic reflections located at the northeast South China Sea （SCS） slope and the Hengchun ridge are the Bottom Simulated Reflections （BSRs）. Yet, the genesis and process of the gas hydrate in these two areas are different because of different regional tectonics and geological environments; b） The genesis of gas hydrate located at the northeast SCS slope area is related to the broadly existing fracture zones, slumping tectosomes, and the distinctive shielding environment of pressure masking field formed by them. But the genesis of the gas hydrate at the Hengchun ridge is associated with the thrust nappe structures and accretionary wedges formed along the Manila subduction zone and the related sub-floor fluid channel system built by them; c） Since the analogous geologic bodies are broadly distributed at slope areas around SCS and the temperature-press environment is very suitable to the formation and conservation of the gas hydrate, we suggest that much more of this resource should be stored in these areas.

微铣刀在位制备方法研究

提出基于WEDG技术的微铣刀在位制备方法,将微铣刀的制备与使用结合起来,在同一台微细电火花加工机床上完成微铣刀的在位制备与在位铣削过程,可实现微铣刀的低成本高精度制备,同时避免微铣刀的二次装夹所造成的倾斜和偏心误差,提高微铣削整体质量。为验证基于WEDG技术的微铣刀在位制备工艺方法的可行性,基于自研μEM-200CDS2型双主轴三工位微细组合电加工机床平台,进行了微铣刀在位制备与在位铣削的实验研究。结合WEDG工艺特点对微铣刀进行材料选用与构型设计,实现了直径小于100μm、刃口锋利的D型微铣刀的制备,并利用所制备微铣刀在位铣削出最小壁厚小于20μm的一组薄壁结构。实验结果表明:基于WEDG技术的微铣刀在位制备方法在原理和技术上是可行的。

微细电火花加工用伺服进给控制系统的设计

本文简要介绍了电火花线电极磨削法（ＷＥＤＧ法）的加工原理。分析了应用该方法进行实验研究中伺服进给的特点，并根据这些特点设计了微细电火花加工用伺服进给控制系统。系统中采用了８０３１单片机作为ＣＰＵ，使用方便灵活；系统应用脉宽调制式细分驱动技术，不但提高了加工中的进给分辨率，也使进给系统的频率响应大大提高，满足了微细电火花加工的要求。

微细电极在线制备技术的研究进展

介绍了反拷块法、WEDG法、电化学腐蚀法、EEDG法等几种微细电极的在线制备方法、基本原理、研究现状及最新进展,为实际加工轴类工件及制备工具电极等提供了有益参考。

基于XML的BSP敏捷开发方法

简要分析了目前Linux BSP开发存在的缺陷,通过分析两个不同版本嵌入式Linux的Ac97声卡驱动程序的异同,针对不同处理器提出了一种基于Linux的BSP标准。在此基础上,实现了一套基于XML的Linux BSP标准化配置工具,实现了基于图形界面的Linux BSP生成方式,提高了嵌入式Linux BSP的开发效率。

TTI介质纯准P波一阶压力-速度方程及求解方法

以具有倾斜对称轴的横向各向同性(Titled Transverse Isotropic,TTI)介质中纯准P波二阶方程为基础,通过引入辅助波场实现了方程的降阶,推导出了TTI介质纯准P波一阶压力-速度方程,并利用旋转交错网格高阶有限差分方法对方程进行数值求解,给出了完全匹配层(Perfectly Matched Layers,PML)吸收边界条件在该方程中应用的方法。理论分析及数值模拟结果表明:相对于二阶形式的准P波方程,该TTI介质纯准P波一阶压力-速度方程在计算精度相同的情况下,具有更高的计算效率;同时能更准确地描述对称轴参数变化剧烈的TTI介质中准P波的传播规律。

利用Elekta Omni-Wedge技术提高靶区剂量均匀性的初步探讨

放疗临床剂量学四原则要求接受照射的靶区剂量均匀性要达到一定的标准，通常为±5％。因受人体体表不平整和体内密度不均匀性的影响，有时需要采用一些物理学方法改变野内束流强度分布，插入楔形板就是其中之一。