A closed-loop algorithm to detect human face using color and reinforcement learning

A closed-loop algorithm to detect human face using color information and reinforcement learning is presented in this paper. By using a skin-color selector, the regions with color "like" that of human skin are selected as candidates for human face. In the next stage, the candidates are matched with a face model and given an evaluation of the match degree by the matching module. And if the evaluation of the match result is too low, a reinforcement learning stage will start to search the best parameters of the skin-color selector. It has been tested using many photos of various ethnic groups under various lighting conditions, such as different light source, high light and shadow. And the experiment result proved that this algorithm is robust to the vary-ing lighting conditions and personal conditions.

Stress and buckling analysis of a thick-walled micro sandwich panel with a flexible foam core and carbon nanotube reinforced composite (CNTRC) face sheets

In this paper,the stresses and buckling behaviors of a thick-walled mi-cro sandwich panel with a flexible foam core and carbon nanotube reinforced composite(CNTRC)face sheets are considered based on the high-order shear deformation theory(HSDT)and the modified couple stress theory(MCST).The governing equations of equi-librium are obtained based on the total potential energy principle.The effects of various parameters such as the aspect ratio,elastic foundation,temperature changes,and volume fraction of the canbon nanotubes(CNTs)on the critical buckling loads,normal stress,shear stress,and deflection of the thick-walled micro cylindrical sandwich panel consider-ing different distributions of CNTs are examined.The results are compared and validated with other studies,and showing an excellent compatibility.CNTs have become very use-ful and common candidates in sandwich structures,and they have been extensively used in many applications including nanotechnology,aerospace,and micro-structures.This paper also extends further applications of reinforced sandwich panels by providing the modified equations and formulae.

Finite difference analysis of an advance core pre-reinforcement system for Toulon's south tube

The stability of shallow tunnels excavated in full face has been a major challenge to the scientific community for a long time. In recent years, new techniques based on the installation of a pre-reinforcement system ahead of the tunnel face were developed to control the deformations and surface settlements induced by the excavation and to ensure the sustainability of the tunnel in the long term. In this paper, a finite difference numerical simulation was conducted to study the behaviors and effects of two pre-reinforcement systems, i.e. the face bolting and the umbrella arch system installed in a section of southern Toulon tunnel in France. For this purpose, two approaches were taken and compared： a two-dimensional （2D） approach based on the convergence–confinement method, and a three-dimensional （3D） approach taking into account the complete modeling of the tunnel. A 2D numerical back-analysis was performed to identify the geomechanical parameters that offer satisfactory agreement with the measurement results. The limit of this method lies in the exact choice of the stress relaxation ratio λ. To overcome this uncertainty, a 3D model was developed, which permitted to study the influence of different pre-support systems on the reaction of ground mass. Both 2D and 3D numerical approaches have been fitted to measurements recorded in a section of the Toulon tunnel and the very satisfactory correspondence has allowed validating the simulations. The results show that the 3D numerical analysis with a full discretization of the inclusions seems unquestionably the most reliable approach.

Seismic responses of the steel-strip reinforced soil retaining wall with full-height rigid facing from shaking table test

To investigate the seismic response of the steel-strip reinforced soil retaining wall with fullheight rigid facing in terms of the acceleration in the backfill, dynamic earth pressure in the backfill, the displacements on the facing and the dynamic reinforcement strain distribution under different peak acceleration, a large 1-g shaking table test was performed on a reduced-scale reinforced-earth retaining wall model. It was observed that the acceleration response in non-strip region is greater than that in potential fracture region which is similar with the stability region under small earthquake,while the acceleration response in potential fracture region is greater than that in stability region in middle-upper of the wall under moderately strong earthquakes. The potential failure model of the rigid wall is rotating around the wall toe. It also was discovered that the Fourier spectra produced by the inputting white noises after seismic wave presents double peaks, rather than original single peak, and the frequency of the second peak trends to increase with increasing the PGA(peak ground amplitude) of the excitation which is greater than 0.4 g. Additionally,the non-liner distribution of strip strain along the strips was observed, and the distribution trend was not constant in different row. Soil pressure peak value in stability region is larger than that in potential fracture region. The wall was effective under 0.1 g-0.3 g seismic wave according to the analyses of the facing displacement and relative density. Also, it was discovered that the potential failure surface is corresponds to that in design code, but the area is larger. The results from the study can provide guidance for a more rational design of reinforced earth retaining walls with full-height rigid facing in the earthquake zone.

玻璃纤维增强复合材料薄壁筒端面车削切削力试验研究

在干切条件下研究了端面车削玻璃纤维增强复合材料薄壁筒时切削力的变化特点,分析切削速度、进给量、切削深度、刀尖圆弧半径、进给方式对切削力的影响规律。试验结果表明:纵向进给方式和横向进给方式下,切削力变化特点不同;在横向进给方式下,切削力随进给量、切削深度的增大而增大,随切削速度的增大先减小后增大;以横向进给方式车削端面时,刀尖圆弧与工件的接触状态直接影响切削力的变化;以纵向进给方式车削玻璃纤维增强复合材料薄壁筒端面时,切削力随着进给量的增大而增大。

不同面板型式加筋土挡墙振动响应数值分析

以刚/柔组合墙面加筋土挡墙的振动台试验结果为基准,建立刚/柔组合式、模块加返包式、模块式和格宾式面板型式加筋土挡墙的FLAC^(3D)数值模型,研究面板型式对挡墙水平位移、加速度响应及地震土压力分布的影响。结果表明:在静力作用下不同面板型式挡墙的变形模式略有不同;振动作用下,变形大小为组合式<模块加返包式<格宾式<模块式;加筋区内加速度放大系数为组合式>模块加返包式>格宾式>模块式;面板处加速度放大系数均大于加筋区,且面板型式不同,放大规律亦不同;面板型式不同,地震主动土压力非线性分布规律不同;合力作用点位置大多高于M-O方法的H/3,且受加速度幅值影响较小。

Investigation of the failure mechanism and theoretical model of bolt-reinforced shallow tunnel faces with different bolt lengths

Using fiberglass bolts to reinforce a tunnel face is a practical auxiliary technology for ensuring tunnel face stability in soft ground.The reinforcing effect and the economics of this technology are significantly affected by bolt length.However,to date,the failure mechanism of bolt-reinforced tunnel faces with different bolt lengths has rarely been investigated.To reveal the failure mechanism of bolt-reinforced shallow tunnel faces,in this study,the stability of bolt-reinforced tunnel faces with different bolt lengths was investigated by using laboratory tests and numerical simulations,and a simplified theoretical model for practical engineering was proposed.The face support pressure and failure pattern for different bolt lengths during the face collapse process were obtained,and the influence of bolt length on face stability was clearly revealed.More specifically,the results show that face stability increases with increasing bolt length,and the reinforcing effect of face bolts is governed by the shear failure at the soil-grout interface first in the stable zone of the tunnel face and then in the failure zone.Once the bolt length in the stable zone is larger than that in the failure zone,face stability will not be improved with increasing bolt length;thus,this bolt length is referred to as the optimal bolt length L_(opt).The L_(opt)value is slightly larger than the initial failure range(in the unreinforced condition)and can be approximately calculated by L_(opt)=(1-0.0133u)D(u is the friction angle of the soil,and D is the tunnel diameter)in practical engineering.Finally,a simplified theoretical model was established to analyse the stability of reinforced tunnel faces,and the results are in good agreement with both laboratory tests and numerical simulations.The proposed model can be used as an efficient tool for the design of face bolts.

轴压比和面承板厚度对混合节点抗震性能的影响

为了研究新型柱全截面隔板式钢筋混凝土柱-钢梁(RCS)混合框架节点形式的抗震性能,考虑不同轴压比和面承板厚度的影响,对2组共6个3/4比例的梁柱节点进行低周往复加载试验研究.试验中所有试件均发生设计预期的节点剪切破坏,滞回曲线呈弓型,表明节点具有良好的抗震性能.试件最终因节点区的混凝土开裂剥落而丧失承载力.试验结果表明,当轴压比为0~0.25时,随着轴压比的增大,RCS节点开裂荷载有所增大,峰值荷载前斜裂缝数量减少、宽度减小,试件的承载力、刚度和耗能能力均有所提高.节点域柱纵筋黏结应力随轴压比增大而减小,表明节点域内黏结状况有明显改善.相较于单向面承板试件,双向面承板试件在承载能力、延性和耗能能力方面均表现出显著提高;当双向面承板厚度由6 mm增加至10 mm时,试件峰值承载力和刚度的提升幅度相对有限.

水-岩软化作用下巴东组泥岩隧道大断面开挖掌子面稳定性研究

为明确软弱围岩条件下高速铁路隧道大断面机械化施工过程中的掌子面稳定性特征,以郑万铁路巴东隧道穿越巴东组紫红泥岩段为工程背景,对隧道揭露的巴东组紫红泥岩开展不同含水率下的三轴试验,揭示巴东隧道紫红泥岩的水-岩软化特征;在考虑水-岩软化特征的Hoek-Brown强度准则下,构建考虑水-岩软化作用的隧道穿越巴东紫红泥岩地层流-固耦合数值模型,揭示不同地层水位下巴东组紫红泥岩隧道大断面施工掌子面稳定性特征;最终提出“掌子面喷混凝土+掌子面超前锚杆+超前管棚”的组合式超前加固方案。经过试验和模拟计算,结果表明:1)随含水量的增加,巴东隧道紫红泥岩的刚度与抗剪强度显著降低,与既有研究揭示的浅表地层紫红泥岩相比,巴东隧道紫红泥岩具有更高的抗剪强度;2)掌子面后方拱顶沉降、掌子面前方拱顶预收敛、掌子面挤出变形的最大值均随历史水位的升高而增大;3)根据不同地层历史水位条件下开挖面支护力与挤出变形之间的关系,巴东隧道紫红泥岩掌子面稳定性可以分为A(稳定)、B(短期稳定)以及C(不稳定)3类,对于C类掌子面,采用“掌子面喷混凝土+掌子面超前锚杆+超前管棚”的组合式超前加固措施后,掌子面前后方各项变形最大值可以减小60%~90%。

返包式加筋土挡墙地震损伤状态评估指标研究

地震损伤状态评估指标可用于快速评估震后加筋土挡墙服役状态,也可服务于基于位移的抗震设计方法。鉴于目前仍缺乏返包式加筋土挡墙的地震损伤状态评估指标,通过模型振动台试验探讨动力特性变化规律及其与损伤程度之间的关系。结果表明:挡墙的变形模式随动荷载强度的增大而发生变化,当所有工况结束后,最大总残余位移为27.8 mm(2.78%H);结构的动力特性变化规律可以表征结构的损伤状态;随动荷载强度的增大,加筋土体的等效剪切应变从1×10^(-4)增至2×10^(-2),结构所处的状态更加危险。提出了一种基于动力特性和位移指数分布规律来确定加筋土挡墙地震损伤状态指标的方法,通过该方法将返包式加筋土挡墙的地震损伤状态定义为三个等级,并给出了对应的位移指数。

综放工作面过陷落柱底板注浆厚度研究

针对综放工作面过陷落柱等地质构造带时极易出现煤壁片帮、架前冒落、支架陷入底板等生产难题,为优化底板注浆加固厚度,结合某矿实际地质条件,通过UDEC数值模拟对比不同注浆厚度时的支架陷底量,推导了注浆加固厚度与支架载荷和加固体强度等参数的本构关系,计算结果显示:加固厚度应随着支架载荷的增大而增大,随着注浆体强度的增大而减小;综合分析确定:当注浆厚度为1m时,支架能够适应底板的条件。依据数值模拟和理论计算结果,设计了注浆主要参数,并完成施工,实现综放工作面安全经济通过陷落柱。

窑洞建筑病害分析及加固技术研究

窑洞建筑是黄土高原地区典型的传统民居,具有4000多年的文明史,它的妥善保护与传承具有重要的历史、文化和科学价值。本文通过大量的实地调研并结合理论分析,对窑洞建筑病害种类及其出现的原因进行了详细分析,根据简单、合理、低成本和快速高效的原则,提出了窑洞建筑合理可行的修缮加固技术,为西北地区传统民居的保护和传承提供科学合理的技术保障。

大采高工作面破碎顶板注浆加固技术应用

以慈林山煤矿3109大采高工作面为工程实例,为解决该工作面在遇断层和超前支撑应力、构造应力耦合状态下,其破碎岩体容易发生超前冒顶和片帮的问题,针对性设计注浆方案与选定注浆浆液;工程实践表明,该工作面破碎区域注浆效果良好,实现了安全推采,提高了生产效率。

成庄矿综放面过构造破碎带耦合加固技术应用

为了解决成庄矿4321工作面过断层破碎带期间片帮冒顶、倒架歪架等问题,针对性提出深孔预注浆加固、顶板锚索补强、帮部化学材料注浆耦合加固技术,结合顶板控制、采高控制、关键设备管理等诸多辅助措施,现场实践表明,采取预注浆加固与锚索补强措施后,液压支架与顶板接触状态得到明显改善,支架稳定性明显增强,保证了工作面过断层期间的安全。

冰水堆积体隧道掌子面稳定性及合理注浆加固参数研究

以西藏自治区林芝市米林隧道穿越冰水堆积体段为背景,建立考虑渗流和不考虑渗流两种情况下的数值模型,对比分析了不同注浆加固参数的隧道掌子面相对挤出变形与强度折减系数的关系。分析结果表明:在考虑渗流和不考虑渗流两种情况下,不同注浆加固参数与安全系数的曲线趋势一致,开挖面安全系数均随注浆厚度、注浆纵向长度和等效黏聚力的增加而增大,并逐渐趋于稳定,渗透系数对开挖面安全系数影响不大,但考虑渗流情况下的开挖面安全系数远小于不考虑渗流情况。

刚性墙面双面加筋土挡墙动力响应振动台模型试验研究

设计并完成了1:4的刚性墙面双面加筋土挡墙振动台试验,在满足相似关系的前提下,通过输入不同幅值的水平向正弦波,分析刚性墙面双面加筋土挡墙的动力响应特性。研究结果表明:两侧加筋区和中部非加筋区的加速度沿着高度方向均呈现出明显的放大效应,并在挡墙顶部达到最大值。随着加载幅值的增加,双面加筋土挡墙顶部的最大放大系数主要分为3个阶段,分别是平稳段、上升段与衰减段。最大墙面位移和残余位移沿着高度方向呈线性增大。当加载幅值未超过临界加速度时,位移量较小;而加载幅值超过临界加速度时,位移会迅速增大。同时,临界加速度对双面加筋土挡墙的变形模式有着决定性作用。刚性墙面双面加筋土挡墙的筋材动应变增量随着加载幅值持续施加而不断增大。底层的最大筋材应变增量出现在连接处,且沿着高度方向,最大筋材应变增量的位置不断向内部移动。

注浆加固技术在综采面过空巷中的应用

通过全面了解综采面过空巷所面临的挑战以及注浆加固技术的发展历程,探究注浆材料、设备和工作原理,结合具体工程实践案例,突显注浆加固技术在实际操作中的成效。比较技术的优势与局限性,强调其在巷道稳定性方面的实际效果,并提出未来研究的方向。该研究旨在为煤矿工程中推广注浆加固技术提供实用指导,以提高煤矿工程的整体安全性和效益。

残采工作面回风巷注浆加固与支护技术研究

为了解决五阳煤矿7615残采工作面回风巷处于煤柱中间应力集中区,在开采卸荷过程中,巷道在工作面回采前方,在回采侧围岩变形,帮部煤体严重挤出,锚杆索锚固失效,难以保障生产的难题,分析7615工作面内部情况,讨论原支护中存在的问题,针对性提出了注浆加固技术和顶板长短锚索加强支护,经数值模拟验证后进行工业性试验,结果表明,顶底板位移量和两帮移近量分别减小了82.20%和69.75%,新的注浆加固与支护技术有效控制了巷道断面收缩,维持了巷道的长期稳定。

大采高工作面过逆断层超前预注浆加固技术研究

针对大采高工作面通过逆断层时煤壁片帮、顶板漏冒严重、工作面推进困难的问题,详细调查工作面情况,建立数值模型模拟研究大采高工作面过逆断层阶段工作面顶底板及超前支承应力显现规律。在此基础上,提出了适合于大采高工作面过逆断层阶段煤壁和顶板围岩稳定性控制的超前预注浆加固技术体系。经现场技术实施可知,注浆后工作面煤壁片帮、冒顶现象大大缓解,工作面日产量达到2400~3600 t,提高近2倍,实现了工作面过断层阶段的安全开采。

高性能无机注浆材料在“孤岛”工作面巷道加固中的应用

为保证“孤岛”工作面巷道顶板和煤柱结构稳定性,针对工作面两巷在回采过程中受到叠加动压影响,变形严重的问题,采取注浆加固措施,使用硫铝酸盐水泥熟料与生石灰、石膏等材料作为主要注浆原材料进行配比,加入添加剂后改良其可塑性及抗压强度,经过实践验证,加固后,巷道两帮移近量217.5~252.6 mm,顶底移近量达212.3~239.4 mm,巷道变形情况得到控制。