摘要：A simplified calculation of the specimen’s stress-strain curve is generally conducted using the two-wave method by the split Hopkinson pressure bar(SHPB),which aligns the onset of the transmitted and reflected ***,this approach neglects the travel time of elastic waves within the *** the travel time of elastic waves,this study quantitatively investigates the error characteristics and patterns of stress,strain,and strain rate in the specimen under different conditions using the theoretical two-wave method,and compares the results with those obtained using the onset-aligned twowave *** study reveals that the stress-time curves derived from the theoretical two-wave method are lower than the actual stress curves,whereas those obtained from the onset-aligned two-wave method are consistently higher than the actual stress curves,with the stress deviation approximating a constant value when the dimensionless time exceeds *** starting point of the stress-strain curves obtained by the theoretical two-wave method is not zero but a point on the strain axis,whereas the onset-aligned two-wave method always starts at ***,the slopes of the stress-strain curves obtained by both methods differ from the actual Young’s modulus of the material,and functional relationships between the slopes and the actual Young’s modulus are *** research offers theoretical guidance for the refined design of SHPB experiments and the accurate processing of data.

摘要：Shearing dislocation is a common failure type for rock–backfill interfaces because of backfill sedimentation and rock strata movement in backfill mining *** paper designed a test method for rock–backfill shearing *** digital image techno-logy and three-dimensional(3D)laser morphology scanning techniques,a set of 3D models with rough joint surfaces was ***,the mechanical behavior of rock–backfill shearing dislocation was investigated using a direct shear *** effects of interface roughness on the shear–displacement curve and failure characteristics of rock–backfill specimens were *** 3D fractal dimen-sion,profile line joint roughness coefficient(JRC),profile line two-dimensional fractal dimension,and the surface curvature of the frac-tures were *** correlation characterization of surface roughness was then analyzed,and the shear strength could be measured and calculated using *** results showed the following:there were three failure threshold value points in rock–backfill shearing dis-location:30%–50%displacement before the peak,70%–90%displacement before the peak,and 100%displacement before the peak to post-peak,which could be a sign for rock–backfill shearing dislocation *** surface JRC could be used to judge the rock–backfill shearing dislocation failure,including post-peak sliding,uniform variations,and gradient change,corresponding to rock–backfill disloca-tion failure on the field *** research reveals the damage mechanism for rock–backfill complexes based on the free joint surface,fills the gap of existing shearing theoretical systems for isomerism complexes,and provides a theoretical basis for the prevention and control of possible disasters in backfill mining.

摘要：畸变谐波是造成电力缺陷问题的主要原因,对于保持联通状态的电缆管道而言,精准检测畸变谐波的谐振行为,才有可能实现对管道内部缺陷的无损检测。为此,文中提出基于时域反射的电缆管道内部缺陷无损检测方法。建立电缆管道接线模型,根据时域反射脉冲参数计算值,确定接头点所处位置,完成电缆管道检测接头点定位。分析缺陷状态下电力谐波,并联合透入深度指标,设计管道内部缺陷检测函数,实现对电缆管道内部缺陷的无损检测。实验结果表明,按照时域反射算法检测电缆管道内部的畸变谐波,可以精准测定谐波信号的谐振强度,能够解决由畸变谐波造成的电力缺陷问题。

摘要：本文在白车身概念设计阶段引入"CAE驱动设计"的思想,采用SFE-CONCEPT建立了某轿车白车身隐式全参数化模型,通过与经验证的有限元模型进行性能分析对比,验证了所建参数化白车身模型的有效性。采用逐步优化方法,结合白车身性能匹配补充轻量化设计的思想,在最大限度地满足白车身静、动态各项性能要求的前提下,获得白车身轻量化设计方案。优化前后白车身性能对比结果表明,在白车身弯曲和扭转刚度变化不大(分别下降0.2%和0.6%)情况下,车身整体长、宽和高分别增加了15,13和9mm,车身1阶弯曲和1阶扭转模态频率分别提高了5.6%和9.2%,车身质量减轻了19.9kg,轻量率达5.76%,取得了明显的轻量化效果。

摘要：如何打造精品教材是教育类出版社共同面对的难题。只有打造强有力的作者团队、编辑团队、营销团队和培训团队,各团队各司其职、通力合作,明晰好教材的标准、明确各团队的权利与义务、合理设计流程,才能打造内容过硬的精品教材。要做到这些,教育出版必须谨记使命,以培养教师和学生为己任,心怀教育大业、心系国家未来。

摘要：新媒体技术是一种以数字技术为核心,以光学和电子为媒介的现代科学技术,主要是依托互联网,通过电脑、电视、手机等媒介传播信息的主流形态。摄影艺术主要是依靠数码相机和数字网络技术的结合,来传递信息的一种艺术方式。探讨新媒体技术对摄影艺术观念的影响,从新媒体技术的内涵和特性、新媒体技术对摄影艺术理念的影响以及新媒体技术对摄影艺术理念影响的表现三个方面来论述。

摘要：直流母线电压对于衡量直流配电系统稳定、保证各功率单元合理分配功率有着重要作用。该文首先分析传统下垂控制的不足,如母线电压偏差、电流分配精度和系统损耗等,由此提出全局下垂控制策略,在减小母线电压偏差的同时可保证各电压源型换流器(voltage source converter,VSC)直流侧输出电流等比例。同时,考虑VSC交直流侧瞬时功率和内部损耗,推导VSC直流侧电压小信号模型,并从非结构化不确定性和参数化不确定性两方面进行建模分析:对于简化电流控制器进行非结构化不确定性建模,消除非线性扰动对于输出电压的影响;而将较为直观的控制器参数和直流侧电容电感值等系统参数变化划分为参数化不确定性,降低不确定性建模结果的冗余度。进而利用?-综合设计方法进行2自由度(2-degree-of-freedom,2DOF)鲁棒控制器设计,分析结果表明,所设计控制器同时满足系统鲁棒稳定性和性能跟踪性的要求。最后,通过稳定性分析及系统仿真验证所提控制器的有效性。

摘要：设计了一种基于Web方式的集信息发布与多媒体通信技术为一体的反恐维稳指挥自动化系统。由信息发布、图形处理和多媒体通信3个子系统组成。将兵力部署、装备部署及设施部署、各种作战预案等图形化地反映于军事电子地图中,利用文字、语音、视频和白板等信息交互方式实现命令的实时下达、战情上报、作战实时监控等行为。

摘要：采空区充填挡墙的设计与施工,直接关系到充填质量、生产能力和成本效益。本文对阿尔哈达铅锌矿采空区充填挡墙的受力情况进行了分析,计算得到不同充填高度下充填挡墙受到的总压力、最大弯矩和作用点位置,同时按照抗压强度、抗剪强度、抗渗透性条件3种计算方法分别对充填挡墙的结构厚度进行了分析,并基于此提出了针对该矿采空区充填挡墙的施工设计方案。研究结果表明:在进行采空区充填时,首次充填高度理论上应低于2.5m;建议现场的施工挡墙厚度不宜小于0.5m。研究成果可为相似工程条件下的采空区充填挡墙的施工设计提供参考。

摘要：研究基于OpenFOAM开源平台,自主开发了三维气体扩散层的重构方法,并基于动网格技术建立了探究振动对气体扩散层内部液态水传输行为影响的数值模型。对不同振动方向、幅度及频率对液态水传输的过程进行了分析。研究发现相比于水平方向,垂直方向上的振动对于液态水的传输影响更明显。液态水的饱和度在高频振动时呈现出较为规则的正弦振动特点,但在低频振动时液态水饱和度的周期性特点不规则或不显著,整体上接近于正弦变化。研究结论对于燃料电池堆的布置方案及减振思路设计具备一定的指导意义。