摘要：Based on the elastic thin plate theory,the main law of the ore roof failure was analyzed and the formula of the ore roof thickness was *** results show that the tensile stress in the roof center accounts for the roof *** to the limit failure conditions of the point,the formula of the ore roof thickness was *** No.10 stope of a bauxite mine as an engineering case,the optimal thickness of the ore roof was 0.36 *** safety factor was taken as 1.3,therefore the design thickness was 0.5 *** the whole industrial test process,the dynamic alarm devices did not start the alarm and the ore roof was not *** with other stopes under similar conditions,its thickness was reduced by 0.1-0.3 *** recovery rate of the ore roof was increased by 16.7%-37.5%.

摘要：This work aimed to quantify the physical and mechanical behavior of three-dimensional microstructures in rocks under uniaxial compression.A high-precision in situ XCT(X-ray transmission computed tomography)technology was applied to investigating the behavior of mineral grains in sandstone:the movement,the rotation deformation,and the principal strains between fault zone and non-fault *** results indicate that after unloading,the shear strain of mineral grains is periodic in the radial direction,the strain of mineral grains in the fracture zone is about 30 times of the macro strain of the specimen,which is about 5 times in the non-fracture zone,and the shear strain near the fault zone is larger than the compressive strain,and there is the shear stress concentration feature.

摘要：Because of its high purity and excellent orientation, mesophase pitch is a superior precursor for high-performance car-bon materials. However, the preparation of top-notch mesophase pitch faces challenges. Catalytic polycondensation at low temperat-ures is more favorable for synthesizing mesophase pitch, because it circumvents the high-temperature free radical reaction of other thermal polycondensation approaches. The reaction is gentle and can be easily controlled. It has the potential to significantly im-prove the yield of mesophase pitch and easily introduce naphthenic characteristics into the molecules, catalytic polycondensation is therefore a preferred method of synthesizing highly spinnable mesophase pitch. This review provides a synopsis of the selective pre-treatment of the raw materials to prepare different mesophase pitches, and explains the reaction mechanism and associated research advances for different catalytic systems in recent years. Finally, how to manufacture high-quality mesophase pitch by using a cata-lyst-promoter system is summarized and proposed, which may provide a theoretical basis for the future design of high-quality pitch molecules.

摘要：针对生物学检测真菌霉素的过程比较复杂、成本高、不易操作等问题,提出了一种利用真菌霉素类物质溶液颜色直接测量溶液浓度的快速检测方法,设计了一个双颜色传感器检测系统.通过颜色传感器测得溶液颜色信息来快速确定被检测物质的质量分数并实现颜色信息采集过程中的动态白平衡,使颜色检测对环境光的变化具有自适应性.最后建立样品溶液颜色的三原色(RGB)值与浓度之间的线性关系.实验结果表明,样品数据的相对标准偏差(RSD)低于5%,利用该快速检测方法建立的线性关系计算得到的溶液浓度与样品实际浓度的相对误差(RE)低于7%,满足实验室精密度和准确度的要求.同时,与传统检测方法相比,该方法快速、方便,并降低了检测成本.

摘要：随着密码攻击方式更加多样、隐蔽且破坏性更强,密码分析者可能拥有越来越多的攻击权限与攻击能力,甚至能够获取算法的内部结构.为了更有效保护密钥,本文提出一种基于三维查找表的白盒SM4密码算法实现方案WIST.首先将SM4分组密码算法的线性变换用矩阵表示,设计了能对密钥信息进行隐藏保护的三维查找表,利用输入编码和输出编码对查找表混淆处理,同时采用仿射函数作为外部编码,完成了SM4算法的白盒化实现,并验证了此算法的正确性.效率分析表明WIST占用内存空间适中,具有较高安全性;安全性分析表明WIST能抵抗BGE攻击、MGH攻击、侧信道攻击、线性攻击与差分攻击等常见攻击类型.WIST可以在白盒攻击环境下更好地保护密钥信息.

摘要：为提高网络流量预测精度,提出结合相空间重构与改进黏菌优化支持向量回归的预测模型。为解决黏菌算法收敛慢、易得局部最优的不足,引入3种形态对立学习对种群进行初始化,提高种群多样性;利用非线性反馈因子更新机制,均衡全局搜索与局部开发;设计柯西-高斯混合变异对最优解变异,扩展搜索空间,避免陷入局部最优。利用改进黏菌算法对支持向量回归优化调参,有效解决超参初值敏感缺陷,提高学习精度和收敛速度,以此构建网络流量预测模型。实验结果表明,改进模型预测误差更小,能够实现高精度和实时性预测要求。

摘要：设计了一款基于形状记忆合金丝(SMA)柔性驱动的机器鱼,详细阐述了柔性驱动器和机器鱼的结构设计和制作工艺,同时设计制作了驱动器和机器鱼的电控系统。柔性驱动器可实现双向弯曲运动,驱动器每一侧布置4路可独立控制的SMA丝,通过选择不同加热路数,可实现机器鱼四级摆动幅度的较精确控制。针对SMA存在的热积累问题,结合柔性驱动器自身的特点,提出了一种轮询加热控制策略,并试验比较了驱动器摆动幅度和摆动频率对机器鱼直线游动行为的影响。试验结果表明,柔性驱动器的摆动幅度越大,机器鱼游速越快;在无SMA热积累的影响下,驱动器的摆动频率越快,机器鱼游速也越快;轮询加热控制策略可有效提高机器鱼的极限摆动频率,获得的最大游速为102mm/s。

摘要：针对三轴叶轮流道粗铣法加工余量不均的问题,提出了基于曲面法向刀具半径偏置法的流道变轴插铣半精加工的刀心点和刀轴矢量计算方法,采用现有的刀心点和安全高度的迭代算法确定了刀具插削和抬刀的轴向位置,所得刀位可有效去除三轴流道开粗法给叶片各部留下的不均匀余量。经对直线轴联动高速端铣和定轴插铣粗加工后的流道进行变轴插铣半精加工的切削实验验证,刀位算法正确,可给后续精加工留下均匀余量,后续叶片精加工可顺利进行。

摘要：阳极层离子源可输出高密度离子束流,广泛用于等离子体清洗和辅助沉积,但大束流下内部易发生放电击穿,且大量离子轰击内外阴极导致明显刻蚀,易造成样品污染.本文提出阳极环绕磁屏蔽罩和内外阴极溅射屏蔽板的设计方案,并仿真研究了其对离子源电磁场和等离子体放电输运的影响.发现阳极环绕磁屏蔽罩可切断离子源内部阴阳极间的磁场回路,消除打火条件.内外阴极溅射屏蔽板选择溅射产额低且绝缘性能好的氧化铝,既可阻挡离子溅射,又能屏蔽阴极外表面电场,使等离子体放电向阳极压缩,在抑制阴极刻蚀行为的同时提升离子输出效率.当距离阴极外表面9 mm时,溅射屏蔽板的作用效果最优,不仅能获得稳定放电和高效输出,还可大幅削弱阴极刻蚀行为并减少污染.实验结果显示:改进离子源无内部打火,输出高效且清洁,相同电流下离子输出效率较原离子源实际提高36%;玻璃基片在经过1 h清洗后,表面成分几乎不变,来自阴极溅射的Fe元素含量仅为0.03%,比原离子源低2个数量级,含量约为原离子源的0.6%,实验结果验证了理论分析.

摘要：讨论了具有随机性风速变化和非线性的风电系统的最大风能捕获控制问题,系统采用基于无源性控制方案下的浆距角和触发角双输入控制方案,通过选择适当的状态稳态特性和注入阻尼的方法,将风能的最大捕获与系统的全局稳定性相结合,设计出了一种对风速变化和参数摄动具有鲁棒性且使风电系统具有良好动态特性的控制系统。仿真结果显示,对于具有随机性风速变化和变参数风电系统,该控制策略可以实现风能的最大捕获。