热镀锌钢板表面锌波纹影响因素的数值分析

针对热镀锌钢板表面出现的锌波纹问题,通过带钢表面锌液流动的一维简化模型预测锌层稳态厚度;采用摄动法并结合三维气刀射流湍流流场的大涡模拟,提出热镀锌钢板表面锌波纹的数值预测模型;研究工艺参数对锌波纹的影响规律.结果表明：气刀距带钢的距离越远,刀唇间隙越大,气刀入口压强越小,带钢表面锌波纹越明显;气刀入口湍流强度对锌波纹影响可以忽略.     

柬教官计算机专业外训教学探索

近年来,我室承担了柬埔寨教官计算机专业培训的外训教学任务,由于没有外训经验,教学过程中面临许多新问题,任务艰巨。如何有效实施计算机专业外训教学,提升外训教学水平是当前迫切需要探索的课题。从柬教官的特点和计算机专业的特点出发,对外训教学的规范化问题提出了几点看法,以期为提高教学效果提供借鉴。     

A robust hybrid approach based on particle swarm optimization and genetic algorithm to minimize the total machine load on unrelated parallel machines

This paper dealt with an unrelated parallel machines scheduling problem with past-sequence-dependent setup times, release dates, deteriorating jobs and learning effects, in which the actual processing time of a job on each machine is given as a function of its starting time, release time and position on the corresponding machine. In addition, the setup time of a job on each machine is proportional to the actual processing times of the already processed jobs on the corresponding machine, i.e., the setup times are past-sequence-dependent (p-s-d). The objective is to determine jointly the jobs assigned to each machine and the order of jobs such that the total machine load is minimized. Since the problem is NP-hard, optimal solution for the instances of realistic size cannot be obtained within a reasonable amount of computational time using exact solution approaches. Hence, an efficient method based on the hybrid particle swarm optimization (PSO) and genetic algorithm (GA), denoted by HPSOGA, is proposed to solve the given problem. In view of the fact that efficiency of the meta-heuristic algorithms is significantly depends on the appropriate design of parameters, the Taguchi method is employed to calibrate and select the optimal levels of parameters. The performance of the proposed method is appraised by comparing its results with GA and PSO with and without local search through computational experiments. The computational results for small sized problems show that the mentioned algorithms are fully effective and viable to generate optimal/near optimal solutions, but when the size of the problem is increased, the HPSOGA obtains better results in comparison with other algorithms.     

基于玻尔兹曼的微机械陀螺温度误差补偿

使用最优拟合的方法,在一定的温度范围内,对微机械陀螺仪温度误差建模,通过温度误差模型对陀螺仪输出进行温度误差补偿。应用线性拟合和玻尔兹曼拟合方法对实验数据进行按拟合修正,该方法减小了温度对微机械陀螺仪的影响,并验证玻尔兹曼误差模型的正确性与可实用性。补偿后的数据较陀螺原始数据零偏,提高了1~2个数量级。在工程实际中有一定的实用参考价值。     

Effects of Auditory Cues for Linear and Differential Magnification Methods on Visual Inspection Performance

The unfavorable consequence of biased attention to peripheral objects was reported with the use of a newly proposed differential magnification method by the authors. Given the favorable influence of auditory cueing on attention orientation, this study investigated the effectiveness of auditory cues in directing participants’ attention from the peripheral to foveal areas of the differential magnifying lens for improving inspection performance. Thirty‐nine Chinese undergraduates performed a simulated inspection task using a particular magnification method (between‐participant factor). Three within‐participant factors of auditory cue interval, target difficulty, and magnification power were tested. Objective performance measures of speed and accuracy and subjective evaluation using NASA task load index were collected and analyzed. The results showed that positive effects of auditory cues were found for the differential magnification methods but not for the traditional linear magnification method. Significant effects of target difficulty and magnification power were also found. It was concluded that the aid of auditory cues, which did not share the same attentional resource with the visual inspection task, proved to be an appropriate reminder for the differential magnification methods to improve participants’ visual inspection performance. Attention should also be paid to selecting an appropriate auditory cue interval for search tasks of different target difficulties. The findings of this study have implications for the design of video magnifiers in the context of multimodal human–machine interfaces.     

用能量法分析体外预压力对简支梁动力性能的二阶效应

精细地考虑了体外筋变形中的二阶项,用能量法推导了体外预应力梁的自振频率,阐明了体外预压力对梁自振频率的效应.计算结果表明:体外预压力压缩软化效应的影响系数,主要取决于转向座的数量.无转向座时,体外筋偏心距损失为最大,影响系数为1,体外预压力的效应与外轴力的效应相同.随着转向座数量的增加,偏心距损失减小,体外筋接近于无粘结筋,影响系数降低至接近于0,即接近于无粘结筋预压力的零效应.当梁转向座的数量≥2时,由于影响系数显著地小于1,可以忽略体外预压力的压缩软化效应.随着体外筋面积和偏心距的增加,梁的第1自振频率增大.不过,体外筋对其他阶自振频率的影响很小,可以忽略.     

粘土水泥复合浆材强度研究

通过室内试验,研究了水灰比、龄期、粘土加量、压滤效应等对粘土水泥浆材结石无侧限抗压强度的影响。分析试验结果表明,粘土水泥浆无侧限抗压强度和浆液水灰比随着龄期的变化规律呈指数关系。在完全压滤作用下,抗压强度随着压力的增大而大幅提高,且强度随龄期呈二次多项式规律变化,如在0.8 MPa压力作用下,粘土水泥浆材结石28 d无侧限抗压强度增大3倍左右;抗压强度随着粘土加量的增大而减小,粘土加量在50%~60%间出现大幅下降。研究表明,在注浆工程中采用粘土水泥浆材时,应尽可能创造条件产生较充分的压滤效应,控制粘土加量不超过50%,水灰比在2∶1左右,可以获得足够的强度指标。适量添加粘土,这类浆材完全可以用于注浆加固工程中。     

明渠流动条件下单圆墩阻水效应实验研究

该文利用明渠水流的水工模型实验手段探究单圆墩阻水效应空间分布规律及其阻水系数取值新方法。利用高精度超声水位测量系统,采集了墩柱附近特定影响区域内水位过程线,通过分析墩柱周围壅高幅值,验证了阻水效应特性与流态因子之间的新关系。定量分析了墩柱阻水效应的空间影响范围及水位变化的空间分布特征,推求墩柱阻水系数计算的新公式。研究结果可为大尺度河流水动力模拟中桥梁墩柱的概化提供一定参考依据。     

沙沱水电站纵向混凝土围堰爆破拆除方案探讨

乌江沙沱水电站纵向围堰建于表孔溢流面、消力池底板和消力池尾坎等永久建筑物上,由于距离过近,必须采取预裂爆破技术。从炮孔布置、预裂爆破参数、装药结构、起爆网络等方面介绍了爆破方案,并通过爆破振速公式确定了最佳段装药量。施工实践表明,沙沱水电站纵向混凝土围堰预裂爆破达到了预期效果,确保了爆区周边永久建筑物的安全稳定。     

爆破振动对邻近水工建筑物影响的监测与分析

在邻近水工建筑物环境下进行爆破开挖,爆破振动会产生一些负面效应,因此爆破振动监测十分必要。以大渡河深溪沟水电站安装间排水灌浆廊道开挖工程为例,对厂房机组及其他关键部位进行了爆破振动监测,并对数据进行回归分析,通过调整和优化爆破参数,既确保了原有机组的正常运行和其他水工建筑物的安全,同时又加快了工程施工进度,可为类似工程提供借鉴和参考。 