粉质黏土中静力沉桩过程产生的孔压试验研究

静压管桩在实际工程中有着广泛应用,桩-土界面超孔隙水压力对静压桩的工作性能有着巨大影响。目前的研究多集中于桩周土中超孔隙水压力的分布,缺少对桩-土界面处应力的真实情况的研究。通过在桩身开孔、嵌入硅压阻式孔隙水压力传感器的方法,在黏性土体中开展了2组模型桩的室内静力压桩试验,对桩-土界面的孔隙水压力、超孔隙水压力的变化规律进行了研究。试验结果表明:利用硅压阻式传感器首次成功监测了沉桩过程中桩-土界面产生的孔隙水压力;2根试桩在沉桩过程中产生的桩-土界面孔隙水压力、超孔隙水压力均随着沉桩深度的增加而增大;同时2根试桩沉桩过程中产生的超孔隙水压力均较大,最大可达4.21 kPa,约为上覆有效土重的75%,在实际工程中需对沉桩过程中产生的较大超孔隙水压力加以重视;同一深度处的超孔隙水压力存在消散现象,随着深度的增加,消散程度逐渐减小;在实际工程中,需采取有效措施,防止超孔隙水压力过大。试验结果可为静压桩施工和桩-土界面理论研究提供参考。     

High precision frequency measurement based on the characteristic of the fuzzy area

The phase difference change is random in the discrete fuzzy area by considering the limit of device resolution, which the device can not stably capture, and the precision of the measured value only reaches the level of ns, but the phase difference change in the concentrated fuzzy area is step by step, and the device can stably capture the change of ps. By using the fuzzy area conversion technology, a high precision frequency measurement is designed. Through computer control and frequency synthesis,the discrete fuzzy area is converted to the concentrated fuzzy area, the ps stability properties of phase difference change on the border of the concentrated fuzzy area is used, the precision can be improved two or three orders of magnitude, and the high precision measurement in a wide range is achieved.     

基于散射光谱的材质分类识别研究

有效的甄别、掌握空间碎片的状态,是合理利用太空资源和在轨航天器规避风险的前提,为了安全、持续地开发和利用空间资源,基于散射光谱,使用夹角余弦和欧式距离嵌入K临近法(KNN-AC-ED),并与经典的朴素贝叶斯分类器作为对比,对实验室测得的空间碎片中常用的四种材质进行分类识别。分类识别的结果显示,KNN-AC-ED法比经典的朴素贝叶斯分类器总体分类精度高4%。研究表明:朴素贝叶斯分类器需要提取每个光谱曲线的三个特征,而特征提取费时费力;KNN-AC-ED法利用光谱线型和强度两种信息,不仅全面的反应了光谱的信息,且计算相对更快捷。通过对空间碎片常用材质的分类,为进一步研究空间碎片的尺寸、材质等信息提供一定的借鉴意义。     

Design of hydraulic shift mechanism for AMT vehicles based on the collaborative optimization method

Based on multidisciplinary design optimization (MDO), a new design method is put forward for hydraulic shift mechanism of heavy-duty vehicle automated manual transmission (AMT). Taking a shift cylinder for example, the collaborative optimization (CO) method for the design problem of a cylinder is devided into one system level design optimization problem and three subsystem level design optimization problems. The system level is an economic model and the subsystem level is mechanics, kinetics, and a reliability model. Application of the multidisciplinary design optimization software iSIGHT modeling and solving, optimal solution of the shifting cylinder CO model is obtained. According to the optimal solution, oil cylinders are machined out and installed on the gearbox of an AMT system for the bench cycle shift test. The results show that the output force and action speed of the optimized mechanism can meet requirements very well. In addition, the optimized mechanism has a better performance compared to the structure of the traditional design method, which indicates that the CO method can optimize the design of hydraulic transmission.     

九龙山珍珠冲组砂砾岩储层改造技术研究与实践

四川盆地九龙山珍珠冲组砾岩储层基质孔渗条件差,非均质性强,裂缝及其溶蚀孔洞是重要的储集空间和主要的渗流通道。针对该区储层特征,结合室内评价实验和储层评价结果,对于裂缝发育的储层,采用土酸酸化;对于裂缝欠发育的储层,在酸化工艺无效的情况下开展加砂压裂工艺试验,通过施工管柱、施工参数的优选,成功地实施了对砾岩储层的加砂压裂改造,取得了一定的改造效果。     

Duffing系统中微弱信号起始点的检测

为从时域上检测微弱信号在系统中出现的时间点,提出了一种基于Duffing系统的微弱信号起始点的间接检测方法.首先将微弱信号与Duffing系统自身的信号相叠加,混合测量后剔除其中Duffing系统产生的信号,再利用dmey小波对待测信号加入系统造成的轨道偏离过程进行时域分析,可较准确测出微弱信号的起始点.由于混沌系统本身对高斯噪声的自免疫特性,因此本方法具有一定的抗噪性.仿真结果显示:该方法能有效地从时域上检测到微弱信号的起始点,其相对误差可达到10-3s,可应用于心动信号特征参数的提取.     

从中国旅游区划研究看中国旅游发展趋势

旅游区划是揭示旅游资源与旅游业空间布局的重要手段,有助于从整体上把握旅游发展趋势.以时间为线索,从命名、范围、依据等方面对不同时期的区划方案进行回顾比较,并对其存在的问题及优缺点进行评述.基于旅游区划的演变对中国旅游业发展趋势进行分析,以期可以更科学合理地进行旅游区划,促使我国旅游业朝着"可持续旅游"方向迈进.     

pH对高氨废水限氧半亚硝化过程中N2O释放的影响

为获得半亚硝化系统中强温室气体N2O减量化释放的控制参数,采用SBR处理人工合成高氨废水(进水氨氮质量浓度约为600 mg·L-1),考察不同进水pH(7.5,8.0和8.5)对N2O释放特性的影响.结果表明,不同进水pH下均释放N2O,每个周期内N2O的释放量随进水pH的升高而减小.pH为7.5,8.0及8.5时,N2O释放量分别占进水氨氮的3.81%、2.35%和2.00%.当pH为7.5时,曝气初始50 min内,N2O释放速率先增大后减小,峰值速率为44.5μg·min-1·g-1,之后维持在16.5μg·min-1·g-1;当p H为8.0及8.5时,曝气初期N2O释放峰值速率分别为33.7,22.9μg·min-1·g-1,之后释放速率随pH降低和NO2-积累而逐渐增大.