Effect of fly ash on drying shrinkage of thermal insulation mortar with glazed hollow beads

Drying shrinkage of thermal insulation mortar with glazed hollow beads was measured by a vertical length comparator, and the influences of fly ash with different contents (0, 18%, 36%, and 54% were used) on the long-term drying shrinkage were discussed. The mass loss was measured by the weighting method and the pore structure was characterized using three different methods, including the light microscopy, the mercury intrusion porosimetry (MIP), and the nitrogen adsorption/desorption (NAD) experiments, and the correlations among them were researched. The results show that drying shrinkage process of thermal insulation mortar includes three steps with increasing curing time: the acceleration period (before 7 d), the deceleration period (7-365 d), and the metastable period (after 365 d). Drying shrinkage in the first stage (7 d before) increases quickly owing to the fast water loss, and its development in the last two stages is attributed to the increment of the pore volume of mortar with the radius below 50 nm, especially the increment of the pore volume fraction of the pore radius within the size range between 7.3 nm and 12.3 nm. There is no change in the drying shrinkage development trend of mortar with fly ash addition, and three steps in the service life, but fly ash addition in the mortar restrains its value. There is a linear relationship between the drying shrinkage and fly ash content, which means that drying shrinkage reduces with fly ash addition.     

High-Precision Wideband Phase-Derived Velocity Measurement for Micro-Motion Extraction

A phase-derived velocity measurement method is proposed in a wideband coherent system, based on a precise echo model considering the inner pulse Doppler effect caused by fast moving targets. The Cramer-Rao low band of velocity measurement precision is deduced, demonstrating the high precision of the proposed method. Simulations and out-field experiments further validate the effectiveness of the proposed method in high-precision measurement and micro-motion extraction for targets with weak reflection intensity. Compared with the long-time integration approaches for velocity measurement, the phase-derived method is easy to implement and meets the requirement for high data rate, which makes it suitable for micro-motion feature extraction in wideband systems.     

论我国预算公开法律制度的完善

2015年颁布实施的新《预算法》首次明确将预算公开写入法律条文,揭开了预算公开法律制度建设新篇章。在取得这项突破性进展的同时,我国相关制度建设还存在一定提升空间。文章从预算公开制度建设的发展历程及预算公开实践评价入手,分析现有法律制度中存在的种种局限,从充实制度体系内容、完善监督措施、疏通救济路径以及营造公开氛围等方面提出建议,以促进我国预算公开不断深化,推进民主法治建设进一步发展。     

劳伦斯在《菊花的清香》中的创伤书写

创伤是劳伦斯文学创作的一个重要主题.在短篇小说《菊花的清香》中,劳伦斯运用固定式内聚焦、记忆闪回与重复、延宕等叙事技术,书写了在工业主义蹂躏下的生态创伤和家庭创伤,记录了女主人公伊丽莎白面对创伤和接受创伤的艰难过程,表达出现代人治愈创伤和超越创伤的可能与希望.作品中人物的心理创伤代表的是现代人的集体创伤无意识,生态和家庭创伤是二十世纪社会创伤的一个缩影.     

地面高精度磁测在新疆青河县贝勒克勒铁矿的应用

通过对新疆青河县贝勒克勒铁矿高精度磁法勘探资料的分析和研究,工作区可划分为西部、北部高磁异常区、中西部负值异常区、中部面积正负磁场平缓变化区、东部跳跃变化正值磁异常区,结合工作区岩矿石标本磁性参数可判别各类磁场类型形成的地质原因。划分局部磁异常6个,其中M1、M2、M3磁异常与地下隐伏含磁铁矿石英岩有关,M4、M5、M6磁异常与含铁石英岩有关。对局部典型异常M1、M4进行了半定量解释,并进行了钻探验证,实际验证结果与推断结果较为吻合。     

基于BIM5D技术施工阶段成本控制模型构建

基于先进的BIM5D技术,结合挣值法,深刻挖掘BIM5D技术在成本控制中的潜在优势,系统性地分析成本控制模型的系统实施流程,并通过北京某信息大厦成本控制过程论证了基于BIM5D技术施工阶段成本控制模型构建的可行性。     

退火态5083铝合金焊接接头组织与性能分析

采用连续挤压—拉拔—刮削光亮化技术制备的ER5356铝合金焊丝对退火态5083铝合金板材进行MIG焊接,并通过金相、扫描、硬度、拉伸等观察与测试手段对其焊接接头进行试验分析。结果表明:该技术制备的焊丝焊接效果良好,焊缝无裂纹、夹杂等缺陷;焊接接头各区域组织分布均匀,焊缝中心硬度最低,为68 HV,焊接接头抗拉强度为277 MPa,强度系数为92.3%,力学性能较好,完全达到了实际焊接要求和船舶使用需求。     

Synchronization and bursting transition of the coupled Hindmarsh-Rose systems with asymmetrical time-delays

The study of synchronization and bursting transition is very important and valuable in cognitive activities and action control of brain as well as enhancement for the reliability of the cortex synapses. However, we wonder how the synaptic strength and synaptic delay, especially the asymmetrical time-delays between different neurons can collectively influence their synchronous firing behaviors. In this paper, based on the Hindmarsh-Rose neuronal systems with asymmetrical time-delays, we investigate the collective effects of various delays and coupling strengths on the synchronization and bursting transition. It is shown that the interplay between delay and coupling strength can not only enhance or destroy the synchronizations but also can induce the regular transitions of bursting firing patterns. Specifically, as the coupling strength or time-delay increasing, the firing patterns of the time-delayed coupling neuronal systems consistently present a regular transition, that is, the periods of spikes during the bursting firings increase firstly and then decrease slowly. In particular, in contrast to the case of symmetrical time-delays, asymmetrical time-delays can lead to the paroxysmal synchronizations of coupling neuronal systems, as well as the concentration level of synchronization for the non-identically coupled system is superior to the one of identical coupling. These results more comprehensively reveal the rich nonlinear dynamical behaviors of neuronal systems and may be helpful for us to have a better understanding of the neural coding.     

简支薄壁箱梁自由振动的摄动法解析解

为研究简支薄壁箱梁中剪力滞效应对结构动力特性的影响,基于模态摄动法提出了一种求解薄壁箱梁自由振动的新方法.该方法以相同跨度等截面欧拉梁的频率和模态为Ritz基函数,将箱梁自由振动的微分方程组转化为一组非线性代数方程进行求解.对于简支箱梁,可进一步将代数方程组简化为一元二次方程,从而得到精确的特征值和特征向量.在此基础上,利用所得箱梁振动模态的解析表达式,提出了模态剪力滞系数的概念,从而建立了箱梁固有频率和剪力滞效应之间的关系.随后研究了模态剪力滞系数随跨宽比、翼板抗弯刚度和截面抗弯刚度之比的变化规律.计算结果表明:简支梁腹板处剪力滞系数最大且大于1,为正剪力滞效应;随着模态阶数的增加、跨宽比的减小和翼板抗弯刚度和截面抗弯刚度之比的增大,剪力滞效应呈现增大的趋势.     

一种采用单双跳变的低功耗确定性BIST方案

为实现低功耗和高故障覆盖率,基于单跳变测试技术和2-bit扭环计数器,提出一种新型的单双跳变的确定性测试向量产生器.首先,与一般的确定性测试方案直接存储确定性种子不同,利用ROM存储控制信号并通过单双跳变生成确定性种子和确定性测试向量,这样控制信号的长度约为确定性种子的1/2,有利于降低功耗并节约存储空间.其次,2-bit减法计数器合理地过滤了冗余向量,大大缩短了测试时间并降低总体能耗.最后,为了适应不同的测试需求,还设计了相应的测试向量压缩算法和三种x指定算法.实验结果表明,平均功耗分别降低了42.36%、32.32%、38.94%,测试长度分别减少了77.6%、86.1%、84.3%,测试数据分别压缩了79.4%、65.2%、68.1%.