电子技术实验课改革初探

本文概括介绍了本系在电子技术实验课教学改革方面的一些探索和尝试     

基于横波分裂方法的海南地幔柱研究

利用横波分裂方法,对北京大学、南方科技大学及桂林理工大学在广东和广西布设的宽频带流动台阵以及国家地震台网在广东、广西和海南的固定台站记录的XKS震相进行计算,得到海南及邻近地区的上地幔各向异性参数,分裂延迟时间在0.35～1.90s之间.综合研究区域内前人发表的和本文的横波分裂结果,认为自新生代以来,伴随东部太平洋板块...     

安梨发酵酒的酿造工艺研究

安梨发酵液的提取中，加入０．２％的果胶酶制剂，比对照提高出汁率２０％左右。在安梨酒的酿造中，以纯汁发酵的方式，采用１５～２０℃的低温发酵处理，较好地保持了安梨酒的独特果香，酒体纯正柔和、绵软爽口，突出了安梨酒的风格。成品避光贮存陈酿，减少了酒中维生素Ｃ的氧化损失。     

陕西镇巴早寒武世的牙形刺形化石

记述了陕西镇巴小洋坝下寒武统筇竹寺阶灯影组西蒿坪段及水井沱组内的一些牙形刺形化石,共计4个属7个种,其中新属及新种各一个,我国首次发现的有2属4种。它们中的许多分子具有地理分布广泛、演化迅速的特点,已成为早寒武世洲际地层对比的重要依据。     

标准件模具加工的一种新技术

本文把超塑成形技术引入标准件模具的加工中。用这种技术加工标准件模具,周期短,成本低;超塑成形的模具质量高,寿命长,具有明显的经济效益和社会效益,是一种很有潜力的标准件模具加工新技术。     

Application Value of Slow Decay Behavior of Energy Density Excited by Electromagnetic Pulses

By comparing the radiated energy densities excited by the continuous wave (CW), the sinusoidal pulse, the Gaussian pulse and the rectangular pulse respectively with the same energy, it is shown that the pulses are not more efficient than CW in the energy transmission. For the sinusoidal pulse and the CW, the radiated energy densities are the same in far zone. The radiated energy density of the Gaussian pulse is equal to the one of CW in far zone when the pulse width equals 1/2 of the CWs period T₀. The energy transmission of pulse is more efficient only in the case of 0/2. For the rectangular pulse, the radiated energy density is equal to the one of CW in far zone when the maximum of frequency spectrum is 10f₀ (f₀=1/T₀) and the pulse width is T₀. The numerical results and theoretical analysis in this paper show that the application value of the slow decay behavior of the energy density excited by electromagnetic pulses is limited.     

一种无需先验信息的抗多点源干扰方法

针对存在主瓣干扰在内的多点源干扰情况,现有的阻塞矩阵预处理和特征投影预处理都取得了一定的抗干扰效果,其主要思想都是先通过预处理消除主瓣干扰,再进行常规自适应波束形成,实现对主瓣干扰的抑制,但是这2种方法需要期望和干扰的先验信息来构造预处理矩阵。为解决实际运用当中先验信息无法直接获取的问题,采用强弱信号波达方向估计方法和估计出期望信号方向和干扰方向,再结合基于伪协方差矩阵的特征投影预处理的主瓣抗干扰方法,得到一种无需先验信息的抗多点源干扰算法。仿真实验结果表明,所提方法在不知道角度先验信息的条件下于多点源干扰处形成了大于60 dB的空陷,且相比于其他方法,波形保持好,受快拍数的影响小,取得了较好的抗多点源干扰效果。     

南水北调东线济平干渠边坡垂直截渗技术

针对南水北调东线济平干渠渠首段存在高水头侧渗、渗水量多、施工困难的问题,采用数值计算和理论分析的方法,提出用深层搅拌水泥土防渗墙进行垂直渗流控制的措施,并运用渗流有限元技术,分析了防渗墙位置对渠道边坡截渗效果的影响,以及不同深度悬挂式防渗墙、封闭式防渗墙对渠道边坡截渗效果的影响,推荐了15 m深的悬挂式垂直截渗方案。     

五大连池新期火山区自然景观分类

应用SPOT4多光谱遥感数据,对五大连池老黑山与火烧山新期火山熔岩区及其周边进行了分类.利用envi图像处理软件对图像进行了粗校正、决策树I、SODATA分类,形成研究区的地貌类型分类图.其中对水体和渣状熔岩的区分进行了着重研究,由于所获得的SPOT4数据的4个波段,光谱均方差太大,导致所选的样本数据的光谱范围出现较大重合,论文中采取了样本优化,得到比较满意的结果.SPOT4数据易获得,分辨率较TM数据高,在地貌分类中有一定应用前景.     

Shape memory biomaterials prepared from polyurethane/ureas containing sulfated glucose

Covalently crosslinked polyurethane/urea polymers were synthesized using diamine monomers modified with pendant glucose groups and 2,4‐toluene diisocyanate, poly(ethylene glycol) (PEG), and 1,1,1‐tris(hydroxymethyl)ethane (triol) comonomers. The polymers showed shape memory behavior with a switching temperature dependent on the glass transition temperature. The glass transition temperature is tuned by varying the mole ratio between the glucose‐diamine and PEG used in the polymerization. Increasing PEG content resulted in decreasing glass transition temperature, and a glass transition temperature of 39 °C, close to physiological temperatures, was obtained. The fixed shape showed gradual shape recovery behavior, but a fixity of 70% was achieved when the material was stored at 25 °C. The polymer recovered to the permanent shape when heated to 50 °C. Finally, the surface of a film of the polymer can be sulfated to achieve increased blood‐compatibility without sacrificing the shape memory properties. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2252–2257