喀斯特地区水土漏失监测方法评述

水土漏失具有隐蔽性、特殊性和复杂性,有效监测水土漏失是水土漏失研究的难点问题。通过对洞穴滴水示踪、~(137)Cs同位素示踪、模拟试验、数学模型等水土漏失监测方法的分析,得出以下结论:1)洞穴滴水示踪技术监测获得的水土漏失量普遍偏大;2)~(137)Cs示踪法在均质土壤条件下可以定量示踪土壤侵蚀,但还不能定量示踪非均质的喀斯特石漠化地区的水土漏失;3)水土漏失模拟试验可以揭示一定的水土漏失机理和规律,试验结论与自然界土壤地下漏失情况有一定偏差,实验结果还难以推广至流域尺度;4)当前已构建的地下漏失数学模型对于地下水土漏失的预测还不够准确,其原因是数学模型中的某个影响因子的获取难度不亚于直接监测水土漏失的困难。鉴于当前水土漏失监测方法的不足,需要从水文地质勘测的方法中寻找合理的水土漏失监测法,建立长期监测的机制,为有效防治和阻控地下水土漏失提供科学依据。     

Notch Effect and Frequency Compensation of Dual-Sensor OBC Data in Shallow Water

Reverberation is significant in shallow water and produces obvious notches in OBC spec-tra. It also degrades the quality of sections and increases the difficulty of processing and interpretation. This ...     

一类血吸虫病模型Hopf分支的频域分析

运用频域上的分支理论研究了一类血吸虫病传播模型的Hopf分支动态，严格证明了Hopf分支的存在性，运用四阶调和平衡方法推导出由Hopf分支产生的周期轨的近似解析表达式、频率和振幅。研究结果表明，被感染的钉螺由潜伏期进入易传染期的几率δ对人体内寄生虫数量有重要影响。     

适用于混沌密钥分发的新误码协调方法

对于现有的密钥分发中的误码协调方法的复杂性和多次传输的问题，使用倒三角类坐标定位法来解决。将所得裸钥放置于下三角矩阵中，三边分别进行奇偶比较并互相传输计算结果，以达到定位错误比特位的目的。使用互注入光反馈激光器产生相关性高的混沌态来提取裸钥，通过该协调方法，最终可以达到10－8～10－10量级的误码率。通过该方法可以简单、有效地删除裸钥中的误码，满足现实通信对误码率的容忍度。     

基于多变量希尔伯特频域模型的癫痫发作预测

癫痫发作具有突发性和反复性,对患者生命安全构成巨大威胁.为了对癫痫发作进行有效地预测,提出了多变量希尔伯特频域模型的癫痫发作预测方法.将希尔伯特边际谱、希尔伯特边际谱的变化方向和希尔伯特加权频率组成一个三维特征向量作为多变量希尔伯特频域模型,输入到支持相量机中,实现癫痫的发作预测,最后采用癫痫发作预测特征方法对预测结果进行评估.实验结果表明:采用多变量希尔伯特频域模型分析方法预测δ波和θ波的癫痫发作,癫痫预测范围在30~45 min,患者有足够的时间采取措施应对;癫痫发作周期在5~10 min,缩短患者等待时间,降低焦虑程度;与多种相关方法进行比较,该方法具有较低的错误预报率和较高的预测敏感度.     

"数字电路与系统"多媒体双语教学的体会

“数字电路与系统”具有实践性和离散性等特点;采用多媒体与板书相结合的方法克服多媒体的局限性,发扬板书的优势,取长补短;加强与学生的交流,创建和谐、有序、兴趣盎然的教学氛围。     

CHARACTERISTICS OF QUATERNARY AMMONIUM RESISTANT BACTERIA FROM A FINE PAPERMACHINE SYSTEM

To evaluate the biocide effect of quaternary ammonium chloride (QAC), a whitewater sample was taken from a fine papermachine headbox. By plate spreading method, 51 strains of facultative anaerobe were isolated morphologically. Then the strains were separately transferred to basal medium and were incubated before the beginning of log phase. To identify strains with different QAC resistance, 30-120 ppm of N-Alkyl-benzyl-dimethyl ammonium chloride were added to basal medium.Biocide effect was investigated by comparison of bacterial growth, which can be monitored by 600 nm light absorbance of basal medium suspension. Among 51 strains, only 2 strains can Survive for QAC concentration up to 120 ppm. API20E aud 16S rRNA gene sequencing technique were applied to identify two strains with highest (120 ppm)QAC resistance. One strain (HB22)was identified as Morganella morganii. HB22 can resist QAC concentration up to 150 ppm. HB22 is Gram-negative rod, motile with flagella, catalase positive, oxidase negative, Indole positive, H2S production negative, facultative anaerobe. HB22 has optimum growth condition of 35℃ and pH 7.0.HB22 can catabolize only glucose and D (+)-Mannose.The other (HB45) was identified with high similarity among Pseudomonas cf. monteili or Pseudomonas mosselii or Pseudomonas putida. HB45 can resist QAC concentration up to 200 ppm.HB45 is Gram-negative rod, motile with flagella,catalase positive, oxidase negative, Indole negative,H2S production negative, aerobe. HB45 has optimum growth condition of 30℃ and pH 7.4. HB45 can catabolize L-Arabinose, L(+)-Rhanmose, D (+)-Mannose, Glucose, Glycerol, Lactose, Maltose,Raffmose, Xylose, Cellulose and Xylan. The implication of this work to paper industry is also discussed.     

PIC系列单片机片内定时器实时时钟的实现

针对直接用单片机片内定时器作实时计时不准问题，本文提出了一种可以获取与秒成整数倍关系的定时器溢出信号的方法，同时克服定量溢出中信号被其它中断暂停所受的计时影响，实验表明，在4MHz晶振下，计时误差可控制在每天14s以下，本方法也适用于一般的单片机，在PIC87系列上的实验结果表明效果很好。