相控线阵声波测井辐射器驱动信号源的设计与测试

介绍了相控线阵声波测井辐射器的工作原理，根据辐射器各个阵元的性能参数设计了两种供实验使用的激励信号源，即5通道Burst信号源和4通道脉冲信号源。Burst信号源输出电压峰值连续可调（6～30V），相邻通道之间的延迟时间可调（0～22μs），步长为1μs，输出频率可根据换能器的频带在10-250kHz选择。脉冲信号源输出电压幅度连续可调（50～150V），延迟时间为0～7vs可调，步长为0.25μs,脉冲宽度为1～4μs。利用这两种信号源可以对相控线阵声波辐射器进行相位和幅度加权控制。在实验室内对这两种信号源进行了性能测试，结果表明，两个信号源均能满足实验要求。     

Rapid growth and sterility of growth hormone gene transgenic triploid carp

Triploid carp (100%) with 150 (3n=150) chromosomes were obtained by crossing the females of improved tetraploid hybrids (♀, 4n=200) of red crucian carp (♀)×common carp (♂) with the males of diploid yellow river carp (♂, 2n=100). The crosses yielded transgenic triploid carp (positive triploid fish, 44.2% of the progeny) and non-transgenic triploid carp (negative triploid fish). Histological examination of the gonads of 24-month-old positive triploid fish suggested they were sterile and the fish were not able to produce mature gametes during the breeding season. Morphologically, both the positive and negative triploid fish were similar. They had a spindle-shaped, laterally compressed, steel grey body with two pairs of barbells. Most of the quantifiable traits of the triploid carp were intermediate between those of the two parents. The positive and negative triploid fish were raised in the same pond for 2 years. The mean body weight of the positive triploid fish was 2.3 times higher than the negative triploid fish. The weight of the largest positive triploid fish was 2.91 times higher than that of the largest negative triploid fish. Thus, we produced fast-growing transgenic triploid carp that have a reduced ecological risk because of their inability to mate and produce progeny.     

国际直线对撞机（ILC）高梯度射频超导加速腔研制

射频超导（sRF）加速技术已广泛应用于基于加速器的大科学装置．在国际直线对撞机和其他相关项目的推动下,近年来国际上多个射频超导实验室开展了高梯度射频超导加速腔的研制．在不断改进精密加工、电磁场调平、表面处理和电子束焊接等工艺流程的基础上,北京大学近期研制成功一只高质量9-cell超导加速腔,其加速梯度为32．6MV／m,品质因数大于1．0×10^10,性能指标全面达到国际直线对撞机（ILC）的要求．这表明我国已经掌握了高水平超导加速腔的研制技术,为未来参加ILC国际合作以及建设其他采用射频超导加速技术的大科学装置打下了良好基础．     

基于遗传-模糊算法的开关磁阻电机位置计算

采用智能方法实现开关磁阻电机的非线性建模及转子位置的精确估算．根据实验测得的开关磁阻电机定子电流、绕组电感和转子位置，得到开关磁阻电动机非线性特性．利用比特性得到模糊规则，实现开关磁阻电机的模糊建模；在此基础上，分别利用神经网络的学习和遗传算法全局优化算法，实现了精确和最优模糊建模．该方法可以实现转子位置的精确估计并具有一定鲁棒性和可靠性，可取代直接的位置传感器．利用智能建模可以避免非线性系统建模的复杂性．仿真结果证明了建模的有效性．     

Statistical method for mapping QTLs for complex traits based on two backcross populations

Most important agronomic and quality traits of crops are quantitative in nature.The genetic variations in such traits are usually controlled by sets of genes called quantitative trait loci (QTLs),and the interactions between QTLs and the environment.It is crucial to understand the genetic architecture of complex traits to design efficient strategies for plant breeding.In the present study,a new experimental design and the corresponding statistical method are presented for QTL mapping.The proposed mapping population is composed of double backcross populations derived from backcrossing both homozygous parents to DH (double haploid) or RI (recombinant inbreeding) lines separately.Such an immortal mapping population allows for across-environment replications,and can be used to estimate dominance effects,epistatic effects,and QTL-environment interactions,remedying the drawbacks of a single backcross population.In this method,the mixed linear model approach is used to estimate the positions of QTLs and their various effects including the QTL additive,dominance,and epistatic effects,and QTL-environment interaction effects (QE).Monte Carlo simulations were conducted to investigate the performance of the proposed method and to assess the accuracy and efficiency of its estimations.The results showed that the proposed method could estimate the positions and the genetic effects of QTLs with high efficiency.     

转生长激素基因三倍体鲤鱼的快速生长与不育特性

将转草鱼生长激素基因黄河鲤(♂)与改良四倍体鲫鲤(♀)交配, 获得100%三倍体子代“鲤鱼”. 通过特异引物PCR检测, 子代鲤鱼包括转基因(简称阳性鱼)和非转基因(简称阴性鱼)两部分, 其中阳性鱼占总检测鱼数的44.2%; 染色体检测表明, 子代转基因鲤鱼的染色体数目为3n=150; 组织切片结果表明性腺不能发育成熟; 在同龄的鲤鱼繁殖季节(24月龄), 转基因三倍体鲤鱼仍不能产生成熟配子. 阳性和阴性三倍体鲤鱼在形态上无明显差异, 它们的体侧扁, 近似纺锤形, 体色青灰, 有两对口须, 大部分可测量性状和可数性状都介于父母本之间, 表现出杂种特征. 2年同塘养殖结果表明, 阳性鱼的平均体重为阴性鱼的2.3倍; 其中最大阳性鱼个体的体重为最大阴性鱼的2.91倍. 因此, 本研究不仅证实了转基因三倍体鲤鱼的生长快速特性, 而且第一次用实验消除了转基因鲤鱼养殖应用上的生态安全之虑.     

一种基于图像边缘的鲁棒水印算法

本文基于图像的边缘,提出一种鲁棒水印算法．该算法使用Prewitt检测算子对载体图像进行边缘检测,并对边缘点进行选取,将水印信息嵌入在边缘点像素处的梯度方向上．由于人类视觉感知在图像边缘处的掩蔽效应,同时由于图像边缘的感知重要性和在图像处理中的稳定性,使得本文算法在不可见性和鲁棒性方面具有较好的效果．本文从理论上分析了算法抵抗攻击的能力．并在试验中得到了验证．同时结合人类视觉感知的掩蔽效应．提出了一种客观评价图像质量的方法．试验中对该方法进行了验证,并表明本文算法在该方法下具有较好的不可见性．     

基于LAMP的售书网站的设计与实现

LAMP(Linux+Apache+MySQL+PHP)以其高效、快捷、安全、成本低廉等优势获得了企业应用开发的青睐。文章介绍了LAMP开发平台构建,以及在该平台上设计和实现电子商务售书网站的过程。     

蛋白基柔性材料的介观重构及其光电子器件

自然界中的蛋白质材料具有天然丰度、多种化学成分、可调控的性能、优异的生物相容及可降解性能等特点,为柔性光电子器件的发展提供了新的机遇.然而,蛋白质化学稳定性差、机械柔性不可控等缺点使得传统加工技术难以应用在其表面,严重制约了其在柔性电子领域的应用.本文首先以丝蛋白和角蛋白为例介绍了天然蛋白材料的介观重构以及加工技术,阐述了天然蛋白质材料的多级网络结构与其物理性能的关系.在此基础上,侧重介绍它们在柔性传感、发光、晶体管及存储等器件中的应用,最后展望了蛋白基柔性材料在光电子器件发展中所面临的挑战以及发展机遇.     

玉树隆宝湖地区粘土可塑性研究

对界限含水量的测定表明，玉树隆宝湖地区的粘性土，由东至西粘性逐渐增强，可塑性也随之增大，其塑性指数在10左右；并作了土质评定。