运输规划问题退化解产生的原因及求解策略

退化解的产生是运输规划问题中的一个常见现象,它明显表现为初始可行基或基变量的数目小于m+n-1,这对它后面的迭代造成了困难,针对这一现象根据基变量的数目为m+n-1的理论,通过用添加“0”的方法来保证基变量的数目,从而使解的退化问题正常化,解决了运输规划问题的求解问题。     

素数排列问题初探

本文在研究素数类型规律的基础上,探讨其排列情况。     

基于波束域LC-GSC的降秩波束形成算法

针对传统GSC算法在处理大型阵列天线时,所需运算量大、工程上难以应用等问题,提出一种基于波束域LC-GSC的降秩波束形成算法。与传统GSC算法相比,它能够在期望信号和特定干扰方向上形成约束响应,利用构造的转换矩阵将信号变换到波束域,并能够降低计算量,加快自适应收敛速度。根据信号特征值大于噪声特征值,可以得到波束域协方差矩阵逆的高次幂基本等价于信号子空间,信号子空间的求取也方便构造阻塞矩阵。降秩矩阵可以利用GSC下支路的快拍数构造,进一步降低运算量。最终根据算法得到自适应权矢量,为了使系统有更好的信噪比稳健性,可以将权矢量向信号子空间投影。通过对GSC算法进行分析并改进,给出算法在FPGA上的实现方案。实验仿真表明,该算法能够在期望信号方向准确形成主瓣,干扰方向准确形成零陷且副瓣电平降低5~10dB。基于波束域LC-GSC的降秩波束形成算法有很好的波束形成性能,算法稳健性较好。     

减缩旋转体时域有限差分法

减缩时域有限差分法(R-FDTD)和旋转体时域有限差分法(BOR-FDTD)是两种高效节约存储量的算法。本文提出了减缩旋转体时域有限差分法(R-BOR-FDTD)的基本原理,实现了两种算法的结合,进一步大幅度地节约了存储空间。数值实验证实了该方法的有效性。     

简约HJ神经网络在图书馆个性化信息推荐中的应用

通过仿真实验得出,运用简约HJ神经网络原理可以从我们所收集查找到的信息中分离出和读者需求信息最接近的信息,这样可以大大降低我们个性化信息推荐的盲目性和低效性,从而更进一步提升我们图书馆的个性化信息服务质量。     

深源地震折合能量的标度性及其与深度的关系

利用1987年1月至2001年12月的哈佛CMT目录和美国NEIC地震辐射能量目录,研究了全球范围内震源深度大于70km的地震的辐射能量与地震矩之比(或称折合能量)随地震矩的变化及其与震源深度之间的关系.结果表明对震源深度为70～400km的地震,折合能量随地震矩的增加而降低;对于深度大于400km的地震,折合能量随地震矩的增加而增加.这一特征与浅源地震似乎很不相同.     

SMILES扩展算法及其在族性结构处理中的应用

目前在所建立的族性结构检索系统中一般包括两个步骤,即族性结构的拆分和还原图(Reduced Graph)的生成。本文在分析SMILES线性编码算法的基础上,通过扩展其算法快速简单地实现了上述两个过程,将SMILES线性编码的使用范围扩展到族性结构研究领域,结合具体实例说明了SMILES线性编码在处理族性结构信息中的应用。     

有限个不全为零的既约分数的一个性质

给出了有限个不全为零的既约分数的一个性质,及其在研究有理系数多项式方面的一个应用。     

Why deaf pupils have reduced graduation rates from compulsory education in Greece？ An investigation of factors related to their low attainment

The current article deals with the issue of increased dropouts of deaf pupils from compulsory education （primary and junior high school） and tries to map out plausible reasons according to what principals and teachers for the deaf say, which might account for these reduced graduation rates for deaf pupils from primary dropouts. Official statistics are employed to demonstrate and junior high school. This data is collected through annual census surveys targeting all primary and secondary schools for the deaf, conducted by the National Statistical Service of Greece （NSSG）. Then, this paper tries to explore some of the possible reasons, which could be at the root of these increased dropout rates from primary and lower secondary schools, according to the accounts of principals and teachers for the deaf, who serve in schools for the deaf. Two types of questionnaire were employed, addressed to principals and teachers for the deaf, serving in schools for the deaf, one on one, and telephone interviews, with these two categories of respondent. Low graduation rates are associated with several factors, including inadequate coverage for schools for the deaf, the fact that Gymnasia do not operate everywhere there are primary schools for the deaf and the fact that often deaf pupils have to enrol in schools for the deaf only after suffering considerable delay can be partly attributed to the relative shortage of schools for the deaf. Other limitations include the inadequate use of hearing aids by pupils, associated with inadequate screening and assessment procedures; a lack of kindergartens and preschools for the deaf; and the relative shortage of speech therapists in schools for the deaf. In addition, teachers criticized the fact that the ＂whole-day＂ school initiative, which allows pupils to remain in school until 4 p.m. and have assistance with their homework, does not operate in the majority of schools for the deaf. In addition, the need to create books and teaching materials more tailored to deaf pupils＇ needs was mentioned, as well as inadequate or lack of teacher training in deaf pedagogy and Greek Sign Language. Findings are discussed in accordance with the international bibliography on this issue.     

减量训练对大鼠骨骼肌超微结构及酶活性的影响

目的探讨大负荷训练后减量训练对大鼠骨骼肌超微结构及其酶活性的影响,为大负荷运动后减量训练的研究提供理论和实验参考。方法大负荷运动7周后,再进行4周减量训练,运用酶免疫和电子显微镜技术观察大负荷训练后减量训练腓肠肌琥珀酸脱氢酶(SDH)、乳酸脱氢酶(LDH)、超氧化物歧化酶(SOD)和丙二醛(MDA)表达及腓肠肌超微结构的变化。结果大负荷训练后再进行4周的减量训练,可明显提高SHD活性,降低MDA的含量,但LDH活性降低;4周的减量训练损伤的腓肠肌细胞结构基本恢复正常。结论 4周的减量训练可明显改善损伤的骨骼肌细胞结构,有利于骨骼肌细胞结构的恢复,提高骨骼肌的有氧代谢能力和抗氧化能力,但不能提高骨骼肌的无氧代谢能力。