基于遗传算法的门限自回归模型在浅层地下水位预测中的应用

提出了建立门限自回归模型的一种简便通用的方法，用遗传算法可同时优化门限值和自回归系数．实例计算的结果说明了其可行性和有效性．该方法在各种工程时序预测中具有广泛的应用价值     

Effective electromagnetic and chiral parameters of chiral composite material

The effective parameters of chiral composite are studied using a simple model, that is, randomly oriented non-interacting wire helices embedded in a nonchiral host medium. It is found that both the effective permittivity ? and permeability μ are independent on the handedness of the chiral objects while the effective chirality admittance ξ is dependent. It is also found that when the ratio of the radius of the chiral helix to its pitch is about 0.23, maximum chirality admittance is achieved. The effective parameters of equichiral sample are also discussed.     

Alkali-metal Na Adsorption and Promoted Oxidation on Si(100)2×1 Surface

The alkali-metal Na adsorption on Si(100)2×1 surface and its promoted oxidation and Si oxidegrowth have been investigated by means of thermal desorption,work function,Auger electronspectroscopy and photoemission electron spectroscopy.The experimental data showed that therewas a new state,interface electron state,near the Fermi level after the deposition of Na atoms.It wasfound that the presence of Na always caused an increase of the oxygen initial uptake whereas thepromotion of Si oxide growth was observed only at the coverage of Na greater than 0.5 ML.A newmechanism of Na-promoted Si oxide growth is suggested in this paper.     

Electrical properties and positron annihilation study of (Ba<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Ho<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>)TiO<Subscript>3</Subscript> ceramics

DC resistivity, dielectric constant, dielectric loss and positron annihilation spectra of (Ba_1−x Ho _x )TiO₃ ceramics have been measured as a function of holmium concentration x. It has been found that the DC resistivity of (Ba_1−x Ho _x )TiO₃ is strongly dependent on the Ho content: it decreases three orders of magnitude and reaches a minimum at x = 0.4%. Doping with 0.6% holmium increases the permittivity of BaTiO₃ by approximately three times (from ∼1,300 to ∼4,000), with only a slight increase in the corresponding dielectric loss. The local electron density and defect concentration estimated using positron annihilation technique conforms well to the features found in the dielectric and resistivity measurements. The results have been discussed in terms of a mixed compensation model.     

长输管道建设物流管理新模式——物资配送

长输管道工程是以线路管道与沿途站场为主要内容的建设工程,其物资配送有着不同于一般物流管理的特点,点多线长,且交通不便.文章结合西南成品油管道建设工程的物资配送实践,总结出长输管道物资配送的类型,并从机构设置、计划编制、台账和报表管理等方面介绍了物资配送的管理内容及经验,实践证明,这种物资配送方法不但使业主的物资管理人员大为减少,而且使长输管道工程的物资供应更加及时有序.     

日本年轻建筑师的现状——1960年代的这一群

一人脉对照 1 日本现代建筑师溯流 引领日本现代建筑进人成熟时期的领袖人物非丹下健三莫属。由师从丹下的模文彦（1928年-）、黑川纪章（1934年-）以及大高正人（1923年-）、菊竹清训（1928年-）等4人在1960年代创导的新陈代谢运动，使主流的欧美建筑界开始认真关注一个亚洲的小国——日本的建筑活动。可以说新陈代谢运动是日本现代建筑发展的基石也是随后其建筑发展的原动力。     

下消化道出血DSA诊断及栓塞结合小剂量垂体后叶素灌注治疗

目的探讨不明原因下消化道出血的DSA诊断及介入栓塞治疗的临床应用价值.方法对32例不明原因下消化道出血患者行DSA检查,通过显示造影剂外溢、病理血管和肿瘤染色来确定出血原因及部位,对出血处行超选择性动脉栓塞治疗和留置导管灌注小剂量垂体后叶素维持12 h止血治疗.结果DSA诊断阳性率75%(24/32),其中肠伤寒2例,肠结核1例,血管性病变14例,肿瘤7例.阳性者介入手术成功20例,手术成功率83.3%,无一例严重并发症.结论DSA检查和介入治疗对诊断不明确或保守治疗无效的下消化道出血有着重要的诊断及治疗     

海洋石油开发工业污染物产生系数和排放系数研究

污染物产生系数和排放系数是工程环境影响评价的重要指标,但对于海洋石油开发工程环境影响评价来说,迄今尚无具权威性的系数可资使用。在我国近海石油开发工程污染源系统调查的基础上,对海洋石油开发行业污染物产生系数和排放系数的定义、计算方法、应用范围及应用方式进行了探讨,研究结果可为海洋石油开发工程项目环境影响评价及环境保护管理,以及行业或企业有关标准的制定提供参考。     

NCP101x系列转换开关在超高亮度Luxeon Star LED驱动电路中的应用

NCP101x系列自供电转换开关集成了固定频率电流模式控制器和900 V的MOSFET.介绍NCP101x系列电路的引脚功能和特点,给出基于NCP101x的Luxeon Star发光二极管(LED)驱动电路.     

海河流域防汛会商系统的开发与应用

结合海河流域防汛会商系统的开发情况,对防汛会商系统的功能、技术进行了详细的说明,对今后防汛会商系统开发及改进具有借鉴意义.