型钢高强混凝土柱轴压比限值的试验研究

通过20个型钢高强混凝土柱的低周反复加载试验对其受力性能进行了研究，分析了剪跨比、轴压比、配箍率以及混凝土强度对型钢高强混凝土柱延性的影响，提出了不同剪跨比、不同配箍率的型钢高强混凝土柱的轴压比限值。其中，剪跨比大于2．0的型钢高强混凝土柱的轴压比限值由大、小偏心界限破坏时力的平衡条件并结合试验结果确定，而剪跨比小于2．0的型钢高强混凝土柱的轴压比限值则通过与剪跨比大于2．0的型钢高强混凝土柱的延性对比加以确定。     

女山幔源包体及其寄主岩中微量元素和过渡金属元素的研究

对女山碧玄岩、超镁铁岩包体和高压巨晶中微量元素及过渡金属元素进行探讨。研究表明,碧玄岩中ＬＲＥＥ较之ＨＲＥＥ更为富集,其分配型式属ＬＲＥＥ富集型;包体中ＬＲＥＥ较ＨＲＥＥ略显富集之势,分配型式属平坦型,这与地幔具有平缓的ＲＥＥ模式相符,其中略富ＬＲＥＥ与碧玄岩对应。碧玄岩、包体和高压巨晶中过渡金属元素具有不同的分配型式。但是不管在碧玄岩与包体之间,还是在巨晶与碧玄岩之间,某些过渡金属元素的含量都具有相关关系。可见,碧玄岩与包体具有成因联系,巨晶与碧玄岩也具有成因联系。     

Nature and role of CO2 in some hot and cold HCO3/Na/CO2-rich Portuguese mineral waters: a review and reinterpretation

 At the northern part of the Portuguese mainland, the upflow zone of several hot and cold HCO₃/Na/CO₂-rich mineral waters is mainly associated with important NNE–SSW faults. Several geochemical studies have been carried out on thermal and non-thermal hydromineral manifestations that occur along or near these long tectonic alignments. The slight chemical differences that exist between these meteoric hot and cold HCO₃/Na/CO₂-rich mineral waters seem to be mainly caused by CO₂. δ¹³C_(TIDC) values observed in these groundwaters range between –6.00 and –1.00‰ versus V-PDB (V denotes Vienna, the site of the International Atomic Energy Agency; PDB originates from the CaCO₃ of the rostrum of a Cretaceous belemnite, Belemnitella americana, collected in the Peedee formation of South Carolina, USA) indicating a deep-seated (mantle) origin for most of the CO₂. Nevertheless, in the case of the heavier δ¹³C_(TIDC) values, the contribution of metamorphic CO₂ or the dissolution of carbonate rock levels at depth cannot be excluded. Concerning the hot waters, the lack of a positive ¹⁸O-shift should be attributed to water-rock interaction in a low temperature environment, rather than to the isotopic influence of CO₂ on the δ¹⁸O-value of the waters. Received: 9 August 1999 · Accepted: 8 March 2000     

病态总体最小二乘问题的谱修正迭代法

针对病态问题岭估计法及正则化方法存在破坏方程的等量关系、解是有偏估计的问题,在最小二乘谱修正迭代法的基础上,提出病态总体最小二乘问题的谱修正迭代法,并推导了总体最小二乘谱修正迭代法及其改进算法的具体公式。通过算例验证和阐明了TLS谱修正迭代法在病态问题中的有效性和易受迭代初值影响的缺点。     

Angstrom公式参数对ET0的影响及FAO建议值适用性评价

作为计算太阳总辐射(R_s)的主要公式,Angstrom公式参数(a、b)的合理取值是计算参照腾发量(ET₀)的重要前提。针对FAO所提出的a、b建议值(a=0.25、b=0.5)在中国无辐射观测资料地区被大量使用,而其合理性尚未得到系统评价的情况,基于中国104个地面站的观测数据,在逐月时间尺度上,讨论了a、b变化对ET₀的影响,分析了a、b的地区分布规律,评价了FAO建议值所导致的ET₀计算误差,进而阐明了该建议值在中国7个区域的适用性。提出了无辐射资料情况下a、b的地区综合取值方法。主要研究结论是:①参数a、b偏差对ET₀的计算有重要影响,在中国无资料地区采用FAO建议值将导致较大的太阳总辐射(R_s)和ET₀计算误差。②大多数站点,a的率定值较FAO建议值明显偏小,而b的率定值明显偏大。新疆地区和华南地区a、b率定值分布比较集中,而在其它区域比较分散。③FAO建议参数值在东北、西北和新疆3个区域计算ET₀的适用性较好,而在西南和华南两个区域的适用性很差,计算的ET₀偏高较大。④提出的地区综合取值方法,能使R_s和ET₀的计算精度较FAO建议值显著提高。     

基于可见—近红外反射光谱的典型农田重金属污染风险分类研究

对于人为因素或自然因素造成的农田土壤重金属元素污染,需要进行大面积的土壤环境质量调查和分类管控,然而传统的采样测试方法存在工作量大、代价高等问题。可见—近红外（Vis-NIR）反射光谱是一种快速低成本获取土壤理化信息的手段。为研究Vis-NIR反射光谱预测模型划分土壤重金属污染风险类别的能力,文章以典型人为污染地区（浙江温岭）和典型地质高背景地区（广西横县）的390份农田土壤为样本,测定8种重金属元素（As、Cd、Cr、Cu、Hg、Ni、Pb和Zn）的含量和pH值,并测定土壤Vis-NIR光谱。使用偏最小二乘（PLS）和支持向量机（SVM）算法建立回归模型,对土壤重金属含量和pH值进行预测,并基于预测值进行土壤重金属污染风险分类。结果显示,温岭土壤主要污染元素Cd和Cu的光谱模型回归预测偏差（RPD）分别为1.23和1.19,预测机制与有机质有关。横县土壤主要污染元素As和Cd的RPD分别为1.98和1.93,预测机制与铁氧化物和粘土矿物有关。地质高背景土壤重金属与铁氧化物的正相关性普遍较强,使得光谱模型对重金属含量预测准确度较高。温岭和横县土壤pH值的光谱模型RPD分别为1.76和1.68。土壤重金属污染风险光谱分类的总体 准确度分别为75.0%~100%（温岭）和80.0%~100％（横县）。将Vis-NIR光谱与遥感技术相结合,对农田土壤重金属污染风险进行快速分类总体是可行的。     

Mixture models and atypical values

The resolution of a mixture of two or more populations into its component distributions may be markedly influenced by one or a few atypical values. The maximum likelihood solution effectively assigns (part of) each observation to one or another of the components via the posterior probabilities, even though the observation may be widely discrepant from all components. This paper presents a modification of the mixture problem, in which the typicality of each observation is considered, as well as the posterior probabilities, with the contribution of atypical observations being downweighted. The extension to the multivariate case is discussed.     

A Glimpse of Steel Manufacture

Abstract

Abstract

This article explores the relationship between the values that teachers bring to the classroom and their performance. The insights are drawn from the National Science Foundation-funded Finding A Way project that was undertaken by the National Council for Geographic Education. I argue here that without understanding the values and beliefs of classroom teachers, professional development initiatives might, in the end, make little difference in what goes on in the classroom.     

A Teacher's Introduction To Remote Sensing

Abstract

This article is an introduction to remote sensing. It provides the novice with a definition of remote sensing, information about some remote sensing products, data that can be obtained from remote sensing images, what can be done with images, ideas to integrate remote sensing with other subjects, a sample unit using images, and a list of associate areas related to remote sensing. The article also contains information for obtaining remote sensing materials and information and considers values concerns relating to remote sensing.     

Public opinions on biological diversity in Norway: Politics,science, or culture?

Loss of biological diversity is among the most pressing environmental problems facing modern societies. Whereas today much is known about peoples' opinions on climate change, there is still a lack of knowledge regarding how people asses the issue of biological diversity. The article represents a step towards a better understanding of public opinions on the issue of biodiversity, and hence also of the prerequisites and possibilities for a more or less vigorous or legitimate policy on this issue. The analyses show that social background matters for concern about biodiversity, but only to a certain extent: women are less negative towards biodiversity protection than men, the older segments of the population, at least in Norway, are less concerned with biodiversity, and education has only a marginal effect. Hence, to a large extent, political attitudes matter and indicate that concern for biodiversity seems to work by various types of available heuristics whereby a given case is linked to political understandings of other and similar and/or familiar issues. The inclusion of other political variables (local decision-making) and what the authors label ‘cultural variables’ (e.g. view of nature and trust in science) seem also to matter decisively for attitudes towards biodiversity.