福建煤炭集团结构调整问题初探

本文在简要介绍福建煤炭集团的战略定位和发展趋势的基础上 ,分析了福建煤炭集团产业结构存在的主要问题 ,提出了当前福建煤炭集团结构调整的对策思考。     

Combined shape and sizing optimization of truss structures

 In this paper, an evolutionary optimization method is presented for weight minimum problem of a 3-dimensional truss structure in terms of nodal coordinates and element cross-sectional areas. The structure is subject to stress, local buckling and displacement constraints. Two types of design variables with different natures are optimized separately: (1) a fully stressed design (FSD) and scaling techniques are applied to sizing variables and (2) the evolutionary node shift method is applied to shape variables. Alternating procedure is utilized to couple the two types of variables and to combine the results. The optimum solution is achieved gradually from the initial configuration design. Two typical truss structures are examined to illustrate the validity of the method. Received: 22 October 2001 / Accepted: 04 June 2002 This research work is supported by the National Natural Science Foundation of China under the guarantees no. 10072050 and 10172072, respectively.     

地热、温泉水利用中氡的防护

地热作为一种比较经济、方便的新能源的同时,也给公众和环境带来辐射影响。本文介绍了地热和温泉水中~(222)Rn 的放射性水平及其对人体健康的影响,对地热、温泉水利用中氡的防护措施提出了一些建议。     

土壤γ辐射剂量率间接测量中的^222Rn析出和含水量修正

本文针对Ｂｅｃｋ公式的局限性，对土壤的含水量和＾２２２Ｒｎ析出引起的γ辐射剂量率变化进行了修正。通过浙江省５７６组测量数据的实验拟合，给出了剂量率计算的修正公式。该公式应用到浙江省自身的测量数据上，使计算的总体均值与实测均值仅相差０．８％；每一点位的计算值与实测值相比，平均仅相差３．４％，其比值离散性与实验误差相一致。而Ｂｅｃｋ公式的计算结果与实测剂量率相比较，以上两项分别偏离＋１０％和１５．２％     

A new family of yeast genes implicated in ergosterol synthesis is related to the human oxysterol binding protein

We have identified three yeast genes, KES1, HES1 and OSH1, whose products show homology to the human oxysterol binding protein (OSBP). Mutations in these genes resulted in pleiotropic sterol-related phenotypes. These include tryptophan-transport defects and nystatin resistance, shown by double and triple mutants. In addition, mutant combinations showed small but apparently cumulative reductions in membrane ergosterol levels. The three yeast genes are also functionally related as overexpression of HES1 or KES1 alleviated the tryptophan-transport defect in kes1Δ or osh1Δ mutants, respectively. Our study implicates this new yeast gene family in ergosterol synthesis and provides comparative evidence of a role for human OSBP in cholesterol synthesis.     

单齿泵削角的优化设计

给出了单齿泵削角的优化模型与计算实例，并对理论设计与实验进行了比较分析。     

液闪测氡中闪烁杯的氡气泄漏

本文简要介绍了液闪测氡中氡气自闪烁杯泄漏的实验结果。实验中对三种玻璃闪烁杯盖的密封性能作了检查,结果表明,这三种闪烁杯均不能满足液闪法测氡中对氡的密封要求。采用一层1mm 厚的橡胶垫片和一层0.01mm 厚的铝化聚脂膜作衬垫,代替原来的聚乙烯或纸板衬垫,解决了其中两种闪烁杯的氡气泄漏问题。建议在使用商品闪烁杯测氡时,应首先检查其对氡的密封性,必要时需采取补救措施,以保证测量结果的可靠性。