土壤全量多元素的ICP-AES分析

本文介绍土壤中多元素的ICP-AES分析方法。文中详细叙述了操作步骤,并给出了分析的精密度、准确度、检出限的数据及与其它分析方法的比较、讨论了干扰元素的影响及其消除的措施。     

云锡矿尘及氡子体暴露诱发大鼠肺癌的实验研究

本文报道了给大鼠气管内灌注云锡矿尘及大鼠吸氡子体诱发肺癌的实验研究。结果表明,单纯灌尘的大鼠发癌率随矿尘中砷含量的增加而增加;在氡子体累积暴露量为1.75—6.59×10MeV·h/L 条件下进行的慢性吸入实验中,有10～20%的大鼠发生肺癌,吸氡子体复合灌尘时的发癌率大体相当于相应水平单纯吸氡子体与单纯灌尘时的发癌率之和。     

试论钱学森的“大成智慧学”-谨以此文祝贺钱老九十寿辰

“大成智慧学”是新世纪的需要，“必集大成 ，才能得智慧！”“大成智慧”的核心是科学与哲学的结合。为此，不仅要利用人——机结合的思维体系，下苦功夫掌握广博的知识、经验、信息，还要从实际出发，实事求是，善于思考，反复实践，努力树立起反映新世纪的世界观、人生观、科学观、方法论。     

Cross-layer design for resource allocation in 3G wireless networks and beyond

Cross-layer design approaches are critical for efficient utilization of the scarce radio resources with QoS provisioning in the third-generation wireless networks and beyond. Better system performance can be obtained from information exchanges across protocol layers, which may not be available in the traditional layering architecture. This article provides an overview of cross-layer design approaches for resource allocation in 3G CDMA networks, summarizes state-of-the-art research results, and suggests further research issues. In addition, a cross-layer design approach for real-time video over time-varying CDMA channels is proposed, where link layer resource allocation benefits from information in both the application and physical layers. Simulations results are given to demonstrate the effectiveness of the proposed approach.     

Cluster‐based coordination scheme for cooperative cognitive radio networks

In this paper, a cluster‐based two‐phase coordination scheme for cooperative cognitive radio networks is proposed considering both spectrum efficiency and network fairness. Specifically, candidate secondary users (SUs) are first selected by a partner selection algorithm to enter the two‐phase cooperation with primary users (PUs). In phase I, the selected SUs cooperate with PUs to acquire a fraction of time slot as a reward. In phase II, all SUs including the unselected ones share the available spectrum resources in local clusters; each of which is managed by a cluster head who participated in the cooperation in phase I. To improve the total network utility of both PUs and SUs, the maximum weighted bipartite matching is adopted in partner selection. To further improve the network performance and communication reliability, network coding is exploited during the spectrum sharing within the cluster. Simulation results demonstrate that, with the proposed cluster‐based coordination scheme, not only the PUs' transmission performance is improved, but also SUs achieve spectrum access opportunities. Copyright © 2015 John Wiley & Sons, Ltd.     

有限方向检测法在高程点线矛盾检查中的应用

地形图生产中,对于人工采集的等高线和高程点,需要检查两者之间是否存在矛盾。在介绍常规高程点线矛盾检查方法的基础上,提出了一种有限方向检测法检查高程点线矛盾检查的手段,阐述了有限方向检测法的基本原理,给出提高方法运行速度和节约方法占有内存的措施。并编写了相应的程序,通过实际生产验证表明:该方法检查结果正确,检查速度快,适应性强,很少发现漏判,没有发现误判。     

铁路隧道衬砌机制砂混凝土耐久性能试验研究

目前天然河砂资源紧缺,基于叙毕铁路川滇段某标段隧道工程大量采用机制砂施作隧道衬砌混凝土的现状,为揭示铁路隧道衬砌机制砂与河砂混凝土耐久性能方面的差异,考虑细骨料、混凝土强度等级、养护条件等因素的影响,进行电通量与碳化试验,研究不同因素对混凝土抗氯离子渗透性能和抗碳化性能的影响。试验结果表明:相同强度等级的机制砂混凝土耐久性能指标高于河砂混凝土约6%~10%,且混凝土耐久性能随强度等级的提高得到不同程度的提升;标准养护条件下混凝土耐久性能明显优于隧道内自然养护条件下混凝土,其抗氯离子渗透性能和抗碳化性能分别提升约43%、37%。根据试验结果,在隧道施工过程中需加强衬砌混凝土养护以增强其耐久性能。     

Age-Hardening Behavior in the Spray Formed Ni-based Superalloy

主要研究了喷射成形镍基高温合金的微观组织特征和时效硬化行为。合金经1140 ℃,8 h固溶处理,然后在780 ℃,2~12 h时效处理。分别测试了合金显微硬度、析出相大小及形态、电导率和正电子湮没寿命与时效时间的关系。结果表明,在时效8 h时,显微硬度达到最大值,此时γ'' 长大到临界尺寸56 nm。然而,时效时间超过8 h,合金显微硬度降低,这是由于γ'' 长大超过了其临界尺寸。随着时效时间延长至6 h,电导率快速增加到其最大值32%IACS,但是正电子湮没寿命则降低到最小值149 ps,在时效时间为10 h时,正电子湮没寿命达到最大值297 ps。这是由在时效过程中γ'' 尺寸的变化以及缺陷浓度的变化引起的     

离子交换膜电解回收含镍废水中镍的研究

采用双膜三室电解法处理含镍废水,阴极电沉积金属镍,同时可得副产品盐酸,并研究各因素对电解过程的影响规律。结果表明:在电流密度为60 A/m2,p H为4,温度为40℃,Ti/Ir Ta作为阳极,电解时间为4 h条件下,镍回收率可达82.3%,电流效率高达85.3%,中隔室盐酸浓度为0.5 mol/L,处理后出水经离子交换富集循环使用。     

聚氨酯改性氯化聚丙烯及其应用研究进展

介绍了聚氨酯改性氯化聚丙烯的制备方法,从物理改性和化学改性两方面评述了聚氨酯改性氯化聚丙烯的研究进展;简要叙述了聚氨酯改性氯化聚丙烯的应用。