试谈高可用性计算机实训室的配置与管理

基于计算机实训教学的需求,重点探讨高可用性计算机实训室的搭建要求、配置特点与管理策略。     

Phosphorus Fractionation and Sorption in P-enriched Soils of Norway

Phosphorus (P) enrichment can lead to imbalance in nutrient availability and pollution of terrestrial and aquatic ecosystems. Hence studies were carried out to investigate fractionation and sorption of P in eleven P-enriched soils collected from different agro-climatic sites in Norway. Different P fractions viz. total, organic, inorganic (easily soluble P, Fe-P, Al-P, Ca-P and occluded P), P_w (water extractable), and NH₄-lactate extractable P (P_AL) at the beginning and after the completion of the experiments varied widely among the soils studied, indicating a wide variability of P supplying capacity of these soils. Soluble P was positively correlated to Ca-P (r = 0.94; P < 0.001), P_w (r = 0.87; P < 0.001), pH (r = 0.79; P < 0.01) and P_AL (r = 0.79; P < 0.01), whereas it was negatively correlated with ammonium oxalate-extractable Al (Al_ox) (r = ?0.68; P < 0.05). Iron-P was only moderately related to Al_ox(r = 0.64; P < 0.05) and P_ox(r = 0.70; P < 0.05), whereas it was not related to any of the other parameters tested. The α [α = P_ox/(Fe_ox + Al_ox)] was highly correlated with P_AL (r = 0.93; P < 0.001), pH (r = 0.87; P < 0.001), inorganic P (r = 0.80; P < 0.01) and P_w(r = 0.77; P < 0.01) but moderately to total P (r = 0.71; P < 0.05). Adsorption data fitted well to the Langmuir equation for most soils. The P affinity constant (k), adsorption maximum (b) and thus maximum buffering capacity (mbc) and adsorption isotherm of P were highest in the sandy clay soil from Øsaker, which also contained high amounts of Fe, Al and clay particles and the lowest in sandy soil from Vestrålen, which contained very high initial P_ALand the lowest content of Fe, Al, silt and clay among all the soils studied. The P affinity constant (k) was correlated positively and significantly to clay content (r = 0.66; P < 0.05), whereas mbc was correlated positively and significantly to clay content (r = 0.63; P < 0.05) and ammonium oxalate-extractable Fe (Fe_ox) (r = 0.63; P < 0.05). Phosphorus desorption of the soils varied widely depending on the initial P status and texture of the soils. Phosphorus desorbed by NH₄-lactate was many fold higher as compared to CaCl₂ in most soils.     

基于VMware的高可用性集群在电力信息系统中的应用

在VMware服务器中安装多个虚拟机,分别作为不同服务器的备用机,并且利用心跳信号持续检测物理服务器的工作状态.当物理服务器出现故障时,高可用性集群自动切换服务,使故障服务器的业务迅速平衡地迁移到虚拟机上,也可以把负载过大的服务器上的应用动态地分配到其他负载较小的服务器上,以确保电力信息系统服务的不间断运行.     

具有两类失效状态和休假的串联可修系统

研究了修理工可多重休假的部件串联可修系统,每个部件有两类失效状态。假定部件寿命服从指数分布,部件修理时间和修理工休假时间均服从一般连续分布,利用向量Markov过程理论和Laplace变换的方法求出了系统的可靠性指标。     

手机人机交互界面设计趋势探究

随着技术平准化、手机产业价格竞争的环境出现,手机的人机交互界面(UI)给手机市场提供了新的卖点,同时凭借各企业固有的UI继续提高客户的忠诚度,渴望成为新的产业发展动力。手机UI的新设计与功能开发是根据各种客户群体的喜好及使用习惯而进行的。随着环境和生活方式的多样化,其开发范围和潜力正在无限扩大。这些新的趋势使得界面交互可能不再囿于某个具体产品本身与用户的互动,它可能涉及到与使用环境、其他用户之间的交流。根据对当前手机技术的分析以及对国外在人机交互及相关领域研究的关注,提出了"泛交互"的概念,并对新的趋势、新的设计进行了展望和探讨。     

Yield response of lentil to directly applied and residual phosphorus in a Mediterranean environment

The response of lentil grown under rainfed conditions to directly applied and residual phosphorus (P) was described by a modified Mitscherlich equation, accounting for the effects of rainfall on (1) potential yield, and (2) the availability of soil-P to the crop. The response of lentil yield to directly applied and residual P was studied in two-course cereal–lentil rotational trials under rainfed conditions in a Mediterranean-type environment. Cereal crops were grown at different P application rates during 4 growing seasons at 3 sites, representing different rainfall zones in northwest Syria. Lentil (Lens culinaris Med.) was grown during 4 seasons at the same sites, each lentil crop following a cereal crop. In 3 out of 4 lentil-growing seasons, additional P was applied to lentil in subplots to compare the residual and direct effects of P application. The initial contents of extractable soil-P (P-Olsen) were low at all sites, in the range of 2–5 ppm P. Under the conditions of the experiments, lentil appeared to benefit slightly more from P applied to the preceding wheat crop (residual P) than from directly applied P. It is shown that the modified Mitscherlich equation could be used as a basis for P fertilizer recommendations for rainfed farming. As for lentil, it was concluded that a single application of P to the wheat crop in a wheat/lentil rotation could reduce the cost of lentil production, without reducing lentil yield.     

SFFS：低延迟的面向小文件的分布式文件系统

社交网站和电子商务等网络服务发展迅速,这类服务需要存储大量图片、音乐、微博文本等小文件。传统的分布式存储系统,如HDFS（Hadoop distributed file system）,是面向大文件而设计的,在存储小文件时会产生元数据开销过大,访问延迟较高等问题,不能适应存储海量小文件的应用环境。分析了TFS（Taobao file system）的系统架构和读写流程,发现TFS在每次读/写过程中至少要建立3次网络连接,增大了读写延迟。针对海量小文件存储带来的挑战和TFS存在的问题,提出了一种新的低延迟、高可用的面向海量小文件的分布式存储方案,并实现了分布式文件系统SFFS（small-file file system）。性能测试表明,SFFS和TFS相比,写延迟降低了76.6%,读延迟降低了约10%。通过对系统结构的分析,相比于TFS,SFFS在中心节点的负载更轻,失效恢复更快,在可用性方面更有优势。     

采用TTT变换的混联系统预防维修策略分析

在年龄更换策略的基础上,考虑复杂的混联系统,以平均期望损失和系统的平均可用度2个指标构建一个预防维修周期的目标优化模型。重点运用TTT变换函数精确求解该目标优化模型,从而确定出混联系统的预防周期。以数值实例阐述了该决策过程,说明该方法的正确性和可行性。     

柴达木盆地涩北地区第四系泥岩型生物气储层孔隙有效性评价

通过低场核磁共振实验分析了柴达木盆地涩北地区第四系泥岩型生物气储层在饱和水状态及渐变烘干温度状态下的T₂谱,明确了孔隙流体的核磁响应特征,以评价孔隙的有效性。研究结果表明： ①核磁共振实验是以饱和水状态T₂谱为基础,采用正态分布函数拟合构建了离心束缚水T₂谱,确定了可动流体和毛管束缚流体T₂截止值,用于划分出流体类型并开展了孔隙有效性评价。②研究区岩样饱和水状态T₂谱谱峰呈左小右大的形态,右峰幅度值远大于左峰,占T₂谱幅度值90%以上;随着烘干温度的升高,T₂谱幅度减小且左移趋势明显;束缚水T₂谱形态近似于正态分布,起始位置与饱和水状态的T₂谱基本重合。③研究区可动流体T₂截止值T_{2 C1}平均为3.3 ms,毛管束缚流体T₂截止值T_{2 C2}平均为1.8 ms;孔隙流体包括可动水、毛管束缚水和黏土束缚水,黏土束缚水T₂小于T_{2 C2},毛管束缚水T₂大于T_{2 C2}且小于T_{2 C1},可动流体T₂大于T_{2 C1};毛管束缚水含量最高,黏土束缚水其次,两者占总孔隙流体的84.43%～95.06%,可动水含量低。④研究区储层有效孔隙占总孔隙的54.99%,主要为毛管束缚孔,黏土束缚孔为无效孔隙;黏土含量越高,有效孔隙度越小。     

基于机会网络中社交关系的转发机制

由于现有的机会网络转发机制不能完全适应社会网络中基于社交关系的判断与分析,为此通过建立社交关系的分类,构建机会网络中的社会关系树结构模型,提出了一种新的转发机制。该机制设置了节点权重值,由节点所处的层次和社会关系的可利用性及可靠性决定。通过路径权重值,选择最有价值的路径进行消息的传递。通过仿真实验,所提出的转发机制有效地降低了网络中的消息副本数和降低了路由开销。