Comparative analysis of extreme ultraviolet solar radiation proxies during minimum activity levels

Four extreme ultraviolet(EUV)solar radiation proxies(Magnesium II core-to-wing ratio(MgII),Lymanαflux(Fα),10.7-cm solar radio flux(F10.7),and sunspot number(Rz))were analyzed during the last four consecutive solar activity minima to investigate how they differ during minimum periods and how well they represent solar EUV radiation.Their variability within each minimum and between minima was compared by considering monthly means.A comparison was also made of their role in filtering the effect of solar activity from the critical frequency of the ionospheric F2 layer,foF2,which at mid to low latitudes depends mainly on EUV solar radiation.The last two solar cycles showed unusually low EUV radiation levels according to the four proxies.Regarding the connection between the EUV“true”variation and that of solar proxies,according to the foF2 filtering analysis,MgII and Fαbehaved in a more stable and suitable way,whereas Rz and F10.7 could be overestimating EUV levels during the last two minima,implying they would both underestimate the inter-minima difference of EUV when compared with the first two minima.

CMLP: Exploiting Caches at Multiple Levels of Proxies to Enhance Seamless Mobility Support in Information-Centric Networks

The recent evolution of the Internet towards "Information-centric" transfer modes has renewed the interest in exploiting proxies to enhance seamless mobility. In this work, we focus on the case of multiple levels of proxies in ICN architectures, in which content requests from mobile subscribers and the corresponding items are proactively cached to these proxies at different levels. Specifically, we present a multiple-level proactive caching model that selects the appropriate subset of proxies at different levels and supports distributed online decision procedures in terms of the tradeoff between delay and cache cost. We show via extensive simulations the reduction of up to 31.63% in the total cost relative to Full Caching, in which caching in all 1-level neighbor proxies is performed, and up to 84.21% relative to No Caching, in which no caching is used. Moreover, the proposed model outperforms other approaches with a flat cache structure in terms of the total cost.

Relationship between pollen assemblages and organic geochemical proxies and the response to climate change in the Zhuye Lake sediments

This paper examines the relationship among organic geochemical proxies （TOC, C/N ratio and ~13C） and pollen assemblages in Zhuye Lake sediments since the Late Glacial. Results show that the reaction extent of organic geochemical proxies and pollen as- semblages to environment changes are different. Organic geochemical proxies are sensitive to overall environmental change, while pollen assemblages indicate detailed information of environmental change. For the entire sedimentary section （except the sand layer fi＇om the bottom of the section）, when values of TOC, C/N ratio and total pollen concentrations are high, 813C values are low, and vice versa. The different responses of organic geochemical proxies and pollen records in Zhuye Lake are mainly due to their different sensitivity and diverse influencing factors in different environmental conditions.

Coral Ba/Ca and Mn/Ca Ratios as Proxies of Precipitation and Terrestrial Input at the Eastern Offshore Area of Hainan Island

Geochemical ratios in coral reef skeletons could be used as proxies to reconstruct past climatological and environmental records in data-poor regions. Using a 103-year data set(1902 to 2005), the annual variations in Ba/Ca and Mn/Ca ratios of Porites lutea skeletons at an eastern offshore area of Hainan Island(19?12'28.4''N, 110?37'38.8''E) were analyzed using inductively coupled plasma-optic emission spectrometry(ICP-OES). The analysis results showed that Ba/Ca ratios varied from a minimum of 3.120 μmol mol^(-1) in 1903 to a maximum of 10.064 μmol mol^(-1) in 1944, with an average of 5.256 μmol mol^(-1). Mn/Ca ratios varied from 0.206 to 5.708 μmol mol^(-1) with an annual average of 1.234 μmol mol^(-1), with peak values in 2001, 1964 and 1932, that correlated with strong rainfall events caused by typhoons. Variation in Ba/Ca and Mn/Ca ratios were compared with available river discharge and precipitation records, providing insight into past climatological events. Human activities and their indirect effects could impact the strength of the relationship between Ba/Ca and Mn/Ca ratios and observed precipitation and terrestrial input in the future.

Influence of Proxies on the Reported Frequency of Falls, Fear of Falling and Activity Restriction in Older People

Introduction: In older populations, the help of a third person may be necessary for a certain number of individuals in order to fill in questionnaires. The influence of this assistance on the collected information can raise questions, among others concerning the concordance between the information provided by the persons themselves and by their proxies, or the introduction of a potential bias. Our study’s objective is to examine, among older people, the differences in the reported frequency of falls, fear of falling and activity restriction due to fear of falling, according to the fact that people had filled in a questionnaire with or without the help of a third person. Methods: The data used come from the secondary analysis of a cross-sectional survey using a self-administered questionnaire and conducted in 2006 in a Belgian semi-rural town among non-institutionalised persons aged 65 years and over. Results: Among the 501 questionnaires, 16.4% were filled in with the help of another person. In bivariate analysis, the persons who needed help reported fall history, fear of falling and activity restriction significantly more often. In multivariable analysis, when considering concurrently the covariates (sex, age, living alone and fall history for fear of falling and for activity restriction), the influence of having received help to fill in the survey was only significant for activity restriction. Conclusion: Our study shows that it is important to know whether or not a person has received help to fill in a questionnaire. This can actually influence the reported frequency of certain outcomes, even, for activity restriction, when considering simultaneously the effect of other covariates. Given the current and future ageing of our populations, it seems that more extensive exploration is needed of the influence of proxies on the collected information about falls, fear of falling and activity restriction among older people.

Statistical Reconstruction of the Antarctic Oscillation Index Based on Multiple Proxies

Based on multiple proxies from the Southern Hemisphere, an austral summer (December-January-February: DJF) Antarctic Oscillation Index (AAO) since 1500 A.D. was reconstructed with a focus on interannual to interdecadal variability (<50 a). By applying a multivariate regression method, the observational AAO-proxy relations were calibrated and cross-validated for the period of 1957 89. The regressions were employed to compute the DJF-AAO index for 1500 1956. To verify the results, the authors checked the explained variance (r 2 ), the reduction of error (RE), and the standard error (SE). Cross-validation was performed by applying a leave-one-out validation method. Over the entire reconstruction period, the mean values of r 2 , RE, and SE are 59.9%, 0.47, and 0.67, respectively. These statistics indicate that the DJF-AAO reconstruction is relatively skillful and reliable for the last ～460 years. The reconstructed AAO variations on the interannual and interdecadal timescales compare favorably with those of several shorter sea level pressure (SLP)-based AAO indices. The leading periods of the DJF-AAO index over the last 500 years are ～2.4, ～2.6, ～6.3, ～24.1, and ～37.6 years, all of which are significant at the 95% level as estimated by power spectral analysis.

Phytocenoses at Environments Contact Sites as Proxies of Climate Dynamics with Time (East Siberia, Russia)

Usage of methods for determination of long-term trends of the dynamics of vegetation formation on the background of climate changes becomes more and more important at modern stage of the assessment of natural systems development. This causes to researchers a series of problems from choice of conceptual base to notions and terms of the processes identified and of state of vegetation of different environments. Solution of such a task results inevitably in necessity to correct the understanding of existing processes occurring in the vegetation cover. It allows establishing a direction of their development in the system of natural factors of any territory. As a result, we have base for determination of age, site and role of current state of phytocenoses in successional systems. It is necessary for this to reveal the peculiarities of phytocenoses composition and formation due to climate dynamics and to determine a period of ecosystems homeostasis, especially for phytocenoses of contact natural conditions. Optimal values of phytocenoses diversity, like one of whole biosystems, depend on the amount of resource in the environment, on stability degree and on evolutional development of cenoses due to ecological, micro-evolutional and evolutional processes.

Late Holocene Environmental History of Lake Victoria Basin： Evidence from Geochemical Proxies

Sedimentary TOC （total organic carbon）, TN （total nitrogen） and C/N （carbon/nitrogen） at selected sites of Lake Victoria basin have provided evidence of phytoplankton productivity, input of nitrates and allochthonous （land） plant materials/catchment destruction in the basin during the late Holocene period （last 4,000 years to present）. TOC and TN in the sediment cores were determined using EuroEA3000 Series Elemental Analyser and radiocarbon dating done using AMS （accelerator mass spectrometry） standard method. Results showed that TOC （13.45%-20.78%） and TN （1.07%-1.92%） values were higher at Napoleon Gulf from about 4,186 years before present （ca. 4,186 yr. BP） to present than at inlet of river Kagera （TOC： 3.27%-6.32% and TN： 0.30%-0.59%） from about 190 years before present （ca. 190 yr. BP） to present. Generally TOC and TN had a negative correlation （r = -0.37, p = 0.04, n = 32） at Napoleon Gulf in the last 4,186 years to present signifying that C/N ratios were governed mostly by phytoplankton productivity which markedly increased during some periods in the last 370 years to present possibly as a result of increased input of nitrates. However, the periods from about 4,186 years to 1,684 years before present （ca. 4,186 yr. BP to 1,684 yr. BP） and some periods between the last 370 years to present indicated increased input of allochthonous plant materials/catchment destruction. On overall, there was a positive correlation between C/N and TOC at inlet of river Kagera （r = 0.57, p = 0.01, n = 20） in the last 190 years to present possibly signifying that C/N ratios were governed mainly by input of allochthonous plant materials hence increased catchment destruction. Input of land plant materials （catchment destruction） along Kagera basin declined during some period after 1950 AD. However the most recent years have shown increased input of land plant materials （catchment destruction） in Kagera basin.

Sharing Smart Card Authenticated Sessions Using Proxies

This paper discusses an approach to share a smart card in one machine with other machines accessible on the local network or the Internet. This allows a user at a browser to use the shared card remotely and access web applications that requiresmart card authentication. This also enables users to access these applications from browsers and machines that do not have the capability to use a smart card. The approach uses proxies and card reader code to provide this capability to the requesting device.Previous work with remote or shared smart card use either requires continuous access to the smart card machine or specific client software. The approach in this paper works for any device and browser that has proxy settings, creates minimal network traffic and computation on the smart card machine, and allows the client to transfer from one network to another while maintaining connectivity to a server. This paper describes the smart card sharing approach, implementation and validation of the approach using real systems, and security implications for an enterprise using smart cards.

Triterpenols as Proxies for Tracking the Mangrove Evolution in China

Objective Located at the interface of terrestrial and marine ecosystems, mangroves are particularly sensitive to environmental changes. They provide a sedimentary sink for organic carbon, whereby core samples could provide detailed records of mangrove evolution. Human induced, rapid environmental changes in recent years require a better understanding of the mangrove ecosystems evolution in the past, by reconstructing the past mangrove dynamics using triterpenols recorded in sediments. The aim of our work is to improve the application of triterpenols as biomarkers for mangrove development in long term in China.

Current Networks of Long Proxies for Building Reconstruction Models of the Atlantic Multidecadal Oscillation

Currently available proxies were studied as networks for building reconstruction models of the Atlantic Multidecadal Oscillation (AMO). Only proxies that would double the current record length (backwards in time from AD 1564) were included. We present two proxy networks and corresponding reconstruction (transfer) models, one for tree-growth based proxies only and another for multiproxies. Both of them show a useful match in timing as well as amplitude with the AMO. These model structures demonstrated reasonable model performance (overall r2 = 0.45 - 0.36). The time stability of proxy-AMO relationships was also validated. The new models produced acceptable results in cross-calibration-verification (reduction of error and coefficient of efficiency statistics in 1856-1921 and 1922-1990 vary between 0.41 and 0.21). The spatial distribution of these data series indicate that proxies respond to an AMO-like climatic oscillation over much of the Northern Hemisphere.

Applications of smart proxies for subsurface modeling

Using artificial intelligence(AI) and machine learning(ML) techniques, we developed and validated the smart proxy models for history matching of reservoir simulation, sensitivity analysis, and uncertainty assessment by artificial neural network(ANN). The smart proxy models were applied on two cases, the first case study investigated the application of a proxy model for calibrating a reservoir simulation model based on historical data and predicting well production while the second case study investigated the application of an ANN-based proxy model for fast-track modeling of CO2 enhanced oil recovery, aiming at the prediction of the reservoir pressure and phase saturation distribution at injection stage and post-injection stage. The prediction effects for both cases are promising. While a single run of basic numerical simulation model takes hours to days, the smart proxy model runs in a matter of seconds, saving 98.9% of calculating time. The results of these case studies demonstrate the advantage of the proposed workflow for addressing the high run-time, computational time and computational cost of numerical simulation models. In addition, these proxy models predict the outputs of reservoir simulation models with high accuracy.

Paleo-productivity and petroleum source evaluation of the Nkporo and Awgu shales, Lower Benue Trough, Nigeria: Insight from inorganic geochemistry

The petroleum paleo-productivity and generative potential of the Nkporo and Awgu shales in the Lower Benue Trough (LBT) were studied. Major oxides were determined using Spectro Ciros Inductively-coupled plasma optical emission spectrometer (ICP-OES) while trace and rare earth elements were determined using an ELAN 9000 Inductively-coupled plasma mass spectrometer (ICP-MS). The shales have Co/Ni ratios greater than 0.1 suggesting oil source rocks with more marine source input due to brief marine incursion in the transition zone after deposition. The very low Ni values and moderate V values, and a lack of correlation between the TOC and sulphur content, suggests that the organic matter is of terrestrial Type Ⅲ;and the very low paleo-productivity (Ba/Al and P/Ti ratios) suggests that the organic matter is of terrestrial origin. The low V/Ni values of the Nkporo and Awgu shales (Av. ≈ 4) and the high metal concentrations indicate a matured status. From the K/Rb ratios of the Nkporo (191–259) and Awgu shales (198–261), it can be deduced that the organic matter within the shales experienced a considerable loss of K and the shales are mature to generate gaseous hydrocarbons.

一种航天器在轨环境下结构变形的反演方法

为实现航天器在轨结构变形高效计算,提出一种基于神经网络的结构变形反演方法:借助有限元分析法获得结构在不同温度载荷作用下的变形分布特征,并利用获取的数据对输入和输出间神经网络进行训练,获取高精度的代理模型。利用该模型,可以在轨测量的温度作为输入,实现对航天器结构全场变形的快速反演;可通过引入合适参数的高斯噪声,增强神经网络对于输入误差的适应能力;可用改进的连接权值分析方法,给出确定传感器数量下,实现变形反演精度最高的结构温度测点的布局优化方案。综上,该反演方法具有精度高、实时性强、受输入误差影响小等优点,其应用对于提升遥感卫星的成像质量具有重要意义。

基于代理指标的供水管网抗震改造优化

基于水力模型计算的管网供水量满足率(SSIQ)指标,是评估供水管网震后性能的常用指标。在供水管网抗震改造优化模型中,若采用SSIQ表示优化目标函数,优化求解需进行大量水力模型计算,计算耗时很长。为减小管网抗震改造优化模型的计算量,对节点流量韧性指标(FR)进行了改进,增加了管道破坏漏水能量损失的影响项,提出了一种管网能量指标(Energy Resilience, ER)表示震后管网性能;以ER指标作为SSIQ的代理指标,用于量化抗震改造优化模型的目标函数。仅通过管道地震失效概率、管网震前正常运行工况的水力参数计算ER指标,不必进行震后管网水力模型计算,以期提升优化模型计算效率。以供水管网震后性能最大化和改造费用最小化为目标,以管道抗震改造措施为优化变量,建立了管网抗震改造多目标优化模型,并比较了ER指标、FR指标以及两个拓扑代理指标的替代效果。案例管网应用结果表明,ER指标与SSIQ指标相关系数呈现强相关性,基于ER指标的优化方案与基于SSIQ指标的优化方案的差异小于3%,ER指标优化模型计算时间不足SSIQ指标优化模型计算时间的1%。

基于SSA-BP神经网络的车-轨-桥系统随机振动分析

轨道及桥梁结构参数随机性对车-轨-桥耦合系统的振动影响不能忽略。基于代理模型研究轨道-桥梁间3层弹簧刚度和弹簧阻尼以及桥梁刚度和阻尼的随机性对竖向车-轨-桥耦合系统动力响应的影响。首先,基于经典的车-轨-桥耦合系统力学模型(没有考虑桥墩),采用Monte-Carlo生成2 000个样本集,作为代理模型的训练集。然后,对比SSA-BP(麻雀优化BP算法)与传统BP神经网络、GA-BP神经网络(遗传优化BP算法)对车辆和桥梁响应的预测精度,同时探讨样本数量以及Levenberg-Marquardt和Bayesian Regulation训练算法对SSA-BP神经网络预测精度的影响。最后,假定各随机参数概率分布规律服从高斯型正态分布,所有随机参数变异系数均分为0.05、0.10、0.15、0.20、0.25等5个级别,采用所提出的SSA-BP神经网络研究轨道及桥梁的刚度和阻尼变化对车辆和桥梁响应极值的影响。结果表明:与经典的车-轨-桥耦合系统力学模型相比,所提出的代理模型具有更高的计算效率;SSA-BP模型对车辆和桥梁响应的预测精度高于GA-BP模型,GA-BP模型的预测精度高于传统的BP模型;SSA-BP模型采用Levenberg-Marquardt训练算法对车辆和桥梁响应的预测精度优于Bayesian Regulation训练算法的预测精度;道砟和桥梁之间弹簧刚度的随机变化对桥梁随机振动响应尤为明显;钢轨和轨枕之间弹簧刚度的随机性对车体响应的影响不可忽视,而桥梁刚度和阻尼随机性对车体的影响可不考虑。研究成果可为车轨桥系统随机振动响应预测进一步研究提供依据和参考。

委托代持担保物权的法律效力

在特定的交易模式中,担保物权可由他人代为持有。为使金融交易方式更加灵活便捷,应缓和担保物权设立上的从属性,允许为将来债权提供担保,在担保物权可得实现之时,主债权真实存在即可。在权利归属认定中,法院不宜恪守于权利登记内容,在不影响第三人权益的前提下,应尊重当事人间的真实意思表示,认定债权人为实际权利人。倘若名义权利人将登记系统上所登记的债权及担保物权无权处分给第三人,善意取得规则自有适用空间。在担保物权可得实现之时,原则上债权人和受托人均可行使担保物权。在特殊情形下,担保物权的行使主体可由当事人约定。

云存储与区块链相结合的电子数据共享模型研究

为解决公安局、检察院、法院及其他司法单位间电子数据共享中存在的低共享程度、安全性不足以及业务协同效率低下等问题,综合运用云存储、区块链、非对称加密、密文可搜索和代理重加密等技术,提出了一种云存储技术与联盟区块链技术相结合的电子数据共享模型。通过理论分析和模型构建,表明该模型能够在公检法等司法单位之间实现电子数据的高效、安全可靠和可溯源共享,从而提高了司法协同效率,而且为司法领域的数字化改革提供了理论基础和技术框架,对推动司法工作的数字化转型具有重要的理论和实践意义。

基于安全代理的信任服务适配方法

随着各种服务的大规模应用,其带来的协议适配及安全问题日益凸显,如何建立一种信任服务适配的统一机制,提升服务适配的可用性和安全性,已成为相关行业关注的焦点。在网络信任系统建设中,不同服务间组合共同构成一个完整的网络信任服务体系,形成分布式服务系统的场景越来越多。信任服务之间交互频繁,传统的服务适配机制直接移植到信任服务体系中会极大降低交互效率和扩展性,因此提出一种基于安全代理的信任服务适配方法,主要解决的技术问题为服务适配的可用性、扩展性和安全性。该方案能够满足服务状态自适应变化、提升服务适配的可用性,同时确保交互双方的身份以及保证交互过程中数据安全。

陕南勉县寒武系仙女洞组生物礁岩相学及古环境分析

【目的】生物礁演化史上一个关键节点是寒武纪早期广泛出现了后生动物古杯与微生物群落的联合造礁,该造礁群落形成环境和发育条件值得探讨。【方法】以华南板块西北缘汉南—米仓山地区的勉县大河坝剖面为例,对寒武系仙女洞组沉积序列和生物礁临近层位开展了系统的岩相学、沉积学和元素地球化学分析。【结果】岩相学特征显示礁体形成于海退背景下的临滨带环境,建造过程可依次分为钙质微生物主导、古杯动物大量繁盛以及古杯与钙质微生物联合建造三个阶段。生物礁灰岩中的陆源碎屑组分含量向上增多,且颗粒变粗,顶部被中—细砂岩覆盖。【结论】古杯—钙质微生物礁生长过程中对低强度的陆源碎屑输入具有一定的耐受度,当粗粒陆源碎屑组分的持续、高强度输入时将造成生物礁发育终止。本实例揭示了古杯—钙质微生物造礁群落生长过程与海底生态指标的相关性,可为古环境学、沉积学和储层地质学相关研究提供参考。