基于数字属性和符号属性混合数据的网络异常入侵检测方法

1IntroductionIntrusion detection systems(IDS)can be catego-rizedinto two types bytheir detection algorithms:mis-use detection and anomaly detection.Misuse detectiondefines known attack signatures(using expert know-ledge),and tries to find the ones that ma…     

数学分析教学中加强学生对反例的学习和运用

数学分析中有许多重要的典型反例,这些反例是数学分析理论不可缺少的重要组成部分,教师在教学中要重视反例的教学,加强学生对反例的学习和运用,提高学生运用反例解决问题的能力.     

误用检测攻击模式表示技术研究

误用检测技术由于其检测效率高、误报警率低，是目前实际IDS系统主要采用的技术，该技术是采用适当的方法描述已知攻击模式，与已知攻击模式匹配的事件认为是入侵，因此，攻击模式的表达是误用检测的主要研究问题。本文主要总结攻击模式的表示方法，并对各种方法进行分析。     

引力势能与太阳温度

根据引力理论和维里定理 ,对太阳温度做了简单的理论推导和估算     

基于聚类分析的非监督式异常检测研究

传统的异常检测方法要求训练数据集完全由已标记为正常的实例所构成，但在实际应用中，很难得到这样的训练数据集。本文提出了一种基于聚类分析的非监督式异常检测方法，该方法的优点在于不需要任何标记数据，并且能够实现网络连接数据的实时检测。实验采用KDD99数据集进行测试，结果表明，该方法具有比较高的检测性能。     

中国西部地区重力位能与板内变形动力

重力位能及其重力浮力是大陆板块内部重要的构造变形动力.中国西部地区构造变形以垂向抬升、横向拉伸和压缩为主要特点，其重力位能及重力浮力分布，深刻影响着西部板内变形动力学机制.地震学和重力学方法计算表明中国大陆西部蕴藏较大的重力位能，其中青藏高原重力位能在2×1012～7×1012N/m之间.地壳重力位能变化导致的重力浮力，是板内变形的主要构造力.在一定流变学条件下，重力位能足以产生青藏高原活动地区的构造形变.     

Electrical conductivity of melts: implications for conductivity anomalies in the Earth's mantle

Magmatic liquids, including silicate and carbonate melts, are principal agents of mass and heat transfer in the Earth and terrestrial planets, and they play a crucial role in various geodynamic processes and in Earth''s evolution. Electrical conductivity data of these melts elucidate the cause of electrical anomalies in Earth''s interior and shed light on the melt structure. With the improvement in high-pressure experimental techniques and theoretical simulations, major progress has been made on this front in the past several decades. This review aims to summarize recent advances in experimental and theoretical studies on the electrical conductivity of silicate and carbonate melts of different compositions and volatile contents under high temperature and pressure. The electrical conductivity of silicate melts depends strongly on temperature, pressure, water content and the ratio of non-bridging oxygens to tetrahedral cations (NBO/T). By contrast, the electrical conductivity of carbonate melts exhibits a weak dependence on temperature and pressure due to their fully depolymerized structure. The electrical conductivity of carbonate melts is higher than that of silicate melts by at least two orders of magnitude. Water can increase electrical conductivity significantly and reduce the activation energy of silicate melts. Conversely, this effect is weak for carbonate melts. In addition, the replacement of alkali-earth elements (Ca²⁺ or Mg²⁺) with alkali elements causes a significant decrease in the electrical conductivity of carbonate melts. A distinct compensation trend is revealed for the electrical conductivity of silicate and carbonate melts under anhydrous and hydrous conditions. Several important applications of laboratory-based melt conductivity are introduced in order to understand the origin of high-conductivity anomalies in the Earth''s mantle. Perspectives for future studies are also provided.     

Equatorial aurora: the aurora-like airglow in the negative magnetic anomaly

The most fantastic optical phenomena in the Earth''s upper atmosphere are the auroras. They are highly informative indicators of solar activity, geomagnetic activity, upper atmospheric structures and dynamics, and magnetospheric energetic particles. An area where the geomagnetic field differs significantly from the expected symmetric dipole, such as at the South Atlantic Anomaly, where the magnetic field intensity is low, gives rise to stronger precipitation of energetic particles into the upper atmosphere. Impact excitation and the subsequent airglow emissions exhibit aurora-like dynamic signatures. Nomenclatures of nonpolar aurora or equatorial auroras are similar to those used with the polar auroras owing to their similar excitation mechanisms. This paper provides an overview of the knowledge and the challenges concerning auroral activity at the South Atlantic Anomaly, or more generally, at the negative magnetic anomaly. We emphasize systematic investigation of the equatorial auroras to reveal the temporal and spatial evolution of the magnetic anomaly and the behaviour of energetic particles in near-Earth space.     

Precision measurement of the Newtonian gravitational constant

The Newtonian gravitational constant G, which is one of the most important fundamental physical constants in nature, plays a significant role in the fields of theoretical physics, geophysics, astrophysics and astronomy. Although G was the first physical constant to be introduced in the history of science, it is considered to be one of the most difficult to measure accurately so far. Over the past two decades, eleven precision measurements of the gravitational constant have been performed, and the latest recommended value for G published by the Committee on Data for Science and Technology (CODATA) is (6.674 08 ± 0.000 31) × 10⁻¹¹ m³ kg⁻¹ s⁻² with a relative uncertainty of 47 parts per million. This uncertainty is the smallest compared with previous CODATA recommended values of G; however, it remains a relatively large uncertainty among other fundamental physical constants. In this paper we briefly review the history of the G measurement, and introduce eleven values of G adopted in CODATA 2014 after 2000 and our latest two values published in 2018 using two independent methods.     

浙江省2003年夏季异常高温气候及其成因分析

本文基于浙江省夏季高温、副热带高压、台风、太阳黑子活动、回归温度等资料，利用距平、不同等级高温日数、与历史极值比较等手段及其方法，所得结果表明：浙江省2003年夏季高温明显偏高，全国偏高2-3℃的区域仅仅出现在浙江省中东部地区；高温强度异常偏强且分布有南强北弱的特点，而以浙江东部地区的高温较为突出；造成浙江2003年夏季高温的主要原因是出梅早、梅期短；控制浙江的副热带高压强大持续稳定；台风影响轻；太阳黑子活动的影响。