Determining the operational limits of an anomaly-based intrusion detector

Anomaly-detection techniques have considerable promise for two difficult and critical problems in information security and intrusion detection: detecting novel attacks, and detecting masqueraders. One of the best-known anomaly detectors used in intrusion detection is stide. (Rather than STIDE or Stide or s-tide, we have chosen "stide" in keeping with the way the detector was referred to in the paper by Warrender et al., 1999.) Developed at the University of New Mexico, stide aims to detect attacks that exploit processes that run with root privileges. The original work on stide presented empirical results indicating that data sequences of length six and above were required for effective intrusion detection. This observation has given rise to the long-standing question, "why six?" accompanied by related questions regarding the conditions under which six may (not) be appropriate. This paper addresses the "why six" issue by presenting an evaluation framework for mapping out stide's effective operating space and by identifying conditions that contribute to detection capability, particularly detection blindness. A theoretical justification explains the effectiveness of sequence lengths of six and above, as well as the consequences of using other values. In addition, results of an investigation are presented, comparing stide's anomaly-detection capabilities with those of a competing detector.     

Investigation of intrinsic dielectric breakdown mechanism in Cu/low-/spl kappa/ interconnect system

Using a specifically designed test structure applying human body model electrostatic discharge (ESD) stress, the origin of dielectric breakdown in Cu/low-/spl kappa/ interconnect systems was found to be in interfacial delamination. The interfacial delamination between a SiC capping layer and a SiOC interdielectric layer is responsible for the increase of intermetal dielectric leakage current, causing high current Joule heating as well as catastrophic thermal breakdown. Also, the defect density increased as the delamination becomes wider while the number of ESD zaps increases.     

Surface leakage currents in SiN/sub x/ passivated AlGaN/GaN HFETs

A novel guarded surface leakage test structure is used to isolate the surface and bulk leakage contributions to gate current in AlGaN/GaN HFETs. Passivation with various recipes of SiN/sub x/ always resulted in the commonly observed increase in gate leakage, which was found to be dominated by bulk leakage through the AlGaN. However, high temperature deposited SiN/sub x/ recipes gave a 1-2 orders reduction in surface leakage, whereas low temperature deposition gave an increase. Gate lag measurements were found to correlate closely with the surface leakage component, giving direct evidence that the key device problem of current slump is associated with current flow at the AlGaN surface.     

Influence of dual-frequency plasma-enhanced chemical-vapor deposition Si<Subscript>3</Subscript>N<Subscript>4</Subscript> passivation on the electrical characteristics of AlGaN/GaN heterostructure field-effect transistors

The influence of dielectric stress on the direct current (DC) electrical characteristics of AlGaN/GaN heterostructure field-effect transistors (HFETs) has been investigated. Dual-frequency plasma deposition was used to vary the amount of stress induced by a passivating dielectric on the surface of the devices. Initial data suggested a strong influence from the induced dielectric stress, but the low-frequency, radio-frequency (RF) excitation of the plasma deposition process was found to induce a severe nonreversible damage to the exposed AlGaN surface through N ion bombardment. The consequence is a drastic reduction of the sheet carrier concentration and mobility of the two-dimensional electron gas (2DEG). Subsequently, an alternative damage-free technique using a helium precursor was used to obtain compressive films. Based on the results, uniform dielectric stress has a minimal impact on the polarization charges within the AlGaN barrier.     

柏林的时尚店

2004年春，柏林市中心的弗里德里希大街迎来了时尚品牌小红帽旗舰店的开张。透过商店的全玻立面向室内望去，首先映入眼帘的便是商店地下一层的入口区域，入口旁几组模特衣架后的屏幕上不停地滚动着梦幻般的画面。实际的售卖区位于地下，通过一部单跑楼梯就可到达。售卖区内的墙壁和柜台全部以白色塑料覆面，并在形状和尺寸各不相同的壁龛及中空中展示货物（不仅包括衣物和鞋子，还有图书和CD），甚至连用于划分室内空间的四个柱体上也都设有展示货架。     

Double‐functional characteristics of a surface molecular imprinted adsorbent with immobilization of nano‐TiO2

A new chitosan molecular imprinted adsorbent obtained by immobilization of nano‐TiO₂ on the adsorbent surface (surface‐imprinted adsorbent with nano‐TiO₂) was prepared. Based on photocatalytic reaction and the surface molecular imprinting technology, this new kind of surface‐imprinted adsorbent with immobilization of nano‐TiO₂ can not only adsorb template metal ions but can also degrade organic pollutants. The results showed that, after the nano‐TiO₂ was immobilized on the adsorbent surface, the adsorption ability for the imprinted ion (Ni²⁺) of this new imprinted adsorbent immobilized with nano‐TiO₂ was not affected, but the degradation ability for p‐nitrophenol (PNP) of the surface‐imprinted adsorbent with nano‐TiO₂ increased three‐fold compared with that of the surface‐imprinted adsorbent without nano‐TiO₂, from 23.8 to 76.1% (at an initial PNP concentration of 20 mg·dm^?3). The optimal TiO₂ concentration in the adsorbent preparation was 0.025 g·TiO₂ g^?1 adsorbent. The removal capacity for PNP reached 60.25 mg·g^?1 (at 400 mg·dm^?3 initial PNP concentration) under UV irradiation. The surface‐imprinted adsorbent with nano‐TiO₂ can be reused for at least five cycles without decreasing the removal ability for PNP and the imprinted ion (Ni²⁺). Copyright © 2006 Society of Chemical Industry     

Investigation on bondability and reliability of UV-curable adhesive joints for stable mechanical properties in photonic device packaging

The demand for volume deployment of photonic components has increased, and with it the need to effectively manufacture in a reproducible and cost effective way. Therefore, it is important to keep the assembly process consistent and stable. A simple shear test setup was used in this study to determine the shear force that can be used as an instant indicator to the process stability of fiber arrays assembly. The shear test was then used to study the effect of curing conditions, surface roughness, and reliability test on the adhesion of the adhesive joints of single channel fiber arrays. In general, shear force increases with the curing conditions. However, thermal-induced residue stress during improper controlled curing process might lead to loss in ductility and reliability of the joints. Results showed that rough bonding surface for the coverlid can provide better wettability and enhances the shear strength. However, it might result in incomplete polymerization due to transmission loss of UV radiation during assembly process that was caused by the uneven surface. Furthermore, rough surface can affect the flow of adhesive that could result in incomplete-fills. Adhesives at the surrounding of V-grooves and edges of the joints were attacked by moisture at elevated temperature. This paper also discussed in details the possible failure mechanism of adhesive joints after temperature and humidity test.     

Novel program versus disturb window characterization for split-gate flash cell

In this letter, a new methodology for program versus disturb window characterization on split gate flash cell is presented for the first time. The window can be graphically illustrated in V/sub wl/ (word-line)-V/sub ss/ (source) domain under a given program current. This method can help us understand quantitatively how the window shifts versus bias conditions and find the optimal program condition. The condition obtained by this method can have the largest tolerance for program bias variations. This methodology was successfully implemented in 0.18-/spl mu/m triple self-aligned (SA3) split-gate cell characterization to provide program condition for 32 M products.