The impact of September 11 on psychologists.

A variety of recent research studies have investigated the psychological impact on victims of the devastating events of September 11, 2001. The present study adopted a different approach, instead focusing on the experience of caregivers through a brief survey of state psychological association members. Overall, practitioners described modest but significant changes in both their professional work and their personal lives. Not surprisingly, those respondents working closest to Ground Zero reported the greatest changes. The sample also reported more positive than negative feelings regarding their work in the post-9/11 environment. Although the survey return rate was only 15%, the findings shed light on several important professional issues related to disaster relief, including service utilization, preparedness, and vicarious traumatization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acute stress disorder in diplomats, military, and civilian Americans living abroad following the September 11 terrorist attacks on America.

Can expatriates witnessing the attack of their country from afar develop acute and posttraumatic stress reactions? In Brussels 50 expatriate Americans were surveyed in the 10 weeks following September 11. Of the sample, 10% (n=5) showed acute stress disorder in the 1st week, and 4% (n=2) persisted with traumatic stress indications in the following weeks. All participants showed symptoms of distress, including derealization, reexperiencing the event, avoidance, heightened arousal, trouble working, and assault on world assumptions. For most, symptoms diminished over time. Increased psychological readiness in terms of assessment, prevention, and treatment methods is called for in response to mass terrorism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Image-Moment Based Affine Invariant Watermarking Scheme Utilizing Neural Networks

Watermarking,as a technique for copyright pro-tection,has drawn significant attention from manyresearchers and there has been intensive research inthis areainrecent years.Robustness of watermarkingstill remains one of the key issues for practical appli-cations.Aserious problemconstrainingsome practicalexplorations of watermarking technologyis the insuf-ficient robustness of existing watermarking algorithmsagainst geometric distortionsuch as rotation,scaling,and translation(RST),etc[1].Designi…     

Timing and hamming weight attacks on minimal cost encryption scheme

The timing and Hamming weight attacks on the data encryption standard (DES) cryptosystem for minimal cost encryption scheme is presented in this article. In the attack, timing information on encryption processing is used to select and collect effective plaintexts for attack. Then the collected plaintexts are utilized to infer the expanded key differences of the secret key, from which most bits of the expanded secret key are recovered. The remaining bits of the expanded secret key are deduced by the correlations between Hamming weight values of the input of the S-boxes in the first-round. Finally, from the linear relation of the encryption time and the secret key's Hamming weight, the entire 56 bits of the secret key are thoroughly recovered. Using the attack, the minimal cost encryption scheme can be broken with 223 known plaintexts and about 221 calculations at a success rate a＞99%. The attack has lower computing complexity, and the method is more effective than other previous methods.     

网络安全中的DDos攻击的检测与防御研究 ——以用户访问权益为优先考虑的DDOS防御策略

现代社会,互联网成为了人民生活的基础设施,网络安全就显得尤为重要。DDOS攻击给网络服务的正常运行会带来不可估量的损失,而现有的DDOS攻击防御方法以保护服务器为初衷,使得过度保护而影响了用户使用权益。文章设计并提出在以用户访问权益为优先考虑的情况下,通过网络数据包捕获、分析与功能限制模组、验证码、黑名单四大模块实现,缓解DDos攻击对服务器造成的过大伤害并使服务器维持运行持续提高服务的方法,通过实验可以有效保障服务器运行的同时抵抗DDOS攻击带来的风险。     

以DDoS攻击为例的网络攻防平台构建和实现

通过对网络攻防模拟平台的研究,分析当前流行的一些攻击方式和手段及这些攻击方式的有效防御方式;并基于Linux的开发环境,以DDoS为例,进行了系统的研究。     

Adaptive Detection of SYN Flooding Attacks at Source-end Networks

An adaptive detection method is proposed to detect SYN flooding attacks at source-end networks. This method can adjust itself to the frequent changes of network conditions. Key features of its design include： （1） creating a detection statistic based on the protocol behavior of TCP SYN-SYN/ACK pairs; （2） forming on-line estimations of the statistical characters of the detection statistic; （3） adjusting its detection threshold according to the variations of network traffic and the latest detection result; （4） decreasing disturbance of random abnormalities in the normal network traffic by consecutive cumulation of threshold violations. Performance analysis and simulation results show the minimum attack traffic that can be detected is about 30% of the legitimate traffic, under the requirements that the probability of false alarms be less than 10^-6, the probability of a miss during an attack be less than 10^-2 and the detection delay be within 7 sampling periods.     

分布式DoS攻击检测系统的改进研究

为了对抗分布式DoS攻击,提出了一个改进的分布式DoS攻击检测系统:采用贝叶斯方法,根据第一次连接的状态,计算后验概率,据此对系统检测攻能进行改进;采用被动响应的方式,改进系统响应功能,对检测到的入侵行为,进行实时响应.仿真实验表明,该改进措施减少了误报率和漏报率,提高了系统的实时响应性.     

Copy-move forgery detection of duplicated objects using accurate PCET moments and morphological operators

This paper presents a new method for copy-move forgery detection of duplicated objects. A bounding rectangle is drawn around the detected object to form a sub-image. Morphological operator is used to remove the unnecessary small objects. Highly accurate polar complex exponential transform moments are used as features for the detected objects. Euclidian distance and correlation coefficient between the feature vectors are calculated and used for searching the similar objects. A set of 20 forged images with duplicated objects is carefully selected from previously published works. Additional 80 non-forged images are edited by the authors and forged by duplicating different kinds of objects. Numerical simulation is performed where the results show that the proposed method successfully detect different kinds of duplicated objects. The proposed method is much faster than the previously existing methods. Also, it exhibits high robustness to various attacks such as additive white Gaussian noise, JPEG compression, rotation, and scaling.     

A multilevel sampled‐data approach for resilient navigation and control of autonomous systems

Autonomous systems are rapidly becoming an integrated part of the modern life. Safe and secure navigation and control of these systems present significant challenges in the presence of uncertainties, physical failures, and cyber attacks. In this paper, we formulate a navigation and control problem for autonomous systems using a multilevel control structure, in which the high‐level reference commands are limited by a saturation function, whereas the low‐level controller tracks the reference by compensating for disturbances and uncertainties. For this purpose, we consider a class of nested, uncertain, multiple‐input–multiple‐output systems subject to reference command saturation, possibly with nonminimum phase zeros. A multirate output‐feedback adaptive controller is developed as the low‐level controller. The sampled‐data (SD) design of this controller facilitates the direct implementation on digital computers, where the input/output signals are available at discrete time instances with different sampling rates. In addition, stealthy zero‐dynamics attacks become detectable by considering a multirate SD formulation. Robust stability and performance of the overall closed‐loop system with command saturation and multirate adaptive control are analyzed. Simulation scenarios for navigation and control of a fixed‐wing drone under failures/attacks are provided to validate the theoretical findings.