Internet-based Composite Repair

There are two essential ingredients for collecting information from the Internet: 1) a World Wide Web (Web) browser, and 2) an Internet search engine. The two most widely used Web browsers are Microsoft's Internet Explorer and Netscape Communications Corporation's Navigator. There are, however, more than 120 browser software possibilities available. These browsers have been cataloged by Adrian Roselli and may be found at Evolt, a site that supports the exchange of Web design information. Web browsers are like brands of shoes; some fit better than others. By visiting Evolt, whose uniform resource locator (URL) is listed below, one might find a browser that works better. For example, some Internet users prefer Firefox (Figure 1) and Safari, because Web browsers have different efficiencies in displaying Internet information on different computer platforms. Figure 1 Search page from the Web browser known as Firefox. Image used with permission of Mozilla, parent of Firefox. For a free copy of Firefox, which operates on either Apple or IBM compatibles, visit http://www.mozilla.org. Evolt http://browsers.evolt.org/ As is the case with Web browsers, there are a number of Internet search engines. Each search engine has a variety of features that address different objectives for finding information from the Internet. The State University of New York at Albany has organized an excellent list of Internet search engines.

Composite materials are enjoying an increasing use in aircraft structures. As more fleets transition from metal to more composite aircraft, the practice of maintenance is also adjusting. Handling, inspection and repair of aircraft composites following non-visible or barely visible damage are among the areas of concern, due to associated cost and safety implications. A pilot study was performed to explore the level of awareness and understanding of aviation maintenance practitioners around these issues. In addition, this research project sought to identify factors related to the technical/engineering judgement capacity of the personnel working with composites and to gauge the need for specialised education and training. A questionnaire survey was administered to a group of 40 professionals working for an aircraft maintenance, repair and overhaul (MRO) organisation. Descriptive statistics in conjunction with analysis of variance (ANOVA) were used to analyse the results. The sources of impact and common areas affected on the aircraft have been identified, with situational awareness suggested as the most important mitigator against impact damage. Over 70% of the participants would refer to their engineering manager for instructions on how to handle composite damage. The need for higher standardisation for composites’ maintenance, repair and handling issues emerged as a common theme across different sections of the survey. Almost all respondents agree on the need for specialised knowledge and training for the handling, repair and inspection of composites.

I. Introduction Studies reveal that often group members collaborate when searching for information even if they were not explicitly asked to collaborate [1]. The activity that involves a group of people engaging in a common information seeking task is called Collaborative Information Seeking (CIS). Over the past few years, CIS research has focused on providing solutions and frameworks to support the process [2]. However, work in this field to date has always assumed that information seekers engaged in CIS activity are using the same access modality, the visual modality. The attention on this modality has failed to address the needs of users who employ different access modalities such as haptic and/or audio. Visual Impaired (VI) employees in a workplace may often have to collaborate with their sighted team members when searching the web. Given that the VI individual's search behaviour is challenged by poor web design and the shortcomings of current assistive technology [3][4]; collaboratively engaging in w...

Today, Web search is treated as a solitary experience. Web browsers and search engines are typically designed to support a single user, working alone. However, collaboration on information-seeking tasks is actually commonplace. Students work together to complete homework assignments, friends seek information about joint entertainment opportunities, family members jointly plan vacation travel, and colleagues jointly conduct research for their projects. As improved networking technologies and the rise of social media simplify the process of remote collaboration, and large, novel display form-factors simplify the process of co-located group work, researchers have begun to explore ways to facilitate collaboration on search tasks. This lecture investigates the who, what, where, when and why of collaborative search, and gives insight in how emerging solutions can address collaborators' needs. Table of Contents: Introduction / Who? / What? / Where? / When? / Why? / Conclusion: How?

Application of composite patches in repair of damaged/aged aircraft structures is one of the most popular repairing methods in aerospace engineering. Since running experiments are difficult, time consuming, expensive, and also require high level of expertise, simulation of the behavior of the patch and also the faulty components after repair can assist designers and engineers in optimization of their designs. In this article, full-scale simulation of a damaged panel that is experimentally repaired with a composite patch will be considered using ABAQUS, a commercial finite element code. The crack growth process is modeled with the extended finite element method and the cohesive zone model (CZM) is used to model the progressive damage in the adhesive of the composite patch repair. Also, sensitivity analysis is performed on the CZM parameters and it is shown that the three parameters i.e. the shear toughness, maximum first shear traction, and penalty parameter for the elastic stiffness are important in the simulation of adhesively bonded composite patch repairs. The calibrated cohesive properties are successfully used to predict the response of the composite patch to the strengthened in damaged structure with considering the linear and nonlinear stage of failure process. The simulation results obtained in different stages have been verified with the existing experimental results.

Analysis of the plastic zone under mixed mode fracture in bonded composite repair of aircraft structures

To support users obtain correct web information and make effective decision during web search, we propose two kinds of search systems. One is a system for helping users to judge the credibility of web search results and to search for credible web pages. This proposed system provides users with the following functions: (1) calculation and visualization of several scores of web search results on the major credibility aspects, (2) prediction of user's credibility judgment model, and (3) re-ranking of web search results based on user's predicted credibility model. The other proposed system suggests suspicious information, promoting more careful information seeking to users during web search and browsing. In this paper, we argue the strong and weak points of the two proposed systems towards credibility-oriented web search.

The SSL/TLS protocol is the de-facto standard for secure Internet communications, and supported by virtually all modern e-mail clients and Web browsers. With more and more PDAs and cell phones providing wireless e-mail and Web access, there is an increasing demand for establishing secure SSL/TLS connections on devices that are relatively constrained in terms of computational resources. In addition, the cryptographic primitives executed on the client side need to be protected against side-channel analysis since, for example, an attacker may be able to monitor electromagnetic emanations from a mobile device. Using an RSA-based cipher suite has the advantage that all modular exponentiations on the client side are carried out with public exponents, which is uncritical regarding performance and side-channel leakage. However, the current migration to AES-equivalent security levels makes a good case for using an Elliptic Curve Cryptography (ECC)-based cipher suite. We show in this paper that, for high security levels, ECC-based cipher suites outperform their RSA counterparts on the client side, even though they require the integration of diverse countermeasures against side-channel attacks. Furthermore, we propose a new countermeasure to protect the symmetric encryption of messages (i.e. “bulk data”) against Differential Power Analysis (DPA) attacks. This new countermeasure, which we call Inter-Block Shuffling (IBS), is based on an “interleaved” encryption of a number of data blocks using a non-feedback mode of operation (such as counter mode), and randomizes the order in which the individual rounds of the individual blocks are executed. Our experimental results indicate that IBS is a viable countermeasure as it provides good DPA-protection at the expense of a slight degradation in performance.

This paper presented a method to visualize Internet forums on the client side. Enhancement to web browsing was proposed to solve problems in information retrieval from forums. Specifically, visualization of structural information provided useful overviews for web browsing. A conceptual model described forums as three-dimensional spaces with information objects as points and web browsing as movements in the spaces. A series of diagrams were proposed to provide overviews for users’ web browsing movements. Implementation of the visualization system and examples of the diagrams were presented in the paper.KeywordsVisualizationInternet Forums

Fatigue problems become an important topic in the maintenance of aircraft structures. Efficient repair technique, called composite patch repair, was used to reinforce the damaged structures and extend the service life. In this paper, using empirical approach, the effect of composite patch repair on fatigue crack growth was investigated on 7050 aluminum alloy. In additional, loading parameters associated with patch repair (Graphite/Epoxy) was studied in order to show their influence on fatigue life and fatigue crack growth rate, namely stress ratio. Results provide an increasing in fatigue life and fatigue crack growth rate in increased stress ratio. A delayed in fatigue life and diminution of FCGRs is the results of composite patch repair. Effect of patch repair was shown highly at high stress intensity factor when maximum applied loading is kept constant.

This paper aims to analyze the multi-effects of the glass fiber reinforced polymer (GFRP) composite patch to repair the inclined cracked 2420-T3 aluminum plate. Three-dimensional finite element method (FEM) was used to study the effect of GFRP composite patch with different stacking composite laminate sequence, [0°]4, [90o]4, [45o]4, [0o/45o]2s and [0°/90°]4s on the crack driving force, J-integral, of inclined cracked 2420-T3 aluminum plate. Furthermore, the effects of patch geometry, number of layers, single or double side patch and crack incline angle are described. The present results show that the patch has a high effect in case of a crack in pure mode I. Furthermore, the effectiveness of the composite patch is increasing with the crack length increases. Moreover, the efficiency of the composite patch has a high effect by changing the fiber orientation, the number of layers, and the single or double side patch.

The use of composite materials is widely spread across the Aerospace sector. Scarf and step lap joints are amongst the most commonly used methods for flush joint repairs; they restore original stiffness and nearly original strength. Prior investigations conducted by the authors have shown that bonded and hybrid step lap joints have superior static strength capabilities than bolted joints. Hybrid step lap joints have shown the highest fatigue resistance than its bolted and bonded counterparts. This investigation aims at optimising the previous step lap joint design containing five steps with a 90 mm long overlap length in order to improve joint efficiency. Four new step lap joint configurations are considered based on a parametric study conducted using Abaqus; two of which contain seven steps and a 130 mm long overlap (bonded and hybrid) whilst the other two contain six steps and a 105 mm long overlap (bonded and hybrid) with a tapered outer step region. Experimental tests right through to numerical modelling using three-dimensional (3D) finite element (FE) models have been investigated. Adhesive non-linear material properties, fastener contacts and friction forces were all included in the 3D FE models. The Multicontinuum Theory (MCT) is used to simulate the progressive failure process and determine the stress states in the four configurations. Overall the FE models are able to accurately predict the bonded and hybrid joint strengths and highlights the importance of not only optimising the number of steps and their lengths but also the individual step heights. This is a parameter which has often been overlooked by fellow researchers. Experimental results showed that all four step lap joint configurations have significant improvement under static and fatigue load cases; the greatest improvement is seen in the two bonded step lap joint configurations. Overall the hybrid joint configuration consistently outperformed the bonded joint configurations. The presence of fasteners supress crack propagation, minimise peak peeling stresses at the ends of the overlap and increase the durability of the joint. This enables early crack detection which can assist composite joint repair certification.

Cryptography is one of the key elements in providing security for modern e‐commerce systems. It is well known that software‐based encryption has built‐in security weaknesses due to storing and managing digital certificates/keys in a high‐risk environment such as a local hard disk or software. This makes embedded hardware encryption a superior solution. However, most existing embedded hardware encryption modules need additional dedicated software in order to implement a secure e‐commerce application, which increases cost as well as adds complexity. In this paper, a new embedded hardware DSP (digital signal processor) encryption module, using the RSA (Rivest, Shamir, and Adleman) algorithm, is developed for secure e‐commerce transactions from the client side. The goal is to seamlessly integrate the embedded DSP hardware encryption module, which combines computational power and flexibility in programming, with a widely available web browser that provides the required e‐commerce functions. The integrated system can store and process security sensitive data inside the plug‐in hardware. The proposed scheme tries to maximize security strength while limiting overheads by utilizing a widely available web browser to perform e‐commerce functions such as product searching, etc. A fully functional web e‐commerce system has been developed as a proof of concept. Our major contribution is a design of a functional RSA plug‐in encryptor which can store and encrypt sensitive information originated from the e‐commerce process using standard web browsers. Implementation details addressing challenging issues such as big integer, large message, and communication components have been provided which have never been reported in the public literature. This can be very useful for real‐life industry security applications. Copyright © 2010 John Wiley & Sons, Ltd.

Modelica is primarily supported by simulation environments for the treatment of equation based models and model libraries. As of today Modelica is rarely used for the exchange of engineering data, visualization or interactive computing, even though the Modelica language offers a lot of interesting features for such applications. This paper investigates the potential of lightweight Modelica tools that run directly in scripting or web clients. Two Modelica parsers have been implemented in the popular client-side languages Python and JavaScript. The Modelica parser in Python is extended with a backend translating algorithmic Modelica definitions to Python. This gives access to existing Python packages from scripted Modelica. It also enables the interactive debugging of algorithmic Modelica code. The Modelica parser in JavaScript offers a generic backend interface. The paper demonstrates two applications. First a simple analysis tool for Modelica packages running from the command line is demonstrated. The true potential of JavaScript is the embedding of engineering data as Modelica code with HTML5 documents and their processing on the client side, e.g. in Web browsers. The paper shows a Modelica text editor and parameter GUI generator running in a web browser.

La búsqueda de información a través de la World Wide Web es una tarea común hoy en día. Sin embargo, es sobre todo una experiencia textual. Este trabajo propone e implementa un entorno 3D para la representación de los resultados de búsqueda Web en un entorno en tres dimensiones (3D) que es controlada por gestos y reconocimiento de voz. Con el fin de hacer eso, se requieren dos escenarios: una solución de servidor basado en Servicios Web XML que permite ser consumidos por los clientes que están buscando información en la Web; y una aplicación en cliente que permite ser ejecutado como una interfaz gráfica de usuario en el escritorio mediante el uso de comandos de voz y gestos. Esta última aplicación se encarga de modelar gráficamente el entorno 3D de acuerdo con los resultados de búsqueda Web. Un prototipo del sistema propuesto fue implementado, lo que representa un conjunto de resultados de búsqueda Web en un entorno 3D. El escenario 3D es manejada por gestos y comandos de voz; el entorno 3D se basa en la administración de algunas transformaciones 3D tales como la rotación y el escalado de las caras interiores de un toroide. Una evaluación del prototipo en contextos de búsqueda sugiere que hay un alto nivel de aceptación del usuario del modelo multimedia propuesto. Las personas que probaron el prototipo han dicho que tiene una interfaz gráfica de usuario intuitiva, y que tanto el habla como el reconocimiento de gestos han sido una alternativa altamente funcional para las tareas relacionadas con la búsqueda Web. Sin embargo, hay algunos aspectos a mejorar, sobre todo en el apoyo de reconocimiento de voz de diferentes acentos. En general, el prototipo multimedia cumplió con las expectativas de una muestra de los usuarios finales, lo que demuestra que este tipo de interfaces tienen un gran potencial.