Static liquefaction is a sudden decrease of soil shear strength due to the rapid development of pore pressures generated during the collapse of loose, saturated soil deposits. If this type of failure occurs in sloping soils, a flowslide can result. Viscous debris moving down a slope with high velocity could cover a vast area and cause significant loss of life and property. The primary objective of this study was to investigate the triggering factors of liquefaction in shallow slopes through the physical modeling technique of centrifuge testing. A flowslide simulator was developed to investigate the factors that lead to the liquefaction of soil slopes. This simulator was capable of replicating groundwater regimes and intense rainfalls with pore pressure transducers to monitor the pore pressure changes in the model slope and digital cameras to calculate the resultant slope deformation, velocity, and acceleration using the Particle Image Velocimetry method (PIV) of digital image correlation. In the course of this research, four centrifuge tests have been performed to evaluate the triggering mechanisms of fast landslides in shallow slopes. A seepage induced failure was simulated in the first test. The second and third tests were conducted applying different groundwater regimes in combination with intense rainfall to bring the slope to failure. The last test was a rainfall induced failure in the absence of a pre-existing groundwater table. The results from these experiments illustrate that the initial groundwater level has a considerable effect on the mobility of flowslides. / Thesis (Master, Civil Engineering) -- Queen's University, 2008-10-15 08:45:05.783

This dissertation examines the response of piezoelectric material strain to electron flux influence. A plate of PZT5h is prepared as the specimen. The positive electrode is removed, and the negative electrode is connected to a power amplifier. Sixteen strain gages are attached as the strain sensor. The specimen is placed in a vacuum chamber, then the positive side is illuminated by electron beam. The characteristic of the static strain response is predicted by deriving the equation strain/deflection of the plate. Two methods are used, the Electro-Mechanical Equations and numerical analysis using Finite Element Method. The settings of the electron gun system (energy and emission current), along with the electric potential of the negative electrode (back-pressure), are varied to examine piezoelectric material responses under various conditions. Several material characteristics are examined: current flow to and from the material, time response of material strain, charge and strain distribution, and blooming. Results from these experiments suggest several conditions control the strain development in piezoelectric material. The current flow and strain on the material is stable if the backpressure voltage is positive. As a comparison, the current flow is small and the strain drifts down if the backpressure voltage is significantly negative. The material needs only 1 second to follow a positive step in backpressure voltage, but needs almost 1 minute to respond to a negative step backpressure change. This phenomenon is a result of secondary electron emission change and the energy transfer from the primary electrons to the local electrons on the material. The time needed to achieve steady state condition is also a dependent of emission current. After a period of time the primary electron incidence induces strain throughout the 7.5-cm-by-5-cm plate despite the fact that the beam diameter is only 1 cm2. One possibility is blooming due to electron movement under intense electric fields in the dielectric material.

Piles are engineering structures which are subjected to axial and lateral loading. In this dissertation, pile load tests were performed on a full-scale fabricated pile to understand lateral pile responses under static and cyclic loading. The experiments were performed on a fabricated test pile at the Geo-Engineering Laboratory at Queen's University. Dry loose Olimag Synthetic Olivine sand was used as the test soil. Instrumentation including axial strain gauges, null sensors (earth pressure sensors) and string potentiometers were used to monitor pile responses throughout the tests. What differentiates the current study from previous investigations is direct measurements of lateral earth pressure on a test pile using those null sensors with conventional measurements of curvature and deformation. The null sensors of Talesnick (2005) have ‘infinite stiffness’ and calibration that is almost independent of the soil type, soil condition and stress history, qualities that make the sensor superior to other commercially available sensors. The initial pile response under static loading was examined. Previous laterally loaded pile test programs have utilized curvature measurements to infer moments, and differentiation of moments to determine lateral forces. Comparisons with the directly measured pressures confirmed the effectiveness of differentiated moments. To understand offshore structures, the behaviour of a pile subjected to cyclic loading is examined and explained by elastic soil response at low load levels and the progressive development of inelastic response at higher load levels. In addition, the loading condition (i.e. two-way versus one-way loading) was found to have a substantial effect on pile responses. The pressure distributions for two-way cyclic loading suggest that the lateral pressure is proportional to displacement with peak pressures near the ground surface during elastic responses. The peak lateral pressures move deeper towards the point of rotation with increasing cyclic loads to generate inelastic responses. However, the lateral pressure response is consistently inelastic for one-way loading. / Thesis (Master, Civil Engineering) -- Queen's University, 2014-05-02 20:29:56.489

Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 50-51)

The continued increasing use of microprocessors in embedded systems has caused a proliferation of embedded software in small devices. In practice, many of these devices are difficult to update to fix security flaws and software errors. This brings an emphasis on ensuring the secure and reliable software prior to the release of the device to ensure the optimal user experience. With the growing need to enable test and diagnostic capabilities into embedded devices the use of the JTAG interface has grown. While the intentions of the interface was originally to give the ability to shift in data into and out of chip’s scan chains for test, the generic framework has allowed for its features to expand. For embedded microprocessor’s the interface allows for halting execution, insertion of instructions, reprogramming the software, and reading from memory. While it creates a powerful debugging system, it also allows unlimited access to a malicious users. In turn such a user has the ability to either copy the intellectual property on the device, disable digital rights management routines, or alter the devices behavior. A novel method to secure JTAG access through the use of a multi-tiered permission system is presented in this paper. The use of static code analysis can be used to verify the functionality of embedded software code. Ideally, a software code should be tested in a way that guarantees correct behavior across all possible execution paths. While in practices this is typically infeasible due to the innumerable number of paths in the system, the use of automated test systems can help maximize the amount of code covered. In addition, such methods can also identify non-executable software statements that can be an indication of software issues, or sections of software that should not be targeted for testing. New static code analysis methods are presented in this dissertation. One technique uses supersets of software solution spaces to correctly identify unreachable software code in complex systems. Another presented technique automatically generates a set of test vectors to quickly maximize the number of code blocks executed by the set of test vectors. It is shown that such a method can be significantly faster than traditional methods.

Static balance is the reduction or elimination of the actuating effort in quasi-static motion of a mechanical system by adding non-dissipative force interactions to the system. In recent years, there is increasing recognition that static balancing of elastic forces in compliant mechanisms leads to increased efficiency as well as good force feedback characteristics. The development of insightful and pragmatic design methods for statically balanced compliant mechanisms is the motivation for this work. In our approach, we focus on a class of compliant mechanisms that can be approximated as spring-loaded rigid-link mechanisms. Instead of developing static balancing techniques directly for the compliant mechanisms, we seek analytical balancing techniques for the simplified spring–loaded rigid–link approximations. Towards that, we first provide new static balancing techniques for a spring-loaded four-bar linkage. We also find relations between static balancing parameters of the cognates of a four-bar linkage. Later, we develop a new perfect static balancing method for a general n-degree-of-freedom revolute and spherical jointed rigid-body linkages. This general method distinguishes itself from the known techniques in the following respects: 1 It adds only springs and not any auxiliary bodies. 2 It is applicable to linkage shaving any number of links connected in any manner. 3 It is applicable to both constant(i.e., gravity type) and linear spring loads. 4 It works both in planar and spatial cases. This analytical method is applied on the approximated compliant mechanisms as well. Expectedly, the compliant mechanisms would only be approximately balanced. We study the effectiveness of this approximate balance through simulations and a prototype. The analytical static balancing technique for rigid-body linkages and the study of its application to approximated compliant mechanisms are among the main contributions of this thesis.

The PHP is a very popular language which is used to write a server side part of web applications. The language is very simple to use and there are lots of small or more complex pages across the internet. But the great widespread of the PHP attracts the people which want to harm and compromise security of the web applications. The weverca analyzer is the first tool which is able to perform complex security analysis of a full page written in the modern version of the PHP and give information about possible security risks in the application. But the performance of Weverca is limited by its time and memory complexity caused by inefficient inner representation of a PHP memory state. The goal of this thesis is to find and solve main problems of the original memory representation. The output of this thesis is an implementation of the new memory representation which minimizes the complexity of the original solution. Powered by TCPDF (www.tcpdf.org)

Detecting bugs plays a significant role in software development. Bugs may lead to unexpected behaviors. An attacker can gain control over a system by exploiting its bugs. Usually, an attack can be triggered by user's input. Unchecked user input can cause serious problems in a program. In order to prevent this situation, user's input must be checked carefully before it can be used. To provide the information of where user's input can affect a program, the taint dataflow analysis is being considered. In this thesis, we introduce a concurrent solution to perform static taint dataflow analysis. The goal is to find the statements of the program dependent on user input and inform the developers to validate those. We provides a method for the static concurrent taint dataflow analysis based on sequential static taint dataflow analysis. Static dataflow analysis is time consuming. This research addresses the challenge of efficiently analyzing the dataflow. Our experimental shows that our concurrent taint dataflow analysis improves the speed of analyzing complex programs.

This research program investigates the performance of a steel truss bridge when subjected to both localized web damage and a subsequent post-tensioned strengthening approach. The investigation utilizes a combined approach involving an experimental scale model bridge and a numerical computer model generated using the commercial finite element software RISA 3-D. The numerical model is validated using test data and further extended to parametric studies in order to investigate the theoretical load rating, strain energy, load redistribution, mode shapes and frequency of the bridge for control, damaged and strengthened states. The presence and severity of damage are found to significantly influence the global safety and reliability of the bridge. Also, higher order modes are more susceptible to changes in shape and frequency in the presence of damage. A recovery of truss deflection and a reduction of member forces are achieved by the proposed strengthening method.

This study investigated the relationship between balance on a moving base and balance on a stationary base. The hypothesis chosen for this investigation was that the correlation between the two types of balance would be zero.