Abstract This study is a master thesis in mechanical engineering at Karlstad’s University that treats operation disturbances that occur during the use of a vehicle integrated air-defense system called Robot-system 70 New Generation (RBS 70 NG) in cooperation with SAAB Dynamics AB. RBS 70 NG is a man-portable air-defense system (MANPADS) which is designed for anti-aircraft warfare and can be used in all climate zones.  The system usually operates on a hard surface such as gravel or hard soil, but for this project the aim is to integrate the system to operate on a vehicle platform. There are two disturbing factors that could affect the system during operation; the first is that the system is displaced due to the external forces that act on the system during use. The second disturbance specification is that the natural frequency of the entire system should be within a range of 3.5-6 Hz for vehicles installed RBS 70 NG [1]. The system is studied by using a simple mathematical model and by the use of computer aided software programs including CATIA V5 R22 and ANSYS R18.1. The modified design of the complete system showed that by adding four external legs to the platform, a natural frequency in-between the given interval is reached. A Transient Response Analysis was done to analyze the MANPADS ground version in order to make have some sort of a reference when studying the vehicle version of the RBS 70 NG and to make both system as similar as possible. The displacement of the system sight was similar for both versions of the system, when operating on the ground and on a vehicle. / Sammanfattning Den här studien är ett examensarbete inom maskinteknik på Karlstads Universitet, som behandlar driftstörningar för ett fordon integrerat ”Robotsystem 70 New Generation” i samarbete med SAAB Dynamics AB. Robotsystem 70 (RBS 70 NG) är ett luftvärnsrobotsystem som tillverkas i Sverige av SAAB Dynamics AB. Systemet används vanligtvis på hårda underlag som till exempel mark och grus, men i den här rapporten studeras integrationen av systemet på ett fordons plattform. Två störningsspecifikationer uppkommer vid användning av RBS 70 NG som tas hänsyn till, den första är att systemets förskjutning som exciteras via de krafter som uppkommer vid utskjutning inte stör systemet under drift. Den andra störningsspecifikationen är att den naturliga frekvensen för hela systemet bör ligga på ett intervall mellan 3,5–6 Hz för fordon installerat RBS 70 NG [1]. Analyserna har gjorts dels genom en förenklad teoretisk modell av systemet och genom användning av datorbaserade program såsom CATIA V5 R22 och ANSYS R18.1. Konstruktions ändringar på plattformen gjordes för att uppnå den minimala gränsen på egenfrekvensen på ca 3,5 Hz. Montering av fyra externa stödben på plattformen gav godkända värden på egenfrekvensen. En så kallad ”Transient Response Analysis” utfördes med hjälp av ANSYS R18.1 som visade att systemet utan konstruktions ändringar förskjuts med mindre än det minimala tillåtna värdet som tidigare beskrivet och att de pålagda krafterna inte var tillräckligt stora för att störa systemets drift.

Understanding the communications between programs can help software security engineers understand the behaviour of a system and detect vulnerabilities in a system. Assembly-level execution traces are used for this purpose for two reasons: 1) lack of source code of the running programs, and 2) assembly-level execution traces provide the most accurate run-time behaviour information. In this thesis, I present a communication analysis approach using such execution traces. I first model the message based communication in the context of trace analysis. Then I develop a method and the necessary algorithms to identify communications from a dual trace which consist of two assembly level execution traces. A prototype is developed for communication analysis. Finally, I conducted two experiments for communication analysis of interacting programs. These two experiments show the usefulness of the designed communication analysis approach, the developed algorithms and the implemented prototype. / Graduate / 2019-05-11

With a market share of 84.82% in 2016 Android is the most influential mobile oper-ating system on the world. In March 2017 users could find about 2.8 million ap-plications in the official Playstore while the number applications from other sourcesis unknown]. Since mobile devices are a fundamental source for news, enter-tainment, social activities and more they are also used for mobile banking, healthtracking and other data sensitive tasks. Besides static analysis the approach of dy-namically analyzing applications is necessary to ensure integrity and security. In theinternet a plethora of dynamic analysis methods for Android can be found. Problem-atic for a software security tester is to keep an overview over the quickly changinglandscape of these approaches. In this thesis work relevant dynamic analysis methodswere grouped and evaluated on different criterion. Furthermore an implementationfor the logging file related system calls with LD_PRELOAD was implemented andinvestigated how API calls can be mapped and the data visualized.

Columns are critical elements of any structure and their failure can lead to the catastrophic consequences of progressive failure. In structural design, procedures to design structures to resist conventional loads are well established. But design for accidental loading conditions is increasingly requested by clients and occupants in modern engineering designs. Among many accidental causes that induce column failure, impact (e.g. vehicular impact, ship impact, crane impact, impact by flying debris after an explosion) has rarely been considered in the modern engineering designs of civil engineering structures such as buildings and bridges. Therefore, most of the design requirements for structural members under vehicle impact as suggested by the current standards and codes such as Eurocode 1 are based on simple equations or procedures that make gross assumptions and they may be highly inaccurate. This research aims to develop more accurate methods of assessing steel column behaviour under vehicle impact.The first main objective of this study is to numerically simulate the dynamic impact response of axially loaded steel columns under vehicle impact, including the prediction of failure modes, using the finite element method. To achieve this goal, a numerical model has been proposed and validated to simulate the behaviour and failure modes of axially loaded steel columns under rigid body impact using the commercial finite element code ABAQUS/Explicit. Afterwards, an extensive parametric study was conducted to provide a comprehensive database of results covering different impact masses, impact velocities and impact locations in addition to different column boundary conditions, axial load ratios and section sizes. The parametric study results show that global buckling is the predominant failure mode of axially unrestrained compressed steel columns under transverse impact. The parametric study results have also revealed that column failure was mainly dependent on the value of the kinetic energy of impact. The parametric study has also shown that strain rate has a minor effect on the behaviour and failure of steel columns under low to medium velocity impact. The parametric study results have been used to develop an understanding of the detailed behaviour of steel columns under transverse impact in order to inform the assumptions of the proposed analytical method.To account for the effect of vehicle impact on the behaviour of steel columns, a simplified numerical vehicle model was developed and validated in this study using a spring mass system. In this spring mass system, the spring represents the stiffness characteristics of the vehicle. The vehicle stiffness characteristics can be assumed to be bilinear, with the first part representing the vehicle deformation behaviour up to the engine box and the second part representing the stiffness of the engine box, which is almost rigid. The second main objective of this research is to develop a simplified analytical approach that can be used to predict the critical velocity of impact on steel columns. The proposed method utilizes the energy balance principle with a quasi-static approximation of the steel column response and assumes global plastic buckling as the main failure mode of the impacted column. The validation results show very good agreement between the analytical method results and the ABAQUS simulation results with the analytical results tending to be on the safe side. A detailed assessment of the design requirements suggested by Eurocode 1, regarding the design of steel columns to resist vehicle impact, has shown that the equivalent static design force approach can be used in the design of moderately sized columns that are typically used in low multi-storey buildings (less than 10 storeys). For bigger columns, it is unsafe to use the Eurocode 1 equivalent static forces. It is acceptable to use a dynamic impulse in a dynamic analysis to represent the dynamic action of vehicle impact on columns, but it is important that both the column and vehicle stiffness values should be included when calculating the equivalent impulse force – time relationship. It is also necessary to consider the two stage behaviour of the impacting vehicle, before and after the column is in contact with the vehicle engine. A method has been developed to implement these changes.

<div>Execution comparison techniques compare multiple executions from the same program or highly similar programs to identify state differences including control flow differences and variable value differences. Execution comparison has been used to debug sequential, concurrent, and regression failures, by reasoning about the causality between execution differences and input differences, thread scheduling differences, and syntactic differences among program versions, respectively. However, execution comparison techniques have several limitations. First, executions may have benign differences, which are not related to the behavior differences that the user can observe. Second, huge storage spaces are required to record two independent executions. Third, the techniques can only compare executions from the same or similar programs.</div><div><br></div><div>In this dissertation, we present an execution comparison technique that (1) removes benign differences, (2) requires less space, and (3) can compare two different programs implementing similar algorithms. Also, we present that the execution comparison technique can be used in identifying and extracting a functional component out of a binary. First, we present a dual execution engine that executes multiple executions at the same time and only introduces the desired differences. Also, the engine compares the executions on-the-fly and stores the differences only. Second, we present a technique to compare two programs written by two different programmers. Especially we will show that this technique can compare the buggy program from a student and the correct from the instructor and can reason about the errors.</div><div><br></div>

<p> A general formulation of the analysis of plane coupled shear walls is presented. The "continuous method" of analysis of coupled shear walls is reformulated in terms of deflection variables. The assumption that midpoints of the connecting beams are points of contraflexure is relaxed so that the resulting theory is applicable to the general case where the lateral loading on the piers can be arbitrarily distributed. The governing equation of the structural system under static loading with the appropriate boundary conditions are given. The effect of asymmetry of the structure is discussed. As an application of the derived theory, the problem of shear walls subjected to differential foundation settlement and rotation is studied. Solutions to deflections and internal stresses, under such conditions, are given. Evaluation of the internal stresses was performed on a practical shear wall structure and the results analysed. Through the use of deflection variables, the formulation is extended into the regime of dynamics. The governing equation of motion with appropriate boundary conditions are given. The free vibration of coupled shear walls is studied and design curves for the fundamental natural frequency are presented. The use of substitutive symmetric systems and its effects on the fundamental frequency of asymmetric systems are examined. Theoretical natural frequencies were verified by dynamic testing on two models to show that the proposed theory is sufficiently accurate to provide information for dynamic analysis in seismic design. / Thesis / Master of Engineering (ME)

<p> An oblique four bar structural model with fixed member ends, being the most general building for space frames, is analysed under free and steady-state vibrations, using discrete mass method. </p> <p> Experimental techniques for measurement of free and steadystate vibrations are described. </p> <p> Experimental results have been compared against analytical ones. </p> / Thesis / Master of Engineering (MEngr)

No description available.

This thesis investigates the torsional performance of steel structures with and without rigid diaphragm constraints through numerical simulations and evaluates the appropriateness of relevant design provisions in current seismic design codes. In the first part of the work, six theme structures with different (1) in-plane stiffness of diaphragm, and (2) horizontal configurations of vertical braced frames were designed and their performance evaluated through both nonlinear static and dynamic analyses. Comparisons of the analytical results between the structures with and without rigid diaphragm constraints indicate that the in-plane rigidity of the diaphragms affects the efficiency of in-plane force transfer mechanisms, resulting in different global ductility and strength demands. Rigid diaphragm structures exhibit higher global strengths as well as higher torsional rotation capacity because of the infinite in-plane stiffness of the diaphragm. Semi-rigid diaphragm structures have higher ductility demands due to the finite in-plane diaphragm stiffness. The inclusion of bi-axial forces in the analyses reduces the structural strength and increases the ductility demands on the peripheral frames. The axial forces in the collectors and chords that make up the diaphragm depend on (1) the sequence of brace buckling and (2) vertical configuration of the braced frames. The results show higher axial forces in collectors in the roof diaphragms, and higher chord axial forces in the third floor diaphragms. The shear connections in the beams that make up both the collectors and chords are susceptible to failure due to the significant increment of axial forces in those members. The conventional beam analogy used in design can severely underestimate the axial forces in chords and collectors when the structures step into the inelastic stage. / Ph. D.

There has always been a challenge for designing structures against extreme dynamic loads. Blast loading falls under these loads category and blast resistant design has been gaining more interest during the past decade. Among different types of structures, Reinforced Concrete (RC) structures are usually recommended to be used for blast resistant design. However, the nonlinearities associated with these structures make their accurate analysis complicated. Therefore, simplified techniques have been introduced for nonlinear dynamic analysis of these structures. This study focuses on developing simplified computational strategies for the dynamic analysis of blast loaded RC elements including beams, panels/slabs and columns. For RC beams, the basis for commonly used Single-Degree-of-Freedom (SDOF) models has been outlined. A Multi-Degrees-of-Freedom (MDOF) model which takes into account the concrete nonlinear properties has been developed and the effect of varying the number of degrees-of-freedom (DOF) on response has been studied. Results showed that increasing the number of DOF affects the pressure-impulse (P-I) diagrams, especially in the impulsive regime, as the extent of damage increased. In addition, the model was compared with the experimental data and showed good agreement. For RC panels, a SDOF technique, based on the US Army Technical Manual TMS-1300 instructions, was constructed and results were compared with the ones obtained from explicit Finite Element (FE) analysis. Compared to the FE results, SDOF model yielded conservative predictions for deflection but it usually underestimated the dynamic reactions. A modification for reaction calculation was proposed which resulted in significantly better prediction of the reaction for the impulsive range of loading. Finally, considering the important role of columns in providing the overall stability of the structure, a MDOF model was developed for RC columns and the load carrying capacity of the columns was investigated for different levels of axial load, strain rate and damage. Increasing the strain rate enhanced the column's cross section properties whereas increasing the levels of axial load reduced the cross section curvature and the column deflection capacities. Results also showed that good detailing at the supports can significantly improve the load carrying capacity of RC columns. / Thesis / Master of Applied Science (MASc)