A general closed-form analytical solution is derived for the lapping tracks with its kinematics for the concentric V-groove lapping system. The lapping tracks on the ball surface for the three contact points are fixed circles, and their lengths of the lapping tracks are linearly proportional to , , and , respectively. In practice, if the orientation is randomized as the ball enters the lap again, then the distribution of the lapping tracks are dense after many cycles, and the larger the lapping length in each cycle, the smaller is the number of cycles required achieving the maximum lapped area ratio. In the geometry design of ball lapping, the V-groove half-angle should be larger than 45¢X, but to prevent the splash of abrasives, it should be less than 75¢X. Since the spin angular speed with its angle continuously varies with time for the eccentric lapping system, lapping tracks are not fixed circles. In practice, the lapped areas are complementary at the contact points of A and B. The total lapped area ratio is higher than 87% for a slip ratio less than 0.5. Hence, it is possible to lap all the surface of a ball by changing the slip ratio during the lapping process. Moreover, the larger the V-groove half-angle, the less is the eccentricity to achieve the optimum lapped area ratio. In order to understand the ball motion and ball lapping mechanism in the magnetic fluid lapping system, the forces and moments equilibrium equations are derived and numerical methods are analyzed. As the balls traveling in a train are assumed to be the same size, only one ball is considered in the dynamic analysis. Results show that as the ball separates from the shaft and the float, the spin angle increases quickly and approaches to 90¢X. Hence, the ball changes its attitude and thereby generates a new lapping tracks on the ball surface. Consequently, after repeating many cycles, lapping tracks would be scoping out more space and this is one of the spherical surface generation mechanisms. Surface waviness of ball causes a variation in the lapping load. When , it is possible to cause the ball separated from float and the lapping load is zero during the separation period. No matter how the ball separates from float, the spin angle always varies in a small range. Hence, only a very small region can be grounded due to the effect of the surface waviness. Therefore, it is not the main lapping mechanism of the spherical surface generation. In fact, during the lapping process, many balls with different diameters are lapped. To understand the ball¡¦s lapping mechanism of the spherical surface generation, it is necessary to consider a batch of balls. For a batch of balls with different diameters, the applied load on each should be different from each other. Generally, the larger the diameter of a ball, the larger is the friction force between the ball and shaft and the ball circulation speed. Therefore, it is possible to cause the collision between the larger and the smaller balls. To understand the interaction between balls traveling in a train, the dynamic analysis of multiple balls is developed. As the ball interacts with each other, it is possible to change the spin angle, and thereby to achieve the larger variation range of the lapping tracks. During the lapping process of a batch of balls, it is also possible to cause the separation between the shaft and the ball, and it causes the ball to change its attitude and to achieve more uniform lapping tracks.

The aim of this study is to perform the dynamic force analysis of a 3-degrees-of-freedom excavator during digging the soil and to simulate the motion on computer screen. Standard load calculations are done statically, therefore the effects of forces changing with time on the system cannot be observed. The dynamic analysis method used in the thesis is Recursive Newton &ndash / Euler Method and the numerical analysis method for simulation is 4th Order Runge &ndash / Kutta Method. After this study, the effects of sudden velocity changes / i.e, accelerational movements on construction machines, positions of bodies and dynamic forces on joints will be appointed and it will be possible to plan and control the motion.

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Sequence diagrams are a popular way to visualize dynamic software execution traces. However, they tend to be extremely large, causing significant scalability problems. Not only is it difficult from a technical perspective to build interactive sequence diagram tools that are able to display large traces, it is also difficult for people to understand them. While cognitive support theory exists to help cope with the later problem, no work to date has described how to implement the cognitive support theory in sequence diagram tools. In this thesis, we tackle both the technical and cognitive support problems. First, we use previous research about cognitive support feature requirements to design and engineer an interactive, widget-based sequence diagram visualization. After implementing the visualization, we use benchmarks to test its scalability and ensure that it is efficient enough to be used in realistic applications. Then, we present two novel approaches for reducing the cognitive overhead required to understand large sequence diagrams. The first approach is to compact sequence diagrams using loops found in source code. We present an algorithm that is able to compact diagrams by up to 80%. The second approach is called the trace-focused user interface which uses software reconnaissance to create a degree-of-interest model to help users focus on particular software features and navigate to portions of the sequence diagram that are related to those features. We present a small user study that indicates the viability of the trace-focused user interface. Finally, we present the results of a small survey that indicates that users of the software find the loop compaction and the trace-focused user interface both useful. / Graduate

Software reconnaissance is a very useful technique for locating features in software systems that are unfamiliar to a developer. The technique was, however, limited by the need to execute multiple test cases and record the components used in each one. Tools that recorded the execution traces of a program made it more practical to use the software reconnaissance technique. Diver was developed as an execution trace visualization tool using sequence diagrams to display the dynamic behaviour of a program. The addition of software reconnaissance to Diver and its trace-focused user interface feature improved the filtering of the Eclipse environment based on the contents of execution traces and led to a very powerful program comprehension tool. Myers' work on Diver was grounded in cognitive support theory research into how to build tools. He conducted a user study to validate the work done on Diver, but the study's findings were limited due to a number of issues. In this thesis, we expand on the study run by Myers, improve on its design, and investigate if software reconnaissance improves Diver's effectiveness and efficiency for program comprehension tasks. We also analyze the influence of software reconnaissance on the interactions of Diver's users, which allows us to identify successful usage patterns for completing program comprehension and feature location tasks. We research the connection between cognitive support theory and the design of Diver and use the study to attempt to validate the cognitive support offered by Diver. Finally, we present the results of a survey of the study participants to determine the usefulness, ease of use, and ease of learning of the tool. / Graduate / 0984

The aim of this study is to perform the dynamic force analysis of a 3-degrees-of-freedom excavator during digging the soil and to simulate the motion on computer screen. Standard load calculations are done statically, therefore the effects of forces changing with time on the system cannot be observed. The dynamic analysis method used in the thesis is Recursive Newton &ndash / Euler Method and the numerical analysis method for simulation is 4th Order Runge &ndash / Kutta Method. After this study, the effects of sudden velocity changes / i.e, accelerational movements on construction machines, positions of bodies and dynamic forces on joints will be appointed and it will be possible to plan and control the motion.

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.