DADS — Dynamic Analysis and Design System

Multi-body contact in non-linear dynamics of real mechanical systems

: A dynamic model of the Polaris Sportsman 500 All-Terrain Vehicle (ATV) was built using Dynamic Analysis and Design System (DADS) version 8.5. Aspects of the model included the front MacPherson struts and rear independent suspension. The model also allowed control over the path and speed of the vehicle using the DADS control elements. The modeling methods discussed here are general in nature and may be applied to other DADS vehicle models of similar systems. This report also provides a usefull reference source to those using this model.

BSS developed a new generation high power (~20kW) solar array to meet the customer demands. The high power solar array had the north and south solar wings of which designs were identical. Each side of the solar wing consists of three main conventional solar panels and the four-side panel swing-out new design. The fully deployed solar array surface area is 966 ft2. It was a quite challenging task to define the solar array's optimum design parameters and deployment scheme for such a huge solar array's successful deployment and on-orbit maneuvering. Hence, a deployable seven-flex-panel solar wing nonlinear math model and a fully deployed solar array/bus-payload math model were developed with the Dynamic Analysis and Design System (DADS) program codes utilizing the inherited and empirical data. Performing extensive parametric analyses with the math model, the optimum design parameters and the orbit maneuvering /deployment schemes were determined to meet all the design requirements, and for the successful solar wing deployment on-orbit.

In order to thwart dynamic analysis and bypass protection mechanisms, malware have been using several file formats and evasive techniques. While publicly available dynamic malware analysis systems are one of the main sources of information for researchers, security analysts and incident response professionals, they are unable to cope with all types of threats. Therefore, it is difficult to gather information from public systems about CPL, .NET/Mono, 64-bits, reboot-dependent, or malware targeting systems newer than Windows XP, which result in a lack of understanding about how current malware behave during infections on modern operating systems. In this paper, we discuss the challenges and issues faced during the development of this type of analysis system, mainly due to security features available in NT 6.x kernel versions of Windows OS. We also introduce a dynamic analysis system that addresses the aforementioned types of malware as well as present results obtained from their analyses.

Malware is one of the biggest security threats on the Internet today and deploying effective defensive solutions requires the rapid analysis of a continuously increasing number of malware samples. With the proliferation of metamorphic malware the analysis is further complicated as the efficacy of signature-based static analysis systems is greatly reduced. While dynamic malware analysis is an effective alternative, the approach faces significant challenges as the ever increasing number of samples requiring analysis places a burden on hardware resources. At the same time modern malware can both detect the monitoring environment and hide in unmonitored corners of the system.In this paper we present DRAKVUF, a novel dynamic malware analysis system designed to address these challenges by building on the latest hardware virtualization extensions and the Xen hypervisor. We present a technique for improving stealth by initiating the execution of malware samples without leaving any trace in the analysis machine. We also present novel techniques to eliminate blind-spots created by kernel-mode rootkits by extending the scope of monitoring to include kernel internal functions, and to monitor file-system accesses through the kernel's heap allocations. With extensive tests performed on recent malware samples we show that DRAKVUF achieves significant improvements in conserving hardware resources while providing a stealthy, in-depth view into the behavior of modern malware.

<div class="htmlview paragraph">In this paper two different tools have been applied to the problem of designing a small UAV. With these tools a parametric study of wing configuration and sizing was performed. The focus of this study was to optimize range and endurance of the UAV during a particular flight mission. The two numerical analysis tools applied to the UAV wing design were developed for widely different analysis problems. The first tool, the aircraft DATCOM was developed for the preliminary design analysis of manned aircraft and will be used to perform parametric modeling and geometry optimization. The Projectile Rocket Ordinance Design and Analysis System (PRODAS<sup>®</sup>) software was developed for ballistic projectiles and will be used for 6 DOF fixed plane trajectory simulation of the developed UAV concepts. While the scale of the UAV selected does not match well with the DATCOM software, the mission requirements and analysis format of the software is advantageous. Conversely, the scale of the problem matches the PRODAS software much better, while modeling a small UAV as a ballistic projectile holds limitations. To complete the parametric study it is helpful to validate the results of the two numerical analysis tools. The development and testing of a wind tunnel prototype can provide basic validation of the numerical analysis.</div>

This document presents the results of a computer-based dynamic performance assessment of a TATRA Truck with a swing arm suspension. A fully three dimensional TATRA model was created using a commercially available modeling and simulation methodology called Dynamic Analysis and Design Systems (DADS) (1). Limited validation was performed by comparing model predictions with video recordings of field tests (2). The model was considered accurate enough to predict various aspects of ride quality and stability performance, critical to the US Army mission needs. Performance evaluations were made by analyzing state variable time histories and high definition computer-generated animations recorded on video tape. One-to-one comparisons of the TATRA and a standard, solid-axle, heavy tactical vehicle (HTV) operating in various terrain and obstacle negotiation conditions were performed.

A flexible impact device based on dynamic forces which are applied to the ground in order to activate pressuremines was developed. The chain impact on the ground surface causes considerable force with a relatively low-weightdevice. This is a relatively simple machine, consisting of chains connected to a rotating drum. The basic model of thedrum and a single chain was developed using the DADS (Dynamic Analysis and Design System) program. In the model,the soil is described as a linear elastic material. The calculation of the impact forces or impulses caused by the chain-soilimpact is based on Hertz contact theory. The current model was developed for estimation of the ground-surface-levelimpact forces. A parametric study can be used to optimize the device design.

In order to design the perception system of the lower limb wearable rehabilitation robot, this study established the kinematics theoretical model of human lower limb and conducted the kinematics analysis of human body. By using the dynamic attitude analysis system, combined with the human body mark points, the position data of human body mark points in the process of standing up, sitting up, walking, stepping up, and squatting were collected. Combined with the movement mechanism of human lower limbs, the characteristics of human motion state transition are analyzed, and the perceptual algorithm for judging human motion intention is studied, so as to determine the wearer's current posture, standing intention while sitting, walking intention while standing, moving intention, and stopping intention during walking. The results show that the angle of the hip joint changes regularly between 0° and 37° and the angle of the knee joint changes regularly between 0° and 70°during the standing process, which is consistent with the angle change trajectory collected by the dynamic attitude analysis system. The angle trajectories of the hip and knee joints measured by the absolute angle sensor are the same as those obtained by the dynamic attitude analysis system. 1.5 rad and 0.3 rad were selected as reasonable and effective thresholds for determining sitting and standing states.

This study is intended to assist property-casualty insurers in modeling their dynamic financial analysis (DFA) system. Moreover, we address the important steps and considerations that go into a user-friendly adaptive decision support system with which the modeler is capable of easily refining the associated models of risk factors through a series of GUIs with as much work as possible left to the computer system.

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The paper presents the development of a measurement system for dynamic stability analysis. The system is composed of an actuation device, that is a robotic platform with four degrees of freedom, and two measurement systems: a force platform, to measure the position of the centre of pressure (COP), and a vision system, to measure the position of the centre of mass (COM). The purpose of the system is to provide means to identify whether a subject behaves like an inverted pendulum (as the literature predicts for static posturography), when a dynamic perturbation is applied. This can be achieved by generating a movement of the robotic platform and, simultaneously, by measuring COP and COM trajectories and verify their coherence with the inverse pendulum model.

In this paper we describe how the knowledge related to a specific domain and the available visual analysis tools can be used to create dynamic visual analysis systems for video surveillance.Firstly, the knowledge is described in terms of application domain (types of objects, events... that can appear in such domain) and system capabilities (algorithms, detection procedures...) by using an existing ontology.Secondly, the ontology is integrated into a framework to create the visual analysis systems for each domain by inspecting the relations between the entities defined in the domain and system knowledge.Additionally, when necessary, analysis tools could be added or removed on-line.Experiments/Application of the framework show that the proposed approach for creating dynamic visual analysis systems is suitable for analyzing different video surveillance domains without decreasing the overall performance in terms of computational time or detection accuracy.

Our emphasis in this book is on constant parameter linear time invariant dynamic systems. Laplace transform theory is most useful when applied to analysis of linear systems, and this transformation allows the analyst to reduce differential equation problems to algebraic problems. The theory discussed later will be utilized in both the dynamic system analysis and control system design portions of the text. It is demonstrated in this chapter that linear, time-invariant dynamic equations can be transformed into rational functions. Many important input (test) signals can be transformed in this way as well.

Problem. The article proposes a developed construction of a suspension – shock absorber, which made it possible to install a hydraulic hammer as a working equipment, simultaneously isolating it from vibrations.
 A mathematical model of the system was developed, the basis of which is a suspension – shock absorber for attaching a hydraulic hammer to an excavator, which includes modeling of its mechanical system. Goal. The goal is the development and research of a sub-axle - shock absorber for the attachment of hydraulic hammer equipment (hydraulic hammer) to an excavator. Methodology. The solution of the set problems involved the creation of a mathematical model of the vibration system and its implementation using the MathCAD application program. Originality. It is proposed to transform the differential equations of the mathematical model of the vibration system by the method of decreasing order and as a result obtain the displacements, velocities, and accelerations of individual elements and obtain the nature of the change in the disturbing force of the vibrating hammer. Using the MathCAD program, a study of the dynamics of the system, which includes a hydraulic ham a shock absorber and an excavator, was performed, as well as the frequencies of free oscillations of the system in question were determined. Practical value. The obtained results of scientific research on vibration protection of excavators, which are operated with attached shock devices (hydraulic hammers), with the use of the MathCAD mathematical program, can be successfully used in the development, as well as in the determination of dynamic loads of similar vibration protection systems used in industry.