scholarly journals Modeling and performance evaluation of a robotic treatment couch for tumor tracking

2016 ◽  
Vol 61 (5) ◽  
Author(s):  
Alexander Jöhl ◽  
Stephanie Lang ◽  
Stefanie Ehrbar ◽  
Matthias Guckenberger ◽  
Stephan Klöck ◽  
...  
Keyword(s):  
Vertical Motion ◽  
Longitudinal Direction ◽  
Lateral Motion ◽  
Tumor Motion ◽  
Unknown Parameters ◽  
One Dimensional ◽  
Tumor Tracking ◽  
Chirp Signals ◽  
And Performance ◽  
Lateral Axis

AbstractTumor motion during radiation therapy increases the irradiation of healthy tissue. However, this problem may be mitigated by moving the patient via the treatment couch such that the tumor motion relative to the beam is minimized. The treatment couch poses limitations to the potential mitigation, thus the performance of the Protura (CIVCO) treatment couch was characterized and numerically modeled. The unknown parameters were identified using chirp signals and verified with one-dimensional tumor tracking. The Protura tracked chirp signals well up to 0.2 Hz in both longitudinal and vertical directions. If only the vertical or only the longitudinal direction was tracked, the Protura tracked well up to 0.3 Hz. However, there was unintentional yet substantial lateral motion in the former case. And during vertical motion, the extension caused rotation of the Protura around the lateral axis. The numerical model matched the Protura up to 0.3 Hz. Even though the Protura was designed for static positioning, it was able to reduce the tumor motion by 69% (median). The correlation coefficient between the tumor motion reductions of the Protura and the model was 0.99. Therefore, the model allows tumor-tracking results of the Protura to be predicted.

Techniques for Determining the Parameters of a Two-Dimensional Tire Model for the Study of Ride Comfort

1997 ◽  
Vol 25 (3) ◽  
pp. 187-213 ◽  
Author(s):  
F. Mancosu ◽  
G. Matrascia ◽  
F. Cheli
Keyword(s):  
Physical Properties ◽  
Ride Comfort ◽  
Dynamic Test ◽  
Longitudinal Direction ◽  
Tire Model ◽  
Rigid Ring ◽  
Ring Model ◽  
Mass Moment ◽  
A New Technique ◽  
And Performance

Abstract A rigid ring model of the tire for the study of in-plane dynamics and a new technique for determining the parameters of the model are presented in this paper. This model can be used for studying the comfort of vehicles, problems of driving, and braking problems in the longitudinal direction. Comparison with finite element models shows that the rigid ring model of the tire is capable of describing the in-plane eigenmode shapes in the frequency range of 0–130 Hz. The well-known “brush model,” integrated into the tire model, is introduced to take into account the slide phenomena in the contact patch. The parameters of the model can be correlated with the physical properties of the tire so that designers can take advantage of such a correlation in the development of new tires in terms of time, cost, and performance. The technique used to determine the parameters of the model for some automobile tires include the direct measurements of some physical properties (mass, moment of inertia, stiffness) and a method of identification applied on the results from a dynamic test. The model is able to predict experimental data in terms of natural frequencies and relative dampings. Results from the application of this technique on two tires are reported.

Design, static analysis and development of a new three-legged shake table

2021 ◽  
pp. 095440622110184
Author(s):  
Ganesh Mangavu ◽  
Anjan Kumar Dash
Keyword(s):  
Vertical Motion ◽  
Torsional Stiffness ◽  
Shake Table ◽  
Lateral Motion ◽  
Sinusoidal Motion ◽  
Gravity Load ◽  
Simulation Results ◽  
Electromechanical Actuation ◽  
Translational Stiffness ◽  
Earthquake Data

In this paper, an alternative design is proposed based on a family of three-legged manipulators. Such manipulators have two actuators (one vertical and one horizontal) in each leg, unlike the standard UP̅S Stewart platform, which has one actuator in each leg. The arrangement of the two actuators is such a way that, to have vertical motion of the shake table only the Vertical Motion Actuators (VMA) are actuated and for longitudinal or lateral motion, the Horizontal Motion Actuators (HMA) alone are moved. Due to its inherent features such as simplified kinematics, control and distributed loading, a study is carried out to determine the performance of such three-legged manipulators as a shake table. Sinusoidal motion and white noise motions are given to the actuators and shown that the VMA forces have linear relationship with the platform forces. The translational stiffness and the torsional stiffness are studied separately for the manipulators. In the dynamic analysis, it is highlighted that the gravity load of the legs is borne by the Vertical actuators, irrespective of the motion being spatial or planar. Hence, this topology provides scope for lighter electromechanical actuation. The performance analysis of the 3 legged configuration is accomplished using simulation results, in comparison to a 7-UP̅S configuration of shake table. A prototype of the shake table is fabricated and tested with earthquake data of El Centro.

scholarly journals Different Reasons for Different Responses: A Review of Incumbents’ Adaptation in Carbon-Intensive Industries

2020 ◽  
pp. 108602661989399 ◽  
Author(s):  
Franziska Sump ◽  
Sangyoon Yi
Keyword(s):  
Carbon Emissions ◽  
Organizational Adaptation ◽  
Three Dimensions ◽  
External Shocks ◽  
Review Of The Literature ◽  
Organizational Responses ◽  
Environmental Pressure ◽  
One Dimensional ◽  
And Performance ◽  
Performance Heterogeneity

Organizations often respond in different ways to common external shocks. To advance theories on organizational adaptation and performance heterogeneity, it is essential to understand different reasons for different organizational responses. We examine how incumbents in carbon-intensive industries adapt to heightened environmental pressure to reduce carbon emissions. Based on a review of the literature, we propose three dimensions along which diverse organizational responses can be efficiently mapped out: goal, timing, and scope. Building on our proposed dimensions, we develop a typology of five different organizational responses. With this, we show that organizational responses are more diverse than a one-dimensional scale could show but that the heterogeneity is somehow limited as the positions on the dimensions are not independent but correlated. To understand this observed limited heterogeneity, we proceed by identifying reasons behind different organizational responses. Furthermore, we discuss the theoretical implications of our findings for research on organizational adaptation and sustainability.

scholarly journals Effect of Thrust on the Structural Vibrations of a Nonuniform Slender Rocket

2020 ◽  
Vol 25 (2) ◽  
pp. 29
Author(s):  
Desmond Adair ◽  
Aigul Nagimova ◽  
Martin Jaeger
Keyword(s):  
Natural Frequencies ◽  
Equations Of Motion ◽  
Approximate Solutions ◽  
Mode Shapes ◽  
Algebraic Equations ◽  
Structural Vibrations ◽  
Unknown Parameters ◽  
One Dimensional ◽  
Vibration Problems ◽  
Nonuniform Beam

The vibration characteristics of a nonuniform, flexible and free-flying slender rocket experiencing constant thrust is investigated. The rocket is idealized as a classic nonuniform beam with a constant one-dimensional follower force and with free-free boundary conditions. The equations of motion are derived by applying the extended Hamilton’s principle for non-conservative systems. Natural frequencies and associated mode shapes of the rocket are determined using the relatively efficient and accurate Adomian modified decomposition method (AMDM) with the solutions obtained by solving a set of algebraic equations with only three unknown parameters. The method can easily be extended to obtain approximate solutions to vibration problems for any type of nonuniform beam.

Multi-Parameter Optimization of Damped Linear Continuous Systems

1972 ◽  
Vol 94 (1) ◽  
pp. 1-7 ◽  
Author(s):  
O. B. Dale ◽  
R. Cohen
Keyword(s):  
Optimal Parameter ◽  
Equations Of Motion ◽  
Analytic Solutions ◽  
System Response ◽  
Continuous Systems ◽  
Frequency Interval ◽  
State Variables ◽  
Initial Value ◽  
Unknown Parameters ◽  
One Dimensional

A method is presented for obtaining and optimizing the frequency response of one-dimensional damped linear continuous systems. The systems considered are assumed to contain unknown constant parameters in the boundary conditions and equations of motion which the designer can vary to obtain a minimum resonant response in some selected frequency interval. The unknown parameters need not be strictly dissipative nor unconstrained. No analytic solutions, either exact or approximate, are required for the system response and only initial value numerical integrations of the state and adjoint differential equations are required to obtain the optimal parameter set. The combinations of state variables comprising the response and the response locations are arbitrary.

scholarly journals Parameter Estimation of a Class One-Dimensional Discrete Chaotic System

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Lidong Liu ◽  
Jinfeng Hu ◽  
Huiyong Li ◽  
Jun Li ◽  
Zishu He ◽  
...  
Keyword(s):  
Parameter Estimation ◽  
Chaotic System ◽  
Chaos Control ◽  
Mean Value ◽  
Unknown Parameters ◽  
Tent Map ◽  
One Dimensional ◽  
Chebyshev Map ◽  
Mean Value Method ◽  
Control And Synchronization

It is of vital importance to exactly estimate the unknown parameters of chaotic systems in chaos control and synchronization. In this paper, we present a method for estimating one-dimensional discrete chaotic system based on mean value method (MVM). It is proposed by exploiting the ergodic and synchronization features of chaos. It can effectively estimate the parameter value, and it is more exact than MVM. Finally, numerical simulations on Chebyshev map and Tent map show that the proposed method has better performance of parameter estimation than MVM.

One-dimensional model analysis and performance assessment of Tesla turbine

2018 ◽  
Vol 134 ◽  
pp. 546-554 ◽  
Author(s):  
Jian Song ◽  
Xiao-dong Ren ◽  
Xue-song Li ◽  
Chun-wei Gu ◽  
Ming-ming Zhang
Keyword(s):  
Performance Assessment ◽  
Model Analysis ◽  
Dimensional Model ◽  
One Dimensional ◽  
And Performance

Theoretical Model of a Flow in a Tube With a Slit

2019 ◽  
Author(s):  
Yuki Toda ◽  
Masataka Morimatsu ◽  
Yu Nishio ◽  
Takanobu Ogawa
Keyword(s):  
Theoretical Model ◽  
Flow Field ◽  
Pressure Loss ◽  
Longitudinal Direction ◽  
Gas Mixture ◽  
Straight Tube ◽  
One Dimensional ◽  
Tube Type ◽  
Gas Burner

Abstract A tube-type gas burner consists of a straight tube with a slit along it and discharges an air-gas mixture through the slit to produce a flame. The flow velocity from the slit depends on the pressure in the tube and the pressure loss at the slit, and it varies in the longitudinal direction of the tube. The resulting uneven flame degrades the quality of the burner. In this study, we develop a one-dimensional theoretical model of the flow in a tube with a slit. To validate the result of the theoretical model, we also conduct experiments and numerical simulations for the same flow field. We applied this theoretical model to a flow in a tube, 1 m length, 40 mm in diameter, with a slit 2.5 mm wide. The end of the tube is closed. We also discuss the effect of the length of the burner on the unevenness.

A large-scale framework for symbolic implementations of seismic inversion algorithms in Julia

Geophysics ◽  
2019 ◽  
Vol 84 (3) ◽  
pp. F57-F71 ◽  
Author(s):  
Philipp A. Witte ◽  
Mathias Louboutin ◽  
Navjot Kukreja ◽  
Fabio Luporini ◽  
Michael Lange ◽  
...  
Keyword(s):  
User Interfaces ◽  
Code Generation ◽  
Large Scale ◽  
Waveform Inversion ◽  
Seismic Inversion ◽  
Linear Operators ◽  
Automatic Code Generation ◽  
Unknown Parameters ◽  
And Performance ◽  
Automatic Code

Writing software packages for seismic inversion is a very challenging task because problems such as full-waveform inversion or least-squares imaging are algorithmically and computationally demanding due to the large number of unknown parameters and the fact that waves are propagated over many wavelengths. Therefore, software frameworks need to combine versatility and performance to provide geophysicists with the means and flexibility to implement complex algorithms that scale to exceedingly large 3D problems. Following these principles, we have developed the Julia Devito Inversion framework, an open-source software package in Julia for large-scale seismic modeling and inversion based on Devito, a domain-specific language compiler for automatic code generation. The framework consists of matrix-free linear operators for implementing seismic inversion algorithms that closely resemble the mathematical notation, a flexible resilient parallelization, and an interface to Devito for generating optimized stencil code to solve the underlying wave equations. In comparison with many manually optimized industry codes written in low-level languages, our software is built on the idea of independent layers of abstractions and user interfaces with symbolic operators. Through a series of numerical examples, we determined that this allows users to implement a series of increasingly complex algorithms for waveform inversion and imaging as simple Julia scripts that scale to large-scale 3D problems. This illustrates that software based on the paradigms of abstract user interfaces and automatic code generation and makes it possible to manage the complexity of the algorithms and performance optimizations, thus providing a high-performance research and production framework.

Thermal Management of Downhole Oil and Gas Logging Sensors for HTHP Applications Using Nanoporous Materials

2007 ◽  
Author(s):  
Saeed Rafie
Keyword(s):  
Oil And Gas ◽  
Electrical Response ◽  
Heat Sinks ◽  
Transient Temperature ◽  
Nanoporous Material ◽  
Electronic Components ◽  
Thermal Shield ◽  
One Dimensional ◽  
And Performance ◽  
Downhole Temperature

One of the main challenges in designing oil & gas downhole wireline logging tools for high temperature and high pressure (HTHP) environments is to put together the most efficient thermal packaging to enhance the tool’s temperature survival time. In general, not all electronic components and sensors can withstand severe downhole temperature (max 500 degrees Fahrenheit). For those heat sensitive components, their electrical response and performance either decay or in some cases they completely fail when their temperature exceeds 300° F. In oil & gas wireline logging applications, the heat sensitive components can be thermally protected inside a Dewar vacuum flask that includes one or two thermal isolators and heat sinks. Cooler electronic components results in longer logging times that lead to a much higher performance and profitability. This paper first discusses the development of a one-dimensional analytical model to determine the transient temperature of heat sensitive sensors and electronic components in wireline logging tools. Second, it introduces a new and improved thermal packaging scheme based on a newly developed and commercially available nanoporous material. This material has a very low thermal conductivity and is used as a thermal shield between the outside environment and the electronics inside the flask. The new packaging scheme also includes a new design for the heat sink which is made of several solid disks separated by this nanoporous material. Results from this new design have shown roughly a 30% improvement compared with the conventional design. Results from both analytical and laboratory tests are discussed in this paper.

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