scholarly journals Development of a Control-Oriented Model of the Vertical Motions of a Fast Ferry

2004 ◽  
Vol 48 (03) ◽  
pp. 218-230
Author(s):  
Segundo Esteban ◽  
Jose M. Giron-Sierra ◽  
Bonifacio de Andres-Toro ◽  
Jesus M. de la Cruz
Keyword(s):  
Computer Aided Design ◽  
High Speed ◽  
Research Study ◽  
Control Strategies ◽  
Simulated Data ◽  
Irregular Waves ◽  
Towing Tank ◽  
Aided Design ◽  
The Impact ◽  
Good Agreement

As a main part of a research study on the control of active flaps and a T-foil of a high-speed ferry, a control-oriented model of vertical motions of the ship has been developed. The objective of the control is to improve comfort, decreasing the impact of heave and pitch motions. We have experimental data from a towing tank institution and simulations with PRECAL. The model is based on a decomposition of the physic phenomena into two main aspects: the coupling of the ship with distance between waves and the dynamics of a semisubmerged mass. The model can be handled with MATLAB-SIMULINK, which is useful for studying control strategies. The model shows good agreement (model validation) with the experimental and simulated data for regular and irregular waves. The article shows a methodology, based on MATLAB tools, for obtaining control-oriented models from computer-aided design (CAD)–based programs. That means that the control-oriented model can be derived from the ship design, even before the ship is built.

scholarly journals Incremental Automatic Correction for Digital VLSI Circuits

2020 ◽  
Author(s):  
Lamya Gaber ◽  
Aziza I. Hussein ◽  
Mohammed Moness
Keyword(s):  
Computer Aided Design ◽  
High Speed ◽  
Negative Impact ◽  
Positive Impact ◽  
Vlsi Circuits ◽  
Digital Vlsi ◽  
Large Numbers ◽  
Aided Design ◽  
The Impact ◽  
Compact Test

The impact of the recent exponential increase in complexity of digital VLSI circuits has heavily affected verification methodologies. Many advances toward verification and debugging techniques of digital VLSI circuits have relied on Computer Aided Design (CAD). Existing techniques are highly dependent on specialized test patterns with specific numbers increased by the rising complexity of VLSI circuits. A second problem arises in the form of large sizes of injecting circuits for correction and large number of SAT solver calls with a negative impact on the resultant running time. Three goals arise: first, diminishing dependence on a given test pattern by incrementally generating compact test patterns corresponding to design errors during the rectification process. Second, to reduce the size of in-circuit mutation circuit for error-fixing process. Finally, distribution of test patterns can be performed in parallel with a positive impact on digital VLSI circuits with large numbers of inputs and outputs. The experimental results illustrate that the proposed incremental correction algorithm can fix design bugs of type gate replacements in several digital VLSI circuits from ISCAS'85 with high speed and full accuracy. The speed of proposed Auto-correction mechanism outperforms the latest existing methods around 4.8x using ISCAS'85 benchmarks. The parallel distribution of test patterns on digital VLSI circuits during generating new compact test patterns achieves speed around 1.2x compared to latest methods.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

TCAD Study of the Raised SiGe Source/Drain in 40nm PMOS

2015 ◽  
Vol 645-646 ◽  
pp. 70-74 ◽  
Author(s):  
Min Zhong ◽  
Yu Hang Zhao ◽  
Shou Mian Chen ◽  
Ming Li ◽  
Shao Hai Zeng ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Critical Role ◽  
Sige Layer ◽  
Strain Engineering ◽  
Effect Transistor ◽  
Simulation Results ◽  
Aided Design ◽  
The Relationship ◽  
Growth Experiments ◽  
Good Agreement

An embedded SiGe layer was applied in the source/drain areas (S/D) of a field-effect transistor to boost the performance in the p channels. Raised SiGe S/D plays a critical role in strain engineering. In this study, the relationship between the SiGe overfilling and the enhancement of channel stress was investigated. Systematic technology computer aided design (TCAD) simulations of the SiGe overfill height in a 40 nm PMOS were performed. The simulation results indicate that a moderate SiGe overfilling induces the highest stress in the channel. Corresponding epitaxial growth experiments were done and the obtained experimental data was in good agreement with the simulation results. The effect of the SiGe overfilling is briefly discussed. The results and conclusions presented within this paper might serve as useful references for the optimization of the embedded SiGe stressor for 40 nm logic technology node and beyond.

Pathfinder Algorithm Modification for CPLD and FPGA Routing Stage

2021 ◽  
Vol 26 (5) ◽  
pp. 399-409
Author(s):  
M.A. Zapletina ◽  
◽  
S.V. Gavrilov ◽  
◽  
Keyword(s):  
Computer Aided Design ◽  
Digital Circuits ◽  
Routing Algorithm ◽  
Design Flow ◽  
Negative Effect ◽  
Industrial Projects ◽  
Placement And Routing ◽  
Aided Design ◽  
The Impact

One of the main advantages of FPGA and CPLD is the high development speed; therefore, the importance of effective computer-aided design tools for modern microcircuits of these classes cannot be overestimated. Placement and routing are the most time-consuming stages of FPGA/CPLD design flow. The quality of results of these stages is crucial to the final perfor-mance of custom digital circuits implemented on FPGA/CPLD. The paper discusses an approach to accelerating the routing stage within the layout synthesis flow for FPGA/CPLD by introducing a few algorithmic improvements to a routing procedure. The basic routing algorithm under study is a modified Pathfinder for a mixed routing resource graph. Pathfinder is a well-known negotiation-based routing algorithm that works on the principle of iteratively eliminating congestions of chip routing resources. For experiments, the sets of test digital circuits ISCAS'85, ISCAS'89, LGSynth'89 and several custom industrial projects were used. The impact of the proposed algorithmic improvements was analyzed using four FPGA/CPLD architectures. It has been established that due to the improvements of the algorithm proposed in the paper, the average reduction in routing time was from 1.3 to 2.6 times, depending on the FPGA/CPLD architecture, with no significant negative effect on the timing characteristics of the designed circuits.

SLAM CHARACTERISTICS OF A HIGH-SPEED WAVE PIERCING CATAMARAN IN IRREGULAR WAVES

2021 ◽  
Vol 156 (A1) ◽  
Author(s):  
B J French ◽  
G A Thomas ◽  
M R Davis
Keyword(s):  
Vertical Velocity ◽  
Significant Wave Height ◽  
High Speed ◽  
Irregular Waves ◽  
Two Dimensional ◽  
Towing Tank ◽  
Filling Height ◽  
Load Distributions ◽  
Poor Indicator ◽  
Wave Elevations

Slam characteristics of a 112m INCAT wave piercing catamaran in a range of realistic irregular sea conditions are presented in this paper. Towing tank testing of a 2.5 m hydroelastic segmented catamaran model was used to gather a database of slam events in irregular seas. The model was instrumented to measure motions, centrebow surface pressures and forces, encountered wave elevations and wave elevations within the bow area tunnel arches. From these measurements characteristics of the vessel slamming behaviour are examined: in particular relative vertical velocity, centrebow immersion, archway wave elevations and slam load distributions. A total of 2,098 slam events were identified over 22 different conditions, each containing about 80 to 100 slam events. The data, although inherently scattered, shows that encounter wave frequency and significant wave height are important parameters with regard to centrebow slamming. Relative vertical velocity was found to be a poor indicator of slam magnitude and slams were found to occur before the centrebow arch tunnel was completely filled, supporting the application of a two-dimensional filling height parameter as a slam indicator.

Effect of In-office Bleaching on Color, Translucency, and Whiteness Variations in CAD-CAM Monolithic Materials

2021 ◽  
Author(s):  
RG Fonseca ◽  
RC Peńa ◽  
R Simóes ◽  
AC Ramos ◽  
LN Dovigo
Keyword(s):  
Optical Properties ◽  
Computer Aided Design ◽  
Calculated Data ◽  
Color Difference ◽  
Deionized Water ◽  
Stain Removal ◽  
Computer Aided ◽  
Cad Cam ◽  
Aided Design ◽  
The Impact

SUMMARY Little is known about the impact of bleaching on the optical properties of computer-aided design and computer-aided manufactured (CAD-CAM) monolithic materials. The aim of the present study was to evaluate the effect of one session of in-office bleaching on stain removal, staining susceptibility, translucency, and whiteness variations of CADCAM monolithic materials. Disks were fabricated from Lava Ultimate (LU), Vita Enamic (VE), Vita Suprinity (VS), and IPS e.max CAD (IPS). A spectrophotometer was used to register Commission Internationale de l’Eclairage L*a*b* coordinates. For stain removal, 80 specimens from each material were assessed at baseline (R0) and after immersion in deionized water or coffee for 365 days followed or not by bleaching with 40% hydrogen peroxide (R1). For staining susceptibility, 80 specimens from each material were analyzed at baseline (R0’), and after having been bleached or not and immersed in deionized water or coffee (R1’). Both analyses were calculated as the color difference (ΔE00) between R1-R0 and R1’-R0’, respectively. Differences in translucency (ΔTP00) and whiteness (ΔWID) between R1-R0 and R1’-R0’ were also calculated. Data were analyzed by three-way ANOVA and the Games-Howell post hoc test (α=0.05). Clinical significance was based on 50%:50% perceptibility and acceptability thresholds for ΔE00, ΔTP00 and ΔWID, respectively. Surfaces were analyzed by scanning electron microscopy. Coffee increased ΔE00 in LU, VE, and VS, and decreased their translucency and whiteness, whereas the IPS had only its whiteness affected. Bleaching after immersion in coffee decreased ΔE00 in LU and VE, and increased translucency and whiteness of LU, VE, and VS. No effect was observed on IPS. Bleaching before immersion in coffee decreased translucency of LU, but within the acceptable interval, while VE exhibited lower ΔE00, and became more translucent and less dark. Both VS and IPS were not affected. One session of in-office bleaching benefited optical properties of the previously stained LU, VE, and VS, without increasing their susceptibility to staining or adversely providing clinically unacceptable variations in their translucency and whiteness. All variations exhibited by the IPS were below the perceptible threshold.

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