A Five-Axis Dual NURBS Interpolator With Constant Speed at Feedrate-Sensitive Regions Under Axial Drive Constraints

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Jian-wei Ma ◽  
Zhen-yuan Jia ◽  
Feng-ze Qin ◽  
De-ning Song ◽  
Wen-wen Jiang ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Constant Speed ◽  
Smooth Transition ◽  
Motion Stability ◽  
Nurbs Interpolator ◽  
Transition Speed ◽  
Incremental Value ◽  
Five Axis ◽  
Linear Interpolator ◽  
Selection Of

In the five-axis machining, the dual nonuniform rational B-spline (NURBS) interpolator performs better than the conventional linear interpolator in improving machining efficiency and quality. However, a successful dual NURBS interpolator faces with two aspects of issues. First, the feedrate should be reasonably scheduled according to axial drive constraints. Furthermore, the axial trajectories should be precisely and rapidly calculated according to the scheduled feedrate. To schedule the feedrate, existing methods use either overall constant speed or frequent time-varying speed. However, the former one is adverse to the motion efficiency, while the latter one is adverse to the motion stability. To deal with these issues, this study schedules feedrate-sensitive and nonsensitive regions and plans constant speed at the sensitive regions and smooth transition speed within the nonsensitive regions, thus balancing the motion stability and the efficiency. In addition, to calculate the axial trajectories, existing methods, using inverse kinematics, result in multiple solutions due to the existence of antitrigonometric functions, and this requires complicated selection of the solutions, otherwise the axial positions will be discontinuity. To deal with this issue, this study proposes a Jacobi matrix-based Adams prediction–correction numerical algorithm, which uses the incremental value of the tool pose to calculate the consecutive unique solution of the five-axis positions directly. By integrating above techniques, a systematic five-axis dual NURBS interpolator with the constant speed at feedrate-sensitive regions under axial drive constraints is presented. Experimental tests are conducted to evaluate the effectiveness of the proposed method.

SELECTION OF CONTROLLABLE PARAMETERS OF THE BINARY DATA ARRAY DETECTION ALGORITHM IN THE INTEGRATED MANAGEMENT SYSTEM

2021 ◽  
Vol 4 (3) ◽  
pp. 11-18
Author(s):  
Khakimjon Zaynidinov ◽  
◽  
Odilbek Askaraliyev
Keyword(s):  
Management System ◽  
Binary Data ◽  
Integrated Management ◽  
Research Work ◽  
Hash Functions ◽  
Experimental Tests ◽  
Detection Algorithm ◽  
Identification Algorithm ◽  
Solution Algorithms ◽  
Selection Of

The article discusses the selection of parameters for the algorithm for determining binary data arrays included in the control system, developed by the authors using independent substitution methods. Based on the analysis of the algorithms of non-cryptographic hash functions, the hash function based on the linear matching method was selected as the basis for independent substitution methods. Simplified schemes of algorithms developed for creating and comparing identifiers using a set of basic hash functions are given. An array of binary data was selected and based on the appropriate values for the size of the divisible blocks and the number of basic hashfunctions used for independent substitutions. The selection of binary data arrays in information systems integrated into the management system was done for the purpose of intellectual processing of incoming data. The properties of the array of data entering integrated systems are studied. The authors conducted experimental tests in the selected direction and presented the results of similarity assessment measurements for various parameters of the identification algorithm. In addition, the article conductedexperiments on the object of study using the selected mathematical model, based on the analytical conclusions. Initiator elements are studied and analyzed using a set of hash functions. An algorithm for comparison of selected identifiers has been developed. A generation algorithm has been developed to demonstrate and test the proposed solution. Algorithms based on analysis and experiments, and methods for selecting binary data arrays using the ash function have been experimentally tested. Based on the results, the indicators are shown. Based on the results obtained, the analytical conclusions and problem solutions of the research work were recognized

Dynamic Hybrid Modeling of the Vertical Z Axis in a High-Speed Machining Center: Towards Virtual Machining

2007 ◽  
Vol 129 (4) ◽  
pp. 780-788 ◽  
Author(s):  
Giovanni Tani ◽  
Raffaele Bedini ◽  
Alessandro Fortunato ◽  
Claudio Mantega
Keyword(s):  
High Speed ◽  
Experimental Tests ◽  
Pneumatic System ◽  
Mechanical Structure ◽  
Virtual Machining ◽  
Feed Drive ◽  
Machining Center ◽  
Dynamic Hybrid ◽  
Five Axis ◽  
Machine Head

This paper describes the modeling and simulation of the Z axis of a five axis machining center for high-speed milling. The axis consists of a mechanical structure: machine head and electro-mandrel, a CNC system interfaced with the feed drive, and a pneumatic system to compensate for the weight of the vertical machine head. These subsystems were studied and modeled by means of: (1) finite element method modeling of the mechanical structure; (2) a concentrated parameter model of the kinematics of the axis; (3) a set of algebraic and logical relations to represent the loop CNC-Z feed drive; (4) an equation set to represent the functioning of the pneumatic system; and (5) a specific analytical model of the friction phenomena occurring between sliding and rotating mechanical components. These modeled subsystems were integrated to represent the dynamic behavior of the entire Z axis. The model was translated in a computer simulation package and the validation of the model was made possible by comparing the outputs of simulation runs with the records of experimental tests on the machining center. The firm which promoted and financed the research now has a virtual tool to design improved machine-tool versions with respect to present models, designed by traditional tools.

Utilizing Modeling in a Reliability Study of ACA Joints in Humidity Tests

2013 ◽  
Vol 10 (1) ◽  
pp. 30-39 ◽  
Author(s):  
Kirsi Saarinen ◽  
Laura Frisk
Keyword(s):  
Radio Frequency Identification ◽  
Cost Savings ◽  
Experimental Tests ◽  
Shear Stresses ◽  
Cycling Test ◽  
Humidity Level ◽  
Anisotropic Conductive Adhesive ◽  
Frequency Identification ◽  
Identification Tags ◽  
Selection Of

Radio frequency identification tags (RFID) with anisotropic conductive adhesive (ACA) joints are used in various applications where the environmental conditions may impair their reliability. Thus the effects of different environmental stresses on reliability need to be investigated. The purpose of this work was to study whether a relatively simple shear stress model can be utilized in reliability prediction of anisotropically conductive paste (ACP) joints in an accelerated humidity test on the basis of the information obtained from another humidity test. If modeling gives accurate results when studying reliability, the need for actual testing would decrease and thereby time and cost savings could be achieved. In this study, finite element models were made to calculate shear stresses in ACP joints induced by two different humidity tests. Additionally, experimental tests were performed and the results were compared with those of modeling. The test samples were RFID tags whose microchips were attached with ACP. A constant humidity test was used to study the effects of high humidity level and a humidity cycling test was used to examine the effects of constantly varying humidity. In the modeling it was observed that the selection of the stress-free temperature has a significant effect on the results. With three different stress-free temperatures, three different sets of results were obtained. Although the tags saturated in the extreme conditions of the humidity cycling test, according to modeling, the change in relative humidity level in the humidity cycling test did not increase the harshness of the test. However, the temperature change in the humidity cycling test increased the harshness.

Vibration Based Condition Monitoring of Helicopter Gearboxes Based on Cyclostationary Analysis

2019 ◽  
Author(s):  
Alexandre Mauricio ◽  
Linghao Zhou ◽  
David Mba ◽  
Konstantinos Gryllias
Keyword(s):  
Experimental Tests ◽  
Operational Reliability ◽  
Health Condition ◽  
Operating Conditions ◽  
False Alarms ◽  
Complex Structures ◽  
Planetary Gearbox ◽  
Bearing Defects ◽  
Envelope Spectrum ◽  
Selection Of

Abstract The core of a helicopter drivetrain is a complex planetary main gearbox (MGB) which reduces the high input speed generated by the engines in order to provide the appropriate torque to the main rotors and to other auxiliary systems. The gearbox consists of various shafts, planetary gears and bearings and operates under varying conditions under excessive friction, heat and high mechanical forces. The components are vulnerable to fatigue defects and therefore Health and Usage Monitoring Systems (HUMS) have been developed in order to monitor the health condition of the gearbox, focusing towards early, accurate and on time fault detection with limited false alarms and missed detections. The main aim of a HUM System is by health monitoring to enhance the helicopters’ operational reliability, to support the maintenance decision making, and to reduce the overall maintenance costs. The importance and the need for more advanced and accurate HUMS have been emphasized recently by the post-accident analysis of the helicopter LN-OJF, which crashed in Norway in 2016. During the last few decades various methodologies and diagnostic indicators/features have been proposed for the monitoring of rotating machinery operating under steady conditions but still there is no global solution for complex structures. A new tool called IESFOgram has been recently proposed by the authors, based on Cyclostationary Analysis, focusing on the accurate selection of a filtering band, under steady and varying speed conditions. Moreover the Cyclic Spectral Coherence is integrated along the selected frequency band leading to an Improved Envelope Spectrum. In this paper the performance of the tool is tested on a complex planetary gearbox, with several vibration sources. The method is tested, evaluated and compared to state of the art methods on a dataset captured during experimental tests under various operating conditions on a Category A Super Puma SA330 main planetary gearbox, presenting seeded bearing defects of different sizes.

The Impact of Modelling Air Compressibility in the Selection of Optimal OWC Design Parameters in Site Specific Wave Conditions

2019 ◽  
Author(s):  
Irene Simonetti ◽  
Lorenzo Cappietti
Keyword(s):  
Fluid Dynamic ◽  
Experimental Tests ◽  
Design Parameters ◽  
Dynamic Simulations ◽  
Regression Approach ◽  
Wave Conditions ◽  
A Site ◽  
The Impact ◽  
Period Wave ◽  
Selection Of

Abstract The importance of properly modelling the effects of air compressibility in the selection of the optimal design parameters for an Oscillating Water Column wave energy converter is investigated. For this purpose, a wide dataset of capture width ratios, obtained from both experimental tests and Computational Fluid Dynamic simulations, is used to formulate an empirical model able to predict the performance of the device as a function of its basic design parameters (chamber width and draught, turbine damping) and of the wave conditions (wave period, wave height). A multiple non-linear regression approach is used to determine the model numerical coefficients. The data used to formulate the model include the effects of air compressibility. The impact of considering such effects on the selection of the optimal geometry of the device is evaluated and discussed by means of the model application for the optimization of a device to be installed in a site located in the Mediterranean Sea (in front of the coast of Tuscany, Italy).

A Feature-Based Morphing Methodology for Biological Structures Applied to the Spatial Organization of Cardiomyocytes in the Left Atrium

2011 ◽  
Author(s):  
Alessandro Satriano ◽  
Edward J. Vigmond ◽  
Elena S. Di Martino
Keyword(s):  
Spatial Organization ◽  
Experimental Tests ◽  
Smooth Transition ◽  
Patient Specific ◽  
Clinical Environment ◽  
Individual Values ◽  
Tissue Properties ◽  
Biological Structures ◽  
Critical Issues ◽  
Parameter Values

When complex biological structures are modeled, one of the most critical issues is the assignment of geometrical, mechanical and electrical properties to the meshed surfaces. Properties of interest are commonly obtained from diagnostic imaging, experimental tests or anatomical observation. These parameters are usually lumped into individual values assigned to a specific region after subdividing the structure in sub-regions. This practice simplifies the problem avoiding the cumbersome assignment of parameter values to each element. However, sub-regions may not adequately represent the smooth transition between regions thus resulting in artificial discontinuities. In addition, some parameters, such as for example the organization of cardiomyocytes, which is the objective of our research, may be obtained through destructive tests or through sophisticated methods that can only be performed on a limited number of samples. Or else, data structure obtained for one animal species could be applied on a different species. Furthermore, in a clinical environment the need for fast turnout of patient-specific models would benefit from the assignment of tissue properties in a semi-automatic manner.

Optoelectronic generation of transient waveforms for UWB radars with rejected frequencies

2020 ◽  
Vol 12 (7) ◽  
pp. 543-550
Author(s):  
Jeremy Hyvernaud ◽  
Gwenael Reineix ◽  
Romain Negrier ◽  
Joel Andrieu ◽  
Michele Lalande ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Design System ◽  
System Software ◽  
Optoelectronic System ◽  
Short Pulses ◽  
Semiconductor Switches ◽  
Number Of Generators ◽  
Set Up ◽  
Switching Mode ◽  
Selection Of

AbstractIn this paper, a new design of an optoelectronic system for transient waveforms shaping, with a selection of rejected frequencies, is presented. The generation of short pulses is performed with several optoelectronic generators using photoconductive semiconductor switches (PCSS) operating in linear switching mode and triggered via a laser pulse. With the appropriate number of generators, the system generates a spectrum ranging from 300 MHz to 3 GHz, with rejected frequencies at 900 MHz and 1.8 GHz. A PCSS characterization has been set up to determine the necessary parameters for the establishment of an optoelectronic generator model on Keysight Advanced Design System software (ADS). Experimental tests have been realized using measurement benches to compare the simulated and measured signals.

A Study on μ-Synthesis Control for Four-Wheel Steering System to Enhance Vehicle Lateral Stability

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Guo-Dong Yin ◽  
Nan Chen ◽  
Jin-Xiang Wang ◽  
Ling-Yao Wu
Keyword(s):  
Control System ◽  
Experimental Tests ◽  
Steering System ◽  
Hardware In The Loop ◽  
Steering Control ◽  
Robust Controller ◽  
Control Scheme ◽  
Parameter Variations ◽  
Good Vehicle ◽  
Selection Of

This paper presents the design of μ-synthesis control for four-wheel steering (4WS) vehicle and an experimental study using a hardware-in-the-loop (Hil) setup. First, the robust controller is designed and the selection of weighting functions is discussed in the framework of μ-synthesis control scheme, considering the varying parameters induced by running vehicle condition. Second, in order to investigate the feasibility of the four-wheel steering control system, the 4WS vehicle control system is built using dSPACE DS1005 platform. The experimental tests are performed using the Hil setup which has been constructed using the devised rear steering actuating system. The dynamics performance is evaluated by experiment using the Hil setup under the condition of parameter variations. Finally, experimental results show that the μ-synthesis controller can enhance good vehicle lateral maneuverability.

Automatic Generation of Piecewise Constant Speed Motion with Smooth Transition for Multi-Axis Machines

1994 ◽  
Vol 116 (2) ◽  
pp. 581-586 ◽  
Author(s):  
D. C. H. Yang ◽  
Jui-Jen Chou
Keyword(s):  
Automatic Generation ◽  
Constant Speed ◽  
Smooth Transition ◽  
Speed Profile ◽  
Piecewise Constant ◽  
Smooth Motion ◽  
Path Geometry ◽  
Five Axes ◽  
The Given ◽  
Motion Profile

This paper presents a general theory on generating a smooth motion profile for the coordinated motion of five-axes CNC/CMM machines. Motion with constat speed is important and required in many manufacturing processes, such as milling, welding, finishing, and painting. In this paper, a piecewise constant speed profile is constructed by a sequence of Hermite curves to form a composite Hermite curve in parametric domain. Given the continuity of acceleration in our proposed speed profile, it generates relatively better product quality than traditional techniques. We also provide a method for the feasibility study of manufacturing capability in terms of the given machine, the desired path, and the assigned speed. We consider machine dynamics, actuator limitation, path geometry, jerk constraints, and motion kinematics.

scholarly journals Thermal Characterization of Medium-Temperature Phase Change Materials (PCMs) for Thermal Energy Storage Using the T-History Method

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7371
Author(s):  
Paulina Rolka ◽  
Roman Kwidzinski ◽  
Tomasz Przybylinski ◽  
Adam Tomaszewski
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Thermophysical Properties ◽  
Phase Change Materials ◽  
Experimental Tests ◽  
Stored Energy ◽  
Medium Temperature ◽  
Heating Systems ◽  
Selection Of

To reduce energy consumption and increase energy efficiency in the building sector, thermal energy storage with phase change materials (PCMs) is used. The knowledge of the thermophysical properties and the characteristics of PCMs (like their enthalpy changes and the distribution of stored energy over a specified temperature range) is essential for proper selection of the PCM and optimal design of the latent thermal energy store (LHTES). This paper presents experimental tests of the thermophysical properties of three medium-temperature PCMs: OM65, OM55, RT55, which can be used in domestic hot water installations and heating systems. Self-made test chambers with temperature control using Peltier cells were used to perform measurements according to the T-history method. In this way the temperature range of the phase transition, latent heat, specific heat capacity, enthalpy and the distributions of stored energy of the three PCMs were determined. The paper also presents measurements of the thermal conductivity of these PCMs in liquid and solid state using a self-made pipe Poensgen apparatus. The presented experimental tests results are in good agreement with the manufacturers’ data and the results of other researchers obtained with the use of specialized instruments. The presented research results are intended to help designers in the selection of the right PCM for the future LHTES co-working with renewable energy systems, waste heat recovery systems and building heating systems.

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