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Advanced CNC thread milling: a comprehensive canned cycle for efficient cutting of threads with fixed or variable pitch and radius

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2024年第5-6期133卷 2219-2233页

作者： Omirou, Sotiris Charalambides, Marios Chasos, Charalambos Frederick Univ Dept Mech Engn Nicosia Cyprus Frederick Univ Ctr Sci Dept Business Adm Nicosia Cyprus

This paper presents the design, implementation, and experimental validation of a novel canned cycle for CNC milling machines, enabling the precise and efficient cutting of threads with fixed or variable pitch and radius. Conventional canned cycles are limited to fixed pitch threads, restricting the versatility of CNC milling machines in thread machining *** development process involves integrating a sophisticated control algorithm into the CNC milling machine's software, giving the operator remarkable control over the thread cutting process. This algorithm allows the operator to choose between external or internal threads, set both initial and final radii, determine initial and final pitches, specify the number of turns, and select the left or right-hand thread type. Such flexibility enables the creation of threads with diverse geometries. Furthermore, the proposed canned cycle provides the capability to switch between roughing and finishing passes by adjusting the step motion along the prescribed helical *** tests conducted under various threading cases clearly demonstrate the efficiency of the proposed canned cycle. These results showcase its capability to address a wide range of machining scenarios, offering practical solutions applicable across a spectrum of applications.

关键词： CNC machining Canned cycles Thread cutting interpolation algorithms

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Design and implementation of an innovative canned cycle for variable pitch thread cutting on CNC milling machines

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2024年第9-10期130卷 4635-4648页

作者： Omirou, Sotiris L. Chasos, Charalambos A. Frederick Univ Dept Mech Engn Nicosia Cyprus

This paper presents the development of a new canned cycle for CNC milling machines capable of cutting threads with variable pitch, addressing a significant limitation in modern CNC systems. While existing CNC milling machines provide canned cycles for thread cutting, they lack the capability to program variable pitch, necessitating reliance on CAM systems. In response, the proposed canned cycle offers increased flexibility, quicker setup times, and reduced dependence on CAM systems. The cycle accommodates both internal and external threads, supports left-hand or right-hand threading, and incorporates a user-friendly control panel for easy programming. To validate its efficiency, the canned cycle is implemented using a G-code parametric algorithm, and a series of simulation tests are conducted. The results demonstrate the viability and advantages of the new CNC milling feature in cutting threads with variable pitch, opening up possibilities for various mechanical applications.

关键词： CNC machining Canned cycles Milling interpolation algorithms

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Provably Convergent Multifidelity Optimization Algorithm Not Requiring High-Fidelity Derivatives

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AIAA JOURNAL 2012年第5期50卷 1079-1089页

作者： March, Andrew Willcox, Karen MIT Dept Aeronaut & Astronaut Cambridge MA 02139 USA

This paper presents a provably convergent multifidelity optimization algorithm for unconstrained problems that does not require high-fidelity gradients. The method uses a radial basis function interpolation to capture the error between a high-fidelity function and a low-fidelity function. The error interpolation is added to the low-fidelity function to create a surrogate model of the high-fidelity function in the neighborhood of a trust region. When appropriately distributed spatial calibration points are used, the low-fidelity function and radial basis function interpolation generate a fully linear model. This condition is sufficient to prove convergence in a trust region framework. In the case when there are multiple lower-fidelity models, the predictions of all calibrated lower-fidelity models can be combined with a maximum likelihood estimator constructed using kriging variance estimates from the radial basis function models. This procedure allows for flexibility in sampling lower-fidelity functions, does not alter the convergence proof of the optimization algorithm, and is shown to be robust to poor low-fidelity information. The algorithm is compared with a single-fidelity quasi-Newton algorithm and two first-order consistent multifidelity trust region algorithms. For simple functions the quasi-Newton algorithm uses slightly fewer high-fidelity function evaluations;however, for more complex supersonic airfoil design problems it uses significantly more. In all cases tested, our radial basis function calibration approach uses fewer high-fidelity function evaluations when compared with first-order consistent trust region schemes.

关键词： algorithms interpolation algorithms CALIBRATION STOCHASTIC convergence MATHEMATICAL models

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Efficient probabilistic contingency analysis through a stability measure considering wind perturbation

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IET GENERATION TRANSMISSION & DISTRIBUTION 2016年第4期10卷 897-905页

作者： Hua, KeQian Vahidnia, Arash Mishra, Yateendra Ledwich, Gerard Queensland Univ Technol Fac Sci & Engn 2 George St Brisbane Qld 4001 Australia RMIT Univ Sch Elect & Comp Engn Melbourne Vic Australia

The integration of stochastic wind power has accentuated a challenge for power system stability assessment. Since the power system is a time-variant system under wind generation fluctuations, pure time-domain simulations are difficult to provide real-time stability assessment. As a result, the worst-case scenario is simulated to give a very conservative assessment of system transient stability. In this study, a probabilistic contingency analysis through a stability measure method is proposed to provide a less conservative contingency analysis which covers 5-min wind fluctuations and a successive fault. This probabilistic approach would estimate the transfer limit of a critical line for a given fault with stochastic wind generation and active control devices in a multi-machine system. This approach achieves a lower computation cost and improved accuracy using a new stability measure and polynomial interpolation, and is feasible for online contingency analysis.

关键词： Wind power Stochastic analysis Perturbation (Mathematics) interpolation algorithms Monte Carlo method Carbon -- Economic aspects

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Bare-earth extraction and DTM generation from photogrammetric point clouds including the use of an existing lower-resolution DTM

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INTERNATIONAL JOURNAL OF REMOTE SENSING 2016年第13期37卷 3104-3124页

作者： Debella-Gilo, Misganu Norwegian Inst Bioecon Res NIBIO Mapping & Stat Div Dept Geomat POB 115 N-1431 As Norway

A method of extracting bare-earth points from photogrammetric point clouds by partially using an existing lower resolution digital terrain model (DTM) is presented. The bare-earth points are extracted based on a threshold defined by local slope. The local slope is estimated from the lower resolution DTM. A gridded DTM is then interpolated from the extracted bare-earth points. Five different interpolation algorithms are implemented and evaluated to identify the most suitable interpolation method for such non-uniformly scattered data. The algorithm is tested on four test sites with varying topographic and ground cover characteristics. The results are evaluated against a reference DTM created using aerial laser scanning. The deviations of the extracted bare-earth points, and the interpolated DTM, from the reference DTM increases with increasing forest canopy density and terrain roughness. The DTM created by the method is significantly closer to the reference DTM than the lower resolution national DTM. The ANUDEM (Australian National University Digital Elevation Modelling) interpolation method is found to be the best performing interpolation method in terms of reducing the deviations and in terms of modelling the terrain realistically with minimum artefacts, although the differences among the interpolation methods are not considerably large.

关键词： DATA extraction DIGITAL elevation models PHOTOGRAMMETRY interpolation algorithms FOREST canopies TERRAIN mapping

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Special version of the collocation method for integral equations of the second kind with singularities in the kernel

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DIFFERENTIAL EQUATIONS 2015年第9期51卷 1236-1242页

作者： Gabbasov, N. S. Galimova, Z. Kh. Kazan Fed Univ Naberezhnye Chelny Inst Naberezhnye Chelny Russia Kazan Inst Econ Management & Law Naberezhnye Chelny Branch Naberezhnye Chelny Russia

We study a linear integral equation of the second kind with fixed singularities in the kernel. For its approximate solution in the space of "pointwise smooth" functions, we suggest and justify a new version ... 详细信息

关键词： INTEGRAL equations SINGULARITIES (Mathematics) KERNEL (Mathematics) SMOOTHNESS of functions interpolation algorithms

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Energy Scaling Law for a Single Disclination in a Thin Elastic Sheet

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ARCHIVE FOR RATIONAL MECHANICS AND ANALYSIS 2017年第3期224卷 985-1019页

作者： Olbermann, Heiner Univ Leipzig Math Inst Postfach 100920 D-04009 Leipzig Germany

We consider a single disclination in a thin elastic sheet of thickness h. We prove ansatz-free lower bounds for the free elastic energy in three different settings: first, for a geometrically fully non-linear plate model;second, for three-dimensional nonlinear elasticity;and third, for the Foppl-von Karman plate theory. The lower bounds in the first and third result are optimal in the sense that we find upper bounds that are identical to the respective lower bounds in the leading order of h.

关键词： SCALING laws (Nuclear physics) SCALING laws (Statistical physics) DISCLINATIONS NONLINEAR elastic fracture interpolation algorithms COERCIVE fields (Electronics)

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Development of City-Wide Road Grade Profiles Utilising Advanced Bus Transportation Systems

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IFAC-PapersOnLine 2018年第9期51卷 428-433页

作者： Singla, Tushti Brady, Mike Magrath, Jared School of Computer Science and Statistics University of Dublin Trinity College Dublin Ireland

Road grade is of vital importance in determining a vehicle's fuel consumption and therefore in designing eco-routing solutions. Consequently, there is a need to develop accurate road grade profiles on a large scale with a high degree of accuracy. Advanced Bus Transportation Systems (ABTS) provide an opportunity to collect large amounts of data about bus routes in the form of GPS traces, which in turn could enable the development of road grade profiles within a large catchment area. This paper reports on an approach to developing large scale road grade profiles in a multistep process. The work investigates the use of GPS trace information from Dublin Bus, combined with elevation information from the Shuttle Radar Topography Mission (SRTM) to develop road grade profiles for all bus routes in the company's system, covering the major areas of the city of Dublin, Ireland. The results are compared with road grades derived from Google elevation data. © 2018

关键词： Bus transportation Catchments Global positioning system Roads and streets Signal processing Tracking radar Transportation Transportation routes Elevation Filtering technique interpolation algorithms Openstreetmap Road grades Smoothing filters Transportation system

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High accuracy Hough transform based on butterfly symmetry

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ELECTRONICS LETTERS 2012年第4期48卷 199-U200页

作者： Du, Shengzhi Tu, Chunling Sun, Mingwei Univ S Africa Dept Elect & Min Engn ZA-0001 Pretoria South Africa Tshwane Univ Technol Dept Elect Engn Pretoria South Africa Nankai Univ Dept Automat Tianjin 300071 Peoples R China

The theoretical symmetry in Hough transform (HT) butterflies is addressed. The reason the symmetry is damaged in real HT butterflies is analysed and employed to propose a high accuracy HT. Experiment demonstrates that... 详细信息

关键词： COMPUTER vision interpolation algorithms GAUSSIAN distribution PREDICATE calculus ROBUST control

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Switching-based variable step-size approach for partial update LMS algorithms

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ELECTRONICS LETTERS 2013年第17期49卷 1081-1082页

作者： Chien, Y. -R. Tseng, W. -J. Natl Ilan Univ Dept Elect Engn Ilan City 26041 Taiwan

A switching-based variable step-size approach for partial update least-mean-square (LMS) algorithms is proposed. During the initial stage, the errors are dominated by the mismatch between the tap weights of the adaptive filter and its ideal weights. In this reported work, the error signals are correlated with the linear interpolated error signals to gain a large step-size;on the other hand, during the steady state, the errors mainly come from the additive noise. Therefore, the correlation is switched to the other mode so that the effect of noise can be eliminated. This can be done by correlating the error signals with a delayed version of the error signals, hence a small step-size is obtained during the late stages. Simulation results show that when only a half of all taps are updated in one iteration, the proposed method significantly enhances the convergence rate, especially for the 'data independent' partial update LMS algorithms.

关键词： ADAPTIVE filters ADDITIVE functions LEAST squares interpolation algorithms ANALOG integrated circuits

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