Thermal Error Modelling of a CNC Machine Tool Feed Drive System using FEA Method

Recirculating ball screw systems are commonly used in machine tools and are one of the major heat sources which cause considerable thermal drift in CNC machine tools. Finite Element Analysis (FEA) method has been used successfully in the past to model the thermal characteristics of machine tools with promising results. Since FEA predictions are highly dependent on the efficacy of numerical parameters including the surrounding Boundary Conditions (BC), this study emphasises on an efficient modelling method to obtain optimised numerical parameters for acquiring a qualitative response from the feed drive system model. This study was performed on a medium size Vertical Machining Centre (VMC) feed drive system in which two parameter dentification methods have been employed; the general prediction method based on formulae provided by OEMs, and the energy balance method. The parameters obtained from both methods were applied to the FEA model of the machine feed drive system and validated against experimental results. Correlation with which was increased from 70 % to 80 % using the energy balance method

Discrete/finite element modelling of rock cutting with a TBM disc cutter

The final publication is available at Springer via http://dx.doi.org/10.1007/s00603-016-1133-7This paper presents advanced computer simulation of rock cutting process typical for excavation works in civil engineering. Theoretical formulation of the hybrid discrete/finite element model has been presented. The discrete and finite element methods have been used in different subdomains of a rock sample according to expected material behaviour, the part which is fractured and damaged during cutting is discretized with the discrete elements while the other part is treated as a continuous body and it is modelled using the finite element method. In this way, an optimum model is created, enabling a proper representation of the physical phenomena during cutting and efficient numerical computation. The model has been applied to simulation of the laboratory test of rock cutting with a single TBM (tunnel boring machine) disc cutter. The micromechanical parameters have been determined using the dimensionless relationships between micro- and macroscopic parameters. A number of numerical simulations of the LCM test in the unrelieved and relieved cutting modes have been performed. Numerical results have been compared with available data from in-situ measurements in a real TBM as well as with the theoretical predictions showing quite a good agreement. The numerical model has provided a new insight into the cutting mechanism enabling us to investigate the stress and pressure distribution at the tool–rock interaction. Sensitivity analysis of rock cutting performed for different parameters including disc geometry, cutting velocity, disc penetration and spacing has shown that the presented numerical model is a suitable tool for the design and optimization of rock cutting process.Peer ReviewedPostprint (published version

Bidding Strategy with Forecast Technology Based on Support Vector Machine in Electrcity Market

The participants of the electricity market concern very much the market price evolution. Various technologies have been developed for price forecast. SVM (Support Vector Machine) has shown its good performance in market price forecast. Two approaches for forming the market bidding strategies based on SVM are proposed. One is based on the price forecast accuracy, with which the being rejected risk is defined. The other takes into account the impact of the producer's own bid. The risks associated with the bidding are controlled by the parameters setting. The proposed approaches have been tested on a numerical example.Comment: 8pages, 13figures, paper for the conference "Applications of Physics in Financial Analysis 6th International Conference

Magnetic vibration analysis of a new DC-excited multitoothed switched reluctance machine

GQ - Electrical Machines for industrial and automotive applicationsThis journal issue contains selected papers from the 2014 IEEE International Magnetics (INTERMAG) ConferenceThis paper proposes a combined numerical and analytical approach for magnetic vibration analysis of a new dc-excited multitoothed switched reluctance (MSR) machine. First, the machine design is artfully to incorporate the dc-excited winding into the MSR topology, hence breeding a new flux controllable, high-torque, low-torque ripple, and doubly salient magnetless machine. Then, the finiteelement-method is used to calculate the machine force and torque. A series of analytical equations are formulated to calculate the magnetic vibration parameters of the proposed machine. The analysis process and the corresponding results are given to verify the validity of the proposed approach for magnetic vibration analysis of the new machine.published_or_final_versio

General expression for the component size distribution in infinite configuration networks

In the infinite configuration network the links between nodes are assigned randomly with the only restriction that the degree distribution has to match a predefined function. This work presents a simple equation that gives for an arbitrary degree distribution the corresponding size distribution of connected components. This equation is suitable for fast and stable numerical computations up to the machine precision. The analytical analysis reveals that the asymptote of the component size distribution is completely defined by only a few parameters of the degree distribution: the first three moments, scale and exponent (if applicable). When the degree distribution features a heavy tail, multiple asymptotic modes are observed in the component size distribution that, in turn, may or may not feature a heavy tail

Integrating tools to improve finite element models of machine tools via experimental modal data

International audienceThis paper presents a specific procedure to improve FE models of multi-axis machine tools that integrates well-tested numerical and experimental techniques for this type of mechanical systems: modal analysis and testing, Design of Experiments (DoE), sensitivity analysis and model updating. First, it is shown that experimental modal analysis must be performed by exciting the machine tool along every main direction and in different geometrical configurations to obtain a complete set of mode shapes and to evaluate the variation of critical parameters like stiffness of joints. In addition, it is demonstrated the interest of using lumped-mass models and DoE techniques to set limit values for parameters that describe joints between structural components and connections to the machine foundation. Results confirm that sensitivity based model updating using natural frequencies and MAC values as responses provides improved FE models that match reasonably well with experimental data

Variational Quantum Approximate Spectral Clustering for Binary Clustering Problems

In quantum machine learning, algorithms with parameterized quantum circuits (PQC) based on a hardware-efficient ansatz (HEA) offer the potential for speed-ups over traditional classical algorithms. While much attention has been devoted to supervised learning tasks, unsupervised learning using PQC remains relatively unexplored. One promising approach within quantum machine learning involves optimizing fewer parameters in PQC than in its classical counterparts, under the assumption that a sub-optimal solution exists within the Hilbert space. In this paper, we introduce the Variational Quantum Approximate Spectral Clustering (VQASC) algorithm - a NISQ-compatible method that requires optimization of fewer parameters than the system size, N, traditionally required in classical problems. We present numerical results from both synthetic and real-world datasets. Furthermore, we propose a descriptor, complemented by numerical analysis, to identify an appropriate ansatz circuit tailored for VQASC.Comment: 21 pages, 6 figure

Volume flexible multi items inventory system with imprecise environment

This paper addresses a multi items volume flexible system for time dependent decaying items with the concept of machine breakdown and imprecise environment. In this study, partially backlogged shortages have been discussed. All the costs are fuzzified with signed distance method. Numerical examples are given to illustrate the theoretical results and sensitivity analysis is given to validate the results for various parameters

A concept for a novel polymer extruder part 1: active grooved feed section

This paper presents a novel concept for an extruder to be used with plastics and polymer composites, especially in the food industry. The design solutions include a grooved feed section with adjustable geometric parameters, which makes it possible for dynamic adjustment of the depth, inclination angle and number of grooves used for granulate transport during continuous operation of the machine. The proposed grooved feed section concept facilitates optimum performance, and is adjustable to suit the general parameters of production. The scope of our study also included the numerical strength and thermal analysis of the designed grooved feed section, conducted using the finite element method. Numerical calculation involved a coupled temperaturedisplacement analysis which constituted a geometrically and physically non-linear problem. The results corroborated the achievement of satisfactory strength for the structural elements of the grooved feed section in the extruder and demonstrated the suitability of the adopted solution in terms of temperature distribution in the parts of the machine, as well as the correct concept of the rcial program