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  • 101. Smirnova, Tatiana
    et al.
    Åkesson, Henrik
    Håkansson, Lars
    Dynamic Modeling of a Boring Bar Using Theoretical and Experimental Engineering Methods Part 1: Distributed-Parameter System Modeling and Experimental Modal Analysis2009Ingår i: International Journal of Acoustics and Vibration, ISSN 1027-5851, Vol. 14, nr 3, s. 124-133Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Boring bar vibration is a common problem during internal turning operations and is a major problem for the manufacturing industry. High levels of boring bar vibration generally occur at frequencies related to the first two fundamental bending modes of a boring bar. This is the first of two companion papers that summarize the theoretical and experimental work carried out concerning modeling of dynamic properties of boring bars. This paper introduces the Timoshenko beam theory for the modeling of clamped boring bars. Also, the traditional Euler-Bernoulli beam theory is applied. These continuous system methods have been utilized to produce fixed-free beam models of the clamped boring bar. In order to improve accuracy of dynamic models of clamped boring bars, the modeling of the boring bar clamping is addressed by means of multi-span beam models with pinned boundary conditions. The derived boring bar models have also been compared with results obtained by means of experimental modal analysis, conducted on the actual boring bar clamped in a lathe. The multi-span beam boring bar models display higher correlation with experimental modal analysis results as compared to fixed-free beam models. For the fixed-free beams the Timoshenko model results in the highest correlation with the experimental results. On the other hand, the interval in frequency and the orientation of the two fundamental modes demonstrate differences, particularly between the continuous system models and the experimental results.

  • 102. Smirnova, Tatiana
    et al.
    Åkesson, Henrik
    Håkansson, Lars
    Dynamic Modeling of a Boring Bar Using Theoretical and Experimental Engineering Methods Part 2: Finite Element Modeling and Sensitivity Analysis2009Ingår i: International Journal of Acoustics and Vibration, ISSN 1027-5851, Vol. 14, nr 3, s. 134-142Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This is the second of two companion papers that summarize the theoretical and experimental work carried out concerning modeling of dynamic properties of boring bars. This paper introduces the finite element method for the modeling of clamped boring bars. The “3-D” FE models of the system boring bar – clamping house as well as the “1-D” FE models of the clamped boring bar were derived. In particular, the modeling of the boring bar clamping is addressed. Dynamic properties predicted based on the developed FE models of the clamped boring bar were compared with the ones estimated by means of experimental modal analysis conducted on the actual boring bar clamped in the lathe. The “3-D” FE models display substantially higher correlation with the experimental modal analysis results compared to the “1-D” FE models. A “3-D” FE model of the boring bar – clamping house manages to model the distance in frequency and the orientation of the two fundamental modes to a large extent. The importance of the modeling of the boring bar boundary conditions for the accuracy of dynamic models of boring bars is demonstrated. The sensitivity of the natural frequency estimates produced by means of the FE and the continuous system (presented in Part 1) boring bar models with respect to variations in material density and Young’s elastic modulus has been addressed.

  • 103. Smirnova, Tatiana
    et al.
    Åkesson, Henrik
    Håkansson, Lars
    Modeling of an Active Boring Bar2007Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Vibration problems occurring during internal turning operations in the manufacturing industry urge for adequate passive and/or active control techniques in order to increase the productivity of machine tools. Usually, passive solutions are based on either boring bars made partly in high Young's modulus non-ductile materials such as intered tungsten carbide or boring bars with tuned vibration absorbers adjusted to increase the dynamic stiffness in the frequency range of a certain resonance frequency of the boring bar. By utilizing an active boring bar with an embedded piezoceramic actuator and a suitable controller, the primary boring bar vibrations originating from the material deformation process may be suppressed with actuator-induced secondary "anti-" vibrations. In order to design an active boring bar, several issues have to be addressed, i.e., selecting the characteristics of the actuator, the actuator size, the position of the actuator in the boring bar, etc. This usually implies the manufacturing and testing of several prototypes of an active boring bar, and this is a time-consuming and costly procedure. Therefore, mathematical models of active boring bars incorporating the piezo-electric effect that enable the accurate prediction of their dynamic properties and responses are of great importance. This report addresses the development of a "3-D" finite element model of the system "boring bar-actuator-clamping house". The spatial dynamic properties of the active boring bar, i.e., its natural frequencies and mode shapes, as well as the transfer function between actuator voltage and boring bar acceleration are calculated based on the "3-D" FE model and compared to the corresponding experimentally obtained estimates. Two types of approximations of the Coulomb friction force, the arctangent and the bilinear models, are evaluated concerning modeling contact between the surface of the boring bar and the clamping house.

  • 104. Smirnova, Tatiana
    et al.
    Åkesson, Henrik
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Accurate FE-modeling of a Boring Bar Correlated with Experimental Modal Analysis2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    In metal cutting the vibration problem of boring bars remains to be one of the most problematic and productivity degrading. A boring bar is very flexible and easily subjected to vibrations due to its large length to diameter ratio, which generally is required to perform internal turning. The boring bar vibrations appear at its first eigenfrequncies, which correspond to the boring bar’s first bending modes that are affected by boring bar’s boundary conditions applied by the clamping and workpiece in the lathe. Therefore the investigation of spatial dynamic properties of boring bars is of great importance for the understanding of the mechanism and nature of boring bars vibrations. This paper addresses the problem of building an accurate 3-D finite element model of a boring bar with ”free-free” boundary conditions. The questions of appropriate meshing and its influence on the boring bar’s spatial dynamic properties estimates as well as modeling the affect of mass loading are discussed. The results from simulations of 3-D finite element model of the boring bar, i.e. its first eigenmodes and eigenfrequencies, are correlated with the results obtained both from experimental modal analysis and analytical calculations using an Euler-Bernoulli model.

  • 105. Smirnova, Tatiana
    et al.
    Åkesson, Henrik
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Estimation of an active boring bar´s control path FRF:s by means of its 3-D FE-model with Coulomb friction2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    In metal cutting boring bar vibrations may be attenuated using an active boring bar with an embedded piezoceramic actuator, attached error sensor and a suitable controller. In the design of active boring bars accurate modelling of control path frequency response functions (FRF), i.e. FRF between the actuator voltage and the boring bars response signal (which is commonly acceleration), are of importance, e.g. for the decision concerning the favorable position of the actuator inside the active boring bar to maximize vibration suppression. This paper addresses the influence of the Coulomb friction force on the transfer function estimates between the actuator voltage and the boring bar acceleration calculated based on the ”3-D” FE model of an active boring bar. Two types of approximations of the Coulomb friction force, the arctangent and the bilinear models, are evaluated concerning modelling the contact between the surface of the boring bar and the clamping house. Results of incorporation of the two different Coulomb friction force models into the active boring bar’s SDOF model as well as ”3-D” FE-model enabling variable contact between the boring bar, the clamping screws and the clamping house are presented in terms of control path FRF:s.

  • 106. Smirnova, Tatiana
    et al.
    Åkesson, Henrik
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Identification of Spatial Dynamic Properties of the Boring Bar by Means of Finite Element Model: Comparison with Experimental Modal Analysis and Euler-Bernoulli Model2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    In metal cutting the boring operation is known to be one of the most troublesome regarding vibration. Boring bars are frequently subjected to vibrations originated from the load applied by the workpiece material deformation process. These vibrations are easily excited due to the boring bars general geometric dimensions, i.e. large length to diameter ratio. Large overhang is usually required to perform internal boring operation and is a consequence the vibration may frequently reach extremely high levels, which result in a poor surface finish, reduced tool life and annoying noise level in the working environment. The vibration problem is directly related to the first bending modes of a boring bar. Therefore investigations of the boring bar’s spatial dynamic properties are of a great importance. The results from experimental modal analysis show that a conventional analytical approach - calculation of boring bar eigenfrequencies using an Euler-Bernoulli model - results in rough estimates. This can be explained by existing nonlinearities introduced e.g. in the areas of contact between the boring bar and the clamping bolts as well as the clamping house, which is not considered in the analytical model where the boring bar instead is assumed to be rigidly clamped. Therefore the estimation of the eigenfrequencies and eigenmodes of a boring bar based on a 3-D finite element model of the clamped boring bar incorporating contact between the bar and the bolts respective the clamping house is a more beneficial strategy. This paper addresses the estimation of the boring bar’s first eigenfrequencies and corresponding eigenmodes based on the 3-D finite element model. The results are compared with results obtained both from experimental modal analysis and an analytical Euler-Bernoulli model.

  • 107. Smirnova, Tatiana
    et al.
    Åkesson, Henrik
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    INITIAL EXPERIMENTS WITH A FINITE ELEMENT MODEL OF AN ACTIVE BORING BAR2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    One of the most troublesome sources of vibration in metal cutting is the vibration caused by internal turning operations. A boring bar is a tool holder which is used to machine deep precise cavities inside a workpiece material. In order to perform this internal turning the boring bar usually has a large length-to-diameter ratio, and thus the boring bar vibrations are easily excited by the material deformation process during metal cutting. The vibrations are related to the lower order fundamental bending modes of the boring bar. To overcome the vibration problem an active control technique can be used. In particular, by utilizing an active boring bar with an embedded piezoceramic actuator and a suitable controller, the primary boring bar vibrations originating from the material deformation process may be suppressed with secondary "anti-" vibrations. In order to produce an active boring bar several decisions should be done, i.e. the characteristics of the actuator, the position of the actuator in the boring bar, etc. This usually implies that several prototypes of an active boring bar should be produced and tested, thus the design of an active boring bar is a tedious and costly procedure. Therefore a mathematical model which would incorporate the piezo-electric effect in order to predict the dynamic properties and the response of the active boring bar are of great importance. This paper addresses the development of a "3-D" finite element model of the system "boring bar-actuator-clamping house". The spatial dynamic properties of the active boring bar, i.e. its natural frequencies and mode shapes, as well as the transfer function between the voltage applied to the actuator and acceleration of boring bar are calculated based on the "3-D" FE model and compared to experimentally obtained estimates.

  • 108. Smirnova, Tatiana
    et al.
    Åkesson, Henrik
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Investigation Concerning Actuator Position in an Active Boring Bar Regarding it´s Performance by Means of "3-D" Finite Element Models2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    Active boring bars may be used for active vibration suppression during internal turning operation in metal cutting. This technique is based on a feedback control scheme of the boring bar vibrations measured by an attached sensor (usually accelerometer) where secondary "anti"- vibrations are applied by means of an embedded piezoelectric actuator. In order to design an active boring bar, several issues have to be addressed, i.e. selecting the characteristics of the actuator, the actuator size, the position of the actuator in the boring bar, etc. A mathematical model of the active boring bar incorporating the piezoelectric effect, e.g. a "3-D" finite element, may simplify designing process. In this paper several "3-D" finite element models of the system "boring bar - actuator - clamping house" are developed for a set of actuator positions. The favorable actuator position is basically selected as the one resulting in the greatest "stiffness" of the active boring bar at the frequency corresponding to the first boring bar fundamental bending mode.

  • 109. Smirnova, Tatiana
    et al.
    Åkesson, Henrik
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Investigation Concerning Dynamic Properties of an Active Boring Bar Regarding its Perfomance by Means of ”1-D” Finite Element Models2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Active boring bars may be used for active vibration suppression during internal turning operations in metal cutting. This technique is typically based on a feedback control scheme of the boring bar vibrations measured by an attached sensor (usually accelerometer) where secondary ”anti”-vibrations are induced by means of an piezoelectric actuator embedded into a cavity located in the boring bar’s longitudinal direction below its central line. Design procedure of an active boring bar requires the selection of the characteristics of the actuator, the actuator size, the position of the actuator in the boring bar, etc. A ”3-D” finite element model of the active boring bar incorporating the piezoelectric effect was proposed previously to simplify the design process. The set of actuator positions used to decide the favorable actuator position was limited due to time-consuming transient response calculations of the ”3-D” finite element model of an active boring bar. In the present paper a larger set of ”1-D” finite element models of a boring bar (which model the position of the cavity for the actuator but do not incorporate piezoelectric effect) was used to predict dynamic properties of the active boring bar. Based on these results a small set of favorable actuator positions is selected for implementation in ”3-D” finite element models of active boring bars.

  • 110. Smirnova, Tatiana
    et al.
    Åkesson, Henrik
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Investigation of Boring Bar Mode Shape Rotation by Experimental Modal Analysis in Correlation with Finite Element Modeling2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    Productivity degrading vibration problems are traditional in metal cutting, in particular in internal turning, when the boring bar is long and slender. The high levels of vibrations arise at the boring bar’s natural frequencies corresponding to its fundamental bending modes. The vibrations are dominating at the boring bar’s eigenfrequency in the cutting speed direction, since the cutting force has the largest component in this direction. The negative effects of vibrations, e.g. poor surface finish, reduced tool life, high sound pressure levels in the working environment etc., can be eliminated for instance by using passive tuned damper or active control. The level of success implementing any of these methods is dependent on the knowledge of the dynamic properties of tooling structure - the interface between the cutting tool or insert and the machine tool - involved. Results from experimental modal analysis on the boring bar clamped in a lathe reveal a rotation of the mode shapes with respect to the cutting speed and cutting depth direction. The paper addresses boring bar mode shape rotation phenomenon and discusses its possible sources based on results obtained from experimental modal analysis of two systems: boring bar with original boundary conditions and boring bar with linearized boundary conditions in correlation with results obtained from corresponding 3-D finite element models.

  • 111. Smirnova, Tatiana
    et al.
    Åkesson, Henrik
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Simulation of Active Suppression of Boring Bar Vibrations by Means of Boring Bar’s ”1-D” Finite Element Model2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    In metal cutting active control is one method that may be used to attenuate vibration of a boring bar during an internal turning operation. It is based on the utilization of an active boring bar with an embedded piezoceramic actuator and a suitable controller, etc. In this case, the primary boring bar vibrations originating from the material deformation process may be suppressed with secondary "anti-" vibrations induced by the actuator. The design of an active boring bar is usually a tedious and costly procedure, which involves decision making concerning the selection of the actuator characteristics, its position inside the boring bar as well as production and testing of several active boring bar prototypes. Therefore accurate mathematical modeling of the active control system; including the active boring and controller, etc. is of importance. In this paper a simple “1-D” finite element model of a boring bar is utilized to simulate its dynamic response and as controller an adaptive digital controller realized by the feedback filtered-x lms algorithm is used. Control system simulations are presented for the case of broadband excitation.

  • 112. Sturesson, Per-Olof
    et al.
    Håkansson, Lars
    Claesson, Ingvar
    Identification of the Statistical Properties of the Cutting Tool Vibration in a Continuous Turning Operation: Correlation to Structural Properties1997Ingår i: Mechanical Systems & Signal Processing, ISSN 0888-3270 , Vol. 11, nr 3, s. 459-499Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The cutting force dynamics in alloyed steel, stainless steel and cast iron have been investigated, although a direct measurement of the cutting forces could not be carried out. Usually, the response of the tool holder shank is measured by strain gauges and will be dependent on the stochastic character of the applied load and the structural dynamic properties of the tool holder. The characterisation of the dynamic response of the tool holder shank relies here on a stochastic approach while the structural dynamic properties were evaluated by a normal mode analysis. The results from both the analysis and the experiments correlate well.

  • 113. Sällberg, Benny
    et al.
    Håkansson, Lars
    Claesson, Ingvar
    Active Noise Control for Hearing Protection using a Lowpower Fixed Point Digital Signal Processor2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    This contribution presents a fixed point implementation for acoustical active noise control in hearing defenders. The well known filtered-x least mean squares structure is conformed to fixed point arithmetic and evaluated in real time. The measured performance of the implementation is 20dB to 30dB attenuation of broad band noise and ca 60dB for sinusoidal interference. The implementation uses a low power fixed point digital signal processor and is well suited for industry application.

  • 114. Tawfik, Mohamed
    et al.
    Sancristobal, Elio
    Sergio, Martin
    Gil, Rosario
    Diaz, Gabriel
    Colmenar, Antonio
    Nilsson, Kristian
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Zackrisson, Johan
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Gustafsson, Ingvar
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Virtual Instrument Systems in Reality (VISIR) for Remote Wiring and Measurement of Electronic Circuits on Breadboard2013Ingår i: IEEE Transactions on Learning Technologies, ISSN 1939-1382, E-ISSN 1939-1382, Vol. 6, nr 1, s. 60-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports on a state-of-the-art remote laboratory project called Virtual Instrument Systems in Reality (VISIR). VISIR allows wiring and measuring of electronic circuits remotely on a virtual workbench that replicates physical circuit breadboards. The wiring mechanism is developed by means of a relay switching matrix connected to a PCI eXtensions for Instrumentation (PXI) instrumentation platform. The entire equipment is controlled by LabVIEW server software, in addition to a measurement server software that protects the equipment from hazard connections by verifying input circuit designs, sent by students, before being executed. This paper addresses other approaches such as remote labs based on Data Acquisition Cards (DAQs), NetLab, and RemotElectLab, comparing them with VISIR in order to emphasize its singularity. Topics discussed are as follows: the technical description, software, operation cycle, features, and provided services. In addition, the feedback received by students at several universities and the encountered drawbacks along with the proposed solutions are highlighted. The paper finally addresses the ongoing and future challenges within the VISIR community including its integration with Learning Management Systems (LMSs) and iLab Shared Architecture (ISA), its new hardware version release that is based on LAN eXtensions for Instrumentation (LXI), and its new open platform version that supports federated access.

  • 115. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Håkansson, Lars
    An Approach to Suppress RFI in Ultrawideband Low Frequency SAR2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper proposes an approach for the Radio Frequency Interference (RFI) suppression in ultrawideband (UWB) low frequency Synthetic Aperture Radar (SAR). The basis of the approach is an Adaptive Line Enhancer (ALE) controlled by the Normalized Least Mean Square (NLMS) algorithm. The proposal is tested successfully on the simulated CARABAS-II data.

  • 116. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Håkansson, Lars
    Gustavsson, Anders
    Ulander, Lars
    RFI Suppression in Ultrawideband SAR Using an Adaptive Line Enhancer2010Ingår i: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 7, nr 4, s. 694-698Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this letter, we propose an approach to suppress radio-frequency interference (RFI) in ultrawideband (UWB) low-frequency synthetic aperture radar (SAR). According to the proposal, RFI is suppressed by using an adaptive line enhancer controlled by the normalized least mean square algorithm. The approach is tested successfully on real UWB low-frequency SAR data. In order to keep the computational burden down, possible ways to integrate the RFI suppression approach into SAR imaging algorithms are also suggested.

  • 117. Walia, M. S.
    et al.
    Karlsson, Magnus
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Chopra, G.
    Analysis Method to Study the Potentialsin Recovering the Brake Energy in Articulated Haulers2014Konferensbidrag (Refereegranskat)
  • 118. Winberg, Mathias
    et al.
    Johansson, Sven
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Active Vibration Isolation in Ships: A Pre-Analysis of Sound and Vibration Problems2005Ingår i: International Journal of Acoustics and Vibration, ISSN 1027-5851, Vol. 10, nr 4, s. 175-196Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Engine-induced sound and vibration levels in boats for professional and leisure use are in many cases unacceptably high in terms of comfort and environmental disturbance. Classical methods for passive treatment are normally less efficient due to the low frequency content and often lead to a substantial increase in weight. The requirements for lower weight which would increase the maximum speed of the boat as well as improve fuel economy have to be considered. More efficient vibration damping methods must therefore be found. With, for example, active engine mounts, it is possible to achieve a decrease in the vibrations even for cases when the hull is not very stiff. This is especially important in marine applications, since the engines are usually mounted on flexible and light structures. The project Active Vibration Isolation In Ships (AVIIS) aims at investigating the effects of using a type of Active Noise and Vibration Control system (ANVC) in this type of marine application. This article presents the analysis of the sound and vibration problems in one particular leisure boat from an ANVC point of view. A very thorough investigation is carried out, the main noise and vibration sources are established as well as the transmission paths of the noise into the boat. Answers are found from this investigation as to where the actuators should be positioned, which kind of ANVC approach that would be preferable to use and the expected interior noise reduction. This is the kind of pre-analysis that is needed for a complex structure such as found in a marine vessel for the successful implementation of ANVC. An optimized engine mount was also designed and evaluated resulting in a 10 dBA saloon sound level reduction compared to the standard engine mounts. Additionally, with the optimized engine mounts, the vibration levels at the hull were also reduced by up to 15 dB at the main harmonic components. This paper also presents a feasible way to estimate the performance of a potential active control system based on feedforward narrowband control of engine and propeller harmonics. Secondary sources inertial mass actuators are proposed and for error sensors, accelerometers or microphones or a combination of the two are used. In the low frequency range, below 300 Hz, a further reduction of engine orders and propeller BPFs in the order of 5-10 dB are predicted.

  • 119.
    Xu, Cheng
    et al.
    Uppsala univ., SWE.
    Källström, Elissabeth
    Volvo Construct Equipment, SWE.
    Risch, Tore
    Uppsala univ., SWE.
    Lindström, John
    Lulea Univ Technol., SWE.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Larsson, Jonas
    Volvo Construct Equipment, SWE.
    Scalable validation of industrial equipment using a functional DSMS2017Ingår i: Journal of Intelligent Information Systems, ISSN 0925-9902, E-ISSN 1573-7675, Vol. 48, nr 3, s. 553-577Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A stream validation system called SVALI is developed in order to continuously validate correct behavior of industrial equipment. A functional data model allows the user to define meta-data, analyses, and queries about the monitored equipment in terms of types and functions. Two different approaches to validate that sensor readings in a data stream indicate correct equipment behavior are supported: with the model-and-validate approach anomalies are detected based on a physical model, while with learn-and-validate anomalies are detected by comparing streaming data with a model of normal behavior learnt during a training period. Both models are expressed on a high level using the functional data model and query language. The experiments show that parallel stream processing enables SVALI to scale very well with respect to system throughput and response time. The paper is based on a real world application for wheel loader slippage detection at Volvo Construction Equipment implemented in SVALI. © 2016 The Author(s)

  • 120. Zackrisson, Johan
    et al.
    Gustavsson, Ingvar
    Håkansson, Lars
    An Overview of the VISIR Open Source Software Distribution 20072007Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper is intended for people who are interested in creating online laboratories. Blekinge Institute of Technology (BTH) in Sweden has started a project known as VISIR (Virtual Instrument Systems in Reality) together with National Instruments in USA and Axiom EduTech in Sweden to disseminate an online laboratory concept created at BTH using open source technologies in collaboration with other universities and organisations. The VISIR open source distribution 2007 includes software for two implemented examples, one laboratory for low frequency electronics and one for signal processing. The distribution is modular and many modules can be used for other online laboratories. The goal is an international standard, enabling teams worldwide to expand and jointly develop this powerful approach into distributed online laboratories. Each laboratory is a client/server application controlled by an administrative system. These three parts are mainly written in Adobe Flash, C++, and PHP respectively. However, the hardware control module of the equipment server is written in LabVIEW. This paper describes the organisation of the software.

  • 121. Åkesson, Henrik
    et al.
    Brandt, Anders
    Håkansson, Lars
    Lagö, Thomas L
    Claesson, Ingvar
    Operational Modal Analysis of a Boring Bar During Cutting2005Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Internal turning or boring operation is a common metal working process that is usually associated with vibration problems. Vibration problems in internal turning considerably influence important factors such as surface quality, productivity, production costs, etc. In this paper we report analysis results from an operational modal analysis of a boring bar during cutting operation. The results are compared with operating deflection shape results and traditional modal analysis results of the same boring bar. Results show that the first bending modes in the directions of cutting speed and cutting depth are active in the operating vibrations. The three analysis methods result in similar conclusions.

  • 122. Åkesson, Henrik
    et al.
    Gustavsson, Ingvar
    Håkansson, Lars
    Claesson, Ingvar
    Remote Experimental Vibration Analysis of Mechanical Structures over the Internet2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    Experimental vibration analysis is of significant importance for e.g. the automobile and aircraft industry. It provides detailed information concerning the actual dynamic properties of vibration, structures, etc. Commonly, information from experimental vibration analysis is used in the development or modification of structures, processes, etc. to obtain for instance a required dynamic behaviour. It usually involves analysis methods such as; spectrum analysis, correlation analysis, experimental modal analysis and operating deflection shapes analysis (ODS). Large experience is generally required to obtain reliable results with these methods. The best way to acquire such experience is to spend many hours in a laboratory supervised by an expert teacher. However, in engineering education the experimental resources are limited and the traditional way of conducting vibration experiments is to participate in time limited scheduled lab sessions. Internet, however, provides the opportunity for engineering students to access the practical and theoretical knowledge advancement in experimental vibration analysis that is highly attractive for the industry. Laboratory exercises in, for example, experimental vibration analysis and signal processing courses, can now be performed remotely using real equipment. Advanced vibration experiments have been conducted over the Internet at Blekinge Institute of Technology, Sweden; the experiments have been carried out using experimental hardware located in a small closed laboratory. Exercises are adapted to on-campus students as well as distance learning engineers in continuing education programs. A new possibility to directly integrate vibration experiments into lectures given by expert teachers appears and after each lecture the students can repeat and elaborate on the experiments. Thus, enabling the students to carry out the experiments within a course at home using the time they require for sufficient comprehension. In this paper the remote experimental vibration analysis laboratory and its possibilities will be presented.

  • 123. Åkesson, Henrik
    et al.
    Håkansson, Lars
    Gustavsson, Ingvar
    Zackrisson, Johan
    Claesson, Ingvar
    Lagö, Thomas L
    Vibration Analysis of Mechanical Structures over the Internet Integrated into Engineering Education2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    Experimental vibration analysis is one of the most important tools for analyzing dynamic properties of mechanical structures. The information from experimental vibration analysis is used in the development of products to obtain a required dynamic behavior, or for instance classify vibration problems in different public, industrial environments etc. In order to carry out such experiments with high quality, knowledge about different analysis methods is of great importance. Also a large experimental experience is required to obtain reliable results as in any field. In engineering education experiment using real mechanical structures and equipment is of significance for the learning process. In traditional university laboratories students conduct experiments under the supervision of an instructor. However, a trend towards decreasing investments to maintain these laboratories can be seen all over the world and instead an increase of simulations or theoretical experiments is replacing these hands on experiments due to cost. Blekinge Institute of Technology (BTH), Sweden provide the opportunity for engineering students to remotely access the practical and theoretical knowledge advancement in experimental vibration analysis that is highly attractive for the industry. Remote laboratory exercises are to day a reality at BTH and are a complement to on-campus laboratory experiments, increasing the availability of the instruments. Previously vibration experiments have been conducted over the Internet at BTH, using experimental hardware located in a small closed laboratory. A further step towards a more user-friendly interface has been developed, increasing the feeling of being in front of a real instrument instead of a virtual front panel. This paper presents a new remote vibration laboratory and how remote experimental vibration analysis has been integrated in the engineering education as a complement to ordinary lessons and experiments in traditional laboratories.

  • 124. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Claesson, Ingvar
    Håkansson, Lars
    On the Development of a Simple and Robust Active Control System for Boring Bar Vibration in Industry2007Ingår i: International Journal of Acoustics and Vibration, ISSN 1027-5851, Vol. 12, nr 4, s. 139-152Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Vibration in internal turning is a problem in the manufacturing industry. A digital adaptive controller for the active control of boring bar vibration may not be a suficient solution to the problem. The inherent delay in a digital adaptive controller delays control authority and may result in tool failure when the load applied by the workpiece on the tool changes abruptly, e.g. in the engagement phase of the cutting edge. A robust analog controller, based on a lead-lag compensator, with simple adjustable gain and phase, suitable for the industry application, has been developed. Also, the basic principle of an active boring bar with embedded actuator is addressed. The performance and robustness of the developed controller has been investigated and compared with an adaptive digital controller based on the feedback filtered-x algorithm. In addition, this paper takes into account those variations in boring bar dynamics which are likely to occur in industry; for example, when the boring bars is clamped in a lathe. Both the analog and the digital controller manage to reduce the boring bar vibration level by up to approximately 50 dB.

  • 125. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Analysis of dynamic properties of boring bars concerning different clamping conditions2009Ingår i: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 23, nr 8, s. 2629-2647Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Boring bars are frequently used in the manufacturing industry to turn deep cavities in workpieces and are usually associated with vibration problems. This paper focuses on the clamping properties’ influence on the dynamic properties of clamped boring bars. A standard clamping housing of the variety commonly used in industry today has been used. Both a standard boring bar and a modified boring bar have been considered. Two methods have been used: Euler–Bernoulli beam modeling and experimental modal analysis. It is demonstrated that the number of clamping screws, the clamping screw diameter sizes, the screw tightening torques, the order the screws are tightened has a significant influence on a clamped boring bars eigenfrequencies and its mode shapes orientation in the cutting speed—cutting depth plane. Also, the damping of the modes is influenced. The results indicate that multi-span Euler–Bernoulli beam models with pinned boundary condition or elastic boundary condition modeling the clamping are preferable as compared to a fixed-free Euler–Bernoulli beam for modeling dynamic properties of a clamped boring bar. It is also demonstrated that a standard clamping housing clamping a boring bar with clamping screws imposes non-linear dynamic boring bar behavior.

  • 126. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Claesson, Ingvar
    Analog and Digital Approaches of Attenuation Boring Bar Vibrations during Metal Cutting Operations2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    In metal cutting operations tool vibration is a frequent problem. Vibrations appear under the excitation applied by the material deformation process during the machining of a workpiece. In order to perform an internal turning or boring operation, e.g. in a pre-drilled hole in a workpiece, it is generally required that the boring bar should be long and slender; therefore it is easily subjected to vibrations. These vibrations will affect the result of machining, in particular the surface finish, and also the tool life may be reduced. As a result of tool vibration severe acoustic noise frequently occurs in the working environment. The vibration problem is to a large extent related to the boring bar low-order fundamental bending modes. In order to control boring bar vibrations in the primary cutting direction an analog and a digital feedback controllers have been used. In both approaches an active boring bar with a built-in actuator has been used. In order to measure the response of the active boring bar, accelerometers are mounted nearby the area, where the excitation force is applied due to material deformation process. This means that in either approach the boring bar vibrations are attenuated actively by the controlled secondary anti-vibrations induced by the actuator. The digital controller, based on the feedback filtered-x LMS-algorithm, manages to reduce the boring bar vibrations in the primary cutting direction by up to approximately 44 dB at the first bending resonance frequency. The analog controller, based on a flexible orthogonal gain and phase lag compensation, results in an attenuation of the boring bar vibrations in the primary cutting direction by up to approximately 40 dB at the first bending resonance frequency. Both controllers also suppress all the harmonics of the first bending resonance frequency. Vibration attenuation performances of the two controllers are compared and discussed.

  • 127. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Advantages and Drawbacks Using Different Sensors in Feedback Control in Active Boring Bar Applications2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    Several prototypes of an active boring bar for industrial applications have been produced for the reduction of cumbersome vibration problems in metal cutting processes. The active boring bar is used in lathe application to machine deep and precise holes in workpieces where long and slender boring bars are required. A vibration sensor embedded in the boring bar together with an embedded actuator is utilized in order to enable active feedback control. This paper discusses different techniques of measuring boring bar vibrations and their influence on the feedback control scheme as well as on the active control performance. Also the dynamic properties of the boring bar are considered when utilizing the different sensor techniques. The sensors that have been used are; accelerometer, strain gauges and piezo film.

  • 128. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Analog versus Digital Control of Boring Bar Vibration2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    In workshops where metal cutting is performed, the machining processes frequently introduces productivity degrading vibration problems and annoying sound, sometimes almost at unbearable levels. Besides producing disturbing noise, the vibrations affect the surface finish of the workpiece and the tool life. Two different approaches based on feedback control are investigated, both applied for the control of an active boring bar. The first approach is based on a digital adaptive feedback controller; the feedback filtered-X LMS algorithm. The second approach is based on an analog controller; a feedback controller with gain and phase orthogonally adjustable, thus flexible for the control of systems with different dynamic properties. Based on open loop frequency response function estimates, robustness and stability of both the digital and the analog feedback control system are discussed. A comparison of the two controllers concerning their boring bar vibration attenuation performance shows that the analog controller attenuates the vibration in same order of magnitude as the digital controller which is approximately by up to 40 dB.

  • 129. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Comparison between different controllers when having abrupt changes in a process2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    When metal cutting is performed, the machining processes introduce productivity degrading vibration. By applying an active control scheme, theses vibrations can be reduced significantly with the result of improved surface finish of the work piece and increased tool life. Due to the large difference of boundary conditions during the machining process, a controller fast enough to follow these changes is needed, for example from no cutting to cutting - the actual engagement of the cutting process. If the controller does not success to follow fast enough, the tool tip might break, as is the case without any active damping. Different approaches based on feedback control are investigated; all implemented using an active boring bar. The first approach is based on a digital adaptive feedback controller; the feedback filtered-X LMS algorithm. The two other controllers are analog; one is a lead controller and the other is lead-lag controller, both with gain and phase orthogonally adjustable. This paper focuses on robustness, stability and convergence of the digital and the analog feedback controllers. The analysis is based on open loop frequency response function estimates during different operating conditions.

  • 130. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Developments Steps of an Active Boring Bar for Industrial Application2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the manufacturing industry, boring bar vibration in internal turning is a frequent problem. Boring bars are often used to machine deep and precise holes in workpieces and are thus usually long and slender. The consequences of boring bar vibration are generally; reduced tool life, poor surface finish and high sound levels in the working environment. Boring bar vibration may however be attenuated using a suitable active vibration control system. Such system may for instance rely on feedback control and an active boring bar with embedded actuators. There are some steps between research results, having a controlled laboratory setup working, and applying the technology in industry, that are essential. Several prototypes of an active boring bar for industrial applications have been produced as part of this research. Different development phases and some challenges along the road to a successful product are discussed. Also, an active boring bar vibration control system in industry is presented and what challenges such a development may include.

  • 131. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Dynamic Properties of Tooling Structure: Hydraulic Clamping versus Standard Screw Clamping in a Lathe Application2008Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    During turning, the metal deformation process excites the tooling structure and may result in high and degrading tool vibration levels. In internal turning the boring bar is generally the weakest link of the tooling structure. The boundary conditions imposed on the boring bar by the clamping housing influence the dynamic properties of a clamped boring bar. The dynamic properties of a clamped boring bar have been investigated for two different clamping housings; one that clamps the boring bar by means of hydraulic pressure and one that clamps the boring bar by means of clamping screws. Both experimental and analytical methods have been utilized in the investigation.

  • 132. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Estimation and Simulation of the Nonlinear Dynamic Properties of a Boring Bar2011Ingår i: International Journal of Acoustics and Vibration, ISSN 1027-5851, Vol. 16, nr 1, s. 35-43Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, an initial investigation of the nonlinear dynamic properties of clamped boring bars is carried out. Two nonlinear, single-degree-of-freedom models with different softening spring nonlinearities are introduced for modeling the nonlinear dynamic behavior of the fundamental bending mode in the cutting speed direction of a boring bar. Also, two different methods for the simulation of nonlinear models are used. The dynamic behavior in terms of frequency response function estimates for the nonlinear models and the experimental modal analysis of the clamped boring bar is compared. Similar resonance frequency shift behavior for varying excitation force levels is observed for both the nonlinear models and the actual boring bar.

  • 133. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    INVESTIGATION OF THE DYNAMIC PROPERTIES OF A BORING BAR CONCERNING DIFFERENT BOUNDARY CONDITIONS2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    The boring bar is one of the most widely used types of tool holder in metal cutting operations. The turning process subjects the tool to vibration, and cutting in deep workpiece cavities is likely to result in high vibration levels. The consequences of such vibration levels are generally; reduced tool life, poor surface finishing and disturbing sound. Internal turning frequently requires a long and slender boring bar in order to machine inside a cavity, and the vibrations generally become highly correlated with the fundamental bending mode of the boring bar. Different methods can be applied to reduce the vibrations, the implementation of the most efficient and stable methods require in depth knowledge concerning the dynamic properties of the tooling system. Furthermore, the interface between the boring bar and the clamping house has a significant influence on the dynamic properties of the clamped boring bar. In this paper different cases of boundary condition of the boring bar are presented partly analytically but also experimentally. This paper focuses on dynamic properties of a boring bar that arise due to different clamping conditions of the boring bar introduced by a clamping house commonly used in the manufacturing industry.

  • 134. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Investigation of the Dynamic Properties of a Passive Damped Boring Bar2008Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Vibration problem during metal cutting is a degrading reality in the manufacturing industry and have a negative impact on the productivity which increases the over all production costs. Sometimes it’s also impossible to achieve the required tolerances. Different methods can be applied to reduce the vibrations, for example by using passively tuned damper or active control. This paper examines the dynamic properties of a boring bar with passive tuned damper, aiming on enhanced vibration con-trol combining passive control and active control. By combining these two methods it is likely that the performance of the passive tuned damper will be enhanced in the sense of wider working range with respect to cutting parameters and materials of workpieces. However, implementation of effi-cient and stable methods requires in-depth knowledge concerning the dynamic properties of the tooling system. The examination of the passive boring bar covers a wide range of cutting parame-ters and the main classes of workpiece materials. This is the first step in the development of a bor-ing bar involving two technologies complementing each other, that is, passive tuned damper and active control which is an already patented technology.

  • 135. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Claesson, Ingvar
    Lagö, Thomas L
    Vibration in Turning and the Active Control of Tool Vibration2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    A frequent problem in the manufacturing industry today is the vibrations or chatter induced in machine tools during machining. Chatter in machine tools affect the result of machining, particularly the surface finish. Furthermore, tool life is correlated with the degree of vibration and acoustic noise introduced. The material deformation process during turning induces a broadband excitation of the machine tool and chatter or tool vibration is usually related to a low-order bending mode of, for example, the tool holder shank in external turning, the boring bar in internal turning. Frequently, the tool holder responses during continuous unstable machining have non-linear properties and exhibit advanced stochastic behaviour. Generally, the tooling structure - the interface between the cutting tool or insert and the machine tool - is the weakest link in a machining system. Active control of tool vibration, however, enables a flexible solution to selectively increase the dynamic stiffness of the tooling structure at the actual frequency of the dominating bending modes. Based on adequate controllers, tool holder shanks and boring bars with embedded actuators and vibration sensors tool vibration in turning may be reduced significantly.

  • 136. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Claesson, Ingvar
    Sigfridsson, Andreas
    Svensson, Tobias
    Lagö, Thomas L
    A First Prototype of an Active Boring Bar Tested in Industry2006Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Metal cutting is a common process in the manufacturing industry. Vibration problem during metal cutting is a reality for these manufactures. The vibration level depends on many different parameters such as material type, dimensions of the workpiece and boring bar, cutting data and operation mode. Internal cutting is one of the most troublesome operation modes, without any continuous monitoring and control from an operator grave vibration levels quickly arises. From the industry point of view this is an expense in the production line. The reduced tool life and the coarse surface finishing caused by the large vibration will force the operator to stop the cutting process, either to change tool when it is broken or change cutting data like decreasing the cutting depth. Any interference like this increases the working time for each component tremendous. These problems have been located and examined in an industry producing and renovating components using a lathe. One lathe was chosen for further investigation by experimental modal analysis and analysis during operational mode. The examination was done in an environment with machining processes in full operation mode and also during non-working ours. After analyzing the problem different solution where scrutinized and a first prototype where constructed. The solution to the problem is an active boring bar. This paper will present the procedure from analyzing a problem in industry to the test of the first prototype of the solution.

  • 137. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Claesson, Ingvar
    Sigfridsson, Andreas
    Svensson, Tobias
    Lagö, Thomas L
    Active Boring Bar Prototype Tested in Industry2006Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Metal cutting processes are common in the manufacturing industry. Vibration problems during metal cutting are a degrading reality in the manufacturing industry and have a negative impact on the productivity and increase’s the production costs. The vibration level depends on many different parameters such as material type, dimensions of the workpiece, tool, tooling structure, machine structure, the cutting data and operation mode. Internal turning is one of the most troublesome operation modes concerning vibration. It generally requires that extra care must be taken with pro-duction planning and in the preparations for the machining of a workpiece. Frequently, continuous monitoring and control by a skilled operator is required to avoid grave degrading vibration levels. The reduced tool life and the coarse surface finishing generally caused by large vibration levels will e.g. force the operator to stop the cutting process, either to change tool when it is broken or change cutting data like decreasing the cutting depth. Any interference like this increases the production time and cost for each component tremendously. In an industry producing and renovating compo-nents using different machine tools, a particular lathe used for internal turning of certain details with extensive vibration problem was chosen for further investigation by experimental modal analysis and vibration analysis during operation. The examination was done in an environment with ma-chine tools in full operation and also during non-working ours. After analyzing the problem different solutions for the reduction of the vibration problem was investigated and subsequently a first proto-type was constructed. The solution to the problem is active control of the tool vibration using an active boring bar. This paper will present the procedure from analyzing a problem in industry to the test of the first prototype of the solution.

  • 138. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Håkansson, Lars
    Lagö, Thomas L
    Claesson, Ingvar
    Investigation of the Dynamic Properties of a Milling Tool Holder2009Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Vibration problems during metal cutting occur frequently in the manufacturing industry. The vibration level depends on many different parameters such as the material type, the dimensions of the workpiece, the rigidity of tooling structure, the cutting data, and the operation mode. In milling, the cutting process subjects the tool to vibrations, and having a milling tool holder with a long overhang will most likely result in high vibration levels. As a consequence of these vibrations, the tool life is reduced, the surface finishing becomes poor, and disturbing sound appears. In this report, an investigation of the dynamic properties of a milling tool holder with moderate overhang has been carried out by means of experimental modal analysis and vibration analysis during the operating mode. Both the angular vibrations of the rotating tool and the vibrations of the machine tool structure were examined during milling. Also, vibration of the workpiece and the milling machine was examined during cutting. This re- port focuses on identifying the source/sources of the dominant milling vibration components and on determining which of these vibrations that are related to the structural dynamic properties of the milling tool holder.

  • 139. Åkesson, Henrik
    et al.
    Smirnova, Tatiana
    Lagö, Thomas L
    Håkansson, Lars
    Analysis of Dynamic Properties of Boring Bars Concerning Different Clamping Conditions2007Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The boring bar is one of the most widely used type of tool holders in metal cutting operations. The turning process subjects the tool to vibrations, and cutting in deep workpiece cavities is likely to result in high vibration levels. The consequences of such vibration levels generally results in: reduced tool life, poor surface finishing and disturbing sound. Internal turning frequently requires a long and slender boring bar in order to machine inside a cavity, and the vibrations generally become highly correlated with one of the fundamental bending modes of the boring bar. Different methods can be applied to reduce the vibrations, the implementation of the most efficient and stable methods require in depth knowledge concerning the dynamic properties of the tooling system. Furthermore, the interface between the boring bar and the clamping house has a significant influence on the dynamic properties of the clamped boring bar. This report focuses on the dynamic properties of a boring bar that arise under different clamping conditions of the boring bar and are introduced by a clamping house (commonly used in the manufacturing industry). The dynamic properties of a boring bar (for different cases of boundary condition of the boring bar) are presented partly analytically but also experimentally.

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