| 1. |
- Gustavsson, Ingvar, et al.
(författare)
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A Flexible Remote Electronics Laboratory
- 2005
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Konferensbidrag (refereegranskat)abstract
- The Internet provides new possibilities for universities and other teaching organizations to share laboratories equipped with expensive instruments. A remotely operated electronics laboratory has been set up by Blekinge Institute of Technology in Sweden. The laboratory is a client/server application and the Internet is used as the communication infrastructure. In the new version presented in this paper security problems are solved and an authentic appearance of instruments and components are provided. Most remote electronics laboratories elsewhere offer fixed experiments but in this one, students can simultaneously assemble circuits and conduct experiments much like they do in a traditional university laboratory. The laboratory is always open and can be used by registered students and guest users around the world.
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| 2. |
- Gustavsson, Ingvar, et al.
(författare)
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A Remote Electronics Laboratory for Physical Experiments using Virtual Breadboards
- 2005
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Konferensbidrag (refereegranskat)abstract
- In traditional university laboratories students conduct experiments under the supervision of an instructor. A remotely-operated laboratory for undergraduate education in electrical engineering which emulates a traditional laboratory has been set up by Blekinge Institute of Technology (hereafter referred to as BTH), Ronneby, Sweden. The laboratory is a client/server application and the Internet is used as the communication infrastructure. Most remote laboratories elsewhere are used for fixed experiments but in the BTH laboratory students around the world can assemble circuits simultaneously from electronic components in much the same way as they do in a traditional laboratory. The teacher or a member of the laboratory staff mounts the components to be used in the lab sessions in a circuit assembly robot in the experiment server in Ronneby. Students use the mouse to connect some of the corresponding virtual components on a virtual breadboard displayed on the client PC. Students thus control the robot by means of the wiring on the virtual breadboard. Virtual instrument front panels are used to control and read the instruments by means of remote control. To avoid potentially serious student mistakes e.g. overloading a component the teacher can preset limits to the source voltages which are accessible to students. The teacher can also restrict student circuits by, for example, dictating minimum impedance in loops created with aid of the components provided. The number of nodes provided on the virtual breadboard is adequate for experiments in undergraduate education. The laboratory is always open and can be used by registered students and guest users alike. The time-sharing scheme used allows simultaneous access for up to 8 client PCs. A 56 kbit/s modem and MS Internet Explorer are all that are required. The client software can be downloaded from the laboratory web site at http://distanslabserver.its.bth.se/. This paper discusses the remotely operated laboratory at BTH; it focuses on the virtual breadboard.
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| 3. |
- Gustavsson, Ingvar, et al.
(författare)
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A Remote Laboratory providing Teacher-defined Sessions
- 2004
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An experiment server emulating a traditional university laboratory for courses in Circuit Analysis and Electronics has been set up at Blekinge Institute of Technology (BTH) in Ronneby, Sweden. Students in different places around the globe can participate in lab sessions allowing up to eight client PCs to be connected to the server via the Internet simultaneously or they can perform experiments alone without supervision around the clock when the laboratory is not fully occupied. Regular sessions are supervised by one instructor using MS Netmeeting or other means of communication. The laboratory pro-vides common instruments and the user interface is in English but universities or other learning organizations engaging the laboratory for their courses can use lab instruction manuals and other learning material in a language of their choice. In a traditional labora-tory the students use a breadboard and components handed over by the instructor to form the circuits assigned and connect the test probes. In the remote laboratory a virtual breadboard and photographs of the components provided in each session are displayed on the client PC screen at startup. The students use the mouse to locate each virtual component on the breadboard and do the wiring to assemble the circuits. The teacher or someone in the laboratory staff mounts the corresponding real components in sockets in a switching matrix in Ronneby controlled by the virtual breadboard routine before the session. The instruments provided are computer-based and have virtual front panels. The time sharing scheme used to allow simultaneous access to one server imposes re-strictions on the time period allowed for each experiment but in courses in electronics the time constants involved can without any inconvenience be selected within a proper range. The number of nodes on the virtual breadboard is also limited due to the hard-ware complexity of the switching matrix but is adequate for experiments in undergradu-ate education. Apart from the fact that each student or student team is working in a vir-tual environment without face to face contact with the instructor or other students in the laboratory the only difference compared to a traditional lab session is that it is not pos-sible for a student to manipulate the components and the wires with their fingers. The laboratory is always open and can be used by everybody outside regular lab sessions. Only a 56 kbit/s modem and MS Internet Explorer are required. The client software can be downloaded from the laboratory web site. The address of the homepage of the ex-periment server is: http://distanslabserver.its.bth.se/. In this paper laboratory sessions in the remote laboratory will be compared with sessions in a traditional laboratory.
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| 4. |
- Gustavsson, Ingvar, et al.
(författare)
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An Instructional Electronics Laboratory Opened for Remote Operation and Control
- 2006
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Konferensbidrag (refereegranskat)abstract
- Blekinge Institute of Technology in Sweden has opened a local instructional laboratory for undergraduate education in electrical and electronic engineering for remote operation and control 24/7 as a complement and a supplement to traditional laboratories. It is equipped with a unique virtual interface enabling students to recognize on their own computer screen the desktop instruments and the breadboard most of them have already used in the local laboratory. The open laboratory is used in regular courses in circuit analysis for distant learning students dispersed all over Sweden and for campus students as well. The research is focused on what is perceived to be the greatest challenge, to give students laboratory experience that is as genuine as possible despite the lack of direct contact with the actual lab hardware. The goal is to produce an open international standard in cooperation with universities and other organizations around the world.
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| 5. |
- Gustavsson, Ingvar, et al.
(författare)
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Experimentera hemma med utrustningen i universitetens övningslaboratorier
- 2006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Blekinge Tekniska Högskola, BTH, har öppnat ett övningslaboratorium för ellära och elektronik för fjärrstyrning och håller på att öppna ett fjärrstyrbart signalbehandlingslaboratorium för vibrationsanalys. Ett unikt användargränssnitt gör det möjligt att från valfri plats styra och manövrera experimentutrustningen på samma sätt som i laboratorielokalerna. Allt som behövs är Internetansluten PC med standardprogramvara. Denna forskning är inriktad mot vad som upplevs som den största utmaningen dvs. att ge studenterna en så genuin upplevelse som möjligt oaktat bristen på direkt kontakt med den fysikiska experimentutrustningen. BTH bjuder in andra lärosäten både nationellt och internationellt att delta i pedagogisk utvärdering av detta komplement till att experimentera i laboratoriesal och att delta i vidareutvecklingen mot en internationell standard.
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| 6. |
- Gustavsson, Ingvar, et al.
(författare)
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Remote Operation and Control of Traditional Laboratory Equipment
- 2006
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Ingår i: International Journal of Online Engineering. - 1868-1646 .- 1861-2121. ; 2:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Physical experiments are indispensable for developing skills to deal with physical processes and instrumentation. The Internet provides new possibilities for universities and other teaching organizations to share laboratories and increase the number of lab sessions without incurring any increase in cost. Blekinge Institute of Technology in Sweden has opened a traditional electronics laboratory for remote operation and control 24/7; it is the first of its kind. The laboratory is equipped with a unique virtual interface enabling students to recognize on their own computer screen the desktop instruments and the breadboard they have already used in the local laboratory. The research is focused on what is perceived to be the greatest challenge, i.e. to give the student laboratory experience that is as genuine as possible despite the lack of direct contact with the actual lab hardware at the same time as it allows the teacher to use existing equipment and teaching material. The goal is to produce an open international standard.
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| 7. |
- Lagö, Thomas L, et al.
(författare)
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Classification of metal cutting vibrations, is it all chatter?
- 2008
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Chatter vibrations are causing large monetary losses daily in industry. New materials have increased the challenges with harmful vibration levels. Since the vibrations, when observed as a final result, are chaotic and the vibration process nonlinear, it is a challenging task to deal with it. It is also a common “understanding” in the cutting industry that chatter is RPM (the rotational speed) dependent, since the behaviour changes with RPM. Many attempts have been done over many years to mitigate and understand the vibrations. In our vast research on these topics, we have found that it is rewarding to classify the vibrations into categories, enabling a better understanding of its underlaying physics and “source of vibrations,” and thus also the formulation of a possible remedy. An analysis approach has been developed where vibrations are analyzed and categorized and a GO/NOGO indicator is telling if the machine has the “right type of vibrations.” The work includes a unique solution to inhibit the chatter process and allowing metal cutting without harmful vibrations, the Acticut™ Smart Cutting product line. This article will discuss how such machine testing can be performed and what solutions are at hand, thus saving important money for the companies and also increases quality.
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| 8. |
- Smirnova, Tatiana, et al.
(författare)
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Accurate FE-modeling of a Boring Bar Correlated with Experimental Modal Analysis
- 2007
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 9. |
- Smirnova, Tatiana, et al.
(författare)
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Dynamic Modeling of a Boring Bar Using Theoretical and Experimental Engineering Methods Part 1 : Distributed-Parameter System Modeling and Experimental Modal Analysis
- 2009
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Ingår i: International Journal of Acoustics and Vibration. - : International Institute of Acoustics and Vibration. - 1027-5851 .- 2415-1408. ; 14:3, s. 124-133
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Smirnova, Tatiana, et al.
(författare)
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Dynamic Modeling of a Boring Bar Using Theoretical and Experimental Engineering Methods Part 2 : Finite Element Modeling and Sensitivity Analysis
- 2009
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Ingår i: International Journal of Acoustics and Vibration. - : International Institute of Acoustics and Vibration. - 1027-5851 .- 2415-1408. ; 14:3, s. 134-142
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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