| 1. |
- Amann, Daniel, 1967-, et al.
(författare)
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Affordability aspects in the concept generation of defence systems
- 2017
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Ingår i: Proceedings of 18th International CINet Conference. - Twente : Continuous Innovation Network. - 9789077360200 ; , s. 26-38
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Cost escalation for fighter aircraft is arguably not sustainable. Pushing frontiers oftechnology by incremental improvements of traditional platforms has led to anexponential increase in cost. This paper addresses the process of concept generationwith the purpose to explore how affordability is managed in that process, in order toidentify possible measures to improve the likelihood of generating affordableconcepts. This is done by studying two cases of concept generation of future combatair systems. The concepts generated in these two cases are however not curbing thecost escalation and are, with only one notable exception, based on incrementalinnovation. Nevertheless, the empirical observations offer leads to potentially fostera more innovative and cost conscious concept generation process, indicatingavenues for future research.
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| 2. |
- Amann, Daniel, et al.
(författare)
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Inducing Affordability?: Observations From An Experimental Study Of Concept Generation
- 2021
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Ingår i: Proceedings of the 22th CINet conference, September 12 – 14, Gothenburg, Sweden. - Enschede. - 9789077360248
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Konferensbidrag (refereegranskat)abstract
- Early preliminary concepts are claimed to have a profound impact on the final product. Since these concepts often are based on intuitive judgements, it is important that these judgements are appropriate for the desired outcome. Intuition is derived from what one brings to mind, and consequently, the access to information is important for making relevant judgements. Therefore, when a departure from a present path of development is sought for, access to new information is likely to be required. Results from an experimental study, addressing affordability and concept generation, indicated that individuals were influenced, by the provision of selective information, to make more cost considerations and even to change approach when generating new concepts. It was further recognized that weak abilities to estimate costs in a lifecycle and capability perspective likely hampered low-cost ambitions. The findings from this study are suggested to contribute to theory on product development, and to support affordability when new products are developed.
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| 3. |
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| 4. |
- Andreas, Molnar, et al.
(författare)
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Isbrytning med svävarfarkoster
- 1979
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Consumer report ("avnämarrapport" in Swedish) for a research foundation (Styrelse för Teknisk Utveckling STU Stockholm eller Transportforskningsdelegationen TDF Stockholm). A comment: As was the praxis during this (early) period of time at Chalmers University of Technology, as well as probably at some other universities. This means that frequent and vast academic publication by means of e.g. conference papers and refereed contributions to scientific journals was almost unheard of. At least so for some of the applied science disciplines (today are the situation indeed very different) (i.e. earlier was the publication in many respects focused on trying to satisfy the executive administrator the research foundation in question).
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| 5. |
- Angenendt, Knut, 1982, et al.
(författare)
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Ionic liquid structures from large DFT calculations using mindless configurations
- 2010
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:48, s. 20577-20582
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Tidskriftsartikel (refereegranskat)abstract
- Three different popular imidazolium based ionic liquids (ILs); EMI-BF4, EMI-PF6, and EMI-TFSI, have been modeled by DFT calculations (B3LYP/6-311+G*) using large, up to 130 atom cluster models, for a better understanding of the structure and ion ion interactions in these ILs and ILs in general. Particular emphasis has been put on the role of appropriate starting structures and how the present large models differ from the ion-pair models of ILs generally used. The system size normalized ion ion interaction energies are shown to converge rapidly, and conformational equilibria and higher order properties like IR spectra are shown to be valuable as quality criteria. The explicit inclusion of an IL environment by the large cluster approach is also compared to using an implicit, continuum, strategy via SCRF C-PCM calculations.
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| 6. |
- Bengtsson, Lars, 1963
(författare)
-
Avancerad Elektrisk Mätteknik
- 1996
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Boken är avsedd för fortsättnigskurser i elektrisk mätteknik på högskolenivå. Den lämpar sig också väl som kompletteringslitteratur för kurser i signalbehandling. Innehållet är framför allt koncentrerat till analog och digital frekvensanalys, brusreducerande mätmetoder och AD/DA-omvandlingsmetoder. Ett kapitel tar upp signalbehandling och sambanden mellan analys i tid och rum. Fouriertransformen och faltningsintegralen gås igenom i detalj. Boken avslutas dels med ett kapitel om snabba förlopp i transmissionsledningar, dels med ett kapitel om GPIB-bussen. I appendix finns även en beskrivning av RS-232-kommunikation.
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| 7. |
- Bengtsson, Lars, 1963
(författare)
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Electrical Measurement Systems and Methods
- 2014
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This book treats a wide range of aspects on electrical measurement systems and the methods used to acquire data from electronic systems. That includes sensors and sensor design, amplifiers such as differential and charge amplifiers, ADCs and DACs, digital oscilloscopes, cable theory and probes, noise and noise coupling, common and normal mode signals. This first part (chapters 1-8) doesn’t require any advanced mathematics and is aimed towards undergraduates. The second part (chapters 9-17) is on an advanced level (master level) and treats transform theory (Fourier, Laplace, z) and how to handle signals in frequency space. We cover the sampling theorem (Nyquist), resolution bandwidth, frequency spectrum distortions like aliasing and leakage and how to apply windows in a frequency spectrum. We also cover systems and signal processing in time-space, including convolution and correlation, filter theory and filter design (both analog and digital). The last chapters concern the statistical aspects on measurement systems and signals, like point and interval estimations, curve fitting and uncertainty estimations according to the GUM method.
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| 8. |
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| 9. |
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| 10. |
- Capaci, Francesca, et al.
(författare)
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Simulating and Analyzing Experiments in the Tennessee Eastman Process Simulator
- 2015
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Ingår i: ENBIS-15.
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Konferensbidrag (refereegranskat)abstract
- In many of today’s continuous processes, the data collection is usually performed automatically yielding exorbitant amount of data on various quality characteristics and inputs to the system. Moreover, such data are usually collected at high frequency introducing significant serial dependence in time. This violates the independent data assumption of many industrial statistics methods used in process improvement studies. These studies often involve controlled experiments to unearth the causal relationships to be used for robustness and optimization purposes.However real production processes are not suitable for studying new experimental methodologies, partly because unknown disturbances/experimental settings may lead to erroneous conclusions. Moreover large scale experimentation in production processes is frowned upon due to consequent disturbances and production delays. Hence realistic simulation of such processes offers an excellent opportunity for experimentation and methodological development.One commonly used process simulator is the Tennessee Eastman (TE) challenge chemical process simulator (Downs & Vogel, 1993)[1]. The process produces two products from four reactants, containing 41 measured variables and 12 manipulated variables. In addition to the process description, the problem statement defines process constraints, 20 types of process disturbances, and six operating modes corresponding to different production rates and mass ratios in the product stream.The purpose of this paper is to illustrate the use of the TE process with an appropriate feedback control as a test-bed for the methodological developments of new experimental design and analysis techniques.The paper illustrates how two-level experimental designs can be used to identify how the input factors affect the outputs in a chemical process.Simulations using Matlab/Simulink software are used to study the impact of e.g. process disturbances, closed loop control and autocorrelated data on different experimental arrangements.The experiments are analysed using a time series analysis approach to identify input-output relationships in a process operating in closed-loop with multivariate responses. The dynamics of the process are explored and the necessary run lengths for stable effect estimates are discussed.
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| 11. |
- Carini, Giovanni, et al.
(författare)
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Hypersonic attenuation in cesium borate glasses: Relaxation and anharmonicity
- 2009
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Ingår i: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - : Elsevier BV. - 0921-5093. ; 521-22, s. 247-250
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Konferensbidrag (refereegranskat)abstract
- The internal friction and the sound velocity in a cesium borate glass (Cs(2)O)(0.14)(B(2)O(3))(0.86) were measured at ultrasonic and hypersonic frequencies by Brillouin scattering measurements over the temperature range between 15 and 300 K. The analysis of the experimental results show that, in addition to thermally activated local motions of structural defects, the vibrational anharmonicity contributes substantially to the temperatures dependences of both the hypersonic loss and velocity. It has been also proved that above 150 K the vibrational anharmonicity appears to be governed by the Akhiezer mechanism of phonon viscosity.
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| 12. |
- Carlsson, Anna K, 1966, et al.
(författare)
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Rollator related pedestrian single accidents and collision events in Sweden
- 2022
-
Ingår i: Traffic Safety Research (TSR). - : Lund University. - 2004-3082. ; 2
-
Tidskriftsartikel (refereegranskat)abstract
- Rollators (four-wheel walkers in USA; zimmer frames in UK) are commonly used as mobility aids for the elderly and people with a variety of disabilities. Pedestrian rollator users are a sub-group of Vulnerable Road Users (VRUs), although this group is rarely recognised in traffic safety contexts. The aim of this study is to extract and analyse rollator related pedestrian accident and injury data in Sweden. The results will provide valuable insight into the risks and obstacles rollator users are exposed to in the traffic environment and may in the long term contribute to improving the mobility of this group. The current study is based on data from 2,020 accidents involving 2,305 persons extracted from the Swedish Traffic Accident Data Acquisition (STRADA) database. For consistency reasons, a subset of data (N = 745) was analysed in order to investigate the development of accidents over a period of 10 years. Thereafter, each accident in the whole data set was registered as either single or collision. The results show that the number of rollator accidents in Sweden increased by approximately 80% during 2007–2016. Females dominate the injury statistics of single accidents, collisions, as well as fatal outcome, which may be due to exposure and/or differences in physical characteristics. Single accidents are much more common than collisions (n=1,668 and n=352, respectively) and the injury consequences are at least as serious. Data from the present study have revealed that the frequency of minor injuries (ISS 1–3) is 4.3 times, moderate (ISS 4–8) 6.0 times and serious injuries (ISS 9–15) 8.9 times higher in single accidents than in collisions. Fatal injuries are, however, more common in collision events (33 in comparison to 8). The vast majority of single accidents (99%) was due to falls. Many of the single accidents (29%) were caused by ground level differences (typically a curb) or due to surface conditions (19%). Collisions involved cars, trucks or buses in 91% of cases, occurring predominantly in car parks (31%) and on (zebra) crossings (30%). In 54% of cases the vehicles reversed into the rollator. Abbreviated Injury Scale (AIS) 3+ injuries were dominated by head (36%) and torso (33%) injuries in collision events, and hip fractures (71%) in single accidents. The present study shows that further research into rollator user related accidents, both single accidents and collision events, is required. In order to introduce appropriate measures, future work should follow up on accident and injury developments and further improve the quality of mobility aid related accident data in general. Improved stability and design, proper training programmes, effective maintenance services, development of a supporting infrastructure would contribute to increased safety for rollator users.
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| 13. |
- Cederberg, Lennart, et al.
(författare)
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The Arctic Tern: AI + Soft Values = Save Fuel
- 2023
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Ingår i: 8th Hull Performance & Insight Conference. ; , s. 38-43
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Konferensbidrag (refereegranskat)abstract
- This paper summaries three years of technical development and research in close collaboration with several major shipping companies. Besides the technical AI-based decision support systems, the project has focused on soft values, how the support systems become efficient support for real, both ashore and onboard. It is important to create knowledge among technical-, commercial- and operation departments within the organisations on how to implement new methods. Different types of vessels operate under vastly different commercial realities that impact the performance and energy effectiveness. Technical systems must be adapted to each actor's reality to achieve a change and drive more climate-friendly transportation. The Arctic Tern shows fuel savings of 2-14%.
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| 14. |
- Chen, Zhe, et al.
(författare)
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Nano-scale characterization of white layer in broached Inconel 718
- 2017
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Ingår i: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - Amsterdam : Elsevier BV. - 0921-5093 .- 1873-4936. ; 684, s. 373-384
-
Tidskriftsartikel (refereegranskat)abstract
- The formation mechanism of white layers during broaching and their mechanical properties are not well investigated and understood to date. In the present study, multiple advanced characterization techniques with nano-scale resolution, including transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD), atom probe tomography (APT) as well as nano-indentation, have been used to systematically examine the microstructural evolution and corresponding mechanical properties of a surface white layer formed when broaching the nickel-based superalloy Inconel 718.TEM observations showed that the broached white layer consists of nano-sized grains, mostly in the range of 20–50 nm. The crystallographic texture detected by TKD further revealed that the refined microstructure is primarily caused by strong shear deformation. Co-located Al-rich and Nb-rich fine clusters have been identified by APT, which are most likely to be γ′ and γ′′ clusters in a form of co-precipitates, where the clusters showed elongated and aligned appearance associated with the severe shearing history. The microstructural characteristics and crystallography of the broached white layer suggest that it was essentially formed by adiabatic shear localization in which the dominant metallurgical process is rotational dynamic recrystallization based on mechanically-driven subgrain rotations. The grain refinement within the white layer led to an increase of the surface nano-hardness by 14% and a reduction in elastic modulus by nearly 10% compared to that of the bulk material. This is primarily due to the greatly increased volume fraction of grain boundaries, when the grain size was reduced down to the nanoscale.
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| 15. |
- Cherednichenko, Serguei, 1970, et al.
(författare)
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Online Detection of H2O and CO in the Humid Raw Gas from the Gasifier Using Terahertz Spectroscopy
- 2013
-
Ingår i: ICPS, 13 International Conference on Polygeneration Strategies, Sept.5-13, Vienna, Austria. - 9783950275483 ; , s. 51-58
-
Konferensbidrag (refereegranskat)abstract
- The integration of a gasifier with a complex multistage synthesis process, such as SNG synthesis, demands a fast monitoring of the gasifier performance. However, despite the availability of standard analyzers for determination of dry gas composition, there are still many practical difficulties remaining in the online measurement of tar and steam in the raw gas. For the detection of steam concentration, electromagnetic waves at terahertz frequencies (102-104 GHz) are promising with regard to development of a robust online measurement device for industrial application. The main reason for the high potential is the low risk for interference with the wide range of other molecules and that the transmission of electromagnetic waves at THz frequencies is rather low sensitive to deposits and particulate matter in the course of the beam compared to the conventional and well established wavelengths like infrared. In the present work, a THz gas spectrometer was designed and constructed to check the feasibility of applying this measurement technique at industrial scale. For this purpose, continuous flows of raw gas with various water and CO contents from the Chalmers gasifier as well as a flue gas with known water content from the biomass combustor were introduced to the spectrometer set-up. H2O and CO compositions in each stream were determined in an online manner. The results confirmed the possibility of applying strong rotational water lines at 448 and 380 GHz to develop reliable devices for online measurement of water vapor with excellent error interval. However, some difficulties were encountered for simultaneous detection CO concentration with water within the frequency range studied in this work (300-500 GHz).
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| 16. |
- Cherednichenko, Serguei, 1970, et al.
(författare)
-
Terahertz Gas Spectrometer
- 2014
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Ingår i: Swedish Microwave Days March 11-12, 2014, Gothenburg, Sweden.
-
Konferensbidrag (refereegranskat)abstract
- We present a 300-500GHz gas spectrometer built for and practically tested at the 2–4-MW indirect gasifier at the Chalmers Power Center. The primary goal is precise online measurements of H2O vapor and CO concentrations in the producer gas. Experimentally obtained H2O vapor concentration resolution was about 1% at the conditions of 50% VMR and 400 deg.C.
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| 17. |
- Chernikova, Dina, 1982, et al.
(författare)
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Development of the Neutron-Gamma-Neutron (NGN) approach for the fresh and spent fuel assay
- 2012
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Ingår i: Proceedings of The 53nd Annual Meeting of the Institute of Nuclear Materials Management.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In connection with current safety and complexity limitations for installations which usekeV neutrons for irradiation in the fresh and spent fuel assay, in medicine, geophysicaland detection fields, there is a long felt need of effective, light, inexpensive systems withlonger lifetimes and the possibility to ”switch off” the source during transportation andwork break. The present paper discusses an opportunity of creating a novel technique basedon using a pulsed neutron generator, hydrogen moderator and beryllium, which will enablecreation of a compact and inexpensive facility capable to satisfy all requirements. The mainidea of the proposed method consists in using photonuclear reaction in beryllium due togamma irradiation originating from (n,gamma) reaction in a hydrogen containing moderator.After the neutron pulse of a modern compact DD neutron generator in hydrogen-containingmoderator, high-energy neutrons (approximately 2.5 MeV) get slowed down mainly by elasticscattering to near thermal energies. At thermal energies, the neutrons diffuse through thematerial until they undergo thermal capture (capture is dominated by hydrogen neutronabsorbers). When a hydrogen atom captures a thermal neutron, it turns into deuteriumwith the release of a large component of 2.23 MeV gamma-rays. Beryllium is one of thefew elements in nature that undergoes a photonuclear reaction with this gamma energyrange (e.g. deuterium has a low energy 2.225 MeV photonuclear threshold). Thus, as theberyllium has lower neutron-binding energy, 1.667 MeV (photonuclear reaction threshold),a photonuclear reaction will take place with emission of neutrons with energy defined by thekinematic equation. Thus, this method allows to obtain a high quality epithermal neutronbeam without using a complex system with particle accelerator or radioisotope sources withlimited decay time. The proposed method has been studied using Monte Carlo simulations,which made it possible to define the theoretical limits of the use of the NGN approach inindustrial applications. The paper will presents the results of these investigations.
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| 18. |
- Chernikova, Dina, 1982, et al.
(författare)
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Testing a direct method for evaluating the concentration of boron in a fuel pool using scintillation detectors, and a 252Cf and an 241Am-Be source
- 2013
-
Ingår i: Proceeding of ESARDA meeting 2013.
-
Konferensbidrag (refereegranskat)abstract
- The present investigations are aimed at the development and testing of a direct non-destructive method for evaluating the concentration of boron in a fuel pool using scintillation detectors. The method uses a modified ratio between two gamma lines with energy of 480 keV and 2.23 MeV. These lines belong to the capture of a thermal neutron in boron and hydrogen, respectively. The relation between them can reveal the concentration of boron in the fuel pond.The method proposed was tested in a laboratory experiment with a 252Cf and an 241Am-Be source. EJ-309 liquid scintillation detectors were used for measurements of gamma spectra. The concentration of boron in water varied from 1550 ppm to 4200 ppm. The optimization and test studies were performed via MCNPX simulations.The results of these tests are provided in the present paper and they show that the boron content in water can be determined through using the characteristics of gamma lines with energy of 480 keV and 2.23 MeV.
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| 19. |
- Danhäll, D, et al.
(författare)
-
Naturligt grupperat arbete vid Volvo Lastvagnar – Delrapport 2
- 1989
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Consumer report for the company in question (the Volvo Truck Company) which is financed by the company and partly also by a research foundation. It is a matter of a work that in this particular case were carried out during nine years in a number of experimental workshops located outside the Chalmers University of Technology. These workshops were financed by the Volvo Automobile and Truck companies. This achievement, as the final contribution to the Swedish automotive industry after having already treated this research field/problem area for more than two decades before this particular period if time (involving several junior and senior research competencies, as well as industrial and governmental foundings). Specifically (and as stated for the previous report), this publication explains how the authors dealt with the product architecture and product variation of the automotive products disassembled, which proved to necessary to be carried out in one of the experimental workshops (several complete automobiles and one heavy truck chassis were disassembled combined with having product data accessible in form of paper print-outs as well as by appropriate computer connections to the two Volvo companies etc.). That is, by using a special sort of “design analysis by means of axonometric hand-drawn illustrations” (see a conference contribution from 1992 that also is registered and available as o PDF-document at Chalmers Public Library (CPL) (a self-developed method found out together with a junior research competency from the School of Architecture at Chalmers).
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| 20. |
- Dominic, Chris, 1968-, et al.
(författare)
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Four-dimensional concurrent engineering : an extended theoretical framework integrating packaging
- 2019
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Ingår i: Four-dimensional concurrent engineering. - : IAPRI. ; , s. 48-48
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Konferensbidrag (refereegranskat)abstract
- This paper takes on the challenge to integrate packaging in a concept of four-dimensional concurrent engineering (4DCE). The purpose is to explore a conceptual model and empirically evaluate the specific performance of packaging in interrelation with product and processes in the Supply Chain (SC). The objectives are to better understand the concepts of packaging logistics and logistics management in the SC. The conceptual model 4DCE is developed based on the three-dimensional concurrent engineering theories.The tool Packaging Scorecard is applied to evaluate the concurrent performance of packaging throughout the SC. The packaging system involves many actors that are integrated into the 4DCE framework with focus on interaction of SC and logistics in relation to packaging and product, with the overall aim to operate as effectively and efficiently as possible. In order to explore the potential of the 4DCE framework, empirical verification and testing of the concept has been carried out. The process has been done through multiple in-depth, action-oriented case studies in three different industries on the Swedish market. The case studies covered holistic aspects on the packaging system.The concept 4DCE contributes to packaging logistics theory by providing a framework for assessment incorporating complex and dynamic interactions between product, packaging, logistics and SC. Furthermore, the holistic packaging development concept is ensured by increasing knowledge of the packaging system and how it interacts with actors and performs to fulfil requirements along the SC. The 4DCE provides valuable data for packaging development processes in the cases, however there is a need for broader studies in different industries.
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| 21. |
- Dordlofva, Christo
(författare)
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Qualification Aspects in Design for Additive Manufacturing : A Study in the Space Industry
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this research is to further the understanding of implications for product development and qualification when introducing additive manufacturing (AM) in the context of the space industry. Increased availability of AM machines and alluring potentials such as design freedom and cost-efficient product development and manufacturing has led to a rapid growth in the use of AM. However, the implementation of AM is hampered by lack of process understanding, implying uncertainties for engineers on how to design products for AM. Furthermore, the AM process chain (including e.g. post-processes) is not sufficiently developed and understood, adding further uncertainties. These uncertainties are a challenge when developing products for space applications, especially if they are critical for mission success and hence not allowed to fail. Such products and their manufacturing processes have to comply with strict requirements on verifying performance, quality, and reliability, i.e. product and process qualification. The purpose of this research is to investigate how qualification is addressed during product development in the space industry in order to find improved ways for engineers to explore the capabilities of AM to better understand its possibilities and limitations. The research is specifically focused on the use of powder bed fusion processes by companies developing and manufacturing sub-system components for space applications. It is limited to the manufacturing of components on Earth for use in space. The research approach is qualitative. Five studies provide the empirical foundation for the thesis, in which a total of four companies are included. In particular, one of the companies is studied in-depth, including a development project for a critical AM product. Individual interviews, workshops and focus groups are used for data collection. Furthermore, the in-depth study is based on a longitudinal presence at the company, providing the opportunity to gather data from project meetings and discussions. Collaborative action research with three of the companies provides a research setting to study the development of three AM products (of which the in-depth study is one) and how uncertainties related to the AM process can be addressed. Four aspects of how to address product qualification in Design for AM are deduced: (i) AM knowledge should be built through application-driven development processes, (ii) qualification should be accounted for early and to a larger extent, (iii) suitable and acceptable requirements should be defined through collaboration, and (iv) rapid manufacturing should be utilised to evaluate critical uncertainties. To support engineering teams on how to address these aspects, this thesis presents two contributions to the design field. The first is a design process utilising AM Design Artefacts (AMDAs) to identify, test and evaluate the AM-related uncertainties that are most pressing for a product. Through the iterative use of AMDAs, products designs are successively evolved, enabling a design which meets process capabilities and fulfils product requirements. The AMDA design process is part of the second contribution, a Design for Qualification framework that encourages a qualification-driven development approach for AM products. The framework includes six design tactics that provide guidance for its implementation. The tactics encourage an application-driven development process where qualification is considered early, and where successive steps are taken towards a thorough AM process chain understanding. The framework is designed based on the studied cases, and future research should focus on developing the framework and tactics further to facilitate implementation and wider applicability.
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| 22. |
- Dufek, Jan, 1978
(författare)
-
Building the nodal nuclear data dependences in a many-dimensional state-variable space
- 2011
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Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 38:7, s. 1569-1577
-
Tidskriftsartikel (refereegranskat)abstract
- We present new methods for building the polynomial-regression based nodal nuclear data models. Thedata models can reflect dependences on a large number of state variables, and they can consider varioushistory effects. Suitable multivariate polynomials that approximate the nodal data dependences are identifiedefficiently in an iterative manner. The history effects are analysed using a new sampling scheme forlattice calculations where the traditional base burnup and branch calculations are replaced by a largenumber of diverse burnup histories. The total number of lattice calculations is controlled so that the datamodels are built to a required accuracy.
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| 23. |
- Dufek, Jan, 1978-
(författare)
-
Complex models of nodal nuclear data
- 2011
-
Ingår i: International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2011). - 9788563688002
-
Konferensbidrag (refereegranskat)abstract
- During the core simulations, nuclear data are required at various nodal thermal-hydraulic and fuel burnup conditions. The nodal data are also partially affected by thermal-hydraulic and fuel burnup conditions in surrounding nodes as these change the neutron energy spectrum in the node. Therefore, the nodal data are functions of many parameters (state variables), and the more state variables are considered by the nodal data models the more accurate and flexible the models get. The existing table and polynomial regressionmodels, however, cannot reflect the data dependences on many state variables. As for the table models, the number of mesh points (and necessary lattice calculations) grows exponentially with the number of variables. As for the polynomial regression models, the number of possible multivariate polynomials exceeds the limits of existing selection algorithms that should identify a few dozens of the most important polynomials. Also, the standard scheme of lattice calculations is not convenient for modelling the data dependences on various burnup conditions since it performs only a single or few burnup calculations at fixed nominal conditions. We suggest a new efficient algorithm for selecting the most important multivariate polynomials for the polynomial regression models so that dependences on many state variables can be considered. We also present a new scheme for lattice calculations where a large number of burnup histories are accomplished at varied nodal conditions. The number of lattice calculations being performed and the number of polynomials being analysed are controlled and minimised while building the nodal data models of a required accuracy.
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| 24. |
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| 25. |
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| 26. |
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| 27. |
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| 28. |
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| 29. |
- Engström, Tomas, 1950, et al.
(författare)
-
Alternativ montering
- 2008
-
Ingår i: Chukyo Keiei Kenkyu (academic japanese journal). ; 18:1, s. 73 - 153
-
Tidskriftsartikel (refereegranskat)abstract
- A translation into Japanese of the three authors’’ book written for and financed by the Swedish Metal Workers Union (IF Metall is Swedish). Namely, “Alternativ montering. Principer och erfarenheter från fordonsindustrin”, Engström, Jonnsson and Medbo 2005). Which was financed by this organization (i.e. Metall), and which summarizes the authors’’ insights and experiences in more popular terms (used for this organization’s education, as well as made available on their website) (see other publications registered in Chalmers Public library CPL).
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| 30. |
- Engström, Tomas, 1950, et al.
(författare)
-
Alternatives to Line Assembly: Some Swedish examples
- 1996
-
Ingår i: International Journal of Industrial Ergonomics. - 1872-8219 .- 0169-8141. ; 17:3, s. 235-245
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years, some criticism of Lean production has occurred, focusing among other things on the working conditions and the susceptibility of traditional assembly work in a society upgrading the demands for a more humanized work. Recently, this criticism has also concerned the technical aspects of this type of manufacturing. Because of this, alternatives to line assembly merit some attention. Experiences from some innovative production systems operated in the Swedish automotive industry during the last two decades are of particular interest. These unconventional production systems feature autonomous work groups and extended work cycles. These types of production systems are elucidated in detail by means of e.g nuance the concept of utilising buffers, i.e. there are different types of buffers (or buffer functions) as is classified (or clarified) in this publications.
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| 31. |
- Engström, Tomas, 1950
(författare)
-
Avrapportering av projekt ”Dokumentation av Volvo Personvagnars slutmonteringsfabrik i Uddevalla”
- 1995
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This publication reports on some of a research foundation's (Arbetsmiljöfonden) financed parts of Engström’s and his colleagues' (researchers a well as other individuals) participation in the design, development, starting-up and full-scale production phases of the Volvo Automobile assembly plant in Uddevalla. This particular initiative (for the publication now treated here) resulted on in the fact that all of the documents from this assembly plant was collected (thereafter sorted on site in order to eliminate redundancies), and finally were each and every binder of documents etc. sent to the basement at of Engström’s final experimental workshop located at Chalmers University of Technology (such workshops are nowadays utopian, see below). There these documents were harboured at this premise for several years until totally new building facilities were provided for a number of different departments. At this moment were rents accelerated (bewildering costs was claimed on individual scientists) (an experimental workshop proved to be utopian). Engström’s research group was therefore forced to let this documentation to be sent to external store rented outside of Chalmers. Moreover, this documentation included (in a similar manner but much better prepared from our side), all of the documents from the Volvo Kalmar assembly plant which was closed approximately a year after the Volvo Uddevalla assembly plant (see some of the other publications registered in Chalmers Public Library CPL). Later on (more than approximately two decades), was this totally unique documentation transferred to Volvo’s Historical Archive (organised under the Volvo Museum) who in all respects mistreated this material and also unfortunately neglected a written agreement (contract) with Chalmers and Engström. In fact, it was by no means a professional treatment of the material in question. In fact, they gradually proved to neglect it. as a part of a protracted process, i.e. this Volvo organisation dragged for years to do anything at all with it (they changed manager and proved to not be able to deal with these two documentations in any professional manner, among other things due to lack of space and must probably for other reasons as well). On the other hand, interest and help from Chalmers side were almost non-existing, at the very end of Engström’s employment were some rather lame efforts to carried out. Individuals at Chalmers were afraid to create conflicts Volvo by asserting the contract due to ongoing financing and the fact that Engström had to retire anyway. Consequently, were no help available from Chalmers side to claim the agreement with the previous manager of Volvo Museum etc. As a result, this material from the two unique/pioneering assembly plants was forever lost to the scientist, or lest severely mutilated (see comment below) (sadly, we never got time to gain any academic merits of this material, it just cost money drawn from Engström's donation granted from Volvo Uddevalla assembly plant). And believe the author here, it was an enormous (almost frightening) amount of binders, books etc. each of them scrupulous registered by Engström and his research colleagues as well as by local Volvo personnel that also kindly helped us out. Note, two written agreement with the top manager of each of these two assembly plants were both predating the contract with the Volvo archive by decades. Among other things, the material was partly used once again by local Volvo personnel than the Autonova plant later was constructed, i.e. some years after the closing down, i.e. the rebirth of the Volvo Uddevalla plant. However, to be frank, here, some of the material was just thrown in pallets at the very end, due to time restraints during our documentation processes. But generally speaking, were most of the material fully organised and saved in bookshelves at the basement of our final experimental workshop at Chalmers (and each binder etc, was assigned a sequence number that corresponded to our register sequence number, denotation, finding-place etc. (in accordance with the written agreements with the two top managers). It was in many respects a bewildering work carried out during several years (e.g. it was not easy for us to figure out exactly how) besides during the period of closing down were not Volvo personnel keen to let the central Volvo organisation get hold of anything (no other would probably have managed to carry through such documentation for a number of different reasons). A comment and important: The documentation work from our side was organised in accordance with the process and organisation of each of the two assembly plants. Thus, was it not following the Swedish Archive Standard usually supported by rather unmanageable PC-based systems (which Volvo’s Historical Archive practised). This archive standard would, in fact, have fragmented et the two documentations, and thereby not enhanced a deeper understanding of each assembly plant (such standards are used for saving of single/individual documents or series thereof) (interrelation between binders and documents are thereby entirely lost). This fact was clear to us and also considered by the earlier manager at the Volvo archive and thus dealt with in the agreement between Chalmers and the historical archive. Among other things was Engström from the beginning supposed to help Volvo out by means of packing up the material. However, this was not considered by the new manager (who, as said before, neglected the registering and work carried out by Engström's research group).
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| 33. |
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| 34. |
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| 35. |
- Engström, Tomas, 1950, et al.
(författare)
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Developments in Assembly System Design: The Volvo Experience
- 1999
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Ingår i: Coping with Variety: Flexible Production Systems for Product Variety in the Automobile Industry; Lung, Y., Chanaron, J. J., Fujimoto, T. and Raff, D. (eds.); Ashgate, Aldershot. - : Routledge. - 9780429839931 ; , s. 192-223
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter focuses on experiences concerning the development of assembly systems within the Volvo Corporation. It provides research and development work within the Swedish automotive industry. The chapter considers a specific trajectory concerning assembly system design in the Swedish automobile industry, generalising the Volvo Kalmar and Volvo Uddevalla experiences. During 1988–1990, the managers at Volvo were planning the manufacturing of the new 800 model at the main Volvo Torslanda plant, as well as looking for a total redesign of the plant. The average product quality in the Uddevalla plant was high–in fact better than in Volvo's line assembly plants–but the product quality varied considerably. Productivity and flexibility proved to be superior to traditional serialassembly systems. Two ways of decreasing the time losses are to introduce parallel flow assembly systems–that is assembly systems consisting of many, short, unpaced flows–or to introduce buffers between work-stations.
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| 36. |
- Engström, Tomas, 1950, et al.
(författare)
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Effektiv småbåtsproduktion. Delrapport
- 1984
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Consumer report ("avnämarrapport" in Swedish) for a research foundation (Styrelsen för Teknisk Utveckling, Stockholm). A comment: Publishing consumer reports was the praxis during this (early) period of time at Chalmers University of Technology, as well as probably at some other universities. This means that frequent and vast academic publication by means of e.g. conference papers and refereed contributions to scientific journals was almost unheard of. At least so for some of the applied science disciplines. However, today are the situation indeed very different (i.e. earlier was the publication in many respects focused on trying to satisfy the executive administrator the research foundation in question etc.). To be more precise, this early praxis was definitively the case for the research and development work carried out at the Department of Transportation (a broadly applied science discipline), which was characterized by more practical strives to e.g. engineer research results. Rather than relying on truer scientific efforts in a narrower sense. Functional satisfaction (i.e. something engineered work as planned instead verification/falsification of a hypothesis) was judged as being a primary aim of this research and development work. Therefore are (in the context of the publications registered in Chalmers Public Library CPL) the author making distinctions between consumer reports, on one hand. And, one the other hand, reports and preprints (manuscripts), while instead the academically orientated publications are various sort of scientific contributions presented at conferences or published in scientific journals (actually it is somewhat more complex, but further explanations are omitted here). The consumer reports were aimed at a various external organization with who the authors cooperated, and these are in many cases not available in PDF format to be easily read by logging in at CPL. This particular approach has judged as being fair/relevant fair in order to mirror of work conducted by the author or authors during the passing decades. Besides, the competencies at Chalmers Library, who actually have been very helpful, have not managed to provide appropriate answers to the various questions implied being at hand just above (this despite trying to get hold of such answers, hence this very comment).
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| 37. |
- Engström, Tomas, 1950, et al.
(författare)
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Engström, T. and Jonsson, D. (2016). Development and Application of (Certain) Principles for Work Structuring
- 2015
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This manuscript is an extensive book (or preprint not yet finished to due to one the author’s retirement) summaries four decades research and development work dealing with development work of alternatives to assembly lines and assembly line work, as have been the case for one of the two authors from a technical point of departure (he is a senior research competency in mechanical engineering). On the other hand, the other authors have an even longer time perspective, but he has a social science background (he is a senior research competency within sociology for more than four decades). That is, they have been working at Chalmers University of Technology respectively at Gothenburg University all throughout their professional life. This while they both are belonging to a normative sociotechnical research tradition earlier at hand in the Gothenburg area, which actually has emanated from specific precursors at Gothenburg University (i.e. mainly professor Edmund Dalhström at the Department of Sociology), this research tradition was later on brought over to Chalmers by professor Ulf Karlsson responsible for operation management at the same university. It is fair to state that this research area required the amalgamation of technical as well as social science aspects. Efforts that during the passing years have been substantiated by extensive help and support from the Swedish automotive industry (Saab Scania and Volvo companies, as well as other parts of the industry) and also from several governmental research foundations. In fact, a truer cross and multi-science research approach than what usually is at hand has always been required. The extensive book manuscript is exceeding more than 600 pages. Twelve chapters exists as well as also a number of freestanding appendixes and the necessary (all-pervading) definitions of primary concepts and term in combination with explaining various synonyms and homonyms (a particular dilemma for cross and multi-science approaches) (i.e. are we in agreement with the text it alone, or are we eventually together understanding the underlying meaning). Moreover, the text is scrutinized by word process programs in form of Word as well as by the professional English check-up program Grammarly) and all of the necessary figures are completed. i.e. several revisions of this manuscript have been iterated first between the authors and later on against other parties. Most notable are external revisions by two senior research competencies (professor David Bennet responsible for operation management at Aston Business School, Birmingham and professor Lennart Nilsson responsible for vocational learning and training at Gothenburg University, Gothenburg). The authoring just described (involving the initiated hinted just above) have occupied our minds for more than one decade (our co-authoring and work with specific Japanese research colleagues, have most certainly underlined a need for careful writing, since among other things just nicking the practitioners’ nomenclature will be misleading, as is also the case while relaying on one or a few scientific research areas) (see some of the other publications registrated in Chalmers Public Library CLP) (it is most certainly an extensive research area, and the skills needed to be mastered in order to understand are indeed wide). The underlying principles of any (real-life) assembly system must, according to our understanding, are inventible required to be explained. Thus, it is important for the analyst to grasp whether or not the principle applied is correct or if the practice is questionable. This means, metaphorically speaking, is the original drawings accurate or have the execution (practice) faulty. The two most sociotechnically advanced (real-life) assembly systems both proved to be successful (more efficient and flexible in relation to comparable assembly lines, and work and work conditions were far better). They were both based on correct principles (i.e. the nowadays defunct Volvo Uddevalla plant and the so-called assembly docks at the Volvo Tuve heavy truck chassis plant located in Gothenburg). As will become evident by the content brought forward in this extensive book manuscript. A comment. The most socio-technically advanced assembly system designs inventible requires reformed/reconfigured information systems dealing with product data (which in turn defines the product architecture and product variation). In fact, no any such (real-life) plant or assembly system would work as anticipated otherwise. And this publication is to some extent describing some selected aspects of this (very) dilemma (changing information systems are usually not something considered than designing assembly systems) (thus are totally new plants – and in turn totally new information systems – most often the real practical change to create something unorthodox) (however, which scientist will gain such opportunities, this is really rare, i.e. the projection of the Volvo Uddevalla plant was thus an exception and the trust given by the industry – by Volvo Uddevalla project organisation – was appreciated by some of the authors).
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| 38. |
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| 39. |
- Engström, Tomas, 1950, et al.
(författare)
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Evaluation Methods for Assembly Work and Product Design in Radically Different Production Systems: Results from case studies and action research in Swedish industry
- 1993
-
Ingår i: Productivity & Quality Management Frontiers – IV, Proceedings 4th Int. Conference on Productivity & Quality Research, Miami; Suthmanth, D. J., Edosomwan, J. A., Poupart, R. and Sink, D. S. (eds.), Industrial Engineering and Management Press, Norcross, Georgia. ; 2, s. 333 - 342
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Konferensbidrag (refereegranskat)
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| 40. |
- Engström, Tomas, 1950, et al.
(författare)
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Extended Work Cycle Assembly - A crucial learning experience
- 1994
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Ingår i: The International journal of human factors in manufacturing. - : Wiley. - 1045-2699 .- 1522-7111. ; 4:3, s. 293-303
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports on a crucial learning experience relating to design principles applied in the Volvo Car Corporation final assembly plant in Uddevalla, Sweden. These principles include the concept of holistic learning, specifically through the creation and transformation of complementary, interrelated physical, semantical, and cognitive structures. We report on the learning environment and learning aids, as well as the learning method applied to the assembly of one-quarter of an automobile performed by one single person. Through the application of this learning concept, it proved possible to dramatically reduce the learning time required for long cycle time assembly work, making cycle times of 2 hours or more a practical proposition for full-scale automotive manufacturing today.
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| 41. |
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| 42. |
- Engström, Tomas, 1950
(författare)
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Flödesmönster i serieproduktion
- 1987
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Ingår i: Essäsamling, Arbetsmiljöfonden, Arbetsmiljöfonden (AMFO).
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 43. |
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| 44. |
- Engström, Tomas, 1950
(författare)
-
Förändring av industriell praxis till funktionella förebilder
- 1990
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Ingår i: Arbetsliv i utveckling – Om forskarstött förändringsarbete, Arbetsvetenskapliga Kollegiet i Göteborg. Göteborg, sid 25 - 37.
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The publication (or this book) was written during a period of time that Arbetsvetenskapliga Kollegiet running in Gothenburg (a research project financed by the Swedish Work Environment Fund in Stockholm (“Arbetsmiljöfonden AMFO” in the Swedish language), which were organized as a joint venture initiative between a number of selected department at Chalmers University of Technology and at Gothenburg University).
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| 45. |
- Engström, Tomas, 1950, et al.
(författare)
-
Illustrationer av funktionella grupper och monteringsfaser
- 1988
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Consumer report for the company in question (the Volvo Automobile Company) which is financed by the company and partly also by a research foundation. It is a matter of a work that in this particular case were carried out during nine years in a number of experimental workshops located outside the Chalmers University of Technology. This system of interrelated drawings was in the developed in the experimental workshop an formed the basis for the assembly work conducted at the Volvo Uddevalla plant (it explains/illustrated a so-called assembly-oriented product structure, which is something very different from the common Volvo companies so-called Function Group Register that instead is a design-oriented product structure) (see the authors' other publication). These workshops were financed by the Volvo Automobile and Truck companies. This achievement, as the final contribution to the Swedish automotive industry after having already treated this research field/problem area for more than two decades before this particular period if time (involving several junior and senior research competencies, as well as industrial and governmental founding). This system of interrelated drawing was developed in one of the experimental workshops together with e.g. operators (as well as senior research competency within vocational learning and training from Gothenburg University) from the temporary learning and training workshop predating the Volvo Uddevalla plant, and thereafter used for full-scale product purpose in the completed assembly plant. They were formalised by an information system used for such purposes. Thus, it is fair to state that these particular drawings were validated at an industrial scale, expressing an assembly-oriented product structure for the Volvo 700-model (note that the system represents years and years of work from both our and others side) (we were helped out by an architect from Chalmers University of Technology, who worked for years in one of the experimental workshops thereby helping us out to formalise the decomposed automotive products (see the authors’ other publications). Comment 1: See a conference contribution from 1992 that also is registered and available as o PDF-document at Chalmers Public Library (CPL) (a self-developed method found out together with e.g. a junior research competency from the School of Architecture at Chalmers as well as by getting helped out på the senior research competency withing vocational learning and training). Comment 2: Publishing reports, especially consumer reports, was the praxis during this (early) period of time at Chalmers University of Technology, as well as probably at some other universities. This means that frequent and vast academic publication by means of e.g. conference papers and refereed contributions to scientific journals was almost unheard of. At least so for some of the applied science disciplines. However, today are the situation indeed very different (i.e. earlier was the publication in many respects focused on trying to satisfy the executive administrator the research foundation in question etc.).
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| 46. |
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