| 1. |
- Lilja, Johan, 1978-, et al.
(författare)
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Exploring an ecosystemic and regenerative approach to quality management : towards new theory and practice for a living world
- 2023
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Konferensbidrag (refereegranskat)abstract
- Quality Management (QM) is currently facing a new landscape that makes the traditional emphasis on internal organizational excellence as well as many of the QM leadership control practices, increasingly insufficient. The purpose of this paper is to contribute to revitalizing and updating QM theory and practice for a living world by exploring an ecosystemic and regenerative approach. The paper presents initial results from a study of the phenomena of developing and improving together, across boundaries of organizations and actors, in two complex ecosystems. The results highlight four enablers and six wishes that could inform further exploration and future QM practice.
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| 2. |
- Tesch, Per, et al.
(författare)
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Peak oxygen uptake using a training device for combined resistance and aerobic exercise in space and on earth
- 2008
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Ingår i: 13th Annual Congress of the European College of Sports Science. - Cologne : Sportools. - 9789727351565 ; , s. 523-
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Konferensbidrag (refereegranskat)abstract
- Astronauts traveling in Orbit are mandated to perform both aerobic and resistance exercise to combat cardiovascular and muscular deconditioning. A non-gravity dependent flywheel resistance exercise device (FWD), proven to be effective in blunting muscle atrophy when used by bedridden subjects, has been configured to allow for aerobic exercise as well. The current study aimed at determining aerobic energy yield and related physiological demands during exercise using this novel apparatus. Methods: Eight men and women (23±3 yrs, 65±5 kg, 170±6 cm) performed all-out, indoor, stationary rowing exercise randomly on either a commercially available Concept II ergometer (CII) or the FWD. Using a magnetic brake system, the FWD and similar to the CII, produced mainly concentric resistance exercise with the aid of the inherent inertia of rotating flywheels. Progressive exercise protocols (increased frequency and magnetic force) assessed peak oxygen uptake and heart rate, rate of perceived exertion and post lactate concentration. Results Peak oxygen uptake averaged 3.18±0.50 and 3.11±0.49 l/min, respectively during exercise using CII and FWD. Peak oxygen uptake, plasma lactate concentration, heart rate and rate of perceived exertion were not different (p>0.05) across exercise using these two devices. However, time to exhaustion was somewhat (p<0.05) longer for the FWD. Conclusion: Collectively the current results suggest that the novel method of offering an aerobic exercise stimulus is as effective as the most established technology for indoor rowing used by crew. Given that the space agencies have recognized the need for effective exercise countermeasures hardware that has a feasible mass and envelope and features allowing for multiple purposes (e.g., concentric/eccentric resistance and aerobic exercise) in a single piece of apparatus, the current technology should be considered for use in space.
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| 3. |
- van de Beek, Jaap, et al.
(författare)
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A conceptual study of OFDM-based multiple access schemes : Part 2: Channel estimation in the uplink
- 1996
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper deals with the design of channel estimators in the uplink of an OFDM based multi-user system. First, we propose a user allocation scheme that is based on the aim to use the correlation of the radio channel for channel estimation purposes. Further, we present the linear MMSE channel estimator based on a few pilot tones. We present an error analysis that proves valuable in the evaluation of linear channel estimators under mismatch. Finally, we present some results on the design of linear channel estimators and pilot patterns, showing by means of examplesthe importance of careful pilot positioning.
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| 4. |
- van de Beek, Jaap, et al.
(författare)
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A conceptual study of OFDM-based multiple access schemes : Part 3: Performance evaluation of a coded system
- 1996
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper is part of a conceptual study of a multiuser OFDM system. In previous reports we have examined requirements for the air interface and presented uncoded performance (in terms of bit error rate) for the uplink of such systems. In this report we adopt the user allocation structure from the previous parts of the study and examine the role of channel coding. We present performance simulations that illustrate the effects of a convolutional code exploiting channel diversity, and channel estimator performance exploiting the channel correlation.
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| 5. |
- van de Beek, Jaap, et al.
(författare)
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A conceptual study of OFDM-based multiple access schemes : Part 4: Tracking of time and frequency offset
- 1996
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper is part of a conceptual study of a multiuser OFDM system. In previous reports we have examined requirements for the air interface and presented uncoded performance (in terms of bit error rate) for the uplink of such systems. In this report we adopt the user allocation structure from the previous parts of the study and examine the role of channel coding. We present performance simulations that illustrate the effects of a convolutional code exploiting channel diversity, and channel estimator performance exploiting the channel correlation.
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| 6. |
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| 7. |
- van de Beek, Jaap, et al.
(författare)
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Channel estimation in the uplink of an OFDM system
- 1996
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Ingår i: Proceedings of Nordic Radio Symposium. ; , s. 32-35
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Konferensbidrag (refereegranskat)abstract
- This paper deals with the design of linear pilot based channel estimators in the uplink of an OFDM-based multiuser system, We evaluate such estimators and pilot patterns, showing by means of examples the importance of careful pilot positioning.
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| 8. |
- van de Beek, Jan-Jaap, et al.
(författare)
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A time and frequency synchronization scheme for multiuser OFDM
- 1999
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Ingår i: IEEE Journal on Selected Areas in Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8716 .- 1558-0008. ; 17:11, s. 1900-1914
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Tidskriftsartikel (refereegranskat)abstract
- We present a multiuser synchronization scheme for tracking the mobile's uplink time and frequency offsets. It uses the redundancy introduced by the cyclic prefix and does not need additional pilots. We show performance results of an orthogonal frequency division multiplexing (OFDM)-based radio interface based on universal mobile telecommunication system (UMTS) parameters. For a UMTS-typical mobile channel environment, the performance of a coherent system employing the scheme is virtually indistinguishable from the performance of a perfectly synchronized system. In a differentially modulated system, synchronization errors decrease the system performance by about 0.7 dB compared to a perfectly synchronized system. Index Terms - Communication system, delay estimation, frequency estimation, multicarrier, multiuser system, orthogonal frequency division multiplexing (OFDM), synchronization, universal mobile telecommunication system (UMTS).
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| 9. |
- van de Beek, Jaap, et al.
(författare)
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Synchronization of a TDMA-OFDM frequency hopping system
- 1998
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Ingår i: Pathway to a global wireless revolution. - Piscataway, NJ : IEEE Communications Society. - 0780343204 ; , s. 1290-1294
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a Time Division Multiple Access-Orthogonal Frequency Division Multiplexing (TDMA-OFDM)-based radio interface proposal for the Universal Mobile Telecommunication System (UMTS). We focus on synchronization and present an implementable algorithm for the tracking of the mobiles' time and frequency offsets at the base station in the uplink. This algorithm is based on recently developed estimation methods that use redundancy introduced by the cyclic prefix. A modified Maximum Likelihood (ML) estimator for the Additive White Gaussian Noise (AWGN) channel is used to meet both implementational requirements and performance requirements for frequency-selective fading multiuser environments. Simulation results for a typical UMTS mobile channel environment show that the uncoded symbol error rate of a coherently modulated system using our synchronization scheme is virtually indistinguishable from that of a system with no time and frequency offset.
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| 10. |
- Wahlqvist, Mats, et al.
(författare)
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A conceptual study of OFDM-based multiple access schemes : Part 1: Air interface requirements
- 1996
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The multimedia era has started. The migration of computer (packet oriented) and telephony (circuit switched) networks in combination with an explosive development of new services, creates a mass market for public broadband communication. There are no reasons foreseen why these kinds of services should not go mobile. Future customers will not treat a mobile access differently than a fixed access to the network. The different types of services together with the demand of broadband mobile communication requires a new air interface. Limitations in the existing systems (flexibility and bit-rate) gives that they are not serious competitirs.
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