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- Baird, John C., et al.
(författare)
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Stimulus Sequence and the Exponent of the Power Function for Loudness
- 1991
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Ingår i: Perceptual and Motor Skills. - : SAGE Publications. - 0031-5125 .- 1558-688X. ; 73:1, s. 3-17
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Tidskriftsartikel (refereegranskat)abstract
- In two experiments, 15 and 13 subjects estimated the loudness of 12 sound-pressure levels (38–104 dB; 6-dB intervals) of a 1000-Hz tone by the method of magnitude estimation with a modulus assigned to the first stimulus presented. The tone duration was 1 sec. and the interstimulus interval was 6 sec. The presentation order was systematically ascending-descending in one experiment and balanced-irregular in the other. The results indicate that (1) loudness is a power function of sound pressure with an exponent of 0.60 for the systematic order and 0.29 for the irregular order. (2) For both the irregular and systematic orders, a large step-size (12 or 18 dB) between the stimulus on Trial n and on Trial n-1 (or n-3) results in a slight assimilation effect. This also occurs for the small step-size (6 dB) in the irregular order. (3) The size of momentary exponents (based on two points, Trials n and n-l or n-3) depends on the sound pressures of successive stimuli, whether the steps are positive or negative, and whether the stimuli have been presented in systematic or irregular order. For positive steps, the momentary exponent is lower for a soft tone (Trial n) than for a loud tone, whereas for negative steps the momentary exponent is lower for a loud tone than for a soft tone. These effects are more pronounced when these stimuli are presented in an irregular order. A relative judgment model is offered for magnitude estimation. It assumes that subjects judge the loudness of a stimulus in terms of three reference markers: the minimum and maximum sound pressures as well as the sound pressure of the previous stimulus.
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| 5. |
- Bengtsson, Lars, 1958-, et al.
(författare)
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Framtida produktionskoncept : Verkstadsorienterad produktion och decentraliserat datorstöd
- 1993
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report elaborate a vision of decentralized work organisation and especially the use of shop floor oriented computer system to support this. The focus is on industrial production. The report is divided into three parts.The first part discuss the characteristics of future production concepts in industrial companies. The point of departure is that Swedish companies abandon Taylorist principles of organization. Alternative paths of rationalization are examined, e.g. Anthropocentric Productions System, Computer Integrated Manufacturing, Lean Production, Total Quality Management and Time Based Management. A conclusion drawn is that future production concepts should be shop floor oriented.The second part present a vision of this shop floor oriented concept. The vision is elaborated in terms of work organization, goal oriented group work and decentralized computer support. Primarily the principles and the concrete functions of new types of shop floor oriented computer systems are presented. This concern systems for production planning and control (Leitstand) and NC programming (WOP). Examples of graphics produced by these systems are given. An alternative CIM strategy based on these systems is also examined.The third part discuss the process of change toward this new production concept. This is enlightened through two case studies.
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- Bengtsson, Lars, 1958-, et al.
(författare)
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Kvalitet och arbetsutveckling- hur går det ihop? : En förstudie
- 1994
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- During the 20th century taylorism has been dominating as a production. concept. But lately the companies has started to look for new concepts. Examples of these are presented in the report: Flexible taylorism, Computer Integrated Manufacturing, Socio-technic, Anthropocentric Production Systems, Lean Production, Time Based Management, Total Quality Management (TQM) and Reengineering. Quality as a strategy is getting stronger and stronger and the prior focus on work organization. and better jobs have now turned towards TQM. TQM consists of, except of different techniques and methods, development of organization, work and personnel.The main question in our study concern the connection between the development of quallity and work. The efficiency in changes is in many parts depending on the organization of work and the motivation and knowledge of the employees. In accordance to this we have used a model in six case-studies that distinguish the technical system and different quality methods used, but mainly the changes concerning personnel and organization. The results are:* The companies follow three quality strategies that affect the employees situation: Control, Motivation and Work development.* The choice of strategy depends on experiences from Work development and the production philosophy in the company.* The Control strategy can give better quality but poor productivity. There are no belief in workers and the work is controlled in detail.* The Motivation strategy upgrade the workers but only optimize the existing system. It can give contradictory work demands if the responsibility for quality inspection is not based on authorities.* The Working development strategy gives possibilities to a flexible manufacturing system and a good work. In ideal the development of work and quality is one process with the same persons involved.* Quality systems based on ISO 9000 have limited effects on the inner efficiency and bring a risk for a new hierarchy.* TQM-work can change the quality organization and create two different organizations. One that is working with product quality and one that is working across the traditional organization.* Kaizen-work has in the study only been seen on the shop floor and as a tool for optimizing the direct work/working place.* TQM is to make all processes in a company better. That makesmeasuring and feedback important. It can affect in total managementcontrol or give the opportunity to management by objectives.* The unions has no strategy for have to deal with quality strategies.
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| 7. |
- Björling, Mikael, et al.
(författare)
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Conformational adaption of poly(ethylene oxide). A 13C NMR study
- 1991
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Ingår i: Journal of Physical Chemistry. - 0022-3654. ; 95:17, s. 6706-6709
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Tidskriftsartikel (refereegranskat)abstract
- The 13C NMR chemical shift was used as a probe for the average partition of rotational conformers around the C-C bond in the O-CH2-CH2-O segments of polyethylene oxide). Dividing the conformers into a large group of trans and a smaller group of gauche conformers, we concluded that the trans conformers have a higher (downfield) average chemical shift than the gauche conformers. The shift of the main PEO 13C line with changing environment was interpreted as an adaption in the partition between the two groups of conformers. Furthermore, the trans conformers had nonpolar character and were favored at high temperatures, whereas the gauche conformers had polar character. The measurements were compared to the predictions of a model proposed by Karlström, and a semiquantitative agreement was found.
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| 8. |
- Björling, Mikael, et al.
(författare)
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Distribution of segments for terminally attached poly(ethylene oxide) chains
- 1990
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Ingår i: Journal of Physical Chemistry. - 0022-3654. ; 94:1, s. 471-481
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Tidskriftsartikel (refereegranskat)abstract
- A theory for describing the equilibrium ethylene oxide (EO) segment distribution for terminally attached poly(ethylene oxide) (PEO) chains is presented. It is based on Scheutjens and Fleer's lattice model for polymer solutions in heterogeneous systems and a two-state model for the EO segments. The two-state model provides one explanation of the solubility gap of homogeneous PEO solutions. The segment distribution is examined as a function of temperature, grafting density, and curvature. The present theory predicts distributions, which cannot be reproduced with the use of temperature-dependent interaction parameters in a one-state model. Specifically, the segments tend to be more accumulated at the surface but also far away from the surface at the expense of the intervening transition region. Calculation on a model of a micelles formed by the nonionic surfactant C 12E 8 supports the experimental conclusions that the EO segments are preferentially accumulated nearby the hydrocarbon core and not completely extended into the water region.
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| 9. |
- Björling, Mikael
(författare)
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Interaction between Surfaces with Attached Poly(ethylene oxide) Chains
- 1992
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 25:15, s. 3956-3970
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents a self-consistent mean-field lattice theory of the Scheutjens-Fleer type where segments may adapt to temperature and the local environment by changing their distribution among internal states. Some new features are introduced in the theoretical treatment of incompressible systems, and it is demonstrated how the chemical potential may be calculated without reference to a bulk system. The theory is applied to make a qualitative prediction for the interaction between surfaces with grafted poly-(ethylene oxide), or PEO, chains. A simple two-state model for the PEO segments is used. The attractive force between the PEO-covered surfaces in water is predicted to be related to the temperature-dependent solubility of PEO in water. The contributions to the force are illustrated by simple examples. The attractive force does not change monotonically upon changing the graft density. At low coverages a strong bridging attraction is predicted if the surfaces are hydrophobic. As the surfaces become more polar, repulsion sets in at a larger separation and the overall attraction becomes less strong. A calculated, closed, solubility gap for a crude model of micelles of nonionic surfactants is presented.
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