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Träfflista för sökning "WFRF:(Olsson Bengt) srt2:(2000-2004);srt2:(2001)"

Sökning: WFRF:(Olsson Bengt) > (2000-2004) > (2001)

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1.
  • Evilevitch, Alex, et al. (författare)
  • Kinetics of oil solubilization in microemulsion droplets. Mechanism of oil transport.
  • 2001
  • Ingår i: Langmuir. - American Chemical Society. - 1040-0397. ; 16:23, s. 8755-8762
  • Tidskriftsartikel (refereegranskat)abstract
    • We have studied the kinetics of the solubilization of oil through a temperature jump into a droplet microemulsion phase in the system water-pentaethylene oxide dodecyl ether-decane at 25 C. The initial state is formed by subjecting the equilibrium system at 25 C to a temperature quench to 22, 20, and 14 C, respectively. At this lower temperature, which at equilibrium corresponds to a two-phase system, oil droplets form and grow in size with increasing time. By varying the time between the quench and the T-jump, the size of the initial oil drops is varied in a systematic and known way in the relaxation study. The relaxation process is monitored by following the turbidity of the system. We find that for all the systems the relaxation back to equlibrium is much faster than the drop growth process observed after the temperature quench. This general observation is explained by realizing that the redissolution of the oil drops is analogous to the oil transfer phase, which in the quench experiment occurs prior to the Ostwald ripening phase. More significant is that we observed a qualitative transition in the relaxation behavior when the initial aggregate distribution is varied. In all cases we have the same initial temperature and overall composition and one population of many small droplets and fewer larger drops. The size of the larger drops only affects the relaxation in a quantitative way. If the small droplets are only slightly smaller than the equilibrium size, equilibration occurs through the diffusion of oil molecules in the bulk phase. When the initial droplets are sufficiently small, a new kinetic route is available where there is an efficient direct oil transfer between the small droplets and large drops. This allows for a fast relaxation of the oil distribution between the two populations of drops.
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2.
  • Evilevitch, Alex, et al. (författare)
  • Molecular transport in a nonequilibrium droplet microemulsion system.
  • 2001
  • Ingår i: Langmuir. - American Chemical Society. - 0743-7463. ; 17:22, s. 6893-6904
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we consider the problem of oil molecular transport between nonequilibrium microemulsion oil droplets in water. In particular, we have investigated the kinetics of solubilization of big oil drops by smaller microemulsion droplets transforming a bimodal size distribution into an equilibrium microemulsion with a unimodal size distribution. The process involves the diffusion of oil monomers across the aqueous solvent. Solubilization experiments are presented on a well-characterized nonionic microemulsion system, where interfacial area and dispersed volume are conserved and where the excess oil chemical potential is dominated by interfacial curvature energy. An analysis of the experiments shows that the solubilization kinetics depend significantly on the concentrations and sizes of big and small droplets. We formulate a quantitative model for the solubilization kinetics where the effects of size and concentrations are treated within the framework of a cell model. A quantitative agreement between model and experiment is obtained, and the analysis also shows that the majority of oil monomers are captured by small droplets already in the vicinity of the big drop surface when the concentration of small droplets is high.
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4.
  • Lif, Magnus, et al. (författare)
  • Workspaces enhance efficiency – theories, concepts and a case study
  • 2001
  • Ingår i: Information Technology and People. - MCB UP Ltd. - 0959-3845. ; 14:3, s. 261-272
  • Tidskriftsartikel (refereegranskat)abstract
    • Traditional process-oriented system development methods often result in fragmentary user interfaces with information presented in various windows without considerations of requirements for simultaneous viewing. Opening, closing, moving and resizing these windows attracts the users’ attention away from the actual work. User interface design according to the workspace metaphor could provide skilled professional users with an efficient, customised user interface to administrative information systems. This can improve work performance and facilitate efficient navigation between workspaces. A case study in co-operation with the Swedish National Tax Board (RSV) describes practical use of the workspace metaphor.
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6.
  • Olsson, Eric, et al. (författare)
  • The emotional climate of care-giving in home-care services
  • 2001
  • Ingår i: Health & Social Care in the Community. - Blackwell Publishing. - 0966-0410. ; 9:6, s. 454-463
  • Tidskriftsartikel (refereegranskat)abstract
    • The emotional aspects of the care-giving relationship in home-care services are studied, starting from the home-care recipients' and the home-care workers' perception of the emotional climate. Their experiences of the care-giving relationship and the influence from different aspects of the care-giving situation and social processes in the work organisation are explored. Two hundred and twenty-two recipients and their home-care workers in three typical Swedish municipalities were studied. The emotional climate is described with the help of a scale of 85 adjectives. Results show that home-care workers are more likely to experience the climate with a higher degree of emotionality. There is symmetry between the parties in the perception of a negative climate. However, if one party perceives the climate as close the other party is more likely to perceive it as rational or instrumental. The organisational processes, especially the group climate of the work team, principally influence the home-care recipients' perceptions. The workers' perceptions are principally influenced by age and gender of the recipients and the workers' own age. The emotional climate is constructed in a process between the parties, depending on their responses to each other. Tendencies to perceive a specific climate are strengthened or weakened by context variables and this in turn changes the care-giving interaction.
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7.
  • Olsson, Eric, et al. (författare)
  • The frail elderly, family network and public home help services : a pilot study of the parties' perception of the help and their reciprocal relationships
  • 2001
  • Ingår i: Working paper-serien. - Lunds universitet : Socialhögskolan. - 91-89604-06-7 ; 2001:2
  • Konferensbidrag (övrigt vetenskapligt)abstract
    • The family with the elderly and the home help workers’ team constitute two organisations, which meet in the care work. In this context the family is extended and often constitute not only members from the nuclear family but also other members of the network of relatives, whom take part in the care of the elderly. The extended family may in some cases include four generations (Finch & Mason, 1993). Home-help for elderly people have expanded in Sweden during the period 1960 - 1980. This was due partly upon the prevailing ideology that it is important for frail elderly to stay in their own homes. Due to this expansion the local communities have developed their public home-care organisations. Different kinds of autonomous group organisation predominate (Olsson et al, 1995). Small work groups take responsibility for home help service in local areas. Home-helpers organise their job themselves, exchange experiences and give each other emotional support. In Sweden both home care and institutional care of the elderly has decreased during the 1980th and 1990th in spite of the fact that the proportion elderly over 80 years (4,5 % of the total population) has increased 60 % since 1980. Twenty-two per cent of the women and 16 % of the men over 80 were cared for in their own home 1996. This development is said to have caused relatives to care for their frail elderly in the homes side by side by the home help services in an increasing degree (Johansson, 1991; Szebehely, 1998). Public care and service has an important impact on the interaction pattern between family members (Hendriksen, 1989; Johansson, 1999; Bass m fl, 1999). Home care may serve as an intervention that influences the health, well-being and life quality of the elderly and other family members. This intervention may have positive as well as negative effects. Problems and conflicts may arise in the interaction between the family members and between the family and the public help services (see McGoldrick & Gerson, 1989). We need more knowledge about these processes. In a research project1 the family and the home help services are studied as two organisations, which interact in the care of the elderly. We start with the hypothesis that the relation between the parties will have an impact on the character and quality of the care. We also think that the quality of the interaction will have an impact on the health and wellbeing of the elderly (see Olsson, 1991, 1998; Olsson & Ingvad, 1999).
8.
  • Olsson, Jan-Ola, et al. (författare)
  • A Turbocharged Dual-Fuel HCCI Engine
  • 2001
  • Ingår i: SAE Special Publications. - Society of Automotive Engineers. - 0099-5908. ; 2001:1627
  • Konferensbidrag (refereegranskat)abstract
    • A 6-cylinder truck engine is modified for turbocharged dual-fuel Homogeneous Charge Compression Ignition (HCCI) engine operation. Two different fuels, ethanol and n-heptane, are used to control the ignition timing. The objective of this study is to demonstrate high load operation of a full-size HCCI engine and to discuss some of the typical constraints associated with HCCI operation. This study proves the possibility to achieve high loads, up to 16 bar Brake Mean Effective Pressure (BMEP), and ultra-low NOdx emissions, using turbo charging and dual fuel. Although the system shows great potential, it is obvious that the lack of inlet air pre heating is a drawback at low loads, where combustion efficiency suffers. At high loads, the low exhaust temperature provides little energy for turbocharging, thus causing pump losses higher than for a comparable diesel engine. Design of turbocharger therefore, is a key issue in order to achieve high loads in combination with high efficiency. In spite of these limitations, brake thermal efficiencies and power rating close to those of the original diesel engine are achieved with significant reduction in NOdx emissions. The maximum efficiency is 41.2%, which is slightly lower than for the original diesel engine.
9.
  • Olsson, Jan-Ola, et al. (författare)
  • Closed-Loop Control of an HCCI Engine
  • 2001
  • Ingår i: SAE Transactions, Journal of Engines. - Society of Automotive Engineers. - 0096-736X. ; 110:3, s. 1076-1085
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents a strategy for closed-loop control of a multi-cylinder turbocharged Homogeneous Charge Compression Ignition (HCCI) engine. A dual fuel port injection system allows control of combustion timing and load individually for each cylinder. The two fuels used are isooctane and n-heptane, which provides a wide range of autoignition properties. Cylinder pressure sensors provide feedback and information regarding combustion. The angle of 50% heat release is calculated in real time for each cycle and used for timing feedback. Inlet air preheating is used at low loads to maintain a high combustion efficiency.
10.
  • Olsson, Louise, 1974-, et al. (författare)
  • A Kinetic Study of NO Oxidation and NOx Storage on Pt/Al2O3 and Pt/BaO/Al2O3
  • 2001
  • Ingår i: Journal of Physical Chemistry B. - 1089-5647. ; 105:29, s. 6895-6906
  • Tidskriftsartikel (refereegranskat)abstract
    • Modeling and flow reactor experiments were used to study the kinetics of NO, storage/release on a Pt/BaO/Al2O3 model catalyst. The mechanism for this concept can be divided into four steps: (i) NO to NO2 oxidation on Pt, (ii) NO2 storage on BaO, (iii) NO, release, and (iv) NO, reduction to N2. In this paper, we have focused on the first three steps. From the NO oxidation study on Pt/Al2O3 compared to Pt/BaO/Al2O3, we observed that the presence of BaO decreases the formation of NO2. To test the importance of this step for effective storage, experiments were performed with a Pt/Al2O3 catalyst placed before the Pt/BaO/Al2O3 catalyst. This resulted in increased NO, storage for the combined system compared to the Pt/BaO/Al2O3 case. To resolve the second and third steps, an experimental investigation of NOx storage/release on BaO/Al2O3 was performed using only NO2 and N2 in the gas feed. We propose a kinetic model, which first includes adsorption of NO2, which oxidizes the surface, followed by nitrate formation. Finally, NO3-BaO-NO2, i.e., Ba(NO3)2, is formed. By using the kinetic parameters from the NO oxidation on Pt/BaO/Al2O3 and the NO, storage on BaO/Al2O3, a kinetic model was constructed to describe NO, storage/release experiments on Pt/BaO/Al2O3. However, the rate for NO, release was increased when Pt was present, and the kinetic model could not accurately describe this phenomenon. Therefore, the mechanism was modified by including a reversible surface spillover step of NO2 between Pt sites and BaO sites. Further, experiments with NO2 exposure followed by a temperature ramp with NO/N2 showed that the desorption behaviors from the BaO/Al2O3 and Pt/BaO/Al2O3 were significantly different, which further supports the spillover mechanism. Finally, the models describing NO, storage on BaO/Al2O3 and on Pt/BaO/Al2O3 were successfully validated with independent experiments.
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