| 1. |
- Marell, Agneta, 1964-, et al.
(författare)
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Intelligent transportation system and traffic safety : – drivers perception and acceptance of electronic speed checkers
- 1999
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Ingår i: Transportation Research Part C. - : Elsevier. - 0968-090X .- 1879-2359. ; 7:2-3, s. 131-147
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Tidskriftsartikel (refereegranskat)abstract
- Intelligent Transportation System (ITS) can play an important role in reducing risks and increasing traffic safety. Discussion as to whether a technological approach or a behavioral approach is the right way to achieve a safer traffic environment forms a point of departure for this paper. On the one hand, there are the technicians who emphasize technology as the way towards safer traffic. Behaviorists, on the other hand, view the drivers’ behavior as fundamental and argue that education and incentive-oriented policies are essential in order to influence the driver and therefore increase traffic safety. Independent of the approach advocated a successful outcome of either a technological improvement, or an information campaign, has to be based on a high level of acceptance among potential users. In order to increase traffic safety, it is therefore essential to recognize driver motivation and attitudes. In this paper we focus on drivers’ attitudes towards risk, traffic safety and safety measures. A study of drivers’ attitudes and acceptance of an electronic device for speed checking (which the drivers tested for nine months) indicated a high acceptance level. The drivers perceived that they had both become more aware of traffic regulations and behaved in accordance with safety regulations.
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| 2. |
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| 3. |
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| 4. |
- Jonsson, Lars, et al.
(författare)
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Controlled topography production - True 3D simulation and experiment
- 1995
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Ingår i: Vacuum. - 0042-207X .- 1879-2715. ; 46, s. 971-975
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Tidskriftsartikel (refereegranskat)abstract
- A true 3D computer program, named DINESE, has been developed to simulate the evolution of real 3D structures during erosion and deposition. It is based on the generalized Huygens reconstruction formalism of surface evolution and can predict the evolution of any surface of the form z = f(x,y) resulting from any erosion or deposition process. True 3D computer simulations of a number of cases are presented and compared with experiment. The powers of the simulation method are further demonstrated by a series of sequential predictive simulations resulting in a desired topography which is then verified experimentally under the same sequence of conditions. Specifically, the evolution of different Si3N4 structures during ion beam etching with Ar ions under different erosion conditions has been studied both numerically and experimentally.
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| 5. |
- Nordén, T, et al.
(författare)
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Mammographic screening for breast cancer : What cancers do we find?
- 1997
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Ingår i: European Journal of Cancer. - : Elsevier. - 0959-8049 .- 1879-0852. ; 33:4, s. 624-628
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare lymph node involvement of breast cancer cases detected at mammography screening with clinically-detected cases. During a 3-year period, 273 primary breast cancers were detected in a population-based screening programme, and 149 primary breast cancers were diagnosed clinically. Lymph node involvement was evaluated in univariate and multivariate logistic regression models correcting for tumour size, histological grade, steroid receptor status and DNA-ploidy. Patients with screen-detected cancers had a low relative risk of having lymph node metastases (univariate, OR = 0.31; 95% confidence interval = 0.19-0.52). In the multivariate logistic regression model, the relative risk was halved (OR = 0.47; 0.28-0.78). The reduced risk was more pronounced for women younger than 50 years of age compared to older women. The risk for screen-detected cases of having lymph node metastases at diagnosis was statistically significantly lower than for clinically-detected cases. The marked reduction, even when correcting for tumour size, makes it less likely that factors such as detection of clinically innocent tumours, length bias sampling or clinical symptoms related to axillary metastases can explain the whole difference. The results indicate at least part of the effect may be explained by tumour progression in the late preclinical detectable phase.
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| 6. |
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| 7. |
- Wiman, Bo, et al.
(författare)
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Perspectives on Aerosol Deposition to Natural Surfaces: interactions between aerosol residence times, removal processes, the biosphere and global environmental change
- 1990
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Ingår i: Journal of Aerosol Science. - 0021-8502 .- 1879-1964. ; 21:3, s. 313-338
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Tidskriftsartikel (refereegranskat)abstract
- This paper summarizes the state-of-the-art and the research needs in the areas of aerosol residence-time assessments, deposition modelling, and understanding of aerosols in biogeochemistry. Research needs are emphasized from a systems perspective of global environmental change. Although fundamental quantitative knowledge is lacking, some qualitative linkages between source strengths, residence times, removal processes and the biosphere can be identified. It turns out that not only are the respective areas as such challenged by new problems, superimposed on the fairly well established conventional ones, but these areas also face mutually operating sets of feedbacks between residence times and sink/source characteristics of ecological systems subject to stress. To evaluate the sensitivity of these feedback loops, and to assess whether they are negative (stabilizing interactions) or positive (destabilizing) are important and potentially urgent tasks. Such studies should focus on a common goal, such as developing empirical and theoretical understanding of aerosol resuspension, transport and deposition for application in large-scale circulation models. A basic link in such advancements is that structural change of vegetated surfaces of the biosphere caused by deposition itself, and by changing land-use and climate, be understood and assessed. This article was initiated in connection with the Workshop on Aerosol Deposition to Natural Surfaces, Lund, Sweden, 2 September, 1988; conducted during the European Aerosol Conference (see J. Aerosol Sci. 19, 775–776). The authors wish to express their thanks to the workshop participants (list available from the workshop coordinators).
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| 8. |
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| 9. |
- Cederfelt, Sven Inge, et al.
(författare)
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On the charge limit for crystallizing particles
- 1990
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Ingår i: Journal of Aerosol Science. - 0021-8502. ; 21:SUPPL. 1, s. 127-130
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Tidskriftsartikel (refereegranskat)abstract
- The electrical charge limit of crystallizing sodium chloride droplets has been studied. Moderately charged sodium chloride solution droplets were dried to highly charged residual particles. The charge limit was found to be near the Rayleigh charge limit for saturated sodium chloride droplets of the same size as the residual particle. The charge loss was not found to affect the particle size to a detectable degree.
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| 10. |
- Deppert, Knut, et al.
(författare)
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Size-selected nanocrystals of III-V semiconductor materials by the aerotaxy method
- 1998
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Ingår i: Journal of Aerosol Science. - 0021-8502. ; 29:5-6, s. 737-748
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a fabrication route to produce size-selected III-V semiconductor nanocrystals via a simple, reliable, and efficient aerosol route. Since this approach includes the reaction of aerosol particles and a self-organized growth of a new compound, all in the aerosol phase, we call this process aerotaxy. Size-selected nanocrystals of different III-V compounds in a diameter range below 20 nm were fabricated using this method. Through the reaction of arsine with gallium droplets or of phosphine with indium droplets, GaAs and InP clusters were formed. Our approach opens the possibility to produce contamination-free and size-selected nanocrystals of compound semiconductor materials with considerable freedom in composition and size.
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| 11. |
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| 12. |
- Gudmundsson, Anders, et al.
(författare)
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Characteristics of Mult-Nozzle Impactors with 50 µm Laser-Drilled Nozzles
- 1995
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Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502. ; 26:6, s. 915-931
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to provide data for the design of multi-nozzle impactors giving size-fractionated samples for X-ray emission analysis and for size-distribution determinations of the α-particle activity from aerosol-particle-attached radon progenies. Different multi-nozzle impactors with laser-drilled 50–60 μm diameter nozzles designed for a cut-off diameter of about 0.05 μm were experimentally characterised. The nozzles were placed in a spiral pattern within a circle of 8.0 mm diameter. The nozzle-plate porosities were 0.013 and 0.050 (porosity = total cross-sectional area of nozzles divided by nozzle-plate area). The results show that laser-drilled nozzles can be used for multi-nozzle impactors and that the maximum nozzle-plate porosity is limited by the cross flow. The collection characteristics of the multi-nozzle impactors studied here were found to be more dependent on the Reynolds number and the S/W ratio [the ratio of the distance (S) between nozzle plate and impaction plate to the nozzle diameter (W)], than what has been shown for single-nozzle impactors. The S/W ratio and the Reynolds number must be considered if high size resolution is to be achieved.
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| 13. |
- Gudmundsson, Anders, et al.
(författare)
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Deposition of Airborne Particles onto the Human Eye - Wind Tunnel Studies of the Deposition Velocity onto the Eyes of a Mannequin
- 1997
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Ingår i: Journal of Aerosol Science. - 0021-8502. ; 28:6, s. 1085-1100
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Tidskriftsartikel (refereegranskat)abstract
- Abstract In the field of occupational hygiene much consideration is devoted to the uptake through the human airways, but there are also reports of irritations, complaints and hazards or potential hazards due to particle deposition onto the eyes. There is a need for data regarding the dependence of the deposition rate on particle size and environmental parameters in order to formulate sampling criteria and to find dose-response relations. The deposition of airborne particles onto the human eye was studied by making use of a dummy, the eyes of which were covered with pieces of transparent sticky foil. The dummy was exposed to airborne particles in a wind tunnel. The airborne particle concentration was simultaneously measured using an Aerodynamic Particle Sizer (APS, TSI Inc., U.S.A.). The deposited particles were counted using an optical microscope equipped with an image analyser. For the particle sizes (2–30 μm), wind velocities (0.5 and 1.0 m s−1), wind directions (0, 90 and 180°) and turbulence intensities (1.3 and 19%) employed in this study, deposition velocities onto the eyes were determined to be in the range of 0.001–1 cm s−1.
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| 14. |
- Gudmundsson, Anders, et al.
(författare)
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Determination of Particle Deposition Velocity onto the Human Eye
- 1992
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Ingår i: Journal of Aerosol Science. - 0021-8502. ; Single Page Abstracts, s. 295-295
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Tidskriftsartikel (refereegranskat)abstract
- Studies have been performed on the deposition of airborne particles onto the human eye. A mannequin with sticky transparent foils covering its eyes is exposed to particles of fused alumina in a wind tunnel. The size distribution of the airborne particle is simultaneously measured with an Aerodynamic Particle Sizer. The particles on the foils are counted and measured with an optical microscope connected to an image analyzer. Deposition velocities have been determined for particles with aerodynamic diameters over the range 2 to 32 μm with different orientations of the mannequin to the wind direction at an air velocity of 1 m/s. The deposition velocity is in the order of 0.01 cm/s.
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| 15. |
- Gudmundsson, Anders, et al.
(författare)
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Particle Size Calibration between the Aerodynamic Particle Sizer and Optical Microscope for Wind Tunnel Studies with Particles of Fused Alumina
- 1991
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Ingår i: Journal of Aerosol Science. - 0021-8502. ; 22 S1, s. 347-350
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Tidskriftsartikel (refereegranskat)abstract
- Abstract When studying the deposition of particles in wind tunnel experiments, we measure theairborne particles with an Aerodynamic Particle Sizer (APS). The deposited particles are examined with an optical microscope connected to an image analyzer. Calibration between the APS and the optical microscope determinations of particle size has been performed for particles of fused alumina. The particle size calibration procedure is performed by comparing the 50% cutoff sizes, determined with APS and optical microscopy measurements, for different single-stage impactors.
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| 16. |
- Martinsson, Bengt G.
(författare)
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Physical basis for a droplet aerosol analysing method
- 1996
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Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502. ; 27:7, s. 997-1013
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Tidskriftsartikel (refereegranskat)abstract
- A technique for the characterisation of droplet aerosols is presented and theoretically evaluated. The system, which finds applications for example in the experimental study of cloud formation and cloud water chemistry, relies on a four-step process. The droplet aerosol is electrically charged in a unipolar charging unit, followed by diffusion drying of the droplets, resulting in charged particles consisting of non-volatile matter (droplet residues). In the third step, the residual particles are classified by electrostatic spectrometry, and in the final step the residual particles are detected, collected or further characterised. The basic function in respect of the charging process and the particle interaction with water vapour is demonstrated by model calculations, which show that droplets which are activated in a thermodynamical sense can be separated from unactivated droplets. Different strategies for the application of the system are briefly outlined. By measuring two parameters, associated droplet size and residual particle size can be determined. Results from the first field measurement campaign of the resulting instrument are also briefly presented.
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| 17. |
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| 18. |
- Wiedensohler, A., et al.
(författare)
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A novel unipolar charger for ultrafine aerosol particles with minimal particle losses
- 1994
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Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502. ; 25:4, s. 639-649
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Tidskriftsartikel (refereegranskat)abstract
- A unipolar diffusion charger with minimal particle losses in the ultrafine size range has been developed. This charger uses two radioactive α-sources to produce ions which are drawn into the charging region by an alternating electric field. The aerosol flow in the centre of the charging region is surrounded by a particle-free sheath air flow to prevent particle losses. Charged aerosol particles move in a "zigzag" manner in the charging channel under the influence of the alternating electric field. Positive gas ions, with higher electrical mobilities than ultrafine aerosol particles, homogeneously fill the entire charging region. Here, the aerosol becomes unipolarly charged. The charging efficiency is strongly dependent on the residence time of the particles in the ion cloud. The ion current was measured in the charging region to determine the ion concentration. The residence time of the particles in the ion cloud was calculated for each stream line of the aerosol flow. The losses of ultrafine particles in the charger were experimentally determined. The unipolar charge distribution was measured and calculated by integrating the theoretical charge distribution over all stream lines of the aerosol flow.
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| 19. |
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| 20. |
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| 21. |
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| 22. |
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| 23. |
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| 24. |
- Lastow, Orest, et al.
(författare)
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FiFi: Simulation of Dendrite Formation of Aerosol Particles on a Single Fibre
- 1992
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Ingår i: Journal of Aerosol Science. - 0021-8502. ; 23:S1, s. 105-108
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Tidskriftsartikel (refereegranskat)abstract
- A personal computer program, FiFi, that makes a real-time, two-dimensional simulation of the dynamic deposition process of particles on a single fibre, has been developed. The formation of dendrites and the particle transport as a function of different parameters are simulated. The trajectory of a spherical particle as a function of external forces and diffusion is calculated by integration and the particle moves across the display until it is captured or passes the fibre. The particles are captured directly on the fibre or on previously captured particles and form dendrites. A particle is characterised by five basic parameters which can be changed in various ways. The size and charge of the fibre are also parameters. At this state the flow around the fibre is described by either of three different air flow models, and four different electric fields can be simulated. The efficiency of any fibre-dendrite geometry can be calculated.
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| 25. |
- Schneider, Thomas, et al.
(författare)
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A Semiempirical model for Particle Deposition onto Facial Skin and Eyes. Role of Air Currents and Electric Fields
- 1994
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Ingår i: Journal of Aerosol Science. - 0021-8502. ; 25:3, s. 583-593
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Tidskriftsartikel (refereegranskat)abstract
- A semiempirical model has been developed for deposition velocity of particles on the forehead and eyes. It is based on published results of wind tunnel studies of deposition of 2-32 μm airborne particles onto the forehead and realistically-shaped eyes of a manikin. The effects of electric fields and particle charges were included in the model on a purely theoretical basis. The model was used to calculate the combined effects of air currents and electric fields, and it was found that electric fields and particle charges are major determinants for deposition of particles approximately 1 μm in diameter, and air turbulence likely to occur in ventilated rooms is a major determinant for particles larger than 10 μm. The model predicts that deposition of particles from typical indoor environments will be enhanced for persons exposed to electric fields, irrespective of the direction of the field. For a complete characterization, particle concentration, size distribution, mean air velocity, direction and turbulence intensity, electric fields and particle charge distribution should be known. For investigators of exposure to airborne particles and its relation to the office eye syndrome, the model can be used for identifying those parameters which are key for given conditions, thus simplifying the description of exposure.
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| 26. |
- Spanne, Mårten, et al.
(författare)
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Characteristics of Particle Emissions at Paint Manufacturing
- 1996
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Ingår i: Journal of Aerosol Science. - 0021-8502. ; 27 S1, s. 437-438
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Tidskriftsartikel (refereegranskat)abstract
- The handling of pigments and powders in paint manufacturing cause emissions of airborne particles. A great variety of substances occur. Previous studies (Bohgard et al., 1994) of simulations of pouring of pigments, which occur in small scale weighing procedures, showed typically bimodal size distribution including a sub-micron and a super-micron mode.The objective of the study was to get detailed knowledge on the relation between different source processes (depending on production technology, equipment and the manual handling routines) and aerosol characteristics.Super-micron particles were continuously measured with a time-of-flight instrument (Aerodynamic Particle Sizer, APS TSI Inc.) and sub-micron particles with an electric mobility spectrometer (Scanning Mobility Particle Sizer, SMPS TSI Inc.). In addition filter sampling techniques for standardised work-place sampling (so-called total dust filter cassettes, a cyclone sampler for respirable dust and IOM-samplers for inhalable dust) have been used for idealised exposure/area measurements using a rotating mannequin as a carrier of these samplers. The filters were analysed gravimetrically and with Particle Induced X-ray Emission Analysis. The aerosols were measured during manufacturing of batches of paint. Sources and source mechanisms, as pouring pigments from bags, disposal of packages, mixing of powders and pigments and suspected re-suspension sources, were documented simultaneously with the performance of the measurements.Figure 1 shows examples of size distributions obtained with the APS and SMPS. The size distributions have essentially bimodal shapes with median diameters of 0.05 -0.4 [mu ]m and of 2-5 [mu ]m respectively. Rapid variation in concentration occurs.Preliminary results show that several sources occur. Irregular activities and events as disposal of package material, cleaning, leakage from conveyor tubes and re-suspension due to wind velocities from open gates and moving vehicles significantly contribute to the particle concentrations.Filter sampling with the samplers mounted on a mannequin torso, rotating 360 degrees forth and back, is advantageous by giving idealised measures on exposure. Samplers mounted on equal horizontal level will have equal sampling location integrated over time. Furthermore, the sampling procedure emulate sampling in accordance with sampling conventions. Inlet characteristics of samplers mounted on a body differ from characteristics of free-hanging samplers (Vincent, 1989). Higher estimated mass concentrations were obtained with the IOM-samplers for inhalable dust than with the 37 mm open-face [ldquo ]total dust[rdquo ] cassettes.Figure omitted
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| 27. |
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| 28. |
- Malmström, P U, et al.
(författare)
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Increasing survival of patients with urinary bladder cancer : A nationwide study in Sweden 1960-1986
- 1993
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Ingår i: European Journal of Cancer. - : Elsevier. - 0959-8049 .- 1879-0852. ; 29A:13, s. 1868-1872
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Tidskriftsartikel (refereegranskat)abstract
- Survival rates were analysed in 29,055 patients with urinary bladder cancer diagnosed in Sweden from 1960 to 1986 and followed up until 1987. The 2-, 5- and 10-year relative survival rates were 79, 70 and 64% for men and 75, 68 and 63% for women, respectively. Patients with a history of bladder cancer for at least 15 years ran a negligible risk of dying from their disease. Prognosis was consistently better in younger than in older patients; below 50 years of age the 5-year relative survival rate was 90%, as compared with 60% in patients aged 70-79 years. Patients diagnosed between 1960 and 1964 had a 60% 5-year relative survival, as compared to 71% in those diagnosed between 1980 and 1984. Multivariate analyses further confirmed that age but not sex is an important prognostic factor in bladder cancer and, further, that a substantial improvement in survival rates took place during the 1960-1986 period. Compared with 1960-1964 the risk of dying of bladder cancer within 5 years in patients diagnosed between 1980 and 1984 was 51% lower in men [relative risk (RR) = 0.49; 95% confidence interval (C.I.) 0.42-0.57] and 44% lower in women (RR = 0.56; 95% C.I. 0.45-0.70).
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| 29. |
- Eriksson, Anders, 1953-
(författare)
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Structural instability analyses based on generalised path-following
- 1998
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Ingår i: Computer Methods in Applied Mechanics and Engineering. - 0045-7825 .- 1879-2138. ; 156:1-4, s. 45-74
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes how quasi-static, conservative instability problems can be completely described, using generalised path-following procedures for augmented equilibrium formulations. In particular, methods for treatment of compound critical states are discussed. The numerical methods are seen as extensions to common equilibrium path methods, allowing the solution of subsets of equilibrium states, also fulfilling auxiliary relations, e.g. criticality. These formulations are in general used to describe the parameter dependence in structural response, in instability analyses and in optimisation. The paper describes the general setting of these generalised equilibrium problems, and discusses some details in their numerical treatment. Emphasis is given to the evaluation of path tangent vectors, in the presence of critical eigenvectors for the structural tangential stiffness matrix. Also, the isolation of special states, i.e. vanishing variables, turning points and exchanges of stability, is discussed. Numerical examples are used to show the possibilities and properties of the obtained solution paths, together with some aspects of the numerical procedures.
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| 30. |
- Bishop, D. M., et al.
(författare)
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Effects of vibration on the polarizability and the first and second hyperpolarizabilities of HF, HCl, and HBr
- 1999
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 111:7, s. 3042-3050
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Tidskriftsartikel (refereegranskat)abstract
- We report calculations, using electron uncorrelated and correlated wave functions, of the electronic and vibrational properties which pertain to certain nonlinear optical properties for HF, HCl, and HBr. Our main focus is on vibrational effects (zero-point-vibrational averaging and pure vibration). Analysis of the results obtained at various levels of approximation indicates that first-order perturbation theory is generally adequate for finding the zero-point-vibrational-averaging corrections for these molecules and that complete second-order perturbation theory nearly always gives reliable results for the pure vibrational corrections. Attention is drawn to some differences with previously published results for these properties. © 1999 American Institute of Physics.
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| 31. |
- Pacoste, C., et al.
(författare)
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Beam elements in instability problems
- 1997
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Ingår i: Computer Methods in Applied Mechanics and Engineering. - 0045-7825 .- 1879-2138. ; 144:1-2, s. 163-197
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the formulation of beam elements for the numerical analysis of instability phenomena in frame-type structures. Total versus co-rotational approaches are discussed comparatively, for both two-dimensional and three-dimensional problems, and the similarities between the two types are outlined. In the context of 3D beam elements, special attention is given to the parameterisation of the orthogonal transformation used to define the rotational field of the beam. The technique advocated in the paper is based on the so-called rotational vector. This leads to symmetric stiffness matrices and avoids the need for special updating procedures for the rotational variables. A set of test problems, for which the critical behaviour is governed by fold, cusp and butterfly catastrophes, is used to assess the performances of the considered element types. It is shown that analytically verified identities in element formulation, also hold in numerical application. The examples also show how complex instability behaviour can be reproduced by all elements, where sufficient accuracy is introduced into the kinematic expressions. The analytical derivation of element expressions, with symbolic manipulations from stated basic assumptions, is consistently used in the paper.
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