| 1. |
- Björling, Marcus, et al.
(författare)
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The influence of DLC coating on EHL friction coefficient
- 2012
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Ingår i: Tribology letters. - : Springer Science and Business Media LLC. - 1023-8883 .- 1573-2711. ; 47:2, s. 285-294
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Tidskriftsartikel (refereegranskat)abstract
- High hardness, high elastic modulus, low friction characteristics, high wear and corrosion resistance, chemical inertness, and thermal stability are factors that make diamond-like carbon (DLC) coatings the subject of many studies. For the same reasons they also seem suitable for use in, amongst others, machine components and cutting tools. While most studies in the literature focus on the influence of coatings on wear and friction in boundary lubrication and pure sliding contacts, few studies can be found concerning rolling and sliding elastohydrodynamic lubrication (EHL) friction, especially in the mixed and full film regime. In this article tests are carried out in a Wedeven Associates Machine tribotester where an uncoated ball and disc pair is compared to the case of coated ball against uncoated disc, coated disc against uncoated ball, and coated disc against coated ball. The tests are conducted at two different temperatures and over a broad range of slide-to-roll ratios and entrainment speeds. The results are presented as friction maps as introduced in previous work (Björling et al. in J Eng Tribol 225(7):671, 2011). Furthermore a numerical simulation model is developed to investigate if there is a possibility that the hard, thin DLC coating is affecting the friction coefficient in an EHL contact due to thermal effects caused by the different thermal properties of the coating compared to the substrate. The experimental results show a reduction in friction coefficient in the full film regime when DLC-coated surfaces are used. The biggest reduction is found when both surfaces are coated, followed by the case when either ball or disc is coated. The thermal simulation model shows a substantial increase of the lubricant film temperature compared to uncoated surfaces when both surfaces are coated with DLC. The reduction in friction coefficient when coating either only the ball or the disc are almost the same, lower than when coating both the surfaces but still higher than the uncoated case. The findings above indicate that it is reasonable to conclude that thermal effects are a likely cause for the decrease in coefficient of friction when operating under full film conditions, and in the mixed lubrication regime when DLC-coated surfaces are used
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| 2. |
- Boart, Patrik, et al.
(författare)
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Enabling variation of manufacturing process parameters in early stages of product development
- 2006
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Ingår i: Proceedings of IMECE 2006. - : American Society of Mechanical Engineers. - 0791847675 ; , s. 1165-1173
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Konferensbidrag (refereegranskat)abstract
- Currently, mechanical design of aero engine structural components is defined by dimensioning of Design Parameters (DP's) to meet Functional Requirements (FR's). FR's are typically loads, geometrical interfaces and other boundary conditions. Parameters from downstream processes are seldom actually seen as DP's. This paper proposes that downstream process parameters are treated as DP's which calls for engineering methods that can define and evaluate these extended set of DP's.Using the proposed approach manufacturing process alternatives can be used as DP's in early stages of product development. Both the capability to quantitatively assess impact of varying manufacturing DP's, and the availability of these design methods are needed to succeed as an early phase design method. One bottleneck is the preparation time to define and generate these advanced simulation models.This paper presents how these manufacturing process simulations can be made available by automating the weld simulation preparation stages of the engineering work. The approach is based on a modular approach where the methods are defined with knowledge based engineering techniques-operating close to the CAD system.Each method can be reused and used independently of each other and adopted to new geometries. A key advantage is the extended applicability to new products, which comes with a new set of DP's.On a local level the lead time to generate such manufacturing simulation models is reduced with more than 99% allowing manufacturing process alternatives to be used as DP's in early stages of product development.
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| 3. |
- Byholm, Patrik, et al.
(författare)
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Paternal transmission of migration knowledge in a long-distance bird migrant
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- While advances in biologging have revealed many spectacular animal migrations, it remains poorly understood how young animals learn to migrate. Even in social species, it is unclear how migratory skills are transmitted from one generation to another and what implications this may have. Here we show that in Caspian terns Hydroprogne caspia family groups, genetic and foster male parents carry the main responsibility for migrating with young. During migration, young birds stayed close to an adult at all times, with the bond dissipating on the wintering grounds. Solo-migrating adults migrated faster than did adults accompanying young. Four young that lost contact with their parent at an early stage of migration all died. During their first solo migration, subadult terns remained faithful to routes they took with their parents as young. Our results provide evidence for cultural inheritance of migration knowledge in a long-distance bird migrant and show that sex-biased (allo)parental care en route shapes migration through social learning.
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| 4. |
- Cha, Matthew, et al.
(författare)
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Influence of pad compliance on nonlinear dynamic characteristics of tilting pad journal bearings
- 2013
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 57, s. 46-53
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Tidskriftsartikel (refereegranskat)abstract
- The effect of pad compliance on the dynamic response of tilting pad journal bearings is investigated. Pad compliance is varied by changing pivot geometry and Young's modulus of pad backing and pad liner. Two pad support configurations are considered: one that allows only circumferential tilt and another one that allows both circumferential and axial tilts. Journal orbits, oil film pressure and oil film thickness are compared and discussed. It is shown that higher pad backing compliance significantly increases the journal orbit size and results in an increase in oil film pressure while oil film thickness is decreased. With a compliant liner, oil film pressure is decreased while oil film thickness is increased. Tapers at the pad edges are essential to increase the global minimum oil film thickness in compliant liner bearings.
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| 5. |
- da Silva, Marisa, et al.
(författare)
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Cohort profile : The Obesity and Disease Development Sweden (ODDS) study, a pooled cohort
- 2024
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Ingår i: BMJ Open. - 2044-6055. ; 14:7
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The Obesity and Disease Development Sweden (ODDS) study was designed to create a large cohort to study body mass index (BMI), waist circumference (WC) and changes in weight and WC, in relation to morbidity and mortality.PARTICIPANTS: ODDS includes 4 295 859 individuals, 2 165 048 men and 2 130 811 women, in Swedish cohorts and national registers with information on weight assessed once (2 555 098 individuals) or more (1 740 761 individuals), in total constituting 7 733 901 weight assessments at the age of 17-103 years in 1963-2020 (recalled weight as of 1911). Information on WC is available in 152 089 men and 212 658 women, out of whom 108 795 have repeated information on WC (in total 512 273 assessments). Information on morbidity and mortality was retrieved from national registers, with follow-up until the end of 2019-2021, varying between the registers.FINDINGS TO DATE: Among all weight assessments (of which 85% are objectively measured), the median year, age and BMI (IQR) is 1985 (1977-1994) in men and 2001 (1991-2010) in women, age 19 (18-40) years in men and 30 (26-36) years in women and BMI 22.9 (20.9-25.4) kg/m 2 in men and 23.2 (21.2-26.1) kg/m 2 in women. Normal weight (BMI 18.5-24.9 kg/m 2) is present in 67% of assessments in men and 64% in women and obesity (BMI≥30 kg/m 2) in 5% of assessments in men and 10% in women. The median (IQR) follow-up time from the first objectively measured or self-reported current weight assessment until emigration, death or end of follow-up is 31.4 (21.8-40.8) years in men and 19.6 (9.3-29.0) years in women. During follow-up, 283 244 men and 123 457 women died. FUTURE PLANS: The large sample size and long follow-up of the ODDS Study will provide robust results on anthropometric measures in relation to risk of common diseases and causes of deaths, and novel findings in subgroups and rarer outcomes.
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| 6. |
- Ekedahl, Henrik, et al.
(författare)
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Low-grade inflammation in survivors of childhood cancer and testicular cancer and its association with hypogonadism and metabolic risk factors
- 2022
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Ingår i: BMC Cancer. - : Springer Science and Business Media LLC. - 1471-2407. ; 22, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In childhood (CCS) and testicular cancer (TCS) survivors, low-grade inflammation may represent a link between testosterone deficiency (hypogonadism) and risk of metabolic syndrome. We aimed to study levels of inflammatory markers in CCS and TCS and the association with hypogonadism and future cardio-metabolic risk factors.METHODS: Serum levels of inflammatory markers and testosterone were analyzed in CCS (n = 90), and TCS (n = 64, median time from diagnosis: 20 and 2.0 years, respectively), and in controls (n = 44). Differences in levels between patients and controls were calculated using univariate analysis of variance. T-test and logistic regression were applied to compare levels of cardio-metabolic risk factors and odds ratio (OR) of hypogonadism and metabolic syndrome in low and high inflammatory marker groups after 4-12 years of follow up. Adjustment for age, smoking, and active cancer was made.RESULTS: TCS and CCS, as compared to controls, had 1.44 (95%CI 1.06-1.96) and 1.25 (95 CI 1.02-1.53) times higher levels of IL-8, respectively. High IL-6 levels were associated with hypogonadism at baseline (OR 2.83, 95%CI 1.25-6.43) and the association was stronger for high IL-6 combined with low IL-10 levels (OR 3.10, 95%CI 1.37-7.01). High IL-6 levels were also associated with higher BMI, waist circumference, insulin, and HbA1c at follow up. High TNF-α was associated with higher diastolic blood pressure. No individual inflammatory marker was significantly associated with risk of metabolic syndrome at follow up. High IL-6 combined with low IL-10 levels were associated with risk of metabolic syndrome (OR 3.83, 95%CI 1.07-13.75), however not statistically significantly after adjustment.CONCLUSION: TCS and CCS present with low-grade inflammation. High IL-6 levels were associated with hypogonadism and cardio-metabolic risk factors. Low IL-10 levels might reinforce the IL-6 mediated risk of developing metabolic syndrome.
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| 7. |
- Eliasson, Lovisa, et al.
(författare)
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Infrared Decontamination of Oregano: Effects on Bacillus cereus Spores, Water Activity, Color, and Volatile Compounds
- 2014
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Ingår i: Journal of Food Science. - : Wiley. - 0022-1147 .- 1750-3841. ; 79:12, s. E2447-E2455
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Tidskriftsartikel (refereegranskat)abstract
- Infrared (IR) heating, a novel technology for decontaminating oregano, was evaluated by investigating the reduction of inoculated Bacillus cereus spores and the effect on water activity (aw), color, and headspace volatile compounds after exposure to IR treatment. Conditioned oregano (aw 0.88) was IR-treated in a closed heating unit at 90 and 100 °C for holding times of 2 and 10 min, respectively. The most successful reduction in B. cereus spore numbers (5.6 log units) was achieved after a holding time of 10 min at 90 °C, while treatment at 100 °C for the same time resulted in a lower reduction efficiency (4.7 log units). The lower reduction at 100 °C was probably due to a reduced aw (aw 0.76) during IR treatment or possibly to the alteration or loss of volatile compounds possessing antimicrobial properties. The green color of oregano was only slightly affected, while the composition of volatile compounds was clearly altered by IR heating. However, two of the key aroma compounds, carvacrol and thymol, were only slightly affected, compared to the effect on the other studied compounds, indicating that the typical oregano aroma can likely be preserved. In conclusion, IR heating shows potential for the successful decontamination of oregano without severe alteration of its color or the key aroma compounds, carvacrol and thymol. Practical Application: This study investigated the potential of infrared heating as a technology for decontaminating oregano. The study outcome contributes to the development of new decontamination solutions to improve the sensory and microbial quality of herbs and spices.
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| 8. |
- Finnilä, Mikko A J, et al.
(författare)
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Mineral Crystal Thickness in Calcified Cartilage and Subchondral Bone in Healthy and Osteoarthritic Human Knees
- 2022
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Ingår i: Journal of Bone and Mineral Research. - : Wiley. - 1523-4681 .- 0884-0431. ; 37:9, s. 1700-1710
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Tidskriftsartikel (refereegranskat)abstract
- Osteoarthritis (OA) is the most common joint disease, where articular cartilage degradation is often accompanied with sclerosis of the subchondral bone. However, the association between OA and tissue mineralization at the nanostructural level is currently not understood. In particular, it is technically challenging to study calcified cartilage, where relevant but poorly understood pathological processes such as tidemark multiplication and advancement occur. Here, we used state-of-the-art microfocus small-angle X-ray scattering with a 5-μm spatial resolution to determine the size and organization of the mineral crystals at the nanostructural level in human subchondral bone and calcified cartilage. Specimens with a wide spectrum of OA severities were acquired from both medial and lateral compartments of medial compartment knee OA patients (n = 15) and cadaver knees (n = 10). Opposing the common notion, we found that calcified cartilage has thicker and more mutually aligned mineral crystals than adjoining bone. In addition, we, for the first time, identified a well-defined layer of calcified cartilage associated with pathological tidemark multiplication, containing 0.32 nm thicker crystals compared to the rest of calcified cartilage. Finally, we found 0.2 nm thicker mineral crystals in both tissues of the lateral compartment in OA compared with healthy knees, indicating a loading-related disease process because the lateral compartment is typically less loaded in medial compartment knee OA. In summary, we report novel changes in mineral crystal thickness during OA. Our data suggest that unloading in the knee might be involved with the growth of mineral crystals, which is especially evident in the calcified cartilage.
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| 9. |
- Gerth, Julia, et al.
(författare)
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Assessing the hardness and residual stress at the very edge of a TiAlN coated cutting insert
- 2024
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Ingår i: Surface and coatings technology. - : Elsevier. - 0257-8972.
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Tidskriftsartikel (refereegranskat)abstract
- A method for determining residual stresses through nanoindentation has been used in order to evaluate the local residual stress in a PVD Ti0.5Al0.5N coating. The influence of residual stress on the measured hardness is obtained by comparing the hardness of as deposited, residually stressed, coating and stress relieved pillars made in the very same coating. The technique offers high lateral resolution, and it can be applied on complex geometries where conventional stress measurements fall short. In this work, the method proved useful for estimating the residual stress at such a complex geometry as a sharp cutting edge. Edges with two different radii were analysed and it was concluded that the nominal residual compressive stress given to a coating can locally, on the very cutting edge, become significantly reduced by elastic relaxation .This effects the cohesion of the coating at that position which, together with the lift-off stress generated at the edge, make the coating in that region especially vulnerable to damage. The experimental results correlated very well with finite element simulations of the residual stress state around cutting edges with the same geometries.
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| 10. |
- Gren, Anna, et al.
(författare)
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Energianvändning i bebyggelse - boendes och aktörers val av teknik : Antologi från forskarskolan program energisystem
- 2007
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Energianvändning är grunden för välstånd och samhällsutveckling. Men vårt sätt att använda energi orsakar miljöpåverkan som i värsta fall kan rasera grunden inte bara för välstånd och samhällsutveckling utan också ytterst för existensen av allt liv på jorden. Vilka är möjligheterna att förändra energianvändningen så att den blir miljömässigt, socialt och ekonomiskt uthållig? Detta är en process som i mycket måste utgå från vad människor gör i sin vardag, i yrkeslivet och som konsumenter och användare av energi i olika aktiviteter. Antologin behandlar energianvändning i bebyggelse utifrån de valmöjligheter som olika aktörer – professionella och hushåll – har när det gäller att bygga och bo i energisnåla hus, att installera och bruka teknik som är energieffektiv och som utnyttjar förnybar energi, till exempel solenergi.Boken vänder sig till alla som har professionellt intresse för frågor om energianvändning i bebyggelse som till exempel aktörer som planerar, bygger och förvaltar byggnader. Den vänder sig också till hushållen, som bor i husen och använder energi. Boken vill vidare visa hur teknisk och samhällsvetenskaplig forskning kan kombineras för att nå ny kunskap om processer i så komplexa sociotekniska system som moderna energisystem.
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