421 research outputs found

    Exploring the potentials and tools of systems engineering and MBSE in machine design

    Get PDF
    Abstract. This thesis explores Systems Engineering (SE) and Model-Based Systems Engineering (MBSE) in the context of modern machine design. The primary objective is to understand how SE’s interdisciplinary and holistic methodologies, once rooted in the telephone industry, can be seamlessly adapted into the intricate realm of machine design. One of the key findings suggests that, despite the growing intrigue around MBSE as a novel approach to systems engineering, there is still a lack of concrete evidence to substantiate its effectiveness. However, certain studies have highlighted the strengths of MBSE, especially its tools’ capability for parametric and numerical analyses. These tools integrate smoothly with the initial phases of the design process, enabling continuous exploration of a system’s dynamic behavior. While MBSE is still emerging, it offers several apparent advantages, such as improved communication, increased consistency, and efficient use of both time and financial resources. With the knowledge that mechanical engineering these days means working with many different specialists from various fields, we can safely say that engineering machines like cars and planes fall into the realm of systems engineering. The primary methodology employed for data acquisition in this thesis was a literature review.Systeemitekniikan ja MBSE:n mahdollisuudet ja työkalut koneensuunnittelussa. TiivistelmĂ€. TĂ€mĂ€ opinnĂ€ytetyö tutkii Systeemitekniikan (SE) ja Mallipohjaisen Systeemitekniikan (MBSE) kĂ€sitteitĂ€ modernin koneensuunnittelun kontekstissa. PÀÀasiallinen tavoite on ymmĂ€rtÀÀ, miten SE:n monitieteelliset ja kokonaisvaltaiset menetelmĂ€t, jotka alun perin juontavat juurensa puhelinalaan, voivat saumattomasti soveltua monimutkaisen koneensuunnittelun maailmaan. Yksi keskeisistĂ€ havainnoista viittaa siihen, ettĂ€ vaikka MBSE herĂ€ttÀÀ kasvavaa kiinnostusta uutena lĂ€hestymistapana systeemitekniikkaan, sen tehokkuutta tukevasta konkreettisesta nĂ€ytöstĂ€ on edelleen niukasti saatavilla. Kuitenkin tietyt tutkimukset ovat korostaneet MBSE:n vahvuuksia, erityisesti sen työkalujen kykyĂ€ parametriseen ja numeeriseen analyysiin. NĂ€mĂ€ työkalut integroituvat saumattomasti suunnitteluprosessin alkuvaiheisiin, mahdollistaen jĂ€rjestelmĂ€n dynaamisen kĂ€yttĂ€ytymisen jatkuvan tutkimisen. Vaikka MBSE on edelleen kehittyvĂ€ alue, se tarjoaa useita selkeitĂ€ etuja, kuten parannetun kommunikaation, lisÀÀntyneen johdonmukaisuuden sekĂ€ ajan ja taloudellisten resurssien tehokkaamman hyödyntĂ€misen. Kun otetaan huomioon, ettĂ€ nykyaikainen koneensuunnittelu edellyttÀÀ usein yhteistyötĂ€ eri alojen erikoisasiantuntijoiden kanssa, voidaan perustellusti vĂ€ittÀÀ, ettĂ€ monimutkaisten koneiden, kuten autojen ja lentokoneiden, suunnittelu kuuluu systeemitekniikan piiriin. TĂ€mĂ€n opinnĂ€ytetyön tĂ€rkein tutkimusmenetelmĂ€ oli kirjallisuuskatsaus

    Guidelines for physical weed control research: flame weeding, weed harrowing and intra-row cultivation

    Get PDF
    A prerequisite for good research is the use of appropriate methodology. In order to aggregate sound research methodology, this paper presents some tentative guidelines for physical weed control research in general, and flame weeding, weed harrowing and intra-row cultivation in particular. Issues include the adjustment and use of mechanical weeders and other equipment, the recording of impact factors that affect weeding performance, methods to assess effectiveness, the layout of treatment plots, and the conceptual models underlying the experimental designs (e.g. factorial comparison, dose response). First of all, the research aims need to be clearly defined, an appropriate experimental design produced and statistical methods chosen accordingly. Suggestions on how to do this are given. For assessments, quantitative measures would be ideal, but as they require more resources, visual classification may in some cases be more feasible. The timing of assessment affects the results and their interpretation. When describing the weeds and crops, one should list the crops and the most abundantly present weed species involved, giving their density and growth stages at the time of treatment. The location of the experimental field, soil type, soil moisture and amount of fertilization should be given, as well as weather conditions at the time of treatment. The researcher should describe the weed control equipment and adjustments accurately, preferably according to the prevailing practice within the discipline. Things to record are e.g. gas pressure, burner properties, burner cover dimensions and LPG consumption in flame weeding; speed, angle of tines, number of passes and direction in weed harrowing. The authors hope this paper will increase comparability among experiments, help less experienced scientists to prevent mistakes and essential omissions, and foster the advance of knowledge on non-chemical weed management

    The gap between behavioral risk status and willingness to change behavior among healthcare professionals

    Get PDF
    Aims: This study explored behavioral health risk factors among healthcare professionals and investigated the at-risk persons' satisfaction with their health habits and ongoing change attempts. Methods: The study was based on a cross-sectional web-based survey directed at the nurses and physicians (N = 1233) in Finnish healthcare. Obesity, low physical activity, smoking, and risky alcohol drinking were used as behavioral health risk factors. Results: In all, 70% of the participants had at least one behavioral risk factor, and a significant number of at-risk persons were satisfied with their health habits and had no ongoing change process. Good self-rated health and good self-rated work ability were significantly associated with whether a participant had a behavioral health risk factor. Conclusion: Overall, unhealthy behaviors and a lack of ongoing change attempts were commonly observed among healthcare professionals. Work in healthcare is demanding, and healthy lifestyles can support coping. Thus, healthy lifestyle programs should also be targeted to healthcare professionals.Peer reviewe

    Factors associated with parental recognition of a child's overweight status - a cross sectional study

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Very few studies have evaluated the association between a child's lifestyle factors and their parent's ability to recognise the overweight status of their offspring. The aim of this study was to analyze the factors associated with a parent's ability to recognise their own offspring's overweight status.</p> <p>Methods</p> <p>125 overweight children out of all 1,278 school beginners in Northern Finland were enrolled.</p> <p>Weight and height were measured in health care clinics. Overweight status was defined by BMI according to internationally accepted criteria. A questionnaire to be filled in by parents was delivered by the school nurses. The parents were asked to evaluate their offspring's weight status. The child's eating habits and physical activity patterns were also enquired about. Factor groups of food and physical activity habits were formed by factor analysis. Binary logistic regression was performed using all variables associated with recognition of overweight status in univariate analyses. The significant risk factors in the final model are reported using odds ratios (ORs) and their 95% confidence intervals (CIs).</p> <p>Results</p> <p>Fifty-seven percent (69/120) of the parents of the overweight children considered their child as normal weight. Child's BMI was positively associated with parental recognition of overweight (OR 3.59, CI 1.8 to 7.0). Overweight boys were less likely to be recognised than overweight girls (OR 0.14, CI 0.033 to 0.58). Child's healthy diet (OR 0.22, CI 0.091 to 0.54) and high physical activity (OR 0.29, CI 0.11 to 0.79) were inversely related to parental recognition of overweight status.</p> <p>Conclusions</p> <p>Child's healthy eating habits and physical activity are inversely related to parental recognition of their offspring's overweight. These should be taken into account when planning prevention and treatment strategies for childhood obesity.</p

    Metabolomic Profiling of Statin Use and Genetic Inhibition of HMG-CoA Reductase

    Get PDF
    Background Statins are first-line therapy for cardiovascular disease prevention, but their systemic effects across lipoprotein subclasses, fatty acids, and circulating metabolites remain incompletely characterized. Objectives This study sought to determine the molecular effects of statin therapy on multiple metabolic pathways. Methods Metabolic profiles based on serum nuclear magnetic resonance metabolomics were quantified at 2 time points in 4 population-based cohorts from the United Kingdom and Finland (N = 5,590; 2.5 to 23.0 years of follow-up). Concentration changes in 80 lipid and metabolite measures during follow-up were compared between 716 individuals who started statin therapy and 4,874 persistent nonusers. To further understand the pharmacological effects of statins, we used Mendelian randomization to assess associations of a genetic variant known to mimic inhibition of HMG-CoA reductase (the intended drug target) with the same lipids and metabolites for 27,914 individuals from 8 population-based cohorts. Results Starting statin therapy was associated with numerous lipoprotein and fatty acid changes, including substantial lowering of remnant cholesterol (80% relative to low-density lipoprotein cholesterol [LDL-C]), but only modest lowering of triglycerides (25% relative to LDL-C). Among fatty acids, omega-6 levels decreased the most (68% relative to LDL-C); other fatty acids were only modestly affected. No robust changes were observed for circulating amino acids, ketones, or glycolysis-related metabolites. The intricate metabolic changes associated with statin use closely matched the association pattern with rs12916 in the HMGCR gene (R2 = 0.94, slope 1.00 ± 0.03). Conclusions Statin use leads to extensive lipid changes beyond LDL-C and appears efficacious for lowering remnant cholesterol. Metabolomic profiling, however, suggested minimal effects on amino acids. The results exemplify how detailed metabolic characterization of genetic proxies for drug targets can inform indications, pleiotropic effects, and pharmacological mechanisms

    Supernova Remnants and Star Formation in the Large Magellanic Cloud

    Full text link
    It has often been suggested that supernova remnants (SNRs) can trigger star formation. To investigate the relationship between SNRs and star formation, we have examined the known sample of 45 SNRs in the Large Magellanic Cloud to search for associated young stellar objects (YSOs) and molecular clouds. We find seven SNRs associated with both YSOs and molecular clouds, three SNRs associated with YSOs but not molecular clouds, and eight SNRs near molecular clouds but not associated with YSOs. Among the 10 SNRs associated with YSOs, the association between the YSOs and SNRs can be either rejected or cannot be convincingly established for eight cases. Only two SNRs have YSOs closely aligned along their rims; however, the time elapsed since the SNR began to interact with the YSOs' natal clouds is much shorter than the contraction timescales of the YSOs, and thus we do not see any evidence of SNR-triggered star formation in the LMC. The 15 SNRs that are near molecular clouds may trigger star formation in the future when the SNR shocks have slowed down to <45 km/s. We discuss how SNRs can alter the physical properties and abundances of YSOs.Comment: 24 pages, 5 figures, 1 table, Accepted for publication in the August 2010 edition of the Astronomical Journa

    A multiwavelength study of the star forming region IRAS 18544+0112

    Full text link
    This work aims at investigating the molecular and infrared components in the massive young stellar object (MYSO) candidate IRAS 18544+0112. The purpose is to determine the nature and the origin of this infrared source. To analyze the molecular gas towards IRAS 18544+0112, we have carried out observations in a 90" x 90" region around l = 34.69, b = -0.65, using the Atacama Submillimeter Telescope Experiment (ASTE) in the 12CO J=3-2, 13CO J=3-2, HCO+ J=4-3 and CS J=7-6 lines with an angular resolution of 22". The infrared emission in the area has been analyzed using 2MASS and Spitzer public data. From the molecular analysis, we find self-absorbed 12CO J=3-2 profiles, which are typical in star forming regions, but we do not find any evidence of outflow activity. Moreover, we do not detect either HCO+ J=4-3 or CS J=7-6 in the region, which are species normally enhanced in molecular outflows and high density envelopes. The 12CO J=3-2 emission profile suggests the presence of expanding gas in the region. The Spitzer images reveal that the infrared source has a conspicuous extended emission bright at 8 um with an evident shell-like morphology of ~ 1.5 arcmin in size (~ 1.4 pc at the proposed distance of 3 kpc) that encircles the 24 um emission. The non-detection of ionized gas related to IRAS 18544+0112, together with the fact that it is still embedded in a molecular clump suggest that IRAS 18544+0112, has not reached the UCHII region stage yet. Based on near infrared photometry we search for YSO candidates in the region and propos that 2MASS 18565878+0116233 is the infrared point source associated with IRAS 18544+0112. Finally, we suggest that the expansion of a larger nearby HII region, G034.8-0.7, might be related to the formation of IRAS 18544+0112.Comment: 14 pages, accepted for publication in A&A. Figures degraded to reduce file siz

    A molecular outflow evidencing star formation activity in the vicinity of the HII region G034.8-0.7 and the SNR W44

    Get PDF
    This work aims at investigating the molecular gas component in the vicinity of two young stellar object (YSO) candidates identified at the border of the HII region G034.8-0.7 that is evolving within a molecular cloud shocked by the SNR W44. The purpose is to explore signatures of star forming activity in this complex region. We performed a near and mid infrared study towards the border of the HII region G034.8-0.7 and observed a 90" X 90" region near 18h 56m 48s, +01d 18' 45" (J2000) using the Atacama Submillimeter Telescope Experiment (ASTE) in the 12CO J=3--2, 13CO J=3--2, HCO+ J=4--3 and CS J=7--6 lines with an angular resolution of 22". Based on the infrared study we propose that the source 2MASS 18564827+0118471 (IR1 in this work) is a YSO candidate. We discovered a bipolar 12CO outflow in the direction of the line of sight and a HCO+ clump towards IR1, confirming that it is a YSO. From the detection of the CS J=7--6 line we infer the presence of high density (>10^7 cm^-3) and warm (>60 K) gas towards IR1, probably belonging to the protostellar envelope where the YSO is forming. We investigated the possible genetic connection of IR1 with the SNR and the HII region. By comparing the dynamical time of the outflows and the age of the SNR W44, we conclude that the possibility of the SNR has triggered the formation of IR1 is unlikely. On the other hand, we suggest that the expansion of the HII region G034.8-0.7 is responsible for the formation of IR1 through the "collect and collapse" process.Comment: 19 pages, 14 figures. Figures degraded to reduce file size. Accepted 06/02/2009 for publication in A&

    A deep wide-field sub-mm survey of the Carina Nebula complex

    Full text link
    The Great Nebula in Carina is a superb location in which to study the physics of violent massive star-formation and the resulting feedback effects, including cloud dispersal and triggered star-formation. In order to reveal the cold dusty clouds in the Carina Nebula complex, we used the Large APEX Bolometer Camera LABOCA at the APEX telescope to map a 1.25 deg x 1.25 deg (= 50 x 50 pc^2) region at 870 micrometer. From a comparison to Halpha images we infer that about 6% of the 870 micrometer flux in the observed area is likely free-free emission from the HII region, while about 94% of the flux is very likely thermal dust emission. The total (dust + gas) mass of all clouds for which our map is sensitive is ~ 60 000 Msun, in good agreement with the mass of the compact clouds in this region derived from 13CO line observations. We generally find good agreement in the cloud morphology seen at 870 micrometer and the Spitzer 8 micrometer emission maps, but also identify a prominent infrared dark cloud. Finally, we construct a radiative transfer model for the Carina Nebula complex that reproduces the observed integrated spectral energy distribution reasonably well. Our analysis suggests a total gas + dust mass of about 200000 Msun in the investigated area; most of this material is in the form of molecular clouds, but a widely distributed component of (partly) atomic gas, containing up to ~ 50% of the total mass, may also be present. Currently, only some 10% of the gas is in sufficiently dense clouds to be immediately available for future star formation, but this fraction may increase with time owing to the ongoing compression of the strongly irradiated clouds and the expected shockwaves of the imminent supernova explosions.Comment: Accepted for publication in Astronomy & Astrophysics; high-quality pre-prints can be obtained from http://www.usm.uni-muenchen.de/people/preibisch/publications.htm
    • 

    corecore