16 research outputs found
Two-stage optimization method for efficient power converter design including light load operation
Power converter efficiency is always a hot topic for switch mode power supplies. Nowadays, high efficiency is required over a wide load range, e.g., 20%, 50% and 100% load. Computer-aided design optimization is developed in this research work, to optimize off-line power converter efficiency from light load to full load. A two-stage optimization method to optimize power converter
efficiency from light load to full load is proposed. The optimization procedure first breaks the converter design variables into many switching frequency loops. In each fixed switching frequency loop, the optimal designs for 20%, 50% and 100% load are derived separately in the first stage, and an objective function using the optimization results in the first stage is formed in the second stage to consider optimizing efficiency at 20%, 50% and 100% load. Component efficiency models are also established to serve as the objective functions of optimizations. Prototypes 400V to 12V/25A 300W two-FET forward converters
are built to verify the optimization results
EXPLORING THE WAYS BLACK CHORAL CONDUCTORS NEGOTIATE RACISM AND NONCULTURALLY RELEVANT LEADERSHIP IN CHORAL MUSIC SPACES IN THE UNITED STATES
The purpose of this narrative inquiry was to understand the ways Black choral conductors negotiated racism and nonculturally-relevant choral music leadership in the United States. I sought to address the following research questions: (a) How do Black choral conductors experience racism in choral settings?; (b) How do Black choral conductors describe an ideal culturally relevantâled choral music setting?; and (c) How have their experiences influenced or informed their decisions as choral conductors today? Using critical race theory (CRT) and culturally relevant leadership learning model (CRLL) as the macro-level theoretical lenses and narrative inquiry as the methodology, I sought counternarratives to amplify the stories of Black choral conductors by engaging in conversations centered around racism and nonculturally-relevant leadership in choral settings. I employed purposeful sampling to select three participants who identified as Black choral conductors working in K-12 and higher education settings. The three participants engaged in two ninety-minute, semi-structured interviews. Using thematic analysis techniques, I identified themes that illustrated patterns in the data. Findings reflect the following themes as they pertain to the research questions: (1) navigating racism through developed resilience and resistance, (2) navigating racism through familiarity with Eurocentric music-making practices, (3) culturally relevantâled choral music settings go beyond the surface level of knowing the people led, and (4) Black life experiences influence the use of voice and desire to liberate others. Findings suggest the importance of incorporating the culturally relevant leadership learning model in choral conducting pedagogy. Results may help choral conductors, music educators, and music training environments to rethink, reimagine, and reconceptualize choral music leadership
RESPONSIBILITY AND SUSTAINABILITY IN THE OUTDOOR CLOTHING INDUSTRY based on the website communication of the brands in 2009 and 2021
TÀmÀ pitkittÀistutkimus on laadullinen tapaustutkimus ulkoiluvaatealan vastuullisuudesta ja kestÀvÀstÀ kehityksestÀ. Tutkimuksessa verrataan kahdentoista ulkoiluvaateyrityksen verkkosivustoilla vuosina 2009 ja 2021 kerÀÀmÀÀni aineistoa. Tutkimuksen ensimmÀinen osa tehtiin vuosina 2007-2009. Tutkin ulkoiluvaatemerkkien vastuullisten toimien viestintÀÀ niiden verkkosivustoilla. Sen jÀlkeen kÀytin verkkosisÀllön analyysia aineiston tulkintaan. Aineistoa analysoitiin sekÀ deduktiivisesti ettÀ induktiivisesti. KÀytin Sustainable Apparel Coalitionin Higg Index -työkalua teemojen koodaamiseen ja poimin teemoja myös induktiivisesti aineistosta.
KestÀvÀÀ kehitystÀ ja vastuullisuutta on tutkittu laajasti, mutta en löytÀnyt tutkimusta vastuullisuuden kokonaisvaltaisesta tarkastelusta ulkoiluvaatealalla. Keskityin teoreettisessa taustatyössÀni vastuullisuuden kahteen nÀkökulmaan, ympÀristö- ja sosiaaliseen vastuullisuuteen. TÀrkeimmÀt aiheet olivat kaikki toimitusketjun vaiheet, mukaan lukien materiaalit, elÀinten hyvinvointi ja työntekijöiden oikeuksien periaatteet. Suurin osa vaatetusalan nykyisestÀ tutkimuksesta keskittyy pikamuotiin, ei erityisesti ulkoiluvaatteisiin. Ulkoiluvaatteiden tekninen luonne asettaa kuitenkin erilaisia vaatimuksia toimitusketjulle. LisÀksi ulkoiluvaateala on yhteydessÀ luontoon, ja siksi sen odotetaan olevan vastuullinen ja ympÀristöystÀvÀllinen. TÀssÀ tutkimuksessa tutkittiin nÀiden 12 yrityksen julkista viestintÀÀ vastuullisuudesta niiden verkkosivustoilla vuosina 2009 ja 2021. NÀin ollen niiden verkkosivustoilla olevat tiedot eivÀt vÀlttÀmÀttÀ vastaa sitÀ, mitÀ ne ovat tehneet tosielÀmÀssÀ. Toisaalta yritykset ovat voineet tehdÀ jotain muuta, mitÀ ne eivÀt vielÀ mainitse julkisesti.TÀmÀn tutkimuksen tavoitteena oli ymmÀrtÀÀ, miten viestittyjÀ vastuullisuustoimia parannettiin kahdentoista vuoden aikana. PÀÀtutkimuskysymyksenÀ oli:
Miten valittujen ulkoiluvaateyritysten verkkosivujen viestintÀ on muuttunut kestÀvÀn kehityksen ja vastuullisuuden osalta vuosien 2009 ja 2021 vÀlillÀ?
Tutkimuksen ensimmĂ€isen vaiheen johtopÀÀtöksenĂ€ esitin: Ulkoilualan yritykset eivĂ€t voisi selviytyĂ€ liiketoiminnassa ilman ympĂ€ristövastuun tiedostamista, koska kuluttajien ympĂ€ristötietoisuus alkoi lisÀÀntyĂ€ jo vuonna 2009. Totesin vuonna 2009, ettĂ€ âulkoiluala on herĂ€nnyt ottamaan vastuuta ja alkanut työskentelemÀÀn kestĂ€vĂ€n kehityksen puolestaâ.
Tutkimuksessa pyrittiin selvittĂ€mÀÀn, mitĂ€ oli tapahtunut viime vuosikymmenen aikana. Monet jo vuonna 2009 todetut vastuullisuustoimet ovat edelleen ajankohtaisia. TĂ€mĂ€n tutkimuksen tuloksena oli, ettĂ€ ympĂ€ristöhaasteet olivat muuttuneet entistĂ€ monimutkaisemmiksi, ja uusia on tullut esiin. Viime vuosikymmenen nousevia aiheita olivat muun muassa ilmastonmuutos, PFC-yhdisteet, mikromuovit ja elĂ€in ten hyvinvointi. Viime vuosikymmenen aikana ovat nousseet esiin ja saaneet enemmĂ€n huomiota sosiaalisen vastuun kysymykset, kuten pakkotyö, elĂ€miseen riittĂ€vĂ€ palkka sekĂ€ terveys ja turvallisuus. Vastuullinen toimitusketjun hallinta edellyttÀÀ usein yhteistyötĂ€ tuotemerkkien, toimialajĂ€rjestöjen, voittoa tavoittelemattomien jĂ€rjestöjen, standardointiorganisaatioiden ja kansalaisjĂ€rjestöjen vĂ€lillĂ€. BrĂ€ndien osallistuminen vastuullisuusjĂ€rjestöihin ja kolmannen osapuolen auditointeihin on lisÀÀntynyt. Lopuksi totean, ettĂ€ viime vuosikymmenen aikana vastuullisuudesta ja kestĂ€vĂ€stĂ€ kehityksestĂ€ on tullut erottamaton osa ulkoiluvaatetusalaa.This research study is a longitudinal qualitative case study on the responsibility and sustainability in the outdoor clothing industry. The study compared the data I collected from the websites of 12 selected outdoor clothing companies between 2009 and 2021. The first part of this study was performed between 2007 and 2009. I studied the responsible actions of the outdoor brands on their websites and then used online content analysis to interpret the data. The data were analyzed both deductively and inductively. I also used the Sustainable Apparel Coalitionâs Higg Index tool for coding themes, as well as picking themes inductively from the data.
A broad body of existing research has addressed specific sustainability issues, but I was unable to find a study providing a holistic view of responsibility in the outdoor industry. I concentrated my theoretical background on two aspects of responsibility, environmental and social responsibility. The major topics were the phases of the supply chain, including materials, animal welfare, and principles of workersâ rights. Most of the existing research in the clothing field has concentrated on fast fashion, not specifically on outdoor clothing. However, the technical nature of outdoor clothing requires different standards for the supply chain. Additionally, the outdoor clothing industry is related to nature and therefore expected to be sustainable. This study investigated the 12 companiesâ public communication about responsibility on their websites in 2009 and 2021. This information does not necessarily correlate with what the companies have done in real life or whether they took further action beyond their public communications. Rather, the objective of this study was to understand how communicated responsibility actions were improved in 12 years. The main research question was as follows:
How has selected outdoor clothing companiesâ websitesâ communication changed regarding sustainability and responsibility between 2009 and 2021?
As a final remark on the studyâs first phase, I suggested that outdoor brands could not survive in the business without acknowledging environmental responsibility as consumersâ environmental awareness was increasing, even in 2009. I concluded that âthe outdoor industry has awakened to take responsibility and started to work for sustainable development.â
Further, this study aimed to determine what progress has happened over the past decade, and it concluded that many factors stated in 2009 are still accurate. The study found that the environmental challenges have become more complex, and new topics have emerged. Some of the emerging topics of the past decade are climate change, PFCs, microplastics, and animal welfare. Furthermore, social responsibility issues, such as forced labor, a living wage, and health and safety, have garnered attention. Responsible supply chain management often requires collaboration between brands, industry associations, non-profits, standards, and non-governmental organizations. Thus, the brandsâ involvement in responsibility organizations and third-party auditioning has increased. I conclude that the past decade has rendered responsibility and sustainability inseparable parts of the outdoor clothing business