48 research outputs found
Wave-front engineering by Huygens-Fresnel principle for nonlinear optical interactions in domain engineered structures
The wave-front engineering for nonlinear optical interactions was discussed.
Using Huygens-Fresnel principle we developed a general theory and technique for
domain engineering with conventional quasi-phase-matching structures being the
special cases. By Fourier analysis we put forward the concept of local
quasi-phase matching, which suggests that the quasi-phase matching is fulfilled
only locally not globally. Experiments on focal effect of second-harmonic wave
agreed well with the theoretical prediction. The proposed scheme combines three
optical functions: generation, focusing and beam splitting of second-harmonic
wave, thus making the device more compact. Further the proposed scheme can be
used to perform the integration of multi-functional optical properties in
nonlinear photonics, as well as expand the use of nonlinear optical devices.Comment: 15 pages, 3 figure
Multistep Parametric Processes in Nonlinear Optics
We present a comprehensive overview of different types of parametric
interactions in nonlinear optics which are associated with simultaneous
phase-matching of several optical processes in quadratic nonlinear media, the
so-called multistep parametric interactions. We discuss a number of
possibilities of double and multiple phase-matching in engineered structures
with the sign-varying second-order nonlinear susceptibility, including (i)
uniform and non-uniform quasi-phase-matched (QPM) periodic optical
superlattices, (ii) phase-reversed and periodically chirped QPM structures, and
(iii) uniform QPM structures in non-collinear geometry, including recently
fabricated two-dimensional nonlinear quadratic photonic crystals. We also
summarize the most important experimental results on the multi-frequency
generation due to multistep parametric processes, and overview the physics and
basic properties of multi-color optical parametric solitons generated by these
parametric interactions.Comment: To be published in Progress in Optic
Uppdatering av LCA-verktyget WAMPS : FöreslÄ nya utslÀppsfaktorer och undersöka konsekvenserna
In recent decades, life cycle assessment (LCA) has become a commonly used approach worldwide when studying environmental impacts linked to waste management systems. These systems are of a complex nature which includes everything from technical solutions, the environmental influence, and various stakeholders. To facilitate studies within this area of research, different LCA models are often utilised. WAMPS is a software specifically developed for assessing the environmental and economic impacts for a waste management system. During recent years, the work to bring the model up to date has begun as the software has not been modernised since it was developed in the early 2000s. The purpose of this degree project is to propose new emission factors for recycling and virgin production of glass, aluminium, steel, and plastic. In addition to this, the study intends to investigate how the implementation of the new figures may affect the results obtained in WAMPS. To fulfil the purpose of the thesis, LCI datasets were collected for each material and evaluated according to three DQIs (Temporal representativeness, geographical representativeness, and documentation). New emission factors were developed based on the evaluation and discussions within the project group, to ensure that all relevant activities of the studied life cycles were included. The implications from implementing the new emission factors were investigated through a comparison with the old values. This was conducted through comparing the obtained results from WAMPS per one tonne of material as well as for a simple scenario. The evaluation of the collected LCI data shows that many of the datasets represent average production in countries within Europe and that the data were generally older than five years old. The results show that the datasets were primarily well documented according to the criterion utilised in this study. Processes from EcoInvent were mainly used to develop the proposed emission factors. The implementation of the new emission factors in WAMPS resulted in significant change in potential environmental impact per tonne of material. Especially for the impact category photooxidation formation. For the scenario, the results indicated that a significant change in potential environmental burden is received when implementing the new emission factors. A reduction in total impact was obtained for all categories where eutrophication showed the largest absolute difference. The developed emission factors are considered appropriate based on the design of this thesis. However, it is concluded that these have several limitations that are important to take into account if these were to be implemented in WAMPS in the future. In addition, it is considered established that an update may be considered reasonable based on the result obtained. Under de senaste decennierna har livscykelanalys (LCA) blivit ett vanligt tillvaÌgagaÌngssaÌtt vaÌrlden oÌver vid analyser av potentiella miljoÌeffekter kopplade till avfallshanteringssystem. Dessa system aÌr av komplex natur och inkluderar allt fraÌn teknologiska loÌsningar, miljoÌpaÌverkan samt flera intressenter. FoÌr att underlaÌtta dessa studier anvaÌnds idag ofta olika LCA-modeller. WAMPS aÌr ett program som aÌr saÌrskilt utvecklad foÌr att bedoÌma baÌde miljoÌmaÌssiga- och ekonomiska konsekvenser kopplat till avfallshanteringssystem. Under de senaste aÌren har arbetet med att uppdatera modellen paÌboÌrjat eftersom programvaran inte har uppdaterats sedan boÌrjan av 2000-talet. Syftet med detta examensarbete aÌr att foÌreslaÌ nya emissionsfaktorer foÌr aÌtervinning och jungfrulig produktion av glas, aluminium, staÌl, och plast. UtoÌver detta avser studien att studera hur implementeringen av de nya siffrorna inverkar paÌ resultatet som erhaÌlls i WAMPS. FoÌr att uppfylla tesen av detta arbete samlades LCI data in foÌr varje material och utvaÌrderades enligt tre DQI:er (Temporal representativitet, geografisk representativitet och dokumentation). Nya utslaÌppsfaktorer utvecklades baserat paÌ utvaÌrderingen och genom diskussioner inom projektgruppen. FramfoÌrallt foÌr att saÌkerhetsstaÌlla att alla relevanta aktiviteter i de studerade livscyklerna aÌr inkluderade. Konsekvenserna av implementeringen av utslaÌppsfaktorerna undersoÌktes genom en jaÌmfoÌrelse av resultat som erhoÌlls i WAMPS daÌ de nya samt de tidigare faktorerna nyttjas. Detta gjordes baÌde per ton material samt genom ett enkelt scenario. UtvaÌrderingen av den insamlade LCI datan paÌvisar att maÌnga av dataseten representerar genomsnittlig produktion inom Europa och att datan generellt var insamlad foÌr minst 5 aÌr sedan. Resultatet paÌvisar att dataseten aÌr vaÌldokumenterad enlig indikatorn som staÌllts upp i denna studie. FraÌmst anvaÌndes processer fraÌn EcoInvent foÌr att utveckla de nya emissionsfaktorerna. Implementeringen av emissionsfaktorerna i WAMPS resulterade i signifikanta skillnader i potentiell miljoÌpaÌverkan per ton material, fraÌmst foÌr bildning av fotooxid. FoÌr fallet med scenariot indikerade studiens resultat att en betydande foÌraÌndring av den potentiella miljoÌbelastningen erhaÌlls naÌr de nya utslaÌppsfaktorerna implementeras. Dessutom paÌvisades en minskning av miljoÌeffekterna foÌr alla kategorier varav eutrofiering visade den stoÌrsta absoluta skillnaden. Slutligen anses de utvecklade emissions faktorerna vara laÌmpliga utifraÌn utformningen av denna tes. Dock dras slutsatsen att dessa har flertalet begraÌnsningar som aÌr viktiga att ta i haÌnsyn ifall dessa implementeras i WAMPS i framtiden. Dessutom anses det vara faststaÌllt att en fortsatt uppdatering kan anses rimlig utifraÌn det erhaÌllna resultatet.
Uppdatering av LCA-verktyget WAMPS : FöreslÄ nya utslÀppsfaktorer och undersöka konsekvenserna
In recent decades, life cycle assessment (LCA) has become a commonly used approach worldwide when studying environmental impacts linked to waste management systems. These systems are of a complex nature which includes everything from technical solutions, the environmental influence, and various stakeholders. To facilitate studies within this area of research, different LCA models are often utilised. WAMPS is a software specifically developed for assessing the environmental and economic impacts for a waste management system. During recent years, the work to bring the model up to date has begun as the software has not been modernised since it was developed in the early 2000s. The purpose of this degree project is to propose new emission factors for recycling and virgin production of glass, aluminium, steel, and plastic. In addition to this, the study intends to investigate how the implementation of the new figures may affect the results obtained in WAMPS. To fulfil the purpose of the thesis, LCI datasets were collected for each material and evaluated according to three DQIs (Temporal representativeness, geographical representativeness, and documentation). New emission factors were developed based on the evaluation and discussions within the project group, to ensure that all relevant activities of the studied life cycles were included. The implications from implementing the new emission factors were investigated through a comparison with the old values. This was conducted through comparing the obtained results from WAMPS per one tonne of material as well as for a simple scenario. The evaluation of the collected LCI data shows that many of the datasets represent average production in countries within Europe and that the data were generally older than five years old. The results show that the datasets were primarily well documented according to the criterion utilised in this study. Processes from EcoInvent were mainly used to develop the proposed emission factors. The implementation of the new emission factors in WAMPS resulted in significant change in potential environmental impact per tonne of material. Especially for the impact category photooxidation formation. For the scenario, the results indicated that a significant change in potential environmental burden is received when implementing the new emission factors. A reduction in total impact was obtained for all categories where eutrophication showed the largest absolute difference. The developed emission factors are considered appropriate based on the design of this thesis. However, it is concluded that these have several limitations that are important to take into account if these were to be implemented in WAMPS in the future. In addition, it is considered established that an update may be considered reasonable based on the result obtained. Under de senaste decennierna har livscykelanalys (LCA) blivit ett vanligt tillvaÌgagaÌngssaÌtt vaÌrlden oÌver vid analyser av potentiella miljoÌeffekter kopplade till avfallshanteringssystem. Dessa system aÌr av komplex natur och inkluderar allt fraÌn teknologiska loÌsningar, miljoÌpaÌverkan samt flera intressenter. FoÌr att underlaÌtta dessa studier anvaÌnds idag ofta olika LCA-modeller. WAMPS aÌr ett program som aÌr saÌrskilt utvecklad foÌr att bedoÌma baÌde miljoÌmaÌssiga- och ekonomiska konsekvenser kopplat till avfallshanteringssystem. Under de senaste aÌren har arbetet med att uppdatera modellen paÌboÌrjat eftersom programvaran inte har uppdaterats sedan boÌrjan av 2000-talet. Syftet med detta examensarbete aÌr att foÌreslaÌ nya emissionsfaktorer foÌr aÌtervinning och jungfrulig produktion av glas, aluminium, staÌl, och plast. UtoÌver detta avser studien att studera hur implementeringen av de nya siffrorna inverkar paÌ resultatet som erhaÌlls i WAMPS. FoÌr att uppfylla tesen av detta arbete samlades LCI data in foÌr varje material och utvaÌrderades enligt tre DQI:er (Temporal representativitet, geografisk representativitet och dokumentation). Nya utslaÌppsfaktorer utvecklades baserat paÌ utvaÌrderingen och genom diskussioner inom projektgruppen. FramfoÌrallt foÌr att saÌkerhetsstaÌlla att alla relevanta aktiviteter i de studerade livscyklerna aÌr inkluderade. Konsekvenserna av implementeringen av utslaÌppsfaktorerna undersoÌktes genom en jaÌmfoÌrelse av resultat som erhoÌlls i WAMPS daÌ de nya samt de tidigare faktorerna nyttjas. Detta gjordes baÌde per ton material samt genom ett enkelt scenario. UtvaÌrderingen av den insamlade LCI datan paÌvisar att maÌnga av dataseten representerar genomsnittlig produktion inom Europa och att datan generellt var insamlad foÌr minst 5 aÌr sedan. Resultatet paÌvisar att dataseten aÌr vaÌldokumenterad enlig indikatorn som staÌllts upp i denna studie. FraÌmst anvaÌndes processer fraÌn EcoInvent foÌr att utveckla de nya emissionsfaktorerna. Implementeringen av emissionsfaktorerna i WAMPS resulterade i signifikanta skillnader i potentiell miljoÌpaÌverkan per ton material, fraÌmst foÌr bildning av fotooxid. FoÌr fallet med scenariot indikerade studiens resultat att en betydande foÌraÌndring av den potentiella miljoÌbelastningen erhaÌlls naÌr de nya utslaÌppsfaktorerna implementeras. Dessutom paÌvisades en minskning av miljoÌeffekterna foÌr alla kategorier varav eutrofiering visade den stoÌrsta absoluta skillnaden. Slutligen anses de utvecklade emissions faktorerna vara laÌmpliga utifraÌn utformningen av denna tes. Dock dras slutsatsen att dessa har flertalet begraÌnsningar som aÌr viktiga att ta i haÌnsyn ifall dessa implementeras i WAMPS i framtiden. Dessutom anses det vara faststaÌllt att en fortsatt uppdatering kan anses rimlig utifraÌn det erhaÌllna resultatet.
Biochar production from beach-cast : A study of the suitability of producing biochar from algae and aquatic plants from Gotland
Ăstersjön har flertalet regionala miljöproblem, exempelvis övergödning samt höga halter av tungmetaller vilka beror pĂ„ mĂ€nsklig pĂ„verkan. PĂ„ Gotland spolas det Ă„rligen upp stora mĂ€ngder slĂ€ke, alger och vattenlevande vĂ€xter pĂ„ strĂ€nderna, som idag inte nyttjas i större utstrĂ€ckning. Denna rapport syftar att bedöma lĂ€mpligheten att anvĂ€nda det gotlĂ€ndska slĂ€ket för produktion av biokol. Under denna studie har ett studiebesök till Gotland, flertalet intervjuer samt en litteraturstudie genomförts vilka lagt grund för berĂ€kningar av energi- och materialbalanser kopplat till slĂ€kesbaserad biokolsproduktion. SlĂ€ket har ett kadmiuminnehĂ„ll pĂ„ cirka 0,9 mg/kg och bestĂ„r till 80 % av vatten, dĂ€r vanligt förekommande arter Ă€r bland annat bandtĂ„ng och krĂ€kel. För berĂ€kningar av energi- och materialbalanser nyttjades tvĂ„ olika förbehandlingsalternativ av slĂ€ket, dĂ€r alternativ A var en vĂ€rmebehandling och alternativ B innefattar en kompostering samt avlsutande vĂ€rmebehandling. Alternativ B Ă€r mer energieffektiv sett till energiförbrukning per kilo producerat biokol vilket var 14,5 MJ/kg jĂ€mfört med 29,8 MJ/kg. Det finns bĂ„de för- och nackdelar med anvĂ€ndning av slĂ€ke för biokolsproduktion. SlĂ€ke Ă€r en outnyttjad resurs som kan ingĂ„ i biokolsframstĂ€llning, dock Ă€r processen energikrĂ€vande pĂ„ grund av det höga vatteninnehĂ„llet i biomassan. AnvĂ€ndningen av ett kadmiumrikt biokol Ă€r Ă€ven problematiskt i och med risken för utlakning av denna tungmetall. UtifrĂ„n resultatet Ă€r det dĂ€rmed svĂ„rt att bedöma lĂ€mpligheten av ett slĂ€kesbaserat biokol.The Baltic sea has multiple environmental problems, such as over-fertilization and high concentration of certain heavy metals, caused by human activity. Yearly, beach-cast is washed up on the shores of Gotland and this biomass is today not utilised to a considerable extent. This report aims to assess the suitability of producing biochar from the left over beach-cast. During this study a visit to Gotland, interviews and a literature study has been completed, which has laid the groundwork for calculations of energy and material balances regarding algae-based biochar production. The beach-cast contains approximately 0.9 mg cadmium per kg and consists of 80 % water, in which common species found are eelgrass and furcellaria, among others. For the calculations of energy- and material balances, two different pretreatment alternatives were used before the pyrolysis. Alternative A simply uses preheating and alternative B consist of a composting step before a finishing preheating session. The most energy efficient was alternative B as the power consumption per kilo produced biochar was 14,5 MJ/kg compared to 29,8 MJ/kg. The use of beach-cast for manufacturing biochar has benefits as well as disadvantages. Beach-cast is an unexploited resource that could be used for biochar production, but on the other hand the process is demanding energy-wise due to the high amount of water in the biomass. The utilisation of cadmium rich biochar is also problematic due to the risk of the heavy metal leaching. Based on the results it is therefore complicated to estimate the suitability of a beach-cast based biochar
Motor abnormalities among children with PANS and/or PANDAS
<p><i>Introduction: </i>Pediatric Acute-onset Neuropsychiatric
Syndrome (PANS) and Pediatric Autoimmune Neuropsychiatric disorders Associated
with Streptococcal Infections (PANDAS) are putative diagnoses with symptoms
including tics and obsessive compulsive disorder. These disorders are believed
to be caused by antibodies against the basal ganglia. Some reports show that
these patients have affected motor control. This may be explained by the
hypothesis that antibodies against the basal ganglia cause the disorders. <i>Aims: </i>This study aimed to compare the
presence of motor abnormalities among patients with PANS and/or PANDAS and age-
and sex-matched healthy persons. <i>Material
and Methods: </i>17 persons aged 8-19 years that had been diagnosed with PANS
and/or PANDAS in Sweden were included in the study. 25 controls were matched
with the patients regarded age and sex. Both groups were then examined with 6
tests of motor function. The tests were scored and groups were compared using
linear regression. The total score for the test was 0-22 where 0 points indicated
a test performed without any impairments and 22 points was a test performed
with large difficulty. <i>Results: </i>The mean
score for the patients was 8.2 points and the mean score for the controls was 4.5
points, indicating a higher presence of motor abnormalities among patients with
PANS and/or PANDAS. The effect adjusted for age was 3.7 points lower for the
controls compared to the patients, p = 0.0004. <i>Conclusions: </i>Our results suggest that patients with PANS and/or
PANDAS have more motor abnormalities compared to age and sex matched controls.</p
Biochar production from beach-cast : A study of the suitability of producing biochar from algae and aquatic plants from Gotland
Ăstersjön har flertalet regionala miljöproblem, exempelvis övergödning samt höga halter av tungmetaller vilka beror pĂ„ mĂ€nsklig pĂ„verkan. PĂ„ Gotland spolas det Ă„rligen upp stora mĂ€ngder slĂ€ke, alger och vattenlevande vĂ€xter pĂ„ strĂ€nderna, som idag inte nyttjas i större utstrĂ€ckning. Denna rapport syftar att bedöma lĂ€mpligheten att anvĂ€nda det gotlĂ€ndska slĂ€ket för produktion av biokol. Under denna studie har ett studiebesök till Gotland, flertalet intervjuer samt en litteraturstudie genomförts vilka lagt grund för berĂ€kningar av energi- och materialbalanser kopplat till slĂ€kesbaserad biokolsproduktion. SlĂ€ket har ett kadmiuminnehĂ„ll pĂ„ cirka 0,9 mg/kg och bestĂ„r till 80 % av vatten, dĂ€r vanligt förekommande arter Ă€r bland annat bandtĂ„ng och krĂ€kel. För berĂ€kningar av energi- och materialbalanser nyttjades tvĂ„ olika förbehandlingsalternativ av slĂ€ket, dĂ€r alternativ A var en vĂ€rmebehandling och alternativ B innefattar en kompostering samt avlsutande vĂ€rmebehandling. Alternativ B Ă€r mer energieffektiv sett till energiförbrukning per kilo producerat biokol vilket var 14,5 MJ/kg jĂ€mfört med 29,8 MJ/kg. Det finns bĂ„de för- och nackdelar med anvĂ€ndning av slĂ€ke för biokolsproduktion. SlĂ€ke Ă€r en outnyttjad resurs som kan ingĂ„ i biokolsframstĂ€llning, dock Ă€r processen energikrĂ€vande pĂ„ grund av det höga vatteninnehĂ„llet i biomassan. AnvĂ€ndningen av ett kadmiumrikt biokol Ă€r Ă€ven problematiskt i och med risken för utlakning av denna tungmetall. UtifrĂ„n resultatet Ă€r det dĂ€rmed svĂ„rt att bedöma lĂ€mpligheten av ett slĂ€kesbaserat biokol.The Baltic sea has multiple environmental problems, such as over-fertilization and high concentration of certain heavy metals, caused by human activity. Yearly, beach-cast is washed up on the shores of Gotland and this biomass is today not utilised to a considerable extent. This report aims to assess the suitability of producing biochar from the left over beach-cast. During this study a visit to Gotland, interviews and a literature study has been completed, which has laid the groundwork for calculations of energy and material balances regarding algae-based biochar production. The beach-cast contains approximately 0.9 mg cadmium per kg and consists of 80 % water, in which common species found are eelgrass and furcellaria, among others. For the calculations of energy- and material balances, two different pretreatment alternatives were used before the pyrolysis. Alternative A simply uses preheating and alternative B consist of a composting step before a finishing preheating session. The most energy efficient was alternative B as the power consumption per kilo produced biochar was 14,5 MJ/kg compared to 29,8 MJ/kg. The use of beach-cast for manufacturing biochar has benefits as well as disadvantages. Beach-cast is an unexploited resource that could be used for biochar production, but on the other hand the process is demanding energy-wise due to the high amount of water in the biomass. The utilisation of cadmium rich biochar is also problematic due to the risk of the heavy metal leaching. Based on the results it is therefore complicated to estimate the suitability of a beach-cast based biochar
à tervinning av smutsig sand frÄn uttjÀnta kostgrÀsplaner : Hanterings- och behandlingsmetoder
DÄ sanden frÄn konstgrÀsplaner Àven innehÄller rester av plast och gummi frÄn infill och grÀsstrÄn sÄ Àr sanden inte lÀmplig att Äterbruka exempelvis pÄ golfbanor eller liknande, men det finns andra alternativa Ätervinningsmetoder. I det hÀr projektet har olika hanteringsmetoder undersökts för att se hur vÀl de fungerar och de har Àven kartlagts för att se var dessa gÄr att finna i nÀrheten av de konstgrÀsplaner dÀr problemet uppstÄr. Det har tagits fram ett antal rekommendationer för att fÄ ett bÀttre resursutnyttjande och för att minska risken för spridning av mikroplast frÄn sanden