No description available.

<p dir="ltr">Among the major row crops in the United States, corn and soybeans stand out due to their high nutritional value and economic importance. Achieving optimal yields is restrained by the challenge of fertilizer management. Many fields experience yield losses due to insufficient mineral nutrients like nitrogen (N), while excessive fertilization raises costs and environmental risks. The critical issue is the accurate determination of fertilizer quantity and timing, underscoring the need for precise, early-stage diagnostics. Emerging high-throughput plant phenotyping techniques, notably hyperspectral imaging (HSI), have been increasingly utilized to identify plant’s responses to abiotic or biotic stresses. Varieties of HSI systems have been developed, such as airborne imaging systems and indoor imaging stations. However, most of the current HSI systems’ signal quality is often compromised by various environmental factors. To address the issue, a handheld hyperspectral imager known as LeafSpec was recently developed at Purdue University and represents a breakthrough with its ability to scan corn or soybean leaves at exceptional spatial and spectral resolutions, improving plant phenotyping quality at reduced costs. Most of the current HSI data processing methods focus on spectral features but rarely consider spatially distributed information. Thus, the objective of this work was to develop a methodology utilizing spatial-spectral features for accurate and reliable diagnostics of crop N nutrient stress. The key innovations include the designing of spatial-spectral features based on the leaf venation structures and the feature mining method for predicting the plant nitrogen condition. First, a novel analysis method called the Natural Leaf Coordinate System (NLCS) was developed to reallocate leaf pixels and innovate the nutrient stress analysis using pixels’ relative locations to the venation structure. A new nitrogen prediction index for soybean plants called NLCS-N was developed, outperforming the conventional averaged vegetation index (Avg. NDVI) in distinguishing healthy plants from nitrogen-stressed plants with higher t-test p-values and predicting the plant nitrogen concentration (PNC) with higher R-squared values. In one of the test cases, the p-values and R-squared values were improved, respectively, from 2.1×10^-3 to 6.92×10^-12 and from 0.314 to 0.565 by Avg. NDVI and NLCS-N. Second, a corn leaf venation segmentation algorithm was developed to separate the venation structure from a corn leaf LeafSpec image, which was further used to generate 3930 spatial-spectral (S-S) features. While the S-S features could be the input variable to build a PNC prediction model, a feature selection mechanism was developed to improve the models’ accuracy in terms of reduced cross-validation errors. In one of the test cases, the cross-validation root mean squared errors were reduced compared with the leaf mean spectra from 0.273 to 0.127 using the selected features. Third, several novel spatial-spectral indexes for corn leaves were developed based on the color distributions at the venation level. The top-performing indexes were selected through a ranking system based on Cohen’s d values and the R-squared values, resulting in a best-performing S-S N prediction index with 0.861 R-squared values for predicting the corn PNC in a field assay. The discussion sections provided insights into how a robust PNC prediction index could be developed and related to plant science. The methodologies outlined offer a framework for broader applications in spatial-spectral analysis using leaf-level hyperspectral imagery, serving as a guide for scientists and researchers in customizing their future studies within this field.</p>

Während über hexagonales (alpha) GaN zum ersten Mal 1932 berichtet wurde, gelang erst 1989 die Synthese einer mit Molekularstrahlepitaxie (MBE) auf 3C-SiC epitaktisch gewachsenen, metastabilen kubischen (eta) GaN Schicht. Die vorliegende Arbeit befaßt sich mit der Herstellung der Verbindungen eta-(In,Ga,Al)N mittels RF-Plasma unterstützter MBE auf GaAs(001) und den mikrostrukturellen sowie optischen Eigenschaften dieses neuartigen Materialsystems. Im Vergleich zur hexagonalen bietet die kubische Kristallstruktur auf Grund ihrer höheren Symmetrie potentielle Vorteile für die Anwendung in optischen und elektronischen Bauelementen. Viele wichtige Materialgrößen der kubischen Nitride sind jedoch noch gänzlich unbekannt, da sich die Synthese einkristalliner Schichten als sehr schwierig erweist. Das Ziel dieser Arbeit ist es daher erstens, die technologischen Grenzen der Herstellung von bauelementrelevanten kubischen (In,Ga,Al)N Heterostrukturen auszuweiten und zweitens, einen Beitrag zur Aufklärung der bis dato wenig bekannten optischen und elektronischen Eigenschaften des GaN und der Mischkristalle In GaN zu leisten. Zunächst wird ein optimierter MBE Prozess unter Einsatz einer Plasmaquelle hohen Stickstofflusses vorgestellt, welcher nicht nur die reproduzierbare Epitaxie glatter, einphasiger GaN Nukleationsschichten auf GaAs ermöglicht. Vielmehr können damit auch dicke GaN. Schichten mit glatter Oberflächenmorphologie hergestellt werden, welche die Grundlage komplizierterer eta-(In,Ga,Al)N Strukturen bilden. An einer solchen GaN Schicht mit einer mittleren Rauhigkeit von nur 1.5 nm werden dann temperaturabhängige Reflexions- und Transmissionsmessungen durchgeführt. Zur Auswertung der Daten wird ein numerisches Verfahren entwickelt, welches die Berechnung des kompletten Satzes von optischen Konstanten im Spektralgebiet 2.0 = 0.4 wären grün-gelbe Laserdioden. Zusammenfassung in PostScript / While the earliest report on wurtzite (alpha) GaN dates back to 1932, it was not until 1989 that the first epitaxial layer of metastable zincblende (eta) GaN has been synthesized by molecular beam epitaxy (MBE) on a 3C-SiC substrate. The present work focuses on radio frequency (RF) plasma-assisted MBE growth, microstructure, and optical properties of the eta-(In,Ga,Al)N material system on GaAs(001). Due to their higher crystal symmetry, these cubic nitrides are expected to be intrinsically superior for (opto-) electronic applications than the widely employed wurtzite counterparts. Owing to the difficulties of obtaining single-phase crystals, many important material constants are essentially unknown for the cubic nitrides. The aim of this work is therefore, first, to push the technological limits of synthesizing device-relevant zincblende (In,Ga,Al)N heterostructures and, second, to determine the basic optical and electronic properties of GaN as well as to investigate the hardly explored alloy InGaN. An optimized MBE growth process is presented which allows not only the reproducible nucleation of smooth, monocrystalline GaN layers on GaAs using a high-nitrogen-flow RF plasma source. In particular, thick single-phase GaN layers with smooth surface morphology are obtained being a prerequisite for the synthesis of ternary eta-(Ga,In,Al)N structures. Temperature dependent reflectance and transmittance measurements are carried out on such a GaN film having a RMS surface roughness as little as 1.5 nm. A numerical method is developed which allows to extract from these data the complete set of optical constants for photon energies covering the transparent as well as the strongly absorbing spectral range (2.0 -- 3.8 eV). Inhomogeneities in the refractive index leading to finite coherence effects are quantitatively analyzed by means of Monte Carlo simulations. The fundamental band gap EG(T) of GaN is determined for 5 < T < 300 K and the room temperature density of states is investigated. Systematic studies of the band edge photoluminescence (PL) in terms of transition energies, lineshapes, linewidths, and intensities are carried out for both alpha- and GaN as a function of temperature. Average phonon energies and coupling constants, activation energies for thermal broadening and quenching are determined. Excitation density dependent PL measurements are carried out for both phases in order to study the impact of nonradiative recombination processes at 300 K. A recombination model is applied to estimate the internal quantum efficiency, the (non)radiative lifetimes, as well as the ratio of the electron to hole capture coefficients for both polytypes. It is seen that the dominant nonradiative centers in the n-type material investigated act as hole traps which, however, can be saturated at already modest carrier injection rates. In summary, despite large defect densities in GaN due to highly mismatched heteroepitaxy on GaAs, band edge luminescence is observed up to 500 K with intensities comparable to those of state-of-the-art alpha-GaN. For the first time, thick InGaN films are fabricated on which blue and green luminescence can be observed up to 400 K for x=0.17 and x=0.4, respectively. Apart from bulk-like InGaN films, the first coherently strained InGaN/GaN (multi) quantum wells with In contents as high as 50 % and abrupt interfaces are grown. This achievement shows that a ternary alloy can be synthesized in a metastable crystal structure far beyond the miscibility limit of its binary constituents despite the handicap of highly lattice mismatched heteroepitaxy. The well widths of these structures range between 4 and 7 nm and are thus beyond the theoretically expected critical thickness for the strain values observed. It is to be expected that even higher In contents can be reached for film thicknesses below 5 nm. The potential application of such InGaN/GaN multi quantum wells with x >= 0.4 would thus be diode lasers operating in the green-yellow range. abstract in PostScript

To increase the survival rate from infectious- and noncommunicable diseases, reliable diagnostic during the preliminary stages of a disease onset is of vital importance. This is not trivial to achieve, a highly sensitive and selective detection system is needed for measuring the low concentrations of biomarkers available. One possible route to achieve this is through biosensing based on plasmonic nanostructures, which during the last decade have demonstrated impressive diagnostic capabilities. These nanoplasmonic surfaces have the ability to significantly enhance fluorescence- and Raman signals through localized hotspots, where a stronger then normal electric field is present. By further utilizing a periodic sub-wavelength nanohole array the extraordinary optical transmission phenomena is supported, which open up new ways for miniaturization. In this study a nanoplasmonic chip (NPC) composed of a nanohole array —with lateral size on the order of hundreds of nanometer— covered in a thin layer of gold is created. The nanohole array is fabricated using soft nanoimprint lithography on two resists, hydroxypropyl cellulose (HPC) and polymethyl methacrylate (PMMA). An in depth analysis of the effect of thickness is done, where the transmittance and Raman scattering (using rhodamine 6G) are measured for varying gold layers from 5 to 21 nm. The thickness was proved to be of great importance for optimizing the Raman enhancement, where a maximum was found at 13 nm. The nanohole array were also in general found beneficial for additionally enhancing the Raman signal. A transmittance minima and maxima were found in the region 200-1000 nm for the NPCs, where the minima redshifted as the thickness increased. The extraordinary transmission phenomena was however not observed at these thin gold layers. Oxygen plasma treatment further proved an effective treatment method to reduce the hydrophobic properties of the NPCs. Care needs be taken when using thin layers of gold with a PMMA base, as the PMMA structure could get severely damaged by the plasma. HPC also proved inadequate for this projects purpose, as water-based fluids easily damaged the surface despite a deposited gold layer on top.

Today’s buildings are responsible for 40% of the world’s energy use and also a substantial share of the Global Warming Potential (GWP). In Sweden, about 21% of the energy use can be related to the heat losses through the climatic envelope. The “Million Program” (Swedish: Miljonprogrammet) is a common name for about one million housing units, erected between 1965 and 1974 and many of these buildings suffer from poor energy performance. An important aim of this study was to access the possibilities of using Vacuum Insulation Panels (VIPs) in buildings with emphasis on the use of VIPs for improving the thermal efficiency of the “Million Program” buildings. The VIPs have a thermal resistance of about 8-10 times better than conventional insulations and offer unique opportunities to reduce the thickness of the thermal insulation. This thesis is divided into three main subjects. The first subject aims to investigate new alternative VIP cores that may reduce the market price of VIPs. Three newly developed nanoporous silica were tested using different steady-state and transient methods. A new self-designed device, connected to a Transient Plane Source (TPS) instrument was used to determine the thermal conductivity of granular powders at different gaseous pressure combined with different mechanical loads. The conclusion was that the TPS technique is less suitable for conducting thermal conductivity measurements on low-density nanoporous silica powders. However, deviations in the results are minimal for densities above a limit at which the pure conduction becomes dominant compared to heat transfer by radiation. The second subject of this work was to propose a new and robust VIP mounting system, with minimized thermal bridges, for improving the thermal efficiency of the “Million Program” buildings. On the basis of the parametric analysis and dynamic simulations, a new VIP mounting system was proposed and evaluated through full scale measurements in a climatic chamber. The in situ measurements showed that the suggested new VIP technical solution, consisting of 20mm thick VIPs, can improve the thermal transmittance of the wall, up to a level of 56%. An improved thermal transmittance of the wall at centre-of-panel coordinate of 0.118 to 0.132 W m-2K-1 and a measured centre-of-panel thermal conductivity (λcentre-of-panel) of 7 mW m-1K-1 were reached. Furthermore, this thesis includes a new approach to measure the thermal bridge impacts due to the VIP joints and laminates, through conducting infrared thermography investigations. An effective thermal conductivity of 10.9 mW m-1K-1 was measured. The higher measured centre-of-panel and effective thermal conductivities than the published centre-of-panel thermal conductivity of 4.2 mW m-1K-1 from the VIP manufacturer, suggest that the real thermal performance of VIPs, when are mounted in construction, is comparatively worse than of the measured performance in the laboratory. An effective thermal conductivity of 10.9 mW m-1K-1 will, however, provide an excellent thermal performance to the construction. The third subject of this thesis aims to assess the environmental impacts of production and operation of VIP-insulated buildings, since there is a lack of life cycle analysis of whole buildings with vacuum panels. It was concluded that VIPs have a greater environmental impact than conventional insulation, in all categories except Ozone Depilation Potential. The VIPs have a measurable influence on the total Global Warming Potential and Primary Energy use of the buildings when both production and operation are taken into account. However, the environmental effect of using VIPs is positive when compared to the GWP of a standard building (a reduction of 6%) while the PE is increased by 20%. It was concluded that further promotion of VIPs will benefit from reduced energy use or alternative energy sources in the production of VIP cores while the use of alternative cores and recycling of VIP cores may also help reduce the environmental impact. Also, a sensitivity analysis of this study showed that the choice of VIPs has a significant effect on the environmental impacts, allowing for a reduction of the total PE of a building by 12% and the GWP can be reduced as much as 11% when considering both production and operation of 50 yes. Finally, it’s possible to conclude that the VIPs are very competitive alternative for insulating buildings from the Swedish “Million Program”. Nevertheless, further investigations require for minimizing the measurable environmental impacts that acquired in this LCA study for the VIP-insulated buildings. / Dagens byggnader ansvarar för omkring 40% av världens energianvändning och  står också för en väsentlig del av utsläppen av växthusgaser. I Sverige kan ca 21 % av energianvändningen relateras till förluster genom klimatskalet. Miljonprogrammet är ett namn för omkring en miljon bostäder som byggdes mellan 1965 och 1974, och många av dessa byggnader har en dålig energiprestanda efter dagens mått. Huvudsyftet med denna studie har varit att utforska möjligheterna att använda vakuumisoleringspaneler (VIP:ar) i byggnader med viss fokus på tillämpning i Miljonprogrammets byggnader. Med en värmeledningsförmåga som är ca 8 - 10 gånger bättre än för traditionell isolering erbjuder VIP:arna unika möjligheter till förbättrad termisk prestanda med minimal isolerings tjocklek. Denna avhandling hade tre huvudsyften. Det första var att undersöka nya alternativ för kärnmaterial som bland annat kan reducera kostnaden vid produktion av VIP:ar. Tre nyutvecklade nanoporösa kiselpulver har testats med olika stationära och transienta metoder. En inom projektet utvecklad testbädd som kan anslutas till TPS instrument (Transient Plane Source sensor), har använts för att mäta värmeledningsförmågan hos kärnmaterial för VIP:ar, vid varierande gastryck och olika mekaniska laster. Slutsatsen blev att transienta metoder är mindre lämpliga för utföra mätningar av värmeledningsförmåga för nanoporösa kiselpulver låg densitet. Avvikelsen i resultaten är dock minimal för densiteter ovan en gräns då värmeledningen genom fasta material blir dominerande jämfört med värmeöverföring genom strålning. Det andra syftet har varit att föreslå ett nytt monteringssystem för VIP:ar som kan användas för att förbättra energieffektiviteten i byggnader som är typiska för Miljonprogrammet. Genom parametrisk analys och dynamiska simuleringar har vi kommit fram till ett förslag på ett nytt monteringssystem för VIP:ar som har utvärderats genom fullskaleförsök i klimatkammare. Resultaten från fullskaleförsöken visar att den nya tekniska lösningen förbättrar väggens U-värde med upp till 56 %. En förbättrad värmegenomgångskoefficienten för väggen i mitten av en VIP blev mellan 0.118 till 0,132 W m-2K-1 och värmeledningstalet centre-av-panel 7 mW m-1K-1 uppnåddes. Detta arbete innehåller dessutom en ny metod för att mäta köldbryggor i anslutningar med hjälp av infraröd termografi. En effektiv värmeledningsförmåga för 10.9 mW m-1K-1 uppnåddes. Resultaten tyder även på att den verkliga termiska prestandan av VIP:ar i konstruktioner är något sämre än mätvärden för paneler i laboratorium. En effektiv värmeledningsförmåga av 10.9 mW m-1K-1 ger dock väggkonstruktionen en utmärkt termisk prestanda. Det tredje syftet har varit att bedöma miljöpåverkan av en VIP-isolerad byggnad, från produktion till drift, eftersom en livscykelanalys av hela byggnader som är isolerade med vakuumisoleringspaneler inte har gjorts tidigare. Slutsatsen var att VIP:ar har en större miljöpåverkan än traditionell isolering, i alla kategorier förutom ozonnedbrytande potential. VIP:ar har en mätbar påverkan på de totala utsläppen av växthusgaser och primärenergianvändningen i byggnader när både produktion och drift beaktas. Miljöpåverkan av de använda VIP:arna är dock positiv jämfört med GWP av en standardbyggnad (en minskning med 6 %) medan primärenergianvändningen ökade med 20 %. Slutsatsen var att ytterligare användning av VIP:ar gynnas av reducerad energiförbrukning och alternativa energikällor i produktionen av nanoporösa kiselpulver medan användningen av alternativa kärnmaterial och återvinning av VIP kärnor kan hjälpa till att minska miljöpåverkan. En känslighetsanalys visade att valet av VIP:ar har en betydande inverkan på miljöpåverkan, vilket ger möjlighet att reducera den totala användningen av primärenergi i en byggnad med 12 % och utsläppen av växthusgaser kan vara minska, så mycket som 11 % när det gäller både produktion och drift under 50 år. Avslutningsvis är det möjligt att dra slutsatsen att VIP:ar är ett mycket konkurrenskraftigt alternativ för att isolera byggnader som är typiska för Miljonprogrammet. Dock krävs ytterligare undersökningar för att minimera de mätbara miljöeffekter som förvärvats i denna LCA-studie för VIP-isolerade byggnader. / <p>QC 20151109</p> / Simulations of heat and moisture conditions in a retrofit wall construction with Vacuum Insulation Panels / Textural and thermal conductivity properties of a low density mesoporous silica material / A study of the thermal conductivity of granular silica materials for VIPs at different levels of gaseous pressure and external loads / Evaluation of the thermal conductivity of a new nanoporous silica material for VIPs – trends of thermal conductivity versus density / A comparative study of the environmental impact of Swedish residential buildings with vacuum insulation panels / ETICS with VIPs for improving buildings from the Swedish million unit program “Miljonprogrammet”

Thesis (Master').

This thesis deals with the solution problem of fitting a window in the wall, especially for passive houses. It provides options to optimize the window connection joints, improve the thermal transmittance of the window frame, thereby reducing the total heat loss through the window. In the first part of the thesis is a research literature on the windows and heat technical and physical mechanisms. Are described equations and physical processes taking place in the windows and related building structures. This section describes the basic points in history, technical description of windows, etc. and present ways of assembly Installation the window and the influence of the thermal properties of the heat loss. The next part deals with the description of the work and the results obtained in the course of doctoral study. Describes the main objectives of the dissertation thesis, calculations and simulations of temperature fields and the results of the calculated values. Furthermore are described and analyzed measurement data and compared with the calculated values. At the end dissertation thesis are given opportunities to improve the current solution regarding the heat transfer coefficient of the frame, the optimal way of installation fillers windows in the perimeter wall and improve the thermal properties of the connecting joint.

No description available.

The goal of the thesis is firstly to get all the information about the initial state of solved block of flats, which is located on the street Merhautova 76/954 in Brno – Černá pole, in terms of constructions, energy consumption and initial state of heating system. In the second part of the thesis, where are discussed the possibilities of reduction of energy consumption, variant drafts of reduction of energy consumption and their financial costs and the choice of optimal variant. Third part deals with assement of solved block of flats in terms of sustainable built environment by using tool to rate buildings in terms of sustainable built environment - SBToolCZ, evaluation of possibility to use renewables. In the end are written summaries and recommendations.