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The use of wood in geotechnical applications has seen renewed interest. However, concerns related to the durability and service life of wood in ground contact applications remain. Wood has the potential to substitute commonly used steel and concrete in the geotechnical engineering sector, but solutions to extending the service life and maintenance intervals require long-lasting wood protection systems capable of inhibiting fungal and bacterial decay. Cement, one of the constituents of concrete was identified as a potential coating material for wood used in soil stabilisation works. Spruce and beech wood rest rolls from commercial veneer peeling has been identified as a potential source for cement-coated geotechnical wood products. Norway spruce and European beech wood was subsequently used in this study.
In this study, a series of tests related to dimensional stability and fungal durability were undertaken to investigate the adhesion of a cement coating to wood and to assess the effect of a cement coating on the resistance to fungal decay. Swelling and shrinkage tests of uncoated specimens were undertaken to investigate dimensional stability. Laboratory fungal durability tests assessed changes in wood durability of specimens coated with a novel, flexural cement coating. Wood impregnated with Polyethyleneglycol-dimethacrylate (PEGDMA) prior to cement coating was investigated to improve wood dimensional stability and reduce cracking of the cement coating under changing wood moisture conditions. Cement coating thickness and delamination tests then assessed the durability of the novel cement coating itself. Results from fungal durability tests showed that a continuous, flexural, and crack-free cement coating was imperative to a wood durability improvement. Double cement-coated spruce wood showed improved resistance to decay by basidiomycetes (Coniphora puteana and Trametes versicolor). Results from swelling and shrinkage tests showed that an improvement in dimensional stability would assist in achieving a durable cement coating and impregnation with Polyethyleneglycol-dimethacrylate (PEGDMA) is one manner to improve dimensional stability and therefore cement adhesion to the wood substrate.
LFT- „Hype or Hope“
(2019)
Outdoor or just on site analyzes of photovoltaic modules can offer some advantages in comparison to indoor Lab studies. In this way the electrical performance is monitored and logged under natural operating conditions in full range of irradiation and temperature. The entirety of monitored IV data allows deriving low-light characteristics of electric parameters, temperature coefficients and root cause analysis for possible degradation. We apply so-called self-reference algorithm in order to increase the accuracy of analysis. The improved precision is due to application of effective acting irradiation and effective temperature instead of externally measured data. Effective irradiation is determined in self-referencing scheme: the short circuit current of the module is assigned to the irradiation. This assignment has to be calibrated, preferably at standard test conditions for irradiation. In this contribution we demonstrate a process of precise measurement of Isc under clear-sky outdoor conditions and the determination of the short circuit current for STC. The measurement method avoids errors by spectral deviations with respect to AM 1.5G spectrum, by optical reflection losses for high angles of incidence and errors by high albedo impact. In particular we investigate comparatively a CdTe module under outdoor conditions and by means a calibrated indoor Lab flasher.
Outdoor or just on site analyzes of photovoltaic modules can offer some advantages in comparison to indoor Lab stud-ies. In this way the electrical performance is monitored and logged under natural operating conditions in full range of irradiation and temperature. The entirety of monitored IV data allows deriving low-light characteristics of electric parameters, temperature coefficients and root cause analysis for possible degradation. We apply so-called self-reference algorithm in order to increase the accuracy of analysis. The improved precision is due to application of effective acting irradiation and effective temperature instead of externally measured data. Effective irradiation is determined in self-referencing scheme: the short circuit current of the module is assigned to the irradiation.
CdS/CdTe thin film solar technology is one of the most promising concepts to accomplish high efficiencies and low costs in mass production. Further knowledge about electric parameters, such as serial resistances and recombination losses, is needed in order to improve in a systematic approach the module efficiency. The basic tool for device evaluation is the JV-measurement (current density – voltage) under standard test conditions. JVmeasurements result in rather direct determination of electric parameters, and detailed JV-analysis in indirect determination of some more relevant electric parameters. For thin film solar cells the usual 2-diode model and the responsible equation can be reduced to a 1-diode model due to significant recombination processes in the space charge region. However, the fit results suffer on imprecision of derived recombination currents (Jrec), and series resistance (Rs), due to their ambiguousness in fit routine. Direct and precise access of Rs by measurements fails for CdTe, due to its significant dependency on illumination levels. In this work we present a new method for precise Rs and Jrec determination of CdTe cells.
Outdoor-I-U-Messungen an Photovoltaik- (PV) - Modulen haben den Vorteil, dass Effekte wie „light soaking“ oder „light-induced degradation“ unter natürlichen Bedingungen untersucht werden können. Solche Outdoor-Analysen können unter Anwendung des Selbstreferenzierungsalgorithmus (SRA) die Zuverlässigkeit von Indoor-Flasher-Messungen erreichen. Dieses neue Konzept liefert I-UEigenschaften für wesentlich mehr Testbedingungen als vom Standard IEC 61853 gefordert und so können Schwachlichtkurven aller relevanten elektrischen I-U-Parameter für bestimmte Temperaturen erzeugt werden. Wir berichten über experimentelle Ergebnisse einer 6-tägigen Outdoor-Messkampagne an Dünnschicht-PV-Modulen. Wir evaluieren darüber hinaus die Möglichkeiten, Temperaturkoeffizienten, STC- und NOCT-Daten zu bestimmen und I-U-Kennlinien als Basis für Fitting-Analysen abzuleiten. Abschließend wird die Genauigkeit der neuen Outdoor-Methode untersucht.
Ziel des Projektes ist es, ein Verfahren für elektrische Vorort-Leistungsanalysen von Photovoltaik (PV)-Anlagen zu entwickeln. Dazu werden die elektrischen Parameter von PV-Strings lokal und global mit Hilfe eines neuen Feldlaboransatzes mit Indoor-Laborgenauigkeit vermessen. Das neue Messverfahren ist normgerecht und wird helfen, die Standardisierung von Feldmessungen weiterzuentwickeln. Im Projekt werden bekannte Messmethoden der Photovoltaik, (IR-Thermografie, I-U-String-Messung, digitale Datenverarbeitung mittels Selbstreferenzierung) zu einem innovativen Gesamtkonzept synthetisch zusammengeführt. Die Entwicklung des Messverfahrens wird an speziell gealterten PV-Anlagen marktbestimmender Technologien (c-Si-, CdTe-, CIGS-Muster-PV-Anlagen) vorangetrieben. So wird das Verfahren auf Erkennung spezifischer Degradationsszenarien und marginaler quantitativer Parameterveränderungen trainiert und geschärft
Outdoor performance analyses of photovoltaic modules can be advantageous compared to indoor investigations, as they take into account the influences of natural test conditions on the modules. However, such outdoor performance assessments usually suffer from poor accuracies due to undefined test conditions for the modules. This paper reports on a comprehensive concept for improved outdoor analysis which results in performance data with indoor laboratory precision. The approach delivers current-voltage characteristics for even more test conditions than required by the standard IEC 61853-1. Hence, curves of modules’ electrical parameters above irradiance can be deduced for any temperatures. The concept allows precise determination of temperature coefficients for user-defined irradiances taking into account outdoor effects like light-soaking or light-induced degradation. The calibration and measurement uncertainty of the presented outdoor analysis method is evaluated quantitatively. For the measurements an advanced outdoor set-up was used.
Freifeldcharakterisierung von PV-Anlagen im Rahmen des Projektes PV- FeldLab -ein Statusbericht-
(2020)
Das Projekt PV-FeldLab verfolgt das Ziel, ein umfassendes Konzept für eine messtechnisch sehr präzise elektrische Freifeld-Charakterisierung von PV-Generatoren zu entwickeln. Es beinhaltet eine optische Untersuchung mittels drohnengestützter Thermografie und eine genaue elektrische Charakterisierung von PV-Anlagen im Freifeld, auch bei räumlicher Inhomogenität von Bestrahlungsstärke, Temperatur und bei variablen Aufbauwinkeln von Modulen im Strang. Die Verknüpfung der elektrischen und optischen Messdaten erlaubt eine effiziente Untersuchung von PV-Anlagen und ermöglicht eine Präzisierung von Ertragsanalysen. Dieser Bericht beschreibt den ersten Projektabschnitt, in welchem der Fokus vor allem auf der Initialisierung der messtechnischen Komponenten, sowie ersten Messungen und Analysen liegt.
A quantitative physical model for potential induced degradation of the shunting type (PID-s) in solar modules is introduced. Based on a drift and diffusion approach for sodium ions and atoms, it gives insight into the kinetics of degradation and the corresponding regeneration. A simple drift/source term is used to describe the time-dependent flux of Na-ions towards stacking faults at the surface of the solar cell. The assumed transport mechanism for Na+ ions through the SiN-layer uses the modified Stern-Eyring rate theory but our approach can also be adapted to other mechanisms. Several PID-s and regeneration curves of one-cell solar modules at T = 49°C and T = 90°C with 1000V potential difference between modul frame and cell were measured and least-square fits of the in-situ measured parallel resistance Rsh to the model were performed giving very good accordance.
Based on a few measurements, the model can predict PID-s and regeneration characteristics of solar modules under different conditions.
When monitoring the energy performance of buildings, it may be of interest to identify the occupation periods of people in the room due to their possible impact on the energy balance. In order to be able to carry out a comprehensive energy assessment of the system and building, it is necessary to be able to classify user influence during the evaluation. This thesis investigates how the presence of people in a room can be determined cost-effectively and with little additional effort. The aim is to determine which sensors of a room control system provide sufficiently reliable data. The presence of 1-2 persons was examined on a test facility of the Technical University Rosenheim. The air-, mean radiation- and surface-temperatures, the air humidity as well as the CO2 and VOC concentrations were measured. For the analysis, a method of supervised machine and statistical learning, random forest, is used. The smallest model error detected in predicting the presence of 1 or 2 persons from CO2 sensor data is 1.43%. The error rates are low for all tested models if time-dynamic effects are used as predictors and the data is processed in a so-called time period form. Additionally, the ways in which this data should ideally be made available for future measurements and processed to facilitate analysis with machine and statistical learning techniques have been investigated. A further goal is to apply the models developed on measurement series in laboratory environments to real rooms and to assess the transferability of these models.
Telematik in der Arbeitsmedizin: Praktische Erfahrungen aus einer Machbarkeitsstudie der BGHM
(2019)
Alle Menschen sollen an den sich schnell erweiternden Möglichkeiten, die Gesundheit wiederherzustellen, zu erhalten und zu bessern, in gleicher Weise teilhaben können. Die Diskussion um steigende Ausgaben für Gesundheit, Rationierung von Leistungen, Fachkräftemangel und Disparitäten im Zugang zur Versorgung zeigt aber: Dieses Versprechen steht in Frage.
Eine besser koordinierte, stärker patientenzentrierte und intersektoral angelegte Versorgung kann Teil der Lösung sein, das Versprechen weiter aufrecht zu halten. Voraussetzung hierfür ist ein Vergütungssystem, das die Sektorengrenzen tatsächlich überwinden kann und Qualität belohnt. Internationale Erfahrungen zeigen, dass sogenannte Capitation-Modelle, die auf mengenunabhängigen und sektorenübergreifenden Pro-Kopf-Pauschalen beruhen, – geeignet ausgestaltet – Anreize für eine derartige Versorgung schaffen können. In solchen Modellen übernehmen Leistungserbringer einen Teil des Versicherungsrisikos bzw. der finanziellen Verantwortung für Leistungen, die direkt von ihnen erbracht, veranlasst oder nicht vermieden werden. Das Potenzial ist deutlich sichtbar. Allerdings gibt es auch Herausforderungen und Risiken, die mit einem derartigen System einhergehen und entsprechend zu adressieren bzw. zu kontrollieren sind.
Deshalb prüft das vorliegende Buch differenziert die Voraussetzungen und Potenziale des Transfers eines derartigen populationsorientierten Vergütungsansatzes nach Deutschland und zeigt die Optionen einer möglichen Umsetzung in Form prospektiver regionaler Gesundheitsbudgets auf. Die Basis hierzu bildet eine fundierte Analyse von Modellen aus Spanien, Peru, den USA und der Schweiz.
Die im deutschen Gesundheitssystem implementierten Vergütungssysteme sind dringend reformbedürftig. Dies gilt insbesondere für den Krankenhaussektor, in dem die Auswirkungen diverser Fehlanreize zu einer Kaskade korrigierender Eingriffe geführt haben, ohne jedoch die tiefwurzelnden Probleme grundlegend zu adressieren. Eine alternative Vergütungsform stellen prospektive regionale Gesundheitsbudgets dar. Diese basieren auf Konzepten, die dem Prinzip der Capitation folgen und nicht für einzelne Fälle oder auch einzelne Patienten, sondern für ganze Gruppen von Versicherten eine sektorenübergreifende Vergütung beinhalten. Im Idealfall wird damit die gesamte Bevölkerung einer Region abgedeckt. Die Umsetzung derartiger pauschalierter Vergütungssysteme ist herausfordernd. Deshalb stellt dieser Beitrag Erfahrungen aus Spanien und den USA dar und diskutiert Implikationen für eine mögliche Implementierung in Deutschland. Das spanische Valencia-Modell steht dabei für einen unmittelbaren und weitreichenden Systemwechsel durch die Implementierung von Modellen, bei denen der Staat eine Konzession für die regionale Versorgung an private Akteure vergibt. Der am Beispiel einer Accountable Care Organisation dargestellte Ansatz der USA verfolgt hingegen die Strategie eines Transformationspfades , der schrittweise zu einer stärkeren Pauschalierung führt und kontinuierlich auf Basis aktueller Erkenntnisse angepasst wird. Es zeigt sich, dass die Modelle zwingend für alle Beteiligten einen Zusatznutzen gegenüber dem Status quo stiften müssen, um angenommen zu werden. Auf der wirtschaftlichen Ebene müssen die Risiken adäquat abgesichert werden, ohne dabei die gewünschten Anreize auszuhebeln. Gleichzeitig müssen wirksame Vorkehrungen getroffen werden, die Unterversorgung verhindern und positive Qualitätsanreize schaffen.
1. Understanding and explaining the structure of communities in response to environmental gradients is a central goal in ecology. Trait‐based approaches are promising but yet rarely applied to understand community dynamics in response to changing environmental conditions.
2. Here, we investigate seasonal succession patterns of functional traits in phytoplankton communities and how nutrient reductions (oligotrophication) alter these patterns. We used phytoplankton data from 40 years of observation from the Rappbode Reservoir (Germany), which underwent a strong shift in trophic conditions, and translated taxonomic composition into functional traits by assigning trait values compiled from the literature.
3. All studied traits (morphological, behavioural and physiological traits) responded to changing environmental conditions and showed consistent, reoccurring seasonal developments. The seasonal succession of phytoplankton communities was shaped by a trade‐off between small‐celled, fast‐growing species that are able to rapidly incorporate existing resources (r ‐strategists) and large‐celled species with more complex and efficient mechanisms to exploit scarce mineral nutrients or acquire previously unexploited nutrient pools (k ‐strategists). In summer, when nutrients were scarce, the k ‐strategy was prevailing (important traits: phosphate affinity, nitrogen fixation, motility and mixotrophy). During the rest of the year, nutrients and turbulence were high and r ‐strategists dominated (important traits: maximum growth rate and light affinity).
4. A comparison between eutrophic and oligotrophic years revealed that the main features of functional trait succession were largely preserved, but intra‐annual fluctuations from spring to summer were stronger during eutrophic years. Nutrient reductions mainly affected functional traits and biomass in spring, while in summer the functional community composition changed little.
5. Synthesis. This study provides for the first time a quantitatively supported functional template for trait‐based succession patterns in lakes under different nutrient conditions. By translating taxonomic composition into trait information, we demonstrate that the quantification of functional characteristics enables ecological interpretation of observed community dynamics and provides not only a testable template but also a powerful tool towards a more mechanistic understanding. The quantification of functional traits further improves the predictability of community shifts in response to changing environmental conditions and thus opens new perspectives for predictive limnology using lake ecosystem models.
We employed the well-established Horton-Strahler, hierarchical, stream-order (ω) scheme to investigate scaling of nutrient loads (P and N) from ~845 wastewater treatment plants (WWTPs) distributed along the river network in urbanized Weser River, the largest national basin in Germany (~46K km2; ~8.4 million population). We estimated hydrologic and water quality impacts at the reach- and basin-scales, at two steady river discharge conditions (median flow, QR50; low-flow, QR90). Of the five WWTPs class-sizes (1 ≤ k ≤ 5), ~68% discharge to small low-order streams (ω < 3). We found large variations in capacity to dilute WWTP nutrient loads because of variability in (1) treated wastewater discharge (QU) within and among different class-sizes, and (2) river discharge (QR) within low-order streams (ω < 3) resulting from differences in drainage areas. For QR50, reach-scale water quality impairment assessed by nutrient concentration was likely at 136 (~16%) locations for P and 15 locations (~2%) for N. About 90% of these locations were lower-order streams (ω < 3). At QR50 and only with dilution, basin-scale cumulative nutrient loads from multiple upstream WWTPs increase impaired locations to 266 (~32% of total) for P. Considering in-stream uptake decreased P-impaired streams to 225 (~27%), suggesting the dominant role of dilution in the Weser River basin. Role of in-stream uptake diminished along the flow paths, while dilution in larger streams (4 ≤ ω ≤ 7) minimizes the impact of WWTP loads. Under QR90 conditions [(QR50/QR90) ~ 2.5], water quality impaired locations will likely double for the basin-scale analyses. Long-term water quality data suggested that diffuse sources are the primary contributors for water quality impairments in large streams. Our data-modeling synthesis approach is transferable to other urbanized river basins and extends understanding of point source impacts on water quality across spatial scales.