Bioenergy is one of the main contributors in the renewable energy markets but the quality of solid biomass is often a concern. This study provides an application of the ISO 18135 on biomass sampling, ...evaluating how sampling procedure affects the analytical results and suggesting possible solutions to reach an acceptable level of precision for quality assessment.
A sampling plan compliant with the aforementioned standard was carried out in a 21 MW biomass power plant located in Northern Italy in August and February, collecting samples of different typology from heaps stored in the plant and from trucks coming from suppliers. Moisture content analysis was performed for all the samples, and for those from heaps ash and nitrogen contents were also investigated.
Considering moisture content, to achieve a good precision, a significantly different number of increments are needed in August and February. Regarding ash content, it would be impossible to obtain the precision suggested by the standard, because it would lead to a number of increments not in line with practical operations. Nitrogen content is not a concern in this case, because of the measured low values. In general terms, precision values suggested by ISO 18135 require a high effort by operator and resulted unsuitable in terms of practical application for moisture and ash contents. This is probably due to the different solid biomass considered during the standard development.
For this reason, it is important to assess the quality of the different solid biofuels in order to tune the sampling procedure accordingly.
Considering the ambitious European targets for reducing greenhouse gas emissions the energy production from renewable energy sources is increasing as well as the number of biomass power plants. ...Biomass is a valid alternative to fossil fuels because it is present worldwide and in different forms. Of course, it is important to assess its quality not only for energy characteristics but also for environmental and operational aspects. In this study more than 1700 woodchip samples have been collected in several Italian power plants and the most important physical and chemical parameters have been analyzed to investigate their quality. These data have been compared with the specification expressed in the recently published ISO/TS 17225-9 technical standard. The results show that the ash content is a fundamental and representative parameter for assessing the biofuel quality and that a certain amount of samples has low quality mainly because of their high ash content. In addition, ANOVA results demonstrated that the quality classes expressed in the standard up to 7% ash content are essential in order to meet the needs of the Italian woodchip market. Beyond the value of 7% in ash content, chlorine, sulfur and nitrogen contents increase significantly with consequences for technical and environmental aspects.
•Graphene/silicon Schottky solar cells are realized by cyclododecane transfer method.•Combined effect of graphene doping and double antireflection coating is investigated.•Measured external quantum ...efficiency is the highest ever reported for these devices.•DARC properties are stable over time and not altered by interaction with doping.•DARC permeability to doping allows to recover the loss of efficiency due to ageing.
Few-layer graphene films were grown by chemical vapor deposition and transferred onto n-type crystalline silicon wafers to fabricate graphene/n-silicon Schottky barrier solar cells. In order to increase the power conversion efficiency of such cells the graphene films were doped with nitric acid vapor and an antireflection treatment was implemented to reduce the sunlight reflection on the top of the device. The doping process increased the work function of the graphene film and had a beneficial effect on its conductivity. The deposition of a double antireflection coating led to an external quantum efficiency up to 90% across the visible and near infrared region, the highest ever reported for this type of devices. The combined effect of graphene doping and antireflection treatment allowed to reach a power conversion efficiency of 8.5% exceeding the pristine (undoped and uncoated) device performance by a factor of 4. The optical properties of the antireflection coating were found to be not affected by the exposure to nitric acid vapor and to remain stable over time.
In this paper, we present a wide bandwidth power amplifier (PA) utilizing a Marchand balun to achieve power combining and inverse class-F (class-F -1 ) matching. We have used a 4-to-1 balun and its ...out-of-band characteristics to achieve matching at the second and third harmonic for differential class-F -1 operation. Thus, the balun simultaneously acts as a combiner and harmonic matching network. The experimental results demonstrate that the prototype PA achieves an output power of 41.5 dBm at the 1-dB compression point (P 1 dB ), power-added efficiency of 55%, and gain of 10 dB over a fractional bandwidth of 40% from 8 to 12 GHz. Due to the differential operation, the class-F -1 PA has also achieved a measured second harmonic distortion of -50 dBc.
Introduction
Background: Little is known about the modifications in gambling patterns during the Covid-19 pandemic, which has shown signs of increase, particularly for individuals with preexisting ...gambling problems.
Objectives
Our aim was to assess the behaviour of a cohort of patients in the Trentino Region.
Methods
A semi structured questionnaire containing Hamilton Depression Rating Scale as well as open-ended questions on gambling activities, specifically online gambling, was administred over the telephone. The survey was administred for two months over the lockdown period (april-june 2020) and took approximately 20 minutes to complete.
Results
About 50 responsens were collected. Data are currently been analyzed and will be avaiable at the time of the Congress.
Conclusions
Will be show at the time of the Congress.
Disclosure
No significant relationships.
Abstract This paper describes the results of preliminary thermophysical characterization carried out on recyclable & biobased Fibre Metal Laminates (FML) for lighter, more sustainable & safer battery ...box production, with higher fire resistance. These FMLs are designed to be suitable for the low and medium end automotive. In particular, the specific heat and the thermal conductivity of four different types of FMLs were analysed and assessed depending on temperature. The results show increasing trends of specific heat by increasing temperatures and thermal conductivity values increasing both with temperature and the density of the samples. Further studies will be carried out both to optimise the composition of the FMLs and to provide extensive assessment of the thermal and mechanical properties of the solutions so as to guarantee high thermal and mechanical performances and durability of battery boxes for electric vehicles.
During the past two decades, curriculum restructuring in South Africa has had some unintended consequences; one of these being the unrealistic demands expected from Life Skills (LS) and Life ...Orientation (LO) teachers. Physical Education (PE) finds itself within the multi-faceted subject of LS/LO, therefore the teacher, often without requisite training, has to be accountable for the dissimilar demands of this multidisciplinary subject. The continuing professional development needs are undoubtedly just as diverse as the subject itself is. The aim of the study was to explore an approach for capacitating in-service LS/LO teachers responsible for teaching PE. The research reported in this article employed a qualitative design, which comprised semi-structured interviews with 10 Subject Advisors of LS/LO in the Free State. Themes that emerged from the data analysis were assessment problems, inappropriate allocation of teachers; rotation of teachers; and lack of knowledge and understanding; which culminates in the need for in-service training. The results of this study indicate the necessity for re-skilling of in-service LS/LO teachers and propose an approach for a re-skilling programme to equip these teachers with the essential knowledge and skills to teach PE proficiently.
Titania nanotubes (TNT), thanks to their semiconducting properties, have received wide attention for application in many fields such as photoelectrolysis, dye sensitized solar cells, photocatalysis, ...and sensors. In this work, highly ordered TNT were grown by controlled electrochemical anodization of titanium sheets. Scanning electron microscope equipped with a field emission gun and electrochemical DC/AC techniques was used to characterize the TNT. Semiconducting properties were investigated through linear sweep voltammetry and electrochemical impedance spectroscopy. Donor concentration (Ned) was obtained by recording Mott–Schottky plots. The high Ned of TNT (around 1026m−3) allows an optimal electron transfer when used as photoelectrode. Frequency dispersion of flat band potential from Mott–Schottky plots (−0.38÷+0.40V vs. saturated calomel electrode, SCE) was used as an indicator of the amorphous semiconductor behaviour. The dispersion of flat band in heat treated samples was extremely reduced (0.48–0.51V vs. SCE) because of the conversion to crystalline semiconductor. The depth of space charge was comparable to the TNT wall thickness, meaning that the entire TiO2 nanotube walls formed the space charge layer. Considering the high charge carrier concentration, we can hypothesise a high density of electronic defects (e.g., surface states) that enhances the electron transport by percolation inside a porous photoelectrode. The transition from amorphous to crystalline structure of TNT was detected from the change of semiconducting properties and confirmed by Raman spectroscopy.
•Highly ordered self-assembled TiO2 nanotubes were synthesized by electrochemical anodization.•The electrochemical and semiconducting properties were studied.•An electrical model was developed for titania nanotubes/electrolyte interface.•Thermal treatment changed electronic properties of TiO2 nanotubes.•Transition from amorphous to crystalline structure determined by electrochemical tests