455 research outputs found
The maximum theoretical performance of unconcentrated solar photovoltaic and thermoelectric generator systems
The maximum efficiency for photovoltaic (PV) and thermoelectric generator
(TEG) systems without concentration is investigated. Both a combined system
where the TEG is mounted directly on the back of the PV and a tandem system
where the incoming sunlight is split, and the short wavelength radiation is
sent to the PV and the long wavelength to the TEG, are considered. An
analytical model based on the Shockley-Queisser efficiency limit for PVs and
the TEG figure of merit parameter is presented. It is shown that for
non-concentrated sunlight, even if the TEG operates at the Carnot efficiency
and the PV performance is assumed independent of temperature, the maximum
increase in efficiency is 4.5 percentage points (pp.) for the combined case and
1.8 pp. for the tandem case compared to a stand alone PV. For a more realistic
case with a temperature dependent PV and a realistic TEG, the gain in
performance is much lower. For the combined PV and TEG system it is shown that
a minimum value is needed in order for the system to be more efficient
than a stand alone PV system.Comment: 6 pages, 5 figure
FruitGrowth - Gasburning in orchards - Environment friendly weed control
Gas burning makes treatment of weed organic. The new ENVO-DAN burner saves 40% gas and treats 1/2 meter in width.It can be mounted on a standard lawn tractor, orchard tractor or a mobile robot. The modular burner system for burning weeds in orchards can be configurated to your needs
Location-Quality-aware Policy Optimisation for Relay Selection in Mobile Networks
Relaying can improve the coverage and performance of wireless access
networks. In presence of a localisation system at the mobile nodes, the use of
such location estimates for relay node selection can be advantageous as such
information can be collected by access points in linear effort with respect to
number of mobile nodes (while the number of links grows quadratically).
However, the localisation error and the chosen update rate of location
information in conjunction with the mobility model affect the performance of
such location-based relay schemes; these parameters also need to be taken into
account in the design of optimal policies. This paper develops a Markov model
that can capture the joint impact of localisation errors and inaccuracies of
location information due to forwarding delays and mobility; the Markov model is
used to develop algorithms to determine optimal location-based relay policies
that take the aforementioned factors into account. The model is subsequently
used to analyse the impact of deployment parameter choices on the performance
of location-based relaying in WLAN scenarios with free-space propagation
conditions and in an measurement-based indoor office scenario.Comment: Accepted for publication in ACM/Springer Wireless Network
How Precisely Can Easily Accessible Variables Predict Achilles and Patellar Tendon Forces during Running?
Patellar and Achilles tendinopathy commonly affect runners. Developing algorithms to predict cumulative force in these structures may help prevent these injuries. Importantly, such algorithms should be fueled with data that are easily accessible while completing a running session outside a biomechanical laboratory. Therefore, the main objective of this study was to investigate whether algorithms can be developed for predicting patellar and Achilles tendon force and impulse during running using measures that can be easily collected by runners using commercially available devices. A secondary objective was to evaluate the predictive performance of the algorithms against the commonly used running distance. Trials of 24 recreational runners were collected with an Xsens suit and a Garmin Forerunner 735XT at three different intended running speeds. Data were analyzed using a mixed-effects multiple regression model, which was used to model the association between the estimated forces in anatomical structures and the training load variables during the fixed running speeds. This provides twelve algorithms for predicting patellar or Achilles tendon peak force and impulse per stride. The algorithms developed in the current study were always superior to the running distance algorithm
Digital news report 2023
The twelfth Digital News Report from the Reuters Institute for the Study of Journalism at the University of Oxford reveals new insights about digital news consumption based on a YouGov survey of over 93,000 online news consumers in 46 media markets
The report provides evidence that news audiences are becoming more dependent on digital and social platforms, putting further pressure on both ad-based and subscription business models of news organisations at a time when both household and company spending is being squeezed. The report documents how video-based content, distributed via networks such as TikTok, Instagram and YouTube are becoming more important for news, especially in parts of the Global South, while legacy platforms such as Facebook are losing influence. Both interest and trust in news continue to fall in many countries as the connection between journalism and much of the public continues to fray
Laser-Annealing and Solid-Phase Epitaxy of Selenium Thin-Film Solar Cells
Selenium has resurged as a promising photovoltaic material in solar cell
research due to its wide direct bandgap of 1.95 eV, making it a suitable
candidate for a top cell in tandem photovoltaic devices. However, the
optoelectronic quality of selenium thin-films has been identified as a key
bottleneck for realizing high-efficiency selenium solar cells. In this study,
we present a novel approach for crystallizing selenium thin-films using
laser-annealing as an alternative to the conventionally used thermal annealing
strategy. By laser-annealing through a semitransparent substrate, a buried
layer of high-quality selenium crystallites is formed and used as a growth
template for solid-phase epitaxy. The resulting selenium thin-films feature
larger and more preferentially oriented grains with a negligible surface
roughness in comparison to thermally annealed selenium thin-films. We fabricate
photovoltaic devices using this strategy, and demonstrate a record ideality
factor of n=1.37, a record fill factor of FF=63.7%, and a power conversion
efficiency of PCE=5.0%. The presented laser-annealing strategy is universally
applicable and is a promising approach for crystallizing a wide range of
photovoltaic materials where high temperatures are needed while maintaining a
low substrate temperature
Co-Chaperones in Targeting and Delivery of Misfolded Proteins to the 26S Proteasome
Protein homeostasis (proteostasis) is essential for the cell and is maintained by a highly conserved protein quality control (PQC) system, which triages newly synthesized, mislocalized and misfolded proteins. The ubiquitin-proteasome system (UPS), molecular chaperones, and co-chaperones are vital PQC elements that work together to facilitate degradation of misfolded and toxic protein species through the 26S proteasome. However, the underlying mechanisms are complex and remain partly unclear. Here, we provide an overview of the current knowledge on the co-chaperones that directly take part in targeting and delivery of PQC substrates for degradation. While J-domain proteins (JDPs) target substrates for the heat shock protein 70 (HSP70) chaperones, nucleotide-exchange factors (NEFs) deliver HSP70-bound substrates to the proteasome. So far, three NEFs have been established in proteasomal delivery: HSP110 and the ubiquitin-like (UBL) domain proteins BAG-1 and BAG-6, the latter acting as a chaperone itself and carrying its substrates directly to the proteasome. A better understanding of the individual delivery pathways will improve our ability to regulate the triage, and thus regulate the fate of aberrant proteins involved in cell stress and disease, examples of which are given throughout the review
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