This paper describes the design and performance of a compact detector, BDX-MINI, that incorporates all features of a concept that optimized the detection of light dark matter in the MeV-GeV mass ...range produced by electrons in a beam dump. It represents a reduced version of the future BDX experiment expected to run at JLAB. BDX-MINI was exposed to penetrating particles produced by a 2.176 GeV electron beam incident on the beam dump of Hall A at Jefferson Lab. The detector consists of 30.5 kg of PbWO
4
crystals with sufficient material following the beam dump to eliminate all known particles except neutrinos. The crystals are read out using silicon photomultipliers. Completely surrounding the detector are a passive layer of tungsten and two active scintillator veto systems, which are also read out using silicon photomultipliers. The design was validated and the performance of the robust detector was shown to be stable during a six month period during which the detector was operated with minimal access.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Nowadays, resilient grids meet growing interest for their capability of let survive critical load even in case of power fault coming from grid disturbance and disasters.
In particular, ...telecommunications infrastructures (point-to-point and cell infrastructure) have distributed systems (RBS, DCs) equipped with storage devices used to guarantee continuous operation of the supplied equipment. Since high value services are provided to a wide set of customers, unexpected service unavailability is source of economic losses.
This embedded UPS function, despite avoiding service interruption and contract penalties to the service providers, requires batteries whose unused capacity could be fruitfully exploited to provide the grid with valuable and paid energy services (frequency regulation - power and/or energy regulation in time slots - peak smoothing).
For this reason, the supply systems of such plants, beside the internal energy storage devices, had better to have redundancy of energy sources (e.g. electrical grid and natural gas network) and tailored power flows control strategies to optimize the equipment utilization and costs, even in the case of external energy shortage.
In this work, a combined approach with Fuel Cell (FC) and Fuzzy Logic (FL) is investigated to determine a good compromise between equipment installation, control logic, and availability of the service (downtime probability), even accounting for weather forecast, energy price and storage system exploitation (depth of discharge).
For the implemented case studies of the simulation, a landline station located in Italy is analyzed by simulating different functions and power equipment to assess the benefits achievable the presented approach.
•UPS hidden capacity exploited to provide grid services even without hardware modifications.•Fuel cell generator allowed to reduce storage capacity and improve system resilience.•Fuzzy logic enhanced the responsivity and resilience of the telecommunications equipment supply.•Overheads and taxes has relevant influence on the overall economic evaluation.
There are more than enough regulations governing food. In addition, the FDA has the authority to implement or amend the regulations or programs as it deems necessary. The current federal regulations ...are adequate and sufficient to protect consumers from foodborne illness. However, narrower and more precise definitional language that would include home delivery services is necessary. The FDA, FSIS, and other federal agencies already have a plan in place to defeat foodborne illness. FSIS's meat and poultry program and the HACCP currently handle the "many matters of importance to the safety and quality of the food supply" and illness prevention. The Food Emergency Response Network deals with all issues related to foodborne illness outbreaks, if the situation should arise, and Congress has delegated its power to several federal agencies in order to improve and implement food safety programs as it sees fit. The seafood HACCP program regulates and provides guidelines for the safe consumption of seafood. Ensuring that all relevant existing regulations accurately define and include meal-kit home delivery services would help close the gap to better ensure the protection of the public from foodborne illness and cross-contamination.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, OILJ, PILJ, PNG, PRFLJ, SAZU, UILJ, UKNU, UL, UM, UPUK, VSZLJ
Electric vehicles, equipped with electrochemical batteries, are expected to significantly penetrate the automotive market in the next few years. Though, the recharge time for battery pack and the ...autonomy range can constitute a limit. An appropriate use of fuel cell technology in electric vehicles can now represent an advantageous choice both from a technical and economic point of view.
This paper reports the results of the development of a hybrid electric city bus, performed by the synergy between fuel cell and batteries. A pure electric city bus, equipped with eight Zebra batteries, was acquired and modified in a fuel cell and batteries hybrid vehicle. In the final version the bus was equipped with six batteries and a hydrogen plant with a proton exchange membrane fuel cell system. In particular an innovative powertrain management, where even the time required for the terminal stops is used to charge the batteries by the fuel cell, is described. Set-up tests on the fuel cell system acquired are presented. Further, tests were conducted also on the battery pack working on board in a real route to demonstrate the capability of the reduced battery pack to drive the vehicle.
•To increase the range of the vehicle a range extender powertrain configuration was chosen.•The powertrain is composed by a FC system, Zebra batteries and an AC induction motor.•The control strategy adopted allows to assure the functionality of the vehicle.
The KM3NeT Collaboration aims to build in the depths of the Mediterranean Sea a neutrino telescope that consists of a kilometer-cube grid of photosensors encapsulated into transparent pressure ...resistant glass spheres. A crucial component of the detector is the acoustic positioning system, which provides the position of photodetectors and structures in the deep sea with an accuracy of about 10 cm. The system is based on measurements of acoustic signals between fixed seabed emitters and receiving hydrophones. A subset of the required acoustic beacons is powered by an autonomous power supply system based on a high-charge battery pack. This paper describes the innovative design used to build the battery packs, derived from the expertise in the construction of underwater detectors encapsulated in glass vessels. The battery pack uses a pressure resistant 17-inch glass sphere as housing, which contains a cluster of 96 batteries properly connected to supply an output DC voltage of 12 V with a total capacity of 410 Ah. The cluster of batteries is surrounded by silicone glue, that stacks all the part together, ensuring mechanical connection with the housing and protecting the batteries against humidity. In order to increase the operating time of the beacon, a custom designed wake-up board is added to implement a duty cycle operating mode. An electronic switch controlled by an ARDUINO microprocessor connects the battery pack to the beacon only for a defined time. So far, 8 supply systems have been deployed at the KM3NeT sites. The beacon battery pack could be easily modified for multipurpose deep-sea applications.
Light dark matter searches with positrons Battaglieri, M.; Bianconi, A.; Bisio, P. ...
European physical journal. A, Hadrons and nuclei,
08/2021, Letnik:
57, Številka:
8
Journal Article
Recenzirano
Odprti dostop
We discuss two complementary strategies to search for light dark matter (LDM) exploiting the positron beam possibly available in the future at Jefferson Laboratory. LDM is a new compelling hypothesis ...that identifies dark matter with new sub-GeV “hidden sector” states, neutral under standard model interactions and interacting with our world through a new force. Accelerator-based searches at the intensity frontier are uniquely suited to explore it. Thanks to the high intensity and the high energy of the Continuous Electron Beam Accelerator Facility (CEBAF) beam, and relying on a novel LDM production mechanism via positron annihilation on target atomic electrons, the proposed strategies will allow us to explore new regions in the LDM parameters space, thoroughly probing the LDM hypothesis as well as more general hidden sector scenarios.
The Muon Portal Project has built a prototype of a real size detector (6m×3m×7 m) for the inspection of containers by muon tomography. This technique may provide 2D and 3D images of the interior of a ...container, to identify the presence of high-Z materials. In the present Project, 4800 extruded scintillator strips were arranged such as to cover four X–Y detection planes (6m×3 m), two placed above and two below the container to be inspected. Silicon photomultipliers were used as photosensors, to collect the light transported by Wave Length Shifter (WLS) fibres embedded in the scintillator strips. First tomographic images are here presented.
The SuperCam instrument onboard the Mars 2020 Perseverance rover investigates Martian geological targets by a combination of multiple spectroscopic techniques. As Raman, Visible‐Infrared ...Spectroscopy, and Laser‐Induced Breakdown Spectroscopy (LIBS) spectra deliver complementary information about the interrogated sample, the multivariate analysis of combined spectroscopic data sets is here proposed as a tool to optimize the SuperCam capability to discriminate mineral phases on Mars. For this purpose, the laboratory study of carbonate phases within the Ca‐Mg‐Fe ternary system were selected as representative case of study. After the characterization of model samples, the discrimination capability of mono analytical Raman, VISIR, and LIBS data sets was evaluated by applying a chemometric approach based on the combination of principal component analysis (for sample clustering) and Linear Discriminant Analysis (for mineral classification). Afterward, the low‐level combination (LL) of Raman, VISIR, and LIBS data was achieved by concatenating their spectra into a single data matrix. The mineral classification achieved by LL data sets outperformed the mono analytical ones, thus proving the complementarity between molecular and elemental spectroscopic techniques. Mineral classification was further improved by using a mid‐level data combination strategy. After evaluating benefits and limitations afforded by the proposed combination strategies, future developments are finally outlined. As such, the final objective of this research line is to develop a classification model based on data combination to optimize the capability of SuperCam in discriminating relevant minerals on Mars, this being a key requirement for the selection of the optimal targets to be cached for the future Mars Sample Return Mission.
Plain Language Summary
The SuperCam instrument onboard the Perseverance rover is capable of analyzing Martian rocks and soils by a combination of Laser‐Induced Breakdown Spectroscopy (LIBS), Raman and Visible‐Infrared Spectroscopy (VISIR). Learning from terrestrial applications, the complementary information provided by the three spectroscopic techniques can be correlated to obtain a more accurate interpretation of the analyzed target. This approach could be particularly useful to discriminate carbonates, which are interesting minerals where to look for traces of past life. Having this in mind, several carbonate samples have been analyzed with laboratory Raman, LIBS, and VISIR instrument. After evaluating the advantages and limitations of each technique, their data were merged by using low‐level and mid‐level strategies that were successfully used previous works. This work proved that, when spectra are combined, the discrimination of carbonate phases is more accurate than when each technique is interpreted separately. This suggests the scientific results obtained by SuperCam on Mars could benefit from the development of tailored classification models based on data combination.
Key Points
Data combination of Raman, Visible‐Infrared Spectroscopy, and Laser‐Induced Breakdown Spectroscopy spectra collected by SuperCam is proposed
Low‐ and mid‐level data combination strategies based on principal component analysis (discrimination) + PC‐Linear Discriminant Analysis (classification are evaluated and compared)
The low‐level combination method outperformed the mono analytical discrimination. The mid‐level one further improved the results
A compact prototype system for H2 production based on a Polymer Electrolyte Membrane (PEM) stack was developed and investigated. A detailed study and an optimization of the Balance of Plant (BoP) was ...carried out. The system was developed in laboratory by using commercial devices tailored around in house-made membrane electrode assemblies (MEAs). The study regarded both the hydraulic circuit efficiency loss and its optimization by varying process parameters. Energy consumption for auxiliary devices was studied at different temperatures (40, 60 and 75 °C). Efficiency and control strategy management of the system were investigated. Despite an increase of stack performance observed at high temperature, maximum system efficiency (65% compared to HHV) was obtained at 40 °C because of moderate energy consumption by the electric heater. To evaluate the stack contribution to the overall efficiency, the present investigation was completed by a hydrodynamic study of the stack inside the system. Diffusional aspects related to the water mass distribution inside the stack were investigated through a computational fluid dynamic analysis (CFD). In particular, a 3D analysis of the whole stack composed by 120 channels and 10 cells was carried out. The model showed a quite uniform distribution of water over the individual channels and a homogeneous pressure inside the cells. Accordingly, the risk of having hot spots and gases accumulated inside the stack was minimal.
•A balance of plant (BOP) study of a proton exchange membrane (PEM) electrolyzer system is carried out.•The system is completely made in house and it has a maximum hydrogen production of 300 Nl/h at 60 A (600 mA/cm2).•System energy consumption is studied at different temperatures (40, 60 and 75 °C).•The study is supplemented by stack computational fluid dynamic analysis (CFD).
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