We demonstrate a genetic method to fabricate large-area nano-structure III-V solar cells with conformal epitaxial growth on pre-patterned substrate. The design, simulation, fabrication, and characterization of a nano-...
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ISBN:
(纸本)9781479933006
We demonstrate a genetic method to fabricate large-area nano-structure III-V solar cells with conformal epitaxial growth on pre-patterned substrate. The design, simulation, fabrication, and characterization of a nano-structure gallium arsenide (GaAs) solar cell device are presented. The optical simulation illustrates that the nano-pyramid array is able to suppress the reflection and enhance the absorption in a wide spectrum range. The iv characterization shows that the short circuit current of the nano-pyramid GaAs solar cell with 200 nm thick junction is as high as 18.5 mA/cm~2, which is more than triple of the planar cell. Our results suggest this nano-structure thin film absorber could significantly reduce epitaxial growth cost and increase yield, thus provides a pathway towards high-efficiency and low-cost solar cells.
The problem of adopting quantum-resistant crypto-graphic network protocols or post-quantum cryptography (PQC) is critically important to democratizing quantum computing. The problem is urgent because practical quantum...
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ISBN:
(数字)9798331541378
ISBN:
(纸本)9798331541385
The problem of adopting quantum-resistant crypto-graphic network protocols or post-quantum cryptography (PQC) is critically important to democratizing quantum computing. The problem is urgent because practical quantum computers will break classical encryption in the next few decades. Past encrypted data has already been collected and can be de-crypted in the near future. The main challenges of adopting post-quantum cryptography lie in algorithmic complexity and hardware/software/network implementation. The grand question of how existing cyberinfrastructure will support post-quantum cryptography remains unanswered. This paper describes: i) the design of a novel Post-Quantum Cryptography (PQC) network instrument placed at the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana-Champaign and a part of the FABRIC testbed; ii) the latest results on PQC adoption rate across a wide spectrum of network protocols (Secure Shell - SSH, Transport Layer Security - TLS, etc.); iii) the current state of PQC implementation in key scientific applications (e.g., OpenSSH or SciTokens); iv) the challenges of being quantum-resistant; and v) discussion of potential novel attacks. This is the first large-scale measurement of PQC adoption at national-scale supercomputing centers and FABRIC testbeds. Our results show that only OpenSSH and Google Chrome have successfully implemented PQC and achieved an initial adoption rate of 0.029 % (6,044 out of 20,556,816) for OpenSSH connections at NCSA coming from major Internet Service Providers or Autonomous Systems (ASes) such as OARNET, GTT, Google Fiber Webpass (U.S.) and Uppsala Lans Landsting (Sweden), with an overall increasing adoption rate year-over-year for 2023–2024. Our analyses identify pathways to migrate current applications to be quantum-resistant.
The use of printed electronics is increasing rapidly and replacing the traditional manufacturing techniques, especially in the consumer electronics sector. In this paper, a closed-loop deep learning approach for corre...
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BL13-XALOC is a Macromolecular Crystallography beamline at the newly built 3-GeV synchrotron ALBA (Barcelona). The optics design is based on an in-vacuum undulator, a Si(111) channel-cut crystal monochromator, and a p...
BL13-XALOC is a Macromolecular Crystallography beamline at the newly built 3-GeV synchrotron ALBA (Barcelona). The optics design is based on an in-vacuum undulator, a Si(111) channel-cut crystal monochromator, and a pair of KB mirrors. The opticaldesign allows three main operation modes: an unfocused configuration, where one or both mirrors are removed from the photon beam path; a focused configuration, where both mirrors can focus the beam to 49×9 μm2 FWHM (H×V), and a defocused configuration that can match the size of the beam to the dimensions of the crystals or to focus it at the detector. To achieve a uniform defocused beam, the slope errors were reduced by using novel method together with our high-accuracy metrology laboratory. Thorough commissioning has also demonstrated that the X-ray beam has excellent energy and spatial stability. The End Station includes a high accuracy single axis diffractometer, a removable mini-kappa goniometer, an automated sample mounting robot and a Pilatus6M, photon-counting detector. This equipment, together with the operation flexibility, allows the beamline to tackle a large variety of crystals, from medium sized crystals with large unit cell parameters to microcrystals. Several examples of high-quality data collections measured during beamline commissioning are described. The beamline started user operation on 18th July 2012.
The optimisation of the support structure of heliostats in concentrating solar power plants is a fundamental task aimed at attempting to reduce the high levelised cost of energy (LCOE) of current configurations. In th...
The optimisation of the support structure of heliostats in concentrating solar power plants is a fundamental task aimed at attempting to reduce the high levelised cost of energy (LCOE) of current configurations. In this work, an integrated multi-objective optimisation framework is presented, which relies on the combination of a lean and fast structural model with a genetic algorithm to simultaneously minimise both the overall mass of the support structure and the mean angle of rotation of the mirror surface, which directly affects the optical efficiency of the component. A particular feature of the proposed framework is that it represents an integrated solution, i.e., it allows to simultaneously optimise the main components of the heliostat support structure, i.e., the pedestal, the truss and the back support structure, assuming they are off-the-shelf components easily available on the market. The optimisation problem is set up selecting as design variables (i) the number of elements in the back support structure and (ii) the relevant characteristics of all the components considered, i.e., section shape and dimensions, according to the components commercial datasheets. At each iteration of the optimisation process, the structural model is fed with the currentdesign variables values and, according to some computed aerodynamic loads, it allows evaluating the displacement and rotation of the points of interest within the mirror surface. An aerodynamic model present in the literature based on experimental wind tunnel tests is used to estimate the wind forces acting on the heliostat as a function both of the mirror inclination angle with respect to the ground and of the wind direction with respect to the mirror orientation. In this work, the proposed methodology is demonstrated on a realistic case study and the results commented in detail, highlighting possible future developments and the limitations of the framework.
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