cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Life Cycle Assessment (LCA) of an air-cooled ORC system for waste heat recovery
Creators: name: Oehler, Maximilian
name: Bederna, Benedikt Gregor
name: Barta, Riley Bradley
name: Hesse, Ullrich
Publisher: name: Technical University of Munich
Year: 2021

description: Organic Rankine Cycle (ORC) systems enable locally emission-free power generation. Nevertheless, they cause emissions and resource consumption during their life cycle. Life cycle assessment (LCA) according to ISO 14044 allows identification of key environmental impacts caused by a product. An LCA was carried out for a direct air-cooled ORC system applied to recover waste heat. As working fluid R-245fa was considered and the nominal generator output was set to 100 kWel. A volumetric expander with a fixed volume ratio was assumed. The simplified thermodynamic cycle was modelled for a source temperature of 130 °C. On this basis, commercially available components were selected according to publicly available data. The inventory analysis was carried out with simple mass fraction inventory of the mainly used materials. Subsequently, the reduced manufacturing processes were implemented using the integrated database of the LCA software GaBi Education. Scenarios were defined for the lifetime of the system and full load operation hours per year, which resulted in different amounts of electricity provided by the system. The life cycle impact assessment was carried out using the ReCiPe 2016 method, including 18 impact categories. Results for each scenario were calculated for the entire system and all results were standardized related to the functional unit of kWhel. Three substantial results were derived. First, the greenhouse gas emissions of the ORC system were significantly increased due to the unavoidable losses of R-245fa during the life cycle. These emissions of the working fluid significantly exceeded those from manufacturing of the system. Second, environmental impacts such as climate change, ionizing radiation, terrestrial acidification, water usage, and fine particulate matter formation were found to be higher compared to electricity generation by wind power if the full load operation hours remain low. Third, a reduction of environmental impacts could be achieved if low global warming potential fluids are used, resource-saving production processes are chosen, a hermetic design is implemented, and full-load operation hours are increased.
Preliminary operation assessment of a two-stage ORC engine combined with evacuated tube solar collectors throughout Greece
Creators: name: Soulis, Konstantinos
name: Manolakos, Dimitrios
name: Ntavou, Erika
name: Kosmadakis, George
Publisher: name: Technical University of Munich
Year: 2021

description: A solar two-stage Organic Rankine Cycle (ORC) engine designed, constructed and experimentally tested in authors’ previous work, is hereby evaluated for operation in a wide set of representative locations distributed throughout Greece. The simulation model gathers daily meteorological data for the areas of interest for a thirty-four years reference period. The produced power and operational efficiency of the integrated system that includes the solar collectors combined with the ORC engine is then calculated, with the use of already existing experimental data. The installation, operational and maintenance cost of the integrated system is calculated at current prices for its lifespan and the cost of every produced kWh is presented in maps for the entire country. Finally, the effect of climate variability on energy production performance and the presence of trends were investigated as well. The results show that there is a great spatial variability on the received solar radiation, the thermal energy and the power production in comparison to the relatively small size of the country and this variation is not only a function of the latitude. The energy cost varies considerably between 0.41 and 0.7 €/kWh throughout the country. The great variance and the complexity of the factors influencing the cost of the produced energy highlight the importance of geospatial analysis approaches to assess renewable energy potential and to support technoeconomic analysis and feasibility studies. The proposed approach was proven to be an effective tool for the assessment of the feasibility and potential of a solar heat-to-power engine for Greece and to be expanded in other regions as well.
Rydberg States of H$_3$ and HeH as Potential Coolants for Primordial Star Formation
Creators: name: Kannan, Gokul
name: Chien, Jeremy R.
name: Benjamin, Anthony J.
name: Bhatia, Niranjan
name: Saykally, Richard J.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Current theory and measurements establish the age of the universe as ca. 13.8 billion years. For the first several hundred million years of its existence, it was a dark, opaque void. After that, the hydrogen atoms comprising most of the "ordinary" matter began to condense and ionize, eventually forming the first stars that would illuminate the sky. Details of how these "primordial" stars formed have been widely debated, but remain elusive. A central issue in this process is the mechanism by which the primordial gas (mainly hydrogen and helium atoms) collected via the action of dark matter cools and further accretes to fusion densities. Current models invoke collisional excitation of H$_2$ molecular rotations and subsequent radiative rotational transitions allowed by the weak molecular quadrupole moment. In this article, we review the salient considerations, and present some new ideas, bases on recent spectroscopic observations of neutral H$_3$ Rydberg electronic state emission in the mid-infrared.
Additional file 1 of Optimizing exoskeleton assistance to improve walking speed and energy economy for older adults
Creators: name: Lakmazaheri, Ava
name: Song, Seungmoon
name: Vuong, Brian B.
name: Biskner, Blake
name: Kado, Deborah M.
name: Collins, Steven H.
Publisher: name: figshare
Year: 2024
Subjects: subject: Space Science
subject: Medicine
subject: Physiology
subject: FOS: Biological sciences
subject: Pharmacology
subject: Biotechnology
subject: Sociology
subject: FOS: Sociology
subject: Biological Sciences not elsewhere classified
subject: Science Policy

description: Additional file 1: Figure S1 shows self-selected walking speed, metabolic cost, and metabolic cost of transport data during zero-torque and optimized torque conditions for each participant. Figure S2 shows self-selected walking speed, metabolic cost, and metabolic cost of transport data during normal shoes and optimized torque conditions for each participant. Figure S3 shows optimized exoskeleton mechanics for each participant. Figure S4 shows individual participant data of step frequency variability in repeated generic torque conditions. Figure S5 shows individual participant data of de-trended step frequency variability in repeated generic torque conditions. Table S1 provides optimized torque parameters for each participant, Table S2 provides step frequency data (strides/min), Table S3 provides step frequency variability data (strides/min), Table S4 provides step length data (m), Table S5 provides step width data (m), and Table S6 provides stance duration data (% stride) for each participant during normal shoes, zero-torque, and optimized torque conditions
Democratizing Facial Recognition with Google Glass
Creators: name: Krach, Jeremy
Publisher: name: Digital Repository at the University of Maryland
Year: 2015

description: Lightweight and camera-equipped wearable devices such as Android-backed
Google Glass— with their potential for wide-spread and mobile data
capture—have piqued the imagination of technologists and privacy
advocates alike. This paper describes an experimental system which
confirms the feasibility of such devices for surveillance through live
data collection and facial recognition. Furthermore, even though
effective surveillance tasks are computationally demanding, this work
illustrates that performance of such systems is scalable through careful
architecting of communication between static servers and mobile
collection devices. When the bulk of the complexity can be offloaded to
the server, and with the availability of highly-available communication
channels between collector and processor, we have the foundation upon
which future surveillance systems might be constructed. Such systems
awaken nightmares for those advocating privacy of the modern citizen,
while inspiring innovators to push forward the bounds of what can be
accomplished with today’s technology. The present project enables
advocates from both ends of the spectrum to debate privacy policy as it
can be seen through the lens of systems that are possible today.
On double cosets of groups $GL(n)$ with respect to subgroups of block strictly triangular matrices
Creators: name: Neretin, Yury A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Group Theory (math.GR)
subject: Rings and Algebras (math.RA)
subject: Representation Theory (math.RT)
subject: FOS: Mathematics
subject: 15A21, 43A85

description: We parametrize the space of double cosets of the group $GL(n,\Bbbk)$ with respect to two subgroups $T_-$, $T_+$ of block strictly triangular matrices. In Addendum, we consider the quasi-regular representation of $GL(n,\Bbb{C})$ in $L^2$ on $T_- \ GL(n,\Bbb{C})$, observe that it admits an additional group of symmetries, find the joint spectrum, and observe that it is multiplicity free.
description: 13p
Magnetotransport in a double quantum wire: Modeling using a scattering formalism built on the Lippmann-Schwinger equation
Creators: name: Gudmundsson, Vidar
name: Tang, Chi-Shung
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We model electronic transport through a double quantum wire in an external homogeneous perpendicular magnetic field using a scattering formalism built on the Lippmann-Schwinger equation. In the scattering region a window is opened between the parallel wires allowing for inter- and intra-wire scattering processes. Due to the parity breaking of the magnetic field the ensuing subband energy spectrum of the double wire system with its regimes of hole- and electron-like propagating modes leads to a more structure rich conductance as a function of the energy of the incoming waves than is seen in a single parabolically confined quantum wire. The more complex structure of the evanescent modes of the system also leaves its marks on the conductance.
description: RevTeX, 8 pages with 10 included postscript figures, high resolution version available at http://hartree.raunvis.hi.is/~vidar/Rann/DW_VGCST_06.pdf
Disk-jet coupling changes as a possible indicator for outbursts from GX 339-4 remaining within the X-ray hard state
Creators: name: de Haas, S. E. M.
name: Russell, T. D.
name: Degenaar, N.
name: Markoff, S.
name: Tetarenko, A. J.
name: Tetarenko, B. E.
name: Eijnden, J. van den
name: Miller-Jones, J. C. A.
name: Parikh, A. S.
name: Plotkin, R. M.
name: Sivakoff, G. R.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We present quasi-simultaneous radio, (sub-)millimetre, and X-ray observations of the Galactic black hole X-ray binary GX 339-4, taken during its 2017--2018 outburst, where the source remained in the hard X-ray spectral state. During this outburst, GX 339-4 showed no atypical X-ray behaviour that may act as a indicator for an outburst remaining within the hard state. However, quasi-simultaneous radio and X-ray observations showed a flatter than expected coupling between the radio and X-ray luminosities (with a best fit relation of $L_{\rm radio} \propto L_{\rm X}^{0.39 \pm 0.06}$), when compared to successful outbursts from this system ($L_{\rm radio} \propto L_{\rm X}^{0.62 \pm 0.02}$). While our 2017--2018 outburst data only span a limited radio and X-ray luminosity range ($\sim$1 order of magnitude in both, where more than 2-orders of magnitude in $L_{\rm X}$ is desired), including data from other hard-only outbursts from GX 339-4 extends the luminosity range to $\sim$1.2 and $\sim$2.8 orders of magnitude, respectively, and also results in a flatter correlation (where $L_{\rm radio} \propto L_{\rm X}^{0.46 \pm 0.04}$). This result is suggestive that for GX 339-4 a flatter radio -- X-ray correlation, implying a more inefficient coupling between the jet and accretion flow, could act as an indicator for a hard-only outburst. However, further monitoring of both successful and hard-only outbursts over larger luminosity ranges with strictly simultaneous radio and X-ray observations is required from different, single sources, to explore if this applies generally to the population of black hole X-ray binaries, or even GX 339-4 at higher hard-state luminosities.
description: 14 pages, 9 figures, 4 tables. All data is provided in the appendices, accepted for publication in MNRAS
Model Dependence of Bayesian Gravitational-Wave Background Statistics for Pulsar Timing Arrays
Creators: name: Hazboun, Jeffrey S.
name: Simon, Joseph
name: Siemens, Xavier
name: Romano, Joseph D.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Physical sciences

description: Pulsar timing array (PTA) searches for a gravitational-wave background (GWB) typically include time-correlated "red" noise models intrinsic to each pulsar. Using a simple simulated PTA dataset with an injected GWB signal we show that the details of the red noise models used, including the choice of amplitude priors and even which pulsars have red noise, have a striking impact on the GWB statistics, including both upper limits and estimates of the GWB amplitude. We find that the standard use of uniform priors on the red noise amplitude leads to 95% upper limits, as calculated from one-sided Bayesian credible intervals, that are less than the injected GWB amplitude 50% of the time. In addition, amplitude estimates of the GWB are systematically lower than the injected value by 10-40%, depending on which models and priors are chosen for the intrinsic red noise. We tally the effects of model and prior choice and demonstrate how a "dropout" model, which allows flexible use of red noise models in a Bayesian approach, can improve GWB estimates throughout.
description: 18 pages, 5 figures
Degeneracy of Decadent Dyons
Creators: name: Dabholkar, Atish
name: Narayan, K.
name: Nampuri, Suresh
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: A quarter-BPS dyon in $\mathcal{N}=4$ super Yang-Mills theory is generically `decadent' in that it is stable only in some regions of the moduli space and decays on submanifolds in the moduli space. Using this fact, and from the degeneracy of the system close to the decay, a new derivation for the degeneracy of such dyons is given. The degeneracy obtained from these very simple physical considerations is in precise agreement with the results obtained from index computations in all known cases. Similar considerations apply to dyons in $\mathcal{N}=2$ gauge theories. The relation between the $\mathcal{N} =4 $ field theory dyons and those counted by the Igusa cusp form in toroidally compactified heterotic string is elucidated.
description: Some typos corrected and references added
Reading-out the state of a flux qubit by Josephson transmission line solitons
Creators: name: Fedorov, Arkady
name: Shnirman, Alexander
name: Schön, Gerd
name: Kidiyarova-Shevchenko, Anna
Publisher: name: arXiv
Year: 2006
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We describe the read-out process of the state of a Josephson flux qubit via solitons in Josephson transmission lines (JTL) as they are in use in the standard rapid single flux quantum (RSFQ) technology. We consider the situation where the information about the state of the qubit is stored in the time delay of the soliton. We analyze dissipative underdamped JTLs, take into account their jitter, and provide estimates of the measuring time and efficiency of the measurement for relevant experimental parameters.
description: 13 pages, 12 figures
Additional file 1 of Incidence of urinary incontinence after hip fracture surgery and associated risk factors: a prospective study
Creators: name: Arroyo-Huidobro, Marta
name: de la Fuente, Josefa López
name: Pagespetit, Mar Riera
name: Perez, Oscar Macho
name: Morera, Jaume Roig
name: López, Anna Maria Abelleira
name: Casanova, David Aivar
name: Garcia-Lerma, Esther
name: Pérez-López, Carlos
name: Rodríguez-Molinero, Alejandro
Publisher: name: figshare
Year: 2024
Subjects: subject: Medicine
subject: Cell Biology
subject: Biotechnology
subject: Developmental Biology
subject: Marine Biology
subject: Cancer
subject: Science Policy
subject: Mental Health
subject: Hematology
subject: Infectious Diseases
subject: FOS: Health sciences

description: Supplementary Material 1
Improving the off-design efficiency of ORC bottoming cycle by variable area nozzle turbine technology
Creators: name: Motamed, Mohammad Ali
name: Nord, Lars O.
Publisher: name: Technical University of Munich
Year: 2021

description: Organic Rankine cycles (ORCs) are expected to operate more at varied working conditions, especially when rapid growth in renewable energies put power generation technologies in variable load operation. A power cycle works with lower efficiency in part loads than expected in full load condition. Here, an organic Rankine bottoming cycle with a control strategy based on variable geometry turbine technology is proposed to boost part load efficiency of combined cycles offshore. The Variable Area Nozzle (VAN) turbine is selected to control cycle mass flow rate and pressure ratio independently. A design methodology is presented, and the performance of proposed design and developed control strategy is assessed by an in-house developed tool. With the suggested solution, part load ORC efficiency is kept close to design values while clearly outperforming the reference case with sliding pressure operation. The proposed solution assures efficient operation in a wide range of loads. The combined cycle efficiency showed a clear improvement compared to the reference case, resulting in thousands of tonnes of annual CO2 (carbon dioxide) emission reduction. Compactness, autonomous operation, and acceptable technology readiness level for VAN turbine solution facilitate application of presented design to offshore oil and gas installations.
A Possible Link Between the Galactic Center HESS Source and Sgr A*
Creators: name: Ballantyne, D. R.
name: Melia, Fulvio
name: Liu, Siming
name: Crocker, Roland M.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Recently, HESS and other air Cerenkov telescopes have detected a source of TeV gamma-rays coincident with the Galactic center. It is not yet clear whether the gamma-rays are produced via leptonic or hadronic processes, so it is important to consider possible acceleration sites for the charged particles which produce the gamma-rays. One exciting possibility for the origin of these particles is the central black hole, Sgr A*, where the turbulent magnetic fields close to the event horizon can accelerate protons to TeV energies. Using a realistic model of the density distribution in a 6 pc x 6 pc x 6pc cube at the Galactic center, we here calculate the trajectories followed by these TeV protons as they gyrate through the turbulent medium surrounding Sgr A*. Diffusing out from the black hole, the protons produce TeV gamma-rays via pi^0 decay following a collision with a proton in the surrounding medium. After following over 222,000 such trajectories, we find that the circumnuclear ring around Sgr A* can reproduce the observed 0.1-100 TeV HESS spectrum and flux if the protons are injected into this medium with an effective power-law index of 0.75, significantly harder than the observed photon index of 2.25. The total energy in the steady-state 1-40 TeV proton population surrounding Sgr A* is inferred to be approx 5x10^{45} ergs. Only 31% of the emitted 1-100 TeV protons encounter the circumnuclear torus, leaving a large flux of protons that diffuse outward to contribute to the Galactic ridge emission observed by HESS on scales of >~ 1 degree.
description: 4 pages, 2 figures, accepted to ApJ Letters
Fractional Generalization of Gradient and Hamiltonian Systems
Creators: name: Tarasov, Vasily E.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Dynamical Systems (math.DS)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Chaotic Dynamics (nlin.CD)
subject: Classical Physics (physics.class-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We consider a fractional generalization of Hamiltonian and gradient systems. We use differential forms and exterior derivatives of fractional orders. We derive fractional generalization of Helmholtz conditions for phase space. Examples of fractional gradient and Hamiltonian systems are considered. The stationary states for these systems are derived.
description: 16 pages
Fractional corner magnetization of collinear antiferromagnets
Creators: name: Watanabe, Haruki
name: Kato, Yasuyuki
name: Po, Hoi Chun
name: Motome, Yukitoshi
Publisher: name: arXiv
Year: 2021
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Recent studies revealed that the electric multipole moments of insulators result in fractional electric charges localized to the hinges and corners of the sample. We here explore the magnetic analog of this relation. We show that a collinear antiferromagnet with spin $S$ defined on a $d$-dimensional cubic lattice features fractionally quantized magnetization $M_{\text{c}}^z=S/2^d$ at the corners. We find that the quantization is robust even in the presence of gapless excitations originating from the spontaneous formation of the Néel order, although the localization length diverges, suggesting a power-law localization of the corner magnetization. When the spin rotational symmetry about the $z$ axis is explicitly broken, the corner magnetization is no longer sharply quantized. Even in this case, we numerically find that the deviation from the quantized value is negligibly small based on quantum Monte Carlo simulations.
description: 10 pages, 7 figures
Optimal Scheduling of Integrated Demand Response-Enabled Community Integrated Energy Systems in Uncertain Environments
Creators: name: Li, Yang
name: Wang, Bin
name: Yang, Zhen
name: Li, Jiazheng
name: Li, Guoqing
Publisher: name: arXiv
Year: 2021
Subjects: subject: Systems and Control (eess.SY)
subject: Signal Processing (eess.SP)
subject: Optimization and Control (math.OC)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Mathematics

description: The community integrated energy system (CIES) is an essential energy internet carrier that has recently been the focus of much attention. A scheduling model based on chance-constrained programming is proposed for integrated demand response (IDR)-enabled CIES in uncertain environments to minimize the system operating costs, where an IDR program is used to explore the potential interaction ability of electricity-gas-heat flexible loads and electric vehicles. Moreover, power to gas (P2G) and micro-gas turbine (MT), as links of multi-energy carriers, are adopted to strengthen the coupling of different energy subsystems. Sequence operation theory (SOT) and linearization methods are employed to transform the original model into a solvable mixed-integer linear programming model. Simulation results on a practical CIES in North China demonstrate an improvement in the CIES operational economy via the coordination of IDR and renewable uncertainties, with P2G and MT enhancing the system operational flexibility and user comprehensive satisfaction. The CIES operation is able to achieve a trade-off between economy and system reliability by setting a suitable confidence level for the spinning reserve constraints. Besides, the proposed solution method outperforms the Hybrid Intelligent Algorithm in terms of both optimization results and calculation efficiency.
description: Accepted by IEEE Transactions on Industry Applications
HyDelta 1.0 Second plenary progress meeting - 07-12-2021
Creators: name: HyDelta
Publisher: name: Zenodo
Year: 2021
Subjects: plenary progress meeting
presentation
hydrogen blending
hydrogen in the gas grid
hydelta
results

description: The complete slide deck of the HyDelta Plenary Progress Meeting 2, which took place online on 07-12-2021. The recording of the webinar can be found here: https://attendee.gotowebinar.com/recording/1094731370769472259
description: Dit project is medegefinancierd door TKI Nieuw Gas | Topsector Energie uit de PPS-toeslag onder referentienummer TKI2020-HyDelta.
Additional file 1 of Health support of people with intellectual disability and the crucial role of support workers
Creators: name: Nijhof, Kim
name: Boot, Fleur H.
name: Naaldenberg, Jenneken
name: Leusink, Geraline L.
name: Bevelander, Kirsten E.
Publisher: name: figshare
Year: 2024
Subjects: subject: Medicine
subject: Sociology
subject: FOS: Sociology
subject: Information Systems not elsewhere classified
subject: Cancer
subject: Science Policy
subject: Mental Health
subject: Computational Biology

description: Additional file 1: Focus group guide
25 Orionis: A Kinematically Distinct 10 Myr Old Group in Orion OB1a
Creators: name: Briceno, Cesar
name: Hartmann, Lee
name: Hernandez, Jesus
name: Calvet, Nuria
name: Vivas, A. Katherina
name: Furesz, Gabor
name: Szentgyorgyi, Andrew
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We report here on the photometric and kinematic properties of a well defined group of nearly 200 low-mass pre-main sequence stars, concentrated within ~ 1 deg of the early-B star 25 Ori, in the Orion OB1a sub-association. We refer to this stellar aggregate as the 25 Orionis group. The group also harbors the Herbig Ae/Be star V346 Ori and a dozen other early type stars with photometry, parallaxes, and some with IR excess emission, consistent with group membership. The number of high and low-mass stars is in agreement with expectations from a standard Initial Mass Function. The velocity distribution for the young stars in 25 Ori shows a narrow peak centered at 19.7 km/s, very close to the velocity of the star 25 Ori. Our results provide new and compelling evidence that the 25 Ori group is a distinct kinematic entity, and that considerable space and velocity structure is present in the Ori OB1a sub-association. The low-mass members follow a well defined band in the color-magnitude diagram, consistent with an isochronal age of ~ 7-10 Myr, depending on the assumed evolutionary model. The highest density of members is located near the star 25 Ori, but the actual extent of the cluster cannot be well constrained with our present data. In a simple-minded kinematic evolution scenario, the 25 Ori group may represent the evolved counterpart of a younger aggregate like the sigma Ori cluster. The 25 Ori stellar aggregate is the most populous ~ 10 Myr sample yet known within 500 pc, setting it as an excellent laboratory to study the evolution of solar-like stars and protoplanetary disks.
description: 28 pages, 5 figures. Astrophysical Journal, in press. Abridged abstract
The Bioleaching of copper sulfide ores in saline media : shake flask studies
Creators: name: Lo, Michael Joseph
Publisher: name: University of British Columbia
Year: 2009

description: The feasibility of bioleaching two Chilean copper ores under saline conditions was evaluated by batch tests. Total copper content of the ores were 3.87% and 1.64%, respectively. Lower ore mineralogy was comprised of atacamite, chrysocolla, bornite, chalcopyrite, chalcocite, and minor pyrite, while Zaldivar's included brochantite, chrysocolla, chalcocite, and pyrite. Mixed bacterial cultures dominated by Thiobacillus ferrooxidans were used in all test work. As the effect of chloride ion on copper extraction was of primary concern, shake flask tests at various chloride levels were conducted. Sterile (no bacteria) tests were run under conditions identical to corresponding bioleach tests to provide information on abiotic leaching. All bioleach tests demonstrated, by attaining high Eh levels, that adaptation occurred at all chloride levels tested. On initial exposure to concentrations above baseline culture tolerance, inhibition occurred, manifesting as lengthier lag times, the severity increasing with the difference in chloride concentration between culture tolerance level and the level in the test medium. With repeated exposure to media containing identical chloride levels, lag times decreased, demonstrating further evidence of bacterial adaptation to chloride ion. Successful adaptation by bacteria was reflected by high copper extractions at all chloride levels for the bioleach tests, averaging 91.9% (Lower (CI) test series) and 94.5% (Zaldivar (CI) test series). As expected, the corresponding sterile tests did not achieve the same level of extraction, averaging 43.6% (Lower (CI)) and 82.0% (Zaldivar (CI)). Clearly, the Zaldivar ore was much more reactive to abiotic leaching than the Lower ore. While chloride-enhanced cupric-ion leaching was a factor for both sets of sterile tests, other factors may also have enhanced abiotic Zaldivar ore leaching. These factors are believed to include (a) conspicuous differences in mineralogical content and distribution, (b) apparently more acid-soluble copper mineralization, and (c) chloride-enhanced galvanic leaching.
Thermodynamic evaluation of an ORC test rig - from comprehensive experimental results to a simulation model
Creators: name: Popp, Tobias
name: Heberle, Florian
name: Weiß, Andreas P.
name: Brüggemann, Dieter
Publisher: name: Technical University of Munich
Year: 2021

description: Organic Rankine Cycle (ORC) systems are a widespread technology for recovering the waste heat of low to medium temperature energy sources. Despite the fact that they are commercially used in a wide range of applications, the data situation concerning the thermodynamic performance of the different components of those plants is rather poor, especially regarding part-load operation. In the scope of the present paper, comprehensive experimental results of an ORC test rig with hexamethyldisiloxane (MM) as working fluid and a Quasi-Impulse Cantilever turbine as expansion machine are presented. For preheating, evaporating and superheating the working fluid, a Plate Shell heat exchanger was applied. Exhaust gas from a propane gas burner served the test rig as heat source. At design point, MM was evaporated at a pressure level of 6 bar. By expanding the working fluid to 0.32 bar, an electrical power output of approx. 12 kW was generated. All main components of the cycle, i.e. heat exchangers, feed pump and turbine, were analyzed concerning their thermodynamic operational behavior. Part-load operating points down to 50% of the ORC design mass flow rate were considered. Due to the fixed swallowing capacity of the used turbine, a decrease in mass flow rate was always associated with a drop of the evaporation pressure of the cycle. Experimental results for each component of the ORC system were analyzed. The corresponding off-design characteristics were implemented in a commercial cycle modelling tool for quasi-stationary simulations. Hence, a digital twin of the experimental test rig was provided. In this simulation model, it could be shown that WHR efficiency at 50% design mass flow rate could be improved from 4.6% to 7.2% by substituting the fixed geometry turbine by one with adjustable swallowing capacity.
Manipulation of ultracold atoms in dressed adiabatic radio frequency potentials
Creators: name: Lesanovsky, I.
name: Hofferberth, S.
name: Schmiedmayer, J.
name: Schmelcher, P.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We explore properties of atoms whose magnetic hyperfine sub-levels are coupled by an external magnetic radio frequency (rf) field. We perform a thorough theoretical analysis of this driven system and present a number of systematic approximations which eventually give rise to dressed adiabatic radio frequency potentials. The predictions of this analytical investigation are compared to numerically exact results obtained by a wave packet propagation. We outline the versatility and flexibility of this new class of potentials and demonstrate their potential use to build atom optical elements such as double-wells, interferometers and ringtraps. Moreover, we perform simulations of interference experiments carried out in rf induced double-well potentials. We discuss how the nature of the atom-field coupling mechanism gives rise to a decrease of the interference contrast.
The spectrum of the Broad Line Region and the high-energy emission of powerful blazars
Creators: name: Tavecchio, F.
name: Ghisellini, G.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: High-energy emission (from the X-ray through the gamma-ray band) of Flat Spectrum Radio Quasars is widely associated with the inverse Compton (IC) scattering of ambient photons, produced either by the accretion disk or by the Broad Line Region, by high-energy electrons in a relativistic jet. In the modelling of the IC spectrum one usually adopts a simple black-body approximation for the external radiation field, though the real shape is probably more complex. The knowledge of the detailed spectrum of the external radiation field would allow to better characterize the soft-medium X-ray IC spectrum, which is crucial to address several issues related to the study of these sources. Here we present a first step in this direction, calculating the IC spectra expected by considering a realistic spectrum for the external radiation energy density produced by the BLR, as calculated with the photoionization code CLOUDY. We find that, under a wide range of the physical parameters characterizing the BLR clouds, the IC spectrum calculated with the black-body approximation reproduces quite well the exact spectrum for energies above few keV. In the soft energy band, instead, the IC emission calculated using the BLR emission shows a complex shape, with a moderate excess with respect to the approximate spectrum, which becomes more important for decreasing values of the peak frequency of the photoionizing continuum. We also show that the high-energy spectrum shows a marked steepening, due to the energy dependence of the scattering cross section, above a characteristic energy of 10-20 GeV, quasi independent on the Lorentz factor of the jet.
description: 10 pages, 9 figures, accepted for publication in MNRAS
The spaces of dyadic distributions
Creators: name: Protasov, Vladimir
name: Karapetyants, Mikhail
Publisher: name: arXiv
Year: 2020
Subjects: subject: Functional Analysis (math.FA)
subject: FOS: Mathematics

description: In this paper subdivision schemes, which are used for functions approximation and curves generation, are considered. In classical case, for the functions defined on the real line, the theory of subdivision schemes is widely known due to multiple applications in constructive approximation theory, signal processing as well as for generating fractal curves and surfaces. Subdivision schemes on a dyadic half-line, which is the positive half-line, equipped with the standard Lebesgue measure and the digitwise binary addition operation, where the Walsh functions play the role of exponents, are defined and studied. Necessary and sufficient convergence conditions of the subdivision schemes in terms of spectral properties of matrices and in terms of the smoothness of the solution of the corresponding refinement equation are proved. The problem of the convergence of subdivision schemes with non-negative coefficients is also investigated. Explicit convergence criterion of the subdivision schemes with four coefficients is obtained. As an auxiliary result fractal curves on a dyadic half-line are defined and the formula of their smoothness is proved. The paper contains various illustrations and numerical results.
La démocratie menacée? Résilience des institutions représentatives
Creators: name: Manin, Bernard
Publisher: name: Università degli Studi di Urbino Carlo Bo
Year: 2015

description: Les démocraties représentatives sont, de nos jours, confrontées à des transformations majeures apportées par les procès de globalisation, l’affirmation de nouvelles technologies de communication et par la diffusion d’un discrédit croissant du personnel politique. Ces transformations semblent affecter les mécanismes centraux de la démocratie représentative. Dès lors, on peut légitimement se demander si elles parviendront à y faire face. Mais il faut observer que les institutions représentatives ont montré jusqu’ici une remarquable résilience, soit une grande capacité d’adaptation  aux changements. Conséquente à quatre facteurs cruciaux, qui concernent l’idée de représentation, l’élection, l’indétermination partielle et l’incomplétude du dispositif représentatif. Les institutions représentatives ne relèvent pas de la géométrie politique ; elles procèdent plutôt d’une raison prudentielle : c’est là une autre source de leur adaptabilité et, du coup, de leur longévité.
description: Argomenti, N° 1 (2015): maggio-agosto
Covers and the curve complex
Creators: name: Rafi, Kasra
name: Schleimer, Saul
Publisher: name: arXiv
Year: 2007
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics
subject: 57M99; 30F99

description: We provide the first non-trivial examples of quasi-isometric embeddings between curve complexes. These are induced either by puncturing a closed surface or via orbifold coverings. As a corollary, we give new quasi-isometric embeddings between mapping class groups.
description: 12 pages, no figures. Added application to mapping class groups
Hop-by-hop Accounting and Rewards for Packet dIspAtching
Creators: name: Machado, Caciano
name: Santos, Renan R. S. dos
name: Westphall, Carla Merkle
Publisher: name: arXiv
Year: 2021
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: FOS: Computer and information sciences

description: Community networks are prone to free-riders, i.e., participants who take advantage of cooperation from others' routers but do not contribute reciprocally. In this paper, we present HARPIA, a system for credit-based incentive mechanisms for data forwarding in community networks aimed to prevent selfish behavior. HARPIA does not require a trusted third-party or tamper-resistant security modules as in other incentive mechanisms. Instead, it uses a distributed accounting scheme (DPIFA) to estimate the balance of data forwarding contribution and consumption of each network router and settle correspondent cryptocurrency debts on an Ethereum smart contract. On-chain settlement transactions are performed every HARPIA cycle (e.g., daily, weekly, monthly) and must be validated by at least m-of-n network routers using a multi-signature scheme (MuSig). We also realized a performance evaluation, security threat assessment, and cryptocurrency costs estimation. Results show that our proposal is suitable for community networks with up to 64 infrastructure routers under specific m-of-n MuSig thresholds.
Spin Susceptibility Above the Superfluid Onset in Ultracold Fermi Gases
Creators: name: Long, Yun
name: Xiong, Feng
name: Parker, Colin V.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: Ultracold atomic Fermi gases can be tuned to interact strongly, where they display spectroscopic signatures above the superfluid transition reminiscent of the pseudogap in cuprates. However, the extent of the analogy can be questioned, since thermodynamic quantities in the low temperature spin-imbalanced normal state can be described successfully using Fermi liquid theory. Here we present spin susceptibility measurements across the interaction strength-temperature phase diagram using a novel radiofrequency technique with ultracold $^6\textrm{Li}$ gases. For all significant interaction strengths and at all temperatures we find the spin susceptibility is reduced compared with the equivalent value for a non-interacting Fermi gas, with the low temperature results consistent with previous studies. However, our measurements extend to higher temperatures, where we find that the reduction persists consistently with a mean-field scenario. At unitarity, we can use the local density approximation to extract the spin susceptibility for the uniform gas, which is well described by mean-field models at temperatures from the superfluid transition to the Fermi temperature.
Thermodynamic analysis of a combined Organic Rankine Cycle (ORC) with Proton Exchange Membrane Electrolyzer (PEME) in an integrated biomass conversion system
Creators: name: Oreva Joe Ogorure
name: Heberle, Florian
name: Brüggemann, Dieter
Publisher: name: Technical University of Munich
Year: 2021

description: The energy content of product gas obtained from biomass gasification requires further processing to reach equivalent standards of natural gas. The product gas is produced at high temperature and undergoes cooling in a heat exchanger system prior to a cleanup process. This study presents the thermodynamic modelling of an integrated biomass to energy plant composed of a gasifier and digester, integrated with an Organic Rankine Cycle (ORC) and a Proton Exchange Membrane Electrolyzer (PEME) configuration for syngas upgrade. Thermal energy from steam at 290°C obtained from the syngas cooling process in view of waste heat recovery is utilized in the ORC for power generation, and as an energy source for the PEME. Six potential ORC working fluids aiming a maximum power generation of the ORC system are considered: R1243zf, R1234ze(Z), R1234yf, R1233zd(E), Isobutane, and Propane. R1233zd(E) is identified as most suitable working fluid with power output of 280.6kW and a thermal efficiency of 19.23 % for ORC configuration with regenerator. An increase in the flow rate of hydrogen resulted in a raise in the power consumption of the PEME, and a corresponding decrease of the ORC net power for each working fluid. Hydrogen gas produced from the PEME was used in upgrading the product gas from the gasification and anaerobic digestion processes through methanation model to comparable natural gas standard. The composition and lower heating value of upgraded product gas was 97.18% CH4, 2.82% H2, and 50.03 MJ/kg, respectively. The efficiency of the PEME was 88.79% with hydrogen gas rate of 0.51kmol/s. In further work, the process parameters will be optimized via multi-objective approach under thermo-economic aspects.
Additional file 1 of Community engagement in genetics and genomics research: a qualitative study of the perspectives of genetics and genomics researchers in Uganda
Creators: name: Nankya, Harriet
name: Wamala, Edward
name: Alibu, Vincent Pius
name: Barugahare, John
Publisher: name: figshare
Year: 2024
Subjects: subject: Medicine
subject: Genetics
subject: FOS: Biological sciences
subject: Biotechnology
subject: Science Policy
subject: Infectious Diseases
subject: FOS: Health sciences
subject: Plant Biology

description: Supplementary Material 1
Fractal-based modeling and spatial analysis of urban form and growth: a case study of Shenzhen in China
Creators: name: Man, Xiaoming
name: Chen, Yanguang
Publisher: name: arXiv
Year: 2020
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: Fractal dimension curves of urban growth can be modeled with sigmoid functions, including logistic function and quadratic logistic function. Different types of logistic functions indicate different spatial dynamics. The fractal dimension curves of urban growth in western countries follows the common logistic function, while these curves of cities in northern China follows quadratic logistic function. Now we want to know whether all Chinese cities follow the same rules of urban evolution. This paper is devoted to exploring the fractals and fractal dimension properties of the city of Shenzhen in southern China. The urban region is divided into four subareas, ArcGIS technology, box-counting method is adopted to extract spatial datasets, and the least squares regression is employed to estimate fractal parameters. The results show that: (1) The urban form of Shenzhen city has clear fractal structure, but fractal dimension values of different subareas are different; (2) The fractal dimension growth curves of all the four study areas can only be modeled by the common logistic function, and the goodness of fit increases over time; (3) The peak of urban growth in Shenzhen had passed before 1986, the fractal dimension growth is approaching its maximum capacity. Conclusions can be reached that the urban form of Shenzhen bears characteristics of multifractals, the fractal structure has been becoming better gradually through self-organization, but its land resources are reaching the limits of growth. The fractal dimension curves of Shenzhen's urban growth are similar to those of European and American cities, but differ from those of the cities in northern China. This suggests that there is subtle different dynamic mechanisms of city development between northern and southern China.
description: 24 pages,7 figures, 3 tables