cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Earthquake Arrival Association with Backprojection and Graph Theory
Creators: name: McBrearty, Ian W.
name: Gomberg, Joan
name: Delorey, Andrew A.
name: Johnson, Paul A.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Geophysics (physics.geo-ph)
subject: FOS: Physical sciences

description: The association of seismic wave arrivals with causative earthquakes becomes progressively more challenging as arrival detection methods become more sensitive, and particularly when earthquake rates are high. For instance, seismic waves arriving across a monitoring network from several sources may overlap in time, false arrivals may be detected, and some arrivals may be of unknown phase (e.g., P- or S-waves). We propose an automated method to associate arrivals with earthquake sources and obtain source locations applicable to such situations. To do so we use a pattern detection metric based on the principle of backprojection to reveal candidate sources, followed by graph-theory-based clustering and an integer linear optimization routine to associate arrivals with the minimum number of sources necessary to explain the data. This method solves for all sources and phase assignments simultaneously, rather than in a sequential greedy procedure as is common in other association routines. We demonstrate our method on both synthetic and real data from the Integrated Plate Boundary Observatory Chile (IPOC) seismic network of northern Chile. For the synthetic tests we report results for cases with varying complexity, including rates of 500 earthquakes/day and 500 false arrivals/station/day, for which we measure true positive detection accuracy of > 95%. For the real data we develop a new catalog between January 1, 2010 - December 31, 2017 containing 817,548 earthquakes, with detection rates on average 279 earthquakes/day, and a magnitude-of-completion of ~M1.8. A subset of detections are identified as sources related to quarry and industrial site activity, and we also detect thousands of foreshocks and aftershocks of the April 1, 2014 Mw 8.2 Iquique earthquake. During the highest rates of aftershock activity, > 600 earthquakes/day are detected in the vicinity of the Iquique earthquake rupture zone.
Design of Hybrid-Minigrids in South African Rural Areas under Consideration of Social and Cultural Aspects
Creators: name: Kühnel, M.
name: Hanke, B.
name: Baranova, Y.
name: Weigel, O.
name: Stuermer, I.W.
name: McMaster, A.
name: Maebe, S.
name: Von Maydell, K.
Publisher: name: WIP
Year: 2018
Subjects: PV Systems - Performance, Applications and Integration
Design and Installation of PV Systems

description: 35th European Photovoltaic Solar Energy Conference and Exhibition; 1656-1661
description: Small scale systems are vulnerable to changes. The development of solution strategies for future changed conditions should be considered from the outset in planning. So far load estimations for first electrification is determined primarily by interviews of the population. However, studies have shown that there are still major differ-ences between the power demand estimated by surveys and the real load after electrification. Reinforcing here is the inadequate assessment of load development through immigration and increased prosperity. On basis of a currently developing mini grid in the Eastern Cape of South Africa we could show that a load increase of approx. 60% within 10 years is to be expected. The following possibilities were outlined as possible counter measures: 1. communicating with the population, i.e. on energy efficiency to raise awareness and understanding, 2. early planning of capacity building and identification of key performance parameters to trigger the expansion based on local socio-cultural con-ditions and grid supporting qualities. An adequate data base for the initial electrification and power development should also be established and available on open source basis for researchers, developers, communities and installers.
Examples of infinite direct sums of spectral triples
Creators: name: Falk, Kevin
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We study two ways of summing an infinite family of noncommutative spectral triples. First, we propose a definition of the integration of spectral triples and give an example using algebras of Toeplitz operators acting on weighted Bergman spaces over the unit ball of $\mathbb{C}^n$. Secondly, we construct a spectral triple associated to a general polygonal self-similar set in $\mathbb{C}$ using algebras of Toeplitz operators on Hardy spaces. In this case, we show that we can recover the Hausdorff dimension of the fractal set.
description: 16 pages
Yielding and hardening of flexible fiber packings during triaxial compression
Creators: name: Guo, Yu
name: Li, Yanjie
name: Liu, Qingzhao
name: Jin, Hanhui
name: Xu, Dandan
name: Wassgren, Carl
name: Curtis, Jennifer
Publisher: name: arXiv
Year: 2019
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences
subject: 70F99

description: This paper examines the mechanical response of flexible fiber packings subject to triaxial compression. Short fibers yield in a manner similar to typical granular materials in which the deviatoric stress remains nearly constant with increasing strain after reaching a peak value. Interestingly, long fibers exhibit a hardening behavior, where the stress increases rapidly with increasing strain at large strains and the packing density continuously increases. Phase diagrams for classifying the bulk mechanical response as yielding, hardening, or a transition regime are generated as a function of the fiber aspect ratio, fiber-fiber friction coefficient, and confining pressure. Large fiber aspect ratio, large fiber-fiber friction coefficient, and large confining pressure promote hardening behavior. The hardening packings can support much larger loads than the yielding packings contributing to the stability and consolidation of the granular structure, but larger internal axial forces occur within fibers.
description: 14 pages, 4 figures
Efficient evaluation of scaled proximal operators
Creators: name: Friedlander, Michael P.
name: Goh, Gabriel
Publisher: name: arXiv
Year: 2016
Subjects: subject: Optimization and Control (math.OC)
subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: Quadratic-support functions [Aravkin, Burke, and Pillonetto; J. Mach. Learn. Res. 14(1), 2013] constitute a parametric family of convex functions that includes a range of useful regularization terms found in applications of convex optimization. We show how an interior method can be used to efficiently compute the proximal operator of a quadratic-support function under different metrics. When the metric and the function have the right structure, the proximal map can be computed with cost nearly linear in the input size. We describe how to use this approach to implement quasi-Newton methods for a rich class of nonsmooth problems that arise, for example, in sparse optimization, image denoising, and sparse logistic regression.
description: 23 pages
Time-crystalline behavior in an engineered spin chain
Creators: name: Schäfer, Robin
name: Uhrig, Götz S.
name: Stolze, Joachim
Publisher: name: arXiv
Year: 2019
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Time crystals appear when systems display a commensurate spontaneous breaking of the discrete time translational invariance imposed by an external periodic drive. No consensus on the definition has been reached as yet, but important aspects comprise robustness against small variations of the parameters and the initial quantum state. Often, disorder and interaction are thought to be essential ingredients for the occurrence of time crystals. We study a finite-length polarized XX spin chain engineered to display a spectrum of equidistant energy levels without drive and show that it keeps a spectrum of equidistant quasienergies in Floquet theory for a large variety of periodic driving schemes. This interesting behavior is explained by mapping the XX spin chain with $N+1$ sites to a single large spin with $S=N/2$ invoking the closure of the group SU(2). For suitably tuned parameters this system realizes time crystals of various periodicities for \emph{all} initial states. The robustness against variations of the parameters is also discussed. Thereby, we establish a clean system without interaction which can display the phenomenon of time crystallization.
description: 17 pages, 5 figures. Title changed. Extended discussion of disorder effects. Accepted for publication in Phys. Rev. B
Orbital character effects in the photon energy and polarization dependence of pure C60 photoemission
Creators: name: Latzke, Drew W.
name: Ojeda-Aristizabal, Claudia
name: Denlinger, Jonathan D.
name: Reno, Ryan
name: Zettl, Alex
name: Lanzara, Alessandra
Publisher: name: arXiv
Year: 2019
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Recent direct experimental observation of multiple highly-dispersive C$_{60}$ valence bands has allowed for a detailed analysis of the unique photoemission traits of these features through photon energy- and polarization-dependent measurements. Previously obscured dispersions and strong photoemission traits are now revealed by specific light polarizations. The observed intensity effects prove the locking in place of the C$_{60}$ molecules at low temperatures and the existence of an orientational order imposed by the substrate chosen. Most importantly, photon energy- and polarization-dependent effects are shown to be intimately linked with the orbital character of the C$_{60}$ band manifolds which allows for a more precise determination of the orbital character within the HOMO-2. Our observations and analysis provide important considerations for the connection between molecular and crystalline C$_{60}$ electronic structure, past and future band structure studies, and for increasingly popular C$_{60}$ electronic device applications, especially those making use of heterostructures.
Performance Analysis of Pre-Cracked PV-Modules at Cyclic Loading Conditions
Creators: name: Buerhop-Lutz, C.
name: Winkler, T.
name: Enzenberger, F.
name: Patel, T.
name: Hauch, J.
name: Camus, C.
name: Brabec, C.J.
Publisher: name: WIP
Year: 2018
Subjects: PV Systems - Performance, Applications and Integration
Operation, Performance and Maintenance of PV Systems

description: 35th European Photovoltaic Solar Energy Conference and Exhibition; 1554-1558
description: PV-modules with precracked solar cells are frequently present in PV-plants as current inspection methods reveal. How these modules perform in the future is still unknown. Uniform static loading tests characterize short-term performance well, as presented previously (EUPVSEC 2017). In order to simulate long-term stability, the application of alternating loads, comparable to wind gusts, is important. The load cycle is fed into the improved mechanical loading test-setup by a PLC whilst recording EL-images simultaneously and measuring IV-curves. For the first time, module performance for long-term stability with 100,000 cycles are presented. The results show that with an increasing number of cycles and pressure, the EL-intensity distribution of cracked cells changes but the performance loss is rather small. These findings correlate with analysis of field-exposed modules.
Regular points of extremal subsets in Alexandrov spaces
Creators: name: Fujioka, Tadashi
Publisher: name: arXiv
Year: 2019
Subjects: subject: Differential Geometry (math.DG)
subject: Metric Geometry (math.MG)
subject: FOS: Mathematics
subject: 53C20, 53C23

description: We define regular points of an extremal subset in an Alexandrov space and study their basic properties. We show that a neighborhood of a regular point in an extremal subset is almost isometric to an open subset in Euclidean space and that the set of regular points in an extremal subset has full measure and is dense in it. These results actually hold for strained points in an extremal subset. Applications include the volume convergence of extremal subsets under a noncollapsing convergence of Alexandrov spaces, and the existence of a cone fibration structure of a metric neighborhood of the regular part of an extremal subset. In an appendix, a deformation retraction of a metric neighborhood of a general extremal subset is constructed.
description: added Theorem 1.5 and Appendix A, simplified the proof of Theorem 1.3
Simulation of Bifacial PV Modules in Nordic Conditions for Low and High Albedo
Creators: name: Molin, E.
name: Stridh, B.
name: Molin, A.
name: Wäckelgård, E.
Publisher: name: WIP
Year: 2018
Subjects: PV Systems - Performance, Applications and Integration
Operation, Performance and Maintenance of PV Systems

description: 35th European Photovoltaic Solar Energy Conference and Exhibition; 1605-1608
description: In this study simulations of bifacial HIT modules using PVsyst will be compared with measured data from test plants in Linköping, Sweden. The simulations have been validated with measured data in the field study. The deviation between simulated and measured annual energy yields were in the range of 3 % for site 1 and 5% for site 2. Moreover, simulations show that the annual specific energy yield would increase to 1.45 MWh/kWp compared to 1.10 MWh/kWp, for south orientation at 40° tilt and to 1.47 MWh/kWp, compared to 0.98 MWh/kWp, for vertical east-west orientation by changing the albedo to 0.80 instead of the existing tar paper with albedo 0.05. The annual specific energy yield increased with 32 % for the south facing modules at site 1 and with 50% for east-west facing modules at site 2 when the albedo change from 0.05 to 0.80. Monofacial simulations show that the annual specific yield increased with 7% for south orientated at 40° tilt on an annual basis when the albedo change from 0.05 to 0.80.
A Generalization of the Gram determinant of type A
Creators: name: Bakshi, Rhea Palak
name: Ibarra, Dionne
name: Mukherjee, Sujoy
name: Przytycki, Józef H.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Geometric Topology (math.GT)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: Primary: 57M27. Secondary: 57M25, 05A19

description: The Gram determinant of type $A$ was introduced by Lickorish in his work on invariants of 3 - manifolds. We generalize the theory of the Gram determinant of type $A$ by evaluating, in the annulus, a bilinear form of non-intersecting connections in the disc. The main result provides a closed formula for this Gram determinant. We conclude the paper by discussing Chen's conjecture about the Gram determinant of type $Mb$ evaluated in the Klein bottle.
description: 17 pages, 19 figures
A Lower TC: In the Future Maybe Not Always the Best Idea?
Creators: name: Govaerts, J.
name: Horvath, I.T.
name: Goverde, H.
name: Aldalali, B.
name: Beausoleil-Morrison, I.
name: Poortmans, J.
Publisher: name: WIP
Year: 2018
Subjects: PV Systems - Performance, Applications and Integration
Design and Installation of PV Systems

description: 35th European Photovoltaic Solar Energy Conference and Exhibition; 1615-1618
description: In the future, with costs for PV modules rapidly declining and an expected increase of PV penetration in energy production, the cost for PV installations may be impacted more and more by balancing costs of storage, load management, and curtailment, rather than the currently dominating hardware components (PV modules and BOS components). With a low overall cost in mind, we should consider the interplay of generation (of course also intraday, but in particular seasonal variations are investigated in this work), load (consumption pattern) and storage costs for each location.
In this paper we want to raise awareness about the increasing complexity of technology optimization resulting from the evolving cost structure of PV electricity generation. The latter can lead to counter-intuitive outcomes such as: a lower temperature coefficient may not always be the best in the future.
First we build some first order analytical model to illustrate the concept and indicate trends. Then we apply our physics-based bottom-up modeling approach, taking into account coupled optical, thermal and electrical effects (and published more in detail elsewhere). This can be used to quantify with high accuracy PV production throughout the year as function of climate data and PV module technical data, in particular the temperature coefficient.
Finally, we indicate some locations where the benefits of a higher temperature coefficient may materialize most, and that deserve some further attention.
Restricted Spatial Regression Methods: Implications for Inference
Creators: name: Khan, Kori
name: Calder, Catherine A.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Methodology (stat.ME)
subject: Statistics Theory (math.ST)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: The issue of spatial confounding between the spatial random effect and the fixed effects in regression analyses has been identified as a concern in the statistical literature. Multiple authors have offered perspectives and potential solutions. In this paper, for the areal spatial data setting, we show that many of the methods designed to alleviate spatial confounding can be viewed as special cases of a general class of models. We refer to this class as Restricted Spatial Regression (RSR) models, extending terminology currently in use. We offer a mathematically based exploration of the impact that RSR methods have on inference for regression coefficients for the linear model. We then explore whether these results hold in the generalized linear model setting for count data using simulations. We show that the use of these methods have counterintuitive consequences which defy the general expectations in the literature. In particular, our results and the accompanying simulations suggest that RSR methods will typically perform worse than non-spatial methods. These results have important implications for dimension reduction strategies in spatial regression modeling. Specifically, we demonstrate that the problems with RSR models cannot be fixed with a selection of "better" spatial basis vectors or dimension reduction techniques.
description: Minor notation and typo edits. Primary change is to statement and proof of Theorem 2. KJournal of the American Statistical Association (2020)
Mars™ Soiling Sensor
Creators: name: Gostein, M.
name: Faullin, S.
name: Miller, K.
name: Schneider, J.
name: Stueve, B.
Publisher: name: WIP
Year: 2018
Subjects: PV Systems - Performance, Applications and Integration
Operation, Performance and Maintenance of PV Systems

description: 35th European Photovoltaic Solar Energy Conference and Exhibition; 1523-1527
description: We evaluate a new proprietary optical soiling measurement technology that does not require washing. The compact, water-free, and maintenance-free sensor technology is designed to permit PV system soiling measurement with lower cost and labor requirements compared to traditional soiling measurement systems using a clean/soiled pair of PV reference devices. These attributes make the sensor suitable for a wide range of sites including not only utility but also commercial-scale PV installations. Laboratory test results using soiled glass test coupons demonstrate excellent correlation between the optical sensor and a PV cell, and field testing is underway.
Predicting Future Soiling Losses Using Environmental Data
Creators: name: Micheli, L.
name: Deceglie, M.G.
Publisher: name: WIP
Year: 2018
Subjects: PV Systems - Performance, Applications and Integration
Operation, Performance and Maintenance of PV Systems

description: 35th European Photovoltaic Solar Energy Conference and Exhibition; 1528-1531
description: The correlations between soiling and parameters describing the atmospheric, pollution and geometric characteristic of a site have already been investigated in the literature. In particular, particulate matter and rainfall data have been shown to be the best parameters to estimate soiling losses occurring at photovoltaic sites in the United States. However, previous investigations only considered soiling and environmental data collected over the same time periods. The aim of the present research is, instead, to understand if future soiling losses can be predicted using environmental parameters recorded during previous time periods. To do this, we compared the soiling occurring at 41 U.S. locations with particulate matter and rainfall data recorded 1 to 30 years earlier.
Counting rational points on smooth cubic curves
Creators: name: Tran, Manh Hung
Publisher: name: arXiv
Year: 2016
Subjects: subject: Number Theory (math.NT)
subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics
subject: 11D25, 11D45, 11G05

description: We use a global version of Heath-Brown's $p-$adic determinant method developed by Salberger to give upper bounds for the number of rational points of height at most $B$ on non-singular cubic curves defined over $\mathbb{Q}$. The bounds are uniform in the sense that they only depend on the rank of the corresponding Jacobian.
description: 10 pages. Comments are welcome
Experimental Analysis of Different Cell and Module Technologies in a BIPV Façade Test Set Up
Creators: name: Lehmann, J.
name: Goncalves, J.
name: Van Der Heide, A.S.H.
name: Yordanov, G.H.
name: Goverde, H.
name: Baert, K.
name: Saelens, D.
Publisher: name: WIP
Year: 2018
Subjects: PV Systems - Performance, Applications and Integration
Building, Infrastructure, Landscape and Other Applications of PV

description: 35th European Photovoltaic Solar Energy Conference and Exhibition; 1478-1482
description: The purpose of this paper is to compare different cell and module technologies comprising monofacial or bifacial, SmartWire or standard busbar interconnection and white or transparent encapsulant in a real conditions BIPV environment. For bifacial modules, the gain obtained in a BIPV configuration using different wall material with contrasting optical properties was investigated. This paper introduces the experimental set-up, followed by an electrical analysis at STC conditions, an electrical and thermal analysis on a sunny winter day and finally a statistical long-term energy yield analysis. Temperatures were measured each second on the back of each module on several relevant location while IV measurements were acquired every 15 seconds, allowing therefore Voc and Isc comparison between the modules. The electrical measurements have evidenced a power production for transparent encapsulant bifacial modules with SmartWire technology up to 16% higher than mono-facial module with standard busbar interconnection. As for the building integration, the results show an important effect of the wall material on the bifacial modules performances, with Isc up to 0.25A higher for white and aluminum wall material, and on the building temperature, with up to 5°C higher temperature observed for black wall material.
Learning Deep Generative Models with Annealed Importance Sampling
Creators: name: Ding, Xinqiang
name: Freedman, David J.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Machine Learning (stat.ML)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Variational inference (VI) and Markov chain Monte Carlo (MCMC) are two main approximate approaches for learning deep generative models by maximizing marginal likelihood. In this paper, we propose using annealed importance sampling for learning deep generative models. Our proposed approach bridges VI with MCMC. It generalizes VI methods such as variational auto-encoders and importance weighted auto-encoders (IWAE) and the MCMC method proposed in (Hoffman, 2017). It also provides insights into why running multiple short MCMC chains can help learning deep generative models. Through experiments, we show that our approach yields better density models than IWAE and can effectively trade computation for model accuracy without increasing memory cost.
Unsupervised Phoneme and Word Discovery from Multiple Speakers using Double Articulation Analyzer and Neural Network with Parametric Bias
Creators: name: Nakashima, Ryo
name: Ozaki, Ryo
name: Taniguchi, Tadahiro
Publisher: name: arXiv
Year: 2019
Subjects: subject: Audio and Speech Processing (eess.AS)
subject: Sound (cs.SD)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: This paper describes a new unsupervised machine learning method for simultaneous phoneme and word discovery from multiple speakers. Human infants can acquire knowledge of phonemes and words from interactions with his/her mother as well as with others surrounding him/her. From a computational perspective, phoneme and word discovery from multiple speakers is a more challenging problem than that from one speaker because the speech signals from different speakers exhibit different acoustic features. This paper proposes an unsupervised phoneme and word discovery method that simultaneously uses nonparametric Bayesian double articulation analyzer (NPB-DAA) and deep sparse autoencoder with parametric bias in hidden layer (DSAE-PBHL). We assume that an infant can recognize and distinguish speakers based on certain other features, e.g., visual face recognition. DSAE-PBHL is aimed to be able to subtract speaker-dependent acoustic features and extract speaker-independent features. An experiment demonstrated that DSAE-PBHL can subtract distributed representations of acoustic signals, enabling extraction based on the types of phonemes rather than on the speakers. Another experiment demonstrated that a combination of NPB-DAA and DSAE-PB outperformed the available methods in phoneme and word discovery tasks involving speech signals with Japanese vowel sequences from multiple speakers.
description: 21 pages. Submitted
Van der Waals phase transition in the framework of holography
Creators: name: Zeng, Xiao-Xiong
name: Li, Li-Fang
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Phase structure of the quintessence Reissner-Nordström-AdS black hole is probed with the nonlocal observables such as holographic entanglement entropy and two point correlation function. Our result shows that, as the case of the thermal entropy, both the observables exhibit the similar Van der Waals-like phase transition. To reinforce the conclusion, we further check the equal area law for the first order phase transition and critical exponent of the heat capacity for the second order phase transition. We also discuss the effect of the state parameter on the phase structure of the nonlocal observables.
description: 16 pages, 6 figures. arXiv admin note: text overlap with arXiv:1511.00383
Integration of Imitation Learning using GAIL and Reinforcement Learning using Task-achievement Rewards via Probabilistic Graphical Model
Creators: name: Kinose, Akira
name: Taniguchi, Tadahiro
Publisher: name: arXiv
Year: 2019
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: Integration of reinforcement learning and imitation learning is an important problem that has been studied for a long time in the field of intelligent robotics. Reinforcement learning optimizes policies to maximize the cumulative reward, whereas imitation learning attempts to extract general knowledge about the trajectories demonstrated by experts, i.e., demonstrators. Because each of them has their own drawbacks, methods combining them and compensating for each set of drawbacks have been explored thus far. However, many of the methods are heuristic and do not have a solid theoretical basis. In this paper, we present a new theory for integrating reinforcement and imitation learning by extending the probabilistic generative model framework for reinforcement learning, {\it plan by inference}. We develop a new probabilistic graphical model for reinforcement learning with multiple types of rewards and a probabilistic graphical model for Markov decision processes with multiple optimality emissions (pMDP-MO). Furthermore, we demonstrate that the integrated learning method of reinforcement learning and imitation learning can be formulated as a probabilistic inference of policies on pMDP-MO by considering the output of the discriminator in generative adversarial imitation learning as an additional optimal emission observation. We adapt the generative adversarial imitation learning and task-achievement reward to our proposed framework, achieving significantly better performance than agents trained with reinforcement learning or imitation learning alone. Experiments demonstrate that our framework successfully integrates imitation and reinforcement learning even when the number of demonstrators is only a few.
description: Submitted to Advanced Robotics
Robust Max Entrywise Error Bounds for Tensor Estimation from Sparse Observations via Similarity Based Collaborative Filtering
Creators: name: Shah, Devavrat
name: Yu, Christina Lee
Publisher: name: arXiv
Year: 2019
Subjects: subject: Machine Learning (cs.LG)
subject: Data Structures and Algorithms (cs.DS)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: Consider the task of estimating a 3-order $n \times n \times n$ tensor from noisy observations of randomly chosen entries in the sparse regime. We introduce a similarity based collaborative filtering algorithm for estimating a tensor from sparse observations and argue that it achieves sample complexity that nearly matches the conjectured computationally efficient lower bound on the sample complexity for the setting of low-rank tensors. Our algorithm uses the matrix obtained from the flattened tensor to compute similarity, and estimates the tensor entries using a nearest neighbor estimator. We prove that the algorithm recovers a finite rank tensor with maximum entry-wise error (MEE) and mean-squared-error (MSE) decaying to $0$ as long as each entry is observed independently with probability $p = Ω(n^{-3/2 + κ})$ for any arbitrarily small $κ> 0$. More generally, we establish robustness of the estimator, showing that when arbitrary noise bounded by $\varepsilon \geq 0$ is added to each observation, the estimation error with respect to MEE and MSE degrades by $\text{poly}(\varepsilon)$. Consequently, even if the tensor may not have finite rank but can be approximated within $\varepsilon \geq 0$ by a finite rank tensor, then the estimation error converges to $\text{poly}(\varepsilon)$. Our analysis sheds insight into the conjectured sample complexity lower bound, showing that it matches the connectivity threshold of the graph used by our algorithm for estimating similarity between coordinates.
Performance Analysis of Vertically Mounted Bifacial PV Modules on Green Roof System
Creators: name: Baumann, T.
name: Carigiet, F.
name: Knecht, R.
name: Klenk, M.
name: Dreisiebner, A.
name: Nussbaumer, H.
name: Baumgartner, F.P.
Publisher: name: WIP
Year: 2018
Subjects: PV Systems - Performance, Applications and Integration
Building, Infrastructure, Landscape and Other Applications of PV

description: 35th European Photovoltaic Solar Energy Conference and Exhibition; 1504-1509
description: A combination of PV and green roof is an ideal fusion in terms of ecology. The green roof improves the
water retention in the city, whereas the PV system produces electric power at the place where it is consumed. Flat tilted
modules in south or east west direction on green roofs generally require intensive maintenance to prevent them from
being shaded by plants and often cover the roof area to a large extent. Because of the space requirement conflict between
PV on the roof and green roofs, it is essential to combine these two systems in a smart way. Vertically mounted bifacial
modules can be an option to combine PV and green roof and to also allow a cost-effective maintenance.
In this paper we report about the layout and the performance of a corresponding system, subdivided into two groups
with differing albedo. Custom made bifacial modules with 20 cells were produced to reduce the wind load and to
improve the general appearance. This 9.09 kWp bifacial plant achieved a specific yield of 942 kWh/kWp in one year
(11.08.2017 to 10.08.2018). High quality DC power measurement systems are installed to monitor two modules in each
bifacial test field and a reference south-facing module. This allows an energy yield comparison between the vertical
bifacial test system with east-west orientation and the monofacial south-facing reference over four months of outdoor
measurements. The use of plants with good reflective properties, which are also well suited two the ambient conditions
on flat roofs, resulted in a yield increase of 17 % compared to a standard green roof planting. The vertically installed
bifacial modules obtained an almost identical specific yield (-1.4 %) compared to a stand-alone monofacial southfacing
reference module. Due to the increased yield in the mornings and afternoons, the vertical bifacial modules can
achieve higher self-consumption depending on the load profile.
Dutch Solar Design BIPV: Optimizing Power Output and Aesthetic Performance in Architectural Design
Creators: name: Slooff, L.H.
name: Van Roosmalen, J.A.M.
name: Okel, L.A.G.
name: Minderhoud, T.
name: Gijzen, G.
name: Polinder, L.C.
name: Goethals, F.
name: Sepers, T.
Publisher: name: WIP
Year: 2018
Subjects: PV Systems - Performance, Applications and Integration
Building, Infrastructure, Landscape and Other Applications of PV

description: 35th European Photovoltaic Solar Energy Conference and Exhibition; 1483-1487
description: The energy transition and more precisely, the contribution of photovoltaics (PV) in that transition, asks
for better integration of PV in buildings, infrastructure and landscapes. To realize this, a variation in shape, size and
color of PV products is needed. In this paper a technology will be shown that allows variation of all these features. The
effect of design variables on the performance is presented as well as stability studies with respect to power output and
color. The results show that the performance and visual appearance can be optimized, resulting in a good visual
appearance without compromising the power output too much. The outdoor tests show no degradation in color or power
output. When subjected to concentrated sunlight, the primary ink colors show limited change, hardly perceivable in a
full color print after 25 years. It shows that this technology is able to add the desired variations in shape, size and color
to PV modules.
Real spinors and real Dirac equation
Creators: name: Zatloukal, Vaclav
Publisher: name: arXiv
Year: 2019
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences
subject: 81R25

description: We reexamine the minimal coupling procedure in the Hestenes' geometric algebra formulation of the Dirac equation, where spinors are identified with the even elements of the real Clifford algebra of spacetime. This point of view, as we argue, leads naturally to a non-Abelian generalisation of the electromagnetic gauge potential.
description: 10 pages, 3 figures
Automated Text Analysis in Theology: An Application
Creators: name: Tagliapietra, Claudio
Publisher: name: Taylor & Francis
Year: 2024
Subjects: Cell Biology
Science Policy

description: This article examines the use of NLP methods in theology. We analyzed a corpus of 37 homilies written by Josemaría Escrivá, a Spanish priest who founded the Catholic Church institution “Opus Dei”. We assumed no prior knowledge of Escrivá and used automated text analysis methods like topic categorization, machine learning algorithms, and network science to examine his presentation of Christ as the center of creation and Christian existence. Our results match the findings of previous studies by numerous Escrivá scholars. We discuss opportunities and risks of incorporating NLP methods into theological research.
Rashba scattering in the low-energy limit
Creators: name: Hutchinson, Joel
name: Maciejko, Joseph
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Gases (cond-mat.quant-gas)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study potential scattering in a two-dimensional electron gas with Rashba spin-orbit coupling in the limit that the energy of the scattering electron approaches the bottom of the lower spin-split band. Focusing on two spin-independent circularly symmetric potentials, an infinite barrier and a delta-function shell, we show that scattering in this limit is qualitatively different from both scattering in the higher spin-split band and scattering of electrons without spin-orbit coupling. The scattering matrix is purely off-diagonal with both off-diagonal elements equal to one, and all angular momentum channels contribute equally; the differential cross section becomes increasingly peaked in the forward and backward scattering directions; the total cross section exhibits quantized plateaus. These features are independent of the details of the scattering potentials, and we conjecture them to be universal. Our results suggest that Rashba scattering in the low-energy limit becomes effectively one-dimensional.
description: corrected typo in Eq. (27). 10 pages, 6 figures
An Overview of Floating PV Worldwide
Creators: name: De Jong, M.M.
name: Dörenkämper, M.
name: Sinapis, K.
name: Folkerts, W.
Publisher: name: WIP
Year: 2018
Subjects: PV Systems - Performance, Applications and Integration
Building, Infrastructure, Landscape and Other Applications of PV

description: 35th European Photovoltaic Solar Energy Conference and Exhibition; 1437-1439
description: Floating solar systems can represent a serious alternative to ground mounted solar systems. At present, the international market for floating PV is small compared to the total PV market, but expected to become a multi-billion market in the coming years. A main driver for the growth of the market for floating PV is the mitigation of land cost. Other drivers are the potential added benefits of deploying photovoltaics on water such as a lower module temperature and reflections from the water, leading to higher energy output. Covering hydropower lakes or drinking water reservoirs will decrease evaporation rates. At present, Japan and China are the two driving markets, with Japan hosting a large number of projects and China being home to a number of very large systems, with the largest over 100MWp. In Europe, the UK hosts the largest systems. The yearly installed capacity shows a quickly increasing trend from 3MWp in 2013 to more than 400 MWp in 2017. Research projects are being executed in Singapore, Malta and the Netherlands. Of 20 different available floating PV systems we assessed different properties that affect the energy output, packing density, survivability, ease of maintenance and installation speed. We see large differences in design philosophy between the systems.
Discrete Element Method Model of Elastic Fiber Uniaxial Compression
Creators: name: Guo, Yu
name: Li, Yanjie
name: Liu, Qingzhao
name: Li, Zhenhua
name: Jin, Hanhui
name: Wassgren, Carl
name: Curtis, Jennifer S.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences
subject: 74B99

description: A flexible fiber model based on the discrete element method (DEM) is presented and validated for the simulation of uniaxial compression of flexible fibers in a cylindrical container. It is found that the contact force models in the DEM simulations have a significant impact on compressive forces exerted on the fiber bed. Only when the geometry-dependent normal contact force model and the static friction model are employed, the simulation results are in good agreement with experimental results. Systematic simulation studies show that the compressive force initially increases and eventually saturates with an increase in the fiber-fiber friction coefficient, and the fiber-fiber contact forces follow a similar trend. The compressive force and lateral shear-to-normal stress ratio increase linearly with increasing fiber-wall friction coefficient. In uniaxial compression of frictional fibers, more static friction contacts occur than dynamic friction contacts with static friction becoming more predominant as the fiber-fiber friction coefficient increases.
description: 30 pages, 14 figures, submitted for publication
Planning and Optimizing the PV Material Life Cycle - The Example of Switzerland
Creators: name: Muntwyler, U.
name: Schüpbach, E.
name: Eppenberger, R.
Publisher: name: WIP
Year: 2018
Subjects: Photovoltaic Modules and BoS Components
Sustainability and Recycling

description: 35th European Photovoltaic Solar Energy Conference and Exhibition; 1411-1415
description: As part of the Energy Strategy 2050, the electricity gap resulting from the phase-out of nuclear energy
is primarily compensated with PV modules. The Energy Strategy 2050 plans the expansion of photovoltaics to 12
TWh in 2050. This could rise to 24 TWh due to the elimination of deep geothermal energy (4TWh) and the replacement
of cars with combustion engines by electric vehicles (approx. 8TWh) i. Based on the current PV market, a huge
number of installed PV modules will be seen 2050. These modules can be made up of different technologies such as
c-Si, thin-film modules such as Cd/Te, CIS or CIGS. Assuming a service life of 25-40 yearsii, all these modules must
be dismantled and disposed of again. Even for PV modules alone the quantities of material that will be disposed of in
Switzerland and thus the recycled material flows are considerable. Forward-looking planning of the products employed,
and their recycling is important for users and installers. This is where the joint research efforts of SENS
eRecycling and the Bern University of Applied Sciences BFH come in.
Neuro-SERKET: Development of Integrative Cognitive System through the Composition of Deep Probabilistic Generative Models
Creators: name: Taniguchi, Tadahiro
name: Nakamura, Tomoaki
name: Suzuki, Masahiro
name: Kuniyasu, Ryo
name: Hayashi, Kaede
name: Taniguchi, Akira
name: Horii, Takato
name: Nagai, Takayuki
Publisher: name: arXiv
Year: 2019
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: This paper describes a framework for the development of an integrative cognitive system based on probabilistic generative models (PGMs) called Neuro-SERKET. Neuro-SERKET is an extension of SERKET, which can compose elemental PGMs developed in a distributed manner and provide a scheme that allows the composed PGMs to learn throughout the system in an unsupervised way. In addition to the head-to-tail connection supported by SERKET, Neuro-SERKET supports tail-to-tail and head-to-head connections, as well as neural network-based modules, i.e., deep generative models. As an example of a Neuro-SERKET application, an integrative model was developed by composing a variational autoencoder (VAE), a Gaussian mixture model (GMM), latent Dirichlet allocation (LDA), and automatic speech recognition (ASR). The model is called VAE+GMM+LDA+ASR. The performance of VAE+GMM+LDA+ASR and the validity of Neuro-SERKET were demonstrated through a multimodal categorization task using image data and a speech signal of numerical digits.
description: New Gener. Comput. (2020)
Boundary versus bulk behavior of time-dependent correlation functions in one-dimensional quantum systems
Creators: name: Eliëns, I. S.
name: Ramos, F. B.
name: Xavier, J. C.
name: Pereira, R. G.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We study the influence of reflective boundaries on time-dependent responses of one-dimensional quantum fluids at zero temperature beyond the low-energy approximation. Our analysis is based on an extension of effective mobile impurity models for nonlinear Luttinger liquids to the case of open boundary conditions. For integrable models, we show that boundary autocorrelations oscillate as a function of time with the same frequency as the corresponding bulk autocorrelations. This frequency can be identified as the band edge of elementary excitations. The amplitude of the oscillations decays as a power law with distinct exponents at the boundary and in the bulk, but boundary and bulk exponents are determined by the same coupling constant in the mobile impurity model. For nonintegrable models, we argue that the power-law decay of the oscillations is generic for autocorrelations in the bulk, but turns into an exponential decay at the boundary. Moreover, there is in general a nonuniversal shift of the boundary frequency in comparison with the band edge of bulk excitations. The predictions of our effective field theory are compared with numerical results obtained by time-dependent density matrix renormalization group (tDMRG) for both integrable and nonintegrable critical spin-$S$ chains with $S=1/2$, $1$ and $3/2$.
description: 20 pages, 12 figures
3-Leibniz bialgebras (3-Lie bialgebras)
Creators: name: Rezaei-Aghdam, A.
name: Sedghi-Ghadim, L.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Rings and Algebras (math.RA)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: The aim of this paper is to extend the notion of bialgebra for Leibniz algebras (and Lie algebras) to $3$-Leibniz algebras (and $3$-Lie algebras) by use of the cohomology complex of $3$-Leibniz algebras. Also, some theorems about Leibniz bialgebras are extended and proved in the case of $3$-Leibniz bialgebras ($3$-Lie bialgebras). Moreover, a new theorem on the correspondence between $3$-Leibniz bialgebra and its associated Leibniz bialgebra is proved. Finally, some examples are discussed in detail.
description: 28 pages
Versatile & Lightweight Transparent Composite Technology for Advanced BIPV Architectural Solutions
Creators: name: Vega De Seoane, J.M.
name: Zubillaga, O.
name: Yurrita, N.
name: Aizpurua, J.
name: Astigarraga Erleaga, A.
name: Arrizabalaga, I.
name: Imbuluzketa, G.
name: Machado, M.
name: Sanz Martinez, A.
name: Román Medina, E.
name: Cano, F.J.
Publisher: name: WIP
Year: 2018
Subjects: PV Systems - Performance, Applications and Integration
Building, Infrastructure, Landscape and Other Applications of PV

description: 35th European Photovoltaic Solar Energy Conference and Exhibition; 1452-1457
description: Despite their yet low market penetration, building-integrated photovoltaic (BIPV) systems are expected to play a relevant role in the achievement of Nearly-Zero Energy Buildings (NZEBs) related targets. One of the main reasons explaining the low market deployment is the lack of versatility and adaptability of the currently dominating glass-based solutions, which present important restrictions at integration level.
With the ambition of overcoming those limitations and fulfilling architects’ demands, TECNALIA R&I has developed Solarface, a transparent fibre-reinforced photovoltaic (PV) encapsulation technology that provides freedom in terms of design, lightness, virtually no shape limitations, mechanical strength and durability, at a competitive cost. The fibre-reinforced PV technology makes possible the fabrication of customized products for various applications: building, urban environment, transport, aerospace. etc.
The technology has been further developed and demonstrated in the FP7 funded BFIRST project (nº 290616), where portfolio of BIPV products were developed and real scale prototypes were manufactured and demonstrated. The development of the technology continues in EnergyMatching (H2020, nº 768766) where the influence of complex geometries on the cell-resin interface, aesthetic finishes and the introduction of additional functionalities to enhance performance are being explored