IA Scholar Query: The Spiral Array: An Algorithm for Determining Key Boundaries.
https://scholar.archive.org/
Internet Archive Scholar query results feedeninfo@archive.orgThu, 15 Sep 2022 00:00:00 GMTfatcat-scholarhttps://scholar.archive.org/help1440Galactic Planetary Nebulae with Emphasis on those that are Members of Open Star Clusters
https://scholar.archive.org/work/dfcxmjn6tbasjnpb2c6pr4ueue
The study of Planetary Nebulae (PNe) provides vital clues for understanding late stage stellar evolution and stellar mass loss. Despite their significance, various issues concerning these objects remain unsolved. Interstellar extinction by dust hampers the detection of many Galactic PNe at optical wavelengths while their largely unknown distances and progenitor masses are two key parameters that hamper deeper understanding. More reliable data is urgently required. Identification of dust obscured PNe can be partially solved with observations at longer wavelengths where extinction effects are less serious and by multi-wavelength techniques proposed for their detection. Multi-wavelength techniques are a proven effective method for identification of Galactic PN candidates. Here, the efficacy of these methods is evaluated for identification of new Galactic PN candidates. From 70 new PN candidates uncovered in this study only 11 have optical counterparts allowing spectroscopic follow-up. From the eight observed so far, seven are confirmed as PNe. One subset of PNe that avoid most of the above issues are PNe in Galactic star clusters. Such PNe have distances and progenitor masses determined independently from cluster color-magnitude diagrams. Observational data of Galactic cluster PNe and their central stars (CSPN) allows determination of their final core masses that can feed into the Initial-To-Final Mass (IFMR) relation which is crucial for understanding the chemical enrichment of the interstellar medium. Evidence of a PN-cluster association requires multiparameter agreement of reddening, distance, angular proximity, PN physical size and most importantly radial velocity. Here, we study the first confirmed PN-open cluster pair (PHR1315-6555 – AL 1) identifying its CSPN and measuring its physical properties. This study allowed the determination of AL 1's physical parameters with precision and the identification of the core of PHR 1315-6555 that is a ̴ 0.6 Mʘ, hot (T= ̴ 110 kK) white dwarf with a progenitor m [...]Vasiliki Fragkou, Quentin A. Parker, Albert Zijlstrawork_dfcxmjn6tbasjnpb2c6pr4ueueThu, 15 Sep 2022 00:00:00 GMTAnalysis of PAPR and BER Reduction in MIMO-OFDM using Hybrid Moth Flame-Improved Firefly Algorithm
https://scholar.archive.org/work/dtu4ykmoebd7rklt632sieku3m
The hybrid innovation of Orthogonal Frequency Division Multiplexing (OFDM) through Multiple-Input Multiple-Output (MIMO) delivers a feasible substitute to increase the Quality of Service (QoS) to accomplish better data rate and spectral efficiency for the transmission network. An extraordinary Peak-to-Average Power Ratio (PAPR) and Bit Error Rate (BER) are the important parameters that can be considered in the analysis of the MIMO-OFDM network. Partition Transmit Sequences (PTSs) is one of the capable procedures and direct methods to attain a reasonable PAPR performance. However, it needs a serious restoration process to discover the vital features that produce a computational multi-layered design with sub-blocks. Here, a reduced computational complexity PTS scheme is proposed which is completely depends on the hybrid procedure named as Moth Flame Optimization with Improved Firefly Algorithm (MFO-IFFA). The simulation outcomes demonstrated the capability of the proposed MFO-IFFA approach decreases the PAPR reduction up to 3.6 dB. Similarly, the proposed MFO-IFFA overcomes the significant evolutionary procedures mentioned in the existing works such as Additive Signal Mixing (ASM), Adaptive Simplified Optimized Iterative Clipping and Filtering (ASOICF) and Hybrid Independent Component Analysis (HICA).work_dtu4ykmoebd7rklt632sieku3mWed, 31 Aug 2022 00:00:00 GMTTIC 5724661: A Long-Period Binary with a Pulsating sdB Star and δ Scuti Variable
https://scholar.archive.org/work/ghnf44375negbclvhg64mwbk5m
Using TESS 20-sec cadence data, we have discovered an unusual combination of pulsating stars in what we infer to be a binary system. The binary consists of a standard δ Scuti star with pulsations over the range 32-41 d^-1; this is in a likely wide orbit with a hot subdwarf B (sdB) star, which itself has a large-amplitude p-mode pulsation at 524 d^-1. We establish constraints on the period of the putative binary by using radial velocity measurements of the δ Scuti star and show that any sdB companion star must orbit with a period greater than a few tens of days. Our identification of this sdB binary serves as an important addition to the relatively small number of sdB binaries known to have orbital periods longer than a few days. We model such a binary using MESA and find that this system could be formed through stable, nonconservative mass transfer from either a low- or intermediate-mass progenitor, without undergoing a common envelope phase.Rahul Jayaraman, Saul Rappaport, Lorne Nelson, Donald W. Kurtz, George Dufresne, Gerald Handler, Abdel Senhadji, David W. Latham, George Zhou, Allyson Bieryla, George Rickerwork_ghnf44375negbclvhg64mwbk5mTue, 02 Aug 2022 00:00:00 GMTDust, CO and [CI]: Cross-calibration of molecular gas mass tracers in metal-rich galaxies across cosmic time
https://scholar.archive.org/work/jqawmcnloveq7lfrliomxatsvy
We present a self-consistent cross-calibration of the three main molecular gas mass tracers in galaxies, the ^12CO(1-0), [CI](^3P_1-^3P_0) lines, and the submm dust continuum emission, using a sample of 407 galaxies, ranging from local disks to submillimetre-selected galaxies (SMGs) up to z ≈ 6. A Bayesian method is used to produce galaxy-scale universal calibrations of these molecular gas indicators, that hold over 3-4 orders of magnitude in infrared luminosity, L_ IR. Regarding the dust continuum, we use a mass-weighted dust temperature, T_ mw, determined using new empirical relations between temperature and luminosity. We find the average L/M_ mol gas mass conversion factors to be α_850= 6.9×10^12 W Hz^-1 M_⊙^-1, α_ CO = 4 M_⊙ (K km s^-1 pc^2)^-1 and α_ CI = 17.0 M_⊙ (K km s^-1 pc^2)^-1, based on the assumption that the mean dust properties of the sample (κ_H = gas-to-dust ratio/dust emissivity) will be similar to those of local metal rich galaxies and the MW. The tracer with the least intrinsic scatter is [CI](1-0), while CO(1-0) has the highest. The conversion factors show a weak but significant correlation with L_ IR. Assuming dust properties typical of metal-rich galaxies, we infer a neutral carbon abundance X_ CI = [C^0/ mol]=1.6× 10^-5, similar to that in the MW. We find no evidence for bimodality of α_ CO between main-sequence (MS) galaxies and those with extreme star-formation intensity, i.e. ULIRGs and SMGs. The means of the three conversion factors are found to be similar between MS galaxies and ULIRGs/SMGs, to within 10-20 show that for metal-rich galaxies, near-universal average values for α_ CO, X_ CI and κ_H are adequate for global molecular gas estimates.L Dunne, S J Maddox, P P Papadopoulos, R J Ivison, H L Gomezwork_jqawmcnloveq7lfrliomxatsvyTue, 02 Aug 2022 00:00:00 GMTA measurement of Hubble's Constant using Fast Radio Bursts
https://scholar.archive.org/work/7mutl77gundl5pktvdrkuxlvxa
We constrain the value of the Hubble constant H_0 by using a detailed model of Fast Radio Burst (FRB) observations from the Australian Square Kilometre Array Pathfinder (ASKAP) and Murriyang (Parkes) radio telescopes. We make use of the redshift-dispersion measure ('Macquart') relationship of FRB populations after accounting for the intrinsic luminosity function, cosmological gas distribution, population evolution, host galaxy contributions to the dispersion measure (DM_host), and observational biases due to burst duration, dispersion measure and telescope beamshape. Using an updated sample of 16 ASKAP FRBs detected by the Commensal Real-time ASKAP Fast Transients (CRAFT) Survey and localised to their host galaxies, and 60 unlocalised FRBs from Parkes and ASKAP, our best-fitting value of H_0 is calculated to be 73_-8^+12 km s^-1 Mpc^-1. The larger uncertainty than previous FRB works stems from our comprehensive treatment of FRB energetics and DM_ host. Using a prior on H_0 covering the 67–74 km s^-1 Mpc^-1 range, we estimate a median DM_ host = 186_-48^+59 pc cm^-3 which exceeds previous estimates from galaxy formation simulations and suggests a greater contribution from the progenitor environment of FRBs. Our large sample of FRB measurements confirms that the FRB population evolves similarly to the star-formation rate. We perform a forecast using a sample of 100 mock FRBs, demonstrating the accuracy of our model, and the potential for high-precision measurements (± 2.5 km s^-1 Mpc^-1) with the coherent FRB search upgrade to ASKAP. This may clarify the current Hubble tension in the near future as the sample of FRBs grows exponentially. Last, we explore a range of sample and selection biases that affect FRB analyses, in both current and future surveys.C.W. James, E.M. Ghosh, J.X. Prochaska, K.W. Bannister, S. Bhandari, C.K. Day, A.T. Deller, M. Glowacki, A.C. Gordon, K.E. Heintz, L. Marnoch, S.D. Ryder, D.R. Scott, R.M. Shannon, N. Tejoswork_7mutl77gundl5pktvdrkuxlvxaMon, 01 Aug 2022 00:00:00 GMTTidal Distortions in NGC1052-DF2 and NGC1052-DF4: Independent Evidence for a Lack of Dark Matter
https://scholar.archive.org/work/vqlxmrqcsjcspmq6cwctcxpx4a
Two ultra diffuse galaxies in the same group, NGC1052-DF2 and NGC1052-DF4, have been found to have little or no dark matter and to host unusually luminous globular cluster populations. Such low mass diffuse objects in a group environment are easily disrupted and are expected to show evidence of tidal distortions. In this work we present deep new imaging of the NGC1052 group, obtained with the Dragonfly Telephoto Array, to test this hypothesis. We find that both galaxies show strong position angle twists and are significantly more elongated at their outskirts than in their interiors. The group's central massive elliptical NGC1052 is the most likely source of these tidal disturbances. The observed distortions imply that the galaxies have a low total mass or are very close to NGC1052. Considering constraints on the galaxies' relative distances, we infer that the dark matter halo masses of these galaxies cannot be much greater than their stellar masses. Calculating pericenters from the distortions, we find that the galaxies are on highly elliptical orbits, with a ratio of pericenter to present-day radius Rperi/R0~0.1 if the galaxies are dark matter-free and Rperi/R0~0.01 if they have a normal dark halo. Our findings provide strong evidence, independent of kinematic constraints, that both galaxies are dark matter deficient. Furthermore, the similarity of the tidal features in NGC1052-DF2 and NGC1052-DF4 strongly suggests that they arose at comparable distances from NGC1052. In Appendix A, we describe sbcontrast, a robust method to determine the surface brightness limit of images.Michael A. Keim, Pieter van Dokkum, Shany Danieli, Deborah Lokhorst, Jiaxuan Li, Zili Shen, Roberto Abraham, Seery Chen, Colleen Gilhuly, Qing Liu, Allison Merritt, Tim B. Miller, Imad Pasha, Ava Polzinwork_vqlxmrqcsjcspmq6cwctcxpx4aMon, 01 Aug 2022 00:00:00 GMTTHE USE OF VIRTUAL REALITY IN EXPLORING THE NON- LINEAR INTERPRETATIONS OF THE LITERARY ARCHITECTURE – A CASE STUDY
https://scholar.archive.org/work/45fluwbmxnemdlmdwm6jlyld6y
No description suppliedAndre Brown, Yisi liu, Webb nickwork_45fluwbmxnemdlmdwm6jlyld6yFri, 29 Jul 2022 00:00:00 GMTDensity waves in protoplanetary discs excited by eccentric planets: linear theory
https://scholar.archive.org/work/w3t4gn7tuzbmtlgvl5l6v2a4vm
Spiral density waves observed in protoplanetary discs have often been used to infer the presence of embedded planets. This inference relies both on simulations as well as the linear theory of planet-disc interaction developed for planets on circular orbits to predict the morphology of the density wake. In this work we develop and implement a linear framework for calculating the structure of the density wave in a gaseous disc driven by an eccentric planet. Our approach takes into account both the essential azimuthal and temporal periodicities of the problem, allowing us to treat any periodic perturbing potential (i.e. not only that of an eccentric planet). We test our framework by calculating the morphology of the density waves excited by an eccentric, low-mass planet embedded in a globally isothermal disc and compare our results to the recent direct numerical simulations (and heuristic wavelet analysis) of the same problem by Zhu and Zhang. We find excellent agreement with the numerical simulations, capturing all the complex eccentric features including spiral bifurcations, wave crossings and planet-wave detachments, with improved accuracy and detail compared with the wavelet method. This illustrates the power of our linear framework in reproducing the morphology of complicated time-dependent density wakes, presenting it as a valuable tool for future studies of eccentric planet-disc interactions.Callum W. Fairbairn, Roman R. Rafikovwork_w3t4gn7tuzbmtlgvl5l6v2a4vmFri, 29 Jul 2022 00:00:00 GMTFirefly: a browser-based interactive 3D data visualization tool for millions of data points
https://scholar.archive.org/work/vlwnagbqazgc7pwvv2ahe255he
We present Firefly, a new browser-based interactive tool for visualizing 3D particle data sets. On a typical personal computer, Firefly can simultaneously render and enable real-time interactions with > ~10 million particles, and can interactively explore datasets with billions of particles using the included custom-built octree render engine. Once created, viewing a Firefly visualization requires no installation and is immediately usable in most modern internet browsers simply by visiting a URL. As a result, a Firefly visualization works out-of-the-box on most devices including smartphones and tablets. Firefly is primarily developed for researchers to explore their own data, but can also be useful to communicate results to researchers/collaborators and as an effective public outreach tool. Every element of the user interface can be customized and disabled, enabling easy adaptation of the same visualization for different audiences with little additional effort. Creating a new Firefly visualization is simple with the provided Python data pre-processor (PDPP) that translates input data to a Firefly-compatible format and provides helpful methods for hosting instances of Firefly both locally and on the internet. In addition to visualizing the positions of particles, users can visualize vector fields (e.g., velocities) and also filter and color points by scalar fields. We share three examples of Firefly applied to astronomical datasets: 1) the FIRE cosmological zoom-in simulations, 2) the SDSS galaxy catalog, and 3) Gaia DR3. A gallery of additional interactive demos is available at https://alexbgurvi.ch/Firefly.Alexander B. Gurvich, Aaron M. Gellerwork_vlwnagbqazgc7pwvv2ahe255heWed, 27 Jul 2022 00:00:00 GMTA Review of Recent Research into the Causes and Control of Noise during High-Speed Train Movement
https://scholar.archive.org/work/iu5j4x5fmra6zo5bqfi3o53vzy
Since the invention of the train, the problem of train noise has been a constraint on the development of trains. With increases in train speed, the main noise from high-speed trains has changed from rolling noise to aerodynamic noise, and the noise level and noise frequency range have also changed significantly. This paper provides a comprehensive overview of recent advances in the development of high-speed train noise. Firstly, the train noise composition is summarized; next, the main research methods for train noise, which include real high-speed train noise tests, wind tunnel tests, and numerical simulations, are reviewed and discussed. We also discuss the current methods of noise reduction for trains and summarize the progress in current research and the limitations of train body panels and railroad sound barrier technology. Finally, the article introduces the development and potential future applications of acoustic metamaterials and proposes application scenarios of acoustic metamaterials for the specific needs of railroad sound barriers and train car bodies. This synopsis provides a useful platform for researchers and engineers to cope with problems of future high-speed rail noise in the future.Hongyu Yan, Suchao Xie, Kunkun Jing, Zhejun Fengwork_iu5j4x5fmra6zo5bqfi3o53vzyTue, 26 Jul 2022 00:00:00 GMTA unified diagrammatic approach to topological fixed point models
https://scholar.archive.org/work/5gx3wybwbfdo7dxdswuotbuta4
We introduce a systematic mathematical language for describing fixed point models and apply it to the study to topological phases of matter. The framework is reminiscent of state-sum models and lattice topological quantum field theories, but is formalised and unified in terms of tensor networks. In contrast to existing tensor network ansatzes for the study of ground states of topologically ordered phases, the tensor networks in our formalism represent discrete path integrals in Euclidean space-time. This language is more directly related to the Hamiltonian defining the model than other approaches, via a Trotterization of the respective imaginary time evolution. We introduce our formalism by simple examples, and demonstrate its full power by expressing known families of models in 2+1 dimensions in their most general form, namely string-net models and Kitaev quantum doubles based on weak Hopf algebras. To elucidate the versatility of our formalism, we also show how fermionic phases of matter can be described and provide a framework for topological fixed point models in 3+1 dimensions.Andreas Bauer, Jens Eisert, Carolin Willework_5gx3wybwbfdo7dxdswuotbuta4Mon, 25 Jul 2022 00:00:00 GMTThe VMC Survey – XLIX. Discovery of a population of quasars dominated by nuclear dust emission behind the Magellanic Clouds
https://scholar.archive.org/work/fmj5vg22bvb2li3ualwuikjgzy
Following the discovery of SAGE0536AGN (z ∼ 0.14), with the strongest 10-μm silicate emission ever observed for an Active Galactic Nucleus (AGN), we discovered SAGE0534AGN (z ∼ 1.01), a similar AGN but with less extreme silicate emission. Both were originally mistaken as evolved stars in the Magellanic Clouds. Lack of far-infrared emission, and therefore star-formation, implies we are seeing the central engine of the AGN without contribution from the host galaxy. They could be a key link in galaxy evolution. We used a dimensionality reduction algorithm, t-SNE (t-distributed Stochastic Neighbourhood Embedding) with multi-wavelength data from Gaia EDR3, VISTA survey of the Magellanic Clouds, AllWISE and the Australian SKA Pathfinder to find these two unusual AGN are grouped with 16 other objects separated from the rest, suggesting a rare class. Our spectroscopy at SAAO/SALT and literature data confirm at least 14 of these objects are extragalactic (0.13 < z < 1.23), all hosting AGN. Using spectral energy distribution fitter CIGALE we find that the majority of dust emission (> 70 %) in these sources is due to the AGN. Host galaxies appear to be either in or transitioning into the green valley. There is a trend of a thinning torus, increasing X-ray luminosity and decreasing Eddington ratio as the AGN transition through the green valley, implying that as the accretion supply depletes, the torus depletes and the column density reduces. Also, the near-infrared variability amplitude of these sources correlates with attenuation by the torus, implying the torus plays a role in the variability.Clara M. Pennock, Jacco Th. van Loon, Joy O. Anih, Chandreyee Maitra, Frank Haberl, Anne E. Sansom, Valentin D. Ivanov, Michael J. Cowley, José Afonso, Sonia Antón, Maria-Rosa L. Cioni, Jessica E. M. Craig, Miroslav D. Filipović, Andrew M. Hopkins, Ambra Nanni, Isabella Prandoni, Eleni Vardoulakiwork_fmj5vg22bvb2li3ualwuikjgzyMon, 25 Jul 2022 00:00:00 GMTLearning effective stochastic differential equations from microscopic simulations: linking stochastic numerics to deep learning
https://scholar.archive.org/work/qvids2ife5etjapaocxrduzyki
We identify effective stochastic differential equations (SDE) for coarse observables of fine-grained particle- or agent-based simulations; these SDE then provide useful coarse surrogate models of the fine scale dynamics. We approximate the drift and diffusivity functions in these effective SDE through neural networks, which can be thought of as effective stochastic ResNets. The loss function is inspired by, and embodies, the structure of established stochastic numerical integrators (here, Euler-Maruyama and Milstein); our approximations can thus benefit from backward error analysis of these underlying numerical schemes. They also lend themselves naturally to "physics-informed" gray-box identification when approximate coarse models, such as mean field equations, are available. Existing numerical integration schemes for Langevin-type equations and for stochastic partial differential equations (SPDE) can also be used for training; we demonstrate this on a stochastically forced oscillator and the stochastic wave equation. Our approach does not require long trajectories, works on scattered snapshot data, and is designed to naturally handle different time steps per snapshot. We consider both the case where the coarse collective observables are known in advance, as well as the case where they must be found in a data-driven manner.Felix Dietrich and Alexei Makeev and George Kevrekidis and Nikolaos Evangelou and Tom Bertalan and Sebastian Reich and Ioannis G. Kevrekidiswork_qvids2ife5etjapaocxrduzykiSun, 24 Jul 2022 00:00:00 GMTExperimental investigation and reduced-order modelling of plasma jets in a turbulent boundary layer for skin-friction drag reduction
https://scholar.archive.org/work/o3zyufn6qfa6pbjlj7gc3i4g2y
Stereo particle imaging velocimetry measurements and reduced-order modelling are combined to provide a full picture of interaction of plasma jets with a turbulent boundary layer (TBL). Three working modes of the plasma actuator are investigated, corresponding to unidirectional jet (mode A), steady crashing jet (mode B) and spanwise oscillating jet (mode C). Results show that in mode C, a periodical alteration of two opposite wall jets can only be achieved at a low modulation frequency of 20 Hz. As the frequency increases to 100 Hz, the two unsteady wall jets collide in the middle, producing a meandering vertical jet column. In the cross-flow TBL, mode A induces a single streamwise vortex which grows in size within the plasma actuation zone and decays rapidly in strength after propagating beyond. As a comparison, modes B and C produce a counter-rotating vortex pair during the interaction. The skin-friction drag variations within the plasma actuation zone are dominated by the cross-stream momentum transportation of streamwise vortices. In the vortex upwash zone where a strong shear is present, high levels of turbulent kinetic energy are produced. Physically, the spanwise shaking and vertical jumping of plasma jet heads contribute noticeably to turbulent fluctuation. Experimental evidences support the simplification of streamwise momentum equation into a nonlinear transportation-diffusion equation, resulting in a reduced-order streamwise vortex transportation model. Detailed comparison with the experimental data shows that this model is able to give a reasonable prediction of the cross-stream flow patterns and streamwise velocity variations, within minutes.Haohua Zong, Zhi Su, Hua Liang, Yun Wuwork_o3zyufn6qfa6pbjlj7gc3i4g2yFri, 22 Jul 2022 00:00:00 GMTAlgebraically constrained finite element methods for hyperbolic problems with applications in geophysics and gas dynamics
https://scholar.archive.org/work/fqeijfrpzrannlpdhhcrf6ws7e
The research conducted in this thesis is focused on property-preserving discretizations of hyperbolic partial differential equations. Computational methods for solving such problems need to be carefully designed to produce physically meaningful numerical solutions. In particular, approximations to some quantities of interest should satisfy local and global discrete maximum principles. Moreover, numerical methods need to obey certain conservation relations, and convergence of approximations to the physically relevant exact solution should be ensured if multiple solutions may exist. Many algorithms based on the aforementioned design principles fall into the category of algebraic flux correction (AFC) schemes. Modern AFC discretizations of nonlinear hyperbolic systems express approximate solutions as convex combinations of intermediate states and constrain these states to be admissible. The main focus of our work is on monolithic convex limiting (MCL) strategies that modify spatial semi-discretizations in this way. Contrary to limiting approaches of predictor-corrector type, their monolithic counterparts are well suited for transient and steady problems alike. Further benefits of the MCL framework presented in this thesis include the possibility of enforcing entropy stability conditions in addition to discrete maximum principles. Using the AFC methodology, we transform finite element discretizations into property-preserving low order methods and perform flux correction to recover higher orders of accuracy without losing any desirable properties. The presented methods produce physics-compatible approximations, which exhibit excellent shock capturing capabilities. One novelty of this work is the tailor-made extension of monolithic convex limiting to the shallow water equations with a nonconservative topography term. Our generalized MCL schemes are entropy stable, positivity preserving, and well balanced in the sense that lake at rest equilibria are preserved. Another desirable property of numerical methods for the sha [...]Hennes Hajduk, Technische Universität Dortmundwork_fqeijfrpzrannlpdhhcrf6ws7eThu, 21 Jul 2022 00:00:00 GMTA Case Study on Renewable Energy Sources, Power Demand, and Policies in the States of South India—Development of a Thermoelectric Model
https://scholar.archive.org/work/5utv64ivlzcofjt2chxelntf3e
This work aims to perform a holistic review regarding renewable energy mix, power production approaches, demand scenarios, power policies, and investments with respect to clean energy production in the southern states of India. Further, a thermoelectric-generator model is proposed to meet rural demands using a proposed solar dish collector technology. The proposed model is based on the idea of employing a parabolic concentrator and a thermoelectric (TE) module to generate electricity directly from the sun's energy. A parabolic dish collector with an aperture of 1.11 m is used to collect sunlight and concentrate it onto a receiver plate with an area of 1.56 m in the proposed TE solar concentrator. The concentrated solar thermal energy is converted directly into electrical energy by using a bismuth telluride (BiTe)-based TE module mounted on the receiver plate. A rectangular fin heatsink, coupled with a fan, is employed to remove heat from the TE module's cool side, and a tracking device is used to track the sun continuously. The experimental results show considerable agreement with the mathematical model as well as its potential applications. Solar thermal power generation plays a crucial part in bridging the demand–supply gap for electricity, and it can be achieved through rural electrification using the proposed solar dish collector technology, which typically has a 10 to 25 kW capacity per dish and uses a Stirling engine to generate power. Here the experimentation work generates a voltage of 11.6 V, a current of 0.7 A, and a power of 10.5 W that can be used for rural electrification, especially for domestic loads.Vijayaraja Loganathan, Dhanasekar Ravikumar, Rupa Kesavan, Kanakasri Venkatesan, Raadha Saminathan, Raju Kannadasan, Mahalingam Sudhakaran, Mohammed H. Alsharif, Zong Woo Geem, Junhee Hongwork_5utv64ivlzcofjt2chxelntf3eWed, 20 Jul 2022 00:00:00 GMTMuseum specimens under scrutiny – new insights into the phylogeny of continental molluscs
https://scholar.archive.org/work/dwylawa3rrcf3lyilkxe4desxm
This dissertation shows how DNA sequence data derived from museum specimens of the family Vitrinidae were used to unravel some taxonomical conundrums in a hitherto neglected group within the malacological community (Chapters 1 and 2). In addition, phylogenetic problems in Swiss freshwater bivalves (Chapter 3) and introduces new and inexpensive laboratory protocols in conjunction with bioinformatic techniques for recent and ancient mollusc DNA investigations (Chapter 4).Beat Ulrich Pfarrerwork_dwylawa3rrcf3lyilkxe4desxmTue, 19 Jul 2022 00:00:00 GMTInvestigation of sketch interpretation techniques into 2D and 3D conceptual design geometry
https://scholar.archive.org/work/5ox5pthx7zdbzk5imsyjljbq7u
This thesis presents the results of new techniques investigated for applying on-line sketching into 2D and 3D conceptual design geometry throughout a whole development process: data collection, concrete curve segmentation and fitting, 2D geometric constraint extraction and solver, and 3D feature recognition and modelling. This is a new approach. A real time sketch and fuzzy knowledge-based prototype system has been developed in four phases. In the first phase, the segmentation approach investigated accepts the input of on-line free-hand sketch, and segments them into meaningful parts, by using fuzzy knowledge in terms of sketching position, direction, speed and acceleration. During the second phase, a parallel curve classification and identification method is studied by employing fuzzy heuristic knowledge in terms of curve linearity and convexity, in order to quickly classify and identify a variety of 2D shapes including straight lines, circles, arcs, ellipse, elliptical arcs, and free-form curves. Afterwards, a geometric constraint inference engine and a constraint solver are utilised according to degrees of freedom analysis, to capture a designer's intention, to infer geometric constraints simply and automatically, and to generate a possible solution without involving iterative computing. The solver also supports variational geometry in 2D and 3D. In the last phase, rule-based feature interpretation and manipulation techniques are investigated. While drawing, the 2D geometry is accumulated until it can be interpreted as a 3D feature. The feature is then placed in the 3D space and a new feature can be built incrementally upon previous versions. The given examples and case studies show that the system can interpret users' intention on 2D and 3D geometry satisfactorily and effectively. It can not only accept sketched input, but also users' menu-based interactive input of 2D primitives and 3D projections' This mixed automatic feature interpretation and interactive design environment can encourage designers with poo [...]Sheng-Feng Qinwork_5ox5pthx7zdbzk5imsyjljbq7uTue, 19 Jul 2022 00:00:00 GMTThe origin of the nuclear star-forming ring in NGC 3182
https://scholar.archive.org/work/slq7rgur3fco3a345wepgyplae
We investigate the stellar and ionized gas kinematics, and stellar populations of NGC3182 galaxy using integral field spectrograph data from the Calar Alto Legacy Integral Field Area survey. We try to clarify the nature of the ring structure in NGC 3182. We find a negative stellar age gradient out to the ring, while [α/Fe] considerably enhanced in the ring. The stellar metallicity shows a smooth negative gradient. From the line ratio diagnostic diagrams, we confirm that NGC 3182 is a Seyfert galaxy from emission line flux ratio, while the gas in the inner ring is ionized mostly by young stars. However, any obvious feature of outflows is not found in its gas kinematics. In the ring, star formation seems to have recently occurred and the gas metallicity is slightly enhanced compared to the center. From our results, we conclude that star formation has occurred in the circumnuclear region within a short period and this may result from a positive feedback by AGN radiation pressure.Mina Pak, Joon Hyeop Lee, Hyunjin Jeong, Woong-Seob Jeongwork_slq7rgur3fco3a345wepgyplaeThu, 14 Jul 2022 00:00:00 GMTSize-dependent transition from steady contraction to waves in actomyosin networks with turnover
https://scholar.archive.org/work/rxdwedttofbebfzhvog75t35pq
Actomyosin networks play essential roles in many cellular processes including intracellular transport, cell division, and cell motility, exhibiting a myriad of spatiotemporal patterns. Despite extensive research, how the interplay between network mechanics, turnover and geometry leads to these different patterns is not well understood. We focus on the size-dependent behavior of contracting actomyosin networks in the presence of turnover, using a reconstituted system based on cell extracts encapsulated in water-in-oil droplets. We find that the system can self-organize into different global contraction patterns, exhibiting persistent contractile flows in smaller droplets and periodic contractions in the form of waves or spirals in larger droplets. The transition between continuous and periodic contraction occurs at a characteristic length scale that is inversely dependent on the network contraction rate. These dynamics are recapitulated by a theoretical model, which considers the coexistence of different local density-dependent mechanical states with distinct rheological properties. The model shows how large-scale contractile behaviors emerge from the interplay between network percolation essential for long-range force transmission and rearrangements due to advection and turnover. Our findings thus demonstrate how varied contraction patterns can arise from the same microscopic constituents, without invoking specific biochemical regulation, merely by changing the system′s geometry.Ashwini Krishna, Mariya Savinov, Niv Ierushalmi, Alex Mogilner, Kinneret Kerenwork_rxdwedttofbebfzhvog75t35pqThu, 14 Jul 2022 00:00:00 GMT