IA Scholar Query: Decremental All-Pairs ALL Shortest Paths and Betweenness Centrality.
https://scholar.archive.org/
Internet Archive Scholar query results feedeninfo@archive.orgTue, 09 Aug 2022 00:00:00 GMTfatcat-scholarhttps://scholar.archive.org/help1440Algebra of Data Reconciliation
https://scholar.archive.org/work/m2radd2tsnferh2tddot63bcva
With distributed computing and mobile applications becoming ever more prevalent, synchronizing diverging replicas of the same data is a common problem. Reconciliation -- bringing two replicas of the same data structure as close as possible without overriding local changes -- is investigated in an algebraic model. Our approach is to consider two sequences of simple commands that describe the changes in the replicas compared to the original structure, and then determine the maximal subsequences of each that can be propagated to the other. The proposed command set is shown to be functionally complete, and an update detection algorithm is presented which produces a command sequence transforming the original data structure into the replica while traversing both simultaneously. Syntactical characterization is provided in terms of a rewriting system for semantically equivalent command sequences. Algebraic properties of sequence pairs that are applicable to the same data structure are investigated. Based on these results the reconciliation problem is shown to have a unique maximal solution. In addition, syntactical properties of the maximal solution allow for an efficient algorithm that produces it.Elod P. Csirmaz, Laszlo Csirmazwork_m2radd2tsnferh2tddot63bcvaTue, 09 Aug 2022 00:00:00 GMTLargest Inscribed Rectangles in Geometric Convex Sets
https://scholar.archive.org/work/ohu3pvbptbg7ldujjiexc22wye
This paper considers the problem of finding maximum volume (axis-aligned) inscribed boxes in a compact convex set, defined by a finite number of convex inequalities, and presents optimization and geometric approaches for solving them. Several optimization models are developed that can be easily generalized to find other inscribed geometric shapes such as triangles, rhombi, and squares. To find the largest axis-aligned inscribed rectangles in the higher dimensions, an interior-point method algorithm is presented and analyzed. For 2-dimensional space, a parametrized optimization approach is developed to find the largest (axis-aligned) inscribed rectangles in convex sets. The optimization approach provides a uniform framework for solving a wide variety of relevant problems. Finally, two computational geometric (1-ε)–approximation algorithms with sub-linear running times are presented that improve the previous results.Mehdi Behrooziwork_ohu3pvbptbg7ldujjiexc22wyeTue, 09 Aug 2022 00:00:00 GMTLIPIcs, Volume 238, DNA 28, Complete Volume
https://scholar.archive.org/work/627o3xn4vbbgpdox5dwolgcuny
LIPIcs, Volume 238, DNA 28, Complete VolumeThomas E. Ouldridge, Shelley F. J. Wickhamwork_627o3xn4vbbgpdox5dwolgcunyThu, 04 Aug 2022 00:00:00 GMTBreaking the Cubic Barrier for All-Pairs Max-Flow: Gomory-Hu Tree in Nearly Quadratic Time
https://scholar.archive.org/work/aeib45wasbeyffdqstath24axm
In 1961, Gomory and Hu showed that the All-Pairs Max-Flow problem of computing the max-flow between all n 2 pairs of vertices in an undirected graph can be solved using only n-1 calls to any (single-pair) max-flow algorithm. Even assuming a linear-time max-flow algorithm, this yields a running time of O(mn), which is O(n^3) when m = Θ(n^2). While subsequent work has improved this bound for various special graph classes, no subcubic-time algorithm has been obtained in the last 60 years for general graphs. We break this longstanding barrier by giving an Õ(n^2)-time algorithm on general, weighted graphs. Combined with a popular complexity assumption, we establish a counter-intuitive separation: all-pairs max-flows are strictly easier to compute than all-pairs shortest-paths. Our algorithm produces a cut-equivalent tree, known as the Gomory-Hu tree, from which the max-flow value for any pair can be retrieved in near-constant time. For unweighted graphs, we refine our techniques further to produce a Gomory-Hu tree in the time of a poly-logarithmic number of calls to any max-flow algorithm. This shows an equivalence between the all-pairs and single-pair max-flow problems, and is optimal up to poly-logarithmic factors. Using the recently announced m^1+o(1)-time max-flow algorithm (Chen et al., March 2022), our Gomory-Hu tree algorithm for unweighted graphs also runs in m^1+o(1)-time.Amir Abboud, Robert Krauthgamer, Jason Li, Debmalya Panigrahi, Thatchaphol Saranurak, Ohad Trabelsiwork_aeib45wasbeyffdqstath24axmWed, 03 Aug 2022 00:00:00 GMTUsing Reinforcement Learning to Improve Airspace Structuring in an Urban Environment
https://scholar.archive.org/work/exbz573vkjdergl3nz5zdyfqoi
Current predictions on future drone operations estimate that traffic density orders of magnitude will be higher than any observed in manned aviation. Such densities redirect the focus towards elements that can decrease conflict rate and severity, with special emphasis on airspace structures, an element that has been overlooked within distributed environments in the past. This work delves into the impacts of different airspace structures in multiple traffic scenarios, and how appropriate structures can increase the safety of future drone operations in urban airspace. First, reinforcement learning was used to define optimal heading range distributions with a layered airspace concept. Second, transition layers were reserved to facilitate the vertical deviation between cruising layers and conflict avoidance. The effects of traffic density, non-linear routes, and vertical deviation between layers were tested in an open-source airspace simulation platform. Results show that optimal structuring catered to the current traffic scenario improves airspace usage by correctly segmenting aircraft according to their flight routes. The number of conflicts and losses of minimum separation was reduced versus using a single, uniform airspace structure for all traffic scenarios, thus enabling higher airspace capacity.Marta Ribeiro, Joost Ellerbroek, Jacco Hoekstrawork_exbz573vkjdergl3nz5zdyfqoiMon, 01 Aug 2022 00:00:00 GMTWhat Can Be Certified Compactly? Compact local certification of MSO properties in tree-like graphs
https://scholar.archive.org/work/wyl6rlfhtfbqpnljje5cu27m7i
Local certification consists in assigning labels (called certificates) to the nodes of a network to certify a property of the network or the correctness of a data structure distributed on the network. The verification of this certification must be local: a node typically sees only its neighbors in the network. The main measure of performance of a certification is the size of its certificates. In 2011, Göös and Suomela identified Θ(log 𝑛) as a special certificate size: below this threshold little is possible, and several key properties do have certifications of this type. A certification with such small certificates is now called a compact local certification, and it has become the gold standard of the area, similarly to polynomial time for centralized computing. A major question is then to understand which properties have 𝑂 (log 𝑛) certificates, or in other words: what is the power of compact local certification? Recently, a series of papers have proved that several well-known network properties have compact local certifications: planarity, bounded-genus, etc. But one would like to have more general results, i.e. meta-theorems. In the analogous setting of polynomialtime centralized algorithms, a very fruitful approach has been to prove that restricted types of problems can be solved in polynomial time in graphs with restricted structures. These problems are typically those that can be expressed in some logic, and the graph structures are those with bounded width or depth parameters. We take a similar approach and prove several meta-theorems for local certification. More precisely, the logic we use is MSO, the most classic fragment for logics on graphs, where one can quantify over vertices and sets of vertices, and consider adjacency between vertices. We prove the relevance of this choice in the context of local certification by first considering properties of trees. On trees, we prove that MSO properties can be certified with labels of constant size, whereas the typical non-MSO property of isomorphism requires Ω(𝑛) size certificates (where Ω hides polylogarithmic factors). We then move on to graphs of bounded treedepth, a well-known parameter that basically measures how far a graph is from a star. We first prove that an optimal certification for bounded treedepth uses certificatesLaurent Feuilloley, Nicolas Bousquet, Théo Pierronwork_wyl6rlfhtfbqpnljje5cu27m7iWed, 20 Jul 2022 00:00:00 GMTAutomated Black-Box Boundary Value Detection
https://scholar.archive.org/work/4dl6jryeejabxiu2zxi7ttz4zu
The input domain of software systems can typically be divided into sub-domains for which the outputs are similar. To ensure high quality it is critical to test the software on the boundaries between these sub-domains. Consequently, boundary value analysis and testing has been part of the toolbox of software testers for long and is typically taught early to students. However, despite its many argued benefits, boundary value analysis for a given specification or piece of software is typically described in abstract terms which allow for variation in how testers apply it. Here we propose an automated, black-box boundary value detection method to support software testers in systematic boundary value analysis with consistent results. The method builds on a metric to quantify the level of boundariness of test inputs: the program derivative. By coupling it with search algorithms we find and rank pairs of inputs as good boundary candidates, i.e. inputs close together but with outputs far apart. We implement our AutoBVA approach and evaluate it on a curated dataset of example programs. Our results indicate that even with a simple and generic program derivative variant in combination with broad sampling over the input space, interesting boundary candidates can be identified.Felix Dobslaw and Robert Feldt and Francisco de Oliveira Netowork_4dl6jryeejabxiu2zxi7ttz4zuTue, 19 Jul 2022 00:00:00 GMTPhotometric IGM Tomography: Efficiently Mapping Quasar Light Echoes with Deep Narrow Band Imaging
https://scholar.archive.org/work/2tmcmvulr5hddapf2bibpayzbe
In the standard picture, episodes of luminous quasar activity are directly related to supermassive black hole (SMBH) growth. The ionising radiation emitted over a quasar's lifetime alters the ionisation state of the surrounding intergalactic medium (IGM), enhancing the Lyα forest transmission – so-called proximity effect – which can be observed in absorption spectra of background sources. Owing to the finite speed of light, the transverse direction of the proximity effect is sensitive to the quasar's radiative history, resulting in 'light echoes' that encode the growth history of the SMBH on Myr-timescales. In this paper, we introduce a new technique to photometrically map this quasar light echoes using Lyα forest tomography by using a carefully selected pair of narrow-band filters. A foreground narrow-band filter is used to measure Lyα forest transmission along background galaxies selected as Lyα emitters by a background narrow-band filter. This novel double narrow-band tomographic technique utilises the higher throughput and wider field of view of imaging over spectroscopy to efficiently reconstruct a two-dimensional map of Lyα forest transmission around a quasar. We present a fully Bayesian framework to measure the luminous quasar lifetime of a SMBH from photometric IGM tomography, and examine the observational requirements. This new technique provides an efficient strategy to map a large area of the sky with a modest observing time and to identify interesting regions to be examined by further deep 3D follow-up spectroscopic Lyα forest tomography.Koki Kakiichi, Tobias Schmidt, Joseph Hennawiwork_2tmcmvulr5hddapf2bibpayzbeSun, 17 Jul 2022 00:00:00 GMTFoundations of Clustering: New Models and Algorithms
https://scholar.archive.org/work/ejn3zmumfzbwvaeircgyztx7ea
In this dissertation, we study clustering, one of the most common unsupervised learning problems. This dissertation covers recent developments in both clustering theory and machine learning practice. In particular, it explores how to bridge the gap between theory and practice by making them benefit from each other. Many clustering algorithms are developed in an application-oriented way lacking the guidance of theory. For some clustering problems it is hard to mathematically characterize what is being optimized. The arising needs in the ML/AI community, such as fairness and scalability, also require updates in current problem formulations. The first few chapters of this dissertation lay the theoretical foundation for multiple clustering problems. We first establish the formal optimization framework. Such a framework gives us conceptual understanding of the problems and becomes the basis for optimization and algorithm design. We then discuss the performance of existing approaches and come up with new algorithms beating the state-of-the-art. Empirical evaluations also verify that the new algorithms perform better in both quality and efficiency, showing it is beneficial to view these problems through the lens of theory. We study one classic clustering problem: hierarchical clustering. Unlike other more well-formulated clustering problems such as k-means, the theoretical study of hierarchical clustering has kicked off recently. The first chapter focuses on new objective function design for hierarchical clustering on point inputs in a Euclidean space. It provides theoretical guarantees for a popular heuristic. The second chapter studies how to incorporate fairness into the hierarchical clustering optimization framework. It defines fair hierarchical clustering trees and discusses how to design algorithms that find fair solutions for previous hierarchical clustering objectives established by the community. Surprisingly, in this setting fairness could be imposed at minimal loss in clustering solution performance. The focu [...]Yuyan Wangwork_ejn3zmumfzbwvaeircgyztx7eaMon, 11 Jul 2022 00:00:00 GMTParallel Batch-Dynamic Algorithms for k-Core Decomposition and Related Graph Problems
https://scholar.archive.org/work/w3vbat47sjgt3b7g3yzc6x5nuy
Maintaining a k-core decomposition quickly in a dynamic graph has important applications in network analysis. The main challenge for designing efficient exact algorithms is that a single update to the graph can cause significant global changes. Our paper focuses on approximation algorithms with small approximation factors that are much more efficient than what exact algorithms can obtain. We present the first parallel, batch-dynamic algorithm for approximate k-core decomposition that is efficient in both theory and practice. Our algorithm is based on our novel parallel level data structure, inspired by the sequential level data structures of Bhattacharya et al [STOC '15] and Henzinger et al [2020]. Given a graph with n vertices and a batch of updates ℬ, our algorithm provably maintains a (2 + ε)-approximation of the coreness values of all vertices (for any constant ε > 0) in O(|ℬ|log^2 n) amortized work and O(log^2 n loglog n) depth (parallel time) with high probability. As a by-product, our k-core decomposition algorithm also gives a batch-dynamic algorithm for maintaining an O(α) out-degree orientation, where α is the current arboricity of the graph. We demonstrate the usefulness of our low out-degree orientation algorithm by presenting a new framework to formally study batch-dynamic algorithms in bounded-arboricity graphs. Our framework obtains new provably-efficient parallel batch-dynamic algorithms for maximal matching, clique counting, and vertex coloring. We implemented and experimentally evaluated our k-core decomposition algorithm on a 30-core machine with two-way hyper-threading on 11 graphs of varying densities and sizes. [...]Quanquan C. Liu, Jessica Shi, Shangdi Yu, Laxman Dhulipala, Julian Shunwork_w3vbat47sjgt3b7g3yzc6x5nuyThu, 07 Jul 2022 00:00:00 GMTResearch on Nickel Material Trade Redistribution Strategy Based on the Maximum Entropy Principle
https://scholar.archive.org/work/elc76myzxbg4rbwowpewvbwigm
In the double carbon background, riding the wind of new energy vehicles and the battery high nickelization, nickel resources rise along with the trend. In recent years, due to the influence of geopolitical conflicts and emergencies, as well as the speculation and control of international capital with its advantages and rules, the world may face price and security supply risks to a certain extent. Therefore, to obtain the most objective trade redistribution strategy, this paper first constructs the nickel material trade network, identifies the core trading countries and the main trade relations of nickel material trade, and finds that the flow of nickel material mainly occurred between a few countries. On this basis, a trade redistribution model is constructed based on the maximum entropy principle. Taking Indonesia, the largest exporter, and the largest trade relationship (Indonesia exports to China) as examples, the nickel material redistribution between countries when different supply risks occur are simulated. The results can provide an important reference for national resource recovery after the risk of the nickel trade.Xingxing Wang, Anjian Wang, Weiqiong Zhong, Depeng Zhuwork_elc76myzxbg4rbwowpewvbwigmWed, 06 Jul 2022 00:00:00 GMTSpecial Relativity – Applications to astronomy and the accelerator physics
https://scholar.archive.org/work/vsow62e7h5dgvlyckzrwsnqi7u
There are many books on the classical subject of special relativity. However, after having spent a number of years, both in relativistic engineering and research with relativity, I have come to the conclusion that there exist a place for a new book. I do believe that the present book is not quite the same as the others, mainly due to attempt to cast light on dark corners. I should make it clear what this little book is not. It is not a textbook on relativity theory. What the book is about is the nature of special relativistic kinematics, its relation to space and time, and the operational interpretation of coordinate transformations. Every theory contains a number of quantities that can be measured by experiment and an expressions that cannot possibly be observed. Whenever we have a theory containing an arbitrary convention, we should examine what parts of the theory depend on the choice of that convention and what parts do not. The distinction is not always made and many authors claim some data to be observable, according to arbitrary conventions, which do not correspond to any physical experiment. This leads to inconsistencies and paradoxes that should be avoided at all cost.Evgeny Saldinwork_vsow62e7h5dgvlyckzrwsnqi7uTue, 05 Jul 2022 00:00:00 GMTTowards Real-Time Counting Shortest Cycles on Dynamic Graphs: A Hub Labeling Approach
https://scholar.archive.org/work/bb5eaujf7vg4dgek3dwz36kbkm
With the ever-increasing prevalence of graph data in a wide spectrum of applications, it becomes essential to analyze structural trends in dynamic graphs on a continual basis. The shortest cycle is a fundamental pattern in graph analytics. In this paper, we investigate the problem of shortest cycle counting for a given vertex in dynamic graphs in light of its applicability to problems such as fraud detection. To address such queries efficiently, we propose a 2-hop labeling based algorithm called Counting Shortest Cycle (CSC for short). Additionally, techniques for dynamically updating the CSC index are explored. Comprehensive experiments are conducted to demonstrate the efficiency and effectiveness of our method. In particular, CSC enables query evaluation in a few hundreds of microseconds for graphs with millions of edges, and improves query efficiency by two orders of magnitude when compared to the baseline solutions. Also, the update algorithm could efficiently cope with edge insertions (deletions).Qingshuai Feng, You Peng, Wenjie Zhang, Ying Zhang, Xuemin Linwork_bb5eaujf7vg4dgek3dwz36kbkmSun, 03 Jul 2022 00:00:00 GMTStructural investigations of elemental metals at multi-megabar pressures using toroidal diamond anvil cells
https://scholar.archive.org/work/xcrwnwiqwrbivdefiodnzjs32y
Research at high pressures has revealed that the elemental metals, most of which have simple crystal structures at ambient conditions such as face-centred cubic, body-centred cubic, or hexagonal close-packed, transition to more complex structures at high pressure. X-ray diffraction methods are well-suited to exploring these complexities, providing detailed data on the structure of elements at high pressure. In particular, this work focuses on studying the alkali metals K and Rb with x-ray diffraction methods. These elements have been found to exhibit a wealth of structural complexity such as the incommensurate host-guest structures K-III and Rb-VI, or the orthorhombic Cmca phases of K-VI and Rb-VI. To study these and other elements at high pressures, diamond anvil cells are frequently used to compress the sample, as they allow for accurate structure identification using x-ray diffraction and can reliably reach pressures of around 300 GPa. However, the study of elements at even higher pressures becomes difficult using conventional diamond anvil cells which are prone to diamond failure at these conditions. This has motivated the development of new DAC designs. In particular, toroidal diamond anvil cells are a promising modification wherein the diamond anvils are 'sculpted' to create a geometry able to achieve pressures above 500 GPa. This work initially investigates the behaviour of the light metals Mg and Al and the alkali metals K and Rb, using conventional diamond anvil cell techniques. The phase transitions of Mg and Al are discussed, with compression data up to 301 GPa and 236 GPa presented for Mg and Al, respectively. Equations of state are fitted for each metal and the data are compared to other studies in the field. In K and Rb, the static phase diagrams are extended up to 321 GPa and 264 GPa, respectively. These studies observe significant changes in the compression curves occurring between 0-100 GPa, where the various phase transitions of these metals display a great variety of compressive behaviour. The [...]Christian Viktor Storm, University Of Edinburgh, Malcolm McMahon, John Lovedaywork_xcrwnwiqwrbivdefiodnzjs32yThu, 30 Jun 2022 00:00:00 GMTA genetic algorithm for finding microgrid cable layouts
https://scholar.archive.org/work/r55vb5iqvzbkhhwhr72n7ekugy
Microgrids play a crucial role in the electrification of rural areas. Designing a microgrid comprises of multiple parts including finding suitable sites for generation units, sizing the components of the microdgrid, and determining the layout of the cables to connect the components. In this work we focus on the latter part, which we formalize as the Microgrid Cable Layout problem. In this problem we assume that the locations and sizes of the generators and consumers are already given. The goal is to find a cost-minimal cable layout that connects these locations and that is sufficient to handle the consumer demands. The cables may be of different cable types, and we may connect multiple cables not only at the locations of the generators and consumers but also at any other point. Microgrid Cable Layout is a strongly N P-hard, non-linear optimization problem. We present a hybrid algorithm for the Microgrid Cable Layout problem, which employs a genetic algorithm for optimizing the topology of the layout and a heuristic for assigning the cables to the edges of the topology. An evaluation on a set of benchmark instances indicates that this algorithm is able to find good solutions within a short amount of time. We further evaluate the performance of the algorithm in a case study on a real-world microgrid in the Democratic Republic of the Congo. CCS CONCEPTS • Theory of computation → Algorithm design techniques; Graph algorithms analysis.Max Göttlicher, Matthias Wolfwork_r55vb5iqvzbkhhwhr72n7ekugyTue, 28 Jun 2022 00:00:00 GMTErudite Fish Swarm Optimization Based Routing Protocol to Maximize Wireless Sensor Network Lifetime
https://scholar.archive.org/work/sr2nyg7utrahxj4ha36eoarnbu
Wireless Sensor Networks (𝐖𝐒𝐍s) are an influential network form that comprises remote nodes having sensing, processing, and communication capabilities. 𝐖𝐒𝐍 is a unique adhoc network with a wireless telecommunications infrastructure that effectively supports, observes, and responds to natural and artificial events. It is impossible to employ the ad-hoc network routing methods in sensor networks since they are not scalable. WSN relies on the routing protocol to get data from sensors to their final destination in a timely way. If the routing protocol fails to work, then it is expected that a significant amount of time and effort will be spent finding the most efficient route, increasing the likelihood that the worst possible option will be selected. Because of this, WSN routing protocols must include the concept of "erudite" features, which refers to a high degree of sensing of the nodes around them to determine the optimum path. Fish swarm optimization is the basis of the new WSN routing protocol proposed in this paper, namely the Erudite Fish Swarm Optimization Based Routing Protocol (𝐄𝐅𝐒𝐎𝐑𝐏). In EFSORP, nodes are treated as fishes. Nodes having prior knowledge about routes are selected at random. Foraging, following, swarming, and random movement is four of the most common behaviors of fishes while seeking food. These behaviors are mimicked to identify the best routes in WSN. EFSORP's performance is evaluated in NS3. A wide range of necessary computer network performance measures are used to assess 𝐄𝐅𝐒𝐎𝐑𝐏 against existing routing protocols. 𝐄𝐅𝐒𝐎𝐑𝐏's results show that it outperforms the current routing protocols on all measures.A. Balasubramanian, P. Ponmuthuramalingamwork_sr2nyg7utrahxj4ha36eoarnbuTue, 28 Jun 2022 00:00:00 GMTHigh-Definition Map Generation Technologies For Autonomous Driving
https://scholar.archive.org/work/2qlotwsapfc6fdl3tewdjxotyi
Autonomous driving has been among the most popular and challenging topics in the past few years. On the road to achieving full autonomy, researchers have utilized various sensors, such as LiDAR, camera, Inertial Measurement Unit (IMU), and GPS, and developed intelligent algorithms for autonomous driving applications such as object detection, object segmentation, obstacle avoidance, and path planning. High-definition (HD) maps have drawn lots of attention in recent years. Because of the high precision and informative level of HD maps in localization, it has immediately become one of the critical components of autonomous driving. From big organizations like Baidu Apollo, NVIDIA, and TomTom to individual researchers, researchers have created HD maps for different scenes and purposes for autonomous driving. It is necessary to review the state-of-the-art methods for HD map generation. This paper reviews recent HD map generation technologies that leverage both 2D and 3D map generation. This review introduces the concept of HD maps and their usefulness in autonomous driving and gives a detailed overview of HD map generation techniques. We will also discuss the limitations of the current HD map generation technologies to motivate future research.Zhibin Bao, Sabir Hossain, Haoxiang Lang, Xianke Linwork_2qlotwsapfc6fdl3tewdjxotyiFri, 24 Jun 2022 00:00:00 GMTComputerized Design, Simulation of Meshing and Stress Analysis of External Helical Gear Drives Based on Critical Control Points
https://scholar.archive.org/work/72mwalq6cbdqvmsziqnj2ws7m4
Helical gears are widely used in powertrain systems. The computerized design of a new type of non-generated external helical gears based on critical control points at the transverse tooth profile is presented. The entire tooth profile is divided into different parts including the active tooth profile and fillet by control points. Involutes, circular arcs and Hermite curves are defined between two critical control points and smoothly connected with each other at those control points. The parametric equations for the tooth surfaces are derived considering the position of the mentioned control points. The basic design parameters and equations of the geometric sizing are proposed. The contact patterns, variation of the maximum stresses and peak-to-peak level of loaded transmission errors for six cases of design of the proposed new geometry of helical gear drives are studied with two cases of traditional helical gear drives as a reference, including gears with and without micro-geometry modifications. One case of an external helical gear drive designed with a combination of a circular arc and an involute to form the active tooth profile for both the pinion and the gear shows a much lower maximum bending stress and similar lower peak-to-peak level of loaded transmission errors with respect to the other cases of design. The proposed design method of tooth profiles based on critical control points lays the foundation for the topological optimization of helical gear drives.Zhen Chen, Bo Lei, Ling Qin, Guoting Qiu, Alfonso Fuentes-Aznarwork_72mwalq6cbdqvmsziqnj2ws7m4Sat, 11 Jun 2022 00:00:00 GMTVariations in Manual Dexterity in 11- and 12-Year-Old Children in the North of Spain in the SARS-CoV-2 Lockdown
https://scholar.archive.org/work/5fo6olwq25e37jd5l74q2yxuii
Between March and June 2019, the SARS-CoV-2 virus broke out in Spain. The lockdown in response entailed the modification of certain habits in the infant–juvenile population, such as those related to the practice of physical activity and the implications derived from it. The aim of this study was to learn the impacts that lockdown had on manual dexterity in children aged 11–12 years. Methods: A total of 50 Spanish children aged 11–12 years (M = 11.40; SD = 0.50) participated, 33 (66%) boys and 17 (34%) girls. The Movement Assessment Battery for Children 2 (Movement ABC-2) and an ad hoc questionnaire for socio-demographic data and other relevant information were administered for the data collection. Results: There are significant differences (p < 0.05) in the results for the manual dexterity variables measured by the peg turning and line drawing tests as well as by the measured, scalar and percentile dimension scores for manual dexterity between before and after the lockdown in both boys and girls. No significant differences were found in measurements related to the triangle assembly variable (p = 0.125). Conclusions: A significant negative impact of SARS-CoV-2 lockdown on manual dexterity values was evident in boys and girls aged 11–12 years.Oliver Ramos-Álvarez, Víctor Arufe-Giráldez, Alberto Sanmiguel-Rodríguez, Rubén Navarro-Patónwork_5fo6olwq25e37jd5l74q2yxuiiFri, 10 Jun 2022 00:00:00 GMT77777777777777777777
https://scholar.archive.org/work/yr4dd2wzeneq5eydistmrwda2q
Once the record has been published, you can no longer change the files in the record,Kjkwork_yr4dd2wzeneq5eydistmrwda2qTue, 07 Jun 2022 00:00:00 GMT