bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Line Integral Convolution-Based Vortex Detection Using Computer Vision
Authors: Abolholl Hazem Ashor Amran , Teschner Tom-Robin , Moulitsas Irene
Published: January 2023

Vortex cores in fluid mechanics are easy to visualize, yet difficult to detect numerically. Precise knowledge of these allows fluid dynamics researchers to study complex flow structures and allow for a better understanding of the turbulence transition process and the development and evolution of flow instabilities, to name but a few relevant areas. Various approaches such as the Q, delta, and swirling strength criterion have been proposed to visualize vortical flows, and these approaches can be used to detect vortex core locations. Using these methods can result in spuriously detected vortex cores and which can be balanced by a cutoff filter, making these methods lack robustness. To overcome this shortcoming, we propose a new approach using convolutional neural networks to detect flow structures directly from streamline plots, using the line integral convolution method. We show that our computer vision-based approach is able to reduce the number of false positives and negatives while removing the need for a cutoff. We validate our approach using the Taylor–Green vortex problem to generate input images for our network. We show that with an increasing number of images used for training, we are able to monotonically reduce the number of false positives and negatives. We then apply our trained network to a different flow problem where vortices are still reliably detected. Thus, our study presents a robust approach that allows for reliable vortex detection which is applicable to a wide range of flow scenarios.
Study on Machining Quality of Aluminum Honeycomb in Ultrasonic Cutting by Disc Cutter
Authors: Sun Jiansong , Kang Renke , Guo Jialin , Dong Zhigang , Wang Yidan
Published: January 2023

Aluminum honeycomb has been highlighted in aeronautics and astronautics in the form of the sandwich structure, but defects are easily generated during machining. Ultrasonic cutting for honeycomb material has received growing attention over the past years for improved machining quality and efficiency. In order to support the industrial application of the ultrasonic cutting for aluminum honeycomb by disc cutter, a finite element (FE) model is established and experimental investigations are conducted to study the influencing factors of the machining quality. The proposed FE model is verified by the comparison of cutting forces obtained from simulations and experiments. Based on the FE model and experiments, influences of tool orientation precisions, including lead angle and runout of disc cutter, are analyzed first. Moreover, cutting force, honeycomb morphology, the stress in the cutting zone, and cell wall deformation at different cutting parameters are investigated. Results show that the lead angle should be set as a slightly positive value, and the axial runout of the disc cutter should be controlled to an extremely small value to avoid machining defects. Meanwhile, the cutting forces decrease significantly with the application of the ultrasonic vibration and increase with the increases in the feed speed and the cutting depth. Therefore, a well-machined surface can be obtained by applying ultrasonic vibration, cutting at a lower feed speed, and a smaller cutting depth.
Contact Path Method of Generating Spherical Conjugated Curves as Bevel Gearing Tooth Profiles
Authors: Leeheng Chan Cody
Published: January 2023

This paper proposes a general method to generate spherical conjugated curves based on their contact path. The main objective of generating conjugated curves is to use them as gearing tooth profiles. The derivation is based on the prescribed spherical contact path, the equation of meshing, and the rigid body motion between two bodies. This paper demonstrates the method by assigning great circle and small circle contact paths in circular pitch pair transmission to generate conjugated curves. With the great circle contact path, the conjugated curves are exact spherical involute, and with the small circle contact path, the conjugated curves are spherical cycloid. The contact properties of the conjugated curves, such as induced curvature and the sliding ratio, are also provided with mathematical equations. Based on the results, the procedures and the geometries between the planar and spherical contact path methods have corresponding relationships. In contrast to the Camus theorem, the exact spherical involute could be generated from a similar procedure of planar involute cases. The ultimate goal of this research topic is to propose a general approach to generating conjugated profiles in planar, spherical, and spatial cases. The successful derivation of the spherical cases in this paper paves the way for spatial cases in the future.
Design of a New Family of Kinematically Redundant Parallel Mechanisms With Two Rotations and One Translation
Authors: Wu Zhen , Li Qinchuan , Ye Wei
Published: January 2023

This article presents a new family of kinematically redundant parallel mechanisms (KR-PMs) with two rotations and one translation (2R1T) based on the Lie group method. Compared with the 2-UPR/RPU PM, these PMs have two main advantages, namely, larger reachable workspaces of the moving platforms and higher motion/force transmission performance, as verified by three typical cases. The inverse kinematics, velocities, singularities, and workspaces of the 2-UPR/PRPU PM are analyzed in detail. A new method for motion/force transmission performance evaluation of KR-PMs in accordance with the indices for nonredundant PMs is proposed. Moreover, the local and global motion/force transmission performances of the 2-UPR/PRPU PM are determined using the new method.
Kinematics Analysis of 6-Degrees-of-Freedom Parallel + Serial Type Hybrid Mechanisms Containing Parallel Mechanism With High Coupling Motions
Authors: Hu Bo , Liu Zhiyong , Zhao Jinjun , Zhao Jingyu , Yao Jiantao
Published: January 2023

The existing displacement of parallel + serial type hybrid mechanisms is mainly solved by the equivalent serial mechanism (SM) method. However, a large number of lower mobility parallel mechanisms (PMs) that have high coupled motions at the end-effector cannot be equivalent to SMs. Thus, the displacement problem especially for the inverse displacement of this type of hybrid mechanisms has not been well solved. On the basis of this situation, this article takes a 6-degrees-of-freedom (DOFs) 3-UPU + 3R hybrid mechanism as an example to give a general method to solve the displacement problem. First, based on the inverse displacement and pose coupling relationship of the 3-UPU PM, its forward displacement is solved by Sylvester’s dialytic elimination method, and then the forward displacement of the 3-UPU + 3R hybrid mechanism is obtained by the superposition method. Second, by skillfully dealing with the relationship between coupling motions of the 3-UPU PM and the motion of hybrid mechanism, three nonlinear equations containing three unknown motion parameters are obtained, and the inverse displacement problem is solved using Sylvester’s dialytic elimination. The research in this article is valuable in the kinematics modeling of hybrid mechanisms.
Design and Analysis of an Active Swing Decoupling Compliant Mechanism With Multiple Co-Directional Input Branches
Authors: Liu Guoshuai , Liu Pengbo , Yan Peng , Shi Yushu
Published: January 2023

In this work, we propose a novel bio-inspired swing decoupling mechanism supporting high precision motion systems, which is composed of multiple co-directional input branches with a rigid swing unit and an anti-rotational guiding unit. By actively adjusting the input displacements, the decoupling mechanism can switch between the swing and translational modes, where the parasitic rotations can be significantly suppressed by the anti-rotational guiding unit. With this, fully decoupled X and Y linear motions are obtained in the presence of co-directional input branches. A theoretical model of the decoupling mechanism is also established to accurately describe the decoupling behavior, which is verified by finite element simulations. A prototype of the proposed swing decoupling mechanism is fabricated and instrumented with comprehensive experimental apparatus, where the experimental results effectively validate the excellent decoupling performance and demonstrate good potentials to precision engineering applications.
Modeling an Evaporative Cooling System to Improve Gas Turbines Performance
Authors: de Oliveira Silva Carlos Rafaello , Bringhenti Cleverson , Tomita Jesuíno Takachi , Lindquist Whitacker Luiz Henrique
Published: January 2023

Evaporative cooling systems are commonly used in thermoelectric plants to cool the air at gas turbines inlet, improving the performance of these engines. Normally, the evaporative cooling is modeled as adiabatic saturation and, in this case, the water-air equilibrium temperature depends only on the atmospheric air properties. However, other factors such as the water temperature that supplies the equipment and the ratio between the mass flow rates of water and air, also affect the equilibrium conditions of these systems. This work presents three methodologies to calculate the air temperature in equilibrium state, considering all the factors mentioned. The methodologies were implemented in a computer program written in fortran. In all cases tested, the results obtained by the three models showed high convergence. As an example, for 70 different sets of inputs, the absolute and relative differences of the results were below 0.3236 °C and 1.2480%, respectively. A statistical study, also on this sample of results, revealed that, for a confidence level of 99%, the hypothesis of the equivalence between the methods cannot be rejected.
Mesoscale convective clustering enhances tropical precipitation
Authors: Angulo-Umana Pedro , Kim Daehyun
Published: January 2023

In the tropics, extreme precipitation events are often caused by mesoscale systems of organized, spatially clustered deep cumulonimbi, posing a substantial risk to life and property. While the clustering of convective clouds has been thought to strengthen precipitation rate, no quantitative estimates of this hypothesized enhancement exist. In this study, after isolating the effects of mesoscale convective clustering on precipitation, we find that strongly clustered oceanic convection precipitates more intensely than weakly clustered convection. We further show that this enhancement is primarily attributable to an increase in convective precipitation rate when the environment is less than 70% saturated, with increases in the size of the rainy stratiform region being of equal or greater importance when the environment is closer to saturation. Our results suggest that a correct representation of mesoscale organized convective systems in numerical weather and climate models is needed for accurate predictions of extreme precipitation events.
Cytokinesis machinery promotes cell dissociation from collectively migrating strands in confinement
Authors: Law Robert A. , Kiepas Alexander , Desta Habben E. , Perez Ipiña Emiliano , Parlani Maria , Lee Se Jong , Yankaskas Christopher L. , Zhao Runchen , Mistriotis Panagiotis , Wang Nianchao , Gu Zhizhan , Kalab Petr , Friedl Peter , Camley Brian A. , Konstantopoulos Konstantinos
Published: January 2023

Cells tune adherens junction dynamics to regulate epithelial integrity in diverse (patho)physiological processes, including cancer metastasis. We hypothesized that the spatially confining architecture of peritumor stroma promotes metastatic cell dissemination by remodeling cell-cell adhesive interactions. By combining microfluidics with live-cell imaging, FLIM/FRET biosensors, and optogenetic tools, we show that confinement induces leader cell dissociation from cohesive ensembles. Cell dissociation is triggered by myosin IIA (MIIA) dismantling of E-cadherin cell-cell junctions, as recapitulated by a mathematical model. Elevated MIIA contractility is controlled by RhoA/ROCK activation, which requires distinct guanine nucleotide exchange factors (GEFs). Confinement activates RhoA via nucleocytoplasmic shuttling of the cytokinesis-regulatory proteins RacGAP1 and Ect2 and increased microtubule dynamics, which results in the release of active GEF-H1. Thus, confining microenvironments are sufficient to induce cell dissemination from primary tumors by remodeling E-cadherin cell junctions via the interplay of microtubules, nuclear trafficking, and RhoA/ROCK/MIIA pathway and not by down-regulating E-cadherin expression.
Direct age constraints on the magnetism of Jack Hills zircon
Authors: Taylor Richard J. M. , Reddy Steven M. , Saxey David W. , Rickard William D. A. , Tang Fengzai , Borlina Cauê S. , Fu Roger R. , Weiss Benjamin P. , Bagot Paul , Williams Helen M. , Harrison Richard J.
Published: January 2023

A potential record of Earth’s magnetic field going back 4.2 billion years (Ga) ago is carried by magnetite inclusions in zircon grains from the Jack Hills. This magnetite may be secondary in nature, however, meaning that the magnetic record is much younger than the zircon crystallization age. Here, we use atom probe tomography to show that Pb-bearing nanoclusters in magnetite-bearing Jack Hills zircons formed during two discrete events at 3.4 and <2 Ga. The older population of clusters contains no detectable Fe, whereas roughly half of the younger population of clusters is Fe bearing. This result shows that the Fe required to form secondary magnetite entered the zircon sometime after 3.4 Ga and that remobilization of Pb and Fe during an annealing event occurred more than 1 Ga after deposition of the Jack Hills sediment at 3 Ga. The ability to date Fe mobility linked to secondary magnetite formation provides new possibilities to improve our knowledge of the Archean geodynamo.
Solid Earth–atmosphere interaction forces during the 15 January 2022 Tonga eruption
Authors: Garza-Girón Ricardo , Lay Thorne , Pollitz Frederick , Kanamori Hiroo , Rivera Luis
Published: January 2023

Rapid venting of volcanic material during the 15 January 2022 Tonga eruption generated impulsive downward reaction forces on the Earth of ~2.0 × 10
13
N that radiated seismic waves observed throughout the planet, with ~25 s source bursts persisting for ~4.5 hours. The force time history is determined by analysis of teleseismic
P
waves and Rayleigh waves with periods approximately <50 s, providing insight into the overall volcanic eruption process. The atmospheric acoustic-gravity Lamb wave expanding from the eruption produced broadband ground motions when transiting land, along with driven and conventional tsunami waves. Atmospheric standing acoustic waves near the source produced oscillatory peak forces as large as 4 × 10
12
N, exciting resonant solid Earth Rayleigh wave motions at frequencies of 3.7 and 4.6 mHz.
Synthesis of hierarchical metal nanostructures with high electrocatalytic surface areas
Authors: Gloag Lucy , Poerwoprajitno Agus R. , Cheong Soshan , Ramadhan Zeno R. , Adschiri Tadafumi , Gooding J. Justin , Tilley Richard D.
Published: January 2023

3D interconnected structures can be made with molecular precision or with micrometer size. However, there is no strategy to synthesize 3D structures with dimensions on the scale of tens of nanometers, where many unique properties exist. Here, we bridge this gap by building up nanosized gold cores and nickel branches that are directly connected to create hierarchical nanostructures. The key to this approach is combining cubic crystal–structured cores with hexagonal crystal–structured branches in multiple steps. The dimensions and 3D morphology can be controlled by tuning at each synthetic step. These materials have high surface area, high conductivity, and surfaces that can be chemically modified, which are properties that make them ideal electrocatalyst supports. We illustrate the effectiveness of the 3D nanostructures as electrocatalyst supports by coating with nickel-iron oxyhydroxide to achieve high activity and stability for oxygen evolution reaction. This work introduces a synthetic concept to produce a new type of high-performing electrocatalyst support.
Soil Chemistry and Soil History Significantly Structure Oomycete Communities in
Brassicaceae
Crop Rotations
Authors: Blakney Andrew J. C. , Bainard Luke D. , St-Arnaud Marc , Hijri Mohamed
Published: January 2023

Oomycetes cause global plant diseases that result in substantial losses, yet they are highly understudied compared to other microbes, like fungi and bacteria. We wanted to investigate how past soil events, like changing crops in rotation, would impact subsequent oomycete communities.
Plasmid-Encoded Traits Vary across Environments
Authors: Finks Sarai S. , Martiny Jennifer B. H.
Published: January 2023

Plasmids are well known for their role in the transmission of antibiotic resistance-conferring genes. Beyond human and clinical settings, however, they disseminate many other types of genes, including those that contribute to microbially driven ecosystem processes.
A Germline-Targeting Chimpanzee SIV Envelope Glycoprotein Elicits a New Class of V2-Apex Directed Cross-Neutralizing Antibodies
Authors: Bibollet-Ruche Frederic , Russell Ronnie M. , Ding Wenge , Liu Weimin , Li Yingying , Wagh Kshitij , Wrapp Daniel , Habib Rumi , Skelly Ashwin N. , Roark Ryan S. , Sherrill-Mix Scott , Wang Shuyi , Rando Juliette , Lindemuth Emily , Cruickshank Kendra , Park Younghoon , Baum Rachel , Carey John W. , Connell Andrew Jesse , Li Hui , Giorgi Elena E. , Song Ge S. , Ding Shilei , Finzi Andrés , Newman Amanda , Hernandez Giovanna E. , Machiele Emily , Cain Derek W. , Mansouri Katayoun , Lewis Mark G. , Montefiori David C. , Wiehe Kevin J. , Alam S. Munir , Teng I-Ting , Kwong Peter D. , Andrabi Raiees , Verkoczy Laurent , Burton Dennis R. , Korber Bette T. , Saunders Kevin O. , Haynes Barton F. , Edwards Robert J. , Shaw George M. , Hahn Beatrice H.
Published: January 2023

An effective HIV-1 vaccination strategy will need to stimulate rare precursor B cells of multiple bNAb lineages and affinity mature them along desired pathways. Here, we searched for V2-apex germ line-targeting Envs among a large set of diverse primate lentiviruses and identified minimally modified versions of one chimpanzee SIV Env that bound several human V2-apex bNAb precursors and stimulated one of these in a V2-apex bNAb precursor-expressing knock-in mouse.
Discrepant Activation Pattern of Inflammation and Pyroptosis Induced in Dermal Fibroblasts in Response to Dengue Virus Serotypes 1 and 2 and Nonstructural Protein 1
Authors: Wei Kai-Che , Wei Wan-Ju , Liao Ching-Len , Chang Tsung-Hsien
Published: January 2023

Skin fibroblasts are the primary cells of DENV infection through mosquito bites. Establishing a successful infection in dermal fibroblasts might be critical for dengue disease.
A possible sea-level fall trigger for the youngest rejuvenated volcanism in Hawaiʻi
Authors: Jicha Brian R. , Garcia Michael O. , Lormand Charline
Published: January 2023

Many intraplate oceanic islands undergo “rejuvenated” volcanism following the main edifice-building stage. Honolulu features Hawaiʻi’s most recent rejuvenated volcanism. K-Ar dating of Honolulu volcanism suggests that it started at ca. 750 ka and ended at <100 ka. Here, we present new 40Ar/39Ar ages and olivine diffusion modeling from Koko Rift lavas to resolve when the most recent Honolulu eruptions occurred and to evaluate possible mechanisms of rejuvenated volcanism and volcanic hazards. Diffusion modeling of olivine zoning profiles in Koko Rift basalts suggests that magmas were stored in the crust for many months prior to eruption. Six new 40Ar/39Ar ages cluster at 67 ± 2 ka (2σ), which demonstrates that Koko Rift is Hawaiʻi’s youngest known area of rejuvenated volcanism. The timing of Koko Rift eruptions coincides with the pronounced drop in global sea level (∼100 m) during Marine Isotope Stage 4. This major sea-level fall may have triggered the eruptions of Koko Rift magmas that were stored in the crust for months to years at < 15 km depth. The proposed mechanism is similar to that at other volcanic islands, which suggests that changes in global sea level may have significant control on the magnitude and frequency of eruptions at ocean island volcanoes.
Empirical relationships for estimating the crest settlement of earth-core rockfill dams subjected to earthquakes
Authors: Ghaemi Arman , Konrad Jean-Marie
Published: January 2023

In this study, new empirical predictive relationships for earthquake-induced crest settlement of earth-core rockfill dams (ECRDs) were developed. A case history database of 19 dams that had been subjected to earthquakes was utilized. The presented relationships correlate the intensity measure (IM) of the earthquake records with the observed settlements, and thus, employing IMs that appropriately describe the severity of ground motion is of vital importance. It is well known that the dynamic properties of an ECRD can change significantly depending on the severity of an earthquake, and that this phenomenon can substantially impact the dynamic responses of dams. Accordingly, two IMs were suggested, taking into account the essential characteristics of ground motions affecting the nonlinear behaviour of ECRDs. The results indicate that the proposed relationships effectively address the limitations of the existing ones, and that they are practical tools that efficiently predict the seismic settlements of ECRDs.
Investigation of boulder impact force and energy transfer for steel baffle with footing
Authors: Ng C.W.W. , Zhang D.C. , Choi Clarence E. , Chen Rui , Koo R.C.H. , Kwan J.S.H. , Ni Jun Jun , Ho K.K.S.
Published: January 2023

Steel baffle installed on footing is commonly used to resist and dissipate the impact energy from boulders carried by debris flow. However, the deformation of a baffle and the resulting energy transfer to the footing during the impact process compound the challenges of predicting the impact force and size of the footing required. In this study, full-scale experiments were conducted to simulate a boulder impacting a steel baffle installed on a square footing. The experimental data were back-analyzed using a three-dimensional (3D) finite element model, which was then used to conduct a parametric study to examine the effects of a range of impact energies and footing sizes. New design charts are developed to assess the required size of a square footing, embedded up to 2 m depth, for a steel baffle subjected to boulder impact with energy in the range of 10–100 kJ.
Impact of different magnetic materials added to silver–magnetite nanoparticles on the structural, magnetic and antimicrobial properties
Authors: El-Bassuony Asmaa. A. H. , Gamal W. M. , Abdelsalam H. K.
Published: January 2023

Different magnetic materials of spinel copper and cobalt nanoferrites added to silver–magnetite nanoparticles were fabricated by a facile, low cost, and rapid auto-combustion method to form a nanocomposite. X-ray diffraction patterns and atomic force microscopy were studied for the investigated samples and confirmed their nanosize range. Adding cobalt nanoferrite to silver–magnetite (CoAF) yielded a more pronounced effect in the magnetic measurements than adding copper nanoferrite (CuAF). This result was attributed to the much higher coercivity Hc and saturation magnetization Ms (5.7-fold and 2.8-fold, respectively) of CoAF than CuAF; accordingly, the CoAF nanocomposite can be applied to a permanent magnet. Next, the operating frequencies of the nanocomposites were calculated from the magnetic measurements. The CoAF and CuAF nanocomposites were applicable in the microwave super-high-frequency C-band and the microwave super-high-frequency S-band, respectively. Both nanocomposites were ineffective against the tested fungi but showed strong antimicrobial activities against the tested Gram-positive and Gram-negative bacteria. Thus, CoAF and CuAF nanocomposites are potential antibacterial nanomaterials for biomedical applications.
Conserved quantities of vectorial magnitudes within the material media
Authors: Weng Zi-Hua
Published: January 2023

By means of the rotational transformations of octonion coordinate systems, the paper aims to explore the physical properties of conserved quantities relevant to the vectorial magnitudes within the material media, revealing the simultaneity of some conserved quantities in the electromagnetic and gravitational fields. Maxwell first utilized the algebra of quaternions to describe the electromagnetic theory. The subsequent scholars studied the physical properties of electromagnetic and gravitational fields simultaneously, including the octonion linear momentum, angular momentum, torque and force within the material media. According to the algebra of octonions, the scalar parts of octonion physical quantities remain unchanged, while the vectorial parts may alter, in the rotational transformations of octonion coordinate systems. From the octonion characteristics, it is able to deduce a few conserved quantities related to the vectorial magnitudes in the octonion space [Formula: see text], including the magnitudes of linear momentum, angular momentum, torque and force. Similarly, it is capable of inferring several conserved quantities relevant to the vectorial magnitudes in the transformed octonion space [Formula: see text], including the magnitudes of electric current, magnetic moment and electric moment. Through the analysis and comparison, it is concluded that some conserved quantities, relevant to the vectorial magnitudes, are unable to be established simultaneously, from the point of view of the octonion spaces. This is helpful to deepen the further understanding of some conserved quantities related to the vectorial magnitudes.
Extending the symmetry of the massless Klein–Gordon equation under the general disformal transformation
Authors: Alinea Allan L. , Chua Mark Ruel D.
Published: January 2023

The Klein–Gordon equation, one of the most fundamental equations in field theory, is known to be not invariant under conformal transformation. However, its massless limit exhibits symmetry under Bekenstein’s disformal transformation, subject to some conditions on the disformal part of the metric variation. In this study, we explore the symmetry of the Klein–Gordon equation under the general disformal transformation encompassing that of Bekenstein and a hierarchy of “sub-generalizations” explored in the literature (within the context of inflationary cosmology and scalar–tensor theories). We find that the symmetry in the massless limit can be extended under this generalization provided that the disformal factors take a special form in relation to the conformal factor. Upon settling the effective extension of symmetry, we investigate the invertibility of the general disformal transformation to avoid propagating nonphysical degrees of freedom upon changing the metric. We derive the inverse transformation and the accompanying restrictions that make this inverse possible.
Study of the Critical Behavior and the Multi-Layer Transition in a Spin-1 Ashkin–Teller Model under the Effect of the RKKY Interaction: Finite-Size-Scaling and Monte Carlo Studies
Authors: Benmansour A. , Brahmi B. N. , Bekhechi S. , Rachadi A. , Ez-Zahraouy H.
Published: January 2023

By using a Monte Carlo simulation, we have studied the effects on the multilayer transition and magnetic properties of the crystal field [Formula: see text], the four-spin coupling [Formula: see text] and RKKY interaction in the spin-1 Ashkin–Teller (AT) model of a system composed of two magnetic multi-layer materials, of various thicknesses, separated by a nonmagnetic spacer of thickness [Formula: see text]. By varying the strength of [Formula: see text], we have obtained a new partially ordered phase [Formula: see text], for different values of [Formula: see text]. We have established a rich phase diagram with first and second-order phase transitions with tricritical points. It is shown that the transition temperature of both magnetic blocks depends strongly on the thickness of the magnetic layers [Formula: see text], as well as [Formula: see text] and [Formula: see text]. There exists a critical thickness of the magnetic layers [Formula: see text] above which the multilayer blocks undergo a transition separately at different temperatures, for a high value of [Formula: see text] and [Formula: see text]. Besides, the critical exponents are computed.
Robust Vision-Based Sliding Mode Control for Uncooperative Ground Target Searching and Tracking by Quadrotor
Authors: Bouzerzour Hamza , Guiatni Mohamed , Allam Ahmed , Bouzid Yasser , Hamrelain Mustapha
Published: January 2023

In this paper, the problem of searching and tracking uncooperative and unidentified mobile ground target using a quadcopter unmanned aerial vehicle (QUAV) is investigated. The proposed strategy is an Image-Based Visual Servoing (IBVS) approach, combined with the virtual camera concept and robust control. This strategy makes use of the rough prior information of the target, in contrast with existing strategies, which will alleviate the problem of altitude estimation noise and enhance the overall accuracy. Hence, a new vision-based sliding mode controller (SMC) is designed to control the quadcopter taking into account the flight phase’s heterogeneity, the external disturbances and parameters uncertainties as well as the target maneuverability. In order to get a better insight about the SMC tuning and adjustment, three different reaching laws are evaluated and compared. The proposed controller allows an automatic execution of the flight strategy whilst the searching phase relies on the Camera Coverage Area (CCA) technique. The vision-based technique allows an automatic QUAV altitude tuning for optimal target observation and tracking. Another contribution of this work is the fact that the designed controller validity and stability overspan the entire scenario to reach the universal and to smoothen out surges generated by control switching. Numerical simulations are conducted to compare the proposed SMC controllers and validate the effectiveness of the whole strategy.
So, How
Can
We Measure UX?
Authors: Speicher Maximilian
Published: January 2023

The
Interactions
website (interactions.acm.org) hosts a stable of bloggers who share insights and observations on HCI, often challenging current practices. Each issue we'll publish selected posts from some of the leading and emerging voices in the field.
babble: Learning Better Abstractions with E-Graphs and Anti-unification
Authors: Cao David , Kunkel Rose , Nandi Chandrakana , Willsey Max , Tatlock Zachary , Polikarpova Nadia
Published: January 2023

Library learning
compresses a given corpus of programs by extracting common structure from the corpus into reusable library functions. Prior work on library learning suffers from two limitations that prevent it from scaling to larger, more complex inputs. First, it explores too many candidate library functions that are not useful for compression. Second, it is not robust to syntactic variation in the input.

We propose
library learning modulo theory
(LLMT), a new library learning algorithm that additionally takes as input an equational theory for a given problem domain. LLMT uses e-graphs and equality saturation to compactly represent the space of programs equivalent modulo the theory, and uses a novel
e-graph anti-unification
technique to find common patterns in the corpus more directly and efficiently.

We implemented LLMT in a tool named babble. Our evaluation shows that babble achieves better compression orders of magnitude faster than the state of the art. We also provide a qualitative evaluation showing that babble learns reusable functions on inputs previously out of reach for library learning.
Dargent: A Silver Bullet for Verified Data Layout Refinement
Authors: Chen Zilin , Lafont Ambroise , O'Connor Liam , Keller Gabriele , McLaughlin Craig , Jackson Vincent , Rizkallah Christine
Published: January 2023

Systems programmers need fine-grained control over the memory layout of data structures, both to produce performant code and to comply with well-defined interfaces imposed by existing code, standardised protocols or hardware. Code that manipulates these low-level representations in memory is hard to get right. Traditionally, this problem is addressed by the implementation of tedious marshalling code to convert between compiler-selected data representations and the desired compact data formats. Such marshalling code is error-prone and can lead to a significant runtime overhead due to excessive copying. While there are many languages and systems that address the correctness issue, by automating the generation and, in some cases, the verification of the marshalling code, the performance overhead introduced by the marshalling code remains. In particular for systems code, this overhead can be prohibitive. In this work, we address both the correctness and the performance problems.

We present a data layout description language and data refinement framework, called Dargent, which allows programmers to declaratively specify how algebraic data types are laid out in memory. Our solution is applied to the Cogent language, but the general ideas behind our solution are applicable to other settings. The Dargent framework generates C code that manipulates data directly with the desired memory layout, while retaining the formal proof that this generated C code is correct with respect to the functional semantics. This added expressivity removes the need for implementing and verifying marshalling code, which eliminates copying, smoothens interoperability with surrounding systems, and increases the trustworthiness of the overall system.
Recursive Subtyping for All
Authors: Zhou Litao , Zhou Yaoda , Oliveira Bruno C. d. S.
Published: January 2023

Recursive types and bounded quantification are prominent features in many modern programming languages, such as Java, C#, Scala or TypeScript. Unfortunately, the interaction between recursive types, bounded quantification and subtyping has shown to be problematic in the past. Consequently, defining a simple foundational calculus that combines those features and has desirable properties, such as
decidability
,
transitivity
of subtyping,
conservativity
and a sound and complete algorithmic formulation has been a long time challenge.

This paper presents an extension of kernel ‍
F
≤
, called
F
≤
µ
, with iso-recursive types.
F
≤
is a well-known polymorphic calculus with bounded quantification. In
F
≤
µ
we add iso-recursive types, and correspondingly extend the subtyping relation with iso-recursive subtyping using the recently proposed nominal unfolding rules. We also add two smaller extensions to
F
≤
. The first one is a generalization of the kernel ‍
F
≤
rule for bounded quantification that accepts
equivalent
rather than
equal
bounds. The second extension is the use of so-called
structural
folding/unfolding rules, inspired by the structural unfolding rule proposed by Abadi, Cardelli, and Viswanathan [1996]. The structural rules add expressive power to the more conventional folding/unfolding rules in the literature, and they enable additional applications. We present several results, including: type soundness; transitivity and decidability of subtyping; the conservativity of
F
≤
µ
over
F
≤
; and a sound and complete algorithmic formulation of
F
≤
µ
. Moreover, we study an extension of
F
≤
µ
, called
F
≤≥
µ
, which includes
lower bounded quantification
in addition to the conventional (upper) bounded quantification of
F
≤
. All the results in this paper have been formalized in the Coq theorem prover.
A Partial Order View of Message-Passing Communication Models
Authors: Di Giusto Cinzia , Ferré Davide , Laversa Laetitia , Lozes Etienne
Published: January 2023

There is a wide variety of message-passing communication models, ranging from synchronous "rendez-vous" communications to fully asynchronous/out-of-order communications. For large-scale distributed systems, the communication model is determined by the transport layer of the network, and a few classes of orders of message delivery (FIFO, causally ordered) have been identified in the early days of distributed computing. For local-scale message-passing applications, e.g., running on a single machine, the communication model may be determined by the actual implementation of message buffers and by how FIFO queues are used. While large-scale communication models, such as causal ordering, are defined by logical axioms, local-scale models are often defined by an operational semantics. In this work, we connect these two approaches, and we present a unified hierarchy of communication models encompassing both large-scale and local-scale models, based on their concurrent behaviors. We also show that all the communication models we consider can be axiomatized in the monadic second order logic, and may therefore benefit from several bounded verification techniques based on bounded special treewidth.
Deconstructing the Calculus of Relations with Tape Diagrams
Authors: Bonchi Filippo , Di Giorgio Alessandro , Santamaria Alessio
Published: January 2023

Rig categories with finite biproducts are categories with two monoidal products, where one is a biproduct and the other distributes over it. In this work we present tape diagrams, a sound and complete diagrammatic language for these categories, that can be intuitively thought as string diagrams of string diagrams. We test the effectiveness of our approach against the positive fragment of Tarski's calculus of relations.
Modular Primal-Dual Fixpoint Logic Solving for Temporal Verification
Authors: Unno Hiroshi , Terauchi Tachio , Gu Yu , Koskinen Eric
Published: January 2023

We present a novel approach to deciding the validity of formulas in first-order fixpoint logic with background theories and arbitrarily nested inductive and co-inductive predicates defining least and greatest fixpoints. Our approach is constraint-based, and reduces the validity checking problem of the given first-order-fixpoint logic formula (formally, an instance in a language called µCLP) to a constraint satisfaction problem for a recently introduced predicate constraint language.

Coupled with an existing sound-and-relatively-complete solver for the constraint language, this novel reduction alone already gives a sound and relatively complete method for deciding µCLP validity, but we further improve it to a novelmodular primal-dualmethod. The key observations are (1) µCLP is closed under complement such that each (co-)inductive predicate in the originalprimalinstance has a corresponding (co-)inductive predicate representing its complement in thedualinstance obtained by taking the standard De Morgan’s dual of the primal instance, and (2)partial solutionsfor (co-)inductive predicates synthesized during the constraint solving process of the primal side can be used as sound upper-bounds of the corresponding (co-)inductive predicates in the dual side, and vice versa. By solving the primal and dual problems in parallel and exchanging each others’ partial solutions as sound bounds, the two processes mutually reduce each others’ solution spaces, thus enabling rapid convergence. The approach is alsomodularin that the bounds are synthesized and exchanged at granularity of individual (co-)inductive predicates.

We demonstrate the utility of our novel fixpoint logic solving by encoding a wide variety of temporal verification problems in µCLP, including termination/non-termination, LTL, CTL, and even the full modal µ-calculus model checking of infinite state programs. The encodings exploit the modularity in both the program and the property by expressing each loops and (recursive) functions in the program and sub-formulas of the property as individual (possibly nested) (co-)inductive predicates. Together with our novel modular primal-dual µCLP solving, we obtain a novel approach to efficiently solving a wide range of temporal verification problems.
Reconciling Shannon and Scott with a Lattice of Computable Information
Authors: Hunt Sebastian , Sands David , Stucki Sandro
Published: January 2023

This paper proposes a reconciliation of two different theories of information. The first, originally proposed in a lesser-known work by Claude Shannon (some five years after the publication of his celebrated quantitative theory of communication), describes how the information content of channels can be described
qualitatively
, but still abstractly, in terms of
information elements
, where information elements can be viewed as equivalence relations over the data source domain. Shannon showed that these elements have a partial ordering, expressing when one information element is more informative than another, and that these partially ordered information elements form a complete lattice. In the context of security and information flow this structure has been independently rediscovered several times, and used as a foundation for understanding and reasoning about information flow.

The second theory of information is Dana Scott’s domain theory, a mathematical framework for giving meaning to programs as continuous functions over a particular topology. Scott’s partial ordering also represents when one element is more informative than another, but in the sense of computational progress – i.e. when one element is a more defined or evolved version of another.

To give a satisfactory account of information flow in computer programs it is necessary to consider both theories together, in order to understand not only what information is conveyed by a program (viewed as a channel, à la Shannon) but also how the precision with which that information can be observed is determined by the definedness of its encoding (à la Scott). To this end we show how these theories can be fruitfully combined, by defining
the Lattice of Computable Information
(LoCI), a lattice of preorders rather than equivalence relations. LoCI retains the rich lattice structure of Shannon’s theory, filters out elements that do not make computational sense, and refines the remaining information elements to reflect how Scott’s ordering captures possible varieties in the way that information is presented.

We show how the new theory facilitates the first general definition of termination-insensitive information flow properties, a weakened form of information flow property commonly targeted by static program analyses.
Abortion Pills and Telehealth Technology
Authors: Calkin Sydney
Published: January 2023

This forum is dedicated to exploring the notion of meaningfulness in design processes, taking the perspectives of community groups, nongovernmental organizations, and those who are marginalized in society as starting points. Authors will reflect conceptually and methodologically on practical engagements.
--- Rosanna Bellini and Angelika Strohmayer, Editors
A Siamese Inverted Residuals Network Image Steganalysis Scheme based on Deep Learning
Authors: Li Hao , Wang Jinwei , Xiong Neal , Zhang Yi , Vasilakos Athanasios V. , Luo Xiangyang
Published: January 2023

With the rapid proliferation of urbanization, massive data in social networks are collected and aggregated in real time, making it possible for criminals to use images as a cover to spread secret information on the Internet. How to determine whether these images contain secret information is a huge challenge for multimedia computing security. The steganalysis method based on deep learning can effectively judge whether the pictures transmitted on the Internet in urban scenes contain secret information, which is of great significance to safeguarding national and social security. Image steganalysis based on deep learning has powerful learning ability and classification ability, and its detection accuracy of steganography images has surpassed that of traditional steganalysis based on manual feature extraction. In recent years, it has become a hot topic of the information hiding technology. However, the detection accuracy of existing deep learning based steganalysis methods still needs to be improved, especially when detecting arbitrary-size and multi-source images, their detection efficientness is easily affected by cover mismatch. In this manuscript, we propose a steganalysis method based on Inverse Residuals structured Siamese network (abbreviated as
SiaIRNet
method,

Sia
mese-
I
nverted-
R
esiduals-
Net
work

Based method). The SiaIRNet method uses a siamese
convolutional neural network (CNN)
to obtain the residual features of subgraphs, including three stages of preprocessing, feature extraction, and classification. Firstly, a preprocessing layer with high-pass filters combined with depth-wise separable convolution is designed to more accurately capture the correlation of residuals between feature channels, which can help capture rich and effective residual features. Then, a feature extraction layer based on the Inverse Residuals structure is proposed, which improves the ability of the model to obtain residual features by expanding channels and reusing features. Finally, a fully connected layer is used to classify the cover image and the stego image features. Utilizing three general datasets, BossBase-1.01, BOWS2, and ALASKA#2, as cover images, a large number of experiments are conducted comparing with the state-of-the-art steganalysis methods. The experimental results show that compared with the classical SID method and the latest SiaStegNet method, the detection accuracy of the proposed method for 15 arbitrary-size images is improved by 15.96% and 5.86% on average, respectively, which verifies the higher detection accuracy and better adaptability of the proposed method to multi-source and arbitrary-size images in urban scenes.
Supervisory Control for Dynamic Feature Configuration in Product Lines
Authors: Thuijsman Sander , Reniers Michel
Published: January 2023

In this paper a framework for engineering supervisory controllers for product lines with dynamic feature configuration is proposed. The variability in valid configurations is described by a feature model. Behavior of system components is achieved using (extended) finite automata and both behavioral and dynamic configuration constraints are expressed by means of requirements as is common in supervisory control theory. Supervisory controller synthesis is applied to compute a behavioral model in which the requirements are adhered to. For the challenges that arise in this setting, multiple solutions are discussed. The solutions are exemplified in the CIF toolset using a model of a coffee machine. A use case of the much larger Body Comfort System product line is performed to showcase feasibility for industrial-sized systems.
Wireless Powered Mobile Edge Computing Networks: A Survey
Authors: Wang Xiaojie , Li Jiameng , Ning Zhaolong , Song Qingyang , Guo Lei , Guo Song , Obaidat Mohammad S.
Published: January 2023

Wireless Powered Mobile Edge Computing (WPMEC) is an integration of Mobile Edge Computing (MEC) and Wireless Power Transfer (WPT) technologies, to both improve computing capabilities of mobile devices and energy compensation for their limited battery capabilities. Generally, energy transmitters, mobile devices, and edge servers form a WPMEC system that realizes a closed loop of sending and collecting energy as well as offloading and receiving task data. Due to constraints of time-varying network environments, time-coupled battery levels, and the half-duplex character of mobile devices, the joint design of computation offloading and resource allocation solutions in WPMEC systems has become extremely challenging, and a great number of studies have been devoted to it in recent years. In this article, we first introduce the basic model of the WPMEC system. Then, we present key issues and techniques related to WPMEC. In addition, we summarize solutions for computation offloading and resource allocation to solve critical issues in WPMEC networks. Finally, we discuss some research challenges and open issues.