Properties Of Pairs Research Articles

Study on Friction and Wear Performance of Sliding Metal Seal Materials Under Reciprocating Motion.

During petroleum drilling, the reciprocating motion in the seal device leads to piston and sleeve wear, which may cause leakage of the sealing medium. Selecting appropriate materials for the piston and sleeve, along with surface modifications, can effectively prolong the seal service life of the seal. The friction and wear properties of piston and sleeve pairs of different materials in a metal sealing device were simulated by the laboratory "pin-on-block" reciprocating friction test. Pins made of 45# steel, 35CrMo, and 20Cr13 were used to simulate piston bulges, while 35CrMo samples were used to simulate sleeves. Additionally, the influence of DLC (diamond-like carbon) coating and QPQ (Quench-Polish-Quench) nitriding on the wear resistance of the materials was studied. Based on this, the friction and wear properties, along with the wear mechanism of different material pairs, were analyzed. The results show that the friction coefficient curves of the three piston base materials and the 35CrMo sleeve are similar, and the friction coefficient of 45# steel is lower than that of 35CrMo and 20Cr13 at the initial stage. The DLC surface coating exhibited the best anti-wear performance, with the lowest friction coefficient, minimal wear, and the most stable friction coefficient. Surface QPQ nitriding treatment can also improve the wear resistance of the base material. However, due to the oxide formed during nitriding being prone to flaking, the friction coefficient fluctuates significantly at the initial stage of testing, and its anti-wear performance was inferior to that of the DLC coating. This study on material pairing and surface modification provides theoretical support for material selection and surface modification design of pistons and sleeves in oil drilling sealing devices.

Structural and Semantic Properties of Idiomatic Pairs in English and Vietnamese: A Contrastive Analysis

There are idiomatic pairs in both English and Vietnamese. While idiomatic pairs in Vietnamese have been extensively researched from different views, it seems that there have been few thorough studies of idiomatic pairs across English and Vietnamese. This paper looks into the structural and semantic properties of idiomatic pairs in English and Vietnamese using the framework of idiom analysability (Langlotz, 2006). This is a contrastive analysis that presents the similarities and differences between English and Vietnamese idiomatic pairs in terms of structural and semantic properties, including grammatical and componential patterns, semantic compositions, and transparent-opaque components. A manual search of Giang's (2018) idiom collection yielded a corpus of 231 English and 2374 Vietnamese idiomatic pairs, which served as the data for the study. The findings of this study indicate that the biggest difference between English and Vietnamese idiomatic pairs lies in their distribution in each language. There are much more idiomatic idioms in Vietnamese than in English. Grammatically, idiomatic pairs in both languages are formed by two syntactically equivalent component parts. In Vietnamese, the components that create idiomatic pairs are even, and in English, they are odd. Semantically, the majority of English and Vietnamese idiomatic pairs are able to be analysable, and their meanings are at least motivated in some way.

Integrated photon pairs source based on counter-propagating spontaneous four wave mixing in a silicon nitride microring resonator

We report the design of an innovative visible-telecom photon pair source based on counter-propagating spontaneous four wave mixing (CP-SFWM) in a silicon nitride microring resonator. Unlike previous designs, the proposed integrated source achieves automatic phase matching, eliminating the need for dispersion engineering. By employing two lasers at wavelengths of 800 nm and 1550 nm as pumps on opposite ends of the bus waveguides, the resonator generates signal and idler photons at the same wavelengths as the pumps, but propagating in opposite directions. The photon pairs are produced in high-quality factor resonant modes, exhibiting a purity of 1, a brightness of 118.70pairs⋅s−1⋅mW−2, and bandwidths of 157.9 MHz and 79.7 MHz for signal and idler photons, respectively. Our proposal outperforms previous CP-SFWM designs in terms of spectral properties of the photon pairs, emission rate, and scalability, making it an interesting alternative for the implementation of integrated photon pair sources for photonic networks.

Quantum tops at circular lepton colliders

We study the quantum properties of top quark pairs in lepton colliders with unpolarised beams, including spin correlations, entanglement, and violation of Bell inequalities. We present analytical results in the SM and in the SMEFT and discuss several practical aspects, like the choice of quantisation axes and tt¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ t\\overline{t} $$\\end{document} threshold effects. We also note a correspondence between parity symmetry and entanglement. We find that quantum observables exhibit a rich phenomenology in the SM, and can also provide additional leverage in detecting new physics residing at higher scales.

Satellite DNAs and the evolution of the multiple X1X2Y sex chromosomes in the wolf fish Hoplias malabaricus (Teleostei; Characiformes)

Multiple sex chromosomes usually arise from chromosomal rearrangements which involve ancestral sex chromosomes. There is a fundamental condition to be met for their long-term fixation: the meiosis must function, leading to the stability of the emerged system, mainly concerning the segregation of the sex multivalent. Here, we sought to analyze the degree of differentiation and meiotic pairing properties in the selected fish multiple sex chromosome system present in the wolf-fish Hoplias malabaricus (HMA). This species complex encompasses seven known karyotype forms (karyomorphs) where the karyomorph C (HMA-C) exhibits a nascent XY sex chromosomes from which the multiple X1X2Y system evolved in karyomorph HMA-D via a Y-autosome fusion. We combined genomic and cytogenetic approaches to analyze the satellite DNA (satDNA) content in the genome of HMA-D karyomorph and to investigate its potential contribution to X1X2Y sex chromosome differentiation. We revealed 56 satDNA monomers of which the majority was AT-rich and with repeat units longer than 100 bp. Seven out of 18 satDNA families chosen for chromosomal mapping by fluorescence in situ hybridization (FISH) formed detectable accumulation in at least one of the three sex chromosomes (X1, X2 and neo-Y). Nine satDNA monomers showed only two hybridization signals limited to HMA-D autosomes, and the two remaining ones provided no visible FISH signals. Out of seven satDNAs located on the HMA-D sex chromosomes, five mapped also to XY chromosomes of HMA-C. We showed that after the autosome-Y fusion event, the neo-Y chromosome has not substantially accumulated or eliminated satDNA sequences except for minor changes in the centromere-proximal region. Finally, based on the obtained FISHpatterns, we speculate on the possible contribution of satDNA to sex trivalent pairing and segregation.

Research on friction and meshing efficiency of ADC12-POM gear pair considering off-line meshing

Metal-plastic gear pairs, due to their combination of the advantages of both materials, have been widely promoted and applied in many industries. However, research on their transmission performance is not yet complete, especially regarding the tribological properties of metal-plastic gear pairs. The study focus on ADC12-POM gear pairs. Based on the principle of potential energy, the study considers significant elastic deformation during POM meshing, resulting in obvious off-line meshing. Consequently, the study establishes a stiffness model for ADC12-POM gear pairs with off-line meshing. Using this stiffness model and a load distribution model, to calculate the tooth surface load distribution coefficient for the gear pairs. Building upon previous research on friction coefficient models, the study develop a friction coefficient model that accounts for off-line meshing and compare it with the friction coefficient model that does not consider off-line meshing. To validate the accuracy of the friction coefficient model, the study design and create an efficiency test rig for ADC12-POM gear pairs, conducting theoretical and experimental studies on gear mesh efficiency. The study analyzes the distribution of mesh efficiency along the meshing line and its relationship with the friction coefficient. By comparing experimental measurements with theoretical calculations, the study verifies the proposed friction coefficient model, providing a theoretical basis for the study of metal-plastic gears.

Classification and Double Commutant Property for Dual Pairs in an Orthosymplectic Lie Supergroup

Classification and Double Commutant Property for Dual Pairs in an Orthosymplectic Lie Supergroup

The surjection property and computable type

We provide a detailed study of two properties of spaces and pairs of spaces, the surjection property and the ϵ-surjection property, that were recently introduced to characterize the notion of computable type arising from computability theory. For a class of spaces including the finite simplicial complexes, we develop techniques to prove or disprove these properties using homotopy and homology theories, and give applications of these results. In particular, we answer an open question on the computable type property, showing that it is not preserved by taking products. We also observe that computable type is decidable for finite simplicial complexes.

Tailoring the spectro-temporal mode of photon pairs generated from interspatial-mode four-wave mixing.

We investigate the spectro-temporal mode property of the photon pairs generated via interspatial-mode spontaneous four-wave mixing (FWM) in a few-mode fiber (FMF) that supports two linearly polarized spatial modes in the 1550 nm telecom band. The two pulsed pumps for the process are in distinct spatial modes, while the created signal and idler photon pairs are also occupying different spatial modes. By exploiting the unique inter-mode phase matching condition in the FMF, we can tailor the spectro-temporal mode structure of the photon pairs by changing the pulse duration (spectral bandwidth) of the two pumps. Especially, photon pairs with a nearly round-shaped factorable joint spectrum are experimentally realized. The techniques are valuable for generating and manipulating quantum states in multi-mode waveguides and exploiting the spatial degree of freedom in quantum information processing.

Tunable entangled photon-pair generation in a liquid crystal

Liquid crystals, with their ability to self-assemble, strong response to an electric field and integrability into complex systems, are key materials in light-beam manipulation1. The recently discovered ferroelectric nematic liquid crystals2,3 also have considerable second-order optical nonlinearity, making them a potential material for nonlinear optics4,5. Their use as sources of quantum light could considerably extend the boundaries of photonic quantum technologies6. However, spontaneous parametric down-conversion, the basic source of entangled photons7, heralded single photons8 and squeezed light9, has so far not been observed in liquid crystals—or in any liquids or organic materials. Here we implement spontaneous parametric down-conversion in a ferroelectric nematic liquid crystal and demonstrate electric-field tunable broadband generation of entangled photons, with an efficiency comparable to that of the best nonlinear crystals. The emission rate and polarization state of photon pairs is markedly varied by applying a few volts or twisting the molecular orientation along the sample. A liquid-crystal source enables a special type of quasi-phase matching10, which is based on the molecular twist structure and is therefore reconfigurable for the desired spectral and polarization properties of photon pairs. Such sources promise to outperform standard nonlinear optical materials in terms of functionality, brightness and the tunability of the generated quantum state. The concepts developed here can be extended to complex topological structures, macroscopic devices and multi-pixel tunable quantum light sources.

Orthogonality and unitary conditions for solutions to some consistent linear matrix equations

The nonlinear matrix equation (A1 + B1X1D1)(A2 + B2X2D2) = A, presents a matrix identity, where A, Ai, Bi, and Di are known matrices of suitable sizes and Xi are unknown matrices for i = 1,2, over the field of complex numbers ℂ. Several known simple methods in linear algebra can handle the orthogonality problem. In this paper, we select some linear matrix equations as illustrative examples to discuss some properties of pairs of identically dimensional consistent linear matrix equations, then apply specific matrix analytic tools, among them is the matrix rank method, the rank of a matrix is one of the most basic quantities and useful methods and tools that are widely used in linear algebra specifically, in matrix theory and its applications. We consider certain forms of linear matrix equations such as T1X1 = N1 and the system A3X3 = C3, X3B3 = D3, to derive novel conditions dictating the orthogonality of all solutions to two consistent matrix equations, as well as the necessary and sufficient conditions for all solutions to be unitary, further we give an illustrative example.

Entangled photon-pair generation in nonlinear thin-films

Abstract We develop a fully vectorial and non-paraxial formalism to describe spontaneous parametric down-conversion in nonlinear thin films. The formalism is capable of treating slabs with a sub-wavelength thickness, describe the associated Fabry–Pérot effects, and even treat absorptive nonlinear materials. With this formalism, we perform an in-depth study of the dynamics of entangled photon-pair generation in nonlinear thin films, to provide a needed theoretical understanding for such systems that have recently attracted much experimental attention as sources of photon pairs. As an important example, we study the far-field radiation properties of photon pairs generated from a high-refractive-index nonlinear thin-film with zinc-blende structure that is deposited on a linear low-refractive-index substrate. In particular, we study the thickness-dependent effect of Fabry–Pérot interferences on the far-field radiation pattern of the photon pairs. We also pay special attention to study of entanglement generation, and find the conditions under which maximally polarization-entangled photon pairs can be generated and detected in such nonlinear thin-films.

Dryland soil recovery after disturbance across soil and climate gradients of the Colorado Plateau

Drylands impacted by energy development often require costly reclamation activities to reconstruct damaged soils and vegetation, yet little is known about the effectiveness of reclamation practices in promoting recovery of soil quality due to a lack of long-term and cross-site studies. Here, we examined paired on-pad and adjacent undisturbed off-pad soil properties over a 22-year chronosequence of 91 reclaimed oil or gas well pads across soil and climate gradients of the Colorado Plateau in the southwestern United States. Our goals were to estimate the time required for soil properties to reach undisturbed conditions, examine the multivariate nature of soil quality following reclamation, and identify environmental factors that affect reclamation outcomes. Soil samples, collected in 2020 and 2021, were analyzed for biogeochemical pools (total nitrogen, and total organic and inorganic carbon), chemical characteristics (salinity, sodicity, pH), and texture. Predicted time to recovery across all sites was 29 years for biogeochemical soil properties, 31 years for soil chemical properties, and 6 years for soil texture. Ordination of soil properties revealed differences between on- and off-pad soils, while site aridity explained variability in on-pad recovery. The predicted time to total soil recovery (distance between on- and off-pad in ordination space) was 96 years, which was longer than any individual soil property. No site reached total recovery, indicating that individual soil properties alone may not fully indicate recovery in soil quality as soil recovery does not equal the sum of its parts. Site aridity was the largest predictor of reclamation outcomes, but the effects differed depending on soil type. Taken together, results suggest the recovery of soil quality - which reflects soil fertility, carbon sequestration potential, and other ecosystem functions - was influenced primarily by site setting, with soil type and aridity major mediators of on-pad carbon, salinity, and total soil recovery following reclamation.

Friction Reduction Achieved by Ultraviolet Illumination on TiO2 Surface.

Controlling friction by light field is a low-cost, low-energy, non-polluting method. By applying ultraviolet light on the surface of photosensitive materials, the properties of the friction pairs or lubricant can be influenced, thus achieving the purpose of reducing friction. In this study, TiO2, an inorganic photosensitive material, was selected to investigate the modulating effect of light fields on friction lubrication when using polyalphaolefin (PAO) base oil as a lubricant, and the modulation law of light fields on the friction lubrication behavior was investigated under different loads (1-8 N), different speeds (20-380 mm/s), and different viscosities (10.1-108.6 mPa·s) of PAO base oil. The experimental results showed that light treatment could reduce the friction coefficient of PAO4 base oil lubrication from 0.034 to 0.016, with a reduction of 52.9% under conditions of 3 N-load and 56.5 mm/s-speed, and the best regulation effect could be achieved under the mixed lubrication condition. After TiO2 was treated with ultraviolet light, due to its photocatalytic property, PAO molecules were oxidized and adsorbed on the TiO2 surface to form an adsorption layer, which avoided the direct contact of rough peaks and thus reduced the friction coefficient. This study combines photosensitivity, photocatalysis, and friction, presenting a method to reduce the friction coefficient by applying a light field without changing the friction pairs or lubricants, which provides a new direction for friction modulation and gives new ideas for practical applications.

Ubiquitous light real-space pairing from long-range hopping and interactions

We systematically examine how long-range hopping and its synergy with extended interactions leads to light bound pairs. Pair properties are determined for a dilute extended Hubbard model with large on-site repulsion (U) and both near- and next-nearest neighbor hopping (t and t′) and attraction (V and V′), for cubic and tetragonal lattices. The presence of t′ and V′ promotes light pairs. For tetragonal lattices, t′<0 pairs can be lighter than non-interacting particles, and d-symmetric pairs form. Close packing transition temperatures, T⁎, are estimated for the Bose-Einstein condensation (BEC) of pairs to be kBT⁎∼0.1t‾, where t‾ is the geometric mean of the hoppings on the Cartesian axes. When pairs have d-symmetry, the condensate has d-wave character. Thus, the presence of both t′ and V′ leads ubiquitously to small strongly bound pairs with an inverse mass that is linear in hopping, which could lead to high temperature BECs.

Hyperon physics at BESIII

Spin polarization and entanglement are utilized by the BESIII experiment to learn more about the production and decay properties of hyperon-antihyperon pairs in a series of recent analyses of its unprecedented datasets at the J/\psiJ/ψ and \psi'ψ′ resonances. This has lead to the observation of significant transverse polarisation in decays of J/\psiJ/ψ or \psi'ψ′ into \Lambda \bar{\Lambda}ΛΛ‾, \Sigma \bar{\Sigma}ΣΣ‾, \Xi \bar{\Xi}ΞΞ‾, and \Omega \bar{\Omega}ΩΩ‾. Because of the non-zero polarization, the decay parameters for the most common hadronic weak decays of both hyperons and antihyperons could be determined independently for the first time. Comparing these to each other yields precise tests of direct, \Delta S = 1ΔS=1 CP-violation that complement measurements of kaon decays.

A physical layer security scheme for 6G wireless networks using post-quantum cryptography

The sixth generation (6G) of mobile networks is poised to revolutionize communication capabilities with its infinite-like reach. These networks will feature an ultra-dense topology, accommodating a wide range of devices, from macro devices like satellites to nano-devices integrated within the human body. However, the extensive data traffic handled by 6G networks, a significant portion of which is sensitive in nature, presents a security challenge. This paper presents the design and implementation of an encryption scheme that ensures the confidentiality of data transmission in the physical layer of 6G networks. The proposed physical layer security architecture relies on lattice cryptography, wherein each user is associated with a pair of bases (a public basis and a private basis) and a set of orthogonal sub-carriers. The encryption process involves projecting the vector of the transmitted data’s quadrature amplitude modulation (QAM) symbols onto the user’s public basis. A random error vector is then added before applying the inverse Fourier transform of the orthogonal frequency division multiplexing (OFDM) technique. The security of this encryption scheme hinges on the complexity of the closest vector problem in an integer lattice. To evaluate its efficacy, we analyze the security of our lattice-based physical layer encryption concerning the properties of the base pairs and error vectors. Our findings indicate that the proposed scheme offers satisfactory security protection against eavesdropping attacks by significantly enhancing the confidentiality of the transmitted signal. Furthermore, we assess the performance of our design through numerical experiments, demonstrating its resilience against various security attacks.

Acoustic correlates of word stress and focus marking in Udmurt

AbstractIn this paper, we investigate the prosodic realization of stress and focus in Udmurt (Uralic, Permic). According to the literature, Udmurt has fixed final stress, but also has several sets of morphosyntactic exceptions with initial stress. We report the results of two production studies. The first one targets nominals with final stress, and the second one investigates the stress properties of minimal pairs consisting of (i) indicative verbs (prs.3sg; final stress) and (ii) imperative verbs (imp.2sg/pl; initial stress). To control for the information-structural contexts, the test words are studied in contexts that elicit narrow focus either on the test word (‘F’ condition) or on another constituent (‘non-F’ condition). The results show that all four acoustic parameters surveyed in the paper – duration, intensity, fundamental frequency (f0), and first formant (F1) values – participate in stress marking in Udmurt. The results for focus marking vary by study and demonstrate that all cues except for intensity may be involved in focus marking. At the same time, we find wide interspeaker variation with respect to the acoustic cues marking stress and/or focus. Finally, we outline a preliminary Autosegmental-Metrical interpretation of our f0 results; a full account of Udmurt intonation awaits further research.

Intermolecular hydrogen bonding in DNA base pairs interacting with different numbers of bare and hydrated Li+: NBO, QTAIM, and computational spectroscopic studies

In this study, the effect of different numbers of Li+ interacting with various sites of DNA base pairs (adenine–thymine (AT) and cytosine-guanine (GC)) on the base pair structures, the strength of hydrogen bonding between the bases, and spectroscopic properties (IR and absorption spectra) of the base pairs was investigated. Two quantum computational analyses, the natural bonding orbitals (NBO) and the quantum theory of atoms in molecules (QTAIM), were used to follow the change in the strength of hydrogen bonds between the bases in each pair. The type of base pair’s site interacting with Li+ showed different effects on the change in the strength of the hydrogen bonds between the bases. The IR and absorption spectra of the lithiated base pairs were calculated and compared with those of bare base pairs. This comparison provided the changes in the spectra as a fingerprint for the structural identification of different lithiated base pairs. Also, the determination of the change in the strength of hydrogen bonds in the lithiated base pairs compared to their bare base pairs. In the other part of this study, the effect of the hydration of the attached Li+ in the structure of lithiated base pairs on the strength of their hydrogen bonds and spectra was investigated.

High-order Azimuth Coherent Imaging for Microseismic Location

Abstract The cross-correlation-based methods, widely used for microseismic monitoring, utilize cross-correlation to extract time differences of signals within station pairs, and subsequently use these time differences for back-projection and localization, without the need for triggering moment scanning. The selection of imaging conditions, applied to the spatial projection of all cross-correlation records determines the noise resistance and resolution of such methods. To fully exploit the azimuthal properties of station pairs for constraining the source imaging, we propose a high-order azimuth coherent imaging condition, which involves the following steps: (1) Choosing station pairs that meet specific inter-station distance criteria; (2) Combining station pairs into dual-station pairs that satisfy a certain inter-station pair angle criterion; (3) Further combining station combinations pairwise to form the final set of station pairs; (4) Multiplying the projection results of station pairs within each combination from the third step; (5) Summing the results of all combinations. This method effectively suppresses the hyperboloid in the spatial projection of a single station, enhances the coherence of seismic source imaging, and maintains noise resistance. Compared to the conventional imaging conditions, the method proposed has demonstrated superior resolution and robustness in both theoretical analysis and practical testing.