Weak Moment Research Articles

Study on Collapse Optimization of Weak Axis Moment Connections

Abstract: 3D Weak axis moment connections are the connections between the beam with the web of an I section. But these connections are weaker as they are connected to the web which are thinner portions of the I section compared to flanges. This can lead to buckling of flanges. A new reduced beam section (RBS) connection, consisting of radius cuts in the beam flanges and circular openings in the beam webs, is proposed to allow for more ductile connections. RBS connections may increase structural deflection and crack width in the steel frame structure under large deformations. Therefore, it is extremely important to consider the bearing capacity and progressive collapse resistance of steel frame structures with RBS connections. Progressive collapse analysis of weak axis moment connections without any improvisation is taken for analysis and their collapse location and collapse resistance studied. To enhance weak joint connection design and to delay collapse time, we introduce reduced beam sections. Curved cell reduced beam sections are modeled and analysis is performed for various thickness of cell and by changing diameter. Thus, an effective size was obtained by combining the results with the conventional and the effective location of weak axis is improved

Hydroelastic analysis of a floating bridge under spatially inhomogeneous waves, with emphasis on the effect of drift force modeling

The pontoon-supported floating bridge is an alternative concept for crossing a fjord with a width of up to 5 km. Due to the huge span, the first two natural periods of the bridge are more than 60 s, indicating that the corresponding modes can be excited by slowly-varying drift forces on the pontoons. A simplified approach for determining the drift forces is to assume that the pontoons are independent of the floating bridge, i.e., fixed or freely floating. However, the first-order motions of the pontoons, which are restricted by the deformation of the floating bridge, have a significant effect on the drift forces. To evaluate the uncertainties implied by the simplification of drift forces, in this study, a second-order beam-connected-discrete-modules (BCDM) hydroelastic method is adopted to assess the effect of different drift force models on the floating bridge. In this method, the first-order response amplitude operators (RAOs) of bridge-restricted pontoons are first solved in the frequency-domain. Based on the RAOs, the mean drift forces for each pontoon are then determined by using potential theory. Considering the spatial inhomogeneity of the wave field, the time series of the first- and second-order wave forces are generated by using the linear transfer functions and Newman’s approximation, respectively. Then, the method is applied to investigate the hydroelastic responses of a straight side-anchored floating bridge for the crossing site of Bjørnafjord. The results show that the horizontal displacement is very sensitive to the different force models implied by various pontoon boundary conditions, i.e., free, fixed, and bridge-restricted. The drift forces on the bridge-restricted pontoons are approximately 10%–20% larger than those for the fixed pontoons. Moreover, wave inhomogeneity results in increased vertical displacements and weak axis bending moments.

Ab initio study: Investigating the adsorption behaviors of polarized greenhouse gas molecules on pillar[5]arenes

Supramolecular organic frameworks (SOFs) based on Pillar[5]arenes (P[5]A) have shown great potential in capturing and separating greenhouse gases. In this study, we investigate the adsorption behaviors of other environmentally harmful gas molecules, including NO, NH3, CO, and NO2 on pillar[5]arenes (P[5]A) using DFTB and DFT calculations. The P[5]A structures exhibit the capability to adsorb including NO, NH3, CO, and NO2 at both the cavity site and OH group, facilitated by π-π interactions and hydrogen bonding. CO exhibits the lowest binding energy among the studied gases, primarily due to its weak dipole moment. In contrast, the cavity-in positions for NO2 and NH3, characterized by high polarization, exhibit the highest adsorption energies. The adsorption energies at the top-out positions are relatively similar for all gases examined. These findings provide valuable insights for the targeted design and optimization of P[5]A, enabling its potential applications in effectively capturing toxic gases.

Complicated point defects in monolayer Ga2S3: stability, midgap states and magnetism

Motivated by recent experimental realization of single-layer α-Ga2S3 [Zheng et al., Adv. Funct. Mater. 31, 2008307(2021)], by using first principles calculations, we systematically investigated the structural, electronic and magnetic properties of single-layer α-Ga2S3 with intrinsic point defects. Although it is a binary semiconductor, its point defects properties are complicated, since there are nonequivalent Ga and S atomic sites in this compound. The most energetically stable vacancy and interstitial defect are VS2 and Si1 for the entire sulfur chemical potential range, while the most energetically favorable antisite defect is dependent on the sulfur chemical potential, such as GaS2 under S-poor condition and SGa1 (SGa2) under S-rich condition. The sulfur vacancy defects (VS1, VS2 and VS2) have induced spin-degenerated defect states in the band gap or the valence band edge, while the gallium vacancy defects (VGa1, and VGa2) have spin-polarized defect states in the band gap or valence band edge with the magnetic moment of 1.30 μB and 1.21μB per defect. The interstitial defects (Gai1, Si1 and Si2) can generate spin-degenerated in-gap defect states. The antisite defects (GaS1, GaS2, GaS3, SGa1, and SGa2) have spin-polarized in-gap defect states with weak magnetic moments of 0.70 μB, 0.69μB, 0.64μB, 0.66μB and 0.65μB per defect. Besides, the origin of the defect states and magnetic moments are examined in detail. These findings are helpful for understanding the defect properties of two dimensional IIIA-VIA binary chalcogenide Ga2S3 and improving its technological applications.

Searching the anomalous electromagnetic and weak dipole moments of the top quark at the bestest little Higgs model

Searching the anomalous electromagnetic and weak dipole moments of the top quark at the bestest little Higgs model

Half-metallicity feature within Ag-doped zincblende WGe alloys: DFT+U insights

By employing the full-potential linearized augmented plane wave (FP-L/APW[Formula: see text]lo) technique based on density functional theory (DFT), the structural, electronic and magnetic properties of zincblende W[Formula: see text]AgxGe alloys ([Formula: see text] and 0.25) are scrutinized thoroughly. Based on the generalized gradient approximation (GGA), the exchange-correlation energy functional is included in the current simulation. For computing the structural features, the GGA approximation is applied, whereas GGA, [Formula: see text] and the modified Burke–Johnson of [Formula: see text] (TB-mBJ-[Formula: see text] approximations are incorporated to perform the calculations of electronic and magnetic behaviors of these alloys. The structural analysis of the alloys indicated that the total energy of the W[Formula: see text]Ag[Formula: see text]Ge alloy was favorable in the ferromagnetic ground state. The spin-polarized electronic structure shows the half-metallic behavior of the W[Formula: see text]Ag[Formula: see text]Ge alloy, while the WGe compound is identified as a metal. The magnetic results obtained from the half-metallic W[Formula: see text]Ag[Formula: see text]Ge alloy increasingly support the full half-metallicity of this compound because an integer value is acquired for the total magnetic moment. The strong hybridization between 4p-Ge and 3d-W states brings forth weak local magnetic moments at the nonmagnetic Ge atomic sites and reduces the local magnetic moment of the W atomic sites from its free space charge.

An Excess Entropy Approach to Classify Long-Term and Short-Term Memory Stationary Time Series

Long-term memory behavior is one of the most important phenomena that has appeared in the time series analysis. Different from most definitions of second-order properties, an excess entropy approach is developed for stationary time series to classify long-term and short-term memory. A stationary sequence with finite block entropy is long-term memory if its excess entropy is infinite. The simulation results are graphically demonstrated after some theoretical results are simply presented by various stochastic sequences. Such an approach has advantages over the traditional ways that the excess entropy of stationary sequence with finite block entropy is invariant under instantaneous one-to-one transformation, and that it only requires very weak moment conditions rather than second-order moment conditions and thus can be applied to distinguish the LTM behavior of stationary sequences with unbounded second moment (e.g., heavy tail distribution). Finally, several applications on real data are exhibited.

Composition‐Dependent Ferroelectricity of LuFeO3 Orthoferrite Thin Films

AbstractThis work characterizes the structural, magnetic, and ferroelectric properties of epitaxial LuFeO3 orthoferrite thin films with different Lu/Fe ratios. LuFeO3 thin films are grown by pulsed laser deposition on SrTiO3 substrates with Lu/Fe ratio ranging from 0.6 to 1.5. LuFeO3 is antiferromagnetic with a weak canted moment perpendicular to the film plane. Piezoresponse force microscopy imaging and switching spectroscopy reveal room temperature ferroelectricity in Lu‐rich and Fe‐rich films, whereas the stoichiometric film shows little polarization. Ferroelectricity in Lu‐rich films is present for a range of deposition conditions and crystallographic orientations. Positive‐up‐negative‐down ferroelectric measurements on a Lu‐rich film yield ≈13 µC cm−2 of switchable polarization, although the film also shows electrical leakage. The ferroelectric response is attributed to antisite defects analogous to that of Y‐rich YFeO3, yielding multiferroicity via defect engineering in a rare earth orthoferrite.

Atomic Displacements Enabling the Observation of the Anomalous Hall Effect in a Non-Collinear Antiferromagnet.

Antiferromagnets with non-collinear spin structures display various properties that make them attractive for spintronic devices. Some of the most interesting examples are an anomalous Hall effect despite negligible magnetization and a spin Hall effect with unusual spin polarization directions. However, these effects can only be observed when the sample is set predominantly into a single antiferromagnetic domain state. This can only be achieved when the compensated spin structure is perturbed and displays weak moments due to spin canting that allows for external domain control. In thin films of cubic non-collinear antiferromagnets, this imbalance waspreviously assumed to require tetragonal distortions induced by substrate strain. Here weshow that in Mn3 SnN and Mn3 GaN, spin canting is due to structural symmetry lowering induced by large displacements of the magnetic manganese atoms away from high symmetry positions. These displacements remain hidden in X-ray diffraction when only probing the lattice metric and require measurement of a large set of scattering vectors to resolve the local atomic positions. In Mn3 SnN, the induced net moments enable the observation of the anomalous Hall effect with an unusual temperature dependence, which weconjecture results from a bulk-like temperature-dependent coherent spin rotation within the Kagomeplane. This article is protected by copyright. All rights reserved.

The effect of teacher leadership on students’ purposeful learning

Teaching leadership is a key factor for students’ learning and flourishing, and it occurs in an asymmetrical and interpersonal relationship. This research seeks to characterize the teaching leadership of high school teachers through the influence they exert on their students. It is not based on the teacher’s self-perception but on the experience that the students have had. For this purpose, a qualitative study was carried out in Spain with 200 first-year university students in which they answered four questions about the teacher who most influenced them during their high school. The results point to five leadership traits or styles that are not mutually exclusive: empathetic leadership, comforting leadership, motivating leadership, exemplary leadership, and wise leadership. In addition, moments of weakness and vulnerability in students are those that most favour the influence of the teacher in their lives, encouraging vital learning in them. This study highlights the importance of teacher leadership for student character education.

Post-Covid Brazil and the new government: Economy and foreign policy

The Brazilian economy has more continuity than ruptures in the end of the pandemic as well over former Bolsonaro’s government closure. Positive economic indicators since 2021 were followed by a further slowdown at the end of 2022, keeping the pattern of weak growth moments in the midst of a near stagnation trend. The export of goods based on natural resources remains a positive factor as in the previous decades, though with the same problems of low leverage capacity of productivity diffusion to other sectors. The public sector faces great difficulties when trying to promote growth and modernization because of fiscal rigidity aggravated by mandatory expenses and varied resistance to cutting spending and redirecting expenses caused by conflicts that are hard to coordinate. After a brief presentation of the economic indicators at the end of 2022, the paper highlights three elements that condition the economic policy in the post-Covid Brazil: the rigidity of fiscal framework; export industry performance and deindustrialization; resumption of the foreign policy that will allow the country to benefit from the international scenario.

Nonasymptotic analysis of robust regression with modified Huber's loss

To achieve robustness against the outliers or heavy-tailed sampling distribution, we consider an Ivanov regularized empirical risk minimization scheme associated with a modified Huber's loss for nonparametric regression in reproducing kernel Hilbert space. By tuning the scaling and regularization parameters in accordance with the sample size, we develop nonasymptotic concentration results for such an adaptive estimator. Specifically, we establish the best convergence rates for prediction error when the conditional distribution satisfies a weak moment condition.

Antiferromagnetic Cavity Magnon Polaritons in Collinear and Canted Phases of Hematite

Cavity spintronics explores light-matter interactions at the interface between spintronic and quantum phenomena. Until now, studies have focused on the hybridization between magnons in ferromagnets and cavity photons. Here, we realize antiferromagnetic cavity magnon polaritons. Hybridization arises from the interaction of the collective spin motion in single hematite crystals (\ensuremath{\alpha}-${\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$) and the microwave field of integrated cavities operating between 18 and 45 GHz. We show theoretically and experimentally that the photon-magnon coupling in the collinear phase is mediated by the dynamic N\'eel vector and the weak magnetic moment in the canted phase by measuring across the Morin transition. We show that the coupling strength, $\stackrel{~}{g}$, scales with the anisotropy field in the collinear phase and with the Dzyaloshinskii-Moriya field in the canted phase. We reach the strong-coupling regime in both canted (cooperativity C > 70 for selected modes at 300 K) and noncollinear phases (C > 4 at 150 K), and thus, towards coherent information-exchange-harnessing antiferromagnetic cavity magnon polaritons. These results provide evidence for a generic strategy to achieve cavity magnon polaritons in antiferromagnets for different symmetries, opening the field of cavity spintronics to antiferromagnetic materials.

Computational study on nickel doped encapsulated Mg, K, Ca on pristine C24 nanocage for gas sensing applications

Intense attention have been channeled into environmental sustainability due to the high emission of greenhouse gases therefore, this investigatiom focuses on the adsorption and sensing properties of nickel doped encapsulated Mg, K, Ca on pristine C24 nanocage for CO2, NO2 and SO2 gases using density functional theory (DFT) method. Two adsorption models were designed due to the shape of the gas molecules, interacting to the doped atom, the DFT/TPSSh/Gen method was utilized to explore the adsorption properties from the perspective of geometry analysis, adsorption energy (Eads), electronic properties, visual study of weak interactions, dipole moment, and recovery time for reusability were considered. This work incorporated a comprehensive reference for the selectivity of the adsorbents’ modification towards the effective sensing of these toxic gases. Thus, the electronic properties confirms the conductivity on modification of surface with dopant. Also, the nature of interaction as reveal by the QTAIM analysis was non-covalent in nature and was further confirmed by the analysis of the non-covalent interaction (NCI). Moreso, the reusability analysis confirms surface sensing properties. Adsorption energies; −3.67, −2.48, −3.89, −2.50, −3.82, −3.67 eV, were reported for NO2–Ni@MgC, CO2–Ni@KC, NO2–Ni@KC, CO2–Ni@CaC, NO2–Ni@CaC, SO2–Ni@CaC respectively. Moreover, the aforementioned analyses demonstrate the significant impact on the adsorption models most especially NO2–Ni@KC. Hence, Ni@KC and Ni@CaC shows promising sensitivity towards the gas molecules than Ni@MgC. Based on our theoretical results, the encapsulation of K, Ca, Mg, and late transition metal dopant enhances the adsorbents, which induced the improvement in surface properties. The highest Eads was observed at M3a at −5.11 eV and the least at M1 at −2.11 eV all for SO2 adsorption.

Russia's Invasion of Ukraine and the Modern History of Belarusian Statehood

This article examines the evolution of Belarusian statehood, highlighting the transition from its independence in 1991 to the increasingly authoritarian regime under President Aleksandr Lukashenka. It scrutinizes the complex relationship between Lukashenka and Russian President Vladimir Putin and the repeated breaches and renegotiations of their political contract. The analysis covers Belarus’ oscillation between integration with Russia and attempts at Western engagement, particularly noting the period of soft Belarusification from 2014 to 2020 as a response to fears of Russian annexation. The 2020 presidential elections marked a turning point, with mass protests against Lukashenka’s claimed victory leading to severe crackdowns and the erosion of Belarusian sovereignty. The article argues that Belarus’ support for Russia’s 2022 invasion of Ukraine signifies a further decline in its autonomy. It advocates for a strategic approach by the West, bolstering the Belarusian opposition, supporting independent media, and exploiting moments of Russian weakness to restore and secure Belarusian democracy and independence. The author suggests that through comprehensive support for Ukraine and a proactive stance on Belarus, the West can counteract the Kremlin’s influence and prevent Russia's complete absorption of Belarus.

Nanoscale imaging of antiferromagnetic domains in epitaxial films of Cr2O3 via scanning diamond magnetic probe microscopy.

We report direct imaging of boundary magnetization associated with antiferromagnetic domains in magnetoelectric epitaxial Cr2O3 thin films using diamond nitrogen vacancy microscopy. We found a correlation between magnetic domain size and structural grain size which we associate with the domain formation process. We performed field cooling, i.e., cooling from above to below the Néel temperature in the presence of a magnetic field, which resulted in the selection of one of the two otherwise degenerate 180° domains. Lifting of such a degeneracy is achievable with a magnetic field alone due to the Zeeman energy of a weak parasitic magnetic moment in Cr2O3 films that originates from defects and the imbalance of the boundary magnetization of opposing interfaces. This boundary magnetization couples to the antiferromagnetic order parameter enabling selection of its orientation. Nanostructuring the Cr2O3 film with mesa structures revealed reversible edge magnetic states with the direction of magnetic field during field cooling.

Magnetotransport and magnetic properties of Cr-modified Mn2Sb epitaxial thin films.

High-quality Mn2-xCrxSb (x = 0.01, 0.04, and 0.1) epitaxial thin films were grown on SrTiO3 (STO) (001) single-crystal substrates using molecular beam epitaxy. Magnetotransport and magnetic measurements reveal that the x = 0.01 sample undergoes a quasi-ferrimagnetic (I) [Q-FIM(I)]-to-ferrimagnetic (II) [FIM(II)] spin reorientation (SR) transition and a giant magnetoresistance (MR) associated first-order ferrimagnetic(II)-to-antiferromagnetic (AFM) phase transition upon cooling, resulting in the AFM ground state with a weak in-plane net moment. Upon increasing the doping level from x = 0.01 to 0.1, both the SR transition and the first-order magnetic transition are suppressed. For x = 0.1, the former transition is suppressed, leaving only the Q-FIM(I)-to-AFM transition within the whole temperature region. TAFM-FIM shows almost similar changes upon the application of either in-plane or out-of-plane magnetic fields. TAFM-FIM values of the x = 0.01 and 0.04 samples are much higher than those of the Mn2-xCrxSb bulk with similar doping levels, which can be understood by the clamping effect from STO substrates. For each thin-film sample, the MR effect is observed near TAFM-FIM and disappears in the high temperature Q-FIM(I) phase and low temperature AFM phase, indicating that MR is related to the spin-dependent electron scattering during the first-order magnetic phase transition. Based on the magnetotransport and magnetic data, a magnetic phase diagram is established for the Mn2-xCrxSb films in the low doping level region.

Research on the electromagnetic and weak dipole moments of the tau-lepton at the Bestest Little Higgs Model

In this paper, using the Bestest Little Higgs Model (BLHM) we calculate at the one-loop level the contributions to the Anomalous Magnetic Dipole Moment (AMDM) and Anomalous Weak Magnetic Dipole Moment (AWMDM) of the tau-lepton. The implications from this model are studied, emphasizing the contributions of the new physics induced by the new scalar and vector bosons of the BLHM: S_i=H_0, A_0, phi ^{0}, eta ^{0}, sigma , H^{pm }, phi ^{pm }, eta ^{pm }, and V_i=Z', W'^{pm } because these quantify the new physics. With these new contributions, we estimated bounds on the real and imaginary parts of the AMDM and AWMDM of the tau-lepton. Our study complements other one-loop-level research performed on models beyond the Standard Model.

Weak dipole moments of the top-quark at the Bestest Little Higgs model

Weak dipole moments of the top-quark at the Bestest Little Higgs model

Tracy-Widom limit for the largest eigenvalue of high-dimensional covariance matrices in elliptical distributions

Let X be an M×N random matrix consisting of independent M-variate elliptically distributed column vectors x1,…,xN with general population covariance matrix Σ. In the literature, the quantity XX∗ is referred to as the sample covariance matrix after scaling, where X∗ is the transpose of X. In this article, we prove that the limiting behavior of the scaled largest eigenvalue of XX∗ is universal for a wide class of elliptical distributions, namely, the scaled largest eigenvalue converges weakly to the same limit regardless of the distributions that x1,…,xN follow as M,N→∞ with M∕N→ϕ0>0 if the weak fourth moment of the radius of x1 exists. In particular, via comparing the Green function with that of the sample covariance matrix of multivariate normally distributed data, we conclude that the limiting distribution of the scaled largest eigenvalue is the celebrated Tracy-Widom law.