Positive Moment Research Articles

Research on the Comprehensive Optimization of the Hydraulic Performance and Frost-Heaving Resistance of a Parabolic Channel

Hydraulic performance and frost-heaving resistance should be considered simultaneously in the channel design of seasonally frozen soil areas. Quadratic parabolic channels have good water and sand transport capacities and high frost-heaving resistances. The width–depth ratio of a parabola determines its section structural form, which in turn determines the hydraulic performance and frost-heaving resistance. In this research, based on the current lack of a comprehensive optimization method that accounts for the hydraulic performance and frost-heaving resistance of the cross-section structures of parabolic channels, a multi-objective optimization model was established with the goal of achieving a minimum cross-sectional flow area and a uniform channel section force. Taking the flow velocity, the width–depth ratio and the crack resistance of concrete lining plate as constraints, the α method of the linear weighted sum method was used to optimize the calculation, and the comprehensive optimal quadratic parabolic channel section was obtained. The comprehensive optimal section of an actual parabolic channel in the Shijin Irrigation District was determined using this method, and the comprehensive optimal section was analyzed and compared to the original design section and two typical parabolic channel sections. The comprehensive optimal section was compared with the original design section in the Shijin Irrigation District. The force uniformity of the optimal section was 23.2% better, the hydraulic performance was 1.96% better, and the land use was 12.35% less. Compared with the values for the hydraulic optimal section, the maximum positive and negative bending moments of the comprehensive optimal section decreased by 5.6% and 11.89%, respectively, and the force uniformity increased by 7.62%. Additionally, compared with the values for the practical economic section, the force uniformity and the hydraulic performance of the comprehensive optimal section increased by 1.79% and 0.2%, respectively, and the land use decreased by 4.49%. Thus, the comprehensive optimal section met the engineering requirements and it could provide a reference for the design and selection of parabolic channels in seasonally frozen soil areas.

Effective slab width for beam-end flexural strength of composite frames with circular-section columns

The calculation of the ultimate loading capacity of composite frame beams is an important step in the design of composite frame structural systems. This paper puts forward the Compression-on-Column-Face, Compression-on-Transverse-Beam and Tension-on-Transverse-Beam mechanisms to explain the mechanism of the circular-section column frame in the ultimate loading state, and an extensive parametric analysis is conducted on a series of typical composite beam–column joint subassemblies using the nonlinear finite-element simulation method. First, an elasto-plastic elaborate finite element model is established to conduct the parametric analysis of the exterior joint of the circular-section column frame under negative and positive moment. Furthermore, based on the parametric analysis, the simplified design formulae of the slab effective width are derived. The proposed formulae and numerical results are compared for the effective slab width for composite frames with circular-section columns, and the relative errors are little. In addition, the applicability of the formulae to calculate the effective slab width at the interior joints in the circular-section column frame is verified. Finally, this paper compares the proposed formulae with formulae in the current design codes, and the proposed formulae provide the most accurate results to predict the effective slab width and ultimate loading capacity.

Paramagnetic Meissner Effect in the Magnetic Superconductor DyRh3.8Ru0.2B4

The paramagnetic Meissner effect, previously observed in yttrium and bismuth cuprates, was discovered in DyRh3.8Ru0.2B4, a single-phase superconductor possessing its own intrinsic magnetic subsystem. Measurement of the magnetic moment in DyRh3.8Ru0.2B4 was carried out in the FC (field-cooling) and ZFC (zero-field cooling) modes: cooling in or without a magnetic field, followed by heating in the magnetic field. Appearance of a positive magnetic moment was established in the study of complex rhodium boride in the FC mode in the fields of ~20 Oe (below the first critical value). The appearance of a paramagnetic Meissner effect in DyRh3.8Ru0.2B4 at fields B < Bc1 is related to the peculiarities of the magnetic subsystem behavior when the sample is cooled in the FC or ZFC modes at a temperature below the phase transition point from the paramagnetic to the ferrimagnetic state. Correlation of this anomaly with the intrinsic magnetic subsystem of the compound formed by a cluster crystal structure of the LuRu4B4 type is discussed. The influence of the intrinsic magnetic subsystem on the increased stability of the superconducting state is established. The presence of the intrinsic magnetic subsystem distinguishes the studied single-phase rhodium boride from other type II superconductors, which do not have a magnetic subsystem.

Parametric slat design study for thick-base airfoils at high Reynolds numbers

Abstract. Standard passive aerodynamic flow control devices such as vortex generators and gurney flaps have a working principle that is well understood. They increase the stall angle and the lift below stall and are mainly applied at the inboard part of wind turbine blades. However, the potential of applying a rigidly fixed leading-edge slat element at inboard blade stations is less well understood but has received some attention in the past decade. This solution may offer advantages not only under steady conditions but also under unsteady inflow conditions such as yaw. This article aims at further clarifying what an optimal two-element configuration with a thick main element would look like and what kind of performance characteristics can be expected from a purely aerodynamic point of view. To accomplish this an aerodynamic shape optimization procedure is used to derive optimal profile designs for different optimization boundary conditions including the optimization of both the slat and the main element. The performance of the optimized designs shows several positive characteristics compared to single-element airfoils, such as a high stall angle, high lift below stall, low roughness sensitivity, and higher aerodynamic efficiency. Furthermore, the results highlight the benefits of an integral design procedure, where both slat and main element are optimized, over an auxiliary one. Nevertheless, the designs also have two caveats, namely a steep drop in lift post-stall and high positive pitching moments.

Finding focus in a difficult landscape: Therapists’ experiences with challenging video guidance processes for parent–infant dyads

Marte Meo video guidance uses filmed interaction of the actual parent-infant dyad in the guidance of caregivers. Exploring the challenges that therapists meet in the guidance of parent-infant dyads may illuminate important aspects of the method itself as well as the therapists' role and requirements. This could lead to method development and improved practice, but is hitherto little addressed. In this paper, we explore how skilled therapists experience and handle challenging or failing guidance processes with parent-infant dyads. We analyzed interviews with 13 Marte Meo therapists/supervisors using team-based reflexive thematic analysis. Four main themes were identified: promoting relational growth in a coercive context, building an alliance that feels safe for the parents, looking at positive moments in difficult lives, and handling intense feelings as a therapist. Our findings show that therapists experience specific therapeutic and ethical challenges with a vulnerable subgroup of parent-infant dyads where child protective issues arise, where caregivers' insecurities impede the therapeutic relationship, and where caregivers have unsolved relational or mental health problems. The therapists' role becomes pivotal and demanding with regard to the therapeutic alliance, the therapeutic interventions in the guidance process, and their own need for regulation, supervision, and structure. Identification of these vulnerable dyads early in the process could facilitate a better adaptation and practice of video guidance. Our findings suggest a need for supporting structures, clinical supervision, and training that address these challenges.

Multi-DQN: An ensemble of Deep Q-learning agents for stock market forecasting

The stock market forecasting is one of the most challenging application of machine learning, as its historical data are naturally noisy and unstable. Most of the successful approaches act in a supervised manner, labeling training data as being of positive or negative moments of the market. However, training machine learning classifiers in such a way may suffer from over-fitting, since the market behavior depends on several external factors like other markets trends, political events, etc. In this paper, we aim at minimizing such problems by proposing an ensemble of reinforcement learning approaches which do not use annotations (i.e. market goes up or down) to learn, but rather learn how to maximize a return function over the training stage. In order to achieve this goal, we exploit a Q-learning agent trained several times with the same training data and investigate its ensemble behavior in important real-world stock markets. Experimental results in intraday trading indicate better performance than the conventional Buy-and-Hold strategy, which still behaves well in our setups. We also discuss qualitative and quantitative analyses of these results.

Connecting spatial moments and momentum densities

The precision of experimental data and analysis techniques is a key feature of any discovery attempt. A striking example is the proton radius puzzle where the accuracy of the spectroscopy of muonic atoms challenges traditional electron scattering measurements. The present work proposes a novel method for the determination of spatial moments from densities expressed in the momentum space. This method provides a direct access to even, odd, and more generally any real, negative and positive moment with order larger than −3. As an illustration, the application of this method to the electric form factor of the proton is discussed in detail.

PARAPET STIFFNESS EFFECT ON LOAD CARRYING CAPACITY OF MULTI-LANE CONCRETE SLAB BRIDGES

Bridge specifications do not consider the effect of parapet stiffness in the analysis and design of reinforced concrete slab bridges. This paper performs a parametric investigation using finite element analysis (FEA) to study the effects of parapet stiffness on live load-carrying capacity of two-span, three-and four-lane concrete slab bridges. This study analyzed 96 highway bridge cases with varied parameters such as span-length, bridge width, and parapet stiffness within practical ranges. Reinforced concrete parapets or railings, built integrally with the bridge deck, were placed on one and/or both sides of bridge deck. The longitudinal bending moments calculated using the FEA results were compared with reference bridge cases without parapets, as well as AASHTO Standard and LRFD specifications. The FEA results presented in this paper showed that the presence of concrete parapets reduces the negative bending moments by 15% to 60% and the positive bending moments by 10% to 45%. The reduction in longitudinal bending moments can mean an increase in the load-carrying capacity of such bridges depending on the parapet stiffness. This investigation can assist engineers in modeling the actual bridge geometry more accurately for estimating the load-carrying capacity of existing concrete bridges. Hence, new bridges can be designed by considering the presence of concrete parapets. Parapets can be used as an alternative for strengthening existing one and two-span reinforced concrete slab bridges.

Experimental detection of non-local correlations using a local measurement-based hierarchy on an NMR quantum processor

The non-local nature of the correlations possessed by quantum systems may be revealed by experimental demonstrations of the violation of Bell-type inequalities. Recent work has placed bounds on the correlations that quantum systems can possess in an actual experiment. These bounds were limited to a composite quantum system comprising of a few lower-dimensional subsystems. In a more general approach, it has been shown that fewer body correlations can reveal the non-local nature of the correlations arising from a quantum mechanical description of nature. Such tests on the correlations can be transformed to a semi-definite program (SDP). This study reports the experimental implementation of a local measurement-based hierarchy on the nuclear magnetic resonance (NMR) hardware utilizing three nuclear spins as qubits. The protocol has been experimentally tested on genuinely entangled tripartite states such as W state, GHZ state and a few graph states. In all the cases, the experimentally measured correlations were used to formulate the SDP, using linear constraints on the entries of the moment matrix. We observed that for each genuinely entangled state, the SDP failed to find a semi-definite positive moment matrix consistent with the experimental data. This implies that the observed correlations can not arise from local measurements on a separable state and are hence non-local in nature, and also confirms that the states being tested are indeed entangled.

Effect of Segmental Joint on Internal Forces in Tunnel Lining under Seismic Loading by Numerical Method

Although segmental tunnel linings are often used for seismic areas, the influence of segment joints on the segmental lining behavior under seismic loading has not been thoroughly considered in the literature. This paper presents the results of a numerical study investigating the effects of the rotational, axial, and radial joint stiffness of the longitudinal joints on the structural forces in segmental tunnel lining under seismic loading. A 3D finite element method is adapted to establish elaborate numerical models of the segments. The validity of the numerical model was tested by comparing the results obtained with the well-known analytical methods presented by Wang and Penzien. The results demonstrate that by increasing the rotational stiffness of the segmental joint, the bending moment increases. When the rotational stiffness ratio is less than 0.5, the positive and negative bending moment variations are more. The numerical modeling results show the variations in the bending moment and the difference between the positive and negative bending moment values increased by increasing the acceleration of seismic loading. Moreover, it is significant for the values. By increasing the rotational stiffness ratio of the segmental joint, the axial force ratio decreases. By increasing the axial and shear stiffness ratio of segmental joint, the variations in the bending moment and axial force in segmental lining is not significant and is ignorable in designing segmental lining.

Религиозная активность православия и ислама в Республике Татарстан в условиях государственного регулирования сложной эпидемиологической обстановки.

During the twentieth century, humanity experienced several pandemics, the most dangerous and large-scale of which was the influenza of the period 1918–1920. In early 2020, the World Health Organization has announced a new worldwide threat caused by a representative of the coronavirus family. All branches of human activity have found themselves in a completely new situation. The spiritual and religious life of the world's population is no exception. In the Russian Federation, religious organizations took into account the new threat, which was reflected in the change in their normal life and Ministry. In the Republic of Tatarstan, there was a rapid response from the leadership of Orthodox and Islamic religious organizations to the problem. At a certain stage, it was decided to suspend the performance of services in religious buildings (temples and mosques). Recommendations were made to strengthen your prayers at home. At the same time, some forms of electronic contact between the religious population and religious organizations were organized (in particular, in the form of receiving electronic notes about health or repose, with the opportunity to make alms for this in the form of electronic payment). It is obvious that among the clergy in the Orthodox and Muslim environment there are different views on everything that is happening, their evolution is discussed in this article. A common positive moment for the Orthodox and Muslim religious community was the decision to resume services with the possibility of full-time attendance of believers. Both in the Kazan Metropolitan area and in the Spiritual administration of Muslims, quite similar regulations were adopted to observe measures to prevent the spread of a new viral infection. However, unfortunately, the accepted instructions are either violated or not fully implemented. Some underestimation of the danger of a new coronavirus infection on the part of both parishioners and the leadership of religious organizations becomes obvious.

Inequalities for the dth residual crank moments of overpartitions

In 2009, Bringmann, Lovejoy and Osburn defined two analogues of the crank function for overpartitions, namely the first residual crank and second residual crank. For a positive integer [Formula: see text], we introduce the notion of a [Formula: see text]th residual crank function for overpartitions, examine the positive moments of these generalized crank functions while varying [Formula: see text], and prove some inequalities.

FCC-to-HCP Phase Transformation in CoCrNix Medium-Entropy Alloys

A hybrid first-principles/Monte Carlo simulation is combined with experiments to study the structure and elastic properties of CoCrNix (x = 1–0.5) alloys. The experimental X-ray diffraction patterns show that the structures have changed from the single-phase face-centered cubic (FCC) structure at x = 1–0.8 to the coexistence of FCC and the hexagonal close-packed structures at x = 0.7–0.5, which is further confirmed by calculations on mixing energies. The elastic moduli by calculation are basically in agreement with experiments. Room-temperature tension shows that the six alloys have a certain plasticity, the strength and plasticity of the alloys have a linear decrease with the decrease in Ni contents, and the plasticity of the alloys drops from 84 to 23%. Furthermore, first-principles density function theory calculations were employed to reveal the electronic and magnetic structures of alloys. The electron density of states for all alloys is asymmetrical, which illustrates that the alloys are ferromagnetism. It is found that Cr atoms can suppress the ferromagnetism of alloys, since Cr atoms have both positive and negative magnetic moments in all alloys.

Overturning and rolling avoidance by gecko when challenged with inclines

Abstract Understanding how animals avoid overturning and rolling in motion to maintain movement stability and to accommodate their habitat and the mechanisms of movement in these habitats is a matter of concern. Gecko climbs a more inclined substrate by lowering the speed; meanwhile, the duty factor is increased with the increase of the incline angle, indicating that the gecko switches the diagonal gait when climbing on the shallow inclines to the triangular gait when on the inverted surface. The overturning impulse moment is increased with an increase of the incline angle. On inclines larger than 90°, the positive and negative overturning impulse moments are increased significantly and show obvious differences. The maximum value of rolling impulse moment on the surface at 180° can reach 15 times that of the minimum value on the surface at 90°, and the positive and negative rolling impulse moments at the inclined surface of 120–180° have obvious differences. The above results show that on shallow inclines, the low centre of mass and the flat posture of the gecko can effectively improve locomotion stability; simultaneously, through the timely conversion of the limb function, the overturning/rolling impulse moments are low, which greatly reduces the probability of overturning/rolling during locomotion. However, on inverted inclines, the gecko takes full advantage of the flexibility of body and limbs to delay the occurrence of rolling and overturning, and actively cooperates with the adjustment of the gait, using the alternating change of gait to avoid overturning and rolling.

Seismic performance evaluation of damage-controlled composite steel frame with flexible-gel-covered studs

This paper proposes flexible-gel-covered (FGC) studs to reduce the earthquake damage of a concrete slab in a composite steel frame. With the FGC studs in the novel frame, the shear constraint between the steel beam and the concrete slab was intentionally released, and the tensile strain of the slab decreased under a positive moment when the initial objective was achieved. To verify the utility of FGC studs in damage control, a numerical model was developed in ABAQUS. The performance of one single composite beam was investigated to obtain the optimal configuration of the FGC studs. Based on single beam analysis, two steel frames were modeled using ABAQUS, including one conventional frame and one novel steel frame with FGC studs. Pushover analysis and nonlinear dynamic analysis were carried out. The numerical simulation results revealed that the overall structural performance of the novel frame with FGC studs was adequately maintained compared with a conventional steel frame, which demonstrates the direct applicability of the current seismic design approach. The performance of the FGC stud and its effective range for damage reduction are discussed in detail. The FGC studs are beneficial in terms of reducing the local slab damage under small to moderate earthquakes. Under strong earthquake, the efficiency decreased for very large story drift.

The (in)efficiency of NYMEX energy futures: A multifractal analysis

We performed a systematic analysis to investigate the multifractal properties and Efficient Market Hypothesis (EMH) in time series of volatility for NYMEX (New York Mercantile Exchange) energy futures using the Multifractal Detrended Fluctuations Analysis (MF-DFA). We studied the generalized Hurst exponent h(q) and the Rényi exponent τ(q) for each record and quantify their statistical properties which allowed us to observe separately the contributing small scale (primarily via the negative moments q) and the large scale (via the positive moments q). We also calculated the multifractal spectrum f(α) and used a fourth-degree polynomial regression fit to estimate the complexity parameters that describe the degree of multifractality of the underlying process. The results obtained from our fitting procedure show that the volatility time series of NYMEX energy futures display overall persistent behavior (α0>0.5), a higher degree of multifractality and the dominance of large fluctuations. In this sense, our empirical results related to (α0>0.5) categorically reject the EMH. Furthermore, our results presented that Crude oil (Light-Sweet, Cushing, Oklahoma), the No. 2 heating oil (New York Harbor) and Propane (Mont Belvieu, Texas) energy futures are highly concentrated with behavior more closely associated to oligopolistic market.

Three Dimensional Analysis of Raft Foundation Rest on Homogenous Soil Using Finite Element Method

The study includes analysis of Al – Samaraie Hospital raft foundation by the finite element method (FEM) using program package Fear 4.0. The analysis conducted on the foundation is resting on infinite, homogeneous, isotropic soil. In this study, effect of raft thickness, soil properties, modulus of elasticity and Poisson’s ratio of soil are investigated. The most dominant parameters such as thickness of raft foundation, modulus of elasticity and Poisson’s ratio of soil are graphically plotted against maximum displacements, maximum positive and negative bending moments (Mx, My and Mxy). The results showed that raft thickness and soil properties play a vital role in changing the values of maximum positive and negative moments (Mx, My) and maximum displacements, while their effect on maximum positive and negative moment (Mxy) can be considered as insignificant. Also, empirical equations have been developed to calculate maximum positive and negative bending moment (Mx, My) and maximum displacements beneath the raft. This is performed by the aid of statistical program (Statistic). The accuracy of the proposed equations was ranging between 92.7% and 99.9%.

Experimental analysis of longitudinal shear of composite slabs

Abstract The composite concrete slab systems with steel-deck incorporated has become an alternative to conventional slab models, since it often does not require the use of shoring, promoting several constructive practices, beyond operation of the reinforcement as a positive moment. The procedure of verification of composite slabs is based on the semi-empirical method m and k. The purpose of this paper was to investigate the application of the "m-k method" in a group of slabs with alternative dimensions as the usually adopted in the tests, even as to correlate the values obtained with the results found when testing the models as proposed by the ANSI 2011 test standard, since the normative method is costly and expensive. Therefore, four-point flexural tests were performed on slab models considering only one deck module, varying two spans, the same procedure was repeated in slabs with usual construction dimensions (normative models). The linear regression method was applied to the data found in order to obtain the parameters that would be analyzed. The main results show that the alternative model with the adopted dimensions does not present values that can be applied directly to the normative models, since the increase of the shear span reduces in a significant way the theoretical resistance of the slabs. Nevertheless, the values for the m and k obtained of both alternative and normative models can be adopted confidently as part of the sizing process of the respective models. The deviations between theoretical and experimental resistance satisfy the specifications of the ANSI 2011 standard for both models helped in the confirmation of the previous statement. The expectation of this paper is to assist in the search for new procedures for determining parameters m and k.

Adsorption of Polarized Molecules for Interfacial Band Engineering of Doped TiO2Thin Films

Owing to their chemical and mechanical stability, metal-oxides have emerged as potential alternatives for conventional pure-metal and organic molecule-based solid-state electronic devices. Traditionally, band engineering of these metal-oxides has been performed to improve the efficiency of solar cells and transistors. However, recent advancements in the field of oxide-based electronic devices demand reversible band structure engineering for applications in next-generation adaptive electronics and memory devices. Therefore, this work aims to reversibly engineer the surface band structure of doped metal-oxides using stable organic ligands with weak dipoles. Para-substituted benzoic acid (BZA) ligands with positive and negative dipole moments were adsorbed in situ on the surface of TiO2:Ni2+ thin film to modify the interfacial dipole moment, and the valence band structure was probed using surface-sensitive ultraviolet photoelectron spectroscopy (UPS). UPS, paired with density functional theory (DFT) simulations, demonstrate the ability to selectively tune interfacial electronic/chemical landscapes with ligand-dependent dipole moment. The unique ability to reversibly tune the band bending at the organic–inorganic interface of doped metal-oxide semiconductors using molecular dipoles is expected to play a key role in the development of metal-oxide-based adaptive electronics that outperform the conventional polymer-based and Si-based devices.

Kloosterman Sums and a Problem of D. H. Lehmer

A classical problem of D. H. Lehmer suggests the study of distributions of elements of Z/pZ of opposite parity to the multiplicative inverse mod p. Zhang initiated this problem and found an asymptotic evaluation of the number of such elements. In this paper, an asymptotic formula for the fourth moment of the error term of Zhang is proved, from which one may see that Zhang’s error term is optimal up to the logarithm factor. The method also applies to the case of arbitrary positive integral moments.