Rotation Mechanism Research Articles

Nanostructure Effect on Magnetization Processes in FePt Polytwin Crystals.

In FePt polytwin crystals with large magnetocrystalline anisotropy, the boundaries may play a crucial role in the magnetization processes occurring under an external magnetic field. In this study, we employed phase-field modeling and computer simulations to systematically investigate the effect of three types of polytwin boundaries-namely, symmetric (Type I), asymmetric (Type II), and mixed (Type III) boundaries-on magnetization processes as well as coercive fields under an external magnetic field along various directions. Because of the large anisotropy of FePt, the domain wall motion mechanism is usually dominant in the domain switching processes, while the magnetization rotation mechanism only becomes important at the late magnetization stage under a high external magnetic field. Among these three types of polytwin boundaries, the low coercivity is mainly due to the domain wall motion process, which starts from the intersection point at the polytwin boundary. The coercive field for the mixed polytwin boundary (Type III) is always in between the values of Type I and II.

Revisiting the face stability of circular tunnels driven in strength nonlinearity soils

The face stability of shield-driven tunnels in soil materials with distinct strength nonlinearity is re-evaluated, based on the kinematic limit analysis theorem. The nonlinear Power-Law failure criterion is piecewise approximated by a multi-tangent technique to improve the conventional single straight-line substitution. A new multi-cone rotational mechanism formed by n curvilinear cones is proposed to accommodate the nonlinearity of the strength envelope considering the associative flow rule. The analytical solution of the critical support pressure on tunnel faces is derived from the energy equilibrium equation. Calculation results show that the multi-tangent method can improve the calculated values by up to 20% compared to the generalized tangent method. According to the back-calculated stress vectors, it is interestingly found that the stress level is not the critical factor influencing the tunnel face stability, while the shear strength parameters are the direct factor. Although the upper-bound analysis is a kinematic method without involving stress analysis, the parametric form of the strength criterion gives a chance to infer the possible stress distribution on the rupture surface and explain the variational trend of the result based on the distribution of back-calculated stress vectors.

Nonadditive functional interactions between ligand-binding sites of the multidrug efflux pump AdeB from Acinetobacter baumannii.

Multidrug efflux is one of the major mechanisms of antibiotic resistance identified in clinical isolates of the human pathogen Acinetobacter baumannii. The multiple antibiotic resistance in this species is often enabled by the overproduction of the tripartite efflux pump AdeABC. In this pump, AdeB is the inner membrane transporter from the resistance-nodulation-division (RND) superfamily of proteins, which is responsible for the recognition and efflux of multiple structurally unrelated compounds. Like other RND transporters, AdeB is a trimeric protein with ligand-binding sites located in the large periplasmic domains. Previous structural studies, however, highlighted the uniqueness of AdeB interactions with ligands. Up to three ligand molecules were bound to one protomer of AdeB, mapping its substrate translocation path. In this study, we introduced single and double substitutions in the identified ligand-binding sites of AdeB. Our results show that the mechanism of substrate translocation by AdeB is different from that of other characterized RND transporters and that the functional interactions between the sites are nonadditive. We identified AdeB mutants with both the loss and the gain of antibiotic susceptibility phenotypes, as well as AdeB mutations making A. baumannii cells overproducing such pump variants even more susceptible to multiple antibiotics than efflux-deficient cells. IMPORTANCE Multidrug efflux pumps of the resistance-nodulation-division superfamily of proteins are important contributors to various aspects of bacterial physiology and antibiotic resistance. Studies of the best-characterized model transporter AcrB from Escherichia coli suggested that these transporters operate by a functional rotation mechanism in which various substrates bind to at least two different binding sites. This study suggests that the mechanism of AdeB is distinct and that the binding sites in this transporter are functionally linked.

Light field measurement of specular surfaces by multi-polarization and hybrid modulated illumination.

Specular highlights present a challenge in light field microscopy imaging fields, leading to loss of target information and incorrect observation results. Existing highlight elimination methods suffer from computational complexity, false information and applicability. To address these issues, an adaptive multi-polarization illumination scheme is proposed to effectively eliminate highlight reflections and ensure uniform illumination without complex optical setup or mechanical rotation. Using a multi-polarized light source with hybrid modulated illumination, the system achieved combined multi-polarized illumination and physical elimination of specular highlights. This was achieved by exploiting the different light contributions at different polarization angles and by using optimal solution algorithms and precise electronic control. Experimental results show that the proposed adaptive illumination system can efficiently compute control parameters and precisely adjust the light source output in real time, resulting in a significant reduction of specular highlight pixels to less than 0.001% of the original image. In addition, the system ensures uniform illumination of the target area under different illumination configurations, further improving the overall image quality. This study presents a multi-polarization-based adaptive de-highlighting system with potential applications in miniaturization, biological imaging and materials analysis.

Mechanism of a high free-energy transduction efficiency of Bacillus PS3 F1-ATPase from the perspective of solvent entropy

Bacillus PS3 F1-ATPase is a rotary molecular motor with a 100% free-energy transduction efficiency (The 100% efficiency means that the free-energy change upon hydrolysis of adenosine triphosphate (ATP) is almost completely consumed by the external dissipation arising from the rotation of the central stalk (γ subunit) of F1-ATPase.). In this work, to elucidate the mechanism of 100% free-energy transduction efficiency, the rotation of Bacillus PS3 F1-ATPase was investigated from the perspective of solvent entropy. The two F1-ATPase structures of the catalytic- and binding-dwell states recently published were used to compute the solvation entropy (The γ subunit of the F1-ATPase structure at the binding-dwell state is rotated by 44° relative to the structure of the catalytic-dwell state). To compute the solvation entropy, the integral equation theory was used. It was found that the change in the solvent entropy of the F1-ATPase upon 44° rotation of the γ subunit is approximately zero, which is surprising because a large structural change occurs in F1-ATPase upon rotation. The present result indicated the compensation of solvent entropy in the F1-ATPase. The compensation behavior was discussed by decomposing the solvent entropy of F1-ATPase into the components of the solvent entropy of subunits and that at the interfaces between the adjacent subunits. We also discussed that the system energy and conformational entropy would also remain unchanged upon the 44° rotation of the γ subunit. Based on the results and discussion, the following rotation mechanism was proposed: the free energy of Bacillus PS3 F1-ATPase is unchanged upon rotation; and the ATP binding, hydrolysis of ATP, and release of products lead to the rotation. This mechanism is consistent with the 100% free-energy transduction efficiency of F1-ATPase.

Formation of contractility of the left ventricle in prematurely born children treated in neonatal intensive care and intensive care units, pathology of newborns

Aim: To study contractility of the left ventricle (LV) in prematurely born children of early and preschool age who received treatment in intensive care units, neonatal intensive care units and pathology of newborns in the neonatal period.Material and Methods. The study included 155 children, of which 108 children aged from one to five years old, born with very low body weight and extremely low body weight; and 47 children of the same age, born full-term and healthy. Study design: pilot, cross-sectional, retrospective, case-control study. EchoCG was performed using the Vivid E9 ultrasound system (GE, Healthcare) with M5S matrix probe (1.5–4.6 MHz). The LV global circumferential (GCSMV, GCSPM, GCSApex), and longitudinal strain, as well as the global strain of the endocardial, middle and epicardial layers of the LV were assessed. in the systole “clockwise”) was found in 33.33% of children with a history of bronchopulmonary dysplasia, and in 28.13% of children who received mechanical ventilation during the neonatal period. In 25 (69.44%) of 36 children with signs of anemia in the neonatal period, there was a decrease in deformation along the circumference of the LV epicardial layer. In 13 (86.67%) of 15 clinical observations with signs of transient hypothyroidism in the anamnesis, a decrease in deformation along the circumference of the epicardial layer was revealed.Conclusion. Factors “body weight at birth”, “fetal growth retardation”, “anemia, use of mechanical ventilation in the neonatal period”, “transient hypothyroidism”, “development of bronchopulmonary dysplasia” in children of early and preschool age born prematurely with very low and extremely low body weight, adversely affect the formation of LV contractility and rotational mechanics in the postnatal period, exacerbating the disorders caused by the immaturity of the child’s heart tissue and the implementation of other pathogenetic mechanisms in prematurity, which requires medical supervision of this clinical group in polyclinic conditions.

Penalty hexahedral element formulation for flexoelectric solids based on consistent couple stress theory

AbstractThis work proposes a penalty 20‐node hexahedral element for size‐dependent electromechanical analysis based on the consistent couple stress theory. The nodal rotation degrees of freedom (DOFs) are used to approximate the mechanical rotation, meeting the C1 requirement in a weak sense by using the penalty function method, and to effectively enhance the standard isoparametric interpolation for determining the displacement test function. The normalized stress functions that satisfy the relevant equilibrium equation and strain compatibility equation a priori are employed to formulate the stress trial function. Since the element has only three displacement, three rotation and the electric potential DOFs per node, it has relatively simple formulation and can be readily incorporated into the existing finite element program. Several benchmarks are examined and the results demonstrate that the new element has good numerical accuracy and captures the size dependence effectively. In addition, the influence of the micro‐inertia on electromechanical dynamic responses of flexoelectric solids at small scale are analyzed using the proposed element. It is shown that the nature frequency decreases with the increase of micro‐inertia and in general, the influences are more obvious on higher order modes.

An in-depth study on melting performance of latent heat thermal energy storage system under rotation mechanism by fluctuating heat source

The Organic Rankine Cycle (ORC) is a reliable and efficient means of converting solar energy into electricity. The challenges brought about by the unpredictable nature of solar energy can be effectively mitigated by utilizing latent heat thermal energy storage (LHTES) technology, specifically by implementing heat source pretreatment. This paper investigates the thermal storage properties of a rotating triplex-tube LHTES unit under different sinusoidal fluctuating heat sources. A transient numerical model is built to analyze the effects of sinusoidal wall temperature amplitude and angular velocity on the melting characteristics of the unit, including melting time, heat storage rate, and temperature response. The design is further analyzed using the Taguchi method. The results show that the angular velocity of the sinusoidal wall temperature has a greater effect on the average heat storage rate and melting time than the amplitude. When the amplitude is set to 10 and the angular velocity to 0.02, the melting time is decreased by 8.7%, while the average heat absorption rate and average temperature response increase by 10.21% and 12.27%, respectively. Additionally, the sensible and total heat energy absorption increase by 2.23% and 0.62%, compared to the initial heat source condition. Furthermore, the heat transfer is enhanced through the introduction of Al2O3 nanoparticles at varying percentages. The unit heat storage rate improves significantly with an increasing percentage of nanoparticles. Specifically, when 2.5% and 5% Al2O3 nanoparticles are added, the melting time of the unit is reduced by 3.77% and 15.07%, respectively, while the average heat absorption rate increases by 2.43% and 10.39%.

Combination of kinematic and inertial loads acting on monopile founda-tions for offshore wind turbines

Due to a growing number of offshore wind farm projects in seismic areas, existing design procedures for slender piles under seismic loading need to be revised to allow for the design of larger and stockier monopiles. This study illustrates how advanced finite element analyses can be used to investigate the combination of seismic loads and may thus inform standard design procedures commonly adopted in practice. In standard design methods, a soil-pile foundation system is represented by a simplified beam-on-nonlinear-springs model [1]. Earthquake loads acting on this system can be decomposed into inertial forces, which originate from the acceleration of a superstructure mass, and kinematic loads due to ground displacements caused by the propagation of seismic waves. Inertial loads are typically derived from modified acceleration spectra which account for the difference between the pile head movement and the soil displacement in the free-field [2, 3, 4]. Maximum displacement profiles can be obtained from site response analyses of the free-field soil column. The distribution of pile bending moments and internal forces can thus be found by superposition of the two loads. However, unless numerical time-domain analyses are carried out, it is not evident whether these components are acting simultaneously on the pile. In the design of long and slender piles, a common assumption is that inertial and kinematic loads may be considered separately, as the former tend to affect only the near-surface zones while the latter dominate at larger depths [2]. However, their combined effect on a far less flexible monopile exhibiting rotational mechanisms is not yet understood, neither is the influence of soil liquefaction triggered by the seismic ground shaking. Experiments on pile groups presented in the literature suggest a dependence of the phase angle on the ratio between the fundamental frequency of the soil deposit and the superstructure [5]. The analogous scenarios are illustrated for a monopile-supported wind turbine in Figure 1.
 The turbine is considered as a single-degree-of-freedom system with the mass off the rotor nacelle assembly lumped together and located at hub height. The time history of the inertial force acting at hub height (), as well as the horizontal ground displacement at surface level (), are schematically shown in Figure 1(b) for a very stiff soil. In this case, the fundamental period of the soil deposit () is significantly lower than that of the superstructure (), which causes the response of the turbine system to act out of phase with the ground movement by 180°. For a soft soil deposit with much higher fundamental period than the turbine (Figure 1(c)), the kinematic and inertial loads are expected to act in phase.
 To investigate the combination of seismic loads acting on a monopile foundation in the time-domain, advanced numerical analyses are carried out on three-dimensional Finite Element models. Soil layers with widely different material properties are considered, including stiff marine clays and liquefiable sands with varying relative densities. The uni-directional motion records adopted as base excitations are sufficiently strong to induce large lateral ground movements and impose significant kinematic loads on the foundation. Through the of use of appropriate constitutive models in a hydro-mechanically coupled formulation, the response of the turbine sub-structure system is simulated while accounting for the degradation of stiffness in the surrounding soil and significant rises in excess pore pressures in the sand layers. An intensely nonlinear material behaviour typically leads to a shift of the fundamental frequency of the deposit [6], which can be deduced from the amplification of accelerations at various depths, with high frequencies dominating in the stiff soil layers and low frequencies in the soft liquefied sand. For a stiff soil deposit prior to liquefaction, local extrema in pile displacements at mudline level are therefore expected to act out of phase with the inertial force resulting from the acceleration of the rotor nacelle assembly at the turbine tower top (Case ). As the stiffness diminishes in a soft or fully liquefied ground, pile and free-field ground displacements are expected to move in-phase with the inertial load, as is characteristic for cases where the period of the soil deposit exceeds that of the superstructure (Case ). This change in behaviour highlights the influence of soil stiffness degradation and extensive ground liquefaction on the combination of seismic soil-structure interaction effects in the time-domain, which can be captured by advanced numerical methods.

Left ventricular rotational mechanics and left ventricular volumes: is there a relationship in healthy adults?-three-dimensional speckle-tracking echocardiography-derived insights from the MAGYAR-Healthy Study.

Left ventricular (LV) rotational mechanics play a crucial role in LV pump function by strengthening and improving its efficacy. Dependence of LV rotational parameters on left atrial volumes has already been demonstrated. The evaluation of the effect of LV rotational mechanics on LV volumes was purposed in a population of healthy subjects by three-dimensional speckle-tracking echocardiography (STE). The study comprised 175 healthy subjects with a mean age of 32.8±12.2 years (79 males). All subjects underwent a complete physical examination, laboratory assessments, standard 12-lead electrocardiography and two-dimensional Doppler and three-dimensional STE, the results of these examinations were within the normal range. Increased basal LV rotation was associated with increased LV volume measured in end-systole and impaired LV ejection fraction. Increased apical LV rotation was associated with reduced LV volumes assessed in end-diastole and in end-systole and increased ejection fraction of the LV. Elevated basal LV rotation showed associations with increased LV mass. In case of increasing basal LV rotation, apical LV rotation showed a decreasing tendency and LV twist showed a tendency of increasing. Similarly, lower basal LV rotation and increased LV twist were seen with increasing apical LV rotation. Increasing LV end-diastolic volume was associated with increasing LV volume measured in end-systole and preserved ejection fraction of the LV. Increasing LV end-systolic volume was associated with increasing LV end-diastolic volume and reduction of LV ejection fraction. Increasing LV volumes were associated with increasing LV mass. While increased LV volumes were associated with reduced apical LV rotation and twist, basal LV rotation did not show significant changes. LV rotational mechanics are strongly associated with LV volumes in healthy adults suggesting its volume-dependence.

A QoS-Aware Energy-Efficient Chimp Optimization Routing Protocol with Efficient Sensor Node Deployment Strategy in Underwater Acoustic Sensor Network

As an extension of wireless sensor networks in the underwater environment, Underwater Acoustic Sensor Networks (UASNs) have led to a broad consideration of academicians. One of the problems that lower UWSN effectiveness in terms of network lifespan is premature energy depletion. It might be caused by the network nodes using different amounts of energy. In UASNs, the effectiveness and dependability of data transfer remain so adverse because of the intricate underwater environment in diverse ocean applications like surveilling atypical submarine oil pipelines. Inspired by the significance of UASNs’ quality of service in several implementations, this study proffers a metaheuristic optimization algorithm (AG) called Chimp Optimization-based Routing Protocol (CH-ORP) for UASNs obtaining intricate features of underwater (UW) medium into concern like 3D changing topology, high propagation delay, node mobility, and density, and, also, cluster head nodes’ rotation mechanism. Initially, the entire network (NW) paradigm has been considered as a three-dimensional cube out of a grid point of view, and the three-dimensional cube has been split into several little cubes by employing Delaunay Triangulation. The optimization has been carried out for lessening node failure rate and NW energy consumption rate by ideally placing the sensor nodes in UW acoustic communication. The NW topology’s steadiness has been assured by the AG, and this optimizes the node redeployment scheme by computing the fitness function for all nodes. The proffered AG’s simulation substantiations have been performed for exhibiting the CH-ORP’s efficiency that executes finer when compared to the advanced methodologies concerning energy efficiency, reliability, and end-to-end delay. It has been found that the proposed Ch-ORP achieves 698 packets received with 28% of energy consumption, 156-sec Network delay, 257 packet loss, 97.23% of PDR, and 1256 Mbps of Network throughput.

Epidemiology, Pathoanatomy and Clinicoradiologic Correlations of Quadrimalleolar Ankle Fractures: A Cross-Sectional Study

Category: Ankle; Trauma Introduction/Purpose: The term ‘quadrimalleolar fracture’ (QMF) describes a trimalleolar (TM) ankle fracture with an associated Chaput or Wagstaffe fracture. Optimal fixation of these injuries not only allows for bone-to-bone healing but also facilitates syndesmotic reduction. However, this is a relatively new concept, and the literature on QMFs is limited to a few case series. Hence, we conducted this study to determine the epidemiology, patterns, and clinicoradiologic correlations of QMFs. The primary objective of this study was to describe the prevalence and patterns of QMFs. The secondary objective was to determine if certain clinical or radiological parameters were associated with different types and patterns of QMFs. Methods: A retrospective analysis of ankle fractures presenting to three tertiary referral hospitals was undertaken. Adult patients (≥18 years) presenting with an acute, traumatic TM ankle fracture over 3 years (July 2018 to July 2021) were included. Isolated medial and lateral malleolar fractures, bimalleolar ankle fractures, pediatric patients, pilon fractures, pathological fractures, and those with delayed presentation or (≥3 weeks of injury) were excluded. Clinical demographic variables were obtained from the patients’ medical records. AP, lateral, and mortise ankle radiographs, and CT scans, (axial, coronal, and sagittal sections along with 3D volume reconstructed models) whenever available, were evaluated in detail. Demographics and radiological parameters were compared between TM and QMF, as well as between different types of QMFs. Odds ratios with 95% confidence intervals were determined to test the strength of association. Results: A total of 876 adult patients with ankle fractures were included after the screening, of which 323 had a TM ankle fracture for which a CT scan had been performed. A total of 159 AITFL avulsions were identified, yielding a prevalence of 18.2% amongst all ankle fractures and 26.1% in ankle fractures where a CT scan had been performed. TMFs had the significantly highest proportion of CT-confirmed AITFL avulsions (44.4%) in comparison to unimalleolar (4.4%) and bimalleolar fractures (6.4%) (P < 0.0001). Age and osteoporosis were significant associations of QMFs. Avulsion of the medial malleolus, Weber B fibular fracture, and supination external rotation mechanism were significantly associated with Wagstaffe fractures. Size of the Chaput fracture was inversely related to that of the posterior malleolar fracture. Conclusion: Quadrimalleolar ankle fractures account for a significant proportion of ankle fractures. The strengths of this study include a large sample size, which was derived from three different hospitals, consecutive inclusion (or exclusion) of cases, strict adherence to the STROBE guidelines, and the fact that only CT-confirmed cases were used to determine clinic-radiological associations. Wagstaffe and Chaput fractures have distinct clinical and radiological correlations. However, further research is needed to determine the optimal fixation protocols for these injuries.

Dynamic hysteretic properties and specific loss power of magnetic nanoparticles in a viscous medium at different thermal baths

A system of magnetite single-domain magnetic nanoparticles in an aqueous colloidal suspension at different temperatures is simulated. In this framework, we study the response of the magnetization of the system to the presence of a time-dependent magnetic field at certain frequency. To do that, a Hamiltonian that includes the Zeeman interaction and the uniaxial magneto-crystalline anisotropy energy is considered. The dynamics of the system is driven according to the solution of the stochastic Landau–Lifshitz–Gilbert differential equation, in combination with a torque term acting on the nanoparticle in order to consider the Brown rotation influenced by the viscosity of the solvent. Thus, both Néel and Brown rotation mechanisms are contemplated. Our results allow us to conclude that Brownian relaxation mediates the alignment of the anisotropy axes with the external field. Thus, depending on the solid or liquid state of the solvent, it is possible to determine the conditions under which a reinforcement of the magnetic anisotropy can take place in order to increase the remanence and squareness of the hysteresis loops.

Double Dust Structures in Different Stratum Phases in Moderate Magnetic Fields

Three-dimensional plasma-dust formations consisting of calibrated dust particles differing in sizes and material densities are studied. The characteristic features of the structures formation in stratified glow discharge were studied, as well as their shapes and dynamics in the external magnetic fields. From several types of powders, the spatially separated double structures were obtained, which filled the dust trap, being located in different stratum phases. For each part of the structure, the average rotational velocities were obtained as functions of the magnetic field. In the range, in which the rotation mechanism depends on the particle size and the ion drag force is dominant, the rotational velocity was numerically estimated with allowance for the parameters variation along the stratum.

Detector of UV light chirality based on a diamond metasurface.

Circularly polarized light (CPL) finds diverse applications in fields such as quantum communications, quantum computing, circular dichroism (CD) spectroscopy, polarization imaging, and sensing. However, conventional techniques for detecting CPL face challenges related to equipment miniaturization, system integration, and high-speed operation. In this study, we propose a novel design that addresses these limitations by employing a quarter waveplate constructed from a diamond metasurface, in combination with a linear polarizer crafted from metallic aluminum. The diamond array, with specific dimensions (a = 84 nm, b = 52 nm), effectively transforms left-handed and right-handed circularly polarized light into two orthogonally linearly polarized beams who have a polarization degree of approximately 0.9. The aluminum linear polarizer then selectively permits the transmission of these transformed linearly polarized beams.Our proposed design showcases remarkable circular dichroism performance at a wavelength of 280 nm, concurrently maintaining high transmittance and achieving a substantial extinction ratio of 25. Notably, the design attains an ultraviolet wavelength transmission efficiency surpassing 80%. Moreover, our design incorporates a rotation mechanism that enables the differentiation of linearly polarized light and singly circularly polarized light. In essence, this innovative design introduces a fresh paradigm for ultraviolet circularly polarized light detection, offering invaluable insights and references for applications in polarization detection, imaging, biomedical diagnostics, and circular dichroic spectroscopy.

Energy-Efficient Improved Optimal K-Means: Dynamic Cluster Head Selection based on Delaying the First Node Death in MWSN-IoT

The Internet of Things (IoT), which attaches dynamic devices that can access the Internet to create a smart environment, is a tempting research area. IoT-based mobile wireless sensor networks (WSN-IoT) are one of the major databases from which the IoT collects data for analysis and interpretation. However, one of the critical constraints is network lifetime. Routing-based clustered protocols and cluster head (CH) selection are crucial in load balancing and sensor longevity. Yet, with clustering, sensor node mobility requires more overhead because the nodes close to the center may get far and thus become unsuitable to be a CH, whereas those far from the center may get close and become good CH candidates, influencing energy consumption. This paper suggests an energy-efficient clustering protocol with a dynamic cluster head selection considering the distance to the cluster center, remaining energy, and each node's mobility degree implementing a rotation mechanism that allows cluster members to be equally elected while prioritizing those with the minimum weight. The advised algorithm aims to delay the first node death (FND) and thus prolong the stability period and minimize energy consumption by avoiding re-clustering. The performance of the proposed protocol exceeds that achieved in our previous work, Improved OKmeans, by 11%, in first dead node lifetime maximization, 43% in throughput, and 44% in energy efficiency.

Simultaneous chiral polarization and edge enhancement imaging enabled by a single geometric-phase-based element.

In this Letter, we propose a multifunctional imaging system enabled by a single geometric-phase-based liquid crystal (LC) element, which integrates chiral polarization and edge enhancement imaging. The element is located at the frequency domain plane in a 4F imaging system, and the phase profile of the element consists of a fork grating in the x direction and a grating in the y direction, which provide edge enhancement and chiral polarization imaging capabilities. Benefiting from the tunable property of the LC, the system can be switched from a polarization and edge imaging mode to the normal conventional imaging mode which is capable of conveniently acquiring the needed image information. Experiments demonstrate that the system can easily achieve multifunctional and switchable imaging, which agrees well with our design, and our LC element can work in the broadband spectrum because of the geometric phase modulation. The multifunctional strategy used here can effectively avoid the need to increase the size of the original microscopic system and the need for additional mechanical rotation of components. We believe that the proposed system with the additional advantages of electric control and tunability can find applications in biological imaging, medical detection, and optical computing.

An Improved Approach of Classical Upper Bound Theory for Stability Analysis of Layered Slopes

The equations for the critical height of layered slope were derived by a related researcher, but they lack details and do not agree with the method of limit equilibrium. So this topic was reinvestigated. Considering the possible global or local failure modes of the layered slope, the equations for the critical height of the above modes are derived based on the upper limit theorem by using rotational failure mechanisms or rotational and translational failure mechanisms. Based on the above theory, the stability coefficients of layered slope are investigated. The results show that the presented upper bound approach has better performance than other methods mentioned in the literature and is consistent with the limit equilibrium method. In combination with the strength reduction method, the global and local stability of the layered slope are analyzed using the several examples. The high-calculation accuracy of presented method and the specific measures to improve the smoothness of the sliding surface are reviewed. From the perspective of the combination of sliding surfaces, the dimensionless parameter vector of the layered slope is introduced. The possible limitations of the upper bound limit approach with log spirals are pointed out and the conditions which must be fulfilled in order to achieve a higher computational accuracy are mentioned.

Inverse reliability analysis and design for tunnel face stability considering soil spatial variability

The traditional deterministic analysis for tunnel face stability neglects the uncertainties of geotechnical parameters, while the simplified reliability analysis which models the potential uncertainties by means of random variables usually fails to account for soil spatial variability. To overcome these limitations, this study proposes an efficient framework for conducting reliability analysis and reliability-based design (RBD) of tunnel face stability in spatially variable soil strata. The three-dimensional (3D) rotational failure mechanism of the tunnel face is extended to account for the soil spatial variability, and a probabilistic framework is established by coupling the extended mechanism with the improved Hasofer-Lind-Rackwits-Fiessler recursive algorithm (iHLRF) as well as its inverse analysis formulation. The proposed framework allows for rapid and precise reliability analysis and RBD of tunnel face stability. To demonstrate the feasibility and efficacy of the proposed framework, an illustrative case of tunnelling in frictional soils is presented, where the soil's cohesion and friction angle are modelled as two anisotropic cross-correlated lognormal random fields. The results show that the proposed method can accurately estimate the failure probability (or reliability index) regarding the tunnel face stability and can efficiently determine the required supporting pressure for a target reliability index with soil spatial variability being taken into account. Furthermore, this study reveals the impact of various factors on the support pressure, including coefficient of variation, cross-correlation between cohesion and friction angle, as well as autocorrelation distance of spatially variable soil strata. The results also demonstrate the feasibility of using the forward and/or inverse first-order reliability method (FORM) in high-dimensional stochastic problems. It is hoped that this study may provide a practical and reliable framework for determining the stability of tunnels in complex soil strata.

Development and Calibration of a Vertical High-Speed Mueller Matrix Ellipsometer

In order to meet the requirements of dynamic monitoring from a bird’s eye view for typical rapidly changing processes such as mechanical rotation and photoresist exposure reaction, we propose a vertical high-speed Mueller matrix ellipsometer that consists of a polarization state generator (PSG) based on the time-domain polarization modulation and a polarization state analyzer (PSA) based on division-of-amplitude polarization demodulation. The PSG is realized using two cascaded photoelastic modulators, while the PSA is realized using a six-channel Stokes polarimeter. On this basis, the polarization effect introduced by switching the optical-path layout of the instrument from the horizontal transmission to the vertical transmission is fully considered, which is caused by changing the incidence plane. An in situ calibration method based on the correct definition of the polarization modulation and demodulation reference plane has been proposed, enabling the precise calibration of the instrument by combining it with a time-domain light intensity fitting algorithm. The measurement experiments of SiO2 films and an air medium prove the accuracy and feasibility of the proposed calibration method. After the precise calibration, the instrument can exhibit excellent measurement performance in the range of incident angles from 45° to 90°, in which the measurement time resolution is maintained at the order of 10 μs, the measurement accuracy of Mueller matrix elements is better than 0.007, and the measurement precision is better than 0.005.