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To study ellipsoidal and spherical particle flow, clogging behavior and unclogging dynamics, a series of numerical simulations were carried out using our validated 3-D coupled computational fluid dynamics–discrete element method (CFD–DEM) model. For the first time, the strength of clogging arches is assessed in terms of fluid pressure gradient, which can effectively break up the clog. The main findings are as follows. In a clogged assembly, only when the flushing fluid reaches the unclogging pressure gradient, the ellipsoidal and spherical particles can flow in a continuous state. For the ellipsoids and spheres with the same equivalent volume, the unclogging pressure gradient of an ellipsoidal assembly is 11.8 times higher than that of a spherical assembly. Clogging arches at the outlet show the highest strength when the longitudinal orientations of the ellipsoids are perpendicular to the outlet plane. In contrast, the formed arch has the lowest stability when the longitudinal orientations of the ellipsoids are in the same direction as the long side of the outlet, as shown in the graphical abstract. The unclogging pressure gradient of the former case is 1.9 times greater than that of the latter case. The granular arches observed in our 3-D model are categorized as complex 3-D backbone arches. In the flowing region, particles rotate nearly perpendicular to the outlet plane, especially those approaching the outlet. Moreover, triangular stagnant zones are formed on both sides of the bottom of the rectangular box. The model presented here offers a great promise for future investigation of various granular systems at the particle scale.

In this paper, a two-dimensional wireless displacement sensor with high sensitivity composed of a bilayer graphene-based frequency selective surface (FSS) is proposed. The lengths of the strip-type resonators on the top and bottom layers of the FSS are different and perpendicular to each other. Based on the resonance and polarization characteristics of the FSS, two-dimensional displacement sensing can be realized. It is well validated both in simulation and experiment that the direction of the displacement can be distinguished by the variation trend of the resonant frequencies of the top and bottom layers. In experiment, the measured results of the FSS based wireless displacement sensor in the dynamic range of 5mm show high sensitivity of 280 MHz/mm in x direction and 370 MHz/mm in y direction. Moreover, the excellent mechanical and chemical stability of the multi-layer graphene also makes it suitable for harsh environments, showing good prospects in application.

In this study, experiments and numerical simulations are performed where a hollow particle with a uniaxial through–hole is dropped freely in water, and its behavior is investigated. The distribution of falling particle trajectories reveals significant deviation in the direction perpendicular to the through–hole of the particle. In addition, the pressure distribution at the particle surface and the vorticity field of the wake of the particle are distributed asymmetrically in the plane perpendicular to the through–hole of the particle. Conversely, this pressure distribution and vorticity field are distributed symmetrically with respect to the direction parallel to the through–hole of the particle. Thus, this study clarifies that the movement of the particle in the direction parallel to the through–hole is suppressed. These results provide valuable novel insights into the control of particle motion.

A new method for the approximation of the root canal's cross-sectional shape and its working width using cone-beam computed tomographic (CBCT) or micro-computed tomographic (micro-CT) imaging was introduced.Scanned data from 29 extracted human mandibular first and second molar distal root canals without instrumentation were reconstructed and analyzed with a self-developed measurement algorithm. The 3-dimensional volume models were sliced perpendicular to the vertical axis. Using different 2-dimensional parametric models, the contour of each root canal slice was approximated and used to determine the canal's cross-sectional dimensions. The measurements of minor width, major width, and the root canal's conicity were statistically analyzed using analysis of variance.The measured minor and major widths of the investigated root canals were significantly higher (probability value P.05) when evaluated by CBCT images than the results obtained from micro-CT data. Both dimensions increased starting from the apical foramen (P.01). The narrowest measured canal widths were 0.19-0.24 mm for CBCT imaging and 0.09-0.21 mm for micro-CT imaging in the apical part. The maximum values for conicity were between 13% and 17% in the cervical third.The 3-dimensional imaging data from CBCT and micro-CT imaging enabled a valuable anatomic assessment of the root canal's cross-sectional working width along the canal up to the physiological foramen in order to determine an adequate apical diameter as well as the correct measured taper in the cervical and medial part.

To explore the reinforcement effects of different reinforcement methods, kraft paper was used as reinforcement material, and shear tests were carried out in sand to study the reinforcement effects of kraft paper perpendicular and parallel to the shear plane. The test results show that the two reinforcement methods can effectively improve the strength of sand and the orthogonal reinforcement form is more superior. The existence of reinforced materials greatly improves the cohesion of sand, but does not significantly improve the internal friction angle. The width of reinforcement material has little effect on the reinforcement effect and shows different variation laws under different reinforcement forms.

The current paper deals with the problem of the simply supported thin rectangular plate subjected to the intermediate strip in-plane loading. Based on the strain energy method (Fourier ansatz), the critical (minimum value) of buckling stress occurrence was determined in a general form dependent only on the strip thickness, strip location, plate width and stress magnitude. Compatible with the classical columns Euler method it was found that the plate stability is decreased with the increasing of the plate width due to larger induced stresses. Also, strip location relative to the support region was found to influence the buckling (same analogy to the Euler buckling theory; consider the strip as a both sides pressed rod). Additionally, the strip width parameter increase is likely to cause larger buckling stress. Moreover, expressions that includes both axial and transverse loads for different extended cases configurations were also derived and examined based on the strain energy method alongside explanation for possible applications (thin aluminum plate welding). In a general view, it was found that the cases of combined axial and perpendicular loading action are less stabilized than cases where only one kind of loading configuration is participated. Finally, the buckling stress was found to agree qualitatively with the cited literature.

Purpose This study aimed to develop a method for the determination of the source‐to‐surface distance (SSD), the X‐ray beam area in a plane perpendicular to the beam axis at the entrance skin surface (Ap ), and the X‐ray beam area on the actual skin surface (As ) during percutaneous coronary intervention (PCI). Materials and Methods Male and female anthropomorphic phantoms were scanned on a computed tomography scanner, and the data were transferred to a commercially available computer‐aided design (CAD) software. A cardiovascular angiography system with a 200 × 200 mm flat‐panel detector with a field‐of‐view of 175 × 175 mm was modeled with the CAD software. Both phantoms were independently placed on 40 mm thick pads, and the examination tabletop at the patient entrance reference point. Upon panning, the heart center was aligned to the central beam axis. The SSD, Ap , and As were determined with the measurement tool and Boolean intersection operations at 10 gantry angulations. Results The means and standard deviations of the SSD, Ap , and As for the male and female phantoms were 573 ± 15 and 580 ± 15 mm, 8799 ± 1009 and 9661 ± 1152 mm2, 10495 ± 602 and 11913 ± 600 mm2, respectively. The number of As overlaps for the male and female phantoms were 15/45 and 21/45 view combinations, respectively. Conclusions CAD‐based X‐ray beam modeling is useful for the determination of the SSD, Ap , and As . Furthermore, the knowledge of the As distribution helps to reduce the As overlap in PCI.

The main purpose of this study was to identify how the accuracy of the tibial rotation reference axes varied in populations with different tibial tubercle locations. We hypothesized that the accuracy of the axes of tibial rotation would be affected by the changes of tibial tubercle locations. Surgical epicondylar axis (SEA), medial third of the patellar tendon (1/3MPT), medial third of the tibial tuberosity (1/3MTT), medial border of the tibial tuberosity (MTT) and Akagi line were drawn. The angle between SEA and horizontal line with the angle between the four tibial rotation axes and the horizontal line was compared by T test. Then, the correlation between TTTG with the angles between the four axes and SEA vertical lines was analyzed. The TTTG was divided into three subgroups (TTTG

This paper presents a position sensor based on a novel configuration of linear variable differential transformer. Design and optimization of the position sensor using finite element method are presented. The measurements are also conducted to validate experimentally the sensor performance. The sensor has short air core coils and long magnetic armatures. The axis of the rectangular excitation coil and two antiserially connected rectangular pick up coils is perpendicular to the motion direction of the position sensor. The coils are located between two parallel silicon steel laminations serving as the armatures. The position sensor is optimized with compromise between minimization of nonlinearity error and maximum sensitivity. The main advantage of the proposed position sensor is the small ratio of coils dimensions to the working range. The position sensor is operated for excitation frequencies of 500 Hz, 1000 Hz, and 2000 Hz. The maximum nonlinearity error is less than 1.5% for the theoretical results and it is less than 2% for the measured results in ±90 mm position range.

The growth characteristic of primary faceted Al2Cu intermetallic compounds (IMCs) during solidification was observed directly by synchrotron radiography. The formation and transition mechanisms of Al2Cu IMCs with diverse morphologies were elucidated by first-principle calculations combined with electron backscatter diffraction analysis. The Al2Cu crystals preferred to grow along the [001] direction and were bounded by {110} planes with the lowest surface energy. The faceted Al2Cu rod-like clusters consisted of multiple crystals with complete rod, hollowness and partial sides, which was attributed to the increase in strain energy and solute redistribution during solidification. The faceted Al2Cu with branches was characteristic with the perpendicular relationship between the main branches and side steps and partial coalescence at the junction, which was ascribed to the continuous propagation and growth of newly formed crystals along the diagonal direction.

Nanoindentation pop-ins in composite source shale were characterized as Type I and Type II, where the slopes on load–displacement (p–h) curves are defined as Δp/Δh = 0 or Δp/Δh > 0, respectively. Type I were associated with sudden instantaneous failure as elastic perfectly plastic “Coulomb-type” and sudden grain dislodging, while Type II were related to shear band progressive failure and/or grain sliding or progressive pile-up. Pop-ins were primarily observed when indenting perpendicular to the shale layers. Estimating magnitudes of pop-in energy dissipation varied widely with shale matrix phases. Meanwhile, Type III pop-ins defined by Δp/Δh

Effects of annealing condition and crack orientation on fatigue crack propagation (FCP) behavior of DED (direct energy deposition)-processed Ti–6Al–4V (Ti64) specimens were studied. It was found that the FCP resistance of Ti64 increased significantly with annealing, particularly above β transus temperature, due to the microstructural coarsening inducing less damage accumulation at the tip of crack. The FCP behavior of as-built and as-annealed DED Ti64 specimens was isotropic with crack direction either parallel or perpendicular to building direction. The detailed micrographic and fractographic analyses on FCP-tested specimens suggested that the presence of largely elongated β grain boundaries did not affect the advance of crack.

In this communication, a leaky-wave antenna (LWA) featuring beam scanning from backfire direction is investigated. The presented LWA is designed based on the odd-mode spoof surface plasmon polariton (SSPP) waveguide that consists of a row of complementary “cross-shaped” units. The odd-mode SSPP is excited by a convertor from the microstrip line to the slotline. As opposed to the even mode, the equivalent electric current of the odd-mode SSPP is perpendicularly distributed to the longitudinal direction, providing a complete backfire radiation component. Then a general method to design a sinusoidally modulated reactance surface (SMRS) LWA is introduced to efficiently generate backfire radiation at desired frequency and the depth of each SSPP unit is determined by calculation. By this way, the optimized working of the LWA will be drastically reduced. A prototype of the presented LWA is simulated, fabricated, and measured. Simulation and experimental results show that the main beam of the presented LWA scans from backfire at desired frequency of 20 GHz to the broadside direction at 27.5 GHz. And the antenna shows bidirectional radiation feature.

Silicon nitride (Si3N4) ceramics with Al2O3, MgO and Y2O3 as sintering additives were fabricated via hot-pressing sintering and gas pressure sintering, respectively, focusing on the texture and fracture toughness. The hardness and fracture toughness on the plane perpendicular and parallel to the hot-pressing direction were different in the hot-pressing sintered samples, and similar values were obtained in the gas pressure sintering. The orientation distribution function (ODF) analyses via X-ray diffraction measurements revealed the presence of 11 2 ¯ 0 〈 0001 〉 type texture in the hot-pressing sintered samples. This suggested that the 0001 planes of most rod-shaped β-Si3N4 grains were oriented in the hot-pressing direction or their c-axes were oriented towards the radial directions of the sintered cylinder-shaped samples. The presence of such a β-Si3N4 grain texture led to the anisotropy in fracture toughness, with its values changing from 9.3–11.3 MPa m1/2 with increasing indentation angles on the plane parallel to the hot-pressing direction.

In general, pulsed lasers with high peak power have been used for the micro-groove formation. However, the processing speed is limited by the pulse repetition rate. On the other hand, CW laser can be expected to perform the high-speed processing by continuous energy input. The mechanism of micro-groove formation by CW laser was investigated by high-speed observation and the thermal fluid analysis. In the perpendicular irradiation of CW laser, the molten metal flows symmetrically around the keyhole to the backward direction, and micro-grooves remain at both edges of molten region. In contrast, in the angled irradiation, the molten metal at the reflection-side scatters as spatters. The remained molten metal flows from the reflection-side to the incident-side through the bottom of keyhole, since the recoil pressure is generated from the reflection-side to the incident-side. In addition, high-speed scanning contributes to keeping the sufficient time and force to move the molten metal in the backward direction. Then, the micro-groove remains at the reflection-side, while the upheaval is formed at the incident-side by gathering the molten metal from the reflection-side and the front of keyhole. Asymmetrical behavior of molten metal flow in angled irradiation of CW laser can create micro-groove in the reflection-side.

Pristine carbon nanotubes (CNTs) and functionalized carbon nanotubes (f-CNTs) were introduced into conductive poly(methyl methacrylate)/graphene nanoplatelet (PMMA/GNP) composites to achieve a synergistic effect in the enhancement of the conductivity and the reduction in the percolation threshold by forming a 3-Dimensional(3-D) hybrid structure. Both the in-plane and perpendicular electrical properties were investigated. The synergies of hybrid fillers in the in-plane direction were more dependent on the total filler loading, while those in the perpendicular direction were significantly influenced by the GNP/CNT or GNP/f-CNT ratios. Typically, a schematic diagram of the evolution of the 3-D conductive pathways of PMMA/GNP/f-CNT composite at different GNP/f-CNT ratios was presented to explain this phenomenon. Moreover, tunable conductivity anisotropy (defined as the ratio of in-plane conductivity to perpendicular conductivity) ranging from 0.01 to 1000 was achieved, simply by constructing different conductive structures at various filler loadings or ratios in composites. Graphical abstract The synergistic effect of GNPs and f-CNTs varies with the microstructural conductive network evolution at different filler ratios.

Conformations of wormlike chains in cylindrical pores with attractive walls are explored for varying pore radius and strength of the attractive wall potential by molecular dynamics simulations of a coarse-grained model. Local quantities such as the fraction of monomeric units bound to the surface and the bond-orientational order parameter as well as the radial density distribution are studied, as well as the global chain extensions parallel to the cylinder axis and perpendicular to the cylinder surface. A nonmonotonic convergence of these properties to their counterparts for adsorption on a planar substrate is observed due to the conflict between pore surface curvature and chain stiffness. Also the interpretation of partially adsorbed chains in terms of trains, loops, and tails is discussed.

The added mass of a group of circular sections in a confined fluid has been studied in many references. This note revisits this problem and aims to reveal some essential results that have not been well studied previously but indicate a general conclusion of the added mass coefficients. The sum of the added mass coefficients of one section caused by all boundaries’ motions along the same direction is equal to the constant value $$-1$$ ; however, the sum of the coefficients perpendicular to the motion direction is the constant value 0. Given this conclusion, this present study extends the previous models to a group of arbitrary sections in a confined fluid for a more general analysis. The conclusion mentioned above is still available for the present modeling and shows generality. According to the principle of superposition, this paper gives concise and strict proof of this conclusion. This general conclusion of fluid added mass can serve as an essential reference for other studies of such a problem.

Panel paintings—complex multi-layer structures consisting of wood support and a paint layer composed of a preparatory layer of gesso, paints, and varnishes—are among the category of cultural objects most vulnerable to relative humidity fluctuations and frequently found in museum collections. The current environmental specifications in museums have been derived using the criterion of crack initiation in an undamaged, usually new gesso layer laid on wood. In reality, historical paintings exhibit complex crack patterns called craquelures. The present paper analyses the structural response of a paint layer with a virtual network of rectangular cracks under environmental loadings using a three-dimensional model of a panel painting. Two modes of loading are considered—one induced by one-dimensional moisture response of wood support, termed the tangential loading, and the other isotropic induced by drying shrinkage of the gesso layer. The superposition of the two modes is also analysed. The modelling showed that minimum distances between cracks parallel to the wood grain depended on the gesso stiffness under the tangential loading. Despite a nonzero Poisson’s ratio, gesso cracks perpendicular to the wood grain could not be generated by the moisture response of the wood support. The isotropic drying shrinkage of gesso produced cracks that were almost evenly spaced in both directions. The modelling results were cross-checked with crack patterns obtained on a mock-up of a panel painting exposed to several extreme environmental variations in an environmental chamber.

A novel and effective method is proposed to determine the temperature and thermal stresses in the case of a finite Griffith crack lying perpendicular to the surface of an isotropic half-plane under...

Press-brake bending is one of the important sheet metal forming processes widely used to fabricate different angles and channels in automotive applications. Plastic deformation of material during bending generates elastic stress waves known as acoustic emission (AE), enabling online monitoring of the bending process. The analysis of these stress waves helps in process characterization and aids in the identification of defects. The non-homogeneous plastic deformation that occurs during bending leads to the development of residual stress (RS) in the bend regions after forming. The locked-in residual stresses that remain after bending are measured using the x-ray diffraction method. The present study aims to use the AE technique for online bend monitoring of austenitic stainless steel (SS) of type 304L and correlate the AE parameters acquired during bending with the final locked-in RS present in the bend regions. Toward this, SS 304L sheets were bent to various bend angles, viz. 45°, 60°, 90°, 108°, 120°, and 135°, along the rolling direction and perpendicular to the rolling direction. Among the many AE parameters derived from the analysis of AE signals, it is shown that normalized cumulative counts and energy increase with bend angle. The increase in AE is well correlated with the RS that develops due to plastic deformation. The observed correlations between AE parameters acquired during bending and RS measured after bending are discussed.

In high-temperature rock engineering projects, rocks are subjected to external loads. Studying the cracking behavior of thermally damaged rock under uniaxial loading is of great significance to engineering. In the present study, real-time computed tomography (CT) scanning was performed on thermally damaged granite subjected to compression loading to observe the evolution of spatial three-dimensional (3D) microcracks and planar two-dimensional (2D) microcracks. The porosity and crack length were further introduced to quantify microcracking behavior. The effects of the load on the 3D microcrack volume distribution and the length of 2D microcracks with different orientations were discussed. The results show that real-time CT imaging intuitively presents the evolutionary process of realistic microcrack morphology during loading. As the load level increases, the porosity of the specimen and the total length of 2D microcracks experience stages of slow decrease, slow increase, and rapid increase. The proportion of microcracks with larger volumes decreases and then increases as the load level increases. In the slice parallel to the loading direction, the length of microcracks within an angle range of 30°–90° to the loading direction decreases as the load level increases. In the slice perpendicular to the loading direction, the microcrack length distribution exhibits obvious anisotropy as the load level increases.

At present, the mechanical properties of laterally loaded threaded fasteners with large diameters embedded in timber elements remain unknown. An experimental study of laterally loaded threaded rods with wood screw threads embedded perpendicular to grain in softwood elements (spruce and pine glulam and spruce LVL) is presented in this paper. Embedment tests with the load acting parallel and perpendicular to grain were carried out and the embedment strength and stiffness were quantified. For some test series, the experimental embedment strengths were lower compared to the predictions according to Eurocode 5 in terms of both mean and characteristic values. This finding indicates that the predictions by Eurocode 5 are not always conservative. To investigate the effect of the thread, additional series of embedment tests were carried out with smooth dowels featuring a diameter approximately equal to the core diameter of the threaded rods. Finally, the yielding moment of threaded rods was quantified based on a series of three-point bending tests of threaded rods. The experimentally determined yielding moment was significantly higher than the prediction of Eurocode 5.

Author(s): Han, HS; Lee, S; Je, SG; Kang, M; Ok, HJ; Kim, N; Chao, W; Im, MY; Lee, KS | Abstract: Stochasticity in magnetic nanodevices is an essential characteristic for harnessing these devices to computing based on population coding or the building blocks of probabilistic computing, p-bits. A magnetic tunneling junction (MTJ) consisting of a patterned magnetic element is considered a promising computing unit in the concept of artificial neurons and p-bits. A comprehensive understanding of the stochasticity in the switching of patterned magnetic elements is crucial for realizing MTJ-based probabilistic computing technology. In the present work, the stochastic behavior in the switching process of a perpendicularly magnetized Co/Pt disk within an array was directly observed utilizing full-field soft X-ray microscopy. Within 50 repeated hysteretic cycles, the stochastic magnetization switching of individual Co/Pt disks within disk arrays is identified. We found that the stochasticity in the magnetization switching of disks considerably depends on the disk size. The stochasticity initially decreases as the disk radius gets bigger from 125 to 375 nm (region I), then increases with further enlarging the disk size to 625 nm (region II). The variance of thermal fluctuation relevant to the disk size and the multilevel switching within a disk are severely involved in the observed size-dependent stochasticity. This work provides the way for controlling the stochasticity in the switching of nanopatterned elements, which is a key aspect of MTJ-based probabilistic computing.

As the first step to study the fatigue crack propagation, the molecular simulations were performed to investigate the opening, propagation and closure behaviors of intragranular and intergranular cracks in nanocrystalline Ni under single-cycle mode I loading. The atomic crack angle was proposed to characterize the crack-tip blunting and sharpening quantitatively. There are obvious different mechanisms between intragranular and intergranular crack propagation. Intragranular crack propagation could be induced by stacking faults and can change its direction very easily, but the intergranular crack perpendicular to the loading direction would propagate along the grain boundary and encounter strong resistance at the triple junction. New cracks could form in the grain boundaries ahead of the original crack. Different from the traditional understanding for intragranular and intergranular cracks, however, the dislocation density increases even in the unloading process and the crack tip is possibly sharpened temporarily during loading.

A tunnel crack along the interface of two coupled one-dimensional piezoelectric quasicrystalline half-spaces is considered. Conductive electrical conditions on the cracks are investigated. It is believed that the arrangement of atoms is periodic in the plane perpendicular to the crack front and it is quasi-periodic in the direction co-directed with the front, and the last axis coincides with the direction of materials polarization. Uniformly distributed antiplane phonon and phason shear stresses and the electric field in the plane perpendicular to the crack front are given at infinity. Matrix-vector representations for phonon and phason stresses and electric field, as well as for the derivatives of phonon and phason displacements jumps and electric displacement are constructed. In these representations the mentioned values are expressed through the vector function holomorphic in the whole complex plane, except of the crack region. Satisfying with the use of these representations the conditions on the crack faces, the Riemann-Hilbert problem of linear relationship with the corresponding conditions at infinity is formulated and the analytical solution of this problem is constructed. Analyzing this solution, we obtain analytical expressions for phonon and phonon stresses and displacements jumps along the materials interface. It is shown that the obtained solution has an oscillating square root singularity near the crack vertices. It is important that this singularity does not lead to mutual penetration of the crack faces as in the plane case. In addition, the oscillation regions are very small, so the resulting solutions are acceptable for practical use. Numerical analysis was performed for a combination of different quasicrystalline compounds. The results are obtained along the material interface for the phonon and phason components of the stress-strain state and are presented in graphical form. Conclusions are made regarding the variation of phonon and phason characteristics at the material interface depending on external loads and geometric factors.

The magnetotactic yet uncultured species 'Candidatus Magnetoglobus multicellularis' is a spherical, multicellular ensemble of bacterial cells able to align along magnetic field lines while swimming propelled by flagella. Magnetotaxis is due to intracytoplasmic, membrane-bound magnetic crystals called magnetosomes. The net magnetic moment of magnetosomes interacts with local magnetic fields, imparting the whole microorganism a torque. Previous works investigated 'Ca. M. multicellularis' behavior when free swimming in water; however, they occur in sediments where bumping into solid particles must be routine. In this work, we investigate the swimming trajectories of 'Ca. M. multicellularis' close to solid boundaries using video microscopy. We applied magnetic fields 0.25-8.0 mT parallel to the optical axis of a light microscope, such that microorganisms were driven upwards towards a coverslip. Because their swimming trajectories approach cylindrical helixes, circular profiles would be expected. Nevertheless, at fields 0.25-1.1 mT, most trajectory projections were roughly sinusoidal, and net movements were approximately perpendicular to applied magnetic fields. Closed loops appeared in some trajectory projections at 1.1 mT, which could indicate a transition to the loopy profiles observed at magnetic fields ≥ 2.15 mT. The behavior of 'Ca. M. multicellularis' near natural magnetic grains showed that they were temporarily trapped by the particle's magnetic field but could reverse the direction of movement to flee away. Our results show that interactions of 'Ca. M. multicellularis with solid boundaries and magnetic grains are complex and possibly involve mechano-taxis.

The differential phase computed tomography (DP-CT) imaging is a kind of X-ray-phase-based CT methods, which is widely used in various X-ray imaging laboratories. At present, a collection of projections with the horizontal direction (perpendicular to the sample rotation axis) DP information is often acquired in DP-CT. In an ideal experiment, if the background is zero, then we can accurately reconstruct the information of each direction of the sample with horizontal data only. Actually, background information will produce streaking artifacts to affect the resolution in directions other than the horizontal direction. To mitigate the streaking artifacts in the conventionally reconstructed DP-CT images. This study develops a novel analytical DP-CT reconstruction framework by jointly using the bilateral DP information obtained along two perpendicular directions. In addition, a new data acquisition scheme is also proposed to quickly acquire the bilateral DP signal without the need of changing the direction of refraction signal acquisition. Experimental results demonstrate that this new algorithm is able to greatly reduce the streaking artifacts on DP-CT images.

—Acoustic transmission data obtained in the laboratory experiment are used to identify stages of hydraulic fracture initiation, growth, and filling with a fracturing fluid. The laboratory setup allows for performing experiments with porous saturated samples made of artificial materials, with a diameter of 430 mm and height 70 mm. The model material was a mixture of gypsum and cement; the sample was saturated with water solution of gypsum and loaded by vertical and two independent horizontal stresses. Fracture was created by constant-rate injection of a viscous fluid through a cased hole in the center of the sample. Hydraulic fracture (HF) was monitored using ultrasonic pulses transmitted through the sample. The comparison of amplitude variations of ultrasonic pulses and injection pressure indicates that HF crack propagation initiates at lower pressure than maximum; HF crack grows faster than is filled with a fluid; after the crack volume is filled up with a fluid, fracture aperture expands. Once the injection stops, the crack closes when pressure in the wellbore decreases due to fluid leakage into the sample. It is shown that if the principal compressive stresses reorient, a secondary hydraulic fracture can appear provided that the primary fracture is perpendicular and secondary parallel to the well axis.

Purpose X‐ray imaging devices contain a collimator system that defines a rectangular irradiation field on the detector plane. The size and position of the X‐ray field, and its congruence with the corresponding light field, must be regularly tested for quality control. We propose a new method to estimate how far the x‐ray field extends beyond the detector which does not require the use of external detectors. Methods A metallic foil is inserted perpendicularly between the source and the detector. A slit camera, a linear extension of a pinhole camera, is used to project onto the detector the fluorescence X‐rays emitted by the irradiated foil. The location where the fluorescence signal inside the camera vanishes is used to extrapolate the location of the field boundary. Monte Carlo simulations were performed to determine the optimal composition and thickness of the foil. A prototype camera with a 1‐mm‐wide slit was built and tested in a clinical mammography and digital breast tomosynthesis (DBT) system. Results The simulations estimated that a foil made of 25 µm of Molybdenum provided the maximum signal inside the camera for a 39 kVp beam. The boundary of the X‐ray fields in mammography and DBT views were experimentally measured. With the camera along the chest wall side, the measured field in multiple DBT views had a variability of only 0.4 ± 0.1 mm compared to mammography. A difference in the measured boundary position of 2.4 and –1.0 mm was observed when comparing to measurements with a fluorescent ruler and self‐developing film. Conclusion The introduced technique provides a practical alternative method to detect the boundary of an X‐ray field. The method can be combined with other testing methods to assess the congruence of the X‐rays and light fields, and to determine if the X‐ray field extends beyond the detector more than permitted.

The aim of the study was to test a novel planning method for simultaneous midfoot and hindfoot deformity correction, based on reference lines and angles (RLA) of the talus, calcaneus and first metatarsal in 64 normal radiographs from 55 patients. Talus Joint Line (TJL), from the border of the articular surface of the talus and the posterior process of talus, and mechanical axis of the first metatarsal form the mechanical Lateral Talometatarsal Angle (mLTMA) = 23.6o (±3.2). The length of the first metatarsal line was measured from its intersections with the TJL and first metatarsal head and it was 4.3 (±0.94) times longer that TJL (k). For hindfoot correction planning, we used an axis of the calcaneus formed by a line starting at the middle of the back of the calcaneal tuberosity and going perpendicular to a line from the top point to the bottom point of the calcaneal tuberosity. The intersection of the calcaneal line and the anterior continuation of TJL form the lateral heel angle (LHA) = 15.2o (±3.4).The following parameters were identified: the length from the intersection point of the lines and anterior point of TJL was 2.56 ± 1.1 longer than TJL (k1). The length from the intersection point and posterior border of the calcaneus was 4.59 ± 1.0 times longer than TJL (k2). Planning using the new method was demonstrated and confirmed on 3 case examples. A novel method for analysis and planning of midfoot and hindfoot sagittal plane deformity correction may be used separately or simultaneously for complex deformity correction.

Preliminary results for the cement specimens under study have been obtained by the nanoindentation method. It has been found that the elastic modulus increases in the specimens that contain a complex admixture with nanosize particles. Also, the effect is observed on adding an admixture containing only one type of nanoparticles (sol of nanosilica SiO2 or the MWCNT carbon material). Parameters of the nanoindentation method have been selected that ensure obtaining final consistent results. These results are presented by the histograms of distribution of nanoindentation points by elastic moduli and hardness, and also by the distributions in these characteristics in the horizontal plane xy, which is perpendicular to the nanoindenter′s motion. The obtained results suggest that there is a change in the nanostructure of the C–S–H gel, which is compared with the increment in the strength, the Young moduli, and the shear on adding SiO2 nanoparticles and MWCNT nanoparticles.

The classical Ramo–Shockley (RS) theorem gives the current induced on perfect conductors by the motion of nearby charges, assuming nonrelativistic motion of those charges in electrostatic fields. This article illustrates how relativistic and electromagnetic effects modify RS in some simple examples. Specifically, we present explicit, closed form analytic solutions of Maxwell’s equations for the induced current distribution on perfectly conducting plates due to the motion of a line charge moving parallel and perpendicular to the plates. The results have been verified by several methods, including particle-in-cell simulations. They are compared with the classical electrostatic theory used to derive RS. New insights into the limitation and validity of RS are provided. Electromagnetic shocks are explicitly calculated in closed form when the line charge strikes a parallel plate transmission line.

A computational study based on the density functional theory calculations is carried out for the band structure and optical spectra of bulk, tri-layer, bi-layer and monolayer CdS system in the hexagonal-wurtzite structure. The aim of this contribution is to see how the electronic and optical properties of CdS change when moving from the bulk form to the monolayer one through tri-layer and bi-layer Cds systems. Our results show that the monolayer form still has a direct (Г-Г) band gap, but with an increased magnitude with respect to that of bulk CdS. The optical properties of the tri-layer, bi-layer and monolayer form are found to be different from those of the bulk form. An anisotropic character has been shown by the optical spectra for light polarized parallel and perpendicular to the x axis of the crystal. Our findings indicate that novel electronic and optical properties may be obtained when passing from bulk to tri-layer, bi-layer and monolayer CdS system.

We consider the initial-boundary value problem describing joint oscillations of periodically alternating layers of viscoelastic material with memory and layers of viscous incompressible fluid. Solving auxiliary problems on the periodicity cell, we write the corresponding homogenized problem and show that the eigenvalues of the boundary value problems involved in the spectra of one-dimensional eigenoscillations of the original and homogenized media are roots of transcendental and algebraic equations respectively. In the case where the eigenoscillations are perpendicular to the layers, we show that the spectra of the original problems Hausdorff converge to the spectrum of the homogenized problem.

Anchorages of non-rectangular configuration, though not covered by current design codes, are often used in practice due to functional or architectural needs. Frequently, such anchor groups are placed close to a concrete edge and are subjected to shear loads. The design of such anchorages requires engineering judgement and no clear rules are given in the codes and standards. In this work, numerical investigations using a nonlinear 3D FE analysis code are carried out on anchor groups with triangular and hexagonal anchor patterns to understand their behavior under shear loads. A microplane model with relaxed kinematic constraint is utilized as the constitutive law for concrete. Two different orientations are considered for both triangular and hexagonal anchor groups while no hole clearance is considered in the analysis. Two loading scenarios are investigated: (i) shear loading applied perpendicular and towards the edge, and (ii) shear loading applied parallel to the edge. The results of the analyses are evaluated in terms of the load-displacement behavior and failure modes. A comparison is made between the results of the numerical simulations and the analytical calculations according to the current approaches. It is found that, similar to the rectangular anchorages, and also for such non-rectangular anchorages without hole clearance, it may be reasonable to calculate the concrete edge breakout capacity by assuming a failure crack from the back anchor row. Furthermore, the failure load of the investigated groups loaded in shear parallel to the edge may be considered as twice the failure load of the corresponding groups loaded in shear perpendicular to the edge.

In this study, for the first time, to our knowledge, a biosensor was produced using cold atmospheric plasma (CAP) treatment of silver thin film surface with non-perpendicular incidence angle for identification of Escherichia coli in distilled water. Field emission scanning electron microscopy (FESEM) exhibits that before deposition, non-perpendicular CAP treatment of glass surface substrate leads to the production of pinhole-free silver thin film. The results of atomic force microscopy (AFM) and curve fitting show that non-perpendicular CAP treatment of this pinhole-free silver thin film indicates to the appearance of Ag NPs with smaller size and larger surface area compared to untreated silver film deposited on the untreated glass substrate. The silver-based pinhole-free SPR biosensor produced with non-perpendicular CAP treatment of both glass substrate and silver film shows E. coli detection in the distilled water in the range of 104 colony forming unit (CFU/ml) to 108 CFU/ml with better sensitivity compared to the untreated silver-based SPR biosensor.

This paper reports a comprehensive laboratory study into the thermophysical, physical-mechanical characteristics, and tribological properties of the designed composite materials based on polytetrafluoroethylene. In the structures of machines and mechanisms, a significant role belongs to the tribological conjugations made from polymeric and polymer-composite materials. The reliability of machines, in general, depends to a large extent on the reliability of movable connections. Composite materials of nonmetallic origin have a low cost, they are resistant to most aggressive chemicals and are capable of operating under conditions without lubrication. It was established that the characteristics and properties of materials must be adapted to the working conditions of separately considered tribological conjugations. The mechanisms of thermal destruction have been established, both in the basic material and the carbon fiber based on it. It was found that carbon fiber, regardless of its content (quantity) in the polymer-composite material based on polytetrafluoroethylene, is mainly oriented perpendicular to the force application plane. It was found that with an increase in the carbon fiber content from 10 to 40% by weight, the heat capacity decreases by 16‒39% compared to the main material. The optimal operating modes for the designed composite materials have been substantiated on the basis of a pv factor: under a dry friction mode – up to 4MPa∙m/s; at friction with lubrication – up to 36.4MPa∙m/s. The dependence has been established of the friction coefficient on the operating modes of a composite material based on polytetrafluoroethylene containing 20% by weight of carbon fiber when lubricated with oil and water. The results reported here make it possible to synthesize the physical-mechanical characteristics and tribological properties of composite materials in accordance with the required modes of tribological conjugation.

Directivity of fault ruptures modifies the ground motion in the direction of rupture (forward directivity) to have large amplitude shorter duration pulses, and the ground motion opposite to the rupture propagation (backward directivity) to have long duration low amplitude pulses, compared to the ground motion at locations perpendicular to the direction of rupture at similar rupture distances (Rrup). Directivity is prominent in the fault-normal component of ground motion. Multiple extents of directivity scenarios (4 scenarios; 1 symmetric bilateral, and 3 directivity scenarios of different unilaterality) of magnitude 7 on a vertical strike-slip fault (analogous to the San Andreas fault in Southern California) are simulated at a few racetrack locations, of which one forward and one backward directivity station are included. Three racetracks (Rrup 5 km, 10 km, and 15 km) are considered within the near-field where NGA West-2 relations suffer for limited data. The simulated ground motion is applied as base excitation to 2-span seat abutment pre-1970 Californian skew bridges of different skew angles (0°, 15°, 30°, 45o, and 60°), with bridges oriented parallel to the fault and perpendicular to the fault. Probabilistic seismic demand models (PSDMs) are computed for each skew angle at each rupture distance and scenario. Collapse fragility curves are derived from PSDMs, and the median and dispersion are compared with those of HAZUS prescribed values.

A NiCr film is introduced in magnetic tunnel junction (MTJ) seed layer to improve the smoothness of multilayer and to enhance the perpendicular magnetic anisotropy (PMA) of the pinning layer. Espec...

Laser powder bed fusion (LPBF) provides fine spatial resolution for additively manufactured (AM) objects. Development of a new LPBF machine technology enables the incorporation of multi-directional compositional gradients. A sample with six compositional regions ranging from 100% titanium to 100% tantalum perpendicular to the build direction was produced, while also changing the processing parameters for the different material composition. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to observe both the bulk and interface regions. SEM images demonstrate that dendritic morphology is present as a result of the non-equilibrium solidification instead of the one-phase solid solution predicted from the equilibrium phase diagram. EDS line and area scans indicate diffusional segregation of tantalum away from the interface regions. The ability to functionally grade material composition in multiple directions using LPBF AM provides the capability to fabricate complex geometries with spatially varying properties tailored to the desired application.

Based on the earlier developed mathematical model of the complex flow due to the double rotations in two perpendicular directions, the stability analysis is performed in the paper. The Navier-Stokes equations are derived in the coordinate system rotating around the two perpendicular different axes, the vertical one of them is arranged on some distance from the other axis of rotation, the horizontal axis is directed along the tangential line to the circle of the vertical rotation. The two centrifugal and Coriolis forces create the unique features in high oscillating flow, with localities of the stretched liquid, due to their action varying by the circumferential cylindrical coordinate in the channel flow. Stability analysis for the complex rotational flow under double rotations creating strongly varying mass forces and stretching of the liquid is considered at first

A six-week field study was conducted to determine spatial and temporal variability of sub-micron (diameter range 10–1000 nm) particles perpendicular to a main road in the city of Berlin, Germany. Measurements were carried out on 17 days with overall 72 runs along a 250 m almost untraveled footpath. Particle number concentration (PNC) as well as the share of local sources were analyzed in relation to the distance to the road, wind speed and wind direction. This study aims to detect patterns of PNC dispersal along the footpath with increasing distance from the road in a built-up urban environment and to identify impact factors. In the majority of cases, results can be expressed well in terms of an exponential decrease of PNC with increasing distance from the road. Traffic flow along the main road has a substantial impact on concentration levels. About 30 % of the PNC at the roadside and 15 % at a distance greater than 100 m can be attributed to traffic. Variations in background concentrations, however, contribute the largest share to concentration levels.

The paper presents the method of analysis and a comparison of the effectiveness of modified and conventional syntactic foams. The method employs the two-phase superposition approach recently developed for composite materials consisting of several concentric phases. Conventional syntactic foams consisting of spherical voids surrounded by thin glass shells embedded in the matrix are compared to modified foams with cylindrical or spheroidal voids. Modified syntactic foams analyzed in the paper include foams with cylindrical voids aligned along the applied stress or perpendicular to the stress and foams with randomly oriented cylindrical voids. It is demonstrated that while conventional syntactic foams with spherical voids absorb more energy than their modified counterparts, the stiffness of such foams is compromised due to the presence of voids to a larger degree than in modified foams. Accordingly, modified syntactic foams may appear a better compromise if a high energy absorption has to be combined with a prescribed large stiffness of the material.

Ratchet devices allow turning an ac input signal into a dc output signal. A ratchet device is set by moving particles driven by zero averages forces on asymmetric potentials. Hybrid nanostructures combining artificially fabricated spin ice nanomagnet arrays with superconducting films have been identified as a good choice to develop ratchet nanodevices. In the current device, the asymmetric potentials are provided by charged Néel walls located in the vertices of spin ice magnetic honeycomb array, whereas the role of moving particles is played by superconducting vortices. We have experimentally obtained ratchet effect for different spin ice I configurations and for vortex lattice moving parallel or perpendicular to magnetic easy axes. Remarkably, the ratchet magnitudes are similar in all the experimental runs; i. e. different spin ice I configurations and in both relevant directions of the vortex lattice motion. We have simulated the interplay between vortex motion directions and a single asymmetric potential. It turns out vortices interact with uneven asymmetric potentials, since they move with trajectories crossing charged Néel walls with different orientations. Moreover, we have found out the asymmetric pair potentials which generate the local ratchet effect. In this rocking ratchet the particles (vortices) on the move are interacting each other (vortex lattice); therefore, the ratchet local effect turns into a global macroscopic effect. In summary, this ratchet device benefits from interacting particles moving in robust and topological protected type I spin ice landscapes., This work was supported by Spanish MICINN grants FIS2016-76058 (AEI/FEDER, UE), EU COST- CA16218. IMDEA Nanociencia acknowledges support from the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D (MICINN, Grant SEV-2016-0686). MCO and AG acknowledges financial support from Spanish MICINN Grant ESP2017-86582-C4-1-R and IJCI-2017-33991; AMN acknowledges financial support from Spanish CAM Grant 2018-T1/IND-10360. MV acknowledges financial support from Spanish MICINN Grant PID2019-104604RB/AEI/10.13039/50110001103.

A complementary source array with enhanced beamwidth is presented based on the substrate-integrated waveguide (SIW) in this communication. The orthogonal complementary source consists of a SIW slot and a vertical monopole, of which the radiation pattern is heart-shaped, pointing to the direction perpendicular to both slot and monopole. To achieve an enhanced beamwidth from the heart-shaped pattern, the complementary sources are cascaded to form an array. In particular, the slots are etched alternately on both sides of the central axis to achieve an in-phase excitation, while the monopoles are uniformly loaded with an alternate antiphase excitation. This arrangement makes the heart-shaped pattern of each complementary source element alternately point to either side of the array axis, so that the synthesized radiation beamwidth is enhanced in the E-plane. Based on the proposed idea, a nine-element line array is designed, fabricated, and tested. Compared with the same-sized referenced SIW slot array with an E-plane half-power beamwidth (HPBW) of only 80°, the proposed complementary source array extends the HPBW to 180°.

The performance and cost of Bi-2212/Ag wire is limited by the large fraction of Ag matrix (∼3:1) that is required in the oxide-powder-in-tube fabrication process. An alternative fabrication process is being developed in which fine-powder Bi-2212 is uniaxially compressed to form bars with a thin Ag foil sheath. The fine powder naturally textures (aligns the a-b planes perpendicular to the direction of compaction) with texture >80% using 200 MPa compression. A billet is formed by stacking trapezoidal-cross-section bars in a symmetric 8-12-16 pattern around an Ag rod and enclosed in an Ag-wall extrusion can. The billet is extruded and drawn to fine wire. Results are presented on present status of the development and testing.