Transverse Cross Section Research Articles

Hard exclusive processes involving kaons

Hard exclusive electroproduction of kaons as well as the kaon-induced exclusive Drell-Yan process are investigated within the handbag approach which is based on factorization in hard subprocesses and soft generalized parton distributions (GPDs). The kaon-hyperon transition GPDs occurring here, are related to the proton GPDs by flavor symmetry. The latter ones are taken from analyses of pion electroproduction. Like in hard processes involving pions the transversity GPDs play an important role in the processes of interest - the transverse cross sections are larger than (or, for the Drell-Yan process, about equal to) the longitudinal ones. The evolution of the transversity GPDs is taken into account for the first time but, as the analysis reveals, it is a minor effect in the range of photon virtualities of interest. The predictions for the cross sections agree fairly well with the sparse available electroproduction data.

Cross Sections, Transition Intensities, and Laser Generation at the 3P1 → 3H5 Transition of LiY0.3Lu0.7F4:Pr3+ Crystal

Lasing and spectroscopic properties of an LiY0.3Lu0.7F4:Pr3+ crystal grown by the Bridgman–Stockbarger method were investigated in detail. Absorption and luminescence spectra were recorded using polarized light. Lifetimes of excited states 3PJ were determined. Absorption and emission transition intensities were calculated according to f–f-transition intensity theory taking into account interconfiguration interaction. Stimulated emission transverse cross sections were determined using the Fuchtbauer–Ladenburg method. Pumping by an InGaN laser diode produced continuous-wave laser generation at 522.6 nm (3P1 → 3H5) in Pr-doped mixed fluoride crystals with a maximum output power of 0.38 W and a slope efficiency of 19%.

REMOVED MACROBUTTON FIELD]Arrays of fiber Bragg gratings selectively inscribed in different cores of 7-core spun optical fiber by IR femtosecond laser pulses

In this paper, we present a new method of point-by-point femtosecond inscription of fiber Bragg gratings (FBG) arrays of different configurations in a 7-core spun optical fiber. The possibility of FBGs inscription with predefined periods in individual fiber cores allowed us to realize: 1) longitudinal FBG arrays with identical or variable resonant wavelengths in all side cores, 2) longitudinal FBG arrays inscribed only in the central or in the selected side core, and 3) an FBG array in a transverse cross section of a fiber consisting of an FBG inscribed in the central and three side cores. Based on the proposed method, by enabling the inscription through the acrylate protective coating of the fiber, a vector bend sensor has been created. Implementation of this sensor has shown that bending radii less than 4 mm can be measured with a high precision using a single-channel interrogation scheme.

Dynamic analysis of continuous beams by the boundary element method

The main contribution of this work is the development of two Boundary Element Method (BEM) formulations for the dynamic analysis of Euler-Bernoulli continuous beams. The first one employs the static fundamental solution; due to this, it is named D-BEM, with D meaning domain. The other employs the time-dependent fundamental solution, and is called TD-BEM, with TD meaning time-domain. Both of formulations present a domain integral of the load. The D-BEM formulation presents an additional domain integral in the equations, thus requiring the discretisation of the entire domain. The TD-BEM formulation enables one to perform the analysis using only the boundary nodes, in the absence of initial conditions. As the problem is one-dimensional, the boundary is constituted only by the external nodes. At each node, one finds four variables: transverse displacement, cross-section rotation, bending moment and shear force. For this reason, not only one but two BEM equations are necessary to solve the problem. These are the equations related to the displacement and to the cross-section rotation. Both formulations produced results with good agreement between them, as the results of the three examples show. In the last example, a comparison is made between Boundary Element Method and Finite Element Method results.

Modeling of direct-drive cylindrical implosion experiments with an Eulerian radiation-hydrodynamics code

Recent improvements to xRAGE, Los Alamos National Laboratory's Eulerian radiation-hydrodynamics code, have enabled the computation of laser-driven experiments relevant to inertial confinement fusion and high energy density physics. Here, previous directly driven cylindrical implosion experiments are modeled in order to benchmark xRAGE design simulations for future cylindrical implosion experiments, representing the first attempt to model such systems with an Eulerian code with adaptive mesh refinement. Simulations in 2D of transverse and axial cross-sections of the cylindrical target are performed, and the results are combined to form a 3D representation of the imploding cylinder. Synthetic radiographs are produced and analyzed from the simulation results, allowing for a direct comparison with experimentally measured quantities. The zeroth-order hydrodynamic trajectories of targets with no specified initial perturbation are well matched by the computations. Simulations of targets with a preimposed sinusoidal perturbation in the azimuthal direction show single-mode instability growth that is in agreement with the available data, but higher fidelity experimental measurements are required to enable more detailed comparisons. The mode growth observed in computations compares favorably with predictions of a linear theory for the ablative Rayleigh-Taylor instability.Recent improvements to xRAGE, Los Alamos National Laboratory's Eulerian radiation-hydrodynamics code, have enabled the computation of laser-driven experiments relevant to inertial confinement fusion and high energy density physics. Here, previous directly driven cylindrical implosion experiments are modeled in order to benchmark xRAGE design simulations for future cylindrical implosion experiments, representing the first attempt to model such systems with an Eulerian code with adaptive mesh refinement. Simulations in 2D of transverse and axial cross-sections of the cylindrical target are performed, and the results are combined to form a 3D representation of the imploding cylinder. Synthetic radiographs are produced and analyzed from the simulation results, allowing for a direct comparison with experimentally measured quantities. The zeroth-order hydrodynamic trajectories of targets with no specified initial perturbation are well matched by the computations. Simulations of targets with a preimposed sinusoi...

Fraunhofer diffraction of a Gaussian beam by a four-sector binary grating with a half period fringes shift between adjacent sectors

The study of Fraunhofer diffraction of a Gaussian laser beam by a computer-generated, binary four-sector grating (FSG) is presented. In the four equal angular sectors of the FSG, parts of a binary rectilinear grating are embedded in such a way that, two neighboring parts are shifted by a half spatial rectilinear grating period. Analytical expressions, describing the diffracted wave field amplitude and intensity distributions in the focal plane of a converging lens, are derived. The zeroth-diffraction-order beam is a Gaussian beam whose transverse cross section has a reduced Gaussian radius. The higher-diffraction-order beam transverse intensity profiles have four bright spots divided by dark crossed lines and a central dark, non-vortex core. They can be described as cosine-Laguerre–Gaussian Kummer beams. The numerically calculated diffraction patterns, as well as the interference patterns of the diffracted beam with a slightly inclined plane wave, are supported by experimentally obtained ones. In both investigations (theoretical and experimental) the interferograms confirm the non-vortex nature of the diffraction spots.

Growth models for two commercial tree species in upland forests of the Southern Brazilian Amazon

Despite all efforts to promote sustainable use of timber resources in tropical forests, the current management criteria still require adjustments at a species level, considering specific growth patterns and ecological features. Forest management in upland forests (terra firme) of the Brazilian Amazon region generally applies for all commercial tree species a common minimum logging diameter (MLD) of 50 cm and a felling cycle (FC) varying according to the harvest intensity between 25 and 35 years.. In this study, we define species-specific FCs and MLDs for the two commercial tree species Hymenaea courbaril L. (Fabaceae) and Handroanthus serratifolius (Vahl) S.O. Grose (Bignoniaceae) from the terra firme of the Southern Brazilian Amazon, applying growth models based on the relationships between estimated tree age, diameter, height and volume. A total of 37 transversal cross-sections (20 stem discs from Hymenaea and 17 from Handroanthus) were obtained at a height of 20–60 cm above soil level in a private forest concession close to the municipality of Novo Aripuanã in the southern region of the Amazonas state. The two species are common in terra firme forests and have high wood densities of 0.76–0.96 g cm−3 (H. courbaril) and 0.85–1.08 g cm−3 (H. serratifolius). The mean age of H. courbaril and H. serratifolius, estimated by ring counting, varied from 104 to 241 years and both species had similar mean diameter increments of 3.9 ± 0.5 mm year−1 and 4.1 ± 0.6 mm year−1, respectively. Both species present similar tree growth in diameter, height and volume resulting in a FC of 24.2 years and a MLD of 64.9 cm for H. courbaril, and a FC of 26.0 years and a MLD of 69.5 cm for H. serratifolius. These results demonstrate the need to adjust the selective logging systems practiced in the Brazilian Amazon region towards a species-specific management of timber species to increase the sustainability of selective logging.

Material anisotropy and elasticity of cortical and trabecular bone in the adult mouse femur via AFM indentation

This paper investigates the elastic properties of bone tissue in the adult mouse femur through Atomic Force Microscopy (AFM) indentation with the goal of understanding its microstructure and underlying mechanics at the nano length scale. Both trabecular and cortical bone types are studied. In particular, we examined the elasticity of cortical bone and individual trabeculae in the longitudinal and transverse directions of the samples. For cortical bone, the elastic modulus in the longitudinal direction was found to be 10–15% higher than that in the transverse direction; for trabecular bone, this difference was 42%. For the trabeculae, this value was found to be in a lower range (0.92 ± 0.22 GPa). As per the transverse elastic modulus, an average of 1.58 ± 0.36 GPa was measured for cortical bone, and 0.55 ± 0.21 GPa for trabecular bone. The anisotropy ratio was within the range of 1.2–1.5 for cortical bone and 1.7–2 for trabecular bone. While the elastic modulus of cortical bone varied along the length of the femur with up to 30% variation, no significant differences were observed within each transverse section. The effect of indentation frequency (1–500 Hz) on the longitudinal elastic moduli was also investigated for cortical and trabecular bone, with results showing a correlation between indentation frequency and elastic modulus.Statement of significance: This study examines the adult mouse femur with a twofold aim: to investigate the anisotropy and inhomogeneity of cortical and trabecular bone tissues and to elucidate their elastic behavior at the nanometer length scale. The elastic moduli of cortical bone and individual trabecula are measured in the longitudinal and transverse cross-sections via AFM indentation at selected locations and in specific directions of the adult mouse femur. The results provide insights into the relationship between mechanical properties and structural morphology of cortical and trabecular bone tissue.

Fractal light from lasers

Fractals, complex shapes with structure at multiple scales, have long been observed in Nature: as symmetric fractals in plants and sea shells, and as statistical fractals in clouds, mountains and coastlines. With their highly polished spherical mirrors, laser resonators are almost the precise opposite of Nature, and so it came as a surprise when, in 1998, transverse intensity cross-sections of the eigenmodes of unstable canonical resonators were predicted to be fractals [Karman et al., Nature 402, 138 (1999)]. Experimental verification has so far remained elusive. Here we observe a variety of fractal shapes in transverse intensity cross-sections through the lowest-loss eigenmodes of unstable canonical laser resonators, thereby demonstrating the controlled generation of fractal light inside a laser cavity. We also advance the existing theory of fractal laser modes, first by predicting 3D self-similar fractal structure around the centre of the magnified self-conjugate plane, second by showing, quantitatively, that intensity cross-sections are most self-similar in the magnified self-conjugate plane. Our work offers a significant advance in the understanding of a fundamental symmetry of Nature as found in lasers.

Band-Like Distribution of Grains in Selective Laser Melting Track Under Keyhole Mode

Grain structure in the melt pool under keyhole mode is complex due to complicated solidified conditions, especially in consideration of the intense fluid flow. This paper aims to clarify grain structure and grain growth mechanism in melt pool under keyhole mode in selective laser melting. The microstructure from transverse cross section and longitudinal cross section near the centerline of 316L single tracks was characterized. In the longitudinal cross section, band-like grain structure formed. It is found that fluid flow can refine the grains, and large columnar grains grow towards crystallographic 〈110〉 direction.

Test of the hadronic interaction models SIBYLL2.3, EPOS-LHC and QGSJETII- 04 with Tibet EAS core data

A hybrid experiment has been started by the ASγ experiment at Yangbajing (4300m a.s.l.) in Tibet since May 2009, that consists of a high-energy air-shower-core array (YAC-I) and a high-density air-shower array (Tibet-III). In this paper, we report our results to check the hadronic interaction models SIBYLL2.3, SIBYLL2.1, EPOS-LHC and QGSJETII-04 in the multi-tens TeV energy region using YAC-I+Tibet-III experimental data from May 2009 through January 2010. The effective live time is calculated as 106.05 days. The results show that the description of transverse momentum, inelastic cross-section and inelasticity for the 4 hadronic interaction models is consistent with YAC-I experimental data within 15% systematic errors range in the forward region below 100 TeV. Among them, the EPOS-LHC model is the best hadronic interaction model. Furthermore, we find that the H4a composition model is the best one below the 100 TeV energy region.

An Automated Procedure for Assessing Local Reliability Index and Life‐Cycle Cost of Alternative Girder Bridge Design Solutions

Stakeholders of civil infrastructures have to usually choose among several design alternatives in order to select a final design representing the best trade‐off between safety and economy, in a life‐cycle perspective. In this framework, the paper proposes an automated procedure for the estimation of life‐cycle repair costs of different bridge design solutions. The procedure provides the levels of safety locally guaranteed by the selected design solution and the related total life‐cycle cost. The method is based on the finite element modeling of the bridge and uses design traffic models as suggested by international technical standards. Both the global behavior and the transversal cross section of the bridge are analyzed in order to provide local reliability indexes. Several parameters involved in the design, such as geometry and loads and materials’ characteristics, are considered as uncertain. Degradation models are adopted for steel carpentry and rebars. The application of the procedure to a road bridge case study shows its potential in providing local safety levels for different limit states over the entire lifetime of the bridge and the life‐cycle cost of the infrastructure, highlighting the importance of the local character of the life‐cycle cost analysis.

Internal structure of ichthyosaur rostrum from the Upper Jurassic of Poland with comments on ecomorphological adaptations of ophthalmosaurid skull

ABSTRACT This study presents a detailed analysis of a semi-articulated finding of an ichthyosaur Ophthalmosauridae indet. rostrum fragment from the Upper Jurassic (Oxfordian) in the Morawica quarry in the Holy Cross Mountains (Southeastern Poland). The specimens are preserved as transverse cross-sections of the large rostrum on the surface of two limestone slabs. 3D virtual reconstructions of these fossils widen knowledge on the internal morphology of the ophthalmosaurid ichthyosaurs cranial region and the functional adaptations and palaeoecology of these marine reptiles. New information about the rostral cavity is provided from three-dimensional models of preserved structures. This Ophthalmosauridae indet. Specimen has a relatively large and wide nasal cavity. We proposed a new model of saturation-inhalation of the ophthalmosaurid ichthyosaurs skull, which is an open system connecting external and internal nares of the animal. This ecomorphological adaptations of ophthalmosaurid skull were useful during the feeding near the water surface in the two-dimensional habitats of shallow sea and sky and also in the deeper three-dimensional marine environment. The function described here is parsimonious with the Late Jurassic shallow marine environment of the Holy Cross Mountains.

Geometrical aspects of ion beam and plasma-based stripping processes for refurbishing cutting tools

Stripping of hard coatings is an essential technological step in the refurbishment of various cutting tools, such as carbide drills, endmills, routers, etc. The dry ion etching method of coating stripping may give significant advantages over conventional wet chemical etching. In this work, a novel ion plasma and ion beam-based method of film stripping are discussed in terms of etching uniformity. Thin film etching rate distribution is experimentally studied over the transverse cross-section of TiN and TiAlCrN coated drill bits. Furthermore the results are discussed in terms of simplified mathematical models of the film removal by ion sputtering. Advantages of the directional ion beam method over the field driven plasma immersion method are concluded.

Correlation of microstructural and mechanical properties of K-doped tungsten fibers used as reinforcement of tungsten matrix for high temperature applications

Reinforcement of tungsten by tungsten fibers (Wf) is considered an attractive option to mitigate the intrinsic brittleness of this material and to possibly extend the operational temperature window to ensure safe operation of the plasma facing component. By now, it has been demonstrated that tungsten fiber-reinforced tungsten composites (Wf/W) acquire pseudo ductility even at room temperature, and crack propagation is determined by the interaction of the fibers with the propagating crack. In view of strong temperature oscillations, expected during operation in the fusion plasma, the mechanical properties of tungsten fibers annealed at different temperatures (up to 2300 °C) were assessed, and the role of potassium (K) doping on the modification of the mechanical properties of as-annealed wires was studied. While K-doping was found to delay the brittleness induced by heat exposure at least up to 1600 °C, still a strong reduction of the fiber strength was observed in tests performed at elevated temperatures. In this work, we investigate the reasons for this effect by performing scanning electron microscopy coupled with electron backscatter diffraction measurements. The longitudinal and transversal cross-sections of W fibers were analyzed to deduce the morphology and size distribution of the grains. Consistent with the mechanical data, we found that annealing at 2100 °C resulted in the full recrystallization of the elongated grains, otherwise formed due to the extrusion fabrication process. Even at 1900 °C, the longitudinal cross-section still exhibits elongated grains. The transversal shape of the grains undergoes a change from needle-like fine structure to equiaxed grain shape upon annealing above 1600 °C. Few scans done for 2300 °C annealed wire revealed that the microstructure contains one or several grains with a dimension of 70–150 μm. The obtained results are discussed and analyzed in the frame of mechanistic model connecting microstructure with the mechanical response.

On a geometrically exact Euler‐Bernoulli beam element

AbstractIn this work, a geometrically exact, fully nonlinear Euler‐Bernoulli beam formulation is presented. Herewith a special case of Timoshenko rod models, discussed in various publications such as [2] or [4], is considered. Following the basic assumptions of transversal shear rigidity and plane cross sections, the formulation is based on displacements, their derivatives and a torsional rotation angle, in order to cover finite deformations and rotations. A straight reference configuration is considered, whereas the possibility for initially curved configurations is discussed in [1]. Within the Euler‐Bernoulli theory a cross section undergoes ridged body translation and rotation. While the translation is described by the motion of the beam axis only, the rotation is accounted within a rotational field, see e.g. [3]. In the present formulation, the rotational field is parametrized by the rotation tensor based on Rodrigues formula, which yields a simple update scheme as shown in [5], and is the first of its kind for Euler‐Bernoulli beam models. Using this parametrization an ansatz is presented, that allows for consistent connection of structural members, even in cases of physical discontinuities. On the element level C1 continuous Hermite polynomials are used to interpolate the displacements an their derivatives, while a Lagrangian interpolation scheme is chosen for the torsional rotation. A numerical Benchmark problems is presented to demonstrate the performance of the finite element formulation.

Patellar dislocation: osteochondral graft of patella and medial patellofemoral ligament reconstruction

Objectives:The incidence of acute femoro-patellar luxation is 6/100000 persons for year. This injury is common among young patients with predominance in women. It has high levels of recurrence (40%) after the first injury. The objective of our study is to assess post-surgical results in patients with relapsing patellar dislocation, after a reconstruction of Medial Patellofemoral Ligament (MPFL) with semitendinous autologous graft associated with autologous osteochondral transplant of patella.Methods:An observational descriptive study (cases serie) with a restrospective transversal cross section was carried out. Six male patients that were treated between March 2014 and March 2016 were evaluated. They were monitored / followed up in an average of 24 months.The functional subjective results were assessed following Kujala patellofemoral pain score.Results:Out of the six patients, all of them were male, with an average age of 19. They were followed-up for an average of 24 months. The results of the Kujala score were 86 points in the posoperative period.Conclusion:The reconstruction of Medial Patellofemoral Ligament (MPFL) with semitendinous autologous graft associated with autologous osteochondral transplant of patella has show excellent short and long-term clinical results with return of patients to their usual normal activities.

Residual stresses of friction melt bonded aluminum/steel joints determined by neutron diffraction

Near interfacial residual stresses are investigated in a joint composed of aluminum alloy and dual phase steel. A small step neutron diffraction scan was initially performed to determine the weld interface position along the measured transverse cross section. Residual stress measurements were then performed in three orthogonal directions for steel and aluminum using {211} and {311} diffraction peaks, respectively. The small step scan enables to identify the wavy nature of the interface, which has been subsequently combined in the residual stress calculation. The resultant of all three components of the residual stresses is almost zero along the mid-thickness of the steel plate, validating the estimated stresses. Near the interface, residual stresses on the steel reveal an “M” shape distribution while in the aluminum sheet they show a “W” shape. The interfacial residual stresses in the steel originate from the thermomechanical processing condition, phase transformation and the mismatch in the coefficients of thermal expansion (CTE). At the vicinity of the interface, the aluminum plate presents a distribution of residual stresses similar to a superposition of residual stresses resulting from an arc welding and the effect of mismatch in CTE.

MRI features of presumed normal palatine tonsils in dogs.

To describe the MRI characteristics of normal palatine tonsils in dogs. Retrospective study of 95 dogs with presumed normal tonsils. Tonsillar margination, shape and signal intensity in pre- and postcontrast studies were assessed and the cross-sectional area was measured at the point of maximal size on transverse images. In all cases the tonsils were located with their largest transverse cross-section at the level of the temporomandibular joints. Their margins were well-defined in all dogs; in 57 (60%) the borders were smooth and in 38 (40%) slightly irregular. The majority (96%) of the tonsils were rounded to oval in cross-section and the remainder were elongated. All tonsils were hyperintense to the medial pterygoid muscles in T1-weighted, T2-weighted, FLAIR and T2* gradient echo images and they showed either homogeneous (53%) or heterogeneous (47%) signal intensity. Contrast enhancement was marked (65%) or moderate (33%) in the majority of animals. Median tonsillar cross-sectional area was approximately 29 mm2 (90% confidence interval: 10.0 to 64.4 mm2 ). There was significant positive correlation between bodyweight and tonsillar cross-sectional area and a weak negative correlation between age and tonsillar cross-sectional area. MRI is of value in assessing normal palatine tonsils in dogs. This study could be used as a baseline for the investigation of the value of MRI in assessment of tonsillar disease in dogs.

HSS coating with keyholes in penetration produced by laser cladding process

This paper is devoted to the assurance of higher durability of hard coatings by using irregular method of laser cladding (LC). The purpose of this study was to demonstrate that by producing of keyhole mode LC coatings enables to create functionally graded structure in interface. This can contribute to decrease the gradient of trough-depth residual stresses of the coating-substrate system formed by dissimilar steels. Experimental work was carried out using precise LC system, which consists of industrial robot (KUKA) and 1kW Yb-fiber laser (IPG Laser). Experimental coatings were created on cold work tool steel substrate AISI D2 using high-speed steel (HSS) powder AISI M2. The properties of coatings produced by two different methods have been evaluated in the course of a comparative analysis by examination of morphology of transverse cross-sections, elemental composition, microhardness distribution inside coatings and tribological tests. Results showed that coating with keyhole mode in penetration had lower hardness due to a larger amount of dilution however the smooth transition of properties in the interface was obtained. Despite the significant difference in hardness both coatings demonstrated very similar tribological behaviour.