Longitudinal Radius Research Articles

An inkjet-printed bendable antenna for wearable electronics.

104Flexible antennas, which can conform to the skin and transfer signals to terminals, are particularly useful for wearable electronics. Bending, which frequently occurs to flexible devices, significantly affects the performance of flexible antennas. Inkjet printing has been used as an additive manufacturing technology for fabricating flexible antenna in recent years. However, there is little research on the bending performance of inkjet printing antenna in both simulation and experiment. This paper proposes a bendable coplanar waveguide antenna with a small size of 30 × 30 × 0.05 mm3 by combining the advantages of fractal antenna and serpentine antenna, which realizes the ultra-wideband feature and avoids the problems of large dielectric layer thickness (greater than 1 mm) and large volume of traditional microstrip antenna at the same time. The structure of the antenna was optimized by simulation using the Ansys high-frequency structure simulator, and the antenna was fabricated on a flexible polyimide substrate by inkjet printing. The experimental characterization results show that the central frequency of the antenna is 2.5 GHz, the return loss is -32 dB, and the absolute bandwidth is 850 MHz, which is consistent with the simulation results. The results demonstrate that the antenna has anti-interference capability and can meet the ultra-wideband characteristics. When the traverse and longitudinal bending radius are greater than 30 mm and skin proximity greater than 1 mm, the resonance frequency offsets are mostly within 360 MHz, and return losses of the bendable antenna are within the -14 dB compared with the no bending condition. The results exhibit that the proposed inkjet-printed flexible antenna is bendable and promising for wearable applications.

A simplified deformation forewarning method for longitudinal structural performance of existing shield tunnels based on Fast Fourier Transform

The longitudinal differential settlement of tunnel is the key factor to determine the safety of tunnel structure during service life. Based on the measured settlement data of the tunnel, this paper provides a forewarning method for defects locations. Firstly, Timoshenko beam is used to simulate the longitudinal mechanical response of the tunnel structure under the surrounding rock load, and the precise tunnel settlement curve reconstructed by Fast Fourier Transform (FFT) is used to replace the Timoshenko theoretical solution which is difficult to be solved directly. Combined with the tunnel longitudinal deformation forewarning analysis model, the approximate conversion between the longitudinal deformation curvature radius, circumferential joint opening, differential settlement and dislocation is carried out. The sensitivity of the deformation indexes is discussed through the dichotomy method. It is concluded that longitudinal deformation curvature radius is the most sensitive deformation indexes for the longitudinal structural performance of the tunnel. Finally, the forewarning results are compared with the actual diseases locations. The results show that the method can better determine the defect location of longitudinal tunnel structure in operation. The method can provide a better reference for deformation forewarning and performance evaluation of existing tunnel.

Interferences and dispersion of developable domains in columnar liquid crystal

We are interested in characteristic defects S1/2 in an optically anisotropic columnar liquid crystal (C8HET) where the growth of the columns develops cylinders or semi-spherical topology around a core of radius rc. We have described the growth of an S1/2 defect in a columnar liquid crystal (CLC). The conservation of several director columns n→ carried by directions (div n→ = 0) gives structures in half-spheres surfaces.In the structure of the half-drop, we compare the growth of the transversal radius RT and the longitudinal radius RL to discuss the topology of the surface structure. We show the existence of destructive fringes on the surface of the half-drop characterized by a black ring. Furthermore, we characterize the interference phenomena between the incident ray and the reflected one in tangential incidence on the surface of the half-drop by the localization of the interference field, the interfringe and the dispersion in polychromatic light.The present work shows that the liquid index nl exhibits a noticeable difference versus the wavelength λ, the liquid index nl is given by the relationship: nl=1.4763+0.0067λ2.

ОЦІНКА ГЕОМЕТРИЧНОЇ ПРОХІДНОСТІ ПЕРСПЕКТИВНИХ БРОНЬОВАНИХ КОЛІСНИХ ПЛАТФОРМ

The issue of forming reasonable requirements for promising samples of weapons and military equipment is an urgent task that must be solved on the basis of the results of scientific research. One of these tasks is the formation of operational and tactical requirements for an armored wheeled platform, which should later become the basis for the creation of a line of armored vehicles for various purposes. In this case, one of the main indicators that affect the combat and technical characteristics of such a platform is its permeability. Thus, assessing the permeability indicators and the impact on them of the design features of the machine and its elements is a task that needs to be solved in the course of the creation of a combat vehicle. The permeability indicators are influenced by factors that can be divided into the following groups: traction-dynamic (machine weight, specific power, specific wheel pressure), structural (type of power transmission, suspension type, types of differentials, type and design of tires), geometric (clearance, angles of front and rear overhang, longitudinal and transverse radius of permeability, wheels, maneuverability). After analyzing these factors, we can conclude that the assessment of geometric permeability indicators can be done already at the design stage, which in the future will help in deciding on the choice of a particular design of the machine. Thus, the article defines indicators that affect the permeability of wheeled BTR, as well as a comparative analysis of geometrical permeability indicators of existing and promising BTR with different wheel formulas. The results of these studies can be used in the further development of proposals for the formation of justified requirements for the components of promising BPC, which affect their permeability. Keywords: armored wheel platform, armament and military equipment, BTR, operational and tactical requirements, geometric permeability.

Shape Prediction of the Sheet in Continuous Roll Forming Based on the Analysis of Exit Velocity.

Continuous roll forming (CRF) is a new technology that combines continuous forming and multi-point forming to produce three-dimensional (3D) curved surfaces. Compared with other methods, the equipment of CRF is very simple, including only a pair of bendable work rolls and the corresponding shape adjustment and support assembly. By controlling the bending shapes of the upper and lower rolls and the size of the roll gap during forming, double curvature surfaces with different shapes can be produced. In this paper, a simplified expression of the exit velocity of the sheet is provided, and the formulas for the calculation of the longitudinal curvature radius are further derived. The reason for the discrepancy between the actual and predicted values of the longitudinal radius is deeply discussed from the perspective of the distribution of the exit velocity. By using the response surface methodology, the effects of the maximum compression ratio, the sheet width, the sheet thickness, and the transverse curvature radius on the longitudinal curvature radius are analyzed. Meanwhile, the correction coefficients of the predicted formulas for the positive and negative Gaussian curvature surfaces are obtained as 1.138 and 0.905, respectively. The validity and practicability of the modified formulas are verified by numerical simulations and forming experiments.

Nonlocal Markov approximation for mean field propagating in a medium with dielectric permittivity fluctuations in case of finite values of longitudinal correlation radius 2. Inhomogeneous background medium

The solution to the integro-differential (nonlocal) Markov equation for the mean field, developed in the companion paper, which takes account of finite values of the longitudinal correlation radius of fluctuations of the dielectric permittivity, is extended to the case of an arbitrary smoothly inhomogeneous background medium. The explicit solution to the problem is presented.

Nonlocal Markov approximation for mean field propagating in a medium with dielectric permittivity fluctuations in case of finite values of longitudinal correlation radius 1. Homogeneous background medium

Classic method of the diffusive Markov parabolic equation for the mean field in a stochastic medium is extended to the case of finite values of the longitudinal correlation radius of fluctuations. In the limiting case of δ-correlated fluctuations the solution constructed reproduces a well-known solution to the case of the diffusive Markov approximation for the mean field.

Dimensional Analysis and Optimization of IsoTruss Structures with Outer Longitudinal Members in Uniaxial Compression.

This study analyzes the buckling behavior of 8-node IsoTruss® structures with outer longitudinal members. IsoTruss structures are light-weight composite lattice columns with diverse structural applications, including the potential to replace rebar cages in reinforced concrete. In the current work, finite element analyses are used to predict the critical buckling loads of structures with various dimensions. A dimensional analysis is performed by: deriving non-dimensional variables using Buckingham’s Theorem; plotting the variables with respect to critical buckling loads to characterize trends between design parameters and buckling capacity; evaluating the performance of the outer longitudinal configuration with respect to the traditional, internal longitudinal configuration possessing the same bay length, outer diameter, longitudinal radius, helical radius, and mass. The dimensional analysis demonstrates that the buckling capacity of the inner configuration exceeds that of the equivalent outer longitudinal structure for the dimensions that are fixed and tested herein. A gradient-based optimization analysis is performed to minimize the mass of both configurations subject to equivalent load criteria. The optimized outer configuration has about 10.5% less mass than the inner configuration by reducing the outer diameter whilst maintaining the same global moment of inertia.

Influence of thickness reduction on the forming results in the three-dimensional surface rolling process with rigid arc-shaped rollers

Three-dimensional surface rolling with rigid arc-shaped rollers (TSRRAR), a new method for manufacturing double-curved metal sheets, can be used to realize the rapid forming of 3D surface sheets. The non-uniform roll gap is generated by a pair of rollers with different axial radii with appropriately reduced sheet thickness. After passing through the roll gap, a flat sheet is bent in the rolling direction. Meanwhile, it deforms perpendicular to the rolling direction, resulting in a three-dimensional surface part with curvatures in both directions. The work adopted the elastic-plastic finite element (FE) method to simulate aluminum alloy sheets with different maximum thickness reductions. The results showed that the longitudinal curvature of sheets rose as the reduction increased. Moreover, a slightly increased reduction caused a significant variation in the longitudinal curvature radius of sheets. Different bending curvatures of sheets could be obtained by changing the reduction, indicating the flexible forming of three-dimensional curved surface metal sheets. Also, the changing trend of longitudinal curvatures of testing parts obtained by rolling experiments was substantially in agreement with the FE simulation results. Therefore, the established FE models can be used for exploring the manufacturing process of TSRRAR.

Bending Capacity of Concrete-Encased Underground Electrical Duct Banks under Monotonic Loading: An Experimental Study

The bending capacity of concrete-encased underground electrical duct banks has been the subject of considerable investigation using the load-structure method; however, the role of high-density polyethylene (HDPE) conduits and the thresholds of electrical duct banks has not been fully scrutinized. This study examines the bending behaviors of electrical duct banks subjected to monotonic vertical loading in a soil box using an advanced monitoring device to measure the conduit diameter change. An analysis of the experiment shows the effective role of HDPE conduits in improving the bending capacity of electrical duct banks. The results suggest 5% and 7.5% as the deformation rate thresholds with respect to the ultimate states of serviceability and bearing capacity, respectively. The threshold of the longitudinal curvature radius is determined to be 18000 m. Finally, the evolution trends of the stress and deformation rates of HDPE conduits are recommended for the monitoring indexes and control standards of electrical duct banks.

Effects of longitudinal and transverse curvatures on optimal design of shell footbridge

Shell bridges have attracted extensive interest in engineering research and practice. This paper aims to evaluate the effects of longitudinal and transverse curvatures on the optimal design of the shell bridge. For this purpose, a slant-legged steel shell footbridge with the same initial and target volumes of steel was chosen to build parametric geometric models with different curvature radii, and then topology optimization was carried out using the bi-directional evolutionary structural optimization (BESO) technique to obtain optimized designs with high structural stiffness. Furthermore, linear static analysis and eigenvalue analysis demonstrate that the displacement, von Mises effective stress, and the first-order vertical vibration frequency satisfied all the requirements of design regulations. Numerical results indicate that not only the longitudinal curvature but also the transverse curvature have a significant effect on the optimized designs of steel shell footbridge. While the mean compliance increased with the transverse curvature radius, it first decreased and then increased with the longitudinal curvature radius.

ФУНКЦИОНИРОВАНИЕ И ДИНАМИКА ЛАНДШАФТОВ ПРИ ПРОЕКТИРОВАНИИ АВТОМОБИЛЬНЫХ ДОРОГ В ГОРНЫХ УСЛОВИЯХ

Introduction. Roads, as linear engineering structures in mountainous conditions for the sake of traffic safety, should provide a smooth interface and their harmonious combination with the surrounding landscape with the use of longitudinal slopes and radii on curves that reduce accidents and injuries. Anthropogenic intervention on the mountain natural landscape, for the purpose of road construction, is not always safe, because weak soils come into dynamics and the functioning of the road is complicated. For this , it is necessary to conduct a spatial analysis and an integrated approach to the issue, covering all aspects of landscape design of the road to eliminate negative consequences. The essence of the question. The design of highways in mountainous areas without observing the landscape principles of safe operation and with less dynamic shifts of the roadbed leads to a violation of the relief forms, with the implementation of large volumes of earthworks necessary to ensure the projected slope. Research methods. In the process of writing the article, the following methods were used: analysis - in the search and analysis of literature on the subject; observation and comparison in the study and selection of the optimal option. Conclusions: 1. When designing highways in mountain landscapes, it is necessary to find a harmonious combination of the functioning of the road and the landscape itself. 2. A scientifically based analysis and correct choice of landscape design elements in the operation of the road will reduce the dynamics of slope phenomena, the number of accidents, the cost of road maintenance, which contribute to improving safety on mountain roads.

Differentiation of hypertensive heart disease and hypertrophic cardiomyopathy with myocardial stiffness measurements: a shear wave imaging study using ultra-high frame rate echocardiography

Abstract Background Recently, cardiac shear wave (SW) elastography, based on high frame rate (HFR) echocardiography, has been proposed as new non-invasive technique for assessing myocardial stiffness. As myocardial stiffness increases with increasing wall stress, differences in measured operating myocardial stiffness do not necessarily reflect differences in intrinsic myocardial properties, but can also be caused by mere changes in loading or chamber geometry. This complicates myocardial stiffness interpretation for different types of pathologic hypertrophy. Purpose To explore the relationship between myocardial stiffness and underlying pathological substrates for cardiac hypertrophy. Methods We included 20 patients with hypertension (HT) and myocardial remodelling (59±14 years, 75% male), 20 patients with hypertrophic cardiomyopathy (HCM) (59±16 years, 60% male) and 20 healthy controls (56±14 years, 75% male). Left ventricular (LV) parasternal long axis views were acquired with an experimental HFR scanner at 1293±362 frames per seconds. Propagation velocity of SW occurring after mitral valve closure in the interventricular septum (IVS) served as measure of operating myocardial stiffness (Figure A). To compare myocardial stiffness among hearts with differing loading conditions and chamber geometry, SW velocities were normalized to end-diastolic wall stress, estimated at IVS from regional wall thickness, longitudinal and circumferential regional radii of curvature, and non-invasively estimated LV end-diastolic pressure (EDP). Results SW velocities differed significantly between groups (p<0.001). The controls had the lowest SW velocities (4.02±0.97 m/s), whereas values between HT and HCM group were comparable (6.46±0.99 m/s vs. 7.00±2.10 m/s; p=0.738). Considering end-diastolic wall stress, HCM patients had the same SW velocity at lower wall stress compared to HT (Figure B), indicating higher myocardial stiffness in the HCM group. SW velocities normalized for wall stress indicated significantly different myocardial stiffness among all groups (p<0.001) (Figure C). In a multiple linear regression model, the underlying pathological substrate independently influenced SW velocity (beta 1.37, 95% CI (0.78–1.96); p<0.001), while wall stress did not significantly affect its value (p=0.479). Conclusions Our study demonstrated that SW elastography can detect differences in myocardial stiffness in hypertensive heart and hypertrophic cardiomyopathy. Additionally, our results suggest that SW velocity is dominated by underlying myocardial tissue properties. We hypothesize that differential changes in cardiomyocytes and/or the extracellular matrix contribute to the differential myocardial stiffening in different pathologic entities of LV hypertrophy. Thus, SW elastography could provide useful novel diagnostic information in the evaluation of LV hypertrophy. Figure A, B, C Funding Acknowledgement Type of funding source: None

Prediction of Longitudinal Curvature Radius of 3D Surface Based on Quadratic Relationship between Strain and Coordinates in Continuous Roll Forming

Continuous roll forming (CRF) is a new method for the rapid forming of three-dimensional (3D) surfaces developed in recent years, and the significant advantage of CRF compared with traditional die forming is that the longitudinal dimension of the sheet metal is not limited. By controlling the curvature radius and gap shape of upper and lower bending rolls, three-dimensional parts with different shapes and sizes can be precisely formed. When the elastic deformation is ignored during the forming process, the transversal curvature radius of the three-dimensional surface is consistent with the radius of the roll gap centerline. Therefore, the calculation of longitudinal curvature radius is the key to improve the accuracy of the 3D surface in CRF. In this paper, the basic principle of CRF is described. The modified formulas for calculating the longitudinal curvature radius of convex and saddle surfaces based on the quadratic relationship between the strain and coordinates are deduced in detail, and the corresponding design method of the roll gap is derived. Furthermore, the mathematical equations of convex and saddle surfaces are given. Through numerical simulation and theoretical analysis, it is found that the relative errors of the longitudinal centerline radius are reduced from 13.67% before modification to 4.35% after modification for a convex surface and 6.81% to 0.41% for a saddle surface when the transversal curvature radius is 800 mm and the compression ratio is 5%. The experimental and measured results indicate that the shapes of formed parts are more consistent with the target parts after modification, which further proves the applicability of the modified formulas.

Digital light microscopy to characterize the scales of two goatfishes (Perciformes; Mullidae).

The normal and lateral line scales from above the head and four flank regions were investigated in two goatfishes by using light microscopy to evaluate the microscopic characteristics of scale surface ornamentation from different body parts of these fishes and to add new morphological data for their discrimination. The body scales were removed and digital images captured with a Dino-Lite digital camera connected to a Leica compound microscope. The presence of both transverse and longitudinal radii was a distinctive characteristic for the scales of studied goatfishes. The most distinctive features of the key scales discriminating the two goatfishes were the scale shape, the presence of irregular grooves in scale surface, the presence of transverse radii in the lateral fields, and the availability of lepidont at the anterior field. The lateral line scale ornamentations were almost similar in two species; however, the lateral line canal was branching in Parupeneus heptacanthus. Scale extension index indicated that in both species, the dimension of normal key scales tends to the right, while the dimension of lateral line scales tends to the left. This study accentuated that scales from different body regions may exhibit variation in surface ornamentations, that scale morphology could successfully be used to discriminate the examined goatfishes, and that the use of fish scale microscopy is an easy and relatively rapid method and does not require fish sacrifice. Since fish identification is essential for the conservation and management of species, the use of scale morphology to this purpose appears particularly promising.

Ranking contributors to traffic crashes on mountainous freeways from an incomplete dataset: A sequential approach of multivariate imputation by chained equations and random forest classifier

The estimation of the effect of contributors to crash injury severity and the prediction of crash injury severity outcomes suffer often from biases related to missing data in crash datasets that contain incomplete records. As both estimation and prediction would greatly improve if the missing values were recovered, this study proposes a sequential approach to handle incomplete crash datasets and rank contributors to the injury severity of crashes on mountainous freeways in China. The sequential approach consists of two parts: (i) multivariate imputation by chained equations imputes the missing values of independent variables; (ii) a random forest classifier analyses the correlation between the dependent and the independent variables. The first part considers different imputation methods in light of the independent variables being either binary, categorical or continuous, whereas the second part classifies the correlations according to the random forest classifier. The proposed method was applied to the case-study about mountainous freeways in China and compared to the analysis of the raw dataset to evaluate its effectiveness, and the results illustrate that the method improves significantly the classification accuracy when compared with existing methods. Moreover, the classifier ranked the contributors to the injury severity of traffic crashes on mountainous freeways: in order of importance vehicle type, crash type, road longitudinal gradient, crash cause, curve radius, and deflection angles. Interestingly, a lower importance was found for environmental factors.

Analysis on light power and three-dimentional temperature distribution characteristics of gain guided and index alternate-guided fiber lasers

Gain guided and index alternate-guided (GGIA-G) fiber was suggested by our group recently. In this work, the improved rate equations of the GGIA-G fiber laser were established and solved. The pump and signal light power distribution along the fiber longitudinal axis were simulated under the conditions of forward, backward and bidirectional pump. Furthermore, a theoretical three-dimensional temperature distribution model of the GGIA-G fiber laser was established, and the temperature distribution characteristics along both the fiber longitudinal axis and radius were simulated and compared when the fiber was pumped with different methods. The research results show that different pump method has obvious influence on both signal light power distribution and the fiber temperature. When the fiber is forward pumped, the signal light power in the fiber is the highest, and when the fiber is bidirectionally pumped, the temperature of the fiber is the lowest. The research conclusions are helpful in the application of the GGIA-G fiber.

Plasma bubble evolution in laser wakefield acceleration in a petawatt regime

The bubble regime of the laser wakefield acceleration is one of the most recent and promising mechanisms for generating quasi-monoenergetic electron beams. In this work, we propose to study the dynamics of bubble (a wake structure devoid of electrons created in underdense plasma by a highly-intense ultrashort laser pulse) in a petawatt regime. The dependence of the electron beam energy and the quality of the electron beam on the shape of the bubble is the main motivation behind this work. The bubble length as well as bubble shape have been investigated using two-dimensional particle-in-cell simulations. The evolution of the bubble with time, and the correlation of bubble length (longitudinal and transverse radius) with the intensity of laser pulse have been revealed in this study. The change of bubble dimensions can be estimated by various determining factors such as the laser pulse focusing, the beam loading, the residual electrons, and the bubble velocity. It has also been confirmed that the shape of the bubble cannot be predicted using fixed shape models as spherical or elliptical. Simulations unveil that as the bubble traverses in plasma, it evolves from spherical shape to the highly elliptical shape. And, as it approaches the dephasing length, the eccentricity decreases further. Consequently, the self-injection of plasma electrons in the bubble is seriously affected by the bubble evolution. Comparison of the electron energy gain at different intensities of laser pulse has also been provided. Various scaling laws for electron beam energy estimations are predicted in this investigation. High quality electron beam can be obtained by controlling the bubble evolution, which may have significant applications in future coherent light sources, biomedical, condensed matter physics, and x-ray generation by table-top FEL.

Added Resistance and Speed Loss of a Ship Found Using Onboard Monitoring Data

Prediction of the added resistance or corresponding speed loss in real sea conditions is essential to evaluate the performance of a ship. Assessment of the environmental impact on vessel performance is essential for route and cargo planning, optimization of fuel consumption and design, and configuration of engines and the main propulsion system. In the present study, added resistance and speed loss in real sea conditions are evaluated from1 year of onboard monitoring data of a platform supply vessel (PSV) operating in the North Sea. The true sea margin is shown on an annual basis. Relative contributions from environmental conditions and vessel operation control are presented. Results are compared with model experiments and existing numerical methods for prediction of added resistance and speed loss in waves. The study shows that added resistance due to waves for this PSV is significantly larger than predicted by conventional frequency-domain calculations or model tests. No reason for the deviation is found, but it is anticipated that a combination of effects of longitudinal mass radius of gyration, differences in wavelength and steepness in model tests and reality, and nonlinear effects (not accounted for in the numerical calculations) is partly responsible for the deviations. For ships having similar main dimensions, the conventional ways of predicting added resistance or speed loss in waves is nonconservative, and improved methods should be sought.

Linear Distribution Principle for Sheet Forming Using Continuous Roll Forming Process

Continuous roll forming (CRF) process utilizes two reconfigurable rollers as forming tools to manufacture 3D surface part. In order to investigate the longitudinal deformation of 3D curved surface part, the detailed mathematical methodology using a geometrical relationship is analyzed and described. The results show that the necessary condition for generating longitudinal bending deformation is the linear distribution of the longitudinal fiber. The deformation characteristics of CRF studied by simulation confirm that the ideal longitudinal deformation is generated when the distribution of longitudinal fibers satisfy the linear distribution principle, the maximum length difference of longitudinal fibers is the major factor determining the longitudinal curvature radius of formed part, and increasing maximum length difference of longitudinal fibers incurs an increasing longitudinal curvature. In addition, 3D surface parts with different longitudinal curvature were prepared by CRF process, which had verified the proposed linear distribution principle.