Radius Of Section Research Articles

Design and Analysis of Matched Microstrip Line Feed Antenna for Ultra Wide Band Applications

The design of an antenna which could cover the entire Ultra Wide Band (UWB) range is always a challenging task. It is often considered as a building block. In this paper a novel technique modifying the ground plane with octagonal shaped monopole patch area is considered for UWB applications. The proposed antenna operates from 2.9GHz to 11.8GHz.The antenna is fabricated on FR-4 substrate with a relative dielectric constant of 4.4 and a thickness of 1.6mm,which is fed by a 50Ω microstrip transmission line. A suitable matching transformer is placed between the feed line and the patch for impedance matching purpose. In this design a partial ground plane with a notch of optimised dimensions is used to achieve UWB characteristics. The antenna is designed and simulated using Microwave studio. The simulated antenna is thoroughly analyzed for Ultra wide band (UWB) characteristics as well as for other geometric specific features. The parameters like feed line dimensions, matching section dimensions, ground length, notch dimensions and radius affecting the performance of an antenna in terms of frequency domain characteristics are investigated. The proposed antenna is simulated in CST and analysed using several parameters like reflection coefficient, Voltage standing wave ratio (VSWR) and Radiation Patterns.

Effect of longitudinal electric field on capillary instability of a thin axisymmetric layer of liquid dielectric coating a dielectric fiber

The flow of a viscous dielectric liquid surrounded with a gas is investigated in the process of capillary disintegration of a thin axisymmetric liquid layer on an undeformable cylindrical dielectric fiber in a uniform electric field is investigated. An asymptotic analysis of the system of equations and hydrodynamic boundary conditions written with allowance for surface ponderomotive forces is carried out for the case when the average thickness of the layer is much smaller than the radius of the fiber cross section. The problem of the transition of the liquid configuration from the state of a stationary cylindrical layer to the hydrodynamic state in the form of a regular sequence of drops is formulated. In this formulation, a nonlinear parabolic equation that describes the evolution of the local thickness of the layer on the time interval to the instant of drop formation is derived. The effect of the key parameters on the capillary instability is analyzed based on the linearized version of the resultant equation and the linearized electrostatic problem of calculating the field perturbations.

Correlation of the properties of ionic conductivity–structure for the RbGaO2 solid electrolyte

The crystal structure of rubidium gallate RbGaO2 in the temperature range of 300–853 K has been investigated using high-temperature neutron diffraction. The channels available for the motion of rubidium cations in the low-temperature and high-temperature modifications of RbGaO2 have been determined using the computer simulation with the TOPOS program. A correlation between the radius of the migration channel cross section and the rubidium cation conductivity has been established.

Measurement and Analysis of Extra Propagation Loss of Tunnel Curve

Wave propagation experiences extra loss in curved tunnels, which is highly desired for network planning. Extensive narrow-band propagation measurements are made in two types of Madrid subway tunnels (different cross sections and curvatures) with various configurations (different frequencies and polarizations). A ray tracer validated by the straight and curved parts of the measuring tunnels is employed to simulate the reference received signal power by assuming the curved tunnel to be straight. By subtracting the measured received power in the curved tunnels from the simulated reference power, the extra loss resulting from the tunnel curve is extracted. Finally, this paper presents the figures and tables quantitatively reflecting the correlations between the extra loss and radius of curvature, frequency, polarization, and cross section, respectively. The results are valuable for statistical modeling and the involvement of the extra loss in the design and network planning of communication systems in subway tunnels.

Three-dimensional effects in low-strain integrity testing of piles: analytical solution

The interpretation of low-strain integrity tests of piles is commonly based on methods developed around the one-dimensional wave propagation theory. In reality, waves resulting from the impact of a hammer on a pile head propagate in three dimensions, and the validity of the plane-front assumption is rather questionable for cases where the size of the hammer is small relative to that of the pile. This paper presents an analytical model of the dynamic response of a pile to an impact load on its head, considering propagation of waves in both vertical and radial directions. The proposed formulation applies to a pile of finite length embedded in multilayered elastic soil, and allows for considering both shape and material pile defects, by reducing locally the radius of the pile cross section or the Young’s modulus of its material. Arithmetic examples are used to depict the effect of high-frequency interferences on the interpretation of pile integrity tests, which can only be accounted for in the three-dimensional formulation of the problem, and lead to practical suggestions for the interpretation of such tests.

Fabrication of aluminum–ceramic skeleton composites based on the Ti2AlC MAX phase by SHS compaction

A one-stage manufacturing technology of aluminum–ceramic skeleton composites by combining the processes of self-propagating high-temperature synthesis (SHS) of a porous skeleton formed by the MAX phase of the Ti2AlC composition and its impregnation by the aluminum melt under pressure (SHS compaction) is considered. A composition of the exothermic charge 2Ti + C + 22.5 wt % Al + 10 wt % TiH2, which provides the formation of a porous skeleton of the Ti2AlC phase without impurity phases by the SHS technology, is selected. It is shown that, when impregnating the hot SHS skeleton with aluminum, new phases are formed such as the MAX phase (Ti3AlC2), titanium carbide (TiC), and titanium aluminide (Al3Ti). However, the content of the basic MAX phase remains high, and the ceramic component of the material consists of Ti2AlC by 76%. When analyzing the microstructure, it is revealed that the composite has certain residual porosity after impregnation and cooling. The influence of the impregnation pressure (q = 22, 28, and 35 MPa) on the distribution of the aluminum content over the height and radius of the diametral sample section is investigated experimentally. It is shown that the nonuniform Al distribution over the sample bulk is caused by the nonuniform pressure and temperature fields, as well as the different compactibility of hot inner and colder outer sample parts. The degree of compaction of characteristic zones is leveled as the impregnation pressure increases, and the composition inhomogeneity over the sample bulk decreases. The difference in aluminum concentration over the sample bulk at q = 35 MPa does not exceed 5%. The SHS-compacted aluminum–ceramic skeleton composite based on the Ti2AlC MAX phase corresponds to high-strength Al-Zn–Mg–Cu aluminum alloys by the hardness level (HB ≈ 150 kg/mm2).

Design and Optimization for the Windowless Target of the China Nuclear Waste Transmutation Reactor

A windowless spallation target can provide a neutron source and maintain neutron chain reaction for a subcritical reactor, and is a key component of China's nuclear waste transmutation of coupling accelerator and subcritical reactor. The main issue of the windowless target design is to form a stable and controllable free surface that can ensure that energy spectrum distribution is acquired for the neutron physical design when the high energy proton beam beats the lead–bismuth eutectic in the spallation target area. In this study, morphology and flow characteristics of the free surface of the windowless target were analyzed through the volume of fluid model using computational fluid dynamics simulation, and the results show that the outlet cross section size of the target is the key to form a stable and controllable free surface, as well as the outlet with an arc transition. The optimization parameter of the target design, in which the radius of outlet cross section is 60 ± 1 mm, is verified to form a stable and controllable free surface and to reduce the formation of air bubbles. This work can function as a reference for carrying out engineering design of windowless target and for verification experiments.

Fabrication of aluminum–ceramic skeleton composites based on the Ti2AlC MAX phase by SHS compaction

A one-stage manufacturing technology of aluminum-ceramic skeleton composites by combining the processes of self-propagating hightemperature synthesis (SHS) of a porous skeleton formed by the MAX phase of the Ti2AlC composition and its impregnation by the aluminum melt under the pressure (SHS compaction). A composition of the exothermic charge 2Ti + C + 22,5 wt % Al + 10 wt % TiH2, which provides the formation of a porous skeleton of the Ti2AlC phase without impurity phases by the SHS technology, is selected. It is shown that when impregnating the hot SHS skeleton with aluminum, new phases are formed such as the MAX phase (Ti3AlC2), titanium carbide (TiC), and titanium aluminide (Al3Ti). However, the content of the basic MAX phase remains high, and the ceramic component of the material consists of Ti2AlC by 76 %. When analyzing the microstructure, it is revealed that the composite has certain residual porosity after the impregnation and cooling. The influence of the impregnation pressure (q = 22, 28 and 35 MPa) on the distribution of the aluminum content over the height and radius of the diametral sample section is investigated experimentally. It is shown that the nonuniform Al distribution over the sample bulk is caused by the nonuniform pressure and temperature fields as well as different compactibility of hot inner and colder outer sample parts. The degree of compaction of characteristic zones is leveled as the impregnation pressure increases, and composition inhomogeneity over the sample bulk decreases. The difference of aluminum concentration over the sample bulk at q = 35 MPa does not exceed 5 %. By the hardness level (HB ≈ 150 kg/mm2), the SHS-compacted aluminum-ceramic skeleton composite based on the Ti2AlC MAX phase corresponds to high-strength Al–Zn–Mg–Cu aluminum alloys.

Effect of acoustic field parameters on arc acoustic binding during ultrasonic wave-assisted arc welding

As a newly developed arc welding method, power ultrasound has been successfully introduced into arc and weld pool during ultrasonic wave-assisted arc welding process. The advanced process for molten metals can be realized by utilizing additional ultrasonic field. Under the action of the acoustic wave, the plasma arc as weld heat source is regulated and its characteristics make an obvious change. Compared with the conventional arc, the ultrasonic wave-assisted arc plasma is bound significantly and becomes brighter. To reveal the dependence of the acoustic binding force on acoustic field parameters, a two-dimensional acoustic field model for ultrasonic wave-assisted arc welding device is established. The influences of the radiator height, the central pore radius, the radiator radius, and curvature radius or depth of concave radiator surface are discussed using the boundary element method. Then the authors analyze the resonant mode by this relationship curve between acoustic radiation power and radiator height. Furthermore, the best acoustic binding ability is obtained by optimizing the geometric parameters of acoustic radiator. In addition, three concave radiator surfaces including spherical cap surface, paraboloid of revolution, and rotating single curved surface are investigated systematically. Finally, both the calculation and experiment suggest that, to obtain the best acoustic binding ability, the ultrasonic wave-assisted arc welding setup should be operated under the first resonant mode using a radiator with a spherical cap surface, a small central pore, a large section radius and an appropriate curvature radius.

Study on Improved Road Geometry Conditions of Chicane Considering the Relationship between Road Geometry and Carbon Emissions Reduction

PURPOSES: Recently, many local governments have applied chicanes for traffic calming to ensure environment-friendly comfortable and safe roads. However, the geometry of a chicane is designed for speed reduction using a curved portion. This study aims to improve the road geometry conditions of chicanes for reducing carbon emissions and maintaining appropriate driving speeds by considering the relationship between road geometry and carbon emissions. METHODS: This study was conducted as follows. First, carbon emissions corresponding to changing acceleration of vehicles were studied. Second, vehicle acceleration caused by the relationship between the curve radius and the straight length was studied. Accordingly, desirable conditions of curve radius and length of the straight section for reducing carbon emissions were proposed. RESULTS: The existing literature on chicanes present the minimum value of stagger length and path angle in the primary variable condition. This study suggests the maximum values of the curve radius and length of straight section in the primary variable condition. Therefore, if a vehicle's speed at a chicane is 30 km/h, this study suggests a curve radius of up to 24 m. In addition, if the vehicle's speed is 24 km/h, this study suggests a length of straight section of up to 6.6 m. These are the geometric conditions for considering the control of acceleration to the vehicle's maximum speed. CONCLUSIONS: This paper proposes an application of geometric conditions to reduce carbon emissions and maintain appropriate speeds of vehicles through a combination of curve radius and length of straight section.

High Sensitivity of Balloon-Like Bent MMI Fiber Low-Temperature Sensor

A novel low cost and simple temperature sensor based on multimode interference (MMI) is formed by a successive singlemode fiber (SMF)-bent multimode fiber (MMF)-SMF structure. Due to the small curvature radius of bent MMF section mimicking a balloon shape, MMI effect from the core is spreading into coating. The high temperature sensitivity is mainly due to the large thermo-optical coefficient of the existing acrylate coating of the MMF fiber. A temperature sensitivity of up to −2060 pm/°C and −25.1 nW/°C for wavelength- and intensity-based interrogation, respectively, have been achieved in the range between 27 °C and 31 °C. This sensor is most suitable in high sensitivity and low-temperature application such as the measurement of human body temperature.

Numerical investigation of hydrodynamics and thermal performance of a specially configured heat pipe for high-temperature thermal energy storage systems

In the present study, a complex geometry, high temperature heat pipe was investigated numerically. The heat pipe was designed specifically to improve the performance of the thermal energy storage system incorporated in a concentrated solar power system. Due to the complexity of the heat pipe geometry, a new numerical approach was developed. The heat conduction in the wall and wick regions was included in the two-dimensional axisymmetric model. The compressibility of the working fluid and viscous dissipation were taken into account. Due to the high expansion ratio from adiabatic section to condenser, high speed vapor flow impinges on the condenser wall. The combined vapor jet impingement and condensation on the condenser wall was modeled by attaching a porous layer. This porous layer forces the impinging vapor jet to split out radially while it allows the wall suction. The heat rejection via the vapor condensation was estimated from the mass flux by energy balance at vapor–liquid interface. The heat transfer limits due to heat pipe geometry, working fluid, wick structure, and operational temperature were calculated. The vapor–wick interface temperature predicted by the current simulation agrees very well with the available experimental data. The performance of the heat pipe was evaluated by calculating the corresponding thermal resistance. The results showed that the thermal resistance decreases with the increase of the operating temperature and vapor radius while increases with the increase of the heat input. It was also shown that, for the cases studied, adiabatic section radius of 15 mm is sufficient. Further increase of the radius does not reduce the thermal resistance of the heat pipe.

Theoretical and experimental analysis of the evaporating flow in rectangular microgrooves

A theoretical model for axial capillary flow in rectangular microgrooves was presented with the assumptions that the meniscus radius in the cross section is approximately constant, and the height of the centerline film recedes along the axial direction with a convex form. Experimental data obtained by Micro-PIV verify the assumptions. Comparison with the experimental data shows that the model is accurate to predict the axial profile of the liquid film for inclined rectangular microgrooves.

МЕТОДИКА ЧИСЛЕННОГО РАСЧЕТА ОПТИМАЛЬНЫХ ФОРМ ТЕЛ ВРАЩЕНИЯ ПРИ ДВИЖЕНИИ В ГРУНТОВОЙ СРЕДЕ

The method of calculating the optimal forms of axisymmetric projectiles during motion in soil medium on the base of direct optimization method is developed. The methods of local variations and cyclic by coordinate descent are used. Direct numerical calculations are carried out in an axisymmetric formulation. The form of a optimal body found on the basis of a model of local interaction is taken as an initial approximation. A local interaction model (LIM) is used below, based on the analytical solution of the one-dimensional problem of the expansion of a spherical cavity in a Grigoryan soil medium assuming that the medium behind the shock wave front is incompressible. The main assumptions made in solving the problem of optimizing the shape of axisymmetric bodies within the framework of the LIM, i.e., that a model that is quadratic in the velocity is applicable, the friction is proportional to the pressure and flow over the body occurs without separation, have been confirmed theoretically and experimentally earlier. The applicability of the LIM in describing the penetration of sharp cones has been demonstrated experimentally and theoretically by comparison with the results of numerical calculations in an axisymmetric formulation using a Grigoryan soil medium model. The errors in the LIM in determining the drag forces when applied to blunt bodies have been shown too. In this work the effectiveness of the developed methodology is shown in the problem determining the shape of minimum resistance projectile among the bodies of revolution having a set length and radius of the cross section. Good agreement has been reached between the results for the generatrix of a body of revolution in the form of a parametric Bezier polynomial and a piecewise linear curve. Convergence of successive approximation methods for the solution of a parametric optimization problem is studied. The essential role of two-dimensional flow effects was revealed.

Modeling Driver Behavior by Using the Speed Environment for Two-Lane Rural Roads

Roadway safety involves the three components of the roadway system: the people, the vehicle, and the roadway. When the design corresponds to what the driver hopes to find, the road is consistent; the most widely used methods to evaluate design consistency are based on analysis of the operating speed profile. When the roadway alignment does not violate driver expectations, the possibility of drivers making errors is reduced. The aim of this experimental study is to obtain widely valid formulas during the design phase to predict the speeds that will actually be found on rural roads. Studies have shown that the dominant influences on curve speed are local curvature and the speed environment pertaining to the road section. The environment speed is a driver's preferred speed of travel within a road section with relatively homogeneous alignment. For the purposes of this study, this speed was taken as the 85th percentile speed measured on a tangent or on the curve with the highest radius in a homogeneous road section.

A Numerical Study of MHD Laminar Flow in a Rotating Curved Pipe with Circular Cross Section

The incompressible viscous steady flow through a rotating curved pipe of circular cross-section with magnetic field is investigated numerically to examine the combined effects of rotation (Coriolis force), magnetic field and curvature (centrifugal force) on the flow. The curvature of the pipe has been assumed to be small, that is, the radius of the circle in which the central line of the pipe is coiled is large in comparison with the radius of the cross section. Spectral method is applied as a main tool for the numerical technique, where Fourier series, Chebyshev polynomials, Collocation methods, and Iteration method are used as secondary tools. The flow depends on the Taylor number (Tr), Dean Number (Dn), Magnetic Parameter (M) and the dimensionless curvature of the pipe δ. When Tr > 0, the rotation is in the direction so that the Coriolis force enforces the curvature effect. When Tr < 0, the rotation is in the direction so that the Coriolis force exhibits an opposite effect to that of the curvature. The calculations are carried out for −1500 ≤ Tr ≤ 1500, Dn ≥ 1000 (large Dean number), M ≥ 0 and δ = 0.01. Due to high magnetic field four-vortex solution is observed in a rotating curved pipe system. Visualization is attained with MAPLE software.

Structure of Sodium Carboxymethyl Cellulose Aqueous Solutions: A SANS and Rheology Study.

We report a small angle neutron scattering (SANS) and rheology study of cellulose derivative polyelectrolyte sodium carboxymethyl cellulose with a degree of substitution of 1.2. Using SANS, we establish that this polymer is molecularly dissolved in water with a locally stiff conformation with a stretching parameter. We determine the cross sectional radius of the chain ( 3.4 Å) and the scaling of the correlation length with concentration (ξ = 296 c−1/2Å for c in g/L) is found to remain unchanged from the semidilute to concentrated crossover as identified by rheology. Viscosity measurements are found to be in qualitative agreement with scaling theory predictions for flexible polyelectrolytes exhibiting semidilute unentangled and entangled regimes, followed by what appears to be a crossover to neutral polymer concentration dependence of viscosity at high concentrations. Yet those higher concentrations, in the concentrated regime defined by rheology, still exhibit a peak in the scattering function that indicates a correlation length that continues to scale as. © 2014 The Authors. Journal of Polymer Science Part B: Polymer Physics Published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 492–501

Parameter Study of Opposite Tape-Spring Flexure Hinge

Parameter study for the qusai-static folding and deployment of opposite tape-spring flexure (OTSF) hinges is presented. The full factorial method is employed to design of experiments, and the qusai-static folding and deployment nonlinear analysis is obtained by ABAQUS/Explicit solver. Parametric studies show that both the section radius and the central angle have significant effects to the peak moment of quasi-static folding and deployment of the OTSF hinges. However, the maximum Mises stress in complete folding configuration is more sensitive to the central angle than the section radius.

Authentication of Polygonati Odorati Rhizoma and other two Chinese Materia Medica of the Liliaceae family by pharmacognosy technique with GC–MS analysis

Yuzhu (Polygonati Odorati Rhizoma), Kangdingyuzhu (Polygonati Prattii Rhizoma), and zhugenqiyuzhu (Disporopsis Fuscopictae Rhizoma) are of the same family, but of different genera. They have all often used in Chinese Materia Medica (CMM) as Polygonati Odorati Rhizoma in China market. Three species of CMM are confused. For better application, we need to identify these plants accurately. This study use pharmacognosy technique and GC-MS analysis, three species of CMM were authenticated. In macroscopic characteristics, the fruit of Polygonati Odorati Rhizoma is blue-black, while the other two are maroon and dark purple orderly. Nodes of Polygonati Odorati Rhizoma are upward and light uplift, about 1 cm spacing, while the other are not. As for microscopic characteristics, the cortex of Polygonati Odorati Rhizoma only occupies about 1/5 of the radius of the transverse section with inconspicuous endodermis, which is much smaller than others. The type of vascular bundles of Polygonati Odorati Rhizoma is closed collateral, but the other is amphivasal. Raphides of calcium oxalate are scattered, but Raphides of the other two are like brooms and neat rows. GC-MS analysis of essential oil could provide different characteristics to distinguish three species. Twenty-three compounds were identified from essential oil of Polygonati Odorati Rhizoma and the main components were n-hexadecanoic acid (49.45%), while n-hexadecanoic acid of the other two are 23.92% and 9.45%. The content of n-hexadecanoic is strongly different. This research was aimed to establish a method by pharmacognosy and GC-MS analysis to identify three CMM and for providing scientifical data to ensure accuracy of origin of three species.

Research on enhancement sensitivity of embedded fiber Bragg grating sensor

With its unique advantages, embedded fiber Bragg grating (FBG) sensor is more and more used in the field of engineering structural health monitoring. According to the actual needs of engineering monitoring, we combined with the internal structure to make sensitivity design of the sensor. It mainly through setting the elastic modulus and the radius of sensor's inner sheath intermediate section, to make the strain of middle section larger than average strain, In order to achieve the increasing sensitivity. Through the analysis, the enhancement degree is relevant to the length, radius and elastic modulus of the middle section, so it could achieved different requirement of sensitizing by adjusting these parameters. Through the analysis of the core strain in the sensitizing structure, it can obtain the strain transfer distribution in the scope of sensor. All these could provide the theory basis for the realization of embedded FBG sensor's sensitivity enhancement.