Annular Groove Research Articles

Kinematic Detections of Protoplanets: A Doppler Flip in the Disk of HD 100546

Abstract Protoplanets and circumplanetary disks are rather elusive in their thermal IR emission. Yet they are cornerstones to the most popular interpretations for the protoplanetary disk structures observed in the gas and dust density fields, even though alternative theories exist. The gaseous velocity field should also bear the imprint of planet–disk interactions, with non-Keplerian fine structure in the molecular-line channel maps. Such kinks or wiggles are affected by the optical depth structure and synthesis imaging limitations, but their detail could in principle be connected to the perturber by comparison with hydrodynamical simulations. These predictions appear to have been observed in HD 163296 and HD 97048, where the most conspicuous wiggles are interpreted in terms of embedded planets. The velocity centroid maps may allow for more robust indirect detections of embedded planets. The non-Keplerian velocity along the planetary wakes undergoes an abrupt sign reversal across the protoplanet. After subtraction of the disk rotation curve, the location of the perturber should be identifiable as a Doppler flip in velocity centroid maps. Here we improve our rotation curves in an extension to disks with intermediate inclinations, which we apply to deep and fine angular resolution CO isotopologue data sets. Trials in HD 163296 and in HD 97048 yield nondetections. However, in HD 100546 we pick up a conspicuous Doppler flip, an important part of which is likely due to radial flows. Its coincidence with a fine ridge crossing an annular groove inside the continuum ring suggests a complex dynamical scenario, in which the putative protoplanet might have recently undergone pebble accretion.

A Low-Temperature Micro Hotplate Gas Sensor Based on AlN Ceramic for Effective Detection of Low Concentration NO2.

Air pollution is one of the major threats to human health. The monitoring of toxic NO2 gas in urban air emission pollution is becoming increasingly important. Thus, the development of an NO2 sensor with low power consumption, low cost, and high performance is urgent. In this paper, a planar structural micro hotplate gas sensor based on an AlN ceramic substrate with an annular Pt film heater was designed and prepared by micro-electro-mechanical system (MEMS) technology, in which Pt/Nb/In2O3 composite semiconductor oxide was used as the sensitive material with a molar ratio of In:Nb = 9:1. The annular thermal isolation groove was designed around the heater to reduce the power consumption and improve the thermal response rate. Furthermore, the finite element simulation analysis of the thermal isolation structure of the sensor was carried out by using ANSYS software. The results show that a low temperature of 94 °C, low power consumption of 150 mW, and low concentration detection of 1 to 10 ppm NO2 were simultaneously realized for the Nb-doped In2O3-based gas sensor. Our findings provide a promising strategy for the application of In2O3-based sensors in highly effective and low concentration NO2 detection.

Numerical simulation of allocator annular flow field

The allocator is the key tool for the oilfield to realize the multi-layered polymer flooding. The most common allocator is the annular pressure-reducing groove structure. The selection of reasonable structural characteristics parameters has always been a difficult problem in the design of pressure reducing structure. The structural optimization design involves many parameters, and the numerical simulation method can effectively reduce the dependence on the experiment and the number of experiments. In this paper, the parametric modelling of the annular pressure-reducing groove structure is carried out, and the numerical simulation model of the power law fluid flowing in the annular channel is established. The turbulence calculation model is used to numerically calculate the flow field. The velocity, pressure, turbulent kinetic energy and strain rate contours are obtained and analysed. The numerical calculation results of the annulus flow field with four different structural characteristic parameters are compared and the optimal structural parameters are obtained, which can provide valuable reference for the design and improvement of the annular pressure-reducing groove allocator.

All-dielectric ultra-broadband metamaterial absorber based on imidazole ionic liquids

We propose an all-dielectric hollow annular groove ultra-broadband metamaterial absorber (A-D ILMMA) based on imidazole ionic liquids, which is freed of metallic substrate and can offer an extremely wide bandwidth of electromagnetic absorption and prominent wide polarization angle range. When the ionic liquid 1-ethyl-3-methylimidazolium Tetrafluoroborate ([EMIM][BF4]) with a high conductivity and dielectric loss factor is arranged into the hollow annular groove unit cells with a 6 mm total thickness, nearly perfect impedance matching can be achieved in a wide frequency range. Research results show that the simulated absorptivity is over 90% in 13.9–50 GHz with the relative bandwidth of 113%, and the corresponding microwave experiment is performed to support the results of the simulation. Moreover, the A-D ILMMA can work efficiently at arbitrary polarization angles from 0° to 90° and wide incident angles from 0° to 60°.

Effect of Rotational Speed on Microstructure and Mechanical Properties of 2060 Aluminum Alloy RFSSW Joint

Refill friction stir spot welding (RFSSW) is used to weld 3.2-mm-thick 2060 aluminum alloy sheets. In this study, we investigated the formation, microstructures and mechanical properties of the RFSSW joint. The results show that increasing the rotational speed is beneficial to eliminating annular groove but increasing the flash. The hook of the joint at each rotational speed is downward bending. The void at the bottom of the sleeve-affected zone (SAZ) and incomplete bonding at the lap interface initially increase and then decrease with the rotational speed increments from 2000 to 2600 rpm. The microstructure distribution at the bottom of the stir zone (SZ) is similar to that at the interface of the SAZ/thermo-mechanically affected zone (TMAZ), including SZ, TMAZ, heat-affected zone, and the base material. The microhardness values of the joint gradually decrease along the sheet thickness at each welding condition. Furthermore, the microhardness at the SAZ/TMAZ interface initially increases to the maximum at 2400 rpm and then decrease to the minimum at 2600 rpm. Moreover, the tensile-shear failure load of the joint initially increases and then decreases with increasing rotational speeds. The fracture positions of tensile-shear specimens are related to microstructure distribution, microhardness, material flow, and welding defects.

ОПРЕДЕЛЕНИЕ ГРАНИЧНЫХ УСЛОВИЙ ДЛЯ РАСЧЁТА ТЕРМОНАПРЯЖЕННОГО СОСТОЯНИЯ ПОРШНЯ

The paper deals with the study of the influence of the working process parameters of the two-stroke opposed piston engine like D100 (20.7/2×25.4), especially the heat exchange between the working substance and the wall of the combustion chamber (CC) – cylinder and pistons on temperature and stress-strain state of the piston. To make an estimation of the effect of a working process on the boundary condition we considered the internal heat balance and specific features of gas dynamic loading of main parts of the cylinder-piston group. To calculate the temperature fields, the actual boundary conditions of non-stationary thermal loading were replaced with the equivalent steady-state ones, obtained from the condition that the amount of heat perceived by the piston surface in real and conditionally equivalent processes are equal. Equivalent parameters of heat transfer are calculated by the condition of conservation of the amount of heat passing through the walls of the CS. It was performed the validation of the calculation of equivalent heat exchange parameters. It is shown that in case of an error in specifying the initial conditions, for example, temperature per 100K, the temperature of the piston CC surface may change by 5K in the first 5 operating cycles. It is shown that the developed model of the workflow can be adjusted according to the available experimental data and used to model the boundary conditions. The authors made corrections to the dependence obtained by prof. Rosenblit, to determine the current heat transfer coefficient from the working fluid to the walls of the CC by the total heat removal for the cycle, equal to 20%. It was obtained the average coefficient of heat transfers from the working fluid to the piston and the temperature of the cycle for the nominal mode, which are 3500 W/(m2•K) and 835 K respectively. It was carried out the simulation of the thermal properties of the gap between the piston ring and the groove filled with combustion products. It is shown that the conditions of heat transfer through annular grooves and rings require clarification in modeling, which is associated with the conditions of heat transfer in the gaps, and the gap can be replaced by a gasket with appropriate thermal properties.

Design of A Novel Dual Band High Gain Antenna Based on the Enhancement of Wave Propagation

A novel planar high gain antenna is presented based on enhanced microwave transmission to meet the needs of antenna gain in communications systems, The antenna consists of two intersecting sub-wavelength holes, add in the surrounding annular groove used to improve transmission enhancement effect. The results show that the gain of the antenna at the operating frequency 11.9GHz is 11.4dB, and the gain of 16.2GHz at the operating frequency point is 12.4dB, which has a high application value in the field of wireless communication.

Demonstration of on-chip quantum dot microcavity lasers in a molecularly engineered annular groove.

The on-chip quantum dot (QD) microcavity laser engineered on an annular groove made of fused silica was demonstrated based on the external quasi-cavity configuration. By incorporating an appropriate dose of polymer into QD film, the spectral purity of the lasing spectrum was significantly enhanced. In contrast to the dye microcavity laser embedded on the same trench profile, a QD laser possesses a lifetime that is over 10 times longer. We have introduced a unique two-step quantum gain deposition process that has remarkably reduced the wavelength drifts of laser emissions in an aqueous environment by approximately 400%. The reconfigurable cavity platform in combination with an appropriately engineered quantum gain medium embedded onto it promises to enable photostable chip-scale coherent light sources for various photonic, chemical, and biochemical sensing applications.

Incremental forming characteristics of hollow parts with grooves

Incremental profile forming (IPF) is a new plastic processing technology developed in recent years. The new profile manufacturing technology is mainly used to produce tubular parts with variable cross sections along the axis of tube. The parts with different cross sections produced by this technology satisfy the lightweight and high strength requirements of the tubular parts. The IPF method is very flexible and can form diverse complex-shaped parts. Because no special machine is available for this technology, depending on the shapes of formed tubular parts, the forming tool and forming method should be designed. Thus, this study proposes a new method to form the annular groove and tube wall groove. Using a special tool and servo drive system of spinning machine, it is possible to form an annular groove and tube wall groove on the surface of tubular part. This is a typical IPF method for tubes. The process of different grooves on the surface of tubes was systematically studied in this paper. Through experiments and finite element simulations, different process parameters influencing the forming quality of groove were studied. It was concluded that the tool’s single feed and spindle speed significantly affect the forming quality and forming limit.

Design and Analysis of the Integrated Motor Cooling System for Shaftless Propeller

In order to deal with the heat dissipation of the integrated permanent magnet motor for a certain shaftless propeller, this paper designs an automatic water-circulation cooling system. The cooling system involves two annular grooves on the inner wall of the duct before and after the blades, the two grooves are connected with the air-gap between the motor stator and rotor to form a cooling passage in which cooling water flows from the rear of the propeller to the front. The performance analysis of the cooling system is a multi-physics problem involving electromagnetic field, flow field, and temperature field. This study combines the finite element method and the finite volume method to simulate and analyze the multi-field coupling problem of the cooling system. Tests of the shaftless propeller prototype are used to prove that the coupling simulation model is accurate and the cooling system is practical. Additionally, the verified simulation model is applied to analyzing the influence of several key factors, such as air-gap flow rate, pouring sealant thermal conductivity, and stator sheath material, on the heat dissipation of the integrated motor. The study made in this paper can provide a reference for developing the same kind of devices.

Numerical simulation of high-speed joining of sheet metal structures

Abstract The increasing trend of multi-material and space-frame design in automotive car body constructions consolidates the need for mechanical joining technologies with one-sided accessibility. The high-speed joining process (also called “RIVTAC®” or “Impact”) is an innovative and flexible technology. In this process, a tack having a profiled shank and an ogival shaped tip is pushed into the joining partners with a speed of 20 to 40 m/s without any pre-punching. The plastic and friction work is converted into heat, which causes an abrupt rise of temperature in the joining zone. This improves the flowability of the material which leads to filling the annular grooves existing on the shank of the tack. Simultaneously, a force-fit is created between the sheet metal and the tack. Furthermore, the effects of inertia are used so that the thin-walled structures can be joined without any additional tools (e.g. a die). The joining process causes the deformation of the structure, which must be taken into account with regard to tolerances. The numerical simulation is a powerful tool to predict the deformation and the joinability of a complex structure as well as the mechanical properties of the connection. The paper is about the detailed process- and load-simulation of high-speed joining as well as the required experimental data basis, such as temperature and strain rate dependent flow curves. Furthermore, the friction parameters are very important for the physical consideration of the force-fit connection. Coupled structural-thermal simulations of an axisymmetric 2D-model are performed using explicit and implicit codes.

ДІАГНОСТИКА ПЕРЕДПОМПАЖНОГО СТАНУ ОСЬОВОГО КОМПРЕСОРА З НАДРОТОРНИМ ПРИЛАДОМ

Ensuring the gas-dynamic stability of gas turbine engine, still remains one of the actual problem of modern aircraft engine building. To date, a significant number of studies have been conducted. This studies are the foundation for different techniques of diagnosing the pre-surge condition condition. Also known that one of the ways to solve the problem of increasing gas-dynamic stability is the use of casing treatment. However, there are no clearly formulated techniques that allow diagnosing the surge line in an axial compressor with casing treatment. Consequently, the problem of their development is relevant. The paper addresses the results of experimental and computational studies of unsteady flows in an axial compressor with the casing treatment in the form of annular grooves. Specific features of the transition to the regime of rotating stall (with break of the compressor characteristic) by an axial compressor with the annular grooves are formulated. The temporary conditions are provided for the formation of the reliable diagnostic signal of the axial compressor pre-surge operating mode with the annular grooves casing treatment by stabilization of the partial rotating stall condition were displayed. Calculation techniques for estimating informative criteria for detecting of the compressor pre-surge condition were proposed. One of them is the appearance of a discrete component of the amplitude-frequency characteristic of the total pressure pulsations (in the direction of rotation of the rotor) in the cavity of the groove of the casing treatment located above the leading edge of the blades. This discrete component appears at the frequency of a single-zone rotating stall, so it can serve as a trigger pulse for surge prevention automatic control system. The second informative criterion is the appearance of the gradientless region in the distribution of pressure on the bounding wall of the airgas channel above the blade. The position of the gradientless section in the pressure distribution on the bounding wall of the airgas channel above the blade with respect to the meridional projection of the chord of the tip end of the blade has been determined experimentally and by calculation according to the developed technique. Comparison of the proposed mathematical models with experimental data was performed. Their qualitative and quantitative conformity to the experiment were shown.

Suction effect of cavitation in the reverse-spiral-grooved mechanical face seals

Abstract Cavitation suction effect is investigated to control the leakage of the mechanical face seals. A face pattern including the forward, reverse spiral grooves and the annular groove is designed. The cavitation suction effect on the leakage and frictional torque are experimentally studied by a developed experimental setup and its mechanism is disclosed by a numerical model. The results show that the low pressure in the cavitation zone is the root of the suction effect and the cavitation is dependent upon the rotational speeds and loads. The zero leakage or reverse suction is achieved by the cavitation suction effect in a range of rotational speed for the fixed load. The cavitation effectively improves the tribological property of the mechanical seals.

A new species of Brasilotyphlus (Gymnophiona: Siphonopidae) and a contribution to the knowledge of the relationship between Microcaecilia and Brasilotyphlus

A third species of Brasilotyphlus, a siphonopid caecilian, is described based on six specimens from two twin mountains in Roraima state, northern Brazil. Brasilotyphlus dubium sp. nov. differs from all other congeners in having a combination of 123-129 primary annuli and 9-16 secondary annular grooves. The first molecular data were generated and analyzed for Brasilotyphlus, and the genus was recovered as monophyletic and nested within a paraphyletic Microcaecilia. The extent of genetic and taxonomic sampling, and moderate phylogenetic support are not considered sufficient enough to place Brasilotyphlus in the synonymy of Microcaecilia.

Detection of heavy metals in water samples by laser-induced breakdown spectroscopy combined with annular groove graphite flakes

The use of laser-induced breakdown spectroscopy (LIBS) for the analysis of heavy metals in water samples is investigated. Some factors such as splashing, surface ripples, extinction of emitted intensity, and a shorter plasma lifetime will influence the results if the water sample is directly measured. In order to avoid these disadvantages and the ‘coffee-ring effect’, hydrophilic graphite flakes with annular grooves were used for the first time to enrich and concentrate heavy metals in water samples before being analyzed by LIBS. The proposed method and procedure have been evaluated to concentrate and analyze cadmium, chromium, copper, nickel, lead, and zinc in a water sample. The correlation coefficients were all above 0.99. The detection limits of 0.029, 0.087, 0.012, 0.083, 0.125, and 0.049 mg l−1 for Cd, Cr, Cu, Ni, Pb, and Zn, respectively, were obtained in samples prepared in a laboratory. With this structure, the heavy metals homogeneously distribute in the annular groove and the relative standard deviations are all below 6%. This method is very convenient and suitable for online in situ analysis of heavy metals.

УЛУЧШЕНИЕ ТОПЛИВНОЙ ЭФФЕКТИВНОСТИ ГАЗОТУРБИННОГО ДВИГАТЕЛЯ УСТАНОВКОЙ В КОМПРЕССОРЕ НАДРОТОРНОГО УСТРОЙСТВА

The analysis of the influence of annular grooves on the flow in the compressor rotor air gas channel and the axial compressor characteristics as well as on the fuel efficiency of the gas turbine engine is presented. The hypothetical mechanism of the flow effect in the cavity of the annular groove on the main flow in the tip end of the blade air-foil of the axial compressor stage is outlined. The effectiveness of the casing treatment in the form of single annular groove, width is 20% of the axial projection of the chord of the tip end section of the blade is shown experimentally in a single-stage and multi-stage axial compressor system. The increase of the compressor efficiency with ten single annular grooves installed above the leading edges of the blades of each stage, has reduced the specific fuel consumption of the serial GTE in its main operating modes.

Study on the Improvement of Turning Technology for Ring Groove of Flame Tube of Heavy Gas Turbine

This paper takes the flame tube of heavy duty gas turbine with a specific wall thickness of 4.78mm conical cylinder as the researching object, combining with the structure characteristic and material characteristic of the flame tube, carries on the technological analysis to the annular groove turning of the heavy duty gas wheel flame tube. According to the actual working conditions, the machining method of annular grooves in turning is improved, so that the processing cost of annular grooves in flame tubes is greatly reduced, which can be used for reference in actual production.

Reduction of steady flow torques in a single-stage rotary servo valve

In this paper, geometry optimization of spool is proposed to reduce the steady flow torques in a single-stage rotary servo valve. The steady flow torques under different spool structures are studied by computational fluid dynamics simulation and experimental test and the most effective spool structure is found out. Then, the effects of geometry parameters on the steady flow torques are studied and an optimized solution for reduction of the steady flow torques is suggested by considering the optimization qualities and production costs. The results show that modification of the geometry of spool can make the jet angle at the orifices much closer to 90°, with almost no effect on the flow rate. Processing annular groove in the spool land with increased number of grooves on one side of the spool land is an effective way to reduce the steady flow torques. The maximum value of steady flow torques reduces with a gradual decrease in reduction as the external diameter of annular groove and the number of grooves increase. With the optimized spool structure, the maximum value of steady flow torques can be reduced significantly.

Subwavelength diamond gratings for vortex coronagraphy: towards an annular groove phase mask for shorter wavelengths and topological charge 4 designs

Subwavelength diamond gratings for vortex coronagraphy: towards annular groove phase mask for shorter wavelengths and topological charge 4 designs

Residual Stresses Measurement in UIC 60 Rail by Ring-Core Method and Sectioning Technique

The measurement of residual stress in rail foot, according to manufacturing standards is mandatory. In this study, the ring-core method and the sectioning technique are used to measure the residual stresses. A calibration technique for the ring-core method has been explained and simulated by the finite element analysis. The calibration coefficient has been determined for certain parameters and various depths of the annular groove. The ring-core method has been simulated for the uniaxial residual stress field and it is observed that the maximum error in the maximum principal residual stress was about 13% which is about 5% of material yield stress. The residual stresses have been measured at the UIC 60 rail foot by the ring-core method and the sectioning technique, and the results are in a good agreement with earlier investigations in this field. Also, it has been indicated that maximum residual stresses on the rail foot are not in the longitudinal direction and in the subsurface of the rail foot, the maximum principal direction coincides with the longitudinal direction. Both methods indicated tensile residual stresses on the rail foot, but the ring-core method predicted 27% higher longitudinal residual stress on the rail foot in comparing with the sectioning technique.