Ring Spacing Research Articles

Acoustic black hole optimization

Acoustic black holes have a tapering profile to create the idealized phenomenon of zero reflection. This phenomenon relies on geometry instead of dampers, so it is an ideal way to remove vibrations without increasing mass or surface area. They can attenuate acoustic and structural vibrations for applications in air, space, ground, and marine vehicles and can be produced in ducts, beams, plates, and wedges. The phenomenon entails wave propagation in an ideal medium where the profile tapers according to the power law shortening the wavelength and decreasing the wave speed. Consequently, the wave’s travel time goes to infinity so that it never reaches the termination and cannot be reflected—creating complete absorption. For the application of a circular duct, thin annular rings of inner radii decrease with the power law to control pressure levels. An infinite number of rings and a final cross sectional area of zero are needed to create an ideal acoustic black hole and is impossible to achieve. However, imperfections create scattering and other losses that increase damping performance. Therefore, various configurations need to be tested to tune parameters such as the amount, thickness, and spacing of tapering rings to produce minimal reflection across a frequency spectrum.

Study on the influence of connection ring on the stability of assembly columns applied in demountable structures

The aluminum alloy assembly column is a demountable component composed of four tubes and connection joints. The design of this column is based on the concept of assembling large components with small ones, which can be operated manually by one or two people. This paper presents influence of connection ring on the stability of assembly columns by experimental and numerical method. The axial stability tests were conducted to obtain the failure modes and strain distributions of columns. The numerical model, which was suitable for parametric analysis of the assembly column, was conducted. The ultimate strength and failure modes obtained from the test results validated the numerical predictions. The parametric analysis of columns with two connection rings was conducted, which identified the influences of connection ring spacing and tube spacing on ultimate bearing capacity of the assembly column. The optimal connection ring location was found. The quantitative calculation method of stability capacity of the column was obtained via the computation of thousands of models. The formula took the influences of the connection ring spacing, tube spacing and the column height into account, which could help guide the design of assembly columns and enlarge the scope of potential applications for demountable structures.

Design and Fabrication of 1.2 kV/10A 4H-SiC Junction Barrier Schottky Diodes with High Current Density

This paper presents an overall optimization procedure and the electrical performances of 1.2 kV/10 A 4H-SiC junction barrier Schottky (JBS) diodes with high current density. To achieve high current density, the epi-layer, the design parameters for active region including p-grid width and cell pitch, and the field limiting ring for edge termination were optimized with analytic calculation to estimate forward electrical performances and with Silvaco atlas™ simulator to estimate reverse electrical performances. Based on the systematic design, the JBS diodes were fabricated and electrically characterized. The experimental results showed that the breakdown voltage (BV) of JBS diode was significantly sensitive to field limiting ring (FLR) space and that the JBS diode with the ratio of pure Schottky contact area to total active area of 0.75 and the FLR space of 1.25 μm had optimum electrical performances such as a forward current density of 370 A/cm2, a reverse leakage current below 20 μA at the reverse anode voltage of 1.2 kV, and the BV of 1400 V. These were in coincidence with the simulation results within 10% error.

Three-dimensional finite element modeling and theoretical analysis of concrete confined with FRP rings

The confinement mechanism of concrete fully confined with fiber-reinforced polymer (FRP) jacket (FRP jacketed concrete) is different from that of concrete partially confined with FRP (i.e., FRP ring-confined concrete and FRP tie-confined concrete) in that the confinement in the latter is non-uniform along the longitudinal direction. In order to build a bridge between FRP jacketed concrete and FRP ring/tie-confined concrete, the current design of concrete confined with FRP rings/ties relies on the “arching action” assumption, which is not necessarily accurate as it was proposed for concrete confined with steel stirrups. Moreover, the arching action assumption usually adopts a hypothesis that the arching action angle equals to 45°, which has not been verified by any theoretical or experimental evidence. To this end, a revised analysis model has been implemented in an advanced finite element (FE) approach to study the axial stress distributions in concrete confined with FRP rings. The stress distribution at the center level of two adjacent FRP rings/ties is obtained, and the relationship between the arching action angle and controlling parameters (i.e., unconfined concrete strength, FRP width, FRP thickness and clear spacing of FRP rings) is established based on a proposed theoretical model of arching action angle. A new confinement effectiveness coefficient is then proposed, leading to a much more reliable prediction of the FRP ring-confined concrete in circular columns. The results presented in the current study can be easily extended to the concrete columns internally reinforced with FRP ties/spiral.

Analysis of tunnel face stability with advanced pipes support

To keep the tunnel face stable is very important for tunnel construction. In this paper, the tunnel face stability under the advanced pipe was analyzed using the Winkler foundation model and rigid limit equilibrium. The tunnel face deformation characteristics were also analyzed using the numerical simulation. The influence of parameters on the deflection of the pipe roof and the stability of the tunnel face were discussed. The results show that the tunnel face stability can be improved through increasing the pipe diameter, decreasing the initial displacement at the beginning of the pipe seat, and adopting the short round length and small excavation height. With the increase of tunnel burial depth, the safety factor of tunnel face stability first decreases, then increases, and then remains unchanged. The deformation at the center of the tunnel face is larger than the deformation at the surround sides and at the corner. The horizontal displacement varies little with the increasing of the pipe length. The horizontal displacement at the center of the tunnel face increases with the increase of the pipe ring spacing and the pipe longitudinal spacing. There is an optimum external angle.

A Potential Plasmonic Biosensor Based Asymmetric Metal Ring Cavity with Extremely Narrow Linewidth and High Sensitivity.

To achieve high sensitivity and multi-mode sensing characteristics based on the plasmon effect, we explored a high-sensitivity refractive index sensor structure with narrow linewidth and high absorption characteristics based on theoretical analysis. The sensor structure is composed of periodic asymmetric ring cavity array, spacer layer and metal thin-film layer. The reflection spectrum of this structure shows six resonance modes in the wavelength range from visible to near-infrared. The sensor performance was optimized based on the change of the sensor structure parameters combining the simulation data, and the results shown that this kind of asymmetric laminated structure sensor has good sensing performance. In theory, it can be combined with microfluidic technology to achieve sensing detection of diverse test samples, multi-mode and multi-component, which has great potential in the field of biosensing.

Ergonomic Evaluation of Orchard Ladders with Shorter Rung Spacing

Falls from ladders continue to be a concern in orchard work. Standard ladder design per the American National Standards Institute utilizes 30.5 cm (12-inch) rung spacing, which is the distance between steps along the rails. The European standard provides for a range of 25.0 to 30.0 cm (9.8 to 11.8 inches). This paper reports on a laboratory study of five tripod-style ladders, one with standard rung spacing and four with incrementally shorter spacing of 12.7 mm (0.5 inches). The ladders were positioned at 72 degrees, as well as at shallower 68 and 64 degree orientations. The average increased heart rate was lowest for the 26.7 cm (10.5 inch) rung spacing. Electromyography, motion, and ratings of perceived exertions were also collected. No test subject chose the standard ladder at any angle as their most preferred. The preliminary findings of this study support the reconsideration of the standard 12” orchard ladder.

Design and Fabrication of Non-Uniform Spacing Multiple Floating Field Limiting Rings for 6500V 4H-SiC JBS Diodes

Designed for 6500V 4H-SiC JBS diodes, a highly-efficient termination structure of a non-uniform multiple floating field limiting rings (MFFLR) featuring with a non-uniform ring spacing and a multiple region division is studied and purposed. For each region, ring spacing is modulated independently by a multiplication factor and a linear increment factor. The non-uniform MFFLR structure is simulated and optimized for a better electric field distribution and a higher breakdown voltage. Based on the simulation results, 4H-SiC JBS diodes with the optimized non-uniform termination designs are fabricated. Experimental results show that the SiC JBS diode with optimized non-uniform MFFLR termination structure can achieve a breakdown voltage of up to 7800 V, and its termination efficiency is about 94% of an ideal parallel-plane junction’s. Our results demonstrate that the optimized non-uniform MFFLR termination structure is capable for SiC JBS diodes with breakdown voltage of 6500V and above. Our results can provide a valuable design methodology of edge termination structures for other high-voltage SiC devices.

An investigation of FinFET single-event latch-up characteristic and mitigation method

FinFET technology compared with planar have an increased sensitivity to single-event latch-up. TCAD simulation demonstrates that the reduction in width of MOSFET, thickness of shallow trench isolation (STI) and nMOS-to-pMOS lateral spacing will reduce the holding voltage, critical charge and increase the current gain of parasitic CMOS Silicon Controlled Rectifier (SCR). Through circuit analysis, it found that the change of parasitic vertical and horizontal resistance is mainly responsible for aforementioned phenomena. In addition, we found that the common protective measures such as guard rings spacing and epitaxial substrate become increasingly difficult. Based on the current preventive methods, we think that appropriate increasing the doping depth or the width of guard rings will improve protection from Single-Event Latch-up (SEL). Moreover, we verify the effectiveness of our methods by TCAD simulation and discuss the feasibility.

Influence of Graphene Oxide on Rheological Parameters of Cement Slurries

In recent years, graphene-based nanomaterials have been increasingly and widely used in numerous industrial sectors. In the drilling industry, graphene oxide in cement slurry has significantly improved the mechanical parameters of cement composites and is a future-proof solution. However, prior to placing it in a borehole ring space, cement slurry must feature appropriate fluidity. Graphene oxide has a significant influence on rheological parameters. Therefore, it is necessary to study graphene oxide’s influence on the rheological parameters of cement slurries. Thus, this paper presents rheological models and the results of studies on rheological parameters. A basic cement slurry and a slurry with a latex addition were used. The latex admixture was applied at concentrations of 0.1%, 0.03%, and 0.06%. In total, studies were carried out for six slurries with graphene oxide and two basic slurries. The obtained results of studies on the slurries with graphene oxide were compared with the control slurry. It was found that the smallest graphene oxide concentration increased slurry value, some rheological parameter values, plastic viscosity, and the flow limit. Surprisingly, a concentration up to 0.03% was an acceptable value, since the increase in plastic viscosity was not excessively high, which allowed the use of cement slurry to seal the hole. Once this value was exceeded, the slurry caused problems at its injection to the borehole.

Design and Experimental Verification of 434 MHz Phased Array Applicator for Hyperthermia Treatment of Locally Advanced Breast Cancer

Design and experimental verification of a phased array (PA) of 434 MHz water-loaded cavity-backed patch antennas is presented for hyperthermia treatment (HT) of locally advanced breast cancer (LABC). A staggered annular array of 18 antennas distributed across three rings with six antennas per ring and 40 mm ring spacing is presented for HT. The applicator performance is assessed on three-layered breast models of varying volumes (133–1286 cm3) with 64 cm3 tumor target at three different locations in the individual breast model, and an anatomically realistic patient model with LABC (46 cm3) in the upper outer quadrant. HT indicators for the optimized applicator indicated average power absorption ratio (aPAratio) ≥ 3.93 and 10.48, and hotspot to target quotient (HTQ) ≤ 1.34 and 1.08 in the large and small breast models, respectively. aPAratio and HTQ were 6.14 and 1.23 in the anatomically realistic model, respectively. Simulation results were experimentally verified on a 3-D phantom fabricated based on the patient model with thermo-dielectric properties of breast tissues. Temperature rise of 6.04 °C, 6.55 °C, and 5.5 °C measured for centered and two off-centered tumor locations in the phantom for 20 min heating, respectively, were in excellent agreement with the simulations without any significant healthy tissue hotspots.

Aromaticity study of heterocyclic anticancer compounds through computational s-nics method

In this study, we have sujessted a theoritical aproach via computing of nucleus-independent chemical shifts (S-NICS) in view point of probes motions in a sphere of de-shielding and shielding spaces of rings of anticancer contain heterocyclic rings. Few research in theoretical of a statistical approach in NMR shielding and nucleus independent chemical shifts for study of anticancer drugs. S-NICS method is an accurate method for estimation the amount of aromaticity in the non-benzene rings such as heterocyclic rings which is a famous for organic chemical compounds as anti-cancer disease. Theoretical of a statistical method of NICS-nucleus independent chemical shift in small distance and are alternate in large distance in the center of heterocyclic rings. In this research, we have explored the statistical approaches through nucleus-independent chemical shifts-SNICS calculations in view point of Bq motions in the center of sphere spaces of heterocyclic rings of some anticancer drugs. The S-NICS method is an accurate computing method for estimation the aromaticity in the non-benzene rings such as heterocyclic rings which are standard molecules in organic anti-cancer compounds. Although NICS values for benzene and naphthalene and so on can be indicated as aromaticity criterion, for other molecules such as heterocyclic rings and their derivatives, S-NICS values are much more accurate compare to NICS index. Hetrocyclic compound with good π stacks are good cacdidate for anticancer medicines. Precence of Nitrogen, oxygen and sulfur in these compounds make them similar biochemical parts such as nuclice acids and. Aromaticity of heterocyclic ring. This similarity especially them π stacks give the the ability of interaction with DNAs and RNAs and the heterocyclic compounds.

Formation of Deposition Patterns Induced by the Evaporation of the Restricted Liquid.

Evaporation-induced self-assembly of colloids or suspensions has received increasing attention. Given its critical applications in many fields of science and industry, we report deposition patterns constructed by the evaporation of the restricted aqueous suspension with polystyrene particles at different substrate temperatures and geometric container dimensions. With the temperature increases, the deposition patterns transition from honeycomb to multiring to island, which is attributed to the competition between the particle deposition rate UP and the contact line velocity UCL, and the dimension of the geometric container has an effect on the characteristics of patterns. In this paper, the formation of an ordered multiring pattern is mainly focused on as a result of UP keeping up with UCL such that the entire contact line can be pinned, that is, the periodic stick-slip motion of the contact line and the particle sedimentation. Moreover, based on the Onsager principle, we develop a theoretical model to reveal the physical mechanisms behind the multiring phenomena. The position and spacing of rings are measured, which shows that the theoretical prediction agrees well with experiments. We also find that the ring spacing decays exponentially from center to edge experimentally and theoretically. This may not only help us to understand the formation of the deposition patterns but also assist future design and control in practical applications.

Design and Development of Ladder Climbing Robot

This paper presents the development of a ladder climbing robot prototype. The development of the prototype includes constructing the basic software and hardware for the robot. The robot controller is designed using Arduino Mega 2560 software implemented in Arduino IDE with C programming. The hardware development involves constructing the main chassis and climbing arm with servomotor, DC geared motor and motor driver. An algorithm to climb ladder is developed with application of Infrared (IR) sensor and ultrasonic sensors. Significantly, the robot prototype is tested on ladders of different rung spacing. In the future, a base with wheels will be constructed for the robot to carry load and move on ground with obstacle avoidance capability and side grippers will be constructed to improve climbing performance of the robot on vertical ladder; this project will contribute to future research on similar topics.

A Novel Three-Phase Tubular Switched Reluctance Linear Machine With Transverse-Flux Path

Several tubular switched reluctance linear machines (TSRLMs) with transverse flux are proposed for improving thrust density recently. Owing to the particularity of the structure of transverse-flux TSRLMs, how to maximize the electrical utilization becomes a key to improve these machines’ performance. A novel three-phase transverse-flux TSRLM is proposed in this paper, whose stator sleeve is composed of six ferromagnetic rings and five spacer rings. And the mover is composed of an aluminum tube and several fan-shaped poles. The adjacent fan-shaped poles are placed at 120 degree intervals. In the novel structure, each half of the windings corresponding to a phase constitute a single coil without the need of intermediate connections. This winding way avoids the limitation of stator ferromagnetic ring spacing, and increases the space for wire placement compared with the other existing transverse-flux TSRLMs. In order to verify the superiority of the novel TSRLM, a conventional transverse-flux TSRLM which has the same volume and main dimensions is presented to compare their performances. Finally, the finite element calculation results show that the average thrust per unit core mass of proposed TSRLM is greater than conventional TSRLM, which shows its superiority for speed control systems. It proves that the novel structure can help increasing the use of TSRLMs.

Enhancement of unidirectional excitation of guided torsional T(0,1) mode by linear superposition of multiple rings of transducers

The higher performance of the guided wave technique for non-destructive testing (NDT) and structural health monitoring (SHM) on large-scale engineering structures is still a requirement in industries. In this paper, the unidirectional excitation function of guided waves by adding many rings of transducers (even or odd number) is described to enhance the wave power output of the inspection system. A parametric analysis based on the wave superposition is developed to predict the maximum power output amplitudes depending on varied ring spacings between the transducer arrays in the different centre frequencies. The proposed approach is tested numerically and then validated through an experiment in which torsional wave mode T(0,1) is excited in a pipe by one, two and three rings of 24 transducers operating in time-delays and different amplitude factors. The performance of transducer arrays for increasing the power output of excitation in the forward direction and cancelling signals in the reserve direction has been evaluated using experimental measurements.

Derived Categories of Finite Spaces and Grothendieck Duality

We obtain some fundamental results, as Bokstedt–Neeman Theorem and Grothendieck duality, about the derived category of modules on a finite ringed space. Then we see how these results are transferred to schemes in a simple way and generalized to other ringed spaces.

On Mixed Fuzzy Topological Ring

The theory of fuzzy topological ring has wide scope of applicability than order topological ring theory. The reason is fuzzy can provide better result. Therefore, fuzzy topological ring has been found in Robotics, computer, artificial intelligent, etc. In this paper, we induce mixed fuzzy topological ring space and fuzzy neighborhoods system of mixed fuzzy topological ring space. Also, we study fuzzy continuity of mixed fuzzy topological ring.

Design of magnetic circuit and extraction system of ECR ion source for intense neutron tube

The magnetic circuit and extraction system were optimized to improve the utilization of neutral gas and neutron yield of a sealed intense neutron tube. An experimental system was established to study the relationship between microwave absorption efficiency and the magnetic field strength. The microwave absorption efficiency can reach 100% when the magnetic field intensity at the microwave window is 0.095 T. To further improve the distribution of ECR region, CST was used to simulate the internal magnetic field distribution of the ion source. The radial and axial magnetization results with the single and double magnetic rings were obtained by changing the position and spacing of the magnetic rings. There are three ECR regions and the location of ECR zones is suitable, when the distance between the center of the magnetic ring and the origin of the resonator is 12.5 mm and the distance between the centers of the two magnetic rings is 60 mm. A two-electrode slit extraction system was designed for uniform beam distribution on target. Compared with the original extraction system, the maximum current density is reduced by 82.5% and the target utilization area is increased by 38.54%, which will effectively reduce the thermal load of the target.

LIPUS far-field exposimetry system for uniform stimulation of tissues in-vitro: development and validation with bovine intervertebral disc cells

Therapeutic Low-intensity Pulsed Ultrasound (LIPUS) has been applied clinically for bone fracture healing and has been shown to stimulate extracellular matrix (ECM) metabolism in numerous soft tissues including intervertebral disc (IVD). In-vitro LIPUS testing systems have been developed and typically include polystyrene cell culture plates (CCP) placed directly on top of the ultrasound transducer in the acoustic near-field (NF). This configuration introduces several undesirable acoustic artifacts, making the establishment of dose-response relationships difficult, and is not relevant for targeting deep tissues such as the IVD, which may require far-field (FF) exposure from low frequency sources. The objective of this study was to design and validate an in-vitro LIPUS system for stimulating ECM synthesis in IVD-cells while mimicking attributes of a deep delivery system by delivering uniform, FF acoustic energy while minimizing reflections and standing waves within target wells, and unwanted temperature elevation within target samples. Acoustic field simulations and hydrophone measurements demonstrated that by directing LIPUS energy at 0.5, 1.0, or 1.5 MHz operating frequency, with an acoustic standoff in the FF (125–350 mm), at 6-well CCP targets including an alginate ring spacer, uniform intensity distributions can be delivered. A custom FF LIPUS system was fabricated and demonstrated reduced acoustic intensity field heterogeneity within CCP-wells by up to 93% compared to common NF configurations. When bovine IVD cells were exposed to LIPUS (1.5 MHz, 200 μs pulse, 1 kHz pulse frequency, and ISPTA = 120 mW cm−2) using the FF system, sample heating was minimal (+0.81 °C) and collagen content was increased by 2.6-fold compared to the control and was equivalent to BMP-7 growth factor treatment. The results of this study demonstrate that FF LIPUS exposure increases collagen content in IVD cells and suggest that LIPUS is a potential noninvasive therapeutic for stimulating repair of tissues deep within the body such as the IVD.