Transmission Configuration Research Articles

Numerical and experimental characterization of twin transmission across grain boundaries along the forward and lateral directions

Pervasive deformation twinning and transmission events across grain boundaries (GBs) affect the strength and failure of hexagonal close-packed (HCP) magnesium. A three-dimensional twin can transmit along the twinning shear direction, η1 (forward), and along the direction perpendicular to both the twinning plane normal and the shear direction, λ (lateral). For the first time, phase-field calculations and electron backscatter diffraction (EBSD)-based statistical analysis are combined to investigate the effect of the twinned grain boundary characteristics on twin transmission (TT) along the forward and lateral directions. This combined analysis reveals that TT propensity decreases with increasing misorientation angle across the GB for both forward and lateral directions. Also, the TT is more favorable along the lateral than along the forward direction. Twin transmission seems harder across GBs with a misorientation axis closer to the twin λ-direction than the other directions (κ1 and η1). Further, the PF calculations reveal that, at the onset of a transmission process, the crystallography tends to be preserved in the case of lateral transmission, whereas, in the forward transmission case, the transmitted twin punches straight through the GBs and its morphology prevails. The EBSD analysis finds that pure forward and lateral transmissions do not occur often, yet reveals a preference for lateral propagation consistent with PF simulations. Further, the local twin transmission configurations observed in the actual material do not correspond to pure tilt or twist GBs, which are most commonly considered as model cases.

6LoWPAN Stack Model Configuration for IoT Streaming Data Transmission over CoAP

Abstract: Different protocols have been developed for the Internet of things (IoT), such as the constrained application protocol (CoAP) for the application layer of the IPv6 over low-power wireless personal area networks (6LoWPAN) stack model. Data transmitted over 6LoWPAN are limited by the throughput and the frame size defined by IEEE 805.14.5 standards. Choosing the best configuration for data transmission involves a trade off between the application requirements, the constrained network configuration, the constrained device specifications and IoT application protocols. This paper provides an analysis of message size and structure recommendations for the 6LoWPAN stack model for different network topologies using CoAP. CoAP is a promising application protocol for the 6LoWPAN stack model because it can effectively manage the transmission required functionality in small header UDP packets compared to TCP packets. However, a data model is also required to realize an effective IoT model. While fragmentation and reassembly are supported by CoAP, they should be avoided for this type of model. As for any conceptual model, a high configuration between layers is mandatory. Additionally, the proposed message format is useful for semantic web of things application development and for WSN design and management.

Forward emission of positronium from nanochanneled silicon membranes

Positronium beam formation and manipulation are required in several fundamental experiments. Efficient positron/positronium conversion in transmission configuration would offer important geometrical advantages over the reflection one for these applications. A novel type of transmission positron/positronium converters, which consists of silicon membranes with pass-through nanochannels, was produced and tested. The amount of forward emitted positronium was studied as a function of the thickness of the membranes and the nanochannel size. A maximum of, at least, $(16\ifmmode\pm\else\textpm\fi{}4)%$ of positrons implanted in $(3.5\ifmmode\pm\else\textpm\fi{}0.5)\ensuremath{-}\ensuremath{\mu}\mathrm{m}$-thick membrane with a nanochannel size of 5--8 nm were found to be forward emitted as positronium. A similar maximum amount of, at least, $(16\ifmmode\pm\else\textpm\fi{}5)%$, was found to be emitted from a membrane $(7.7\ifmmode\pm\else\textpm\fi{}1.3)\ensuremath{-}\ensuremath{\mu}\mathrm{m}$-thick with a nanochannel size of 7--10 nm. A preliminary evaluation shows that the maximum amount of forward emitted positronium with the entire kinetic energy distribution below 1 eV is, at least, 9% of the positrons implanted in the $(3.5\ifmmode\pm\else\textpm\fi{}0.5)\ensuremath{-}\ensuremath{\mu}\mathrm{m}$-thick membrane.

Investigation and performance evaluation of transmitter configurations in urban environment for next generation of wireless communications

Millimeter-wave communications, together with MIMO antenna transmission schemes, have shown its great potential to deal with the increased data requirements for 5G mobile networks. The efficient deployment of these technologies in a dense cellular network environment requires accurate performance prediction for a real-world scenario. In this work impact of inter-site distance, antenna array size, and the center frequency of the transmitter on system performance is evaluated for the urban macrocellular environment. General guidelines for link budget, coverage, and achievable rate are provided. Finally, simulation results from the city center of Kyiv city are shown to align with recently announced 5G standards. Experiments show the existence of an optimal combination of transmitter array size, inter-site distance, and the operating frequency.

Review of the Methods to Optimize Power Flow in Electric Vehicle Powertrains for Efficiency and Driving Performance

Electric vehicles (EV) are quickly gaining a foothold in global markets due to their zero tailpipe emissions and increasing practicality in terms of battery technologies. However, even though EV powertrains emit zero emissions during driving, their efficiency has not been fully optimized, particularly due the commonly used single-speed transmission. Hence, this paper provides an extensive review on the latest works carried out to optimize the power flow in EV powertrains using multispeed discrete transmission, continuously variable transmission and multi-motor configurations. The relevant literatures were shortlisted using a keyword search related to EV powertrain in the ScienceDirect and Scopus databases. The review focused on the related literatures published from 2018 onwards. The publications were reviewed in terms of the methodologies applied to optimize the powertrain for efficiency and driving performance. Next, the significant findings from these literatures were discussed and compared. Finally, based on the review, several future key research areas in EV powertrain efficiency and performance are highlighted.

Recording of Long Low-Amplitude Bulk Elastic Waves in Transparent Solid Waveguides by Digital and Classical Holography

In this paper we compare two implementations of the holographic technique for recording long, nonlinear, elastic waves of low amplitude in solid polymer waveguides: classical holographic interferometry and digital holography. Both implementations are realized in transmission configuration, with recording in the off-axis schematic. The advantages and disadvantages of these implementations are discussed as applied to the investigation of the evolution of shock waves and strain solitons in transparent solid waveguides.

Efficient transmissive remote phosphor configuration for a laser-driven high-luminance white light source.

To realize laser-driven high-luminance white light sources, many reflective configurations have been studied, often resulting in a challenging optical design. In this paper it is demonstrated that the efficacy of a transmissive configuration can be significantly enhanced by using a sapphire half-ball lens as out-coupling optic. This lens not only improves efficiency, but also drastically increases the potential light output due to improved heat dissipation from the single-crystal phosphor converter. Both claims are substantiated with detailed experimental results and realistic opto-thermal simulations, showing a light output of 6550 lm and over 20000 lm, respectively and corresponding luminance of 67 MCd/m2 and 209 MCd/m2.

Transmitter Half Distribution Angle Optimization in Non-Line of Sight Visible Light Communication

Visible light communication is a subset of wireless optical communication that uses white light-emitting diode-based illumination infrastructure for data transmission. Visible light communication (VLC) for indoor communication has recently received much attention to meet the ever-increasing data demands. In VLC, line-of-sight (LOS) connections can provide massive bandwidth while ensuring low path loss if there is an unobstructed path between the transmitter and the receiver, but they are prone to blocking. Non-line of sight (NLOS) links can provide significant blocking resilience and ease of usage by relying on light reflections from the walls, ceiling, and other diffusely reflecting surfaces. Non-line-of-sight optimization is required in VLC to improve receiver optical power and, as a result, system performance. Various studies have been conducted to optimize receiver setups to improve the optical power at the receiver end. In a non-line of sight (NLOS) scenario, however, transmitter configurations significantly impact the received optical power at the detector. The received optical power is spatially non-uniform owing to the scattered trait of white LEDs. This reduces the NLOS link performance. While employing LEDs with a larger half distribution angle minimizes these spatial power fluctuations, it also intensifies reflections from the walls. The more the reflections the more the signal attenuation. In consequence, to improve the receiver optical power in NLOS, this research provides a Transmitter half distribution angle optimization technique, in which the spatial power heterogeneity and the receiver’s mean power gain are recursively estimated for different reflections. The optimization results in a higher mean power gain and reduced spatial power heterogeneity, improving VLC link performance when transmitter and receiver are not in-line.

Active thermography technique for barrier coatings characterization

Aim of this paper is to define and set up an experimental procedure, based on active thermography, for the characterization of thermal barrier coatings for industrial applications, above all in aerospace field. The developed procedure is intended to be a fast and reliable method, alternative to the consolidated one described in International Standards as ISO18755 and ISO18555. In particular, this approach consists of a pulsed active thermography, in transmission configuration, obtained by means of a laser excitation. Temperature data processing, according to and adapting Standard procedures, allowed us to determine thermal parameters as conductivity and diffusivity. Obtained results were compared in terms of thermal properties variation with respect to base and coated materials, and in term of different coating procedures. These results were also compared to those available in literature.

Tailored Magnetic Linear Birefringence in Wedge-Shaped Co Nanocluster Assemblies

The purpose of this paper is to present an experimental method to induce strong magnetic linear birefringence in two-dimensional assemblies of Co nanoclusters grown on glass plates. Additionally, we have also correlated the magnitude and characteristics of that nonlinear magneto-optical effect with the thickness and profile of those disordered nanostructures. For those aims, we have grown Co nanocluster assemblies on amorphous substrates, by means of pulsed laser ablation in off-axis geometry. This approach enabled us to obtain magnetic media with an intended and pronounced thickness profile, i.e., wedge-shaped assembly, to investigate the orientation and behavior of surface magnetization regarding both the thickness gradient direction and in-plane magnetic field. That study was accomplished by measuring the magneto-optical effects in reflection and transmission configurations, unveiling an out-of-plane magnetization whose magnitude depends closely on the thickness gradient direction. That component, arising from a graded magnetic anisotropy along the wedged nanostructure, adds a reversal mechanism to the surface magnetization, thus being responsible for the magnetic linear birefringence in our ultrathin Co assemblies.

Synthesis of multi-input multi-degree-of-freedom fixed shaft gear transmission configuration for vehicles

The rapid development of dual-clutch transmission (DCT) and hybrid and purely electric vehicles stimulate the researches on multi-input fixed shaft gear transmission mechanisms. The multiple degree-of-freedom (DOF) transmission mechanism can achieve a wider range of speed ratio adjustment and more modes under certain space and weight constraints, which is an ideal choice for multi gear transmission. In this paper, a synthesis method of fixed shaft gear transmission configuration is proposed. Based on the established graph theory model, kinematic characteristics of the fixed shaft gear transmission configuration are studied and the shift sequence is determined. Using these characteristics, a derivation method from the basic configuration to the comprehensive gears and shafts configuration is proposed. Multiple parameters such as the synchronizer arrangement and speed ratios are optimized. Finally, the proposed method is vigorously verified by a seven-speed DCT with four DOFs. This method is comprehensive and systematic in designing fixed shaft gear transmission configurations, which can be applied to DCT, transmissions for parallel hybrid electric vehicles, and to some novel multi-input transmissions.

Double Antiresonance Fiber Sensor for the Simultaneous Measurement of Curvature and Temperature.

Antiresonant hollow core fibers (ARHCFs) have gained some attention due to their notoriously attractive characteristics on managing optical properties. In this work, an inline optical fiber sensor based on a hollow square core fiber (HSCF) is proposed. The sensor presents double antiresonance (AR), namely an internal AR and an external AR. The sensor was designed in a transmission configuration, where the sensing head was spliced between two single mode fibers (SMFs). A simulation was carried out to predict the behaviors of both resonances, and revealed a good agreement with the experimental observations and the theoretical model. The HSCF sensor presented curvature sensitivities of −0.22 nm/m−1 and −0.90 nm/m−1, in a curvature range of 0 m−1 to 1.87 m−1, and temperature sensitivities of 21.7 pm/°C and 16.6 pm/°C, in a temperature range of 50 °C to 500 °C, regarding the external resonance and internal resonance, respectively. The proposed sensor is promising for the implementation of several applications where simultaneous measurement of curvature and temperature are required.

A unified optimal power flow modeling for VSC-HVDC converter: a novel methodology for optimal installation based on average loadability index

PurposeThis paper aims to propose a novel methodology for optimal voltage source converter (VSC) station installation in hybrid alternating current (AC)/direct current (DC) transmission networks.Design/methodology/approachIn this analysis, a unified power flow model has been developed for the optimal power flow (OPF) problem for VSC-based high voltage direct current (VSC-HVDC) transmission network and solved using a particle swarm optimization (PSO) algorithm. The impact of the HVDC converter under abnormal conditions considering N-1 line outage contingency is analyzed against the congestion relief of the overall transmission network. The average loadability index is used as a severity indicator and minimized along with overall transmission line losses by replacing each AC line with an HVDC line independently.FindingsThe developed unified OPF (UOPF) model converged successfully with (PSO) algorithm. The OPF problem has satisfied the defined operational constraints of the power system, and comparative results are obtained for objective function with different HVDC test configurations represented in the paper. In addition, the impact of VSC converter location is determined on objective function value.Originality/valueA novel methodology has been developed for the optimal installation of the converter station for the point-to-point configuration of HVDC transmission. The developed unified OPF model and methodology for selecting the AC bus for converter installation has effectively reduced congestion in transmission lines under single line outage contingency.

Design and optimisation of single motor electric powertrains considering different transmission topologies

In this paper, a systematic design approach is presented combining an analytic open-source design method for electrical machines (EM) with a novel transmission design approach tailored for the usage within a holistic powertrain optimisation. This allows a co-optimisation of both the EM and the transmission aiming at a globally optimal powertrain system for battery electric vehicles (BEVs). To systematically synthesise transmissions, basic elements are defined, which can be connected individually. Additionally, a generic transmission loss model is introduced allowing to account for transmission losses based on the design approach. Using this methodology, two one-speed and one two-speed transmission configurations are synthesised and optimised in a case study. Applying a multi-objective genetic algorithm, both EM and transmission parameters are optimised aiming at minimal electrical energy consumption and minimal powertrain cost. The results show that the optimal powertrain configuration is sensitive to both EM and transmission design parameters, demonstrating that a comprehensive co-optimisation is necessary to obtain globally optimal electric powertrain solutions.

Spherical wavefront measurement on modified cyclic radial shearing interferometry.

We propose a radial shearing interferometric approach to measure spherical wavefronts as both of the reflective and transmissive optical configurations. The modified cyclic radial shearing interferometer uses a single lens in the optical layout, which can conveniently adjust the radial shearing ratio between two shearing spherical wavefronts, and the use of a polarization camera enables to reconstruct the wavefront by a single image. The wavefront mapped onto the camera plane can be identified and quantified throughout an optimized wavefront reconstruction algorithm. In the experiments, plano-convex lenses and concave mirrors were used to generate spherical wavefronts, and the proposed system was able to reconstruct the surface figures after system characterization and calibration. Further investigations were performed to evaluate the system measurement accuracy by the radius of curvature comparison with design value and a commercial Shack-Hartmann wavefront sensor.

Minimum Length Scheduling for Multi-Cell Full Duplex Wireless Powered Communication Networks.

Wireless powered communication networks (WPCNs) will be a major enabler of massive machine type communications (MTCs), which is a major service domain for 5G and beyond systems. These MTC networks will be deployed by using low-power transceivers and a very limited set of transmission configurations. We investigate a novel minimum length scheduling problem for multi-cell full-duplex wireless powered communication networks to determine the optimal power control and scheduling for constant rate transmission model. The formulated optimization problem is combinatorial in nature and, thus, difficult to solve for the global optimum. As a solution strategy, first, we decompose the problem into the power control problem (PCP) and scheduling problem. For the PCP, we propose the optimal polynomial time algorithm based on the evaluation of Perron–Frobenius conditions. For the scheduling problem, we propose a heuristic algorithm that aims to maximize the number of concurrently transmitting users by maximizing the allowable interference on each user without violating the signal-to-noise-ratio (SNR) requirements. Through extensive simulations, we demonstrate a 50% reduction in the schedule length by using the proposed algorithm in comparison to unscheduled concurrent transmissions.

The influence of Unified Power Flow Controller to increase the value of Available Transfer Capability on transmission system Java – Bali, Indonesia

Industrial growth and population in Indonesia led to an increase in demand for electricity. It needs a device that can perform a voltage correction profile online so that power will flow through transmission line. TJBTB (Transmisi Jawa Bagian Timur dan Bali) conditions before the installation of UPFC (Unified Power Flow Controller), the power supply received by the load is not 100% obtained from plants in the region, for example the Paiton power plant. In this research, the method used is with the help of MATLAB R2014a simulation by designing a 500 kV transmission system configuration and the placement of the UPFC found in regional IV namely East Java - Bali. From the simulation results, showing that there was a change in power flow when placing the UPFC. The right location is the West Surabaya - Gresik channel. On the Ngimbang bus there is a change in active power which before using UPFC by 1612 MW to 2208 MW after using UPFC, an increase in active power was 36.97%. The UPFC can fulfill all these functions and thereby meet multiple control objectives by adding the injected voltage with appropriate amplitude and phase angle, to the terminal voltage v.

Flexible and directional fibre optic ultrasound transmitters using photostable dyes.

All-optical ultrasound transducers are well-suited for use in imaging during minimally invasive surgical procedures. This requires highly miniaturised and flexible devices. Here we present optical ultrasound transmitters for imaging applications based on modified optical fibre distal tips which allow for larger transmitter element sizes, whilst maintaining small diameter proximal optical fibre. Three optical ultrasound transmitter configurations were compared; a 400 µm core optical fibre, a 200 µm core optical fibre with a 400 µm core optical fibre distal tip, and a 200 µm core optical fibre with a 400 µm core capillary distal tip. All the transmitters used a polydimethylsiloxane-dye composite material for ultrasound generation. The material comprised a photostable infra-red absorbing dye to provide optical absorption for the ultrasound transduction. The generated ultrasound beam profile for the three transmitters was compared, demonstrating similar results, with lateral beam widths <1.7 mm at a depth of 10 mm. The composite material demonstrates a promising alternative to previously reported materials, generating ultrasound pressures exceeding 2 MPa, with corresponding bandwidths ca. 30 MHz. These highly flexible ultrasound transmitters can be readily incorporated into medical devices with small lateral dimensions.

Demonstration of Faraday anomalous dispersion optical filter with reflection configuration

A narrow linewidth Faraday anomalous dispersion optical filter (FADOF) with reflection configuration is achieved for the first time based on the cesium (Cs) ground state 6S1/2 to the excited state 6P3/2 transition at 852 nm. Compared with the conventional FADOF with transmission configuration, reflection-type FADOF can greatly improve the transmittance of optical filter under the same experimental parameters, because it allows signal light to go and return through the atomic vapor cell. In our experiment, peak transmittance at Cs 6S1/2 F = 4–6P3/2 transition is 81% for the reflection-type FADOF, and while 54% for the transmission-type FADOF when the temperature of Cs vapor cell and the axial magnetic field are 60 °C and 19 G. The idea of this reflection-type FADOF design has the potential to be applied to the FADOF operating between two excited states to obtain higher transmittance.

Data Efficient Estimation for Quality of Transmission Through Active Learning in Fiber-Wireless Integrated Network

Quality of Transmission (QoT) estimation, where the received signal quality is predicted before deployment, plays a significant role in efficient resource utilization, such as determining the optimal transmission configuration. Traditionally, it is implemented with analytical models, and often accompanied by large link margins to account for the low estimation accuracy. Machine learning (ML) based methods have been recently demonstrated as an alternative solution with high accuracy. However, they require a large number of training data, which is often expensive to obtain in the context of QoT estimation. In this paper, we use active learning (AL) to achieve data efficient QoT estimation. A learner actively selects the training data to be labeled by applying the strategy of uncertainty sampling which favors data with high model uncertainty. A data selection algorithm compatible with the widely studied artificial neural network (ANN)-based QoT estimator is proposed and experimentally demonstrated in a fiber-wireless integrated testbed. Monte Carlo dropout (MC dropout) is utilized to calculate model uncertainty. To achieve a mean squared error (MSE) of 0.055, the number of training data can be reduced by more than 25% compared with the conventional passive ML. The algorithm is also investigated under different sampling settings and the impact of hyperparameters is discussed.