Layer Technology Research Articles

Microstructure control and hot cracking behavior of the new Ni-Co based superalloy prepared by electron beam smelting layered solidification technology

The prevention of hot cracking formation is of utmost importance in the production of the new Ni-Co based superalloys through the utilization of the electron beam smelting layered solidification technique (EBSL), as it ensures exceptional homogeneity and dependable consistency of the specimens. In contrast to previous studies that focused on minimizing the liquid film and solidification range, our methodology adopts a distinct approach. In this research, a novel methodology was employed to mitigate internal stresses through the implementation of equiaxed grain layers via an alternately reduced cooling method. This ultimately resulted in the elimination of hot cracking. To be more specific, the transition from a columnar to an equiaxed structure was observed during the layer-by-layer construction process in the fabrication of the new Ni-Co based superalloy in EBSL. The EBSL-Ni-Co superalloy, when subjected to the alternating reduction cooling method, exhibited an internal stress of 49 MPa. This value represents a significant reduction of 83.8% compared to the internal stress observed when employing the linear reduction cooling method. Additionally, the solvus temperature of the γ-γ' eutectic phases in EBSL-Ni-Co superalloys produced by the alternating reduction cooling method is significantly higher. Intriguingly, the Nth layer of the EBSL-Ni-Co based superalloys produced by EBSL simultaneously heats treated with the preceding layers. And the low melting point phase gradually dissolved back into the matrix. The implementation of an alternating reduced cooling method successfully mitigated the formation of the liquid film in the γ-γ' eutectic phase and the buildup of internal stresses in the EBSL-Ni-Co superalloy during its manufacturing process. These discoveries open up a novel preparation procedure pathway for the manufacture of crack-free superalloys with superior mechanical characteristics using EBSL.

Analysis of Physical Layer Standard Specifications and Technologies for 5G NR-Unlicensed

Analysis of Physical Layer Standard Specifications and Technologies for 5G NR-Unlicensed

An Efficient Adaptive Data-Link-Layer Architecture for LoRa Networks

LoRa is one of the most popular low-power wireless network technologies for implementation of the Internet of Things, with the advantage of providing long-range communication, but lower data rates, when compared with technologies such as Zigbee or Bluetooth. LoRa is a single-channel physical layer technology on top of which LoRaWAN implements a more complex multi-channel network with enhanced functionalities, such as adaptive data rate. However, LoRaWAN relies on expensive hardware to support these functionalities. This paper proposes a LoRa data-link-layer architecture based on a multi-layer star network topology that adapts relevant LoRa parameters for each end node dynamically taking into account its link distance and quality in order to balance communication range and energy consumption. The developed solution is comprised of multiple components, including a LoRa parameter calculator to help the user to configure the network parameters, a contention-free MAC protocol to avoid collisions, and an adaptive spreading factor and transmission power mechanism. These components work together to ensure a more efficient use of the chosen ISM band and end node resources, but with low-cost implementation and operation requirements.

Thin Cell Layer Tissue Culture Technology with Emphasis on Tree Species

An increased dependency on plant-based resources for food, shelter, and medicinal usage has increased their sustainable and unsustainable exploitation. To use this resource sustainably, plant tissue culture (PTC) is one important technology. Among different PTC techniques, thin cell layer (TCL) technology is a relatively simple and easily adaptable technique for in vitro cultures of plants. This technique uses small explants about 0.5–2 mm in thickness excised from different plant organs. It has been successfully used in the large-scale propagation of vegetables, legumes, and plants with medicinal benefits. TCL technology has proven to be effective in stimulating various organogenic responses when combined with various new methods such as nanotechnology or microtome-based explantation, especially in tree species. It is considered an important tool in plant biotechnology. Although the morphogenetic response per explant is usually higher in conventional explants, the appropriate use of plant growth regulators and geometric factors in TCL has the potential to make it more efficient and beneficial. This article provides an overview of the concept of TCL as applied to different plant species, particularly trees, since there are few, if any, summaries of TCL technology, especially in trees. This review will certainly revitalize this important technology so that it can be used effectively for successful mass propagation in the field of plant tissue culture.

Performance Improvement of InGaN Red Light‐Emitting Diode by Using V‐Pits Layer and Step‐Graded GaN Barrier

The carrier‐transport properties of InGaN red light‐emitting diode (LED) with V‐pits layer and step‐graded GaN barrier are investigated. By using V‐pits layer technology, the inverted pyramid–shaped V‐pit layer forms an energy barrier around the dislocation, inhibits the lateral diffusion of electrons from active layer to the dislocation center, and reduces the probability of non‐radiative recombination rate of electrons and holes. With the increase of the horizontal opening width of the V‐pits layer, the uniformity of holes concentration distribution in InGaN/GaN multiple quantum well (MQWs)‐active region is improved significantly. Compared with the traditional InGaN/GaN MQWs‐active region with fixed well/barrier thickness, step gradient GaN barrier is adopted in the active layer of InGaN red LED, which can reduce the length of the transmission path and improve the injection efficiency of holes into deep quantum wells close to the n‐type region. At injection current density of 200 A cm−2, the internal quantum efficiency of LED D with V‐pits layer and step‐graded GaN barrier is improved by 56.4% as compared with that of reference LED A. In addition, the efficiency droop of LED D can also be effectively alleviated as compared with that of reference LED A.

A Survey on Physical Layer Techniques and Challenges in Underwater Communication Systems

In the past decades, researchers/scientists have paid attention to the physical layer of underwater communications (UWCs) due to a variety of scientific, military, and civil tasks completed beneath water. This includes numerous activities critical for communication, such as survey and monitoring of oceans, rescue, and response to disasters under the sea. Till the end of the last decade, many review articles addressing the history and survey of UWC have been published which were mostly focused on underwater sensor networks (UWSN), routing protocols, and underwater optical communication (UWOC). This paper provides an overview of underwater acoustic (UWA) physical layer techniques including cyclic prefix orthogonal frequency division multiplexing (CP-OFDM), zero padding orthogonal frequency division multiplexing (ZP-OFDM), time-domain synchronization orthogonal frequency division multiplexing (TDS-OFDM), multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM), generalized frequency division multiplexing (GFDM), unfiltered orthogonal frequency division multiplexing (UF-OFDM), continuous phase modulation orthogonal frequency division multiplexing (CPM-OFDM), filter bank multicarrier (FBMC) modulation, MIMO, spatial modulation technologies (SMTs), and orthogonal frequency division multiplexing index modulation (OFDM-IM). Additionally, this paper provides a comprehensive review of UWA channel modeling problems and challenges, such as transmission loss, propagation delay, signal-to-noise ratio (SNR) and distance, multipath effect, ambient noise effect, delay spread, Doppler effect modeling, Doppler shift estimation. Further, modern technologies of the physical layer of UWC have been discussed. This study also discusses the different modulation technology in terms of spectral efficiency, computational complexity, date rate, bit error rate (BER), and energy efficiency along with their merits and demerits.

Teletraffic analysis and simulation on FSO systems: the traffic generators approach

Free Space Optical Communications (FSO) has become an interesting topic to researchers in recent years since the amount of data generated by devices is growing, and it is necessary to use data links that support high bandwidth to transmit them from one device to another. This technology is used to establish not only terrestrial links but also space links.A CubeSat satellite is generally deployed in the Low Earth Orbit (LEO) region. To maintain the altitude, the satellite must have a high orbital speed. For that reason, the time to transmit data between a particular ground station and the CubeSat satellite is limited. On the other hand, the volume, mass, and energy storage capacity are restricted in a CubeSat. The greater the bandwidth capacity of radio frequency links, the greater the demand for volume, mass, and energy they require. For that reason, to transmit a significant amount of data, traditional radio frequency links are not suitable and are becoming replaced by FSO as technology improves.Despite research in physical layer technologies on FSO (modulation schemes, error mitigation techniques, pointing and tracking systems), there is very little research in the literature about data link layer protocols for FSO. Secondly, there is little research to measure the data traffic demand on CubeSat satellites so that a certain data link layer protocol can be selected or adapted to be implemented in an FSO system.This paper presents research to address the issue of teletraffic through the use of traffic generators. The result is the design and development of a traffic generator for a discrete event simulator that will later be used to observe the behavior and to measure the performance of the Selective Repeat ARQ protocol in a simulated satellite FSO link, in order to propose improvements to adapt the protocol to this scenario.

LTE-NBP with holistic UWB-WBAN approach for the energy efficient biomedical application.

Increased use of ultra-wideband (UWB) in biomedical applications based on wireless body area networks (WBAN) opens a variety of options in the field of biomedical research. WBAN may aid in the continuous health monitoring of patients while they go about their everyday lives. Many studies and researchers were conducted several experimentations in the same field for the performance improvement. This study covered the hybridization of UWB technology, as well as on-body, off-body, and human-body ultra-wideband communication (HB-UWB). In this paper, the parameters considered are throughput, energy consumption, energy efficiency, energy used, network survival and delay. An improved model for design and assessment of power-saving UWB-WBAN was developed in this paper. A novel protocol model was introduced in this paper, namely low-power traffic-aware emergency based narrowband protocol (LTE-NBP) to overcome the major drawbacks of emergency, critical data transmission, reliability and the power issues in UWB-WBAN. It's the emergency-based low-power traffic-aware narrowband protocol. It is based on the dual-band physical layer technology. The suggested protocol considered an aware traffic model and an emergency medium access control (MAC) protocol. The proposed model's performance was evaluated and compared with the related algorithms on different performance parameters. The improved model is found to be efficient in throughput, energy efficiency, energy consumption, and delay.

Design and Strengthening of Superhydrophobic Coatings: The Influence of Intermediate Layers

The employment of intermediate layer technology to improve the mechanical stability of superhydrophobic coatings (SHCs) is an acknowledged tool, but the mechanism by which intermediate layers, especially different ones, affect superhydrophobic composite coatings is not clear. In this work, a series of SHCs based on the strengthening of the intermediate layer were fabricated by employing polymers with different elastic moduli such as polydimethylsiloxane (PDMS), polyurethane (PU), epoxy (EP) resin, as well as graphite/SiO2 hydrophobic components. Following that, the effect of different elastic modulus polymers as an intermediate layer on the durability of SHCs was investigated. From the perspective of elastic buffering, the strengthening mechanism of elastic polymer-based SHCs was clarified. Furthermore, from the perspective of self-lubrication, the wear resistance mechanism of self-lubricating hydrophobic components in the SHCs was elucidated. Also, the prepared coatings exhibited excellent acid and alkali resistance, self-cleaning, anti-stain, and corrosion resistance. This work confirms that low-elastic-modulus polymers can also play the role of buffering external impact energy by elastic deformation even as an intermediate layer, and provides theoretical guidance for the development of SHCs with robustness.

Assesment of Effectiveness of Reclamation Activities on Coal Dumps in Kuzbass

The results of assessing the soil-ecological efficiency of reclamation activity on different ages coal dumps in the forest-steppe of Kuzbass are presented. The main physical and chemical soil properties were studied: density, clay fraction and organic carbon in the areas of forestry and agricultural reclamation measures and natural overgrowing. It was revealed that the maximum efficiency achieves by technologies of the fertile layer of natural soils application on the surface of dumps (more over 80% of efficiency).

A Review on Cell-Free Massive MIMO Systems

Cell-free massive multiple-input multiple-output (CF mMIMO) can be considered as a potential physical layer technology for future wireless networks since it can benefit from all the advantages of distributed antenna systems (DASs) and network MIMOs, such as macro-diversity gain, high channel capacity, and link reliability. CF mMIMO systems offer remarkable spatial degrees of freedom and array gains to mitigate the inherent inter-cell interference (ICI) of cellular networks. In such networks, several distributed access points (APs) together with precoding/detection processing can serve many users while sharing the same time-frequency resources. Each AP can be equipped with single or multiple antennas, and hence, can provide a consistently adequate service to all users regardless of their locations in the network. This paper presents a detailed overview of the current state-of-the-art on CF systems. First, it performs a literature review of the conventional CF and scalable user-centric (UC) CF mMIMO systems in terms of the limited capacity of the fronthaul links and the connection between APs and user equipments (UEs). As beyond networks will rely on higher frequency bands, it is of paramount importance to discuss the impact of beamforming techniques that are being investigated. Finally, some of the CF promising enabling technologies are presented to emphasize the main applications in these networks.

A Survey on Nongeostationary Satellite Systems: The Communication Perspective

The next phase of satellite technology is being characterized by a new evolution in non-geostationary orbit (NGSO) satellites, which conveys exciting new communication capabilities to provide non-terrestrial connectivity solutions and to support a wide range of digital technologies from various industries. NGSO communication systems are known for a number of key features such as lower propagation delay, smaller size, and lower signal losses in comparison to the conventional geostationary orbit (GSO) satellites, which can potentially enable latency-critical applications to be provided through satellites. NGSO promises a substantial boost in communication speed and energy efficiency, and thus, tackling the main inhibiting factors of commercializing GSO satellites for broader utilization. The promised improvements of NGSO systems have motivated this paper to provide a comprehensive survey of the state-of-the-art NGSO research focusing on the communication prospects, including physical layer and radio access technologies along with the networking aspects and the overall system features and architectures. Beyond this, there are still many NGSO deployment challenges to be addressed to ensure seamless integration not only with GSO systems but also with terrestrial networks. These unprecedented challenges are also discussed in this paper, including coexistence with GSO systems in terms of spectrum access and regulatory issues, satellite constellation and architecture designs, resource management problems, and user equipment requirements. Finally, we outline a set of innovative research directions and new opportunities for future NGSO research.

Low-Power Circuits and Energy-Aware Protocols for Connecting Batteryless Sensors

Removing batteries from Internet of Things (IoT) devices is a big innovative step toward green operation and sustainability. Batteryless IoT operates by only harvesting the surrounding ambient energy and achieving low environmental impact. As the harvested energy may be irregular and transient, batteryless devices operate intermittently due to frequent arbitrary power failures. Intermittent operation prevents reliable communication among transiently operated IoT devices. Exploiting ultra-low-power physical layer technologies does not guarantee reliable wireless communication since nodes can still fail during data transmission due to the random nature of energy availability. This article presents the main characteristics, challenges, and existing solutions in transiently powered communication, including our recent efforts in this domain. We summarize existing hardware designs and protocol solutions that support overcoming the challenge of intermittent operation during wireless communication. We emphasize that the key insight to achieving reliable communication is to share the energy status of the batteryless nodes, allowing for energy-aware data packet communication. Our experimental results show that energy-aware communication completely avoids data and energy loss due to intermittent operation and enhances the network throughput by three times. Finally, we provide open challenges for future research to draw the attention of the wireless communication community to this new field.

Research Progress on Improving Bending Reliability of Flexible OLED Based on Neutral Layer Technology

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A Real and Accurate Ultrasound Fetal Imaging Based Heart Disease Detection Using Deep Learning Technology

The heart anomalies detection is a significant task in cardiac medical research. The CT, ULTRASOUND, CTA and MRI scans have been used to detect heart diseases but giving false experimental outcomes in longer time of conversion (ToC). Therefore, patients haven’t getting better treatment from doctors. So that in this research work an ultrasound image scan-based heart disease prediction and classification is performed with deep learning technology. The LeNet 10 deep learning classifier has been trained Kaggle dataset using appropriate CNN layers. Proposed CNN LeNet -10 is a 165 layers technology consists of flattened layer, dense layer, convolution layer, max pooling layer and etc. Classification and feature extraction has been performed to loading with LeNet-10 architecture. The real time heart ultrasound test images are collecting from Manipal super specialty hospital Vijayawada, these test features are managed to test.CSV file. In pre-processing step, Ostu segmentation and histogram equalization is applied to make heart ultrasound images to be clear. In Segmentation, edge and region-based convolutional steps are applied such that deep features have been identified. LeNet-10 classification is used to find affected area as well as abnormality location. Finally proposed deep learning with confusion matrix can generating application measures. Implementation has been performed on python 3.9 and DL (Deep learning) packages like TensorFlow, keras, sklearn and etc. The measures like Accuracy 98.37%, sensitivity 97.81%, Recall 98.34% and F1 score 98.98% had been attained, proposed heart disease estimation application is more robust and compete with present technology.

Impermeable Atomic Layer Deposition for Sputtering Buffer Layer in Efficient Semi-Transparent and Tandem Solar Cells via Activating Unreactive Substrate.

Atomic layer deposition (ALD) turns out to be particularly attractive technology for the sputtering buffer layer when preparing the semi-transparent (ST) perovskite solar cells (PSCs) and the tandem solar cells. ALD process turns to be island growth when the substrate is unreactive with the ALD reactants, resulting in the pin-hole layer, which causes an adverse effect on anti-sputtering. Here, p-i-n structured PSCs with ALD SnOx as sputtering buffer layer are conducted. The commonly used electron transportation layer (ETL) PCBM in the p-i-n structured PVK solar cell is an unreactive substrate that prevents the layer-by-layer growth for the ALD SnOx . PCBM layer is activated by introducing reaction sites to form impermeable ALD layers. By introducing reaction sites/ALD SnOx as sputtering buffer layer, the authors succeed to fabricate ST-PSCs and perovskite/silicon (double-side polished) tandem solar cells with power conversion efficiency (PCE) of 20.25% and 23.31%, respectively. Besides, the unencapsulated device with reaction sites maintains more than 99% of the initial PCE after aging over 5100 h. This work opens a promising avenue to prepare impermeable layer for stable PSCs, ST-PSCs, tandem solar cells, and the related scale-up solar cells.

Layered Excavation of the Third Potash Seam with Reduced Thickness of Interlayer Ceiling

The third potash seam of the Starobinsky deposit is mainly mined using the layered mining technology. The essence of the technology lies in the advance excavation of the 4th sylvinite layer by the uppere lava and the joint excavation of layers 2, 2–3 and 3 by the lagging lower lava under the protection of the interlayer pack of rock salt 3–4 (ceiling) left in the goaf. The thickness of the ceiling in accordance with the requirements of the regulatory document should be at least 0.8 m. At the same time, in the mine field of the mine of the Third Mine Administration, there are areas with a ceiling thickness reduced to 0.66–0.70 m. The purpose of the author’s research was to determine the possibility of safe mining of the Third potash seam using the layered mining technology with a reduced thickness of the ceiling. In the course of a full-scale experiment, the geological structure and strength properties of the rocks of the ceiling, its stability in the bottomhole space and the intensity of loading of the bottomhole lining of the lower lavas have been studied in the paper. The research methods also included the analysis of literary sources and statistical processing of the obtained data. It has been established that a decrease in the thickness of the ceiling by 0.10–0.14 m from the required one does not have a significant effect on its strength, while it remains stable in the near-bottom space of the lower longwalls. The main indicators of the manifestation of rock pressure in the studied lower longwalls – the rate of increase of the bottomhole lining in the stope cycles and the lowering of the roof in the bottomhole space – did not exceed the similar indicators in the longwalls with the required thickness of the ceiling. The obtained data indicate the possibility of safemining of the Third potash seam using the layered excavation technology with the thickness of the interlayer rock salt pack 3–4 not less than 0.66 m. In this case, the bearing capacity of the bottomhole lining should be at least 550 kN/m2.

Microstructures and homogenization behavior of a nickel-based superalloy used for 850 ℃ turbine disc prepared by electron beam smelting layered solidification

Electron beam smelting layered solidification technology is applied to prepare a nickel-based superalloy for turbine disks with service temperature up to 850 ℃. The microstructures, segregation and homogenization behavior were investigated. The results show that there is a cellular crystal structure with a width of 1.5 mm between the layers, and the dendritic structure is observed within the layers. The average secondary dendrite arming spacing is 28.6 µm, which attributed to higher temperature of molten pool and faster cooling rate. After electron beam smelting layered solidification technology, the macrosegregation is eliminated, and the microsegregation is weakened. The average temperature on the molten pool surface during electron beam smelting is 1813 K according to evaporation rates of Ni. The effect of homogenization treatment on the microstructures and microsegregation evolution was discussed. Based two diffusion models, the diffusion coefficient of Nb and W at 1190 °C are calculated as 7.365 × 10−16 m2/s and 5.805 × 10−16 m2/s, respectively.

Acoustic radiation performance investigation of a double-walled cylindrical shell equipped with annular plates and porous foam media

Acoustic radiation through a system of double-walled shells, lined with porous foams, and stiffened by annular plates simultaneously is studied. Based on modeling, the porous foams as absorbent fluid property, acoustic characteristics of structure are presented for various sandwich construction by means of vibro-acoustic finite element method with automatic matching layer technology. It is noted that equipping porous foams and annular plates simultaneously enhances the acoustic insulation of structure in the entire frequency domain. The overall sound power level is modified by the density of shell. Moreover, the increase of structural stiffness is shown to effectively reduce the acoustic radiation via rising the thickness of inner shell and the number of annular plates. The foam cores decrease the peak value of structural sound power level through using polyurethane foam cores and increasing filling ratio.

Interference Mitigation and Decoding Through Gateway Diversity in LoRaWAN

Long Range (LoRa) represents an efficient low power solution for the Internet of Things. Specifically, LoRa defines a physical layer technology, while access control and network issues are handled by the LoRaWAN protocol. Channel access is essentially unslotted ALOHA, so LoRaWAN performance suffer from packet collision events. Such problem becomes more penalizing in dense network scenarios, where the large number of devices simultaneously connected makes the collision probability significantly grow. The largest part of solutions proposed to overcome LoRaWAN inefficiency is oriented to collision avoidance. Differently, we firstly present an algorithm for mitigating the interference among superposing LoRa signals, allowing collided packets to be detected anyway. Then, we propose a novel combining mechanism, implemented at the LoRaWAN network server, that exploits the information carried by the same packet, but received by different gateways, to achieve a more robust decoding. Hence, packet detection is reliably performed even in the presence of interference, thus reducing the need of retransmission and providing energy saving for end devices. Furthermore, simulation results show that the proposed solutions allow the end users to transmit exploiting low spreading factors, thus reducing the channel use that will be fundamental when dealing with larger scale network scenarios.