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Keywords = bi-directional gain amplifier

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33 pages, 9805 KiB  
Article
Fluid–Structure Interaction Study in Unconventional Energy Horizontal Wells Driven by Recursive Algorithm and MPS Method
by Xikun Gao, Dajun Zhao, Yi Zhang, Yong Chen, Zhanzhao Gao, Xiaojiao Zhang and Shengda Wang
Appl. Sci. 2025, 15(12), 6743; https://doi.org/10.3390/app15126743 - 16 Jun 2025
Viewed by 314
Abstract
With the unconventional energy sector (e.g., shale gas) increasingly focused on precision drilling and cost-effective extraction, slim-hole horizontal well technology is gaining prominence. However, drill string dynamics in narrow, complex fluid environments are not fully understood. This study presents a novel bidirectional fluid–structure [...] Read more.
With the unconventional energy sector (e.g., shale gas) increasingly focused on precision drilling and cost-effective extraction, slim-hole horizontal well technology is gaining prominence. However, drill string dynamics in narrow, complex fluid environments are not fully understood. This study presents a novel bidirectional fluid–structure interaction (FSI) model, uniquely integrating recursive algorithms with the Moving Particle Semi-implicit (MPS) method to couple drill string–wellbore contact with drilling fluid interactions. Key findings show that drilling fluid significantly impacts drill string behavior; for instance, it can reduce natural frequencies by 20–25%, while stiff formations amplify lateral resonance risks. Optimizing fluid properties can substantially cut energy losses, though TREE is marginally elevated when viscosity exceeds the threshold (2.5 × 10−5 m2/s). The drill string typically displaces rightward, but higher viscosity can shift it left; a moderate friction coefficient aids centering. Excessive lateral displacement impairs cuttings removal, affecting fracturing. These insights enable actionable strategies: adjusting fluid viscosity and drag reducers can optimize drill string position and enhance cleaning. This research provides a framework for energy-efficient drilling in complex reservoirs, balancing efficiency with wellbore integrity and improving outcomes in the unconventional energy sector. Full article
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9 pages, 2057 KiB  
Communication
Linear Fiber Laser Configurations for Optical Concentration Sensing in Liquid Solutions
by Liliana Soares, Rosa Ana Perez-Herrera, Susana Novais, António Ferreira, Susana Silva and Orlando Frazão
Photonics 2024, 11(5), 393; https://doi.org/10.3390/photonics11050393 - 24 Apr 2024
Cited by 1 | Viewed by 1449
Abstract
In this study, different configurations based on linear fiber lasers were proposed and experimentally demonstrated to measure the concentration of liquid solutions. Samples of paracetamol liquid solutions with different concentrations, in the range from 52.61 to 201.33 g/kg, were used as a case-study. [...] Read more.
In this study, different configurations based on linear fiber lasers were proposed and experimentally demonstrated to measure the concentration of liquid solutions. Samples of paracetamol liquid solutions with different concentrations, in the range from 52.61 to 201.33 g/kg, were used as a case-study. The optical gain was provided by a commercial bidirectional Erbium-Doped Fiber Amplifier (EDFA) and the linear cavity was obtained using two commercial Fiber Bragg Gratings (FBGs). The main difference of each configuration was the coupling ratio of the optical coupler used to extract the system signal. The sensing head corresponded to a Single-Mode Fiber (SMF) tip that worked as an intensity sensor. The results reveal that, despite the optical coupler used (50:50, 60:40, 70:30 or 80:20), all the configurations reached the laser condition, however, the concentration sensing was only possible using a laser drive current near to the threshold value. The configurations using a 70:30 and an 80:20 optical coupler allowed paracetamol concentration measurements with a higher sensitivity of (3.00 ± 0.24) pW/(g/kg) to be performed. In terms of resolution, the highest value obtained was 1.75 g/kg, when it was extracted at 20% of the output power to the linear cavity fiber laser configuration. Full article
(This article belongs to the Special Issue Single Frequency Fiber Lasers and Their Applications)
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22 pages, 9068 KiB  
Article
YOLO-BLBE: A Novel Model for Identifying Blueberry Fruits with Different Maturities Using the I-MSRCR Method
by Chenglin Wang, Qiyu Han, Jianian Li, Chunjiang Li and Xiangjun Zou
Agronomy 2024, 14(4), 658; https://doi.org/10.3390/agronomy14040658 - 24 Mar 2024
Cited by 19 | Viewed by 2689
Abstract
Blueberry is among the fruits with high economic gains for orchard farmers. Identification of blueberry fruits with different maturities has economic significance to help orchard farmers plan pesticide application, estimate yield, and conduct harvest operations efficiently. Vision systems for automated orchard yield estimation [...] Read more.
Blueberry is among the fruits with high economic gains for orchard farmers. Identification of blueberry fruits with different maturities has economic significance to help orchard farmers plan pesticide application, estimate yield, and conduct harvest operations efficiently. Vision systems for automated orchard yield estimation have received growing attention toward fruit identification with different maturity stages. However, due to interfering factors such as varying outdoor illuminations, similar colors with the surrounding canopy, imaging distance, and occlusion in natural environments, it remains a serious challenge to develop reliable visual methods for identifying blueberry fruits with different maturities. This study constructed a YOLO-BLBE (Blueberry) model combined with an innovative I-MSRCR (Improved MSRCR (Multi-Scale Retinex with Color Restoration)) method to accurately identify blueberry fruits with different maturities. The color feature of blueberry fruit in the original image was enhanced by the I-MSRCR algorithm, which was improved based on the traditional MSRCR algorithm by adjusting the proportion of color restoration factors. The GhostNet model embedded by the CA (coordinate attention) mechanism module replaced the original backbone network of the YOLOv5s model to form the backbone of the YOLO-BLBE model. The BIFPN (Bidirectional Feature Pyramid Network) structure was applied in the neck network of the YOLO-BLBE model, and Alpha-EIOU was used as the loss function of the model to determine and filter candidate boxes. The main contributions of this study are as follows: (1) The I-MSRCR algorithm proposed in this paper can effectively amplify the color differences between blueberry fruits of different maturities. (2) Adding the synthesized blueberry images processed by the I-MSRCR algorithm to the training set for training can improve the model’s recognition accuracy for blueberries of different maturity levels. (3) The YOLO-BLBE model achieved an average identification accuracy of 99.58% for mature blueberry fruits, 96.77% for semi-mature blueberry fruits, and 98.07% for immature blueberry fruits. (4) The YOLO-BLBE model had a size of 12.75 MB and an average detection speed of 0.009 s. Full article
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17 pages, 9396 KiB  
Article
A Multimode 28 GHz CMOS Fully Differential Beamforming IC for Phased Array Transceivers
by Ayush Bhatta, Jeongsoo Park, Donghyun Baek and Jeong-Geun Kim
Sensors 2023, 23(13), 6124; https://doi.org/10.3390/s23136124 - 3 Jul 2023
Cited by 3 | Viewed by 3467
Abstract
A 28 GHz fully differential eight-channel beamforming IC (BFIC) with multimode operations is implemented in 65 nm CMOS technology for use in phased array transceivers. The BFIC has an adjustable gain and phase control on each channel to achieve fine beam steering and [...] Read more.
A 28 GHz fully differential eight-channel beamforming IC (BFIC) with multimode operations is implemented in 65 nm CMOS technology for use in phased array transceivers. The BFIC has an adjustable gain and phase control on each channel to achieve fine beam steering and beam pattern. The BFIC has eight differential beamforming channels each consisting of the two-stage bi-directional amplifier with a precise gain control circuit, a six-bit phase shifter, a three-bit digital step attenuator, and a tuning bit for amplitude and phase variation compensation. The Tx and Rx mode overall gains of the differential eight-channel BFIC are around 11 dB and 9 dB, respectively, at 27.0–29.5 GHz. The return losses of the Tx mode and Rx mode are >10 dB at 27.0–29.5 GHz. The maximum phase of 354° with a phase resolution of 5.6° and the maximum attenuation of 31 dB, including the gain control bits with an attenuation resolution of 1 dB, is achieved at 27.0–29.5 GHz. The root mean square (RMS) phase and amplitude errors are <3.2° and <0.6 dB at 27.0–29.5 GHz, respectively. The chip size is 3.0 × 3.5 mm2, including pads, and Tx mode current consumption is 580 mA at 2.5 V supply voltage. Full article
(This article belongs to the Special Issue Advanced CMOS Integrated Circuit Design and Application II)
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11 pages, 2188 KiB  
Communication
Isolation Improvement in Reflectarray Antenna-Based FMCW Radar Systems
by Hesham Yamani and Jihwan Yoon
Sensors 2022, 22(22), 8972; https://doi.org/10.3390/s22228972 - 19 Nov 2022
Cited by 1 | Viewed by 2680
Abstract
This paper presents an optimization of reflectarray-based RF sensors for detecting UAV and human presence. Our previous human detection radar system adapted a center-fed reflectarray antenna to a commercially available radar system, successfully increasing the gains of the transmit (TX) and receive (RX) [...] Read more.
This paper presents an optimization of reflectarray-based RF sensors for detecting UAV and human presence. Our previous human detection radar system adapted a center-fed reflectarray antenna to a commercially available radar system, successfully increasing the gains of the transmit (TX) and receive (RX) antennas by 21.18 dB and the range for detecting human targets 3.4 times. However, because the TX and RX antennas were placed in the focal point of the reflectarray, the TX signal reflected by the reflectarray was directly propagated into the RX antenna, causing desensitization or damage to the receiving circuit if high powers were used. To reduce this direct reflection, we propose a novel radar antenna configuration in which the TX and RX antennas are placed back-to-back with each other. In this configuration, the RX antenna does not directly face the reflectarray, thus direct path between the TX to RX through the reflectarray is removed. The results demonstrate that this approach achieves the optimum isolation level of 51.3 dB. With the reflectarray, the TX antenna gain increases to 30.6 dBi, but the RX antenna gain remains at 16 dBi since the RX antenna does not utilize the reflectarray. The TX and RX gain difference (14.6 dB) is a trade-off for good isolation and may be reduced by utilizing a high-gain receiver amplifier. Full article
(This article belongs to the Special Issue RF and IoT Sensors: Design, Optimization and Applications)
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9 pages, 2362 KiB  
Article
A Ku-Band Bi-Directional Transmit and Receive IC in 0.13 μm CMOS Technology
by Jeong-Geun Kim and Donghyun Baek
Appl. Sci. 2022, 12(11), 5710; https://doi.org/10.3390/app12115710 - 3 Jun 2022
Cited by 2 | Viewed by 2479
Abstract
This paper presents a Ku-band transmit and receive IC in 0.13 µm CMOS technology for mobile satellite communication beamforming systems. A Ku-band transmit and receive IC is composed of a bi-directional amplifier, a 6-bit phase shifter, and a 6-bit digital step attenuator. The [...] Read more.
This paper presents a Ku-band transmit and receive IC in 0.13 µm CMOS technology for mobile satellite communication beamforming systems. A Ku-band transmit and receive IC is composed of a bi-directional amplifier, a 6-bit phase shifter, and a 6-bit digital step attenuator. The precise trimming bits are implemented in the phase shifter (2.8°) and digital step attenuator (0.5 and 1 dB) for the amplitude and phase error correction. The phase variation range of the phase shifter is 360° with a phase resolution of 5.625°. The attenuation range of 31.5 dB with an amplitude resolution of 0.5 dB is achieved. The gain of 2~5 dB and the input/output return losses of >10 dB are achieved from 12 to 16 GHz. The chip size is 2.5 × 1.5 mm2 including bonding pads. The DC power consumption is 216 mW. Full article
(This article belongs to the Special Issue Recent Research in Microwave and Millimeter-Wave Components)
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12 pages, 2862 KiB  
Article
A 5–50 GHz SiGe BiCMOS Linear Transimpedance Amplifier with 68 dBΩ Differential Gain towards Highly Integrated Quasi-Coherent Receivers
by Guillermo Silva Valdecasa, Jose A. Altabas, Monika Kupska, Jesper Bevensee Jensen and Tom K. Johansen
Electronics 2021, 10(19), 2349; https://doi.org/10.3390/electronics10192349 - 26 Sep 2021
Cited by 4 | Viewed by 3167
Abstract
Quasi-coherent optical receivers have recently emerged targeting access networks, offering improved sensitivity and reach over direct-detection schemes at the expense of a higher receiver bandwidth. Higher levels of system integration together with sufficiently wideband front-end blocks, and in particular high-speed linear transimpedance amplifiers [...] Read more.
Quasi-coherent optical receivers have recently emerged targeting access networks, offering improved sensitivity and reach over direct-detection schemes at the expense of a higher receiver bandwidth. Higher levels of system integration together with sufficiently wideband front-end blocks, and in particular high-speed linear transimpedance amplifiers (TIAs), are currently demanded to reduce cost and scale up receiver data rates. In this article, we report on the design and testing of a linear TIA enabling high-speed quasi-coherent receivers. A shunt-feedback loaded common-base topology is adopted, with gain control provided by a subsequent Gilbert cell stage. The circuit was fabricated in a commercial 130 nm SiGe BiCMOS technology and has a bandpass characteristic with a 3 dB bandwidth in the range of 5–50 GHz. A differential transimpedance gain of 68 dBΩ was measured, with 896 mVpp of maximum differential output swing at the 1 dB compression point. System experiments in a quasi-coherent receiver demonstrate an optical receiver sensitivity of −30.5 dBm (BER = 1 × 103) at 10 Gbps, and −26 dBm (BER = 1 × 103) at 25 Gbps. The proposed TIA represents an enabling component towards highly integrated quasi-coherent receivers. Full article
(This article belongs to the Special Issue RF and Mixed Signal High Speed Circuit Design)
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24 pages, 8109 KiB  
Article
New Compact Wearable Metamaterials Circular Patch Antennas for IoT, Medical and 5G Applications
by Albert Sabban
Appl. Syst. Innov. 2020, 3(4), 42; https://doi.org/10.3390/asi3040042 - 8 Oct 2020
Cited by 10 | Viewed by 5752
Abstract
The development of compact passive and active wearable circular patch metamaterials antennas for communication, Internet of Things (IoT) and biomedical systems is presented in this paper. Development of compact efficient low-cost wearable antennas are one of the most significant challenges in development of [...] Read more.
The development of compact passive and active wearable circular patch metamaterials antennas for communication, Internet of Things (IoT) and biomedical systems is presented in this paper. Development of compact efficient low-cost wearable antennas are one of the most significant challenges in development of wearable communication, IoT and medical systems. Moreover, the advantage of an integrated compact low-cost feed network is attained by integrating the antenna feed network with the antennas on the same printed board. The efficiency of communication systems may be increased by using efficient passive and active antennas. The system dynamic range may be improved by connecting amplifiers to the printed antenna feed line. Design, design considerations, computed and measured results of wearable circular patch meta-materials antennas with high efficiency for 5G, IoT and biomedical applications are presented in this paper. The circular patch antennas electrical parameters on the human body were analyzed by using commercial full-wave software. The circular patch metamaterial wearable antennas are compact and flexible. The directivity and gain of the antennas with Circular Split-Ring Resonators (CSRR) is higher by 2.5dB to 3dB than the antennas without CSRR. The resonant frequency of the antennas without CSRR is higher by 6% to 9% than the antennas with CSRR. The computed and measured bandwidth of the stacked circular patch wearable antenna with CSRR for IoT and medical applications is around 12%, for S11 lover than −6dB. The gain of the circular patch wearable antenna with CSRR is around 8dBi. Full article
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12 pages, 2690 KiB  
Article
An Approach for a Wide Dynamic Range Low-Noise Current Readout Circuit
by Wei Wang and Sameer Sonkusale
J. Low Power Electron. Appl. 2020, 10(3), 23; https://doi.org/10.3390/jlpea10030023 - 29 Jul 2020
Cited by 3 | Viewed by 4685
Abstract
Designing low-noise current readout circuits at high speed is challenging. There is a need for preamplification stages to amplify weak input currents before being processed by conventional integrator based readout. However, the high current gain preamplification stage usually limits the dynamic range. This [...] Read more.
Designing low-noise current readout circuits at high speed is challenging. There is a need for preamplification stages to amplify weak input currents before being processed by conventional integrator based readout. However, the high current gain preamplification stage usually limits the dynamic range. This article presents a 140 dB input dynamic range low-noise current readout circuit with a noise floor of 10 fArms/sq(Hz). The architecture uses a programmable bidirectional input current gain stage followed by an integrator-based analog-to-pulse conversion stage. The programmable current gains setting enables one to achieve higher overall input dynamic range. The readout circuit is designed and in 0.18 μm CMOS and consumes 10.3 mW power from a 1.8 V supply. The circuit has been verified using post-layout simulations. Full article
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9 pages, 818 KiB  
Article
A Channel Model to Deal with Distributed Noises and Nonlinear Effects in a Fiber System with Distributed Raman Amplifiers
by Yao Xie, Qiguang Feng, Wei Li, Qiang Zheng and You Wang
Appl. Sci. 2020, 10(1), 133; https://doi.org/10.3390/app10010133 - 23 Dec 2019
Cited by 6 | Viewed by 2731
Abstract
Nowadays, the distributed fiber Raman amplifier (FRA) has become more and more popular in long-haul fiber systems, owing to its lower noise figures and weaker nonlinear effects in the link. The critical issue in distributed FRAs is the presence of various kinds of [...] Read more.
Nowadays, the distributed fiber Raman amplifier (FRA) has become more and more popular in long-haul fiber systems, owing to its lower noise figures and weaker nonlinear effects in the link. The critical issue in distributed FRAs is the presence of various kinds of noises and their interactions with the signal. However, the existing Raman channel models and their numerical solving methods can only partially describe how the randomly distributed noises interact with the signal. This causes the difficulties in analyzing the distributed FRA precisely and the inconveniences for the applications and the maintenance of FRA systems. In this paper, we propose a modified Raman channel model to describe more comprehensively the interactions between the distributed noises and the signal under the influence of loss, distributed gain, dispersion, and nonlinear effects in the distributed FRA systems. With the comparisons of the error–vector magnitude (EVM) curves, our model can get lower errors in the experimental results regarding bidirectional pumped FRA single-span fiber systems and multi-span systems with backward-pumped FRAs. Full article
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11 pages, 7124 KiB  
Article
A Broadband Switch-Less Bi-Directional Amplifier with Negative-Group-Delay Matching Circuits
by Yuwei Meng, Zhongbao Wang, Shaojun Fang, Te Shao and Hongmei Liu
Electronics 2018, 7(9), 158; https://doi.org/10.3390/electronics7090158 - 23 Aug 2018
Cited by 14 | Viewed by 4838
Abstract
A broadband switch-less bi-directional low noise amplifier based on negative group delay (NGD) matching circuits with a non-Foster characteristic is proposed. To validate the feasibility, two circuits were designed and compared, which are matched by NGD circuits and traditional lumped elements respectively. The [...] Read more.
A broadband switch-less bi-directional low noise amplifier based on negative group delay (NGD) matching circuits with a non-Foster characteristic is proposed. To validate the feasibility, two circuits were designed and compared, which are matched by NGD circuits and traditional lumped elements respectively. The structure proposed in this paper has a measured relative bandwidth (RBW) of 32.6% rather than 5.1% for the traditional one. From 797 MHz to 1095 MHz, the input and output return losses (RL) are more than 10 dB with a noise factor (NF) of about 3.5 dB and peak gain of 12.2 dB. Meanwhile, the reverse isolation and stability factor (SF) are greater than 20 dB and 1, respectively. The group delay (GD) value is 0.5 ns ± 0.25 ns in the operating frequency band, which is much flatter and lower compared to that of the traditional one. Full article
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17 pages, 14557 KiB  
Article
An X-band Bi-Directional Transmit/Receive Module for a Phased Array System in 65-nm CMOS
by Van-Viet Nguyen, Hyohyun Nam, Young Joe Choe, Bok-Hyung Lee and Jung-Dong Park
Sensors 2018, 18(8), 2569; https://doi.org/10.3390/s18082569 - 6 Aug 2018
Cited by 14 | Viewed by 5805
Abstract
We present an X-band bi-directional transmit/receive module (TRM) for a phased array system utilized in radar-based sensor systems. The proposed module, comprising a 6-bit phase shifter, a 6-bit digital step attenuator, and bi-directional gain amplifiers, is fabricated using 65-nm CMOS technology. By constructing [...] Read more.
We present an X-band bi-directional transmit/receive module (TRM) for a phased array system utilized in radar-based sensor systems. The proposed module, comprising a 6-bit phase shifter, a 6-bit digital step attenuator, and bi-directional gain amplifiers, is fabricated using 65-nm CMOS technology. By constructing passive networks in the phase-shifter and the variable attenuator, the implemented TRM provides amplitude and phase control with 360° phase coverage and 5.625° as the minimum step size while the attenuation range varies from 0 to 31.5 dB with a step size of 0.5 dB. The fabricated T/R module in all of the phase shift states had RMS phase errors of less than 4° and an RMS amplitude error of less than 0.93 dB at 9–11 GHz. The output 1dB gain compression point (OP1dB) of the chip was 5.13 dBm at 10 GHz. The circuit occupies 3.92 × 2.44 mm2 of the chip area and consumes 170 mW of DC power. Full article
(This article belongs to the Section Remote Sensors)
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10 pages, 1539 KiB  
Article
Optimization of Split Transmitter-Receiver Digital Nonlinearity Compensation in Bi-Directional Raman Unrepeatered System
by Qiang Zheng, Zhilin Yuan, Yuan Li and Wei Li
Appl. Sci. 2018, 8(6), 972; https://doi.org/10.3390/app8060972 - 13 Jun 2018
Cited by 2 | Viewed by 3010
Abstract
A theoretical model of the nonlinear signal-to-noise interaction (NSNI) in a bi-directional Raman amplified system with receiver-side digital back-propagation (DBP) or split-DBP is given, which is helpful for the design of such a system. In the proposed model, the distributed Raman gain and [...] Read more.
A theoretical model of the nonlinear signal-to-noise interaction (NSNI) in a bi-directional Raman amplified system with receiver-side digital back-propagation (DBP) or split-DBP is given, which is helpful for the design of such a system. In the proposed model, the distributed Raman gain and the spontaneous Raman scattering are taken into account. The results of the theoretical calculation are compared with the results of transmission simulations, which indicates that the theoretical model matches well with the results of simulations when the pre-compensation length is less than 100 km. For the cases of pre-compensation lengths more than 100 km, the theoretical model has an error of less than 0.1 dB compared with the simulations. By using the theoretical model, the efficiency of the split-DBP is analyzed, and the results are compared with transmission simulations. Both the results of theoretical calculation and simulations show that the split-DBP can effectively mitigate the NSNI in such a system. By adopting split-DBP, with an appropriate pre-compensation length, the signal-to-noise ratio (SNR) of the signal increases by about 1 dB. In addition, the impact of the double Rayleigh scattering (DRB) is also analyzed using the proposed model, and the results show that DRB has little impact on the system. Full article
(This article belongs to the Special Issue DSP for Next Generation Fibre Communication Systems)
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