Explore the vast range of titles available.

Spinal diseases and frozen shoulder are prevalent health problems in Asian populations. Early assessment and treatment are very important to prevent the disease from getting worse and reduce pain. In the field of computer vision, it is a challenging problem to assess the range of motion. In order to realize efficient, real-time and accurate assessment of the range of motion, an assessment system combining MediaPipe and YOLOv5 technologies was proposed in this study. On this basis, Convolutional Block Attention Module (CBAM) is introduced into the YOLOv5 target detection model, which can enhance the extraction of feature information, suppress background interference, and improve the generalization ability of the model. In order to meet the requirements of large-scale computing, a client/server (C/S) framework structure is adopted. The evaluation results can be obtained quickly after the client uploads the image data, providing a convenient and practical solution. In addition, a game of \"Picking Bayberries\" was developed as an auxiliary treatment method to provide patients with interesting rehabilitation training.

This paper presents the development of the world’s first high-gain, all-photopolymer Bragg horn antennas explicitly designed for the WR-3.4 band (220–325 GHz), marking a groundbreaking advancement in terahertz (THz) antenna technology. Unlike conventional metallic horn antennas, which suffer from conductor losses and manufacturing complexity, this innovative design utilizes eco-friendly photopolymer materials and additive manufacturing, achieving a fractional bandwidth of 38.5% that fully covers the WR-3.4 band. The proposed antenna achieves a measured peak gain of 28.98 dBi at 300 GHz, with a return loss better than − 20dB across the band and a consistent half-power beamwidth (HPBW) of ~ 5°, ensuring precise directivity and minimal sidelobe interference. By employing a novel horn-type adapter for seamless mode conversion from TE 10 to the fundamental HE 11 mode, the design significantly enhances coupling efficiency and reduces signal loss. Additionally, fabrication costs can be reduced by over 50% compared to traditional metallic designs, while maintaining repeatability and enabling rapid prototyping. As the first demonstration of photopolymer-based antennas achieving such high gains in the 220–325 GHz THz spectrum, this work establishes a new benchmark in THz antenna technology, providing an eco-friendly, cost-effective, and high-performance solution for high-speed communication, medical diagnostics, security imaging, and spectroscopy applications.

This study aims to provide a non-contact detection of liquid composition inside containers using Microwave Radar Cross-section (RCS) measurement technology. Firstly, it analyzes the limitations of traditional near-infrared spectroscopy methods and proposes the necessity of introducing microwave detection methods. The research demonstrates through experiments a significant correlation between polar substances like total acid content and radar scattering capability, showing microwave radar’s effectiveness in reflecting the polarity characteristics of liquids. Furthermore, theoretical derivations and experimental validations illustrate that differences in electromagnetic properties of different liquid components lead to variations in echo loss, thereby impacting RCS levels. Experimental results indicate that microwave radar RCS measurement technology achieves an accuracy level of 2%, capable of distinguishing between different concentrations of ethanol, acetic acid, and other solutions. This study highlights the significant advantages of microwave radar RCS measurement technology in non-contact detection of liquid composition, providing new methods and a technological foundation for precise liquid component detection.

This paper presents a comprehensive study of the optical and electrical dielectric material properties of six commonly-used silicon and glass substrates at terahertz (THz) frequencies, including refractive index, absorption coefficient, dielectric constant and loss factor. The material characterization techniques used in this paper feature THz time-domain transmission and reflection spectroscopy with the measurement frequencies from 0.5 THz up to a maximum of 6.5 THz. Of the six selected dielectric and semiconductor substrates, two are silicon wafers with resistivities ranging from 0.001 to 0.02 Ω-cm. From the measurement results, loss tangents of the selected silicon wafers range from 0.680 to 5.455 and the dielectric constants are from 1.079 to 17.735. The four other wafers are all glass-based substrates: D263 glass, Borofloat 33 glass, fused silica and Sapphire. From the measurements, it is found that the THz dielectric properties vary considerably between the substrate samples e.g. dielectric constants range from 1.925 to 3.207 while loss tangents are from 0.042 × 10 −3 to 0.127. Most of the selected silicon and glass-based substrates are quite useful for many THz applications, e.g., THz integrated circuits (THz ICs), THz microsystem technologies (THz MSTs) and THz system-on-a-chip (THz SoC) and system-on-substrate (SiP).

We designed and optimized a miniaturized coplanar Vivaldi antenna specifically for microwave imaging in cerebral hemorrhage detection. The antenna measures 80 mm × 80 mm × 1 mm and features an arc-shaped radiating arm, a 3 mm × 3 mm optimized pad layout, and an improved metallized via structure with nine vias, each 0.5 mm in diameter. These enhancements significantly improve the antenna's directivity, impedance matching, and signal penetration capability. Experimental results demonstrate that the antenna operates stably within the ultra-wide frequency band of 1.6-8 GHz, achieving a reflection coefficient as low as -45 dB at 4 GHz, a voltage standing wave ratio (VSWR) consistently below 1.5, and a peak gain of 9.5 dB at 6.5 GHz. These characteristics fully meet the sensitivity and penetration depth requirements for medical imaging. In addition to presenting a novel antenna design, this study validates its effectiveness under realistic biological conditions. Comparative analysis between 18- and 36-element antenna arrays demonstrates that the 36-element configuration improves image resolution and signal uniformity, while the 18-element array offers faster acquisition and better suitability for emergency or point-of-care screening scenarios. Additionally, in realistic skull model experiments, we employed rotating antenna technology (with a 20° step size) and multi-angle signal acquisition, further optimizing imaging uniformity and detection accuracy in hemorrhagic regions. By integrating real-time differential imaging technology and beamforming algorithms such as Delayed Sum (DAS) and Delayed Multiplication and Sum (DMAS), the experimental results indicate substantial progress in the identification of brain hemorrhage areas. This research provides critical technical support for the development of portable and non-invasive cerebral hemorrhage detection systems. Overall, by integrating miniaturization, performance optimization, and targeted enhancements, this study provides a robust technical basis for the development of early stroke detection systems.

This study presents a design study of a novel concept of a three-dimensional (3D) micromachined square helical antenna designed for 75 GHz, which is completely integrated into a semiconductor silicon substrate. In contrast to conventional on-chip integrated antennas which typically are built on top of the substrate surface, the proposed antenna concept utilises, for the first time to the knowledge of the authors, the whole volume of the wafer by building the helical structure inside the substrate, which results in a very area-efficient high-gain radiating element for a substrate-integrated millimeter-wave system. The effective permittivity of the antenna core and the surrounding substrate can be tailor-made by 3D micromachining, for optimising the maximum antenna performance with this design study it was found, that such an antenna concept can achieve a maximum gain of 13.2 dBi, a radiation efficiency of 95.3% at the axial ratio of 0.94 and a half-power beamwidth (HPBW) of smaller than 40°, and a return loss S11 of −22.3 dB at the nominal frequency of 74.5 GHz, with a 15-GHz bandwidth with a reflection coefficient better than −10 dB. A 16-element substrate-integrated helical line array is demonstrated and achieves a maximum gain of 24.2 dBi with a HPBW of 6.3° in the y–z-plane. This study also studies intensively the influences of the surrounding silicon substrate and dielectric-core etching, the matching transition between the helical structure and a coplanar-waveguide feeding, as well as size and geometry of the ground structure.

The rapidly growing global data usage has demanded more efficient ways to utilize the scarce electromagnetic spectrum resource. Recent research has focused on the development of efficient multiplexing techniques in the millimeter-wave band (1–10 mm, or 30–300 GHz) due to the promise of large available bandwidth for future wireless networks. Frequency-division multiplexing is still one of the most commonly-used techniques to maximize the transmission capacity of a wireless network. Based on the frequency-selective tunnelling effect of the low-loss epsilon-near-zero metamaterial waveguide, we numerically and experimentally demonstrate five-channel frequency-division multiplexing and demultiplexing in the millimeter-wave range. We show that this device architecture offers great flexibility to manipulate the filter Q -factors and the transmission spectra of different channels, by changing of the epsilon-near-zero metamaterial waveguide topology and by adding a standard waveguide between two epsilon-near-zero channels. This strategy of frequency-division multiplexing may pave a way for efficiently allocating the spectrum for future communication networks.

The rapidly growing global data usage has demanded more efficient ways to utilize the scarce electromagnetic spectrum resource. Recent research has focused on the development of efficient multiplexing techniques in the millimeter-wave band (110 mm, or 30-300 GHz) due to the promise of large available bandwidth for future wireless networks. Frequency-division multiplexing is still one of the most commonly-used techniques to maximize the transmission capacity of a wireless network. Based on the frequency-selective tunnelling effect of the low-loss epsilon-near-zero metamaterial waveguide, we numerically and experimentally demonstrate five-channel frequency-division multiplexing and demultiplexing in the millimeter-wave range. We show that this device architecture offers great flexibility to manipulate the filter g-factors and the transmission spectra of different channels, by changing of the epsilon-near-zero metamaterial waveguide topology and by adding a standard waveguide between two epsilon-near-zero channels. This strategy of frequency-division multiplexing may pave a way for efficiently allocating the spectrum for future communication networks. frequency-division multiplexing, artificial effective medium, epsilon-near-zero metamaterial, integrated photonics PACS number(s): 41.20.Jb, 42.25.Dd, 42.79.Sz, 84.40.A

This study reports on the radiofrequency (RF) performance optimisation of a novel multi-stage microelectromechanical system (MEMS) dielectric-block phase-shifter concept. The objective is to minimise the average return loss for all possible operation states of a multi-stage phase shifter, without substantially compromising the overall insertion loss or in phase-shift performance. The optimisation method presented in this study is generally applicable to any type of multi-stage RF MEMS devices that are operated in all possible state combinations of the different stages. The return loss is optimized for a seven-stage MEMS dielectric-block phase shifter by adjusting the individual distances between the phase shifter stages, for the nominal frequency of 75 GHz as well as for 500 MHz and 1 GHz bandwidth. A total of seven different designs following different optimisation approaches are investigated by simulations and measurements of fabricated devices. The best concept was found for exponentially increasing distances between the stages that takes into account the proper actuation sequence for all possible phase-shift combinations. As compared with a non-optimised device previously published by the authors, the design offering the best compromise between return loss and insertion loss, achieved by this optimisation method, results in a significant return loss improvement of 11.8 dB (simulated) and 6.98 dB (measured), whereas compromising the insertion loss by only 0.75 dB (simulated) and 0.92 dB (measured). In contrast to that all other investigated concepts, including intuitive optimisation methods such as λ/4 distances or optimisation of equidistant concepts result in a much smaller or no return-loss improvement and some even in a drastic worsening of the insertion loss.

This paper presents a novel approach to the design and fabrication of low-cost and high-gain aperture-coupled microstrip patch antenna (AC-MPA) arrays with improved radiation pattern for millimetre-wave applications such as simultaneous wireless information and power transfer (SWIPT) and Internet-of-Things (IoT) device connectivity. A higher-order mode substrate integrated waveguide (SIW) cavity is used to feed the MPA arrays through aperture coupling. The improved design approach is introduced and discussed in detail. Simulation and experimental results for 2 × 2 and 4 × 4 arrays are presented, demonstrating excellent agreement. Key performance metrics are side-lobe levels of less than −24 dB and −29 dB in the E-plane and −22 dB and −26 dB in the H-plane and realized gain of 11 dBi and 15 dBi for the 2 × 2 and 4 × 4 arrays respectively, at a design frequency of 30 GHz.