Radiation Characteristics Research Articles

Interference and precursor signal analysis based on random forest and improved logistic regression model

Coal is the main energy and industrial raw material in China. In order to prevent the risks of coal mining and ensure the safety and efficiency of coal mining, this paper established random forest model, ADF and MK test model and logistic regression model, and used autocorrelation function algorithm, Fourier transform and sliding window transformation of time series data to analyze and optimize the characteristics of interference signals and precursor characteristics. For the first work, the huge data is preprocessed, tested, and outliers are removed, and the time characteristics are taken to aggregate and classify the data. For work (1.1), data parameters were sorted out, Fourier transform prediction signal model was initially established, and characteristic values were extracted by wavelet transform. Finally, autocorrelation function algorithm was used to optimize and analyze the results. The final results were shown in Table 4 for the data characteristics of electromagnetic radiation (EMR) interference signals and Table 5 for the interference signals of acoustic propagation signals. For work (1.2), a random forest model is established, with sliding window transformation of time series data, window size is specified, boundary processing mode is specified, and label value is defined as interference and normal. The data set is divided into training set and test set in the way of eighty-two allocation. After AE training, there are three stages of training. Finally, random forest algorithm is used to calculate the electromagnetic radiation interference signal interval. For work (2.1), the model and algorithm of work 1 are used to identify the trend characteristics of the data before the occurrence of electromagnetic radiation and acoustic emission signals, and the signal data are judged to have a "slightly rising" trend. The statistical values are compared by KS trend test, and the trend characteristics of normal and precursor signals are calculated by using the autocorrelation function algorithm. A trend feature table is obtained for the precursory feature data of electromagnetic radiation and acoustic propagation signal. For work (2.2), Augmented dickey-Fuller and MK test models of the system were established. For work 3, a logistic regression model is established to predict the probability of precursor feature data appearing at the last moment of multiple time periods. By using maximum likelihood estimation to train model parameters, the characteristics of the last data collection moment of each time period are predicted, and the probability of precursor feature appearing at each moment is output. As shown in Table 14, the probability of precursor features appearing at the time when the data of multi-classification logistic regression is located is obtained. **************** ACKNOWLEDGEMENTS**************** This work is supported by ministry of education industry-university cooperative education project (Grant No.: 231106441092432), the research and practice of integrating "curriculum thought and politics" into the whole process of graduation design of Mechanical engineering major: (Grant. No.: 30120300100-23-yb-jgkt03), research on the integration mechanism of "course-training-competition-creation-production" for innovation and entrepreneurship of mechanical engineering majors in applied local universities (Grant. No.: CXKT202405), Mechanical manufacturing equipment design school-level "gold class" construction project (Grant. No.: 30120324001).

Influence of spread of the Josephson junction parameters on the radiation characteristics of active Josephson antennas

Influence of spread of the Josephson junction parameters on the radiation characteristics of active Josephson antennas

Flexible circularly polarized CPW antenna for X-band: design, simulation, and experimental validation

Abstract This paper presents the design and analysis of a circularly polarized coplanar waveguide (CPW) antenna specifically tailored for X-band applications. The antenna, with compact dimensions of 27 mm x 28 mm, is fabricated on a flexible 0.1 mm thick polyimide substrate. It operates effectively within the frequency range of 10.5 GHz to 12 GHz. To enhance performance metrics such as gain and radiation characteristics, two complementary split-ring resonators (CSRRs) are integrated into the radiating patch. Comprehensive simulations were conducted, followed by the fabrication and experimental testing of the antenna. The results indicate a high degree of agreement between the simulated and measured performance parameters. The antenna achieves a gain of up to 6 dBi, with an axial ratio maintained below 3 dB across the operating frequency band, signifying excellent circular polarization characteristics. These findings underscore the potential of the proposed CPW antenna design as a highly efficient solution for X-band applications, offering notable improvements in gain and axial ratio performance. This work contributes to the development of advanced antenna technologies suitable for modern communication systems operating in the X-band spectrum.

High-Gain Miniaturized Multi-Band MIMO SSPP LWA for Vehicular Communications

This paper introduces a novel miniaturized, four-mode, semi-flexible leaky wave Multiple-Input Multiple-Output (MIMO) antenna specifically designed to advance vehicular communication systems. The proposed antenna addresses key challenges in 5G low- and high-frequency bands, including millimeter-wave communication, by integrating innovative features such as a periodic Spoof Surface Plasmon Polariton Transmission Line (SSPP-TL) and logarithmic-spiral-like semi-circular strip patches parasitically fed via orthogonal ports. These design elements facilitate stable impedance matching and wide impedance bandwidths across operating bands, which is essential for vehicular networks. The hybrid combination of leaky wave and SSPP structures, along with a defected wide-slot ground structure and backside meander lines, enhances radiation characteristics by reducing back and bidirectional radiation. Additionally, a naturalization network incorporating chamfered-edge meander lines minimizes mutual coupling and introduces a fourth radiation mode at 80 GHz. Compact in size (14 × 12 × 0.25 mm3), the antenna achieves high-performance metrics, including S11 < −18.34 dB, dual-polarization, peak directive gains of 11.6 dBi (free space) and 14.6 dBi (on vehicles), isolation > 27 dB, Channel Capacity Loss (CCL) < 3, Envelope Correlation Coefficient (ECC) < 0.001, axial ratio < 2.25, and diversity gain (DG) > 9.85 dB. Extensive testing across various vehicular scenarios confirms the antenna’s robustness for Vehicle-to-Vehicle (V2V), Vehicle-to-Pedestrian (V2P), and Vehicle-to-Infrastructure (V2I) communication. Its exceptional performance ensures seamless connectivity with mobile networks and enhances safety through Specific Absorption Rate (SAR) compliance. This compact, high-performance antenna is a transformative solution for connected and autonomous vehicles, addressing critical challenges in modern automotive communication networks and paving the way for reliable and efficient vehicular communication systems.

In Situ Preparation of Thin-Film Q-Switches Based on Vanadium Dioxide for Pulsed Fiber Lasers

In the presented work, erbium fiber lasers operating in the pulsed mode with a nonlinear element containing a vanadium oxide saturable absorber are demonstrated. The structure of the saturable absorber is based on a segment of thinned silica fiber coated with a thin-film vanadium oxide by the method of metalorganic chemical vapor deposition. A fiber laser scheme is demonstrated that allows controlling the transmission of the internal cavity of the resonator during laser generation and deposition of a thin film. We have demonstrated a method for obtaining and annealing nanocoatings with laser generation control. We controlled the laser output parameters directly during the synthesis of the saturable absorber material. Vanadium oxides obtained in the work demonstrated the Mott–Paierls phase transition practically at room temperature. In this work, the optical characteristics of the output radiation of a fiber laser with a saturable absorber were measured. At temperatures above 70 °C, the coatings demonstrate a passive Q-switch with a repetition rate of 38 kHz and a pulse duration of 3.8 μs. At temperatures below the phase transition, a short-term mode-locking mode occurs. The transmission jump at a wavelength of about 1350 nm during structural rearrangement was 24%. For comparison, VO2 nanopowder in a polydimethylsiloxane elastomer matrix was used as a saturable absorber material. The nanopowder modulator made it possible to obtain pulses with a frequency of 27 kHz and a duration of about 7.2 μs.

Design of dual-band filtering patch antenna slot coupling feed

Abstract A novel microstrip filtering antenna with slot coupling feed is presented in this work. An asymmetric interdigital coupling structure is used for the feed to excite the patch antenna through gap-fed coupling. Introducing a U-shaped slot on the patch surface modifies the current path to attain different resonant modes. The asymmetric coupled fingers in the low-frequency band generate a radiation null of −64 dBi, while additional resonances introduced in the high band broaden the bandwidth from 4.9 to 5.3 GHz. A horizontally shorted microstrip branch produces another null point of −28 dBi between the bands, enabling steeper roll-off and further improvement in frequency selectivity. The proposed filtering antenna provides a flexible filter response without requiring extra filtering circuits, with appreciable peak gains (6.1 dBi and 7.1 dBi) and stable radiation characteristics. This makes it suitable for WLAN (Wireless Local Area Network) and ISM (Industrial Scientific Medical) systems applications.

Broadband Rectangular Microstrip Antenna with Slits for W-Band Applications

This work introduces a broadband rectangular patch antenna optimized for efficient data transmission in the W-band, particularly for 5G applications. By integrating two I-shaped slits with the radiating element, the antenna achieves an impressive performance, exhibiting wide bandwidth and excellent radiation characteristics. Utilizing Rogers RT5880 as the substrate material with a relative permittivity (εr) of 2.2, a small antenna with a size of 3.7 × 4.1 × 0.16 mm³ is realized. Extensive simulations are conducted using CST software in both frequency and time domains to optimize the antenna. The results show a notable 16% fractional bandwidth from 80.75 GHz to 94.79 GHz, with dual resonance frequencies at 84.5 GHz and 91.5 GHz, primarily a result of the incorporated slits. At 84.5 GHz, the antenna demonstrates an outstanding reflection coefficient of -66.37 dB, a Voltage Sanding Wave Ratio (VSWR) of 1.00096, a gain of 9.71 dBi, a directivity of 9.75 dB, and a high radiation efficiency of 91.8%. Similar trends are observed at 91.5 GHz, where the return loss remains at an impressive value of 55.92 dB and the VSWR maintains a very low value of 1.0032, indicating continued excellent impedance matching. While the gain (6.98 dBi) and directivity (7.05 dB) are slightly lower at this frequency, the radiation efficiency remains remarkably high at 94.9%, indicating efficient energy utilization. The wide bandwidth of the proposed design enables high data transfer rates, a crucial requirement for 5G networks. This translates to significant improvements in network capacity, allowing for more connected devices and data traffic. Additionally, the design exhibits excellent signal transmission characteristics, ensuring reliable data transfer. Finally, the antenna's compact size and efficient radiation have the potential to reduce power consumption in 5G devices, contributing to improved battery life and sustainability.

Evaluation of weighted-sum-of-gray-gases models and radiation characteristics analysis for gas-ash particle mixture in ash deposition

Evaluation of weighted-sum-of-gray-gases models and radiation characteristics analysis for gas-ash particle mixture in ash deposition

Compact MIMO antenna for the IOT applications and new generation of wireless communications

ABSTRACT The aim of this article is to cover the LTE band along with IOT applications, by presenting a new design of multi-input/multi-output antenna acceptable radiation pattern and gain is obtained. The design process in this research is a semi-fractal element with a physical size of 35 × 30 × 1.6 mm3 that covers frequency band 1.6–2.2 GHz with peak gain of 3.2 dBi at the central frequency of operational band. The IOT-MIMO antenna has impedance bandwidth from 1.7 to 3.62 (72%). Using multi-input multi-output technique with appropriate radiator leads to wider operational band beside with CP property. The ultimate array MIMO antenna has peak gain of 8.2 dBi at operational band. IOT-MIMO antenna has semi-bipolar radiation characteristics. Based on the obtained results, the desired structure has circular polarisation in frequency bands of 2.2–3.2 GHz (30%). In this research, presented IOT-MIMO antenna, covers 1.7 GHz LTE RF-EMF (focused on brain or nervous that are exposed to wireless communication),1.9 GHz (18.80–1900 MHz which developed to support the operation cordless telecommunication services (CTS)), WLAN (2400–2484 MHz), WiMAX (IEEE 802.16e) 2500–2600 MHz, Internet of Things (IOT) 2400 MHz and WiMAX (3.5 GHz IEEE802.11ac).

A Small Implantable Compact Antenna for Wireless Telemetry Applied to Wireless Body Area Networks

Wireless Body Area Networks (WBANs) are human-centric wireless networks, and implantable antennas represent a vital communication component within WBANs. The dielectric properties of human tissue are highly complex, with each layer exhibiting distinct dielectric constants that significantly influence the performance of implanted antennas. It is therefore imperative that a compact broadband implantable antenna be designed in order to address the instability in communication of medical implant devices. The antenna, coated in silicone, is a single-layer structure fed by a coaxial cable, with a volume of just 6 mm × 6 mm× 0.53 mm. A metallic patch is etched on the upper surface of the substrate, and the compact antenna design is enhanced with the introduction of S-shaped, F-shaped, and rectangular slots on the patch. The bottom side of the substrate is etched with rectangular ground planes, which broaden the impedance bandwidth of the antenna. The simulation results demonstrate that the antenna attains an impedance bandwidth of 23.8% (2.08–2.64 GHz), encompassing the entirety of the Industrial, Scientific, and Medical (ISM) band (2.4–2.48 GHz). In order to simulate the working environment of the antenna within the human body, physical tests were conducted on the antenna in pork tissue. The test results demonstrate that the antenna exhibits a measured bandwidth of 28% (2.3–3.03 GHz), with a radiation pattern that displays omnidirectional radiation characteristics. The antenna’s impedance matching and radiation characteristics remain essentially consistent in both bent and unbent states, indicating structural robustness. In comparison to other implantable antennas, this antenna displays a wider impedance bandwidth, a lower Specific Absorption Rate (SAR), and superior implant performance.

Dual polarization scattering reconfigurable integrated coded metasurface antenna based on a rotating adjustable resistor

The design of a rotating adjustable resistor-based dual-polarization scattering reconfigurable metasurface antenna is presented in this paper. By incorporating four rotating adjustable resistors at the edge of the structure, independent tuning of x-polarized and y-polarized scattering phases is achieved by the metasurface antenna. The effectiveness of this independent tuning capability is verified through equivalent circuit analysis and scattering current distributions. Furthermore, an “L” type patch feed configuration is employed for coupled feeding, enabling compact size reduction and integrated design of radiation and scattering characteristics within the metasurface antenna. Subsequently, an 8 × 8 array arrangement of the designed unit structures allows for dynamic control over dual-polarization scattering phase distribution by adjusting resistance values of rotating adjustable resistor, thereby achieving multiple independent control over scattering properties. With an impedance matching bandwidth ranging from 6.95 to 7.5 GHz and a peak gain of 19.4 dBi along with favorable radiation characteristics, the proposed metasurface antenna demonstrates excellent performance capabilities. Finally, experimental measurements validate that the measured results closely align with simulation outcomes.

A Wideband Eight-Port MIMO Antenna with Reduced Mutual Coupling for Future 5G mm-Wave Applications.

An eight-element MIMO antenna with a neutralization line was utilized for future 5G mm-wave applications. The MIMO configuration was designed for two ports, four ports and eight ports to validate the desired impedance and radiation characteristics. The measured results in terms of MIMO and scattering parameters correlate well with the simulated one. The printed eight-port antenna was a miniaturized size of 44 × 70 × 0.8 mm3. Roger RT/duroid 5880 substrate was used to print antennas. The presented antenna produced a vast bandwidth of 18 GHz, varying from 28 to 46 GHz, and achieved a reduced mutual coupling of 30 dB with 6.8-8.5 dBi gain. The eight-port antenna is compared with contemporary antennas considering size, isolation, impedance bandwidth, diversity characteristics and radiation properties, confirming that the presented antenna is a promising candidate for future 5G mm-wave applications.

Impact of host climate model on contrail cirrus effective radiative forcing estimates

Abstract. Estimates of aviation effective radiative forcing (ERF) indicate that contrail cirrus is currently its largest contributor, although with a substantial associated uncertainty of ∼ 70 %. Here, we implement the contrail parameterisation developed for the Community Atmosphere Model (CAM) in the UK Met Office Unified Model (UM), allowing us to compare, for the first time, the impact of key features of the host climate model on contrail cirrus ERF. We find that differences in background humidity between the models result in the UM-simulated contrail fractions being 2 to 3 times larger than in CAM. Additionally, the models show contrasting responses in overall global cloud fraction, with contrails increasing the total cloud fraction in the UM and decreasing it in CAM. Differences in the complexity of the cloud microphysics schemes lead to significant differences in simulated changes to cloud ice water content due to aviation. After compensating for the unrealistically low contrail optical depth in the UM, we estimate the 2018 contrail cirrus ERF to be 40.8 mW m−2 in the UM, compared to 60.1 mW m−2 in CAM. These values highlight the substantial uncertainty in contrail cirrus ERF due to differences in microphysics and radiation schemes between the two models. We also find a factor-of-8 uncertainty in contrail cirrus ERF due to existing uncertainty in contrail cirrus optical depth. Future research should focus on better representing microphysical and radiative contrail characteristics in climate models and on improved observational constraints.

Design Method of Infrared Stealth Film Based on Deep Reinforcement Learning

With the rapid advancement of infrared detection technology, the development of infrared stealth materials has become a pressing need. The study of optical micro/nano infrared stealth materials, which possess selective infrared radiation properties and precise structural features, is of significant importance. By integrating deep reinforcement learning with a multilayer perceptron, we have framed the design of radiation-selective films as a reinforcement learning problem. This approach led to the creation of a Ge/Ag/Ge/Ag multilayer micro/nano optical film that exhibits infrared stealth characteristics. During the design process, the agent continuously adjusts the thickness parameters of the optical film, exploring and learning within the defined design space. Upon completion of the training, the agent outputs the optimized thickness parameters. The results demonstrate that the film structure, optimized by the agent, exhibits a low average emissivities of 0.086 and 0.147 in the 3∼5 µm and 8∼14 µm atmospheric windows, respectively, meeting the infrared stealth requirements in terms of radiation characteristics. Additionally, the film demonstrates a high average emissivity of 0.75 in the 5∼8 µm range, making it effective for thermal radiation management. Furthermore, we coated the Si surface with the designed thin film and conducted experimental validation. The results show that the coated material exhibits excellent infrared stealth properties.

Discovery and characterization of ZTF J0112+5827: An 80.9-minute polar with strong cyclotron features

A new X-ray Cataclysmic variable (CV) candidate exhibits distinct light-curve characteristics in the ZTF's g, r, and i bands. The paper includes the optical identification and multiwavelength analysis of this CV candidate. This work aims to determine if a previously identified CV candidate, ZTF J0112+5827, is a polar system by examining its X-ray and cyclotron radiation characteristics. We characterized the X-ray emission of ZTF J0112+5827 using the ROSAT observations. The gri-band optical light curves were obtained from the Zwicky Transient Facility. After two nights of time-domain spectroscopic observations with the Palomar 200-inch telescope, we mapped the accretion structures using Doppler tomography. ZTF J0112+5827 exhibits an orbital period of 80.9 minutes, determined from the ZTF light curves, and an average X-ray flux of $(68.4 ± 15.7) $ erg s^-1 cm^-2 in the 0.1–2.4 keV range. It shows an ellipsoidal-like variability curve in the g band, with two prominent humps around phases of ∼0.0 and ∼0.7 in the i and r bands. In the spectra corresponding to these phases, a redward-increasing power-law continuum appears, which is accompanied by prominent features of cyclotron emission humps. Emission lines of He II and Balmer series were observed. The magnetic field strength of ZTF J0112+5827 was determined from the cyclotron harmonics. Its tomography map revealed the presence of accretion streams, but there was no evidence of an accretion disk structure. The line-of-sight velocity of the Balmer emission was measured at about 500 km s^-1, the majority of which was contributed by accretion streams and accretion spots. Our result confirms that ZTF J0112+5827 is a polar system. It contains a magnetic white dwarf with a magnetic field strength of $ 38.7_ MG$.

Compact mmWave measurement system for array antennas in a production environment

Abstract Millimeter wave antenna arrays are essential components of modern communication and radar systems. To produce these devices in large quantities, manufacturers require fast and reliable measurement equipment. The measurement equipment needs to ensure the quality, interoperability, and adherence to regulatory norms of the produced devices. In this work, we present an active probe array structure (PAS), which enables fast, compact, and reliable over-the-air (OTA) measurements of radiation characteristics. No relative movement between the antenna under test (AUT) and the active PAS is required, making the system very suitable for cost-effective large-scale characterization and commercial production test scenarios. We demonstrate and discuss how a near-field (NF) OTA measurement performed by this active PAS system can be used to reconstruct the far-field (FF) antenna radiation behavior of AUTs using an NF to FF correlation approach.

AN INVESTIGATION OVER THE INFLUENCE OF RADIANT THERMAL MAT DIMENSIONS ON ITS RADIATIVE AND CONVECTIVE HEAT TRANSFER CHARACTERISTICS

For living spaces, radiant thermal mats are seen to be a good substitute for traditional heating systems. The natural convection heat transfer properties of radiant heating and cooling systems have been well studied, while the properties of radiant mats placed on surfaces have received relatively less attention. Mats of square and rectangular shapes (<i>a</i> × <i>b</i> = 0.5 m × 0.5 m, 1 m × 1 m, 1.2 m × 1.2 m, 1.4 m × 1.4 m, 1 m × 1.2 m, 1 m × 1.4 m, and 1 m × 1.6 m) are installed on the walls of an enclosure with floor dimensions <i>L</i> × <i>L</i> = 4 m × 4 m and a height of <i>H</i> = 3 m in order to address this gap in the literature. Upon analyzing the complete dataset of local convective heat transfer, it is evident that there is a steady decline in the local convective heat transfer coefficients. This decline commences at the initial point of mats, which corresponds to 3 W/m<sup>2</sup> K. This trend remains rather constant until the impact of turbulence becomes noticeably apparent, which occurs when the mat dimensions are 1 m by 1.6 m. Average convective, radiative, and overall heat transfer characteristics, which are important for building energy simulation programs, are found and correlated for different mat dimensions using the surface-to-surface (S2S) radiation model and the <i>k-ε</i> RNG turbulence model in the numerical program, with error ranges of ± 15%, ± 5%, and ± 5%, respectively.

Adaptive Dual-band Antenna for 5G and ITS Applications with Monopole-to-broadside Radiation Characteristics

Adaptive Dual-band Antenna for 5G and ITS Applications with Monopole-to-broadside Radiation Characteristics

Review of Wearable Antennas: Part 1: Materials, fabrication, and radiation characteristics

Review of Wearable Antennas: Part 1: Materials, fabrication, and radiation characteristics

Engineering Leaky-Wave Antennas: Modulated Impedance Surfaces and Radiative Characteristics

Engineering Leaky-Wave Antennas: Modulated Impedance Surfaces and Radiative Characteristics