The outage probability performance of a hybrid free space optical (FSO)/radio frequency (RF) system with a reconfigurable intelligent surface (RIS) assisted full-duplex relay is presented in this paper. The FSO link follows the Gamma-Gamma distribution over pointing error and atmospheric turbulence with random foggy impairments. The RF link between the relay and the destination is subject to Nakagami-m distributions, while the RIS links and the relay self-interference (SI) link follow Rayleigh fading. As a result, the RIS-to-relay link's cumulative distribution function (CDF) of the signal to interference plus noise ratio (SINR) is obtained. On the basis of this, the system's outage probability is determined according to the decode and forward relay protocol. Thus, Monte-Carlo simulations are utilized to verify the obtained expression's accuracy. Our findings show how atmospheric turbulence, pointing errors, fog conditions, and the number of RIS reflecting elements affect the system performance. Furthermore, it is concluded that, under the identical channel conditions, heterodyne detection performs better than intensity modulation/direct detection (IM/DD).
Sepsis is a life-threatening infectious disease. Mitochondrial dysfunction is widespread in severe sepsis. The myocardium contains a large number of mitochondria, and the survival rate of sepsis decreases sharply when cardiac dysfunction is involved. Vericiguat (BAY 1021189) is a novel drug for the prevention of heart failure. In this study, we evaluated the mitochondrial function of septic mice and drug-treated mice by resonance Raman spectroscopy (RRS). RRS can accurately identify the Raman characteristic peak at 750 cm-1, 1128 cm-1 and 1585 cm-1 attributed to the reduced cytochrome in septic mice. We found that the intensity of the characteristic peak was significantly decreased in septic mice, indicating an imbalance of mitochondrial redox function, while the function was improved in the drug-treated group. It proves that BAY has the potential as a novel treatment for mitochondrial dysfunction in sepsis.
This research extends the theory of binomial array antennas. A closed-form expression for the half-power beamwidth of the array factor of an array antenna is presented. The expression is correct for the ratios of element spacing to wavelength greater than or equal to one quarter. Also, exact equations for determining the half-power beamwidth for main-beam steering are derived. A comparison with an approximate formula for the half-power beamwidth of binomial array antennas is carried out.
In the paper, a wideband circularly polarized (CP) filtering antenna is proposed, which is composed of four bent Vivaldi elements excited with sequential-rotated feeding technique. Since the Vivaldi element has the advantages of high gain and wide bandwidth, it is selected as the radiation element. On this basis, two cross slots are etched on the Vivaldi antenna to increase the gain at lower frequency band, and bent method which has less effect on the overall performance is applied for lowing the profile of the antenna. To realize filtering characteristic, the quadrature four-feed network consisting of one modified miniaturized filtering rat race coupler (FRC) and two compact wideband quadrature couplers is utilized as the sequential-rotated feeding for the Vivaldi elements. Design procedures of the Vivaldi antenna, the modified filtering FRC and the quadrature four-feed network are given. For validation, a prototype is fabricated and measured. Results show that more than 60% fractional bandwidth (FBW) is achieved under the criterions of more than 10 dB return loss and less than 3 dB axial ratio. Within the AR bandwidth, the gain is in the range of 7.5 dBic~10.1 dBic. Out of the operation band, the gain sharply decreases to be lower than -5 dBic with a rectangle coefficient (|Normalized Gain-10-dB/Gain0-dB|) of 1.25, which indicates good filtering performance.
A novel flexible printed monopole antenna with a windmill-shaped fractal design, which is fed by co-planar waveguide (CPW) is presented in this manuscript for ultra-wideband (UWB) applications. By integrating a modified windmill-shape fractal into the conventional irregular hexagonal-patch, the antenna achieves a significantly wider impedance bandwidth extending up to 156.6% across the frequency band of 1.37-11.25 GHz. Additionally, increasing the number of the windmill-shaped fractals leads to the emergence of further resonances. The overall dimensions of the designed antenna are 50 × 70 × 0.2 mm3, and it boasts an impressive bandwidth-dimension ratio (BDR) of 4457, showcasing exceptional efficiency in utilizing its compact size. The maximum gain reaches 4.8 dBi, while the radiation efficiency attains an impressive 98%. The modified windmill-shape fractal antenna design leverages the multifractal concept, providing monopole antennas with enhanced flexibility in controlling resonances and bandwidth. This manuscript offers a comprehensive presentation and discussion of the process used to improve the impedance bandwidth, shedding light on the antenna's exceptional performance and capabilities.
This paper presents a simple approach for evaluating the complex magnetic permeability of the steel fibers used in concrete according to frequency. The approach utilises the eddy current non-destructive evaluation method, where the electrical impedance is measured using a precision LCR meter and computed using a magneto-harmonic model solved in Py-FEMM software. Initially, the electrical conductivity of the steel fiber is measured using a two-contact DC method. Then, the inverse problem method is applied to identify the complex magnetic permeability. This is achieved by iteratively minimising the difference between the calculated and measured impedances using a simplex optimization algorithm. The proposed approach offers a non-contact, non-destructive, fast, and efficient procedure to evaluate the complex permeability. The obtained results provide valuable insights into evaluating the distribution of steel fibers in concrete.
The research on landslide displacement prediction can help the early warning and prevention of landslide disasters in mining areas. In view of the problem that BP neural network is prone to local convergence, and considering that the network trained based on time-series cumulative displacement may produce large errors in prediction, this paper proposes a method combining displacement increment and CS-BP (Cuckoo Search-Back Propagation) neural network to predict landslide displacement. Compared with the conventional landslide displacement prediction methods, this method uses displacement increment instead of the commonly used cumulative displacement as the network input data, and selects the CS algorithm with few parameters and easy to implement to optimize the BP network to construct the prediction model, and predicts the corresponding amount of displacement change at the next moment by the historical landslide displacement increment. Combined with the measured data of three feature points of a mine in Xinjiang, China, obtained by the micro-deformation monitoring radar, the displacement prediction accuracy of the proposed model on the three measured data sets is compared with the prediction accuracy of the BP, GA-BP (Genetic Algorithm, GA), and FA-BP (Firefly Algorithm, FA) network prediction models based on cumulative displacement and incremental displacement, respectively. The experimental results show that this method achieves superior performance with an average root mean square error of 0.3261 and an average mean absolute error of 0.2785 across the three feature points, outperforming the other models, and holds promising applications in disaster prevention and control work.
A novel microstrip loop-type resonator with four resonant modes is proposed in this letter. The resonator is formed by a loop-type microstrip line loaded with four shorted stubs. It has a symmetrical structure, thus the odd-even-mode method is adopted to implement the resonant analysis. The novelty of the proposed resonator lies in two aspects. One is that its resonant frequencies can be adjusted in a more flexible way. The other is that its resonant modes have a uniform electromagnetic field distribution, which is beneficial for the excitation of resonant modes. For the purpose of demonstration, based on the novel resonator, a single-band bandpass filter with four transmission poles and a dual-band bandpass filter with two transmission poles in each passband are constructed. Additionally, source-load cross coupling is introduced, and several transmission zeros are generated in the stopband, which improves the out-of-band performance greatly. The designed single-band filter has the central frequency of 2.4 GHz and fractional bandwidth (FBW) of 4.5%, and the dual-band filter has the central frequency of 1.8/2.4 GHz and fractional bandwidth of 2.0%/2.5%. The two bandpass filters are designed, fabricated, and measured. Agreement between the simulated and measured results verifies the effectiveness of the proposed resonator and filters.
This paper presents the design of a planar tunable Negative Group Delay (NGD) circuit with low reflections. A pulse-shaped stub inscription on the signal strip of a microstrip line generates a negative group delay, which can then be tuned to a desired value by varying the resistance inside the inscription. Poor reflection characteristics are inherent in such circuits, and a conventional solution like a simple impedance matching circuit compromises the overall NGD performance for a reduced reflection loss. Here, we have included a novel impedance-matching network loaded with absorptive elements at the input/output ports to avoid any reflections from the circuit, while maintaining its NGD behavior and compactness. The measured results validate the proposed design with -5 ns GD at 3 GHz with less than -10 dB reflection loss over the whole NGD bandwidth of 228 MHz at 3 GHz.
An accurate, efficient and scalable SPICE model is essential for modern integrated circuits design, especially for radio frequency (RF) circuit design. A PSP based scalable RF model is extracted and verified in 0.11 μm CMOS manufacturing process. The S parameter measurement system and open-short de-embedding technique is applied. The macro-model equivalent subcircuit and parameters extraction strategy are discussed. The extracted model can match the de-embedded S parameters data well. By combining the model parameters' dependencies on each geometry quantity, the scalable expression of parameters with all geometry quantities included can be obtained. This work can be a reference for the RF MOSFETs modeling and RF circuit design.
This letter investigates a differential, planar and wideband antenna on a commercial organic printed circuit board (PCB) substrate at 240 GHz with a novel packaging concept to integrate massive monolithical integrated circuits (MMICs). The antenna utilizes multiple series resonators to achieve a bandwidth of 75 GHz around 240 GHz. A novel differential bond wire package solution from chip to antenna feeds the differential antenna from an on-chip Marchand balun. The fabrication of the antenna and interconnect are analyzed, and potential improvements for future works are highlighted. Measurement proves the function of the designed package, which is competitive to the state of the art.
In this paper, a broadband compact dual-polarized antenna for base stations is proposed. This antenna consists of a pair of crossed dipoles, four triangular parasitic patches, four metal posts and a box reflector. The crossed dipoles are fed by two 50 Ω coaxial cables. The increase of four parasitic patches allows the resonant point to be generated at high frequencies to further widen the impedance bandwidth; the size of the parasitic patches is reduced to realize the reduction of the antenna radiator size; and the impedance matching is improved by cutting circular slots in the dipole arms. The measured results show that the proposed antenna is able to achieve a wide impedance bandwidth of 79% (1.67 to 3.87 GHz) with VSWR less than 1.6. A stable gain of 8-8.7 dBi and a half-power beamwidth (HPBW) of 60-78° are obtained at 2.2-3.65 GHz. In addition, the antenna radiator is very compact in size, only about 0.41λL × 0.41λL × 0.17λL, where λL is the longest operating wavelength.
For long-range communication, the directivity and gain of a millimeter wave antenna should be high. The aim of the paper is to design an antenna array that works at higher frequencies X/Ku-band (8-12 GHz)/(12-18 GHz) respectively for applications such as RADAR. This can be achieved by an array of antennas as single antenna cannot provide such high gain and directivity. The radiation pattern has directional pencil beam in which the frequency and gain plot is shown at 11.32 GHz. The maximum gain of 29.0994 dB has been achieved at 11.32 GHz frequency. The software High Frequency Structure Simulator (HFSS) has been used for simulation, and the simulated and measured results are found in agreement with each other
Ultrasmall nanoparticles with tunable photo-optical properties and colloidal nature are ideal for a wide range of photocatalytic reaction. Herein, we reported the facile synthesis of ultrasmall aluminum nanoparticles (AlNPs), which exhibited unique UV-B photoluminescence and excitation wavelength dependent fluorescence characteristic. Spherical aberration-corrected scanning transmission electron microscope (ACTEM) and X-ray photoelectron spectroscopy (XPS) were used to study the microstructure and verify the successful synthesis of AlNPs. Time-resolved photoluminescence spectroscopy was employed to gain insight into the unique photoluminescence behavior. The photocatalytic activity of ultrasmall AlNPs was evaluated by the photoreduction of resazurin (RZ) to resorufin (RF) under UV light irradiation. This photodegradation of RZ obeyed the pseudo-first-order reaction kinetics with reaction rate achieved 6.62 × 10-2 min-1. Our study suggested that the prepared ultrasmall AlNPs have a great potential application in photocatalytic field.
In this paper, equivalent circuit models are first presented for characterizing the CPW SSPPs with etched slot. The asymptotic frequency and dispersion are investigated based on the theoretical model. And the analyses reveal that both the asymptotic frequency and dispersion curve can be manipulated by changing the inductance brought by the etched slots and the capacitance of the loaded capacitors. To validate the propagation performance, the proposed SSPP structure was fabricated and tested. The experimental results are consistent with the theoretical analysis, indicating that the designed SSPP structure possesses excellent low-pass filtering characteristics. Compared with traditional SSPP structures, the proposed structure exhibits a much narrower transversal width and does not require mode-conversion structures.