Double Modulation Research Articles

Ecological compensation mechanism under the double control of water quality and quantity in the Bai River Basin

Watershed ecological compensation is an effective economic policy measure for water ecology conservation and water environment management. This study constructed an eco-compensation mechanism under the double control of water quality and quantity, which consisted of the water quality control module, the water quantity control module, and the double control compensation value module. The pollution loss water quantity and the river habitat compensation water quantity were calculated, and the water quality achievement or excess and water quantity surplus or deficit were identified to divide the multi-scenario compensation mode and obtain the double control compensation value. The Bai River Basin in Nanyang, China, was selected as the case study, and the double control compensation value of the three counties in the basin was calculated from 2015 to 2018. The results showed that the water quantity compensation value of all counties was higher than the water quality compensation value, indicating that the water quantity has a greater impact on the water environment compared with water quality, and the ecological water demand of rivers needs to be guaranteed while strengthening water pollution treatment. The compensation mode all belonged to the double control mode. The double-control compensation mechanism had a distinct advantage over the single-control compensation, indicating that water quality and quantity should be considered in the compensation programs to maintain healthy ecological conditions in the water supply. The research results provide ideas for the quantification of eco-compensation and the formulation of long-term ecological protection mechanisms.

A robust method based on reinforcement learning and differential evolution for the optimal photovoltaic parameter extraction

It is crucial to identify the optimal parameters of Photovoltaic (PV) models with the purpose of evaluating, controlling, and improving PV systems. Lots of optimization algorithms have been developed to solve the problem and achieve better results. But, the performance of most algorithms is greatly influenced by their parameters. A Reinforcement Learning-based Adaptive Parameter and Mutation operator Differential Evolution algorithm (RLAPMDE) is developed, in which the parameters of algorithms are randomly set in [0,1], and the mutation operator is adaptively adjusted between Rand/1 and Best/1. Rand/1 is mainly responsible for exploration, while Best/1 is to implement exploitation. Exploration and exploitation are well balanced. RL technique is used to realize the process through interaction with the environment. The RLAPMDE is employed to identify the optimal parameters of PV. The dataset used in experiments is Single Diode Model (SDM), Double Diode Model (DDM) and PV module. The results of the best RMSE obtained by RLAPMDE are 9.8602E-4, 9.8248E-4, 2.4251E-3, 1.7298E-3 and 1.6601E-2, which are the minimum when compared with the conventional DE, five DE variants, six latest meta-heuristic algorithms and some reported results. The proposed PLAPMDE algorithm is one of the alternative algorithms when estimating the parameters of PV systems.

Coupling Projection Synchronization of Three Chaotic Systems and Its Multilevel Secure Communication via DNA CRNs

The complete synchronization of two chaotic systems and its secure communication have been considered based on DNA chemical reaction networks (DNA CRNs). There are concerns about the security of the single-level chaotic secure communication system. Thereby a multi-level secure communication scheme is put forward via DNA CRNs in this work. Firstly, a three-variable chaotic system that consists of catalysis, double, fasciation, and annihilation modules is constructed using DNA CRNs. Secondly, according to the stability principle of nonlinear systems, DNA CRNs are adopted to realize the coupling projection synchronization of three chaotic systems, and the synchronization results are discussed. Finally, sine and cosine signals are designed using DNA CRNs. These signals are added into three systems to realize multi-level encryption and decryption. Furthermore, the interference terms are taken into consideration to test the robustness of the system. The results show that the proposed scheme has high security, and can efficiently encrypt and decrypt biological signals through multi-level transmission in the presence of interference.

Tunneling conductance regulated by the electrostatic barrier in monolayer black phosphorene

We investigate the tunneling conductance of monolayer black phosphorene through double magnetic barriers modulated by the electrostatic barrier. This magnetic barrier is generated by two ferromagnetic strips deposited on monolayer phosphorene and can form parallel (P) and antiparallel (AP) structures. Applying a voltage to a ferromagnetic strip will create an electrostatic barrier. The transmission of P and AP magnetic structures is calculated using the transfer matrix. Tunneling conductance is given by Landauer–Büttiker theory. Our results show that under double electrostatic barriers modulation, the AP conductance of the system is zero except for sharp peaks, while the P conductance has a certain value, which implies a large tunneling magnetoresistance. However, in the case of single electrostatic barrier modulation, the conductance becomes flat. For the Fermi level in the valence band, the movement of the Fermi level leads to the severe mismatching of transmitted wave vectors in the barrier region, resulting a positive and negative oscillation magnetoresistance. This may be useful for designing memory using a two-dimensional electron gas system.

Transformer With Double Enhancement for Low-Dose CT Denoising.

Increasingly serious health problems have made the usage of computed tomography surge. Therefore, algorithms for processing CT images are becoming more and more abundant. These algorithms can lessen the harm of cumulative radiation in CT technology for the patient while eliminating the noise of image caused by dose reduction. However, the mainstream CNN-based algorithms are inefficient when dealing with features in broad regions. Inspired by the large receptive field of transformer framework, this paper designs an end-to-end low-dose CT (LDCT) denoising network based on the transformer. The overall framework of network contains a main branch and dual side branches. Specifically, the overlapping-free window-based self-attention transformer block is adopted on the main branch to realize image denoising. On the dual side branches, we propose double enhancement module to enrich edge, texture, and context information of LDCT images. Meanwhile, the receptive field of network is further enlarged after processing, which is helpful for building model's long-range dependencies. The outputs of the side branches are concatenated to the middle layer of the network for enhancing information and generating high-quality CT images. In addition, to better train the network and achieve the expected results, we introduce a compound loss function including mean squared error (MSE), multi-scale perceptual (MSP), and Sobel-L1 (SL) to make the denoised image closer to the targeted norm-dose CT (NDCT) image. Lastly, we conducted experiments on two clinical datasets including abdomen, head, and chest LDCT images with 25%, 25%, and 10% of the full dose, respectively. The experimental results demonstrated that the proposed DEformer achieved better denoising performance than the existing algorithms.

The effect of storage conditions on the long-term stability of ethylene-vinyl-acetate (EVA) copolymer used in glass/glass modules

We evaluate the effect of storage conditions of uncured encapsulant rolls and the potential consequences on photovoltaic (PV) module performance. We show the impact of residual water trapped inside laminated double glass PV modules after lamination and during UV exposure. We focus on ethylene vinyl acetate (EVA) copolymer and its stability over 630 kWh/m2 UV exposure (equivalent to 10 years of outdoor exposure in a Central European country). Three storage conditions were tested by simulating different moisture contents to mimic relative humidity variations that can occur when polymeric foils are exposed to an uncontrolled environment, such as the PV module production line, next to the laminator machine. The presence of water during lamination had no apparent impact on module quality and performance after the fabrication but only became apparent during the aging test. The module power loss was directly related to the EVA chemical and physical degradation and varied depending on the storage history. Results indicate that when the storage is not too harsh, its effect can be somehow mitigated. Based on our observations, we leave a door open to the adoption of high-quality EVA polymers in the manufacturing of glass-glass modules. However, the storage and handling conditions prescribed by the supplier should be carefully respected.

Optical Tunable Frequency-Doubling OEO Using a Chirped FBG Based on Orthogonally Polarized Double Sideband Modulation

We propose and experimentally demonstrate a tunable frequency-doubling optoelectronic oscillator (FD-OEO) based on a single-bandpass dispersion-induced microwave photonic filter (MPF) consisting of a Mach–Zehnder modulator (MZM), a linearly chirped fiber Bragg grating and polarization-multiplexed dual-loop. Thanks to the polarization dependence of the MZM, a special double sideband modulation is implemented where the optical carrier (OC) and subcarriers are orthogonally polarized. By simply tuning the PC in the OEO loop, the phase difference between the orthogonal polarization carrier and two sidebands can be controlled, and thus the center frequency of the fundamental OEO can be tuned. Furthermore, a PC and a polarizer are placed outside the OEO to achieve optical carrier suppression (OCS) modulation, which ensures that a frequency-tunable microwave signal at the second-harmonic frequency is generated. In the experiment, a fundamental frequency signal with tunable frequency from 3.6 to 6.85 GHz and FD-OEO with a tunable frequency range from 7.2 to 13.7 GHz are generated.

Experimental investigation and analysis of cooling performance of solar thermoelectric refrigerator

Nowadays, a potential alternate source of renewable energy for heating and cooling purposes is solar thermal energy. In remote areas electricity problems, the solar cooling and heating are very useful for living. The present research is focus to develop a solar thermoelectric refrigerator (STER) by using thermoelectric module based on principles of Peltier effect (creating cold and hot zone). Inside the refrigerator compartment, the cold side zone of the thermoelectric module is used for refrigeration. However, the rejected heat from other hot side of module to ambient surrounding through heat sinks and fans. The experimental model considers a steel aluminium box of dimension 200 × 195 × 300 mm3 having two thermoelectric (TE) modules and two heat sink with cooling fan to investigate the performance evaluation of solar thermoelectric refrigerator. The STER unit utilises a 100 W solar panel. The experimental result of double module with internal fan shows that the STER unit reduces room temperature of 33 °C to 4.1 °C in 44 min with coefficient of performance (COP) of 0.61. Therefore, the present novel refrigeration system is augmented for domestic and medicine storage purpose in remote area with economically viable and environmental friendly.

Microwave photonic dispersion immune self-interference cancellation scheme for a radio over fiber based in-band full duplex communication link

A microwave photonic scheme for multi-functional radio over fiber based in-band full duplex communication links to realize deep self-interference cancellation, long range transmission, and efficient signal recovery is proposed. In the proposed scheme, double sideband modulation helps avoid applying electrical couplers or optical filters and is beneficial to improve the frequency conversion efficiency. By virtue of the intermediate frequency signal amplitude regulation mechanism induced by fiber dispersion, the conditions of dispersion induced power fading compensation, amplitude matching, and phase reversion between self-interference and reference signals can be satisfied through joint DC bias tuning. The high precision delay matching in the optical domain is advantageous to the deep self-interference cancellation performance in a wide frequency range compared to its electrical counterparts. Furthermore, the deterioration of signal quality and self-interference cancellation performance caused by fiber dispersion is avoided. Experimental analyses show that a single tone signal in a wide frequency range of 2–20 GHz can be cancelled over 60 dB. A broadband signal with bandwidth of 50 MHz in the C-band, X-band, and K-band can be cancelled over 35 dB. Furthermore, the recovery performance of the signal of interest with different modulation formats and different signal to interference ratios is investigated, showing high quality signal transmission and efficient signal recovery. The capability of dispersion induced power fading compensation is also verified, and the spurious-free dynamic range is measured to be 88.47dB⋅Hz2/3.

Ultrasound-Based Directional Sound System via Double Sideband Amplitude Modulation

With unique advantages of reducing noise pollution, lengthening the propagation distance, directional sound system (DSS) is a novel technology to control sound directivity based on modulation algorithm. By using the double side band amplitude modulation (DSB-AM), we successfully design a DSS device and the experimental verification is conducted to evaluate the performance of the sound directivity with different ultrasonic array. The modulation and self-demodulation based on DSB-AM is simulated, which proves theoretically that the audible sound can be transmitted with ultrasound signal and recovered in air. The sound directivity influenced by operating frequency is simulated to determine carrier frequency. To attain optimal arrangement of the ultrasound array, the square and rectangular array is constructed in the simulation. We develop a DSS hardware configuration to investigate sound directivity of ultrasonic array. It proves that the envelope of the modulated signal is matched with the original audio signal when modulation factor m=0.5 is chosen, which can ensure the performance of transmitting sound. The sound directivity of ultrasonic array is evaluated qualitatively and quantitatively. The experiments show that the 7×7 array has the better sound directivity than the rest of arrays, where the minimum emitting angle of main beam is produced. Sound directivity demonstration solidly verifies the superiority of 7×7 array in audible music propagation.

Efficient photonics beam forming system incorporating super structure fiber Bragg grating for application in Ku band

We propose and demonstrate a photonic true-time delay beamforming system for a 1 × 4 linear phased array antenna, operating in the Ku-band, based on superstructured fiber Bragg gratings (SFBGs) with linearly rising equivalent chirps. The proposed beam-forming network operates at 18 GHz frequency, which is theoretically analyzed and simplified by simulated results. The SFBG has a distinct number of gratings in each beamforming path, which provides a large and progressive phase delay. The advantage of the proposed technique can be found in terms of its wavelength tunable scheme making the system squint-free. The proposed architecture is a true time delay optical beam forming a network, which enables squint-free beam steering of radio frequency (RF) signals. In this study, a technique known as double sideband modulation of multiple wavelengths is utilized to investigate the reflection quality of SFBG at various chirp rates. Taking into account that each segment of FBG consists of 50, 60, 70, and 80 gratings and phase shift section samples of each segment, the overall length of the SFBGs is calculated to be 2 cm, 2.4 cm, 2.8 cm, 3.2 cm, respectively, are used for calculating group delay. An equation in a closed form representing the corresponding dispersion is derived. SFBG group delay response is analyzed theoretically with required simulation to investigate the reflectance characteristics. All simulation work for designing the beam forming system is done on Optisystem version 19 and designing of Super structure fiber Bragg grating Optigrating version 4.2. The optically process wavelengths are detected by high speed dedicated photo-detector (PD) and delay response is investigated through array factor of each antenna. Errors in the fabricated SFBGs' group delay responses are examined also.

Transformer-based 3D U-Net for pulmonary vessel segmentation and artery-vein separation from CT images.

Transformer-based methods have led to the revolutionizing of multiple computer vision tasks. Inspired by this, we propose a transformer-based network with a channel-enhanced attention module to explore contextual and spatial information in non-contrast (NC) and contrast-enhanced (CE) computed tomography (CT) images for pulmonary vessel segmentation and artery-vein separation. Our proposed network employs a 3D contextual transformer module in the encoder and decoder part and a double attention module in skip connection to effectively finish high-quality vessel and artery-vein segmentation. Extensive experiments are conducted on the in-house dataset and the ISICDM2021 challenge dataset. The in-house dataset includes 56 NC CT scans with vessel annotations and the challenge dataset consists of 14 NC and 14 CE CT scans with vessel and artery-vein annotations. For vessel segmentation, Dice is 0.840 for CE CT and 0.867 for NC CT. For artery-vein separation, the proposed method achieves a Dice of 0.758 of CE images and 0.602 of NC images. Quantitative and qualitative results demonstrated that the proposed method achieved high accuracy for pulmonary vessel segmentation and artery-vein separation. It provides useful support for further research associated with the vascular system in CT images. The code is available at https://github.com/wuyanan513/Pulmonary-Vessel-Segmentation-and-Artery-vein-Separation .

The electronic structure and dynamics of the excited triplet state of octaethylaluminum(III)-porphyrin investigated with advanced EPR methods

The photoexcited triplet state of octaethylaluminum(III)-porphyrin (AlOEP) was investigated by time-resolved Electron Paramagnetic Resonance, Electron Nuclear Double Resonance and Electron Spin Echo Envelope Modulation in an organic glass at 10 and 80 K. This main group element porphyrin is unusual because the metal has a small ionic radius and is six-coordinate with axial covalent and coordination bonds. It is not known whether triplet state dynamics influence its magnetic resonance properties as has been observed for some transition metal porphyrins. Together with density functional theory modelling, the magnetic resonance data of AlOEP allow the temperature dependence of the zero-field splitting (ZFS) parameters, D and E, and the proton AZZ hyperfine coupling (hfc) tensor components of the methine protons, in the zero-field splitting frame to be determined. The results provide evidence that the ZFS, hfc and spin–lattice relaxation are indeed influenced by the presence of a dynamic process that is discussed in terms of Jahn-Teller dynamic effects. Thus, these effects should be taken into account when interpreting EPR data from larger complexes containing AlOEP.

Study on effective front region thickness of PCM in thermal energy storage using a novel semi-theoretical model

Thermal energy storage in mobile applications, particularly battery of electric vehicles, is currently gaining a lot of importance. In this paper, a semi-theoretical time-dependent mathematical model of the phase change in a double shell thermal energy storage module has been developed where the inner tube is a heat exchange surface. An effective front region thickness for the melting and solidification process has been studied. The proposed model is calibrated based on our experimental data. The purpose of such a model is to enable the optimization of the geometry of the energy storage modules in terms of the PCM to the TES container mass ratio and enhancement of phase change rate. In addition, results obtained for a single tube can be used in the bundle of tubes in shell and tube TES design. The results have shown that for the larger diameter of the module (smaller difference between the working tube and shell diameter) the optimal working time is around 2000 s.

Algorithms for searching and detecting navigation signals with double meander modulation with a different number of spectral components

One of the main directions of improving the accuracy characteristics of navigation equipment of consumers of global navigation satellite systems is the use of new types of navigation signals, in particular, signals with double meander modulation. However, these signals have a relatively high level of closely spaced side lobes of the autocorrelation function, which makes it difficult to solve the problem of unambiguous measurements during search and tracking. To conduct a study of the noise immunity of algorithms for searching and detecting navigation signals by double meter modulation. Analytical expressions are obtained for calculating the total envelope at the detector output using four and two spectral components of a navigation signal with double meander modulation. It is revealed that the detection algorithm using four spectral components of a signal with double meander modulation to form the total envelope has better noise immunity than the detection algorithm using two spectral components. It is shown that the detection algorithm using two spectral signal components with double meander modulation, due to the simplicity of implementation, ensures compatibility with the existing navigation equipment of consumers of global navigation satellite systems. As a result of mathematical modeling, the dependences of the probability of the search ending with the correct detection on the signal/interference ratio are obtained. The presented research results can be used by specialists in the field of satellite radio navigation in the modernization of global navigation satellite systems, as well as in the development of advanced navigation equipment for consumers working with signals with double meander modulation.

Multiplexed Active Clamp High-Frequency Link Inverter With De–Re-Coupling Frequency Doubling Modulation

In this paper, a multiplexed active clamp high-frequency link inverter (MACHFLI) with de-re-coupling frequency doubling modulation (DFDM) is proposed. The proposed MACHFLI consists of a primary inverter, high-frequency transformer, multiplexed active clamp (MAC) circuit, and cycloconverter. MAC recycles leakage inductance energy and eliminates voltage spikes caused by leakage inductance. Overlapping commutation is designed in the DFDM to ensure the safe commutation of the output filter inductor current and realize the ZVS of the cycloconverter. The ZVS of the primary inverter can be realized utilizing magnetizing current, and full-range ZVS of MAC can also be realized with turn-on delay. The operating principle and ZVS conditions of the proposed MACHFLI are analyzed, and the design of the transformer and clamp capacitor is discussed in this paper. Finally, a 1kW prototype is made to verify the analysis results. Experimental results show that MACHFLI has Four-quadrant operation capability, good dynamic response, high efficiency over a wide load range, and peak efficiency reaches 95.4%.

Corrections to “Photonic Sub-Terahertz IM Links: Comparison Between Double and Single Carrier Modulation” [Sep 22 6064-6070

In this manuscript we report four mistakes in [1] and their respective corrections. Two mistakes are notation typos with no implications, whereas the other two are mistakes regarding the simulations. The correction of these two mistakes changes slightly the technical analysis presented in [1], however, they do not affect the main conclusions reported in such a paper.

A Novel Closed-Loop Control to Solve Light Source Power Fluctuations in the Fiber-Optic Gyroscope

The performance of a gyroscope is directly affected by the fluctuations in the light source power (LSP) in an interferometric fiber-optic gyroscope (IFOG). Therefore, it is important to compensate for fluctuations in the LSP. When the feedback phase generated by the step wave completely cancels the Sagnac phase in real-time, the error signal of the gyroscope is linearly related to the differential signal of the LSP, otherwise, the error signal of the gyroscope is uncertain. Herein, we present two compensation methods to compensate for the error of the gyroscope when the error is uncertain, which are double period modulation (DPM) and triple period modulation (TPM). Compared with the TPM, DPM has better performance, but it increases the requirements for the circuit. TPM has lower requirements for the circuit and is more suitable for small fiber- coil applications. The experimental results show that, when the frequency of the LSP fluctuation is relatively low (1 kHz and 2 kHz), DPM and TPM do not differ significantly in terms of performance; both of them can achieve an improvement of about 95% in bias stability. When the frequency of the LSP fluctuation is relatively high (4 kHz, 8 kHz and 16 kHz), DPM and TPM can achieve about 95% and 88% improvement in bias stability, respectively.

Approximation by linear combinations of translates in invariant Banach spaces of tempered distributions via Tauberian conditions

This paper describes an approximation theoretic approach to the problem of completeness of a set of translates of a “Tauberian generator”, which is an integrable function whose Fourier transform does not vanish. This is achieved by the construction of finite rank operators, whose range is contained in the linear span of the translates of such a generator, and which allow uniform approximation of the identity operator over compact sets of certain Banach spaces (B,‖⋅‖B). The key assumption is availability of a double module structure on (B,‖⋅‖B), meaning the availability of sufficiently many smoothing operators (via convolution) and also pointwise multipliers, allowing localization of its elements. This structure is shared by a wide variety of function spaces and allows us to make explicit use of the Riesz–Kolmogorov Theorem characterizing compact subsets in such Banach spaces.The construction of these operators is universal with respect to large families of such Banach spaces, i.e. they do not depend on any further information concerning the particular Banach space. As a corollary we conclude that the linear span of the set of the translates of such a Tauberian generator is dense in any such space (B,‖⋅‖B). Our work has been inspired by a completeness result of V. Katsnelson which was formulated in the context of specific Hilbert spaces within this family and Gaussian generators.

Triple immune modulator therapy for aberrant hyperinflammatory responses in severe COVID-19

A dysregulated hyperinflammatory response is a key pathogenesis of severe COVID-19, but optimal immune modulator treatment has not been established. To evaluate the clinical effectiveness of double (glucocorticoids and tocilizumab) and triple (plus baricitinib) immune modulator therapy for severe COVID-19, a retrospective cohort study was conducted. For the immunologic investigation, a single-cell RNA sequencing analysis was performed in serially collected PBMCs and neutrophil specimens. Triple immune modulator therapy was a significant factor in a multivariable analysis for 30-day recovery. In the scRNA-seq analysis, type I and II IFN response-related pathways were suppressed by GC, and the IL-6-associated signature was additionally downregulated by TOC. Adding BAR to GC and TOC distinctly downregulated the ISGF3 cluster. Adding BAR also regulated the pathologically activated monocyte and neutrophil subpopulation induced by aberrant IFN signals. Triple immune modulator therapy in severe COVID-19 improved 30-day recovery through additional regulation of the aberrant hyperinflammatory immune response.