Side Of Peak Research Articles

A Synchronization Algorithm for MBOC Signal Based on Reconstructed Correlation Function

In order to address the ambiguous synchronization problem caused by the multi-peak nature of the autocorrelation function of the modulated signal of the Multiplexed Binary Offset Carrier (MBOC) in the Global Navigation Satellite System (GNSS), a new synchronization algorithm for MBOC signals is presented in this paper, which uses a reconstruction correlation function to effectively handle synchronization ambiguities associated with multi-peak signals. The paper proposes an algorithm for reconstructing the correlation function of the MBOC signal by analyzing its characteristics. The algorithm generates three local auxiliary signals, namely, pseudo-random codes (PRN), BOC(1,1) signals, and MBOC signals, which are correlated with the received signal. By combining the three correlation functions, the algorithm produces a reconstructed correlation function based on reconstruction rules, eliminating side peaks and achieving unambiguous synchronization. Simulation results show that the proposed algorithm in this paper eliminates all side peaks while maintaining a high detection probability, and its deblurring capability is optimal compared to other algorithms. In addition, the discriminant curve shows that the algorithm in this paper successfully eliminates all the mis-locked points, and the slope gain is improved by more than 2.5 dB compared with other algorithms, and the anti-multipath performance of the algorithm in this paper is better than that of other traditional algorithms, such as ASPeCT (Autocorrelation Side-Peak Cancellation Technique).

Visual localization and quantitative detection method for thermal defects in cable terminals of high-speed trains based on a temperature derivative

Abstract Cable terminal defect detection plays an important role in ensuring the safe and stable operation of high-speed trains (HST). In this paper, a numerical model of the electromagnetic thermal field of overheating defects of cable terminal shielding grids and a method of detecting internal defects of cable terminals - even-order temperature derivative (EOTD) is proposed for quantitative detection of internal defective structures of vehicle-mounted cable terminals. Firstly, a numerical model of the electromagnetic thermal field of cable terminals under the condition of leakage current is constructed, through which the temperature field distribution characteristics of different defective structures are analyzed. Then, the intuitive location of the defective region is obtained by investigating the derivative characteristics of the temperature image, and the depth and intensity of the defects are quantitatively assessed by using the main side peak (MSP) distances and the MSP values extracted from the derivative curves. Finally, the simulation and experimental results achieve the identification of defect structures and the quantitative detection of defect depth and intensity, proving the effectiveness and accuracy of the proposed method.

Coupled twiss parameters estimation from turn-by-turn data

Linear optics parameters are often estimated using turn-by-turn (TbT) data. In-plane beta functions, which are the most common measurement objectives, can be estimated from the amplitudes or phases of TbT data, providing an overall characterization of the linear lattice. In addition to estimating uncoupled Twiss parameters, TbT data can also be utilized for characterizing coupled linear motion. We investigate several methods for constructing a full normalization matrix at each beam position monitor (BPM). BPMs provide information on beam centroid transverse coordinates, but direct observation of transverse momenta is not available. To estimate momenta, one can use a pair of BPMs or fit data obtained from several BPMs. By using both coordinates and momenta, it is possible to fit the one-turn matrix (or its power) at each BPM, allowing for the computation of coupled Twiss parameters. Another approach involves the minimization of side peak amplitudes in the spectrum of normalized complex coordinates. Similarly, the normalization matrix can be estimated by fitting linear coupled invariants. In this study, we derive and utilize a special form of the normalization matrix, which remains non-singular in the zero coupling limit. Coupled Twiss parameters can be obtained from the normalization matrix. The paper presents the results of applying and comparing these methods to both modeled and measured VEPP-4M TbT data, demonstrating effective estimation of coupled Twiss parameters.

Enhanced frame synchronization and carrier recovery in coherent FSO communication: a pseudo-random and cyclic QPSK approach.

To alleviate the impact of atmospheric turbulence on receiver carrier recovery in free-space optical communication, this study introduces a novel frame synchronization and carrier recovery method. This method employs a blend of pseudorandom sequences and specific cyclic quadrature phase shift keying (QPSK) training sequences, facilitating frame synchronization and frequency offset (FO) estimation. The research designs a time-series metric curve to counteract the effect of side peaks, enhancing the accuracy of frequency offset estimation via QPSK spectrum features. Furthermore, the method incorporates a two-stage frequency offset estimation process, utilizing the inherent sign characteristics of the x and y polarization states. Applied to the quadrature amplitude modulation system under atmospheric turbulence conditions, the proposed algorithm demonstrates high precision under both strong and weak turbulence conditions. Furthermore, we confirmed the universality of the algorithm across multiple modulation formats.

Ab initio calculations on magnetic and optical characteristics of pure ZnO and Mn(II)-doped ZnO monolayers with and without neutral charged vacancies defects

At high Curie temperatures, diluted magnetic semiconductors exhibit induced ferromagnetism and spin-dependent interactions, making them useful in magneto-electronic devices. In spite of the fact that ferromagnetism and optical emission dynamics are characterized by intricate microstructural and compositional features, the origins of these phenomena are not yet completely understood. Here, we used first principles calculations to study how vacancy defects affect the electrical, optical, and magnetic properties of pure ZnO and Mn@ZnO monolayers. In the pristine monolayer, the Zn vacancy produces magnetism with a total magnetic moment of 2 μB, but the oxygen vacancy does not. The magnetic semiconducting characteristic of the Mn substitution at the Zn site is shown by a total magnetization of 5 μB. The magnetic ground state of the ZnO monolayer doped with Mn is significantly influenced by the presence of native defects. More specifically, Zn vacancies are essential for stabilizing the FM states due to the bound magnetic polarons (BMPs) formation, but O vacancies have no influence on the magnetic ground state of the Mn(II)@ZnO monolayer. Based on the optical study, we discovered that Zn and O vacancies in the ZnO ML produce optical absorption peaks at 1.92 eV and 2.90 eV, respectively. The substitution of Mn(II) at Zn site not only increases the band gap of the ZnO monolayer but also produces d-d transition bands at lower energy side of fundamental energy gap peak. The Zn vacancies in the Mn(II)@ZnO ML produce an infrared absorption band around 1.13 eV, which could be due to the formation of the BMP, and enhance the optical absorption efficiency. The ZnO ML’s energy gap and Mn ion’s d-d transition bands exhibit a blueshift in AFM systems and a redshift in the FM systems. In far configuration, the Mn(II)@ZnO monolayer show no shift in the fundamental bandgap and intra-band transition of the Mn(II) spins due to the Mn(II) ion’s paramagnetic nature.

Interaction with the Extratropics as a New Hypothesis for the Spectral Peak of the Madden–Julian Oscillation

Abstract The Madden–Julian oscillation (MJO) propagates eastward as a disturbance of mostly zonal wind and precipitation along the equator. The initial diagnosis of the MJO spectral peak at 40–50-day periods suggests a reduction in amplitude associated with slower MJO events that occur at lower frequencies. If events on the low-frequency side of the spectral peak continued to grow in amplitude with reduced phase speed, the spectrum would just be red. Wavelet regression analysis of slow and fast eastward-propagating MJO signals during northern winter assesses how associated moisture and wind patterns could explain why slow MJO events achieve lower amplitude in tracers of moist convection. Results suggest that slow MJO events favor a ridge anomaly over Europe, which drives cool dry air equatorward over Africa and Arabia as the active convection develops over the Indian Ocean. We hypothesize that dry air tracing back to this source, together with a longer duration of the events, leads to associated convection diminishing along the equator and instead concentrating in the Rossby gyres off the equator. Significance Statement The Madden–Julian oscillation (MJO) dominates the subseasonal variability of the tropical atmosphere. This work suggests that it favors maximum convective activity in the 40–50-day period range because lower-frequency MJO signals tend to import more cool dry air from the extratropics and along the equator, thereby weakening the slower events.

Baddeleyite U-Pb age and whole-rock geochemical characteristics of ∼ 1670 Ma diabase dyke in the Shennongjia area: Implications for the tectonic setting of northern Yangtze Craton during the late Paleoproterozoic

The Shennongjia Group in the northern margin of the Yangtze Craton consists mainly of thick carbonate rocks interlayered with some intervals of volcanic and terrigenous clastic rocks. With the geochronological achievements in recent years, the depositional age of this group can be constrained into the time span of 1400–1000 Ma at present, belonging to the Mesoproterozoic Ectasian period. It is also a potential candidate interval for the “Undefined System/Period” in the Regional Chronostratigraphic Chart of China. According to the 1:200,000-scale conventional regional geological survey in the ‘1960–1970 s’, at the northwest side of the dominant peak of the Mt. Shennongding, it shows a ring-shaped gabbro-diabase dyke intruded in these Ectasian formations. However, due to the lack of comprehensive studies, there are lots of controversy both about the intrusion time and the tectonic setting of the mafic dyke.In this study, by means of the LA-ICP-MS and SHRIMP method successfully, the baddeleyite from the Banbiyan gabbro-diabase dyke yielded gained the weighted average 207Pb/206Pb age 1668.3 ± 5 Ma (MSWD = 1, N = 53) and 1667.8 ± 7 Ma (MSWD = 0.7, N = 23), respectively. It represents an unambiguous late Paleoproterozoic Statherian Period magmatic event in northern Yangtze Craton. Further, for the first time, it indicates the existence of the geological records prior to ∼ 1.67 Ga in the Shennongjia area.In addition, Banbiyan gabbro-diabase samples have relatively concentrated SiO2 (48.33 % to 49.65 %) and high whole iron content (10.25 % to 12.78 %). They show Na2O + K2O ranging from 2.9 % to 4.64 % and TiO2 from 1.36 % to 1.62 %. All samples are enriched in LILE, e.g., Rb, K, and Ba. The REE pattern shows a moderately right-inclined curve between E-MORB and OIB. These geochemiacal characteristics are agreed with contemporaneous magmatic event in the southwestern Yangtze Craton, indicating a within-plate rifting background and should correspond to the rifting of the Columbia Supercontinent.

Method for measuring time waveforms of minute sinusoidal displacements using continuous waves with a network analyzer

This study proposes a method for precise measurement of time waveforms of minute sinusoidal displacements using continuous waves. The technique involves measuring the S-parameter of ultrasonic waves reflected from an object undergoing sinusoidal vibration with a network analyzer. When the sinusoidal displacement is not sufficiently small, second-order side peaks emerge in its inverse Fourier transform, alongside the main and first-order side peaks. This method, which incorporates second-order side peaks previously overlooked, enhances the accuracy of measurements. It facilitates precise measurement of sinusoidal displacements ranging from 0.3 to 50 μm at frequencies between 10 and 300 Hz.

Narrow bandpass filter with ultra-wide stopband in a hybrid metal-optical Tamm state structure

Narrow bandpass filters (NBPF) play an important role in quantum communications, optical biometrics and other fields. However, traditional narrow bandpass filters have limited stopband capabilities. Here, an ultrawide stopband narrow bandpass filter is realized by combining a metal layer with a distributed Bragg reflector (DBR) structure to simultaneously excite the upper and lower Tamm plasma polarization (TP) modes. Numerical simulations show that the transmittance of the filter exceeds 94 % at a wavelength of 1.55 μm with a full width at half maximum (FWHM) of 8 nm. In addition, the addition of metal layer Ge reduces the electric field intensity of the lower DBR structure, effectively reducing the side peak, making the filter stopband range reach 1 μm–20 μm, which is 32 times that of traditional NBPF. Our research results provide a method to obtain narrow-band optical signals from ultra-broad and strong background noise, which facilitates the field of quantum communication.

Numerical Investigation of Wind Flow and Speedup Effect at a Towering Peak Extending out of a Steep Mountainside: Implications for Landscape Platforms

Wind flow over complex terrain is strongly influenced by the topographical features of the region, resulting in unpredictable local wind characteristics. This paper employs numerical simulation to study the wind flow at a towering peak extending out of a steep mountainside and the wind-induced effect on onsite landscape platforms. First, the wind flow from seven different directions is explored via 3D numerical simulations, and the wind load distribution on the platforms is highlighted. Second, a 2D numerical simulation is conducted to evaluate the wind speedup effect at the side peak, examining the influence of the side peak height and the mountainside steepness on the wind speedup factor. The numerical simulations presented in this research were validated by replicating a published numerical and experimental study. The results illustrate the amplifying and blocking effects of the surrounding topography, yielding unpredictable and nonuniform wind pressure distribution on the platforms. The presence of the side peak leads to a significant increase in the speedup factor, and the side peak height and the mountainside steepness have a moderate influence on the value of the speedup factor. Additionally, the speedup factor obtained from this study varies significantly, especially near the surface, from the recommendations of several wind load standards. Consequently, the impact of the local terrain and the wind speedup effect must be thoroughly assessed to ensure the structural integrity of structures installed at a similar topography.

Strong plasmon-mechanical coupling through standing acoustic waves and antenna enhancement, toward mass transduction

Plasmon-mechanical resonators are frequently employed in sensor development. Here, I report the coupling of plasmon and mechanical modes in a multilayer architecture. In the experiment, the multilayer comprised indium tin oxide (ITO) and silver (Ag) mirrors placed on the top and bottom of a SiO2 substrate. By activating a Fabry–Pérot hybrid mode and surface plasmon polariton in a Kretschmann configuration, I demonstrated the generation of a hybrid plasmon-mechanical mode by plasmonic dispersion and through strong coupling, which resulted in mechanical distortion at multiple frequencies. Adsorption of rhodamine G6 on Ag modifies the optomechanical spectrum; it causes eigenmodes to split, resulting in a coupling rate greater than the optical decay rate (κ∗<g). Besides, the excitonic modes were observed to interact with plasmon-mechanical modes, especially on-resonance, where the plasmon-mechanical modes exhibited the higher intensity. For example, the out-of-phase flexural mode (iii, g0=427×2πkHz) became active because of the coupling of the dye. Meanwhile, after dye absorption, the strong in-phase compressional mode (iv, g0=560×2πkHz) exhibited the widest splitting and an increase in the side peaks, which merged when the pump power was raised. The system was then analyzed to determine the ideal experimental settings for detecting mass by the oscillator in a controlled experiment. The mass sensor responsivity was evaluated to be F=1017Hzg−1. Advantages and disadvantages of this approach are presented.

Experimental investigation on the h-shaped pulse with leading edge in a Raman fiber laser

We report the experimental investigation on the h-shaped pulse with leading edge in a Raman fiber laser. Based on the nonlinear polarization rotation (NPR) technology, we successfully obtain the h-shaped pulse with leading edge in the all-fiber Raman fiber laser. After that, we experimentally study different affecting factors of pump power and polarization state on the leading edge, even the origin of it. Through adjusting the polarization state or increasing pump power, the leading edge can be extended up to 3907.71 ns or 3554.5 ns respectively without pulse collapse, showing an amazing stability and ultra-wide tunability. Finally, the corresponding spectra show that a left side peak always exists and gets stronger along with the extension of leading edge. After employing a home-made Lyot filter, we confirm that the leading edge is derived from the left side peak. Our work will contribute to the understanding of the h-shaped pulse with leading edge in soliton dynamics and its specific application in the material processing.

Molecular Dynamics Simulation of Diffusion Behavior in Liquid Sn and Pb

This study aimed to clarify the effect of a unique structure with a “shoulder,” which represents a hump on the high wave vector side of the first peak of static structure factor, in liquid Sn (liq-Sn) on the self-diffusion behavior through molecular dynamics (MD) simulation. The MD simulations of liq-Sn at 573 K and liquid Pb (liq-Pb) at 773 K were performed for comparison. The former and latter were selected as element with and without shoulder structure and reliable self-diffusion coefficients in liquid have been measured in both elements. The calculated self-diffusion coefficients of liq-Sn and liq-Pb were reproduced as the same order of magnitude with the referred reliable data of diffusion coefficients, which were obtained by experiments on the ground. The microscopic diffusion behavior of liq-Sn is unlike that of the hard-sphere model because the atoms become sluggish in the range that corresponds to the shoulder appearing in the pair distribution function of liq-Sn as well as in the structure factor of liq-Sn based on the local atomic configurations and time-series analyses of individual atoms. Therefore, the velocity autocorrelation function (VACF) converges to zero more rapidly than that of liq-Pb, and it is reproduced by the hard-sphere model. However, the macroscopic diffusion behavior of liq-Sn expressed by the self-diffusion coefficient is the same as that of the hard-sphere model with the non-correlation of the VACF in the long time.

Unusual spectral features in square-net based nonsymmorphic Kondo lattice system, CeCuX2 (X = As/Sb)

We study the electronic structure of a nonsymmorphic Kondo lattice system, CeCuX2 (X = As/Sb), a promising class of correlated topological materials important for advanced technology. While both the materials show Kondo behavior in their transport properties, CeCuSb2 is antiferromagnetic and no magnetic order is observed in CeCuAs2. We studied high-quality single-crystalline samples employing hard x-ray photoemission spectroscopy. The sample cleaving exposes the square-net structured pnictogen layers. The CeCuSb2 valence band indicates a highly metallic phase. The spectral intensity at the Fermi level in CeCuAs2 is weak, revealing close to semi-metallic behavior of the system. The Ce 3d spectra exhibit multiple features; the intensity of the features changes with the change in surface sensitivity of the technique, suggesting significant differences in the surface and bulk electronic structure. The bulk spectra of the Kondo system do not exhibit the typical f0-feature often observed in such materials. Instead, a distinct feature is observed at the lower binding energy side of the well-screened peak; the signature of this feature is manifested in the spectra from high-quality single-crystalline samples. This is outstanding and calls for physics beyond existing theories of correlated systems.

Majorana tunneling in a one-dimensional wire with non-Hermitian double quantum dots

The combination of non-Hermitian physics and Majorana fermions can give rise to new effects in quantum transport systems. In this work, we investigate the interplay of PT-symmetric complex potentials, Majorana tunneling and interdot tunneling in a non-Hermitian double quantum dots system. It is found that in the weak-coupling regime the Majorana tunneling has pronounced effects on the transport properties of such a system, manifested as splitting of the single peak into three and a reduced 1/4 peak in the transmission function. In the presence of the PT-symmetric complex potentials and interdot tunneling, the 1/4 central peak is robust against them, while the two side peaks are tuned by them. The interdot tunneling only induces asymmetry, instead of moving the conductance peak, due to the robustness of the Majorana modes. There is an exceptional point induced by the union of Majorana tunneling and interdot tunneling. With increased PT-symmetric complex potentials, the two side peaks will move towards each other. When the exceptional point is passed through, these two side peaks will disappear. In the strong-coupling regime, the Majorana fermion induces a 1/4 conductance dip instead of the three-peak structure. PT-symmetric complex potentials induce two conductance dips pinned at the exceptional point. These effects should be accessible in experiments.

Spectral analysis of beam-combining-systems based on laser array with smile effect

The smile effect in semiconductor laser arrays can cause spectral deterioration in spectral beam combining (SBC) systems. We analyze this effect using position error and pointing deviation and propose a coupled-cavity resonance model based on the external-cavity optical feedback and the multibeam interference theory to study locked spectra. Our results indicate that the central emitter exhibits excellent spectral purity, and the edge emitters show side peaks and a decrease in peak intensity. With the increase in the position error and pointing deviation, the emitters experience an obvious spectral shift and an expansion of the spectral width. Pointing deviation has a greater impact on wavelength locking and array spectral width than position errors. Increasing the focal length and incident angle can reduce shifts and spectral width. Furthermore, adopting a grating with a large line density can also decrease its center wavelength shift and compress the spectral width of the combined beam.

Artifact side peaks in saturated absorption spectroscopy caused by inappropriate lock-in amplification

Saturated absorption spectroscopy is a powerful technique that provides valuable information about gas-phase atomic targets, including not only the precise positions of transitions but also the effects of velocity-changing collisions, which manifest as changes in the shape of the peaks. However, using a lock-in amplifier inappropriately can generate artifact side peaks, potentially leading to a misinterpretation of results. To investigate the emergence of these artifacts, we conducted numerical calculations based on the basic Lambert–Beer’s law. Our model reproduced the artifact side peaks and revealed that these artifacts become more significant as the transmittance of the probe laser decreases.

Structural and Chemical Properties of NiOx Thin Films: Oxygen Vacancy Formation in O2 Atmosphere.

NiOx films on Si(111) were put in contact with oxygen at elevated temperatures. During heating and cooling in oxygen atmosphere Near Ambient Pressure (NAP)-XPS and -XAS and work function (WF) measurements reveal the creation and replenishing of oxygen vacancies in dependence of temperature. Oxygen vacancies manifest themselves as a distinct O1s feature at 528.9 eV on the low binding energy side of the main NiO peak as well as by a distinct deviation of the Ni2p3/2 spectral features from the typical NiO spectra. DFT calculations reveal that the presence of oxygen vacancies leads to a charge redistribution and altered bond lengths of the atoms surrounding the vacancies causing the observed spectral changes. Furthermore, we observed that a broadening of the lowest energy peak in the O K-edge spectra can be attributed to oxygen vacancies. In the presence of oxygen vacancies, the WF is lowered by 0.1 eV.

Count the charging load forecast of the battery remaining life and ownership

In order to solve the accuracy of EV charging load prediction, the residual life reduction and the exact value of EV ownership caused by battery aging are taken into consideration. The charging load curve of the EV is simulated based on the Monte Carlo simulation method. Finally, based on the actual data of a certain region, the charging load of electric vehicles within a day is obtained. The case analysis shows that the proposed charging load prediction model of electric vehicles has high accuracy, which also shows that the large-scale grid connection of electric vehicles will bring new challenges to the power system. This method provides data support for the subsequent formulation of electric vehicle charging strategy and load side peak shifting and valley filling.

Photonic Millimeter Wave Generation and Stabilization in Optically Injected Discrete-Mode Semiconductor Lasers Subject to Photonic Filter Feedback

Photonic millimeter wave signal generation and stabilization based on nonlinear dynamics of optically injected discrete-mode semiconductor lasers with photonic filter feedback are experimentally and numerically studied. The photonic filter is constructed by jointing two ports of a 2×2 optical coupler to form a ring cavity recirculation and is modelled as an infinite impulse response filter. The results show that >30GHz photonic millimeter wave signals can be obtained after optical to electrical conversion of the period-one oscillation output of the optically injected discrete-mode semiconductor laser. More importantly, the linewidth, side peak suppression ratio, as well as the stability of the generated millimeter wave, can be optimized using the photonic filter feedback. A fair comparison of the photonic filter feedback scheme and the single/double optical feedback schemes in terms of optimization performance has been made. The corresponding results demonstrate that the photonic filter feedback scheme has obvious superiority in millimeter wave side peak suppression and stability. The effect of the coupling coefficient as well as the phase variables in the ring cavity has also been discussed in the simulation work and the results qualitatively agree with the experimental observations.