Two-step phase-shifting Fresnel incoherent correlation holography based on discrete wavelet transform

Fresnel incoherent correlation holography(FINCH)has the ability to generate three-dimensional images with a superresolution by using incoherent sources.However,there are unwanted direct current term and twin image in interferograms,so it is of great significance to find a method to eliminate them.Phase-shifting technology is a most widely used technique for this task,but its three-step phase-shifting is not suitable for the instantaneous measurement of dynamic objects,and the quality of reconstructed image with the traditional two-step phase-shifting is lower.In this paper,we present a method of enhancing the resolution through using a two-step phase-shifting technology based on the discrete wavelet transform.After two-step phase-shifting,the resulting hologram is a superposition of multiple forms.The frequency of the resulting hologram is decomposed into different levels through using discrete wavelet transform,then the image is reconstructed after retrieving the low frequency band.Various experiments have verified the effectiveness of this method.

Three-step self-calibrating generalized phase-shifting interferometry

An accurate and fast three-step self-calibrating generalized phase-shifting interferomertry(SGPSI) is proposed. In this approach, two new phase-shifting signals are constructed by the difference interferograms normalization and noise suppressing, then the unknown phase shift between the two difference phase-shifting signals is estimated quickly through searching the minimum coefficient of variation of the modulation amplitude, a limited number of pixels are selected to participate in the search process to further save time, and finally the phase is reconstructed through the searched phase shift. Through the reconstruction of phase map by the simulation and experiment, and the comparison with several mature algorithms, the good performance of the proposed algorithm is proved, and it eliminates the limitation of requiring more than three phase-shifting interferograms for high-precision SGPSI. We expect this method to be widely used in the future.

Research on the Intelligent Control Strategy of the Fuel Cell Phase-Shifting Full-Bridge Power Electronics DC-DC Converter

focus of all countries.As an effective new energy,the fuel cell has attracted the attention of scholars.However,due to the particularity of proton exchange membrane fuel cell(PEMFC),the performance of traditional PI controlled phase-shifted full-bridge power electronics DC-DC converter cannot meet the needs of practical application.In order to further improve the dynamic performance of the converter,this paper first introduces several main topologies of the current mainstream front-end DC-DC converter,and analyzes their performance in the fuel cell system.Then,the operation process of the phase-shifted fullbridge power electronics DC-DC converter is introduced,and the shortcomings of the traditional PI control are analyzed.Finally,a double closed-loop adaptive fuzzy PI controller is proposed,which is characterized by dynamically adjusting PI parameters according to different working states to complete the intelligent control of phase-shifted full-bridge DC-DC converter.The simulation results in MATLAB/Simulink show that the proposed algorithm has good a control effect.Compared with the traditional algorithm,the overshoot and stabilization time of the system are shorter.The algorithm can effectively suppress the fluctuation of the output current of the fuel cell converter,and is a very practical control method.

Clinical Observation of Self-made Four-step Tendon Regulating Manipulation in the Treatment of 30 Cases of Thumb Stenotic Tenosynovitis

[Objectives] To observe the effectiveness of four-step tendon manipulation in the treatment of thumb stenotic tenosynovitis, under the guidance of "tendon first" theory. [Methods] 30 patients with stenotic tenosynovitis of thumb were treated with four-step tendon manipulation and traditional manipulation respectively, 3 times a week, a total of two weeks. The clinical efficacy, changes of visual analogue scale (VAS) and the recurrence rate after 15 d of follow-up treatment were observed before and after treatment. The differences were statistically significant ( P <0.05). [Results] After treatment, the VAS and the recurrence rate after 15 d of treatment in the observation group were significantly lower than those in the control group ( P <0.05). After treatment, the total effective rate was 73.33% in the control group and 93.33% in the observation group ( P <0.05). [Conclusions] The effect of four-step tendon regulating manipulation in the treatment of thumb stenotic tenosynovitis is ideal. The effect is significantly better than that of traditional Chinese medicine in improving thumb pain and function, which is worthy of clinical promotion.

High-order harmonic generation of ZnO crystals in chirped and static electric fields

High harmonic generation in ZnO crystals under chirped single-color field and static electric field are investigated by solving the semiconductor Bloch equation(SBE). It is found that when the chirp pulse is introduced, the interference structure becomes obvious while the harmonic cutoff is not extended. Furthermore, the harmonic efficiency is improved when the static electric field is included. These phenomena are demonstrated by the classical recollision model in real space affected by the waveform of laser field and inversion symmetry. Specifically, the electron motion in k-space shows that the change of waveform and the destruction of the symmetry of the laser field lead to the incomplete X-structure of the crystal-momentum-resolved(k-resolved) inter-band harmonic spectrum. Furthermore, a pre-acceleration process in the solid four-step model is confirmed.

Research on Phase-Shifted Full-Bridge Circuit Based on Frequency and Phase-Shift Synthesis Modulation Strategy

The full-bridge converters usually use transformer leakage inductance and parallel resonant capacitors to achieve smooth current commutation and soft switching functions,which can easily cause problems such as energy leakage and significant duty cycle loss.This paper designs a novel full-bridge zero-current(FB-ZCS)converter with series resonant capacitors and proposes a frequency and phase-shift synthesis modulation(FPSSM)control strategy based on this topology.Compared with the traditional parallel resonant capacitor circuit,the passive components used are significantly reduced,the structure is simple,and there is only a slight energy loss.By controlling the charging time of the capacitor,it can be achieved without additional switches or auxiliary circuits.The automatic control of capacitor energy based on input current addresses the low efficiency of the traditional control strategies.This paper introduces its principle in detail and verifies it through simulation.Finally,an experimental prototype was built further to demonstrate the feasibility of the theory through experiments.The module can be applied to a photovoltaic DC collection system using input parallel output series(IPOS)cascade to provide a new topology for large-scale,long-distance DC transmission.

Information Encryption Based on Using Arbitrary Two-Step Phase-Shift Interferometry

A deterministic phase-encoded encryption system is proposed. A lenticular lens array (LLA) sheet with a particular LPI (lenticular per inch) number is chosen as a modulator (key) instead of the random phase molator. The suggested encryption scheme is based on arbitrary two-step phase-shift interferometry (PSI), using an unknown phase step. The encryption and decryption principle is based on an LLA in arbitrary unknown two-step PSI. Right key holograms can be used to theoretically show that the object wavefront is the only one left in the hologram plane and that all accompanying undesired terms are eliminated. The encrypted image can therefore be numerically and successfully decrypted with the right key in the image plane. The number of degrees of freedom of the encryption scheme increases with the distance from the object and the LLA to the CCD, and also with the unknown phase-step and the LLA LPI number. Computer simulations are performed to verify the encryption and decryption principles without a key, with the wrong key and with the right key. Optical experiments are also performed to validate them.

Innovative Development Path of the Pension Model Under the Background of the Aging Society: Taking Chongqing as an Example

The aging society has dawned on China,and the pension industry is now considered to be a sunrise industry.In 2020,the number of people over the age of 65 in Chongqing had reached more than 5.47 million.At present,the mainstream home-based care,children support,and institutional care cannot fully meet the needs of the elderly for food,housing,medical care,nursing,and entertainment.The value curve model from“Blue Ocean Strategy”is used to look for innovative,differentiated competitive strategies.Through community-sharing pension institutions,it is believed that a new model that provides lower prices and more professional medical care services for the elderly,enriches the spiritual world of the elderly with rich entertainment activities,and connects social services through an elderly studio to meet the needs of the elderly for self-realization can be introduced.

一种具有宽输入电压范围的集成Buck-Boost LLC级联变换器

研究一种集成Buck-Boost LLC（integrated Buck-Boost LLC,IBBLLC）变换器。该变换器适用于宽输入电压范围场合的应用,通过开关管的共用变换器减少了开关管数量。通过采用PWM＋Phase-Shift控制,使得原边各个开关管在全输入电压和全负载范围内均能够实现零电压开通（zero voltage switching,ZVS）。文中首先介绍变换器的拓扑结构及直流增益。其次详细分析变换器的工作模式及前级电感Lb对变换器性能的影响,为变换器参数的选取提供了理论依据。此外,研究变换器的ZVS特性,给出变换器能够实现ZVS的工作区域。最后搭建一台200～450 V输入、14 V/80 A输出的实验样机,实验结果验证了理论分析的正确性及方案的可行性。

基于啁啾相移光纤光栅的多波长滤波器的研究

使用Ⅴ-Ⅰ传输矩阵法分析了相移量、相移点位置以及啁啾系数对啁啾相移光纤光栅透射谱特性的影响,并分析了在啁啾光纤光栅中同时引入多相移时生成的多陷波滤波器的波长间隔,发现其与以同样的位置引入单相移时陷波滤波器的波长偏离间隔基本一致。依据仿真分析结果,可以优化啁啾相移光栅相移数量、位置间隔、啁啾系数和相移量的参数选择,设计出实际需要的多波长滤波器。

A novel random phase-shifting digital holographic microscopy method

This paper proposes a new method that reconstructs the information of specimen by using random phase shift step in digital holographic microscopy (DHM). The principles of the method are described and discussed in detail. In practical experiment, because the phase shifter is neither perfectly linear nor calibrated, digital holograms with inaccurate phase shift step are recorded by the charge-coupled device (CCD). The phase could be accurately reconstructed from the recorded digital holograms by using the random phase-shifting algorithm, which makes up for reconstructed phase error caused by ordinary phase-shifting algorithm. The phase aberration compensation is also discussed. In order to verify the flexibility of the proposed method, numerical simulation of random phase-shifting DHM was carried out. The simulation results illustrated that the presented method is effective when the phase shift step is unknown or random in DHM.

Numerical study of hydrodynamic mechanism of dynamic tidal power

Dynamic tidal power is a new way of capturing tidal energy by building a water head using a dike perpendicular to the coast. This study explored the hydrodynamic mechanism of the water head across an intended dynamic tidal power dike system using the Delft3 D-FLOW software module. The propagating wave was simulated in a rectangular domain with a horizontal sea bottom at a 30-m depth. A significant water head was created across the dike by blocking the water. The water head increased with increasing dike length and increasing undisturbed tidal current acceleration. The maximum water head for the dike with a length of 50 km, located 900 km from the western boundary, was 2.15 m,which exceeded the undisturbed tidal range. The time series of the water head behaved in a manner identical to the undisturbed tidal current acceleration. The distribution of the water head over the dike assumed an elliptical shape. A parasitic wave was generated at the attachment and scattered outward. The phase lag across the dike did not behave as a linear function of the detour distance.

3D surface reconstruction based on binocular vision using structured light

A 3D surface reconstruction method using a binocular stereo vision technology and a coded structured light,which combines a gray code with phase-shift has been studied.The accuracy of the 3 D surface reconstruction mainly depends on the decoding of gray code views and phase-shift views.In order to find the boundary accurately,gray code patterns and their inverses are projected onto a human eye plaster model.The period dislocation between the gray code views and the phase-shift views in the course of decoding has been analyzed and a new method has been proposed to solve it.The splicing method is based on feature points.The result of the 3D surface reconstruction shows the accuracy and reliability of our method.

Migration of Magnetotelluric Data in Two——Dimensional Model

Since the wave equation of magnetotelluric(MT)field is similar to the one of seis-mic,the migration techniques used in seismic can be applied to MT data.In thispaper we make use of the principle of reflector mapping(i.e.U/D imaging principle)to image MT data.That is,the MT wavefield observed on the surface of the earth canbe resolved into upgoing and downgoing waves,the waves are extrapolated downward bythe phase-shift method or the phase-shift plus interpolation(PSPI)method.Conductivi-ty interfaces of the medium could be found by using the time coincidence of the upgoingand downgoing waves.Theoretical calculations show that the migration technique of MTdata presented here is very effective.It can not only enhance the lateral resolution of MTdata,but also obtain the visual image of subsurface interfaces.As compared with theconventional 2-D inversion,this procedure is more simple in calculation and can be easi-ly put into practice on a personal computer and is able to obtain the MT depth section,which

Phase-shifting technique applied to circular harmonic-based joint transform correlator

The phase-shifting technique is applied to the circular harmonic expansion-based jointtransform correlator. Computer simulation has shown that the light efficiency and the discrimination capability are greatly enhanced, and the full rotation invariance is preserved after the phase-shifting technique has been used. A rotation-invariant optical pattern recognition with high discrimination capability and high light efficiency is obtained. The influence of the additive noise on the performance of the correlator is also investigated. However, the anti-noise capability of this kind of correlator still needs improving.

A Universal Hybrid Precoding Scheme for Massive MIMO Communications

Based on an analog radio frequency(RF)network,hybrid precoding(HPC)for massive MIMO can achieve very high spectral efficiencies with moderate hardware cost and power consumption.Despite the extensive research efforts in recent years,the practioners are still looking for HPCs that are efficient and easy-to-implement.In this paper,we present a new method termed as the universal hybrid precoding(UHP),which is nearly optimal,computationally efficient,and applicable to various types of RF network(thus,the name universal):the components of the network can be phase shifters(with finite or infinite resolutions),switches,or their combinations;the topology of the network can be fully-connected or partiallyconnected.Besides the standard UHP,we also propose a simplified version termed as sUHP to trade a negligible performance loss for much reduced computational complexity.The analysis shows that the computational complexity of the proposed UHP/sUHP is one to two orders of magnitude lower than the state-of-theart methods.Simulation results verify the(near-)optimality of the proposed UHP scheme for various forms of the analog networks.

The holographic reconstructing algorithm and its error analysis about phase-shifting phase measurement

Phase-shifting measurement and its error estimation method were studied according to the holographic principle.A function of synchronous superposition of object complex amplitude reconstructed from N-step phase-shifting through one integral period(N-step phase-shifting function for short)was proposed.In N-step phase-shifting measurement,the interferograms are seen as a series of in-line holo-grams and the reference beam is an ideal parallel-plane wave.So the N-step phase-shifting function can be obtained by multiplying the interferogram by the original reference wave.In ideal conditions,the proposed method is a kind of synchro-nous superposition algorithm in which the complex ampli-tude is separated,measured and superposed.When error exists in measurement,the result of the N-step phase-shifting function is the optimal expected value of the least-squares fitting method.In the above method,the N+1-step phase-shifting function can be obtained from the N-step phase-shifting function.It shows that the N-step phase-shifting function can be separated into two parts:the ideal N-step phase-shifting function and its errors.The phase-shifting errors in N-steps phase-shifting phase measurement can be treated the same as the relative errors of amplitude and intensity under the understanding of the N+1-step phase-shifting function.The difficulties of the error estimation in phase-shifting phase measurement were restricted by this error esti-mation method.Meanwhile,the maximum error estimation method of phase-shifting phase measurement and its formula were proposed.

Four-quadrant demodulation fiber sensor for wavelength monitoring of a wavelength phase-shifting interferometer

Real-time monitoring of wavelength is important for high-speed wavelength phase-shifting interferometry.In this paper,a wavelength sensor based on a polarization-maintaining fiber interferometer with four-quadrant demodulation was proposed.We built the wavelength sensing system with resolution better than 0.005 pm and 0.1 ms sampling interval and measured the response time of the tuned wavelength at 35 ms in the phase-shifting process of a commercial wavelength phase-shifting free-space interferometer,as well as the wavelength drift velocity of 0.01 pm per second in the hysteresis process.The optical fiber wavelength sensor with four-quadrant demodulation provides a real-time wavelength sensing scheme for high-speed wavelength phase-shifting interferometers.

二维超外差条纹处理技术

本文从超外差式调频接受机的原理出发,提出一个适合于各种灵敏度测量的二维超外差条纹处理方法.与超外差式调频接受机的优点对应,该条纹处理方法有兼顾各种灵敏度,具有统一的中频处理与鉴相模块等优点.与其它采用条纹骨架的处理方法相比较,该方法实际上是直接的位相检测,其鉴相部分运用普通的phase-shift原理,因而具有测量精高度、灵敏度高的优点.此外,该方法也便于用硬件实现.

Comparative Analysis of Hybrid Controllers of Done Systems (UPFC) and Interphase Power Regulators Type RPI 30p15 on Contingency Management in Electrical Networks

The aim of this work is to demonstrate that interphase power regulators (IPR) bring new and interesting ultra-solutions that complement those already taken into account by the FACTS (Flexible Alternative Transmission System) in the resolution of the problems related to the power flow in the AC transmission networks. In order to facilitate the understanding of this work, a comparative study of the performances of the two technologies between the UPFC (Unified Power Flow Controller) and RPI was carried out and at the end of which we were able to highlight the preponderance of RPI compared to the UPFC in the bypassing of the short-circuit fault insofar as the latter allows, in particular, an increase in the transformation capacity without an increase in the level of the short-circuit. The decoupled watt-var method has been used to control the UPFC while the RPI is controlled by phase shift. The simulation results are obtained in the Matlab Simulink environment and show the flexibility of the RPI compared to the UPFC in limiting strong contingencies.