A novel variable polarity welding power based on high-frequency pulse modulation

A new type of variable polarity welding power modulated with high-frequency pulse current is developed. Series of high-frequency pulse current is superimposed on direct-current-electrode-negative （DCEN）, which can improve the crystallization process in the weld bead as a result of the electromagnetic force generated by pulse current. Digital signal processor （DSP） is used to realize the closed-loop control of the first inverter, variable polarity output of the second inverter and high-frequency pulse current superposition.

Thermal Performance of a 4 K High-Frequency Pulse Tube Cryocooler with Different Working Fluids

The high-frequency pulse tube cryocooler(HPTC)represents a promising miniature cryocooling technology due to its compact structure and the absence of low-temperature moving components.However,limited to the non-ideal gas effect of4He,the HPTC is hard to obtain high cooling performance in the liquid helium temperature range.3He as the working fluid can effectively improve the cooling performance of the HPTC,but the high cost hinders its wide application.In consideration of both cooling performance and cost-effectiveness,this paper explores the feasibility of utilizing^(3)He-^(4)He mixtures as the working fluid for HPTCs.Firstly,the experimental results of a developed HPTC based4He are reported.With a total power consumption of 575 W,the lowest temperature of 3.26 K was observed.And the measured cooling power at 4.2 K was 20.8 mW.Then the theoretical utmost efficiency of the cryocooler was calculated in terms of the thermophysical properties of the working fluids,using ^(3)He-^(4)He mixtures with different compositions as the working fluids.The whole machine modeling of the HPTC was further carried out,and the influence of the working fluids with different components on the structural parameters such as double-inlet and inertance tube,and operating parameters such as pressure and frequency were analyzed.The calculated results show that the cooling power is expected to be increased to36 mW and 53 mW if the equimolar ^(3)He-^(4)He mixture and pure ^(3)He are used,respectively.

A Kinetic Study on Dismutation of Superoxide Ion by Macrocyclic Dioxotetramine-Copper(Ⅱ) Complex by Using Pulse Radiolysis

We studied the reaction kinetics of dismutation for superoxide ion by copper (Ⅱ) complex of macrocycllc dioxotetramine ligand 12- ( 4' - nitro )- benzyl-1,4,7,10- tetraazacy-clotridecane-11,13-dionato copper (Ⅱ) by using pulse radiolysis. The rate constants of dismutation kcat's were measured to be 1. 78×106 mor-1 . L.s-1(at pH 7. 0) and 1. 06×106 mol-1. L. s-1(at pH 7. 8). The reaction mechanism is similar to that catalyzed by super-oxide dismutase.

THE DISMUTATION OF SUPEROXIDE ANION BY COPPER(Ⅱ)COMPLEX OF 1,4,7,10-TETRAAZACYCLOTRIDECANE-11,13-DIONE—A KINETIC STUDY BY MEANS OF PULSE RADIOLYSIS

The dismutation kinetics of superoxide anion by copper complex of 1,4,7,10-tetranza- cyctotridecane-11,13-dione was studied by pulse radiolysis.The dismutation rate constants at various pH and concentration of complex were obtained.

Ultrashort optical pulse shaper based on complex-modulated long-period-grating coupler

In this paper,we present a novel ultrashort pulse shaper based on complex-modulated long-period-grating coupler（CM-LPGC）.Temporal rectangular waveform with 2-ps full width at half maximum（FWHM） is obtained by transforming the input Gaussian pulse.Tolerances of the CM-LPGC-based shaper to various non-ideal excitation conditions and fabricating errors are investigated.Results confirm that CM-LPGC is stable and suitable for optical pulse shaping operation.

Investigation on the automatic parameters extraction of pulse signals based on wavelet transform

This paper analyses a key problem in the quantification of pulse diagnosis. Due to the subjectivity and fuzziness of pulse diagnosis,quantitative methods are needed. To extract the parameters of pulse signals,the prerequisite is to detect the corners of pulse signals correctly. Up to now,the pulse parameters are mostly acquired by marking the pulse corners manually,which is an obstacle to modernize pulse diagnosis. Therefore,a new automatic parameters extraction approach for pulse signals using wavelet transform is presented. The results testified that the method we proposed is feasible and effective and can detect corners of pulse signals accurately,which can be expected to facilitate the modernization of pulse diagnosis.

Influence of high frequency pulse on electrode wear in micro-EDM

An electromagnetic coupling mathematical model is established by finite element method and is verified by the contrastive experiments of copper matrix Ni-TiN cylindrical coating electrode,copper electrode and Cu50 W electrode.The wear mechanism of Ni-TiN/Cu composite electrode in the case of high-frequency pulse current is studied,and the influence of the fluctuation frequency of discharge current on electrode wear in micro-EDM is found out.Compared with the electrode made from homogeneous material,the high frequency electromagnetic properties of Ni-TiN composite layer can be used effectively to inhibit the effect of high frequency pulse on the electrode and improve the distribution trend of current density.

Simulation method of near-fault pulse-type ground motion

The two characteristics of near-fault ground motions, i.e., the forward directivity effect and permanent displacement effect, result in long period and large velocity pulse in the velocity time history and large step pulse in the displacement time history. Considering the two effects, a simple expression of continuous function for equivalent velocity pulse time history is presented in this paper. The equivalent pulse model, in which the pulse period, peak velocity and pulse shape are described by five parameters, is highly advantageous to fit and simulate the pulse-type velocity time history. The equivalent pulse model comprises only one low-frequency component while the high-frequency component of a pulse-type earthquake record cannot be considered. Based on 28 records of 11 earthquakes, the pulse frequency of pulse-type records is generally less than 1 Hz. Therefore the low-frequency component and high-frequency component are simulated respectively and combined them together to generate a pulse-type ground motion.

Dynamics of high-frequency modulated waves in a nonlinear dissipative continuous bi-inductance network

This paper presents intensive investigation of dynamics of high frequency nonlinear modulated excitations in a damped bimodal lattice. The effects of the dissipation are considered through a linear dissipation coefficient whose evolution in terms of the carrier wave frequency is checked. There appears that the dissipation coefficient increases with the carrier wave frequency. In the linear limit and for high frequency waves, study of the asymptotic behavior of plane waves reveals the existence of two additional regions in the dispersion curve where the modulational phenomenon is observed compared to the lossless line. Based on the multiple scales method exploited in the continuum approximation using an appropriate decoupling ansatz for the voltage of the two different cells, it appears that the motion of modulated waves is described by a dissipative complex Ginzburg–Landau equation instead of a Korteweg–de Vries equation. We also show that this amplitude wave equation admits envelope and hole solitons in the high frequency mode. From basic sources, we design a programmable electronic generator of complex signals with desired characteristics, which delivers signals exploited as input waves for all our numerical simulations. These simulations are performed in the LTspice software that uses realistic components and give the results that corroborate perfectly our analytical predictions.

Some nonlinear parameters of PP intervals of pulse main peaks

The PP intervals of pulse main peaks from healthy and unhealthy people(arrhythmia) have different nonlinear char-acteristics. In this paper,the extraction of PP intervals of pulse main peaks is achieved by picking up P peaks of pulse wave with wavelet transform. Furthermore,several nonlinear parameters(correlative dimensions,maximum Lyapunov exponents,com-plexity and approximate entropy) of the PP intervals of pulse main peaks extracted from normal and unhealthy pulse signals are calculated,with the results showing that these nonlinear parameters calculated from the main wave interval signals are helpful for analyzing human's health state and diagnosing heart diseases.

Fast repetition rate fs pulsed lasers for advanced PLIM microscopy

Simultaneous metabolic and oxygen imaging is promising to follow up therapy response,dis-ease development and to determine prognostic factors.FLIM of metabolic coenzymes is now widely accepted to be the most reliable method to determine cellular bioenergetics.Also,oxygen consumption has to be taken into account to understand treatment responses.The phosphorescence lifetimne of oxygen sensors is able to indicate local oxygen changes.For phosphorescence lifetime imaging(PLIM)dyes based on ruthenium(I)coordination com-plexes are useful,in detaill TLD1433 which possesses a variety of different triplet states,enables complex photochemistry and redox reactions.PLIM is usally reached by two photon exci-tation of the drug with a femtosecond(fs)pulsed Ti:Sapphire laser working at 80 MHz repe-tition rate and(time-correlated single photon counting)(TCSPC)detection electronics.The interesting question was whether it is possible to follow up PLIM 1using faster repetition rates.Faster repetition rates could be advantageous for the induction of specific photochemical reactions because of similar light doses used normally in standard CW light treatments.For this,a default 2p-FLIM-PLIM system was expanded by adding a second fs pulsed laser("helixx")which provides 50 fs pulses at a repetition rate of 250 MHz,more than 2.3 w average power and tunable from 720 nm to 920 nm.The laser beam was coupled into the AOM instead of the default 80 MHz laser.We demonstrated siuccessful applications of the 250 MHz laser for PLIM which correlates well with measurements done by excitation with the conventional 80MHx laser source.

太赫兹波段介质电磁参数测量与提取对比研究

本文完善了基于太赫兹时域光谱系统和基于矢量网络分析系统材料参数测量的一般理论,在2类系统的交叉频段,建立了相同准光学参数的测量条件,对比分析了2类系统信号参数测量和理论提取的过程。实验验证了在光子学和电子学的重叠区域,不同测量系统在相同测量条件下,能够获取趋于一致的测量结果,证实了结果的准确性只取决于物理模型、理论方法和测量条件是否匹配。提炼出采用单次时域法同时适用于时域系统和频域系统参数测量和提取的适配条件,并形成匹配条件经验理论公式,用于判断材料太赫兹参数测量结果的可靠性。

Spatio-Temporal Pulsating Dissipative Solitons through Collective Variable Methods

A semi-analytical approach for the pulsating solutions of the 3D complex Cubic-quintic Ginzburg-Landau Equation (CGLE) is presented in this article. A collective variable approach is used to obtain a system of variational equations which give the evolution of the light pulses parameters as a function of the propagation distance. The collective coordinate approach is incomparably faster than the direct numerical simulation of the propagation equation. This allows us to obtain, efficiently, a global mapping of the 3D pulsating soliton. In addition it allows describing the influence of the parameters of the equation on the various physical parameters of the pulse and their dynamics.

Electrochemical Study of Cadmium (Ⅱ) Complexation with Cysteine

The complexation of Cd with cysteine has been investigated at pH ~9, and in constant ionic medium 0.59 M NaNO3 and borate buffer. Reduction signals of the hydrated Cd2+ and Cd-cysteinate complex were resolved on the potential scale during amperometric titration of 2 × 10-6 M Cd2+ with cysteine and cysteine with Cd2+, in a differential pulse (DP) mode on HMDE. The 1:1 molar ratio of Cd2+ to cysteine, and cysteine to Cd2+, was defined for Cd-cysteinate complex formed under the defined conditions. The appearance of the prepeak on the Cd-cysteinate reduction signal is showed, as the result of cysteine adsorption in reduced form. From the mass balance equations, the stoichiometric stability constants of Cd-cysteinate complex were calculated. Under various experimental conditions, comparable log K values were obtained. The grand average log K = 7.83 M-1 refers to 0.59 M ionic strength and 23℃.

高密度脉冲流复杂调制信号测量接收机计量方法研究

为了解决高密度脉冲流复杂调制信号测量接收机的计量难题,借鉴数字与矢量信号计量校准思路,研究提出一种基于通用测试仪器的模拟器提供激励信号、模拟高密度脉冲流下的复杂调制信号、采用矢量信号分析仪和高密度脉冲流复杂调制信号测量接收机比测验证的计量方法,并搭建基于通用测试仪器计量装置,选取基于基本波形片断的高密度脉冲流下复杂调制信号的典型计量状态,进行实验验证。实验结果表明,装置的脉冲、调频、调相、捷变频等计量性能满足实际需求,该方法可行。

一种基于关联脉冲对的动态直方图分选算法

针对现有分选算法在复杂电磁环境下准确性与效率降低的问题,提出了一种基于关联脉冲对的动态直方图分选方法。该方法首先对到达时间差进行固定箱长统计,将高于检测门限的相邻箱进行合并,得到动态直方图统计结果,估计出潜在PRI(pulse repetition interval)。对潜在PRI对应的关联脉冲对进行分析,剔除虚假PRI并估计出真实PRI的抖动量。最后,再依据PRI参数完成脉冲序列搜索,实现对雷达信号的分选。仿真实验表明,该方法在较低的到达时间差级数条件下,对多部复杂PRI调制信号的分选准确率达到95%,能够对复杂电磁环境下的雷达信号进行有效分选。

基于复杂网络和CSLPA的多功能雷达信号分选

复杂网络理论在多功能雷达信号分选中已成功得到应用。针对标签传播拓展算法(SLPA)在节点更新顺序和标签传播时采用随机策略导致的划分结果不稳定、随机性强等问题,提出基于接近中心性的节点排序方法和度量节点相似性的条件标签传播拓展算法(CSLPA)用于分选时的社区检测。首先,将雷达脉冲信号的细微特征与脉冲描述字(PDW)参数组成特征向量,根据滑动有限穿透可视图构建复杂网络模型;然后,采用CSLPA算法和密度峰值聚类算法进行社区检测,完成分选过程。仿真结果表明,所提方法在参数重叠较多及存在多功能雷达信号的复杂电磁环境中,分选性能优于标签传播算法及两种传统分选算法——k-means聚类与脉冲重复间隔变换法,在存在噪声、漏脉冲和虚假脉冲等条件下具有较强的鲁棒性。

复合酸辅助强脉冲光治疗玫瑰痤疮的疗效及安全性分析

目的:探讨复合酸辅助强脉冲光(Intense pulsed light,IPL)治疗玫瑰痤疮的疗效及安全性。方法:选取2019年1月-2021年1月医院收治的85例玫瑰痤疮患者,采用随机数字表法分为对照组(n=43)和研究组(n=42),对照组采用IPL治疗,研究组在对照组基础上联合复合酸治疗。比较两组治疗前后皮损改善情况、皮肤状态、皮肤屏障功能指标,观察并记录两组不良反应发生情况。结果:治疗6周后,两组皮损评分均低于治疗前,研究组皮损评分低于对照组(P<0.05);研究组治疗总有效率高于对照组(P<0.05);治疗后6、12周,两组经表皮水分流失量(TWEL)较治疗前逐渐降低,皮脂含量、角质层含水量均较治疗前逐渐增加(P<0.05);同时间段研究组TWEL均低于对照组,皮脂含量、角质层含水量均高于对照组(P<0.05);研究组瘙痒、刺痛、潮红及水肿发生率均低于对照组(P<0.05)。结论:复合酸辅助IPL能减少玫瑰痤疮患者面部炎性皮损,改善患者皮肤状态,提高皮肤屏障功能,临床疗效较好,安全性佳。

复杂波形核脉冲信号的梯形成形研究

提出一种对复杂波形核脉冲信号进行梯形成形的方法。该方法将复杂波形核脉冲信号看成传递函数的冲激响应,对传递函数因式分解成一阶惯性环节和的形式。采用粒子群算法对复杂波形核脉冲信号进行识别,得到一阶惯性环节的个数、各个环节的比例系数以及脉冲幅值相关系数、发生时间和时间常数等参数。通过所识别的参数进行其梯形成形的公式推导及仿真实验表明,该方法获取的脉冲幅值精度较高。

桑托斯盆地L区块早白垩世Aptian期火山喷发旋回特征与Itapema组介壳灰岩沉积

桑托斯盆地裂陷初期岩浆活动与储层发育关系密切。本文以盆地L区块火成岩-介壳灰岩复合体为研究对象,通过对火成岩岩石学、年代学测试及钻井、测井资料分析等,首次明确了桑托斯盆地裂陷初期岩浆活动特征及其对介壳灰岩沉积过程的控制,并指出介壳灰岩储层的分布特征。L区块内火成岩分属晚白垩世Santonian期—Campanian期和早白垩世Aptian两期岩浆活动产物,并以Aptian期为主,至少经历了7次不连续喷发和3次侵入过程,形成了块状玄武岩、杏仁状玄武岩和玻基斑状玄武岩(含再沉积玻基斑状玄武岩)等喷发相火成岩和以辉绿岩(局部属粗玄岩)、煌斑岩形式产出的侵入相火成岩。Aptian期岩浆多期活动重塑了古地貌,形成了局部构造凸起,促成并控制了下白垩统Itapema组至少6期介壳灰岩沉积,最终形成了~620 m厚火成岩-介壳灰岩复合体。介壳灰岩储层呈透镜体形状,以“散点式”不连续分布在Aptian期盆内古隆、古断阶(坡)等区域,横向连续性差,垂向连通性受限,其发育规模和质量受古地貌及水深条件等影响。