Effects of current waveform parameters during droplet transfer on spatter in high speed waveform controlled Short-circuiting GMAW

Aim at improving the stability of the Short-circuiting Gas Metal Arc Welding （GMAW-S） process for the enhanced speed usage, effects of current waveform parameters during short-term on the welding stability have been investigated by experimental method. The welding power source used for the research is an inverter with a special current waveform control. It is shown that the spatter decreases at first then increases with each increase of the low current period, current increase rate and the maximum current limit. The test results are provided for welding of 1 mm and 3 mm mild steel at speed of 1.2 m/min. The stable GMA W-S process under high speed welding condition has been achieved by optimizing the parameters.

Adaptive time-space resource and waveform control for collocated MIMO radar with simultaneous multi-beam

Collocated multiple input multiple output(MIMO)radar,which has agile multi-beam working mode,can offer enhanced multiple targets tracking(MTT)ability.In detail,it can illuminate different targets simultaneously with multi-beam or one wide beam among multi-beam,providing greater degree of freedom in system resource control.An adaptive time-space resource and waveform control optimization model for the collocated MIMO radar with simultaneous multi-beam is proposed in this paper.The aim of the proposed scheme is to improve the overall tracking accuracy and meanwhile minimize the resource consumption under the guarantee of effective targets detection.A resource and waveform control algorithm which integrates the genetic algorithm(GA)is proposed to solve the optimization problem.The optimal transmitting waveform parameters,system sampling period,sub-array number,binary radar tracking parameterχ_i(t_k),transmitting energy and multi-beam direction vector combination are chosen adaptively,where the first one realizes the waveform control and the latter five realize the timespace resource allocation.Simulation results demonstrate the effectiveness of the proposed control method.

Investigation on microprocessor based waveform control of short circuit transfer CO_2 welding

A new kind of simple and flexible CO2 welding system was developed to carry out waveform control. The system consisted of IGBT inverter, PWM circuit and microprocessor unit （ MPU） , in which the output current of constant current （CC） power supply could be changed according to transient physical state, and the variable down slope rate control could be used to ensure a stable welding process. The welding experiment results proved the effectiveness of this control approach.

Computer simulation of short-circuiting transfer welding under waveform control on inverter power source

A simulation model is introduced about the non-linearity process of short-circuiting transfer in CO2 arc welding for displaying the interaction between the inverter power source and welding arc under waveform control. In the simulation model, the feedback signals of current and voltage are taken respectively at the different phase in a short circuit periodic time and applied to the PWM （pulse width modulation） module in a model of inverter power source to control the output of power source. The simulation operation about the dynamic process of CO2 short-circuiting transfer welding is implemented on the founded simulation model with a peak arc current of 400 A and a peak voltage of 35 V, producing the dynamic arc waveforms which can embody the effect of inverter harmonic wave. The simulating waveforms are close to that of welding experiments.

Simulation of droplet transfer process and current waveform control of CO_2 arc welding

A simulation system used in the arc welding short circuit transfer process and current waveform control process was developed in this paper. The simulation results are basically consistent with welding technical experiments. The simulation system can be used to simulate and test the current waveform control parameters with welding variables. By this simulation system, the influence regularities of the current waveform control parameters in the CO 2 arc welding droplet short circuit transfer process can be got. Moreover, the basic mode of real time current waveform control can be also established by the simulation testing.

Effects of controlled pulse current waveform on key-holing condition in plasma arc welding

To overcome the shortcomings of conventional plasma arc welding （ PAW）, the ＇ controlled pulse key-holing＇ strategy is proposed and the keyhole PAW experiment system is developed. ＇The efflux plasma voltage signal is detected in realtime to characterize the keyhole size and dimension. The welding current waveform for controlled pulse key-holing strategy is implemented, and two slow-decreasing slopes are added at the dropping point from peak current to base current to further reduce both heat input and arc force so that the controllability of keyhole dynamics is improved. Two kinds of PAW tests are conducted, anti the different parameters of the controlled pulse current and the relevant efflux plasma voltage are measured in real-time to investigate ihe effects of welding current waveform parameters on the key-holing condition.

两种波形调控方法获得单次谐波光源的研究

本文利用啁啾波形调控和双色场波形调控对单次谐波光源的产生进行了研究.结果发现:在啁啾波形调控下,单次谐波光源的调节范围在170次到370次谐波区间,能量调节范围较宽.并且,单次谐波的产生对激光脉宽和光强的要求不高.在双色场波形调控下,单次谐波光源的调节范围仅在80次到110次谐波区间,能量调节范围较窄.并且,单次谐波的产生对激光脉宽和光强的要求较高.

Theoretical modeling of airways pressure waveform for dual-controlled ventilation with physiological pattern and linear respiratory mechanics

The present paper describes the theoretical treatment performed for the geometrical optimization of advanced and improved-shape waveforms as airways pressure excitation for controlled breathings in dual-controlled ventilation applied to anaesthetized or severe brain injured patients, the respiratory mechanics of which can be assumed linear. Advanced means insensitive to patient breathing activity as well as to ventilator settings while improved-shape intends in comparison to conventional square waveform for a progressive approaching towards physiological transpulmonary pressure and respiratory airflow waveforms. Such functional features along with the best ventilation control for the specific therapeutic requirements of each patient can be achieved through the implementation of both diagnostic and compensation procedures effectively carried out by the Advance Lung Ventilation System (ALVS) already successfully tested for square waveform as airways pressure excitation. Triangular and trapezoidal waveforms have been considered as airways pressure excitation. The results shows that the latter fits completely the requirements for a physiological pattern of endoalveolar pressure and respiratory airflow waveforms, while the former exhibits a lower physiological behaviour but it is anyhow periodically recommended for performing adequately the powerful diagnostic procedure.

电液振动台加速度时域波形自适应控制策略

针对电液振动台加速度时域波形复现精度低的问题,提出了一种基于内环前馈逆补偿和外环非线性滤波的在线自适应控制策略。首先,构建了电液振动台伺服驱动机构模型,采用三状态控制策略获得了初步加速度控制性能;其次,基于多新息遗忘梯度算法辨识了三状态控制下系统参数化模型,利用零幅值跟踪技术构建了内环前馈逆补偿策略,拓展了系统频宽,降低了相位滞后误差;然后,引入了外环非线性Volterra自适应滤波算法,抑制了电液振动台模型参数偏差、非线性动态特性和不确定性扰动的影响;最后,在搭建的水平单轴电液振动台上开展了时域波形复现对比实验。结果表明,提出的自适应控制策略与传统策略相比具有更优越的加速度时域波形复现精度。

局部干法水下快频脉冲MIG焊电源研制

针对复杂水下环境焊接过程对焊接电源超高动特性与精确控制需求,设计基于SiC模块的快频脉冲焊接电源功率主电路,开发全数字化控制系统,研制出局部干法水下快频脉冲MIG焊电源(local dry underwater fastfrequency pulsed MIG,LDU-FFPMIG).研制的LDU-FFPMIG焊接电源额定输出电流为400 A,能精确输出多种0~30 kHz的快频脉冲电流波形,快频脉冲电流幅值高达200 A.提出LDU-FFPMIG焊接新工艺,将快频脉冲应用到304不锈钢局部干法水下MIG焊接,探究快频脉冲对传统局部干法水下脉冲MIG焊的影响.结果表明,研制的LDU-FFPMIG焊接电源能够实现稳定的局部干法水下MIG焊,可获得良好的焊缝成形;快频脉冲电流的引入可显著提高电弧能量密度和焊接稳定性,减小熔宽(B)、增大熔深(H),焊缝成形系数(B/H)减小约30%,并且可以细化晶粒.

爆破振动强度、波形与频谱研究综述:预测及主动控制

岩石钻孔爆破不可避免地会产生爆破振动效应及危害,准确预测爆破振动效应并进行主动控制具有极大的现实意义。论文综述了近40年来,国内外研究人员在爆破振动预测及主动控制方面取得的研究成果。在爆破振动速度峰值(PPV)预测方面,经验模型预测方法体现出了较大的便捷性,但预测精度与效果较差,将概率统计理论引入经验模型预测方法,提高了PPV预测精度;而基波叠加预测方法可实现对振速、频率和持续时间的综合预测,但是该方法对振动基波的测试精度要求较高,同时亟须在行业内建立对爆破振动采集设备的定期标定与校核机制;人工智能预测方法极大提高了PPV预测精度,同时为多因素影响下的爆破振动效应预测提供了新思路,但需要建立在海量真实有效实测数据的基础上,目前还缺乏充实的振动测试样本数据库;PPV预测理论模型及数值模拟预测法对理论与专业知识、数值模拟技术等要求高,限制了两种方法在工程的普遍应用。在爆破振动速度主动控制上,可以确定合理的延期时间,采用毫秒延迟干扰减振法来降低PPV,但目前多为单一防护对象所提出的延期时间建议值;从调整爆破振动频谱结构的角度,通过主动改变延期时间调控爆破振动频率成分,可避开建(构)筑物自振频带,减小爆破振动危害,然而目前仅仅停留在理论层面或模型试验尺度条件下,缺乏大规模的现场应用实例。最后,对未来爆破振动预测及控制方面重点研究内容进行了展望。

连续振动载荷在线复现控制技术研究

提出一种主从分布式振动试验方法,建立了连续振动载荷在线复现控制技术,研制了系统样机。其中,提出一种信号分帧处理与重构技术,解决了长时连续振动载荷的在线波形复现难题;提出一种基于多量级样本库构建与加权平均的传递函数动态估计方法,抑制了系统非线性对控制精度的影响;采用谱误差反馈修正方法,改善了系统的频域控制精度。开展了“1主2从”联台试验,结果表明:时域和频域控制精度良好,整体延迟时间在亚秒量级,全程总均方根值误差在1%以内,为主从分布式振动试验提供了关键技术支撑。

基于波形相控反演的致密砂岩储层模拟预测方法——以黄骅坳陷沧东凹陷南部古近系孔二段为例

在岩石物理分析的基础上,利用波形相控反演与模拟相结合的方法,并结合拟声波阻抗重构技术及基于坐标旋转的储层参数指示构建技术,对黄骅坳陷沧东凹陷南部中高斜坡区古近系孔二段的致密砂岩储层进行预测。研究结果表明:(1)波阻抗曲线对于砂岩和泥岩的识别效果较差,而自然伽马能以83 API为界限值有效区分砂岩与泥岩,优选的自然电位曲线不仅能以-13 mV为界限值有效区分砂岩和泥岩,对于储层与非储层也具有一定的区分能力。(2)重构后的拟声波阻抗曲线提高了对砂岩和泥岩的识别能力,基于坐标旋转的储层指示曲线以-10为门槛值划分储层与非储层,且储层指示曲线可实现对致密砂岩储层的预测。(3)波形相控反演与模拟相结合的储层预测方法能够提高致密砂岩储层预测的精度,并可降低储层预测的多解性,储层预测符合率达83.3%。

分布式全固态波形可调高压脉冲发生器研制

为了满足多领域对幅值、脉宽、波形、重复频率等参数的不同要求,基于分布式理念,提出了一种分布式全固态波形可调高压脉冲发生器。该脉冲发生器由多个结构相同的子模块构成,单个模块采用半桥结构的全固态Marx主拓扑,驱动采用磁隔离方案;每个模块具有统一设计的连接端子与通信协议,多个模块可以独立工作,也可以直接串联工作以获得更好的性能。整个装置采用分层式设计,结构紧凑。详细阐述了该发生器的电路拓扑、工作原理与波形产生方法,并搭建了3台8级基本单元的9电平试验样机,串联后可输出25级电平的单极性任意高压脉冲波形,最大输出电压达到16 kV。

准噶尔盆地红车断裂带石炭系火山岩油藏地球物理特征及有利储层预测

准噶尔盆地西缘红车断裂带火山岩油气藏资源丰富,储量规模巨大,具有满带含油的特点。然而火山岩油藏受构造、相带、岩性控制,断裂复杂,岩性岩相变化快,非均质性强,致使优质储层难以识别。首先,基于岩石薄片、测井、地震等资料,分析了研究区石炭系发育的优势岩性以及不同岩性的测井响应特征,运用多参数分布交会法建立了自然伽马-密度、密度-电阻率/自然伽马、电阻率-自然伽马/密度的岩性识别组合图版,确定优势岩性特征,进而对目的层段的岩性进行了有效识别。然后,通过地震相、测井相、岩性特征及试油结果等资料的分析,明确研究区火山岩相、储盖组合和油藏分布规律。根据地震反射结构和反射构型特征,识别研究区典型的地震相特征;在岩石物理和敏感参数分析的基础上,发挥地震纹理属性和瞬时相位余弦属性在岩性体刻画、边界分析方面的优势,以及地震波形相控反演在提高储层识别垂向分辨率的同时,兼顾了横向预测的能力,综合运用地震多属性分析、波形相控反演和沿层切片技术,通过对地震平-剖面成果与井上有利储层的分析,最终确定优势储层的发育和空间分布范围,为落实准噶尔盆地红车断裂带火山岩储层油气优势聚集带提供了支持。

多导睡眠测量仪质量控制检测与性能评估

目的:研究多导睡眠测量仪质量控制检测方法,确保其使用中性能的安全性与有效性。方法:针对多导睡眠测量仪的脑电信号、肌电信号、心电信号和脉搏血氧饱和度主要指标参数,设计质量控制检测方法。选取2023年8月陆军军医大学大坪医院临床在用的2台同品牌不同型号的多导睡眠测量仪(标记为测试设备A和测试设备B),采用心脑电图机检定仪和生命体征模拟仪进行多导睡眠测量仪质量控制检测,评估多导睡眠测量仪性能的可靠性。结果:针对多导睡眠测量仪的脑电信号、肌电信号、心电信号和脉搏血氧饱和度示值重复性制定质量控制检测方法进行多导睡眠测量仪质量控制检测,记录数据除测试设备B电压测量模拟仪输出值2 mV时,相对误差为-11%,出现参数超差,测试设备A和测试设备B的其余检测数据均满足国家计量检定规程和设备生产厂家技术要求的最大极限输出值。结论:多导睡眠测量仪质量控制检测方法能够对选取的测试设备A和测试设备B多导睡眠测量仪进行性能参数评估,为该类设备质量控制检测和使用安全提供技术支持。

海洋可控源电磁法与地震全波形二维联合反演研究

为降低单一地球物理反演方法的局限性以及反演中所存在的多解性等问题,开展了海洋可控源电磁法(MCSEM)与地震全波形的二维联合反演研究。MCSEM采用数据空间OCCAM反演算法,地震全波形采用梯度法反演算法,引入交叉梯度函数实现两种物性参数结果的相互耦合;开发出一套二维联合反演算法,并通过3组理论模型算例验证了算法的准确性。研究结果表明:MCSEM联合反演结果相对于单方法反演结果有显著改善和提升,主要体现在异常体的形态刻画、结构构造以及物性数值的恢复,这说明全波形的反演方法能够提高MCSEM反演结果的可靠性。

混合域特征波全波形反演速度建模质控方法

常规的速度建模方法速度模型精度低,往往不能改善断层阴影带成像质量,通过采用混合域特征波全波形反演技术能加快全波形反演运算速度和收敛。同时提出成像剖面叠合分析、收敛性分析、测井速度与全波形反演速度对比分析、实际炮集与正演炮集波形对比分析、全波形反演模型与观测记录相似系数对比分析五步法全波形反演速度建模质控方法 ,并建立了目标泛函收敛是判断全波形反演是否收敛最直观的参数,目标函数不下降表明反演不收敛;全波形反演速度趋势与测井趋势要相吻合;正演炮集与实际炮集特征波对比越接近,目标泛函数值越小;正演炮集与实际炮集相似系数越大越一致,表明反演速度越精确等混合域特征波全波形反演速度建模质控主要标准。应用该质控方法,在较为准确的背景速度基础上应用构造约束混合域特征波全波形反演技术,引入较为准确的断层信息,建立精度更高的速度模型,提高了断层阴影带成像质量,有效改善了断层阴影带下盘构造成像畸变现象。

一种无功补偿控制器延时时间测试方法介绍

文中介绍了JB/T 9663-2013标准对控制器延时时间的测试要求与控制器工作原理。结合标准要求与控制器输出回路工作方式,介绍了一种可用于测量控制器延时时间测试方法。在此方法中,通过数据采集系统测量通道采集控制器输出回路V12与K1至K12中DC12电压信号和取样电流回路三相开关进线端相间AC47V电压波形出现或消失时刻。利用采集到的波形,测量控制器接通与分断延时时间。

Present Status and Prospect of High-Frequency Electro-hydraulic Vibration Control Technology

Electro-hydraulic vibration equipment(EHVE)is widely used in vibration environment simulation tests,such as vehicles,weapons,ships,aerospace,nuclear industries and seismic waves replication,etc.,due to its large output power,displacement and thrust,as well as good workload adaptation and multi-controllable parameters.Based on the domestic and overseas development of high-frequency EHVE,dividing them into servo-valve controlled vibration equipment and rotary-valve controlled vibration equipment.The research status and progress of high-frequency electro-hydraulic vibration control technology(EHVCT)are discussed,from the perspective of vibration waveform control and vibration controller.The problems of current electro-hydraulic vibration system bandwidth and waveform distortion control,stability control,offset control and complex vibration waveform generation in high-frequency vibration conditions are pointed out.Combining the existing rotary-valve controlled high-frequency electro-hydraulic vibration method,a new twin-valve independently controlled high-frequency electro-hydraulic vibration method is proposed to break through the limitations of current electro-hydraulic vibration technology in terms of system frequency bandwidth and waveform distortion.The new method can realize independent adjustment and control of vibration waveform frequency,amplitude and offset under high-frequency vibration conditions,and provide a new idea for accurate simulation of high-frequency vibration waveform.