基于SDRS数据的钻石DA20飞机故障分析及处理

基于使用困难报告系统(SDRS)对钻石DA20飞机的故障数据进行分析。基于SDRS系统收集到的数据,结合故障分类方法,对钻石DA20飞机的不同故障进行研究,并提出相应的解决措施,有利于提高钻石DA20飞机机队的可靠性和安全性。

基于SDR的探测雷达反演树干分层介电参数仿真

为有效检测树干分层介质厚度和相对介电常数,该研究提出一种基于雷达探测的树干分层结构介电参数反演方法。基于斯涅耳定律结合树干生理结构特点,构建雷达信号在树干分层结构中的传播模型。利用软件定义无线电平台(software defined radio,SDR)搭建树干探测雷达。然后采用稀疏分解算法、K-SVD字典训练以及层剥离算法对探测雷达回波信号进行参数反演,并对不同的稀疏分解算法反演结果进行了对比。试验表明在回波混叠和无混叠的情况下,该方法均能够对树干分层介质厚度和相对介电常数进行估算;无混叠时相对介电常数和厚度的反演误差分别在2.93%和3.5%以内,混叠时相对介电常数和厚度的反演误差分别在7.52%和7.61%以内。综合试验结果表明,在5种反演算法中,SAMP算法在未知信号稀疏度的条件下表现最佳,具有较高的反演准确率和鲁棒性。

不同遗传背景对水稻sdr4突变体表型的影响

SDR4基因是借助QTL(quantitative trait loci)方法克隆的调控水稻种子休眠的关键基因。种子休眠性状是由多基因调控的。利用CRISPR/Cas9技术敲除日本晴品种和宜香1B品种的SDR4基因,发现前者突变体完全无休眠,种子活力差;而后者突变体的种子呈弱休眠,有一定比例的穗发芽,但未穗发芽的种子可耐受脱水干燥。此外,可以明显观察到宜香1B背景下sdr4突变体的胚胎体积增加、胚胎蛋白含量增多,为研究SDR4基因功能及其下游基因,甚至克隆SDR4互作基因提供了重要基础。

Linearized waveform inversion for vertical transversely isotropic elastic media:Methodology and multi-parameter crosstalk analysis

Seismic migration and inversion are closely related techniques to portray subsurface images and identify hydrocarbon reservoirs.Seismic migration aims at obtaining structural images of subsurface geologic discontinuities.More specifically,seismic migration estimates the reflectivity function(stacked average reflectivity or pre-stack angle-dependent reflectivity)from seismic reflection data.On the other hand,seismic inversion quantitatively estimates the intrinsic rock properties of subsurface formulations.Such seismic inversion methods are applicable to detect hydrocarbon reservoirs that may exhibit lateral variations in the inverted parameters.Although there exist many differences,pre-stack seismic migration is similar with the first iteration of the general linearized seismic inversion.Usually,seismic migration and inversion techniques assume an acoustic or isotropic elastic medium.Unconventional reservoirs such as shale and tight sand formation have notable anisotropic property.We present a linearized waveform inversion(LWI)scheme for weakly anisotropic elastic media with vertical transversely isotropic(VTI)symmetry.It is based on two-way anisotropic elastic wave equation and simultaneously inverts for the localized perturbations(ΔVp_(0)/Vp_(0)/Vs_(0)/Vs_(0)/,Δ∈,Δδ)from the long-wavelength reference model.Our proposed VTI-elastic LWI is an iterative method that requires a forward and an adjoint operator acting on vectors in each iteration.We derive the forward Born approximation operator by perturbation theory and adjoint operator via adjoint-state method.The inversion has improved the quality of the images and reduces the multi-parameter crosstalk comparing with the adjoint-based images.We have observed that the multi-parameter crosstalk problem is more prominent in the inversion images for Thomsen anisotropy parameters.Especially,the Thomsen parameter is the most difficult to resolve.We also analyze the multi-parameter crosstalk using scattering radiation patterns.The linearized waveform inversion for VTI-elastic media presented in this article provides quantitative information of the rock properties that has the potential to help identify hydrocarbon reservoirs.

Full waveform inversion based on hybrid gradient

The low-wavenumber components in the gradient of full waveform inversion(FWI)play a vital role in the stability of the inversion.However,when FWI is implemented in some high frequencies and current models are not far away from the real velocity model,an excessive number of low-wavenumber components in the gradient will also reduce the convergence rate and inversion accuracy.To solve this problem,this paper firstly derives a formula of scattering angle weighted gradient in FWI,then proposes a hybrid gradient.The hybrid gradient combines the conventional gradient of FWI with the scattering angle weighted gradient in each inversion frequency band based on an empirical formula derived herein.Using weighted hybrid mode,we can retain some low-wavenumber components in the initial lowfrequency inversion to ensure the stability of the inversion,and use more high-wavenumber components in the high-frequency inversion to improve the convergence rate.The results of synthetic data experiment demonstrate that compared to the conventional FWI,the FWI based on the proposed hybrid gradient can effectively reduce the low-wavenumber components in the gradient under the premise of ensuring inversion stability.It also greatly enhances the convergence rate and inversion accuracy,especially in the deep part of the model.And the field marine seismic data experiment also illustrates that the FWI based on hybrid gradient(HGFWI)has good stability and adaptability.

Truncated Gauss-Newton full-waveform inversion of pure quasi-P waves in vertical transverse isotropic media

Full-waveform inversion(FWI) uses the full information of seismic data to obtain a quantitative estimation of subsurface physical parameters. Anisotropic FWI has the potential to recover high-resolution velocity and anisotropy parameter models, which are critical for imaging the long-offset and wideazimuth data. We develop an acoustic anisotropic FWI method based on a simplified pure quasi P-wave(qP-wave) equation, which can be solved efficiently and is beneficial for the subsequent inversion.Using the inverse Hessian operator to precondition the functional gradients helps to reduce the parameter tradeoff in the multi-parameter inversion. To balance the accuracy and efficiency, we extend the truncated Gauss-Newton(TGN) method into FWI of pure qP-waves in vertical transverse isotropic(VTI) media. The inversion is performed in a nested way: a linear inner loop and a nonlinear outer loop.We derive the formulation of Hessian-vector products for pure qP-waves in VTI media based on the Lagrange multiplier method and compute the model update by solving a Gauss-Newton linear system via a matrix-free conjugate gradient method. A suitable preconditioner and the Eisenstat and Walker stopping criterion for the inner iterations are used to accelerate the convergence and avoid prohibitive computational cost. We test the proposed FWI method on several synthetic data sets. Inversion results reveal that the pure acoustic VTI FWI exhibits greater accuracy than the conventional pseudoacoustic VTI FWI. Additionally, the TGN method proves effective in mitigating the parameter crosstalk and increasing the accuracy of anisotropy parameters.

First-Arrival Picking Method for Active Source Data with Ocean Bottom Seismometers Based on Spatial Waveform Variation Characteristics

The precision and reliability of first-arrival picking are crucial for determining the accuracy of geological structure inversion using active source ocean bottom seismometer(OBS)refraction data.Traditional methods for first-arrival picking based on sample points are characterized by theoretical errors,especially in low-sampling-frequency OBS data because the travel time of seismic waves is not an integer multiple of the sampling interval.In this paper,a first-arrival picking method that utilizes the spatial waveform variation characteristics of active source OBS data is presented.First,the distribution law of theoretical error is examined;adjacent traces exhibit variation characteristics in their waveforms.Second,a label cross-correlation superposition method for extracting highfrequency signals is presented to enhance the first-arrival picking precision.Results from synthetic and field data verify that the proposed approach is robust,successfully overcomes the limitations of low sampling frequency,and achieves precise outcomes that are comparable with those of high-sampling-frequency data.

Co-Sharing Waveform Design for Millimeter-Wave Radar Communication Systems

Millimeter-wave(mmWave)radar communication has emerged as an important technique for future wireless systems.However,the interference between the radar signal and communication data is the main issue that should be considered for the joint radar communication system.In this paper,a co-sharing waveform(CSW)is proposed to achieve communication and radar sensing simultaneously.To eliminate the co-interference between the communication and sensing signal,signal splitting and processing methods for communication data demodulation and radar signal processing are given respectively.Simulation results show that the bit error rate(BER)of CSW is close to that of the pure communication waveform.Moreover,the proposed CSW can achieve better performance than the existing waveforms in terms of range and velocity estimation.

Underwater Pulse Waveform Recognition Based on Hash Aggregate Discriminant Network

Underwater pulse waveform recognition is an important method for underwater object detection.Most existing works focus on the application of traditional pattern recognition methods,which ignore the time-and space-varying characteristics in sound propagation channels and cannot easily extract valuable waveform features.Sound propagation channels in seawater are time-and space-varying convolutional channels.In the extraction of the waveform features of underwater acoustic signals,the effect of high-accuracy underwater acoustic signal recognition is identified by eliminating the influence of time-and space-varying convolutional channels to the greatest extent possible.We propose a hash aggregate discriminative network(HADN),which combines hash learning and deep learning to minimize the time-and space-varying effects on convolutional channels and adaptively learns effective underwater waveform features to achieve high-accuracy underwater pulse waveform recognition.In the extraction of the hash features of acoustic signals,a discrete constraint between clusters within a hash feature class is introduced.This constraint can ensure that the influence of convolutional channels on hash features is minimized.In addition,we design a new loss function called aggregate discriminative loss(AD-loss).The use of AD-loss and softmax-loss can increase the discriminativeness of the learned hash features.Experimental results show that on pool and ocean datasets,which were collected in pools and oceans,respectively,by using acoustic collectors,the proposed HADN performs better than other comparative models in terms of accuracy and mAP.

Joint Design of ISAC Waveform Under PAPR Constraints

In this paper,we formulate the precoding problem of integrated sensing and communication(ISAC)waveform as a non-convex quadratically constrained quadratic programming(QCQP),in which the weighted sum of communication multi-user interference(MUI)and the gap between dual-use waveform and ideal radar waveform is minimized with peak-toaverage power ratio(PAPR)constraints.We propose an efficient algorithm based on alternating direction method of multipliers(ADMM),which is able to decouple multiple variables and provide a closed-form solution for each subproblem.In addition,to improve the sensing performance in both spatial and temporal domains,we propose a new criteria to design the ideal radar waveform,in which the beam pattern is made similar to the ideal one and the integrated sidelobe level of the ambiguity function in each target direction is minimized in the region of interest.The limited memory Broyden-Fletcher-Goldfarb-Shanno(LBFGS)algorithm is applied to the design of the ideal radar waveform which works as a reference in the design of the dual-function waveform.Numerical results indicate that the designed dual-function waveform is capable of offering good communication quality of service(QoS)and sensing performance.

基于多通道SDR和DOA算法的车载广播信号接收增强技术研究

现代车载广播在车辆通信中扮演关键角色,连接驾驶员与外界信息,对通讯体验和车辆安全性有着非常重要作用。然而,城市环境的信号干扰和偏远地区的覆盖问题限制了信号接收质量,削弱了通信效果和应急响应能力。本研究旨在优化车载广播的信号接收性能,从而提高通信质量。将多通道SDR模块和DOA技术相结合,搭建了相应的硬件平台,仿真了多通道天线在车载应用和实验环境中的方向增强特性,获得了信噪比提升的实验效果,为车载广播信号接收增强提供了有益的技术参考。

Electroacupuncture with different waveforms for primary dysmenorrhea:A randomized controlled trial

Objective:To observe and compare the clinical effects of different electroacupuncture waveforms on primary dysmenorrhea.Methods: This was a prospective,randomized,three-group,parallel-controlled trial.Participants with primary dysmenorrhea were randomly divided into dense-sparse wave,continuous wave,and discontinuous wave groups in a 1:1:1 ratio.Two lateral Ciliao(BL 32)points were used.All three groups started treatment 3–5 days before menstruation,once a day for six sessions per course of treatment,one course of treatment per menstrual cycle,and three menstrual cycles.The primary outcome measure was the proportion with an average visual analog scale(VAS)score reduction of≥50%from baseline for dysmenorrhea in the third menstrual cycle during treatment.The secondary outcome measures included changes in dysmenorrhea VAS scores,Cox Menstrual Symptom Scale scores and the proportion of patients taking analgesic drugs.Results: The proportion of cases where the average VAS score for dysmenorrhea decreased by≥50%from baseline in the third menstrual cycle was not statistically significant(P>.05).Precisely 30 min after acupuncture and regarding immediate analgesia on the most severe day of dysmenorrhea,there was a statistically significant difference in the dense-sparse wave group compared with the other two groups during the third menstrual cycle(P<.05).Additionally,there was a statistically significant difference between the dense-sparse wave and discontinuous wave groups 24 h after acupuncture(P<.05).Conclusions: Waveform electroacupuncture can alleviate primary dysmenorrhea and its related symptoms in patients.The three groups showed similar results in terms of short-and long-term analgesic efficacy and a reduction in the number of patients taking analgesic drugs.Regarding achieving immediate analgesia,the dense-sparse wave group was slightly better than the other two groups.

关于敌我识别信号M5的SDR实现研究

文章首先阐述了SDR收发框架及配套软件工具GNURadio,其次介绍了敌我识别系统的工作组成,并围绕系统工作模式5(M5)的物理层特性展开了分析,最后进行了软件仿真设计和硬件实现。测量结果表明,时频域信息与理论特性接近一致。

Simultaneous Waveform Inverse Modelling for Litho-Fluid Prediction in an Old Marginal, “Agbbo”Field, Onshore Niger Delta, Nigeria

Simultaneous waveform inversion was used to predict lithofacies and fluid type across the field. Very often, characterizing reservoirs in terms of lithology and fluid type using conventional methods is replete with uncertainties, especially in marginal fields. An approach is employed in this study that integrated rock physics and waveform inverse modelling for lithology and fluid-type characterization to appropriately identify potential hydrocarbon saturated zones and their corresponding lithology. Seismic and well-log data were analyzed using Hampson Russel software. The method adopted includes lithofacies and fluid content analysis using rock physics parameters and seismic simultaneous inverse modelling. Rock physics analysis identified 2 broad reservoirs namely: HDZ1 and HDZ2 reservoirs. Results from the inverse modelling showed that low values of acoustic impedance from 19,743 to 20,487 (ft/s)(g/cc) reflect hydrocarbon-bearing reservoirs while medium to high values shows brine and shale respectively, with brine zone ranging from 20,487 to 22,531 (ft/s)(g/cc) and shale above 22,531 (ft/s)(g/cc). Two lithofacies were identified from inversion analysis of Vp/Vs and Mu-Rho, namely: sand and shale with VpVs 1.95 values respectively. Mu-Rho > 12.29 (GPa)(g/cc) and <12.29 (GPa) (g/cc) represent sand and shale respectively. From 3D volume, it was observed that a high accumulation of hydrocarbon was observed to be saturated at the north to the eastern part of the field forming a meandering channel. Sands were mainly distributed around the northeastern to the southwestern part of the field, that tends to be away from Well 029. This was also validated by the volume of rigidity modulus (Mu-Rho) showing high values indicating sands fall within the northeastern part of the field.

基于SDR的FPGA加速MIMO通信系统设计

重点研究基于软件定义无线电(Software Defined Radio,SDR)和现场可编程逻辑门阵列(Field Programmable Gate Array,FPGA)的多进多出(Multiple Input Multiple Output,MIMO)通信系统设计。利用SDR技术建立具有灵活性和可配置性的通信平台,以适应不同通信标准和应用场景。深入研究基于SDR的信号转换与处理方法,包括数字信号处理(Digital Signal Process,DSP)和MIMO信号处理算法。在此基础上,引入FPGA加速技术高效执行MIMO信号处理算法,提高系统的实时性和处理速度。最后,通过对比实验,验证所提出方法的性能优势。

基于SDR货币篮子的人民币汇率波动影响因素分析

本文依据购买力平价理论及利率平价理论,参考以SDR货币篮子为基础计算的人民币汇率指数的衡量方法,创新性地构建了主要国际经济体,即美国、欧盟、中国、日本及英国的综合物价水平指标、综合利率水平指标,实证研究了开放经济背景下,主要国际经济体综合物价水平和利率水平对人民币汇率波动的影响。结果表明,主要国际经济体的综合物价水平及利率水平均对人民币汇率指数具有显著影响,其中前者对人民币汇率指数变动具有正向效应,后者对人民币汇率指数具有负向效应。实证研究也表明,滞后一期的人民币汇率指数的影响力远高于主要国际经济体当期综合物价和利率,考虑到人民币汇率指数滞后一期受同期综合物价及利率水平的影响,因此推测当期人民币汇率指数受到前期主要国际经济体的物价水平、利率水平的影响更明显。本文仅供参考。

Theoretical Analysis and Design Implementation of FM Broadcast Receiving System based on SDR

ADALM Pluto is a software-defined radio product.Based on theoretical analysis,this paper designs a Frequency Modulation(FM)broadcast receiving system using ADALM Pluto as a wireless receiver on the Simulink platform.The simulation results show that the theoretical analysis is correct and the parameter settings are reasonable,and the Software-Defined Radio(SDR)has the characteristics of high performance,high ease of use,and low cost.

SDR在楔状缺损修复治疗中的疗效评价

选择门诊患者168人共302颗楔状缺损患牙,分别使用3种材料进行修复,随访观察12~15个月,比较疗效。结果发现,新型的楔状缺损修复材料(smart dentin replacement,SDR)(n=112)、玻璃离子水门汀(n=98)和光固化复合树脂(n=92)的修复成功率分别为96.2%、84.8%和86.2%,SDR的修复效果明显好于另外2组(P<0.01)。

人民币占SDR份额与我国国际收支平衡的关系研究:基于国际经验的比较借鉴

本文从理论和实证双重视角分析国际化货币占SDR份额变动与本币国国际收支间的关系,研究发现不同国际化阶段的货币占SDR份额变动对本币国国际收支差额变动影响迥异。具体而言,美元份额变动影响最小,欧元份额变动会带来较大的正向影响,英镑份额变动影响较为反复,而日元份额变动的负向影响要大于正向影响;基于国际化货币的经验,分析人民币占SDR份额变动对我国国际收支平衡模式选择的影响,并假设人民币占SDR份额逐步提升至20%、30%、40%时我国国际收支可能面临的情景与压力,进而提出在当前金融环境中,我国应谨慎提升人民币占SDR份额,稳步推进人民币国际化,构建市场化的国际收支平衡调节机制,积极推动扩大SDR使用规范和范围。

人民币加入SDR预期对其国际化的影响

一国货币的国际化程度主要体现在其国际影响力及对国际主要国家货币汇率波动的反应程度。人民币纳入SDR货币篮子将会改变人民币在国际货币金融体系中的地位与作用,从而影响人民币国际化程度。基于2015年8月11日至2016年3月16日的样本区间数据,通过构建VAR模型实证检验人民币加入SDR预期因素对人民币国际化程度的影响。结果发现:第一,人民币加入SDR预期能够提升人民币在国际货币金融体系中的影响力,尤其是人民币对美元的影响力将大大增加,但是其对世界其他主要货币的影响力仍显不足;第二,样本区间内,人民币自由化程度并没有提升,因为人民币汇率并没有随着世界主要货币汇率的波动而有所变化。