New forecasting model using type-2 fuzzy multivariate time series

利用Hypermesh和nastran创建mnf流程1.建立几何模型，定义材料属性、单元属性。

2.创建约束和特征值卡，如下：约束为无量纲。

定义为mis1,选择下列四点确定一个节点集定义。

定义单元集。

特征值为EIGRL特征。

3.对控制卡进行设置（1）sol（2）PARAMParam fixedb -1Param autospc yesParam post，0(3) case_unsupported_cards一般有以下部分：ADAMSMNF FLEXBODY=YES,OUTGSTRN=YES,OUTGSTRS=yes，EXPORT= BOTHRESVEC=yes，STRFIELD = ALLGPSTRESS=all **要求节点应力输出GPStrain（plot）=all **要求节点应变输出Stress（PLOT）=all **要求单元应力输出STRAIN(FIBER,PLOT) **要求单元应变输出OUTPUT(POST) ** 分界符Set 101=all **为面或者体定义单元集SURFACE 102 SET 101（**上面定义的单元集）FIBER=Z1，NORMAL zSet 103=allVolume 104 set 103 , direct **定义实体单元集的体积(4)bulk _unsupported _cardsDTI,UNITS,1,KG,N,M,S(5) global_case_controlSuper=1 Method=1Stress （plot ）=allStrain （fiber ，plot ）=all Gpstress=all Gpstrain=allCreate an MD DB using MD NastranMD DB can be created in the same was as creating MNF. A new option, EXPORT, is added to ADAMSMNF card to specify the output option.ADAMSMNF FLEXBODY=YES EXPORT=MNF/DB/BOTH MNF: generate modal neutral file DB: generate MD DBBOTH: generate both MNF and DBPlease refer to MD Nastran Quick Reference Guide and Reference Manual for details. Use Flex Toolkit to convert MNF to MD DBUse can also use the mnf2mtx utility to convert MNF to MD DB. The usage is: adams flextk mnf2mtx source.mnf -O dest.MASTERwhere source.mnf is the mnf you want to convert and dest.MASTER is the Database name. If dest.MASTER exists, mnf2mtx will append the flexible body in source.mnf to dest.MASTER. So user can combine MNFs into one MD DB using mnf2mtx. For example, adams flextk mnf2mtx source1.mnf -O dest.MASTER thenadams flextk mnf2mtx source2.mnf -O dest.MASTER点选EIGRL 卡Output 栏中相关主题PopupPopup另请参阅PopupTranslating FE Model Data > Translating MSC.Nastran DataTranslating MSC.Nastran DataThere are two different interfaces that you use to translate MSC.Nastran data for use in Adams/Flex. Learn about:• Using MSC.Nastran 2004 and Above• Using MSC.Nastran 69.x, 70.x, or 2001• Verifying the Model• Computing MSC.Nastran Stress/Strain Modes• MSC.Nastran XDB Support for Stress/Strain Modes• Shortened Stress/Strain ModesUsing MSC.Nastran 2004 and AboveStarting in version 2004, MSC.Nastran provides an improved interface for generating a modal neutral file (MNF). The new MSC.Nastran Adams Interface allows you to generate an MNF directly from MSC.Nastran without generating an OUTPUT2 file. The MSC.Nastran Adams Interface does not require a DMAP alter or a translator to convert MSC.Nastran output files to MNFs.The MSC.Nastran Adams Interface is a licensed feature of MSC.Nastran. For more information, contact your local sales representative. If you already have the MSC.Nastran Adams Interface license,refer to the MSC.Nastran Quick Reference Guide and Reference Manual for information on how to use it.Using MSC.Nastran 69.x, 70.x, or 2001Learn more about translating MSC.Nastran data using later versions of MSC.Nastran:• About the MSC.Nastran DMAP and OUTPUT2 to MNF Translator • Defining Your FE Model • Running MSC.Nastran • Running the Translator• Technical Notes on the MSC.Nastran DMAPNote: V ersions 69.x, 70.x, and 2001 of MSC.Nastran must be licensed to use the DMAP alters andrun solution 103. MSC.VisualNastran for Windows does not meet these requirements.About the MSC.Nastran DMAP and OUTPUT2 to MNF TranslatorTo generate a modal neutral file (MNF ) in versions 69.x, 70.x, or 2001 of MSC.Nastran, you need: • mnfx.alt - A solution sequence-independent DMAP alter. It directs MSC.Nastran to compute the data required for the MNF and write it to an OUTPUT2 file. Adams/Flex includes mnfx.alt DMAP in theAdams distribution.• msc2mnf.exe - MSC.Nastran OUTPUT2 file to MNF translator. It is an executable translator thatreads the MSC.Nastran OUTPUT2 file and writes MNFs.The mnfx.alt DMAP alter extracts flexible body information from MSC.Nastran. It uses thesuperelement techniques of component modal synthesis in MSC.Nastran to generate the flexible body information and output the data to a binary file, in full machine precision.The OUTPUT2 to MNF translator is based on the Adams MNF Toolkit, which you can configure to optimize the MNF .Defining Your FE ModelThe following outline the steps required to set up your MSC.Nastran input file to generate the necessary data for a modal neutral file (MNF ). To set up your MSC.Nastran input file:1. Create a finite element model of the flexible body. The finite element model is defined in the Bulk Data Section. For more information, see the MSC.Nastran Quick Reference Guide .2.Set up an MSC.Nastran analysis of the model using one of the following solution sequences: SOL 103, 111, 112. 3. Include a DTI, UNITS entry in the BULK DATA Section. Learn about setting units .4.Include the mnfx.alt DMAP alter distributed with Adams/Flex. You can obtain the file mnfx.alt from: install_dir /flex/examples/MSCNASTRAN/v69/mnfx.altinstall_dir /flex/examples/MSCNASTRAN/v70/mnfx.alt install_dir /flex/examples/MSCNASTRAN/v70.7/mnfx.alt install_dir /flex/examples/MSCNASTRAN/v2001/mnfx.alt5.In the File Management section of the MSC.Nastran input file, assign a file to be used as the output file and assign the file to unit 20. For example, enter the following to assign the output file test4.out to unit 20: assign output2='test4.out' status=unknown unit=20 form=unformattedNote: Unit must be 20. The DMAP alter is hard-coded to use unit 20.6.To avoid data recovery on the residual structure, include the following in the BULK DATA section: param,fixedb,-1Note: L oads, boundary conditions, and output requests are not necessary to the extent they are in aconventional analysis.Running MSC.NastranYou execute MSC.Nastran using the command nastran (your system administrator can assign a different name to the command). You specify keywords with the nastran command to request options for how to execute the MSC.Nastran job.Formatnastran input.dat keyword_1 = value_1 keyword_2 = value_2 ... where input.dat is the MSC.Nastran input file. Some common keywords are listed below. For information on keywords and their defaults, see the MSC.Nastran Installation and Operations Guide . Keyword DescriptionRunning the TranslatorOnce you've generated an output file, you can run the translator, msc2mnf.exe, to generate the modal neutral file (MNF ). You can run the translator:• Through the Adams/Flex Toolkit, which you access through Adams toolbar on UNIX and the StartMenu on Windows.For instructions about running the translator through the Adams/Flex toolkit, see Running theMSC.Nastran Translator .Before running the translator, be sure to set up the translation as explained in Setting Up TranslationOptions through the MNF Toolkit .To run the translator from the command window: Enter the following where file .out is the MSC.Nastran output file: msc2mnf.exe file.out For example, enter:msc2mnf.exe test4.outAlso, verify that the free body normal modes have a reasonable natural frequency. You should expect to see six rigid body modes, unless you fixed the DOFs with displacement boundary conditions.Technical Notes on MSC.Nastran DMAPThe next sections describe the DMAP alter in more detail and explain some optional parameters and settings that you might want to set before running a translation:• More on DMAP Alter• Optional Parameters You Can Set • Setting UnitsMore on DMAP AlterThe MSC.Nastran DMAP alter is organized on a superelement-by-superelement basis so you can output multiple MNF files from a single MSC.Nastran job. The input requirement is that each Adams flexible component be its own superelement.By default, the alter automatically orthogonalizes component modes within MSC/Nastran before outputting the data to the intermediate output file. A case control subcase and corresponding eigenvalue extraction entry (for example, EIGRL) are not necessary for the orthogonalization. Adams skips the subsequent orthogonalization phase if it detects diagonal mass and stiffness matrix input. You can generate additional diagnostic output and send it to the *.f06 file by setting the parameter check to 1 (param, check,1 in BULK DATA). For more information on diagnostics, see OptionalParameters You Can Set .The information that the alter provides is:• Units information, provided in a DTI entry. (For more information, see Setting Units .)• Grid and element connectivity output to neutral file, eliminating the need for any *.f06 output to beread.• Multiple coordinate systems because all quantities are transformed to the basic coordinate system priorto output.• Flexible body data including the following, which is written to the intermediate output file: • Grid data (BGPDT)• Element connection data (ECT) • Physical mass distribution (MGG)• Orthogonalized Craig-Bampton component modes• Generalized stiffness and generalized mass corresponding to the Craig-Bampton modesNote that WTMASS has been removed from all output mass quantities (physical and generalized). Units data input to Adams is expected to resolve all potential discrepancies.Optional Parameters You Can SetYou can set the following parameters in BULK DATA before translating the model using the param,name,value format:Setting UnitsBecause Adams/View and Adams/Solver require units, you must specify units in MSC.Nastran data using a DTI BULK DATA entry that includes the unique identifier UNITS. When you specify the units, the units apply to all superelements in your model.The format of the DTI BULK DATA entry is shown next. The table below lists the appropriate unit labels.DTI UNITS 1 MASS FORCE LENGTH TIMEFor example, you can enter the following for units:DTI UNITS 1 KG N M SUnit LabelsNote: A lthough you need the MSC.Nastran's WTMASS parameter to ensure consistent units inMSC.Nastran, MSC.Nastran ignores WTMASS when generating output for Adams/Flex. Instead, you supply units data for Adams/Flex using the DTI, UNITS entry, as explained earlier.For example, if you model mass in grams, force in Newtons, length in meters, and time in seconds, you set the WTMASS parameter to 0.001, ensuring that MSC.Nastran works with the consistent set of kg, N, and m. You then set the units for Adams/Flex by entering: DTI, UNITS, 1, GRAM, N, M, SOn the other hand, if you model length in inches and force in pounds, you can enter the mass in slug units with WTMASS set to 0.083 (=1/12), or in units of pounds mass with WTMASS set to 2.588e-3 (=1/32.2/12=1/386.4). The DTI, UNITS choices for Adams/Flex are, therefore, either of the following:DTI, UNITS, 1, SLUG, LBF, IN, S DTI, UNITS, 1, LBM, LBF, IN, SApplying the WTMASS parameter directly to the mass (for example, specifying density in terms of [12slug/in**3]) is not acceptable for Adams/Flex because [12slug] is not a mass unit known to Adams.Verifying the ModelThe MSC.Nastran translator writes a summary of the modal neutral file (MNF ) export to the terminal window. If you are using MSC.Nastran 2004 or above, the Adams interface writes a summary of the MNF export to the MSC.Nastran output file. Please review this data for any concerns. In particular, ensure that the:• Mass, center of mass location, and moments of inertia are as expected.• During the MNF write, the constraint modes and the constrained normal modes are orthogonalized.This yields modes that are:• An approximation of the free-body normal modes.• Interface modes, where the interface is the collection of all the attachment point DOFs.Also, verify that the free body normal modes have a reasonable natural frequency. You should expect to see six rigid-body modes, unless displacement boundary conditions are present.Computing MSC.Nastran Stress/Strain ModesFor Adams/Durability to process stresses or strains on flexible bodies, modal stress or strain shapes need to be present in the modal neutral file (MNF ) of the flexible body. You do this by havingMSC.Nastran recover a stress or strain mode for every mode shape computed for Component Mode Synthesis (CMS).• MSC.Nastran Grid Point Stresses• Example• Known Limitations, Problems, and RestrictionsMSC.Nastran Grid Point StressesBecause modal information contained in the MNF can only be associated with nodes, the MSC.Nastran grid-point stress data recovery option is required. The following Case Control commands are required in the MSC.Nastran input file to compute stress or strain modes for the MNF:• GPSTRESS: Requests grid point stresses output.• GPSTRAIN: Requests grid point strains output.• STRESS(PLOT): Requests element stress output.• STRAIN(FIBER,PLOT): Requests element strain output.• OUTPUT(POST): Delimiter.• SET: Defines a set of elements for a surface or volume.• SURFACE: Defines a surface of plate elements referenced by the SET command.• VOLUME: Defines a volume of solid elements referenced by the SET command.For more information on these commands, see the Case Control section of the MSC.visualNastran Quick Reference Guide. For more information on computing grid point stresses, see the MSC.Nastran Linear Static Analysis User's Guide.Note: Y ou can only transfer one surface stress or strain fiber of plate elements to the MNF for processing in Adams. If more than one fiber is specified on the SURFACE card, the msc2mnf translator issues a warning message and only transfers the first surface stress fiber it finds inthe OUTPUT2 file.Including stress or strain modes in the MNF can significantly increase the file size. Therefore, it becomes even more important to optimize the MNF if possible. For information onoptimizing the MNF, see Optimizing an MNF or an MD DB. Including both stress and strainmodes will further increase the size of the MNF and is generally not recommended for largemodels, unless both quantities are needed.When defining subcases in Case Control, you must have the GPSTRESS, GPSTRAIN,STRESS, and STRAIN cards before the first SUBCASE card. In addition, the OUTPUT,SURFACE, and VOLUME cards should follow all subcase definitions and appear at the end of the Case Control.ExampleExample above shows the changes that are required in the MSC.Nastran input file when the computation and transfer of both stress and strain modes are desired. Because the model contains solid and shell elements, a surface and a volume are defined for computing these grid-point stresses and strains. The surface fiber selected is Z1 and the grid-point stress/strain coordinate system is consistently defined to be the basic FE model system.Known Limitations, Problems, and Restrictions• Only one FIBER is output on SURFACE.• SURFACE or VOLUME should be defined in consistent coordinate (basic) system.MSC.Nastran XDB Support for Stress/Strain ModesYou can store the ortho-normal stress and/or strain modes in XDB file format that are compatible with the mode shapes in the modal neutral file (MNF) and subsequent modal responses from an Adams simulation. The benefits of this capability are:• Unlimited model size - MSC.Patran can access results from an XDB file of any size and with muchmore efficiency than from an OP2 file.• MSC.Fatigue analysis - Modal coordinates from Adams can be combined with stress or strain modes in XDB file for very efficient MSC.Fatigue analysis using modal superposition.• Element-based support - The XDB file format supports element-based and/or grid-point based stress or strain. Element-based results allow you to perform advanced fatigue analyses such as multi-axial fatigue and weldments.Learn more:• Creating an XDB File• Limitations• ExamplesCreating an XDB FileTo create an XDB file with stress or strain modes, add the following entry in the Bulk Data section: PARAM,POST,0This is in addition to the necessary commands that are added to Case Control (see Computing MSC.Nastran Stress/Strain Modes ). In the case of grid point stresses or strain, however, one additional command is required to output grid point stress or strain modes:STRFIELD = ALLNote that if you are only interested in working with element-based stress or strain, this command is not needed. For more information on these entries and commands see the, MSC.Nastran Quick Reference Guide.Limitations• Grid-point strain modes cannot be stored in the XDB nor can MSC.Patran post-process them. • Element-based stress or strain modes cannot be stored in the MNF nor can Adams/Durability postprocess them.ExamplesThe following are examples of MSC.Nastran input decks. See the Case Control section of theMSC.Nastran Quick Reference Guide for more information on the AdamsMNF command that is being used in these examples.Example of Requesting No Grid Point Stress/StrainIn the following example, no grid point stress or strain modes have been requested. Only element-based strain modes have been requested with STRAIN(PLOT) = ALL. These strains will be stored in the XDB (PARAM,POST,0) for postprocessing in MSC.Patran or for combining with Adams modal responses from Adams/Durability for an MSC.Fatigue analysis. This is the most efficient process for obtaining strains for the sole purpose of performing a fatigue analysis. If you are not interested in viewing strains in Adams, there is no need to compute grid-point strain modes nor storing them in the MNF . You will also seea savings in file size and processing time from this. The same is true for stress modes if they are desired over strains.SOL 103CENDAdamsMNF, FLEXBODY=YES, OUTGSTRS=NO, OUTGSTRN=NO...STRAIN(PLOT) = ALL...BEGIN BULK...PARAM,POST,0...ENDDATAExample of Requesting Grid-Point Stress on All Solid ElementsIn the following example, grid-point stress (GPSTRESS) modes have been requested on all solid elements (VOLUME). This data, as well as the element-based stress (STRESS) modes, will be stored in the XDB due to the STRFIELD=ALL command and the PARAM,POST,0 card. The grid point stress modes will also be stored in the MNF with the OUTGSTRS=YES option set on the AdamsMNF command. This allows Adams/Durability to postprocess stresses on the flexible body in Adams using the modal stress recovery technique.SOL 103CENDAdamsMNF, FLEXBODY=YES, OUTGSTRS=YES, OUTGSTRN=NOSTRFIELD = ALL...STRESS(PLOT) = ALLGPSTRESS = ALLOUTPUT(POST)SET 92 = ALLVOLUME 12 SET 92 DIRECTBEGIN BULK...PARAM,POST,0...ENDDATAExample of Requesting Grid-Point StressIn the following example, again, grid-point stress modes have been requested. They will not be stored in the XDB, however, because the STRFIELD=ALL command is missing. Therefore, onlyelement-based stress modes will be available in the XDB. Grid-point stress modes will be stored in the MNF because the AdamsMNF option, OUTGSTRS is still set to YES.SOL 103CENDAdamsMNF, FLEXBODY=YES, OUTGSTRS=YES, OUTGSTRN=NO...STRESS(PLOT) = ALLGPSTRESS = ALLOUTPUT(POST)SET 92 = ALLVOLUME 12 SET 92 DIRECTBEGIN BULK...PARAM,POST,0...ENDDATAShortened Stress/Strain ModesShortened stress/strain modes refers to the capability of defining a group or subset of elements in FEA for stress/strain recovery during modal neutral file (MNF) generation. FEA programs allow you to judicially define subregions of your component where stress/strain is of interest. If these subregions are defined during MNF generation, the node length of the stress/strain modes becomes shorter than that for the mode shapes. This reduces the amount of stress/strain data in the MNF, and allows you to avoid doubling the file size when including stress or strain modes. Adams/Durability, however, will only be able to recover stress or strain at those subregions.Support for this capability was first introduced in version 2005. Before 2005, a null tensor (all zero values) would be stored in the MNF for those nodes that did not have stress/strain computed by the FEA program. No reduction in file size was obtained, but worse yet, Adams/Durability would report zero stress/strain for those nodes, which could be misleading. In Adams/Flex 2005 or greater, it is now possible to remove these zero stress/strain states during MNF optimization. More information on how to do this is provided in the next sections.Starting in MSC.Nastran 2005, only grid point stresses that are computed for a subset of the component are output to the MNF. Support for this capability by the other FEA programs is not yet available. Learn more:• Note on MNF Compatibility• MNF Translation and Optimization• Version ScenariosNote on MNF CompatibilityIn general, an MNF is upward, but not necessarily backward, compatible. Adams will always support earlier versions of the MNF. For example, an MNF generated in a version of MSC.Nastran before 2005 will be supported. However, an MNF generated by MSC.Nastran 2005 or later will be incompatible in a version of Adams earlier than 2005. This is because, by default, MSC.Nastran generates a version of the MNF that supports shortened stress/strain modes, or in other words, a reduced MNF. However, an option exists in Adams/Flex to convert a reduced MNF to a full MNF, so that it can be processed by earlier versions of Adams.MNF Translation and OptimizationSupport for shortened stress/strain modes is available in the Adams/Flex MSC-> Translator and -> Optimizer through the menu option Stress & Strain Modes. Three options are available as listed in the table below.Version ScenariosExampleIn this MSC.Nastran example, ten shell elements (CQUAD4) are used to model a beam. Grid point strains are requested (GPSTRAIN) on only four of the elements (4,5,6,7) because of the SET 100 specification on the SURFACE card. This results in a reduced MNF with shortened strain modes on grids that are common to those elements (grids 104 through 108 and 204 through 208).SOL 103CEND$AdamsMNF FLEXBODY=YES,OUTGSTRN=YES,OUTGSTRS=NOMETHOD=300RESVEC=NO$STRAIN(PLOT)=ALLGPSTRAIN(PLOT)=ALLOUTPUT(POST)SET 100 = 4,5,6,7SURFACE 101 SET 100 NORMAL X3 FIBRE=Z1$BEGIN BULKASET1,123,101,111,201,211SPOINT,1001,thru,1003QSET1,0,1001,thru,1003DTI,UNITS,1,KG,N,M,SPARAM,GRDPNT,0$EIGRL 300 -1. 3$GRID 101 0. 0. 0.GRID 102 0.05 0. 0.GRID 103 0.1 0. 0.GRID 104 0.15 0. 0.GRID 105 0.2 0. 0.GRID 106 0.25 0. 0.GRID 107 0.3 0. 0.GRID 108 0.35 0. 0.GRID 109 0.4 0. 0.GRID 110 0.45 0. 0.GRID 111 0.5 0. 0.GRID 201 0. 0.03 0.GRID 202 0.05 0.03 0.GRID 203 0.1 0.03 0.GRID 204 0.15 0.03 0.GRID 205 0.2 0.03 0.GRID 206 0.25 0.03 0.GRID 207 0.3 0.03 0.GRID 208 0.35 0.03 0.GRID 209 0.4 0.03 0.GRID 210 0.45 0.03 0.GRID 211 0.5 0.03 0.$CQUAD4 1 1 101 102 202 201 CQUAD4 2 1 102 103 203 202 CQUAD4 3 1 103 104 204 203 CQUAD4 4 1 104 105 205 204 CQUAD4 5 1 105 106 206 205 CQUAD4 6 1 106 107 207 206 CQUAD4 7 1 107 108 208 207 CQUAD4 8 1 108 109 209 208 CQUAD4 9 1 109 110 210 209 CQUAD4 10 1 110 111 211 210 $MAT1 1 2.+11 .3 7800. PSHELL 1 1 .01 1ENDDATA。

doi:10.3969/j.issn.1001-893x.2021.06.013引用格式:蒋平,谢跃雷.一种民用小型无人机的射频指纹识别方法[J].电讯技术,2021,61(6):737-743.[JIANG Ping,XIE Yuelei.A radio fre-quency fingerprint identification method for civil small UAVs[J].Telecommunication Engineering,2021,61(6):737-743.]一种民用小型无人机的射频指纹识别方法∗蒋㊀平∗∗,谢跃雷(桂林电子科技大学宽带与智能信息技术中心,广西桂林541004)摘㊀要:随着民用无人机的普及,无人机 黑飞 事件频频发生,给公共安全带来极大隐患㊂为了实现对 黑飞 无人机的有效监管,通过提取遥控信号指纹特征对无人机识别是一种有效的方法㊂基于民用小型无人机遥控信号通常采用跳频通信这一特性,通过分形贝叶斯变点检测算法对实测无人机遥控信号的瞬态起始点进行检测,并提取信号瞬态部分所含有的指纹特征,由主成分分析法进行特征降维,最后采用多分类支持向量算法对该信号进行分类及识别㊂实验结果表明,采用射频指纹法能够完成无人机型号的区分以及同一型号无人机的区分㊂关键词:民用小型无人机;射频指纹;遥控信号;分类识别;分形贝叶斯变点检测开放科学(资源服务)标识码(OSID):微信扫描二维码听独家语音释文与作者在线交流享本刊专属服务中图分类号:TN971㊀㊀文献标志码:A㊀㊀文章编号:1001-893X(2021)06-0737-07A Radio Frequency Fingerprint Identification Methodfor Civil Small UAVsJIANG Ping,XIE Yuelei(Research Center for Wideband and Intelligence Information Technology,Guilin University of Electronic Technology,Guilin541004,China) Abstract:With the popularization of unmanned aerial vehicles(UAVs),the illegal incident of UAV hap-pens frequently,which brings a significant threat to public security.In order to achieve effective supervision for illegal UAV,it is an effective method to extract fingerprint features of remote control signals for UAV i-dentification.Based on the characteristic that frequency hopping communication is usually used in the re-mote control signal of civil small UAV,this paper uses fractal Bayesian change point detection algorithm to detect the transient starting point of the measured UAV remote control signal,and extracts the fingerprint features contained in the transient part of the signal.The feature dimension is reduced by principal compo-nent analysis(PCA).Finally,the multi-classification support vector machine(SVM)algorithm is used to classify the signal.The experimental results show that the radio frequency distinct native attribute(RF-DNA)method can be used to distinguish the UAV model and even the same type UAV.Key words:civil small UAV;RF-DNA;remote control signal;classification and recognition;fractal Bayes-ian change point detection0㊀引㊀言随着民用小型无人机技术的高速发展,因操作人员缺乏安全意识,无人机侵入机场㊁军事基地㊁重要会场的违法事件屡有发生,给国家和社会带来了㊃737㊃第61卷第6期2021年6月电讯技术Telecommunication Engineering Vol.61,No.6 June,2021∗∗∗收稿日期:2020-07-07;修回日期:2020-08-03基金项目:广西科技重大专项(桂科AA17202022);认知无线电与信息处理教育部重点实验室主任基金项目(CRKL180105);广西研究生教育创新计划项目(2020YCXS021);桂林电子科技大学研究生优秀学位论文培育项目资助(18YJPYSS07)通信作者:879702235@严重的安全隐患[1]㊂因此,加强对无人机的管控势在必行,而如何探测和发现无人机则是实现管控的第一步[2-4]㊂探测和识别无人机的射频信号,是发现无人机的一种有效方法[5-7]㊂民用小型无人机的射频信号可分为遥控信号及图传信号,遥控信号用于无人机控制,通常采用跳频方式的扩频通信信号,而无人机图传信号则用于空中拍摄视频的传输,通常采用正交频分复用技术(Orthogonal Frequency Division Mul-tiplexing,OFDM)的调制信号㊂许多学者通过无人机遥控信号对无人机进行检测及识别,其中文献[5]给出了一种基于无线电信号特征识别的无人机监测算法设计,从跳频信号及图传信号方面对无人机进行探测,但未给出具体算法分析及更近一步的实现原理;文献[6]提出基于软件无线电平台的无人机入侵检测,通过无人机跳频信号特征对无人机进行检测与识别,能在15m内检测无人机的存在,但该方法无法完成对无人机具体型号的区分;文献[7]采用对跳频信号进行图像分类的方式完成无人机信号的检测与识别,并取得了较好的识别效果,但跳频信号易受噪声淹没造成信号丢失,导致其不能较好地进行参数估计,从而无法有效区分无人机型号,并且该方法不能区分个体㊂针对以上检测及识别所存在的缺陷,本文采用射频指纹提取法(Radio Frequency Distinct Native At-tribute,RF-DNA)[8-9]对遥控信号进行检测及识别㊂首先零中频接收机对无人机遥控信号进行侦收,随后检测遥控信号瞬态部分起始点并进行统计特征提取,构造RF-DNA指纹特征并对其进行特征降维,最后由多支持向量机(Support Vector Machine, SVM)分类器对无人机型号以及同一型号的个体进行区分㊂1　无人机遥控信号模型对于无人机的检测与识别,需从信号方面进行分析㊂民用无人机遥控信号通常采用跳频方式进行扩频通信[10-11],因此遥控信号即为用于无人机控制的跳频信号㊂跳频信号因其具有较好的抗干扰能力,广泛用于通信对抗方面,而民用无人机的控制也在其列㊂信息数据m(t)通过信号调制器得到d(t),发射的跳频信号为S(t)=d(t)S FH(t)㊂(1)式中:S FH(t)是跳频信号,表达式为S FH(t)=AðN-1k=0w T(t-kT h)cos[2πf k(t-kT h)+φn]㊂(2)式中:N为频点个数;A为振幅;w T为宽度为T h的矩形窗,T h为跳频信号的跳频周期;f0,f1,f2, ,f k为调频频率集;φn为初始相位,n=0,1,2, ,N-1㊂实测无人机遥控信号离散数据由Cool Edit Pro 软件打开,如图1所示㊂图1㊀无人机遥控信号瞬态及稳态图㊃837㊃电讯技术㊀㊀㊀㊀2021年㊀㊀从图1可知,不同厂商无人机机型具有不同瞬态部分,但同一无人机型号的瞬态部分不易区分㊂本文主要基于民用无人机遥控信号瞬态部分进行研究㊂对于无人遥控信号瞬态部分,因无人机发射设备硬件特性不同,导致瞬态部分出现细微差异,这些差异主要由无人机发射设备系统中的分立器件㊁信号混频器㊁功率放大器㊁数模转换器㊁滤波器㊁锁相环等多种硬件设备产生㊂瞬态部分不携带数据信息,只与硬件设备本身的特性有关,具有唯一性,所以常对瞬态部分进行分析㊂瞬态部分存在于信号功率由零变为额定功率之间,所以一般存在发射设备开关机时刻㊂因此采集发射设备的瞬态部分具有一定难度,尤其体现在硬件接收设备[12]㊂由于无人机遥控信号采用跳频通信方式,在操控无人机期间,信号会不停经历由功率零到额定功率的变化过程,所以采用RF -DNA 方法对无人机遥控信号进行检测及识别是一个有效的方法㊂2㊀基于RF -DNA 的无人机识别2.1㊀RF -DNA 特征提取RF -DNA 方法是近年来较为关注方法之一,最早由美国空军技术学院Temple 等人提出㊂该方法是一种采用统计方法生成射频指纹(Radio Frequen-cy Fingerprinting,RFF)特征的计算框架,可分成瞬态信号子区域划分㊁瞬态信号基础特征生成和瞬态信号统计特征生成㊂对于该算法,对其分步骤描述㊂Step 1㊀对接收信号X (n )进行希尔伯特变换,得其解析式:X (n )=I (n )+j Q (n )㊂(3)式中:I (n )㊁Q (n )为正交信号㊂Step 2㊀求信号瞬时幅度a (n )㊁瞬时相位p (n )和瞬时频率f (n ):a (n )=I (n )2+Q (n )2,(4)p (n )=arctan Q (n )I (n )éëêêùûúú,(5)f (n )=12πp (n )-p (n -1)Δn㊂(6)Step 3㊀为了消除零中频接收机偏差对瞬时信号影响,对瞬时信号进行中心化处理:a c (n )=a (n )-u a ,(7)f c (n )=f (n )-u f ㊂(8)对于瞬时相位,需在中心化处理之前对瞬时相位中的非线性分量进行逐个滤除,以保证特征提取质量:p nl =p (n )-2πu f (n )Δt ,(9)p c (n )=p nl (n )-u p nl ㊂(10)式中:u a ㊁u f 表示瞬时幅度与瞬时频率的均值,Δt 表示采样时间间隔,u p nl 为消除非线性分量后瞬时相位平均值,p nl 表示非线性相位响应,a c (n )㊁f c (n )㊁p c (n )分别为中心化处理后的瞬时幅度㊁瞬时频率㊁瞬时相位值㊂Step 4㊀将以上所求三个瞬时特征a c (n )㊁f c (n )㊁p c (n )进行分区,并对其求特征值㊂这里特征值有两种方式,第一种为求三个时域瞬时信号的方差㊁偏度和峰度,第二种为求三个时域瞬时信号的标准差㊁方差㊁偏度和峰度㊂标准差:σ=1N x ðN xn =1(x c (n )-u )2㊂(11)方差:σ2=1N x ðN xn =1(x c (n )-u )2㊂(12)偏度:r =1N x σ3ðN xn =1(x c (n )-u )3㊂(13)峰度:k =1N x σ4ðN xn =1(x c (n )-u )4㊂(14)式中:N x 表示中心化数据x c (n )的长度,u 表示x c (n )的均值㊂Step 5㊀求其特征向量,因其具有三种特征,方法一为标准RF -DNA 法,只求方差㊁偏度㊁峰度,则特征具有3ˑ3维,而方法二添加标准差这一特征,则特征具有3ˑ4维㊂每一架无人机的每一个跳频信号瞬时幅度㊁瞬时频率㊁瞬时相位特征所求标准差㊁方差㊁偏度㊁峰度的集如下:F a =[σσ2r k ]a ,(15)F p =σσ2r k []p ,(16)F f =σσ2r k []f ,(17)㊃937㊃第61卷蒋平,谢跃雷:一种民用小型无人机的射频指纹识别方法第6期F i=[F a F p F f]㊂(18)式中:F i为每一架无人机每一跳信号的特征集合㊂一架无人机所有跳频信号瞬态特征集如下:F R=F1,F2,F3, ,F N[]㊂(19)式中:N为每一架无人机跳频信号总共个数㊂所有无人机的无人机跳频信号瞬态特征集合表达式如下:F C=F R1,F R2,F R3, ,F Rj[]㊂(20)式中:j为无人机个数㊂取一组各个无人机瞬时幅度的标准差㊁方差㊁峰度㊁偏度特征进行特征统计,统计值如表1所示㊂表1㊀遥控信号瞬时幅度统计特征表特征标准差方差偏度峰度大疆精灵4pro1号8.611274.15310.0282 1.8725大疆精灵4pro2号7.633258.2650-0.6562 2.2574司马航模x8hw404.37152 1.6379ˑ105-0.2373 2.1364HM 6.021632.2594-7.231976.5866大疆悟252.0166 2.7057ˑ103 1.3153 3.8405司马航模x25pro233.0327 5.4304ˑ104-0.3815 1.6164 2.2㊀识别算法本文主要目的是从信号角度对无人机进行识别,其中识别的具体步骤如下:Step1㊀采集无人机实测数据㊂Step2㊀采用分形贝叶斯变点检测算法对无人机遥控信号瞬态部分进行提取㊂Step3㊀采用RF-DNA统计特征法进行特征提取,提取采用两种方式,第一种含有标准差,第二种不含有标准差㊂Step4㊀对Step3所提取的特征集采用主成分分析(Principal Component Analysis,PCA)算法进行特征降维,特征降维可将维数降维为二维㊁三维㊁四维等,不同维数对识别率有一定影响㊂Step5㊀通过SVM[13]分类器对降维后的数据进行分类识别㊂这里分类器采用Libsvm进行分类,该分类器具有多分类特点,采用的是一对一法完成多分类操作㊂3㊀实验分析本次实验主要采用自制硬件设备对大疆精灵4pro1号及2号㊁司马航模x8hw㊁HM㊁大疆悟2㊁司马航模x25pro无人机信号进行采集,完成相应信号预处理及分类识别,采集系统如图2所示㊂图2㊀无人机遥控信号采集系统实物图通过对5架无人机共225组信号数据段进行实验,其中每个无人机训练数据30组,测试数据15组㊂实验中,因含有三个瞬时特征且每一瞬时特征含有多种特征信息,且含有标准差的特征维数为12维,不含有标准差的为9维㊂采用PCA算法将特征集降维到二维㊁三维,其中二维散点图坐标轴F1㊁F2分别代表二维中维数特征,三维散点图中坐标轴F1㊁F2㊁F3分别代表三维中维数的特征㊂实验1:采用不含有标准差㊁特征降维维数为二维的方式进行分类识别,实测数据二维散点图如图3所示㊂图3㊀无人机遥控信号不含标准差二维特征散点图㊃047㊃电讯技术㊀㊀㊀㊀2021年该图共10类散点数据,主要是5类无人机训练数据和5类无人机测试数据,不同颜色及形状表示不同无人机㊂无人机训练数据用于建立数据单元库,无人机测试数据用于测试无人机识别率㊂从图中可知,不同无人机训练数据散点图分布区域不同,测试数据同样,但部分测试数据存在于其他组训练数据中,故该部分数据为错误识别组㊂无人机遥控信号不含标准差且二维特征识别率表如表2所示,其中无人机总识别率为80%㊂表2㊀无人机遥控信号不含标准差二维特征识别率无人机型号无人机识别率/%无人机总识别率/%大疆精灵4pro 80.000司马航模x8hw 73.333HM100.000大疆悟2无人机73.333司马航模x25pro73.33380实验2:采用不含标准差且特征维数为三维的方式进行分类识别,其散点图㊁识别率如图4及表3所示㊂图4㊀无人机遥控信号不含标准差三维特征散点图表3㊀无人机遥控信号不含标准差三维特征识别率无人机型号无人机识别率/%无人机总识别率/%大疆精灵4pro 100.000司马航模x8hw 86.666HM93.333大疆悟2无人机100.000司马航模x25pro93.33394.666通过图4及表3可知,相对于二维而言,在同样不含有标准差时,三维识别效果更佳,识别率达到94.666%㊂实验3:采用标准差且特征降维维数为二维的方式进行分类识别,其散点图及识别率如图5及表4所示㊂从图和表可知,相对于不含有标准差的二维散点图,含有标准差性能更好,且识别率达到97.333%㊂图5㊀无人机遥控信号含标准差二维特征散点图表4㊀无人机遥控信号含标准差二维特征识别率无人机型号无人机识别率/%无人机总识别率/%大疆精灵4pro 93.333司马航模x8hw100.000HM 100.000大疆悟2无人机100.000司马航模x25pro93.33397.333实验4:采用标准差,特征降维维数为三维方式进行分类识别,散点图及识别率如图6和表5所示,其中含有标准差且三维特征时,其识别率与二维特征相同㊂图6㊀无人机遥控信号含标准差三维特征散点图表5㊀无人机遥控信号含标准差三维特征识别率无人机型号无人机识别率/%无人机总识别率/%大疆精灵4pro 93.333司马航模x8hw 100.000HM100.000大疆悟2无人机100.000司马航模x25pro93.33397.333为更进一步测试识别性能,在实测数据中叠加㊃147㊃第61卷蒋平,谢跃雷:一种民用小型无人机的射频指纹识别方法第6期高斯白噪声,具体方法及步骤如下:Step 1㊀对实测训练数据建立数据单元库及训练数据特征集㊂Step 2㊀对实测测试数据叠加高斯白噪声㊂Step 3㊀通过分形贝叶斯变点检测㊁RF -DNA 统计特征提取已加高斯白噪声后数据特征集㊂Step 4㊀Step 3中已加高斯白噪声后数据特征集与Step 1中训练数据特征集进行均值中心化,产生新特征集,取新特征集中已加高斯白噪声部分特征数据组作为测试特征集㊂Step 5㊀对Step 4所得测试特征集进行PCA 降维,其中为验证维数影响,选择一维㊁二维㊁三维㊁四维作为测试变量㊂Step 6㊀采用SVM 多分类器进行分类,绘出两种识别率曲线图,一种为含有标准差二维特征㊁含有标准差三维特征㊁不含有标准差二维特征㊁不含有标准差三维特征在不同信噪比下识别率对比图,命名为无人机遥控信号不同标准差及不同维数特征识别率图;另一种为含有标准差下一维㊁二维㊁三维㊁四维特征在不同信噪比的识别率对比图,命名为无人机遥控信号含有标准差下不同维数特征识别率图㊂图7为无人机遥控信号不同标准差及不同维数特征识别率图㊂从图中可知,含有标准差识别率优于不含标准差识别率,且三维总体高于二维㊂含有标准差时,信噪比大于15dB 时,其二维及三维识别率大于70%,而不含有标准差时,信噪比大于20dB时,其识别率大于70%㊂总体而言,随着高斯白噪声的增加,识别率逐渐下降,但因对其中心化处理㊁散点图较为集中等原因,其识别率在低于40%以下呈现低识别率随机起伏等混乱状态㊂图7㊀无人机遥控信号不同标准差及不同维数特征识别率图图8是在不同信噪比且含有标准差这一特征下不同维数识别率,总体来说,四维优于三维,三维优于二维及一维㊂在信噪比小于-5dB 时,各维识别率皆低于60%;在信噪比大于20dB 时,各维数识别率且大于90%,且四维最高㊂从识别曲线总体来看,维数越高其识别率更高㊂图8㊀无人机遥控信号含有标准差下不同维数特征识别率图通过以上四个实验得出采用RF -DNA 法对实测无人机遥控信号可以完成其型号的区分,其中三维识别率最高,为97.33%㊂为了更好地验证射频指纹方法的优点,取同一型号的两架大疆精灵4pro 无人机进行个体区分实验,并得出散点图及不同维数识别曲线图㊂由图9(a)可知,同一型号无人机散点图较为紧密,区分难度较大,对分类器有一定要求㊂由图9(b)可知,一维与二维曲线相同,但整体维数对识别率无较大影响,主要受分析数量所限从而无法凸显维数优势㊂总体来说随着信噪比增加,识别率逐渐升高,当信噪比在17dB 以上时各维数识别率达到80%,因此可证明射频指纹识别法可对无人机个体进行区分㊂(a)同一型号无人机遥控信号二维散点图(b)同一型号无人机遥控信号含有标准差下不同维数特征识别率图图9㊀同一型号无人机遥控信号散点图及识别率图㊃247㊃ 电讯技术㊀㊀㊀㊀2021年4　结束语本文针对无人机 黑飞 问题,采用RF-DNA方法完成了无人机具体型号及其个体的识别,可为无人机有效监管提供帮助㊂采用是否含有标准差以及不同维数作为测试条件,验证了在含有标准差且维数为四维时对无人机的型号区分效果最好㊂而通过对两架大疆精灵4pro无人机进行同一型号个体区分实验,得出RF-DNA能够区分同一型号无人机,但是无人机型号的区分抗噪性能高于同一型号的个体区分㊂此外,由于本实验目前只做了两架无人机的同一型号区分,后面应考虑增加更多同一型号无人机,以便于验证一定数量无人机同时存在对个体区别所带来的影响㊂并且,下一步应寻求更好的特征及分类方式从而更有效地对同一型号无人机进行个体区分,增加其实用价值㊂参考文献:[1]㊀赵时轮.无人机危害及恐怖行为反制对策研究[J].中国军转民,2019(6):15-20.[2]㊀李晓文.小型无人机在战术空中控制中的应用分析[J].飞航导弹,2020(5):49-53.[3]㊀张嘉,李润文,崔铠韬.浅析无人机管控手段及无人机无线电反制设备对民航空管运行的影响[J].中国无线电,2019(8):16-18.[4]㊀罗淮鸿,卢盈齐.国外反 低慢小 无人机能力现状与发展趋势[J].飞航导弹,2019(6):32-36. [5]㊀何小勇,韩兵,张笑语,等.一种基于无线电信号特征识别的无人机监测算法设计[J].中国无线电,2019(11):72-74.[6]㊀徐淑正,孙忆南,皇甫丽英,等.基于软件无线电平台的无人机入侵检测[J].实验室研究与探索,2018,37(12):64-67.[7]㊀刘丽.民用无人机跳频信号分析与识别技术研究[D].北京:北京邮电大学,2019.[8]㊀季澈,彭林宁,胡爱群,等.基于射频信号特征的Air-max设备指纹提取方法[J].数据采集与处理,2020,35(2):331-343.[9]㊀曾勇虎,陈翔,林云,等.射频指纹识别的研究现状及趋势[J].电波科学学报,2020,35(3):305-315. [10]㊀张宝林,吕军,李彤,等.一种改进的跳频信号参数估计方法[J].电讯技术,2018,58(11):1310-1316. [11]㊀耿健,杨威.一种同步组网跳频信号的盲分离方法[J].电讯技术,2018,58(12):1464-1469. [12]㊀魏兰兰.基于设备指纹的无线设备识别研究[D].北京:北京交通大学,2019.[13]㊀梁楠,邹志红.结合新型模糊支持向量机和证据理论的多传感器水质数据融合[J].电讯技术,2020,60(3):331-337.作者简介:蒋㊀平㊀男,1994年生于四川成都,2017年于成都工业学院获工学学士学位,现为桂林电子科技大学硕士研究生,主要研究方向为无人机信号侦测与识别㊁FPGA的数字系统设计㊂谢跃雷㊀男,1975年生于河北邯郸,1997年和2003年于桂林电子科技大学分别获工学学士学位和硕士学位,现为副教授㊁硕士生导师,主要研究方向为通信信号处理㊁阵列信号处理及信号处理的VLSI设计实现㊂㊃347㊃第61卷蒋平,谢跃雷:一种民用小型无人机的射频指纹识别方法第6期。

第47卷第3期气象Vol.47No.3 2021年3月METEOROLOGICAL MONTHLY March2021张烨方，冯真祯，刘冰，2021.基于卷积神经网络的雷电临近预警模型气象,47(3):373-380.Zhang Y F,Feng Z Z,Liu B, 2021.Lightning nowcasting early warning model based on convolutional neural networC[J#Meteor Mon,47(3)：373-380(in Chinese).基于卷积神经网络的雷电临近预警模型!张烨方12冯真祯2刘冰21福建省灾害天气重点实验室，福州3500012福建省气象灾害防御技术中心，福州350001提要：从研究人工智能雷电临近预警模型的目的出发，以卷积神经网络模型为基础，结合多个时间序列的雷达产品(组合反射率、液态水含量、回波顶高)与闪电数据，对雷电临近预报方法进行基于卷积神经网络结构的应用，以福建省2017-2018年雷达、闪电数据为样本完成了模型的训练与预测研究)训练结果显示15〜30min模型训练样本测试集准确率为0.7985；选取福建省2019年20个雷电过程验证分析表明15〜30min模型对动力抬升型雷电过程预警TS评分为0.716,夏季局地热雷暴预警TS评分为0.694,与常规采用雷达、闪电阈值控制的雷电预警算法相比，准确率有一定的提高，具有一定的实践意义)关键词：卷积神经网络，雷电临近预警，人工智能中图分类号：P456,P457文献标志码：A DOI：10.7519/j.issn.1000-0526.2021.03.010Lightning Nowcasting Early Warning ModelBased on Convolutional Neural NetworkZHANG Yefang12FENG Zhenzhen2LIU Bing21Fujian Key Laboratory of Severe Weather,Fuzhou3500012Fujian Meteorological Disaster Prevention Technology Center,Fuzhou350001Abstract:For the purpose of studying the lightning nowcasting early warning model of artificial intelli­gence,by relying on the convolutional neural network model and combining the radar data(MCR,VIL, ET)andlightningdataofmultipletimeseries,weconducttheapplicationofthelightningnowcastingpre-diction methodbasedonthestructureofconvolutionalneuralnetwork.Inaddition,takingtheradarand lightningdataofFujianProvincein2017and2018assamples,wealsofinishthetrainingandpredictionre-search of the model.The training results show that the test set accuracy of15—30min model t r aining samplesis0.7985.Theverifica ionanalysisof he20ligh ningprocessesinFujianProvincein2019indi-ca es ha heTSscoreof he15—30minmodelfor henowcas ingearlywarningof hedynamic-lif ligh-ningprocessis0.716,and heTSscoreof helocalized hermal hunders paredwi h heconven ionalligh ningwarningalgori hm whichusesradarandligh ning hresholdcon rol,hesevalueshaveacer ainimprovemen inaccuracy,sohavingcer ainprac icalsignifi-cance.Key words:convolution neural network,lightning nowcasting early warning,artificial intelligence logical*福建省科技厅社会发展引导性(重点)项目(2019Y0063)，福建省气象局研究型业务专项项目(2020YJ08)共同资助2019年11月27日收稿；2021年1月24日收修定稿第一作者：张烨方，主要从事气象人工智能、气象预报方面研究.E-mail:228532148@374气象第47卷引言人工智能是近几年来发展特别迅速的一门科学技术，普遍被认为是下一场科技革命的生产力代表，2017年8月国务院印发《新一代人工智能发展规划》，提出了面向2030年我国新一代人工智能发展的战略目标。

NX Advanced FEM includes the fundamental modeling functions of automatic and manual mesh generation,application of loads and boundary conditions and model development and checking.A robust set of visualization tools generates displays quickly,lets you view multiple results simultane-ously and enables you to easily print the display.In addition,extensive post-processing functions enable review and export of analysis results to spreadsheets and provide extensive graphing tools for gaining an understanding of results.Post-processing also supports the export of JT ™data for collaboration across the enterprise with JT2Go and Teamcenter for lifecycle visualization.NX Advanced FEM provides seamless,transparent support for a number of industry-standard solvers,such as NX Nastran,MSC Nastran,Ansys and Abaqus.For example,when you create either a mesh or a solution in NX Advanced FEM,you specify the solver environment that you plan to use to solve your model and the type of analysis you want to perform.The software then presents all meshing,boundary conditions and solution options using the terminology or “language”of that solver and analysis type.Additionally,you can solve your model and view your results directly in Advanced FEM without having to first export a solver file or import your results.•Advanced FEM features data structures,such as the separate Simulation (.sim)and FEM files (.fem)that help facilitate the development of FE models across a distributed work environment.These data structures also allow analysts to easily share FE data to perform multiple types of analyses.•Advanced FEM offers world-class meshing capabilities.The software is designed to produce a very high quality mesh while using an economic element count.Advanced FEM supports a complete complement of element types (0D,1D,2D and 3D).Additionally,Advanced FEM gives analysts control over specific meshing tolerances that control,for example,how the software meshes complex geometry,such as fillets.•Advanced FEM includes multiple geometry abstraction tools that give analysts the ability to tailor the CAD geometry to the needs of their analysis.For example,analysts can use these tools to improvethe overall quality of their mesh by eliminating problematic geometry,such as tiny edges or slivers.NX Advanced FEMNX/plmfact sheetBenefitsEmbedded tools for 3D geometry creation and editing of both components and assembliesAssociation to the design geometry allows the analyst to work closely with the design engineer•Knowledge of design changes•“On-demand”FE model updates based on design geometry changesSupport for NX Manager and Teamcenter ®software for all created FE data setsSolver environments customized for the nomenclature of the selected solverA full range of tools for FE model generation including predefined constraint conditions and automated mesh mating conditionsVerification of models before processing with a full set of graphical and mathematical tools that help check model suitableAbility to view analysis results quickly and easily with a dynamic visualization toolExtensive post-processing tools to continue the iterative phases of analysis or to export/import informationDirect integration with Simulation Process Studio for CAE "best-practices"knowledge capture;including process wizard templates for vibration and stress analysisIntegrated basic durability analysis SummaryNX Advanced FEM software is a comprehensive multi-CAD finite element modeling and results visualization product that is designed to meet the needs of experienced CAE analysts.It includes a full suite of geometry creation and editing tools as well as FE pre-and post-processing tools and supports a broad range of product performance evaluation solutions.NX Advanced FEM provides 2-way association to NX design geometry,allowing users to rapidly iterate on design changes.Robust CAD translators,along with the embedded industry-standard Parasolid 3D modeling kernel,enable non-native geometry to be easily imported for use within the NX Advanced FEM environment.Siemens PLM Softwareremoval of design artifacts such as sliver faces, the actual design features but rather allows for quality of the mesh.This set of commandsmeshingtriangles or quadrilateral dominant meshes reduce element distortionsbefore meshingrigid bars,spring,gap andfeatures(updates occur with designtypes of analysis and modeling quickly and including linear and parabolic forms ofsprings,dampers,masses,rigid links andsymbols.P-elements(solid tetrahedra)aredisplacementsymbolsmaintained through design geometry changes conditions to correctly simulate nonlinearto Excel(Windows only)for further manipulation and results inspectiononly)or a spreadsheet text fileAnsys,Nastran,etc.Advanced FEM product include: Solution typeLinear statics(SOL101)with surface-to-surface contactNormal modes(SOL103) Response simulation(SOL103) Buckling(SOL105)Nonlinear statics(SOL106)Direct frequency response(SOL108) Direct transient response(SOL109) Modal frequency response(SOL111) Modal transient response(SOL112) Advanced nonlinear(SOL601) Linear and advanced nonlinear transient response(SOL129)transfer(SOL153)ContactSiemens PLM SoftwareAmericas8004985351Europe+44(0)1276702000Asia-Pacific852********/plm©2007.Siemens Product Lifecycle Management Software Inc.All rights reserved.Siemens and the Siemens logo are registered trademarks of Siemens AG. Teamcenter,NX,Solid Edge,Tecnomatix,Parasolid,Femap,I-deas,JT,UGS Velocity Series,Geolus and the Signs of Innovation trade dress are trademarks or registered trademarks of Siemens Product Lifecycle Management Software Inc.or its subsidiaries in the United States and in other countries.All other logos,trademarks,registered trademarks or service marks used herein are the property of their respective holders.9/07。