Sound Transmission Loss Analysis of a Double Plate-Acoustic Cavity Coupling System with In-Plane Functionally Graded Materials

In this paper, the isogeometric analysis (IGA) is employed to develop an acoustic radiation model for a double plate-acoustic cavity coupling system, with a focus on analyzing the sound transmission loss (STL). The functionally graded (FG) plate exhibits a different material properties in-plane, and the power-law rule is adopted as the governing principle for material mixing. To validate the harmonic response and demonstrate the accuracy and convergence of the isogeometric modeling, ANASYS is utilized to compare with numerical examples. A plane wave serves as the acoustic excitation, and the Rayleigh integral is applied to discretize the radiated plate. The STL results are compared with the literature, confirming the reliability of the coupling system. Finally, the investigation is conducted to study impact of cavity depth and power-law parameter on the STL.

Impact Damage Identification for Composite Material Based on Transmissibility Function and OS-ELM Algorithm

A method is proposed based on the transmissibility function and the OnlineSequence Extreme Learning Machine (OS-ELM) algorithm, which is applied to theimpact damage of composite materials. First of all, the transmissibility functions of theundamaged signals and the damage signals at different points are calculated. Secondly,the difference between them is taken as the damage index. Finally, principal componentanalysis (PCA) is used to reduce the noise feature. And then, input to the online sequencelimit learning neural network classification to identify damage and confirm the damagelocation. Taking the amplitude of the transmissibility function instead of the accelerationresponse as the signal analysis for structural damage identification cannot be influencedby the excitation amplitude. The OS-ELM algorithm is based on the ELM (ExtremeLearning Machine) algorithm, in-creased training speed also increases the recognitionaccuracy. Experiment in the epoxy board shows that the method can effectively identifythe structural damage accurately.

Vibration and sound transmission loss characteristics of porous foam functionally graded sandwich panels in thermal environment

This study investigates the vibration and acoustic properties of porous foam functionally graded(FG)plates under the influence of the temperature field.The dynamics equations of the system are established based on Hamilton's principle by using the higher-order shear deformation theory under the linear displacement-strain assumption.The displacement shape function is assumed according to the four-sided simply-supported(SSSS)boundary condition,and the characteristic equations of the system are derived by combining the motion control equations.The theoretical model of vibro-acoustic coupling is established by using the acoustic theory and fluid-structure coupling solution method under the simple harmonic acoustic wave.The system's natural frequency and sound transmission loss(STL)are obtained through programming calculations and compared with the literature and COMSOL simulation to verify the validity and reliability of the theoretical model.The effects of various factors,such as temperature,porosity coefficients,gradient index,core thickness,width-to-thickness ratio on the vibration,and STL characteristics of the system,are discussed.The results provide a theoretical basis for the application of porous foam FG plates in engineering to optimize vibration and sound transmission properties.

Design and application of electric oil pump in automatic transmission for efficiency improvement and start–stop function

For the purpose of improving efficiency and realizing start–stop function, an electric oil pump(EOP) is integrated into an 8-speed automatic transmission(AT). A mathematical model is built to calculate the transmission power loss and the hydraulic system leakage. Based on this model, a flow-based control strategy is developed for EOP to satisfy the system flow requirement. This control strategy is verified through the forward driving simulation. The results indicate that there is a best combination for the size of mechanical oil pump(MOP) and EOP in terms of minimum energy consumption. In order to get a quick and smooth starting process, control strategies of the EOP and the on-coming clutch are proposed. The test environment on a prototype vehicle is built to verify the feasibility of the integrated EOP and its control strategies. The results show that the selected EOP can satisfy the flow requirement and a quick and smooth starting performance is achieved in the start–stop function. This research has a high value for the forward design of EOP in automatic transmissions with respect to efficiency improvement and start–stop function.

SYNTHESIS OF MULTIVALUED CMOS CIRCUITS WITH MANY VARIABLES BASED ON TRANSMISSION FUNCTION THEORY

Based on transmission function theory,the synthesis technique for multivaluedCMOS circuits is discussed.By comparing the CMOS circuits based on transmission functiontheory with the T gate,it is shown that their action principles are identical.Based on it,thesynthesis method for multivalued CMOS circuits with many variables by using function decom-position is proposed.

Global Stability Analysis of the Mathematical Model for Malaria Transmission between Vector and Host Population

In this paper, we discuss a mathematical model of malaria transmission between vector and host population. We study the basic qualitative properties of the model, the boundedness and non-negativity, calculate all equilibria, and prove the global stability of them and the behaviour of the model when the basic reproduction ratio R0 is greater than one or less than one. The global stability of equilibria is established by using Lyapunov method. Graphical representations of the calculated parameters and their effects on disease eradication are provided.

EMI下TTFPS算法传输可靠性的研究

为了评价TT-FPS调度算法的传输可靠性,考虑到电磁干扰(EMI)是造成CAN总线产生传输错误、影响传输可靠性的重要因素,首先以泊松分布为EMI干扰模型给出了在EMI下TT-FPS调度算法的概率化最糟糕响应时间计算方法,进而以此为基础给出了TT-FPS算法传输可靠性的计算方法,并通过实例分析验明了在传输性能和传输可靠性方面TT-FPS是一种处于FPS与TTCAN之间的折衷方案。所提出的TT-FPS传输可靠性计算方法已成功用于纯电动汽车CAN总线通讯系统的可靠性评价,取得了良好的效果。

TF分子基态(X^1∑^+)势能函数

电子相关耦合族方法CCSD(T)和QCISD(T)以及基组6-311++G**和cc-pvdz是目前最可靠的单参考组态方法。利用其对TF分子的基态进行优化计算,使优化的平衡间距分别为0.091 599 872 nm,0.091 971 495nm,0.091 623 623 nm,0.091 978 183 nm。它们与实验值0.091 760 000 nm基本吻合,误差小于0.000 22。采用标准Murrell-Sorbie函数进行非线性最小二乘法拟合,得到了TF分子势能函数的解析表达式。这样计算所得的力常数及光谱常数与实验数据符合得相当好。

一种基于改进TF-IDF函数的文本分类方法

为了解决传统TF-IDF函数由于忽略特征项之间的联系带来的诸多问题,对TF-IDF函数在文本分类中的应用进行了研究.结合信息论相关知识,找出了类间分布度和类内分布度表征特征项之间的潜在关系,进而提出改进的TF-IDF函数用于文本分类.实验表明,改进后的TF-IDF函数是有效可行的,而且较好的弥补了传统方法所丢失的特征项之间的关联信息,提高了文本分类的准确率.

纳米分子器件量子传导中的Green's Function模型

将纳米分子器件的电极和分子本体作为一个系统,考虑到入射电子在原子电极和分子本体中的传导,在电极与分子之间界面上的透射的量子状态,在满足Fisher-Lee关系式的基础上,一个新型的Green’sFunction被设计出来。这一理论模型把三个区域上的不同量子状态完整地表达在一个方程式里,符合物理学基本原理,可以系统地用来研究纳米分子器件的量子传导特性。

基于OTF的红外动态跟踪特性测试技术研究

根据基于空域的匀速直线运动、简谐振动的动像传递函数数学模型,设计光学系统,利用对被测红外系统在特定运动激励下的静像、动像传递函数测量,与理论数学模型进行比较,实现红外动态跟踪特性的评价,匀速直线运动下动像传递函数测量试验的结果表明,系统解决了运动对成像质量影响的测试难题。

循经针刺联合非手术脊柱减压对腰椎间盘突出症腰椎功能及血清TFAR19、Apaf-1的影响

目的探讨循经针刺联合非手术脊柱减压对腰椎间盘突出症腰椎功能及血清TF-1细胞凋亡相关基因19(TFAR19)、凋亡蛋白酶激活因子-1(Apaf-1)的影响。方法选取2018年6月—2020年7月该院收治的94例腰椎间盘突出症患者,随机分为对照组与观察组,各47例。对照组给予非手术脊柱减压治疗,观察组在对照组基础上另给予循经针刺治疗。对比治疗前、治疗3个月后腰椎功能[日本骨科协会腰椎功能(JOA)评分、Oswestry功能障碍指数(ODI)评分]及治疗前、治疗1个月、治疗3个月的腰腿疼痛评分[视觉模拟评分法(VAS)],并比较临床疗效及治疗前、治疗1个月、治疗3个月的椎旁肌肉肌电变化情况,另比较治疗前、治疗3个月后血清TFAR19、Apaf-1水平变化情况及治疗期间不良事件发生情况。结果两组治疗3个月后JOA评分均高于治疗前(P<0.05),观察组治疗3个月后高于对照组(P<0.05);两组治疗3个月后ODI评分均低于治疗前(P<0.05),观察组治疗3个月后低于对照组(P<0.05);两组治疗1个月、3个月的VAS评分均低于治疗前(P<0.05),治疗3个月的VAS评分均低于治疗1个月(P<0.05);观察组治疗1个月、3个月的VAS评分均低于对照组(P<0.05);观察组总有效率高于对照组(P<0.05);两组治疗1个月、3个月的竖脊肌及多裂肌积分肌电值(IEMG)、平均振幅、平均频率斜率均高于治疗前(P<0.05),治疗3个月均高于治疗1个月(P<0.05);观察组治疗1个月、3个月的竖脊肌及多裂肌IEMG、平均振幅、平均频率斜率均高于对照组(P<0.05);两组治疗3个月后血清TFAR19、Apaf-1水平均低于治疗前(P<0.05),观察组治疗3个月后血清TFAR19、Apaf-1水平均低于对照组(P<0.05);两组治疗期间不良事件发生率比较差异无统计学意义(P>0.05)。结论循经针刺联合非手术脊柱减压治疗腰椎间盘突出症患者,可明显减轻患者腰腿疼痛感,改善腰椎功能及椎旁肌肉肌力,提升椎旁肌群稳定性,降低血清TFAR19、Apaf-1水平,提高临床疗效,且安全性良好。

Dynamic design of a nonlinear energy sink with NiTiNOL-steel wire ropes based on nonlinear output frequency response functions

A novel vibration isolation device called the nonlinear energy sink(NES)with NiTiNOL-steel wire ropes(NiTi-ST)is applied to a whole-spacecraft system.The NiTi-ST is used to describe the damping of the NES,which is coupled with the modified Bouc-Wen model of hysteresis.The NES with NiTi-ST vibration reduction principle uses the irreversibility of targeted energy transfer(TET)to concentrate the energy locally on the nonlinear oscillator,and then dissipates it through damping in the NES with NiTi-ST.The generalized vibration transmissibility,obtained by the root mean square treatment of the harmonic response of the nonlinear output frequency response functions(NOFRFs),is first used as the evaluation index to analyze the whole-spacecraft system in the future.An optimization analysis of the impact of system responses is performed using different parameters of NES with NiTi-ST based on the transmissibility of NOFRFs.Finally,the effects of vibration suppression by varying the parameters of NiTi-ST are analyzed from the perspective of energy absorption.The results indicate that NES with NiTi-ST can reduce excessive vibration of the whole-spacecraft system,without changing its natural frequency.Moreover,the NES with NiTi-ST can be directly used in practical engineering applications.

Effect of Tooth Profile Modification on Vibration of Power Split Gear Transmission System

Based on Newton ' s second law,the bend-torsion-shaft coupling nonlinear dynamic model and equations of power split gear transmission system are established.According to the principle of tooth profile modification,the tooth profile modification is considered as time-varying gear backlash function acting along the line of action.Then the dynamic functions are solved by using Runge-Kutta numerical method.After analyzing the effect of tooth profile modification quantity( TPMQ) and relative tooth profile modification length( TPML) to the nonlinear dynamic characteristics of power split gear transmission,the following conclusions are drawn:1 The TPMQ of a certain stage transmission affects the vibration of its own stage more significantly than the other stage,and the coupling effect between two stages can be ignored usually in the modification design;2 If the first stage TPMLs are less than 0.3,the influence of the first stage TPMLs to the first stage transmission vibration is much more greatly than the influence of the second stage TPMLs to the first stage transmission vibration,or else both the first and second stage TPMLs affect the first stage transmission vibration largely.The same is true for the second stage TPMLs,and the cutoff value is 0.2;3 The TPMQ affects the vibration of power split gear transmission system more principally than the TPML,and should be top-priority in the modification design.

The Interaction of Oblique Flexural Gravity Waves With a Small Bottom Deformation on a Porous Ocean-Bed： Green＇s Function Approach

The interaction of oblique incident water waves with a small bottom deformation on a porous ocean-bed is examined analytically here within the framework of linear water wave theory. The upper surface of the ocean is assumed to be covered by an infinitely extended thin uniform elastic plate, while the lower surface is bounded by a porous bottom surface having a small deformation. By employing a simplified perturbation analysis, involving a small parameter c^（〈〈l ）, which measures the smallness of the deformation, the governing Boundary Value Problem （BVP） is reduced to a simpler BVP for the first-order correction of the potential function. This BVP is solved using a method based on Green＇s integral theorem with the introduction of suitable Green＇s function to obtain the first-order potential, and this potential function is then utilized to calculate the first-order reflection and transmission coefficients in terms of integrals involving the shape function c（x） representing the bottom deformation. Consideration of a patch of sinusoidal ripples shows that when the quotient of twice the component of the incident field wave number propagating just below the elastic plate and the ripple wave number approaches one, the theory predicts a resonant interaction between the bed and the surface below the elastic plate. Again, for small angles of incidence, the reflected wave energy is more as compared to the other angles of incidence. It is also observed that the reflected wave energy is somewhat sensitive to the changes in the flexural rigidity of the elastic plate, the porosity of the bed and the ripple wave numbers. The main advantage of the present study is that the results for the values of reflection and transmission coefficients obtained are found to satisfy the energy-balance relation almost accurately.

基于NTF仿真的汽车噪声源识别

介绍了噪声传递函数的基本理论.针对某款汽车,分析其道路试验得到的数据,发现转速为1 600 r·min-1左右时车内后排存在轰鸣声.针对该问题采用计算机辅助工程(CAE)方法进行了分析,通过在传动系统与车身连接点施加单位激励,运用Hyperworks软件中的Optistruct求解器求解后排右耳响应,并通过试验验证了仿真结果.仿真和试验结果均表明:在54 Hz左右,发动机二阶激励激起传动轴和后桥弯曲模态,产生共振,并通过车身连接点传到车身,从而激起空腔模态,导致后排产生轰鸣声.

Dynamic Fatigue Reliability Analysis of Transmission Gear Considering Failure Dependence

Multiple failuremodes and strength degradation are usually inherent in the gear transmission system,which brings new challenges for conducting fatigue reliability analysis and design.This paper proposes a novel dynamic fatigue reliability analysis method for failure dependence and strength degradation based on the combination of theCopula function and Gamma process.Firstly,the dynamic simulation model of the gear transmission system is established to obtain the dynamic stress-time history.The Gamma process is then used to describe the strength degradation to establish the dynamic stress-strength interference model.The marginal distribution functions of tooth contact fatigue and dedendumbending fatigue are calculated respectively based on the dynamic interferencemodel.Finally,the joint distribution of the two failure modes can be obtained by the t-Copula function to characterize the failure dependence,and so the dynamic fatigue reliability considering failure dependence can be estimated.The effectiveness of the proposed method is illustrated with examples.The results reveal the temporal law of reliability and the effects of failure dependence on dynamic fatigue reliability.

Measurements in Situ and Spectral Analysis of Wind Flow Effects on Overhead Transmission Lines

In the paper an important issue of vibrations of the transmission line in real conditions was analyzed.Such research was carried out by the authors of this paper taking into account the cross-section of the cable being in use on the transmission line.Analysis was performed for the modern ACSR high voltage transmission line with span of 213.0 m.The purpose of the investigation was to analyze the vibrations of the power transmission line in the natural environment and compare with the results obtained in the numerical simulations.Analysis was performed for natural and wind excited vibrations.The numerical model was made using the Spectral Element Method.In the spectral model,for various parameters of stiffness,damping and tension force,the system response was checked and compared with the results of the accelerations obtained in the situ measurements.A frequency response functions(FRF)were calculated.The credibility of the model was assessed through a validation process carried out by comparing graphical plots of FRF functions and numerical values expressing differences in acceleration amplitude(MSG),phase angle differences(PSG)and differences in acceleration and phase angle total(CSG)values.Particular attention was paid to the hysteretic damping analysis.Sensitivity of the wave number was performed for changing of the tension force and section area of the cable.The next aspect constituting the purpose of this paper was to present the wide possibilities of modelling and simulation of slender conductors using the Spectral Element Method.The obtained results show very good accuracy in the range of both experimental measurements as well as simulation analysis.The paper emphasizes the ease with which the sensitivity of the conductor and its response to changes in density of spectral mesh division,cable cross-section,tensile strength or material damping can be studied.

基于差异化建模与TF-IDF算法的城市功能区识别及混合度测算

基于POI性质、特点的不同,本文构建了一个融合统计分析法、核密度分析法的城市功能区定量识别模型,有效地识别出了广州市中心四区的功能区类型。利用耦合TF-IDF算法和信息熵算法测算城市功能混合度并进行面积加权,使得城市功能混合度测算更加符合实际情况。研究结果表明:广州市中心城区呈现出混合用地为主的特征,总体混合程度高。混合用地主要分布在研究区中心,单一类型用地零星分布在研究区外围,呈现出显著的“核心-外围”式的圈层化分布格局。城市功能混合度呈现“中心高,四周低”“多中心,组团式”、空间梯度差异显著的分布特征,并且功能混合程度与发展水平有一定正相关关系;功能分区结果与混合密度情况分布较为一致,表明本研究方法可行、研究结果合理。

CHARACTERISTIC IMPEDANCE OF SPECIFIC TRANSMISSION LINES WITH OFFSET INNER CONDUCTORS

The partial charge simulation method is presented to solve the characteristicimpedance of the transmission line of specific cross section with an offset inner conductor.Thismethod has a higher accuracy due to the accurate satisfaction of the boundary condition on theouter conductor.The combined method of the Gauss elimination and optimization is used tosolve the equation of charge simulation,and it is an effective method for increasing the accuracyand assuring the convergence.The Green’s functions of five transmission lines(i.e,with circular,elliptic,rectangular,trough and slab conductor)are given.