Prediction of phosphorus content of electroless nickel–phosphorous coatings using artificial neural network modeling

A multilayer feedforward neural network with two hidden layers was designed and developed for prediction of the phosphorus content of electroless Ni–P coatings. The input parameters of the network were the pH, metal turnover, and loading of an electroless bath. The output parameter was the phosphorus content of the electroless Ni–P coatings. The temperature and molar rate of the bath were constant ( 91^° \textC, 0.4 \textNi^{\text + +} /\textH₂ \textPO₂ ^{- -} 91^\circ {\text{C}},\:0.4\,{\text{Ni}}^{{{\text{ + + }}}} /{\text{H}}_{2} {\text{PO}}_{2}^{{ - - }} ). The network was trained and tested using the data gathered from our own experiments. The goal of the study was to estimate the accuracy of this type of neural network in prediction of the phosphorus content. The study result shows that this type of network has high accuracy even when the number of hidden neurons is very low. Some comparison between the network’s predictions and own experimental data are given.     

谐振式微机械加速度计设计的关键技术

谐振式微机械加速度计直接输出频率信号,具有稳定性好、精度高的特点.分析了谐振式微机械加速度计的工作机理,建立了第一级敏感结构、杠杆机构和第二级敏感结构的数学模型,指出了实现高灵敏度加速度测量的关键技术在于支撑梁、质量块、谐振器和杠杆机构的设计.提出了一种谐振式微机械加速度计结构,进行了结构的优化设计和仿真计算,得出的性能指标:谐振频率98 858 Hz,Q值673.9,灵敏度24.52 Hz/gn.     

硅微机械谐振式陀螺仪的技术研究

介绍了硅微机械谐振式陀螺仪的工作原理,设计了一种新型微机械谐振式陀螺,并用有限元方法进行了仿真,制造了一批样机,进行了初步的驱动特性实验.结果表明,该微机械谐振陀螺仪实际驱动模态的谐振频率与仿真值的最大误差小于6%,满足设计要求.     

Improved design of a silicon micromachined gyroscope withpiezoresistive detection and electromagnetic excitation

In this paper, an improved design of a silicon micromachined gyroscope (angular rate sensor) is presented. It is based on the tuning fork principle and realized by combining two proof masses. The gyroscope is driven by electromagnetic forces and detects the Coriolis force by means of four piezoresistors connected in a Wheatstone bridge. The main fabrication steps including advanced deep reactive ion etching (ADRIE) and a wafer scale packaging are reported. The major novelty consists in a new design to reduce output drift. Both a higher symmetric mechanical structure and a separation of the first and the second mechanical resonant frequencies have been successfully investigated. This allows both driving and sensing of the device at its first resonant frequency while not exciting the second one. Thus, better uncoupling between the sensor modes has been obtained. As main results, a bandwidth of 10 Hz has been achieved and long-term measurements have been performed which were not possible with the previous design due to the low stability of the zero rate signal. For the current design, the dynamic behavior, the temperature dependence, rotation measurement, and the sensor stability have been characterized     

不等基频硅微谐振式加速度计

分析了硅微谐振式加速度计的两个谐振器在谐振频率相交点附近区域产生耦合的原因,设计了一种新型的不等基频硅微谐振式加速度计,并对其进行了有限元仿真.该加速度计由质量块、放大惯性力的杠杆机构以及一对尺寸不同的谐振器组成.采用DDSOG工艺加工.利用ANSYS有限元软件进行仿真,结果表明加速度计上谐振器的谐振基频为124 67...     

硅微机械振动陀螺的静电驱动

详细分析了双框架结构的硅微机械振动陀螺的驱动技术。结果说明：为了获得陀螺的最佳灵敏度，陀螺外框架上外加驱动电压的人小和频率的选择受到陀螺内外框架固有频率的约束。     

A method to simulate the vibrating characters of the resonator for resonant MEMS gyroscope

This paper proposes one study method of resonant MEMS gyroscope based on the circuit in order to solve problems such as long verification cycle and high cost of the MEMS gyroscope structure design. Firstly, on the basis of Euler–Bernoulli beam theory, this study establishes resonant beam vibration equation, obtains semi-Mathieu equation after normalization, namely parameter excitation characteristic equation of the frequency micro gyroscope, then deduces the characteristic equation in consideration of the damping condition, and uses the parameter perturbation method to study the output characteristic of gyroscope under ideal and damping states. Then, the analog circuit is innovatively used to obtain the characteristic equation of gyroscope under ideal and damping states, subsequently, the characteristic equation is normalized. It is realized that the dynamics equation is equivalent to the analog circuit. Finally, the experimental study is carried out, and experimental device for the frequency micro gyroscope harmonic oscillator parameter excitation characteristic is produced. Meanwhile, the analog circuit output waveform and frequency change correctness are verified by using the Runge–Kutta method and the parameter perturbation method, respectively. The experimental results show that the experiment device can be used to study the nonlinear vibration characteristics of the gyroscope.     

Strong-Stability-Preserving 7-Stage Hermite–Birkhoff Time-Discretization Methods

Optimal, 7-stage, explicit, strong-stability-preserving (SSP) Hermite–Birkhoff (HB) methods of orders 4 to 8 with nonnegative coefficients are constructed by combining linear k-step methods with a 7-stage Runge–Kutta (RK) method of order 4. Compared to Huang’s hybrid methods of the same order, the new methods generally have larger effective SSP coefficients and larger maximum effective CFL numbers, \textnum_\texteff\text{num}_{\text{eff}}, on Burgers’ equation, independently of the number k of steps, especially when k is small for both methods. Based on \textnum_\texteff\text{num}_{\text{eff}}, some new methods of order 4 compare favorably with other methods of the same order, including RK104 of Ketcheson. The new SSP HB methods are listed in their Shu–Osher representation in Appendix.     

Meta-logic programming for a synonymy logic

In order to give a suitable framework for a synonymy-based logic programming, we argue about the possibility of reducing fuzzy logic programming to classical logical programming. More precisely, we show that given a fuzzy program in a language L, we can translate it into an equivalent classical program in a (meta-)language \textL_m {\text{L}}_{m} in which every predicate name in L becomes a constant in \textL_m . {\text{L}}_{m} . This enables us to admit in \textL_m {\text{L}}_{m} meta-relations among predicates and therefore, in particular, the synonymy.     

A Single-Crystal Silicon Symmetrical and Decoupled MEMS Gyroscope on an Insulating Substrate

This paper presents a single-crystal silicon symmetrical and decoupled (SYMDEC) gyroscope implemented using the dissolved wafer microelectromechanical systems (MEMS) process on an insulating substrate. The symmetric structure allows matched resonant frequencies for the drive and sense vibration modes for high-rate sensitivity and low temperature-dependent drift, while the decoupled drive and sense modes prevents unstable operation due to mechanical coupling, achieving low bias-drift. The 12–15-$mu m$-thick single-crystal silicon structural layer with an aspect ratio of about 10 using DRIE patterning provides a high sense capacitance of 130 fF, while the insulating substrate provides a low parasitic capacitance of only 20 fF. A capacitive interface circuit fabricated in a 0.8-$mu m$CMOS process and having a sensitivity of 33 mV/fF is hybrid connected to the gyroscope. Drive and sense mode resonance frequencies of the gyroscope are measured to be 40.65 and 41.25 kHz, respectively, and their measured variations with temperature are$+18.28~ Hz/~^circ C$and$+18.32~ Hz/~^circ C$, respectively, in$-40~^circ C$to$+85~^circ C$temperature range. Initial tests show a rate resolution around 0.56 deg/s with slightly mismatched modes, which reveal that the gyroscope can provide a rate resolution of 0.030 deg/s in 50-Hz bandwidth at atmospheric pressure and 0.017 deg/s in 50-Hz bandwidth at vacuum operation with matched modes.hfillhbox[1195]     

无驱动结构微机械陀螺理论分析

应用欧拉动力学基本方程,对无驱动结构的硅微机械陀螺进行了理论分析,推导出陀螺在俯仰和偏航角速度同时存在情况下的动力学方程,建立了陀螺输出信号的数学模型。理论分析了陀螺输出信号的特点以及与俯仰、偏航角速度的关系。最后,通过实物仿真实验,验证了推导的正确性,为无驱动结构陀螺的应用提供了理论指导。     

A HARPSS polysilicon vibrating ring gyroscope

This paper presents the design, fabrication, and testing of an 80-μm-thick, 1.1 mm in diameter high aspect-ratio (20:1) polysilicon ring gyroscope (PRG). The vibrating ring gyroscope was fabricated through the high aspect-ratio combined poly and single-crystal silicon MEMS technology (HARPSS). This all-silicon single-wafer technology is capable of producing electrically isolated vertical electrodes as tall as the main body structure (50 to 100's (μm tall)) with various size air-gaps ranging from submicron to tens of microns. A detailed analysis has been performed to determine the overall sensitivity of the vibrating ring gyroscope and identify its scaling limits. An open-loop sensitivity of 200 μV/deg/s in a dynamic range of ±250 deg/s was measured under low vacuum level for a prototype device tested in hybrid format. The resolution for a PRG with a quality factor (Q) of 1200, drive amplitude of 0.15 μm, and sense node parasitic capacitances of 2 pF was measured to be less than 1 deg/s in 1 Hz bandwidth, limited by the noise from the circuitry. Elimination of the parasitic capacitances and improvement in the quality factor of the ring structure are expected to reduce the resolution to 0.01 deg/s/(Hz)^0.5     

Optimal design and noise consideration of micromachined vibratingrate gyroscope with modulated integrative differential optical sensing

A novel design of a micromachined vibrating rate gyroscope is presented. The rate gyroscope consists of a suspended proof mass which is attached by indium bumps to a CMOS chip. The proof mass is excited to vibration by electrostatic force. The displacements due to rate are sensed optically, using CMOS-integrated photodiodes and analog electronics. System considerations, including the mechanical behaviour, optical sensing, electronics, and noise sources of the rate gyroscope, are discussed. An expression for the noise equivalent rate (NER) of the system is obtained in order to derive an optimal design approach for the rate gyroscope. Optimal design and simulations of a case study of a rate gyroscope are presented. The device shows the ability of sensing 1 deg/h even at moderate quality factors of the order of 5000 and low-excitation voltages of 2.25 V     

A dual-axis MEMS capacitive inertial sensor with high-density proof mass

This paper reports a novel dual-axis microelectromechanical systems (MEMS) capacitive inertial sensor that utilizes multi-layered electroplated gold. All the MEMS structures are made by gold electroplating that is used as a post complementary metal-oxide semiconductor (CMOS) process. Due to the high density of gold, the Brownian noise on the proof mass becomes lower than those made of other materials such as silicon in the same size. The single gold proof mass works as a dual-axis sensing electrode by utilizing both out-of-plane (Z axis) and in-plane (X axis) motions; the proof mass has been designed to be 660 μm × 660 μm in area with the thickness of 12 μm, and the actual Brownian noise in the proof mass has been measured to be 1.2 \({\upmu}{\text{G/}}\sqrt {\text{Hz}}\) (in Z axis) and 0.29 \({\upmu}{\text{G/}}\sqrt {\text{Hz}}\) (in X axis) at room temperature, where 1 G = 9.8 m/s². The miniaturized dual-axis MEMS accelerometer can be implemented in integrated CMOS-MEMS accelerometers to detect a broad range of acceleration with sub-1G resolution on a single sensor chip.     

MEMS压电-磁电复合式振动驱动微能源的设计

在单一效应的MEMS振动驱动微能源的基础上,提出了一种MEMS压电-磁电复合振动驱动微能源器件。该微能源由八悬臂梁-中心质量块结构和永磁铁两部分组成,环境振动使中心质量块振动,PZT压电敏感单元由于压电效应产生电势差;同时中心质量块上集成的高密度线圈切割磁感线产生感应电动势,将压电转换与磁电转换相结合把振动能转换为电能。建立了该结构的数学模型并用有限分析软件Ansys12.0对该器件进行力学特性分析,最后对加工出的微能源进行性能测试。测试结果表明,该微能源谐振频率为8 Hz,易与环境发生共振;在共振条件下,施加1 gn 的加速度,器件压电发电开路输出电压峰峰值达154 mV,磁电发电开路输出电压峰-峰值达8 mV,有望为无线传感网络节点提供稳定的能源。     

Development of a Dual-Axis Convective Gyroscope With Low Thermal-Induced Stress Sensing Element

This paper describes the design, simulation, and fabrication of a dual-axis gyroscope, whose working principle is based on the thermal convective and thermoresistive effects in lightly doped p-type silicon. The sensor configuration consists of a piezoelectric pump and a microthermal sensing element that is packaged in an aluminum case with a diameter of 14 mm and a length of 25 mm. The novel structure of the sensing element reduces the thermal-induced stress up to 89% as compared with the previous design. The sensor has been fabricated by micro- electromechanical systems technology, and completely packaged and characterized. The measured sensitivities of the gyroscope for the X-axis and Y-axis were 0.082 and 0.078 mV/deg/s, respectively. The cross sensitivities between the two input axes were less than 0.26%, and the nonlinearity was smaller than 0.5% full scale in the range of plusmn200deg/s. The resolution was 0.2deg/s at a measurement frequency of 1 Hz. The noise equivalent rate was 0.18deg/s/radicHz, which is equivalent to an angle random walk of 10.8deg/radich in a 65-Hz bandwidth. The offset drift was 360deg/h in 12-h measurement.     

电容式微机械陀螺双环路闭环驱动电路研究

为了提高微机械陀螺系统的检测灵敏度,对微机械陀螺系统的驱动电路进行了研究.分析了微陀螺闭环驱动系统理论,基于此提出一种双环路闭环驱动方法,并且利用数学工具simulink建立系统模型,验证此方法的可行性,最后设计完成相应电路.此方法引入锁相环实现闭环驱动电路的稳频控制;采用自动增益控制器(AGC)实现恒幅控制.利用Hspice完成电路级仿真.结果表明,微机械陀螺双环路闭环驱动电路建立稳定振荡的时间为45 ms,稳定振荡频率为2.7553 KHz,频率偏差为0.1 z,频率抖动为0.056563 Hz.相对于传统的AGC闭环驱动电路,此闭环驱动电路建立稳定振荡时间缩短了30.77%,频率稳定性是传统AGC闭环驱动电路的32.72%.微机械陀螺环路闭环驱动电路提高驱动信号性能,对于微机械陀螺检测灵敏度的提高有着重要意义.     

Inherently robust micromachined gyroscopes with 2-DOF sense-mode oscillator

Commercialization of reliable vibratory micromachined gyroscopes for high-volume applications has proven to be extremely challenging, primarily due to the high sensitivity of the dynamical system response to fabrication and environmental variations. This paper reports a novel micromachined gyroscope with two degrees-of-freedom (DOF) sense-mode oscillator that provides inherent robustness against structural parameter variations. The 2-DOF sense-mode oscillator provides a frequency response with two resonant peaks and a flat region between the peaks, instead of a single resonance peak as in conventional gyroscopes. The device is nominally operated in the flat region of the sense-mode response curve, where the amplitude and phase of the response are insensitive to parameter fluctuations. Furthermore, the sensitivity is improved by utilizing dynamical amplification of oscillations in the 2-DOF sense-mode oscillator. Thus, improved robustness to variations in temperature, damping, and structural parameters is achieved, solely by the mechanical system design. Prototype gyroscopes were fabricated using a bulk-micromachining process, and the performance and robustness of the devices have been experimentally evaluated. With a 25 V dc bias and 3 V ac drive signal resulting in 5.8 /spl mu/m drive-mode amplitude, the gyroscope exhibited a measured noise-floor of 0.64/spl deg//s//spl radic/Hz over 50 Hz bandwidth in atmospheric pressure. The sense-mode response in the flat operating region was also experimentally demonstrated to be inherently insensitive to pressure, temperature, and dc bias variations.     

Post-CMOS-Compatible Aluminum Nitride Resonant MEMS Accelerometers

This paper describes the development of aluminum nitride (AlN) resonant accelerometers that can be integrated directly over foundry CMOS circuitry. Acceleration is measured by a change in resonant frequency of AlN double-ended tuning-fork (DETF) resonators. The DETF resonators and an attached proof mass are composed of a 1- $muhbox{m}$ -thick piezoelectric AlN layer. Utilizing piezoelectric coupling for the resonator drive and sense, DETFs at 890 kHz have been realized with quality factors $(Q)$ of 5090 and a maximum power handling of 1 $muhbox{W}$. The linear drive of the piezoelectric coupling reduces upconversion of $1/f$ amplifier noise into $1/f^{3}$ phase noise close to the oscillator carrier. This results in lower oscillator phase noise, $-$96 dBc/Hz at 100-Hz offset from the carrier, and improved sensor resolution when the DETF resonators are oscillated by the readout electronics. Attached to a 110-ng proof mass, the accelerometer microsystem has a measured sensitivity of 3.4 Hz/G and a resolution of 0.9 $hbox{mG}/surdhbox{Hz}$ from 10 to 200 Hz, where the accelerometer bandwidth is limited by the measurement setup. Theoretical calculations predict an upper limit on the accelerometer bandwidth of 1.4 kHz.$hfill$ [2008-0190]      

Maximum throughput of multiple access channels in adversarial environments

We consider deterministic distributed broadcasting on multiple access channels in the framework of adversarial queuing. Packets are injected dynamically by an adversary that is constrained by the injection rate and the number of packets that may be injected simultaneously; the latter we call burstiness. A protocol is stable when the number of packets in queues at the stations stays bounded. The maximum injection rate that a protocol can handle in a stable manner is called the throughput of the protocol. We consider adversaries of injection rate 1, that is, of one packet per round, to address the question if the maximum throughput 1 can be achieved, and if so then with what quality of service. We develop a protocol that achieves throughput 1 for any number of stations against leaky-bucket adversaries. The protocol has O(n²+\textburstiness){\mathcal{O}(n^2+\text{burstiness})} packets queued simultaneously at any time, where n is the number of stations; this upper bound is proved to be best possible. A protocol is called fair when each packet is eventually broadcast. We show that no protocol can be both stable and fair for a system of at least two stations against leaky-bucket adversaries. We study in detail small systems of exactly two and three stations against window adversaries to exhibit differences in quality of broadcast among classes of protocols. A protocol is said to have fair latency if the waiting time of packets is O(\textburstiness){\mathcal{O}(\text{burstiness})}. For two stations, we show that fair latency can be achieved by a full sensing protocol, while there is no stable acknowledgment based protocol. For three stations, we show that fair latency can be achieved by a general protocol, while no full sensing protocol can be stable. Finally, we show that protocols that either are fair or do not have the queue sizes affect the order of transmissions cannot be stable in systems of at least four stations against window adversaries.