一种新型高精度线性压电激励器的研制

报道了一种新型压电线性激励器，设计出它的结构，完成了器件制作。设计测试系统对其性能进行测试。器件的线性步进位移特性明显，具有步进模式和连续线性位移模式。行程可达几个厘米、位移分辨率为0．1μm、运行速度可达0．6mm/s。激励器结构简单，控制方便，适于研制闭环控制高精度定位系统。     

压电直线驱动器

采用电磁与压电相结合的方式给出了一种直线驱动器,详细介绍了该驱动器的结构与工作原理,并对其牵引力进行了估算与分析;比较了几种典型的驱动器控制信号波形,并选择一种较为合理的波形进行了驱动器性能试验,试验结果表明该驱动器能够可靠地实现双向运动,具有行程大,精度高,易于控制等特点,可用于微定位、微驱动等领域。     

The MIMO ARQ Channel: Diversity–Multiplexing–Delay Tradeoff

In this paper, the fundamental performance tradeoff of the delay-limited multiple-input multiple-output (MIMO) automatic retransmission request (ARQ) channel is explored. In particular, we extend the diversity-multiplexing tradeoff investigated by Zheng and Tse in standard delay-limited MIMO channels with coherent detection to the ARQ scenario. We establish the three-dimensional tradeoff between reliability (i.e., diversity), throughput (i.e., multiplexing gain), and delay (i.e., maximum number of retransmissions). This tradeoff quantifies the ARQ diversity gain obtained by leveraging the retransmission delay to enhance the reliability for a given multiplexing gain. Interestingly, ARQ diversity appears even in long-term static channels where all the retransmissions take place in the same channel state. Furthermore, by relaxing the input power constraint allowing variable power levels in different retransmissions, we show that power control can be used to dramatically increase the diversity advantage. Our analysis reveals some important insights on the benefits of ARQ in slow-fading MIMO channels. In particular, we show that 1) allowing for a sufficiently large retransmission delay results in an almost flat diversity-multiplexing tradeoff, and hence, renders operating at high multiplexing gain more advantageous; 2) MIMO ARQ channels quickly approach the ergodic limit when power control is employed. Finally, we complement our information-theoretic analysis with an incremental redundancy lattice space-time (IR-LAST) coding scheme which is shown, through a random coding argument, to achieve the optimal tradeoff(s). An integral component of the optimal IR-LAST coding scheme is a list decoder, based on the minimum mean-square error (MMSE) lattice decoding principle, for joint error detection and correction. Throughout the paper, our theoretical claims are validated by numerical results     

Explicit Space–Time Codes Achieving the Diversity–Multiplexing Gain Tradeoff

A recent result of Zheng and Tse states that over a quasi-static channel, there exists a fundamental tradeoff, referred to as the diversity-multiplexing gain (D-MG) tradeoff, between the spatial multiplexing gain and the diversity gain that can be simultaneously achieved by a space-time (ST) code. This tradeoff is precisely known in the case of independent and identically distributed (i.i.d.) Rayleigh fading, for Tgesn_t+n_r-1 where T is the number of time slots over which coding takes place and n_t,n_r are the number of transmit and receive antennas, respectively. For Tt+n_r-1, only upper and lower bounds on the D-MG tradeoff are available. In this paper, we present a complete solution to the problem of explicitly constructing D-MG optimal ST codes, i.e., codes that achieve the D-MG tradeoff for any number of receive antennas. We do this by showing that for the square minimum-delay case when T=n_t=n, cyclic-division-algebra (CDA)-based ST codes having the nonvanishing determinant property are D-MG optimal. While constructions of such codes were previously known for restricted values of n, we provide here a construction for such codes that is valid for all n. For the rectangular, T>n_t case, we present two general techniques for building D-MG-optimal rectangular ST codes from their square counterparts. A byproduct of our results establishes that the D-MG tradeoff for all Tgesn_t is the same as that previously known to hold for Tgesn_t+n _r-1     

Fast Wavelength Switching Lasers Using Two-Section Slotted Fabry–PÉrot Structures

Fast wavelength switching of a two-section slotted Fabry–PÉrot laser structure is presented. The slot design enables operation at five discrete wavelength channels spaced by 10 nm by tuning one section of the device. These wavelengths operate with sidemode suppression ratio in excess of 35 dB, and switching times between these channels of approximately 1 ns are demonstrated.     

On the Stopping Redundancy of Reed–Muller Codes

The stopping redundancy of the code is an important parameter which arises from analyzing the performance of a linear code under iterative decoding on a binary erasure channel. In this paper, we will consider the stopping redundancy of Reed-Muller codes and related codes. Let R(lscr,m) be the Reed-Muller code of length 2^m and order lscr. Schwartz and Vardy gave a recursive construction of parity-check matrices for the Reed-Muller codes, and asked whether the number of rows in those parity-check matrices is the stopping redundancy of the codes. We prove that the stopping redundancy of R(m-2,m), which is also the extended Hamming code of length 2^m, is 2m-1 and thus show that the recursive bound is tight in this case. We prove that the stopping redundancy of the simplex code equals its redundancy. Several constructions of codes for which the stopping redundancy equals the redundancy are discussed. We prove an upper bound on the stopping redundancy of R(1,m). This bound is better than the known recursive bound and thus gives a negative answer to the question of Schwartz and Vardy     

压电型步进式精密直线驱动器的试验研究

利用压电陶瓷的逆压电效应,基于步进运动原理和误差补偿技术设计了一种高精度定位的大行程精密直线驱动器,制作了样机,进行了静态特性和幅频特性测试以及运动性能试验,给出了驱动器的移动速度与工作电压、频率之间的试验关系曲线.结果表明在计算机闭环控制下,驱动器能稳定地实现双向运动,在行程1 mm时,定位精度达士0.01 μm,有效驱动力达13.5 N.     

Coding for the Feedback Gel'fand–Pinsker Channel and the Feedforward Wyner–Ziv Source

We consider both channel coding and source coding, with perfect past feedback/feedforward, in the presence of side information. It is first observed that feedback does not increase the capacity of the Gel'fand-Pinsker channel, nor does feedforward improve the achievable rate-distortion performance in the Wyner-Ziv problem. We then focus on the Gaussian case showing that, as in the absence of side information, feedback/feedforward allows to efficiently attain the respective performance limits. In particular, we derive schemes via variations on that of Schalkwijk and Kailath. These variants, which are as simple as their origin and require no binning, are shown to achieve, respectively, the capacity of Costa's channel, and the Wyner-Ziv rate distortion function. Finally, we consider the finite-alphabet setting and derive schemes for both the channel and the source coding problems that attain the fundamental limits, using variations on schemes of Ahlswede and Ooi and Wornell, and of Martinian and Wornell, respectively     

关于压电致动器的动力学和致动作用力

从压电本构方程出发，将外加电信号处理为外界激励作用。在理论上给出了应用最广泛的矩形薄板压电致动器在激励作用下的动力学效应，同时给出了其致动作用力表达式，为以前的有关报道结果提供了严格的理论依据。根据结果不难具体分析这种压电致动器的动力学响应。     

Perfect Space–Time Block Codes

In this paper, we introduce the notion of perfect space-time block codes (STBCs). These codes have full-rate, full-diversity, nonvanishing constant minimum determinant for increasing spectral efficiency, uniform average transmitted energy per antenna and good shaping. We present algebraic constructions of perfect STBCs for 2, 3, 4, and 6 antennas     

Time-Interleaved Multirate Sigma–Delta Modulators

A time-interleaved (TI) implementation of multirate sigma-delta modulators (SDMs) is proposed. In multirate SDMs, the first integrator is clocked at a rate that is lower than that of the rest of the integrators. In the proposed architecture, each integrator clocked at a high rate is replaced by two parallel integrators operating in interleaved mode and clocked at the same low rate as the first one. The new architecture has several nice features. First, every integrator operates at the same low rate, which simplifies the clock circuitry when compared to the original multirate modulator. Second, there are no delayed cross paths, which is typical of TI-SDMs. Third, no high-rate sample-and-hold at the input of a TI-SDM is required. Finally, as time interleaving is not applied to the first integrator, the proposed modulator is robust against circuit mismatches, unlike other TI architectures. The same strategy can be applied to continuous time (CT) modulators. To the authors' knowledge, this is the first TI-CT-SDM ever reported     

On Space–Time Trellis Codes Achieving Optimal Diversity Multiplexing Tradeoff

Multiple antennas can be used for increasing the amount of diversity (diversity gain) or increasing the data rate (the number of degrees of freedom or spatial multiplexing gain) in wireless communication. As quantified by Zheng and Tse, given a multiple-input-multiple-output (MIMO) channel, both gains can, in fact, be simultaneously obtained, but there is a fundamental tradeoff (called the Diversity-Multiplexing Gain (DM-G) tradeoff) between how much of each type of gain, any coding scheme can extract. Space-time codes (STCs) can be employed to make use of these advantages offered by multiple antennas. Space-Time Trellis Codes (STTCs) are known to have better bit error rate performance than Space-Time Block Codes (STBCs), but with a penalty in decoding complexity. Also, for STTCs, the frame length is assumed to be finite and hence zeros are forced towards the end of the frame (called the trailing zeros), inducing rate loss. In this correspondence, we derive an upper bound on the DM-G tradeoff of full-rate STTCs with nonvanishing determinant (NVD). Also, we show that the full-rate STTCs with NVD are optimal under the DM-G tradeoff for any number of transmit and receive antennas, neglecting the rate loss due to trailing zeros. Next, we give an explicit generalized full-rate STTC construction for any number of states of the trellis, which achieves the optimal DM-G tradeoff for any number of transmit and receive antennas, neglecting the rate loss due to trailing zeros     

On the Probability of Undetected Error for Overextended Reed–Solomon Codes

Upper and lower bounds on the weight distribution of overextended Reed-Solomon (OERS) codes are derived, from which tight upper and lower bounds on the probability of undetected error for OERS codes are obtained for q-ary symmetric channels     

压电陶瓷驱动器线性动态驱动电源的研制

根据压电陶瓷基本物理参数计算出压电驱动电源的最小基本性能参数,并利用高压运放研制了一种新型压电陶瓷驱动器的驱动电源,它具有高的输出电压范围(±200V),高输出电流(200mA,峰值电流300mA)。并且通过对反馈电路的波特图分析,讨论了自激震荡的产生和防止。在试验中通过对压电驱动器的正弦信号激励分析,表明驱动电源在带负载时有良好的输入跟随性能,能够满足复杂压电驱动器控制需要。     

压电微位移致动器的研制及其应用

文章是以光纤光栅传感系统中匹配FBG光纤解调为背景展开研究的,对压电陶瓷的材料特性、压电陶瓷驱动电源的软硬件设计和压电微位移致动在匹配FBG光纤解调中的应用等问题进行了探讨,开发了实用的压电微位移致动器。针对压电陶瓷的容性负载特性,提出了驱动电源的设计方案,完成了驱动电源软硬件设计,构建了直流稳压电路、PA78组成的混合放大电路。实验表明,所研制的压电微位移致动器具有良好性能,可应用于光纤光栅传感系统的匹配FBG光纤解调中。     

Optimization of Spectrum-Sliced ASE Source for Injection-Locking a Fabry–PÉrot Laser Diode

We experimentally study the impact of filter bandwidth of a spectrum-sliced amplified spontaneous emission (ASE) source on the injection-locking of a Fabry–PÉrot laser diode (FPLD) for passive optical network application. Optimal bandwidth of a spectrum-sliced ASE source was found in terms of receiver sensitivity after transmission. We also investigate the impact of intensity noise (IN) of the spectrum-sliced ASE source and its suppression for a wavelength-locked FPLD using a semiconductor optical amplifier. Experiment results show that the output performance of a wavelength-locked FPLD is improved by IN suppression.     

Zero-Error Source–Channel Coding With Side Information

This correspondence presents a novel application of the theta function defined by Lovasz. The problem of coding for transmission of a source through a channel without error when the receiver has side information about the source is analyzed. Using properties of the Lovasz theta function, it is shown that separate source and channel coding is asymptotically suboptimal in general. By contrast, in the case of vanishingly small probability of error, separate source and channel coding is known to be asymptotically optimal. For the zero-error case, it is further shown that the joint coding gain can in fact be unbounded. Since separate coding simplifies code design and use, conditions on sources and channels for the optimality of separate coding are also derived     

A New Planar InGaAs–InAlAs Avalanche Photodiode

We discuss a new simple InGaAs–InAlAs avalanche photodiode (APD) with a planar buried multiplication region. Some of the advantages compared to standard APDs are as follows: 1) The thickness of the avalanche and the charge control regions are accurately controlled by molecular beam epitaxy growth in contrast to the standard diffusion process; 2) InAlAs is the multiplication material (avalanching faster electrons) instead of InP (avalanching slower holes); 3) InAlAs avalanche gain has a lower noise figure than that for InP; 4) a guard ring is not required; 5) fabrication is as simple as that for a p-i-n detector; 6)the APD has high wafer uniformity, and high reproducibility; 7)the InAlAs breakdown voltage is lower than InP, and its variation with temperature is three times lower than that for InP; 8) excellent aging and reliability including Telcordia GR-468 qualification for die and modules; 9) high gain-bandwidth product as high as 150 GHz; and 10) high long-range (LR-2) bit-error-rate$10^-12$receiver sensitivity of$-$29.0 dBm at 10 Gb/s,$-$28.1 at 10.7Gb/s, and$-$27.1 dBm at 12.5 Gb/s.     

Multiple Virtual Private Networks Over Passive Optical Networks Using RF Subcarrier Multiplexing and Fabry–PÉrot Laser Diodes

An optical layer solution for implementing multiple virtual private networking capabilities over a passive optical network using subcarrier multiplexed (SCM) transmission is proposed and experimentally demonstrated with 60-Mb/s data multiplexed with two radio-frequency subcarriers. The transmission of the SCM data is carried out using Fabry–PÉrot laser diodes. Experimental results and theoretical analysis show that our technique can potentially support high data rate traffic from a large number of simultaneous virtual private networks with minimal penalty resulting from optical beat interference.     

压电执行器非线性控制方法研究进展

压电执行器在微驱动和微定位领域应用广泛,但压电执行器在输入电压和输出位移间存在着迟滞非线性。非线性的存在使压电执行器定位精度降低,动态响应速度变慢,是其工程上进一步应用的主要障碍。减小和消除迟滞非线性成为实现高精度控制的关键。总结了近年来国内外在减小和消除压电执行器迟滞非线性方面上的研究工作,并指出当今研究的热点及未来研究的方向。