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The accuracy and operational stability of a turntable system can be reduced by the backlash problem that occurs in the reducer’s gear transmission system. To solve this problem, this work proposes a scheme in which two motors are used to eliminate the effects of backlash through a linearization process. By calculating and outputting two independent torques synchronously from the two servo motors to the system output shaft’s gears, a nonlinear system with backlash can be transformed into a linear system without backlash, thus making the resulting system easy to control. Experiments verify that the system will remain stable after the movement of the output shaft stops.

Micro Unmanned Aerial Vehicles (MUAVs), including consumer-grade ones, have been frequently threatening urban low-altitude security in recent years. This article analyses the necessity to develop specialized technology of anti-MUAVs. Then the article proposes an engineering scheme of a Smart Weapon Capturing MUAVs (SWCM) in an automatic and soft-killing way. The scheme includes a ground subsystem and an aircraft subsystem. The ground subsystem mainly includes optical sighting equipment and handheld launch control device. The aircraft subsystem includes guidance, control, structure, aerodynamic, etc. The design principle of this scheme embodies the technical characteristics of autonomy, high efficiency, low cost and civil-military dual use. The validity of the smart weapon system design is proved by numerical simulations and experiments, and its application is also prospected.

The failure of the motor or controller of a motor servo system could lead to terrible casualties and property loss in fields such as aviation and transportation. Current research mainly focuses on the algorithm for fault-tolerant control and the topological structure of hardware. Such approaches may reduce the system frequency through the use of a complex algorithm or increase the system cost through the use of special components. The present paper proposes and tests a multi-redundant, permanent-magnet synchronous motor. Through the parallel connection of multiple independent windings and a supporting control method that controls each redundancy separately, the system continues to run even when the winding or controller of one redundancy suffers an open-circuit or short-circuit fault. The system controller is easy to build and minimize without special components and does not require additional algorithms.

Sparsity property has long been exploited to improve the performance of least mean square (LMS) based identification of sparse systems, in the form of l_0-norm or l_1-norm constraint. However, there is a lack of theoretical investigations regarding the optimum norm constraint for specific system with different sparsity. This paper presents an approach by seeking the tradeoff between the sparsity exploitation effect of norm constraint and the estimation bias it produces, from which a novel algorithm is derived to modify the cost function of classic LMS algorithm with a non-uniform norm (p-norm like) penalty. This modification is equivalent to impose a sequence of l_0-norm or l_1-norm zero attraction elements on the iteration according to the relative value of each filter coefficient among all the entries. The superiorities of the proposed method including improved convergence rate as well as better tolerance upon different sparsity are demonstrated by numerical simulations. [ABSTRACT FROM PUBLISHER]

This paper proposes an architecture for routing Internet protocol (IP) packets directly on optical networks. The use of label switching is assumed in the IP routers, while a new routing architecture is introduced to transport IP packets across an optical backbone network. The architecture is based on a two-tier multiplexing approach with wavelength division multiplexing (WDM) addressing the number of regional exchanges and time-division switching communicating among the hubs. Such an architecture not only has the advantages of simple network management and high efficiency with low latency; it also is scalable by addition of regional exchanges, hubs, and fibers [ABSTRACT FROM PUBLISHER]

We present here a supervisory management scheme and two complete lightpath restoration algorithms based on integer linear programming. The supervisory management uses a hierarchical approach with a network manager supervising all node managers, each of which monitors the health status of all network components and subsystems on that link. Extension to the existing CCS7 protocol is proposed to include the surveillance information in the signaling network. For the restoration algorithms, their performances are compared in three networks commonly cited for testing purposes. In general, the source-based restoration algorithm performs better than that based on the link-based restoration algorithm, but requires much longer computation time. Also, the former restoration algorithm ensures the fairness in satisfying lightpath demands within the network [ABSTRACT FROM PUBLISHER]

A close-form analytical expression is obtained for the performance study of a bit-rate limiter (BRL). Both bit-error rate (BER) and power penalty are derived for different BRL modulation signals and modulation formats using a random signal model. We also present ways to improve the BRL performance and to eliminate the BRL-induced crosstalk, by using an optimal BRL modulation index and a specific BRL modulation signal, respectively. The analytical expression is found to match well with the experimental measurements [ABSTRACT FROM PUBLISHER]

The usable bandwidth of an optical filter is not only limited by signal attenuation, but also the waveform distortion when optical signal is passed through the edge of the filter. The waveform distortion due to optical filtering is investigated with the assumption of linearly chirped Gaussian pulse. While the first-order optical filtering (linear slope in dB) does not induce waveform distortion, second-order optical filtering induces pulse distortion similar to fiber dispersion [ABSTRACT FROM PUBLISHER]

Extraordinary optical transmission (EOT) of metallic film perforated by a periodic array of subwavelength holes is significant in photoelectric devices. In this paper, a multilayer structure with periodic nanoslit arrays is proposed to achieve broadband EOT in infrared. The optical transmission properties of such structure are simulated through the finite-element method. Greatly enhanced transmissions over a broad spectral range are observed in near-infrared wavelengths, and many enhanced electric fields occur in the narrower slit. In addition, the effects of structural parameters on transmission properties are also investigated. All these findings could guide the design of devices with broadband-enhanced transmission and high electric-field concentration.

In this letter, we present a simple and effective interferometric approach for waveform restoration in a semiconductor optical amplifier (SOA) using a fiber loop mirror. Pattern-dependent distortion caused by gain dynamics of the SOA can be compensated. With our scheme, an enhanced input power dynamic range of 7 dB was achieved. For data sequences with different pattern lengths, both significant waveform and extinction ratio improvement were obtained [ABSTRACT FROM PUBLISHER]

In this letter, we propose and experimentally demonstrate a novel supervisory scheme to monitor the working status of multiple optical amplifiers in a wavelength-division-multiplexing transmission link. An optical feedback loop with unique loop length is added around each inline optical amplifier to create monitoring signal at a common supervisory wavelength. By analyzing the RF spectra of the common supervisory wavelength at the receiver end, any failed optical amplifier in the transmission link can be identified [ABSTRACT FROM PUBLISHER]

The root-mean-squared bandwidth of spectral broadening induced by cross-phase modulation is derived analytically for a two-channel system consisting of a pump and probe channel. The pump channel is randomly modulated by binary data and the probe channel is a weak continuous-wave channel. The analytical expression is verified by experiments [ABSTRACT FROM PUBLISHER]

We propose and demonstrate a fault-tolerant WDM add-drop/branching unit for long-haul optical transmission systems. This unit not only can perform the necessary optical amplification and wavelength add-drop functions with the local network, but also provide the much needed fault identification and fault recovery features [ABSTRACT FROM PUBLISHER]

Used in optical networks, a reconfigurable and low-cost 2×2 optical cross-connect device based on fiber Bragg gratings and optical limiting amplifiers is investigated and demonstrated. The input dynamic range is over 20 dB for both crossing and passing channels. A small power penalty of 0.6-1.0 dB is found for a two-channel 2.5 Gb/s over a 100-km system demonstration [ABSTRACT FROM PUBLISHER]

We propose and experimentally demonstrate a new fiber-fault identification scheme for optically amplified branched networks. The scheme makes use of fiber Bragg gratings and an internally generated light source from erbium-doped fiber amplifiers through an optical feedback loop, and no additional dedicated monitoring source is required. The monitoring technique invokes both frequency and time domain by sweeping the wavelength of the monitoring source. By combining with a conventional optical time-domain reflectometer technique, exact location in fiber cut in branched network can be identified readily [ABSTRACT FROM PUBLISHER]