Discrete time robust detection of stochastic signals in non-Gaussian contaminated noise

For many applications in signal detection, imprecise knowledge of the underlying noise process often makes desirable the employment of a robust detector. In this paper we consider the discrete time detection of stochastic signals in white noise, where the univariate noise density is known perfectly only on an interval about the origin. We present a method to enhance the asymptotic performance of the detector by exploiting this knowledge, and at the same time preserve robustness properties of the detector to the remaining inexact knowledge of the univariate noise density via a saddlepoint condition. We then provide examples to show that improved performance is indeed obtained.     

Resolving information asymmetries in financing new product development: The case of reward-based crowdfunding

Reward-based crowdfunding has evolved as a significant alternative source of financing for new product development over the past years. Unlike traditional investors, reward-based crowdfunding investors financing the production process are essentially consumers pre-ordering the product. Since financing takes place prior to production, this context is prone to information asymmetries. Consumers financing new product development have incomplete information regarding the quality of the product they have pre-ordered and the reward they will receive for their early support. We draw on information economics to examine how signals, such as price commitment, discount, and reward classes, play a role in conveying information about product quality and the financial reward backers receive for pre-ordering the product. Our empirical analysis covers detailed hand-collected information on a random sample of 1835 Kickstarter campaigns. We find that signaling information regarding the future retail price enhances campaign performance. Moreover, when the different signals originate from the same source and overlap in the information they convey, the more informative signals partially offset the effect of the less informative signals.     

An exact formula for the half-plane pull-in range of a PLL

A second-order phase-lock loop (PLL) that is based on a triangular-characteristic phase detector and imperfect-integrator loop filter is found in many applications where simplicity and economics are major considerations. For many of these applications, digital-logic-compatible reference and VCO signals are used, an exclusive-OR gate implements the phase detector, and the loop filter is constructed from passive components. When designing these loops, the half-plane pull-in range Ω₂ is of interest. Until now, this important loop parameter could only be calculated by using a computer-based technique that numerically integrated the nonlinear differential equation that describes the PLL model. This requirement/limitation is removed here by the development of an exact closed-form formula for Ω₂, the main contribution of this paper. More generally, the value of Ω₂ is dependent on the PLL phase detector characteristic that is used, be it triangular, sinusoidal, or something else. With regard to the value of Ω₂ produced, a comparison is given of two PLLs, both described by the same linear model so that the comparison is meaningful. The first PLL is based on a triangular-characteristic phase detector; the second loop is based on a sinusoidal phase detector.     

Random-valued impulse noise removal based on component-wise noise detector with auto-tuning function and vector median interpolation

We present a novel switching median filter for the removal of random-valued impulse noise on a color image. The present filter consists of a new noise detector with auto-tuning function, and a vector type noise remover avoiding the occurrence of the color artifacts after the noise removal. The detector has a parameter, which is automatically tuned only by using the distribution information of the noise signal without any training signals, and detects the pixel corrupted by the random-valued impulse noise with the parameter. And the detector operates in each channel independently. As a noise remover, the ordinary vector median filter is employed to interpolate only the pixel which is detected as noisy one by the detector. Through the experiments using some digital color images, the validity and the effectiveness of the present method are verified.     

A data-driven covert attack strategy in the closed-loop cyber-physical systems

In this paper, a data-driven covert attack strategy is proposed for a class of closed-loop cyber-physical systems. Without the parameters of the system plant and the nominal controller, the attacker can only use the intercepted input and output data of the nominal system. The injected input attack signals are designed based on the subspace predictive control method, which can deviate the real outputs to the expected attack references in a future time horizon. Meanwhile, by injecting the designed output attack signals for compensation, the attack cannot be detected by the anomaly detector. The simulation results of an irrigation canal system illustrate the effect of the proposed strategy with satisfactory performances.     

Fault detection of discrete-time delay Markovian jump systems with delay term modes partially available

This paper focuses on the fault detection problem for a class of discrete-time delay Markovian jump systems with delay term modes partially available. A crucial but general hypothesis considered here is there is a suitable and effective detector to provide a measurement signal of operation mode of delay term. The fault detection filter used as the residual generator could depend on the original system operation mode or the signal emitted from detector. Via minimizing the error between the residual and fault signal, the problem of fault detection and isolation (FDI) is converted into an H_∞ filtering problem and closely related to a probability representing the degree of dependence between the original and measurable signals. An improved Lyapunov function depending on such two operation modes is exploited to study the corresponding problems. Sufficient conditions for the existence of the desired FDI filter are presented in terms of LMIs. When such a probability is uncertain or partially unknown, similar problems are also considered. A practical example is used to demonstrate the effectiveness and superiority of the proposed methods.     

降低“违约责任保证金”有利于中小卖家吗?——基于信号传递理论的博弈分析

运用信号传递理论,分析了不同类型的卖家发送不同类型的保障标记信号的均衡:当传递信号成本无差异时,不同类型的卖家混同于不发送信号的精炼贝叶斯均衡;只有传递信号成本在不同类型的卖家之间有差异时,才会产生唯一的分离均衡,即高质量卖家选择发送信号,低质量卖家不发送信号,卖家的类型显示能够有效地解决网络交易中的信息不对称问题。     

Detection of replay attacks in cyber-physical systems using a frequency-based signature

This paper proposes a frequency-based approach for the detection of replay attacks affecting cyber-physical systems (CPS). In particular, the method employs a sinusoidal signal with a time-varying frequency (authentication signal) into the closed-loop system and checks whether the time profile of the frequency components in the output signal are compatible with the authentication signal or not. In order to carry out this target, the couplings between inputs and outputs are eliminated using a dynamic decoupling technique based on vector fitting. In this way, a signature introduced on a specific input channel will affect only the output that is selected to be associated with that input, which is a property that can be exploited to determine which channels are being affected. A bank of band-pass filters is used to generate signals whose energies can be compared to reconstruct an estimation of the time-varying frequency profile. By matching the known frequency profile with its estimation, the detector can provide the information about whether a replay attack is being carried out or not. The design of the signal generator and the detector are thoroughly discussed, and an example based on a quadruple-tank process is used to show the application and effectiveness of the proposed method.     

Asymptotic memoryless detection of random signals in dependent noise

Design of detectors for strong mixing signals in strong mixing noise is considered, where a large degree of dependency may occur between the signal and noise. Under the criterion of asymptotic relative efficiency, it is shown that this design reduces to determining the solution of an integral equation, where only knowledge of the second order statistics of the randon processes involved is required. In particular, if the signal is independent of the noise and has nonzero mean, the optimal detector is the same as in the known constant signal case. It is also shown that it is possible to delete several regularity conditions which may be difficult to check in practice in the slightly more restrictive case where the maximal correlation coefficients of the signal and noise tend to zero.     

Approximation based on orthogonal and almost orthogonal functions

In this paper, we define a class of almost orthogonal rational functions of Legendre type in a new manner. Relations of these functions with classical exponentional functions orthogonal over interval (0, ∞), as well as classical polynomials orthogonal over (0, 1) are explained. Defining relations of these functions can be used for designing almost orthogonal filters. These filters are generators of orthogonal signals and can be successfully applied in finding the best signal approximation in the sense of the mean square error. The filters orthogonal property enables building of physical (in this case electrical) models of dynamical systems (the sources of signals to be approximated) either with less components for the same model accuracy or higher accuracy for the same number of components than the other known models. New filters represent further improvement of previously designed filters, by the same authors, in the sense of simplicity, higher accuracy, lesser approximation time and even a possibility to approximate signals generated by systems with built-in imperfections. Series of experiments were performed to analyze the dependence of approximation accuracy and the number of filters sections.     

一种基于多通道分解的图像测试信号设计方法

HVS中多通道分解模型用于度量误差图像空间尺寸的视觉感受,为了降低主观评价实验方法的条件要求,建立了一种基于多通道分解的图像测试信号设计方法。该方法通过控制白噪声在频域存在的区间,即白噪声经正交变换、掩膜量化矩阵,产生信噪比相同且空间尺寸不同的测试图像信号。分析和实验表明,多通道分解测试图像信号产生一对与高频和低频对应的误差图像,其信噪比基本相等但其空间尺寸的视觉感受不同,有利于考察与视觉感知相吻合的图像评价方法。     

A radar detector using quantized envelope samples

The detection of a sequence of echo pulses with random carrier phase is an important problem in radar. It is well known that, to a first approximation, the optimum receiver is a quadratic detector for small signal-to-noise ratios and is a linear detector for large signal-to-noise ratios. In this paper, a detector based on scaling and rounding envelope samples into digital words of only a few bits is presented and analyzed. This detector is essentially a generalization of a suboptimum detector known as a binary detector which performs postdetection integration by digital counting and is particularly useful in automatic detection systems. The asymptotic relative efficiencies of this detector relative to the quadratic detector and the linear detector are obtained. Also, non-asymptotic performance comparisons based on relative efficiency and on probability of detection are made. It is shown that this detector is more efficient than the other two detectors in most signal-to-noise ratio ranges. In addition, this detector is applicable when the noise environment is somewhat different from Gaussian.     

具有确定逼近域的自适应模糊DSC控制

针对一类不确定非线性时滞系统,提出了一种具有确定逼近域的自适应模糊控制器的设计方案。在动态面控制（DSC）的基础上,通过时滞代换技巧,使得自适应模糊逼近器的输入为参考信号,从而可以明确定义逼近域,同时可以处理系统中完全未知的时滞信号。基于Lyapunov-Krasovskii范函,证明闭环系统所有信号为半全局一致有界的,并且跟踪误差可以收敛到原点附件的一个小邻域内。仿真结果进一步说明了该方法的有效性。     

An improved lock detector for phase-locked communication receivers

A quadrature lock detector is incorporated in almost all coherent radio communication receivers. This commonly-used receiver subsystem is comprised of a quadrature phase detector that drives a low-pass filter, the output of which is subjected to a user-specified threshold to make a lock/unlock decision. Signal acquisition and phase lock are declared if an above threshold condition is observed. Unfortunately, this method of lock detection may yield a positive lock indication when the receiver is false locked; i.e., a classical quadrature lock detector may generate a false-positive lock indication. This tendency to produce an incorrect lock indication can be reduced significantly by using the new lock detector algorithm that is described here. Compared to the classical quadrature lock detector, the new lock detector is better able to differentiate between true phase lock and anomalous false lock. The classical quadrature lock detector is a simple, first-order approximation of the new lock detector algorithm. That is, the new lock detector algorithm consists of a classical quadrature detector that is augmented by a correction term.     

煤矿中的信道和信号安全的设计

鉴于当前的通信差、干扰强的煤矿网络信息传输通道,为了更好的实现各种信号安全稳定的传输,以计算机传输协议和煤矿成熟的光纤网为基础,实现监控服务器使用组态软件对井下下位机进行监控并且实现数据的传输,建立起一套完整的信号传输信道。主要是以光纤网为核心,通过计算机组态软件的UDP信号传输协议,并以矿用通信屏蔽电缆为传输介质来保证信号的安全稳定的传输,并以此实现了对下位机的监控、信号采集及远程控制。     

基于AT89C51和弦音乐播放器设计

音乐是由音符、节拍组成的。每个音符有固定的频率。若单片机定时器产生与音符相同的频率,同时采用延控制节拍,就能播放音乐。利用AT89C51单片机的P1.0、P1.1引脚同时输出音频信号,产生和弦音乐。     

基于仿射变换的双波段红外图像配准算法研究

图像配准是图像融合技术中的首要环节,只有经过配准的图像才能够进行融合。虽然双波段红外探测器探测的是同一场景,但是由于光学系统的构造产生了两幅图像,而两幅图像之间却存在了几何位置上的差异,所以在本文中提出一种配准方法。通过点检测方法获取图像的特征点,然后再选取其中两组较为明显的特征点组,再根据仿射变换关系式,确定其中的模型参数,并且对图像进行配准。     

供应商参与对制造商产品创新模式影响的分析

阐明了制造商产品创新的分类和供应商参与的优势,并且基于供应商参与产品创新的阶段将其划分为供应商前期参与和供应商后期参与两种类型,分析了不同供应商参与阶段对制造商产品创新的影响.结果表明,供应商前期参与有利于制造商突变式产品创新的实现,而供应商的后期参与则有利于制造商渐进式产品创新的实现.     

A Detection Scheme for Dependent Noise Processes

In this paper the problem of memoryless discrete time detection of a constant signal in additive φ-mixing noise is considered. The fidelity criterion is taken to be the asymptotic relative efficiency. The optimal detector nonlinearity is approximated by a polynomial, and the statistical knowledge required for the design of the detector is the family of joint moments of the noise, resulting in a very simple design procedure for the detector. It is shown that the performance of this detector can be made arbitrarily close to that of the optimal memoryless detector for a large class of noises.     

Innovation management for an industrial product

Successful innovation in industrial products can be carried out by means of a carefully planned innovation process. This paper describes such a process carried out in a company that faced heavy financial losses due to an obsolete product mix.The total process took about two years, during which a new industrial product was acquired, the organization was adapted, the market introduction was started, and financial resources from outside the company were successfully obtained.The innovation process can be divided in different steps: objective formulation, potential product search, licence search or product development, negotiation, and finally market introduction.The first two steps were carried out in order to direct product development and licence search efforts as effectively as possible. As a result potential product licences were traced, on which none or only little furtner product development was needed. All this was fairly simple and took only a few months.During the negotiation (the next step), a very strong internal promotion of the most promising potential product licence was carried out at all decision levels, whilst at the same time the acquisition of this product licence was negotiated. Altogether this period lasted more than one year.Finally, a licence for a new product was acquired, after which the market introduction was started, resulting in a multimillion guiders turnover within less than two years after the start of the innovation process.The success of this product innovation resulted from careful planning and management of the whole process by an innovation manager, in cooperation with a task force, and from the considerable effort spent on internal company promotion. At the same time, pulling the selected new product through problem areas, and turning it into a commercial success, was the most creative part of this product innovation process.