Information Sharing as a Coordination Mechanism for Reducing the Bullwhip Effect in a Supply Chain

The bullwhip effect is an amplification of the variability of the orders placed by companies in a supply chain. This variability reduces the efficiency of supply chains, since it incurs costs due to higher inventory levels and supply chain agility reduction. Eliminating the bullwhip effect is surely simple; every company just has to order following the market demand, i.e., each company should use a lot-for-lot type of ordering policy. However, many reasons, such as inventory management, lot-sizing, and market, supply, or operation uncertainties, motivate companies not to use this strategy. Therefore, the bullwhip effect cannot be totally eliminated. However, it can be reduced by information sharing, which is the form of collaboration considered in this paper. More precisely, we study how to separate demand into original demand and adjustments. We describe two principles explaining how to use the shared information to reduce the amplification of order variability induced by lead times, which we propose as a cause of the effect. Simulations confirm the value of these two principles with regard to costs and customer service levels     

Oscillation modes of laser diode pumped hybrid bistable system withlarge delay and application to dynamical memory

An electrooptical bistable system with a very large delay was constructed, and self-oscillation phenomena were investigated. Many multistable self-oscillation modes were observed, including second-order bifurcations of the 265th harmonic. The dynamical memory function was demonstrated by locking second order bifurcated modes to external clock oscillations and performing WRITE and READ of binary data sequences in the waveforms of the bifurcated modes. The nonlinear bifurcation phenomena in this system are applicable for large-capacity memory and signal processing. Spurious preferential excitation of particular harmonic modes was related to the fine structure in the transfer spectrum of the open loop associated with spurious resonances in the electrooptical modulator used as a nonlinear element     

Nonlinear amplifier optimal characteristics shaping for self-oscillating systems of vibrofrequency densometers

It is considered methods of nonlinear amplifier optimal characteristics shaping for self-oscillating systems of vibrofrequency densometers. This method allows to decrease essentially non-stability of self-oscillation mechanical resonators in comparison with “saturation” type characteristic of and analysis of high harmonics at the output of nonlinear amplifier on self-oscillation frequency.     

New nonlinear design tools for self-oscillating mixers

New nonlinear design tools for self-oscillating mixers are presented here, with the aim to increase the designer's control over their behavior. The new tools enable fixing the self-oscillation frequency and selecting the optimum self-oscillation amplitude for maximum conversion gain. They can also be applied for the optimized design of harmonic self-oscillating mixers. Using bifurcation-theory concepts, it has been possible to increase the input-power range with self-oscillating-mixer operation. A self-oscillating mixer with 5.5 GHz input frequency has been designed and simulated obtaining very good agreement with the experimental results     

Product attribute bullwhip in the technology planning process and a methodology to reduce it

This paper considers the upstream flow of product attribute forecast information often used to drive the technology planning process. It is noted that, while downstream customers are willing to pay for improvements in key product attributes, they do not always provide accurate and timely product attribute forecasts to upstream suppliers. As a result of this increasing distortion of product attribute demand as information flows upstream, upstream suppliers often either fail to develop technology that will be needed in the marketplace or develop technology that ultimately is unused. This is shown to be a strategic, technology planning analog to the tactical, order decision problem of order quantity bullwhip observed in the field of supply chain management. As such, we define the technology planning problem under consideration here as "product attribute bullwhip." Based on solutions employed to address order quantity bullwhip in supply chain management, we propose a methodology to reduce product attribute bullwhip by comparing product attribute information obtained directly from the end user with that which flows upstream through the supply chain. To illustrate this effect, we apply the proposed methodology to an example from the wireless communication industry by comparing trends in the perceived value of cellular telephone handset face area with trends in the perceived value of face area observed at the component level of the supply chain.     

Further Motivation for Continuous Improvement in Just-In-Time Logistics

In the supply chain literature, little work has been done on modeling the propagation pattern of quality defects in supply chains. We quantitatively model a defect bullwhip effect in supply chains that can be addressed logistically by reducing time intervals between product deliveries. We explicitly consider the cause and effect of this defect bullwhip effect and demonstrate analytically that there is a strong incentive for practitioners to continuously reduce shipment size. We also consider production characteristics such as the frequency of supplier failure and stringency of the buyer's inspection process. Implications for managers are suggested.     

Simulation of field bifurcations in electrodynamic structures containing a nonlinear semiconductor medium exhibiting instability

A strip-slot guiding structure (GS) containing a distributed semiconductor inclusion with a negative differential conductivity is considered. Instabilities and nonlinear effects observed during propagation of electromagnetic waves in such a structure are investigated via numerical analysis of branching points of solutions to the nonlinear Maxwell equations. The method of universal autonomous blocks with Floquet channels is applied to solve the 3D problem of diffraction of electromagnetic waves by a nonlinear semiconductor irregularity in a strip-slot GS. The solutions obtained describe frequency multiplication and generation of the GS fundamental mode near a branching point. The generation process is described as a function of the incident-wave amplitude. The bifurcation points of the nonlinear Maxwell operator are found numerically with allowance for bounding geometries. These points specify the self-oscillation frequencies in planar Gunn effect diodes in a strip-slot GS.     

Exploiting low complex digital predistortion to improve wideband nonlinear satellite downlinks

With the increasing demand for higher data rate, increasing throughput requires wider bandwidth. Due to the nonlinear effect of power amplifier, severe nonlinear distortion effects will appear onboard satellite. Digital predistortion (DPD) scheme is usually employed to compensate for the distortions and memory effects introduced by traveling wave tube amplifier (TWTA) and output multiplexing filter (OMUX). In conventional predistorter, the signal loss of band‐limited feedback signal output through OMUX is usually ignored. Actually, it will affect the linear effect of TWTA. In order to solve the problem as to improve wideband nonlinear satellite downlink, this paper introduces a novel spectral extrapolation method based on deep neural network to recover the band‐limited feedback signal. On this basis, an advanced orthogonal matching pursuit algorithm is adopted in the nonlinear TWTA model construction to further reduce the DPD complexity. The proposed setup effectively compensates the distortions and is well suited for systems that generate data bits on satellites.     

Oscillation mechanism of avalanche region of the IMPATT diode

The oscillation mechanism of the avalanching region of the IMPATT diode is clarified by referring to the cavity resonator and feedback theories. When the avalanche takes place, the microwave electric field and the particle currents grow spacially. But the spacial growth does not directly mean the self-oscillation, as there exists the reflection loss at the region edges. When the gain due to the avalanche exceeds the reflection loss, the self-oscillation can take place. The preceding phenomena are analyzed by the conception of the open-loop transfer gain in feedback theory.     

Partial likelihood for signal processing

We present partial likelihood (PL) as an effective means for developing nonlinear techniques for signal processing. Posing signal processing problems in a likelihood setting provides a number of advantages, such as allowing the use of powerful tools in statistics and easy incorporation of model order/complexity selection into the problem by use of appropriate information-theoretic criteria. However, likelihood formulations in most time series applications require a mechanism to discount the dependence structure of the data. We address how PL bypasses this requirement and note that it might coincide with conditional likelihood in a number of cases. We show that PL theory can also be used to establish the fundamental information-theoretic connection, to show the equivalence of likelihood maximization and relative entropy minimization without making the assumption of independent observations, which is an unrealistic assumption for most signal processing applications. We show that this equivalence is true for the basic class of probability models (the exponential family), which includes many important structures that can be used as nonlinear filters. We conclude by giving examples of the application of PL theory.     

耳蜗模型的Volterra泛函分析

随着对语音信号处理的研究日益深入,研究听觉系统的机理显得越来越重要。本文建立了耳蜗的非线性运动方程及相应的状态空间方程,并首次利用Volterra泛函分析方法,获得了非线性耳蜗模型满足任意精度的频域解析解。还证明了,文献[1]给出的分析方法是本文分析方法的一种特例,说明了本文的分析方法具有一般性。     

Self and excited oscillations in a circuit composed of a non-linear element and a delay line

This paper presents an analysis of pulse circuits composed of a tunnel diode and a transmission line. The method employed, analysis in the v-i plane, is applied to the self-oscillation mode as well as to that of the one-shot mode. Effects of load and source (bias) impedance, linear and non-linear, are investigated. The analysis of nonlinear biasing leads to configurations which present an improved triggering ability, shorter recovery time and less sensitivity to bias voltage variations     

基于四波混频的元素超精细光谱研究

提出将简并四波混频激光光谱分析技术用于物质超精细结构检测，加之量子光学理论计算的新方法测量同位素含量。即由实验现象确定出自激振荡频率后，在三阶极化率的基础上，通过量子光学梯形三能级系统的计算，得到了简并四波混频双光子共振吸收下，三阶极化率与原子数密度的关系。     

非线性盲辨识补偿处理的宽带超外差接收机

提出了一种基于非线性盲辨识补偿处理的新型宽带超外差接收机。在时域,分别提取接收前端输出信号的大信号成分（大功率频率分量）和小信号成分（主要包含非线性失真分量）,并以大信号的非线性模型与小信号的残差平方和最小作为其非线性行为模型参数的辨识准则,利用加权迭代改善算法实现模型参数的自适应提取和更新,最后在线实时地对接收机输出信号进行数字域后补偿处理。实测结果表明,在同时多信号接收的情况下,该非线性盲辨识补偿处理可将整机的无杂散失真动态范围(SFDR)提高超过20dB,极大地提高了在强干扰存在时对微弱信号接收与检测的能力。      

基于LMS算法的自适应直放站回波消除算法研究

针对无线同频直放站转发器输出的大功率射频信号可使整个系统会自激这一问题,提出了基于LMS的回波消除系统算法。如果不用回波消除,会造成增益不可增大以及系统容易自激,若整个系统自激,可造成系统不稳定,进而可能损坏末级放大器。采用回波抑制技术后,可以有效改善信号的回波对系统的影响,提高系统的稳定性。仿真结果表明该算法可有效地抑制回波。     

应用大数据分析的电网业务需求规划管理平台

为提升电力负荷预测能力和电网业务需求信息处理效果,设计应用大数据分析的电网业务需求规划管理平台。以大数据平台为基础,通过传输机制完成电网业务需求在平台内横向集成以及管理层面的纵向贯通;平台工作层的典型业务分析模块负责各类业务需求数据的综合查找、汇总分析、重点工程的走廊展示等相关信息分析;规划信息管理模块通过电网业务功能管理和规划指标管理,完成电网基本情况、电网建设情况、用电情况等内容存储以及电网业务需求分析。实验结果显示,所设计平台的电力负荷预测能力强、信息覆盖度高、信息处理效果好。     

On the clinotron effect in a backward-wave tube

The results of a theoretical study of the clinotron effect in a clinotron model, which takes into account static electron trajectories in the focusing magnetic field and the initial spacing between the lower beam boundary and the surface of the slow-wave structure, are presented. Physical processes of interaction between a thick electron beam with transverse dimensions comparable with the length of the slow wave and the RF field at its oblique incidence onto the structure are considered. It is demonstrated that, as the current is increased from the starting to the working value, a beam tilt is necessary to reduce the nonlinear effects of interaction between the beam and the RF field and prevent the complex self-oscillation dynamics in the clinotron; in the small amplitude mode (start), the beam tilt is related to optimization of the beam supply into the interaction space, which ensures the minimum starting current. In addition, it is shown that, in the presence of the initial spacing between the beam and structure, the reduced clinotron efficiency η/С increases and, at the optimum tilt angle, is no less than the normalized efficiency of classical backward-wave tubes with a thin electron beam.     

The kernel recursive least-squares algorithm

We present a nonlinear version of the recursive least squares (RLS) algorithm. Our algorithm performs linear regression in a high-dimensional feature space induced by a Mercer kernel and can therefore be used to recursively construct minimum mean-squared-error solutions to nonlinear least-squares problems that are frequently encountered in signal processing applications. In order to regularize solutions and keep the complexity of the algorithm bounded, we use a sequential sparsification process that admits into the kernel representation a new input sample only if its feature space image cannot be sufficiently well approximated by combining the images of previously admitted samples. This sparsification procedure allows the algorithm to operate online, often in real time. We analyze the behavior of the algorithm, compare its scaling properties to those of support vector machines, and demonstrate its utility in solving two signal processing problems-time-series prediction and channel equalization.     

Theory of degenerate four-wave mixing in saturable absorbing media with the inclusion of pump propagation effects

The phase-conjugate reflectivity attainable by degenerate four-wave mixing in an idealized saturable absorbing medium is calculated for arbitrary values of the laser intensity, laser frequency, and absorption path-length of the nonlinear medium. The influence of pump-wave absorption, including saturation and standing-wave effects, is included in the theory. The treatment is based on an analytic expression for the intensity distribution of the counterpropagating waves. The theoretical predictions differ substantially from those based on theories that ignore pump absorption effects. The results of the present calculation are used to predict the minimum laser intensity, absorption path-length, and detuning required to obtain unit reflectivity and self-oscillation.     

Adaptive pre- and post-compensation of nonlinear distortions for high-level data Modulations

In this letter, we show how different signal processing techniques can be combined to optimize the performance of a typical wideband nonlinear satellite link with spectrally efficient high-level modulation techniques. In particular, we follow two concurrent approaches: on one side, we pursue signal optimization in the form of special amplitude and phase shift keying (APSK) constellations to reduce the effect of nonlinear distortions, while on the other, we analyze the feasibility of adaptive data predistortion (DP) at the transmitter and adaptive nonlinear equalization (NLE) at the receiver. We demonstrate that the use of such optimized constellations relieves the complexity of the nonlinearity compensation techniques, and we also show that by clever adoption of these techniques the sensitivity to nonlinear distortion of both uncoded and turbo coded quadrature amplitude modulation and APSK constellations is greatly reduced.