Estimating the distribution of a sum of independent lognormalrandom variables

Four methods that can be used to approximate the distribution function (DF) of a sum of independent lognormal random variables (RVs) are compared. The aim is to determine the best method to compute the DF considering both accuracy and computational effort. The investigation focuses on values of the dB spread, σ, valid for practical problems in wireless transmission (6 dB ⩽σ⩽12 dB). Contrary to some previous reports, our results show that the simpler Wilkinson's approach gives a more accurate estimate, in some cases of interest, than Schwartz and Yeh's (1982) approach     

平面设计方法在工业产品造型设计中的应用

平面设计通过Photostyle、AutoCAD、Animotor Pro、3D Studio等多种软件作为开发工具,用于平面广告、商标和品牌、出版物、广告牌、海报、标志和产品包装等产品的造型设计中。本文对3D Studio软件用于产品造型动画设计问题进行了深入研究,通过3D Studio软件来设计出动画逼真的产品造型,大大缩短了产品造型的设计周期。     

平面设计方法在工业产品造型设计中的应用

平面设计通过Photostyle、AutoCAD、Animotor Pro、3D Studio等多种软件作为开发工具,用于平面广告、商标和品牌、出版物、广告牌、海报、标志和产品包装等产品的造型设计中。本文对3D Studio软件用于产品造型动画设计问题进行了深入研究,通过3D Studio软件来设计出动画逼真的产品造型,大大缩短了产品造型的设计周期。     

Estimating dynamic power consumption for memristor-based CiM architecture

Nowadays, Computing-in-Memory (CiM) represents one of the most relevant solutions to deal with CMOS technological issues and several works have been proposed so far targeting front and back-end synthesis. However, a given CiM architecture can be synthesized depending on different parameters, leading to different implementations w.r.t. area, power consumption and performance. It is thus mandatory to have an evaluation framework to characterize the actual implementation depending on the above terms. This is even more important during the Design Exploration phase, in which many different implementations are explored to identify the best candidate w.r.t. the user requirements. In this work, we focus on the dynamic power consumption estimation of a given CiM implementation. Instead of resorting to a simulation-based power estimation, we propose an analytical approach that will dramatically speed up the estimation since no simulations are required. By comparing the proposed approach against the simulation-based method over a massive experimental campaign, we show that the accuracy of the estimation turns out to be very high.     

Estimating dynamic positioning errors of coordinate measuring machines

Modern industrial production requires fast and automated quality control using state-of-the-art surface metrology sensors embedded in fast high-precision measuring machines. In order to achieve both fast and precise positioning, active control systems with model-based compensation of dynamic positioning errors due to increased acceleration forces can be applied. However, these active control systems require an accurate estimate of the dynamic positioning errors of the tool-center-point (TCP) with respect to the precisely measured position of the drive axes. A novel optical camera sensor system with high subpixel precision based on multi-spot detection enables the direct measurement of the TCP position at a slower rate than the sampling time of the control system and with significant latency or dead-time. Based on a general yet simple deviation model with large model mismatch, three approaches to estimate the TCP position are presented and compared with simulation and test bench results of a modified Mahr MFU 100 measuring machine. First, a multi-rate Kalman filter with delay compensation is designed based on a simple physical modal model generalizing the applicability of the concept for different types of measuring machines and machine tools. Second, additional sensors in form of accelerometers placed at the TCP are used to obtain an indirect measurement of the TCP position at a fast sampling rate to reduce the effect of the model mismatch. Third, instead of additional sensors, an alternative concept consisting of enhanced Gaussian process modeling to improve the model accuracy with a data-based error model is incorporated in the Kalman filter framework in form of fast pseudo-measurements outperforming the other approaches.     

浅谈平面设计中软件的结合运用

随着计算机行业不断的发展和壮大,21世纪已经成为信息以光速发展的时代,各行各业都将计算机作为办公的首要选择工具,平面设计行业也不例外。利用计算机平面设计软件作为制图工具,广泛应用于平面设计中,已经是平面设计行业的主力军。     

Nonlinear control of a dynamic model of HIV-1

Highly active antiretroviral therapy (HAART) reduces the viral burden in human immunodeficiency virus type 1 (HIV-1) infected patients. The paper addresses the problem of controlling the predator-prey like model of the interaction among CD4+ T-cell, CD8+ T-cell, and HIV-1 by an external drug agency. By exploring the dynamic properties of the system, the original system is first regrouped into two subsystems, then a nonlinear global controller is presented by designing two controllers over two complementary zones: a local controller on a finite region and a global controller over its complement. The local controller is designed to guarantee nonnegativty, and avoids the problem of control singularity within the neighborhood of the origin omega. The complementary controller is designed via backstepping for both subsystems over the complementary region. The closed-loop system is globally stable at nominal values through the introduction of a novel bridging virtual control, and the resulting controller is singularity free and guarantees nonnegativity. In this paper, simulations are conducted in discrete-time with sampling time Ts to show the effectiveness of the proposed method.     

动态自学习的高效入侵检测模型研究

提出了一种基于归纳推理的动态自学习的高效入侵检测模型。将归纳推理方法应用到入侵检测中，提出了适用于入侵检测的增量学习推理算法。通过该算法建立的入侵检测模型能够对不断出现的新的网络行为数据进行自学习，并动态修正模型的行为轮廓，从而克服了传统静态检测模型必须完全重新学习才能更新模型甚至无法重新学习的缺陷，同时较大地提高了入侵检测模型的学习效率和检测效率。     

New dynamic SPT algorithm based on a ball-and-string model

A key functionality in today's widely used interior gateway routing protocols such as OSPF and IS-IS involves the computation of a shortest path tree (SPT). In many existing commercial routers, the computation of an SPT is done from scratch following changes in the link states of the network. As there may coexist multiple SPTs in a network with a set of given link states, such recomputation of an entire SPT not only is inefficient but also causes frequent unnecessary changes in the topology of an existing SPT and creates routing instability.. This paper presents a new dynamic SPT algorithm that makes use of the structure of the previously computed SPT. Our algorithm is derived by recasting the SPT problem into an optimization problem in a dual linear programming framework, which can also be interpreted using a ball-and-string model. In this model, the increase (or decrease) of an edge weight in the tree corresponds to the lengthening (or shortening) of a string. By stretching the strings until each node is attached to a tight string, the resulting topology of the model defines an (or multiple) SPT(s). By emulating the dynamics of the ball-and-string model, we can derive an efficient algorithm that propagates changes in distances to all affected nodes in a natural order and in a most economical way. Compared with existing results, our algorithm has the best-known performance in terms of computational complexity as well as minimum changes made to the topology of an SPT. Rigorous proofs for correctness of our algorithm and simulation results illustrating its complexity are also presented     

A dynamic photoresponse model for a pinned photodiode in CMOS image sensors

A novel dynamic photoresponse model for complementary metal-oxide-semiconductor (CMOS) image sensors with pinned photodiode (PPD) structures is proposed. The PPD is regarded as the bonding structure of the two p-n junctions. The transient current equation of the two junctions is calculated by the current-voltage formula of the p-n junction, and the photoresponse curve of the PPD is calculated and drawn by the numerical solution. Simulation results show that the dynamic model successfully restores the entire process of the electron accumulation in the PPD. The difference between the full well capacity (FWC) values which were calculated by the proposed model and the simulation results is less than 5%, which is much smaller than the error of 40% for the traditional model.     

Approximate dynamic model for evaluating distortion in a semiconductor laser under overmodulation

Overmodulation of a directly modulated semiconductor laser causes distortion in the optical signal. This distortion can be analyzed, in a first approach, using the model of a static limiter for the laser. In this letter, the dynamic effects in overmodulation of a semiconductor laser are addressed for a sinusoidal modulating current and an improved model is proposed by introducing an hysteresis. A time delay is taken into account for evaluating additional dynamic distortion arising when the optical intensity rises above threshold.     

图形化外场通用故障诊断模型开发平台设计与实现

外场装备的故障诊断系统要求具有通用性、直观性等特点,不依赖精确的数学模型和在线数据。基于符号有向图(SDG)的故障诊断系统具有逻辑直观清晰,推理计算高效,使用简单方便等优点,特别适用于外场通用故障诊断系统。通过分析SDG模型及其建模方法,开发了图形化故障诊断模型开发平台,实现了拖曳式绘图和智能化图形分析功能,使得装备使用维护人员也能够方便地开发故障诊断库,提高了外场装备保障能力。     

基于贝叶斯动态模型的某器件性能预测

在导弹武器系统当中,及时准确的故障预报对提高导弹的安全性具有极其重要的意义。本文根据导弹惯性器件故障预报系统的设计要求,利用贝叶斯动态线性模型对导弹某惯性器件的性能进行了预测研究。贝叶斯预测是利用历史信息和从样本获得的信息来获取后验分布的一种预测方法,该方法不需要平稳性的假设,而且充分利用了已有的信息,可以用来对电子设备的性能进行预测。实例研究表明,该方法具有比较好的预测效果。     

基于代理制的动态信息安全模式

从决策的角度提出了一种基于代理制的动态信息安全模式,该模式能够动态整合分布式信息安全系统,使分布式信息安全系统能够有效地系统工作,并修复已经收到攻击的系统.从应用层面来讲,提出的模式是保证信息安全的经济可行的方案.     

A discrete dynamic contour model

A discrete dynamic model for defining contours in 2-D images is developed. The structure of this model is a set of connected vertices. With a minimum of interaction, an initial contour model can be defined, which is then automatically modified by an energy minimizing process. The internal energy of the model depends on local contour curvature, while the external energy is derived from image features. Solutions are presented to avoid undesirable deformation effects, like shrinking and vertex clustering, which are common in existing active contour models. The deformation process stops when a local minimum of the energy function is reached. The final shape of the model is a reproducible approximation of the desired contour. Results of applying the method to computer-generated images, as well as clinical images, are presented.     

HotSpot: a dynamic compact thermal model at the processor-architecture level

This paper describes a thermal-modeling approach that is easy to use and computationally efficient for modeling thermal effects and thermal-management techniques at the processor architecture level. Our approach is based on modeling thermal behavior of the microprocessor die and its package as a circuit of thermal resistances and capacitances that correspond to functional blocks at the architecture level. This yields a simple compact model, yet heat dissipation within all major functional blocks and the heat flow among blocks and through the package are accounted for. The model is parameterized, boundary- and initial-conditions independent, and is derived by a structure assembly approach. The architecture community has demonstrated growing interest in thermal management, but currently lacks a way to model on-chip temperatures in a tractable way. Our model can be used for initial exploration of the design space at the architecture level. The model can easily be integrated into popular power/performance simulators, can be used to determine how thermal stress is correlated to the architecture, and how architecture-level design decisions influence thermal behavior and related effects.     

A model of write-inhibition in dynamic injection MNOS

Dynamic Injection MNOS (DIMNOS) memory devices feature high-speed writing, 5-V drain voltage, and MNOS backup one-transistor-type dynamic RAM's. They are written on MNOS, like conventional one-transistor-type dynamic RAM's, when high writing voltage is applied to the MNOS gate. In experiments with DIMNOS, the threshold-voltage shift (Delta V_{th}) of MNOS in the writing mode does not depend very much on temperature;Delta V_{th}in the write-inhibited mode depends hardly at all on temperature; andDelta V_{th}in the write-inhibited mode decreases under the condition that the product of the number of attempts and pulsewidth is constant when he pulsewidth is longer than 10^-4s. The proposed model in the write-inhibited mode means that weak avalanche occurs due to field concentration between the control transistor and MNOS memory region. As a result, hot electrons are injected between the ultrathin SiO2and Si3N4films of MNOS. This model is supported by the above mentioned experimental results in the write-inhibited mode.     

Establishment of a dynamic model for the p-Ge far IR laser

Using new experimental data from modeling the p-Ge laser pulse plus literature data, basic laser parameters are obtained so that one can solve the laser equations of Pantell and Puthoff to obtain formulas for calculating all laser quantities of interest. Values, calculated using the formulas, such as gain, saturation intensity, pump population differences, power generated, output coupling, efficiency, etc. are in excellent agreement with available experimental data. This work contributes to problems in determining laser line transitions, the laser cycle, and the optimization of the laser performance.     

A connectionist model for dynamic control

This paper describes an application of connectionist modeling techniques in the area of dynamic device control. In particular, competition-based spreading activation is applied to a simplified problem in camera tracking. Performance measures are obtained for both the fully operational connectionist network and for a partially impaired network. It is found that the connectionist model performed well in both cases, with the performance of the partially impaired network only being mildly diminished. This work shows that there is potential for the use of competitive activation mechanisms in such applications.