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Analysis of Compressed Foetal Phono-Cardio-Graphy (PCG) Signals with Discrete Cosine Transform and Discrete Wavelet Transform

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IETE JOURNAL OF RESEARCH 2022年第4期68卷 2736-2742页

作者： Aggarwal, Vibha Gupta, Sandeep Patterh, Manjeet Singh Kaur, Lakhwinder Punjabi Univ Coll Engn & Management Neighborhood Campus Rampura Phul India Punjabi Univ Univ Coll Engn Patiala Punjab India

In the present era, precise medical instruments are available to record the medical signals for diagnosis as well as regular monitoring of pregnant lady and foetus. These recorded signals are then transmitted to the medical expert as radio signals for clinical advice. The recorded signal if transmitted without any modification, it may consume a lot of memory space and bandwidth. To address this problem, a tunable compression technique has been implemented for Foetal Phonocardiography (PCG) signal using Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT). The results show that the overall increase in compression ratio was 16.2% and 19.4%, by varying the user-defined percentage root mean square difference (UPRD) value from 0.5 to 2.0 for DCT and DWT, respectively. The performance of DWT was better as compared to DCT for Foetal PCG signals in terms of high spatial resolution in DWT.

关键词： Arithmetic encoder bisection algorithm Huffman encoder MaxLloyd quantizer Tunable compression

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Chatter stability analysis and prediction for elliptical ultrasonic vibration-assisted milling process

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2024年第5-6期133卷 2937-2950页

作者： Li, Zhongqun Yang, Shangzhen Liu, Qiang Liu, Hong Liu, Yang Hunan Univ Technol Sch Mech Engn Zhuzhou 412007 Peoples R China Beihang Univ Jiangxi Res Inst Nanchang 330224 Peoples R China

Elliptical ultrasonic vibration-assisted milling (EUVAM) introduces ultrasonic frequency vibration into conventional milling (CM) to achieve high-frequency intermittent milling. It has broad application prospects in processing difficult-to-cut materials such as titanium alloys, superalloys, carbon fiber-reinforced plastic (CFRP), and hard and brittle materials. This study focuses on the development of a dynamic model for EUVAM that considers regenerative effects and analyzes the interaction between the cutting edge and the workpiece in both radial and tangential directions, and the dynamic chip thickness is derived based on this model. To solve the model, a Runge-Kutta-based fully discrete method (RKFDM) is employed. This numerical method accurately predicts the stability of the EUVAM process under specified cutting conditions. In addition, a bisection algorithm is utilized to construct the stability lobe diagram of EUVAM, enhancing the computational efficiency of the process. Stability tests are conducted to validate the proposed stability model and solution method for EUVAM. The results of these tests confirm the accuracy and reliability of the approach presented in this paper. This study provides valuable insights and a practical framework for implementing EUVAM in the processing of difficult-to-cut materials, offering improved machining performance in various industrial applications.

关键词： Elliptical ultrasonic vibration assisted milling Stability lobe diagram Runge-Kutta based fully discrete method bisection algorithm

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Joint Scheduling and Resource Allocation in the OFDMA Downlink: Utility Maximization Under Imperfect Channel-State Information

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2011年第11期59卷 5589-5604页

作者： Aggarwal, Rohit Assaad, Mohamad Koksal, C. Emre Schniter, Philip Ohio State Univ Dept Elect & Comp Engn Columbus OH 43210 USA

We consider the problem of simultaneous user-scheduling, power-allocation, and rate-selection in an orthogonal frequency division multiple access (OFDMA) downlink, with the goal of maximizing expected sum-utility under a sum-power constraint. In doing so, we consider a family of generic goodput-based utilities that facilitate, e. g., throughput-based pricing, quality-of-service enforcement, and/or the treatment of practical modulation-and-coding schemes (MCS). Since perfect knowledge of channel state information (CSI) may be difficult to maintain at the base-station, especially when the number of users and/or subchannels is large, we consider scheduling and resource allocation under imperfect CSI, where the channel state is described by a generic probability distribution. First, we consider the "continuous" case where multiple users and/or code rates can time-share a single OFDMA subchannel and time slot. This yields a nonconvex optimization problem that we convert into a convex optimization problem and solve exactly using a dual optimization approach. Second, we consider the "discrete" case where only a single user and code rate is allowed per OFDMA subchannel per time slot. For the mixed-integer optimization problem that arises, we discuss the connections it has with the continuous case and show that it can solved exactly in some situations. For the other situations, we present a bound on the optimality gap. For both cases, we provide algorithmic implementations of the obtained solution. Finally, we study, numerically, the performance of the proposed algorithms under various degrees of CSI uncertainty, utilities, and OFDMA system configurations. In addition, we demonstrate advantages relative to existing state-of-the-art algorithms.

关键词： bisection algorithm imperfect channel state information (CSI) mixed integer optimization orthogonal frequency division multiple access (OFDMA) resource allocation scheduling utility maximization

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Generation of a finite element MESH from stereolithography (STL) files

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COMPUTER-AIDED DESIGN 2002年第1期34卷 1-17页

作者： Béchet, E Cuilliere, JC Trochu, F Ecole Polytech Dept Genie Mecan CRASP Montreal PQ H3C 3A7 Canada Univ Quebec Trois Rivieres Dept Genie Mecan Lab Prod Trois Rivieres PQ G9A 5H7 Canada

The aim of the method proposed here is to show the possibility of generating adaptive surface meshes suitable for the finite element method, directly from an approximated boundary representation of an object created with CAD software. First, we describe the boundary representation, which is composed of a simple triangulation of the surface of the object. Then we will show how to obtain a conforming size-adapted mesh. The size adaptation is made considering geometrical approximation and with respect to an isotropic size map provided by an error estimator. The mesh can be used "as is" for a finite element computation (with shell elements), or can be used as a surface mesh to initiate a volume meshing algorithm (Delaunay or advancing front). The principle used to generate the mesh is based on the Delaunay method, which is associated with refinement algorithms, and smoothing. Finally, we will show that not using the parametric representation of the geometrical model allows us to override some of the limitations of conventional meshing software that is based on an exact representation of the geometry. (C) 2001 Published by Elsevier Science Ltd.

关键词： mesh generation STL file format bisection algorithm Delaunay triangulation

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Private Sequential Learning

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OPERATIONS RESEARCH 2021年第5期69卷 1575-1590页

作者： Tsitsiklis, John N. Xu, Kuang Xu, Zhi MIT LIDS 77 Massachusetts Ave Cambridge MA 02139 USA Stanford Univ Grad Sch Business Stanford CA 94305 USA

We formulate a private learning model to study an intrinsic tradeoff between privacy and query complexity in sequential learning. Our model involves a learner who aims to determine a scalar value v* by sequentially querying an external database and receiving binary responses. In the meantime, an adversary observes the learner's queries, although not the responses, and tries to infer from them the value of v*. The objective of the learner is to obtain an accurate estimate of v* using only a small number of queries while simultaneously protecting his or her privacy by making v* provably difficult to learn for the adversary. Our main results provide tight upper and lower bounds on the learner's query complexity as a function of desired levels of privacy and estimation accuracy. We also construct explicit query strategies whose complexity is optimal up to an additive constant.

关键词： sequential learning privacy bisection algorithm

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Modeling, optimization and control of a FC/battery hybrid locomotive based on ADVISOR

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2017年第29期42卷 18568-18583页

作者： Zhang, Guorui Chen, Weirong Li, Qi Southwest Jiaotong Univ Sch Elect Engn Chengdu 610031 Sichuan Peoples R China

This paper presents a hybrid locomotive system which combines proton exchange membrane fuel cell (PEMFC) as primary energy source for its advantages of high efficiency and low emissions, and Pb acid battery as secondary energy storage (ESS) to supplement the output of FC during acceleration or whenever else needed and to absorb regenerative energy during braking. Advanced Vehicle Simulator (ADVISOR), a vehicle simulating software, is secondly developed in this paper for the locomotive modeling and simulation. An analysis of simulation is conducted to verify the effectiveness of the proposed model. Then the power of FC, battery and motor are optimized by adopting bisection algorithm under certain constraints. It is confirmed that the dynamic performance and economy performance are improved after optimization. An advanced energy management system is extremely necessary to contribute the demand power of locomotive between energy sources in a suitable way, therefore a fuzzy logic based control strategy is proposed for the hybrid locomotive. With advantages of easy understanding, flexibility and capability to deal with imprecise data, fuzzy logic methodology is suitable for the control of hybrid locomotive. The simulation results demonstrate the superiority of fuzzy logic energy management system in terms of dynamic and economy performance. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Fuel cell/battery hybrid locomotive ADVISOR System modeling bisection algorithm Fuzzy logic

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Predictive Reliability Analysis of Power Distribution Systems Considering the Effects of Seasonal Factors on Outage Data Using Weibull Analysis Combined With Polynomial Regression

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IEEE ACCESS 2023年 11卷 138261-138278页

作者： Dechgummarn, Yuttana Fuangfoo, Pradit Kampeerawat, Warayut Khon Kaen Univ Fac Engn Dept Elect Engn Khon Kaen 40002 Thailand Prov Elect Author PEA Bangkok 10900 Thailand

In this study, the reliability of power distribution systems is analyzed using a novel strategy of predictive reliability analysis based on the lifetime failure rate cycle in a bathtub curve shape and considering the standard Weibull distribution to determine the trend of the failure rate in each period using median rank regression for parameter estimation. The proposed strategy consists of three processes. The first process involves separating the external and internal factors that influence power outages in the power distribution system from the seasonal multimodal shape in the empirical distribution of the dataset using a bisection algorithm of residuals of polynomial regression. Second, clustering and characterization of each component in the power distribution system according to the condition of the total factor bathtub curve leads to the introduction of the use of shape parameters as the total factor deterioration index (TFDI) with linear regression trends of log scale shape parameters of the useful period. A simple approximation of the system's overall total factor bathtub curve using a sixty-year forecast is the final process presented that can be used in reliability planning to address lifecycle risks. The actual time-to-outage dataset between 2015 and 2020 of the Provincial Electricity Authority, Region 1, Northeastern Thailand, which covers the area of distribution line life in the three periods of the bathtub curve, was used as the test data. The numerical results obtained from the proposed process provide a comprehensive prediction of the reliability of the electrical distribution system for risk response planning. The results show the proportion and amount of internal deterioration versus external disturbances, helps to group components according to health and usability and prioritizes them according to risk. Furthermore, it clarifies the important moments of status transition. All of these factors make it possible to improve reliability in the right

关键词： Time to outage failure rates bathtub curve standard Weibull distribution predictive reliability electric distribution system polynomial regression bisection algorithm

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Optimal dynamic-inversion-based control of an overhead crane

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IEE PROCEEDINGS-CONTROL THEORY AND APPLICATIONS 2002年第5期149卷 405-411页

作者： Piazzi, A Visioli, A Univ Parma Dipartimento Ingn Informaz I-43100 Parma Italy Univ Brescia Dipartimento Elettron & Automaz I-25121 Brescia Italy

A methodology is proposed to control the transient sway and residual oscillation of a payload carried by an overhead crane. The design approach is based on a linearised model of the crane and consists of dampening the linearised system by an observer-based controller and applying a dynamic inversion procedure in order to assure a predetermined oscillation free polynomial motion law for the payload. Polynomial functions are adopted in order to guarantee that the input function has a continuous derivative of an arbitrary order. Moreover, the motion time can be minimised, taking into account constraints on the actuators, by means of a simple bisection algorithm. Parameter uncertainties are taken into account during the whole design procedure. Simulation results, based on a nonlinear crane model, show how the method is also effective when the payload is hoisted or lowered during the motion, and when friction effects are considered.

关键词： parameter uncertainties functions nonlinear systems design approach motion control Control applications to materials handling friction polynomial functions state feedback feedforward cranes transient sway Materials handling equipment residual oscillation Materials handling and distribution optimal control Optimal control Nonlinear control systems Algebra nonlinear crane model polynomials optimal dynamic-inversion-based control control system synthesis bisection algorithm Control system analysis and synthesis methods friction effects overhead crane payload observer-based controller predetermined oscillation free polynomial motion law Spatial variables control linearised model

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Entropy maximization and NT vacation M/G/1 model with a startup and unreliable server: comparative analysis on the first two moments of system size

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INTERNATIONAL JOURNAL OF COMPUTER MATHEMATICS 2009年第4期86卷 703-718页

作者： Ke, Jau-Chuan Lin, Chuen-Horng Huang, Hsin-I Natl Taichung Inst Technol Dept Informat Management Taichung Taiwan Natl Taichung Inst Technol Dept Appl Stat Taichung Taiwan Natl Taichung Inst Technol Dept Comp Sci & Informat Engn Taichung Taiwan

We consider the control policy of an M/G/1 queueing system with a startup and unreliable server, in which the length of the vacation period is controlled either by the number of arrivals during the idle period, or by a timer. After all the customers have been served in the queue, the server immediately takes a vacation and operates an NT vacation policy: the server reactivates as soon as the number of arrivals in the queue reaches a predetermined threshold N or when the waiting time of the leading customer reaches T units. In such a variant vacation system, the steady-state probabilities cannot be obtained explicitly. Thus, the maximum entropy principle is used to derive the approximate formulas for the steady-state probability distributions of the queue length. A comparitive analysis of two approximation approaches, using the first and the second moments of system size, is studied. Both solutions are compared with the exact results under several service time distributions with specific parameter values. Our numerical investigations demonstrate that the use of the second moment of system size for the available information is, in general, sufficient to obtain more accurate estimations than that of the first moment.

关键词： bisection algorithm comparative analysis Lagrange's method maximum entropy moments of system size

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Joint Throughput Equalization Power Control and Cell-Free Model for Enhancing Performance of WBANs

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WIRELESS PERSONAL COMMUNICATIONS 2024年第2期139卷 921-946页

作者： Bao, Bo Quoc Anh, Bui Tien Yen, Vu Thi Hoang Hiep, Pham Thanh Le, Hai-Nam Hanoi Univ Ind Fac Elect Engn Hanoi 100000 Vietnam Le Quy Don Tech Univ Adv Wireless Commun Grp 236 Hoang Quoc Viet Hanoi 100000 Vietnam Le Quy Don Tech Univ Fac Radioelect Engn 236 Hoang Quoc Viet Hanoi 100000 Vietnam

Wireless body area networks (WBANs) have gained significant attention due to their versatile applications in healthcare and the rapid development of personal healthcare devices. This paper proposes a novel cell-free (CF) model for WBANs, where multiple access points (APs) instantaneously support distributed sensors placed on the body by allowing all sensors to share the same time and frequency resources. Unlike multiple access schemes, such as non-orthogonal multiple access (NOMA), "cell-free" in our context denotes a decentralized architecture where multiple distributed APs cooperatively serve multiple sensors without the traditional cell boundaries. In NOMA systems, APs communicate with sensors in a cell by superimposing signals at different power levels, whereas CF systems enhance signal quality through joint processing across APs. Different from the traditional star topology WBAN where one AP communicates with only one sensor at a time, the CF model allows all sensors to transceive information data at the same time. Furthermore, a joint CF model and transmit power control algorithm is proposed to control the transmit power of sensors in the uplink and APs in the downlink of the CF model WBAN based on channel conditions in order to reduce the inter-user interference, maintain fairness among all sensors, and thereby improve the per-sensor throughput. The achievable uplink and downlink rates are derived using matched filtering and computational algorithms, resulting in a closed-form solution. The proposed joint method of the CF model and transmit power control algorithm is compared with the CF model without power control and traditional star topology WBANs to assess the effectiveness of the proposed approaches via several key parameters, including the number of sensors, the number of APs, and the length of pilot sequences. Simulation results demonstrate that the proposed approaches enhance system performance in both uplink and downlink across all tested scenarios.

关键词： Wireless body area network Cell-free Throughput equalization power control bisection algorithm

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