Miracle-dz/UniFAR-FTUs huggingface dataset:
Modeling joints with clearance and friction in multibody dynamic simulation of automotive differentials

Defects in kinematic joints can sometimes highly influence the simulation response of the whole multibody system within which these joints are included. For instance, the clearance, the friction, the lubrication and the flexibility affect the transient behaviour, reduce the component life and produce noise and vibration for classical joints such as prismatics, cylindrics or universal joints. In this work, a new 3D cylindrical joint model which accounts for the clearance, the misalignment and the friction is presented. This formulation has been used to represent the link between the planet gears and the planet carrier in an automotive differential model.
A low-power small-area ADC array for IRFPA readout

The readout integrated circuit (ROIC) is a bridge between the infrared focal plane array (IRFPA) and image processing circuit in an infrared imaging system. The ROIC is the first part of signal processing circuit and connected to detectors directly, so its performance will greatly affect the detector or even the whole imaging system performance. With the development of CMOS technologies, it’s possible to digitalize the signal inside the ROIC and develop the digital ROIC. Digital ROIC can reduce complexity of the whole system and improve the system reliability. More importantly, it can accommodate variety of digital signal processing techniques which the traditional analog ROIC cannot achieve. The analog to digital converter (ADC) is the most important building block in the digital ROIC. The requirements for ADCs inside the ROIC are low power, high dynamic range and small area. In this paper we propose an RC hybrid Successive Approximation Register (SAR) ADC as the column ADC for digital ROIC. In our proposed ADC structure, a resistor ladder is used to generate several voltages. The proposed RC hybrid structure not only reduces the area of capacitor array but also releases requirement for capacitor array matching. Theory analysis and simulation show RC hybrid SAR ADC is suitable for ADC array applications
Equivalent Damping in Support of Direct Displacement-Based Design

The concept of equivalent linearization of nonlinear system response as applied to direct displacement-based design is evaluated. Until now, Jacobsen's equivalent damping approach combined with the secant stiffness method has been adopted for the linearization process in direct displacement-based design. Four types of hysteretic models and a catalog of 100 ground motion records were considered. The evaluation process revealed significant errors in approximating maximum inelastic displacements due to overestimation of the equivalent damping values in the intermediate to long period range. Conversely, underestimation of the equivalent damping led to overestimation of displacements in the short period range, in particular for effective periods less than 0.4 seconds. The scatter in the results ranged between 20% and 40% as a function of ductility. New equivalent damping relations for four structural systems, based upon nonlinear system ductility and maximum displacement, are proposed. The accuracy of the new equivalent damping relations is assessed, yielding a significant reduction of the error in predicting inelastic displacements. Minimal improvement in the scatter of the results was achieved, however. While many significant studies have been conducted on equivalent damping over the last 40 years, this study has the following specific aims: (1) identify the scatter associated with Jacobsen's equivalent damping combined with the secant stiffness as utilized in Direct Displacement-Based Design; and (2) improve the accuracy of the Direct Displacement-Based Design approach by providing alternative equivalent damping expressions.
S3 Micromachine as Multi-Scale Interface for BME

This paper describes multi-scale interface for bio and medical engineering based on MEMS technology. MEMS technology can provide various interfaces for biomedical application corresponding to hierarchical components of living organism such as cell, tissue, and organ. This paper mainly deals with small, soft, and safe (S3) micromachine as multi-scale interfaces for medical application. Micromachine is small in nature. S3 micromachine is based on its soft and flexible structure and safe driving principle. These features are suitable for advanced medical tools for minimally invasive medical operations. S3 micromachines-based medical tool has been applied to a retractor for spacing in front of the endoscope at our early stage. This paper also presents the S3 micromachine as a surgical tool for a cell sheet transplantation in an eye.
Experimental and Numerical Investigations on Nonlinear Aeroelasticity of Forward-Swept, Compliant Wings

At the beginning of aviation history, aeroelastic static instabilities represented a problem in operating monoplane aircraft. After being discovered, they were systematically avoided, since they would have led to large deformations and structural failure. A new idea (active aeroelasticity) reverts this approach and utilizes static instabilities to realize wing morphing instead of avoiding them. Another innovative idea (compliant systems) deals with structures designed to achieve large deformations within the elastic range of the material. Joining those two ideas leads to a novel class of airfoil structures (active aeroelastic, compliant airfoils) which enable operation at and beyond aeroelastic instabilities. Such structures need a new modeling approach, which includes nonlinearities of structural and aerodynamic kinds. In this paper, a non linear analysis of aeroelastic bending divergence (a phenomenon which concerns forward-swept wings) is presented, initially based on so-called low-fidelity models. Such models are, to some extent, inaccurate but allow a good insight into the physical behavior of the phenomenon and are very useful in preliminary design. The results of wind-tunnel tests follow, which were performed to investigate the aeroelastic response of a compliant airfoil model near divergence. Finally, high fidelity simulation results based on state-of-the-art methods (finite element method and fluid-structure-interaction) are shown and discussed. Those tools allow the prediction of the system response more accurately and are therefore well suited to the detailed design of active aeroelastic, compliant airfoils.
Technological challenges on the road toward transparent networking

The sustainable growth of high-bandwidth services and on-demand applications has introduced new challenges to next-generation networks in terms of capacity, configurability, and resiliency. Significant networking advancements need to be achieved with architectures and technologies that are scalable with respect to cost, size, and power requirements, while they should be capable of handling high traffic volumes and dynamically changing connection patterns. Transparent networking has the potential to meet those requirements and offer significant benefits in terms of performance and cost. We present the key enabling technologies, review the state-of-the-art achievements, and discuss the new opportunities that optical transparency has and will introduce.
Comparison of fixed speed and doubly-fed induction wind turbines during power system disturbances

The dynamic modelling of large (MW) capacity fixed and variable speed induction generator wind turbines is discussed. A reduced order dynamic machine model is derived suitable for modelling both fixed speed and doubly-fed asynchronous generator wind turbines. Control schemes for variable speed turbines, using doubly-fed induction generators (DFIG), are described and simulated. Speed control characteristics and converter protection of the DFIG are implemented in the model. The operation of the models during power system disturbances such as network voltage sags and three-phase faults, as well as the possibility of network voltage instability, are investigated. Simulation results are presented using typical turbine and network data for wind farm installations.
FEEDBACK CONTROL AND STEERING LAWS FOR SPACECRAFT USING SINGLE GIMBAL CONTROL MOMENT GYROS

The complete dynamic equations for large-angle rotational maneuvers of spacecraft using single gimbal control moment gyros are derived by the Newton-Euler approach. Feedback control laws are developed by using Liapunov stability theory. Gimbal rate steering laws neglecting gimbal and rotor transverse inertia terms are reviewed. A gimbal acceleration steering law is also developed by including all the CMG inertia terms. \Vith these control and steering laws, several rotational maneuvers are simulated numerically by a Runge-Kutta method. The feedback control laws in combination with either velocity or acceleration steering laws are shoan to work well. It is found that the velocity steering law is adequate for simulations, but the acceleration steering law provides more reliable and useful data regarding gimbal torques. It is also observed that the initial gimbal angles have a profound influence on singularity avoidance.
On nonuniform packet switched delta networks and the hot-spot effect

We analyse the performance of a multistage interconnection network (MIN) with a packet-switching protocol, embedded in a closed network of processors. First, the expected value of transmission time through a delta-2 type of MIN is determined. We then obtain, for the first time by an analytical method, a formula for its probability density function from which the variance and higher moments follow. Previously densities have only been estimated by simulation which is expensive and can be unreliable, especially in the often crucial tail region. Numerical results reveal new insights into the hot-spot phenomenon which occurs when one output address is selected more frequently than the others. We first show how mean transmission time on hot paths increases with the hot-spot intensity and compare this with cooler paths. We also plot the density functions for these transmission times. Hence it is possible to determine precisely transmission time variability and to obtain reliability measures from their tails. The approach can handle arbitrary routing frequencies to the MIN output addresses and suggests new approximation techniques with wider applicability.
Carrier-rotation strategy for voltage balancing in flying capacitor multilevel inverter

A carrier-rotation PWM technique to solve the voltage unbalancing problem of flying capacitors in the flying capacitor multilevel inverter (FCMI) is proposed. The PWM technique equalises the utilisation of phase leg voltage redundancies corresponding to the charging and the discharging state of individual flying capacitors during one switching period of all the switches. Therefore, the charging and the discharging quantities of the flying capacitors are equal, which causes the average variation of the flying capacitor voltages to become zero and keeps their voltage stable during a minimum specified period. The proposed PWM technique also has the same switch utilisation and the reduced harmonic content of the output voltage since the switching frequency of each switch is identical and all the carrier signals are in phase. Hence, it is more suitable for the FCMI than the phase-shift PWM method. The proposed PWM technique is analysed in a flying capacitor three-level inverter and is then expanded to an N-level FCMI (N>3). Simulation and experimental results on the laboratory prototype flying capacitor three-level inverter confirm the validity of the proposed PWM technique.
Design and Electromagnetic Analysis of Microstructured Holey Optical Fibres with Stepwise Random-Air-Hole Distributions in Concentric Cladding Layers

As distinctive variants of the microstructured holey optical fibre (MHOF), stepwise random-air-hole optical fibres (SRHOFs) are first proposed, and design parameters are explained in order to find out influences of air-filling fraction (AF) conditions of randomized air holes in stepwise cladding regions and obtain small effective area and fairly reasonable dispersion characteristics for sensor or nonlinear device applications. Based on two computational techniques of finite-difference time-domain (FDTD) method and finite difference method (FDM), several propagation characteristics such as normalized propagation constants, chromatic dispersions, electromagnetic fields, and effective areas are investigated. This new type of design approach can be expected to be useful from the point of view of manufacturing processes and fabrications of variety fibre-optic components.
Dynamic State Forecasting in Electric Power Networks

The real time monitoring and control have become very important in electric power system in order to achieve a high reliability in the system. So, improvement in Energy Management System (EMS) leads to improvement in the monitoring and control functions in the control center. In this paper, DSE is proposed based on Weighted Least Squares (WLS) estimator and Holt’s exponential smoothing to state predicting and Extended Kalman Filter to state filtering. The results viewing the dynamic state the estimator performance under normal and abnormal operating conditions.
TLD Technique for Reducing Ice-Induced Vibration on Platforms

Tuned liquid damper (TLD) containers are designed to provide their sloshing forces in opposite directions against the inertia loads of the vibrating structure and thus to reduce the vibration. The sloshing forces that result from liquid motion may be determined either analytically or experimentally. The efficiency of the TLD in vibration reduction then can be estimated by attaching the TLD subsystem onto the dynamic equation of the vibrating structure. This paper describes investigations of the TLD system for an existing Bohai production jacket, which has routinely been excited by drifting ice during the winter seasons. In addition to a theoretical demonstration, a scaled model test and a full-scale field experiment were performed in this study. The technical strategy and main results of the investigation are presented in this paper.
Burst Detection Using an Artificial Immune Network in Water-Distribution Systems

AbstractA new method using artificial immune network is presented to identify pipe burst in water-distribution systems. Burst detection is considered as the problem of pattern recognition in the proposed method. An artificial database that includes information on burst events (BEs) is first established. Using the clonal selection algorithm, the artificial immune network is constructed based on the principle of immune system. The burst location is finally identified using the nearest neighbor method. Three offline case studies are illustrated in detail to evaluate the current method. A total of five possible burst locations are identified from 34 nodes in Case Study 1, whereas four possible burst locations are identified from 77 nodes in Case Study 2. The results derived from the first two case studies show that the method can identify the possible burst areas, including the true burst location, using model-simulated results. The data derived from real BEs in Case Study 3 are used to evaluate the proposed .
Application of fused visual and thermal images in monitoring and evaluation of welding processes

This article presents the application results of different methods of merging images recorded using vision cameras and thermal imaging cameras. The images were recorded during the evaluation of a welding process. The object of observation was the welding arc and the welded joint during its cooling phase. Images recorded during GMA welding on two different welding stations have been taken into account. The observations have been conducted using cameras equipped with different optics systems. This article presents an analysis of the influence of different parameters of the optics systems on the resulting fused images. The analysis also considers the pre-processing method to ensure correct matching of images. The study shows that the fused image contains aggregated information useful in online monitoring and quality evaluation of the welding process.
Longitudinal wave propagation in piezoelectric coupled rods

This paper presents the results of longitudinal wave propagation in piezoelectric coupled rod structures. The deduction of non-dispersive or dispersive characteristics of the structures is based on a classical rod model and the Mindlin–Herrmann rod model. In the classical model, correction factors for piezoelectric effects are introduced to provide remedy for the discontinuity of the normal stress at the interface of the host rod and the piezoelectric layer. The non-dispersive characteristics of the structures, in which the piezoelectric effects are modelled are thus obtained by this classical model. The two-mode characteristics for the piezoelectric coupled rod structures are obtained by the Mindlin–Herrman model in which the lateral inertia is considered. This model is more accurate in predicting the dispersive characteristics of the structures. The results of the long- and short-wavelength limits are obtained as by-products. The results of phase velocity by the two models are agreeable at low wavenumber by adjusting the correction factor defined in the classical model. The results of this paper can serve as a reference for future study on wave propagation in coupled structures as well as in the design of smart structures incorporating piezoelectric materials.
PDR-Aided Algorithm with WiFi Fingerprint Matching for Indoor Localization

Recently, indoor localization is essential to enable location-based services for many mobile and social network applications. Due to fluctuation of the wireless signal, the accuracy of a simple WiFi fingerprint-based localization is not high. In this paper, we first exploit Pedestrian Dead Reckoning (PDR) technology to overcome the problem of the wireless signal fluctuation, then propose a PDR-aided algorithm with WiFi fingerprint matching for indoor localization, which using the PDR technology aided indoor localization. Experiments show that our algorithm has better accuracy than other indoor localization methods.
Bi-directional Zero-current Soft-switching Technique Applied for Bi-directional DC-DC Converter in Energy Capacitor Systems

Abstract In our previous work, we proposed the current-source energy capacitor system (CS-ECS), which consists of an electric double-layer capacitor, current-source inverter, and bi-directional four-quadrant DC-DC (FQ DC-DC) converter to control active/reactive power that can achieve the output leveling of wind energy system. However, this system had low conversion efficiency due to hard-switching losses. The improvement of conversion efficiency and performance are indispensable to implement the CS-ECS. This article proposes the soft-switched FQ DC-DC converter with a simple L-C resonant circuit for the CS-ECS. Since the insulated gate bipolar transistors of the converter softly turns on and off by using current-mode resonance, the conversion efficiency for the proposed system improves. In order to illustrate the operating principle of the proposed system, we analyze the transition of conversion efficiency with charge and discharge operation in detail through a theoretical approach and computer simulations with MATLAB/SIMULINK and SimPowerSystems Toolbox.
A real-time inclinometer based on an etched fiber Bragg grating connected to hollow-core fiber

We propose and experimentally demonstrate a low-cost, compact temperature-insensitive inclinometer, which is constructed by connecting a chemically etched fiber Bragg grating to a hollow-core fiber filled with tin. The optical power reflected from the grating is linearly proportional to the inclination angle of the grating and can provide a real-time measure of the inclination angle. Our experimental sensor can measure the inclination angle from 0° to 20° with an uncertainty of ± 0. 35º and negligible temperature interference.
General formulation of the current‐voltage characteristic of a p‐n heterojunction solar cell

A derived current‐voltage (I‐V) characteristic for p‐n heterojunction solar cells of the form window/absorber is obtained. The development lends itself to a simple, diagrammatical interpretation of the step‐by‐step collection of the photocurrent flowing out of the base of the absorber. The resulting general I‐V characteristic under illumination is in a form useful for the design of these devices and for the interpretation of their performance.
Simulation approach for the design of radiation-hardened Erbium doped fiber amplifiers

We investigate the sensitivity of fiber amplifiers to radiations and present an approach to design radiation hardened rare-earth doped fiber amplifiers. This paper includes testing experiments on comparing the radiation responses (200krad electron irradiation) of fiber amplifiers made with same lengths of different rare-earth doped fibers. Simulation tools can also be used to improve the tolerance of the fiber amplifiers by helping identifying the best performance for operation in harsh environment, simulation analysis figured that fiber length of the amplifier should be optimized to reduce the radiation-induced losses around the signal wavelength that strongly impact the fiber response. By using this particular approach, fiber amplifiers with little insensitivity to radiations could be manufactured in the future.
Risk based engineering for design, material selection and maintenance of power plants

Abstract Risk based engineering (RBE) provides a measure of decision making through risk assessment of design, manufacturing, operation and maintenance. The application study of RBE to fossil power plants is presented here especially focusing on steam turbines. Typical damage modes and mechanisms are presented, and failure scenarios are expressed in terms of event trees. The comprehensive risk assessment approach is expressed in terms of the conventional risk matrix method for prioritizing the important events and the probabilistic approach for more quantitative evaluation. To make more rational decision making, a ‘Bayesian’ network approach is introduced as an effective tool of casual structure determination in the probabilistic risk assessment framework. The Bayesian network approach for determining the casual structure of risk scenario is shown to be a potential tool for constructing the risk scenario automatically in the data-driven manner even in the case of insufficient available data. Finally a material selection and design map is presented for the creep-fatigue damage condition of turbine components using a two-parameter probability distribution function to make a reliable initial design of high temperature structures.
Life-Cycle Environmental Analysis for Evaluation of Pavement Rehabilitation Options

Transportation engineers, planners, and policy makers are currently faced with the need to incorporate sustainability issues such as energy use, greenhouse gas emissions, and overall health impacts into the decision-making process. Life-cycle environmental analysis (LCEA) is one of the evolving tools available to assist in this effort. LCEA differs from traditional environmental analysis in that LCEA takes a more comprehensive look, or global perspective, at the environmental and resource burden of specific management decisions as opposed to traditional environmental analysis, which tends to focus almost exclusively on specific impacts at the activity or in the immediate geographic vicinity of the activity. The results of a study are presented: the computer program Pavement Life-Cycle Assessment Tool for Environmental and Economic Effects (PaLATE) was used to compare the environmental burden of employing cold in-place recycling with the environmental burden of the conventional maintenance options of a 3-in. mill and fill and a 3-in. hot-mix asphalt overlay. The results illustrate the potential of life-cycle environmental models to assist transportation officials in developing 21st century transportation policy as well as the current limitations associated with their use.