To develop closed-loop coupling models for brake squeal analyses, the modal parameters of the disc rotor are calculated from the finite element model and many repeated-root modes appear. A pair of repeated-root modes represents one vibration mode. However, the current substructure mode composition analysis method treats each pair of repeated-root modes as two independent modes, so there may be difficulty in identifying the most important parameters for the noise mode. The modal shape coefficients of the repeated-root modes are fit from the finite element results. A single composition factor is then derived for each pair of repeated-root modes which represents the total contribution of these modes to the noise mode according to the definition of the mode composition and the curve fits. Examples show that this method more clearly relates repeated-root modes of the disc rotor to the noise mode, which provides support for developing effective measures for squeal reduction.

Accident velocity information is difficult to obtain with accident reconstruction used to compute velocities, primarily using energy-based estimates. However, the different stiffnesses of the vehicles are difficult to estimate, which leads to significant uncertainty in the computed velocity. This is a major problem because most approaches for estimating the effect of driver assistant systems need the velocities of the involved vehicles. A method is given here to evaluate past safety enhancements to predict future enhancement based on the vehicle deformation depth. Analyses of German accident data show that for vehicles of significantly different stiffnesses, the vehicle deformation depth more truly reflects the severity of the accident than the velocity change. Vehicle safety enhancements over the past 30 years are then calculated based on the deformation depth. The results are in good agreement with historical data, which verifies the safety enhancement evaluation method using deformation depth information. A deformation-depth-based safety impact prediction method is also given for driver assistance systems. This prediction method uses the accurate deformation depth information in the accident database to improve evaluations of driver assistance systems.

Reliable routing and charging plans are needed for fully electric vehicles (FEVs) to ease the intrinsic drawbacks of FEVs, such as mileage limitations, overly long charging times, limited charging stations, and limited battery lifetimes to enhance the driving performance and drivers' acceptance. However, most research has overlooked the effects of changing traffic system features and has provided travelling strategies for only a single travelling objective rather than strategies that consider multi-factors simultaneously. This paper describes a multi-objective, multi-constraint travelling plan optimization strategy for dynamic time-dependent traffic networks for FEVs. This optimization strategy includes the time-dependent stochastic changes of the traffic environment with the multi-objective ant colony optimization method used to calculate the optimal Pareto travelling plan set. The result provides drivers with information including travelling route, travelling speed on each road, charging locations and modes, and air-conditioner usage. The results show that a travelling plan within a dynamic time-dependent traffic environment is better than that within a stable deterministic traffic environment. The travelling result with multi-objective optimization is better than a single objective strategy. This multi-objective, multi-constraint optimization method provides reasonable travelling plans that enhance the driving performance of FEVs.

The driving comfort of drivers in passenger vehicles was evaluated using an ontology model for driving comfort in a human-machine-environment system. The model was then used to evaluate driving comfort with the main driving comfort description extracted and classified via user interviews based on the improved term frequency-inverse document frequency (TF-IDF) method. The words were then ranked in a hierarchical structure. The scale of nine in the traditional analytical hierarchy process (AHP) was replaced by a scale of three to improve the accuracy. The comparative judgment matrix was defined with the weight of each index calculated through a Delphi survey. The index consistency system was also tested. The reliability of this method was validated using C-class passenger vehicles. Thus, this gives an effective approach for evaluating vehicle driving comfort.

Clutchless coupled motor-transmission system characteristics often change, so models are needed to predict their gear shifting characteristics. This study uses multi-body dynamics and hybrid system theories to build a hybrid automaton model of the gear shifting process in the clutchless coupled system. The shifting quality of the clutchless coupled system is then analyzed for various shifting forces and relative rotational positions and speeds of sleeve and the clutch gear. The clutchless coupled system can provide better shifting quality than systems with clutches by actively controlling the motor torque and shifting force.

A coordinated control system is developed for the regenerative and hydraulic braking systems in electric vehicles based on a tire-road adhesion model to ensure the stability of electric vehicles with anti-lock braking using motor control accuracy and fast response. The system is designed for a distributed drive electric vehicle with the tire-road adhesion estimated according to the vehicle dynamics. The system measures the motor torque and the wheel cylinder braking pressure. Different coordinated control strategies are given for three tire-road adhesion levels with a coordination mechanism that stops the regenerative braking during anti-lock braking control. Simulations show that this strategy improves both the braking stability and the regenerative energy efficiency during braking. The regenerative braking control reduces the hydraulic braking pressure fluctuations and improves braking stability and comfort.

The flows in brush seals were modeled using a two-dimensional closed staggered tube bundle model of the bristle pack cross section that was solved using computational fluid dynamics (CFD). The pressure and velocity distributions of the leakage were studied for various pressure differentials, number of axial bristle rows, and inter-tube spacing. The results show that the calculated pressures and velocities with 1 and 6 bristles in the circumferential direction are very similar with differences less than 3% for each data point and the calculated pressure gradients agree with rotor surface pressure measurements. For an inlet pressure of 0.2 MPa, the pressure drop across the last downstream bristle is about 6 times that over the upstream bristles while the maximum velocity rise is about 8 times greater. The growing pressure differential exacerbates the pressure drop and the maximum velocity rise across the last downstream bristle. The average outlet axis velocity increases linearly with the increasing pressure differentials and deceases logarithmically with the number of axial bristle rows. The sealing effect can be significantly enhanced by reducing the inter-tube spacing of the bristles for normal pressure differentials and number of axial bristle rows.

Graphite gaskets are widely used static seals. This study examines the mechanical properties on the seal interface which is significant to the sealing performance. The study uses finite element simulations based on a test rig structure and elastic-plastic material properties. The compression-resilience curve is measured in the same test rig. The simulations show the changes in the contact pressure and deformation distribution during loading and unloading. The simulated compression-resilience curves agree with the measured data to validate the finite element model. The results explain the sealing mechanism of high contact stiffness, load stability, and installation repeatability for this kind of gasket.

The loosening of threaded fasteners experiencing transverse vibrations is a complicated multi-stage process. This study uses a Junker transverse vibration tester to study the loosening of threaded fasteners with transverse vibrations. Also, the clamping force is correlated with the transverse displacement for single transverse vibration cycles. Correlations of the clamping force show that during the early stage of the loosening process, the clamping force correlates well with the number of transverse vibration cycles when using a double-exponential equation. This equation reflects the strain relaxation and dynamic changes in the contact conditions at the friction interface of the threaded fasteners. The parameters of the double-exponential equation are related to the amplitude of the transverse vibration and the initial pre-tightening force. This function for the decaying clamping force provides an approach for quantitative predictions of the loosening of threaded fasteners.

An eccentric rotor does not only occur with dynamic loads, but also has vibrations with static loads. A unified formula is given for the air-gap length for an eccentric rotor considering both the dynamic and static eccentricities. The unbalanced magnetic pull (UMP) of the rotor is calculated numerically. Differential motion equations are given for the rotor system for the effect of UMP, static load (gravity), and unbalanced mass excitation. The rotor shaft orbit and displacement spectra are analyzed for a dynamic eccentricity and a mixed eccentricity with a static load. The direction and magnitude of the static eccentricity are related to the vibration characteristics of the rotor system. The results show that the static eccentricity angle affects the rotor shaft orbit and makes the displacement frequency component amplitudes vary periodically. A harmonic appears at four times the rotating speed with increasing static eccentricity. The effects of a static load on the rotor system can be regarded as a static eccentricity in the direction of the load.

Cable disturbances are a major disturbance source for high precision motion control of wafer scanners. The disturbances couple extra forces and couples to the system, which degrades the motion control system performance. This study analyzes the mechanics of a wafer scanner system and establishes a mathematical system model. Two time-varying parameters can be obtained for a generalized center of mass by an online recursive estimation algorithm to decouple the wafer scanner's four coils. Tests show that the online real-time dynamic decoupling strategy for a plane motor improves the self-adaptive ability, reduces the crosstalk between the three degrees of freedom (DOF), and improves the wafer scanner control.

Cutting temperature distributions were analyzed to determine the thermal deformation of “S” testing specimens. The cutting temperature field model was based on the heat distribution ratio for the tool-workpiece contact area. The intermittent cutting temperature model was based on the actual cutting process by combining heat sources, the heat distribution, and temperature measurements. The cutting heat distribution was optimized and the coolant application was simplified to a simple forced convection heat transfer coefficient. These boundary conditions were used in a finite element simulation of the cutting heat in “S” test specimens with the results verified against temperature measurements using thermocouples on a Parpas-PM20 five-axis computer numerical control (CNC) machine tool.

Crystal array decoding based on light sharing is one of the most efficient detector design schemes. However, detector module design depends heavily on the designer's experience and intuition and is largely based on trial and error. Simulations are needed to study the crystal array decoding and light sharing layer design. The GATE simulation toolkit is used to simulate a light sharing based detector with the reflectors in the light sharing layer then optimized by a column approximation optimization algorithm. Some key parameters in the simulation are then analyzed. The results show that the GATE simulation based optimization method can efficiently optimize the crystal array decoding in a light sharing detector.

The Stokes vector contains complete polarization information. Traditional measurements of the Stokes vector have commonly used a rotating polarizer, but this method cannot be used in real time. This paper presents a fast measurement method based on a twisted nematic (TN) liquid crystal and a polarizer. Light with the known polarization state is used to calibrate the device by calculating the first line of the Mueller matrix for the device. Then, the Stokes vector of the incident light is obtained by applying different voltages to the TN liquid crystal. The method is tested by measuring the incident angle of natural light reflected by a dielectric. The tested incident angles are 10°-70° with every 10° tested once. The results are 8.54°, 18.47°, 27.09°, 38.93°, 47.86°, 60.27°, and 70.89°. Thus, this method has similar accuracy to a rotating polarizer.

Foot-mounted inertial navigation systems (INS) having inexpensive micro electro mechanical system (MEMS)-based inertial sensors are widely used for pedestrian navigation. A foot-mounted INS can be combined with a magnetometer to constrain the heading angle error, but the magnetometer needs to be calibrated before use. This paper presents a magnetometer error model and an online calibration algorithm based on the foot-mounted INS characteristics. The magnetometer error characteristics and the foot-mounted INS mobility characteristics are used to develop a state equation and a magnetometer error measurement equation. An extended Kalman filter (EKF) is used for the online estimation and real-time calibration of the three-axis magnetometer errors with the zero velocity update (ZUPT) algorithm and a magnetic heading angle constraint algorithm for error constraint. The algorithm is validated by walking in a square playing ground. The results show that the online estimation and calibration algorithm reduce the end position error of the east direction from -110.7 to 1.8 m and the end position error of the north direction from 37.8 to 5.2 m compared to the system without calibration. This algorithm provides online calibration of magnetometer errors and significantly improves the positioning accuracy of pedestrian navigation.

Line width measurements are of great importance for detecting small objects. An algorithm is developed for sub-pixel line width measurements based on the orthogonal Legendre moment. The line width is converted into the sum of two different symmetrical line widths. The 0th, 2nd and 4th order orthogonal Legendre moments are used to develop expressions for the symmetrical line widths. Template coefficients of the moments are derived for analyzing digital images and the principle error is analyzed and corrected. Tests of the algorithm for measuring the line widths of standard particles in ampoules show that the algorithm is accurate and efficient.

Fire smoke exhaust systems in buildings need accurate designs of the smoke exhaust start-up time. The start-up time is mainly determined by expert experience or the performance of constant exhaust systems, which are very subjective. This paper describes a recursive solution method to calculate the smoke layer height that integrates empirical models. A sensitivity analysis method is then used to study the influence of the smoke exhaust start-up time on the smoke control. Methods are given to calculate the best start-up time, the risk start-up time, and the critical invalidation start-up time. These findings can be used to improve smoke exhaust systems.