An Accurate Calibration Means for the Phase Measuring Deflectometry System

Calibration is a critical step for the phase measuring deflectometry system. Existing calibration methods are mainly optimizing the calibration parameters with respect to the 2D re-projection error criterion. However, such a procedure cannot reduce metric errors in the practical application. Therefore, an accurate and practical calibration method is proposed. In which, conventional calibration means is first applied for the primary calibration. Then, a precise square planar mirror is used for the optimization of system calibration parameters. All the intrinsic and extrinsic parameters are considered as a global multi-objective optimization problem. Three metric error criteria are introduced to evaluate the 3D reconstruction accuracy of the reference mirror. Compared with classical calibration means, which apply the parameter optimization in 2D image space to minimize the re-projection errors, the proposed optimization approach is executed in 3D space directly. An experiment and comparison are conducted to verify that the proposed optimal calibration approach can effectively reduce the system deviation and to improve the system measurement accuracy.

Risks in Prefabricated Buildings in China: Importance-Performance Analysis Approach

Prefabrication has drawn wide attention in China during the last decade. However, the market share of prefabricated buildings in China remains comparatively low. The Importance-Performance Analysis approach is employed in this study to investigate the crucial risk factors associated with prefabricated buildings in China. A preliminary list of risks associated with prefabricated buildings in China was developed based on a critical literature review, which was consequently refined by the interview with related experts. A questionnaire survey was then conducted with selected industry professionals to solicit their expert opinions of critical risks associated with prefabricated buildings in China. Findings show that attention should be paid to the following risks: improper decomposition system, low level of factory management, incompetent quality assurance system, deviation in specification of prefabricated components, defects of component system, missing catalogue of building parts and components, poor adaptability of prefabricated building during the operational stage, and lack of actual cases to prove the environmental benefits of prefabricated buildings. This study also revealed the discrepancy between perceived critical risks and those risks with comparatively lower management performance. These findings offer useful inputs for the future development of prefabricated buildings in China and beyond.

Crystal structure of 4-azidomethyl-6-tert-butyl-2H-chromen-2-one

In the title compound, C14H15N3O2, one of the methyl C atoms of thetert-butyl group lies almost in the plane of the chromene ring system [deviation = −0.097 (2) Å], one lies above and one lies below [deviations = 1.460 (3) and 1.006 (3) Å, respectively]. The C—C—N—N torsion angle is 142.33 (17)°. In the crystal, moelcules are linked by weak C—H...O hydrogen bonds to generateC(6) chains propagating in the [010] direction.

Improved Different Dimensional Sensors Combined Space Registration Algorithm

To address the problem of deviation and registration of 3D radar and infrared sensor, this paper presents and improves a method based on the state value and space deviation of federated filtering of unscented Kalman filter and standard Kalman filter, which conduces to real time registering of system deviation of radar and IF sensors. In the method presented here, a covariance matching criteria-based approach was employed for judgment of filtering divergent trend, while self-adaptive attenuation factor was introduced for correction of the predicted error covariance so as to inhibit the divergent phenomenon. The experiment results indicated that the method presented here conduces to improvement of the precision and speed of space registration, showing practical value in deviation registration of 3D radars and infrared sensors.

Stochastic Robust Hybrid Observer With Applications to Automotive Slip Angle Estimation

In this article, the state estimation for Automotive Slip Angle considering the measurement noise in sensor is addressed. Real-time measurement of the slip angle is applicable to many active vehicle safety applications, such as rollover prevention and yaw stability control. As the sensors that measure slip angle directly are expensive, the method to extract slip angle from other available sensors in vehicle is considered. First from the simplified nonlinear dynamic system of vehicle, a Piecewise Affine (PWA) model with calculated uncertainties is obtained. The uncertainties are the result of nonlinear system deviation from PWA model. Then using the PWA model, a Stochastic Robust Hybrid Observer design is developed to estimate the slip angle. Design of the Observer is based on Linear Matrix Inequalities which gives bound on the estimation variance based on the sensor noise measurements. Finally, through simulation, the effectiveness and performance of this method is investigated.

An Intelligent Control System for Edge Position Deviation of Narrow Fabrics

Focused on the S-shape deviation problem in the narrow fabric production process, this paper introduces an intelligent control system with DC servomotor as the actuator for an intermediate guide roll system. To improve the dynamic performance of the deviation control system and solve the motor vibration problem, the deviation control algorithm is proposed, which is related to intelligent PD feedback control combined with the feed-forward regulation for the system deviation, and its MatLab simulation results show its good performances and advantages. Furthermore, a technical approach for the deviation controller using DSP processor chip TMS320F2812 is presented. The system is applied in the intermediate guide roll system, and the application result indicates that the system is characterized by fast response and steady operation and it is a good solution for the motor vibration.