Calibration of Camera with Large Field-of-View Based on Flexible Planar Target

For high precision calibration of camera with large field-of-view,massive calibration points will be needed if traditional methods are selected,which makes the calibration complex and time-consuming.In order to solve this problem,a calibration method based on flexible planar target is proposed.In this method,distortion factor is firstly acquired by the invariance of cross ratio,and existing feature points are adjusted with the distortion factor.Then,a large number of points that will be used for the calibration are constructed with the adjusted feature points.Simultaneously,Tsai method is modified so as to reduce the complexity of calibration,which makes the process linear.The simulation and real experiments show that the method proposed in this paper is simple,linear,accurate and robust,and the precision of this method is close to that of Tsai method using abundant points.The method can satisfy the requirement of high precision calibration for camera with large field-of-view.

Asymmetric Three-Phase Cascading Trinary-DC Source Multilevel Inverter Topologies for Variable Frequency PWM

Asymmetric three-phase cascading Trinary-DC source Multilevel Inverter which can achieve reduced harmonics and superior root mean square (RMS) values of the output voltage is proposed. This topology can achieve cascaded full bridge inverter operation with dissimilar (unequal) DC Source and it is fired by using variable frequency pulse with modulation technique as a switching strategy. This pulse width modulation switching strategy has a newly adopted multicarrier single reference technique. The performance parameter factors like Form Factor (FF), Crest Factor (CF), Total Harmonic Distortion (THD) and fundamental RMS output voltage (VRMS) are estimated by using proposed asymmetrical three-phase cascading multilevel inverter for several modulation indices (0.8 - 1). The research study carries with MATLAB/SIMULINK based simulation and experimental results obtained using appropriate prototype (test board) to prove the viability of the proposed concept.

The Threshold Effect of Factor Price Distortion on Technological Content of Exports:Evidence from China

Using panel data from 31 provinces in China,covering the period from 2003 to 2017,this article analyzes the threshold effect of factor price distortion on the technological content of exports.The results show that factor price distortion does not necessarily impede improvement in the quality of the technological content of exports.Instead,the adverse ejfect can be weakened when the value of per capita GDP is higher than RMB13,154 or the value of FDI goes beyond RMB480.9 billion.This is because a high regional economic development level alleviates the adverse effect of factor price distortion on the technological content of exports.Our results are robust when the dependent variable and sample years are changed.This article also addresses the endogeneity issue.We also consider the underlying mechanism through which factor price distortion affects the technological content of exports.

Exchange Rate Change, Factor Market Distortion and Company Performance

Based on the matched data of China’s tax survey and customs from 2007 to 2011,this paper studies the differential impact of exchange rate changes on the performance of companies by region from the perspective of factor market distortion.The results show that for import companies,the RMB appreciation significantly contributes to improving their performance and this phenomenon is more pronounced in areas with high factor market distortions.Channel tests show that the proportion of intermediate goods imported by final producers increases with regional factor market distortions.Therefore,the appreciation of the national currency is more favorable for areas with high factor market distortions(companies with high proportion of imported intermediate goods).In addition,the appreciation of the national currency will promote the production of China’s upstream intermediate goods producers by expanding the output of downstream enterprises.This paper complements previous studies on the differential impact of RMB exchange rate changes on regional economic growth from a micro perspective.