In this article,current application,materials,key equipments,finite element(FE) simulation and parts properties of hot stamping are introduced.The investigations of all processes and further excellent processes are de...In this article,current application,materials,key equipments,finite element(FE) simulation and parts properties of hot stamping are introduced.The investigations of all processes and further excellent processes are described.The survey of existing works,especially key equipments has revealed several gaps.Some new ideas and programs are proposed on the basis of traditional process.This article aims at providing an insight into a whole process backgrounds and pointing out the great potential for further investigations and innovations of hot stamping.展开更多
In this paper,a novel UWB communication system structure is proposed.The transmitted signal uses OOK modulation and chirp spread spectrum.The received signal first goes through a dechirp pulse compression process,and ...In this paper,a novel UWB communication system structure is proposed.The transmitted signal uses OOK modulation and chirp spread spectrum.The received signal first goes through a dechirp pulse compression process,and then is processed with a two-level sliding correlation algorithm for coarse timing synchronization and fine timing synchronization.After the SNR estimation,the signal is demodulated by an energy detection method.An integrated system level simulation model is established,and the performance of this system is evaluated over the AWGN channel,IEEE 802.15.3a CM1 and CM4 channels.The theoretical analysis and simulation results show that this UWB communication system can effectively reduce the sampling rate and signal processing speed at the receiver,and it is more suitable for long-distance and low-rate UWB communications with high spreading gain.展开更多
Schottky-contacted sensors have been demonstrated to show high sensitivity and fast response time in various sensing systems.In order to improve their sensing performance,the Schottky barriers height(SBH)at the interf...Schottky-contacted sensors have been demonstrated to show high sensitivity and fast response time in various sensing systems.In order to improve their sensing performance,the Schottky barriers height(SBH)at the interface of semiconductor and metal electrode should be adjusted to appropriate range to avoid low output or low sensitivity,which was induced by excessively high or low SBH,respectively.In this work,a simple and effective SBH tuning method by triboelectric generator(TENG)is proposed,the SBH can be effectively lowered by voltage pulses generated by TENG and gradually recover over time after withdrawing the TENG.Through combining the TENG treatment with piezotronic effect,a synergistic effect on lowering SBH was achieved.The change of SBH is increased by 3.8 to 12.8 times,compared with dependent TENG treatment and piezotronic effect,respectively.Furthermore,the recovery time of the TENG-lowered SBH can be greatly shortened from 1.5 h to 40 s by piezotronic effect.This work demonstrated a flexible and feasible SBH tuning method,which can be used to effectively improve the sensitivity of Schottky-contact sensor and sensing system.Our study also shows great potential in broadening the application scenarios of Schottky-contacted electronic devices.展开更多
基金National Science and Technology Supporting Program of China(No.2011BAG03B02)
文摘In this article,current application,materials,key equipments,finite element(FE) simulation and parts properties of hot stamping are introduced.The investigations of all processes and further excellent processes are described.The survey of existing works,especially key equipments has revealed several gaps.Some new ideas and programs are proposed on the basis of traditional process.This article aims at providing an insight into a whole process backgrounds and pointing out the great potential for further investigations and innovations of hot stamping.
基金Supported by the National High Technology Research and Development Program of China(No.2009 AA011202,2009AA011205)the National Science and Technology Major Project of China(No.2009ZX03006-007)
文摘In this paper,a novel UWB communication system structure is proposed.The transmitted signal uses OOK modulation and chirp spread spectrum.The received signal first goes through a dechirp pulse compression process,and then is processed with a two-level sliding correlation algorithm for coarse timing synchronization and fine timing synchronization.After the SNR estimation,the signal is demodulated by an energy detection method.An integrated system level simulation model is established,and the performance of this system is evaluated over the AWGN channel,IEEE 802.15.3a CM1 and CM4 channels.The theoretical analysis and simulation results show that this UWB communication system can effectively reduce the sampling rate and signal processing speed at the receiver,and it is more suitable for long-distance and low-rate UWB communications with high spreading gain.
基金the National Key R&D Program of China(2016YFA0202703)Key-Area Research and Development Program of Guangdong Province(2018B030331001)+3 种基金the National Natural Science Foundation of China(61875015,81971770,52002027,and 82071970)Beijing Natural Science Foundation(JQ20038,2214083)China National Postdoctoral Program for Innovative Talent(BX20200380)the Fundamental Research Funds for the Central Universities。
文摘Schottky-contacted sensors have been demonstrated to show high sensitivity and fast response time in various sensing systems.In order to improve their sensing performance,the Schottky barriers height(SBH)at the interface of semiconductor and metal electrode should be adjusted to appropriate range to avoid low output or low sensitivity,which was induced by excessively high or low SBH,respectively.In this work,a simple and effective SBH tuning method by triboelectric generator(TENG)is proposed,the SBH can be effectively lowered by voltage pulses generated by TENG and gradually recover over time after withdrawing the TENG.Through combining the TENG treatment with piezotronic effect,a synergistic effect on lowering SBH was achieved.The change of SBH is increased by 3.8 to 12.8 times,compared with dependent TENG treatment and piezotronic effect,respectively.Furthermore,the recovery time of the TENG-lowered SBH can be greatly shortened from 1.5 h to 40 s by piezotronic effect.This work demonstrated a flexible and feasible SBH tuning method,which can be used to effectively improve the sensitivity of Schottky-contact sensor and sensing system.Our study also shows great potential in broadening the application scenarios of Schottky-contacted electronic devices.
