In order to improve the characteristics of a conventional moving coil permanent magnet linear motor （MCPMLM）, such as weak points on export force, response time, response speed, we studied a permanent magnet （PM） ...In order to improve the characteristics of a conventional moving coil permanent magnet linear motor （MCPMLM）, such as weak points on export force, response time, response speed, we studied a permanent magnet （PM） structure that is a key component of MCPMLM. Different magnetization techniques of single PM and differ- ent array structures of multiple PMs are compared, and a new MCPMLM magnetized along the external field force lines wing eight pieces of a tegular Halbach magnet array with air gaps is proposed as well. The analysis on magnetic field and experimental results of MCPMLM demonstrates that the force between the coil and the PM increases by more than 40%. The simulation frequeney is close to 350 Hz at -3 dB , and the response time is O. 005 s. In addition, the experiment frequency reaches 300 Hz at -3 dB and the response time is 0. 004 s, which agrees well with the simulation results. It means that the developed MCPMLM enjoys advantages in high frequency and rapid response, and can satisfy the requirements of a high speed electro-hydraulic proportional valve.展开更多
With the rapid development of artificial intelligence and the widespread use of the Internet of Things, semantic communication, as an emerging communication paradigm, has been attracting great interest. Taking image t...With the rapid development of artificial intelligence and the widespread use of the Internet of Things, semantic communication, as an emerging communication paradigm, has been attracting great interest. Taking image transmission as an example, from the semantic communication's view, not all pixels in the images are equally important for certain receivers. The existing semantic communication systems directly perform semantic encoding and decoding on the whole image, in which the region of interest cannot be identified. In this paper, we propose a novel semantic communication system for image transmission that can distinguish between Regions Of Interest (ROI) and Regions Of Non-Interest (RONI) based on semantic segmentation, where a semantic segmentation algorithm is used to classify each pixel of the image and distinguish ROI and RONI. The system also enables high-quality transmission of ROI with lower communication overheads by transmissions through different semantic communication networks with different bandwidth requirements. An improved metric θPSNR is proposed to evaluate the transmission accuracy of the novel semantic transmission network. Experimental results show that our proposed system achieves a significant performance improvement compared with existing approaches, namely, existing semantic communication approaches and the conventional approach without semantics.展开更多
A termetallic catalyst of Pt-Ir-Au/Al2O3 for NOx decomposition was prepared by loading the metallic colloids in C2H5OH-H2O solution and a surfactant of polyvinyl pyrrolidone.Compared with an impregnated Pt/Al2O3 catal...A termetallic catalyst of Pt-Ir-Au/Al2O3 for NOx decomposition was prepared by loading the metallic colloids in C2H5OH-H2O solution and a surfactant of polyvinyl pyrrolidone.Compared with an impregnated Pt/Al2O3 catalyst,the termetallic catalyst of PtIrAu811/Al2O3,with a Pt：Ir：Au atomic ratio of 8：1：1,exhibited higher NO decomposition and selectivity to N2.Transmission electron microscopy and X-ray diffraction were conducted to clarify the state of the supported metals and indicate three precious metals alloyed on the catalyst.In the study of NO-temperature programmed desorption,oxygen desorption on the PtIrAu811 catalyst shifted to the low temperature side compared to that on Pt/Al2O3,which correlated well with its higher catalytic performance in NO decomposition.展开更多
Solution-processed colloidal quantum dot solar cells(CQDSCs) is a promising candidate for new generation solar cells.To obtain stable and high performance lead sulfide(PbS)-based CQDSCs,high carrier mobility and low n...Solution-processed colloidal quantum dot solar cells(CQDSCs) is a promising candidate for new generation solar cells.To obtain stable and high performance lead sulfide(PbS)-based CQDSCs,high carrier mobility and low non-radiative recombination center density in the PbS CQDs active layer are required.In order to effectively improve the carrier mobility in PbS CQDs layer of CQDSCs,butylamine(BTA)-modified graphene oxide(BTA@GO) is first utilized in PbS-PbX2(X=I-,Br-) CQDs ink to deposit the active layer of CQDSCs through one-step spin-coating method.Such surface treatment of GO dramatically upholds the intrinsic superior hole transfer peculiarity of GO and attenuates the hydrophilicity of GO in order to allow for its good dispersibility in ink solvent.The introduction of B TA@GO in CQDs layer can build up a bulk nano-heterojunction architecture,which provides a smooth charge carrier transport channel in turn improves the carrier mobility and conductivity,extends the carriers lifetime and reduces the trap density of PbS-PbX2 CQDs film.Finally,the BTA@GO/PbS-PbX2 hybrid CQDs film-based relatively large-area(0.35 cm2) CQDSCs shows a champion power conversion efficiency of 11.7% which is increased by 23.1% compared with the control device.展开更多
Cyclic variability is a factor adversely affecting engine performance. In this paper a cyclic moving average regulation approach to cylinder pressure at top dead center （TDC） is proposed, where the ignition time is ...Cyclic variability is a factor adversely affecting engine performance. In this paper a cyclic moving average regulation approach to cylinder pressure at top dead center （TDC） is proposed, where the ignition time is adopted as the control input. The dynamics from ignition time to the moving average index is described by ARMA model. With this model, a one-step ahead prediction-based minimum variance controller （MVC） is developed for regulation. The performance of the proposed controller is illustrated by experiments with a commercial car engine and experimental results show that the controller has a reliable effect on index regulation when the engine works under different fuel injection strategies, load changing and throttle opening disturbance.展开更多
Future vehicular Internet-of-Things(IoT)systems feature a large number of devices and multi-access environments where different types of communication,computing,and storage resources must be efficiently utilized.At th...Future vehicular Internet-of-Things(IoT)systems feature a large number of devices and multi-access environments where different types of communication,computing,and storage resources must be efficiently utilized.At the same time,novel services such as cooperative autonomous driving and intelligent transportation systems(ITS),that demand unprecedented high accuracy,ultra-low latency,and large bandwidth,are emerging.展开更多
Most products have the potential to negatively impact the environment during all life-cycle stages.However,most environmental impact assessment methods focus on a single product life-cycle and on a specific life-cycle ...Most products have the potential to negatively impact the environment during all life-cycle stages.However,most environmental impact assessment methods focus on a single product life-cycle and on a specific life-cycle stage.Product design plays a significant role by determining traditional environmental impacts,such as embodied energy of materials,but also by influencing market adoption and production volumes.The main objective of this work is to develop a design optimization framework that estimates the environmental impact of design decisions(e.g.materials choice,etc.)across all life-cycle stages in consumer products.The methodology relies on quality function deployment(QFD),multi-attribute utility theory,non-linear mathematical programming,and life-cycle assess-ment tools to estimate the utility of the design options to the customer,the producer,and the environment.The proposed framework allows designers and other decision makers to select options that are environmentally sound and also aligned with the business objectives.展开更多
As an accurate 2D/3D fabrication tool,inkjet printing technology has great potential in preparation of micro electronic devices.The morphology of droplets produced by the inkjet printer has a great impact on the accur...As an accurate 2D/3D fabrication tool,inkjet printing technology has great potential in preparation of micro electronic devices.The morphology of droplets produced by the inkjet printer has a great impact on the accuracy of deposition.In this study,the drop-on-demand(DoD)inkjet simulation model was established,and the accuracy of the simulation model was verified by corresponding experiments.The simulation result shows that the velocity of the droplet front and tail,as well as the time to disconnect from the nozzle is mainly affected by density(ρ),viscosity(μ)and surface tension(σ)of droplets.When the liquid filament is about to disconnect from the nozzle,the filament length and filament front velocity are found to have a linear correlation withσ/ρμand ln(ρ/(μσ1/2)).展开更多
The development of vehicle integrated photovoltaics-powered electric vehicles (VIPV-EV) significantly reduces CO<sub>2</sub> emissions from the transport sector to realize a decarbonized society. Although ...The development of vehicle integrated photovoltaics-powered electric vehicles (VIPV-EV) significantly reduces CO<sub>2</sub> emissions from the transport sector to realize a decarbonized society. Although long-distance driving of VIPV-EV without electricity charging is expected in sunny regions, driving distance of VIPV-EV is affected by climate conditions such as solar irradiation and temperature rise of PV modules. In this paper, detailed analytical results for effects of climate conditions such as solar irradiation and temperature rise of PV modules upon driving distance of the VIPV-EV were presented by using test data for Toyota Prius and Nissan Van demonstration cars installed with high-efficiency InGaP/GaAs/InGaAs 3-junction solar cell modules with a module efficiency of more than 30%. The temperature rise of some PV modules studied in this study was shown to be expressed by some coefficients related to solar irradiation, wind speed and radiative cooling. The potential of VIPV-EV to be deployed in 10 major cities was also analyzed. Although sunshine cities such as Phoenix show the high reduction ratio of driving range with 17% due to temperature rise of VIPV modules, populous cities such as Tokyo show low reduction ratio of 9%. It was also shown in this paper that the difference between the driving distance of VIPV-EV driving in the morning and the afternoon is due to PV modules’ radiative cooling. In addition, the importance of heat dissipation of PV modules and the development of high-efficiency PV modules with better temperature coefficients was suggested in order to expand driving range of VIPV-EV. The effects of air-conditioner usage and partial shading in addition to the effects of temperature rise of VIPV modules were suggested as the other power losses of VIPV-EV.展开更多
基金supported by The National High Technology Research and Development of China (863 Programme) under Grant No. 2006AA09Z226
文摘In order to improve the characteristics of a conventional moving coil permanent magnet linear motor （MCPMLM）, such as weak points on export force, response time, response speed, we studied a permanent magnet （PM） structure that is a key component of MCPMLM. Different magnetization techniques of single PM and differ- ent array structures of multiple PMs are compared, and a new MCPMLM magnetized along the external field force lines wing eight pieces of a tegular Halbach magnet array with air gaps is proposed as well. The analysis on magnetic field and experimental results of MCPMLM demonstrates that the force between the coil and the PM increases by more than 40%. The simulation frequeney is close to 350 Hz at -3 dB , and the response time is O. 005 s. In addition, the experiment frequency reaches 300 Hz at -3 dB and the response time is 0. 004 s, which agrees well with the simulation results. It means that the developed MCPMLM enjoys advantages in high frequency and rapid response, and can satisfy the requirements of a high speed electro-hydraulic proportional valve.
基金supported in part by collaborative research with Toyota Motor Corporation,in part by ROIS NII Open Collaborative Research under Grant 21S0601,in part by JSPS KAKENHI under Grants 20H00592,21H03424.
文摘With the rapid development of artificial intelligence and the widespread use of the Internet of Things, semantic communication, as an emerging communication paradigm, has been attracting great interest. Taking image transmission as an example, from the semantic communication's view, not all pixels in the images are equally important for certain receivers. The existing semantic communication systems directly perform semantic encoding and decoding on the whole image, in which the region of interest cannot be identified. In this paper, we propose a novel semantic communication system for image transmission that can distinguish between Regions Of Interest (ROI) and Regions Of Non-Interest (RONI) based on semantic segmentation, where a semantic segmentation algorithm is used to classify each pixel of the image and distinguish ROI and RONI. The system also enables high-quality transmission of ROI with lower communication overheads by transmissions through different semantic communication networks with different bandwidth requirements. An improved metric θPSNR is proposed to evaluate the transmission accuracy of the novel semantic transmission network. Experimental results show that our proposed system achieves a significant performance improvement compared with existing approaches, namely, existing semantic communication approaches and the conventional approach without semantics.
文摘A termetallic catalyst of Pt-Ir-Au/Al2O3 for NOx decomposition was prepared by loading the metallic colloids in C2H5OH-H2O solution and a surfactant of polyvinyl pyrrolidone.Compared with an impregnated Pt/Al2O3 catalyst,the termetallic catalyst of PtIrAu811/Al2O3,with a Pt：Ir：Au atomic ratio of 8：1：1,exhibited higher NO decomposition and selectivity to N2.Transmission electron microscopy and X-ray diffraction were conducted to clarify the state of the supported metals and indicate three precious metals alloyed on the catalyst.In the study of NO-temperature programmed desorption,oxygen desorption on the PtIrAu811 catalyst shifted to the low temperature side compared to that on Pt/Al2O3,which correlated well with its higher catalytic performance in NO decomposition.
基金supported by the Japan Science and Technology Agency(JST)CREST programBeijing Advanced Innovation Center for Future Urban Design,Beijing University of Civil Engineering and Architecture(Grant UDC2018031121)+3 种基金the MEXT KAKENHI(Grant 17H02736)the Natural Science Foundation of Shaanxi Province(2019JQ-423)the Fundamental Research Funds for the Central Universities(GK201903053)Key Lab of Photovoltaic and Energy Conservation Materials,Chinese Academy of Sciences(No.PECL2019KF019)for financial support.
文摘Solution-processed colloidal quantum dot solar cells(CQDSCs) is a promising candidate for new generation solar cells.To obtain stable and high performance lead sulfide(PbS)-based CQDSCs,high carrier mobility and low non-radiative recombination center density in the PbS CQDs active layer are required.In order to effectively improve the carrier mobility in PbS CQDs layer of CQDSCs,butylamine(BTA)-modified graphene oxide(BTA@GO) is first utilized in PbS-PbX2(X=I-,Br-) CQDs ink to deposit the active layer of CQDSCs through one-step spin-coating method.Such surface treatment of GO dramatically upholds the intrinsic superior hole transfer peculiarity of GO and attenuates the hydrophilicity of GO in order to allow for its good dispersibility in ink solvent.The introduction of B TA@GO in CQDs layer can build up a bulk nano-heterojunction architecture,which provides a smooth charge carrier transport channel in turn improves the carrier mobility and conductivity,extends the carriers lifetime and reduces the trap density of PbS-PbX2 CQDs film.Finally,the BTA@GO/PbS-PbX2 hybrid CQDs film-based relatively large-area(0.35 cm2) CQDSCs shows a champion power conversion efficiency of 11.7% which is increased by 23.1% compared with the control device.
文摘Cyclic variability is a factor adversely affecting engine performance. In this paper a cyclic moving average regulation approach to cylinder pressure at top dead center （TDC） is proposed, where the ignition time is adopted as the control input. The dynamics from ignition time to the moving average index is described by ARMA model. With this model, a one-step ahead prediction-based minimum variance controller （MVC） is developed for regulation. The performance of the proposed controller is illustrated by experiments with a commercial car engine and experimental results show that the controller has a reliable effect on index regulation when the engine works under different fuel injection strategies, load changing and throttle opening disturbance.
文摘Future vehicular Internet-of-Things(IoT)systems feature a large number of devices and multi-access environments where different types of communication,computing,and storage resources must be efficiently utilized.At the same time,novel services such as cooperative autonomous driving and intelligent transportation systems(ITS),that demand unprecedented high accuracy,ultra-low latency,and large bandwidth,are emerging.
文摘Most products have the potential to negatively impact the environment during all life-cycle stages.However,most environmental impact assessment methods focus on a single product life-cycle and on a specific life-cycle stage.Product design plays a significant role by determining traditional environmental impacts,such as embodied energy of materials,but also by influencing market adoption and production volumes.The main objective of this work is to develop a design optimization framework that estimates the environmental impact of design decisions(e.g.materials choice,etc.)across all life-cycle stages in consumer products.The methodology relies on quality function deployment(QFD),multi-attribute utility theory,non-linear mathematical programming,and life-cycle assess-ment tools to estimate the utility of the design options to the customer,the producer,and the environment.The proposed framework allows designers and other decision makers to select options that are environmentally sound and also aligned with the business objectives.
基金supported by the Tsinghua University–Toyota Research Center Project。
文摘As an accurate 2D/3D fabrication tool,inkjet printing technology has great potential in preparation of micro electronic devices.The morphology of droplets produced by the inkjet printer has a great impact on the accuracy of deposition.In this study,the drop-on-demand(DoD)inkjet simulation model was established,and the accuracy of the simulation model was verified by corresponding experiments.The simulation result shows that the velocity of the droplet front and tail,as well as the time to disconnect from the nozzle is mainly affected by density(ρ),viscosity(μ)and surface tension(σ)of droplets.When the liquid filament is about to disconnect from the nozzle,the filament length and filament front velocity are found to have a linear correlation withσ/ρμand ln(ρ/(μσ1/2)).
文摘The development of vehicle integrated photovoltaics-powered electric vehicles (VIPV-EV) significantly reduces CO<sub>2</sub> emissions from the transport sector to realize a decarbonized society. Although long-distance driving of VIPV-EV without electricity charging is expected in sunny regions, driving distance of VIPV-EV is affected by climate conditions such as solar irradiation and temperature rise of PV modules. In this paper, detailed analytical results for effects of climate conditions such as solar irradiation and temperature rise of PV modules upon driving distance of the VIPV-EV were presented by using test data for Toyota Prius and Nissan Van demonstration cars installed with high-efficiency InGaP/GaAs/InGaAs 3-junction solar cell modules with a module efficiency of more than 30%. The temperature rise of some PV modules studied in this study was shown to be expressed by some coefficients related to solar irradiation, wind speed and radiative cooling. The potential of VIPV-EV to be deployed in 10 major cities was also analyzed. Although sunshine cities such as Phoenix show the high reduction ratio of driving range with 17% due to temperature rise of VIPV modules, populous cities such as Tokyo show low reduction ratio of 9%. It was also shown in this paper that the difference between the driving distance of VIPV-EV driving in the morning and the afternoon is due to PV modules’ radiative cooling. In addition, the importance of heat dissipation of PV modules and the development of high-efficiency PV modules with better temperature coefficients was suggested in order to expand driving range of VIPV-EV. The effects of air-conditioner usage and partial shading in addition to the effects of temperature rise of VIPV modules were suggested as the other power losses of VIPV-EV.
