It is shown in this article that by changing the initial operation condition of the batch processes, the dynamic performance of the system can be varied largely, especially for the initial operational temperature of t...It is shown in this article that by changing the initial operation condition of the batch processes, the dynamic performance of the system can be varied largely, especially for the initial operational temperature of the exothermic reaction. The initial operation condition is often ignored in the designing batch processes for flexibility against disturbances or parameter variations. When the initial condition is not rigid as in the case of a batch reactor, where the initial reaction temperature is quite arbitrary, optimization can also be applied to determine the ＂best＂ initial condition to use. Problems for dynamic flexibility analysis of exothermic reaction including initial temperature and process operation can be formulated as dynamic optimization problems. Formulations are derived when the initial conditions are considered or not. When the initial conditions are considered, the initial condition can be transferred into control variables in the first optimal step. The solution of the dynamic optimization is on the basis of Rugge-Kutta integration algorithm and decomposition search algorithm. This method, as illustrated and tested with two highly nonlinear process problems, enables the determination of the optimal level. The dynamic performance is improved by the proposed method in the two exothermic reaction examples.展开更多
The fluctuation in Ommastrephe bartrami yield from 1995 to 2001 in the North Pacific was shown obvious, on which this study was conducted using data of sea surface temperature （SST）, chlorophyll-a （chl-α） and sta...The fluctuation in Ommastrephe bartrami yield from 1995 to 2001 in the North Pacific was shown obvious, on which this study was conducted using data of sea surface temperature （SST）, chlorophyll-a （chl-α） and statistical production. The study shows that, cool water and low food abundance caused by abnormal Kuroshio resulted in the reduction in abundance of O. bartrami, which was worsened by excessive catch and the unawareness to local fishery resources protection.展开更多
To enhance the serviceability of steel bridge deck pavement(SBDP)in high-temperature and rainy regions,a concept of rigid bottom and flexible top was summarized using engineering practices,which led to the proposal of...To enhance the serviceability of steel bridge deck pavement(SBDP)in high-temperature and rainy regions,a concept of rigid bottom and flexible top was summarized using engineering practices,which led to the proposal of a three-layer ultra-high-performance pavement(UHPP).The high-temperature rutting resistance and wet-weather skid resistance of UHPP were evaluated through composite structure tests.The internal temperature distribution within the pavement under typical high-temperature conditions was analyzed using a temperature field model.Additionally,a temperature-stress coupling model was employed to investigate the key load positions and stress response characteristics of the UHPP.The results indicate that compared with the traditional guss asphalt+stone mastic asphalt structure,the dynamic stability of the UHPP composite structure can be improved by up to 20.4%.Even under cyclic loading,UHPP still exhibits superior surface skid resistance compared to two traditional SBDPs.The thickness composition of UHPP significantly impacts its rutting resistance and skid resistance.UHPP exhibits relatively low tensile stress but higher shear stress levels,with the highest shear stress occurring between the UHPP and the steel plate.This suggests that the potential risk of damage for UHPP primarily lies within the interlayer of the pavement.Based on engineering examples,introducing interlayer gravel and optimizing the amount of bonding layer are advised to ensure that UHPP possesses sufficient interlayer shear resistance.展开更多
Most of the supercapacitors reported in literatures showed little or no flexibility in the working temperature around 150℃. However, the supercapacitors are generally exposed under complex system or extreme temperatu...Most of the supercapacitors reported in literatures showed little or no flexibility in the working temperature around 150℃. However, the supercapacitors are generally exposed under complex system or extreme temperature, such as electric vehicles and extremely cold area. Herein, we successfully fabricated a large-scale robust nanocarbon hybrid film consisting of reduced graphene oxide (rGO), carbon nanotubes (CNTs) and MnOx nano-flowers with the size up to 550 cm^2. The mechanical properties of the hybrid films depend on the ratio o f CNTs. The supercapacitors prepared with the hybrid films exhibit high flexibility and keep their performances in a temperature range from - 20 to 200℃. In addition, the devices display remarkable electrochemical and deformation stability at extrem e temperature. This strategy has a potential for the more efficient preparation of flexible electrode materials.展开更多
With the rapid development of portable devices and internet of things,the requirement of system wearability and integration accelerates the investigation of flexible multifunctional sensors.In this study,we developed ...With the rapid development of portable devices and internet of things,the requirement of system wearability and integration accelerates the investigation of flexible multifunctional sensors.In this study,we developed an integrated flexible sensing system with four nanowire-based sensors and a Ni microwire-based temperature sensor.The four nanowirebased sensors are three kinds of photodetectors responding to lights with different wavelengths and a gas sensor.Due to the large surface volume ratio and considerable sub wavelength effect,all the nanowire-based sensors show good sensing response and excellent linear relationship between sensitivity and temperature.The as-fabricated flexible sensing system can simultaneously detect environmental parameters,including temperature change,light intensities from UV-Visible to near infrared regions,and harmful gas concentration.Our flexible multifunctional sensing system therefore opens up a new way for the emerging portable and wearable electronics.展开更多
Graphene emerges as an ideal material for constructing high-performance strain sensors,due to its superior mechanical property and high conductivity.However,in the process of assembling graphene into macroscopic mater...Graphene emerges as an ideal material for constructing high-performance strain sensors,due to its superior mechanical property and high conductivity.However,in the process of assembling graphene into macroscopic materials,its conductivity decreases significantly.Also,tedious fabrication process hinders the application of graphene-based strain sensors.In this work,we report a freestanding graphene assembled film(GAF)with high conductivity((2.32±0.08)×105 S m-1).For the sensitive materials of strain sensors,it is higher than most of reported carbon nanotube and graphene materials.These advantages enable the GAF to be an ultra-low power consumption strain sensor for detecting airflow and vocal vibrations.The resistance of the GAF remains unchanged with increasing temperature(20-100℃),exhibiting a good thermal stability.Also,the GAF can be used as a strain sensor directly without any flexible substrates,which greatly simplifies the fabrication process in comparison with most reported strain sensors.Additionally,the GAF used as a pressure sensor with only^4.7μW power is investigated.This work provides a new direction for the preparation of advanced sensors with ultra-low power consumption,and the development of flexible and energy-saving electronic devices.展开更多
基金Supported by the National Natural Science Foundation of China （20536020, 20876056）.
文摘It is shown in this article that by changing the initial operation condition of the batch processes, the dynamic performance of the system can be varied largely, especially for the initial operational temperature of the exothermic reaction. The initial operation condition is often ignored in the designing batch processes for flexibility against disturbances or parameter variations. When the initial condition is not rigid as in the case of a batch reactor, where the initial reaction temperature is quite arbitrary, optimization can also be applied to determine the ＂best＂ initial condition to use. Problems for dynamic flexibility analysis of exothermic reaction including initial temperature and process operation can be formulated as dynamic optimization problems. Formulations are derived when the initial conditions are considered or not. When the initial conditions are considered, the initial condition can be transferred into control variables in the first optimal step. The solution of the dynamic optimization is on the basis of Rugge-Kutta integration algorithm and decomposition search algorithm. This method, as illustrated and tested with two highly nonlinear process problems, enables the determination of the optimal level. The dynamic performance is improved by the proposed method in the two exothermic reaction examples.
基金Supported by National Key Project for Basic Research of China (2005CB422300)
文摘The fluctuation in Ommastrephe bartrami yield from 1995 to 2001 in the North Pacific was shown obvious, on which this study was conducted using data of sea surface temperature （SST）, chlorophyll-a （chl-α） and statistical production. The study shows that, cool water and low food abundance caused by abnormal Kuroshio resulted in the reduction in abundance of O. bartrami, which was worsened by excessive catch and the unawareness to local fishery resources protection.
基金The National Natural Science Foundation of China(No.51878167)the Postgraduate Research and Practice Innovation Program of Jiangsu Province(No.KYCX23_0300).
文摘To enhance the serviceability of steel bridge deck pavement(SBDP)in high-temperature and rainy regions,a concept of rigid bottom and flexible top was summarized using engineering practices,which led to the proposal of a three-layer ultra-high-performance pavement(UHPP).The high-temperature rutting resistance and wet-weather skid resistance of UHPP were evaluated through composite structure tests.The internal temperature distribution within the pavement under typical high-temperature conditions was analyzed using a temperature field model.Additionally,a temperature-stress coupling model was employed to investigate the key load positions and stress response characteristics of the UHPP.The results indicate that compared with the traditional guss asphalt+stone mastic asphalt structure,the dynamic stability of the UHPP composite structure can be improved by up to 20.4%.Even under cyclic loading,UHPP still exhibits superior surface skid resistance compared to two traditional SBDPs.The thickness composition of UHPP significantly impacts its rutting resistance and skid resistance.UHPP exhibits relatively low tensile stress but higher shear stress levels,with the highest shear stress occurring between the UHPP and the steel plate.This suggests that the potential risk of damage for UHPP primarily lies within the interlayer of the pavement.Based on engineering examples,introducing interlayer gravel and optimizing the amount of bonding layer are advised to ensure that UHPP possesses sufficient interlayer shear resistance.
基金supported by the Key Research and Development Program of Shandong Province (2017GGX20123)the Fundamental Research Funds for the Central Universities of China (17CX02063 and 18CX02158A)
文摘Most of the supercapacitors reported in literatures showed little or no flexibility in the working temperature around 150℃. However, the supercapacitors are generally exposed under complex system or extreme temperature, such as electric vehicles and extremely cold area. Herein, we successfully fabricated a large-scale robust nanocarbon hybrid film consisting of reduced graphene oxide (rGO), carbon nanotubes (CNTs) and MnOx nano-flowers with the size up to 550 cm^2. The mechanical properties of the hybrid films depend on the ratio o f CNTs. The supercapacitors prepared with the hybrid films exhibit high flexibility and keep their performances in a temperature range from - 20 to 200℃. In addition, the devices display remarkable electrochemical and deformation stability at extrem e temperature. This strategy has a potential for the more efficient preparation of flexible electrode materials.
基金supported by the National Natural Science Foundation of China(61874111 and 61625404)the Young Elite Scientists Sponsorship Program by CAST(2018QNRC001)China Postdoctoral Science Foundation(2016M601131)。
文摘With the rapid development of portable devices and internet of things,the requirement of system wearability and integration accelerates the investigation of flexible multifunctional sensors.In this study,we developed an integrated flexible sensing system with four nanowire-based sensors and a Ni microwire-based temperature sensor.The four nanowirebased sensors are three kinds of photodetectors responding to lights with different wavelengths and a gas sensor.Due to the large surface volume ratio and considerable sub wavelength effect,all the nanowire-based sensors show good sensing response and excellent linear relationship between sensitivity and temperature.The as-fabricated flexible sensing system can simultaneously detect environmental parameters,including temperature change,light intensities from UV-Visible to near infrared regions,and harmful gas concentration.Our flexible multifunctional sensing system therefore opens up a new way for the emerging portable and wearable electronics.
基金the National Natural Science Foundation of China(51701146,51672204)the Fundamental Research Funds for the Central Universities(WUT:2017IB015)Foundation of National Key Laboratory on Electromagnetic Environment Effects(614220504030617)。
文摘Graphene emerges as an ideal material for constructing high-performance strain sensors,due to its superior mechanical property and high conductivity.However,in the process of assembling graphene into macroscopic materials,its conductivity decreases significantly.Also,tedious fabrication process hinders the application of graphene-based strain sensors.In this work,we report a freestanding graphene assembled film(GAF)with high conductivity((2.32±0.08)×105 S m-1).For the sensitive materials of strain sensors,it is higher than most of reported carbon nanotube and graphene materials.These advantages enable the GAF to be an ultra-low power consumption strain sensor for detecting airflow and vocal vibrations.The resistance of the GAF remains unchanged with increasing temperature(20-100℃),exhibiting a good thermal stability.Also,the GAF can be used as a strain sensor directly without any flexible substrates,which greatly simplifies the fabrication process in comparison with most reported strain sensors.Additionally,the GAF used as a pressure sensor with only^4.7μW power is investigated.This work provides a new direction for the preparation of advanced sensors with ultra-low power consumption,and the development of flexible and energy-saving electronic devices.
