Atmospheric chemistry models usually perform badly in forecasting wintertime air pollution because of their uncertainties. Generally, such uncertainties can be decreased effectively by techniques such as data assimila...Atmospheric chemistry models usually perform badly in forecasting wintertime air pollution because of their uncertainties. Generally, such uncertainties can be decreased effectively by techniques such as data assimilation（DA） and model output statistics（MOS）. However, the relative importance and combined effects of the two techniques have not been clarified. Here,a one-month air quality forecast with the Weather Research and Forecasting-Chemistry（WRF-Chem） model was carried out in a virtually operational setup focusing on Hebei Province, China. Meanwhile, three-dimensional variational（3 DVar） DA and MOS based on one-dimensional Kalman filtering were implemented separately and simultaneously to investigate their performance in improving the model forecast. Comparison with observations shows that the chemistry forecast with MOS outperforms that with 3 DVar DA, which could be seen in all the species tested over the whole 72 forecast hours. Combined use of both techniques does not guarantee a better forecast than MOS only, with the improvements and degradations being small and appearing rather randomly. Results indicate that the implementation of MOS is more suitable than 3 DVar DA in improving the operational forecasting ability of WRF-Chem.展开更多
Heterojunction and morphology control assume a significant part in adjusting the intrinsic electromagnetic properties of absorbers to acquire outstanding microwave absorption(MA)performance,but this still faces huge c...Heterojunction and morphology control assume a significant part in adjusting the intrinsic electromagnetic properties of absorbers to acquire outstanding microwave absorption(MA)performance,but this still faces huge challenges.Herein,FeS_(2)/C/MoS_(2)composite with core–shell structure was successfully designed and prepared via a multi-interface engineering.MoS_(2)nanosheets with 1T and 2H phases are coated on the outside of FeS_(2)/C to form a porous interconnected structure that can optimize the impedance matching characteristics and strengthen the interfacial polarization loss capacity.Remarkably,as-fabricated FCM-3 harvests a broad effective absorption bandwidth(EAB)of 5.12 GHz and a minimum reflection loss(RL_(min))value of-45.1 d B.Meanwhile,FCM-3 can accomplish a greatest radar cross section(RCS)reduction value of 18.52 d B m^(2)when the detection angle is 0°.Thus,the convenient computer simulation technology(CST)simulations and encouraging accomplishments provide a novel avenue for the further development of efficient and lightweight MA materials.展开更多
In the new era,the impact of emerging productive forces has permeated every sector of industry.As the core production factor of these forces,data plays a pivotal role in industrial transformation and social developmen...In the new era,the impact of emerging productive forces has permeated every sector of industry.As the core production factor of these forces,data plays a pivotal role in industrial transformation and social development.Consequently,many domestic universities have introduced majors or courses related to big data.Among these,the Big Data Management and Applications major stands out for its interdisciplinary approach and emphasis on practical skills.However,as an emerging field,it has not yet accumulated a robust foundation in teaching theory and practice.Current instructional practices face issues such as unclear training objectives,inconsistent teaching methods and course content,insufficient integration of practical components,and a shortage of qualified faculty-factors that hinder both the development of the major and the overall quality of education.Taking the statistics course within the Big Data Management and Applications major as an example,this paper examines the challenges faced by statistics education in the context of emerging productive forces and proposes corresponding improvement measures.By introducing innovative teaching concepts and strategies,the teaching system for professional courses is optimized,and authentic classroom scenarios are recreated through illustrative examples.Questionnaire surveys and statistical analyses of data collected before and after the teaching reforms indicate that the curriculum changes effectively enhance instructional outcomes,promote the development of the major,and improve the quality of talent cultivation.展开更多
With the implementation of General Senior High School Mathematics Curriculum Standards(2017 Edition,Revised in 2020),probability and statistics,as important carriers of the core mathematical competencies“mathematical...With the implementation of General Senior High School Mathematics Curriculum Standards(2017 Edition,Revised in 2020),probability and statistics,as important carriers of the core mathematical competencies“mathematical modeling”and“data analysis,”have increasingly highlighted their educational value.By summarizing the historical evolution of probability and statistics thinking and combining with teaching practice cases,this study explores its unique role in cultivating students’core mathematical competencies.The research proposes a project-based teaching strategy relying on real scenarios and empowered by technology.Through cases,it demonstrates how to use modern educational technology to realize the whole-process exploration of data collection,model construction,and conclusion verification,so as to promote the transformation of middle school probability and statistics teaching from knowledge imparting to competency development,and provide a practical reference for curriculum reform.展开更多
本文提出了一种低功耗全MOS电压基准源设计,利用MOS管在亚阈值区的温度特性,降低了功耗并满足低电压、宽温度范围的需求。传统的带隙基准源由于采用双极管和电阻,无法满足低功耗应用的要求,因此,本文设计了一种全MOS管的基准电压源,通...本文提出了一种低功耗全MOS电压基准源设计,利用MOS管在亚阈值区的温度特性,降低了功耗并满足低电压、宽温度范围的需求。传统的带隙基准源由于采用双极管和电阻,无法满足低功耗应用的要求,因此,本文设计了一种全MOS管的基准电压源,通过优化电路结构和工作原理,实现了低静态功耗、较宽的工作温度范围和较低的温度系数。仿真结果显示,在−55℃到150℃的温度范围内,输出电压变化仅为2.03 mV,温度系数为16.5 × 10⁻⁶/℃,静态电流为5.7 μA,功耗为6.84 μW,PSRR为−59.16 dB。该设计在低功耗、低电压应用中具有显著优势,适用于物联网、可穿戴设备等对功耗要求较高的场合。This paper proposes a low-power all-MOS voltage reference design that utilizes the temperature characteristics of MOS transistors operating in the subthreshold region to achieve low power consumption while meeting the requirements of low voltage and wide temperature range. Traditional bandgap reference circuits, which rely on bipolar junction transistors and resistors, fail to satisfy the demands of low-power applications. Therefore, this design adopts an all-MOS voltage reference structure. By optimizing the circuit architecture and operational principles, the design achieves low static power consumption, a wide operating temperature range, and a low temperature coefficient. Simulation results show that within the temperature range of −55˚C to 150˚C, the output voltage variation is only 2.03 mV, with a temperature coefficient of 16.5×10⁻⁶/˚C. The static current is 5.7 μA, power consumption is 6.84 μW, and the power supply rejection ratio (PSRR) is −59.16 dB. This design demonstrates significant advantages in low-power, low-voltage applications, making it suitable for use in IoT devices, wearable electronics, and other scenarios with stringent power consumption requirements.展开更多
This paper focuses on the ideological and political construction of the course“Probability Theory and Mathematical Statistics.”Aiming at the current situation in teaching where emphasis is placed on knowledge impart...This paper focuses on the ideological and political construction of the course“Probability Theory and Mathematical Statistics.”Aiming at the current situation in teaching where emphasis is placed on knowledge imparting while value guidance is neglected,and combined with the requirements of ideological and political education policies in the new era,this paper explores the integration path between professional courses and ideological and political education.Through literature analysis,case comparison,and empirical research,the study proposes a systematic implementation plan covering the design of teaching objectives,the reconstruction of teaching content,and the optimization of the evaluation system.The purpose is to cultivate students’sense of social responsibility and innovative awareness by excavating the ideological and political elements in mathematics.The research results provide practical reference for colleges and universities to deepen the reform of ideological and political education in courses,and promote the implementation of the fundamental task of fostering virtue through education in STEM education.展开更多
基金supported by the State Key Research and Development Program (Grant Nos. 2017YFC0209803, 2016YFC0208504, 2016YFC0203303 and 2017YFC0210106)the National Natural Science Foundation of China (Grant Nos. 91544230, 41575145, 41621005 and 41275128)
文摘Atmospheric chemistry models usually perform badly in forecasting wintertime air pollution because of their uncertainties. Generally, such uncertainties can be decreased effectively by techniques such as data assimilation（DA） and model output statistics（MOS）. However, the relative importance and combined effects of the two techniques have not been clarified. Here,a one-month air quality forecast with the Weather Research and Forecasting-Chemistry（WRF-Chem） model was carried out in a virtually operational setup focusing on Hebei Province, China. Meanwhile, three-dimensional variational（3 DVar） DA and MOS based on one-dimensional Kalman filtering were implemented separately and simultaneously to investigate their performance in improving the model forecast. Comparison with observations shows that the chemistry forecast with MOS outperforms that with 3 DVar DA, which could be seen in all the species tested over the whole 72 forecast hours. Combined use of both techniques does not guarantee a better forecast than MOS only, with the improvements and degradations being small and appearing rather randomly. Results indicate that the implementation of MOS is more suitable than 3 DVar DA in improving the operational forecasting ability of WRF-Chem.
基金financially supported by the National Natural Science Foundation of China(Nos.52402354,62174016 and 12374394)China Postdoctoral Science Foundation(Nos.2023M740471)the Natural Science Foundation of Jiangsu Higher Education Institutions(Nos.24KJB430002)。
文摘Heterojunction and morphology control assume a significant part in adjusting the intrinsic electromagnetic properties of absorbers to acquire outstanding microwave absorption(MA)performance,but this still faces huge challenges.Herein,FeS_(2)/C/MoS_(2)composite with core–shell structure was successfully designed and prepared via a multi-interface engineering.MoS_(2)nanosheets with 1T and 2H phases are coated on the outside of FeS_(2)/C to form a porous interconnected structure that can optimize the impedance matching characteristics and strengthen the interfacial polarization loss capacity.Remarkably,as-fabricated FCM-3 harvests a broad effective absorption bandwidth(EAB)of 5.12 GHz and a minimum reflection loss(RL_(min))value of-45.1 d B.Meanwhile,FCM-3 can accomplish a greatest radar cross section(RCS)reduction value of 18.52 d B m^(2)when the detection angle is 0°.Thus,the convenient computer simulation technology(CST)simulations and encouraging accomplishments provide a novel avenue for the further development of efficient and lightweight MA materials.
文摘In the new era,the impact of emerging productive forces has permeated every sector of industry.As the core production factor of these forces,data plays a pivotal role in industrial transformation and social development.Consequently,many domestic universities have introduced majors or courses related to big data.Among these,the Big Data Management and Applications major stands out for its interdisciplinary approach and emphasis on practical skills.However,as an emerging field,it has not yet accumulated a robust foundation in teaching theory and practice.Current instructional practices face issues such as unclear training objectives,inconsistent teaching methods and course content,insufficient integration of practical components,and a shortage of qualified faculty-factors that hinder both the development of the major and the overall quality of education.Taking the statistics course within the Big Data Management and Applications major as an example,this paper examines the challenges faced by statistics education in the context of emerging productive forces and proposes corresponding improvement measures.By introducing innovative teaching concepts and strategies,the teaching system for professional courses is optimized,and authentic classroom scenarios are recreated through illustrative examples.Questionnaire surveys and statistical analyses of data collected before and after the teaching reforms indicate that the curriculum changes effectively enhance instructional outcomes,promote the development of the major,and improve the quality of talent cultivation.
基金2021 Annual Research Project of Yili Normal University(2021YSBS012)。
文摘With the implementation of General Senior High School Mathematics Curriculum Standards(2017 Edition,Revised in 2020),probability and statistics,as important carriers of the core mathematical competencies“mathematical modeling”and“data analysis,”have increasingly highlighted their educational value.By summarizing the historical evolution of probability and statistics thinking and combining with teaching practice cases,this study explores its unique role in cultivating students’core mathematical competencies.The research proposes a project-based teaching strategy relying on real scenarios and empowered by technology.Through cases,it demonstrates how to use modern educational technology to realize the whole-process exploration of data collection,model construction,and conclusion verification,so as to promote the transformation of middle school probability and statistics teaching from knowledge imparting to competency development,and provide a practical reference for curriculum reform.
文摘本文提出了一种低功耗全MOS电压基准源设计,利用MOS管在亚阈值区的温度特性,降低了功耗并满足低电压、宽温度范围的需求。传统的带隙基准源由于采用双极管和电阻,无法满足低功耗应用的要求,因此,本文设计了一种全MOS管的基准电压源,通过优化电路结构和工作原理,实现了低静态功耗、较宽的工作温度范围和较低的温度系数。仿真结果显示,在−55℃到150℃的温度范围内,输出电压变化仅为2.03 mV,温度系数为16.5 × 10⁻⁶/℃,静态电流为5.7 μA,功耗为6.84 μW,PSRR为−59.16 dB。该设计在低功耗、低电压应用中具有显著优势,适用于物联网、可穿戴设备等对功耗要求较高的场合。This paper proposes a low-power all-MOS voltage reference design that utilizes the temperature characteristics of MOS transistors operating in the subthreshold region to achieve low power consumption while meeting the requirements of low voltage and wide temperature range. Traditional bandgap reference circuits, which rely on bipolar junction transistors and resistors, fail to satisfy the demands of low-power applications. Therefore, this design adopts an all-MOS voltage reference structure. By optimizing the circuit architecture and operational principles, the design achieves low static power consumption, a wide operating temperature range, and a low temperature coefficient. Simulation results show that within the temperature range of −55˚C to 150˚C, the output voltage variation is only 2.03 mV, with a temperature coefficient of 16.5×10⁻⁶/˚C. The static current is 5.7 μA, power consumption is 6.84 μW, and the power supply rejection ratio (PSRR) is −59.16 dB. This design demonstrates significant advantages in low-power, low-voltage applications, making it suitable for use in IoT devices, wearable electronics, and other scenarios with stringent power consumption requirements.
基金Shaanxi Provincial 14th Five-Year Plan for Educational Science Research(SGH24Q481)。
文摘This paper focuses on the ideological and political construction of the course“Probability Theory and Mathematical Statistics.”Aiming at the current situation in teaching where emphasis is placed on knowledge imparting while value guidance is neglected,and combined with the requirements of ideological and political education policies in the new era,this paper explores the integration path between professional courses and ideological and political education.Through literature analysis,case comparison,and empirical research,the study proposes a systematic implementation plan covering the design of teaching objectives,the reconstruction of teaching content,and the optimization of the evaluation system.The purpose is to cultivate students’sense of social responsibility and innovative awareness by excavating the ideological and political elements in mathematics.The research results provide practical reference for colleges and universities to deepen the reform of ideological and political education in courses,and promote the implementation of the fundamental task of fostering virtue through education in STEM education.
