Pub Date : 2024-09-01DOI: 10.1016/j.fmre.2023.08.006
Urban Air Mobility (UAM) is an emerging transportation system that aims at revolutionizing urban mobility through the deployment of small electric vertical takeoff and landing (eVTOL) aircraft. The development of UAM is largely driven by advances in Intelligent Technology (IT). This review article provides an overview of the UAM system and discusses the application of IT in UAM. Major challenges facing UAM are also identified, and an outlook on the future of this promising transportation system is presented. Our main conclusions suggest that IT is a fundamental driver of UAM, enabling a range of applications such as air traffic management and autonomous drone control. However, the UAM system is facing a number of challenges, including eVTOL technology, system integration issues, and noise pollution. Despite these challenges, the future of UAM appears promising; as a disruptive transportation mode, UAM is expected to play an important role in addressing the growing demand of urban transportation in the coming decades.
{"title":"The role of intelligent technology in the development of urban air mobility systems: A technical perspective","authors":"","doi":"10.1016/j.fmre.2023.08.006","DOIUrl":"10.1016/j.fmre.2023.08.006","url":null,"abstract":"<div><div>Urban Air Mobility (UAM) is an emerging transportation system that aims at revolutionizing urban mobility through the deployment of small electric vertical takeoff and landing (eVTOL) aircraft. The development of UAM is largely driven by advances in Intelligent Technology (IT). This review article provides an overview of the UAM system and discusses the application of IT in UAM. Major challenges facing UAM are also identified, and an outlook on the future of this promising transportation system is presented. Our main conclusions suggest that IT is a fundamental driver of UAM, enabling a range of applications such as air traffic management and autonomous drone control. However, the UAM system is facing a number of challenges, including eVTOL technology, system integration issues, and noise pollution. Despite these challenges, the future of UAM appears promising; as a disruptive transportation mode, UAM is expected to play an important role in addressing the growing demand of urban transportation in the coming decades.</div></div>","PeriodicalId":34602,"journal":{"name":"Fundamental Research","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134917368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.fmre.2023.01.008
Multiscale visualization of human anatomical structures is revolutionizing clinical diagnosis and treatment. As one of the most promising clinical diagnostic techniques, photoacoustic imaging (PAI), or optoacoustic imaging, bridges the spatial-resolution gap between pure optical and ultrasonic imaging techniques, by the modes of optical illumination and acoustic detection. PAI can non-invasively capture multiple optical contrasts from the endogenous agents such as oxygenated/deoxygenated hemoglobin, lipid and melanin or a variety of exogenous specific biomarkers to reveal anatomy, function, and molecular for biological tissues in vivo, showing significant potential in clinical diagnostics. In 2001, the worldwide first clinical prototype of the photoacoustic system was used to screen breast cancer in vivo, which opened the prelude to photoacoustic clinical diagnostics. Over the past two decades, PAI has achieved monumental discoveries and applications in human imaging. Progress towards preclinical/clinical applications includes breast, skin, lymphatics, bowel, thyroid, ovarian, prostate, and brain imaging, etc., and there is no doubt that PAI is opening new avenues to realize early diagnosis and precise treatment of human diseases. In this review, the breakthrough researches and key applications of photoacoustic human imaging in vivo are emphatically summarized, which demonstrates the technical superiorities and emerging applications of photoacoustic human imaging in clinical diagnostics, providing clinical translational orientations for the photoacoustic community and clinicians. The perspectives on potential improvements of photoacoustic human imaging are finally highlighted.
{"title":"Towards in vivo photoacoustic human imaging: Shining a new light on clinical diagnostics","authors":"","doi":"10.1016/j.fmre.2023.01.008","DOIUrl":"10.1016/j.fmre.2023.01.008","url":null,"abstract":"<div><div>Multiscale visualization of human anatomical structures is revolutionizing clinical diagnosis and treatment. As one of the most promising clinical diagnostic techniques, photoacoustic imaging (PAI), or optoacoustic imaging, bridges the spatial-resolution gap between pure optical and ultrasonic imaging techniques, by the modes of optical illumination and acoustic detection. PAI can non-invasively capture multiple optical contrasts from the endogenous agents such as oxygenated/deoxygenated hemoglobin, lipid and melanin or a variety of exogenous specific biomarkers to reveal anatomy, function, and molecular for biological tissues <em>in vivo</em>, showing significant potential in clinical diagnostics. In 2001, the worldwide first clinical prototype of the photoacoustic system was used to screen breast cancer <em>in vivo</em>, which opened the prelude to photoacoustic clinical diagnostics. Over the past two decades, PAI has achieved monumental discoveries and applications in human imaging. Progress towards preclinical/clinical applications includes breast, skin, lymphatics, bowel, thyroid, ovarian, prostate, and brain imaging, etc., and there is no doubt that PAI is opening new avenues to realize early diagnosis and precise treatment of human diseases. In this review, the breakthrough researches and key applications of photoacoustic human imaging <em>in vivo</em> are emphatically summarized, which demonstrates the technical superiorities and emerging applications of photoacoustic human imaging in clinical diagnostics, providing clinical translational orientations for the photoacoustic community and clinicians. The perspectives on potential improvements of photoacoustic human imaging are finally highlighted.</div></div>","PeriodicalId":34602,"journal":{"name":"Fundamental Research","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49569101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.fmre.2023.10.015
The study considers issues of elaborating and validating a technique of autonomous vehicle motion planning based on sequential trajectory and speed optimization. This method includes components such as representing sought-for functions by finite elements (FE), vehicle kinematic model, sequential quadratic programming for nonlinear constrained optimization, and Gaussian N-point quadrature integration. The primary novelty consists of using the inverse approach for obtaining vehicle trajectory and speed. The curvature and speed are represented by integrated polynomials to reduce the number of unknowns. For this, piecewise functions with two and three degrees of freedom (DOF) are implemented through FE nodal parameters. The technique ensures higher differentiability compared to the needed in the geometric and kinematic equations. Thus, the generated reference curves are characterized by simple and unambiguous forms. The latter fits best the control accuracy and efficiency during the motion tracking phase. Another advantage is replacing the nodal linear equality constraints with integral nonlinear ones. This ensures the non-violation of boundary limits within each FE and not only in nodes. The optimization technique implies that the spatial and time variables must be found separately and staged. The trajectory search is accomplished in the restricted allowable zone composed by superposing an area inside the external and internal boundaries, based on keeping safe distances, excluding areas for moving obstacles. Thus, this study compares two models that use two and three nodal DOF on optimization quality, stability, and rapidity in real-time applications. The simulation example shows numerous graph results of geometric and kinematic parameters with smoothed curves up to the highest derivatives. Finally, the conclusions are made on the efficiency and quality of prognosis, outlining the similarities and differences between the two applied models.
本研究考虑了如何详细阐述和验证基于顺序轨迹和速度优化的自主车辆运动规划技术。该方法包括用有限元（FE）表示所需的函数、车辆运动学模型、用于非线性约束优化的顺序二次编程和高斯 N 点正交积分等组成部分。主要的新颖之处在于使用逆方法获取车辆轨迹和速度。曲率和速度由积分多项式表示，以减少未知数的数量。为此，通过 FE 节点参数实现了具有两个和三个自由度 (DOF) 的分片函数。与几何方程和运动方程所需的可微分性相比，该技术可确保更高的可微分性。因此，生成的参考曲线形式简单明了。后者最适合运动跟踪阶段的控制精度和效率。另一个优点是用积分非线性约束代替了节点线性相等约束。这就确保了在每个 FE 中，而不仅仅是在节点中，边界限制不会受到破坏。优化技术意味着空间和时间变量必须分开并分阶段查找。在保持安全距离的基础上，排除移动障碍物的区域，在外部和内部边界叠加而成的限制允许区域内完成轨迹搜索。因此，本研究比较了使用两个节点和三个节点 DOF 的两种模型在实时应用中的优化质量、稳定性和快速性。模拟示例显示了大量几何参数和运动参数的图表结果，其中包括平滑曲线直至最高导数。最后，就预报的效率和质量得出结论，并概述了两种应用模型之间的异同。
{"title":"Developing inverse motion planning technique for autonomous vehicles using integral nonlinear constraints","authors":"","doi":"10.1016/j.fmre.2023.10.015","DOIUrl":"10.1016/j.fmre.2023.10.015","url":null,"abstract":"<div><div>The study considers issues of elaborating and validating a technique of autonomous vehicle motion planning based on sequential trajectory and speed optimization. This method includes components such as representing sought-for functions by finite elements (FE), vehicle kinematic model, sequential quadratic programming for nonlinear constrained optimization, and Gaussian N-point quadrature integration. The primary novelty consists of using the inverse approach for obtaining vehicle trajectory and speed. The curvature and speed are represented by integrated polynomials to reduce the number of unknowns. For this, piecewise functions with two and three degrees of freedom (DOF) are implemented through FE nodal parameters. The technique ensures higher differentiability compared to the needed in the geometric and kinematic equations. Thus, the generated reference curves are characterized by simple and unambiguous forms. The latter fits best the control accuracy and efficiency during the motion tracking phase. Another advantage is replacing the nodal linear equality constraints with integral nonlinear ones. This ensures the non-violation of boundary limits within each FE and not only in nodes. The optimization technique implies that the spatial and time variables must be found separately and staged. The trajectory search is accomplished in the restricted allowable zone composed by superposing an area inside the external and internal boundaries, based on keeping safe distances, excluding areas for moving obstacles. Thus, this study compares two models that use two and three nodal DOF on optimization quality, stability, and rapidity in real-time applications. The simulation example shows numerous graph results of geometric and kinematic parameters with smoothed curves up to the highest derivatives. Finally, the conclusions are made on the efficiency and quality of prognosis, outlining the similarities and differences between the two applied models.</div></div>","PeriodicalId":34602,"journal":{"name":"Fundamental Research","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138991135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.fmre.2022.04.012
Propane dehydrogenation (PDH) is an efficient technology for the direct production of propylene. Nevertheless, current PDH catalysts mainly rely on precious Pt or toxic Cr and especially undergo severe coke deposition. Herein, we report a Ru catalyst decorated by boron species (Ru-3B/Al2O3), which exhibits high catalytic performance for PDH. HAADF-STEM, EELS, and CO-FTIR characterization are used to identify the surface structure of the Ru active component, which shows that the high-energy unsaturated coordination sites, including corners, edges and step atoms for Ru-3B/Al2O3, are appropriately modified by BOx species. The encapsulation of high-energy active sites prone to CC cracking and deep dehydrogenation leads to higher propylene selectivity (> 95%) and strong carbon resistance (kd 0.0007 min) over Ru-3B/Al2O3. The XPS and H2-TPR results show that the migration of B species is driven by the reduction of B2O3 to B2O2 and that the coating degree of Ru particles is controlled by the chemical valance of Ru species.
{"title":"The structural decoration of Ru catalysts by boron for enhanced propane dehydrogenation","authors":"","doi":"10.1016/j.fmre.2022.04.012","DOIUrl":"10.1016/j.fmre.2022.04.012","url":null,"abstract":"<div><div>Propane dehydrogenation (PDH) is an efficient technology for the direct production of propylene. Nevertheless, current PDH catalysts mainly rely on precious Pt or toxic Cr and especially undergo severe coke deposition. Herein, we report a Ru catalyst decorated by boron species (Ru-3B/Al<sub>2</sub>O<sub>3</sub>), which exhibits high catalytic performance for PDH. HAADF-STEM, EELS, and CO-FTIR characterization are used to identify the surface structure of the Ru active component, which shows that the high-energy unsaturated coordination sites, including corners, edges and step atoms for Ru-3B/Al<sub>2</sub>O<sub>3,</sub> are appropriately modified by BO<sub>x</sub> species. The encapsulation of high-energy active sites prone to C<img>C cracking and deep dehydrogenation leads to higher propylene selectivity (> 95%) and strong carbon resistance (<em>k<sub>d</sub></em> 0.0007 min) over Ru-3B/Al<sub>2</sub>O<sub>3</sub>. The XPS and H<sub>2</sub>-TPR results show that the migration of B species is driven by the reduction of B<sub>2</sub>O<sub>3</sub> to B<sub>2</sub>O<sub>2</sub> and that the coating degree of Ru particles is controlled by the chemical valance of Ru species.</div></div>","PeriodicalId":34602,"journal":{"name":"Fundamental Research","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48390003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.fmre.2022.06.004
Photothermal therapy has aroused great attention and showed promising potential in minimally invasive tumor ablation, but the clinical translation is still stifled by the concerns of unwanted injury to normal tissues. The safety concerns might be completely solved only when the two security obstacles of “material-toxicity” and “photo-toxicity” were overcome simultaneously. Herein, a completely non-toxic food-grade photothermal transduction agent (PTA) with double safety guarantees was invented, which shows an absolute transformation of the photothermal effect from “0” to “1” after being triggered by an acidic tumor microenvironment. Inspired by the classical starch-iodine test, a preprogrammed [starch-KI-KIO3] complex was prepared in large quantities through a modified wet-milling procedure. It's demonstrated that a macroscopic consecutive reaction could be triggered by low pH to produce the starch-iodine complex which can generate lethal temperature under the near-infrared light irradiation. Meanwhile, the PTA shows excellent biocompatibility with no “material-toxicity” owing to the raw materials drawn from our daily food. Animal experiments reveal that the tumor microenvironment can activate the switch of photothermal effect from “0” to “1” successfully, which is thus responsible for the discriminative photo-damage to the tumor region while no “photo-toxicity” to normal tissue. The good treatment efficacy confirms the feasibility of such photothermal transduction agents with double safety guarantees in clinical applications.
{"title":"Double safety guarantees: Food-grade photothermal complex with a pH-triggered NIR absorption from zero to one","authors":"","doi":"10.1016/j.fmre.2022.06.004","DOIUrl":"10.1016/j.fmre.2022.06.004","url":null,"abstract":"<div><div>Photothermal therapy has aroused great attention and showed promising potential in minimally invasive tumor ablation, but the clinical translation is still stifled by the concerns of unwanted injury to normal tissues. The safety concerns might be completely solved only when the two security obstacles of “material-toxicity” and “photo-toxicity” were overcome simultaneously. Herein, a completely non-toxic food-grade photothermal transduction agent (PTA) with double safety guarantees was invented, which shows an absolute transformation of the photothermal effect from “0” to “1” after being triggered by an acidic tumor microenvironment. Inspired by the classical starch-iodine test, a preprogrammed [starch-KI-KIO<sub>3</sub>] complex was prepared in large quantities through a modified wet-milling procedure. It's demonstrated that a macroscopic consecutive reaction could be triggered by low pH to produce the starch-iodine complex which can generate lethal temperature under the near-infrared light irradiation. Meanwhile, the PTA shows excellent biocompatibility with no “material-toxicity” owing to the raw materials drawn from our daily food. Animal experiments reveal that the tumor microenvironment can activate the switch of photothermal effect from “0” to “1” successfully, which is thus responsible for the discriminative photo-damage to the tumor region while no “photo-toxicity” to normal tissue. The good treatment efficacy confirms the feasibility of such photothermal transduction agents with double safety guarantees in clinical applications.</div></div>","PeriodicalId":34602,"journal":{"name":"Fundamental Research","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43359841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.fmre.2023.06.009
Carbon dioxide (CO2) from road traffic is a non-negligible part of global greenhouse gas (GHG) emissions, and it is a challenge for the world today to accurately estimate road traffic CO2 emissions and formulate effective emission reduction policies. Current emission inventories for vehicles have either low-resolution, or limited coverage, and they have not adequately focused on the CO2 emission produced by new energy vehicles (NEV) considering fuel life cycle. To fill the research gap, this paper proposed a framework of a high-resolution well-to-wheel (WTW) CO2 emission estimation for a full sample of vehicles and revealed the unique CO2 emission characteristics of different categories of vehicles combined with vehicle behavior. Based on this, the spatiotemporal characteristics and influencing factors of CO2 emissions were analyzed with the geographical and temporal weighted regression (GTWR) model. Finally, the CO2 emissions of vehicles under different scenarios are simulated to support the formulation of emission reduction policies. The results show that the distribution of vehicle CO2 emissions shows obvious heterogeneity in time, space, and vehicle category. By simply adjusting the existing NEV promotion policy, the emission reduction effect can be improved by 6.5%–13.5% under the same NEV penetration. If combined with changes in power generation structure, it can further release the emission reduction potential of NEVs, which can reduce the current CO2 emissions by 78.1% in the optimal scenario.
{"title":"Uncovering the CO2 emissions of vehicles: A well-to-wheel approach","authors":"","doi":"10.1016/j.fmre.2023.06.009","DOIUrl":"10.1016/j.fmre.2023.06.009","url":null,"abstract":"<div><div>Carbon dioxide (CO<sub>2</sub>) from road traffic is a non-negligible part of global greenhouse gas (GHG) emissions, and it is a challenge for the world today to accurately estimate road traffic CO<sub>2</sub> emissions and formulate effective emission reduction policies. Current emission inventories for vehicles have either low-resolution, or limited coverage, and they have not adequately focused on the CO<sub>2</sub> emission produced by new energy vehicles (NEV) considering fuel life cycle. To fill the research gap, this paper proposed a framework of a high-resolution well-to-wheel (WTW) CO<sub>2</sub> emission estimation for a full sample of vehicles and revealed the unique CO<sub>2</sub> emission characteristics of different categories of vehicles combined with vehicle behavior. Based on this, the spatiotemporal characteristics and influencing factors of CO<sub>2</sub> emissions were analyzed with the geographical and temporal weighted regression (GTWR) model. Finally, the CO<sub>2</sub> emissions of vehicles under different scenarios are simulated to support the formulation of emission reduction policies. The results show that the distribution of vehicle CO<sub>2</sub> emissions shows obvious heterogeneity in time, space, and vehicle category. By simply adjusting the existing NEV promotion policy, the emission reduction effect can be improved by 6.5%–13.5% under the same NEV penetration. If combined with changes in power generation structure, it can further release the emission reduction potential of NEVs, which can reduce the current CO<sub>2</sub> emissions by 78.1% in the optimal scenario.</div></div>","PeriodicalId":34602,"journal":{"name":"Fundamental Research","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44140084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.fmre.2022.12.006
Scholars and practitioners believe that the large-scale deployment of charging piles is imperative to our future electric transportation systems. Major economies ambitiously install charging pile networks, with massive construction spending, maintenance costs, and urban space occupation. However, recent developments in technology may significantly reduce the necessary charging capacity required by the system. This paper develops a linear programming model to characterize the effects of likely scenarios where vehicle-to-vehicle (V2V) charging is available via vehicle modularization or wireless charging. Specifically, we consider scenarios in which vehicles can transmit energy to each other (coordinated by a central platform) while traveling closely on the same road. We first estimate the number of charging piles needed for completing the travel plan of 73 cars from data, assuming a battery capacity of 400 km’s range and no V2V charging. Our results show that once V2V charging technologies with an efficiency of 50% are available, more than 2/3 of the charging piles investment would be wasted. Additionally, if the efficiency of V2V charging increases to 75%, we can easily reduce the battery capacity of vehicles to 200 km, which will reduce production costs and improve energy efficiency. These results may reveal us an alternative pathway towards transportation electrification.
{"title":"Are more charging piles imperative to future electrified transportation system?","authors":"","doi":"10.1016/j.fmre.2022.12.006","DOIUrl":"10.1016/j.fmre.2022.12.006","url":null,"abstract":"<div><div>Scholars and practitioners believe that the large-scale deployment of charging piles is imperative to our future electric transportation systems. Major economies ambitiously install charging pile networks, with massive construction spending, maintenance costs, and urban space occupation. However, recent developments in technology may significantly reduce the necessary charging capacity required by the system. This paper develops a linear programming model to characterize the effects of likely scenarios where vehicle-to-vehicle (V2V) charging is available via vehicle modularization or wireless charging. Specifically, we consider scenarios in which vehicles can transmit energy to each other (coordinated by a central platform) while traveling closely on the same road. We first estimate the number of charging piles needed for completing the travel plan of 73 cars from data, assuming a battery capacity of 400 km’s range and no V2V charging. Our results show that once V2V charging technologies with an efficiency of 50% are available, more than 2/3 of the charging piles investment would be wasted. Additionally, if the efficiency of V2V charging increases to 75%, we can easily reduce the battery capacity of vehicles to 200 km, which will reduce production costs and improve energy efficiency. These results may reveal us an alternative pathway towards transportation electrification.</div></div>","PeriodicalId":34602,"journal":{"name":"Fundamental Research","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47884164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.fmre.2022.09.013
This paper discusses the predefined practical finite-time (PPFT) dynamic positioning (DP) control problem for DP vessels subject to internal/external uncertainties. Those heterogeneity uncertainties are handled by a separate-type treatment approach. The finite-time (FT) DP control is fulfilled by a predefined FT function on the basis of a time-based generator (TBG). Under the dynamic surface control together with the TBG design framework, the convergence time and control accuracy of the DP system can be determined by the designer offline. Meanwhile, the virtual derivation and computational burden problems are dissolved by using a first-order filter and virtual parameter learning technique. To reduce mechanical wear, an event-triggering protocol between the control law and the actuator is built to reduce the operating frequency of the actuator. An event-triggered neuroadaptive PPFT control scheme is presented for DP vessels. The stability of the closed-loop DP control systems is validated via the Lyapunov theorem. Approach efficiency is confirmed by numerical examples.
{"title":"Event-triggered neuroadaptive predefined practical finite-time control for dynamic positioning vessels: A time-based generator approach","authors":"","doi":"10.1016/j.fmre.2022.09.013","DOIUrl":"10.1016/j.fmre.2022.09.013","url":null,"abstract":"<div><div>This paper discusses the predefined practical finite-time (PPFT) dynamic positioning (DP) control problem for DP vessels subject to internal/external uncertainties. Those heterogeneity uncertainties are handled by a separate-type treatment approach. The finite-time (FT) DP control is fulfilled by a predefined FT function on the basis of a time-based generator (TBG). Under the dynamic surface control together with the TBG design framework, the convergence time and control accuracy of the DP system can be determined by the designer offline. Meanwhile, the virtual derivation and computational burden problems are dissolved by using a first-order filter and virtual parameter learning technique. To reduce mechanical wear, an event-triggering protocol between the control law and the actuator is built to reduce the operating frequency of the actuator. An event-triggered neuroadaptive PPFT control scheme is presented for DP vessels. The stability of the closed-loop DP control systems is validated via the Lyapunov theorem. Approach efficiency is confirmed by numerical examples.</div></div>","PeriodicalId":34602,"journal":{"name":"Fundamental Research","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42109040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.fmre.2023.03.021
Core-shell nanoparticles (CSNPs) are widely used in energy harvesting, conversion, and thermal management due to the excellent physical properties of different components. Because of the synergistic interaction between the core and the shell, the thermal radiative properties are expected to be further enhanced. In this work, we achieve near-field radiative heat transfer (NFRHT) enhancement between SiC@Drude CSNPs. Numerical results show that the total heat flux between NPs is 1.47 times and 9.98 times higher than homogeneous SiC and Drude NPs at the same radius when the core volume fraction is 0.76. Surface modes hybridization arising from the interfaces of the shell-core and shell-air contributes to the improved thermal radiation. The effect of shift frequency on the NFRHT between SiC@Drude CSNPs is studied, showing that the enhancement ratio of NFRHT between CSNPs can reach 4.34 at a shift frequency of 1 × 1014 rad/s, which is 38.34 times higher than the previous work. This study demonstrates that surface modes hybridization in CSNPs can significantly improve NFRHT and open a novel path for high-efficiency energy transport at the nanoscale.
{"title":"Enhanced near-field radiative heat transfer between core-shell nanoparticles through surface modes hybridization","authors":"","doi":"10.1016/j.fmre.2023.03.021","DOIUrl":"10.1016/j.fmre.2023.03.021","url":null,"abstract":"<div><div>Core-shell nanoparticles (CSNPs) are widely used in energy harvesting, conversion, and thermal management due to the excellent physical properties of different components. Because of the synergistic interaction between the core and the shell, the thermal radiative properties are expected to be further enhanced. In this work, we achieve near-field radiative heat transfer (NFRHT) enhancement between SiC@Drude CSNPs. Numerical results show that the total heat flux between NPs is 1.47 times and 9.98 times higher than homogeneous SiC and Drude NPs at the same radius when the core volume fraction is 0.76. Surface modes hybridization arising from the interfaces of the shell-core and shell-air contributes to the improved thermal radiation. The effect of shift frequency on the NFRHT between SiC@Drude CSNPs is studied, showing that the enhancement ratio of NFRHT between CSNPs can reach 4.34 at a shift frequency of 1 × 10<sup>14</sup> rad/s, which is 38.34 times higher than the previous work. This study demonstrates that surface modes hybridization in CSNPs can significantly improve NFRHT and open a novel path for high-efficiency energy transport at the nanoscale.</div></div>","PeriodicalId":34602,"journal":{"name":"Fundamental Research","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43097142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.fmre.2022.08.022
Using in situ observations collected by a drifting air–sea interface buoy (DrIB) in the northern South China Sea from August 30 to September 13, 2018, the extreme air–sea turbulent fluxes that occurred from September 8 to 13 during tropical cyclone (TC) Barijat were investigated. The most striking features were substantial increases in momentum and heat fluxes, with maximum increases of 10.8 m s−1 in the wind speed (WS), 0.73 N m−2 in the wind stress, 68.1 W m−2 in the sensible heat fluxes (SH) and 258.8 W m−2 in the latent heat fluxes (LH). The maximum WS, wind stress, SH and LH values amounted to 15.3 m s−1, 0.8 N m−2, 70.9 W m−2 and 329.9 W m−2, respectively. Using these new DrIB observations, the performance of two state-of-the-art, high-resolution reanalysis products, ERA5 and MERRA2, was assessed. The consistency of the observed values with ERA5 was slightly better than with MERRA2, reflected in higher correlations but both products underestimated the WS during TC conditions. In calm weather conditions, the turbulent heat fluxes were overestimated, because they simulated a too dry and cold atmospheric state, enhancing the air–sea differences in temperature and humidity. Considering that an accurate representation of the air–sea turbulent and momentum fluxes is essential for understanding and predicting ocean and atmospheric variability, our findings indicate that more high-quality temperature and relative humidity observations are required to evaluate and improve existing reanalysis products.
利用2018年8月30日至9月13日南海北部漂流海气界面浮标（DrIB）采集的原位观测资料，研究了9月8日至13日热带气旋（TC）"百里嘉 "期间发生的极端海气湍流通量。最显著的特征是动量和热通量大幅增加，最大风速（WS）增加了 10.8 m s-1，风应力增加了 0.73 N m-2，显热通量（SH）增加了 68.1 W m-2，潜热通量（LH）增加了 258.8 W m-2。最大 WS 值、风压值、SH 值和 LH 值分别为 15.3 m s-1、0.8 N m-2、70.9 W m-2 和 329.9 W m-2。利用这些新的 DrIB 观测数据，对两种最先进的高分辨率再分析产品 ERA5 和 MERRA2 的性能进行了评估。观测值与ERA5的一致性略好于MERRA2，反映在更高的相关性上，但这两种产品都低估了TC条件下的WS。在风平浪静的天气条件下，湍流热通量被高估了，因为它们模拟的大气状态过于干燥和寒冷，加剧了海气温湿度差异。考虑到准确表示海气湍流和动量通量对于理解和预测海洋和大气变率至关重要，我们的研究结果表明，需要更多高质量的温度和相对湿度观测资料来评估和改进现有的再分析产品。
{"title":"Extreme air–sea turbulent fluxes during tropical cyclone Barijat observed by a newly designed drifting buoy","authors":"","doi":"10.1016/j.fmre.2022.08.022","DOIUrl":"10.1016/j.fmre.2022.08.022","url":null,"abstract":"<div><div>Using <em>in situ</em> observations collected by a drifting air–sea interface buoy (DrIB) in the northern South China Sea from August 30 to September 13, 2018, the extreme air–sea turbulent fluxes that occurred from September 8 to 13 during tropical cyclone (TC) Barijat were investigated. The most striking features were substantial increases in momentum and heat fluxes, with maximum increases of 10.8 m s<sup>−1</sup> in the wind speed (WS), 0.73 N m<sup>−2</sup> in the wind stress, 68.1 W m<sup>−2</sup> in the sensible heat fluxes (SH) and 258.8 W m<sup>−2</sup> in the latent heat fluxes (LH). The maximum WS, wind stress, SH and LH values amounted to 15.3 m s<sup>−1</sup>, 0.8 N m<sup>−2</sup>, 70.9 W m<sup>−2</sup> and 329.9 W m<sup>−2</sup>, respectively. Using these new DrIB observations, the performance of two state-of-the-art, high-resolution reanalysis products, ERA5 and MERRA2, was assessed. The consistency of the observed values with ERA5 was slightly better than with MERRA2, reflected in higher correlations but both products underestimated the WS during TC conditions. In calm weather conditions, the turbulent heat fluxes were overestimated, because they simulated a too dry and cold atmospheric state, enhancing the air–sea differences in temperature and humidity. Considering that an accurate representation of the air–sea turbulent and momentum fluxes is essential for understanding and predicting ocean and atmospheric variability, our findings indicate that more high-quality temperature and relative humidity observations are required to evaluate and improve existing reanalysis products.</div></div>","PeriodicalId":34602,"journal":{"name":"Fundamental Research","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43399629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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