This technical note presents a sensor fault detection and isolation scheme for a class of Lipschitz nonlinear systems with unstructured modeling uncertainty. It significantly extends previous results ...by considering a class of system nonlinearities which are modeled as functions of the system input and partially measurable state variables. A new sensor fault diagnosis method is developed using adaptive estimation techniques. Adaptive thresholds for fault detection and isolation are derived, and several important properties are investigated, including robustness, stability and learning capability, and fault isolability. A robotic example is used to show the effectiveness of the method.
This paper investigates the relationship between candidates' online popularity and election results, as a step towards creating a model to forecast the results of Taiwanese elections even in the ...absence of reliable opinion polls on a district-by-district level. 253 of 354 legislative candidates of single-member districts in Taiwan's 2016 general election had active public Facebook pages during the election period. Hypothesizing that the relative popularity of candidates' Facebook posts will be positively related to their election results, I calculated each candidate's Like Ratio (i.e. proportions of all likes on Facebook posts obtained by candidates in their district). In order to have a measure of online interest without the influence of subjective positivity, I similarly calculated the proportion of daily average page views for each candidate's Wikipedia page. I ran a regression analysis, incorporating data on results of previous elections and available opinion poll data. I found the models could describe the result of the election well and reject the null hypothesis. My models successfully predicted 80% of winners in single-member districts and were effective in districts without local opinion polls with a predictive power approaching that of traditional opinion polls. The models also showed good accuracy when run on data for the 2014 Taiwanese municipal mayors election.
This brief presents the systematic design and real-time experimental results of a fault detection, isolation, and accommodation algorithm for quadrotor actuator faults using nonlinear adaptive ...estimation techniques. The fault diagnosis architecture consists of a nonlinear fault detection estimator and a bank of nonlinear adaptive fault isolation estimators designed based on the functional structures of the faults under consideration. Adaptive thresholds for fault detection and isolation are systematically designed to enhance the robustness and fault sensitivity of the diagnostic algorithm. After fault isolation, the fault parameter estimate generated by the matched isolation estimator is used for accommodating the fault effect. Using an indoor quadrotor test environment, real-time experimental results are shown to illustrate the effectiveness of the algorithms.
This brief presents the design, analysis, and implementation of a nonlinear robust adaptive fault-tolerant altitude and attitude tracking method for accommodating actuator faults in quadrotor ...unmanned aerial vehicles without the need of a fault diagnosis mechanism. Actuator faults are modeled as a constant loss of effectiveness in the thrust generated by the rotors. The fault-tolerant control (FTC) algorithm guarantees asymptotic convergence of the altitude and attitude tracking error even in the presence of possible multiple actuator faults and modeling uncertainties. The FTC method is implemented using a real-time indoor quadrotor test environment. Experimental results are shown to illustrate the effectiveness of the algorithm.
Abstract
This semester-long qualitative case study, spanning 4 months, focused on an English reading course in which 20 university English-as-a-foreign-language readers were instructed to engage in ...web-based collaborative learning outside of class. The study drew on data resources including interviews with students, field notes on their web-based collaborative learning practices, and students’ written reflections. A thematic analysis of the data sources shows that the positivity of student readers’ beliefs about web-based collaborative learning (i.e., about web-based collaborative platforms and reading activities) changed over time but ultimately became stably positive. The change was found to be related to the interactions between their beliefs about web-based collaborative platforms and their beliefs about reading activities over time. The students’ beliefs about web-based collaborative learning were also found to be sensitive to factors regarding the students’ learning over time, including their prior learning experiences and their ongoing learning experiences. In the process, the students’ web-based collaborative learning practices were primarily driven by their positive beliefs and constrained by their negative beliefs although additional factors emerged over time from their learning process and intervened in the relationship between their beliefs and their learning. The implications of these findings on how to best engage students in web-based learning are discussed.
•An integrated model analysis framework and tool called WEFO.•Multi-period socioeconomic model for water-energy-food nexus.•Interactions among water, energy, and food are simultaneously ...addressed.•Tradeoffs among economic objectives, resource constraints and environmental impacts.
Water, energy and food (WEF) are inextricably interrelated. Effective planning and management of limited WEF resources to meet current and future socioeconomic demands for sustainable development is challenging. WEF production/delivery may also produce environmental impacts; as a result, green-house-gas emission control will impact WEF nexus management as well. Nexus management for WEF security necessitates integrated tools for predictive analysis that are capable of identifying the tradeoffs among various sectors, generating cost-effective planning and management strategies and policies. To address these needs, we have developed an integrated model analysis framework and tool called WEFO. WEFO provides a multi-period socioeconomic model for predicting how to satisfy WEF demands based on model inputs representing productions costs, socioeconomic demands, and environmental controls. WEFO is applied to quantitatively analyze the interrelationships and trade-offs among system components including energy supply, electricity generation, water supply-demand, food production as well as mitigation of environmental impacts. WEFO is demonstrated to solve a hypothetical nexus management problem consistent with real-world management scenarios. Model parameters are analyzed using global sensitivity analysis and their effects on total system cost are quantified. The obtained results demonstrate how these types of analyses can be helpful for decision-makers and stakeholders to make cost-effective decisions for optimal WEF management.
Display omitted
Sustainable agricultural economic development is the core task for achieving the objective of rural revitalization strategy in China, which cannot be separated from the support and guidance of fiscal ...policy, and agricultural industry integration is a key path for the fiscal promotion of sustainable agricultural economic development. This paper systematically examines the interaction mechanism between fiscal agricultural expenditures and sustainable agricultural economic development by using 31 provincial panel data in China from 2008 to 2020 and adopting a two-way fixed effect model, a panel quantile model, and a mediating effect model, respectively. The results show that the impact of fiscal agricultural expenditures on sustainable agricultural economic development is significantly positive, and appears a dynamic increasing trend with the agricultural development stage upgrading. Moreover, heterogeneity analysis shows that the effect of fiscal agricultural expenditures is more obvious for the samples in the central region and with a high share of primary industry. Further, a mediating effect test finds that agricultural industry integration plays a mediating mechanism between fiscal agricultural expenditures and sustainable agricultural economic development. Therefore, this paper proposes constructing a long-term investment mechanism for fiscal agricultural expenditures, formulating differentiated fiscal support policies for agriculture, and prioritizing support for agricultural industry integration, which provides theoretical support and policy inspiration for promoting sustainable agricultural economic development.
PDF
