This paper aims at designing a nonasymptotic and robust pseudo-state estimator for a class of fractional order linear systems which can be transformed into the Brunovsky's observable canonical form ...of pseudo-state space representation with unknown initial conditions. First, this form is expressed by a fractional order linear differential equation involving the initial values of the fractional sequential derivatives of the output, based on which the modulating functions method is applied. Then, the former initial values and the fractional derivatives of the output are exactly given by algebraic integral formulae using a recursive way, which are used to nonasymptotically estimate the pseudo-state of the system in noisy environment. Second, the pseudo-state estimator is studied in discrete noisy case, which contains the numerical error due to a used numerical integration method, and the noise error contribution due to a class of stochastic processes. Then, the noise error contribution is analyzed, where an error bound useful for the selection of design parameter is provided. Finally, numerical examples illustrate the efficiency of the proposed pseudo-state estimator, where some comparisons with the fractional order Luenberger-like observer and a new fractional order H ∞ -like observer are given.
In this paper, a non-asymptotic and robust method is proposed to estimate the fractional integral and derivative of the pseudo-state for a class of fractional order linear systems in noisy ...environment with unknown initial conditions. To the best of our knowledge, no method has been developed for such estimation. Firstly, the estimation problem is transformed into estimating the fractional integral and derivative of the output and a set of fractional derivative initial values. Then, algebraic integral formulas are exactly derived for the sought estimators by applying different modulating functions with specified properties. In particular, a design parameter is introduced in the formulas of fractional derivative initial values, which can improve the robustness by choosing appropriate values. Secondly, it is shown how to construct the required modulating functions in an efficient way, where another design parameter is involved. Moreover, some error analysis is given to choose the design parameters. Finally, numerical simulations are provided to demonstrate the efficiency and the robustness to noises of the proposed method.
New anthracene‐bridged organic dyes CXC12 and CXC22 are designed and synthesized for high‐efficiency dye‐sensitized solar cells (DSSCs) under dim light. Compared to their parent dye TY6, CXC dyes ...have additional anthracene‐acetylene group to extend the π‐conjugation of the molecules, resulting in red‐shifted absorption and an enhanced molar extinction coefficient. The absorption spectra of CXC12 and CXC22 with a maximum located at 561 and 487 nm, respectively, match to those of AM 1.5G sunlight and T5 fluorescent light better than that of TY6 (419 nm). It was initially anticipated that long alkoxyl chains introduced to the 2,6‐position of the bridged anthracenyl in CXC12 will retard charge recombination and dye molecular aggregation, and achieve a higher device open‐circuit voltage. However, adsorption of CXC12 molecules on the photoanode dramatically decrease to less than half as compared to that of CXC22 and TY6, resulting in lower short‐circuit current and thus power conversion efficiency. Among these three anthracene‐based dyes, CXC22 has the most appropriate molecular structure for light harvesting and striking the balance between dye loading and molecular aggregation, to exhibit a remarkable power conversion efficiency as high as 37.07% under dim‐light. Therefore, this work shows the potential of anthracene‐bridged organic dyes for indoor photovoltaic applications.
Bis‐anthracene‐based organic dye CXC22 is synthesized for high‐efficiency dye‐sensitized solar cells (DSSCs) that exhibit a remarkable power conversion efficiency as high as 37.07% under dim light. CXC22 has stronger and red‐shifted absorption due to a more extensive π‐backbone of in its molecular skeleton compared to its parent dye TY6, showing the potential of anthracene‐based dyes for indoor photovoltaics.
Sudden shifts towards online education since the outbreak of Covid-19 propelled the unprepared changes in teaching and learning over the world. The impact of transferring Interpreter training from ...face-to-face instruction and practices to a fully online environment was viewed differently. Issues such as relatively inferior engagement in learning and dissatisfied performance in competence building were highlighted and compounded by the concern of academic burnout and learning stress caused by the abiding pandemic. To curb the unsatisfactory situation, alternative learning methods and innovative pedagogical approaches were advocated. The present study was a pioneering effort to integrate informal learning into remote interpreter training by developing and implementing an online informal learning communities for undergraduate interpreting trainees in a Chinese university. The researcher recruited 36 students (n = 36) from the institution as participants in the 1.5-year piloting project. The findings of the research revealed the impact of informal learning in supplementing formal education by engaging involved students. Student-centered learning supported by collaborative and experiential activities in an informal environment was well-received for its ability to galvanize student’s engagement and academic achievements. The perceptions from participants revealed preference and expectation from students for expanded roles of trainers in interpreter training.
Advancement of research in education has propelled the augmentation of theoretical and practical knowledge in learning-oriented feedback. In recent years, the channels, modes, and orientations of ...feedback became manifold. Copious empirical evidence from the body of literature supported the strength of feedback in enhancing learning outcomes and promoting the motivation of learners. However, compared to the popularity in implementation and fruitfulness of findings in other educational domains, the application of state-of-the-art technology-enhanced feedback in fostering students' L2 oral abilities remain few and far between. To address the knowledge gap, the present study endeavored to investigate the effect of Danmaku-based and synchronous peer feedback on L2 oral performance and the acceptance thereof among students. Adopting a mixed-method design, the study recruited 74 (n = 74) undergraduate English majors from a Chinese university for a 16-week 2x2 experiment. The collected data were analyzed through statistical and thematic analysis respectively. The findings revealed that Danmaku-based and synchronous peer feed-back was impactful on students' performance in L2 oral production. Furthermore, the impacts of peer feedback on subdomains of L2 competence were statistically analyzed. Regarding students' perceptions, the incorporation of peer feedback was generally favored by participants who were satisfied and motivated in the learning process but lacked confidence in their assessment literacy. Furthermore, students expressed their agreement with the benefit of reflective learning and the subsequent enrichment in knowledge and horizon. The research was significant for its conceptual and practical contribution for follow-up researchers and educators in L2 education and learning-oriented feedback.
MicroRNAs (miRNAs) exhibit various roles in multiple biological processes and abnormal expression of miR‐182‐5p has been involved in many diseases. However, the role miR‐182‐5p in Atherosclerosis ...(AS) remains poorly understood. In our current investigation, an AS model was established by using oxidized low‐density lipoprotein (ox‐LDL) in RAW264.7 cells. miR‐182‐5p was markedly decreased in AS model dose‐dependently and time‐dependently. Additionally, CD36, oil‐red staining levels, TC, and TG were inhibited by miR‐182‐5p mimics, meanwhile ROS levels, MDA, and cell apoptosis were also restrained with an enhancement of SOD activity. Consistently, opposite results were exhibited when miR‐182‐5p inhibitors were transfected into RAW264.7 cells. It is well known that toll‐like receptor 4 (TLR4) is responsible for many inflammation diseases. By using bioinformatics analysis, TLR4 was indicated as a potential target of miR‐182‐5p. We observed TLR4 was activated in AS models and miR‐182‐5p could repress AS progression by targeting TLR4 in vitro. In conclusion, we uncovered that miR‐182‐5p played significant roles in AS through inhibiting oxidative stress and apoptosis via inactivating TLR4 expression.
Our study indicated a crucial role of miR‐182‐5p in AS development. TLR4 was shown as a target of miR‐182‐5p. We demonstrated that miR‐182‐5p can be identified as an inhibitor of AS via inactivating TLR4 pathway.
This paper presents the implementation of Luneburg lens antenna based on a 2-D parallel-plate structure for broadband multibeam radiation at millimeter-wave frequencies. In particular, each beam ...pattern of this 2-D Luneburg lens antenna has a narrow beamwidth along the multibeam dimension, and exhibits a broad beamwidth along the other cross section, analogous to the radiation from a 1-D array of antennas embedded inside the parallel-plate structure. Furthermore, the isolation to external structures by the top and bottom metal parallel plates may reduce the beam distortion from external interferences, and therefore enhance its compatibility to integrate with other radio frequency (RF) components to form an RF subsystem module. In addition, a theoretic model to realize the dielectric variation of Luneburg lens is developed by using stacked multiple planar layered dielectric materials for a cheap manufacture. In this paper, numerical simulation to validate the developed model of 2-D Luneburg lens design is first presented. Afterward, simulation and experimental measurement results of a practical design are both presented to validate the design concept.
•A stochastic modeling method with OB models to predict district loads is proposed.•This method was applied to a case study in China using the DeST simulation engine.•This study summarizes the ...typical occupancy schedules and OB modes in HSCW of China.•The proposed method performs better than two conventional simulation methods.•Applications and limitations of the proposed method are also discussed.
District cooling systems are widely used in urban residential communities in China. Most of such systems are oversized, which leads to wasted investment, low operational efficiency and, thus, waste of energy. The accurate prediction of district cooling loads that can support the rightsizing of cooling plant equipment remains a challenge. This study develops a novel stochastic modeling method that consists of (1) six prototype house models representing most apartments in a district, (2) occupant behavior models of residential buildings reflecting their spatial and temporal diversity as well as their complexity based on a large-scale residential survey in China, and (3) a stochastic sampling process to represent all apartments and occupants in the district. The stochastic method was applied to a case study using the Designer’s Simulation Toolkit (DeST) to simulate the cooling loads of a residential district in Wuhan, China. The simulation results agreed well with the measured data based on five performance metrics representing the aggregated cooling consumption, the peak cooling loads, the spatial load distribution, the temporal load distribution and the load profiles. Two prevalent simulation methods were also employed to simulate the district cooling loads. The results showed that oversimplified assumptions about occupant behavior could lead to significant overestimation of the peak cooling load and the total cooling loads in the district. Future work will aim to simplify the workflow and data requirements of the stochastic method for its application, and to explore its use in predicting district heating loads and in commercial or mixed-use districts.
Abstract
An interesting result that was recently reported for Mrk 421 is the detection of a significant excess at hard X-ray energies, which could provide useful information to investigate particle ...acceleration and emission mechanisms in the relativistic jet. Considering a two-injection scenario, we develop a self-consistent one-zone leptonic model to understand the origin of the hard X-ray excess in Mrk 421 during the period of extremely low X-ray and very high-energy flux in 2013 January. In the model, two populations of mono-energetic ultra-relativistic electrons are injected into the emission region, which is a magnetized plasmoid propagating along the blazar jet. We numerically calculate the emitting electron energy distribution by solving a kinetic equation that incorporates both shock acceleration and stochastic acceleration processes. Moreover, we infer analytic expressions relating the electrons’ acceleration, cooling, escape, and injection to the observed spectra and variability. In particular, for the injection luminosity, we derive a new approximate analytical expression for the case of continual injection with a mono-energetic distribution. Based on a comparison between the theoretical predictions and the observed SED, we conclude that the hard X-ray excess that was observed in Mrk 421 may be due to the synchrotron radiation emitted by an additional electron population, which is co-spatial with an electron population producing simultaneous optical/UV, soft X-ray, and
γ
-ray emissions. Therefore, stochastic acceleration may play a major role in producing the observed X-ray spectrum.
PDF
