Summary
By using the adaptive control approach, we solve the error feedback regulator problem for the one‐dimensional wave equation with a general harmonic disturbance anticollocated with control and ...with two types of disturbed measurements, ie, one collocated with control and the other anti‐collocated with control. Different from the classical error feedback regulator design, which is based on the internal mode principle, we give the adaptive servomechanism design for the system by making use of the measured tracking error (and its time derivative) and the estimation mechanism for the parameters of the disturbance and of the unknown reference. Constructing auxiliary systems and observer and applying the backstepping method for infinite‐dimensional system play important roles in the design. The control objective, which is to regulate the tracking error to zero and to keep the states bounded, is achieved.
The development of highly efficient and durable electrocatalysts for the nitrogen reduction reaction (NRR) is of paramount significance for NH3 electrosynthesis. Herein, we report an effective ...B-doping strategy for the structural engineering of MnO2 toward the NRR through combined experimental and theoretical studies. Introducing B-dopants into MnO2 nanosheets was found to create abundant O-vacancies which cooperated with B-dopants to promote the conductivity and enhance the intrinsic NRR activity of MnO2. The developed B-doped MnO2 nanosheets grown on carbon cloth (B-MnO2/CC) exhibited a significantly enhanced NRR performance with an NH3 yield of 54.2 μg h−1 mg−1 (−0.4 V) and a faradaic efficiency of 16.8% (−0.2 V), and are among the best Mn-based NRR catalysts reported so far. Density functional theory calculations further revealed the synergistic role of B-dopants and O-vacancies in inducing asymmetric charge distribution, which could activate the neighboring Mn atoms to facilitate the stabilization of the key intermediate *N2H on MnO2, leading to reduced reaction energy barrier and enhanced intrinsic NRR activity.
The active disturbance rejection control (ADRC) is now considered as a powerful control strategy in dealing with large uncertainty covering unknown dynamics, external disturbance, and unknown part in ...coefficient of the control. However, all theoretical works up to present are limited to deterministic uncertainty. In this technical note, we generalize the ADRC to uncertain nonlinear systems subject to external bounded stochastic disturbance described by an uncertain stochastic differential equation driven by white noise. We first design an extended state observer (ESO) that is used to estimate both state, and total disturbance which includes the internal uncertain nonlinear part and the external uncertain stochastic disturbance. It is shown that the resulting closed-loop system is practically stable in the mean-square topology. The numerical experiments are carried out to illustrate effectiveness of the proposed approach.
China is making efforts to promote the equalization of National Essential Public Health Services (NEPHS) for internal migrants. Studies have demonstrated that the impacts of social capital on health ...services are different among subgroups of people. Clarifying these differences will help China accurately promote the equalization of NEPHS for the internal migrants and provide reference for other countries.
Data from the China Migrant Dynamic Survey of 2017, involving 130,642 migrants in 31 provinces were used to clarify the complex relationship between social capital and the utilization of NEPHS. Social capital was divided into regional cognitive social capital (RCSC), regional structural social capital (RSSC), individual cognitive social capital (ICSC), and individual structural social capital (ISSC). Then, multi-level logistic regression was conducted to analyze their impacts on the utilization of NEPHS of the migrants, and whether such impacts are moderated by sex and education.
(1) There are significant differences in the levels of CSC, SSC, and NEPHS utilization between different sexs and educational subgroups of the migrants, among which the educational difference is more prominent. (2) An interaction exists between the levels and dimensions of social capital and NEPHS projects. Also, the impact of SSC on NEPHS is always greater than that of CSC at the same level. (3) The effects of RCSC, RSSC, ICSC, and ISSC on NEPHS utilization by migrants are not moderated by sex. However, a high education could weaken the relationship between RCSC and health education, ISSC and health education, and RSSC and health records but strengthen the correlation between RSSC and health education.
Social capital plays an important role in the access of migrants to NEPHS. Governments should vigorously promote the construction of regional social capital, encourage migrants to actively participate in community activities, especially pay attention to the enhancement of the migrants with low SES to the destination identity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this paper, we consider boundary stabilization for a multi-dimensional wave equation with boundary control matched disturbance that depends on both time and spatial variables. The active ...disturbance rejection control (ADRC) approach is adopted in investigation. An extended state observer is designed to estimate the disturbance based on an infinite number of ordinary differential equations obtained from the original multi-dimensional system by infinitely many test functions. The disturbance is canceled in the feedback loop together with a collocated stabilizing controller. All subsystems in the closed-loop are shown to be asymptotically stable. In particular, the time varying high gain is first time applied to a system described by the partial differential equation for complete disturbance rejection purpose and the peaking value reduction caused by the constant high gain in literature. The overall picture of the ADRC in dealing with the disturbance for multi-dimensional partial differential equation is presented through this system. The numerical experiments are carried out to illustrate the convergence and effect of peaking value reduction.
Regional disparities and individual determinants have a significant impact on the accessibility of national essential public health services (NEPHS) for internal migrants (IMs) Nevertheless, few ...studies have explored the interaction between these two factors.
A cross-sectional sample of 102,632 IMs from the 2017 China Migrant Dynamic Survey was selected. The 28 provinces were divided into high-income provinces (HIPs) and low and middle-income provinces (LMIPs) according to their per capita disposable income (PCDI). Logistic regression was conducted using sex, residence duration, education, community type, migration range, social participation and relative personal income as independent variables, NEPHS awareness and health records registration (HRR) as dependent variables, and regional economic development level (REDL) as a moderating variable.
The rate of NEPHS awareness and HRR in HIPs (60.7, 30.6%) were lower (x
= 42.486, p < 0.001; x
= 25.573, p < 0.001) than those in LMIPs (62.9, 32.2%). After controlling for other variables, NEPHS awareness (OR = 1.379, p < 0.001) and HRR (OR = 1.661, p < 0.001) of IMs in HIPs were higher. Sub-group proportion of education Ms. in HIPs were higher. Sub-group = 1.379, p < 0.001) and HRR dependent mong internal migrants:, 61.0, 42.2%) were higher than those in LMIPs (60.4, 19.7, 35.8, 25.5%). Among urban communities, intra-provincial migration, social participation, education > 9 years, and middle-income, the protective effect of the first three factors on NEPHS awareness was greater in HIPs (OR = 1.386, p < 0.001; OR = 1.383, p < 0.001; OR = 2.008, p < 0.001) than in LMIPs (OR = 1.053, p < 0.001; OR = 1.109, p < 0.001; OR = 1.861, p < 0.001), while the effect of all five factors on HRR was greater in HIPs (OR = 1.440, p < 0.001; OR = 1.380, p < 0.001; OR = 1.895, p < 0.001; OR = 1.148, p < 0.001; OR = 1.146, p < 0.001) than in LMIPs (OR = 1.045, p < 0.05; OR = 1.169, p < 0.001; OR = 1.677, p < 0.001; OR = 1.027, p > 0.05; OR = 1.028, p > 0.05).
REDL directly affected the NEPHS utilization of IMs, and the negative effects of vulnerable characteristics on the NEPHS utilization of IMs were amplified in HIPs. The government is urged to regard IMs with vulnerable characteristics in HIPs as the key population in future NEPHS equalization and take targeted measures to stimulate their enthusiasm to participate in NEPHS.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Photon blockade is an effective way to generate single photon, which is of great significance in quantum state preparation and quantum information processing. Here we investigate the statistical ...properties of photons in a double-cavity optomechanical system with nonreciprocal coupling, and explore the photon blockade in the weak and strong coupling regions respectively. To achieve the strong photon blockade, we give the optimal parameter relations under different blockade mechanisms. Moreover, we find that the photon blockades under their respective mechanisms exhibit completely different behaviors with the change of nonreciprocal coupling, and the perfect photon blockade can be achieved without an excessively large optomechanical coupling, i.e., the optomechanical coupling is much smaller than the mechanical frequency, which breaks the traditional cognition. Our proposal provides a feasible and flexible platform for the realization of single-photon source.
Coordination networks that reversibly switch between closed and open phases are of topical interest since their stepped isotherms can offer higher working capacities for gas‐storage applications than ...the related rigid porous coordination networks. To be of practical utility, the pressures at which switching occurs, the gate‐opening and gate‐closing pressures, must lie between the storage and delivery pressures. Here we study the effect of linker substitution to fine‐tune gate‐opening and gate‐closing pressure. Specifically, three variants of a previously reported pcu‐topology MOF, X‐pcu‐5‐Zn, have been prepared: X‐pcu‐6‐Zn, 6=1,2‐bis(4‐pyridyl)ethane (bpe), X‐pcu‐7‐Zn, 7=1,2‐bis(4‐pyridyl)acetylene (bpa), and X‐pcu‐8‐Zn, 8=4,4′‐azopyridine (apy). Each exhibited switching isotherms but at different gate‐opening pressures. The N2, CO2, C2H2, and C2H4 adsorption isotherms consistently indicated that the most flexible dipyridyl organic linker, 6, afforded lower gate‐opening and gate‐closing pressures. This simple design principle enables a rational control of the switching behavior in adsorbent materials.
Pillars of adsorption: Pillar substitution enables the fine‐tuning of the gate‐opening/gate‐closing pressures for a family of flexible coordination networks. The fact that linker flexibility favors lower gate‐opening pressure has broad implications for controlling a key parameter of switching adsorbent materials.
Removal of arsenic (As) from water supplies is needed to reduce As exposure through drinking water and food consumption in many regions of the world. Magnetite nanoparticles (MNPs) are promising and ...novel adsorbents for As removal because of their great adsorption capacity for As and easy separation. This study aimed to investigate the adsorption mechanism of arsenate, As(V), and arsenite, As(III), on MNPs by macroscopic adsorption experiments in combination with thermodynamic calculation and microspectroscopic characterization using synchrotron-radiation-based X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS). Adsorption reactions are favorable endothermic processes as evidenced by increased adsorption with increasing temperatures, and high positive enthalpy change. EXAFS spectra suggested predominant formation of bidentate binuclear corner-sharing complexes (2 C) for As(V), and tridentate hexanuclear corner-sharing (3 C) complexes for As(III) on MNP surfaces. The macroscopic and microscopic data conclusively identified the formation of inner-sphere complexes between As and MNP surfaces. More intriguingly, XANES and XPS results revealed complex redox transformation of the adsorbed As on MNPs exposed to air: Concomitant with the oxidation of MNPs, the oxidation of As(III) and MNPs was expected, but the observed As(V) reduction was surprising because of the role played by the reactive Fe(II).
Shewanella oneidensis MR‐1, a model strain of exoelectrogenic bacteria (EEB), plays a key role in environmental bioremediation and bioelectrochemical systems because of its unique respiration ...capacity. However, only a narrow range of substrates can be utilized by S. oneidensis MR‐1 as carbon sources, resulting in its limited applications. In this study, a rapid, highly efficient, and easily manipulated base‐editing system pCBEso was developed by fusing a Cas9 nickase (Cas9n (D10A)) with the cytidine deaminase rAPOBEC1 in S. oneidensis MR‐1. The C‐to‐T conversion of suitable C within the base‐editing window could be readily and efficiently achieved by the pCBEso system without requiring double‐strand break or repair templates. Moreover, double‐locus simultaneous editing was successfully accomplished with an efficiency of 87.5%. With this tool, the key genes involving in N‐acetylglucosamine (GlcNAc) or glucose metabolism in S. oneidensis MR‐1 were identified. Furthermore, an engineered strain with expanded carbon source utilization spectra was constructed and exhibited a higher degradation rate for multiple organic pollutants (i.e., azo dyes and organoarsenic compounds) than the wild‐type when glucose or GlcNAc was used as the sole carbon source. Such a base‐editing system could be readily applied to other EEB. This study not only enhances the substrate utilization and pollutant degradation capacities of S. oneidensis MR‐1 but also accelerates the robust construction of engineered strains for environmental bioremediation.
Cheng and coworkers have successfully developed a rapid and highly efficient base editing system‐pCBEso in Shewanella oneidensis MR‐1. With this tool, the authors identified the key genes involving in the N‐acetyl‐glucosamine metabolism and rapidly constructed an engineered strain with enhanced substrate utilization and pollutant degradation capacities. Such a base editing tool could be readily applied to other exoelectrogenic bacteria (EEB) and promote the application of EEB in bioremediation.
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