86 research outputs found
Opportunistic Wireless Control Over State-Dependent Fading Channels
The heterogeneous system consisting of the wireless control system (WCS) and
mobile agent system (MAS) is ubiquitous in Industrial Internet of Things (IIoT)
systems. Within this system, the positions of mobile agents may lead to shadow
fading on the wireless channel that the WCS is controlled over and can
significantly compromise the WCS's performance. This paper focuses on the
controller design for the MAS to ensure the performance of WCS in the presence
of WCS and MAS coupling. Firstly, the constrained finite field network (FFN)
with profile-dependent switching topology is adopted to proceed the operational
control for the MAS. By virtue of the algebraic state space representation
(ASSR) method, an equivalent form is obtained for the WCS and MAS coupling. A
necessary and sufficient condition in terms of constrained set stabilization is
then established to ensure the Lyapunov-like performance with expected decay
rate. Finally, a graphical method together with the breath-first searching is
provided to design state feedback controllers for the MAS. With this method, it
is easy to check the constrained set stabilization of MAS and to ensure the
performance requirements of WCS in the presence of WCS and MAS coupling. The
study of an illustrative example shows the effectiveness of the proposed
method
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Controlled mode tuning in 1-D âRIMâ plasmonic crystal trench cavities probed with coupled optical emitters
We present a design of plasmonic cavities that consists of two sets of 1-D plasmonic crystal reflectors on a plasmonic trench waveguide. A 'reverse image mold' (RIM) technique was developed to pattern high-resolution silver trenches and to embed emitters at the cavity field maximum, and FDTD simulations were performed to analyze the frequency response of the fabricated devices. Distinct cavity modes were observed from the photoluminescence spectra of the organic dye embedded within these cavities. The cavity geometry facilitates tuning of the modes through a change in cavity dimensions. Both the design and the fabrication technique presented could be extended to making trench waveguide-based plasmonic devices and circuits.Engineering and Applied Science
Convolutional Neural Networks and Feature Fusion for Flow Pattern Identification of the Subsea Jumper
The gasâliquid two-phase flow patterns of subsea jumpers are identified in this work using a multi-sensor information fusion technique, simultaneously collecting vibration signals and electrical capacitance tomography of stratified flow, slug flow, annular flow, and bubbly flow. The samples are then processed to obtain the data set. Additionally, the samples are trained and learned using the convolutional neural network (CNN) and feature fusion model, which are built based on experimental data. Finally, the four kinds of flow pattern samples are identified. The overall identification accuracy of the model is 95.3% for four patterns of gasâliquid two-phase flow in the jumper. Through the research of flow profile identification, the disadvantages of single sensor testing angle and incomplete information are dramatically improved, which has a great significance on the subsea jumperâs operation safety.publishedVersio
Atomic decoration for improving the efficiency of field electron emission of carbon nanotubes
The field electron emission from the single-walled carbon nanotubes with
their open ends terminated by -BH, -NH, and -O has been simulated. The
apex-vacuum barrier and the emission current have been calculated. It has been
found that -BH and -NH suppress the apex-vacuum barrier significantly and lead
to higher emission current in contrast to the -O terminated structure in the
same applied field. The calculated binding energy implies that the carbon
nanotubes terminated with -BH and -NH are more stable than those saturated by
oxygen atoms or by hydrogen atoms.Comment: 8 pages, 9 figures, LaTeX; content changed, typos corrected,
references adde
Paleocene to Pliocene low-latitude, high-elevation basins of southern Tibet: implications for tectonic models of India-Asia collision, Cenozoic climate, and geochemical weathering
The elevation history of the Tibetan Plateau promises insight into the mechanisms and dynamics that develop and sustain high topography over tens of millions of years. We present the first nearly continuous Cenozoic elevation history from two sedimentary basins on the southern Tibetan Plateau within the latest Cretaceous to Eocene Gangdese arc. Oxygen-isotope and Î47 clumped-isotope compositions of nonmarine carbonates allow us to constrain carbonate formation temperature and reconstruct the paleoprecipitation record of the Eocene to Pliocene Oiyug Basin and Paleocene to Eocene Penbo Basin. We exploit the systematic decrease of surface temperature and meteoric water ÎŽ18O values with elevation to derive paleoelevation estimates for these basins. Minimally altered and unaltered pedogenic and lacustrine carbonates from the Oiyug Basin yield Î47, CDES (relative to the carbon dioxide equilibrium scale [CDES]) values of 0.625â° to 0.755â°, which correspond to temperatures of 1â30 °C using a Î47 thermometer for low-temperature carbonates. Similarly, the Penbo Basin yielded Î47, CDES values of 0.701â° to 0.726â°, corresponding to temperatures of 6â12 °C. The apparent evidence for survival of primary clumped-isotope values in the face of substantial burial and heating is an important result for the field of carbonate clumped-isotope thermometry.
Our paleoelevation estimates for the Eocene to Pliocene Oiyug Basin (âŒ6.5â4.1 km) support previous evidence that high elevations were attained in southern Tibet by at least ca. 30 Ma. Stable-isotope results allow for the possibility of significant topographic subsidence during the Miocene as a result of regional extension. In the Penbo Basin, our paleoelevation estimates for the Paleocene to Eocene Nianbo Formation (4.4 +1.3/â1.7 km) and Eocene Pana Formation (4.1 +1.2/â1.6 km) extend the altitude record of the southern Tibetan Plateau to preâIndia-Asia collision. These results support the âLhasaplanoâ model of an Andean-type continental margin tectonic system.
The rise of the Himalayas and Tibet is often invoked to understand isotopic proxies for global chemical weathering in the Cenozoic and has constrained the debate on the nature of CO2âclimateâweathering feedbacks. The nature of the Tibetan paleoelevations from pre- to postcollision, as presented here, indicates that high relief at low latitude prevailed on the Asian margin much earlier than previously thought. Thus, high topography alone at low latitude is not sufficient to account for the Cenozoic weathering proxy record
Mechanism and Growth of Flexible ZnO Nanostructure Arrays in a Facile Controlled Way
Nanostructure arrays-based flexible devices have revolutionary impacts on the application of traditional semiconductor devices. Here, a one-step method to synthesize flexible ZnO nanostructure arrays on Zn-plated flexible substrate in Zn(NO3)2/NH3â
H2O solution system at 70â90âC was developed. We found out that the decomposition of Zn(OH)2 precipitations, formed in lower NH3â
H2O concentration, in the bulk solution facilitates the formation of flower-like structure. In higher temperature, 90âC, ZnO nanoplate arrays were synthesized by the hydrolysis of zinc hydroxide. Highly dense ZnO nanoparticale layer formed by the reaction of NH3â
H2O with Zn plating layer in the initial self-seed process could improve the vertical alignment of the nanowires arrays. The diameter of ZnO nanowire arrays, from 200ânm to 60ânm, could be effectively controlled by changing the stability of Zn(NH3)42+ complex ions by varying the ratio of Zn(NO3)2 to NH3â
H2O which further influence the release rate of Zn2+ ions. This is also conformed by different amounts of the Zn vacancy as determined by different UV emissions of the PL spectra in the range of 380â403ânm
The Characteristics of Sports Culture in the Zhuang Myth Bubo
This paper mainly adopts the method of the literature analysis and
combines knowledge of mythology, sports history, and ethnology to study
Bubo, a Zhuang myth about a hero named Bubo, who fought heroically
against the Thunder King and the Dragon King. By analyzing Buboâs
struggle with nature and the ruthless rulers, this paper reveals the sublime
heroism that consists of bravery, strength, wisdom, and fearlessness, and a
cultural tradition that emphasizes virtue, reason, life, and unity. Moreover,
this paper offers a glimpse of the characteristics of the Zhuang sports
culture behind the myth, including the humanistic trait of being peopleoriented, the code of conduct of observing morals and manners, the knighterrantry of rising above self, the need-based incentive of guiding people to
their merits, and the educational significance of promoting collectivism
Effects of Structured Physical Activity Program on Chinese Young Childrenâs Executive Functions and Perceived Physical Competence in a Day Care Center
Purpose. To examine the effects of a structured physical activity program on executive functions and perceived physical competence as compared to a traditional recess among preschool children. Methods. Participants were 40 preschool children aged 4-5 from an urban child care center in a southern Chinese metropolitan area. Prior to the intervention, baseline assessments of childrenâs executive functions and perceived physical competence were conducted. Children were then assigned to (1) intervention condition: a structured physical activity intervention group; (2) control condition: free-activity recess. The structured physical activity or recess programs were provided to the intervention and control groups 30 minutes daily for 3 months, respectively, followed by the identical postintervention measures. Results. Thirty-nine children (19 girls; mean age = 4.67 years old, BMI = 15.54±1.21) were included in the analysis. In general, childrenâs executive functions and perceived physical competence increased over time. Repeated measures analysis of variance revealed the intervention group had significant greater increases in executive functions compared to the control children (F(1, 37) = 4.20, p=0.04, η2=.10), yet there were no greater increases in perceived physical competence (F(1, 37) = 2.35, p=0.13, η2=.06). Conclusion. The intervention exerted significant greater increases in executive functions in preschool children. It is meaningful to offer structured physical activity programs in day care centers
Temperature and Humidity Effects on the Dynamic Stiffness of a Polyester Mooring Rope
In this paper, the nonlinear stiffness of a polyester rope under dynamic loads at different temperatures was experimentally investigated. The effects and evolution of the average load, load period and load amplitude on dynamic stiffness were studied. The experimental results show that the dynamic stiffness at 30 °C was greater than that at 20 °C and 40 °C. This is because the dynamic stiffness reduced as the temperature and humidity increased, while in the closed thermostat, humidity decreased with an increase in temperature. In response to this phenomenon, a new set of empirical equations was proposed to consider temperature, humidity, and dynamic load based on the existing empirical formulas, by combining the experimental results. A set of experiments was conducted at 25 °C to verify the accuracy and applicability of the formula. The experimental results and the predicted results are in good agreement
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