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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 3809-3816 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The behavior of tethered polymers on gel/gel adhesion is studied with the single-chain mean-field (SCMF) theory. It is shown that the gel surface structure, the gel/gel adhesion strength, the equilibrium gel/gel distance, and the detailed interface structures can be tailored by specifically designed tethered layers on gel surfaces. The SCMF theory allows to study the effect of various variables of tethered layers, such as the surface coverage, the attraction between polymers and gels, and the composition of block copolymers. These theoretical results provide guidelines for experimental designs of novel gel materials with tethered layers. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a laser heated diamond anvil cell system at the GeoSoilEnviroCARS sector at the Advanced Photon Source. The system can be used for in situ x-ray measurements at simultaneously ultrahigh pressures (to 〉150 GPa) and ultrahigh temperatures (to 〉4000 K). Design goals of the laser heating system include generation of a large heating volume compared to the x-ray beam size, minimization of the sample temperature gradients both radially and axially in the diamond anvil cell, and maximization of heating stability. The system is based on double-sided laser heating technique and consists of two Nd:YLF lasers with one operating in TEM00 mode and the other in TEM01* mode, optics to heat the sample from both sides, and two spectroradiometric systems for temperature measurements on both sides. When combined with an x-ray microbeam (3–10 μm) technique, a temperature variation of less than 50 K can be achieved within an x-ray sampled region for longer than 10 min. The system has been used to obtain in situ structural data and high temperature equations of state on metals, oxides, and silicates to 3500 K and 160 GPa. © 2001 American Institute of Physics.
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  • 3
    Publication Date: 2015-08-11
    Description: In this study, we developed a new method for in-situ pressure determination in multi-anvil, high-pressure apparatus using an acoustic travel time approach within the framework of acoustoelasticity. The ultrasonic travel times of polycrystalline Al 2 O 3 were calibrated against NaCl pressure scale up to 15 GPa and 900 °C in a Kawai-type double-stage multi-anvil apparatus in conjunction with synchrotron X-radiation, thereby providing a convenient and reliable gauge for pressure determination at ambient and high temperatures. The pressures derived from this new travel time method are in excellent agreement with those from the fixed-point methods. Application of this new pressure gauge in an offline experiment revealed a remarkable agreement of the densities of coesite with those from the previous single crystal compression studies under hydrostatic conditions, thus providing strong validation for the current travel time pressure scale. The travel time approach not only can be used for continuous in-situ pressure determination at room temperature, high temperatures, during compression and decompression, but also bears a unique capability that none of the previous scales can deliver, i.e., simultaneous pressure and temperature determination with a high accuracy (±0.16 GPa in pressure and ±17 °C in temperature). Therefore, the new in-situ Al 2 O 3 pressure gauge is expected to enable new and expanded opportunities for offline laboratory studies of solid and liquid materials under high pressure and high temperature in multi-anvil apparatus.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
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  • 4
    Publication Date: 2016-04-01
    Description: Generally, the phase structure change of Pb(B′ B″)O 3 –PZT solid solutions near a morphotropic phase boundary (MPB) can be originated from composition variations. Here our results show that the excess PbO and the sintering temperature can also result in the ferroelectric phase structure change in the Pb(Ni 1/3 Nb 2/3 )O 3 –Pb(Zr,Ti)O 3 (PNN–PZT)-based ceramics near the MPB. The dielectric, piezoelectric, and ferroelectric properties are dependent on the tetragonal phase content ( TP ) which is closely associated with the excess PbO and the sintering temperature. The temperature dependence of the polarization ( P )–electric field ( E ) hysteresis loops reveals that the tetragonal phase in the PNN–PZT-based ceramics has a lower activation energy ( E a ) for domain wall movement than that of the rhombohedral phase, thus resulting in easier polarization rotation. This is responsible for the phase structure–electrical property relationships in the PNN–PZT-based ceramics, exhibiting the dependence of the tetragonal phase content ( TP ) on the electrical properties.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
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  • 5
    Publication Date: 2015-12-29
    Description: In this paper, we study the long time behavior of solutions to a weakly dissipative fractional Korteweg de Vries (KdV) equation on the real line R . The main difficulty lies in that the dissipative term is a nonlocal operator. We overcome this difficulty by the commutator estimates and product estimates associated with fractional Laplacian. The asymptotical compactness of solution semigroup is proved by the tail estimates. Finally, we conclude the existence of ( H 2 ( R ), H 5 ( R )) global attractor of the weakly dissipative fractional KdV equation.
    Print ISSN: 0022-2488
    Electronic ISSN: 1089-7658
    Topics: Mathematics , Physics
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  • 6
    Publication Date: 2019
    Description: The electricity output from microbial fuel cell (MFC) with a microalgae assisted cathode is usually higher than that with an air cathode. The output of electricity from a photosynthetic microalgae MFC was positively correlated with the dissolved oxygen (DO) level in the microalgae assisted biocathode. However, DO is highly affected by the photosynthesis of microalgae, leading to the low stability in the electricity output that easily varies with the change in microalgae growth. In this study, to improve the electricity output stability of the MFC, a partially submerged carbon cloth cathode electrode was first investigated to use oxygen from both microalgae and air, with synthetic piggery wastewater used as the anolyte and anaerobically digested swine wastewater as the catholyte. When the DO levels dropped from 13.6–14.8 to 1.0–1.6 mg/L, the working voltages in the MFCs with partially submerged electrodes remained high (256–239 mV), whereas that for the conventional completely submerged electrodes dropped from 259 to 102 mV. The working voltages (average, 297 ± 26 mV) of the MFCs with the 50% submerged electrodes were significantly (p 〈 0.05) higher than with other partially or completely submerged electrodes. The associated maximum lipid production from wastewater was 250 ± 42 mg/L with lipid content of 41 ± 6% dry biomass. Although the partially submerged electrode had no significant effects on lipid production or nitrogen removal in wastewater, there was significant improvement in the stability of the electricity generated under variable conditions.
    Electronic ISSN: 1996-1073
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 7
    Publication Date: 2019
    Description: With the convening of the annual global climate conference, the issue of global climate change has gradually become the focus of attention of the international community. As the largest carbon emitter in the world, China is facing a serious situation of carbon emission reduction. This paper uses the IPCC (The Intergovernmental Panel on Climate Change) method to calculate the carbon emissions of energy consumption in China from 1996 to 2016, and uses it as a dependent variable to analyze the influencing factors. In this paper, five factors, total population, per capita GDP (Gross Domestic Product), urbanization level, primary energy consumption structure, technology level, and industrial structure are selected as the influencing factors of carbon emissions. Based on the expanded STIRPAT (Stochastic Impacts by Regression on Population, Affluence, and Technology) model, the influencing degree of different factors on carbon emissions of energy consumption is analyzed. The results show that the order of impact on carbon emissions from high to low is total population, per capita GDP, technology level, industrial structure, primary energy consumption structure, and urbanization level. On the basis of the above research, the carbon emissions of China′s energy consumption in the future are predicted under eight different scenarios. The results show that, when the population and economy keep a low growth rate, while improving the technology level can effectively control carbon emissions from energy consumption, China′s carbon emissions from energy consumption will reach 302.82 million tons in 2020.
    Electronic ISSN: 1996-1073
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 8
    Publication Date: 2019
    Description: To solve the self-alignment problem of the Strapdown Inertial Navigation System (SINS), a novel adaptive filter based on Complementary Ensemble Empirical Mode Decomposition (CEEMD) is proposed. The Gravitational Apparent Motion (GAM) is used in the coarse alignment, and the problem of obtaining the attitude matrix between the body frame and the navigation frame is attributed to obtaining the matrix between the initial body frame and the current navigation frame using two gravitational apparent motion vectors at different moments. However, the accuracy and time of this alignment method always suffer from the measurement noise of sensors. Thus, a novel adaptive filter based on CEEMD using an l 2 -norm to calculate the similarity measure between the Probability Density Function (PDF) of each Intrinsic Mode Function (IMF) and the original signal is proposed to denoise the measurements of the accelerometer. Furthermore, the advantage of this filter is verified by comparing with other conventional denoising methods, such as PDF-based EMD (EMD-PDF) and the Finite Impulse Response (FIR) digital low-pass filter method. The results of the simulation and experiments indicate that the proposed method performs better than the conventional methods in both alignment time and alignment accuracy.
    Electronic ISSN: 1424-8220
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Published by MDPI
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  • 9
    Publication Date: 2018
    Description: The motivation of this work is to help outpatients find their corresponding departments or clinics, thus, it needs to provide indoor positioning services with a room-level accuracy. Unlike wireless outdoor localization that is dominated by the global positioning system (GPS), wireless indoor localization is still an open issue. Many different schemes are being developed to meet the increasing demand for indoor localization services. In this paper, we investigated the AoA-based wireless indoor localization for outpatients’ wayfinding in a hospital, where Wi-Fi access points (APs) are deployed, in line, on the ceiling. The target position can be determined by a mobile device, like a smartphone, through an efficient geometric calculation with two known APs coordinates and the angles of the incident radios. All possible positions in which the target may appear have been comprehensively investigated, and the corresponding solutions were proven to be the same. Experimental results show that localization error was less than 2.5 m, about 80% of the time, which can satisfy the outpatients’ requirements for wayfinding.
    Electronic ISSN: 1424-8220
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Published by MDPI
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  • 10
    Publication Date: 2019
    Description: Model-free reinforcement learning is a powerful and efficient machine-learning paradigm which has been generally used in the robotic control domain. In the reinforcement learning setting, the value function method learns policies by maximizing the state-action value (Q value), but it suffers from inaccurate Q estimation and results in poor performance in a stochastic environment. To mitigate this issue, we present an approach based on the actor-critic framework, and in the critic branch we modify the manner of estimating Q-value by introducing the advantage function, such as dueling network, which can estimate the action-advantage value. The action-advantage value is independent of state and environment noise, we use it as a fine-tuning factor to the estimated Q value. We refer to this approach as the actor-dueling-critic (ADC) network since the frame is inspired by the dueling network. Furthermore, we redesign the dueling network part in the critic branch to make it adapt to the continuous action space. The method was tested on gym classic control environments and an obstacle avoidance environment, and we design a noise environment to test the training stability. The results indicate the ADC approach is more stable and converges faster than the DDPG method in noise environments.
    Electronic ISSN: 1424-8220
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Published by MDPI
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