349 research outputs found
FIGURE 1 in The complete mitochondrial genome of Thereuopoda clunifera (Chilopoda: Scutigeridae) and phylogenetic implications within Chilopoda
No full textFIGURE 1. Circular map of the mitochondrial genome of T. cluniferaPublished as part of Zhao, Xinyi, Lu, Yifan, Fan, Shiming, Xu, Wei, Wang, Jiachen, Wang, Guobing & Liu, Hongyi, 2022, The complete mitochondrial genome of Thereuopoda clunifera (Chilopoda: Scutigeridae) and phylogenetic implications within Chilopoda, pp. 165-180 in Zootaxa 5174 (2) on page 169, DOI: 10.11646/zootaxa.5174.2.3, http://zenodo.org/record/698613
State of the art and outlook of energy tunnels: Design, construction, and thermal systems
No full textEnergy tunnel is thermally activated through embedding absorber pipes within the tunnel lining, where the underground heat is extracted and transferred above the ground via a heat pump for building energy applications. Energy tunnel offers advantages such as low carbon emissions, cleanliness, high efficiency, and safety. The heat source can be either outside or inside the tunnel. This article first categorizes energy tunnels into external and internal heat source energy tunnels, describes the characteristics of the environment inside and outside of these tunnels and their methods of construction, and some practical projects. Subsequently, the energy utilization systems with different heat sources are analyzed, underlining the critical role of heat transfer process being closely linked to the arrangement of absorber pipes with different heat sources. Factors affecting the heat transfer performance are then reviewed and the measures to enhance heat transfer are systematically discussed. Finally, the future study and application of different types of energy tunnels are proposed. Current research studies on energy tunnels primarily focus on transportation and mining tunnels, extracting geothermal energy generated outside the tunnels. However, studies and application of waste heat within energy tunnels are currently insufficient. Moreover, the design of natural geothermal energy collection, structural safety of the tunnel facilities, along with concerns regarding condensate water generated within the energy tunnel, necessitate further investigations
A hybrid control method for a bidirectional converter used in micro-grid systems
No full textThe stability control and power quality improvement of micro-grid systems using a bidirectional converter is studied. In consideration of the fact that the traditional converters like dynamic voltage regulator (DVR), static var generator (SVG), active power filter (APF) cannot be directly applied to micro grids due to the reasons of their dynamic response, power level and economy, a compound control method based on the nonlinear control theory is proposed. The method uses feedback linearization to control the inner current loop to turn the complex nonlinear system into a linear system, and fully decouples active and reactive current to improve the tracking precision and dynamic response of the inner current roop, and also improve fast response capability of the voltage outer loop; at the same time, it uses the sliding mode to control the voltage outer loop to solve the problem of time-varying parameters and to improve the robustness and anti-interference of the outer loop voltage. The experiments show that this composite control method has the abilities of fast dynamic response, higher precision, smaller harmonic of the AC side current, and the DC side voltage has the fast dynamic response
COMPUTATIONAL STUDY OF LIQUID-SOLID INTERFACE
No full textThe solid interface is of fundamental importance to numerous scientific and technological fields, such as heterogeneous catalysis, water splitting, electrochemistry, corrosion, drug delivery, tribology, and wetting. However, there is still limited knowledge of the structures and properties of the first adsorbed monolayer at distinct solid interfaces. We perform theoretical calculations to study the interactions between the solid surfaces and the first adsorbed monolayer at the interface, to understand from the electronic/atomic levels how the properties of solid surface influence the adsorption of the first monolayer at the solid interfaces.
In Chapter 3, we developed the force field parameter for the thiolate/defective Au(111) interface. A molecular-level understanding of the interplay between self-assembled monolayers (SAMs) of thiolates and gold surface is of great importance to a wide range of applications in surface science and nanotechnology. Despite theoretical research progress of the past decade, an atomistic model, capable of describing key features of SAMs at reconstructed gold surfaces, is still missing. We carried out the periodic ab initio density functional theory (DFT) calculations to develop a new atomistic force field model for alkanethiolate SAMs on a reconstructed Au(111) surface. Based on the newly-developed force field parameters, the molecular dynamics (MD) simulations showed that the geometrical features of the investigated Au−S interface models and structural properties of the C10S SAMs are in good agreement with the ab initio MD studies.
In Chapter 4, we investigate the wettability transition of the first adsorbed water layer (FAWL) on metal surfaces under a compressive lattice strain. A molecular-level description of a near-surface water structure and a handy manipulation of its properties are relevant to a broad range of scientific and technological phenomena. Through a series of MD simulations, we report the observation and characterization of a low-mobility FAWL and its tunable wetting transition at three metal surface models. The results reveal that (i) there is a formation of the FAWL, resulting from competitive water−water hydrogen bonding and water−solid interactions, which in turn dictates the wettability at water−metal interfaces, (ii) applying compressive lattice strain to metal substrates can induce interfacial wettability transition, and (iii) by adjusting the lattice strains, the bimetallic junction can host a switchable wettability transition.
In Chapter 5, we study the structures and dynamics of the FAWL at distinct titanium dioxide (TiO2) surfaces. The behavior of the FAWL at TiO2 surfaces is critical to the fundamental understanding of TiO2-based applications. Using classical MD simulations, we study the properties of FAWL at four TiO2 surfaces, including the density profile, the angular orientation distribution, the HB structural and dynamic properties, and the vibrational spectra of water molecules in the FAWL. The calculation results demonstrate that the water molecules show distinct adsorption structures and HB properties at the studied TiO2 surfaces, leading to completely different vibrational signatures for the OH groups.
In Chapter 6, we explore the role of interfacial potassium on the surface-enhanced Raman spectroscopy for single-crystal TiO2 nanowhisker by combining experiments and theoretical calculations. For TiO2-based surface-enhanced Raman spectroscopy (SERS) substrates, maintaining a good crystallinity is critical to achieving excellent Raman scattering. we report the successful synthesis of TiO2 nanowhiskers with excellent SERS properties. The enhancement factor, an index of SERS performance, is 4.96×106 for methylene blue molecule detecting, with a detection sensitivity around 10−7 mol·L−1. The DFT calculations reveal that interfacial potassium can form a monolayer structure on the TiO2 surface, resulting in a negatively charged TiO2 nanowhisker surface. Such structures would promote the adsorption of methylene blue molecules and thereby significantly improves SERS performance via the electrostatic adsorption effect.
In Chapter 7, we investigate the friction of ionic liquid (IL)–glycol ether mixtures by combining AFM experiments and nonequilibrium MD (NEMD) simulations. We have measured the negative “friction–load dependence” of IL/oil mixtures at Ti interfaces. Such a negative phenomenon was also confirmed by our NEMD simulations, in which the friction force declines as the normal load increases. NEMD simulations revealed a structural reorientation of the studied IL as the normal load increases, i.e., the cation alkyl chains of ILs change the orientation to preferentially stay parallel to the tip scanning path, similar to the “blooming lotus leaf.” This reoriented IL structures produce a new sliding interface and reduce the friction force
Influence of Measurement Uncertainty on Parameter Estimation and Fault Location for Transmission Lines
No full textFault location algorithms for transmission lines use the parameters of the transmission line to locate faults after the faults have occurred along the line. Although these parameters can be estimated by the phasor measurement units (PMUs) at the terminal(s) of the transmission line continuously, the uncertainty in the measurements will give rise to stochastic errors in the measured values. Thus, the uncertainty in measurements definitely influences the estimations of the parameters of the transmission line, which, in turn, influences the results of fault location algorithms. Inaccurate results of fault location algorithms may lead to costly maintenance fees and prolonged outage time. Therefore, in this article, we estimate the parameters of the transmission line considering the uncertainty in the measurements so that a more accurate fault location can be derived. The uncertainty in the measurements will be modeled as a stochastic distribution, and the maximum likelihood estimation (MLE) method will be adopted to reduce the uncertainty in the measurements. In addition, as an illustration, the telegrapher's equations will be used to calculate the parameters of the transmission line, and the two-terminal positive sequence network fault location algorithm will be used to locate the fault. In a simulation, a case study of a real-life transmission line the influence of the uncertainty in the measurements on the transmission line parameter estimations and the effectiveness of the MLE method for estimations are simulated and analyzed. The results show that the influence of the uncertainty in the measurements on the positive sequence network fault location algorithm should not be neglected and that the proposed method is very effective in significantly reducing the influence of the uncertainty in the measurements.Accepted Author ManuscriptTeam Bart De SchutterDelft Center for Systems and Contro
CREDIBILITY EVALUATION FOR BLIND PROCESSING RESULTS OF BPSK SIGNALS BY USING PHASE SPECTRAL ENTROPY
No full text
Credibility Evaluation for Blind Processing Results of BPSK Signals by Using Phase Spectral Entropy
No full textAbstract
A credibility test method based on the features of frequency domain entropy of a phase is proposed to evaluate the blind processing results of a BPSK signal. Initially, a reference signal was constructed depending on the certain identified modulation results. By analyzing the differences of the phase of the correlation series between the observed signal and the reference signal, a reliability test problem for the BPSK signal is performed by calculating the phase spectrum entropy and comparing it with a certain threshold. Simulation results show that the proposed method can be used to verify the reliability of the blind processing results of a BPSK signal at a low signal-to-noise ratio and without a priori knowledge of the signal parameters.</jats:p
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