140 research outputs found
Simulations of engine knock flow field and wave-induced fatigue of a downsized gasoline engine
A mathematical correlation is developed, based on the thermodynamic model of a
downsized gasoline engine, to establish the numerical relationship among the
thermodynamic parameters of the combustion chamber. In the developed numerical
model, the in-cylinder pressure curves of various operation condition are simulated by
varying the air-fuel ratio in the cylinder, and the associated knock characteristics are
recorded. The accuracy of the numerical simulation results is verified against the
knock excitation experiment. Then, based on the Rover K16 gasoline engine, a
simulation model is developed to simulate the engine knock in the combustion
chamber and observe the force acting on the top surface of the piston. The results
show that the forces act on the piston top surface are varying at various locations at
the same time, and the largest forces occur at the edge of the piston and followed by
the piston centre. Then, by comparing the thermo-mechanical coupling strength of the
piston under different operating conditions, the results show that the occurrence of the
knocking does not exceed the piston's strength limit. However, the stress and
deformation value of the piston is increased significantly, and the failure point of the
piston position is changed. Finally, based on the calibrated strength results, the piston
durability is predicted for various engine knock conditions. The results show that the
initial damage of piston in the process of detonation at the surface of the piston pin
hole and the joint of the piston cavity. The gasoline engine finally has a predicted
mileage of 253,440 km continuously which meet the prescribed mileage of 220,000
km
Memristors with diffusive dynamics as synaptic emulators for neuromorphic computing
The accumulation and extrusion of Ca2+ in the pre- and postsynaptic compartments
play a critical role in initiating plastic changes in biological synapses. To emulate this fundamental process in electronic devices, we developed diffusive Ag-in-oxide
memristors with a temporal response during and after stimulation similar to that of the
synaptic Ca2+ dynamics. In situ high-resolution transmission electron microscopy and nanoparticle dynamics simulations both demonstrate that Ag atoms disperse under electrical bias and regroup spontaneously under zero bias because of interfacial energy minimization, closely resembling synaptic influx and extrusion of Ca2+, respectively. The diffusive memristor and its dynamics enable a direct emulation of both short- and long-term plasticity of biological synapses and represent a major advancement in hardware implementation of neuromorphic functionalities
Anatomy of Ag/Hafnia‐Based Selectors with 1010 Nonlinearity
Sneak path current is a significant remaining obstacle to the utilization of large crossbar arrays for non-volatile memories and other applications of memristors. A two-terminal selector device with
an extremely large current-voltage nonlinearity and low leakage current could solve this problem.
We present here a Ag/oxide-based threshold switching (TS) device with attractive features such
as high current-voltage nonlinearity (~1010
), steep turn-on slope (less than 1 mV/dec), low OFF-state leakage current (~10-14 A), fast turn ON/OFF speeds (108
cycles). The feasibility of using this selector with a typical memristor has been demonstrated by
physically integrating them into a multilayered 1S1R cell. Structural analysis of the nanoscale
crosspoint device suggests that elongation of a Ag nanoparticle under voltage bias followed by
spontaneous reformation of a more spherical shape after power off is responsible for the observed
threshold switching of the device. Such mechanism has been quantitatively verified by the Ag nanoparticle dynamics simulation based on thermal diffusion assisted by bipolar electrode effect and interfacial energy minimization
Superconducting magnetic separation of phosphate using freshly formed hydrous ferric oxide sols
<p>Paramagnetic materials, such as ferric hydroxides, which are cost-effective and highly-efficient, have been little studied in relation to the magnetic separation process. In this study, freshly formed hydrous ferric oxide (HFO) sols were used to remove aqueous phosphate, followed by superconducting magnetic separation. The magnetization of HFO was determined to be 5.7 emu/g in 5.0 T. The particle size distributions ranged from 1 to 80 μm. Ferrihydrite was the primary mineral phase according to XRD analysis. Dissolved P (DP) was first adsorbed on HFO, and second, the P-containing HFO were separated by high gradient superconducting magnetic separation (HGSMS) to remove the Total P (TP). To obtain a P concentration of <0.05 mg/l in the effluent, 0.3, 1.0 and 1.3 g/l HFO were added to 2.5, 5 and 10 mg/l P solutions. The capacity of the HGSMS canister for capturing P-adsorbed HFO depends on the magnetic intensity and flow rate. In the 5.0 T HGSMS at a 1.0 cm/s flow rate, there were 75 column volumes in a single HGSMS cycle. The P concentration increased by 37.5 times after regeneration. Approximately 170 mg/l TP was measured in the backwash water.</p
Effect of Substituent Groups in Anions on Some Physicochemical Properties of 1‑Butyl-3-methylimidazolium Carboxylate Ionic Liquids
In
this work, four 1-butyl-3-methylimidazolium carboxylate ionic
liquids (ILs) with different substituent groups in anions, including
1-butyl-3-methylimidazolium glycollate [C<sub>4</sub>mim][HOCH<sub>2</sub>COO], 1-butyl-3-methylimidazolium lactate [C<sub>4</sub>mim][CH<sub>3</sub>CHOHCOO], 1-butyl-3-methylimidazolium benzoate [C<sub>4</sub>mim][C<sub>6</sub>H<sub>5</sub>COO], and 1-butyl-3-methylimidazolium
glycinate [C<sub>4</sub>mim][H<sub>2</sub>NCH<sub>2</sub>COO], have
been synthesized and characterized. Their densities (ρ) and
surface tensions (γ) have been determined experimentally in
the temperature range of (298.15 to 343.15) K. By using thermodynamic
and empirical equations, molar volume (<i>V</i><sub>m</sub>), isobaric expansivity (α<sub><i>p</i></sub>), standard
entropy (<i>S</i>°), lattice energy (<i>U</i><sub>POT</sub>), surface excess entropy (<i>S</i><sub>s</sub>), vaporization enthalpy (Δ<sub>l</sub><sup>g</sup><i>H</i><sub>m</sub><sup>0</sup>) and Hildebrand solubility parameter
(δ<sub>H</sub>) of these ILs have been derived from density
and surface tension data. The effects of substituent groups in carboxylate
anions on densities and surface tensions of these ILs have been assessed
from the analysis of the structure–property relationship
Neighbor-joining phylogenetic tree based on 16S rRNA gene sequence (<i>ca</i>.1,400 bp) of actinomycetes from the tissue of soft coral <i>Scleronephthya</i> sp.
<p>The sequences obtained in this work are marked by black dot. The number is the percentage indicating the level of boot strap support, based on a neighbor-joining analysis of 1,000 resampled data sets. The scale bar represents 0.02 substitutions per nucleotide position.</p
HPLC of the EtOAc extract of <i>Micromonospora</i> sp. strain A5-1 fermentation broth (UV spectra of selected peaks at t<sub>R</sub> 5.22 min show similar absorption as jadomycins).
<p>HPLC of the EtOAc extract of <i>Micromonospora</i> sp. strain A5-1 fermentation broth (UV spectra of selected peaks at t<sub>R</sub> 5.22 min show similar absorption as jadomycins).</p
A zoom-in view of the vessel remodelling in the tumour region.
<p>Microvessel radius (R) is represented by different colour (unit:μm). Pink dots represent the approximate boundary of GBM invasion. White arrows indicate the vessel dilation (A, B, C). White arrowheads indicate the neo-vasculatures. D. 3D view of a cluster of capillaries before (top) and undergo (bottom) remodelling. Note the dilated vessels indicated by arrows.</p
Neighbor-joining tree constructed using aligned KS<sub>α</sub> domain amino acid sequence (203 amino acid positions) from type II PKSs.
<p>The sequences obtained in this work are marked by black dot. Next to the taxon name, GenBank accession number of KS<sub>α</sub> domain amino acid sequence or/and the identified compounds are indicated. Bootstrap values calculated from 1,000 resamplings using neighborjoining are shown at the respective nodes when the calculated values were 50% or greater. The scale bar represents 0.05 substitutions per amino acid position.</p
The influence of flow-dependent oxygen transport on the model.
<p>The proportion of oxygen supply to the tumour tissue by every Strahler order in the basic case and the test case (C_c) at T = 200.</p
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