1,544 research outputs found
Development Of An On-line Adaptive ANN-based Controller For A Direct Expansion Air Conditioning System
No full textAn on-line adaptive artificial neural network (ANN)-based controller has been developed for an experimental DX A/C system. It controls the indoor air temperature and humidity simultaneously by varying the compressor speed and supply fan speed in a space served by the experimental DX A/C system. The ANN-based direct inverse control (DIC) strategy was adopted in the development of the controller and the specialized training method was used to on-line update an ANN-based model and an inverse model used in the controller. The controllability tests including the command following test and the disturbance rejection test were carried out using the experimental DX A/C system, and the test results showed that the on-line adaptive ANN-based controller developed was able to control indoor air dry-bulb temperature and wet-bulb temperature outside the operating conditions within which the models were trained, with a high control accuracy
PGR IHC (4%Li cut-off value) and PGR Dx (5.5 cut-off value) RS risk class distribution.
No full textPGR IHC (4%Li cut-off value) and PGR Dx (5.5 cut-off value) RS risk class distribution.</p
On DX centers in A1xGa1-xAs
No full textÉ feito um resumo dos principais modelos criados para se explicar as intrigantes propriedades do centro DX e atualizar o problema. O decaimento da fotocondutividade persistente (PPC) é medido em AlxGa1-x As dopado com Si e se discute a validade dos modelos em função da cinética de captura dos elétrons pelos centros DX. Boa concordância com o modelo de Chadi e Chang é encontrada desde que se postule a existência de um nível doador mais raso. O crescimento por MBE assim como todo o processamento de amostras para os experimentos realizados é descrito sinteticamente. É discutido também o problema dos contatos a baixa temperatura e a possível influência dos centros DX nos desvios do comportamento ôhmico observados. Inclui-se também a descoberta da. fotocondutividade persistente em AlxGa1-xAs dopado com Pb, que também é relacionado à existência dos centros DX.A short discussion about the main models created to explain the striking properties of the DX center is done in order to bring the problem up-to-date. The decay of persistent photoconductivity is measured and it is analyzed as a function of the kinetics of electron trapping by DX centers in Si-doped AlxGa1-xAs, according to these models. Good agreement with Chadi and Chang\'s model is found as long as we postulate the existence of a shallower donor. The M.B.E. growth as well as the whole sample processing is shortly described. It in siso diacussed the problem of low temperature contacts and the possible influence of DX centers in the deviation from ohmic behavior. Persistent Photoconductivity has been found in Pb-doped AlxGa1-xAs and it is also related to the DX center existence
Field Test of DX Pile Group
No full textDX pile is a newly developed variable cross-section pile. Compared to conventional straight pile, it has distinct advantages on bearing capacity and settlement control. However, the bearing mechanism and characteristics of settlement, especially on group DX piles, are not clear. This paper illustrated and analyzed the bearing capacity and settlement characteristics of single DX pile and group DX piles according to the test results of in-situ model test. Special attention was paid on single and group DX pile comparison under same circumstances, at the mean while, compared the single DX pile and conventional pile with the same pile length and diameter, and with the same bearing capacity. The conclusions from the test results provided theoretical references for the design of the DX piles in engineering practices.</jats:p
Entropy splitting for high-order numerical simulation of compressible turbulence
No full textA stable high-order numerical scheme for direct numerical simulation (DNS) of shock-free compressible turbulence is presented. The method is applicable to general geometries. It contains no upwinding, artificial dissipation, or filtering. Instead the method relies on the stabilizing mechanisms of an appropriate conditioning of the governing equations and the use of compatible spatial difference operators for the interior points (interior scheme) as well as the boundary points (boundary scheme). An entropy-splitting approach splits the inviscid flux derivatives into conservative and nonconservative portions. The spatial difference operators satisfy a summation-by-parts condition, leading to a stable scheme (combined interior and boundary schemes) for the initial boundary value problem using a generalized energy estimate. A Laplacian formulation of the viscous and heat conduction terms on the right hand side of the Navier–Stokes equations is used to ensure that any tendency to odd–even decoupling associated with central schemes can be countered by the fluid viscosity. The resulting methods are able to minimize the spurious high-frequency oscillations associated with pure central schemes, especially for long time integration applications such as DNS. For validation purposes, the methods are tested in a DNS of compressible turbulent plane channel flow at low values of friction Mach number, where reference turbulence data bases exist. It is demonstrated that the methods are robust in terms of grid resolution, and in good agreement with published channel data. Accurate turbulence statistics can be obtained with moderate grid sizes. Stability limits on the range of the splitting parameter are determined from numerical tests
Critical assessment of existing slope stability formulae and application to slope stabilisation
No full textIn this research, extensive use has been made of limit equilibrium methods of analysis
for studying the stability of slopes. For the determination of the factor of safety (FOS)
of slopes, the usual two-step process has been adopted; (a) assuming a slip surface for
the soil mass, and (b) using the appropriate limit equilibrium equation(s). Eight wellknown
limit equilibrium methods have been programmed to calculate different FOS
values. The comparative performance of the various analyses has been carried out
successfully using case studies. The innovative use of Gauss quadrature to calculate
the FOS values has been shown to reducet he iterative sequencesd ramatically with no
loss of accuracy.
A visco-plastic flow model has been proposed to estimate lateral forces on piles used
for slope stabilisation. The present research data occupies an "in-between" position to
the previously reported values, with the variation trend being confirmed satisfactorily
in all cases.
Slope stabilisation due to the presence of a row of piles has been investigated using
two distinct lateral load estimations. These include theories of plastic deformation and
the proposed visco-plastic flow which are modelled and implemented in a computer
program. Eight well-known methods of slope stability analyses have been adopted and
computer coded to re-calculate FOS values for a slope reinforced by a row of piles. A
Finite Element computer program has been developed to evaluate the displacement,
bending moment and shear force along the pile axis. The pile is analysed at two levels
above and below the slip failure surface
A Data-driven dE/dx Simulation with Normalizing Flow
No full textIn high-energy physics, precise measurements rely on highly reliable detector
simulations. Traditionally, these simulations involve incorporating experiment
data to model detector responses and fine-tuning them. However, due to the
complexity of the experiment data, tuning the simulation can be challenging.
One crucial aspect for charged particle identification is the measurement of
energy deposition per unit length (referred to as dE/dx). This paper proposes a
data-driven dE/dx simulation method using the Normalizing Flow technique, which
can learn the dE/dx distribution directly from experiment data. By employing
this method, not only can the need for manual tuning of the dE/dx simulation be
eliminated, but also high-precision simulation can be achieved
Quantitative analysis of chloroplast protein targeting
No full textThis thesis presents the first use of the Partition of Unity Method in quantifying
the spatio-temporal dynamics of a fluorescent protein targeted to
the chloroplast twin-arginine translocation pathway.
The fluorescence loss in photobleaching technique is applied in a modified
fashion to the measurement of substrate mobilities in the chloroplast
stroma. Our in vivo results address the two suggested protein targeting
mechanisms of membrane-binding before lateral movement to the translocon
and direct binding to the translocon.
A high performance computing C/C++ implementation of the Partition
of Unity Method is used to perform simulations of fluoresence loss
in photobleaching and allow a compelling comparison to photobleaching
data series. The implementation is both mesh-free and particle-less
Direct numerical simulation of hypersonic boundary layer transition over a blunt cone with a small angle of attack
No full textThe direct numerical simulation of boundary layer transition over a 5° half-cone-angle blunt cone is performed. The free-stream Mach number is 6 and the angle of attack is 1°. Random wall blow-and-suction perturbations are used to trigger the transition. Different from the authors’ previous work [Li et al., AIAA J. 46, 2899(2008)], the whole boundary layer flow over the cone is simulated (while in the author’s previous work, only two 45° regions around the leeward and the windward sections are simulated). The transition location on the cone surface is determined through the rapid increase in skin fraction coefficient (Cf). The transition line on the cone surface shows a nonmonotonic curve and the transition is delayed in the range of 0° ≤ θ ≤ 30° (θ = 0° is the leeward section). The mechanism of the delayed transition is studied by using joint frequency spectrum analysis and linear stability theory (LST). It is shown that the growth rates of unstable waves of the second mode are suppressed in the range of 20° ≤ θ ≤ 30°, which leads to the delayed transition location. Very low frequency waves VLFWs� are found in the time series recorded just before the transition location, and the periodic times of VLFWs are about one order larger than those of ordinary Mack second mode waves. Band-pass filter is used to analyze the low frequency waves, and they are deemed as the effect of large scale nonlinear perturbations triggered by LST waves when they are strong enough.The direct numerical simulation of boundary layer transition over a 5° half-cone-angle blunt cone is performed. The free-stream Mach number is 6 and the angle of attack is 1°. Random wall blow-and-suction perturbations are used to trigger the transition. Different from the authors’ previous work [ Li et al., AIAA J. 46, 2899 (2008) ], the whole boundary layer flow over the cone is simulated (while in the author’s previous work, only two 45° regions around the leeward and the windward sections are simulated). The transition location on the cone surface is determined through the rapid increase in skin fraction coefficient (Cf). The transition line on the cone surface shows a nonmonotonic curve and the transition is delayed in the range of 20° ≤ θ ≤ 30° (θ = 0° is the leeward section). The mechanism of the delayed transition is studied by using joint frequency spectrum analysis and linear stability theory (LST). It is shown that the growth rates of unstable waves of the second mode are suppressed in the range of 20° ≤ θ ≤ 30°, which leads to the delayed transition location. Very low frequency waves (VLFWs) are found in the time series recorded just before the transition location, and the periodic times of VLFWs are about one order larger than those of ordinary Mack second mode waves. Band-pass filter is used to analyze the low frequency waves, and they are deemed as the effect of large scale nonlinear perturbations triggered by LST waves when they are strong enough
Functional characterization of orbicularis oculi and extraocular muscles
No full textThe orbicularis oculi are the sphincter muscles of the eyelids and are involved in modulating facial expression. They differ from both limb and extraocular muscles (EOMs) in their histology and biochemistry. Weakness of the orbicularis oculi muscles is a feature of neuromuscular disorders affecting the neuromuscular junction, and weakness of facial muscles and ptosis have also been described in patients with mutations in the ryanodine receptor gene. Here, we investigate human orbicularis oculi muscles and find that they are functionally more similar to quadriceps than to EOMs in terms of excitation-contraction coupling components. In particular, they do not express the cardiac isoform of the dihydropyridine receptor, which we find to be highly expressed in EOMs where it is likely responsible for the large depolarization-induced calcium influx. We further show that human orbicularis oculi and EOMs express high levels of utrophin and low levels of dystrophin, whereas quadriceps express dystrophin and low levels of utrophin. The results of this study highlight the notion that myotubes obtained by explanting satellite cells from different muscles are not functionally identical and retain the physiological characteristics of their muscle of origin. Furthermore, our results indicate that sparing of facial and EOMs in patients with Duchenne muscular dystrophy is the result of the higher levels of utrophin expression
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