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Numerical Strategies for Mixed-Integer Optimization of Power-Split and Gear Selection in Hybrid Electric Vehicles
Get PDFThis paper presents numerical strategies for a computationally efficient energy management system that co-optimizes the power split and gear selection of a hybrid electric vehicle (HEV). We formulate a mixed-integer optimal control problem (MIOCP) that is transcribed using multiple-shooting into a mixed-integer nonlinear program (MINLP) and then solved by nonlinear model predictive control. We present two different numerical strategies, a Selective Relaxation Approach (SRA), which decomposes the MINLP into several subproblems, and a Round-n-Search Approach (RSA), which is an enhancement of the known ‘relax-n-round’ strategy. Subsequently, the resulting algorithmic performance and optimality of the solution of the proposed strategies are analyzed against two benchmark strategies; one using rule-based gear selection, which is typically used in production vehicles, and the other using dynamic programming (DP), which provides a global optimum of a quantized version of the MINLP. The results show that both SRA and RSA enable about\ua03.6%\ua0cost reduction compared to the rule-based strategy, while still being within\ua01%\ua0of the DP solution. Moreover, for the case studied RSA takes about\ua035%\ua0less mean computation time compared to SRA, while both SRA and RSA being about\ua099\ua0times faster than DP. Furthermore, both SRA and RSA were able to overcome the infeasibilities encountered by a typical rounding strategy under different drive cycles. The results show the computational benefit of the proposed strategies, as well as the energy saving possibility of co-optimization strategies in which actuator dynamics are explicitly included
Scenario Tracking for Airborne Bistatic Radar Systems
No full textAn effective space-time adaptive processing implementation provides an accurate estimate of the corresponding space-time covariance matrix of the distribution of the interference and the noise. Such an estimate is commonly calculated from secondary observations associated with the most recent coherent processing interval. In this paper, we derive the covariance matrix using a parametric model which depends on a few parameters describing the state of the radar scenario. With this formulation, it is sufficient to estimate the\ua0 scenario parameters to obtain the covariance matrix estimate. The scenario parameters represents the position and velocities of the platforms comprising the airborne bistatic configuration. Moreover, the framework of radar scenarios enables information from previously considered coherent processing intervals to contribute to the covariance matrix estimate. Consequently, as the scenario parameters denotes motion characteristics of a platform, the scenario parameters can be tracked over time by assuming a motion model. Thus, the estimator of this paper uses a combination of the likelihood density of the most recent set of radar observations, together with a dynamical model which enables the propagation of the scenario parameters dynamics through time. Hence, the density of the likelihood and the prior density from the propagation of previous scenario parameter estimates through time is combined to calculate a maximum a posteriori estimate of the scenario parameters. In numerical simulations, the maximum a posteriori estimate is compared with the corresponding scenario parameter estimate considering only a maximum likelihood estimate. The numerical simulations indicates that the maximum a posteriori estimate obtains a scenario parameter estimate which is closer to the true scenario parameters. Moreover, the maximum a posteriori estimate is more robust towards a low number of secondary data comprising the likelihood density compared to the maximum likelihood estimate
Application of Convolutional Neural Networks to Predict Magnetic Fields’ Directions in Turbulent Clouds
Get PDFWe adopt the deep learning method casi-3d (convolutional approach to structure identification-3D) to infer the orientation of magnetic fields in sub-/trans-Alfv\ue9nic turbulent clouds from molecular line emission. We carry out magnetohydrodynamic simulations with different magnetic field strengths and use these to generate synthetic observations. We apply the 3D radiation transfer code radmc-3d to model 12CO and 13CO (J = 1−0) line emission from the simulated clouds and then train a casi-3d model on these line emission data cubes to predict magnetic field morphology at the pixel level. The trained casi-3d model is able to infer magnetic field directions with a low error (≲10\ub0 for sub-Alfv\ue9nic samples and ≲30\ub0 for trans-Alfv\ue9nic samples). We further test the performance of casi-3d on a real sub-/trans- Alfv\ue9nic region in Taurus. The casi-3d prediction is consistent with the magnetic field direction inferred from Planck dust polarization measurements. We use our developed methods to produce a new magnetic field map of Taurus that has a three times higher angular resolution than the Planck map
High temperature corrosion resistance of FeCr(Ni, Al) alloys as bulk/overlay weld coatings in the presence of KCl at 600 \ub0C
Get PDFThe long-term high temperature corrosion behavior of FeCr(Ni, Al) alloys, both in bulk form and as overlay welds, was investigated in a new experimental setup, in the presence of KCl at 600 \ub0C. All the alloys experienced breakaway oxidation, with the bulk materials exhibiting better corrosion resistance than the overlay weld coatings with similar compositions. All results indicate diffusion-controlled kinetics, and the analysis revealed an improved corrosion behavior connected to an increased Cr content in the inward-growing scale
Fate of charge order in overdoped La-based cuprates
Get PDFIn high-temperature cuprate superconductors, stripe order refers broadly to a coupled spin and charge modulation with a commensuration of eight and four lattice units, respectively. How this stripe order evolves across optimal doping remains a controversial question. Here we present a systematic resonant inelastic x-ray scattering study of weak charge correlations in La2−xSrxCuO4 and La1.8−xEu0.2SrxCuO4. Ultra high energy resolution experiments demonstrate the importance of the separation of inelastic and elastic scattering processes. Long-range temperature-dependent stripe order is only found below optimal doping. At higher doping, short-range temperature-independent correlations are present up to the highest doping measured. This transformation is distinct from and preempts the pseudogap critical doping. We argue that the doping and temperature-independent short-range correlations originate from unresolved electron–phonon coupling that broadly peaks at the stripe ordering vector. In La2−xSrxCuO4, long-range static stripe order vanishes around optimal doping and we discuss both quantum critical and crossover scenarios
Vehicle cabin air quality – influence of air recirculation on energy use, particles and CO2
Get PDFIn this study simulations were performed to investigate the influence of different vehicle climate ventilation strategies, mainly the air recirculation (REC) degree, on the cabin air quality and climate system power. The focus of air quality is on the cabin particle concentrations including PM2.5 (particles of aerodynamic diameter less than 2.5 μm), UFP (ultrafine particles of aerodynamic diameter less than 100 nm), and cabin CO2 concentration. Three outside climates (cold, intermediate, and warm) and three outside particle concentrations are studied. The studied vehicle originally shows possibilities to meet WHO PM2.5 guideline of 15 μg/m3 with a new filter. The aged filter have reduced performance, especially when outside concentration is high. Increased REC shows advantages in all the three climates in reducing particles and climate power for the studied vehicle. Application of 70% REC (70% of ventilation air is recirculated air) on average lowers PM2.5 by 55% and 39% for a new and aged filter respectively. 70% REC with a new filter reduces cabin PM2.5 below guideline of 15 μg/m3 in all conditions. The reduction of UFP counts results are generally similar to that of PM2.5. Increased REC also lessens the average climate system power by up to 27 % on average. When REC is increased, the cabin CO2 concentration arise accordingly, and the magnitude is relevant to the passengers. In all studied conditions with 1 passenger, 70% REC does not increase CO2 above the common guideline of 1000 ppm. 70% REC is not recommended with more than 1 passengers in cold and intermediate climate, and 2 passengers in warm climate. Besides, to avoid the potential windscreen fog risk in cold climate, REC should be avoided when passengers are more than 3.Except for constant REC values, a sample study investigates a dynamic control of the REC. It shows the possibility of continuously optimizing REC to reduce the climate power and particles, while maintaining the CO2 concentration below 1000 ppm. In warm climate with 1 passenger boarded, the average optimized REC is 90%, which in comparison with base case lead to 44% PM2.5 reduction and 12% climate power reduction
GOALS-JWST: Mid-infrared Spectroscopy of the Nucleus of NGC 7469
Get PDFWe present mid-infrared spectroscopic observations of the nucleus of the nearby Seyfert galaxy NGC 7469 taken with the MIRI instrument on the James Webb Space Telescope (JWST) as part of Directors Discretionary Time Early Release Science program 1328. The high-resolution nuclear spectrum contains 19 emission lines covering a wide range of ionization. The high-ionization lines show broad, blueshifted emission reaching velocities up to 1700 km s−1 and FWHM ranging from ∼500 to 1100 km s−1. The width of the broad emission and the broad-to-narrow line flux ratios correlate with ionization potential. The results suggest a decelerating, stratified, AGN-driven outflow emerging from the nucleus. The estimated mass outflow rate is 1-2 orders of magnitude larger than the current black hole accretion rate needed to power the AGN. Eight pure rotational H2 emission lines are detected with intrinsic widths ranging from FWHM ∼125 to 330 km s−1. We estimate a total mass of warm H2 gas of ∼1.2
7 107 M ⊙ in the central 100 pc. The PAH features are extremely weak in the nuclear spectrum, but a 6.2 μm PAH feature with an equivalent width of ∼0.07 μm and a flux of 2.7
7 10−17 W m−2 is detected. The spectrum is steeply rising in the mid-infrared, with a silicate strength of ∼0.02, significantly smaller than seen in most PG QSOs but comparable to other Seyfert 1s. These early MIRI mid-infrared IFU data highlight the power of JWST to probe the multiphase interstellar media surrounding actively accreting supermassive black holes
A Molybdenum Disulfide Nanozyme with Charge-Enhanced Activity for Ultrasound-Mediated Cascade-Catalytic Tumor Ferroptosis
No full textThe deficient catalytic activity of nanozymes and insufficient endogenous H2O2 in the tumor microenvironment (TME) are major obstacles for nanozyme-mediated catalytic tumor therapy. Since electron transfer is the basic essence of catalysis-mediated redox reactions, we explored the contributing factors of enzymatic activity based on positive and negative charges, which are experimentally and theoretically demonstrated to enhance the peroxidase (POD)-like activity of a MoS2 nanozyme. Hence, an acidic tumor microenvironment-responsive and ultrasound-mediated cascade nanocatalyst (BTO/MoS2@CA) is presented that is made from few-layer MoS2 nanosheets grown on the surface of piezoelectric tetragonal barium titanate (T-BTO) and modified with pH-responsive cinnamaldehyde (CA). The integration of pH-responsive CA-mediated H2O2 self-supply, ultrasound-mediated charge-enhanced enzymatic activity, and glutathione (GSH) depletion enables out-of-balance redox homeostasis, leading to effective tumor ferroptosis with minimal side effects
Iron based oxygen-carrier-aided oxy-fuel combustion of coal char: Reactivity and oxygen transfer mechanism
No full textAdding an active oxygen carrier to the inert bed material may favor the oxygen distribution in fluidized bed (FB) combustors. This so-called method “Oxygen-carrier-aided combustion, OCAC” has been applied recently to air combustion in FB boilers, but could also be potentially interesting in oxy-fuel combustion. Here we analyze OCAC in oxy-fuel combustion by experimental determination of the reactivity of char from three coals (lignite, bituminous and anthracite coal) using three oxygen carriers (OC, analytical reagent Fe2O3, hematite, and steel slag). The tests were conducted in a micro thermo-gravimetric analyzer (micro-TGA) and the combustion kinetics was determined for the nine combinations of char and OC. Additional tests were conducted in a macro-TGA i.e., much sample in a big ceramic crucible, to evaluate the phase composition and crystal quality using X-ray diffraction (XRD) to the combustion residues collected at various degrees of carbon conversion (0.2, 0.5, and 0.8). The results show that the burnout temperature decreases with OCs as the combustion rate increases, while the ignition temperature hardly changes. The enhancement of the rate of char combustion by OCs is in the following order: steel slag < hematite < AR-Fe2O3. The lower the fuel rank, the stronger the effect of the oxygen carrier. The combustion kinetics of chars using OC has a higher activation energy and pre-exponential factor than pure char. The enlarged lattice constant of Fe2O3 measured by XRD during the char combustion indicates that the redox reactions of Fe2O3 accelerate the oxidization of char by enhancing the rate of oxygen transport to the carbon surface