This paper presents a 2MHz 4V-to-48V VIN, GaN-based buck-boost converter with optimized buck-boost mode, enhanced safe protection, and fast transient response for automotive Advanced Driving Assistant Systems (ADAS). A flying-capacitor-based floating-ground topology is proposed first time to solve the issue associated with extremely short on time, improve power efficiency in the buck-boost region and provide real-time detection and management of the inductor peak current. This floating-ground technique helps alleviate the problem of efficiency drop in the four-switch buck-boost topology and ensures converter/load safety. An indirect current sensor is also proposed, which allows for sensing the inductor current change in the buck-boost mode without using any bulky sensing resistors and achieves $k$ fast transient response with 100mv-undershoot/80mV-overshoot for 1A load current change. This converter achieves a maximum efficiency of 92% which is comparable to the state-of-the-art buck-boost schemes
The BESIII collaboration has recently reported the first time measurement of the decay asymmetry $\alpha(\Lambda_c^+ \to \Xi^0 K^+) = 0.01 \pm 0.16(stat.) \pm 0.03(syst.)$ and also a sizable phase shift of $\delta_P-\delta_S = -1.55 \pm 0.25$ or $1.59\pm 0.25$ between S- and P-wave amplitudes. This implies significant strong phase shifts in the decay amplitudes. The strong phases indicate the existence of rescattering or loop effects, which are challenging to calculate due to non-perturbative effects. By employing the flavor $SU(3)_F$ symmetry and applying the K\"orner-Pati-Woo theorem to reduce the number of parameters, we find that the current data already allow us to obtain, for the first time, model-independent decay amplitudes and their strong phases. The establishment of the existence of sizable strong phases opens a window for future investigations into CP violation. In our fit, a notable discrepancy emerges in the branching ratio of $\Xi_c^0 \to \Xi^- \pi^+$. The direct relationship between $\Gamma (\Lambda_c^+ \to \Lambda e^+\nu_e)$ and $\Gamma (\Xi_c^0 \to \Xi^- e^+\nu_e)$, along with newly discovered $SU(3)_F$ relations, collectively suggests an underestimation of $\mathcal{B}(\Xi_c^0 \to \Xi^- \pi^+)$ in experimental findings.
Abstract We explore the semileptonic and nonleptonic decays of doubly heavy baryons $$(\Omega _{cc}^{(*)+},\Omega _{bb}^{(*)0},\Omega _{bc}^{(*)-},\Omega _{bc}^{\prime 0})$$ (Ωcc(∗)+,Ωbb(∗)0,Ωbc(∗)-,Ωbc′0) induced by the $$s\rightarrow u$$ s→u transition. Hadronic form factors are parametrized by transition matrix elements and are calculated in the light front quark model. With the form factors, we make use of helicity amplitudes and analyze semileptonic and nonleptonic decay modes of doubly heavy baryons. Benchmark results for partial decay widths, branching fractions, forward–backward asymmetries and other phenomenological observables are derived. We find that typical branching fractions for semileptonic decays into $$\ell \bar{\nu }$$ ℓν¯ are at the order $$10^{-7}-10^{-8}$$ 10-7-10-8 and the ones for nonleptonic decays are at the order $$10^{-5}$$ 10-5 , which are likely detectable such as in LHCb experiment. With the potential data accumulated in future, our results may help to shape our understanding of the decay mechanism in the presence of two heavy quarks.
Policy-Space Response Oracles (PSRO) as a general algorithmic framework has achieved state-of-the-art performance in learning equilibrium policies of two-player zero-sum games. However, the hand-crafted hyperparameter value selection in most of the existing works requires extensive domain knowledge, forming the main barrier to applying PSRO to different games. In this work, we make the first attempt to investigate the possibility of self-adaptively determining the optimal hyperparameter values in the PSRO framework. Our contributions are three-fold: (1) Using several hyperparameters, we propose a parametric PSRO that unifies the gradient descent ascent (GDA) and different PSRO variants. (2) We propose the self-adaptive PSRO (SPSRO) by casting the hyperparameter value selection of the parametric PSRO as a hyperparameter optimization (HPO) problem where our objective is to learn an HPO policy that can self-adaptively determine the optimal hyperparameter values during the running of the parametric PSRO. (3) To overcome the poor performance of online HPO methods, we propose a novel offline HPO approach to optimize the HPO policy based on the Transformer architecture. Experiments on various two-player zero-sum games demonstrate the superiority of SPSRO over different baselines.
With the decrease of pressure during the production process of low-permeability condensate gas reservoirs, different degrees of retrograde condensate pollution appear in the area near the wellbore, resulting in a rapid decrease in the productivity of gas wells. Due to the poor physical properties of low-permeability condensate gas reservoirs, conventional single measures such as circulating gas injection and huff and puff gas injection cannot effectively relieve the condensate pollution in the near-wellbore area. For this reason, this paper explores the WH1 gas well in the W low-permeability condensate gas reservoir and conducts research on the retrograde of reverse condensate pollution in a single well. First, 12 groups of inside evaluation experiments for the decontamination of retrograde condensates are carried out using the core of the condensate gas reservoir W and 6 different agents. According to the experimental results, methanol + CO<sub>2</sub> huff and puff are selected as the optimal agent for decontamination by retrograde condensate. Secondly, by analyzing the physical properties of the W low-permeability condensate gas reservoir and the production performance parameters of the WH1 well, a three-dimensional numerical simulation model of the single well of the WH1 gas well is established, and the PVT phase state matching and production performance history matching are carried out for the model. Finally, the single-well numerical simulation model of the WH1 gas well, combined with the experimental results, is used to simulate the obturation effect of CO<sub>2</sub> injection after methanol injection. Among them, the change of reservoir physical properties in the near-wellbore area after methanol injection is simulated by the method of local grid refinement. The research shows that after the simulated well is injected with 20m3 methanol when the CO<sub>2</sub> injection volume in a single cycle is 120 × 10<sup>4</sup> m<sup>3</sup>, the injection rate is 4 × 10<sup>4</sup> m<sup>3</sup>/d, and the well soaking time is 11 days. The reservoir pollution removal effect is the best in the area near the wellbore. From the change of liquid saturation in the near-wellbore area, it can be concluded that the damage of retrograde condensate is relieved by about 87.1%. This study has formed a set of efficient technical means for removing reverse condensate pollution in W low-permeability condensate gas reservoirs. It provides some technical guidance for the formulation of a rational development mode of condensate gas reservoirs.
To study the combined model of radiomic features and clinical features based on enhanced CT images for noninvasive evaluation of microsatellite instability (MSI) status in colorectal liver metastasis (CRLM) before surgery.The study included 104 patients retrospectively and collected CT images of patients. We adjusted the region of interest to increase the number of MSI-H images. Radiomic features were extracted from these CT images. The logistic models of simple clinical features, simple radiomic features, and radiomic features with clinical features were constructed from the original image data and the expanded data, respectively. The six models were evaluated in the validation set. A nomogram was made to conveniently show the probability of the patient having a high MSI (MSI-H).The model including radiomic features and clinical features in the expanded data worked best in the validation group.A logistic regression prediction model based on enhanced CT images combining clinical features and radiomic features after increasing the number of MSI-H images can effectively identify patients with CRLM with MSI-H and low-frequency microsatellite instability (MSI-L), and provide effective guidance for clinical immunotherapy of CRLM patients with unknown MSI status.
In this study, we investigate the nonleptonic decays of the charmed-baryon Xi^ {0} _ c induced by the c -> u(d\bar{d})/(s\bar{s}) transition. Utilizing the factorization assumption, we decompose the decay amplitudes in terms of transition form factors which are then calculated within the light-front quark model. We employ helicity amplitudes to analyze the nonleptonic decay modes of the charmed-baryon Xi^ {0} _c and derive benchmark results for decay widths and branching fractions. Our calculations suggest that the branching fractions for some of these rare nonleptonic decays are at the order of 10^ {-4} - 10^ {-3}, which are likely to be detectable at experiments such as LHCb or BESIII. The potential data accumulated in the future may help to further our understanding of the decay mechanism in the presence of charm quarks.
A large amount of data on hadronic two-body weak decays of antitriplet charmed baryons ${T}_{c\overline{3}}$ to an octet baryon ${T}_{8}$ and an octet or singlet pseudoscalar meson $P$, ${T}_{c\overline{3}}\ensuremath{\rightarrow}{T}_{8}P$, have been measured. The SU(3) flavor symmetry has been applied to study these decays to obtain insights about weak interactions for charm physics. However not all such decays needed to determine the SU(3) irreducible amplitudes have been measured forbidding a complete global analysis. Previously, it was shown that data from measured decays can be used to do a global fit to determine all except one parity-violating and one parity-conserving amplitudes of the relevant SU(3) irreducible amplitudes causing 8 hadronic two body weak decay channels involving ${\mathrm{\ensuremath{\Xi}}}_{c}^{0}$ to $\ensuremath{\eta}$ or ${\ensuremath{\eta}}^{\ensuremath{'}}$ transitions undetermined. It is important to obtain information about these decays in order to guide experimental searches. In this work using newly measured decay modes by BESIII and Belle in 2022, we carry out a global analysis and parametrize the unknown amplitudes to provide the ranges for the branching ratios of the eight undetermined decays. Our results indicate that the SU(3) flavor symmetry can explain the measured data exceptionally well, with a remarkable minimal ${\ensuremath{\chi}}^{2}/\mathrm{d}.\mathrm{o}.\mathrm{f}.$ of 1.21 and predict 80 observables in 45 decays for future experimental data to test. We then vary the unknown SU(3) amplitudes to obtain the allowed range of branching ratios for the eight undetermined decays. We find that some of them are within reach of near future experimental capabilities. We urge our experimental colleagues to carry out related searches.
Plasma density is an important factor in determining wave-particle interactions in the magnetosphere. We develop a machine-learning-based electron density (MLED) model in the inner magnetosphere using electron density data from Van Allen Probes between September 25, 2012 and August 30, 2019. This MLED model is a physics-based nonlinear network that employs fundamental physical principles to describe variations of electron density. It predicts the plasmapause location under different geomagnetic conditions, and models separately the electron densities of the plasmasphere and of the trough. We train the model using gradient descent and backpropagation algorithms, which are widely used to deal effectively with nonlinear relationships among physical quantities in space plasma environments. The model gives explicit expressions with few parameters and describes the associations of electron density with geomagnetic activity, solar cycle, and seasonal effects. Under various geomagnetic conditions, the electron densities calculated by this model agree well with empirical observations and provide a good description of plasmapause movement. This MLED model, which can be easily incorporated into previously developed radiation belt models, promises to be very helpful in modeling and improving forecasting of radiation belt electron dynamics.
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