435 research outputs found
Боротьба української громадськості за розв’язання мовної проблеми в народних школах (друга половина ХІХ – початок ХХ ст.)
(uk) У статті висвітлено маловідомі сторінки історії боротьби української громадськості за розв’язання мовної проблеми в народних школах у другій половині ХІХ – на початку ХХ ст. Важливу роль у цих змаганнях відіграли педагогічні з’їзди та з’їзди отців-законовчителів.(en) The article covers the little-known pages of the history of the struggle of the Ukrainian Community for the decision of the language problem in national schools in the second half of the 19th century and at the beginning of the 20th century. Pedagogical congresses played an important part in those contests
Adaptive Group-based Signal Control by Reinforcement Learning
AbstractGroup-based signal control is one of the most prevalent control schemes in the European countries. The major advantage of group-based control is its capability in providing flexible phase structures. The current group-based control systems are usually implemented with rather simple timing logics, e.g. vehicle actuated logic. However, such a timing logic is not sufficient to respond to the traffic environment whose inputs, i.e. traffic demands, dynamically change over time. Therefore, the primary objective of this paper is to formulate the existing group-based signal controller as a multi-agent system. The proposed signal control system is capable of making intelligent timing decisions by utilizing machine learning techniques. In this regard, reinforcement learning is a potential solution because of its self-learning properties in a dynamic environment. This paper, thus, proposes an adaptive signal control system, enabled by a reinforcement learning algorithm, in the context of group-based phasing technique. Two different learning algorithms, Q-learning and SARSA, have been investigated and tested on a four-legged intersection. The experiments are carried out by means of an open-source traffic simulation tool, SUMO. Performances on traffic mobility of the adaptive group- based signal control systems are compared against those of a well-established group-based fixed time control system. In the testbed experiments, simulation results reveal that the learning-based adaptive signal controller outperforms group-based fixed time signal controller with regards to the improvements in traffic mobility efficiency. In addition, SARSA learning is a more suitable implementation for the proposed adaptive group-based signal control system compared to the Q-learning approach
Practical Modeling and Comprehensive System Identification of a BLDC Motor
The aim of this paper is to outline all the steps in a rigorous and simple procedure for system identification of BLDC motor. A practical mathematical model for identification is derived. Frequency domain identification techniques and time domain estimation method are combined to obtain the unknown parameters. The methods in time domain are founded on the least squares approximation method and a disturbance observer. Only the availability of experimental data for rotor speed and armature current are required for identification. The proposed identification method is systematically investigated, and the final identified model is validated by experimental results performed on a typical BLDC motor in UAV
Cardiac Specific Overexpression of Mitochondrial Omi/HtrA2 Induces Myocardial Apoptosis and Cardiac Dysfunction.
Myocardial apoptosis is a significant problem underlying ischemic heart disease. We previously reported significantly elevated expression of cytoplasmic Omi/HtrA2, triggers cardiomyocytes apoptosis. However, whether increased Omi/HtrA2 within mitochondria itself influences myocardial survival in vivo is unknown. We aim to observe the effects of mitochondria-specific, not cytoplasmic, Omi/HtrA2 on myocardial apoptosis and cardiac function. Transgenic mice overexpressing cardiac-specific mitochondrial Omi/HtrA2 were generated and they had increased myocardial apoptosis, decreased systolic and diastolic function, and decreased left ventricular remodeling. Transiently or stably overexpression of mitochondria Omi/HtrA2 in H9C2 cells enhance apoptosis as evidenced by elevated caspase-3, -9 activity and TUNEL staining, which was completely blocked by Ucf-101, a specific Omi/HtrA2 inhibitor. Mechanistic studies revealed mitochondrial Omi/HtrA2 overexpression degraded the mitochondrial anti-apoptotic protein HAX-1, an effect attenuated by Ucf-101. Additionally, transfected cells overexpressing mitochondrial Omi/HtrA2 were more sensitive to hypoxia and reoxygenation (H/R) induced apoptosis. Cyclosporine A (CsA), a mitochondrial permeability transition inhibitor, blocked translocation of Omi/HtrA2 from mitochondrial to cytoplasm, and protected transfected cells incompletely against H/R-induced caspase-3 activation. We report in vitro and in vivo overexpression of mitochondrial Omi/HtrA2 induces cardiac apoptosis and dysfunction. Thus, strategies to directly inhibit Omi/HtrA2 or its cytosolic translocation from mitochondria may protect against heart injury
A dynamic multi-objective evolutionary algorithm based on decision variable classification
The file attached to this record is the author's final peer reviewed version.In recent years, dynamic multi-objective optimization problems (DMOPs) have drawn increasing interest. Many dynamic multi-objective evolutionary algorithms (DMOEAs) have been put forward to solve DMOPs mainly by incorporating diversity introduction or prediction approaches with conventional multi-objective evolutionary algorithms. Maintaining good balance of population diversity and convergence is critical to the performance of DMOEAs. To address the above issue, a dynamic multi-objective evolutionary algorithm based on decision variable classification (DMOEA-DVC) is proposed in this study. DMOEA-DVC divides the decision variables into two and three different groups in static optimization and change response stages, respectively. In static optimization, two different crossover operators are used for the two decision variable groups to accelerate the convergence while maintaining good diversity. In change response, DMOEA-DVC reinitializes the three decision variable groups by maintenance, prediction, and diversity introduction strategies, respectively. DMOEA-DVC is compared with the other six state-of-the-art DMOEAs on 33 benchmark DMOPs. Experimental results demonstrate that the overall performance of the DMOEA-DVC is superior or comparable to that of the compared algorithms
MOEA/D with Adaptive Weight Adjustment
Recently, MOEA/D (multi-objective evolutionary algorithm based on decomposition) has achieved great success in the field of evolutionary multi-objective optimization and has attracted a lot of attention. It decomposes a multi-objective optimization problem (MOP) into a set of scalar subproblems using uniformly distributed aggregation weight vectors and provides an excellent general algorithmic framework of evolutionary multi-objective optimization. Generally, the uniformity of weight vectors in MOEA/D can ensure the diversity of the Pareto optimal solutions, however, it cannot work as well when the target MOP has a complex Pareto front (PF; i.e., discontinuous PF or PF with sharp peak or low tail). To remedy this, we propose an improved MOEA/D with adaptive weight vector adjustment (MOEA/D-AWA). According to the analysis of the geometric relationship between the weight vectors and the optimal solutions under the Chebyshev decomposition scheme, a new weight vector initialization method and an adaptive weight vector adjustment strategy are introduced in MOEA/D-AWA. The weights are adjusted periodically so that the weights of subproblems can be redistributed adaptively to obtain better uniformity of solutions. Meanwhile, computing efforts devoted to subproblems with duplicate optimal solution can be saved. Moreover, an external elite population is introduced to help adding new subproblems into real sparse regions rather than pseudo sparse regions of the complex PF, that is, discontinuous regions of the PF. MOEA/D-AWA has been compared with four state of the art MOEAs, namely the original MOEA/D, Adaptive-MOEA/D, [Formula: see text]-MOEA/D, and NSGA-II on 10 widely used test problems, two newly constructed complex problems, and two many-objective problems. Experimental results indicate that MOEA/D-AWA outperforms the benchmark algorithms in terms of the IGD metric, particularly when the PF of the MOP is complex.</jats:p
Trainable Projected Gradient Method for Robust Fine-tuning
Recent studies on transfer learning have shown that selectively fine-tuning a
subset of layers or customizing different learning rates for each layer can
greatly improve robustness to out-of-distribution (OOD) data and retain
generalization capability in the pre-trained models. However, most of these
methods employ manually crafted heuristics or expensive hyper-parameter
searches, which prevent them from scaling up to large datasets and neural
networks. To solve this problem, we propose Trainable Projected Gradient Method
(TPGM) to automatically learn the constraint imposed for each layer for a
fine-grained fine-tuning regularization. This is motivated by formulating
fine-tuning as a bi-level constrained optimization problem. Specifically, TPGM
maintains a set of projection radii, i.e., distance constraints between the
fine-tuned model and the pre-trained model, for each layer, and enforces them
through weight projections. To learn the constraints, we propose a bi-level
optimization to automatically learn the best set of projection radii in an
end-to-end manner. Theoretically, we show that the bi-level optimization
formulation could explain the regularization capability of TPGM. Empirically,
with little hyper-parameter search cost, TPGM outperforms existing fine-tuning
methods in OOD performance while matching the best in-distribution (ID)
performance. For example, when fine-tuned on DomainNet-Real and ImageNet,
compared to vanilla fine-tuning, TPGM shows and relative OOD
improvement respectively on their sketch counterparts. Code is available at
\url{https://github.com/PotatoTian/TPGM}.Comment: Accepted to CVPR202
Single pair of charge-two high-fold fermions with type-II van Hove singularities on the surface of ultralight chiral crystals
The realization of single-pair chiral fermions in Weyl systems remains
challenging in topology physics, especially for the systems with higher chiral
charges . In this work, based on the symmetry analysis, low-energy effective
model, and first-principles calculations, we identify the single-pair high-fold
fermions in chiral cubic lattices. We first derive the minimal lattice model
that exhibits a single pair of Weyl points with the opposite chiral charges of
= . Furthermore, we show the ultralight chiral crystal
P432-type LiC and its mirror enantiomer as high-quality candidate
materials, which exhibit large energy windows to surmount the interruption of
irrelevant bands. Since two enantiomers are connected by the mirror symmetry,
we observe the opposite chiral charges and the reversal of the Fermi arc
velocities, showing the correspondence of chirality in the momentum space and
the real space. In addition, we also reveal type-II van Hove singularities on
the helicoid surfaces, which may induce chirality-locked charge density waves
on the crystal surface. Our work not only provides a promising platform for
controlling the sign of topological charge through the structural chirality but
also facilitates the exploration of electronic correlations on the surface of
ultralight chiral crystals.Comment: 8 pages, 5 figure
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