University of Electro-Communications

About: University of Electro-Communications is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Laser & Robot. The organization has 8041 authors who have published 16950 publications receiving 235832 citations. The organization is also known as: UEC & Denki-Tsūshin Daigaku.

Ultrafast Electron Injection from Photoexcited Perovskite CsPbI3 QDs into TiO2 Nanoparticles with Injection Efficiency near 99

Abstract: Photoexcited electron injection dynamics from CsPbI3 quantum dots (QDs) to wide gap metal oxides are studied by transient absorption spectroscopy. Experimental results show under a low excitation intensity that ∼99% of the photoexcited electrons in CsPbI3 QDs can be injected into TiO2 with a size-dependent rate ranging from 1.30 × 1010 to 2.10 × 1010 s–1, which is also ∼2.5 times faster than that in the case of ZnO. A demonstration QD-sensitized solar cell based on a CsPbI3/TiO2 electrode is fabricated that delivers a power conversion efficiency of 5%.

Calculation of Demagnetizing Field Distribution Based on Fast Fourier Transform of Convolution

Abstract: It is confirmed that the calculation of the demagnetizing field in micromagnetic simulations can be accelerated significantly by using the discrete convolution theorem and the fast Fourier transform (FFT). When the magnetization distribution is periodic, application of the theorem to the demagnetizing field calculation is straightforward. Unlike the previously reported FFT method which is based on the continuous Fourier transform of the demagnetizing field, the method can also be used in the case of non-periodic magnetization structures. It is also confirmed that the result obtained using the new FFT method coincides with that of the conventional direct method, as expected. The principle of calculation and the results of one- and two-dimensional calculations which show the validity and effectiveness of the developed method are presented.

Facial-component-based bag of words and PHOG descriptor for facial expression recognition

Abstract: A novel framework of facial appearance and shape information extraction for facial expression recognition is proposed. For appearance extraction, a facial-component-based bag of words method is presented. We segment face images into 4 component regions, and sub-divide them into 4×4 sub-regions. Dense SIFT (Scale-Invariant Feature Transform) features are calculated over the sub-regions and vector quantized into 4×4 sets of codeword distributions. For shape extraction, PHOG (Pyramid Histogram of Orientated Gradient) descriptors are computed on the 4 facial component regions to obtain the spatial distribution of edges. Our framework provides holistic characteristics for the local texture and shape features by enhancing the structure-based spatial information, and makes the local descriptors be possible to be used in facial expression recognition for the first time. The recognition rate achieved by the fusion of appearance and shape features at decision level using the Cohn-Kanade database is 96.33%, which outperforms the state of the arts.

Completely Independent Spanning Trees in Maximal Planar Graphs

Abstract: Let G be a graph. Let T1, T2, . . . , Tk be spanning trees in G. If for any two vertices u, v in G, the paths from u to v in T1, T2, . . . , Tk are pairwise openly disjoint, then we say that T1, T2, . . . , Tk are completely independent spanning trees in G. In this paper, we show that there are two completely independent spanning trees in any 4-connected maximal planar graph. Our proof induces a linear-time algorithm for finding such trees. Besides, we show that given a graph G, the problem of deciding whether there exist two completely independent spanning trees in G is NP-complete.

A linear-size quantum circuit for addition with no ancillary qubits

Abstract: We construct a quantum circuit for addition of two n-bit binary numbers that uses no ancillary qubits. The circuit is based on the ripple-carry approach. The depth and size of the circuit are O(n). This is an affirmative answer to the question of Kutin [1] as to whether a linear-depth quantum circuit for addition can be constructed without ancillary qubits using the ripple-carry approach. We also construct quantum circuits for addition modulo 2n, subtraction, and comparison that use no ancillary qubits by modifying the circuit for addition.