A words-of-interest model of sketch representation for image retrieval

In this paper we propose a method for sketch-based image retrieval. Sketch is a magical medium which is capable of conveying semantic messages for user. It’s in accordance with user’s cognitive psychology to retrieve images with sketch. In order to narrow down the semantic gap between the user and the images in database, we preprocess all the images into sketches by the coherent line drawing algorithm. During the process of sketches extraction, saliency maps are used to filter out the redundant background information, while preserve the important semantic information. We use a variant of Words-of-Interest model to retrieve relevant images for the user according to the query. Words-of-Interest (WoI) model is based on Bag-ofvisual Words (BoW) model, which has been proven successfully for information retrieval. Bag-of-Words ignores the spatial relationships among visual words, which are important for sketch representation. Our method takes advantage of the spatial information of the query to select words of interest. Experimental results demonstrate that our sketch-based retrieval method achieves a good tradeoff between retrieval accuracy and semantic representation of users’ query

N=(0, 2) Deformation of (2, 2) Sigma Models: Geometric Structure, Holomorphic Anomaly and Exact Beta Functions

We study N=(0,2) deformed (2,2) two-dimensional sigma models. Such heterotic models were discovered previously on the world sheet of non-Abelian strings supported by certain four-dimensional N=1 theories. We study geometric aspects and holomorphic properties of these models, and derive a number of exact expressions for the beta functions in terms of the anomalous dimensions analogous to the NSVZ beta function in four-dimensional Yang-Mills. Instanton calculus provides a straightforward method for the derivation. The anomalous dimensions are calculated up to two loops implying that one of the beta functions is explicitly known up to three loops. The fixed point in the ratio of the couplings found previously at one loop is not shifted at two loops. We also consider the N=(0,2) supercurrent supermultiplet (the so-called hypercurrent) and its anomalies, as well as the "Konishi anomaly." This gives us another method for finding exact $\beta$ functions. We prove that despite the chiral nature of the models under consideration quantum loops preserve isometries of the target space.Comment: 38 pages, 6 figures, minor changes in the text and references, the journal versio

Study on OPAL-RT Simulation System Hardware in Loop and Simulation on Microgrid Black Start

In power grid simulation able to provide real time simulation give us an advantage to see how to power gird work in real time and let the electrical power grid operator to make adjustment in a humane time scale much more easily. Before OPAL- RT simulator system been sold in the market in late 1990s, real time simulation of the Electrical Grid is much more difficult. The OPAL-RT simulation system use a dictated computer system and efficient coding to make the power grid simulation runs much faster and able to display the result of the simulation in real time. The OPAL-RT simulation system also has many digital and analog output and input port, which can be use to connect and control many external hardware, by using this feature we can make a hardware in loop simulation to control and read the output of power simulation hardware in real time. The scope of this project is to study how to program the OPAL- RT simulation system to do the hardware simulation. I will also simulate the microgrid during main electrical grid fault using OPAL-RT simulation system and study how to improve the stability of the microgrid during black start after disconnect with the main electrical gird. Finally I will create a hardware in loop simulation to find if the result of the computer simulation match with the hardware in loop simulation