There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Probability Distributions.- Linear Models for Regression.- Linear Models for Classification.- Neural Networks.- Kernel Methods.- Sparse Kernel Machines.- Graphical Models.- Mixture Models and EM.- Approximate Inference.- Sampling Methods.- Continuous Latent Variables.- Sequential Data.- Combining Models.

Pattern Recognition and Machine Learning

The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

The adoption of a reconfigurable intelligent surface (RIS) for downlink multi-user communication from a multi-antenna base station is investigated in this paper. We develop energy-efficient designs for both the transmit power allocation and the phase shifts of the surface reflecting elements subject to individual link budget guarantees for the mobile users. This leads to non-convex design optimization problems for which to tackle we propose two computationally affordable approaches, capitalizing on alternating maximization, gradient descent search, and sequential fractional programming. Specifically, one algorithm employs gradient descent for obtaining the RIS phase coefficients, and fractional programming for optimal transmit power allocation. Instead, the second algorithm employs sequential fractional programming for the optimization of the RIS phase shifts. In addition, a realistic power consumption model for RIS-based systems is presented, and the performance of the proposed methods is analyzed in a realistic outdoor environment. In particular, our results show that the proposed RIS-based resource allocation methods are able to provide up to 300% higher energy efficiency in comparison with the use of regular multi-antenna amplify-and-forward relaying.

Reconfigurable Intelligent Surfaces for Energy Efficiency in Wireless Communication

An electronically steerable monopulse antenna based on reconfigurable reflectarray antenna (RRA) has been designed, fabricated and tested. The large-scale RRA at X-band is consisted of $160\times 64$ elements integrated with PIN diodes, and is controlled by arrays of 160 field-programmable gate arrays (FPGAs) in parallel, for the steerable monopulse patterns. The steerable sum-difference beams are achieved by the diode state distributions of the RRA. The gain of the RRA is measured to be 37.35dBi, and the null-depth is measured to be -43.51dB at the direction angle of 0 o. A null-depth of under -37.54dB is verified at the direction angle of 60°. The electronically steerable monopulse antenna based on RRA presents a low-cost solution for high resolution tracking applications.

An X-band Reconfigurable Reflectarray Antenna with Steerable Monopulse Patterns

The equivalence principle algorithm is a domain decomposition scheme based on integral equation formulation. One of the key building blocks in this algorithm is the equivalence principle operator that computes the scattered equivalent current on a virtual closed surfaces. In this abstract, we studied the numerical error of the inside-out procedure in the equivalence principle operator. This procedure projects smooth electromagnetic fields in three dimensions onto two-dimensional equivalence currents that may contain geometrical discontinuities. We observe that the field projection error is related with the geometry of the equivalence surfaces as well as the choice of expansion functions for electric and magnetic currents. A careful choice of these parameters could help to further improve the accuracy of the equivalence principle algorithm.

Numerical study on the field projection error in the equivalence principle algorithm

Soluble sugar accumulation in fruit ripening determines fleshy fruit quality. However, the molecular mechanism for this process is not yet understood. Here, we showed a transcriptional repressor, CmMYB44, regulates sucrose accumulation and ethylene synthesis in oriental melon (Cucumis. melo var. makuwa Makino) fruit. Overexpressing CmMYB44 suppressed sucrose accumulation and ethylene production. Furthermore, CmMYB44 repressed the transcriptional activation of CmSPS1 (sucrose phosphate synthase 1)and CmACO1 (ACC oxidase 1), two key genes in sucrose and ethylene accumulation, respectively. During the later stages of fruit ripening, the repressive effect of CmMYB44 on CmSPS1 and CmACO1 could be released by overexpressing CmERFI-2 (ethylene response factor I-2) and exogenous ethylene in 'HS' fruit (high sucrose accumulation fruit). CmERFI-2 acted upstream of CmMYB44 as a repressor by directly binding the CmMYB44 promoter region, indirectly stimulating the expression level of CmSPS1 and CmACO1. Taken together, we provided a molecular regulatory pathway mediated by CmMYB44, which determines the degree of sucrose and ethylene accumulation in oriental melon fruit and sheds light on transcriptional responses triggered by ethylene sensing that enable the process of fruit ripening.

The transcription factor CmERFⅠ-2 represses CmMYB44 expression to increase sucrose levels in oriental melon fruit.

With the development of electromagnetic theory and fabrication technology, quasi-periodic arrays have been used in many novel electromagnetic devices. These arrays have similar elements located on a periodic lattice. Different from periodic arrays, the elements in a quasi-periodic array are not the same, and the whole array is usually electrically large with multi-scale features. In this work we study fast algorithms for fullwave simulation of quasi-periodic arrays. We apply the reduced basis method to reduce the number of unknowns of the quasi-periodic arrays. To compress the mutual coupling impedance matrix and further accelerate the solution process, we adopt the $\mathcal {H}^{2}-$ matrix algorithm and combine it with the reduced basis method. Numerical examples also validate the accuracy and efficiency of this method using integral equation solvers.

Quasi-Periodic Array Modeling Using Reduced Basis with H 2 -Matrix Algorithm

The invention relates to an optimal control method for real-time safety correction of gateway electric power of a multi-energy system and belongs to the technical field of integrated energy system operation and control. The method has the advantages that by utilizing the characteristics of multi-energy coupling and complementing, the purpose of reducing the gateway electric power of the multi-energy system is achieved through the cooperative control of various energy devices such as electrical energy devices, thermal energy devices, cold energy devices and the like and the optimal real-time safety corrective control is realized by using linear optimization; an optimal control model for the real-time safety correction is provided, the linearization of the optimal model is realized by specifying the adjustment direction of each device and the rapid solving and the engineering application are benefited; and the method can be applied to the real-time online operation control of the multi-energy system and when the situation that the gateway electric power exceeds the upper limit is monitored, the adjustment amount of each device is calculated through the method, the gateway electric power is reduced and the safe operation of the multi-energy system is guaranteed.

Fan Yang

Papers

An X-band Reconfigurable Reflectarray Antenna with Steerable Monopulse Patterns

Numerical study on the field projection error in the equivalence principle algorithm

The transcription factor CmERFⅠ-2 represses CmMYB44 expression to increase sucrose levels in oriental melon fruit.

Quasi-Periodic Array Modeling Using Reduced Basis with H 2 -Matrix Algorithm

Optimal control method for real-time safety correction of gateway electric power of multi-energy system