A Calibration Method for Wide Field Multicolor Photometric System

The purpose of this paper is to present a method to self-calibrate the spectral energy distribution (SED) of objects in a survey based on the fitting of an SED library to the observed multi-color photometry. We adopt for illustrative purposes the Vilnius (Strizyz and Sviderskiene 1972) and Gunn & Stryker (1983) SED libraries. The self-calibration technique can improve the quality of observations which are not taken under perfectly photometric conditions. The more passbands used for the photometry, the better the results. This technique has been applied to the BATC 15-passband CCD survey.Comment: LateX file, 1 PS file, submitted to PASP number 99-025 The English has been improved and some mistakes have been correcte

Antidiabetic effect of Tibetan medicine Tang-Kang-Fu-San on high-fat diet and streptozotocin-induced type 2 diabetic rats

The aim of this study was to investigate the antidiabetic effects of a Tibetan medicine, Tang-Kang-Fu-San (TKFS), on experimental type 2 diabetes mellitus (T2DM) rats and to explore its underlying mechanisms. Firstly two major chemical compositions of TKFS, gallic acid and curcumin, were characterized by HPLC fingerprint analysis. Next T2DM in rats was induced by high-fat diet and a low-dose streptozotocin (STZ 35 mg/kg). Then oral gavage administration of three different doses of TKFS (0.3 g/kg, 0.6 g/kg, and 1.2 g/kg) was given to T2DM rats. Experimental results showed that TKFS dramatically reduced the levels of fasting blood glucose, fasting blood insulin, triglyceride, total cholesterol, LDL cholesterol, and HDL cholesterol, even though it did not alter the animal body weight. The downregulation of phosphorylation-AKT (p-AKT) and glucose transporter-4 (GLUT4) in skeletal muscle of T2DM rats was restored and abnormal pathological changes in pancreas tissues were also improved. Our work showed that TKFS could alleviate diabetic syndromes, maintain the glucose homeostasis, and protect against insulin resistance in T2DM rats, and the improvement of AKT phosphorylation and GLUT4 translocation in skeletal muscle would be one of its possible underlying mechanisms

Tri-Band Dual-Polarized Shared-Aperture Antenna Arrays with Wide-Angle Scanning and Low Profile for 5G Base Stations

A novel tri-band shared aperture antenna (TSAA) array is proposed in this paper to meet the requirements of modern base station antennas for multi-band antenna fusion and independent control. Different antenna types are utilized for each operating band, including 3D-printed dielectric resonator antennas (DRAs) for the middle bands (MB, 3.4 to 3.6 GHz) and high bands (HB, 5.4 to 5.6 GHz), and dipole antennas forthe low band (LB, 1.85 to 2.15 GHz). The TSAA comprises a 1x4 dipole antenna array for LB, a 2x7 MB antenna array located at the edges of the aperture, and a 2x12 HB antenna array at the aperture center. The LB dipole antenna array is positioned above the MB and HB antenna arrays, providing wideband electromagnetic transparency for both MB and HB simultaneously. By exploiting the high dielectric permittivity ofthe DRAs, the overall array profile is miniaturized to 0.13 0 (0 is the free-space wavelength at central frequency of LB), while the array element spacing meets scanning conditions for suppressing grating lobes and achieving wide-angle control of each frequency band. Additionally, the adoption of symmetric -shaped stripline coupled feeding technology in the LB antenna effectively improves the problem of tilted radiation patterns of the HB antenna

Analysis of nonlinear suspension power harvest potential

Because the power consumption of a controlled suspension is huge, the power harvest potential of a nonlinear controlled suspension is analyzed. Instead of simplifying the suspension to a linear model or adopting some control strategies to solve the problem, this paper investigates the effect of the nonlinear characteristics on the power harvesting potential. A mathematic model is introduced to calculate the nonlinear vibration, and the amount of harvested power was obtained using the multi-scale method. A numerical validation is carried out at the end of this study. The results show that the investigated mechanical parameters affect both the vibration amplitude and the induced current, while the electric parameters only affect the induced current. The power harvesting potential of the nonlinear suspension is generally greater than the linear suspension because the frequency band of the actual pavement also contains bandwidth surrounding the body resonance point. The only exception occurs if the vehicle travels on a road with a particular profile, e.g. a sine curve. To optimize harvested power, it is better to consider the nonlinear characteristics rather than simplifying the suspension to a linear model

Internal Model Current Control of Brushless Doubly Fed Induction Machines

In the wind energy generation system, the brushless doubly-fed induction machine (BDFIM) has shown significant application potential, since it eliminates the electric brush and slip ring. However, the complicated rotor structure increases the control difficulty, especially resulting in complicated coupled terms in the current sub-system, which deteriorates the dynamic performance and reduces the system robustness. In order to address the problems caused by complex coupled terms, an internal model current control strategy is presented for the BDFIM, and an active damping term is designed for suppressing the disturbance caused by the total resistance. The proposed method simplifies the controller parameters design, and it achieves the fast-dynamic response and the good tracking performance, as well as good robustness. On the other hand, the feedforward term composed by the grid voltage is added to the internal model controller in order to suppress the disturbance when the symmetrical grid voltage sag happens. Finally, the simulation and experimental results verify the feasibility and effectiveness of the proposed method