Dynamic Response and Optimal Design of Radio Telescope Structure under Wind Load Excitation

The dynamic response of a radio telescope structure under wind load excitation significantly impacts the accuracy of signal reception. To address this issue, this study established a parametric finite element model of a radio telescope to simulate its dynamic response under wind load excitation. An improved Latin hypercube sampling method was applied in the design of experiments (DOEs) to optimize the structural dimensional parameters of various components of the radio telescope with the aim of reducing the dynamic response to wind load. A response surface model and multi-objective genetic algorithm (MOGA) were employed for multi-objective structural optimization of the radio telescope structure. The findings reveal that the thickness of the stiffening ribs, the length of the side of the square hollow pole, the thickness of the middle pole, and the inner diameter of the thin pole are the most influential structural parameters affecting the first-order frequency (F1), second-order frequency (F2), maximum deformation in the x-direction (DX), and maximum deformation in the z-direction (DZ) of the radio telescope, respectively. Optimizing the radio telescope results in a 40.00% improvement in F1 and a 24.16% enhancement in F2, while reducing DX by 43.94% and DZ by 64.25%. The study outcomes offer a comprehensive scheme for optimizing the structural dimensional parameters of various radio telescope components in regions characterized by multiple wind fields

Visual Monitoring of Food Spoilage Based on Hydrolysis-Induced Silver Metallization of Au Nanorods

Colorimetric detection of biogenic amines, well-known indicators of food spoilage, plays an important role for monitoring of food safety. However, common colorimetric sensors for biogenic amines suffer from low color resolution or complicated design and intricate output for the end-users. Herein, we explored a simple but effective strategy for visual monitoring of biogenic amines with multiple color change based on hydrolysis-induced silver metallization reaction to tune the localized surface plasmon resonance (LSPR) adsorption of Au nanorods (NRs). The color change and blue shift of longitudinal LSPR peak of Au NRs were closely related to the concentration of biogenic amines. This strategy provided a simple, sensitive, robust, nondestructive, cost-effective, and user-friendly platform for in situ evaluating the freshness of foodstuffs

Specifically and Visually Detect Methyl-Mercury and Ethyl-Mercury in Fish Sample Based on DNA-Templated Alloy Ag–Au Nanoparticles

Methyl-mercury (CH₃Hg⁺) and ethyl-mercury (C₂H₅Hg⁺) have much higher toxicity than Hg²⁺ and can be more easily accumulated by organisms to form severe bioamplification. Hence, the specific and on-site detection of CH₃Hg⁺ and C₂H₅Hg⁺ in seafood is of great significance and a hard challenge. We herein designed two T-rich aptamers (H_T5 and H_T7) for specifically recognizing CH₃Hg⁺ and the total of CH₃Hg⁺ and C₂H₅Hg⁺, respectively. In the presence of all Au³⁺, Ag⁺, and T-rich aptamer, CH₃Hg⁺ and C₂H₅Hg⁺ specifically and preferentially bind with aptamer and thus induced the formation of alloy Ag–Au nanoparticles after reduction, which led to the color change in solution. This provided a sensing platform for the instrument-free visual discrimination and detection of CH₃Hg⁺ and C₂H₅Hg⁺. By using H_T5 as probe, the method can be used to detect as low as 5.0 μM (equivalent to 1.0 μg Hg/g) of CH₃Hg⁺ by bare eye observation and 0.5 μM (equivalent to 100 ng Hg/g) of CH₃Hg⁺ by UV–visible spectrometry. By using H_T7 as probe, the method can be used to detect the total concentration of CH₃Hg⁺ and C₂H₅Hg⁺ with a visual detection limit of 5.0 μM (equivalent to 1.0 μg Hg/g) and a UV–visible spectrometry detection limit of 0.6 μM (equivalent to 120 ng Hg/g). The proposed method has been successfully used to detect CH₃Hg⁺ and C₂H₅Hg⁺ in fish muscle samples with a recovery of 101–109% and a RSD (<i>n</i> = 6) < 8%. The success of this study provided a potential method for the specific and on-site detection of CH₃Hg⁺ and C₂H₅Hg⁺ in seafood by only bare eye observation

Large-energy, wavelength-tunable, all-fiber passively Q-switched Er:Yb-codoped double-clad fiber laser with mono-layer chemical vapor deposition graphene

National Natural Science Foundation of China [61275050, 61177044]; Natural Science Foundation of Fujian Province of China [2011J01370]; Specialized Research Fund for the Doctoral Program of Higher Education [20120121110034]; Fundamental Research Funds for the Central Universities [2011121048]We demonstrate a large-energy, wavelength-tunable, all-fiber passively Q-switched Er:Yb-codoped laser using a mono-layer chemical vapor deposition (CVD) graphene saturable absorber (SA). By exploiting the large laser gain of Er:Yb double-clad fiber and optimizing the coupling ratio of the output coupler, not only can the mono-layer CVD graphene SA be protected from oversaturation and thermal damage, but also a large pulse energy up to 1.05 mu J (corresponding to the average output power of 25.6 mW) is thus achieved. Using a tunable fiber Fabry-Perot filter, stable Q-switched pulses can operate with a tunable range from 1530.97 to 1546.92 nm, covering a wavelength range of similar to 16 nm. The Q-switching states at the different lasing wavelengths have been observed and recorded. The Q-switched repetition rate and the pulse duration (with the minimum one of 2.6 mu s) have been characterized as well. This is, to the best of our knowledge, the largest pulse energy from an all-fiber graphene Q-switched laser. (C) 2014 Optical Society of Americ

Passive synchronization of 106- and 153-μm fiber lasers Q-switched by a common graphene SA

We demonstrate the passive synchronization of two large-energy Q-switched all-fiber lasers, operating at 1.06 and 1.53 μm, by sharing a common monolayer graphene Q-switcher. The fiber-compatible Q-switcher is constructed by transferring a monolayer CVD graphene nanosheet onto a fiber ferrule. By exploiting the broadband saturable absorption of graphene and optimizing the cavity designs, both the largeenergy Q-switched Yb and Er/Yb double-clad fiber lasers are successfully synchronized. The Q-switching synchronization can be realized in the broad repetition-rate range of 9-20 kHz by adjusting the pump powers of the two lasers. The maximum pulse energies are 5.30 μJ at 1.06 μm and 1.20 μJ at 1.53 μm, respectively, which is, to the best of our knowledge, the largest pulse energy obtained from graphene Q-switched all-fiber laser. ? 1989-2012 IEEE