Dynamic Response of a Casting Crane Rigid-Flexible Coupling System to High Temperature

To determine the influence of temperature on the mechanical properties of crane metal structures, three Q355 alloy steel samples were processed and their elastic moduli were tested at different temperatures using a metal tension test bed. The constitutive equation for the elastic modulus of Q355 alloy steel at different temperatures was predicted using test data and a neural network algorithm. Based on crane structural characteristics and the principle of system dynamics, a coupling vibration model was established that included the crane flexible girder, cabin, trolley, crane, and temperature. System motion equations were established according to the Lagrange equation, and the approximate solution of nonlinear system vibration was solved by the direct integration method (the Newmark method). The dynamic characteristics of the main beam and cabin were analyzed at different temperatures, as well as safety during service. The results show that, with increasing temperature, the maximum midspan displacement of the main beam increases gradually, by 14.3%, 21.4%, and 57.1% at temperatures of 300°C, 400°C, and 600°C, respectively. The cabin vibration displacement increases with temperature, by up to 32.5% at 600°C, but the influence of temperature on cabin vibration acceleration is not obvious. It was concluded that the influence of temperature on the dynamic characteristics of the main beam must be considered during the design stage of cranes. The proposed model and analysis method provide a theoretical basis for the design of casting cranes according to temperature

A new specular reflection optimization algorithm

With the development of optimization theory and the application of computer technology, some new intellective optimization algorithms are developed quickly and applied widely, which is becoming the most important method for optimization problems. In this article, a new intellective optimization algorithm—Specular Reflection Algorithm—is proposed by authors who are inspired by the physical function of mirror. The traditional mathematical theory is used to prove the global convergence of this new algorithm. In order to validate the performance of this algorithm, three classical testing functions are adopted; then the algorithm is used to solve discrete engineering optimization problems and the results indicate that the Specular Reflection Algorithm has higher computation efficiency and extensive prospect for engineering application

Analysis on the Difference of Quality and Mineral Elements Among Jinmudan Oolong Tea

The sensory evaluation scores, quality indexes (tea polyphenols, caffeine, 8 catechins, soluble sugars, free amino acids, theanine, water extracts and total flavonoids) and 8 mineral elements of different grades of Jinmudan Oolong tea were determined. The results showed that the higher the grade, the higher the water extract content of Jinmudan Oolong tea, and the water extract content of Grand Prize was 1.07% and 1.75% higher than that of first prize and quality prize, respectively, and the differences all reached a significant level (P0.05). The ratio of phenol to ammonia was significantly lower in the grand prize than in the first prize and the quality prize (P0.05). The restricted principal coordinates analysis showed that the quality indexes combined with restricted principal coordinates analysis could well distinguish the grade differences of Jinmudan Oolong tea with an R value of 1.00. However, the mineral elements combined with restricted principal coordinates analysis did not well distinguish the quality differences of different grades of Jinmudan Oolong tea. These results could provide a certain reference for the quality judgment of Jinmudan Oolong tea

Contribution of traditional deep fermentation to volatile metabolites and odor characteristics of Wuyi rock tea

Fermentation is extremely important for the formation of the special flavor of Wuyi rock tea. This study determined volatile metabolite contents using GC-MS technique and futher analyzed their odor characteristics during the traditional deep fermentation technology of Wuyi rock tea. The results showed that 17 characteristic compounds significantly changed during the first stage of the preliminary processing, namely fresh leaves, withering and fermentation. The key to the formation of floral aroma lied in dihydromyrcenol, and the woody aroma derived from six terpenoids, and their synthesis depended on dihydromyrcenol content. The fruity aroma was dominated by six esters, and the fruity aroma mainly came from (Z) -3-hexen-1-yl butyrate, (E) -3-hexen-1-yl butyrate and 5-Hexenyl butyrate. This study provided an important theoretical and practical basis for improving the preliminary processing of Wuyi rock tea