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Turbulent winds and earthquakes are the two main factors that lead to the vibration of the wind turbine tower. In order to study the dynamic response characteristics and anti-seismic of wind turbine structure under wind-earthquake coupling condition, NREL 5 MW wind turbine is studied. A soil-structure interaction model was established by Wolf Method, and based on the multi body dynamics simulation and open source software FAST, the seismic load calculation module is developed. The structural control of the wind turbine tower under the seismic condition is carried out by configuring a tuned mass damper（Tuned Mass damper, TMD） at the top of the tower by self-compiling program. The results show that the seismic load greatly increases the lateral vibration of the tower, and the excitation frequency is the first-order lateral natural frequency of the tower. Under the control of TMD, the dynamic response of tower and nacelle are obviously reduced, where the amplitude of lateral displacement of the tower top is reduced by 18%, the standard deviation is reduced by 67%, and the response amplitude of the first order natural frequency of tower is greatly reduced, as high as 90%. Additionally, the variation of the lateral acceleration of the tower top is reduced by 4%, the standard deviation is reduced by 61%, and the peak vibration of the first-order natural frequency decreases by 88%. Therefore, the TMD can be used for anti-seismic of wind turbines in extreme environments such as earthquakes, and improve the stability of wind turbines.

Human muscles can grow and change their length with body development; therefore, artificial muscles that modulate their morphology according to changing needs are needed. In this paper, we report a strategy to transform an artificial muscle into a new muscle with a different morphology by thermodynamic-twist coupling, and illustrate its structural evolution during actuation. The muscle length can be continuously modulated over a large temperature range, and actuation occurs by continuously changing the temperature. This strategy is applicable to different actuation modes, including tensile elongation, tensile contraction and torsional rotation. This is realized by twist insertion into a fibre to produce torsional stress. Fibre annealing causes partial thermodynamic relaxation of the spiral molecular chains, which serves as internal tethering and inhibits fibre twist release, thus producing a self-supporting artificial muscle that actuates under heating. At a sufficiently high temperature, further relaxation of the spiral molecular chains occurs, resulting in a new muscle with a different length. A structural study provides an understanding of the thermodynamic-twist coupling. This work provides a new design strategy for intelligent materials. [ABSTRACT FROM AUTHOR]

There are targets with different velocities in the radar echoes and Doppler phase difference between multi-band signals is dependent on velocity, which cannot be compensated by multiplying the uniform fixed phase and linear phase. This paper proposes a Doppler phase compensation method based on Keystone transform to solve this problem. This method defines a new slow time variable, which scales the slow time axis as a function of fast frequency to complete the Doppler phase compensation for different velocity targets at the same time. The effectiveness of the algorithm is verified by simulation analysis, which provides a method for mutual-coherence processing in multi-band and multi-target signal coherent processing. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we analyze effectiveness factors of Pt utilization in perfluorosulfonate ionomer (PFSI) bonded thin film cathode catalyst layers of polymer electrolyte fuel cells. We define the effectiveness [...]

For the treatment of complex volatile organic compounds (VOCs) exhaust gas in the process of petrochemical production, a high-efficiency regenerative thermal oxidation reactor technology was developed. Combined with exhaust gases pre-treatment and concentration regulation technology such as absorption and condensation, the regenerative thermal oxidation reactor has been applied industrially in exhaust gas treatment for tank area, loading, oil-greasy pool and gasoline oxidation decathiol process in petrochemical enterprises. The industrial application effect of exhaust gas treatment using two-bed thermal oxidation reactor and three-bed thermal oxidation reactor was investigated respectively. The industrial experiments show that the effect of the three-bed thermal oxidation reactor is much better than that of the two-bed thermal oxidation reactor. For the complex VOCs exhaust gas in petrochemical enterprises, after treated by the three-bed thermal oxidation reactor, the total hydrocarbon concentration in the purified gas is less than 10 mg/m³, the concentration of hydrogen sulfide, organic sulfide, benzene, toluene, xylene is lower than the detection limits, which is superior to the most stringent emission standards, and realizing near zero emission of VOCs. [ABSTRACT FROM AUTHOR]

Alkaline absorbent jet SO3 removal technology is a technology that uses the acid-base neutralization reaction between alkaline absorbent and SO3 in flue gas to remove SO3. It has high SO3 removal efficiency and can alleviate the problems of denitration catalytic blockage and downstream equipment corrosion. The removal effects of several alkaline absorbents on SO3 in flue gas are studied. The experimental results show that the mixed absorbent with a certain proportion has a better removal ability of SO3 than a single absorbent. Appropriately increasing the reaction time and temperature are conducive to improving the removal effect of SO3. In order to ensure the removal effect of SO3 from flue gas and the stable operation of the alkaline absorber injection system, it is necessary to make a reasonable process design for the alkali absorbent mixture, conveying and injection system. [ABSTRACT FROM AUTHOR]

A study was conducted to characterize a structural approximate procedure for topological modifications of finite element systems that supports the introduction and reanalysis of the modified initial stiffness matrix. Topological changes were represented into two types based on changes to degrees of freedom. Results indicated the effectivity of the method during changes in topological modifications.

Uncarboxylated osteocalcin (unOc) is an osteoblast‐derived hormone with multiple regulatory functions. Osteocalcin knockdown delays the maturation of mineral species and downregulates the expression of osteogenic‐specific genes in human mesenchymal stromal cells. However, the underlying mechanisms remain unclear. Here, we investigated the effects of unOc on the osteogenic differentiation of mouse bone marrow–derived mesenchymal stem cells (BMSCs) and discovered that unOc promoted osteogenic differentiation of BMSCs, which was characterized by increases in alkaline phosphatase (ALP) activity, type I collagen (COLI) production, calcified nodule formation, and expression of osteogenic‐specific genes including the osterix, runt‐related transcription factor 2 (Runx2), ALP, and COLI genes. Further experiments indicated that unOc promoted the osteogenic differentiation of BMSCs via activation of the Erk‐Smad/β‐catenin signalling pathways. Significance of the study: Osteoporosis is associated with the osteogenic differentiation of BMSCs. In recent years, the role of unOc function as an endocrine hormone has received much attention. In this study, we reported for the first time that unOc promoted the osteogenic differentiation of mouse BMSCs through Erk‐Smad/β‐catenin signalling pathway. Our results highlight the importance of unOc as a hormone in promoting the osteogenic differentiation of BMSCs, indicating that this hormone may be beneficial in treatments for osteoporosis and fracture healing. [ABSTRACT FROM AUTHOR]