Partial Shade Optimizes Photosynthesis and Growth in Bayberry (Myrica rubra) Trees

Guanghui Zeng,Yanping Guo,Jianxu Xu,Meijun Hu,Jie Zheng,Zhenwang Wu 한국원예학회 2017 Horticulture, Environment, and Biotechnology Vol.58 No.3

This study investigates the effects of radiation heat-load reduction under different shading conditions on thegrowth of three-year-old bayberry (Myrica rubra) trees from 1 July through 31 October 2007 in the Zhejiang Province,a warm subtropical region of China. The trees were grown under direct sunlight (control) and under 25%, 50%, and75% shading conditions using black plastic nets. Stomatal conductance and photosynthesis were greatest under 50%shading, as were plant height and leaf and root dry weights. Twenty-five percent shading did not significantly influenceplant height or root and leaf dry weights, whereas 75% shading resulted in a decrease in root and leaf dry weightswhen compared with the controls. The photochemical efficiency and electron transport of PSII increased under shadedconditions due to an increase in D1 protein. The concentrations of chlorophyll a and b and the total chlorophyllcontent in leaves were increased in plants grown under 25% and 50% shading, but reduced in those grown under75% shading. Under 50% shading, growth and biomass increased due to increased photosynthesis, which resulted fromdecreased photodamage and increased chlorophyll concentration. These data show that 50% shading promotes optimalgrowth in bayberry plants.

An effective online delay estimation method based on a simplified physical system model for real-time hybrid simulation

Zhen Wang,Bin Wu,Guoshan Xu,Yong Ding,Oreste S. Bursi 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.6

Real-Time Hybrid Simulation (RTHS) is a novel approach conceived to evaluate dynamic responses of structures with parts of a structure physically tested and the remainder parts numerically modelled. In RTHS, delay estimation is often a precondition of compensation; nonetheless, system delay may vary during testing. Consequently, it is sometimes necessary to measure delay online. Along these lines, this paper proposes an online delay estimation method using least-squares algorithm based on a simplified physical system model, i.e., a pure delay multiplied by a gain reflecting amplitude errors of physical system control. Advantages and disadvantages of different delay estimation methods based on this simplified model are firstly discussed. Subsequently, it introduces the least-squares algorithm in order to render the estimator based on Taylor series more practical yet effective. As a result, relevant parameter choice results to be quite easy. Finally in order to verify performance of the proposed method, numerical simulations and RTHS with a buckling-restrained brace specimen are carried out. Relevant results show that the proposed technique is endowed with good convergence speed and accuracy, even when measurement noises and amplitude errors of actuator control are present.

An adaptive delay compensation method based on a discrete system model for real-time hybrid simulation

Zhen Wang,Guoshan Xu,Qiang Li,Bin Wu 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.25 No.5

The identification of delays and delay compensation are critical problems in real-time hybrid simulations (RTHS). Conventional delay compensation methods are mostly based on the assumption of a constant delay. However, the system delay may vary during tests owing to the nonlinearity of the loading system and/or the behavioral variations of the specimen. To address this issue, this study presents an adaptive delay compensation method based on a discrete model of the loading system. In particular, the parameters of this discrete model are identified and updated online with the least-squares method to represent a servo hydraulic loading system. Furthermore, based on this model, the system delays are compensated for by generating system commands using the desired displacements, achieved displacements, and previous displacement commands. This method is more general than the existing compensation methods because it can predict commands based on multiple displacement categories. Moreover, this method is straightforward and suitable for implementation on digital signal processing boards because it relies solely on the displacements rather than on velocity and/or acceleration data. The virtual and real RTHS results show that the studied method exhibits satisfactory estimation smoothness and compensation accuracy. Furthermore, considering the measurement noise, the low-order parameter models of this method are more favorable than that the high-order parameter models.

Performance validation and application of a mixed force-displacement loading strategy for bi-directional hybrid simulation

Zhen Wang,Qiyang Tan,Pengfei Shi,Ge Yang,Siyu Zhu,Guoshan Xu,Bin Wu,Jianyun Sun 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.3

Hybrid simulation (HS) is a versatile tool for structural performance evaluation under dynamic loads. Although real structural responses are often multiple-directional owing to an eccentric mass/stiffness of the structure and/or excitations not along structural major axes, few HS in this field takes into account structural responses in multiple directions. Multi-directional loading is more challenging than uni-directional loading as there is a nonlinear transformation between actuator and specimen coordinate systems, increasing the difficulty of suppressing loading error. Moreover, redundant actuators may exist in multi-directional hybrid simulations of large-scale structures, which requires the loading strategy to contain ineffective loading of multiple actuators. To address these issues, lately a new strategy was conceived for accurate reproduction of desired displacements in bi-directional hybrid simulations (BHS), which is characterized in two features, i.e., iterative displacement command updating based on the Jacobian matrix considering nonlinear geometric relationships, and force-based control for compensating ineffective forces of redundant actuators. This paper performs performance validation and application of this new mixed loading strategy. In particular, virtual BHS considering linear and nonlinear specimen models, and the diversity of actuator properties were carried out. A validation test was implemented with a steel frame specimen. A real application of this strategy to BHS on a full-scale 2-story frame specimen was performed. Studies showed that this strategy exhibited excellent tracking performance for the measured displacements of the control point and remarkable compensation for ineffective forces of the redundant actuator. This strategy was demonstrated to be capable of accurately and effectively reproducing the desired displacements in large-scale BHS.

Preparation and characterization of flaky FeSiAl composite magnetic powder core coated with MnZn ferrite

Zhen Wang,Xiansong Liu,Xucai Kan,Ruiwei Zhu,Wei Yang,Qiuyue Wu,Shengqiang Zhou 한국물리학회 2019 Current Applied Physics Vol.19 No.8

The flattening of FeSiAl soft magnetic powder was achieved by ball milling process, and MnZn/FeSiAl composite magnetic powder core was prepared by press molding. The effect of different coating amount of MnZn ferrite on the soft magnetic properties of FeSiAl was studied. At the same time, the optimal stress-relieving annealing temperature of the composite magnetic powder core is revealed. The results showed that the addition of MnZn ferrite affected the magnetic properties such as saturation magnetization (Ms), initial permeability (μi) and power loss (Pcm) of FeSiAl soft magnetic. With the increase of MnZn ferrite addition content, the saturation magnetization of composites decreased gradually, and the magnetic permeability increased first and then decreased, and the loss decreased first and then increased. When the addition content of MnZn ferrite was 5%, the permeability reached the maximum, which was 28.1% higher than that of the pure FeSiAl magnetic powder core under the same conditions. At the same time, the loss was the lowest, which was 13.3% lower than the pure FeSiAl powder core under the same conditions. When the annealing temperature is around 650 °C, the magnetic powder core has the largest magnetic permeability and the lowest loss.