A differential game model research on dynamic pricing and coordination of fresh agricultural products supply chain based on freshness

For the problem of optimal dynamic pricing and coordination of fresh agricultural products supply chain, the differential equations related to freshness and market needs are constructed, and the optimal control theory is used to solve the optimal strategy under centralized and decentralized decision-making, i.e., optimal selling price and optimal preservation input. The equilibrium results under the two scenarios are also compared. The comparison finds that the decentralized scenario leads to low overall supply chain profits, based on which a two-part pricing contract is proposed to coordinate the supply chain operating companies. The results show that freshness effectiveness directly impacts pricing, and the centralized scenario does not necessarily lead to high prices for fresh produce due to the ‘double marginal effect’. the two pricing contracts can successfully coordinate the supply chain. The freshness effectiveness increases the supply chain coordination ability of fresh produce suppliers, while operational inefficiencies, on the contrary, decrease the coordination abilit

A New Single-blade Based Hybrid CFD Method for Hovering and Forward-flight Rotor Computation

AbstractA hybrid Euler/full potential/Lagrangian wake method, based on single-blade simulation, for predicting unsteady aerodynamic flow around helicopter rotors in hover and forward flight has been developed. In this method, an Euler solver is used to model the near wake evolution and transonic flow phenomena in the vicinity of the blade, and a full potential equation (FPE) is used to model the isentropic potential flow region far away from the rotor, while the wake effects of other blades and the far wake are incorporated into the flow solution as an induced inflow distribution using a Lagrangian based wake analysis. To further reduce the execution time, the computational fluid dynamics (CFD) solution and rotor wake analysis (including induced velocity update) are conducted parallelly, and a load balancing strategy is employed to account for the information exchange between two solvers. By the developed method, several hover and forward-flight cases on Caradonna-Tung and Helishape 7A rotors are performed. Good agreements of the loadings on blade surface with available measured data demonstrate the validation of the method. Also, the CPU time required for different computation runs is compared in the paper, and the results show that the present hybrid method is superior to conventional CFD method in time cost, and will be more efficient with the number of blades increasing

Cooperative Acoustic Navigation Scheme for Heterogenous Autonomous Underwater Vehicles

International audienceCooperative Acoustic Navigation Scheme for Heterogenous Autonomous Underwater Vehicle

Compressed Sensing and Low-Rank Matrix Decomposition in Multisource Images Fusion

We propose a novel super-resolution multisource images fusion scheme via compressive sensing and dictionary learning theory. Under the sparsity prior of images patches and the framework of the compressive sensing theory, the multisource images fusion is reduced to a signal recovery problem from the compressive measurements. Then, a set of multiscale dictionaries are learned from several groups of high-resolution sample image’s patches via a nonlinear optimization algorithm. Moreover, a new linear weights fusion rule is proposed to obtain the high-resolution image. Some experiments are taken to investigate the performance of our proposed method, and the results prove its superiority to its counterparts

Motion Segmentation by New Three-View Constraint from a Moving Camera

We propose a new method for the motion segmentation using a moving camera. The proposed method classifies each image pixel in the image sequence as the background or the motion regions by applying a novel three-view constraint called the “parallax-based multiplanar constraint.” This new three-view constraint, being the main contribution of this paper, is derived from the relative projective structure of two points in three different views and implemented within the “Plane + Parallax” framework. The parallax-based multiplanar constraint overcomes the problem of the previous geometry constraint and does not require the reference plane to be constant across multiple views. Unlike the epipolar constraint, the parallax-based multiplanar constraint modifies the surface degradation to the line degradation to detect the motion objects followed by a moving camera in the same direction. We evaluate the proposed method with several video sequences to demonstrate the effectiveness and robustness of the parallax-based multiplanar constraint

LCC-HVDC Converter Station Reactive Power Optimization and Two-Layer Coordination Strategy Research Based on Synchronous Sondenser

[Introduction] Under the existing converter station reactive power compensation scheme, the synchronous condenser only provides transient reactive power support, and the AC (Alternating Current) filter undertakes steady-state reactive power compensation and adjustment tasks, with a lack of coordination scheme between the two and insufficient economy. [Method] On the basis of ensuring the dynamic characteristics of the synchronous condenser, based on the operating characteristics of the DC (Direct Current) sending and receiving end systems, firstly, a reactive power optimization scheme for the converter station was proposed, in which the regulator was used to replace a part of the part of the AC filter capacity with the regulator, and both participated in steady state reactive power compensation. Ubsequently, a two-layer reactive power adjustment strategy for the converter station was proposed according to the sequence of actions. The first layer of reactive power adjustment was undertaken by the synchronous condenser, which was realized by adjusting the output within the range of steady state operation. The second layer of reactive power adjustment was started after the first layer of reactive power adjustment, and the AC filters were switched on group by group for reactive power adjustment until the reactive power adjustment requirement of the converter station was reached. Finally, a LCC-HVDC (Line-Commutated Converter High Voltage Direct Current) system simulation model was built in PSCAD for simulation verification. [Result] The simulation results show that the reactive power compensation scheme and the two-layer reactive power adjustment strategy proposed can optimize the number of AC filter configuration groups in the converter station, reduce the frequency of AC filter switching in the converter station. [Conclusion] The proposed scheme achieves optimization of the existing LCC-HVDC converter station reactive power compensation scheme and reactive power adjustment strategy

A novel esterase gene cloned from a metagenomic library from neritic sediments of the South China Sea

<p>Abstract</p> <p>Background</p> <p>Marine microbes are a large and diverse group, which are exposed to a wide variety of pressure, temperature, salinity, nutrient availability and other environmental conditions. They provide a huge potential source of novel enzymes with unique properties that may be useful in industry and biotechnology. To explore the lipolytic genetic resources in the South China Sea, 23 sediment samples were collected in the depth < 100 m marine areas.</p> <p>Results</p> <p>A metagenomic library of South China Sea sediments assemblage in plasmid vector containing about 194 Mb of community DNA was prepared. Screening of a part of the unamplified library resulted in isolation of 15 unique lipolytic clones with the ability to hydrolyze tributyrin. A positive recombinant clone (pNLE1), containing a novel esterase (Est_p1), was successfully expressed in <it>E. coli </it>and purified. In a series of assays, Est_p1 displayed maximal activity at pH 8.57, 40°C, with ρ-Nitrophenyl butyrate (C₄) as substrate. Compared to other metagenomic esterases, Est_p1 played a notable role in specificity for substrate C₄(<it>k</it>_cat/<it>K</it>_mvalue 11,500 S^-1m M^-1) and showed no inhibited by phenylmethylsulfonyl fluoride, suggested that the substrate binding pocket was suitable for substrate C₄and the serine active-site residue was buried at the bottom of substrate binding pocket which sheltered by a lid structure.</p> <p>Conclusions</p> <p>Esterase, which specificity towards short chain fatty acids, especially butanoic acid, is commercially available as potent flavoring tools. According the outstanding activity and specificity for substrate C₄, Est_p1 has potential application in flavor industries requiring hydrolysis of short chain esters.</p