Advanced Materials Research Vols. 181-182

Abstract: A new optical instrument for fast determination of pear leaves nitrogen status was designed and fabricated. A multi-spectral imaging system was used as optical detector. In the paper, the principle of multi-spectral imaging for the measurement of leaves nitrogen status was first introduced. Then, the method of using error back propagation artificial neural network (BP-ANN) for calibration modeling was elaborated. Mean reflective light intensities in all images covering blue, green, red and infrared wavelength were taken as the input data to BP-ANN. The structure of BP-ANN with three layers has been optimized to minimize its calibration error. In the test, total 200 leave samples picked from Huang-hua pear trees planted in three orchards with different nitrogen fertilizing schemes. Among them, 150 samples were selected randomly out as for calibration set with the remaining 50 for prediction set. The result shows that correlation coefficient of R2 between predicted and measured values of nitrogen content reaches 0.82 with maximum prediction error less than 4.72(SPAD). The study suggests that the new optical method integrating multi-spectral images with BP-ANN is promising for fast diagnosis of fruit tree nutrition status.

Abstract: In this paper, a robust image watermarking method in two-dimensional space/spatial-frequency distributions domain is proposed which is robust against geometric distortion. This watermarking is detected by a linear frequency change. The dopplerlet transformation is used to detect the watermark. The chirp signals are used as watermarks and this type of signals is resistant to all stationary filtering methods and exhibits geometrical symmetry. In the two-dimensional Radon-Wigner transformation domain, the chirp signals used as watermarks change only its position in space/spatial-frequency distribution, after applying linear geometrical attack, such as scale rotation and cropping. But the two-dimensional Radon-Wigner transformation needs too much difficult computing. So the image is put into a series of 1D signal by choosing scalable local time windows. The watermark embedded in the dopplerlet transformation domain. The watermark thus generated is invisible and performs well in StirMark test and is robust to geometrical attacks. Compared with other watermarking algorithms, this algorithm is more robust, especially against geometric distortion, while having excellent frequency properties.

Abstract: The forming of the completed aluminium foam sandwich (AFS) panels would determine an improvement in the manufacturing of parts and panels. In this paper the authors have investigated the formability of AFS through experiments. the load versus punch stroke curve and deformation procedures of Aluminium foam sandwiche panels was investigated by performing V-bending experiments. A serious problem encountered in the V-bending was bending-induced large transverse shear deformation of the skin-core layer. It causes the delamination of the AFS. It was found from experimental observations that the large shear defomation progresses rapidly only at the final stage of V-bending. Consequently, the air-bending operation for Aluminium foam sandwiche panels is recommended for suppressing the shear deformation of skin-core layer to within an acceptable limit.

Abstract: The phenol-melamine-urea-formaldehyde (PMUF) cocondensed resin adhesive was prepared by using phenol, urea, melamine and formaldehyde as reactants. It was characterized by 13C NMR and the results indicated that the PMUF could reduce the content of free formaldehyde, and it could make wood-based panel with high water resistance and weatherability. Sodium carbonate (Na2CO3) was able to shorten the curing time by 40% when applied to the plywood process. The addition of Na2CO3 as the curing accelerator of a PMUF had little influence on the bonding strength of waterproof layer and could shorten the hot-press time.

Abstract: On average, each of the 1011 neurons has 1000 synaptic connections with other neurons in reality. In order to simulate a biological genuine model, the stability of a special discrete-time recurrent neural networks model that every neuron only has one input neuron is considered. And a main result is obtained. It provides some theoretical basis for the application.

Abstract: The main effect factors about force of pressure head (FPH) are investigated by numerical simulation for the process of equal-channel angular pressing (ECAP). The influence of extrusion mould design parameters which including corner angler ( ) and corner radius (R), friction condition between mould’s inner wall and multi specimen in the mould, different last location of pressure head and extrusion specimen etc on force of pressure head, are analyzed and discussed by numerical simulation.

Abstract: An analysis has been conducted on the hydraulic bridge of the water hydraulic servo valve with annular clearance between sleeve and spool land as its first hydraulic resistance. Through some formula deductions, the simplified hydraulic bridge is drawn and the relationship between flapper displacement and differential pressure of spool ends, which is demonstrated by the subsequent simulation works, is extracted. By the CFD(computational fluid dynamics) simulation, firstly, the pressure distributions of the flapper face and the fore end face of the nozzle are obtained. Results show that the flapper has an annular area where the existing pressure is negative. Secondly, the relationship between flapper displacement and flow force acting on flapper is also acquired, which is much beneficial to the steady-state and dynamic analysis of the water hydraulic servo valve.

Abstract: MD simulations are carried out on the sI CO2-CH4 mixed hydrates in the constant-NVT and constant-NPT ensembles for the two cases of CO2 occupancy. One is 75% called normal, the other is 87.5%. The simulations results show that the hydrate structure can be maintained both for the two hydrates over the temperature range of 0K to 300K. However, the equilibrium pressure, the potential energy and the MSDs of the atoms in H2O for the higher CO2 ratio hydrates is larger than that of the normal CO2 ratio hydrates, indicating that the normal mixed hydrates is more stable than the higher CO2 occupancy mixed hydrate. These results are consistent with the present experimental results.

Abstract: The leak tightness of control valve may be broken more easily with high flow rate, so this paper considers a control valve of mixed gas as the research object to establish a mathematical model of leakage fault on results of a study on the mechanism of leakage faults. We obtain a method of extracting fault symptom through a simulation test of fault in order to form the foundation for a system of intelligent fault diagnosis and detection (IFDD) for the control valve.

Abstract: As a promising technology that uses electricity to displace petroleum consumption in the vehicle fleet, plug-in hybrid electric vehicle’s performance is due to its control strategy. Traditional hybrid electric vehicle methods, such as charge balance strategy, could not fit it so much. An electric dominant strategy (EDS) is presented for plug-in hybrid electric vehicle. Two parameters, including battery SOC and vehicle velocity are chosen as threshold to coordinate the operation of fuel converter (engine) and energy storage system (batteries). Finally, compared to Charge Balance Strategy (CBS), simulation experiments are carried on electric vehicle platform ADVISOR software. Simulation results show the validity of EDS.