Advanced Materials Research Vols. 468-471

Abstract: In this paper, an adaptive control scheme is proposed for the uncertain flight control system of the helicopter with fault in vertical flight. The controller is designed using sliding mode theory and adaptive technology. In the controller, the nonlinear function is brought in, which can enlarge the small errors, and saturate the large errors. And it can make sure the good transient performances and stability of the helicopter flight control system. Finally, the simulation results of the nonlinear helicopter flight system illustrate the effectiveness and feasibility of the proposed scheme in the paper.

Abstract: A coarse and fine combined fast search and auto-focusing algorithm was suggested in this paper. This method can automatically search and find the focal plane by evaluating the image definition. The Krisch operator based edge energy function was used as the big-step coarse focusing, and then the wavelet transform based image definition evaluation function, which is sensitivity to the variation in image definition, was used to realize the small-step fine focusing in a narrow range. The un-uniform sampling function of the focusing area selection used in this method greatly reduces the workload and the required time for the data processing. The experimental results indicate that this algorithm can satisfy the requirement of the optical measure equipment for the image focusing.

Abstract: At present, ship pipeline leakage has become a great hidden risk of safe navigation and environmental pollution, but piping detecting technology mostly focuses on long-distance oil and gas pipeline, and does a little on the complicated pipeline system, for example, ship pipeline system. The frequently-used leakage detecting of negative pressure wave method, because the frequent adjustable pump or reset valve of ship pipeline system will also produce the negative pressure wave, may easily fail to report or even misreport. In order to monitor ship pipeline leakage effectively and greatly reduce fault alarm rate and missing alarm rate, SOM network (self-organizing feature map neural network) had been used to identify leakage from different working conditions. At first, the waveform characteristics of pressure and flow signals were analyzed by kurtosis calculating to obtain condition eigenvectors. From data sampling in terms of pipe working conditions, learning samples were obtained. Accordingly, the nonlinear mapping between SOM neural network inputs and outputs were well established via training. Afterwards, ship piping leakage was detected based on input eigenve

Abstract: We present the preparation, structure and physical properties of CoNb₂O₆ ceramics using spark plasma sintering technique. Magnetic data reveal the two antiferromagnetic transitions at 2.9 and 2 K. Microwave measurements gives ε_{r = 23.5 and a loss tangent of 29×10-3.}

Abstract: Intense electromagnetic interference while drilling prevents traditional analog phase sensitive detection (APSD) from correctly acquiring electromagnetic wave signal of logging while drilling (LWD). A digital phase sensitive detection (DPSD) utilizes high-performance floating-point DSP and FPGA to separately process real part and imaginary part of the acquired logging signal, changes traditional calculating method, improves processing speed and calculating precision. The programmable technique used can fully utilize logging information, simplify control logic, improve precision of timing control and measuring precision. Discussed are the principle, characteristics, implement of circuit and analysis of experimental data. Testing result shows that the DPSD may utilize logging information effectively and optimize the LWD system.

Abstract: With the development of information technology, such as CAD, CAPP and CAM, assembly process, which accounts for large amount of time and cost of manufacturing, to be included in virtual manufacturing system is urgently required. According to the principle that the sequence and path in assembly and disassembly process are reversible, the assembly path can be obtained on the basis of assembly constraints analysis and information model building through optimized and reversed. The method of assembly path planning presented in this paper can effectively reduce computational complexity and improve planning efficiency, whose correctness and efficiency is proven by an application example.

Abstract: This paper adopts the allowable stress and limit state methods of Chinese and European crane structure design standards(GB3811-2008 and FEM-1998 ), and illustrates correspondingly in detail the computing means on the overall checking of strength, static and dynamics stiffness, buckling of bar and plate, and fatigue. Taking a real crane as an example, according to the above three specifications, it designs the crane’s metal structure again, checks all aspects and guarantees the strength, buckling and fatigue indexes all reach 90 percent of the permissions, then comparative analyzes the new design parameters and checking indicators, combining failure probability obtained by PDS. It provides helpful and reference value for understanding the transition from the allowable stress to limit state method in design standards and the differences of theirs’ at home and abroad.

Abstract: One variety of durum wheat (Triticum durum L.), ‘Longfu 30’, was choosen to study the allelopathic effects of seed germination extracts on other plants. The allelopathic effects of different polarity extracts were measured in terms of germination rate and germination speed on a test cucumber variety ‘Jinyou No.2’ (Cucumis sativus L.), and the allelopathic substance in chloroform extract was preliminarily separated with HSCCC and determined by GC-MS. The results showed that the allelopathy of wheat seed germination extracts varied with the polarity of solvent, and the substance in chloroform phase was the most active and showed a significantly inhibitory effect on seed germination of cucumber by 80.7% under Petri dish culture. The major allelopathic substance in wheat seed germination extracts were phenol, amine, piperazine, alcohols, esters and ketones.

Abstract: The valve ball is one of the most important parts in the ball valve. Lapping is a very important pressing method in valve ball’s production. A valve ball's lapping instrument with a cup shaped cutter, and build the lapping mathematics model is studied in this paper. To build the mathematical of valve ball, theoretical analysis and the simulation, the results proven that some key parameters could be properly controlled to improve the lapping process.

Abstract: In this paper, a novel mm frequency SIW antenna is presented, which is a planar taper slot antenna owns function of high gain advantage. The max gain of the antenna is 7 dB. The frequency width of the antenna is 10 GHz.