Advanced Materials Research Vols. 317-319

Abstract: It is the first time to study the consistent difference scheme of pressure equation and Neumann boundary conditions on two-dimensional non-staggered grid by using two-dimensional axisymmetric inhomogeneous equation for steady flow. The result of computing the fluid field of jet pump by using the Monte Carlo method is conforming approximately to the actual flow which is measured by the laser Doppler anemometry. The Monte Carlo simulation of flow field is therefore practical and feasible.

Abstract: As a new dynamic reactive compensation devices, static synchronous compensator (STATCOM) has better reactive power compensation effect such as small in size, capacity, continuous adjusting, fast response and economic performance compared with SVC. It is suitable to be used in large-scale wind farm to improve the voltage stability of wind power system. With the help of ideas and methods in conventional electric power system to calculate the two-dimensional parameter bifurcation boundary, the node voltage two-dimensional saddle-node bifurcation boundary of wind power system was calculated by using wind farm active power inject(Pin ),STATCOM parameters KMdc and Vrefdc as bifurcation control parameters. And on the basis of this analysis, the laws of wind power system voltage stability affected by active power and STATCOM parameters were obtained.

Abstract: This paper presents analytical approximate solutions for the initial post-buckling deformation of the sandwich beams including transverse shear. The approximate procedure is based on the nonlinear beam equation (with transverse shear included), by combining the Newton’s method with the method of harmonic balance, we establish analytical approximations to deformation of the sandwich beams. Illustrative examples are presented for a few typical sandwich construction configurations, and it is shown that these approximate solutions are excellent agreement with the “reference” solutions.

Abstract: In this paper,a novel two-port bandstop filter based on coaxial cavity is proposed,which is different to the conventional bandstop filters based on microstrip or stripline.The design and simulated results show that the novel bandstop filter has a good performance,which are stopband rejection less than -80dB from 1920MHz to 1980MHz, return loss less than -20dB and insert loss more than -2 dB in two widebands from 1700MHz to 1910MHz and 1990MHz to 2200MHz,respectively. Moreover,the measured results have good agreement with simulated results.

Abstract: Increasing number of network applications require authentication of the user's identity which is the first step to ensure security. This paper analyzes the security performance of one proposed remote two-factor user authentication scheme and discusses the attacks it suffers. Then we propose an improved scheme based on the RSA cryptography and one-way secure hash function to avoid the attacks it suffers. After that we prove the proposed scheme is autonomous and effective for both sides in the authentication process.

Abstract: According to the various multidentate heteroatomic ligands(based oxygen,nitrogen, phosphorus,mixed N and P,mixed N and S donors, composition, activity and overall selectivity to 1-hexene of chromium-based trimerization catalysts were reviewed. Commercial application foreground of these catalyst systems was also expected.It was found that effect of ligand structure on activity and selectivity for ethylene trimerization was the most predominant.The PNP （(Ph2P)2N(cyclopentyl)）ligands were prepared using inexpensive reagents and gave the corresponding complexes in high yields.Due to the inexpensive ligands coupled with low MAO （methyl aluminum oxide）requirements and high activity and selectivity of these systems, this has positive implication for a commercial process to 1-hexene.

Abstract: The design and implementation of DRO with isolated structure are presented. The simulation result and measured result show that the DRO with isolated structure is feasible and the indicators are satisfied. Based on the feasible fact, an approach of cavity miniaturization of DRO is provided. The design shows that such method could effectively reduce the spatial dimensions of DRO and achieve the purpose of miniaturization.

Abstract: In order to fulfill the need of minimizing sensor cost and characterizing sensor agricultural application for the promising wireless sensor network technology, this paper evaluates a pair of SMC sensors (EC-5 and 5TE) under some laboratory experiments which is based on a standardized sensor characterization methodology using liquid medium with a known standard water content. The results showed that the electronics of the EC-5 and the 5TE are sensitive to temperature, electric conductivity and pH variations and it is concluded that both the 5TE sensor and the EC-5 sensor are suitable for wireless network applications. Moreover, the results of this paper also suggested that the effects of temperature, electric conductivity and pH on the sensor measurement ability have to be compensated using the appropriate correction functions. Future work will focus on the field application of these sensors and their correction effects in more detail to derive more general correction functions.

Abstract: Ultrahigh pressure water-jet machine tool with multi-cutter can boost efficiency when dealing with large and complex planar workpieces. This paper focuses on the coordinated control of multi-cutter, brings forward a system frame of coordinated control of multi-cutter based on the ultrahigh pressure water-jet machine tool and having resolved the issues of compartmentalizing the interference zone and the instruction for fast moving. By using the Microsoft Visual C++ 6.0 development kits to develop an application to automatically modify the NC code and programming the PLC embedded in FAGOR NC system, it has achieved the coordinated control of multi-cutter.

Abstract: Permanent-Magnet Synchronous Motor is a multivariable nonlinear system with over-coupling and very sensible to outer disturbance and inner perturbance. To improve robustness of the servo systems, the method of Sliding Mode Control is introduced and a simple controller based on the algorithm of sliding mode control is developed in this paper. The simulation and experiment results demonstrate that the sliding mode controller designed is feasible and valid. It can offer a valid approach to the implementation of Permanent-Magnet Synchronous Motor servo systems.