Applied Mechanics and Materials Vols. 44-47

Abstract: An attitude estimation method is presented for a robot using low-cost solid-state inertial sensors. The attitude estimates are obtained from a complementary filter by combining the measurements from the integration of a tri-axis gyro and an aiding system mechanized using a tri-axis accelerometer and a tri-axis magnetometer. The results show that the estimation error is less than 1 degree compare to the reference attitude. It is a simple, yet effective method for attitude estimation, suitable for real-time implementation on a robot.

Abstract: Under the traditional “data Mules” scheme in Wireless Sensor Networks, nodes cannot send the data until the Mules move nearby, which leads to longer data delay. To overcome this shortcoming, this paper improve the “data Under the traditional “data Mules” scheme in Wireless Sensor Networks, nodes cannot send the data until the Mules move nearby, which leads to longer data delay. To overcome this shortcoming, this paper improve the “data Mules” through changing the working area of the Mules and designing its track. According to the mathematical analysis, we can find that reducing the working area of the Mules and its overlapped part can significantly reduced data delay and enhance the equity among sensor nodes. On the basis of this conclusion, a novel thinking and several recommendatory schemes are proposed. The simulation result shows that the new algorithms are significantly superior to traditional one in the aspects of data delay and nodes’ equity.

Abstract: The non-stationary signal is classified into the abrupt singular signal and the gradual singular signal. Because the fault of closed-loop control system is difficult to detect the initial moment when the fault happened, and often there is a more serious consequences once the fault was detected. A new method is proposed which can predict whether the fault happened through the trend signal of a dynamic system. The trend signal was got by the wavelet transform of the detected signal. In order to verify the effectiveness of the method, the leak fault was installed in the process control water tank experiment system, and the signal of liquid level and flow was collected. The gradual leak fault was found through the trend signal in low frequency which was got by the wavelet multi-scale resolution, so the practicability of the proposed method was proved.

Abstract: Power industry is the key field of implementing energy saving and pollutant emission reduction in china, strengthen power energy saving is helpful to establish a resource-saving and environment-friendly society and promote a sustainable development of economic society. This paper synchronizes respective advantages of rough set and neural network, puts forward a prediction model-RSBPNN which uses rough set knowledge reduction method to prune the redundant and neural network to build a forecasting model.

Abstract: This paper proposes a data driven based optimization approach which combines augmented Lagrangian method, MARS with effective data processing. In the approach, an expensive simulation run is required if and only if a nearby data point does not exist in the cumulatively growing database. Over time the database matures and is enriched as more and more optimizations have been performed. MARS is a self-adaptive regression process, which fits in with the multidimensional problems, and uses a modified recursive partitioning strategy to simplify high-dimensional problems into smaller yet highly accurate models. Combining the local response surface of MARS and augmented Lagrangian method improve sequential approximation optimization and reduce simulation times by effective data processing, yet maintain a low computational cost. The approach is applied to a six dimensional test function, a ten dimensional engineering problem and a two dimensional global test functions to demonstrate its feasibility and convergence, and yet some limiting properties.

Abstract: BACnet is a standard data communication protocol designed specifically for building automation and control systems. In BACnet network, each device is modeled as a collection of network-accessible, data structure called “objects”. LabVIEW is a graphical development environment for creating flexible data acquisition, device control and industrial automation applications at minimal cost. In this study, a remote monitoring system based on LabVIEW and BACnet was proposed, in which electromechanical equipment is described by a series of BACnet objects and LabVIEW provides a friendly unified human-computer interface for users. In order to evaluate the feasibility of this system, an experimental model was developed. Due to the characteristic of device-independent, not only can extend the scope of BACnet application, but also make different equipments monitored under the same platform becomes possible.

Abstract: Piezoelectric system shunted with proper negative capacitance in series has low dynamic stiffness. According to frequency characteristic equations of the piezoelectric system, optimal parameters and characteristics of both shunted series structures were deduced and compared theoretically. One is negative-capacitance and resistance in series, and the other is negative-capacitance, resistance and inductance in seires. It presented that high damping characteristic can be obtained at low frequencies when shunted with series negative-capacitance. If proper inductance is included in shunt circuit, effective bandwidth could be extended and the peak of amplitude of response is decreased, what’ more, the stability of this structure is enhanced. This technology can be used in vibration isolators or sensors and the shunt structure including inductance is recommended.

Abstract: Contact deformation experiments in stiffness measurement of spring tubes are studied in this paper. Firstly, Herzian catact theory, Person method and one numerical method are proposed to solve the contact problem based on the character of the contact in spring tube stiffness measurement. Secondly, the normalized pressure profiles and the relationship between non-dimensionalized contact pressure and contact angle are taken to study three contact theories. Lastly, it’s proved by some error compensation experiments that Persson method and the Numerical method are more conformable to solve closely conformal problem.

Abstract: In the new geometrical product specification (GPS), the specification surface model is a new concept in the new-generation geometrical product specification, which is the bridge to connect between nominal model and real model. To solve the problem for generate specification surface model of flatness, a generation method for generate specification surface model of flatness is presented in this paper. Based on the composing of real surface, specification surface model of flatness is classified to three factors: function requirement factor, manufacture process factor, and roughness factor. Aimed at the different characteristic of each factor, generation model for function requirement factor, manufacture process factor, and roughness factor are built respectively. Finally, a plate part is applied to illustrate the proposed generation method for specification surface model of flatness.

Abstract: A piezoelectric nanostage using bridge-type flexure hinge mechanisms is developed. Elastic beam theory was used to analyze the ideal and theoretic displacement amplification ratio and find that their value is mainly influenced by the length of the tilt rod and tilt angle of bridge-type. A multilayer S-type hinge is designed as the prismatic of moving platform. Stiffness and natural frequency model of the whole stage is built and find out that their value is mainly relevant to hinge thickness, tilt angle of bridge-type hinge and length of S-type hinge. Finally, finite element method (FEM) is used to verify the drived model. The errors of the total stiffness and the natural frequency of the stage between FEM and theory analysis are 3.8% and 6.6% respectively, which confirm the predictions of theory analysis.