Applied Mechanics and Materials Vol. 145

Abstract: In this paper， we introduced a system of coherent optical detection with homodyne， which implementing coherent optical communication，our own design based on the principle of coherent optical communication. IN the system, PCI6111E was useed as a data acquisition(DAQ) module. Alice and Bob’s control procedure by their computers under the LabVIEW. The synchronous detection and DAQ were carried out on the system. The signals were processed, displayed and measured. The Experimental results show that by light-synchronization and LabVIEW procedure control, each function module work together in cooperation, include Alice’s acousto-optic modulator and electro-optical modulator, Bob’s data acquisition and phase adjustment by PZT. The coherent optical information could be transitted by Alice and real-time demodulated by Bob.

Abstract: When fabricating laser diode transceiver modules, the coupling efficiency can be improved via a laser hammering process, in which additional, calculated spot welds are performed at key locations within the package in order to compensate for post-weld shift. The present study performs a numerical investigation into the post-weld-shift compensation of a butterfly laser module package incorporating a lensed optical fiber and a laser diode with a central wavelength of 980 nm. In performing the simulations, the deformation of the package components during the welding process is modeled using Marc finite element software. Furthermore, the laser power coupling efficiency is estimated using the commercial Zemax optical design program. It is shown that the numerical predictions for the coupling power in the laser diode transceiver module are in good agreement with the experimental results. The optimal welding sequence which minimizes the post-weld shift of the optical fiber relative to the laser diode is determined. It is shown that the corresponding coupling efficiency is equal to 69%. Finally, it is shown that by performing an optimized laser hammering process, the coupling efficiency can be improved to around 99%.

Abstract: Poyang Lake is the largest freshwater lake in China which located in the Jiangxi province. Flood happened around the lake almost each summer. Remote sensing technology is an effective way to monitoring flood at large scale. This study employs images of Advanced Synthetic Aperture Radar (ASAR) and Landsat Enhance Thematic Mapping Plus (ETM+) to map the flooding area in Poyang Lake. Two ASAR scenes are adopted in this study: one was acquired in flooding period on 1st July 2010, and another was acquired on 9th September 2010 in dry season. Water body is extracted using threshold method, and flood inundation area is detected using the two images. Texture analysis of ASAR data and ETM+ indices are synchronously used in classification. Texture layers of ASAR data are computed, and Normalized Difference Vegetation Index (NDVI) and Modified Normalized Difference Water Index (MNDWI) are also calculated using ETM+ data acquired in the dry season. NDVI and MNDWI derived from ETM+ data are sensitive to soil moisture and vegetation cover., therefore, these two classes are more separable from dry and non-flooded objects than they are in a “ASAR only” classification. The indices derived from ETM+ are used as additional layers for water body classification. Supervised classification is implemented on both ASAR dataset and ASAR+TM data using Maximum Likelihood classifier. Results suggest the classification of ASAR and ETM+ combined data is more homogeneous because the indices reduced speckle-noise, and features can be clearly separated.

Abstract: For general image capture device, it is difficult to obtain an image with every object in focus. To solve the fusion issue of multiple same view point images with different focal settings, a novel image fusion algorithm based on local energy pattern (LGP) is proposed in this paper. Firstly, each focus images is decomposed using discrete wavelet transform (DWT) separately. Secondly, to calculate LGP with the corresponding pixel and its surrounding pixels, then use LGP to compute the new coefficient of the pixel from each transformed images with our proposed weighted fusing rules. The rules use different operations in low-bands coefficients and high-bands coefficients. Finally, the generated image is reconstructed from the new subband coefficients. Moreover, the reconstructed image can represent more detailed for the obtained scene. Experimental results demonstrate that our scheme performs better than the traditional discrete cosine transform (DCT) and discrete wavelet transform (DWT) method in both visual perception and quantitative analysis.

Abstract: TRIZ has been developed over six decades and attracted a great deal of interest in industry and education. It can provide a systematic approach to analyze problems where innovation is needed and to provide strategies and methods to solve the problem. It consists of many tools such as 40 inventive principles and the matrix of contradictions, laws of technical system evolution, substance-field analysis, ARIZ (algorithm of inventive problems solving). In this paper, we focused on engineering innovative education and developed a TRIZ-based systematic method applied to inspire individual student’s interest and learning motivation based on their life experience and capability. The process of this method includes analysis of individual student’s interest and expertise, requirement analysis, confirmation of problem direction, problem definition, selection of TRIZ tools, generation of solutions, evaluation of solutions. A case study including an integrated application with mechanical, electrical and information techniques was illustrated for the method and process. The authors expects this research could provide a reference for engineering innovation education and the method proposed in this paper is general in form to be applied for the other disciplines.

Abstract: The study was done both numerically and experimentally on the heat transfer behaviors of a microchannel heat sink. The solver of numerical simulations (CFD - ACE⁺ software package) was developed by using the finite volume method. This numerical method was performed to simulate for an overall microchannel heat sink, including the channels, substrate, manifolds of channels as well as the covered top wall. Numerical results associated with such kinds of overall microchannel heat sinks are rarely seen in the literatures. For cases done in this study, a heat flux of 9.6 W/cm² was achieved for the microchannel heat sink having the inlet temperature of 25 °C and mass flow rate of 0.4 g/s with the uniform surface temperature of bottom wall of the substrate of 50 °C; besides, the maximum heat transfer effectiveness of this device reached 94.4%. Moreover, in this study, when the mass flow rate increases, the outlet temperature decreases; however, as the mass flow rate increases, the heat flux of this heat sink increases also. In addition, the results obtained from the numerical analyses were in good agreement with those obtained from the experiments as well as those from the literatures, with the maximum discrepancies of the heat fluxes estimated to be less than 6 %.

Abstract: In this work computational mass transfer was investigated based on computational fluid dynamics (CFD) in single-phase flow with the open-source software, OpenFOAM. OpenFOAM supplied a kind of open structure, which made it convenient that a suitable physical model was added with CFD equations according to the problem. In order to compute mass transfer with fluid flow, the component conservation equation was listed with Navier-Stokes equations. With the equations, a pipe flow with mass transfer was simulated on the assumption that the fluid density is constant by our solver which was developed based on OpenFOAM. By the simulation, the pressure, velocity and component mass fraction can be easily obtained at different time and position, which is very important for the analysis of equipments in chemical engineering. Although some details need to be considered such as the change of density with composition, the boundary conditions and the affect of complex shape, computational mass transfer with OpenFOAM has showed very large potential to be applied in industry.

Abstract: In recent years, the usage pattern of the Web has been undergoing dramatic changes. The traditional definition of the Web, “a system of interlinked hyper-text documents”, can no longer describe the situation accurately today. Instead, users want to interact with Web resources and even want to create their own Web resources that can interact with others. This is what we call “Web 2.0”, a new Web that is both read-able and write-able. However, considering Web-based services around us: the calendar services, the traveling services, and the messaging services, etc., one can draw a conclusion that what Web users nowadays expect from the Web are not only contents and interactions but also services. To meet this expectation, a read/write/execute-able Web is demanded. In this paper, new technologies for building such a Web are proposed. A virtual browsing environment is employed to transform existing Web resources into executable services. Furthermore, an HTML-to-XML annotation/transformation technology is integrated into the virtual browsing environment to form the data model part. With these technologies, the Web will be transformed into “a system of interlinked services.”

Abstract: Fuzzy time series methods have been applied to social forecasting for over a decade; however, little research has been done to discuss the decision of an optimal fuzzy model for time series. In the paper, we evaluate the forecasting performance of three listed multivariate fuzzy models by comparing forecasting MSE of model. The data obtained from AEROM, Taiwan, includes Taiwan’s exports and foreign exchange rate for models’ test. The algorithm for predictive value of the models has three-stage computation procedure: First, calibrating time series correlation, deciding window base and interval partition; second, solving the static forecasting value of each model; third, comparing the dynamic parameter to impact of the forecasting error. The empirical results indicate that increasing predictor variables has no significant effect on predictive performance of the models; increasing length of interval would not improve the prediction performance of the models. Moreover, Fuzzy model is better for short-term time series forecasting. For forecasting purpose, Heuristic model has best forecasting performance among three fuzzy models. The findings of the paper represent a significant contribution to our understanding of the applicability of fuzzy models to predict.

Abstract: nformation security has become a major issue in recent years, as new ways of information exchange arise due to the rapid development of computing, communication and internet technologies. We propose the image communication systems to secure the information by using a steganographic system and empirical mode decomposition method. The concealed message between the sender and receiver is important in the steganographic system. The encrypted message is further decomposed by using the empirical mode decomposition. The information is transmitted via the public channel and secure channel. At the receiver side the weak message can be retrieved back effectively. The retrieved message carries the same characteristics as the original message. Simulation results have confirmed that this combination model is highly robust against various signal processing operations and geometric attacks. The system increases the security of information data given a variety of constraints and conditions. Our methods have been proven effective for application in various fields which require secure communication, such as mobile telephone, internet and others. By means of this method, researchers can better understand the characteristics of the secure communication.