Earticle

To the existing real-time operating systems implemented by software, it is hard to continually enhance their real-time performance by simply improving their scheduling algorithms. New scheduling algorithms of μC/OS-II real-time operating systems and their hardware implementation are shown in this paper. They breakthrough the limit of the number of total task, and hardware task scheduler was used to select tasks from ready list instead of the original ready table, improving the efficiency and maintaining the correctness of the real-time system. This system design adopted VHDL hardware description language and implemented and simulated in ISE 8.2. Based on the result, new task scheduling algorithms and hardware scheduler decrease the cost of hardware logic and spending of running time, while the new task management and TCB data structure keep the correctness of the original software version.

Spread spectrum technique becomes one of the most important communication techniques in the recent decades. It provides high security, in addition to its resistance to the various interference and fading types. One of the most important parameter in the spreading process is the spreading code used in the spreading process, especially in the direct sequence spread spectrum. Recently, many researches focused on the chaotic codes, due to its attractive security properties, in addition to its availability to generate a huge number of spreading codes. This property is very useful in the multi-access applications. However, as the number of the MAI is increased, the performance of the chaotic codes is degraded. This paper presents a new method to generate a set of orthogonal self-balanced chaotic codes. The results show that the presented method generates a set of chaotic codes with correlation properties much better than the traditional chaotic code. The results show also that the BER performance of the presented orthogonal chaotic codes is superior and outperforming the BER performance of the traditional chaotic codes in addition to the PN sequences.

Wind power prediction of wind farm plays a decisive role in stable electric power system operation.The BP neural network’s basic principle was introduced, and the numerical weather prediction (NWP) data and power data of wind farm as the training data of BP neural network was selected and trained; a linear regression model about the sample prediction error was presented, which considers the coupling relationship between the individual sample prediction error, the individual sample prediction error of BP neural network was selected as the regression factor, the individual sample prediction result of BP neural network was modified. As the modified prediction results performing, the prediction algorithm of short-term wind power considering the sample prediction error correction, has good self-learning and adaptive ability of BP neural network. It has overcome the shortcoming that the BP neural network has only considered the overall the prediction error of training samples, but without considered the prediction error of individual samples. This has further improved the prediction accuracy of BP neural network.

In recent years, outsourcing large amount of data in cloud and how to manage the data raises many challenges with respect to privacy. The concerns of privacy can be addressed if cloud users encrypt the data deployed in the cloud. Among the various cryptographic encryption schemes, homomorphic scheme allow to perform meaningful computations on encrypted data. In this context, the research deals with homomorphic encryption scheme for maintaining privacy and security in cloud by detecting the error incurred while transferring data using RSA cryptosystem. Three types omomorphic error detection schemes proved that preserving privacy seems to be efficient using Map-Reduce Model.

The multi- pad circular guide hydrostatic bearing of heavy-duty CNC machine is taken as the research object. Based on the lubrication properties of the heavy hydrostatic bearing, viscosity-temperature equation of interstitial fluid is established in various viscosities. In accordance with factory actual production, the fluid critical from laminar to turbulent is calculated by finite volume method. The inner flow field of hydrostatic bearing is simulated, when the rotating speed of workbench is 6r/min at different flow. The simulation results reveal flow distribution low and verify the reliability of the calculation. The results show that, the transition critical inlet fluid flow from laminar to turbulent of fluid in hydrostatic bearing is 22L/min. Through the above analysis and research, reveals the flow rule of the hydrostatic bearing oil film bearing gap, provides a theoretical basis for actual hydrostatic bearing for engineering structural optimization design.

The objectives of this study were to investigate the effect on the casein concentration detected by the method of scattered transmitted ratio (STR) at different structure parameters and wavelength. Detection experiments were performed at four kinds of testing devices and five kinds’ different wavelength lasers. All measurements had good reproducibility. Both structure parameters and wavelength had a significant effect on the measured effective concentration of the casein. The design of four different structure of the testing device was measured and analyzed. And the structure parameter of the testing device was determined in this paper. Compared measured value with standard value, it was determined by more effective wavelength. The accuracy of the method of scattered transmitted ratio, evaluated through the correlation coefficient (R) and the root mean square error of prediction (RMSEP) for five kinds different wavelength lasers. Overall, the results of this study suggest that the suitable structure parameter was experimented for testing devices.

Time-varying channel estimation is an important activity in next generation wireless communication. Channel estimation is required mainly for the significant signal processing operation in multiple input multiple output (MIMO)-orthogonal frequency division multiplexing (OFDM) systems such as precoder designing at transmitter & relay and relay selection scheme in cooperative communication system. In this paper we investigate and compare various efficient channel estimation schemes for OFDM system. In this paper the channel estimation techniques based on block type Pilot arrangement for OFDM system are investigated. Finally, the discrete Fourier transform (DFT) based channel estimation technique is performed which gives better performance over least square(LS) and minimum mean square error(MMSE) based channel estimation. The bit error rate (BER) of DFT based channel estimation is less than the BER of LS and MMSE based channel estimation with same signal to noise ratio (SNR).

Dalvik virtual machine’s performance determines the performance of the Android platform. And each Dalvik virtual machine process is a Linux process, and each Dalvik virtual machine thread is a Linux thread. This paper analyses and researches process model of Android Dalvik virtual machine. Through research and analysis the role of Zygote in startup process of Dalvik virtual machine and the Zygote boot process, we analyze the relationship between the processes of the operating system and the Dalvik processes and we study the relationship between the Dalvik virtual machine processes. It answers the question why a Dalvik virtual machine process is actually a process of Linux.

Internet public opinion reflects the trend of public opinion in all sectors of society directly. It can affect the harmony and stability of society. Therefore reducing the incidence of adverse events and improving the ability to deal with Internet public opinion have become an important issue that the government needs to solve. Based on the existing literature，the paper firstly analyzes the propagation rule of Internet public opinion and its features. Then it uses the system dynamics to have an analysis of the influencing factors of ecological dissemination system about internet public opinion. What’s more, it takes a qualitative analysis to analyze the relationship between the factors through the causal analysis diagrams and it establishes the stock flow diagram of the factors. Lastly, it has a simulation analysis for the model in order to present the suggestions to control the dissemination of Internet public opinion positively..