Guangzhao Cui

An encryption scheme using DNA technology

The vast parallelism, exceptional energy efficiency and extraordinary information density inherent in DNA molecules are being explored for computing, data storage and cryptography. DNA cryptography is a new field of cryptography arising with the research of DNA computing in recent years. In this paper, an encryption scheme is designed by using the technologies of DNA synthesis, PCR amplification and DNA digital coding as well as the theory of traditional cryptography. By applying the special function of primers to PCR amplification, the primers and coding mode are used as the key of the scheme. The traditional encryption method and DNA digital coding are used to preprocess to the plaintext, which can effectively prevent attack from a possible word as PCR primers. Biological difficult issues and cryptography computing difficulties provide a double security safeguards for the scheme. And the security analysis shows that the encryption scheme has high confidential strength. To demonstrate the performance, we present an interesting example to encode and decode message just between specific two persons using the proposed scheme.

Study on Field-Weakening Theory of Brushless DC Motor Based on Phase Advance Method

An analysis is made on the field-weakening effect caused by the phase advance method of Brushless DC motor, and it is indicated that when the phase of the phase current leads the phase back EMF, the transformer EMF in the phase voltage equation can restrain the increase of the phase back EMF, which is equivalent to the field-weakening control of DC motor. This is the primary reason of field-weakening operation for brushless DC motor. Through analysis the paper deduces the equations of brushless DC motor phase current during the phase advance control. The paper also deduces the mathematic expression of phase advance angle by utilizing the concept of rms current, and the calculation method of the phase advance angle is established. The field-weakening control of the phase advance can be realized through the lookup table method. The experiment section provides a field-weakening operation curve of the brushless DC motor. The result is relatively coincide with the theoretic analysis. Also the defects of this method are also discussed at the end of the paper.

A New Numerical Approximation CDD Method Based for Particle Filtering Algorithm Research and Its Applications to TA System

In order to improve the estimation precise of particle filtering algorithm in the state estimation problems of transfer alignment (TA) nonlinear systems for large initial misalignment angles, based on the UKPF theory, this paper developed the CDDPF algorithm which made use of the CDDF algorithm as the proposal distribution. The CDDF Algorithm based on Stirling polynomial interpolation formula is used to generate local linearization approximations to nonlinear system equations and/or measurement equations which can be easy to implement, and whose Cholesky factorization of prediction error variance matrix is employed to guarantee the positive definiteness of the estimation error variance matrix, and the higher-order truncation errors of local linearization are decreased to some degree. The CDDPF algorithm generates a set of particles which can integrate the latest observation information into system state transition density so that expands the overlap region between proposal distribution and posterior density distribution of system states, and can effectively improve the approximation precision of proposal distribution to the system state posterior probabilistic distribution. Finally the simulation experiments on TA nonlinear system for large misalignment angles are implemented with the new CDDPF and UKPF algorithms. The simulation results indicate that, comparing to UKPF algorithm, the CDDPF algorithm has better numerical stability, and its estimation precision is improved obviously.

Research on Invasive Weed Optimization based on the cultural framework

Invasive weed optimization (IWO), which is inspired from the invasive habits of growth of weeds in nature, is a population-based intelligence algorithm. In this paper, the IWO is embedded into cultural framework as a population space of a cultural algorithm (CA), called cultural IWO. CA is mechanisms that incorporate generic knowledge sources obtained during the evolutionary process, which increases the efficiency of searching processes. Here, this situational knowledge and normative knowledge specifically designed according to the IWO evolution population are used to guide the evolution of the population, and they exploit the information sufficiently that the optimum individual carries and speed up the evolutionary process. The performance of the proposed method is evaluated by a number of test functions. Computational results reveal that the algorithm can be efficiently applied to the function optimization.

Construction of Logic Gate Based on Multi-channel Carbon Nanotube Field-Effect Transistors

Carbon nanotubes (CNTs) are one-dimensional nanostructures with many excellent properties that make them the most promising candidates for in steading of silicon materials. In the previous studies, the individual single-walled carbon nanotube (SWCNT) has been extensively used as conduction channels of carbon nanotube field-effect transistors (CNTFETs). However, the single-channel CNTFETs will fail if the only channel breaks down. Therefore, an individual SWCNT as the channel of the CNTFETs have some drawbacks. In this paper, the parallel CNT array with a controllable number and space of SWCNTs is used as the active channels of multi-channel carbon nanotube field-effect transistors (MC-CNTFETs). The logic AND gate and logic OR gate can be fabricated by MC-CNTFETs.

An anti-windup design for linear parameter varation systems with input saturation

It is well known that actuator saturation can introduce severe performance degradation and possible instability in control systems. Using results from the area of linear matrix inequalities, this work extends the antiwindup compensator design method used in LTI systems to a class of linear parameter varation systems. This method is shown to be less conservative than the existing conditions which are based on the circle criterion or the vertex analysis. Moreover, the condition can be expressed as linear matrix inequalities (LMIs) in terms of all the varying parameters and hence can easily be used for LPV system synthesis. The effectiveness of the extended anti-windup control scheme will be demonstrated using a flight control example.

Fault Diagnosis for Induction Motors Using the Wavelet Ridge

Early detection and diagnosis of incipient faults is desirable for online condition assessment, product quality assurance, and improved operational efficiency of induction motors. The characteristic frequency component(CFC) of broken rotor bars is very close to the power frequency component in frequency domain but far less in amplitude, which brings about great difficulty in detecting the broken bars in induction motors. A new method based on wavelet ridge is presented in this paper. As a motor accelerates progressively and the CFC of its broken rotor bars approaches the power frequency component gradually during the motors starting period, the wavelet ridge-based method is adopted to analyze this transient procedure and the CFC is extracted effectively. The influence of power frequency can be eliminated, and the detection accuracy can be greatly improved. Furthermore, experimental results show this is truly a novel but excellent approach for the detection of the broken rotor bars in squirrel-cage induction motors.

Solving Maximum Clique Problems with Microfluidic DNA Computer

Since the Adlemans experimental demonstration of its feasibility, DNA computing has been used to solve various computationally hard problems. In order to improve its reliability and simplify operations, microfluidic chips support an effective way to realize an automatable and universal DNA computer. In this paper we introduce microfluidic logic operators, simple fluidic switches and memory. Furthermore, the use of electronic fluidic control components in microfluidic systems will be demonstrated in such way as to perform dynamic operations and programming. Finally a proposal for an actual fluidic computer will be made which solves the maximum clique problems.

Three Dimensional DNA Self-Assembly Model for the Minimum Vertex Cover Problem

DNA self-assembly technology has brought novel inspiration to the development of DNA computing. Diversified computational models based on DNA self-assembly have been used to solve various NP problems. In this paper, a three-dimensional (3D) DNA self-assembly model is presented to solve the minimum vertex cover problem. With the capacity of DNA molecules in massive parallel computation, the model can simulate a non-deterministic algorithm and solve the problem in polynomial time. Meanwhile, the computation space of the model is O(n3) and the number of distinct tiles is O(1).

Broken Rotor Bar Detection in Induction Motors via Wavelet Ridge

On-line diagnostics of induction motor faults such as broken rotor bars can be accomplished by analyzing the anomalies of motor stator current. This paper presents a novel approach for the detection of the broken rotor bars in induction motors based on wavelet ridge. The characteristic frequency component(CFC) of the broken rotor bars is very close to power frequency in frequency domain but far less in amplitude in steady state, so it is very difficult to detect the broken rotor bars by Fourier Transform. As the CFC of the broken rotor bars approaches power frequency gradually during the motor’s startup process, the wavelet ridge-based method is introduced to analyze this transient procedure and the CFC of the broken rotor bars is extracted effectively. The influence of power frequency can be well eliminated, and the detection accuracy is greatly improved. Experimental results also demonstrate this is truly an excellent approach for the detection of the broken rotor bars.