Reconstructing non-ideal-bordered field by simple self-correlative algebraic reconstruction technique

A new algorithm for iterative reconstruction is suggested.It is named simple self-correlative algebraic reconstruction technique (SSART).With numerical simulation experiments,SSART was applied in reconstructing a non-ideal-bordered field in order to test its reconstructive effect.For contrast,three current representative algebraic reconstruction(ARTs) including basic ART,simultaneous ART (SART) and modified SART (MSART) were simulated simultaneously.The calculated results and reconstructive accuracy are discussed with three kinds of error indexes,namely mean-square error (MSE),absolute value error (AVE) and peak error (PE).As the results,the indexes of reconstructive accuracy are much improved by the proposed SSART.The MSE and PE have been decreased by 63.6% on the order of magnitude 10-4 and 88.9% on the order of magnitude 0-2,respectively,compared to that of ART.It is concluded that SSART is one of the most super iterative reconstructing techniques.

Iteration compensation of inside fringe in reconstructing field with an opaque object

An algorithm is suggested to compensate the inside fringe in reconstruction field for the iterative distortion when an opaque object exists.With numerical simulation, a model field with an opaque object is reconstructed by a new algebraic reconstructing technique (ART),named Simple Self-correlative ART (SSART),which shows that the inside fringe of the reconstructed field is quite irregular with serious profile distortion.An algorithm of the compensation of the inside fringe for the iterative distortion is suggested and applied to the reconstruction of the field.It is found that the reconstructed field is quite similar to the model.With the compensation algorithm, the field with an opaque object in can be accurately reconstructed by SSART.

A PHEMT Based Wideband LNA for Wireless Applications

This work is about the development of a super low noise amplifier with minimum power consumption and high gain for several wireless applications.The amplifier operates at frequency bands of 0.9-2.4 GHz and can be used in many applications like Wireless local area network(WLAN),WiFi,Bluetooth,ZigBee and Global System for mobile communications(GSM).This new design can be employed for the IEEE 802.15.4 standard in industrial,scientific and medical(ISM) Band.The enhancement mode pseudomorphic high electron mobility transistor PHEMT is used here due to its high linearity,better performance and less noisy operation.The common source inductive degeneration method is employed here to enhance the gain of amplifier.The amplifier produces a gain of more than 17 dB and noise figure of about 0.5 dB.The lower values of S11 and S22 reflect the accuracy of impedance matching network placed at the input and output sides of amplifier.Agilent Advance Design System(ADS) is used for the design and simulation purpose.Further the layout of design is developed on the FR4 substrate.

An Improved Empirical Mode Decomposition for Power Analysis Attack

Correlation power analysis(CPA) has become a successful attack method about crypto-graphic hardware to recover the secret keys. However, the noise influence caused by the random process interrupts(RPIs) becomes an important factor of the power analysis attack efficiency, which will cost more traces or attack time. To address the issue, an improved method about empirical mode decomposition(EMD) was proposed. Instead of restructuring the decomposed signals of intrinsic mode functions(IMFs), we extract a certain intrinsic mode function(IMF) as new feature signal for CPA attack. Meantime, a new attack assessment is proposed to compare the attack effectiveness of different methods. The experiment shows that our method has more excellent performance on CPA than others. The first and the second IMF can be chosen as two optimal feature signals in CPA. In the new method, the signals of the first IMF increase peak visibility by 64% than those of the tradition EMD method in the situation of non-noise. On the condition of different noise interference, the orders of attack efficiencies are also same. With external noise interference, the attack effect of the first IMF based on noise with 15dB is the best.

Anomalous Transport Characteristics of High Temperature Superconductors and Josephson Currents

The transport characteristics of high temperature superconductor current and Josephson current is inves-tigated in the framework of the modified time-dependent Ginzburg-Landau model and the Lawrence-Doniach model.We evaluated the vortex equation and found that the signs of the high temperature superconductor current and theJosephson current can reverse. Some explicit expressions for different cases are derived, which accord with experimentaldata.

Study of Properties in Superconducting Nanowires

We consider a simple approach of standard Ginzburg-Landan free-energy functional for a wire to study the properties of superconducting nanowires, and analyze the problem of quantum and thermally activated phase slips. In such systems one can consider a possibility for phase slips to be created not only due to thermal but also due to quantum fluctuations of a superconducting order parameter. We obtain some expressions of the free energy, the entropy, the specific heat and the bias current, respectively. The bias current I is a function of the temperature and the length of superconducting nanowires, and has a quantum phase slip. We obtain the stochastic dynamics of superconductiveresistive switching in hysteretic current-biased superconducting nanowires undergoing phase-slip fluctuations, and obtain the distribution of switching currents. Our results can be verified in modern experiments with superconducting nanowires.

Critical Temperature Characteristics of Layered High-Temperature Superconductor Under Pressure

We consider a Ginzburg-Landau modified model of layered high-temperature superconductor under pressure. We have theoretically studied the relation between the pressure and the temperature of layered high-temperature superconductor. If the pressure is not a constant, we have a relation of quadratic equation between the pressure and the temperature of layered high-temperature superconductor. In a special case, we find the critical temperature decreases with further increasing pressure. In another special ease, the critical temperature increases with further increasing pressure.

Phase separations in graded-indium content InGaN/GaN multiple quantum wells and its function to high quantum efficiency

Phase separations have been studied for graded-indium content In_xGa_（1-x）N/GaN multiple quantum wells（MQWs） with different indium contents by means of photoluminescence（PL）,cathodeluminescence（CL） and time-resolved PL（TRPL） techniques.Besides the main emission peaks,all samples show another 2 peaks at the high and low energy parts of the main peaks in PL when excited at 10 K.CL images show a clear contrast for 3 samples,which indicates an increasing phase separation with increasing indium content.TRPL spectra at 15 K of the main emissions show an increasing delay of rising time with indium content,which means a carrier transferring from low indium content structures to high indium content structures.