In order to investigate effect of the gain coefficient and core-shell ratio on surface plasmon resonance of nanoparticles, the Au nanostructure with gain medium in the core was numerically simulated. The results show that as gain coefficient of material increases to reach the threshold, the scattering cross section is about 2×105 times of the value of the case without gain. Meanwhile, the absorption cross section turns to negative with the extinction cross section close to zero simultaneously. The electric intensity enhances about 185 times of the case without gain, and the resonant bandwidth decreases from 60 nm to 1 nm. With the core-shell ratio enhanced, both of the extinction peak and the absorption peak are red-shifted. Therefore, the related results provide theoretical reference and technique support on the application of gain medium in surface plasmon resonance.
Based on Kronig-Penney model, the changing tendency of band gap or a particular level with the volume deformation in crystalline materials was derived. Based on the tendency, the zero-phonon charge-transfer (CT) energy Ezp was deduced to be decreased when the size of Y2 O3 :Eu3 + phosphor decreases in nano-scale. In addition, the rigidity decrease of lattice environment in Y2 O3 :Eu3 + nano-phosphor leads to the enlargement of CT state coordinate offset, an optical center would reach a higher vibration level Evib in CT excitation. The increasing magnitude in Evib is smaller than the decreasing magnitude of Ezp when the size of Y2 O3 :Eu3 + phosphor decreases in nano-scale. As a result, the CT energy ECT is decreased, and the CT excitation spectrum shifts to lower energy.
The basic principles of photoacoustic spectroscopy were introduced. A portable photoacoustic spectroscopy system Transport-X, which can detect a series of DGA products developed by Kelman Company, was applied to detect CO and SO2 of SF6 decomposition. The filter of SO2 was selected according to the HITRAN2004 database as a result of the incapable of detecting SO2 of Transport-X. One of the filters of Kelman was replaced by the new selected SO2 filter. Calibration experiments of different concentrations of CO and SO2 were carried out and the results showed that photoacoustic signal and the concentration have a perfect linear relationship and the detection limit for CO and SO2 are 4.063 ppm and 9.540 ppm.
Single image dehazing is an ill-posed problem of the image degradation model. Many researches focused on the problem in estimating the atmospheric light intensity and the medium transmission. A simple but effective interval estimation method was proposed to quickly remove haze from a single input image in a new perspective. Firstly, scope of interval estimation was reduced by discussing on atmospheric light intensity and medium transmission. Secondly, the fast joint bilateral filtering and median filtering were adopted to optimize the edge regions of medium transmission. And by the absolute value of the difference of atmospheric light and dark channel, the bright areas can be judged and amended. Finally, the tone mapping was used to refine the performance of the restored image. Experimental results demonstrate that the proposed method can clearly improve the computational speed and obtain a better restoration effect compared to some state-of-the-art methods.
In order to improve the classification accuracy of hyperspectral image data, reduce dependence on large number of data sets, an improved method was proposed for feature extraction of hyperspectral data based on the weighted fuzzy C means algorithm. The approach is an extension of previous approach-prototype space feature extraction. Each feature with different weights in terms of weighted fuzzy C means algorithm to ensure the features contain more information after extracted. Experiment results show that compared to results obtained from approach prototype spatial feature extraction method, this method has a stability of data set and higher classification accuracy when extracted a small number of features, which greatly reduces the dependence on the number of data sets of samples, and improves the efficiency of the prototype spatial characteristics method.
In order to improve the performance of image enhancement, effectively preserve original image details, an image enhancement method using multi-scale gray-level transformation was presented. The original image was decomposed into multi-scale layers using gradient domain based recursive bilateral filtering. Based on wavelet transform, the subcinctures of decomposed layers were transformed respectively in the gray-level. The overall image enhancement was realized based on the enhancement results of decomposed layers, which were reconstituted with the transformed subcinctures. Compared with histogram equalization and gray-level transformation, the proposed method performed better in image enhancement, and preserved details. The performance of the enhancement results was evaluated by the objective indicator. The experimental results show that the proposed method has excellent effect, simple structure and lower computational complexity.
Based on the linear electro-optic effect with quasi-phase matching in periodically poled LiNbO3 crystal, the evolution laws of the output laser polarization with the applied electric field were explored by means of Poincare sphere theory, under different duty ratio of the crystal and temperature. It is found that the evolution of the output laser polarization is very sensitive to the applied electric field E0, the crystal duty ratio D and the crystal temperature T0. With T0 fixed at 273 K, and D fixed at 0.25, 0.5 and 0.75, the output polarization appears periodical evolution with the increase of E0. If D is 0.5, and T0 are 263 K, 293 K and 313 K, evolution of the laser polarization show irregular. Arbitrary polarized light can be performed by reasonable selection of a certain applied electric field, duty ratio and temperature. These results are helpful in optimizing design of the polarization controller based on PPLN crystal.
The wavelet transform for signal analysis was promoted to research of the non-classical quantum properties of the photon-added coherent state by means of quantum transformation theory and the technique of integration within an ordered product of operators. The result shows that the wavelet transform spectra of the photon-added coherent states not only exhibits the common behaviors, which are characteristics of the wavelet transformation, but also disappears its symmetry and arises some new crests gradually with the increasing value of the number of added photons.
Spin squeezing is an important concept in quantum mechanics, which was found closely related with the criteria of entanglement in quantum information. A theoretical scheme for generating spin squeezing state in spinor Bose-Einstein condensate (SBEC) with a laser pulse was put forward. Using the single-mode approximation, the time-dependent wave function of SBEC were obtained, and the analytical expressions of the squeezed angle and spin squeezing parameter were obtained. By investigating spin squeezing in SBEC, it’s found that the spin squeezed state with more squeezing can be generated by increasing coupling strength between laser pulse and the condensate.
Geometric quantum discord as well as dense coding capacity were investigated in a model where two superconducting charge qubits were coupled with a Josephson junction. The influence of the initial mean photon number, relative phase and amplitude of the two qubits on the time evolution of geometric quantum discord and the dense coding capacity was discussed. The results show that the initial mean photon number, relative phase and amplitude of two qubits may play an important role in the evolution of geometric quantum discord and the dense coding capacity. Importantly, the dense coding channel capacity can be increased via changing the relative phases.
Recently, quantum game has attracted more and more attention. Most of the studies focused on the advantages of quantum game in the case of the maximally entangled states and the certain quantum operations. In practice, the particles may not in the maximally entangled state and there are some quantum operation deviations. For this, the two factors are considered in CHSH game. It is found that when particles are in general entangled quantum states, the probability of winning for quantum strategy P is not always greater than that for classical strategy Pc, therefore suitable quantum operations should be chosen to satisfy P>Pc. The maximum of the probability of winning for quantum strategy Pmax increases with the degree of entanglement of quantum states. For some angle regions that near the angle corresponding to Pmax, P change slightly. All these results provide theoretical guidance for quantum games.
In the traditional Chord-based botnets, all adjacent nodes need to maintain the periodic communication so that the routing table of every node keeps accurate and efficient. The periodic communication behavior affects the robustness of the traditional Chord-based botnets. For the aforementioned problems, a Chord-based quantum botnet control platform based on the improved B92 protocol was constructed. The simulation analysis showed that the infected hosts in the Chord-based quantum botnet can more quickly be increased, and can maintain a larger scale compared with the traditional Chord-based botnet. Meanwhile, the Chord-based quantum botnet can reduce the hazards of the periodic communication behavior on botnet control system and has better robustness and stability.
The quantum dot array consisting of a uniform and orderly quantum dot based on one-dimensional linear real space lattice of tight-binding model was investigated, and the evolution operator was used to transfer a single qubit in a spin chain of quantum dot array. That is to say, the information of one-qubit is transferred to the terminal state from the multi-particle state |110203…0N-10N> of initiating terminal of the quantum dot array |010203…0N-11N> with the evolution operator exp(-iλt?H). The probability was calculated. The results show that it is possible that the information of one-qubit is transferred from the first qubit of initiating terminal of the multi-particle state |110203…0N-10N> to the N qubit of the end of the terminal state |010203…0N-11N>.
In order to make the computing system with low power consumption and fault-tolerant ability, a fault-tolerant universal shift register was designed using reversible logic. A new reversible fault-tolerant gate named Parity preserving D flip- flop gate (PP- DFG) was proposed. Some circuits such as register and multiplexer were designed using PP- DFG and existing gates. Based on the above modules, the fault-tolerant reversible universal shift register was built. It was modeled in Verilog hardware description language for verification. Simulation results indicate that its logic structure is correct. Compared with the existing ones in terms of quantum cost, delay and garbage outputs, the proposed circuit not only supports fault-tolerant but also has 16%~48% performance improvement. This circuit can be used as an important storage element applied in future low-power computing system.
The propagation properties of two orthogonal polarized center-coincidence Hermite-Gaussian (HG) beams were investigated in strongly nonlocal medium with exponential-decay response using variational method. The evolutional equations for the parameters of HG beams and one critical power Pc were obtained. The HG spatial optical solitons come into being when the two incidental powers are both equal to the critical power. However, when two beams are incident with total power 2Pc while the two incident powers are not equal, they form HG breathers. By means of numerical simulation, the beam with low order may have approximate soliton solution. When the orders of beam are higher than the third, there are no soliton solutions. By comparing variational solution with numerical solution, it’s found that when the order of beams are under the third the variational solutions can well reveal the propagation properties of orthogonal polarization center-coincidence double HG beams in strongly nonlocal medium with exponential-decay response.
The non-uniform illumination of high-throughput microfluidic qPCR is significant for improving the precision of DNA quantitative results. According to the theoretical principle of qPCR, theoretical analysis was presented. The analysis focused on the deviation of cycle threshold (Ct) resulting from non-uniform illumination. On the basis, the deviation formula of Ct caused by non-uniform illumination was proposed. Moreover, the requirement of excitation light was determined, and the relative standard deviation of excitation should be less than 11.56%. Then, according to the characteristics of microfluidic chip and the requirement of the excitation light uniformity, an illumination system based on light pipe was designed. The relative standard deviations of irradiance, obtained from simulation and experiment, were respectively 3.10% and 6.01%, both less than 11.56%. And the uniform illumination system is able to meet the requirement of high-throughput microfluidic qPCR.
To realize the precipitation particle imaging and measurement in the airborne condition, an imaging and measurement system was developed based on photodiode array. The system is composed of an optical system, a hardware system and a software system. The optical system can shape the laser beam and image the particles. The hardware system is composed of a front-end signal conditioning circuit and an FPGA controlling circuit, and mainly function in the particle image acquisition and signal processing. The software system contains two parts in FPGA and PC respectively, and realize the particle image compression, display and storage. Calibration in laboratory shows that the system’s measurement range is in 60~7400 μm, with a resolution in 60 μm. Field campaign results indicate that the system can meet the requirement of precipitation particle imaging and measurement under the flying condition.
Mobile passive differential optical absorption spectroscopy (DOAS) was used for the remote sensing of the emission flux from different systems of a steel factory. Correlation matrix of the absorption cross sections was used for the best DOAS inversion band. Vertical column density was retrieved by this system, combined with the meterorological wind field and car speed information,the emission of SO2 and NO2 in the area was estimated. The results showed that the average value of the flux of SO2 and NO2 was 149 kg/h and 372 kg/h in the rolling and smelting system, 260 kg/h and 286 kg/h in the coking system, 21 kg/h and 26 kg/h in the power system, 64 kg/h and 79 kg/h in the roasting system, and 34 kg/h and 99 kg/h in the sintering system.
Exciton binding energies in Cd1-x Mnx Te/CdTe parabolic quantum well (PQW) with different Mn contents were calculated through variational method in the effective mass approximation. The variations of exciton binding energy as a function of well width, barrier width and electric field were calculated with different Mn compostions. The results show that the exciton binding energy is a non-monotonic function of well width. It increases first until reaching a maximum, and then decreases as the well width increases farther. In addition, with the increase of Mn content the well width should decrease to reach the maximum value of the exciton binding energy due to the change of material band gap. The exciton binding energy increases first until reaching a stable value with the increase of barrier width, which is related to the barrier penetration of wave function. The external electric field has little effect on binding energy, and the effect decreases with the increase of Mn content, but when the electric field is large enough, it will destroy the excitonic effect. The results are meaningful in design of optoelectronic device based on PQW.