Abstract:We study time-inconsistent optimal control problems with infnite horizon and dominating discount. In this problem, the non-constant discount rate results in the time inconsistency, thus local optimization is not equal to overall optimization anymore. Hence we study the equilibrium control instead of the optimal control. By using the needle variation method, we deduce the sufcient and necessary conditions for the equilibrium control. When the discount function has exponential form, our results degenerates to the Pontryagin maximum principle with infnite horizon. Finally, we given an example in economy.

Abstract:In this study, a stable local projection finite element method is derived for unsteady Navier-Stokes equations. This method is formed by local projection of advection term and pressure gradient. By using the equal-order conforming finite elements in space and implicit finite difference scheme in time, we derive a full discrete formulation and prove the stability and convergence of the approximation solution. Notably, the error estimates hold even for large Reynolds numbers.

Abstract:American option allows an option holder to exercise the option at any time before the expiration of option. Thus it is impossible to price it by the B-S formula. Numerical methods are usually applied to price an American option. The least square Monte Carlo method (LSM) was firstly proposed by Longstaff and Schwartz in 2001, in which different basis functions in the least square regression can significantly affect the final pricing. In this study we discuss the effect of different basic functions on the American option pricing.

Abstract:A second-order two-scale (SOTS) analysis method is developed for eigenvalue problems with quasi-periodic porous domain in curvilinear coordinates. Firstly, the eigenvalue equation is reformulated in the curvilinear coordinate system with periodic structure by using appropriate coordinate transformation. Secondly, the SOTS approximate solutions of the eigenvalues and corresponding eigenfunctions in curvilinear coordinates are constructed by the SOTS asymptotic expansion method and the corresponding finite element algorithms. The numerical experiments show that SOTS with its finite element algorithms has high computational accuracy and the algorithm in coordinate transformation is effective.

Abstract:We characterize the boundedness of the product of Toeplitz and composition operators for two polynomials symbols on Fock-Sobolev spaces. We also consider the commutativity of Toeplitz and composition operator, and obtain several necessary and sufficient conditions.

Abstract:We consider the real-time planning problem of swarm movement in complex environments with irregular obstacles and borders and proposes an improved limit cycle group obstacle avoidance algorithm. In this algorithm, the concepts of locality and envelope are borrowed from the traditional limit cycle. Then, by improving the repulsive force function of the traditional artificial potential field, the boundary repulsion is characterized in order to avoid collision with the boder. Finally, two simulations are implemented. The simulation results show that, compared with the traditional artificial potential field method, our algorithm can reduce the number of collisions and shorten the obstacle avoidance time adaptability and effectively.

Abstract:In order to make up for the negative impact of texture on the extraction results of the traditional GrabCut model, this paper analyzes the scale characteristics of the image edge and color distribution, and combines the image multiscale decomposition and GrabCut to propose a foreground extraction model based on image multi-scale decomposition. This model firstly decomposes an image into a series of smoothed images with the total variation regularization. In this decomposition process, the image edges are preserved, the textures are smoothed, and the color distribution range of the image regions is compressed; secondly, the foreground color distribution of the given smoothed image is represented with the Gaussian mixture model, and the histogram shape analysis method is used to optimize the number of Gaussians in the Gaussian mixture model, which makes up for the negative effects caused by the fixed number of Gaussians; finally, an iterative termination condition is designed according to the segmentation results of different smoothed images, thus the foreground can be extracted from the appropriate decomposition scale. Compared with the traditional foreground extraction algorithm, this model reduces the negative effect of texture on foreground extraction, and the evaluation scores are higher than the traditional algorithms.

Abstract:Rating prediction is the core issue of the recommendation system research. It predicts the user's rating of the product through the user's historical behavior, and recommends the user's favorite product based on the rating. The current recommendation system based on comment score prediction generally only uses convolutional neural network to capture local features or recurrent neural network to capture global features, ignoring the effective fusion of these two types of features. Aiming at the existing problems, this paper proposes a rating prediction recommendation model based on review feature extraction and hidden factor model, using adaptive receptive field convolutional neural network (CNN) to extract local features, and using gated recurrent unit (GRU) to extract global features. Fusion of different features into embedded representations of reviews. Then combined with the hidden factor model (LFM) to model the user's feature preference and the feature attributes of the product. Finally, the rating prediction is made on the embedded representations of users and commodities. The experimental results show that the model in this paper is higher than the existing baseline model on the five data sets.

Abstract:In view of the problems of ghost and incomplete detection in the process of target detection in the visual background extractor (ViBe) algorithm, this paper proposes a new algorithm of target detection of ViBe based on phased improvement.Firstly, in the initial phase of the model, the background model is constructed using the average value of the corresponding pixels of the first m frames of video sequence.At the same time, the 8 neighborhood of the original algorithm is changed to 24 neighborhood for sample selection and dynamic adjustment of the matching radius; then in the target detection stage, the maximum inter class difference method is introduced to calculate the best segmentation threshold of the current frame, and then the foreground pixels are discriminated twice; Secondly, in the phase of background model updating, the size of updating factor is dynamically adjusted according to the speed of background change; finally, the final foreground target is obtained by morphological processing of the obtained foreground image.Experimental results show that the improved ViBe algorithm not only solves the ghost problem effectively, but also improves the accuracy and integrity of target detection.

Abstract:The control flow integrity (CFI) strategy can effectively defend against control flow hijacking attacks, but the complex control flow graph construction makes the actual deployment of this strategy very difficult. In order to realize a practical detection method against control flow hijacking attacks, a method based on identifying abnormal program behaviors is proposed to detect control flow hijacking attacks, and a control flow hijacking attack detection system is implemented based on this method. Experiments show that this method can effectively detect various abnormal program behaviors caused by control flow hijacking attacks. The attack detection system works well and can be easily deployed in the actual application environment.

Abstract:In view of the limitations in the process of assembling the conceptual model according to the the designer’s experience in the current product design system, a product design method based on design scheme tree and knowledge base is proposed. The formulae, experience, optimization principles and other information in the design process are stored in the knowledge base in which the structure is the tree with the product attributes as its nodes. The product conceptual design and parts’ detailed design are combined, and the product components are screened and designed while the principles are arranged. The tree structure is adopted and the product attribute is taken as the node to generate the design tree. Then the ideal solution method based on analytic hierarchy process is used to rank the alternatives, which increases the diversity of alternative schemes and reduces the cost of the product while obtaining the optimal solution. Taking the design of the hoist as an example, the reliability and practicability of the algorithm are verified

Abstract:The k-d tree registration algorithm has the disadvantages of too much computation for high-dimensional features, less use of SIFT feature information and a lot of errors in the registration results, due to the complexity of scale invariant feature transformation (SIFT). Therefore, a fast stitching algorithm based on perceptual hash and scale invariant feature transformation is proposed. Firstly, the perceptual HASH algorithm is used to extract the hash fingerprint of the matching image and that of the image to be matched, and the similar parts of the two images are quickly identified. Then the SIFT feature points of similar areas are calculated and extracted. In the feature point registration algorithm, the traditional k-d tree algorithm is replaced. The main direction and coordinate position information of SIFT feature points are used to filter out the unnecessary feature point matching and reduce the registration time. Finally, the best weighted seam image fusion algorithm is used to eliminate the mutation and complete the stitching. Experimental results show that the number of feature points extracted by this algorithm is less than the number of feature points extracted by the traditional algorithm, and the amount of calculation is reduced in the registration algorithm. At the same time, some mismatches are roughly filtered, which improves the matching accuracy, and the time-consuming of the algorithm is significantly improved compared with the traditional method.

Abstract:With the rapid development of Internet Finance, the existence of financing websites has become a much more serious problem for personal property safety. However, the traditional website recognition technology is only applicable to the website identification with some remarkable features, resulting in low efficiency of financing websites detection. This paper selects features from multiple dimensions and summarizes detection features into five categories: domain name features, search engines index features, tag features, image features, textual features, which greatly reflect the essential difference between the financing websites and other types of websites. Then a recognition model with deep neural network is proposed. In order to verify the validity of the model, a comparison experiment of our model with decision tree algorithm, support vector machine algorithm and K-Nearest Neighbor algorithm is designed. The experiments demonstrate that the accuracy and precision of the accuracy and precision of the proposed model is 95.9%, 98.7% respectively, and all kinds of evaluation indicators are better than the traditional machine learning algorithm. The results show that the proposed method can effectively detect the financing websites.

Abstract:The accuracy of the energy consumption models for aluminum electrolysis is poor due to the intensive noise, unknown distribution types and high-dimensional parameter characteristics in the aluminum electrolysis process. In order to solve the problem, a novel modeling method based on Adaptive Markov Chain Monte Carlo Unscented Particle Filter Neural Network (AMCMC-UPFNN) is proposed. This method firstly used the square term of the κ parameter in the Unscented Transformation (UT) to replace the corresponding regular term in the UPFNN algorithm, avoiding the nonpositive definite situation of the UT matrix due to high dimension, and ensuring the reasonableness of Sigma point sampling in UPFNN; then, an adaptive sampling strategy was introduced on the basis of the traditional MCMC method to maintain the diversity of particles and make the established probability density distribution closer to the true distribution. Finally, the verification experiment of aluminum electrolysis industrial application was carried out to compare the proposed method with related modeling methods. The results show that the relative error rate of the AMCMCUPFNN model does not exceed 1%, and it has achieved better performance indicators than PFNN, UPFNN and MCMC-UPFNN.

Abstract:Portable gamma spectrometer is widely used in many fields, such as field prospecting, environmental radiation monitoring and scientific experiments. In order to further reduce the volume of portable energy spectrometer and improve its energy spectrum performance, so as to extend its application field. Based on the latest scintillation crystal materials, semiconductor photoelectric converters and high performance microprocessors, we have developed a new generation of portable gamma spectrometer. In terms of detector design, GAGG: Ce crystal coupled SIPM array is used to successfully design and manufacture a compact energy spectrum probe with high efficiency and high energy resolution; in terms of data acquisition circuit, high performance ARM processor and its own ADC peripheral are used to replace the traditional circuit architecture of FPGA + ADC, and a special signal processing ARM program is designed to realize online energy spectrum measurement, which greatly reduce the circuit Size and system power consumption. To sum up, based on GAGG: Ce crystal coupled SIPM and ARM processor, a pocket type energy spectrometer with low cost, small volume, low power consumption and high performance has been successfully developed. The volume of the whole spectrometer is only 80 mm × 40 mm × 40 mm, and the weight is 200 g. The tested power of the spectrometer is 481mW, and it can work for 26 hours with its own power supply. The linear goodness of fit of the spectral response is 0.996, and the energy resolution is 5.2% (@ 662 keV).

Abstract:Quantum state discrimination is a very important problem in the field of quantum information and quantum computation. Usually，the equatorial state, a special latitudinal state, is often used to study quantum communication both from theoretical and experimental perspectives. In this paper, we mainly use Neumark's theorem and the optical realization of the programmable quantum state discriminator to investigate how to unambiguously discriminate two unknown latitudinal states of arbitrary distribution. The detection operators and the successful probability are derived. Furthermore, we find that the detection operators obtained in this paper are the same as the optimal detection operators obtained from the unambiguous discrimination of two unknown latitudinal states of uniform distribution. These results have important reference significance for the construction of the programmable quantum discriminator in laboratory.

Abstract:Breather is an important nonlinear vibration mode that widely exists in many nonlinear models. In this paper, the approximate breather solution of the time-dependent Peierls equation is presented, and the correctness of the breather solution is verified by numerical simulation. The results show that the proposed solution is really a breather of the dynamical Peierls equation, and the breather solution can be viewed as a bound state of dislocation and anti-dislocation.

Abstract:A terminal for the study of simultaneous proton irradiation and hydrogen gas permeation for testing tritium permeation barrier (TPB) coatings at elevated temperature has been developed. A set of special testing equipment was added to the 2×3 MV tandem accelerator in Sichuan University providing the capability to study the synergistic effect of displacement damage, hydrogen permeation, and high temperature on the microstructure and properties of the coatings. The overall design goal and some main components of this terminal were introduced in detail, such as sample holder, hydrogen-containing permeation gas loop and design principle. The terminal was developed in order to obtain relevant data on TPB coatings, and it will enable future studies into the effect of irradiation on hydrogen permeation property in high temperature environment using in situ proton irradiation. Furthermore, the optimization of the terminal and testing parameters were discussed in this study.

Abstract:It is of very important theoretical significance to study the velocity and temperature distributions for transitional boundary layers with abrupt changes of wall friction and heat transfer. The momentum and thermal boundary layers are divided into the laminar sublayer and quasi-turbulent layer for natural transition flows on a flat plate, and the velocity (or temperature) profiles in the two zones are represented by the cubic polynomial and 1/7.5 (or 1/7) power functions, respectively. An integral method is used to recast the momentum and energy equations into the integro-differential equation groups, and the closed-form analytical solutions of velocity and temperature for transition boundary-layers are obtained by employing the fourth-order Runge-Kutta method. Following the foregoing analytical results, the characteristics of local skin friction factor as well as Nusselt number is also obtained. It is showed that the present analytical solutions can be validated by comparing with the Dhawan and Narasimha’s solution (D-N solution), Coupland’s T3A benchmark experimental and proposed numerical results, respectively, and the accuracy of analytical solution can reach 4.8% for the specified conditions in this paper. The two key parameters affecting the profiles of velocity and temperature of the transition boundary layer are also proposed and analyzed, and it is found that an intermittency factor has a crucial effect on the distributions of velocity and temperature across the laminar sublayer of transition regions.

Abstract:Using the characteristics of harmonic generation from X2+ isotope molecules (H2+, D2+ and T2+), an effective method to generate a high-intensity spectral continuum and isolated attosecond pulse has been theoretically proposed. It is found that, driven by different pulse durations, H2+, D2+ and T2+ can enter into the charge resonance enhanced ionization region, respectively. When the half-cycle of the laser amplitude region is exactly in the charge resonance enhanced ionization region, the harmonic emission peak with the maximum emitted energy happens to have the optimal harmonic intensity. Further, by introducing a half-cycle unipolar pulse in this region, the selected harmonic emission peak can be extended, showing an intense spectral continuum contributed by single harmonic emission peak. Through superposing the harmonics on this spectral continuum, the pulse duration of 42 as isolated attosecond pulses can be obtained.

Abstract:By using first-principles calculation based on density-functional theory, we have systematically investigated the stability, electronic and mechanical properties of (4, 2) Au-Ag alloy nanotubes encapsulated in a series of zigzag (n, 0) carbon nanotubes with various diameters. The most stable combined system with larger filling rate is AuxAg4-x@(15, 0) with an optimal tube-tube distance of about 4.20 ?. The analysis of band structure shows that the quantum conductance of the composite system is much higher than that of the corresponding isolated alloy nanotubes. The energy states near the Fermi level are mainly attributed to the s electrons of the inner Au and Ag atoms as well as the p electrons of the outer C atoms. The critical strains and the ideal strengths of the combined systems are remarkably higher than those of the freestanding alloy nanotubes, suggesting that the mechanical properties of the alloy nanotubes are signi?cantly enhanced by the carbon nanotube coating.

Abstract:The bentonite from Wuhu, Anhui (WH), Santai, Sichuan (ST), and Xinyang, Henan (XY) were used as the raw material, and sodium carbonate was used as a modifying agent to modify three raw materials (named as WH-G, XY-G and ST-G), then the sodium samples were heat-treated at high temperature. The phase, structure, thermal properties and spectral characteristics of samples were characterized and analyzed. The results showed that the temperature of the montmorillonite losing adsorbed water and interlayer water in the three samples WH-G, XY-G and ST-G increase with the increase of the layer charge number of the montmorillonite in the samples, but its thermal stability is opposite. The structures of montmorillonite WH-G and XY-G samples are completely destroyed at 900 °C, while the structure of montmorillonite of ST-G sample is completely destroyed at 800 °C.

Abstract:In order to explore the biological control potential of Bjerkandera adusta BK-1, this study tested the disease resistance effect of BK-1 with the antifungal activity. And used RT-qPCR to analyze the expression levels of eight cell-wall lyase genes of B. adusta strain BK-1. The results showed that in response to six pathogenic fungi (Alternaria alternata, Alternaria alternata f. sp. mali, Alternaria solani, Alternaria tenuissima, Fusarium oxysporum and Botrytis cinerea), the expression of the chitinase gene BaCHIB was up-regulated by 27.3 to 50.3 times expression of,which is much higher than the other seven candidate genes. BaCHIB belongs to the glycoside hydrolase 18 family (GH 18), and has the Chic_BD (aromatic chitin/cellulose-binding site residues) domain, a domain that belongs to the chitinase subgroup B (CHIB). Combined with the analysis of disease resistance in planta, the up-regulation of the gene induced expression is highly synchronized with the appearance of disease resistance. And the exogenously expressed protein BaCHIB extracted from the Pichia pastoris expression system showed high chitinase and significant antifungal activity against a variety of plant-pathogenic fungi, including Alternaria alternata, Alternaria solani and Botrytis cinerea. This result showed that BaCHIB has a fungicide activity.

Abstract:To explore the main active components that inhibit T.rubrum in the leaves of Rhododendron dauricum L., 16 compounds were isolated and identified from the ethyl acetate phase of Rhododendron dauricum L.’s leaves by a variety of isolation methods based on the bioactivity tracking method.They are identified as Daurichromenic acid(1), farrerol(2), vanillic acid(3), taxifolin(4), 4-Hydroxybenzoic acid(5), umbelliferone(6), 2-Methyl-5,7-dihydroxychromone(7), Maslinic acid(8), corosolic acid(9), avicularin(10), syringic acid(11), kaempferol(12), quercetin(13), ursolic acid(14), oleanolic acid(15),cucurbitacin D(16).Among them,compounds 7~9 were isolated from this plant for the first time.The results of bacteriostatic activity determination showed that compounds 1~3, 5~7 and 11 had certain inhibitory activities against T.rubrum.Among them, compounds 2, 6 and 7 had the highest inhibitory activity and were the main active substances, with MIC of 0.15625~0.3125mg·mL-1 and MFC of 1.25~5 mg·mL-1.In this study, it was first found that leaves of R.dauricum L.had better inhibitory activity against T.rubrum and the active monomer was screened out.

Abstract:In order to study the classification and evolution of bHLH transcription factor family members in Populus tremula, and predicate their possible functions under drought stress, a variety of bioinformatics methods were used to identify and characterize the bHLH transcription factor in P. tremula at the whole genome level, and analyze the transcriptome of roots tissue under drought stress. The results showed that there were 167 bHLH transcription factor family proteins in P. tremula genome. By phylogenetic analysis with Arabidopsis bHLH protein sequence, it was divided into 15 sub-families, and 39 PtbHLH functions were predicted. These functions indicated that theses bHLHs were involved in multiple physiological processes of the growth and development of P. tremula. Gene structure and motif analysis illustrated that almost all PtbHLHs in the same subfamily have similar exon/intron and motif structure. In addition, RNA-seq data was used to analyze the expression of PtbHLH gene under drought stress, and 4 potential bHLH drought-resistant proteins were screened out.

Abstract:In order to promote the reuse of Larix kaempferi waste resources， this study used the litter needles of Larix kaempferi as raw materials to optimize the extraction process of total flavonoids by ultrasonic-assisted extraction method, and studied the antioxidant activity of flavonoids. By three-factor three-level response surface analysis, the best extraction process for total flavonoids from Larix kaempferi litter needles was: the ethanol concentration is 60%, the liquid-to-material ratio is 33:1 mL/g, the extraction temperature is 80 ℃, the ultrasonic power is 270 W, the ultrasonic frequency is 40 kHz, and the extraction time is 58 min. Studies on the antioxidant activity of different extraction phases in vitro showed that the antioxidant activity was n-butanol phase>water residue phase>ethyl acetate phase>petroleum ether phase from large to small. The semi-inhibitory rate of n-butanol on DPPH free radical was 7.438 μg/mL, which is slightly weaker than that of vitamin C (7.259 μg/mL); the IC50 value of ABTS radical scavenging was 6.425 μg/mL, showing a higher scavenging capacity than vitamin C. These results showed that the extraction process was stable and feasible, with a high yield of total flavonoids and good antioxidant activity. The research results show that Larix kaempferi waste has the potential to develop into plant-derived natural antioxidants.