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In this paper, we propose a directionally selective fractional-order lobular giant motion detector (LGMD) visual neural network. Unlike most collision-sensing network models based on LGMDs, our model can not only sense collision threats but also obtain the motion direction of the collision object. Firstly, this paper simulates the membrane potential response of neurons using the fractional-order differential operator to generate reliable collision response spikes. Then, a new correlation mechanism is proposed to obtain the motion direction of objects. Specifically, this paper performs correlation operation on the signals extracted from two pixels, utilizing the temporal delay of the signals to obtain their position relationship. In this way, the response characteristics of direction-selective neurons can be characterized. Finally, ON/OFF visual channels are introduced to encode increases and decreases in brightness, respectively, thereby modeling the bipolar response of special neurons. Extensive experimental results show that the proposed visual neural system conforms to the response characteristics of biological LGMD and direction-selective neurons, and that the performance of the system is stable and reliable.

Yaoqiang Wu,1 Bo Yu,2 Yaping Li,3 Fuxiang Yu,1 Zhongguo Li,1 Daxin Chen,1 Feng Jiang,1 Jianbo Bo,1 Hongwei Xue,1 Hongyang Lv,1 Haiyang Li1 1Department of General Surgery, Dandong First Hospital, Dandong, Liaoning, People’s Republic of China; 2Department of Gastroenterology, Dandong First Hospital, Dandong, Liaoning, People’s Republic of China; 3Department of Intensive Care Unit, Dandong First Hospital, Dandong, Liaoning, People’s Republic of ChinaCorrespondence: Yaoqiang Wu, Department of General Surgery, Dandong First Hospital, Dandong, Liaoning, People’s Republic of China, Tel/Fax + 86-415-2819133, Email wo612389@163.comPurpose: Colon cancer is the most commonly diagnosed gastrointestinal cancer. This research intended to evaluate the prognostic values of LINC01006 and miR-3199 for colon cancer and their effects on cell physiology.Patients and Methods: LINC01006 and miR-3199 expression levels were determined by RT-qPCR. Patients’ 5-year cumulative survival rate was analyzed by Kaplan–Meier curves with the Log rank test. Chi-square test and multivariate Cox regression analysis were used to access the clinical significance. CCK-8 assay, transwell assay, and TUNEL assays were used to monitor the change of cell proliferation, invasion, migration, and apoptosis.Results: The expression level of LINC01006 was increased while miR-3199 was decreased in colon tissues and cells compared to normal ones. This dysregulated expression was correlated with T stage (P = 0.002) and N stage (P = 0.009). High LINC01006 level (HR = 4.048, 95%: 1.502– 10.911, P = 0.006) or low miR-3199 level (HR = 3.421, 95% CI: 1.254– 9.330, P = 0.016) was outstanding for predicting poor prognosis in patients with colon cancer. Downregulation of LINC01006 reduced cell proliferation, invasion, and migration but induced cell apoptosis (P < 0.05).Conclusion: LINC01006 knockdown showed anti-proliferative, anti-metastatic, and apoptotic-induced effects on colon cancer cells. This study contributes to research on promising prognostic biomarkers of colon cancer and might give way to further investigation of alternative tumor targets.Keywords: colon cancer, LINC01006, miR-3199, prognosis

Additional file 2: Figure S1 The relative abundances of dominant taxa at class level (A), order level (B), family level (C), and species (D). Figure S2 Analysis result of the function annotationsin Cir group and NC group based on the MetaCyc database. Figure S3 Analysis result of the function annotationsin HE group and NC group based on the MetaCyc database.

Additional file 1: Table S1 The serum concentrations of 11 SCFAs in the three groups. Table S2 The serum concentrations of 28 tryptophan metabolites in the three groups. Table S3: The faecal concentrations of 11 SCFAs in the threegroups. Table S4 The faecal concentrations of 29 tryptophan metabolites in the three groups.

Objectives This study aims to investigate whether surgery performed during night compared with daytime were associated with an increased risk of operative mortality of type A aortic dissection (TAAD) patients. Methods A total of 2015 TAAD patients who underwent surgical repair were collected from two cardiovascular centers from Jan 2015 to Jan 2021. According to the start time of surgery, patients were divided into daytime group (06:01 a.m. to 06:00 p.m.) and night-time group (06:01 p.m. to 06:00 a.m.), and retrospective analyses were performed between them. Results The operative mortality of night-time group (12.2%, 43/352) was dramatically higher than daytime group (6.9%, 115/1663; p = 0.001). There was significant difference between night-time and daytime groups in terms of 30-days mortality (5.8% vs 10.8%; p = 0.001) and in-hospital mortality (3.5% vs 6.0%; p = 0.03). The night-time group had a longer duration of intensive care unit stay (4 vs two; days; p < 0.001) and ventilation support (34 vs 19; hours; p < 0.001), compared with daytime group. The risk factors for operative mortality were night-time surgery (odds ratio [OR], 1.545; p = 0.027), age (odds ratio, 1.152; p < 0.001), total arch replacement (OR, 2.265; p < 0.001) and previous aortic surgery (OR, 2.376; p = 0.003). Conclusion Night-time surgical repair may be associated with higher operative mortality of patients with TAAD. Nevertheless, it is reasonable to offer emergency surgery at night-time for such patients who were more likely to present disastrous complications with delayed surgical intervention, as outcomes indicate acceptable operative mortality.

Objective Prevalence of hepatopulmonary syndrome (HPS) ranges from 4% to 47% in patients with cirrhosis. This study aimed to explore possible relationship between CX3CR1 and angiogenesis or macrophage accumulation in pathological process of HPS. Material and methods Wide-type C57Bl/6 mice were divided into WT-sham, WT-common bile duct ligation (WT-CBDL), WT-CBDL plus antibody (WT-CBDL + Ab) and WT-CBDL plus Bevacizumab. The CX3CR1GFP/GFP mice were grouping into CX3CR1 GFP/GFP-sham, CX3CR1 GFP/GFP-CBDL and CX3CR1 GFP/GFP-CBDL + Bevacizumab group. Intrapulmonary expression of Akt, pAkt, ERK, pERK, iNOS, VEGF, PDGF was measured using biological technology. Hematoxylin-eosin (H&E) staining and immunohistochemical analysis were used to evaluate changes of pulmonary tissues including pathological abnormality, angiogenesis and macrophage accumulation. Results Blockade CX3CR1 pathway inhibited angiogenesis, macrophage accumulation and pathological changes of lung tissues. Blockade of CX3CR1 pathway reduced pAkt, pERK, iNOS, PDGF and VEGF activation. CX3CR1 contributed to the process of angiogenesis and activate the pro-angiogenic factors. CX3CR1 deficiency obviously reduced the macrophage accumulation. Inhibition of VEGF by Bevacizumab improved intrapulmonary angiogenesis and pathological changes of lung tissues. Inhibition of VEGF by Bevacizumab retarded the production of pAKt, PDGF, and iNOS. Inhibition of VEGF by Bevacizumab reduced CX3CL1 production. Conclusion CX3CR1 could regulate the angiogenesis and activation of pro-angiogenic factors, including pAKT, pERK, iNOS, VEGF and PDGF in the process of hepato-pulmonary syndrome. Moreover, CX3CR1 could also contribute to the macrophage accumulation.

AimsTo investigate the potential role of renal arterial resistance index (RI) in the differential diagnosis between diabetic kidney disease (DKD) and non-diabetic kidney disease (NDKD) and establish a better-quantified differential diagnostic model.Materials and MethodsWe consecutively reviewed 469 type 2 diabetes patients who underwent renal biopsy in our center. According to the renal biopsy results, eligible patients were classified into the DKD group and the NDKD group. The diagnostic significance of RI was evaluated by receiver operating characteristic (ROC) curve analysis. Logistic regression analysis was used to search for independent risk factors associated with DKD. Then a novel diagnostic model was established using multivariate logistic regression analysis.ResultsA total of 332 DKD and 137 NDKD patients were enrolled for analysis. RI was significantly higher in the DKD group compared with those in the NDKD group (0.70 vs. 0.63, p< 0.001). The optimum cutoff value of RI for predicting DKD was 0.66 with sensitivity (69.2%) and specificity (80.9%). Diabetic retinopathy, diabetes duration ≥ 60 months, HbA1c ≥ 7.0(%), RI ≥ 0.66, and body mass index showed statistical significance in the multivariate logistic regression analysis. Then, we constructed a new diagnostic model based on these results. And the validation tests indicated that the new model had good sensitivity (81.5%) and specificity (78.6%).ConclusionsRI has a potential role in discriminating DKD from NDKD. The RI-based predicting model can be helpful for differential diagnosis of DKD and NDKD.

Additional file 2: Fig. S1. Distribution of SNP number in different chromosomes and count of MAF. A, SNP numbers. B, SNP frequency in different minor allele frequency. Fig. S2. Distributions of SNP linkage disequilibrium decay and heterozygosity. A, Linkage disequilibrium decay (r2) across different linkage disequilibrium windows in 294 wild soybean accessions. B, Histogram of heterozygosity for SNPs. Fig. S3. Boxplot representing the distribution of flowering time in five active accumulated temperature zones in Heilongjiang province, China. A, flowering time data recorded in 2020; B, flowering time data recorded in 2021. Active accumulated temperature zones have five types (I, II, III, IV, and V). Fig. S4. Histogram of flowering time recorded from two consequent years. A, 2020 phenotyping of flowering days. B, 2021 phenotyping of flowering days. Fig. S5. Correlation of flowering time between two-year experiments in 2020-2021. Pearson correlation coefficient (r) was used. Fig. S6. Haplotype distribution of candidate genes against active accumulated temperature (AAT) zones. A, Glyma.02g100800. B, Glyma.04g096000. C, Glyma.09g279900. Fig. S7. Haplotypic distribution of flowering time in 2020-2021 for three candidate genes. A-B, TAXi_N haplotypes analysis in 2020 and 2021. C-D, EDR1 haplotypes analysis in 2020 and 2021. E-F, SCAR2 haplotypes analysis in 2020 and 2021. Different letters represent the significant levels at P

Additional file 2: Fig. S4. Source data of full gel blot images for Fig.1a.

Additional file 4: Table S1. Primers used for PCR and qRT-PCR in this study.

The purpose of the Session-Based Recommendation System is to predict the user's next click according to the previous session sequence. The current studies generally learn user preferences according to the transitions of items in the user's session sequence. However, other effective information in the session sequence, such as user profiles, are largely ignored which may lead to the model unable to learn the user's specific preferences. In this paper, we propose a heterogeneous graph neural network-based session recommendation method, named SR-HetGNN, which can learn session embeddings by heterogeneous graph neural network (HetGNN), and capture the specific preferences of anonymous users. Specifically, SR-HetGNN first constructs heterogeneous graphs containing various types of nodes according to the session sequence, which can capture the dependencies among items, users, and sessions. Second, HetGNN captures the complex transitions between items and learns the item embeddings containing user information. Finally, to consider the influence of users' long and short-term preferences, local and global session embeddings are combined with the attentional network to obtain the final session embedding. SR-HetGNN is shown to be superior to the existing state-of-the-art session-based recommendation methods through extensive experiments over two real large datasets Diginetica and Tmall.

Additional file 1: Fig. S1. Phenotypes of E1 transgenic lines and DN50 plants under LD (long day, 16 h light/8 h dark) conditions. Fig. S2. The leaf phenotypic characterization of the E1-overexpression (E1-OE) plants in W82. Fig. S3. The transcription levels of TCP33, TCP36, TCP37, TCP39 and TCP42 in DN50 and E1-OE plants.

In this paper, combining with the tenth anniversary load test of Sutong Bridge, we proposed the Brillouin Optical Time Domain Analysis (BOTDA) to conduct health monitoring research on the bridge, and completed the following three aspects: Firstly as an auxiliary measure of strain monitoring, monitor the level of stress and strain along the longitudinal bridge to each position. Secondly through the parking of the vehicles at different positions on the bridge pavement, the influence lines on the overall structural stress of the bridge are obtained. Thirdly through the long-term strain monitoring of the bridge, the impact of the usual traffic load information on the bridge strain is obtained.The results show that the technology not only breaks through the monitoring bottleneck of traditional point sensors, but also realizes distributed measurement of strain on the transmission path; it can also be used for real-time monitoring, damage identification, crack location, settlement monitoring of traffic load information of bridges and other structures.. Compared with the traditional sensor test results, the effectiveness and frontier of the technology are proved, and the significance of the distributed fiber-optic sensor technology for the health monitoring of major structures such as bridges is fully explained.

Teleoperation could be used in space on-orbit serving missions, such as object deorbits, spacecraft approaches, and automatic rendezvous and docking back-up systems. Teleoperation rendezvous and docking in lunar orbit may encounter bottlenecks for the inherent time delay in the communication link and the limited measurement accuracy of sensors. Moreover, human intervention is unsuitable in view of the partial communication coverage problem. To solve these problems, a shared control strategy for teleoperation rendezvous and docking is detailed. The control authority in lunar orbital maneuvers that involves two spacecraft as rendezvous and docking in the final phase was discussed in this paper. The predictive display model based on the relative dynamic equations is established to overcome the influence of the large time delay in communication link. We discuss and attempt to prove via consistent, ground-based simulations the relative merits of fully autonomous control mode (i.e., onboard computer-based), fully manual control (i.e., human-driven at the ground station) and shared control mode. The simulation experiments were conducted on the nine-degrees-of-freedom teleoperation rendezvous and docking simulation platform. Simulation results indicated that the shared control methods can overcome the influence of time delay effects. In addition, the docking success probability of shared control method was enhanced compared with automatic and manual modes.

Background Hypothermic circulatory arrest is usually used in aortic surgery, congenital heart defect repairs and other complex surgeries. It is frequently associated with excessive postoperative bleeding and the transfusion of allogeneic blood products. The physiopathology of hypothermic circulatory arrest-induced coagulopathy has never been systematically studied. The aim of the study was to investigate this phenomenon in a pig model. Methods Ten pigs were randomly assigned to 30 min of hypothermic circulatory arrest at either 15 °C (n = 5) or 25 °C (n = 5). Detection of apoptosis and haemostatic system assays were performed in this experiment. Enzyme-linked immunosorbent assays were performed at ten time points in each group to study the changes in the coagulation system in hypothermic circulatory arrest. All of the statistical analyses were performed in SPSS software, version 18.0, and as bilateral tests, and p Results There was no significant difference in the effect of different types of hypothermic circulatory arrest on routine laboratory tests and tissue sample analysis (p > 0.05, for all). Our results demonstrated that more severe systemic activation of the coagulation system (TAT and F1+2) was applied in the deep hypothermic circulatory arrest group but not in the moderate hypothermic circulatory arrest group (TAT/p = 0.01, F1+2/p = 0.03). However, this activation of the coagulation system (AT III and PC) was not associated with changes in the anticoagulation pathway (AT III/p = 0.24, PC/p = 0.33). In addition, analysis of biomarkers of the haemostatic system revealed that the consumption of coagulation is more concentrated on extrinsic coagulation factors (FVII/p = 0.01). Conclusions Moderate hypothermic circulatory arrest is more suitable for patients with coagulation dysfunction. We believe the application of deep hypothermic circulatory arrest should pay more attention to changes in coagulation rather than the anticoagulation pathway. Extrinsic coagulation factor supplementation is more effective after deep hypothermic circulatory arrest.

Standard flow facility is a platform for performance test of flowmeters. Flow diverter is an essential component of liquid flow facility based on flying start-and-stop method, and is also a key equipment deciding the uncertainty of flow facility. In order to improve the accuracy of large flow facilities, the effects of acceleration performance and liquid shock force on the uncertainty of the flow diverter with large flow rate is analyzed. The actuation structure using servo motor and reducer to drive the flow diverter is put forward. The effect of step motor and servo motor on the uncertainty of the flow diverter is verified by real-flow test. The results of experiment indicate that servo motor driven flow diverter has faster transfer acceleration and more stable transfer process. The test results of transition time difference method show that the uncertainty of servo motor driven flow diverter is less than 0.003%.

Shaking table tests (STTs) provide an effective method to realistically assess seismic performance of nonstructural components (e.g., ceilings, water pipe supports and hangers, and glass screen walls), whose damage losses have been found to exceed those of structural components in recent earthquakes. During a shaking table test, nonstructural components respond upon the floor motion of a supporting frame where nonstructural components are attached to. Accurately reproducing floor response spectra of the supporting frame is therefore critical to achieve consistent and high-quality test results. This paper proposes a multi-directional decoupling iteration (MDI) control method to achieve this demand. The principle of the proposed MDI method is explained first. The effectiveness of the proposed controller to overcome the dynamic coupling between the supporting frame and the shaking table and to accurately reproduce floor response spectra along multi-directions is validated through a series of STTs of water pipe supports and hangers.

In this paper, a continuous and non-convex promoting sparsity fraction function is studied in two sparse portfolio selection models with and without short-selling constraints. Firstly, we study the properties of the optimal solution to the problem $(FP_{a,\lambda,\eta})$ including the first-order and the second optimality condition and the lower and upper bound of the absolute value for its nonzero entries. Secondly, we develop the thresholding representation theory of the problem $(FP_{a,\lambda,\eta})$. Based on it, we prove the existence of the resolvent operator of gradient of $P_{a}(x)$, calculate its analytic expression, and propose an iterative fraction penalty thresholding (IFPT) algorithm to solve the problem $(FP_{a,\lambda,\eta})$. Moreover, we also prove that the value of the regularization parameter $\lambda>0$ can not be chosen too large. Indeed, there exists $\bar{\lambda}>0$ such that the optimal solution to the problem $(FP_{a,\lambda,\eta})$ is equal to zero for any $\lambda>\bar{\lambda}$. At last, inspired by the thresholding representation theory of the problem $(FP_{a,\lambda,\eta})$, we propose an iterative nonnegative fraction penalty thresholding (INFPT) algorithm to solve the problem $(FP_{a,\lambda,\eta}^{\geq})$. Empirical results show that our methods, for some proper $a>0$, perform effective in finding the sparse portfolio weights with and without short-selling constraints.

The affine matrix rank minimization (AMRM) problem is to find a matrix of minimum rank that satisfies a given linear system constraint. It has many applications in some important areas such as control, recommender systems, matrix completion and network localization. However, the problem (AMRM) is NP-hard in general due to the combinational nature of the matrix rank function. There are many alternative functions have been proposed to substitute the matrix rank function, which lead to many corresponding alternative minimization problems solved efficiently by some popular convex or nonconvex optimization algorithms. In this paper, we propose a new nonconvex function, namely, $TL_{\alpha}^{\epsilon}$ function (with $0\leq\alpha0$), to approximate the rank function, and translate the NP-hard problem (AMRM) into the $TL_{p}^{\epsilon}$ function affine matrix rank minimization (TLAMRM) problem. Firstly, we study the equivalence of problem (AMRM) and (TLAMRM), and proved that the uniqueness of global minimizer of the problem (TLAMRM) also solves the NP-hard problem (AMRM) if the linear map $\mathcal{A}$ satisfies a restricted isometry property (RIP). Secondly, an iterative thresholding algorithm is proposed to solve the regularization problem (RTLAMRM) for all $0\leq\alpha0$. At last, some numerical results on low-rank matrix completion problems illustrated that our algorithm is able to recover a low-rank matrix, and the extensive numerical on image inpainting problems shown that our algorithm performs the best in finding a low-rank image compared with some state-of-art methods.

Coverage analysis is a foundation computation analysis of space missions, which calculates figures of merits and visible periods of the spacecraft. Conventional analysis algorithms are computationally efficient but lack universality because they deal specifically with particular conditions of special orbits and specific objects. In this study, a coverage analysis tool that rectifies this state of affairs was developed using a plugin. The developed tool decouples coverage calculation from orbit propagation and thereby facilitates efficiency, universality, and flexibility. Orbit propagation is carried out using the independently developed astrodynamics simulation software AstroSim, and coverage calculation is achieved via the analysis plugin tool. This paper discusses the development of the coverage analysis tool based on the objectoriented AstroSim software and Qt, and explains the key technologies used in the coverage tool design from three aspects: platform architecture, plugin interface, and implementation. The designed tool can investigate measurement parameters and access periods of various objects (such as satellites, sensors, and facilities) and orbits, and can also calculate their related statistical figure of merit.

The goal of compressed sensing is to reconstruct a sparse signal under a few linear measurements far less than the dimension of the ambient space of the signal. However, many real-life applications in physics and biomedical sciences carry some strongly nonlinear structures, and the linear model is no longer suitable. Compared with the compressed sensing under the linear circumstance, this nonlinear compressed sensing is much more difficult, in fact also NP-hard, combinatorial problem, because of the discrete and discontinuous nature of the $\ell_{0}$-norm and the nonlinearity. In order to get a convenience for sparse signal recovery, we set most of the nonlinear models have a smooth quasi-linear nature in this paper, and study a non-convex fraction function $\rho_{a}$ in this quasi-linear compressed sensing. We propose an iterative fraction thresholding algorithm to solve the regularization problem $(QP_{a}^{\lambda})$ for all $a>0$. With the change of parameter $a>0$, our algorithm could get a promising result, which is one of the advantages for our algorithm compared with other algorithms. Numerical experiments show that our method performs much better compared with some state-of-art methods.

According to the gas equation of state, the volume of gas at a certain time is related to the current temperature and pressure. Therefore, the calibrated K-factor of gas flowmeter will be affected by the temperature and pressure during the calibration process. Normally, in the ordinary pressure calibration process, the temperature change of calibration medium does not exceed 0.2 degrees, and the influence on the measurement results is about 0.08%. However, the influence on the measurement results can reach 3%~4% due to the different position of the pressure-sampling. An array experiments were carried out on the gas vortex flowmeter (which was most influenced by the pressure-sampling position). It was found that different pressure-sampling positions affect the calibrated K-factor of the gas vortex flowmeters without temperature and pressure compensation, and the degree of influence is proportional to the pressure drop generated by the gas passing through the flowmeter. And the influence is nonlinear. The greater the gas flow velocity is, the more obvious the pressure difference among different pressure-sampling positions of the pipeline is and the more serious the deviation of calibrated K-factor from normal value is. So, when the calibrated K-factor deviate greatly at large flow velocity points but linear at other flow velocity points, the correctness of the pressure-sampling position in the calibration process should be considered.

Signal de-noising and feature extraction, whose performance directly affect the evaluation of non-destructive testing (NDT) results, is essential technology for ultrasonic NDT echo processing. Aiming to solve the problem of nonlinear distortion between measured ultrasonic echo and its mathematical model, which widely used are exponential model (EM) and Gauss model (GM), a dual Gaussian attenuation model (DGAM) of ultrasonic echo signal and its parameter estimation method are proposed in this paper. The proposed dual Gaussian attenuation model parameter estimation (DGAM-PE) method is introduced in three parts: calculating mean square error between measured signal and model, optimizing mean square error by particle swarm optimization, optimum parameters extraction based on optimization result. The simulation and experiment results show that compared with the exponential model and Gaussian model, the proposed dual gaussian attenuation mathematical model of ultrasonic signal in this paper can better simulate the measured ultrasonic echo signal, with a mean square error of 0.0073 and normalized correlation coefficient of 0.9816. Additionally, an improved adaptive particle swarm optimization is proposed in order to enhance the accuracy of parameter estimation results.

In this paper, the problem of defect reconstruction in the ultrasonic inspection of an axisymmetric object is studied. Focusing on the shortcomings of the traditional method based on propagation time reversal, we analyzed the causes of errors and proposed a method of defect reconstruction based on boundary tangent fitting. The circle model and ellipse model are used to reconstruct the defect of an air hole. The reconstruction results show that the reconstruction error by circle fitting is less than 0.05 mm for testing a circular defect in a solid object. Meanwhile, the reconstruction error by ellipse fitting for a circular defect and an elliptical defect are less than 0.1 and 0.5 mm, respectively. Because the ultrasonic wave is perpendicular to the exterior of the solid object and has a radial angle to the exterior of the hollow object, the reconstruction error for the hollow object is greater than that for the solid object. If the boundary fitting model is chosen properly, the method in this paper is also applicable to the reconstruction of defects by the rectangular and arbitrary boundary model, or the reconstruction of defects in objects with other shapes.

Ultrasonic non-destructive testing, which is one of the most important and rapidly developed non-destructive testing technologies, is widely used in industrial production and other areas. Signal de-noising and feature extraction, whose performance directly affects the evaluation of non-destructive testing results, are the key technologies of ultrasonic non-destructive testing data processing, and also the core elements of ultrasonic non-destructive testing. Therefore, the research on them has important academic significance and practical value. In order to solve the problem of parameter estimation and noise reduction of ultrasonic echo in strong noise background, a novel ultrasonic echo processing method is proposed in this paper. The principle of the proposed method in this paper is as follows. The ultrasonic echo, which is generated by modulating the ultrasonic transducer, has a specific structure, but the noise in practical engineering is usually a Gauss random process, therefore the noise is independent of the ultrasonic signal structure. In this paper, the problem of parameter estimation and noise reduction of ultrasonic echo signal are converted into a function optimization problem by establishing the model of ultrasonic signal, determining the objective function, optimizing the objective function, estimating the parameters, and reconstructing the ultrasonic signal. Firstly, a dual gaussian attenuation mathematical model of ultrasonic signal is established based on practical engineering experience. Secondly, the cosine similarity function, an effective measure of data sequence similarity, is selected as an objective function according to the observed echo and the established ultrasonic signal model. Thirdly, the artificial bee colony algorithm is selected to optimize the objective function to obtain the optimal estimation parameters of the ultrasonic signal from the noisy ultrasonic echo. Fourthly, the estimation of de-noising ultrasonic signal is reconstructed by the optimal parameters based on the established ultrasonic signal mathematical model. The processing results of simulated ultrasonic echoes and measured ultrasonic echoes show that the proposed method can accurately estimate the parameters of ultrasonic signal from strong background noise whose signal-to-noise ratio is lowest, as low as –10 dB. In addition, compared with the adaptive threshold based wavelet method and empirical mode decomposition method, the proposed method in this paper shows the good de-noising performance. Furthermore, compared with the commonly used exponential model and Gaussian model in numerical and simulation analysis, the proposed dual gaussian attenuation mathematical model of ultrasonic signal in this paper can well simulate the measured ultrasonic signal, with a mean square error of 9.4 × 10–5 and normalized correlation coefficient of 0.98.

Facial expression details are important visual cues to interpret expressions, which are also hard to be synthesized. We propose a novel facial expression transferring method to synthesize realistic colorful facial expressions with source-specific expression details. First, we choose YUV color space to represent the expression images. In Y channel of the color space, the expression image of the source object is transformed into frequency domain through discrete cosine transform. Then, the expression details including micro-expressions of the source object are extracted through analyzing their frequency distribution. Finally, those expression details are stitched smoothly to the target object with Poisson image editing method. The transferred result is combined with U and V channels of the warped target expression to synthesize the colorful realistic expressions of the target object, which reduces the effect of illumination and skin color variations. Experiments on the Multi-PIE database show that our method has higher perceptual quality over the state-of-the-art methods.

To expand mission capabilities needed without a proportional increase in cost or risk for exploration of the solar system, the multiple objective trajectory using low-thrust propulsion and gravity-assist technique is considered. However, low-thrust, gravity-assist trajectories pose significant optimization challenges because of their large design space. Here, the planets are selected as primal scientific mission goals, while the asteroids are selected as secondary scientific mission goals, and a global trajectory optimization problem is introduced and formulated. This multi-objective decision making process is transformed into a bi-level programming problem, where the targets like planets with small subsamples but high weight are optimized in up level, and targets like asteroids with large subsamples but low weight are optimized in down level. Then, the selected solutions for bi-level programming are optimized thanks to a cooperative Differential Evolution (DE) algorithm that is developed from the original DE algorithm; in addition, an sequential quadratic programming (SQP) method is used in low-thrust optimization. This solution approach is successfully applied to the simulation case of the multi-objective trajectory design problem. The results obtained are presented and discussed.

on the basis of population rate equation of multiphoton ionization and fragmentation processes, the controllability of fragmentation process in mpi experiments of polyatomic molecules is analyzed in this paper. curves of ionization efficiency and mean energy of ions versus laser intensity were calculated for different ionization schemes. from the calculation results, we find that only 1+1 ionization scheme, soft ionization and hard fragmentation can be controlled by changing the intensity of ionization laser. for 3+1 ionization scheme, due to additional absorption photons after ionization, the ions have already obtained internal energy about 20 similar to 30ev/per ion even at single ion detection limit. this amount of energy far exceeds the dissociation threshold of the parent ion, so the parent ions formed by ionization can completely dissociate to daughters in the same laser pules. our analyses can explain why parent ions didn't appear in mpi mass spectra of furan molecule at 450 nm.

the multiphoton ionization and fragmentation pathway of furan at 450nm is analyzed on the basis of statistical theory and ladder-switching model. our calculation indicates that fragmentation take.s plase after furan molecules absorb six photons of 450nm, c+ begins to appear after absorption of nine photons, production of c-2(+) ions needs absorption of at least 15 photons. our interesting result is that c+ ions is produced by dissociation of c3h-, ch2+ and c-3(+) ions, not of c-2(-) theoretically computed relative abundance of c+/c-2(+) after absorption 15 photons agrees well with our experimental results.

The collision-free multiphoton ionization and dissociation of jet cooling methyl nitrite (ch3ono) were studied by using intense dye laser around 440nm. no+ ion peak in the tof mass spectrum was obtained under different accelerating electric field and different angle (x) between laser polarization plane and the axis of the flight tube.

By analyzing the key indicators of rotor profile in roots pump, the reason of constraining the Roots pump to improve the efficiency is identified, on this basis, the conventional involutes profile is improved. Compared with the key indicators of the conventional profile, the improvement profile's diameter distance ratio and area coefficient are higher clearly. And the improvement profile is smooth.

To correctly judge transfer type of tool radius compensation, based on the principle of C-function tool radius compensation, the paper study the transfer type of programming route in tool radius compensation. By utilizing directional vector of tool radius compensation, trigonometric function value of the transfer angel is obtained. Finally, the paper summarizes the classification method of transfer type by determining positive and negative of trigonometric function value.