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In this paper, ER50-6 steel was fabricated by wire arc additive manufacturing (WAAM) with an A-W GTAW system. The microstructure, mechanical properties, and corrosion behaviors of ER50-6 steel by WAAM were studied. The results showed that, with the GMAW current increased, from the bottom to the top of the sample, the microstructure was fine ferrite and granular pearlite, ferrite equiaxed grains with fine grains at grain boundaries, and columnar ferrite, respectively. The average hardness in the vertical direction of samples 1# and 2# was 146 and 153 HV, respectively. The hardness of sample 2# increased because of the refinement of grain. The pores in the sample increased as the bypass current increased. The higher bypass current also has a deterioration effect on the corrosion behavior of ER50-6 steel. [ABSTRACT FROM AUTHOR]

Chaos optimization algorithm (COA) usually utilizes chaotic maps to generate the pseudorandom numbers mapped as the decision variables for global optimization problems. Recently, COA has been applied to many single objective optimization problems and simulations results have demonstrated its effectiveness. In this paper, a novel parallel chaos optimization algorithm (PCOA) will be proposed for multiobjective optimization problems (MOOPs). As an improvement to COA, the PCOA is a kind of population-based optimization algorithm which not only detracts the sensitivity of initial values but also adjusts itself suitable for MOOPs. In the proposed PCOA, crossover and merging operation will be applied to exchange information between parallel solutions and produce new potential solutions, which can enhance the global and fast search ability of the proposed algorithm. To test the performance of the PCOA, it is simulated with several benchmark functions for MOOPs and mixed H 2 / H ∞ controller design. The simulation results show that PCOA is an alternative approach for MOOPs. [ABSTRACT FROM AUTHOR]

The slip ratio control is an important research topic in in-wheel-motored electric vehicles (EVs). Traditional control methods are usually designed for some specified modes. Therefore, the optimal slip ratio control cannot be achieved while vehicles work under various modes. In order to achieve the optimal slip ratio control, a novel model predictive controller-based optimal slip ratio control system (MPC-OSRCS) is proposed. The MPC-OSRCS includes three parts, a road surface adhesion coefficient identifier, an operation mode recognizer, and an MPC based-optimal slip ratio control. The current working road surface is identified by the road surface adhesion coefficient identifier, and a modified recursive Bayes theorem is used to compute the matching degree between current road surfaces and reference road surfaces. The current operation state is recognized by the operation mode recognizer, and a fuzzy logic method is applied to compute the matching degree between actual operation state and reference operation modes. Then, a parallel chaos optimization algorithm (PCOA)-based MPC is used to achieve the optimal control under various operation modes and different road surfaces. The MPC-OSRCS for EV is verified on simulation platform and simulation results under various conditions to show the significant performance. [ABSTRACT FROM AUTHOR]

This paper investigates a class of nonlinear time-delayed systems with output prescribed performance constraint. The neural network and DOB (disturbance observer) are designed to tackle the uncertainties and external disturbance, and prescribed performance function is constructed for the output prescribed performance constrained problem. Then the robust controller is designed by using adaptive backstepping method, and the stability analysis is considered by using Lyapunov-Krasovskii. Furthermore, the proposed method is employed into the unmanned helicopter system with time-delay aerodynamic uncertainty. Finally, the simulation results illustrate that the proposed robust prescribed performance control system achieved a good control performance. [ABSTRACT FROM AUTHOR]

Time delay phenomena exist almost everywhere in the actual world and are especially important in the control of an AHV. The small time delay usually ignored in control may cause quite obvious errors in the flight trajectory tracking, because of the extremely high flight speed. In this paper, a new framework of solving a nonlinear input delay regulation problem is proposed for the first time, which is comprised of nonlinear damping controllers, nonlinear disturbance observers, and a nonlinear time delay predictor-based compensator, under the proved separation principle. Then the attitude tracking control of an AHV with a known time-varying input delay is studied based on the proposed design framework. Simulation results show the advantage of the proposed control method. [ABSTRACT FROM AUTHOR]

A 57‐year‐old man suffered chest pain during the COVID‐19 pandemic, but he delayed medical treatment due to fear of infection. After 4 months, symptoms of chest tightness and shortness of breath appeared. Electrocardiogram (ECG) revealed old myocardial infarction; color sonography and myocardial computed tomography revealed apical myocardial defect. He refused surgery and percutaneous transcatheter closure, and follow‐up observation. After 22 months, the symptoms of chest tightness and shortness of breath aggravated. He recovered after percutaneous transcatheter closure, and was discharged. This case shows delayed closure is one of the possible options for patients without severe organ dysfunction or hemodynamic disturbance. [ABSTRACT FROM AUTHOR]

Hyperhomocysteinemia is a risk factor for various cardiovascular diseases. However, the mechanism underlying homocysteine- (Hcy-) induced vascular injury remains unclear. The purpose of the present study was to examine a potential mechanism by which Hcy induced injury in human umbilical vascular endothelial cells (HUVEC). The protein abundance of autophagy-related markers was markedly decreased after Hcy treatment, which was associated with endoplasmic reticulum (ER) stress and apoptosis in HUVECs. Protein expression level of angiotensin II type 1 receptor (AT1 receptor) was dramatically increased in response to Hcy. Valsartan, an AT1 receptor blocker, improved autophagy and prevented ER stress and apoptosis in HUVECs treated with Hcy. Consistent with this, silence of AT1 receptor with siRNA decreased the protein abundance of ER stress markers, prevented apoptosis, and promoted autophagy in HUVECs. Inhibition or knockdown of AT1 receptor was shown to be associated with suppression of p-GSK3β/GSK3β-p-mTOR/mTOR signaling pathway. Additionally, inhibition of autophagy by 3-MA aggravated Hcy-induced apoptosis, while amelioration of ER stress by 4-PBA prevented Hcy-induced injury in HUVECs. Hcy-induced HUVEC injury was likely attributed to AT1 receptor activation, leading to impaired autophagy, ER stress, and apoptosis. [ABSTRACT FROM AUTHOR]

The interest focusing on Eriobotrya japonica leaf triterpene acid (ELTA) has increased recently because of its beneficial effects on health. However, there has been a lack of experimental data on its toxicity. The present study therefore was conducted to evaluate its toxicity in ICR mice. The results showed that ELTA produced neither mortality nor toxicity of the main organs in ICR male and female mice in both acute (0.30, 0.65, 1.39, and 3.00 g·kg−1 body weight) and subacute (150, 300, and 600 mg·kg−1 BW) 28-day toxicity studies. Because of lacking apparently adverse effects found in the hematology, clinical biochemistry, and histopathology evaluation, results of the present study together with the beneficial effects make ELTA as a promising dietary supplement and indicated that ELTA administered orally might have a large safety margin for human. [ABSTRACT FROM AUTHOR]

The problem of state feedback stabilization is studied for networked control systems (NCSs) subject to actuator saturation and network-induced delays. To facilitate the controller design, the NCSs are modeled as a class of discrete-time systems with bounded delays and input saturation. Based on Lyapunov-Krasovskii theory and free weighting matrix approach, the sufficient condition is derived in terms of linear matrix inequality for the asymptotic stability. Finally, the effectiveness of the developed control approach is proved through numerical examples. [ABSTRACT FROM AUTHOR]

Distributed denial of service (DDoS) attacks are the most common means of cyberattacks against infrastructure, and detection is the first step in combating them. The current DDoS detection mainly uses the improvement or fusion of machine learning and deep learning methods to improve classification performance. However, most classifiers are trained with statistical flow features as input, ignoring topological connection changes. This one-sidedness affects the detection accuracy and cannot provide a basis for the distribution of attack sources for defense deployment. In this study, we propose a topological and flow feature-based deep learning method (GLD-Net), which simultaneously extracts flow and topological features from time-series flow data and exploits graph attention network (GAT) to mine correlations between non-Euclidean features to fuse flow and topological features. The long short-term memory (LSTM) network connected behind GAT obtains the node neighborhood relationship, and the fully connected layer is utilized to achieve feature dimension reduction and traffic type mapping. Experiments on the NSL-KDD2009 and CIC-IDS2017 datasets show that the detection accuracy of the GLD-Net method for two classifications (normal and DDoS flow) and three classifications (normal, fast DDoS flow, and slow DDoS flow) reaches 0.993 and 0.942, respectively. Compared with the existing DDoS attack detection methods, its average improvement is 0.11 and 0.081, respectively. In addition, the correlation coefficient between the detection accuracy of attack flow and the four source distribution indicators ranges from 0.7 to 0.83, which lays a foundation for the inference of attack source distribution. Notably, we are the first to fuse topology and flow features and achieve high-performance DDoS attack intrusion detection through graph-style neural networks. This study has important implications for related research and development of network security systems in other fields. [ABSTRACT FROM AUTHOR]

The high-profile attacks of malicious HTML and JavaScript code have seen a dramatic increase in both awareness and exploitation in recent years. Unfortunately, exiting security mechanisms provide no enough protection. We propose a new protection mechanism named PMHJ based on the support of both web applications and web browsers against malicious HTML and JavaScript code in vulnerable web applications. PMHJ prevents the injection attack of HTML elements with a random attribute value and the node-split attack by an attribute with the hash value of the HTML element. PMHJ ensures the content security in web pages by verifying HTML elements, confining the insecure HTML usages which can be exploited by attackers, and disabling the JavaScript APIs which may incur injection vulnerabilities. PMHJ provides a flexible way to rein the high-risk JavaScript APIs with powerful ability according to the principle of least authority. The PMHJ policy is easy to be deployed into real-world web applications. The test results show that PMHJ has little influence on the run time and code size of web pages. [ABSTRACT FROM AUTHOR]

The reference governor strategy is presented for the flight envelope protection control of the aircraft during high angle of attack maneuvers. Limits of key flight parameters and amplitude saturation of control surfaces are explicitly considered by imposing the output and input constraints on the flight system. Firstly, a nominal flight control scheme is designed using eigenstructure assignment approach. The static and dynamic reference governors are discussed for flight envelope protection control of the aircraft during stability-axis roll maneuver. Then, a new reference governor is presented based on step response model. The performance of these reference governors for flight envelope protection is demonstrated and compared by numerical simulations. Results show that the dynamic reference governor and the proposed step response model based reference governor are valid for the flight envelope protection control and the latter is easier to be realized. [ABSTRACT FROM AUTHOR]

Non-small-cell lung cancer (NSCLC) is one of the most frequent solid tumors and regarded as a significant threat to individual health around the world. MicroRNAs (miRs) are recognized as critical governors of gene expression during carcinogenesis, while their clinical significance and mechanism in NSCLC occurrence and development are required for further investigation. In this report, we characterized the functional role of miR-598 and its regulation mechanism in NSCLC. The expression level of miR-598 in NSCLC tissues and cell lines was detected by qRT-PCR. A549 cells were transiently transfected with miR-598 mimics or miR-598 inhibitors. Scratch assay and Transwell assay were used to detect cell transfection, migration, and invasion. Possible binding sites of miR-598 in MSI2 mRNA were predicted by bioinformatics and validated by dual-luciferase reporter gene system. The ability of migration and invasion was examined on cells transfected with MSI2 alone or cotransfected A549 cells with miR-598. The expression of miR-598 in NSCLC tissues was significantly lower than that in adjacent tissues, and the expression of miR-598 in NSCLC cell lines (A549, H1650, and H1299) was also significantly lower than that of normal lung epithelial cell line BEAS-2B. A549 cells were significantly inhibited in migration and invasion after transfection with miR-598 mimics, while miR-598 inhibitors were significantly enhanced in migration and invasion. MSI2 was a direct target gene of miR-598. MSI2 can promote the migration and invasion of A549 cells, but the ability to promote cell migration and invasion was reversed when miR-598 was introduced. In conclusion, miR-598 inhibits the migration and invasion of NSCLC by downregulating the target gene MSI2. [ABSTRACT FROM AUTHOR]

Non-small-cell lung cancer (NSCLC) is one of the most frequent solid tumors and regarded as a significant threat to individual health around the world. MicroRNAs (miRs) are recognized as critical governors of gene expression during carcinogenesis, while their clinical significance and mechanism in NSCLC occurrence and development are required for further investigation. In this report, we characterized the functional role of miR-598 and its regulation mechanism in NSCLC. The expression level of miR-598 in NSCLC tissues and cell lines was detected by qRT-PCR. A549 cells were transiently transfected with miR-598 mimics or miR-598 inhibitors. Scratch assay and Transwell assay were used to detect cell transfection, migration, and invasion. Possible binding sites of miR-598 in MSI2 mRNA were predicted by bioinformatics and validated by dual-luciferase reporter gene system. The ability of migration and invasion was examined on cells transfected with MSI2 alone or cotransfected A549 cells with miR-598. The expression of miR-598 in NSCLC tissues was significantly lower than that in adjacent tissues, and the expression of miR-598 in NSCLC cell lines (A549, H1650, and H1299) was also significantly lower than that of normal lung epithelial cell line BEAS-2B. A549 cells were significantly inhibited in migration and invasion after transfection with miR-598 mimics, while miR-598 inhibitors were significantly enhanced in migration and invasion. MSI2 was a direct target gene of miR-598. MSI2 can promote the migration and invasion of A549 cells, but the ability to promote cell migration and invasion was reversed when miR-598 was introduced. In conclusion, miR-598 inhibits the migration and invasion of NSCLC by downregulating the target gene MSI2. [ABSTRACT FROM AUTHOR]

Unmanned autonomous helicopter (UAH) path planning problem is an important component of the UAH mission planning system. The performance of the automatic path planner determines the quality of the UAH flight path. Aiming to produce a high-quality flight path, a path planning system is designed based on human-computer hybrid augmented intelligence framework for the UAH in this paper. Firstly, an improved artificial bee colony (I-ABC) algorithm is proposed based on the dynamic evaluation selection strategy and the complex optimization method. In the I-ABC algorithm, the following way of on-looker bees and the update strategy of nectar source are optimized to accelerate the convergence rate and retain the exploration ability of the population. In addition, a space clipping operation is proposed based on the attention mechanism for constructing a new spatial search area. The search time can be further reduced by the space clipping operation under the path planning result within acceptable changes. Moreover, the entire optimization process and results can be feeded back to the knowledge database by the human-computer hybrid augmented intelligence framework to guide subsequent path planning issues. Finally, the simulation results confirm that a feasible and effective flight path can be quickly generated by the UAH path planning system based on human-computer hybrid augmented intelligence. [ABSTRACT FROM AUTHOR]

A novel adaptive signal decomposition algorithm, broadband mode decomposition (BMD), is proposed for analyzing nonstationary broadband signals. Unavoidable error will occur when applying former time-frequency methods to broadband signals, which is caused by Gibbs phenomenon and the calculation of extrema. To overcome that problem, BMD is proposed by searching in the associative dictionary that contains both broadband and narrowband signals. The procedure of the proposed method is as follows: First, the collected datasets are analyzed by BMD and the composite multiscale fuzzy entropies (CMFEs) of the obtained effective components are calculated. Then, locality preserving projection (LPP) is applied for further feature extraction. Analysis results show BMD is more effective when drawing broadband feature from noise and BMD is adaptive for the quality monitoring of DPMIG welding. [ABSTRACT FROM AUTHOR]

Background and Objective. The direct-acting antiviral agents (DAAs) antiviral therapy has drastically improved the prognosis of hepatitis C virus (HCV) patients. However, the viral drug resistance-associated variants (RAVs) can limit the efficacy of DAAs. For the HCV-6a is not the predominant prevalent genotype; the data on the prevalence of naturally occurring RAVs in it is scarce. Our study aims to assess the prevalence of RAVs in treatment-naive HCV-6a patients. Methods. Nested PCR assays were performed on 95 HCV-6a patients to amplify HCV viral regions of NS3, NS5A, and NS5B. Results. In NS3/4A region, we detected Q80K in 95.5% isolates (84/88) and D168E in 2.3% isolates (2/88). In NS5A region, we detected Q30R in 93.2% isolates (82/88), L31M in 4.6% isolates (4/88), and H58P in 6.8% isolates (6/88). In NS5B region, we detected A15G in 2.3% isolates (2/88), S96T in 1.1% isolates (1/88), and S282T in 20.7% isolates (17/88) and we detected I482L in 100% isolates (4/4), V494A in 50% isolates (2/4), and V499A in 100% isolates (4/4). Conclusions. RAVs to DAAs preexist in treatment-naive HCV-6a patients. Further studies should address the issue of the impact of RAVs in response to DAA therapies for HCV-6a patients. [ABSTRACT FROM AUTHOR]