Prone position ventilation (PPV) is attracting more and more attention as a part of mechanical ventilation treatment, and relevant consensus and guidelines have been formulated. Prone position therapy (PPT) is widely used in the clinical diagnosis and treatment of burns. Compared with traditional PPV, burn PPT is significantly different in indications, process details, precautions, etc. Therefore, the Burn and Trauma Branch of Chinese Geriatric Society and Critical Care Group of Chinese Burn Association collected the evidence,led the formulation of
To prepare graphene oxide (GO)-containing gelatin methacrylate anhydride (GelMA) hydrogel and to investigate the effects of in situ photopolymerized GO-GelMA composite hydrogel in wound vascularization of full-thickness skin defect in mice.
The experimental study method was used. The 50 μL of 0.2 mg/mL GO solution was evenly applied onto the conductive gel, and the structure and size of GO were observed under field emission scanning electron microscope after drying. Human skin fibroblasts (HSFs) were divided into 0 μg/mL GO (without GO solution, the same as below) group, 0.1 μg/mL GO group, 1.0 μg/mL GO group, 5.0 μg/mL GO group, and 10.0 μg/mL GO group treated with GO of the corresponding final mass concentration, and the absorbance value was detected using a microplate analyzer after 48 h of culture to reflect the proliferation activity of cells (
GO had a multilayered lamellar structure with the width of about 20 μm and the length of about 50 μm. The absorbance value of HSFs in 10.0 μg/mL GO group was significantly lower than that in 0 μg/mL GO group after 48 h of culture (
GO with mass concentration lower than 10.0 μg/mL had no adverse effect on proliferation activity of HSFs, and GO of 0.1 μg/mL can promote the migration of HSFs and HUVECs, and can promote the secretion of VEGF in HSFs. In situ photopolymerized of GO-GelMA composite hydrogel dressing can promote the wound neovascularization of full-thickness skin defect in mice and increase wound blood perfusion in the early stage, with GO showing an enrichment effect on angiogenesis, and the mechanism may be related to the role of GO in promoting the secretion of VEGF by wound cells.
To explore the heterogeneity and growth factor regulatory network of dermal fibroblasts (dFbs) in mouse full-thickness skin defect wounds based on single-cell RNA sequencing.
The experimental research methods were adopted. The normal skin tissue from 5 healthy 8-week-old male C57BL/6 mice (the same mouse age, sex, and strain below) was harvested, and the wound tissue of another 5 mice with full-thickness skin defect on the back was harvested on post injury day (PID) 7. The cell suspension was obtained by digesting the tissue with collagenase D and DNase Ⅰ, sequencing library was constructed using 10x Genomics platform, and single-cell RNA sequencing was performed by Illumina Novaseq6000 sequencer. The gene expression matrices of cells in the two kinds of tissue were obtained by analysis of Seurat 3.0 program of software R4.1.1, and two-dimensional tSNE plots classified by cell group, cell source, and gene labeling of major cells in skin were used for visual display. According to the existing literature and the CellMarker database searching, the expression of marker genes in the gene expression matrices of cells in the two kinds of tissue was analyzed, and each cell group was numbered and defined. The gene expression matrices and cell clustering information were introduced into CellChat 1.1.3 program of software R4.1.1 to analyze the intercellular communication in the two kinds of tissue and the intercellular communication involving vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), epidermal growth factor (EGF), and fibroblast growth factor (FGF) signal pathways in the wound tissue, the relative contribution of each pair of FGF subtypes and FGF receptor (FGFR) subtypes (hereinafter referred to as FGF ligand receptor pairs) to FGF signal network in the two kinds of tissue, and the intercellular communication in the signal pathway of FGF ligand receptor pairs with the top 2 relative contributions in the two kinds of tissue. The normal skin tissue from one healthy mouse was harvested, and the wound tissue of one mouse with full-thickness skin defect on the back was harvested on PID 7. The multiple immunofluorescence staining was performed to detect the expression and distribution of FGF7 protein and its co-localized expression with dipeptidyl peptidase 4 (DPP4), stem cell antigen 1 (SCA1), smooth muscle actin (SMA), and PDGF receptor α (PDGFRα) protein.
Both the normal skin tissue of healthy mice and the wound tissue of full-thickness skin defected mice on PID 7 contained 25 cell groups, but the numbers of cells in each cell group between the two kinds of tissue were different. Genes
In the process of wound healing of mouse full-thickness skin defect wound, dFbs are highly heterogeneous, act as potential major secretory or receiving cell populations of a variety of growth factors, and have a close and complex relationship with the growth factor signal pathways. FGF7-FGFR1 signal pathway is the main FGF signal pathway in the process of wound healing, which targets and regulates multiple dFb subgroups.
To investigate the effects of methacrylic anhydride gelatin (GelMA) hydrogel loaded with silver and recombinant human basic fibroblast growth factor (rh-bFGF) on deep partial-thickness burn wounds in rabbits.
The experimental research method was adopted. Low-concentration GelMA materials, medium-concentration GelMA materials and high-concentration GelMA materials containing different concentrations of methacrylic anhydride (MA) were prepared, after adding photoinitiator, low-concentration GelMA hydrogels, medium-concentration GelMA hydrogels, and high-concentration GelMA hydrogels were obtained, respectively. The nuclear magnetic resonance spectroscopy was performed to detect the hydrogen nuclear magnetic resonance spectra of the above-mentioned three concentrations of GelMA materials, and to calculate the degree of substitution according to the spectrum diagram. The three-dimensional microstructure and pore size of 3 types of above-mentioned GelMA hydrogels were detected by field emission scanning electron microscopy (FESEM), with 9 samples measured. According to the selected concentration of MA, ten kinds of solutions of GelMA with different concentration of silver (silver-containing GelMA) were synthesized, and the silver-containing GelMA solution of each concentration was divided into three parts, and then exposed to ultraviolet light lasting for 20, 25, and 35 s, respectively. After adding photoinitiator,the corresponding silver-containing GelMA hydrogels were obtained. The residual degradation rate of silver-containing GelMA hydrogel with different photocrosslinking times was detected by collagenase degradation method at degradation of 12, 24, 36, and 48 h; and the time required for complete degradation was detected, and the sample number was 5. The inhibition zone diameter of GelMA hydrogel under above screened photocrosslinking times containing 10 concentrations of silver against
The substitution degree among low-concentration GelMA materials, medium-concentration GelMA materials, and high-concentration GelMA materials was significantly different (
The medium-concentration GelMA hydrogel has good physical and chemical properties in terms of swelling and degradability. The screened silver-containing GelMA hydrogels had the lowest antibacterial activity and the lowest drug loading concentration. Composite hydrogel can significantly shorten the healing time of deep partial-thickness burn wounds in rabbits.
To investigate the effects and molecular mechanism of exogenous L-carnitine on hepatic pyroptosis mediated by excessive endoplasmic reticulum stress in severely scald rats.
The experimental research method was adopted. According to the random number table (the same group method below), fifteen female Sprague Dawley rats aged 6-8 weeks were divided into sham-injury group, scald alone group, and scald+carnitine group (with 5 rats in each group), and full-thickness scald of 30% total body surface area were made on the back of rats in scald alone group and scald+carnitine group, and rats in scald+carnitine group were additionally given intraperitoneal injection of L-carnitine. At post injury hour (PIH) 72, The levels of aspartate aminotransferase (AST) and alanine dehydrogenase (ALT) of biochemical indicators of liver injury were detected by automatic biochemical analyzer with the sample number of 5. At PIH 72, liver tissue damage was detected by hematoxylin-eosin staining. At PIH 72, The mRNA levels of nucleotide-binding oligomerization domain-containing protein-like receptor family pyrin domain containing 3 (NLRP3), cysteine aspartic acid specific protease 1 (caspase-1), gasderminD (GSDMD), and interleukin 1β(IL-1β) in liver tissue as pyroptosis-related markers and glucose regulatory protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP) in liver tissue as endoplasmic reticulum stress-related markers were detected by real-time fluorescence quantitative reverse transcription polymerase chain reaction (RT-qPCR). Protein expression levels of GRP78, CHOP, NLRP3, caspase-1, caspase-1/p20, GSDMD-N, and cleaved IL-1β in liver tissue were detected by Western blotting, and the sample numbers were all 5. HepG2 cells as human liver cancer cells were divided into dimethyl sulfoxide (DMSO) group, 0.1 μmol/L tunicamycin (TM) group, 0.2 μmol/L TM group, 0.4 μmol/L TM group, and 0.8 μmol/L TM group and were treated accordingly. After 24 h of culture, cell viability was detected by cell counting kit 8, and the intervention concentration of TM was screened, and the sample number was 5. HepG2 cells were divided into DMSO group, TM alone group, and TM+carnitine group, and treated accordingly. After 24 h of culture, the protein expression levels of GRP78, CHOP, NLRP3, caspase-1, caspase-1/p20, GSDMD-N, and cleaved IL-1β in cells were detected by Western blotting, and the sample numbers were all 3. Data were statistically analyzed with one-way analysis of variance and least significant difference-
At PIH 72, the AST and ALT levels of serum in scald alone group were (640±22) and (157±8) U/L, which were significantly higher than (106±13) and (42±6) U/L in sham-injury group, respectively, with
In severely scald rats, exogenous L-carnitine may play a protective role against liver injury by inhibiting the pathways related to excessive endoplasmic reticulum stress-mediated pyroptosis.
The problem of pedestrian-vehicle conflict in intelligent driving scenes is closely related to pedestrian crossing behavior. In order to enable advanced driving assistance system (ADAS) to have the function of identifying pedestrian crossing intentions and raising advanced warning of pedestrian-vehicle collision events, a pedestrian crossing intention recognition framework based on graph representation learning (GRL) method is proposed. It uses open source tools to generate pedestrian skeleton information. Then it establishes a graph model to represent the characteristics of pedestrian action sequence by taking the skeleton key points of each frame of pedestrian within a sequence as nodes, as well as taking the natural connections, the topological correlations and time-domain relationships between skeleton joints as edges. Taking the graph structure data as the input, the pedestrian crossing intention recognition model is trained based on support vector machine (SVM). The results show that the classification accuracy of pedestrian crossing intention can reach 90.29%. The proposed method can effectively identify the pedestrian crossing intention, which is of great significance to improve the safety of intelligent vehicle decision-making.
To achieve dynamic real-time obstacle avoidance of unmanned vehicles, a local obstacle avoidance path planning algorithm was proposed based on artificial potential field method. Firstly, improving the potential field environment and the potential field force were arranged in the new method to solve the local minimum value and target unreachable problem of the traditional potential field method. And then, considering the safety of vehicle collisions, the working conditions of lateral dynamic obstacles and the same direction dynamic obstacles were analyzed, and a dynamic window method was used for real-time dynamic obstacle avoidance planning. To ensure path flatness and traceability, a BSL curve was used to smoothing the planned path. Finally, the proposed control algorithm was verified under the co-simulation platform of CarSim and Matlab/Simulink. The simulation results show the effectiveness, safety and traceability of the planning algorithm for obstacle avoidance.
The accuracy and robustness of intelligent vehicle trajectory tracking are important characteristic of vehicle motion control performance. Many Researches of tracking control based on path preview information have significantly improved vehicle performance. However, the insufficient response of the vehicle steering system have caused many difficulties for the vehicle to accurately track the reference trajectory based on the preview information in real time. To solve this problem, introducing state of the steering system in real time, a dual closed-loop trajectory tracking control structure was established to ensure the robustness of the intelligent vehicle trajectory tracking control algorithm for the insufficient response of the steering system. Concretely, in the outer loop of this structure, a model predictive control method was used to solve the optimal steering angle based on preview information. And in the inner loop of this structure, a PID method was used to design a feedback control law based on steering state error to compensate for insufficient steering response. Coupling control input, the dual closed-loop structure can ensure the robust optimal tracking control of the vehicle. Finally, the effectiveness of the dual closed-loop control structure was verified in Carsim and Simulink co-simulation.
Vehicle mass-centroid sideslip angle plays an important role in the judgment of vehicle lateral stability. Overestimation or underestimation of the sideslip angle will affect the stability control system. At present, the estimation of sideslip angle still has a large error and has not been practically used in engineering. In order to reduce the observation error and improve the practicability of the estimation system, a robust fuzzy second-order sliding-mode observer was proposed to calculate the observed value of the sideslip angle, and the integral value of the sideslip angle was calculated by using the inertial measurement unit signal. Then, the advantages and disadvantages of the two estimation methods were analyzed, and the observation estimation value and the integral estimation value of the sideslip angle were extensively fused to realize the correction of the observation value with the sensor signal. Finally, the estimation method of sideslip angle was verified by Simulink/TruckSim simulation and hardware in the loop simulation. The effectiveness of the proposed method is proved based on the control effect in real vehicle test under the constant circular acceleration condition. The results show that the proposed method can accurately reflect the actual sideslip angle, and has good reliability and practicability.
In order to improve the reliability of unmanned-vehicle control system, a fault-tolerant control method was proposed for unmanned vehicle path following, considering the influence of both steering control system fault and unknown disturbance on path-tracking effect of unmanned vehicle. Firstly, analyzing the input fault of steering control system and characterizing nominal fault from the unknown system interference, a mathematical model was established. And then, a differential equation of nominal fault was constructed with a high-order sliding mode observer, and the estimation method of vehicle sideslip angle and nominal fault was designed based on adaptive cubature Kalman filter, providing reliable information source for fault-tolerant control of unmanned vehicle. Finally, a fault-tolerant controller was designed based on sliding mode control method for path following of unmanned vehicle to prove its convergence. The results of co-simulation and hardware in the loop test show that, the proposed estimation method can get accurate and reliable estimation results of vehicle sideslip angle and nominal fault, and compared with no fault-tolerant control, the designed fault-tolerant path following controller can significantly improve the control performance of vehicle in the face of fault and interference, and at the same time ensure the path following ability and its own stability of vehicle.
Intelligent vehicles have achieved a considerable development in technologies and can fulfill the basic functions of autonomous driving in a limited closed environment. However, results of actual road tests show that the current technologies of intelligent vehicles still have many limitations and their large-scale application in complex urban and off-road environments still faces many challenges. As one of the key technologies, the motion planning and control technology has basically formed a complete theoretical system and has been widely applied in engineering. However, the traditional methods still have some defects in practical application, such as the inability of understanding dynamic and complex scenes, poor adaptability for different scenes, high complexity of the model, and difficulty in parameter tuning. Due to the strong ability in knowledge representation and model fitting, machine learning methods have been widely applied in perception and navigation technology for intelligent vehicles. In order to solve the problems of generalization and applicability in traditional motion planning and control techniques, many researchers have also devoted themselves to exploring the usage of deep learning, reinforcement learning, and so on machine learning methods in motion planning and control policy for intelligent vehicles. In this paper, machine learning-based methods were reviewed for motion planning and control in intelligent vehicles, analyzing the existing policy learning methods for motion planning and control from three aspects, including basic framework, basic learning paradigms, and different planning and control methods based on learning. Finally, the research status and future development directions were summarized and prospected.
In this article, the fuel economy of lane changing trajectories was studied based on the space and trajectory curvature constraints of intelligent vehicle. Based on an engine transient fuel consumption model, the most economical speed for driving on the flat roads was calculated, and the third-order Bezier lane changing trajectory model was established for various constraints. The results of Matlab/Simulink and Carsim co-simulation verification show that, the fuel consumption of the Bezier lane changing trajectory developed in the paper is 3.49% and 0.77% less than the existing sin-tanh and
Aerial-ground platform has multi-domain maneuverability and can adapt to various complex environments through the conversion of land and air mode, but the land and air mode conversion is mostly static take-off or hovering descent, which is not conducive to the full display of the maneuverability of the aerial-ground platform. Aiming at a deformable aerial-ground amphibious platform with deflectable power mechanism, the flight dynamics model of the aerial-ground platform was established based on the Newton-Euler equation, the time sequence of the deflection angle was planned to obtain dynamic constraints, and the relative time optimal objective function was determined. The fifth-order polynomial was used to fit the two-dimensional trajectory, and the trajectory tracking controller was designed according to the PID control method, and the trajectory planning and control simulation were carried out. The results show that the dynamic switching time is shortened by 23.02% compared with the static switching time, the dynamic switching planning trajectory is smooth, there is no overshoot in the altitude direction, and the controller can better track the target flight trajectory.
In order to quantitatively describe the damage degree and failure process of the cemented backfill under dynamic load, numerical simulation software was used to perform SHPB dynamic impact on the cemented backfill, and the feasibility of the numerical simulation method was verified by the indoor SHPB impact test results. For 4 kinds of cemented fillings (with cement-sand mass ratios of 1∶4, 1∶6, 1∶8 and 1∶10 respectively) made under different impact speeds (1.5, 1.7, 1.8, and 2.0 m/s), the micro-crack density method was used to define the damage variable value
In order to solve the problem of complex rotor structure, deficient mechanical strength, and difficulty in high-speed applications of synchronous reluctance motor, a new type of synchronous switched reluctance motor (SSRM) was proposed. Taking the both advantages of switched reluctance motor and a synchronous reluctance motor, the new motor rotor was designed with several excellences including simple manufacturing process for punching sheet, strong reliability, suitable for high-speed fields, high salient pole rate and strong torque output capability. Based on the electromagnetic design of the new SSRM, the parameters of the motor were optimized by the orthogonal method, taking the average torque, torque ripple and motor efficiency as the optimized performance indicators. The finite element simulation and experiment results show that the optimized SSRM possesses the characteristics of low torque ripple and high efficiency.
Micro-expression apex frame contains abundant micro-expression information. In order to spot the apex frame accurately, a neural network classification was proposed based on optical flow characteristics. Taking prior knowledge as rules, a detection method was designed to realize micro-expression apex frame spotting. Firstly, optical flow information was extracted from the image in a fixed size sliding window. And then, the spatial and temporal features of optical flow information in x and y directions was extracted and classified based on dual input network. Finally, according to the trade-off rules based on prior knowledge of micro expression, a post-processing was carried out to improve the detection accuracy. The experimental results on data set CASMEⅡtesting show that the apex spotting rate (ASR) and
Due to the insufficient analysis on the specific impact of dual stealth aircraft formation self-defense coherent jamming on monopulse radar and the lack of rational evaluation to error effectiveness, considering the random characteristics of the phase difference between the dual aircraft echoes, a dual stealth aircraft coherent jamming model and an angle error evaluation model were established. Setting the track of dual aircraft and extracting the dynamic RCS of dual aircraft, a calculation formula was deduced for the random angle error caused by the dual aircraft coherent jamming under the echo. And then several processes were carried out including solving the first order digital characteristics of random angle errors, establishing the angle error validity evaluation criterion according to the miss distance, and calculating the validity probability of angle error. Simulation results show that the angle error caused by the dual stealth aircraft coherent jamming is relatively larger and the random fluctuation is weak. The stable jamming effect and large error validity probability to radar can insure the security of formation penetration.
To indicate clearly the dynamic response mechanism and deformation strengthening mechanism of shipbuilding steel materials under ultra-high strain rate, the free surface velocity-time curve of E36 shipbuilding steel under impact pressure of 10, 20 and 30 GPa was measured through one-dimensional plate impact test, and the Hugoniot elastic limit and spall strength of E36 shipbuilding steel were calculated. ANSYS software was used to simulate the temperature field under different impact pressure. The damage evolution law and deformation strengthening mechanism of E36 shipbuilding steel under high-pressure impact were studied based on SEM, TEM and other techniques. The results show that the spalling occurs in the materials under the above mentioned impact pressures, and the damage mechanism is the nucleation, growth and aggregation of micropores and microcracks. With the increase of impact pressure, the Hugoniot elastic limit of E36 shipbuilding steel change little while the spalling strength gradually increases. Phase transformation strengthening, dislocation strengthening and twin strengthening are the main strengthening mechanisms of E36 shipbuilding steel under high pressure and high strain rate.
In view of the phase transition phenomenon of solid⁃liquid⁃vapor coupling when ice crystals moved in a warm environment,the phase transition model and calculation method of ice crystals were established based on Eulerian method.The melting phase transition processes of ice crystals under forced convection were calculated,and the comparison with the experimental results verified the accuracy of the movement phase transition model and calculation method.The thermodynamic characteristics of ice crystals moving around the NACA0012 airfoil were calculated,and the motion characteristics of ice crystals in a warm environment and the melting ratio were analyzed when they reached the impact surface.The influences of initial particle size,initial particle sphericity,air relative humidity and temperature on the movement phase transition were studied.The results showed that the ice crystal particle movement phase transition model can effectively evaluate the ice crystal icing risk,and the melting rate of ice crystal particles mainly counted on the particle diameter,sphericity,airflow temperature and humidity.When the air temperature was 288 K,the melting time of ice crystal particles was 27.5 s,while the melting time was only 5.2 s when the air temperature was 302 K under the same conditions.
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