The timely and accurate identification of traffic signs plays a significant role in realizing the autonomous driving of vehicles. However, the size of traffic signs accounts for a low proportion of ...the input picture, which increases the difficulty of detection. This paper proposes an improved faster R-CNN traffic sign detection method. ResNet50-D feature extractor, attention-guided context feature pyramid network (ACFPN), and AutoAugment technology are designed for the faster R-CNN model. ResNet50-D is selected as the backbone network to obtain more characteristic information. ACFPN is performed to decrease the loss of contextual information. And data augmentation and transfer learning are adopted to make model training more convenient and time-saving. To prove the availability of the proposed method, we compare it with mainstream approaches (SSD, YOLOv3, RetinaNet, cascade R-CNN, FCOS, and CornerNet-Squeeze) and state-of-the-art methods. Experimental results on the CCTSDB dataset show that the improved faster R-CNN achieves the frames per second of 29.8 and the mean average precision of 99.5%, which is superior to the state-of-the-art methods and more suitable for traffic sign detection. Moreover, the proposed model is extended to the Tsinghua-Tencent 100 K (TT100K) dataset and also achieves a competitive detection result.
This paper proposes a comprehensive model to predict the dynamical coupling behaviors of a rotating rigid manipulator mounted on a rectangular plate, which represents real applications such as ...on-orbit array installation of solar panels. The three-dimensional relationship of displacement field between the end-effector, with arbitrary installation position and azimuth, and the rectangular plate is first established based on spatial descriptions and transformations method. Galerkin’s method is employed and extended to treat the spatial partial derivatives. Then, the governing equation of motion is derived using the Hamilton principle. The dynamic behavior of the system with respect to torque input, the variation of structural parameters as well as installation position and azimuth of the manipulator, is analyzed by simulation, which may provide some principles to control the vibration amplitude of plate and oscillating value of end-effector. Simulation results show that the presented three-dimensional dynamic model is more proper and accurate to describe the dynamic behaviors of system through comparison with two conventional dynamic models, and especially the large structure parameter manipulator is mounted on a rectangular plate.
Nonlinear dynamic of a flexible slender truss-structure mounted manipulator for on-orbit assembly, which can be simplified as a beam-rotating link interaction system, is theoretically investigated. ...The governing partial differential equations (PDEs) of beam with time-varying coefficients is established by using the D'Alembert principle incorporated with the moment balance method where the beam is of a Euler-Bernoulli type and the influence of slope is considered. Such system is a typical parametrically excited system. The multiple scales method is used to determine the approximate solution and the conditions of the primary resonance (<inline-formula> <tex-math notation="LaTeX">\omega _{1}\approx \omega _{ref} </tex-math></inline-formula>) and sub-harmonic resonance (<inline-formula> <tex-math notation="LaTeX">\omega _{1}\approx ~2\omega _{ref} </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">\omega _{1}\approx ~3\omega _{ref} </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">\omega _{1}\approx ~4\omega _{ref} </tex-math></inline-formula>) are obtained. In addition, the nonlinear response, stability and bifurcations for primary and sub-harmonic resonance conditions have also been investigated by varying system parameters. Moreover, the results of some specific conditions by the perturbation analysis are compared with the numerical solution and are found to be in good agreement. This work has certain guiding significance for autonomous on-orbit assembly task and the method can be extended to the more general three-dimensional case.
Abstract
In order to control the rotation of the end effector in a long and narrow space, a spatial parallel mechanism that can realize 2 degrees of freedom rotation is proposed. In this article, the ...forward kinematics model is established according to the constraint conditions of the mechanism’s pose, and the closed vector method is used to obtain the inverse kinematics model. Then based on the kinematics results, the dynamic inverse solution model was established by Newton-Euler method, and the dynamic analysis of the whole mechanism was carried out. Finally, the theoretical calculation results are compared with the simulation results of Adams software to verify the accuracy of the solution process.
•A parametric model for optimum shape design of 3-PPR planar parallel manipulators is presented.•Dexterity and transmission quality are applied to evaluate the performance.•Singular shapes of both ...mobile and base platforms are identified, which must be avoided in design.•Two optimal configurations are obtained from the numerical simulation results.
This work presents a parametric model of 3-PPR11P and R represent prismatic and revolute joints, and an underline letter indicates an actuated joint planar parallel manipulators, aiming to optimize shape design of the base and mobile platforms. The kinematic model is established with shape parameters and motion variables. With the model, the inverse and forward position analyses are carried out, upon which the dexterity performance in terms of conditioning index is evaluated and analyzed. The analysis of global dexterity reveals a number of platform shapes, which lead to singularity in all configurations and must be avoided in design. Further performance evaluation in terms of transmission quality is also presented. Finally, two optimal configurations for the considered manipulators are obtained from the numerical simulation results. A case study is included to demonstrate the dynamics performance with an optimal platform shape design.
Metabolic Syndrome (MS) is a rapidly growing medical problem worldwide and is characterized by a cluster of age-related metabolic risk factors. The presence of MS increases the likelihood of ...developing atherosclerosis and significantly raises the morbidity/mortality rate of acute coronary syndrome (ACS) patients. Early detection of MS is crucial, and biomarkers, particularly blood-based, play a vital role in this process. This cross-sectional study focused on the investigation of certain plasma ceramides (Cer14:0, Cer16:0, Cer18:0, Cer20:0, Cer22:0, and Cer24:1) as potential blood biomarkers for MS due to their previously documented dysregulated function in MS patients. A total of 695 ACS patients were enrolled, with 286 diagnosed with MS (ACS-MS) and 409 without MS (ACS-nonMS) serving as the control group. Plasma ceramide concentrations were measured by LC-MS/MS assay and analyzed through various statistical methods. The results revealed that Cer18:0, Cer20:0, Cer22:0, and Cer24:1 were significantly correlated with the presence of MS risk factors. Upon further examination, Cer18:0 emerged as a promising biomarker for early MS detection and risk stratification, as its plasma concentration showed a significant sensitivity to minor changes in MS risk status in participants. This cross-sectional observational study was a secondary analysis of a multicenter prospective observational cohort study (Chinese Clinical Trial Registry, https://www.who.int/clinical-trials-registry-platform/network/primary-registries/chinese-clinical-trial-registry-(chictr), ChiCTR-2200056697), conducted from April 2021 to August 2022.
The hybrid aircraft model support mechanism is subjected to six directional forces in the experiment, and high spatial stiffness requirement of the parallel part is the guarantee for the stability of ...the aircraft model. The purpose of this paper is to obtain a planar parallel part with relatively good spatial stiffness and to explore the influence of components on the stiffness characteristics. We employed screw theory and virtual work principle to establish the spatial stiffness model of two possible parallel parts for the support mechanism. The stiffness characteristics of the two parallel mechanisms were evaluated by a desired trajectory sub-workspace deformation distribution and two novel stiffness indexes. According to deformation distributions of the sub-workspace, the deformation of typeI is smaller than that of type II. The proposed indexes indicate that the influence of the hydraulic cylinder range on the stiffness of type II is more significant; RVR of ASI is 263.5%, RVR of CSI is 18.1%. These reveal type I has better spatial stiffness than type II. The reason is that the guideway of type I provides a part of the ability to resist external forces.
Weaning is an important period that affects the performance of piglets. However, the regulation of dietary amino acid levels is considered to be an effective way to alleviate the weaning stress of ...piglets. N-carbamylglutamate (NCG) plays an important role in improving the growth performance and antioxidant capacity of animals. A total of 36 weaned piglets were randomly assigned to two treatment groups, a control group (CON) and a 500 mg/kg NCG group (NCG), and the experiment lasted for 28 days. The results show that the NCG treatment group showed an increased 0-28 days average weight gain and average daily feed intake, and also increased contents of GLU and HDL, and lower SUN in serum, and an upregulation of the expression of the amino acid transporters SNAT2, EAAC1, SLC3A1, and SLC3A2 mRNA in the jejunum (
< 0.05), as well as an increased villus length and VH:CD ratio, and claudin-1, occludin, and ZO-1 mRNA expression in the jejunum (
< 0.05). The NCG treatment group showed an increased content of GSH-Px in serum and T-AOC and SOD in the jejunum, and a lower content of MDA (
< 0.05); and the upregulation of the mRNA expression related to antioxidant enzymes (CAT, SOD1, Gpx4, GCLC, GCLM and Nrf2, AhR, CYP1A1) in the jejunal mucosa (
< 0.05). In addition, compared with the control group, the NCG treatment group saw an upregulation in the mRNA expression of IL-10 and a decrease in the expression of IL-1β and IL-4 in the jejunal mucosa (
< 0.05). In summary, the results of this study suggest that NCG improved growth performance and jejunal morphology, improved the jejunal transport of amino acids related to the ornithine cycle, and improved the antioxidant capacity in weaned pigs.
Amygdala serves as a highly cellular, heterogeneous brain region containing excitatory and inhibitory neurons and is involved in the dopamine and serotoninergic neuron systems. An increasing number ...of studies have revealed the underpinned mechanism mediating social hierarchy in mammal and vertebrate, however, there are rare studies conducted on how amygdala on social hierarchy in poultry. In this study, we conducted food competition tests and determined the social hierarchy of the rooster. We performed cross-species analysis with mammalian amygdala, and found that cell types of human and rhesus monkeys were more closely related and that of chickens were more distant. We identified 26 clusters and divided them into 10 main clusters, of which GABAergic and glutamatergic neurons were associated with social behaviors. In conclusion, our results provide to serve the developmental studies of the amygdala neuron system and new insights into the underpinned mechanism of social hierarchy in roosters.
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•We obtain a comprehensive cellular atlas of the domestic chicken amygdala cell type•We performed found out that cell types of human and rhesus monkeys were more closely related and that of chickens were more distant from them•We identified 26 clusters including two neurons and eight non-neurons clusters. Of which, the GABAergic and glutamatergic neurons are considered as main neurons mediating the social hierarchy in chickens•RHOB and CDK14 might be involved with the role of the mechanism of social hierarchy in chickens
Neuroscience; Omics; Transcriptomics
Dominance hierarchy exists in social animals and shows profound impacts on animals' survival, physical and mental health, and reproductive success. Aggressive interaction, as the main indicator used ...to calculate social hierarchy, however, is not found in some female animals. In this study, we aimed to figure out the establishment of social hierarchy in hens that almost perform aggressive behaviors and investigated the interactions of social hierarchy with production performance and gut microbiome. Forty 49-day-old Qingyuan hens were randomly divided into four groups. The social hierarchy of hens was calculated by the relative position around the feeder. The rank 1 (R1), R2, R3, R4, R5, R6, R7, R8, R9, and R10 birds were determined in ascending order. Then, R1 and R2 birds (four duplicates,
= 8) were named as the high-ranking hens (HR) group, while R9 and R10 individuals were named as the low-ranking hens (LR) group (four duplicates,
= 8). The heart index (
= 0.01), number of visits per day, daily feed intake, and occupation time per day were higher in the HR group than LR group, but the LR group had a higher feed intake per visit than the HR group. The alpha diversity was significantly lower in the HR group than the LR group (
= 0.05). The relative abundance of phylum
was higher while that of phylum
was lower in the HR group than LR group (
< 0.05). At the genus level, the relative abundance of
,
, and
were higher in HR group than in LR group. The relative abundance of
,
,
, and
was higher in the LR group than HR group (
< 0.05). In conclusion, the rank of hens could be calculated by the relative position around the feeder when they compete for food. The dominant hens have a versatile. Moreover, they are more vigilant and have priority when foraging. Low-ranking hens adopt strategies to get enough food to sustain themselves. Hens of high-rank possess beneficial bacteria that use favorable substances to maintain the balance of the gut environment.
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