Investigation on the cushioning characteristic of cat paw pad in motion: A synergy of its histological structure and kinematic mechanical characteristics

The paw pads of cats had evolved to exhibit strong cushioning characteristic that could attenuate ground impacts effectively in motion. The purpose of this study was to explore the realization mechanism of the cushioning characteristic of paw pads. Ten adult domestic cats were included for this study and three experimental investigations, i.e histological experiment of tissues, ground reaction forces experiment and contact strain experiment of the paw pads in motion, were undertaken. The results of the study proved that the realization mechanism of the cushioning characteristic of the paw pads was a result of synergy of multiple factors. First, on the histological level, a multi-layer structure of the paw pads, which were made of the stratified epithelium layer, dermis layer and subcutaneous tissue layer, helped to achieve outward and inward contact stress and strain decaying. Next, the results from the ground reaction forces experiment showed that the fore-pads played a more important role than that of the hind in achieving cushioning characteristic. And the contact strain experiment revealed that, the movement characteristics of front-back and left-right swing deformation occurred in paw pads, especially in metacarpal pad, was beneficial to the exertion of the cushioning energy storage. The histological structure of paw pads revealed its natural advantage to realize the cushioning characteristic, but the mechanical characteristics were the acquired adaptive habits responsible for the realization of cushioning characteristic. These exploratory investigations gave the insights into the cushioning characteristic of the cat paw pad

Small-Scale Foreign Object Debris Detection Using Deep Learning and Dual Light Modes

The intrusion of foreign objects on airport runways during aircraft takeoff and landing poses a significant safety threat to air transportation. Small-scale Foreign Object Debris (FOD) cannot be ruled out on time by traditional manual inspection, and there is also a potential risk of secondary foreign body intrusion. A deep-learning-based intelligent detection method is proposed to solve the problem of low accuracy and low efficiency of small-scale FOD detection. Firstly, a dual light camera system is utilized for the collection of FOD data. It generates a dual light FOD dataset containing both infrared and visible light images. Subsequently, a multi-attention mechanism and a bidirectional feature pyramid are integrated into the baseline network YOLOv5. This integration prioritizes the extraction of foreign object features and boosts the network’s ability to distinguish FOD from complex backgrounds. Additionally, it enhances the fusion of higher-level features to improve the representation of multi-scale objects. To ensure fast and accurate localization and recognition of targets, the Complete-IoU (CIoU) loss function is used to optimize the bounding boxes’ positions. The experimental results indicate that the proposed model achieves a detection speed of 36.3 frame/s, satisfying real-time detection requirements. The model also attains an average accuracy of 91.1%, which is 7.4% higher than the baseline network. Consequently, this paper verifies the effectiveness and practical utility of our algorithm for the detection of small-scale FOD targets

Research on Vibration Reduction Method of Nonpneumatic Tire Spoke Based on the Mechanical Properties of Domestic cat’s Paw Pads

Although there is no risk of puncture, the vibration problem caused by discontinuous structures limits nonpneumatic tire development (NPT). The vibration reduction of nonpneumatic tires is a solvable urgent problem. This current study analyzed the dynamic grounding characteristics and the vibration reduction mechanism of the cat’s paw pads and then applied the mechanical properties to the bionic design of nonpneumatic tire spokes to solve the vibration problem. Domestic cats’ paw pads’ dynamic grounding characteristics were determined using the pressure-sensitive walkway, high-speed camera, and VIC-2D. The results indicated that the mechanical characteristics of swing deformation of paw pads during the grounding process attenuated the grounding stress and buffered the energy storage to achieve the vibration reduction effect. According to the similarity transformation, a finite element model of NPT that could accurately reconstruct the structure and realistically reflect the load deformation was employed. The structure design of asymmetric arcs on the spokes’ side edges was proposed, and it can effectively reduce the radial excitation force of NPT. The three parameters, the asymmetric arc, the thickness, and the curvature of spokes, were used as design variables to maximize the vibration reduction. The orthogonal experimental, the Kriging approximate model, and the genetic algorithm were carefully selected for optimal solutions. Compared with the original tire, the results showed that peak amplitude 1, peak amplitude 2, and the root square of the optimized tire’s amplitudes were reduced by 76.07%, 52.88%, and 51.65%, respectively. These research results offer great potential guidance in the design of low-vibration NPT

Adaptability of Kinetic Parameters to a Narrow Speed Range in Healthy Free-Moving Cats

Ground reaction force and impulse measurement is an established method for assessing the physical condition and efficacy of treatment for some animals. The primary aim of this study was to quantify the kinetic parameters of the limbs of healthy cats at different speeds. The second aim was to determine the explicit relationship between the kinetic parameters and speed. Peak vertical force (PVF), vertical impulse (VI), stance phase duration (SPD), and paw contact area (PCA) of each limb (forelimb, F; hindlimb, H) of seven clinically healthy, client-owned cats were recorded in the speed interval of 0.5–2.5 m/s. The cats were encouraged to pass by a pressure-sensitive walkway with different speeds. The results revealed that there were no significant differences in any of the tested parameters between the left and right forelimbs and the left and right hindlimbs. Means and regression formulas of the kinetic parameters with speed were obtained. It was evident that PVF-F and PVF-H increased linearly with speed, while VI-F and VI-H decreased exponentially. SPD-F was practically equal to SPD-H and exponentially decreased with speed. PCA-F increased linearly with speed, and PCA-H was almost invariable. Pressure-sensitive walkway is a suitable and convenient equipment for assessing the kinetic parameters of cats. Variation of these kinetic parameters with speed can be explained by the functional difference for forelimb-dominant and hindlimb-driven

Design of Two-Wheeled Motorcycle Tire Crown Contour Bioinspired by Cat Paw Pads

The grip force of tires is crucial for vehicle security and drivability under different driving conditions. A small contact area and stress concentration in the contact patch of two-wheeled motorcycle (TWM) tires result in a reduction in grip performance and wear resistance. Even worse, improving the grip and wear resistance together is difficult to achieve. The purpose of the current study is to analyze the dynamic grounding characteristics and geometry of a cat paw pad and then apply its structure to the TWM tire to improve the contact area and wear resistance under different operating conditions. A nonlinear finite element tire model that could accurately reconstruct the tire structure and realistically reflect the mechanical response to different loads was employed. Then, the accuracy of the tire model was validated by a static test with a control tire. For cats, the dynamic grounding characteristics and topology of paw pads were determined using a pressure-sensitive walkway and a three-dimensional (3D) laser scanner. The results indicated that the cat forepaw third pad (CFTP) exhibited excellent grip capacity. According to similarity transformation, a bionic tire crown was designed according to the lateral fitting curve of the CFTP. Comparative results showed the enlargement of the contact area and decreases in peak pressure and frictional energy rate for the bionic tire under different conditions. With these improvements, the grip performance was improved, and the service life was extended synchronously. These research results can be applied for the design of TWM tires, especially cross-country motorcycle tires

Intralesional Interstitial Injection of Bleomycin for Management of Extracranial Arteriovenous Malformations in Children

ABSTRACT: Background: Despite many advances in the treatment for extracranial arteriovenous malformations (AVMs), they still result in tedious dissection and potential unacceptable complications, particularly in children. Therefore, this study aimed to investigate the efficacy and safety of intralesional interstitial injection of bleomycin for the treatment of children with AVMs. Methods: A total of 10 children (6 boys and 4 girls) with AVMs were treated with serial interstitial bleomycin injections between May 2014 and January 2017. Maximum single doses of 15 U and 1 U/kg per session were administered for six sessions at a 1-month interval. Therapeutic effectiveness was evaluated and classified into four categories: complete response (CR), partial response (PR), no response, and worsening at 3 months after the last session. Further clinical follow-up outcomes were classified as improved, stable, or aggravated. Adverse events were recorded according to the Society of Interventional Radiology classification. Results: All 10 children completed the sessions and follow-ups. CR occurred in 3 (30%) patients, PR in 6 (60%), and no response in 1 (20%). Minor complications (class A) included maculopapular rash, bulla, vomiting, and hyperpigmentation, whereas no major complications occurred. Conclusion: Intralesional interstitial injection of bleomycin is a feasible approach for the treatment of AVMs in children and provides safe and effective outcomes. This method may be an earlier treatment alternative in children to prevent potential destructive progression, considering the serious complications of currently available therapeutic methods