Bionic Ring Grooves Design and Experiment of the Suction Cup Applied in Oil-Immersed Substrate

The vacuum suction cup is often used as an end effector and widely used in wall-climbing operations. However, there are few vacuum suction cup designs and applications for oil-immersed substrates. Inspired by the surface morphology of the octopus sucker, bionic suction cups with different numbers, diameters, and spacings of the ring grooves were designed. Their normal adsorption force was evaluated on the untreated and polished steel plate in oil. The test results showed that ring grooves positively affected the adsorption force. The bionic suction cup with a groove number of 3, a diameter of 0.5 mm, and a spacing of 3 mm was the most excellent in the test. It achieved normal adsorption forces of 54.83 ± 0.48 N and 43.89 ± 0.69 N on the untreated and polished steel plate. Compared with the standard suction cup, it increased by 32.31% and 12.28% on the untreated and polished steel plate. The regression model between the normal adsorption force and design factors was established based on the adsorption force test results, and the influence law of the ring groove structure parameters on the adsorption force of suction cups on oil-immersed substrates was analyzed. The order of significant effects of groove design parameters on normal adsorption forces was groove diameters, spacings, and numbers. The finite element analysis (FEA) results show that the ring grooves could significantly increase the contact pressure, frictional stress, and sliding distance between the suction cup and the substrate. The ring groove structure effectively improves the adsorption force of the suction cup on the oil-immersed surface by forming a more effective seal and increasing the friction force and adsorption area. This study could provide a reference for developing the actuator of the oil-immersed or lubricated climbing machine

Securing Embedded System from Code Reuse Attacks: A Lightweight Scheme with Hardware Assistance

The growing prevalence of embedded systems in various applications has raised concerns about their vulnerability to malicious code reuse attacks. Current software-based and hardware-assisted security techniques struggle to detect or block these attacks with minor performance and implementation overhead. To address this issue, this paper presents a lightweight hardware-assisted scheme to enhance the security of embedded systems against code reuse attacks. We develop an on-chip lightweight hardware shadow stack to validate target addresses at runtime for backward-edge control flow integrity, which backs up valid return addresses during function calls and automatically verifies actual return addresses during the return phase. Additionally, we propose a lightweight stream cipher circuit that encrypts and decrypts critical stack data related to control flow manipulation, preventing attackers from analyzing or tampering with them. When designing and implementing the security mechanism for embedded systems, we fully consider the constraints of limited system resources and performance, optimizing both the architecture design and implementation of the proposed hardware. Finally, we integrate both the proposed lightweight hardware shadow stack and the runtime data encryption hardware into the OR1200 processor. We have verified the system security function on the Terasic DE1-SoC FPGA platform and evaluated the system performance as well as implementation overhead. The results show that the proposed lightweight hardware-assisted scheme can provide a dedicated defense capability against code reuse attacks for embedded systems, with an average system performance overhead of 0.39% and an area footprint of 0.316 mm2

Study on Friction and Wear Behavior of Inconel 625 Superalloy during Hot Extrusion

Friction during the hot extrusion of Inconel 625 superalloy tubes causes severe wear of the mold and plays a decisive role in the quality of the workpieces. In this paper, a ball-to-disk method was utilized to investigate the tribological behavior of Inconel 625 using two different tribological pairs, i.e., GCr15 and Si3N4, at room and elevated temperatures. Friction coefficient, specific wear rate, and morphology of worn surfaces were systematically characterized. It was found that the friction coefficients for both tribological pairs generally increased as the testing temperature increased, while the specific wear rate increased firstly and then decreased with the rise of temperature. Along with the increasing sliding speed, the friction coefficient between Inconel 625 and Si3N4 decreased monotonically, while the specific wear rate increased firstly and then decreased. Under any given testing condition, the friction coefficient and specific wear rate of the Inconel 625 for Inconel/Si3N4 pair are less than those of the Inconel/GCr15 pair. The main wear mechanisms between GCr15 and Inconel 625 are adhesive and fatigue wear at all testing temperatures. The wear mechanisms between Si3N4 and Inconel 625 are adhesive and abrasive wear at room temperature but fatigue wear at 500°C. Our findings indicate that the use of ceramic molds in the hot extrusion of Inconel 625 may significantly improve the surface qualities of the product and reduce the wear of the mold

Transcriptomic and Metabolomic Analyses of <i>Palaemon carinicauda</i> Hepatopancreas in Response to <i>Enterocytozoon hepatopenaei</i> (EHP) Infection

Enterocytozoon hepatopenaei (EHP), a microsporidian responsible for hepatopancreatic microsporidiosis, is a major pathogen in commercial shrimp production. Among the affected species, Palaemon carinicauda (formerly Exopalaemon carinicauda) is commercially important in China and represents a potential research model for studying crustaceans. However, little information is available on its response to EHP infection. Hence, this study analyzed the transcriptome and metabolome of P. carinicauda’s hepatopancreas using high-throughput sequencing and liquid chromatograph-mass spectrometry (LC-MS) to determine its response during the early stage of infection. The transcriptomic analyses identified 730 differentially expressed genes, of which those associated with EHP infection were enriched in metabolic pathways as well as detoxification and antioxidant pathways. In addition, 144 differential metabolites were identified using a combination of positive and negative ion modes in LC-MS. The Kyoto encyclopedia of genes and genomes pathway analyses further indicated that the degradation of aromatic compounds, the AMP-activated protein kinase signaling pathway and C5-branched dibasic acid metabolism were significantly enriched after EHP infection. These results could provide useful insights into the effects of EHP on shrimps during the early stages of infection and help to understand the mechanisms underlying the stunted growth of shrimps after infection

Transcriptomic and Metabolomic Analyses of Palaemon carinicauda Hepatopancreas in Response to Enterocytozoon hepatopenaei (EHP) Infection

Enterocytozoon hepatopenaei (EHP), a microsporidian responsible for hepatopancreatic microsporidiosis, is a major pathogen in commercial shrimp production. Among the affected species, Palaemon carinicauda (formerly Exopalaemon carinicauda) is commercially important in China and represents a potential research model for studying crustaceans. However, little information is available on its response to EHP infection. Hence, this study analyzed the transcriptome and metabolome of P. carinicauda&rsquo;s hepatopancreas using high-throughput sequencing and liquid chromatograph-mass spectrometry (LC-MS) to determine its response during the early stage of infection. The transcriptomic analyses identified 730 differentially expressed genes, of which those associated with EHP infection were enriched in metabolic pathways as well as detoxification and antioxidant pathways. In addition, 144 differential metabolites were identified using a combination of positive and negative ion modes in LC-MS. The Kyoto encyclopedia of genes and genomes pathway analyses further indicated that the degradation of aromatic compounds, the AMP-activated protein kinase signaling pathway and C5-branched dibasic acid metabolism were significantly enriched after EHP infection. These results could provide useful insights into the effects of EHP on shrimps during the early stages of infection and help to understand the mechanisms underlying the stunted growth of shrimps after infection

Bionic Ring Grooves Design and Experiment of the Suction Cup Applied in Oil-Immersed Substrate

The vacuum suction cup is often used as an end effector and widely used in wall-climbing operations. However, there are few vacuum suction cup designs and applications for oil-immersed substrates. Inspired by the surface morphology of the octopus sucker, bionic suction cups with different numbers, diameters, and spacings of the ring grooves were designed. Their normal adsorption force was evaluated on the untreated and polished steel plate in oil. The test results showed that ring grooves positively affected the adsorption force. The bionic suction cup with a groove number of 3, a diameter of 0.5 mm, and a spacing of 3 mm was the most excellent in the test. It achieved normal adsorption forces of 54.83 ± 0.48 N and 43.89 ± 0.69 N on the untreated and polished steel plate. Compared with the standard suction cup, it increased by 32.31% and 12.28% on the untreated and polished steel plate. The regression model between the normal adsorption force and design factors was established based on the adsorption force test results, and the influence law of the ring groove structure parameters on the adsorption force of suction cups on oil-immersed substrates was analyzed. The order of significant effects of groove design parameters on normal adsorption forces was groove diameters, spacings, and numbers. The finite element analysis (FEA) results show that the ring grooves could significantly increase the contact pressure, frictional stress, and sliding distance between the suction cup and the substrate. The ring groove structure effectively improves the adsorption force of the suction cup on the oil-immersed surface by forming a more effective seal and increasing the friction force and adsorption area. This study could provide a reference for developing the actuator of the oil-immersed or lubricated climbing machine