Visual Robotic Manipulation with Depth-Aware Pretraining

Recent work on visual representation learning has shown to be efficient for robotic manipulation tasks. However, most existing works pretrained the visual backbone solely on 2D images or egocentric videos, ignoring the fact that robots learn to act in 3D space, which is hard to learn from 2D observation. In this paper, we examine the effectiveness of pretraining for vision backbone with public-available large-scale 3D data to improve manipulation policy learning. Our method, namely Depth-aware Pretraining for Robotics (DPR), enables an RGB-only backbone to learn 3D scene representations from self-supervised contrastive learning, where depth information serves as auxiliary knowledge. No 3D information is necessary during manipulation policy learning and inference, making our model enjoy both efficiency and effectiveness in 3D space manipulation. Furthermore, we introduce a new way to inject robots' proprioception into the policy networks that makes the manipulation model robust and generalizable. We demonstrate in experiments that our proposed framework improves performance on unseen objects and visual environments for various robotics tasks on both simulated and real robots.Comment: submitted to ICRA202

Room temperature 2D ferromagnetism in few-layered 1TT-CrTe2_{2}

Spin-related electronics using two dimensional (2D) van der Waals (vdW) materials as a platform are believed to hold great promise for revolutionizing the next generation spintronics. Although many emerging new phenomena have been unravelled in 2D electronic systems with spin long-range orderings, the scarcely reported room temperature magnetic vdW material has thus far hindered the related applications. Here, we show that intrinsic ferromagnetically aligned spin polarization can hold up to 316 K in a metallic phase of 1$T$-CrTe$_{2}$ in the few-layer limit. This room temperature 2D long range spin interaction may be beneficial from an itinerant enhancement. Spin transport measurements indicate an in-plane room temperature negative anisotropic magnetoresistance (AMR) in few-layered CrTe$_{2}$, but a sign change in the AMR at lower temperature, with -0.6$\%$ at 300 K and +5$\%$ at 10 K, respectively. This behavior may originate from the specific spin polarized band structure of CrTe$_{2}$. Our findings provide insights into magnetism in few-layered CrTe$_{2}$, suggesting potential for future room temperature spintronic applications of such 2D vdW magnets.Comment: 9 Pages, 4 Figure

Functional Divergence among Silkworm Antimicrobial Peptide Paralogs by the Activities of Recombinant Proteins and the Induced Expression Profiles

Antimicrobial peptides are small-molecule proteins that are usually encoded by multiple-gene families. They play crucial roles in the innate immune response, but reports on the functional divergence of antimicrobial peptide gene families are rare. In this study, 14 paralogs of antimicrobial peptides belonging to cecropin, moricin and gloverin families were recombinantly expressed in pET expression systems. By antimicrobial activity tests, peptides representing paralogs in the same family of cecropin and moricin families, displayed remarkable differences against 10 tested bacteria. The evolutionary rates were relatively fast in the two families, which presented obvious functional divergence among paralogs of each family. Four peptides of gloverin family had similar antimicrobial spectrum and activity against tested bacteria. The gloverin family showed similar antimicrobial function and slow evolutionary rates. By induced transcriptional activity, genes encoding active antimicrobial peptides were upregulated at obviously different levels when silkworm pupae were infected by three types of microbes. Association analysis of antimicrobial activities and induced transcriptional activities indicated that the antimicrobial activities might be positively correlated with induced transcriptional activities in the cecropin and moricin families. These results suggest that representative BmcecB6, BmcecD and Bmmor as the major effector genes have broad antimicrobial spectrum, strong antimicrobial activity and high microbe-induced expression among each family and maybe play crucial roles in eliminating microbial infection

Mimic Encryption Box for Network Multimedia Data Security

With the rapid development of the Internet, the security of network multimedia data has attracted increasingly more attention. The moving target defense (MTD) and cyber mimic defense (CMD) approaches provide a new way to solve this problem. To enhance the security of network multimedia data, this paper proposes a mimic encryption box for network multimedia data security. The mimic encryption box can directly access the network where the multimedia device is located, automatically complete the negotiation, provide safe and convenient encryption services, and effectively prevent network attacks. According to the principles of dynamization, diversification, and randomization, the mimic encryption box uses a reconfigurable encryption algorithm to encrypt network data and uses IP address hopping, port number hopping, protocol camouflage, and network channel change to increase the attack threshold. Second, the mimic encryption box has a built-in pseudorandom number generator and key management system, which can generate an initial random key and update the key with the hash value of the data packet to achieve “one packet, one key.” Finally, through the cooperation of the ARM and the FPGA, an access control list can be used to filter illegal data and monitor the working status of the system in real time. If an abnormality is found, the feedback reconstruction mechanism is used to “clean” the FPGA to make it work normally again. The experimental results and analysis show that the mimic encryption box designed in this paper has high network encryption performance and can effectively prevent data leakage. At the same time, it provides a mimic security defense mechanism at multiple levels, which can effectively resist a variety of network attacks and has high security

Numerical Simulation of Oil Spill in the Arctic Ice-Covered Waters: Focusing on Different Ice Concentrations and Wave’s Impacts

The computational model was established to investigate the characteristics of oil spreading under arctic environments focusing on two aspects: ice concentrations and wave impacts. The ice field was constructed using the ice plates to compose three kinds of fixed arrays based on different ice concentrations of 90%, 60% and 0%. The wave was generated using the improved Jonswap spectrum method to control the focusing time, focusing location and focusing wave amplitude. The oil spreading’s movement was simulated and compared to the field experiment to verify the numerical model’s validity. The oil spill was trapped under the ice plates’ lower surface when the ice concentration was 60% or 90%, which had a spreading velocity slower than the non-ice water. The moving ice simulation was performed via the overset technique and coupled with the current, wind and wave. With ice drifting, the oil spreading was accelerated, leading to the presence of oil both on and under the ice surface. The ice was driven by the wave to affect the running details of the oil trajectory. These findings can be utilized for future oil spreading prediction when an oil spill accident occurs in the Arctic Ocean

Antifouling Ability of Hydrophilic PVDF-TiO

The PVDF flat-membrane was modified by hydrophilic nano-TiO2, which blending by ultrasonication and mechanical stirring pretreatment in phase inversion method. To evaluate the permeate productivity and anti-fouling capacity of protein solution, both the critical flux (JCW) and threshold flux (JTH) of PVDF and PVDF-TiO2 membrane were firstly measured by Advanced Constant Pressure-step Method in cross-flow filtration apparatus. Some evaluation indicators were utilized to analyze the results, such as Flux vs. Time and TMP vs. Time Curves, flux decline rate (dFlux/dt) and TMP-Fluxave curve. Two type fluxes were compared, results exhibited that hydrophilic PVDF-TiO2 modified membrane possessed a higher level of both Jcw and JTH and better anti-protein fouling ability after testing by Advanced Constant Pressure-step Method

Universal Adhesives- Different Curing Methods and Applications

The adhesive is a kind of material with good adhesion properties which could join objects by adhesion of surfaces via forces of adhesion and cohesion. There are many kinds of adhesives. This paper mainly classifies them by curing method, from UV curing and heat curing to moisture curing and microwave curing, and describes the corresponding mechanisms. Furthermore, it covers the advantages and disadvantages, application ranges, and related chemical compounds of different curing ways for adhesives. This can broaden our understandings of different ways of adhesive curing. Besides, it could also help us choose the most appropriate curing method according to different requirements in daily life

Carbon Emission Reduction Evaluation of End-of-Life Buildings Based on Multiple Recycling Strategies

With the promotion of sustainability in the buildings and construction sector, the carbon saving strategies for the end-of-life (EoL) phase have been receiving increasing attention. In this research, life cycle assessment (LCA) theory was employed to study and compare the carbon savings benefits of three different management strategies (i.e., recycling, remanufacturing, and reuse) on the EoL phase of various buildings (including residential, office, commercial, and school buildings). Moreover, the carbon savings potential (CSP) was calculated and analyzed, which is defined as the percentage of the actual carbon savings to the sum of the total embodied carbon of the building. Results show that compared with traditional demolition and landfill treatment, the implementation of integrated management strategies for residential, office, commercial, and school buildings can reduce carbon emissions by 193.5–526.4 kgCO2-e/m2. Among the building materials, steel bar, structural steel, and concrete account for the major proportion of the total carbon savings of buildings (81.5–93.2%). The sequence of the CSPs for the four types of buildings, in descending order, is school, residential, commercial, and office buildings. A building with a life span of 50 years has the greatest CSP. The results of the study can be used to reduce environmental impacts, and have broad positive implications in terms of sustainable construction