A new paradigm in functionally graded adhesives

To fully realize the benefits of advanced composites, mechanical fasteners must be supplanted by more efficient technologies such as adhesive bonding. The promise of functionally graded adhesives to provide particularly high levels of performance in this context has been recognized for decades, but a means of generating stable, high performance adhesive joints with arbitrary gradations in mechanical properties has proved elusive. Please click Additional Files below to see the full abstract

New developments in dual cure epoxies

Direct write 3D printing provides an exciting new means of generating novel structures from thermosetting resins via an additive approach. Initial efforts along these lines demonstrated the preparation of homogenous, high quality parts. More recent work has shown that it is possible to modulate the properties of these parts locally through changes in orientation of high aspect ratio fillers. In this work, we present complementary developments related to resin chemistry that should provide practitioners of direct write 3D printing with additional options as far as the realization of functional gradations is concerned. This is accomplished via the creation of so-called “dual cure” resins. Here this term refers to materials that undergo thermal cure in a similar fashion to many conventional resins. Then, in a second step, the selective exposure of these materials to high energy radiation (gamma rays, electrons, etc.) results in further increases in local crosslink density, altering thermomechanical performance and providing a means of inducing arbitrary gradations in properties in a post-processing step. A number of different families of dual cure resins have been explored and are presented here, as well as data concerning changes in thermal and mechanical performance as a function of the details of the dual curing process. Preliminary efforts giving evidence of the generation of stable functional gradations in practice are also described. Ongoing and future efforts are focused on the optimization of these systems and the incorporation of their cure-dependent mechanical behavior into simulations in order to enable design optimization

Learning to Reweight with Deep Interactions

Recently, the concept of teaching has been introduced into machine learning, in which a teacher model is used to guide the training of a student model (which will be used in real tasks) through data selection, loss function design, etc. Learning to reweight, which is a specific kind of teaching that reweights training data using a teacher model, receives much attention due to its simplicity and effectiveness. In existing learning to reweight works, the teacher model only utilizes shallow/surface information such as training iteration number and loss/accuracy of the student model from training/validation sets, but ignores the internal states of the student model, which limits the potential of learning to reweight. In this work, we propose an improved data reweighting algorithm, in which the student model provides its internal states to the teacher model, and the teacher model returns adaptive weights of training samples to enhance the training of the student model. The teacher model is jointly trained with the student model using meta gradients propagated from a validation set. Experiments on image classification with clean/noisy labels and neural machine translation empirically demonstrate that our algorithm makes significant improvement over previous methods.Comment: Accepted to AAAI-202

Feature-Based Simplification of Process Plant Models over Network

International audienceVisualization of 3D process plant models is an essential feature to support design review in distributed design environment. The preprocessing time, frame rate and visual fidelity play the same import role in improving the effectiveness and efficiency of the entire design review process. General model simplification algorithms, such as levels of detail (LODs) and hierarchical levels of detail (HLODs), always need unbearable time for preprocessing large-scale models and may distort design feature and make them unrecognizable to the reviewer. To efficiently transmit models, various compression technologies can be applied to shrink the data size. However, transmitting large-scale models over network is still a bottleneck of rendering performance. In this paper, we presented a new, faster feature-based model simplification algorithm to simplify process plant models over network. We first get the model’s geometric parameters and topology information from the server before visualization. Then we compute LODs and HLODs according to the model’s geometric parameters and composing feature on the client. No triangles are transmitted during visualization. We demonstrate its performance on complex process plant models composed of tens of millions of triangles. Results show that our approach is able to shorten the preprocessing time greatly. And it can achieve considerable speedups in frame rate with little loss in image quality

EXPERIMENTAL RESEARCH ON MECHANICAL PROPERTIES OF LAMINATED POPLAR WOOD VENEER/PLASTIC SHEET COMPOSITES

In this study, to improve the structural applications of wood plastic composite (WPC) according to its relatively lower MOE, wood veneer and plastic sheets were laminated to form laminated WPC (LWPC). Bonding performance tests were conducted to determine the effects of coupling agent and processing on bonding performance between wood and plastic, followed by mechanical properties tests. The bondlines between wood and plastic were examined using scanning electron microscopy (SEM). The results showed the following. 1) Delamination of untreated LWPCs was converted into wood fracture by adding a coupling agent. 2) The bending strength and tensile strength are both higher than those of the conventional WPCs, and the MOE of parallel multilayered LWPCs was significantly increased. The parallel multilayered LWPC with a density of 0.6 g/cm3 and wood-to-plastic ratio of 3:1 had an MOE of 11,490 MPa, and the bending and tensile strength were 40.36 MPa and 31.47 MPa, respectively. 3) SEM indicated that a strong interfacial connection in LWPC was obtained. This study demonstrated that the configuration of LWPC in combination with laminated veneer lumber and conventional WPC technologies is an effective method to improve mechanical properties. The LWPC can be used as a load-bearing material in timber structure

Evaluation of Rock Burst Propensity and Rock Burst Mechanism in Deep Phosphate Mines: A Case Study of Sujiapo Phosphate Mine, Hubei Province, China

Rockburst is one of the major problems in rock underground engineering and mechanics. To make a risk assessment of rockburst and improve the mine safety index, some evaluation systems for rockburst propensity have been proposed and applied, and progress has been made in the study of high-value mines and single evaluation systems, but these evaluation systems are still immature for deep low and medium grade phosphate mines with more complex influencing factors. Therefore, to solve this problem, this study takes the phosphate mining area of the Sujiapo phosphate mine as the main research object, and combines the characteristics of the deep rockburst of the phosphate mine and its physical and mechanical properties; the evaluation system combines fuzzy mathematical method and multiple evaluation methods to determine the propensity of rockburst of deep mining of Sujiapo phosphate mine. The JSM-500LV SEM and acoustic emission results are used to analyze the microscopic mechanism of rockburst from the morphology and composition of the rocks, and the rationality of the evaluation system is further demonstrated. The study shows that dolomite and phosphorite in the study area are moderate rockburst, and shale has a weak rockburst tendency; because the roof dolomite and phosphorite crystallization degree are higher, the elastic modulus is large. Under the action of external load, the roof dolomite stored more elastic strain energy. Deformation damage consumes less energy. The energy released to the outside world after the damage is large, more likely to occur brittle damage, and the rockburst tendency is high. Therefore, the evaluation system combining multiple evaluation methods can comprehensively determine rockburst in phosphate mines

Comparison of Long-Read Methods for Sequencing and Assembly of Lepidopteran Pest Genomes

Lepidopteran species are mostly pests, causing serious annual economic losses. High-quality genome sequencing and assembly uncover the genetic foundation of pest occurrence and provide guidance for pest control measures. Long-read sequencing technology and assembly algorithm advances have improved the ability to timeously produce high-quality genomes. Lepidoptera includes a wide variety of insects with high genetic diversity and heterozygosity. Therefore, the selection of an appropriate sequencing and assembly strategy to obtain high-quality genomic information is urgently needed. This research used silkworm as a model to test genome sequencing and assembly through high-coverage datasets by de novo assemblies. We report the first nearly complete telomere-to-telomere reference genome of silkworm Bombyx mori (P50T strain) produced by Pacific Biosciences (PacBio) HiFi sequencing, and highly contiguous and complete genome assemblies of two other silkworm strains by Oxford Nanopore Technologies (ONT) or PacBio continuous long-reads (CLR) that were unrepresented in the public database. Assembly quality was evaluated by use of BUSCO, Inspector, and EagleC. It is necessary to choose an appropriate assembler for draft genome construction, especially for low-depth datasets. For PacBio CLR and ONT sequencing, NextDenovo is superior. For PacBio HiFi sequencing, hifiasm is better. Quality assessment is essential for genome assembly and can provide better and more accurate results. For chromosome-level high-quality genome construction, we recommend using 3D-DNA with EagleC evaluation. Our study references how to obtain and evaluate high-quality genome assemblies, and is a resource for biological control, comparative genomics, and evolutionary studies of Lepidopteran pests and related species

Chem. Lett.

A porous ferrihydrite has been synthesized from layered double hydroxide precursors via selective extraction. The characterization results show that the porous ferrihydrite possesses not only large total pore volume but also uniform micropore size distribution, which make it exhibit a good charge/discharge capacity and cycling performance as the lithium battery cathode.A porous ferrihydrite has been synthesized from layered double hydroxide precursors via selective extraction. The characterization results show that the porous ferrihydrite possesses not only large total pore volume but also uniform micropore size distribution, which make it exhibit a good charge/discharge capacity and cycling performance as the lithium battery cathode