Subwavelength light confinement and propagation: A numerical study of a two-layer silver film with perforated holes

Confinement and propagation of light under the diffraction limit is a substantial challenge for the development of waveguides as components in subwavelength optical devices. Light confinement and propagation at optical frequencies in a two-layer silver film with a periodic array of holes is investigated in a numerical study using the discrete dipole approximation method. Extraordinary subwavelength confinement and propagation of light can be obtained along an extremely subwavelength cross section of a region as small as 10 x 20 nm(2) at a distance of over 10 mu m. This study provides rational design of waveguides under subwavelength dimensions

SH3 interactome conserves general function over specific form

Src homology 3 (SH3) domains bind peptides to mediate protein–protein interactions that assemble and regulate dynamic biological processes. We surveyed the repertoire of SH3 binding specificity using peptide phage display in a metazoan, the worm Caenorhabditis elegans, and discovered that it structurally mirrors that of the budding yeast Saccharomyces cerevisiae. We then mapped the worm SH3 interactome using stringent yeast two-hybrid and compared it with the equivalent map for yeast. We found that the worm SH3 interactome resembles the analogous yeast network because it is significantly enriched for proteins with roles in endocytosis. Nevertheless, orthologous SH3 domain-mediated interactions are highly rewired. Our results suggest a model of network evolution where general function of the SH3 domain network is conserved over its specific form

Numerical simulation of the tensile behavior of Al 7075-T6 alloy with corrosion pits

peer reviewedCorrosion which occurs at local scale has been found to result in a dramatic macroscopic tensile ductility loss of the 7075 Aluminum alloy. The aim of the present paper is to investigate the plastic property and ultimate strength characteristics of high strength Aluminum alloy with corrosion pits. The tensile behavior of corroded 7075-T6 specimens has been simulated on the basis of micromechanics analysis by taking into account the degree of corrosion pit by weight loss rate. The mathematic description of the void volume fraction evolution is modified and the parameters in the modified model were obtained according to the tensile test results of uncorroded material. Ductile fracture behavior of the specimens with different corrosion time was analyzed by using the modified Gurson model. The results of numerical simulation agree well with experimental data. The insights developed from the present study will be very useful for damage tolerant design of Aluminum alloy structures with pit corrosion damage

Study of Dynamic Impact Behaviors and Ballistic Properties of Ceramic/UHMWPE Composite Armor

peer reviewedThe ballistic properties of different thickness combinations of ceramic/UHMWPE composite armors were studied in this paper, in order to find a better ballistic property structure subject to 12.7mm bullet. Powder-gun ballistic testing system was used to carry out the normal impact tests to determine the response and the ballistic limit of these combinations of ceramic/UHMWPE composite armors subject to impact loading. Compared with the test, an explicit finite element (FE) model was built with LS-DYNA Code to simulate the impact process. The influence of different parameters on the impact behavior was considered analytically. Results show very good agreement with the experimental data

Study of Dynamic Impact Behaviors and Ballistic Properties of Hybrid Composites

This paper deals with the ballistic properties of two kinds of hybrid composites: Kevlar/Carbon laminates and S-Glass/Carbon laminates. Twelve kinds of combinations of samples were made including various fibers; various fiber orientations and various target thickness. Air-gun tests were carried out to determine the response of these combinations of hybrid laminates subject to impact loading. Compared with the test, an explicit finite element (FE) model was built with Pam-crash Code to simulate the impact process. The bullet was considered as a deformable body in contact with the composite shells. The Ladevèze model was used to describe the unidirectional properties of Carbon plies and Ladevèze fabric model was used to describe the homogeneous properties of the S-glass and Kevlar laminates. The influence of different parameters on the impact behavior of the two kinds of hybrid laminates was considered analytically. Results show very good agreement with the experimental data. Suggestions are also presented for the better hybrid mode to improve the ballistic properties

An Experimental Study on the Mechanical Performance and Damage Evolution of Woven Fabric E-glass Fiber Reinforced Epoxy Composite

The present study focuses on the mechanical performance and damage evolution of woven fabric E-glass fiber reinforced epoxy composite (7781/F155-glass/epoxy). For the identical behavior in the 0o and the 90o directions of the tested material, the mechanical experiments were performed with 0o and 45o specimens. Three kinds of tests were implemented respectively: tension test with 0o specimen, compression test with 0o specimen, and tension test with 45o specimen which represents the in-plane shear test. Tension, compression and in-plane shear damage, which are defined as the decreasing ratio of modulus, were calculated from the data of quasi-static cyclic tests. The influence of loading rate on material behaviors were investigated under three different loading rates. Although all of the three loading rates are low, it showed that the strain rate has obvious effects on the ultimate strengths and moduli of the glass fiber reinforced epoxy composite

Accelerated corrosion tests of high strength 7075 aluminum alloy in salt water spray

peer reviewedHigh-strength aluminum alloy is often used in aircraft structure. The corrosion is a big problem for high strenth aluminum alloy. Acid salt spray (fog) test is used here to accelerate the corrosion of 7075 aluminum alloy. The results obtained from the test show that the acid salt spray test could simulate and accelerate the atmospheric corrosion well. The mechanical properties of the corrosion samples have been tested. And it was found that the mechanical properties of the corrosion samples declined obviously with the corrosion time. Based on the test and the knowledge of damage mechanics, a concept of equivalent corrosion damage was proposed for the accelerated corrosion tests

Study on the relationship between corrosion damage and residual strength of AL 7075-T6 alloy

peer reviewedIt has been found in experiment that the local-scale pit corrosion of aluminum alloy 7075-T6 can lead to dramatic loss of its macroscopic tensile ductility. Based on the Gurson’s void model, the present paper aims to investigate quantitatively the changing characteristics of the plastic property and ultimate strength for the aluminum alloy with skin-deep pit corrosion. The tensile behaviors of the corroded 7075-T6 specimens with the different degrees of pit corrosion and weight loss are estimated by micromechanical analysis in this paper, and also the yielding strengths of the specimens are evaluated by the Gurson’s criterion. The predicted properties of the corroded specimens are in accordance with the experimental results very well

Exploring the processes and mechanisms by which nonprofit organizations orchestrate global innovation networks: A case study of the COVAX program

In cocreating value with other organizations, nonprofit organizations may face multiple management challenges, posed by multistakeholder global innovation networks. Since these have not yet been systematically studied by academics, this study explores how nonprofit organizations can promote the cocreation of value in multistakeholder global innovation networks. Adopting a longitudinal single-case study approach from the perspective of network orchestration theory, this work deeply analyzes how nonprofit organizations can promote the evolution of the global innovation network of the COVID-19 vaccine under the COVAX program. The results show that nonprofits need to successively address the dilemmas of legitimacy, direction, and heterogeneity in constructing global innovation networks and that to solve these stage dilemmas, orchestrators must successively function as network architects, liaisons, and leaders to direct the implementation of network actions using trusted, leveraged, and adapted orchestration logics. This paper further proposes a model of the orchestration process and mechanisms by which nonprofit organizations facilitate multistakeholder global innovation networks. Theoretically, this study therefore extends network orchestration theory by summarizing the mechanisms and orchestration logics by which NPOs construct and develop networks when they act as orchestrators. From a practical perspective, this study also provides guidance for future unexpected global public health crises, improving the global community's ability to combat them

Theoretical and experimental research for the elastic properties of corroded 7075-T6 Al alloy

peer reviewedThe researches were aimed at assessing the elastic properties of material with pre-existing corrosion damage. Corrosion in the form of pitting in certain classes of aluminum alloys, e.g. 7075-T6, is considered here. Based on the characteristics of corrosion metrics and micromechanics, the paper describes a mechanical property prediction procedure for corroded aluminum alloy. The model was developed in the framework of micro-mechanics, in combination with the existing corroded coupon tensile test results. The existing data included the weight loss rates of 7075-T6 sheet exposed to acid salt spray (fog) for various time periods. Tensile tests were taken for corroded 'dog bone' coupons. The paper describes the test procedures and mechanical test results. The results provide a database for verifying the analysis model. The accuracy of the method is assessed by comparing the predicted results with those of tests of corroded 7075-T6 specimens. The results indicate that corrosion can be represented by voids damage in the material as the elastic properties of corroded aluminum alloy are concerned