Target-Driven Structured Transformer Planner for Vision-Language Navigation

Vision-language navigation is the task of directing an embodied agent to navigate in 3D scenes with natural language instructions. For the agent, inferring the long-term navigation target from visual-linguistic clues is crucial for reliable path planning, which, however, has rarely been studied before in literature. In this article, we propose a Target-Driven Structured Transformer Planner (TD-STP) for long-horizon goal-guided and room layout-aware navigation. Specifically, we devise an Imaginary Scene Tokenization mechanism for explicit estimation of the long-term target (even located in unexplored environments). In addition, we design a Structured Transformer Planner which elegantly incorporates the explored room layout into a neural attention architecture for structured and global planning. Experimental results demonstrate that our TD-STP substantially improves previous best methods' success rate by 2% and 5% on the test set of R2R and REVERIE benchmarks, respectively. Our code is available at https://github.com/YushengZhao/TD-STP

Laser-Induced Damage Initiation and Growth of Optical Materials

The lifetime of optical components is determined by the combination of laser-induced damage initiation probability and damage propagation rate during subsequent laser shots. This paper reviews both theoretical and experimental investigations on laser-induced damage initiation and growth at the surface of optics. The damage mechanism is generally considered as thermal absorption and electron avalanche, which play dominant roles for the different laser pulse durations. The typical damage morphology in the surface of components observed in experiments is also closely related to the damage mechanism. The damage crater in thermal absorption process, which can be estimated by thermal diffusion model, is typical distortion, melting, and ablation debris often with an elevated rim caused by melted material flow and resolidification. However, damage initiated by electron avalanche is often accompanied by generation of plasma, crush, and fracture, which can be explained by thermal explosion model. Damage growth at rear surface of components is extremely severe which can be explained by several models, such as fireball growth, impact crater, brittle fracture, and electric field enhancement. All the physical effects are not independent but mutually coupling. Developing theoretical models of multiphysics coupling are an important trend for future theoretical research. Meanwhile, more attention should be paid to integrated analysis both in theory and experiment

Self-assembled nanostructured polyaniline with different structure-directing agents

Ph.DDOCTOR OF PHILOSOPH

A detailed study of growth of nanostructured poly(aniline) particles in the light of thermodynamic interaction balance

In this paper, various nanostructured poly(aniline) (PANI) particles have been prepared via redox polymerization of aniline in the presence of tri(ethylene glycol) bis(1,5-dihydroxynaphthalene- 2,6- disulfate) ether (TBE). The morphology evolution of the resulting PANI particles was carefully monitored by electron microscopy, clearly underlining the structure-directing role of TBE during the agglomeration of PANI primary nanoparticles (NPs) in the course of polymerization. Various interactions exerted on the PANI primary NPs were assessed based on extended Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, and the thermodynamic balance of these interactions was used to analyze the effect of the TBE concentration on the morphology of the nanostructured PANI particles.

Shape transformation of gold nanoparticles in aqueous CTAB/CTAC solution to generate high-index facets for electrocatalysis and SERS activity

Gold nanoparticles (Au NPs) have demonstrated great potential in chemical and biological sensing, catalysis, biomedicine, X-ray computed tomography, and other applications, owing to their unique properties. Au NPs with high-index facets have attracted more attention in the past decade owing to their superior electrocatalytic activity in fuel cells and enhanced performance in surface-enhanced Raman spectroscopy (SERS) applications. This review presents an overview of our achievements in the direct synthesis of Au NPs with controlled shapes in water using cationic surfactants. By deliberately adjusting the nature of the surfactant stabilizers, preformed Au NPs with simple shapes can be readily transformed into Au NPs with complicated shapes with controlled high-index facets by simple seeded growth. The high-index facets of the as-prepared Au NPs can be consistently correlated with their superior performance in the electrooxidation of methanol and ethanol and their enhanced SERS activity

Synthesis of monodisperse quasi-spherical gold nanoparticles in water via silver(I)-assisted citrate reduction

We demonstrate a simple and reproducible way to produce quasi-spherical Au nanoparticles (NPs) with a fairly narrow size distribution in water by rapidly adding a mixture solution of HAuCl4, sodium citrate, and a trace amount of silver nitrate into boiling water. The sizes of quasi-spherical Au NPs obtained increases from 12(1 nmto 18(3, 25(3, and 36 ( 3 nm with decrease of the citrate concentration in a fairly linear way. The present protocol can efficiently minimize the effect of citrate to buffer the pH of the reaction media and thus change the type and reactive activity of auric ions and significantly speed up the nucleation and growth rate of Au NPs. The presence of Ag þ ions can not only suppress the secondary nucleation but also reshape the polycrystalline Au NPs into a quasi-spherical shape. In the case of synthesis of Au NPs of sizes ranging from 10 to 36 nm, our approach efficiently makes up the shortages of the classical Turkevich method with respect to the reproducibility and uniformity of the NP size and shape.

Improved Baseline Correction Method Based on Polynomial Fitting for Raman Spectroscopy

Abstract Raman spectrum, as a kind of scattering spectrum, has been widely used in many fields because it can characterize the special properties of materials. However, Raman signal is so weak that the noise distorts the real signals seriously. Polynomial fitting has been proved to be the most convenient and simplest method for baseline correction. It is hard to choose the order of polynomial because it may be so high that Runge phenomenon appears or so low that inaccuracy fitting happens. This paper proposes an improved approach for baseline correction, namely the piecewise polynomial fitting (PPF). The spectral data are segmented, and then the proper orders are fitted, respectively. The iterative optimization method is used to eliminate discontinuities between piecewise points. The experimental results demonstrate that this approach improves the fitting accuracy

Simple Synthesis of Monodisperse, Quasi-spherical, Citrate-Stabilized Silver Nanocrystals in Water

Monodisperse, quasi-spherical silver nanocrystals (Ag NCs) have been produced directly in water via adding the aqueous solution of a mixture of AgNO₃, sodium citrate, and KI into the boiling aqueous solutions of ascorbic acid (AA). The AA is used to significantly accelerate reduction of AgNO₃ in order to promote a very fast nucleation, and the KI is used to tailor the growth of the Ag NCs into a quasi-spherical shape via its preferential adsorption on the NC {111} facets. The major role of citrate is to stabilize the newly formed NCs, whereas it has a minor contribution to reduction of AgNO₃. The synergy of the effects of AA, citrate, and KI can significantly narrow the size distributions of the Ag NCs obtained so and transform the NC shapes to be truly quasi-spherical