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[IEEE 2019 International Conference on Computer, Communication, Chemical, Materials and Electronic Engineering (IC4ME2) - Rajshahi, Bangladesh (2019.7.11-2019.7.12)] 2019 International Conference on Computer, Communication, Chemical, Materials and Electronic Engineering (IC4ME2) - Low Loss Microstructure Optical Fiber Refractive Index Sensor based on Surface Plasmon Resonance
摘要： This paper studies the optimization problem of topological active net (TAN), which is often seen in image segmentation and shape modeling. A TAN is a topological structure containing many nodes, whose positions must be optimized while a prede?ned topology needs to be maintained. TAN optimization is often time-consuming and even constructing a single solution is hard to do. Such a problem is usually approached by a “best improvement local search” (BILS) algorithm based on deterministic search (DS), which is inef?cient because it spends too much efforts in nonpromising probing. In this paper, we propose the use of micro-differential evolution (DE) to replace DS in BILS for improved directional guidance. The resultant algorithm is termed deBILS. Its micro-population ef?ciently utilizes historical information for potentially promising search directions and hence improves ef?ciency in probing. Results show that deBILS can probe promising neighborhoods for each node of a TAN. Experimental tests verify that deBILS offers substantially higher search speed and solution quality not only than ordinary BILS, but also the genetic algorithm and scatter search algorithm.
关键词： grid deformation,topological active net (TAN),structure optimization,Differential evolution (DE),topological optimization
更新于2025-09-23 15:19:57
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Strongly coupled 2D-2D nanojunctions between P-doped Ni2S (Ni2SP) cocatalysts and CdS nanosheets for efficient photocatalytic H2 evolution
摘要： Developing low-cost, environment-friendly and highly-active nanocomposites for photocatalytic hydrogen evolution reaction (HER) holds pivotal function in water splitting. Supported cocatalysts on semiconductor can facilitate speedy transfer and separation of photoexcited charge, active interfacial response and suppress photocorrosion. We, for the first time, proposed a novel strategy to formed 2D-2D (two dimensional) nanocomposites by loading 2D P-doped Ni2S (Ni2SP) cocatalysts onto 2D CdS nanosheets (NSs). The as-obtained 2D-2D CdS/Ni2SP nanocomposites exhibited excellent HER activity in 0.25 M Na2S-Na2SO3 sacrificial solution under visible light (λ ≥ 420 nm). The optimal loading of 2 wt% 2D Ni2SP on 2D CdS as a cocatalyst yielded an optimal H2 production rate at 18.96 mmol g-1 h-1, which was approximately 3.26 folds higher than that of bare 2D CdS (5.82 mmol g-1 h-1) without cocatalysts. In the presence of non-precious metal, the highest apparent quantum efficiency of 4.8% was recorded at 420 nm. The enhanced photocatalytic HER activity was attributed to the excellent interfacial coupling effects of Ni2SP NSs cocatalyst with CdS NSs, which was essential for the rapid charge separation and transfer, increased number of active sites and improved H2-evolution kinetics. This study offers a feasible scheme to design efficient photocatalysts system to produce hydrogen.
关键词： Charge separation and transfer,2D-2D nanojunctions,P-doped Ni2S (Ni2SP) cocatalysts,Photocatalytic hydrogen evolution reaction
更新于2025-09-23 15:19:57
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Establishing high photocatalytic H2 evolution from multiwalled titanate nanotubes
摘要： Black TiO2 in various forms has been investigated for numerous photochemical applications. In photocatalytic water splitting, “grey” titania can reach considerable H2 generation rates without using a noble metal co-catalyst. Up to now, a variety of anatase powders or other morphologies has been investigated in grey and black forms. Here we describe that hydrothermal titanate/anatase nanotubes can show a strong noble metal free photocatalytic activity. For optimized “blackening” conditions, a drastically higher photocatalytic H2 production can be obtained than for other nanoscale morphologies. This effect can further be improved with a very mild Pt doping that again shows a clearly stronger photocatalytic H2 production than comparably loaded nanopowders.
关键词： hydrothermal titania nanotubes,hydrogenation,absorption,photocatalysis,hydrogen evolution
更新于2025-09-23 15:19:57
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Self-assembled shape evolution of the domain wall and formation of nanodomain wall traces induced by multiple IR laser pulse irradiation in lithium niobate
摘要： The formation of the domain structure in congruent lithium niobate crystals by multiple pulse irradiation using an infrared laser was studied experimentally. The qualitative change of the domain wall shape with an increase of the pulse number was revealed. The chains of isolated nanodomains representing the domain wall traces appeared after each laser pulse irradiation in the samples with an irradiated polar surface covered by an indium–tin oxide layer. This effect allowed extraction of the detailed information about the evolution of the domain wall shape. The domain kinetics under the action of the pyroelectric field has been considered. The mechanism of the self-assembled shape evolution of the moving domain wall as a result of the local wall accelerations and retardations caused by the shape fluctuations (bumps and valleys) was proposed. The experimentally observed formation of the quasi-regular comb-like domain structures with randomly distributed bumps and valleys was confirmed by computer simulation. The discovered effects allowed us to create the stable random and quasi-regular domain structures and open the way for further development of the domain engineering methods.
关键词： pyroelectric field,infrared laser,nanodomains,domain wall shape evolution,lithium niobate,domain structure
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Methodology for Predicting Flexible Photovoltaic Cell Life using Accelerated Tests
摘要： Low-density parity-check (LDPC) codes with very long block lengths are well known for their powerful error correction, but it is not always desirable to employ long codes in communication systems, where latency is a serious issue, such as voice and video communication between multiple users. Finite length analyses of LDPC codes have already been presented in the literature for the additive white Gaussian noise channel, but in this paper, we consider the finite length analysis of LDPC codes for channels that exhibit impulsive noise. First, an exact uncoded bit error probability (BEP) of an impulsive noise channel, modeled as a symmetric α-stable (SαS) distribution, is derived. Then, to obtain the LDPC-coded performance, density evolution is applied to evaluate the asymptotic performance of LDPC codes on SαS channels and determine the threshold signal-to-noise ratio. Finally, we derive closed-form expressions for the BEP and block error probability of short LDPC codes on these channels, which are shown to match closely with simulated results on channels with different levels of impulsiveness, even for block lengths as low as 1000 b.
关键词： impulsive noise,density evolution,finite length analysis,LDPC codes
更新于2025-09-23 15:19:57
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Plasmonic Cocatalyst with Electric and Thermal Stimuli Boots Solar Hydrogen Evolution
摘要： Exploring low-cost and high-activity cocatalysts cooperated with semiconductors is a prerequisite to advance cost-efficient photocatalytic water splitting. Herein, nickel nanoparticles (NNPs) loaded on graphitic carbon nitride (CN) as unique non-noble metal cocatalysts with electric and thermal excitation upon surface plasmon for photocatalytic hydrogen (H2) evolution reaction (HER) are designed. The plasmonic NNPs not only endow highly active sites, steering hot electron extraction from excited CN toward HER against charge recombination, but also act as full-spectrum light-harvesting antennas enabling plasmon heating for kinetic acceleration. As a result, the optimized CN/NNP hybrid exhibits a significant increase in the H2-evolution rate up to 13.23 mmol g?1 h?1 with temperature up to 73 °C within 2 h, which far surpasses bare CN and even outperforms CN/Pt hybrid. This work describes the capacity of plasmonic cocatalysts to convert the supplementary photon flux into numerous stimuli, which provides new inspirations for designing photocatalytic systems for solar energy conversion.
关键词： electron transfer,photothermal effect,photocatalytic H2 evolution,metal plasmons,cocatalysts
更新于2025-09-23 15:19:57
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Plasmonic-induced overgrowth of amorphous molybdenum sulfide on nanoporous gold: An ambient synthesis method of hybrid nanoparticles with enhanced electrocatalytic activity
摘要： Hybrid materials of earth abundant transition metal dichalcogenides and noble metal nanoparticles, such as molybdenum sulfide (MoSx) and gold nanoparticles, exhibit synergistic effects that can enhance electrocatalytic reactions. However, most current hybrid MoSx-gold synthesis requires an energy intensive heat source of >500 ○C or chemical plating to achieve deposition of MoSx on the gold surface. Herein, we demonstrate the direct overgrowth of MoSx over colloidal nanoporous gold (NPG), conducted feasibly under ambient conditions, to form hybrid particles with enhanced electrocatalytic performance toward hydrogen evolution reaction. Our strategy exploits the localized surface plasmon resonance-mediated photothermal heating of NPG to achieve >230 ○C surface temperature, which induces the decomposition of the (NH4)2MoS4 precursor and direct overgrowth of MoSx over NPG. By tuning the concentration ratio between the precursor and NPG, the amount of MoSx particles deposited can be systematically controlled from 0.5% to 2% of the Mo/(Au + Mo) ratio. Importantly, we find that the hybrid particles exhibit higher bridging and an apical S to terminal S atomic ratio than pure molybdenum sulfide, which gives rise to their enhanced electrocatalytic performance for hydrogen evolution reaction. We demonstrate that hybrid MoSx-NPG exhibits >30 mV lower onset potential and a 1.7-fold lower Tafel slope as compared to pure MoSx. Our methodology provides an energy- and cost-efficient synthesis pathway, which can be extended to the synthesis of various functional hybrid structures with unique properties for catalysis and sensing applications.
关键词： molybdenum sulfide,electrocatalytic activity,nanoporous gold,hydrogen evolution reaction,plasmonic
更新于2025-09-23 15:19:57
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Analytical mechanics modeling of residual stress in laser powder bed considering flow hardening and softening
摘要： Residual stress builds up during the fabrication of components via laser powder bed fusion (L-PBF) process which causes parts to fail due to the crack initiation and growth, low fatigue life, and fall outside of the specified dimensions. During the thermal loading, the grain size affected by strain hardening and flow softening is altered at the subsurface through dynamic recrystallization (DRx) and subsequent recovery. The yield strength of the alloys is largely determined by the size of nucleated grains, and it has a substantial influence on flow stress and residual stress build-up. In this work, a physics-based analytical model is proposed to predict the residual stress affected by the strain hardening, flow softening, and microstructural evolution during L-PBF process with IN718 as a material system for exploration. The temperature field is predicted using a transient moving point heat source approach. Due to the non-uniform heating, materials experience high thermal stress which may exceed the yield strength of the material. The thermal stress is obtained from Green’s functions of stresses due to the point body load. A material constitutive flow stress model known as Johnson-Cook is used to determine the yield surface. This flow stress model is modified to incorporate the effects of flow softening and grain size. The dynamic recrystallization and grain refinement models are used to calculate the grain size using recrystallized volume fraction from nucleation and growth rates. As a result of the cyclic heating and cooling and the fact that the material is yielded, the residual stress build-up is precited using incremental plasticity and kinematic hardening behavior of the metal according to the property of volume invariance in plastic deformation in coupling with the equilibrium and compatibility conditions. Results from the analytical residual stress model showed good agreement with X-ray diffraction measurements used to determine the residual stresses in the IN718 specimens built via L-PBF.
关键词： Residual stress,Microstructure evolution,Strain hardening,Flow softening,Laser powder bed fusion
更新于2025-09-23 15:19:57
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Optical Fiber Transducer for Monitoring Single-Phase and Two-Phase Flows in Pipes
摘要： This paper presents a cooperative differential evolution (DE) with multiple populations for multiobjective optimization. The proposed algorithm has M single-objective optimization subpopulations and an archive population for an M-objective optimization problem. An adaptive DE is applied to each subpopulation to optimize the corresponding objective of the multiobjective optimization problem (MOP). The archive population is also optimized by an adaptive DE. The archive population is used not only to maintain all nondominated solutions found so far but also to guide each subpopulation to search along the whole Pareto front. These (M + 1) populations cooperate to optimize all objectives of the MOP by using adaptive DEs. Simulation results on benchmark problems with two, three, and many objectives show that the proposed algorithm is better than some state-of-the-art multiobjective DE algorithms and other popular multiobjective evolutionary algorithms. The online search behavior and parameter sensitivity of the proposed algorithm are also investigated.
关键词： cooperative populations,differential evolution,archive search,multiobjective optimization,many-objective optimization
更新于2025-09-23 15:19:57
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A facile in situ growth of CdS quantum dots on covalent triazine-based frameworks for photocatalytic H2 production
摘要： CdS quantum dots (QDs) are excellent visible-light-driven photocatalysts due to their unique small size (<10 nm), suitable band energy structure, and short charge transportation length. Unfortunately, the easy aggregation of CdS QDs to form larger particles results in a higher recombination rate for photoinduced electron-hole pairs, which deteriorates the photocatalytic activity. Here, we report in situ growth of CdS QDs with high dispersion and stability on covalent triazine-based frameworks (CTFs) via a facile photoreduction method. The photocatalytic H2 evolution activity of CdS QD-loaded CTFs is effectively enhanced to approximately 55 and 4 times than that of pristine CTFs and bulk CdS, respectively. This enhanced photocatalytic performance is mainly ascribed to the higher separation rate of photogenerated carriers resulting from synergistic QD-on-sheet interactions between CdS QDs and CTFs. This work develops an efficient one-pot strategy to prepare metal-sulfide QDs with high dispersion and underlines the potential of utilizing CTFs as a suitable platform to develop efficient photocatalytic systems.
关键词： In situ growth,CdS QDs,Photocatalysis,Visible light,H2 evolution,Covalent triazine-based frameworks
更新于2025-09-23 15:19:57