scholarly journals Comprehensive Evaluation for Protective Coatings: Optical, Electrical, Photoelectrochemical, and Spectroscopic Characterizations

2022 ◽  
Vol 9 ◽  
Author(s):  
Xin Shen ◽  
Rito Yanagi ◽  
Devan Solanki ◽  
Haoqing Su ◽  
Zhaohan Li ◽  
...  
Keyword(s):  
Charge Separation ◽  
Performance Metrics ◽  
Comprehensive Evaluation ◽  
Protective Coatings ◽  
Aqueous Electrolytes ◽  
Figures Of Merit ◽  
Transport Loss ◽  
Low Charge ◽  
Testing Protocols ◽  
Pec Water Splitting

Numerous efficient semiconductors suffer from instability in aqueous electrolytes. Strategies utilizing protective coatings have thus been developed to protect these photoabsorbers against corrosion while synergistically improving charge separation and reaction kinetics. Recently, various photoelectrochemical (PEC) protective coatings have been reported with suitable electronic properties to ensure low charge transport loss and reveal the fundamental photoabsorber efficiency. However, protocols for studying the critical figures of merit for protective coatings have yet to be established. For this reason, we propose four criteria for evaluating the performance of a protective coating for PEC water-splitting: stability, conductivity, optical transparency, and energetic matching. We then propose a flow chart that summarizes the recommended testing protocols for quantifying these four performance metrics. In particular, we lay out the stepwise testing protocols to evaluate the energetics matching at a semiconductor/coating/(catalyst)/liquid interface. Finally, we provide an outlook for the future benchmarking needs for coatings.

Persistent memory hash indexes

2021 ◽  
Vol 14 (5) ◽  
pp. 785-798
Author(s):  
Daokun Hu ◽  
Zhiwen Chen ◽  
Jianbing Wu ◽  
Jianhua Sun ◽  
Hao Chen
Keyword(s):  
Future Development ◽  
High Performance ◽  
Performance Metrics ◽  
Comprehensive Evaluation ◽  
State Of The Art ◽  
Hash Tables ◽  
Trade Offs ◽  
Depth Analysis ◽  
Persistent Memory ◽  
Memory Modules

Persistent memory (PM) is increasingly being leveraged to build hash-based indexing structures featuring cheap persistence, high performance, and instant recovery, especially with the recent release of Intel Optane DC Persistent Memory Modules. However, most of them are evaluated on DRAM-based emulators with unreal assumptions, or focus on the evaluation of specific metrics with important properties sidestepped. Thus, it is essential to understand how well the proposed hash indexes perform on real PM and how they differentiate from each other if a wider range of performance metrics are considered. To this end, this paper provides a comprehensive evaluation of persistent hash tables. In particular, we focus on the evaluation of six state-of-the-art hash tables including Level hashing, CCEH, Dash, PCLHT, Clevel, and SOFT, with real PM hardware. Our evaluation was conducted using a unified benchmarking framework and representative workloads. Besides characterizing common performance properties, we also explore how hardware configurations (such as PM bandwidth, CPU instructions, and NUMA) affect the performance of PM-based hash tables. With our in-depth analysis, we identify design trade-offs and good paradigms in prior arts, and suggest desirable optimizations and directions for the future development of PM-based hash tables.

scholarly journals Creation of Hybrid Photoactive Inorganic/Organic Interface Assemblies of Cadmium Oxide mixtures (CdO2/CdO)/Poly-2,2-Bithiophene; Optical and Photoelectrochemical Investigations

2017 ◽  
Vol 9 (4) ◽  
pp. 71
Author(s):  
Kasem K. Kasem ◽  
Henry Worley ◽  
Ashley Lovins
Keyword(s):  
Charge Separation ◽  
Cadmium Oxide ◽  
Equilibrium Mixture ◽  
Organic Polymer ◽  
Aqueous Electrolytes ◽  
Charge Generation ◽  
Transfer Processes ◽  
Organic Interfaces ◽  
Band Alignments ◽  
Induced Charge

Nanoparticles of cadmium peroxide (CdO2) were immobilized in poly 2,2 bithiophene (PBTh) to build photoactive inorganic/organic interfaces (I/O/I). Studies indicated that the CdO2 initially immobilized in the organic polymer partially decomposed to a low band gap CdO. Therefore we refer to this mixture as CdO2/CdO. The CdO2/CdO/PBTh assemblies were subjected to optical and photoelectrochemical investigations in aqueous electrolytes containing acetate, nitrate, or phosphate. The equilibrium mixture of CdO2/CdO influenced the optical conductivity and dielectric contents of the assemblies. Furthermore, O2 played an important role in the charge separation and transfer processes. The effects of an applied magnetic field were investigated and reported. The results were explained on the basis of formation of hybrid sub-bands due to band alignments between the assembly components. The photo-induced charge generation of PBTh was improved by occlusion of CdO2 in the polymer as was evident by the greater photocurrent generated by CdO2/CdO/PBTh than that generated by PBTh.

CMIP model evaluation with the ESMValTool v2.0

2020 ◽  
Author(s):  
Axel Lauer ◽  
Fernando Iglesias-Suarez ◽  
Veronika Eyring ◽  
the ESMValTool development team
Keyword(s):  
Model Evaluation ◽  
Large Scale ◽  
Performance Metrics ◽  
Comprehensive Evaluation ◽  
Coupled Model ◽  
Data Sets ◽  
Evaluation Tool ◽  
Emergent Constraints ◽  
Data Volume ◽  
And Performance

<p>The Earth System Model Evaluation Tool (ESMValTool) has been developed with the aim of taking model evaluation to the next level by facilitating analysis of many different ESM components, providing well-documented source code and scientific background of implemented diagnostics and metrics and allowing for traceability and reproducibility of results (provenance). This has been made possible by a lively and growing development community continuously improving the tool supported by multiple national and European projects. The latest version (2.0) of the ESMValTool has been developed as a large community effort to specifically target the increased data volume of the Coupled Model Intercomparison Project Phase 6 (CMIP6) and the related challenges posed by analysis and evaluation of output from multiple high-resolution and complex ESMs. For this, the core functionalities have been completely rewritten in order to take advantage of state-of-the-art computational libraries and methods to allow for efficient and user-friendly data processing. Common operations on the input data such as regridding or computation of multi-model statistics are now centralized in a highly optimized preprocessor written in Python. The diagnostic part of the ESMValTool includes a large collection of standard recipes for reproducing peer-reviewed analyses of many variables across atmosphere, ocean, and land domains, with diagnostics and performance metrics focusing on the mean-state, trends, variability and important processes, phenomena, as well as emergent constraints. While most of the diagnostics use observational data sets (in particular satellite and ground-based observations) or reanalysis products for model evaluation some are also based on model-to-model comparisons. This presentation introduces the diagnostics newly implemented into ESMValTool v2.0 including an extended set of large-scale diagnostics for quasi-operational and comprehensive evaluation of ESMs, new diagnostics for extreme events, regional model and impact evaluation and analysis of ESMs, as well as diagnostics for emergent constraints and analysis of future projections from ESMs. The new diagnostics are illustrated with examples using results from the well-established CMIP5 and the newly available CMIP6 data sets.</p>

scholarly journals Are Current Physical Match Performance Metrics in Elite Soccer Fit for Purpose or Is the Adoption of an Integrated Approach Needed?

2018 ◽  
Vol 13 (5) ◽  
pp. 656-664 ◽  
Author(s):  
Paul S. Bradley ◽  
Jack D. Ade
Keyword(s):  
High Intensity ◽  
Performance Metrics ◽  
Traditional Approach ◽  
Team Sports ◽  
Integrated Approach ◽  
Time Motion ◽  
Fit For Purpose ◽  
Data Collection Technique ◽  
Testing Protocols ◽  
Physical Match

Time–motion analysis is a valuable data-collection technique used to quantify the physical match performance of elite soccer players. For over 40 years, researchers have adopted a “traditional” approach when evaluating match demands by simply reporting the distance covered or time spent along a motion continuum of walking through to sprinting. This methodology quantifies physical metrics in isolation without integrating other factors, and this ultimately leads to a 1-dimensional insight into match performance. Thus, this commentary proposes a novel “integrated” approach that focuses on a sensitive physical metric such as high-intensity running but contextualizes this in relation to key tactical activities for each position and collectively for the team. In the example presented, the integrated model clearly unveils the unique high-intensity profile that exists due to distinct tactical roles, rather than 1-dimensional “blind” distances produced by traditional models. Intuitively, this innovative concept may aid coaches’ understanding of the physical performance in relation to the tactical roles and instructions given to the players. In addition, it will enable practitioners to effectively translate match metrics into training and testing protocols. This innovative model may well aid advances in other team sports that incorporate similar intermittent movements with tactical purpose. Evidence of the merits and application of this new concept is needed before the scientific community accepts this model as it may well add complexity to an area that conceivably needs simplicity.

ZnIn2S4 nanosheet growth on amine-functionalized SiO2 for the photocatalytic reduction of CO2

2021 ◽  
Author(s):  
Yuqing Shao ◽  
Zhaolin Dou ◽  
Xiaoyu Liang ◽  
Xinxin Zhang ◽  
Min Ji ◽  
...  
Keyword(s):  
Charge Separation ◽  
Active Sites ◽  
Separation Efficiency ◽  
Sustainable Energy ◽  
Photocatalytic Reduction ◽  
Amine Functionalized ◽  
Charge Separation Efficiency ◽  
Reduction Of Co2 ◽  
Low Charge

The photocatalytic reduction of CO2 into valuable fuels and sustainable energy has a promising future, yet remains a challenge due to low charge separation efficiency and inadequate active sites. We...

Enhancement of photoelectrochemical performance in ferroelectric films via the introduction of an Au buffer layer

2021 ◽  
Vol 42 (11) ◽  
pp. 112701
Author(s):  
Dawei Cao ◽  
Ming Li ◽  
Jianfei Zhu ◽  
Yanfang He ◽  
Tong Chen ◽  
...  
Keyword(s):  
Electric Field ◽  
Buffer Layer ◽  
Water Splitting ◽  
Charge Separation ◽  
Sol Gel ◽  
Ferroelectric Films ◽  
Photoelectrochemical Performance ◽  
Band Bending ◽  
Polarization Electric Field ◽  
Pec Water Splitting

Abstract The inefficient separation of photogenerated carriers has become a serious problem that limits the photoelectrochemical (PEC) performance of semiconductors. Herein, a sol-gel method was used to prepare BiFeO3 ferroelectric thin films with FTO and FTO/Au as substrates, respectively. The polarization electric field of the ferroelectric can more effectively separate the carriers generated in the photoelectrode. Meanwhile, the introduction of an Au buffer layer can reduce the resistance in the process of charge transfer, accelerate the carrier migration, and enhance the efficiency of the charge separation. Under light irradiation, Au/BiFeO3 photoelectrode exhibited an extraordinary improvement in PEC water splitting compared with BiFeO3. In addition, the ferroelectric polarization electric field causes band bending, which further accelerates the separation of electrons and holes and improves the PEC performance of the photoelectrode. This work promotes the effective application of ferroelectric films in PEC water splitting.

Unified Applicable Propulsion System Performance Metrics

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Oliver Schmitz ◽  
Mirko Hornung
Keyword(s):  
System Performance ◽  
Exergy Analysis ◽  
Performance Metrics ◽  
Aircraft Design ◽  
Electrical Energy ◽  
Propulsion System ◽  
Combustion Engines ◽  
Propulsion Systems ◽  
Figures Of Merit ◽  
Parallel Hybrid

Progress in the development of electrical storage and conversion technology progressively attains focus in aerospace motive power research. Novel propulsion system concepts based on hybrid or even entirely electrical energy sources are seriously considered for aircraft design. To this point, unified figures of merit are required in order to allow for consistent comparative investigations of existing combustion engines and future electrically-based propulsion systems. Firstly, this paper identifies the shortcomings of conventional performance metrics used for nonthermal electrical conversion processes and then approaches exergy-based loss methods as means of metrics extensions. Subsequently, energy source-independent figures of merit based on exergy analysis are derived and embedded into the well-known performance definitions. Finally, the unified metrics are demonstrated through application to a conventional turbofan, a parallel-hybrid turbofan, a novel integrated-hybrid turbofan concept, and an entirely electrical fan concept.

scholarly journals A coating strategy to achieve effective local charge separation for photocatalytic coevolution

2021 ◽  
Vol 118 (7) ◽  
pp. e2023552118
Author(s):  
Tianshuo Zhao ◽  
Rito Yanagi ◽  
Yijie Xu ◽  
Yulian He ◽  
Yuqi Song ◽  
...  
Keyword(s):  
Water Splitting ◽  
Charge Separation ◽  
Protective Coatings ◽  
Photoelectrochemical Cell ◽  
Aqueous Environment ◽  
High Quantum Efficiency ◽  
Solar Water Splitting ◽  
Local Charge ◽  
Protection Strategies ◽  
Bandgap Semiconductors

Semiconductors of narrow bandgaps and high quantum efficiency have not been broadly utilized for photocatalytic coevolution of H2 and O2 via water splitting. One prominent issue is to develop effective protection strategies, which not only mitigate photocorrosion in an aqueous environment but also facilitate charge separation. Achieving local charge separation is especially challenging when these reductive and oxidative sites are placed only nanometers apart compared to two macroscopically separated electrodes in a photoelectrochemical cell. Additionally, the driving force of charge separation, namely the energetic difference in the barrier heights across the two type of sites, is small. Herein, we used conformal coatings attached by nanoscale cocatalysts to transform two classes of tunable bandgap semiconductors, i.e., CdS and GaInP2, into stable and efficient photocatalysts. We used hydrogen evolution and redox-mediator oxidation for model study, and further constructed a two-compartment solar fuel generator that separated stoichiometric H2 and O2 products. Distinct from the single charge-transfer direction reported for conventional protective coatings, the coating herein allows for concurrent injection of photoexcited electrons and holes through the coating. The energetic difference between reductive and oxidative catalytic sites was regulated by selectivity and local kinetics. Accordingly, the charge separation behavior was validated using numerical simulations. Following this design principle, the CdS/TiO2/Rh@CrOx photocatalysts evolved H2 while oxidizing reversible polysulfide redox mediators at a maximum rate of 90.6 μmol⋅h−1⋅cm−2 by stacking three panels. Powered by a solar cell, the redox-mediated solar water-splitting reactor regenerated the polysulfide repeatedly and achieved solar-to-hydrogen efficiency of 1.7%.

scholarly journals A Large-Scale Experimental Evaluation of High-Performing Multi- and Many-Objective Evolutionary Algorithms

2018 ◽  
Vol 26 (4) ◽  
pp. 621-656 ◽  
Author(s):  
Leonardo C. T. Bezerra ◽  
Manuel López-Ibáñez ◽  
Thomas Stützle
Keyword(s):  
Evolutionary Algorithms ◽  
Large Scale ◽  
Performance Metrics ◽  
Comprehensive Evaluation ◽  
Assessment Tools ◽  
Apparent Contradiction ◽  
Multi Objective ◽  
Automatic Algorithm Configuration ◽  
Wide Range ◽  
Evolutionary Operators

Research on multi-objective evolutionary algorithms (MOEAs) has produced over the past decades a large number of algorithms and a rich literature on performance assessment tools to evaluate and compare them. Yet, newly proposed MOEAs are typically compared against very few, often a decade older MOEAs. One reason for this apparent contradiction is the lack of a common baseline for comparison, with each subsequent study often devising its own experimental scenario, slightly different from other studies. As a result, the state of the art in MOEAs is a disputed topic. This article reports a systematic, comprehensive evaluation of a large number of MOEAs that covers a wide range of experimental scenarios. A novelty of this study is the separation between the higher-level algorithmic components related to multi-objective optimization (MO), which characterize each particular MOEA, and the underlying parameters—such as evolutionary operators, population size, etc.—whose configuration may be tuned for each scenario. Instead of relying on a common or “default” parameter configuration that may be low-performing for particular MOEAs or scenarios and unintentionally biased, we tune the parameters of each MOEA for each scenario using automatic algorithm configuration methods. Our results confirm some of the assumed knowledge in the field, while at the same time they provide new insights on the relative performance of MOEAs for many-objective problems. For example, under certain conditions, indicator-based MOEAs are more competitive for such problems than previously assumed. We also analyze problem-specific features affecting performance, the agreement between performance metrics, and the improvement of tuned configurations over the default configurations used in the literature. Finally, the data produced is made publicly available to motivate further analysis and a baseline for future comparisons.

Unified Applicable Propulsion System Performance Metrics

2013 ◽  
Author(s):  
Oliver Schmitz ◽  
Mirko Hornung
Keyword(s):  
System Performance ◽  
Exergy Analysis ◽  
Performance Metrics ◽  
Aircraft Design ◽  
Electrical Energy ◽  
Propulsion System ◽  
Combustion Engines ◽  
Propulsion Systems ◽  
Figures Of Merit ◽  
Parallel Hybrid

Progress in the development of electrical storage and conversion technology progressively attains focus in aerospace motive power research. Novel propulsion system concepts based on hybrid or even entirely electrical energy sources are seriously considered for aircraft design. To this point, unified figures of merit are required in order to allow for consistent comparative investigations of existing combustion engines and future electrically-based propulsion systems. Firstly, this paper identifies the shortcomings of conventional performance metrics used for non-thermal electrical conversion processes and then approaches exergy-based loss methods as means of metrics extensions. Subsequently, energy source-independent figures of merit based on exergy analysis are derived and embedded into the well-known performance definitions. Finally, the unified metrics are demonstrated through application to a conventional turbofan, a parallel-hybrid turbofan, a novel integrated-hybrid turbofan concept and an entirely electrical fan concept.

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