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31.
Web‐Like Interconnected Carbon Networks from NaCl‐Assisted Pyrolysis of ZIF‐8 for Highly Efficient Oxygen Reduction Catalysis 下载免费PDF全文
Yuhong Qian Tao An Karl Erik Birgersson Zhaolin Liu Dan Zhao 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(16)
The oxygen reduction reaction (ORR) is under intense research due to its significance in energy storage and conversion processes. Recent studies show that interconnected and hierarchically porous structures can further enhance ORR kinetics as well as catalyst durability, but their preparation can be quite time and/or chemical consuming. Here, a simple approach is reported to prepare such complex structures by pyrolyzing composites containing NaCl and ZIF‐8. The templating effect of molten NaCl connects ZIF‐8 particles into web‐like carbon networks. During ORR activity measurements, it achieves a 0.964 V onset potential and a 38 mV dec?1 Tafel slope, which are comparable to those of the benchmark Pt/C (0.979 V and 40 mV dec?1). Due to the metal‐free feature, this catalyst exhibits a 16 mV shift in half‐wave potential after a 10 000‐cycle durability test, which is only 60% of that of Pt/C. The catalyst is also tested in Zn–air batteries and the assemblies are able to work at above 1.2 V for 140 h, which triples the life held by those with Pt/C. This study demonstrates a facile strategy to prepare metal‐free ORR catalysts with interconnectivity and hierarchical porosity, and proves their great potentials in ORR catalysis and Zn–air batteries. 相似文献
32.
Mostafizur Rahman Rana Erik Upol Biswas Sultan Mahmud Salman Meem Sahel Syeda Sarita Hassan Mahdy Rahman Chowdhury Mahdy 《Advanced Engineering Materials》2023,25(20):2300438
Electromagnetic wideband absorption is still perceived as a critical and formidable challenge to address with an unambiguous photonic absorber. Subwavelength metamaterial (MM) unit cells with unique and controlled features have recently gained considerable interest. However, meta-atoms, generated using a quantum-inspired pattern distribution, are underwhelming in existing literature to design photonic absorbers and their potential application to manufacture solar sails is still quite uncommon. In this article, to create a flexible, polarization-insensitive, ultrathin, and broadband MM absorber, quantum interference pattern-inspired design is utilized. Herein, a novel approach to fabricating solar sails for the space exploration incorporates the proposed broadband photonic absorber rather than conventional reflectors. The quantum-inspired meta-absorber (QIMA) exhibits an absorption of over 91% for the visible domain, i.e., 380–800 nm under a conventional plane-polarized source. It is shown in the study that broadband absorbers are almost equivalent to excellent reflectors to design the solar sails in terms of the time-averaged force calculated by utilizing the Maxwell stress tensor method. Thus, the QIMA has the potential to be a viable alternative to reflectors in the design of futuristic solar sails for space exploration. The interference theory model is also utilized to assure the dependability of calculated data, and additionally, the standard AM1.5 solar spectrum is utilized to demonstrate the QIMA's solar-harvesting potentiality. 相似文献
33.
34.
Esben Lindgaard Erik Lund 《Computer Methods in Applied Mechanics and Engineering》2010,199(37-40):2319-2330
The paper presents an approach to nonlinear buckling fiber angle optimization of laminated composite shell structures. The approach accounts for the geometrically nonlinear behaviour of the structure by utilizing response analysis up until the critical point. Sensitivity information is obtained efficiently by an estimated critical load factor at a precritical state. In the optimization formulation, which is formulated as a mathematical programming problem and solved using gradient-based techniques, a number of the lowest buckling factors are included such that the risk of “mode switching” during optimization is avoided. The presented optimization formulation is compared to the traditional linear buckling formulation and two numerical examples, including a large laminated composite wind turbine main spar, to clearly illustrate the pitfalls of the traditional formulation and the advantage and potential of the presented approach. 相似文献
35.
Explanation and reliability of prediction models: the case of breast cancer recurrence 总被引:1,自引:1,他引:0
Erik ?trumbelj Zoran Bosni? Igor Kononenko Branko Zakotnik Cvetka Gra?i? Kuhar 《Knowledge and Information Systems》2010,24(2):305-324
In this paper, we describe the first practical application of two methods, which bridge the gap between the non-expert user
and machine learning models. The first is a method for explaining classifiers’ predictions, which provides the user with additional
information about the decision-making process of a classifier. The second is a reliability estimation methodology for regression
predictions, which helps the users to decide to what extent to trust a particular prediction. Both methods are successfully
applied to a novel breast cancer recurrence prediction data set and the results are evaluated by expert oncologists. 相似文献
36.
Improved PLSOM algorithm 总被引:1,自引:1,他引:0
Erik Berglund 《Applied Intelligence》2010,32(1):122-130
The original Parameter-Less Self-Organising Map (PLSOM) algorithm was introduced as a solution to the problems the Self-Organising
Map (SOM) encounters when dealing with certain types of mapping tasks. Unfortunately the PLSOM suffers from over-sensitivity
to outliers and over-reliance on the initial weight distribution. The PLSOM2 algorithm is introduced to address these problems
with the PLSOM. PLSOM2 is able to cope well with outliers without exhibiting the problems associated with the standard PLSOM
algorithm. The PLSOM2 requires very little computational overhead compared to the standard PLSOM, thanks to an efficient method
of approximating the diameter of the inputs, and does not rely on a priori knowledge of the training input space. This paper
provides a discussion of the reasoning behind the PLSOM2 and experimental results showing its effectiveness for mapping tasks. 相似文献
37.
Making changes to software systems can prove costly and it remains a challenge to understand the factors that affect the costs
of software evolution. This study sought to identify such factors by investigating the effort expended by developers to perform
336 change tasks in two different software organizations. We quantitatively analyzed data from version control systems and
change trackers to identify factors that correlated with change effort. In-depth interviews with the developers about a subset
of the change tasks further refined the analysis. Two central quantitative results found that dispersion of changed code and
volatility of the requirements for the change task correlated with change effort. The analysis of the qualitative interviews
pointed to two important, underlying cost drivers: Difficulties in comprehending dispersed code and difficulties in anticipating
side effects of changes. This study demonstrates a novel method for combining qualitative and quantitative analysis to assess
cost drivers of software evolution. Given our findings, we propose improvements to practices and development tools to manage
and reduce the costs. 相似文献
38.
The multi-mode resource-constrained project scheduling problem (MRCPSP) involves the determination of a baseline schedule of the project activities, which can be executed in multiple modes, satisfying the precedence relations and resource constraints while minimizing the project duration. During the execution of the project, the baseline schedule may become infeasible due to activity duration and resource disruptions. We propose and evaluate a number of dedicated exact reactive scheduling procedures as well as a tabu search heuristic for repairing a disrupted schedule, under the assumption that no activity can be started before its baseline starting time. We report on promising computational results obtained on a set of benchmark problems. 相似文献
39.
In a 2008 paper, Walmsley argued that the explanations employed in the dynamical approach to cognitive science, as exemplified
by the Haken, Kelso and Bunz model of rhythmic finger movement, and the model of infant preservative reaching developed by
Esther Thelen and her colleagues, conform to Carl Hempel and Paul Oppenheim’s deductive-nomological model of explanation (also
known as the covering law model). Although we think Walmsley’s approach is methodologically sound in that it starts with an
analysis of scientific practice rather than a general philosophical framework, we nevertheless feel that there are two problems
with his paper. First, he focuses only on the deductivenomological model and so neglects the important fact that explanations
are causal. Second, the explanations offered by the dynamical approach do not take the deductive-nomological format, because
they do not deduce the explananda from exceptionless laws. Because of these two points, Walmsley makes the dynamical explanations
in cognitive science appear problematic, while in fact they are not. 相似文献
40.
Classifying species of individual trees by intensity and structure features derived from airborne laser scanner data 总被引:3,自引:0,他引:3
Hans Ole Ørka Erik Næsset Ole Martin Bollandsås 《Remote sensing of environment》2009,113(6):1163-3342
The objective of this study was to identify candidate features derived from airborne laser scanner (ALS) data suitable to discriminate between coniferous and deciduous tree species. Both features related to structure and intensity were considered. The study was conducted on 197 Norway spruce and 180 birch trees (leaves on conditions) in a boreal forest reserve in Norway. The ALS sensor used was capable of recording multiple echoes. The point density was 6.6 m− 2. Laser echoes located within the vertical projection of the tree crowns, which were assumed to be circular and defined according to field measurements, were attributed to three categories: “first echoes of many”, “single echoes”, or “last echoes of many echoes”. They were denoted FIRST, SINGLE, and LAST, respectively. In tree species classification using ALS data features should be independent of tree heights. We found that many features were dependent on tree height and that this dependency influenced selection of candidate features. When we accounted for this dependency, it was revealed that FIRST and SINGLE echoes were located higher and LAST echoes lower in the birch crowns than in spruce crowns. The intensity features of the FIRST echoes differed more between species than corresponding features of the other echo categories. For the FIRST echoes the intensity values tended to be higher for birch than spruce. When using the various features for species classification, maximum overall classification accuracies of 77% and 73% were obtained for structural and intensity features, respectively. Combining candidate features related to structure and intensity resulted in an overall classification accuracy of 88%. 相似文献