AbstractA building façade is affected by the environment as well as the physical performances of the building-materials at every stage of the building’s life cycle. Although a number of studies have ...been conducted to overcome the nonsustainable conditions of building façade, they mostly focus on cost-based design. Accordingly, previous studies did not incorporate critical issues such as the durability of building façade at the design stage; therefore, a process for the selection of optimal façade materials is needed, with a particular consideration of durability, as well as the functional and economic performances of the materials. The aim of this study is therefore the development of the corresponding decision-making process for the selection of façade materials to minimize the potential defects at the design stage. The case study reveals that the priority of the material options for building façade can be changed if minimum 30% weighting of the durability for each option is reflected on the decision-making process. The research contribution here is the incorporation of a value-based decision-making process during the selection of optimal façade materials for sustainability.
AbstractThe selection of materials for a sustainable building façade has various requirements, which include the analysis of economic performance, as well as the physical performance at every stage ...of their life cycle. Previous research efforts have focused on buildings and building systems in terms of critical issues of life cycle cost (LCC). Concomitantly, little research has been reported on calculating the LCC of façade material for a building at the design stage; LCC is a critical issue in the selection of facade materials. In particular, investments in long-life elements, such as building façade materials, are characterized by uncertainties regarding service life, operation and maintenance costs, revenues, and other factors that affect project economics. Therefore, it is essential to review uncertainties affecting these variable factors in computing LCC. This research aims to develop a process for calculating the probabilistic LCC of building facade materials throughout their life cycle. The research method includes life cycle cost analysis (LCCA) and failure mode, effect, and criticality analysis (FMECA) as research methodologies. Thus, the original contribution of this research is the development of a probabilistic LCC assessment within the decision-making process of selecting optimal facade materials of buildings at an early stage. The case study shows that with new, closer replacement cost estimates based on a probabilistic approach, the uncertainty could be reduced, and the confidence index (CI) improved; the alternative with a lower LCC may be implemented with reasonable assurance that it will have the lowest costs over its lifetime.
PurposeThe purpose of the paper is to develop a method to integrate the schedule-based analysis with a productivity-based analysis to prove and support the result of the damages ...calculation.Design/methodology/approachIn this paper, a “cost and schedule impact integration” (CSI2) model is proposed to objectively show and estimate lost productivity due to changes in construction projects.FindingsA schedule-based analysis to include separate tracking of change order costs can be used to predict productivity due to the delay and disruption; changes in construction projects almost always result in delay and disruption. However, the schedule-based analysis needs to be integrated with a productivity-based analysis to prove and support the result of the damages calculation.Practical implicationsThe results of this study expand upon construction practices for proving and quantifying lost productivity due to changes in construction projects.Originality/valueThe contribution of the paper is summarized as the introduction of a “schedule impact analysis” into a “cost impact analysis” technique to assess the damages, as well as to demonstrate the labor productivity impact due to delay and disruption in construction projects.
Highlights
One-dimensional CoSe
2
nanorods supported on three-dimensional microspheres were prepared via spray pyrolysis.
Nanorods were coated by N-doped graphitic C and polydopamine-derived C.
The ...unique nanostructure exhibits exceptional cycling stability (5000 cycles at 2.0 A g
−1
).
Metal–organic framework-templated nitrogen-doped graphitic carbon (NGC) and polydopamine-derived carbon (PDA-derived C)-double coated one-dimensional CoSe
2
nanorods supported highly porous three-dimensional microspheres are introduced as anodes for excellent Na-ion batteries, particularly with long-lived cycle under carbonate-based electrolyte system. The microspheres uniformly composed of ZIF-67 polyhedrons and polystyrene nanobeads (
ϕ
= 40 nm) are synthesized using the facile spray pyrolysis technique, followed by the selenization process (P-CoSe
2
@NGC NR). Further, the PDA-derived C-coated microspheres are obtained using a solution-based coating approach and the subsequent carbonization process (P-CoSe
2
@PDA-C NR). The rational synthesis approach benefited from the synergistic effects of dual carbon coating, resulting in a highly conductive and porous nanostructure that could facilitate rapid diffusion of charge species along with efficient electrolyte infiltration and effectively channelize the volume stress. Consequently, the prepared nanostructure exhibits extraordinary electrochemical performance, particularly the ultra-long cycle life stability. For instance, the advanced anode has a discharge capacity of 291 (1000th cycle, average capacity decay of 0.017%) and 142 mAh g
−1
(5000th cycle, average capacity decay of 0.011%) at a current density of 0.5 and 2.0 A g
−1
, respectively.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Golden bristlegrass‐like unique nanostructures comprising reduced graphene oxide (rGO) matrixed nanofibers entangled with bamboo‐like N‐doped carbon nanotubes (CNTs) containing CoSe2 nanocrystals at ...each node (denoted as N‐CNT/rGO/CoSe2 NF) are designed as anodes for high‐rate sodium‐ion batteries (SIBs). Bamboo‐like N‐doped CNTs (N‐CNTs) are successfully generated on the rGO matrixed nanofiber surface, between rGO sheets and mesopores, and interconnected chemically with homogeneously distributed rGO sheets. The defects in the N‐CNTs formed by a simple etching process allow the complete phase conversion of Co into CoSe2 through the efficient penetration of H2Se gas inside the CNT walls. The N‐CNTs bridge the vertical defects for electron transfer in the rGO sheet layers and increase the distance between the rGO sheets during cycles. The discharge capacity of N‐CNT/rGO/CoSe2 NF after the 10 000th cycle at an extremely high current density of 10 A g−1 is 264 mA h g−1, and the capacity retention measured at the 100th cycle is 89%. N‐CNT/rGO/CoSe2 NF has final discharge capacities of 395, 363, 328, 304, 283, 263, 246, 223, 197, 171, and 151 mA h g−1 at current densities of 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 A g−1, respectively.
As high‐performance anodes for sodium‐ion batteries, golden bristlegrass‐like graphene nanofibers entangled with N‐doped CNTs containing CoSe2 nanocrystals are designed and synthesized. The synthesized unique nanostructure exhibits high cycling and rate performances even at extremely high current densities. The synergistic effect of the golden bristlegrass‐like unique structure and the N‐doped CNTs/graphene composite results in efficient anode materials for sodium‐ion batteries.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The importance of surface finishing processes and accurate surface quality prediction models has increased in response to the growing demand for improved surface finish in ultra-precision ...applications. To enhance process efficiency and develop accurate predictive models, numerous studies have investigated the monitoring and prediction of surface roughness. However, existing mathematical approaches encounter challenges in establishing the correlation between input and output variables and providing real-time surface status monitoring. Therefore, this study aimed to monitor and predict surface roughness in real-time for the rotational electro-magnetic finishing (REMF) process using acoustic emission (AE) signals. First, a total of 72 fundamental experiments were conducted based on the mixed orthogonal array L
18
(2
1
×
3
4
) to determine the optimal configuration for achieving a high-quality surface. The results revealed that the best combination was achieved with an abrasive length of 3.0 mm, an abrasive diameter of 0.7 mm, a total abrasive weight of 2.0 kg, a rotational speed of 1800 rpm, and a working time of 10 min. To analyze signal features and develop an accurate surface prediction model, a convolutional neural network (CNN) was suggested, utilizing scalogram images as time–frequency characteristics of AE signals. The suggested model demonstrated outstanding quantitative results compared to those of the regression model, with training coefficient of determination (
R
2
), mean squared error (MSE), and
F
-test of 0.986, 0.19
×
10
−3
, and 99%, and testing
R
2
, MSE, and
F
-test of 0.951, 2.23
×
10
−3
, and 99%, respectively. In addition, the suggested model showed good generalization ability with a relatively lower mean MSE of 0.003 through verification experiments. These results demonstrated that the sensory data and image-driven model were effective in real-time monitoring and surface roughness prediction in the REMF process with high accuracy and reliability.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
AbstractDisruption to continuous workflow is a major cause of cost overruns affecting many construction projects, especially for repetitive construction. The compensatory claims for damages including ...disruption are different from damages due to delay because of the complex characteristics of disruption per se. To estimate the cumulative damages due to disruptions, all the possible issues of damages caused by interruption of workflow should be considered. Various methods have been proposed in the literature for analyzing the impact on schedules and the damages resulting from disruptions. However, these methods have a limitation because they do not consider the ripple effect of disruptions. This paper proposes a modified method that can reasonably estimate damages caused by disruptions in construction projects, especially for repetitive construction. The proposed method includes the resource continuity and earned value analysis research methodologies to forecast the direct effect of disruptions. In addition, earned value management (EVM) is utilized to demonstrate and forecast the ripple effect of disruptions on construction activities. The original contribution of the paper is summarized as (1) application of EVM to the topic of damage calculations due to changed process sequence and (2) development of a method to assess the ripple effect as well as the direct effect of disruptions on project productivity performance.
Hierarchically well‐developed porous graphene nanofibers comprising N‐doped graphitic C (NGC)‐coated cobalt oxide hollow nanospheres are introduced as anodes for high‐rate Li‐ion batteries. For this, ...three strategies, comprising the Kirkendall effect, metal–organic frameworks, and compositing with highly conductive C, are applied to the 1D architecture. In particular, NGC layers are coated on cobalt oxide hollow nanospheres as a primary transport path of electrons followed by graphene‐nanonetwork‐constituting nanofibers as a continuous and secondary electron transport path. Superior cycling performance is achieved, as the unique nanostructure delivers a discharge capacity of 823 mAh g−1 after 500 cycles at 3.0 A g−1 with a low decay rate of 0.092% per cycle. The rate capability is also noteworthy as the structure exhibits high discharge capacities of 1035, 929, 847, 787, 747, 703, 672, 650, 625, 610, 570, 537, 475, 422, 294, and 222 mAh g−1 at current densities of 0.5, 1.5, 3, 5, 7, 10, 12, 15, 18, 20, 25, 30, 40, 50, 80, and 100 A g−1, respectively. In view of the highly efficient Li+ ion/electron diffusion and high structural stability, the present nanostructuring strategy has a huge potential in opening new frontiers for high‐rate and long‐lived stable energy storage systems.
Hierarchically well‐developed porous graphene nanofibers comprising N‐doped graphitic C‐coated cobalt oxide hollow nanospheres are introduced as anodes for high‐rate Li‐ion batteries. In view of the highly efficient Li+ ion/electron diffusion and high structural stability, the unique nanostructuring strategy has a huge potential in opening new frontiers for high‐rate and long‐lived stable energy storage systems.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The introduction of a functional interlayer between the cathode and anode in lithium-sulfur battery (LSB) technology results in significant improvements in electrochemical performance. Here, we ...developed hierarchically structured porous, conductive, and multifunctional N-doped carbon (N-C) nanofibers comprising homogeneously dispersed vanadium nitride quantum dots and hollow N-C nanocages as functional interlayers for advanced LSBs. The freestanding interlayer contains well-developed long-range channels and numerous interconnected hollow N-C nanocages derived from the metal-organic framework. Furthermore, the presence of a N-C framework and vanadium nitride quantum dots measuring several nanometers improves the redox reaction kinetics and provides numerous chemisorption sites for the effective trapping and reuse of lithium polysulfide. As a result, the assembled Li-S cell employing the unique nanostructured freestanding interlayer exhibits superior rate capability and stable cycling performance (decay rate of 0.02% per cycle at 0.5C) considering the high sulfur content (80 wt%) and loading (
ca.
4 mg cm
−2
) in the sulfur electrodes. Even with an ultra-high sulfur loading of 11.0 mg cm
−2
, the Li-S cell delivered a stable areal capacity of 5.0 mA h cm
−2
after 100 charge-discharge cycles at 0.05C. Thus, the uniquely nanostructured interlayer shows high potential for the development of advanced LSBs utilizing pure sulfur electrodes with realistic battery parameters.
Herein, a hierarchically developed multifunctional, porous, and freestanding interlayer is utilized for efficient polysulfide absorption and superior electrochemical performance in lithium-sulfur cells with sulfur cathode and low electrolyte volume.
