scholarly journals Spatial effect of conical angle on optical-thermal distribution for circumferential photocoagulation

2017 ◽  
Vol 8 (12) ◽  
pp. 5663 ◽  
Author(s):  
Van Gia Truong ◽  
Suhyun Park ◽  
Van Nam Tran ◽  
Hyun Wook Kang
Keyword(s):  
Spatial Effect ◽  
Thermal Distribution ◽  
Conical Angle

scholarly journals A Thermally Conductive Pt/AAO Catalyst for Hydrogen Passive Autocatalytic Recombination

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 491
Author(s):  
Alina E. Kozhukhova ◽  
Stephanus P. du Preez ◽  
Aleksander A. Malakhov ◽  
Dmitri G. Bessarabov
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Combustion Temperature ◽  
Volume Fraction ◽  
Morphological Characteristics ◽  
Al Alloy ◽  
Impregnation Method ◽  
Case Scenario ◽  
Worst Case ◽  
Thermal Distribution

In this study, a Pt/anodized aluminum oxide (AAO) catalyst was prepared by the anodization of an Al alloy (Al6082, 97.5% Al), followed by the incorporation of Pt via an incipient wet impregnation method. Then, the Pt/AAO catalyst was evaluated for autocatalytic hydrogen recombination. The Pt/AAO catalyst’s morphological characteristics were determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The average Pt particle size was determined to be 3.0 ± 0.6 nm. This Pt/AAO catalyst was tested for the combustion of lean hydrogen (0.5–4 vol% H2 in the air) in a recombiner section testing station. The thermal distribution throughout the catalytic surface was investigated at 3 vol% hydrogen (H2) using an infrared camera. The Al/AAO system had a high thermal conductivity, which prevents the formation of hotspots (areas where localized surface temperature is higher than an average temperature across the entire catalyst surface). In turn, the Pt stability was enhanced during catalytic hydrogen combustion (CHC). A temperature gradient over 70 mm of the Pt/AAO catalyst was 23 °C and 42 °C for catalysts with uniform and nonuniform (worst-case scenario) Pt distributions. The commercial computational fluid dynamics (CFD) code STAR-CCM+ was used to compare the experimentally observed and numerically simulated thermal distribution of the Pt/AAO catalyst. The effect of the initial H2 volume fraction on the combustion temperature and conversion of H2 was investigated. The activation energy for CHC on the Pt/AAO catalyst was 19.2 kJ/mol. Prolonged CHC was performed to assess the durability (reactive metal stability and catalytic activity) of the Pt/AAO catalyst. A stable combustion temperature of 162.8 ± 8.0 °C was maintained over 530 h of CHC. To confirm that Pt aggregation was avoided, the Pt particle size and distribution were determined by TEM before and after prolonged CHC.

Spatial Effect of Crime on Peer-to-Peer Lodging Performance

2021 ◽  
pp. 004728752110082
Author(s):  
Yu-Hua Xu ◽  
Lori Pennington-Gray ◽  
Jinwon Kim
Keyword(s):  
Peer To Peer ◽  
Spatial Effect ◽  
Econometric Models ◽  
Spatial Econometric ◽  
Community Based ◽  
Negatively Associated ◽  
Business Operations ◽  
Spatial Econometric Models ◽  
Crime Types ◽  
Social Uncertainty

Safety is a major factor impacting consumers’ participation in peer-to-peer (P2P) economies. Using spatial econometric models, this study examined crime effects on the performance (RevPAR) of P2P lodgings at three spatial ranges: property, community, and destination level. The performance of P2P lodgings is negatively associated with crime densities, while the degree of the association varies by crime types and room types. Crime can “spill over” to the neighborhood and have the strongest impact at the community level, followed by the destination level and the property level. The study provides a way to understand tourism risks using criminology theories and the concept of social uncertainty. Empirically, the study provides implications to the governance of community-based lodging business. We suggest that the effect of crime on P2P lodging performance was more conditioned by the safety environment in its neighborhood and the whole destination, rather than individual business operations.

scholarly journals Copper Phyllosilicates-Derived Catalysts in the Production of Alcohols from Hydrogenation of Carboxylates, Carboxylic Acids, Carbonates, Formyls, and CO2: A Review

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 255
Author(s):  
Dien-Thien To ◽  
Yu-Chuan Lin
Keyword(s):  
Carboxylic Acids ◽  
Catalytic Performance ◽  
Spatial Effect ◽  
Synthesis Methods ◽  
The Past ◽  
Surface Areas ◽  
Preparation Conditions ◽  
Remedial Actions ◽  
The Stability ◽  
Size Interaction

Copper phyllosilicates-derived catalysts (CuPS-cats) have been intensively explored in the past two decades due to their promising activity in carbonyls hydrogenation. However, CuPS-cats have not been completely reviewed. This paper focuses on the aspects concerning CuPS-cats from synthesis methods, effects of preparation conditions, and dopant to catalytic applications of CuPS-cats. The applications of CuPS-cats include the hydrogenation of carboxylates, carboxylic acids, carbonates, formyls, and CO2 to their respective alcohols. Besides, important factors such as the Cu dispersion, Cu+ and Cu0 surface areas, particles size, interaction between Cu and supports and dopants, morphologies, and spatial effect on catalytic performance of CuPS-cats are discussed. The deactivation and remedial actions to improve the stability of CuPS-cats are summarized. It ends up with the challenges and prospective by using this type of catalyst.

scholarly journals Visualizing thermal distribution through hydrogel confined ionic system

iScience ◽  
2021 ◽  
Vol 24 (2) ◽  
pp. 102085
Author(s):  
Qinyuan Gui ◽  
Bin Fu ◽  
Yonglin He ◽  
Shanzhi Lyu ◽  
Yingchao Ma ◽  
...  
Keyword(s):  
Ionic System ◽  
Thermal Distribution

Construction of Spatial Effect from Atomically Dispersed Co Anchoring on Subnanometer Ru Cluster for Enhanced N2-to-NH3 Conversion

ACS Catalysis ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 4430-4440
Author(s):  
Yangyu Zhang ◽  
Jiejie Li ◽  
Jihui Cai ◽  
Linlin Yang ◽  
Tianhua Zhang ◽  
...  
Keyword(s):  
Spatial Effect

scholarly journals MHD squeezed Darcy–Forchheimer nanofluid flow between two h–distance apart horizontal plates

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 1100-1107
Author(s):  
Ghulam Rasool ◽  
Waqar A. Khan ◽  
Sardar Muhammad Bilal ◽  
Ilyas Khan
Keyword(s):  
Heat Flux ◽  
Fluid Flow ◽  
Velocity Field ◽  
Concentration Distribution ◽  
Numerical Data ◽  
Brownian Diffusion ◽  
Nanofluid Flow ◽  
Viscosity Parameter ◽  
Thermal Distribution ◽  
Factor Data

Abstract This research is mainly concerned with the characteristics of magnetohydrodynamics and Darcy–Forchheimer medium in nanofluid flow between two horizontal plates. A uniformly induced magnetic impact is involved at the direction normal to the lower plate. Darcy–Forchheimer medium is considered between the plates that allow the flow along horizontal axis with additional effects of porosity and friction. The features of Brownian diffusive motion and thermophoresis are disclosed. Governing problems are transformed into nonlinear ordinary problems using appropriate transformations. Numerical Runge–Kutta procedure is applied using MATLAB to solve the problems and acquire the data for velocity field, thermal distribution, and concentration distribution. Results have been plotted graphically. The outcomes indicate that higher viscosity results in decline in fluid flow. Thermal profile receives a decline for larger viscosity parameter; however, Brownian diffusion and thermophoresis appeared as enhancing factors for the said profile. Numerical data indicate that heat flux reduces for viscosity parameter. However, enhancement is observed in skin-friction for elevated values of porosity factor. Data of this paper are practically helpful in industrial and engineering applications of nanofluids.

scholarly journals Variable Selection for the Spatial Autoregressive Model with Autoregressive Disturbances

Mathematics ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1448
Author(s):  
Xuan Liu ◽  
Jianbao Chen
Keyword(s):  
Variable Selection ◽  
Autoregressive Model ◽  
Rapid Development ◽  
Heterogeneous Data ◽  
Spatial Effect ◽  
Spatial Effects ◽  
Spatial Autoregressive Model ◽  
Monte Carlo Studies ◽  
Spatial Autoregressive ◽  
Theoretical Results

Along with the rapid development of the geographic information system, high-dimensional spatial heterogeneous data has emerged bringing theoretical and computational challenges to statistical modeling and analysis. As a result, effective dimensionality reduction and spatial effect recognition has become very important. This paper focuses on variable selection in the spatial autoregressive model with autoregressive disturbances (SARAR) which contains a more comprehensive spatial effect. The variable selection procedure is presented by using the so-called penalized quasi-likelihood approach. Under suitable regular conditions, we obtain the rate of convergence and the asymptotic normality of the estimators. The theoretical results ensure that the proposed method can effectively identify spatial effects of dependent variables, find spatial heterogeneity in error terms, reduce the dimension, and estimate unknown parameters simultaneously. Based on step-by-step transformation, a feasible iterative algorithm is developed to realize spatial effect identification, variable selection, and parameter estimation. In the setting of finite samples, Monte Carlo studies and real data analysis demonstrate that the proposed penalized method performs well and is consistent with the theoretical results.

Field Monitoring of Surrounding Rock Stress in Tunnel Construction

2012 ◽  
Vol 170-173 ◽  
pp. 1735-1739
Author(s):  
Ying Na Dong ◽  
Qiang Huang
Keyword(s):  
Spatial Effect ◽  
Field Monitoring ◽  
Surrounding Rock ◽  
Tunnel Construction ◽  
Rock Stress ◽  
Vibrating Wire ◽  
Stress Variation ◽  
Stress Changes ◽  
Tunnel Diameter ◽  
Surrounding Rock Stress

The surrounding rock stress field monitor has been done in excavation by vibrating wire transducer. The field monitoring data are compared with numerical simulation results. The result shows: Vibrating wire transducer can record the stress variation of surrounding rock and support. Surrounding rock stress changes violently at every excavation step, such as lower bench excavation, the stress variation is mainly controlled by the spatial effect. When the distance from excavation face to the monitoring section is more than a tunnel diameter, the rock stress variation is mainly affected by time and it is relatively smooth and continuous.

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