scholarly journals High-frequency fluctuations of indoor pressure: A potential driving force for vapor intrusion in urban areas

2020 ◽  
Vol 710 ◽  
pp. 136309
Author(s):  
Yijun Yao ◽  
Yuting Xiao ◽  
Jian Luo ◽  
Genfu Wang ◽  
Jonathan Ström ◽  
...  
Keyword(s):  
High Frequency ◽  
Urban Areas ◽  
Driving Force ◽  
Vapor Intrusion ◽  
Frequency Fluctuations

What Kind of People Use Carsharing for Commuting? Case Study in Shanghai

2019 ◽  
Vol 2673 (5) ◽  
pp. 770-778 ◽  
Author(s):  
Jianhong Ye ◽  
Daoge Wang ◽  
Hua Zhang ◽  
Hong Yang
Keyword(s):  
High Frequency ◽  
Urban Areas ◽  
Descriptive Analysis ◽  
User Characteristics ◽  
Logistic Regression Models ◽  
Highly Educated ◽  
Suburban Areas ◽  
Commuting Mode ◽  
Study Offer

Carsharing as a service has been growing rapidly worldwide. Its expansion has drawn wide attention in the research community with regard to the underlying driving factors and user characteristics. Despite these extensive investigations, there are still limited studies focusing on the examination of users using carsharing as a commuting mode. The answers to questions such as what kind of people would like to use carsharing for commuting and why they frequently use carsharing to commute are not clear. To enrich our understanding of these problems, this paper aims to investigate carsharing commuters in a mega city. Specifically, it intends to integrate the actual user order data with survey data from 1,920 participants to uncover the characteristics of carsharing commuters. Data from the Evcard carsharing systems in Shanghai were explicitly analyzed. Through descriptive analysis and logistic regression models, the characteristics and critical factors that affect the choice of carsharing as a commuting mode were captured. The results show that: 1. carsharing commuters mostly live or work in suburban areas in which public transport accessibility is limited; 2. carsharing commuters are more likely to be highly educated, in a higher income bracket, and older than other carsharing members; 3. high-frequency carsharing commuters own a reduced number of private cars; and 4. those high-frequency carsharing commuters with higher income are less sensitive to the carsharing costs caused by congestion. The findings in the study offer some insights into carsharing commuters and provide some supportive information for considering policies in developing carsharing systems in urban areas.

scholarly journals Norovirus recombination

2007 ◽  
Vol 88 (12) ◽  
pp. 3347-3359 ◽  
Author(s):  
Rowena A. Bull ◽  
Mark M. Tanaka ◽  
Peter A. White
Keyword(s):  
High Frequency ◽  
Driving Force ◽  
Recombination Event ◽  
Viral Evolution ◽  
Rna Recombination ◽  
Recombination Point ◽  
The Family ◽  
Double Recombination ◽  
Double Recombination Event ◽  
Recombination Breakpoints

RNA recombination is a significant driving force in viral evolution. Increased awareness of recombination within the genus Norovirus of the family Calicivirus has led to a rise in the identification of norovirus (NoV) recombinants and they are now reported at high frequency. Currently, there is no classification system for recombinant NoVs and a widely accepted recombinant genotyping system is still needed. Consequently, there is duplication in reporting of novel recombinants. This has led to difficulties in defining the number and types of recombinants in circulation. In this study, 120 NoV nucleotide sequences were compiled from the current GenBank database and published literature. NoV recombinants and their recombination breakpoints were identified using three methods: phylogenetic analysis, SimPlot analysis and the maximum χ 2 method. A total of 20 NoV recombinant types were identified in circulation worldwide. The recombination point is the ORF1/2 overlap in all isolates except one, which demonstrated a double recombination event within the polymerase region.

High-frequency fluctuations in the IGS'92 polar series

1995 ◽  
Vol 19 (3) ◽  
pp. 391-398
Author(s):  
Cheng-li Huang ◽  
Wen-jing Jin ◽  
De-chun Liao ◽  
Wen-yao Zhu ◽  
Jie-xian Wang
Keyword(s):  
High Frequency ◽  
Frequency Fluctuations

Exploring High Frequency Temporal Fluctuations in the Terminal Aneurysm of the Basilar Bifurcation

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Matthew D. Ford ◽  
Ugo Piomelli
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
High Frequency ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Disturbed Flow ◽  
Frequency Fluctuations ◽  
Wall Shear ◽  
Inflow Jet

Cerebral aneurysms are a common cause of death and disability. Of all the cardiovascular diseases, aneurysms are perhaps the most strongly linked with the local fluid mechanic environment. Aside from early in vivo clinical work that hinted at the possibility of high-frequency intra-aneurysmal velocity oscillations, flow in cerebral aneurysms is most often assumed to be laminar. This work investigates, through the use of numerical simulations, the potential for disturbed flow to exist in the terminal aneurysm of the basilar bifurcation. The nature of the disturbed flow is explored using a series of four idealized basilar tip models, and the results supported by four patient specific terminal basilar tip aneurysms. All four idealized models demonstrated instability in the inflow jet through high frequency fluctuations in the velocity and the pressure at approximately 120 Hz. The instability arises through a breakdown of the inflow jet, which begins to oscillate upon entering the aneurysm. The wall shear stress undergoes similar high-frequency oscillations in both magnitude and direction. The neck and dome regions of the aneurysm present 180 deg changes in the direction of the wall shear stress, due to the formation of small recirculation zones near the shear layer of the jet (at the frequency of the inflow jet oscillation) and the oscillation of the impingement zone on the dome of the aneurysm, respectively. Similar results were observed in the patient-specific models, which showed high frequency fluctuations at approximately 112 Hz in two of the four models and oscillations in the magnitude and direction of the wall shear stress. These results demonstrate that there is potential for disturbed laminar unsteady flow in the terminal aneurysm of the basilar bifurcation. The instabilities appear similar to the first instability mode of a free round jet.

Near-surface Structure of Downtown Jinan, China: Application of Ambient Noise Tomography with a Dense Seismic Array

2019 ◽  
Vol 24 (4) ◽  
pp. 641-652
Author(s):  
Feng Liang ◽  
Zhihui Wang ◽  
Hailong Li ◽  
Kai Liu ◽  
Tao Wang
Keyword(s):  
Surface Wave ◽  
Human Activities ◽  
High Frequency ◽  
Urban Areas ◽  
Ambient Noise ◽  
Velocity Structure ◽  
Shear Velocity ◽  
Ambient Noise Tomography ◽  
Surface Wave Dispersion ◽  
Near Surface

Urban geophysics ups the ante in the world of applied geophysics, which requires innovative thinking and seemingly off-the-wall approaches, if for no other reason than the settings. Ambient-noise-tomography (ANT) can play a pivotal role in yielding subsurfa2ce information in urban areas, which is capable of dealing with challenges related to these scenarios ( e.g., human activities and low signal-to-noise ratio). In this study, the ANT was conducted to investigate the near-surface shear-velocity structure in the surrounding area of the Baotu Spring Park in downtown Jinan, Shandong Province, China. Quiet clear Rayleigh waves have been obtained by the cross-correlation, which indicates that strong human activities, such as moving vehicles and municipal engineering constructions, can produce approximately isotropic distribution of noise sources for high-frequency signals. The direct surface-wave tomographic method with period-dependent ray-tracing was used to invert all surface-wave dispersion data in the period band 0.2-1.5 s simultaneously for 3D variations of shear-velocity (Vs) structure. Our results show a good correspondence to the geological features with thinner Quaternary sediments, the geological structural characteristic of the limestone surrounded by the igneous which has the highest velocity than that of the limestone in the study area, and several concealed faults of which specific location has been detected at depth. The results demonstrate that it is possible to successfully use ANT with high-frequency signal in an urban environment provided a detailed planning and execution is implemented.

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