scholarly journals Bolide Energetics and Infrasound Propagation: Exploring the 18 December 2018 Bering Sea Event to Identify Limitations of Empirical and Numerical Models

2021 ◽  
Vol 1 (3) ◽  
pp. 164-171
Author(s):  
Stephen Arrowsmith ◽  
Petru Negraru ◽  
Greg Johnson
Keyword(s):  
Long Range ◽  
State Of The Art ◽  
Numerical Models ◽  
The United States ◽  
Propagation Models ◽  
International Monitoring ◽  
Source Scaling ◽  
Signal Period ◽  
Nuclear Tests ◽  
Equivalent Yield

Abstract Infrasound observations are an important tool in assessing the energetics of bolides and can help quantify the flux of meteoroids through Earth’s atmosphere. Bolides are also important atmospheric sources for assessing long-range infrasound propagation models and can be used as benchmark events for validating the International Monitoring System (IMS) infrasound network, which is designed to detect nuclear tests in the atmosphere. This article exploits unique infrasound observations from a large bolide recorded on IMS infrasound arrays and high-density infrasound deployments in the United States to assess limitations in infrasound source scaling relationships. The observations provide an unprecedented sampling of infrasound propagation along a transect at an azimuth of 60° from the source to a distance of ∼8000 km. Widely used empirical laws for assessing bolide energetics and state-of-the-art numerical models for simulating infrasound propagation are assessed to quantify important discrepancies with the observations. In particular, empirical laws for equivalent yield, which are based on signal period and are assumed to be relatively unaffected by propagation effects, can be heavily contaminated by site noise. In addition, by modeling infrasound propagation over a range of ∼8000 km, we show that state-of-the-art models do not reproduce the observed amplitude decay over this long range (which decays by a rate of at least 2 higher than can be modeled).

FOREWORD

Geophysics ◽  
1964 ◽  
Vol 29 (2) ◽  
pp. 151-153 ◽  
Author(s):  
Charles C. Bates
Keyword(s):  
Prime Minister ◽  
State Of The Art ◽  
The United States ◽  
The Political ◽  
Bad Faith ◽  
Political Leaders ◽  
The Past ◽  
Current State ◽  
Nuclear Tests ◽  
Test Ban

A decade ago, it would have been the rare geophysicist indeed who would have predicted that his specialty was destined to become a major topic of discussion between such world political leaders as Presidents Eisenhower and Kennedy, Prime Minister Macmillan of Great Britain, and Chairman Khrushchev of the USSR. Yet this has come to pass during the past six years, for in 1958 there started the continuing round of international negotiations directed towards the creation of an effective underground test-ban treaty. During the conduct of these negotiations, it has been repeatedly necessary to assess the current state-of-the-art in seismology and its sister geophysical sciences, for the only detectable signals known to propagate for several hundreds to thousands of miles from underground nuclear tests are seismic in nature. With the United States policy being only to seek an underground-test-ban agreement incorporating strong safeguards against acts of bad faith, it is important that the political safe-guards be backed up by those of a geophysical nature.

Strategies to improve implementation of adaptive management practices for restoration in coastal Louisiana

Shore & Beach ◽  
2020 ◽  
pp. 83-91
Author(s):  
Tim Carruthers ◽  
Richard Raynie ◽  
Alyssa Dausman ◽  
Syed Khalil
Keyword(s):  
Adaptive Management ◽  
Management Practices ◽  
Numerical Models ◽  
The United States ◽  
State Agency ◽  
Coastal Protection ◽  
Coastal Restoration ◽  
Management Actions ◽  
Coastal Louisiana ◽  
Restoration Effort

Natural resources of coastal Louisiana support the economies of Louisiana and the whole of the United States. However, future conditions of coastal Louisiana are highly uncertain due to the dynamic processes of the Mississippi River delta, unpredictable storm events, subsidence, sea level rise, increasing temperatures, and extensive historic management actions that have altered natural coastal processes. To address these concerns, a centralized state agency was formed to coordinate coastal protection and restoration effort, the Coastal Protection and Restoration Authority (CPRA). This promoted knowledge centralization and supported informal adaptive management for restoration efforts, at that time mostly funded through the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA). Since the Deepwater Horizon (DWH) oil spill in 2010 and the subsequent settlement, the majority of restoration funding for the next 15 years will come through one of the DWH mechanisms; Natural Resource and Damage Assessment (NRDA), the RESTORE Council, or National Fish and Wildlife Foundation –Gulf Environmental Benefit Fund (NFWF-GEBF). This has greatly increased restoration effort and increased governance complexity associated with project funding, implementation, and reporting. As a result, there is enhanced impetus to formalize and unify adaptive management processes for coastal restoration in Louisiana. Through synthesis of input from local coastal managers, historical and current processes for project and programmatic implementation and adaptive management were summarized. Key gaps and needs to specifically increase implementation of adaptive management within the Louisiana coastal restoration community were identified and developed into eight tangible and specific recommendations. These were to streamline governance through increased coordination amongst implementing entities, develop a discoverable and practical lessons learned and decision database, coordinate ecosystem reporting, identify commonality of restoration goals, develop a common cross-agency adaptive management handbook for all personnel, improve communication (both in-reach and outreach), have a common repository and clearing house for numerical models used for restoration planning and assessment, and expand approaches for two-way stakeholder engagement throughout the restoration process. A common vision and maximizing synergies between entities can improve adaptive management implementation to maximize ecosystem and community benefits of restoration effort in coastal Louisiana. This work adds to current knowledge by providing specific strategies and recommendations, based upon extensive engagement with restoration practitioners from multiple state and federal agencies. Addressing these practitioner-identified gaps and needs will improve engagement in adaptive management in coastal Louisiana, a large geographic area with high restoration implementation within a complex governance framework.

scholarly journals The WxChallenge: Forecasting Competition, Educational Tool, and Agent of Cultural Change

2013 ◽  
Vol 94 (10) ◽  
pp. 1501-1506 ◽  
Author(s):  
Bradley G. Illston ◽  
Jeffrey B. Basara ◽  
Christopher Weiss ◽  
Mike Voss
Keyword(s):  
Cultural Change ◽  
State Of The Art ◽  
Learning Experience ◽  
The United States ◽  
Higher Learning ◽  
Educational Tool ◽  
Web Interfaces ◽  
Wind Speeds ◽  
University Of Oklahoma ◽  
The University

The WxChallenge, a project developed at the University of Oklahoma, brings a state-of-the-art, fun, and exciting forecast contest to participants at colleges and universities across North America. The challenge is to forecast the maximum and minimum temperatures, precipitation, and maximum wind speeds for select locations across the United States over a 24-h prediction period. The WxChallenge is open to all undergraduate and graduate students, as well as higher-education faculty, staff, and alumni. Through the use of World Wide Web interfaces accessible by personal computers, tablet computer, and smartphones, the WxChallenge provides a state-of-the-art portal to aid participants in submitting forecasts and alleviate many of the administrative issues (e.g., tracking and scoring) faced by local managers and professors. Since its inception in 2006, 110 universities have participated in the contest and it has been utilized as part of the curricula for 140 classroom courses at various institutions. The inherently challenging nature of the WxChallenge has encouraged its adoption as an educational tool. As its popularity has grown, professors have seen the utility of the Wx-Challenge as a teaching aid and it has become an instructional resource of many meteorological classes at institutions for higher learning. In addition to evidence of educational impacts, the competition has already begun to leave a cultural and social mark on the meteorological learning experience.

scholarly journals Revealing the spatial shifting pattern of COVID-19 pandemic in the United States

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Di Zhu ◽  
Xinyue Ye ◽  
Steven Manson
Keyword(s):  
United States ◽  
Long Range ◽  
Network Optimization ◽  
Network Modeling ◽  
The United States ◽  
Standard Series ◽  
Time And Space ◽  
Long Range Interactions ◽  
Dynamic Relationships ◽  
Over Time

AbstractWe describe the use of network modeling to capture the shifting spatiotemporal nature of the COVID-19 pandemic. The most common approach to tracking COVID-19 cases over time and space is to examine a series of maps that provide snapshots of the pandemic. A series of snapshots can convey the spatial nature of cases but often rely on subjective interpretation to assess how the pandemic is shifting in severity through time and space. We present a novel application of network optimization to a standard series of snapshots to better reveal how the spatial centres of the pandemic shifted spatially over time in the mainland United States under a mix of interventions. We find a global spatial shifting pattern with stable pandemic centres and both local and long-range interactions. Metrics derived from the daily nature of spatial shifts are introduced to help evaluate the pandemic situation at regional scales. We also highlight the value of reviewing pandemics through local spatial shifts to uncover dynamic relationships among and within regions, such as spillover and concentration among states. This new way of examining the COVID-19 pandemic in terms of network-based spatial shifts offers new story lines in understanding how the pandemic spread in geography.

1—by Captain A. Wepster

1963 ◽  
Vol 16 (4) ◽  
pp. 389-398
Keyword(s):  
United States ◽  
Travel Time ◽  
Long Range ◽  
The United States ◽  
Point Of View ◽  
Ship Routing ◽  
Waves And Currents ◽  
Meteorological Institute

In 1960 Hanssen and James described to the Institute a system developed and used by the United States Hydrographic Office for selecting the optimum track for transoceanic crossings by applying long-range predictions of winds, waves and currents to a knowledge of how the routed vessel reacts to these variables. The paper (Journal, 13, 253) described how, over a period of two years, an average reduction in travel time of 14 hours was achieved over 1000 optimum routes.In the present papers, presented at an Institute meeting held in London on 19 April, Captain Wepster of the Holland-America Line first of all goes into the benefits which effective ship routing offers the ship operator and then describes the results of the experimental routing programme undertaken by his Company in association with the Royal Netherlands Meteorological Institute. Mr. Verploegh of that Institute then discusses the programme from the forecaster's point of view.

Optimum Ship Routing

1960 ◽  
Vol 13 (3) ◽  
pp. 253-272 ◽  
Author(s):  
George L. Hanssen ◽  
Richard W. James
Keyword(s):  
United States ◽  
Travel Time ◽  
Long Range ◽  
Wind Waves ◽  
The United States ◽  
Ship Routing ◽  
Waves And Currents

The paper describes the system developed and used by the United States Hydrographic Office for selecting the optimum track for transoceanic crossings by applying long-range predictions of wind, waves and currents to a knowledge of how the routed vessel reacts to these variables. Over a period of two years, over 1000 optimum ship routes were provided to one authority, with an average reduction in travel time of 14 hours.

scholarly journals VERIFICATION OF NUMERICAL WAVE PROPAGATION MODELS IN TIDAL INLETS

1988 ◽  
Vol 1 (21) ◽  
pp. 30 ◽  
Author(s):  
J.A. Vogel ◽  
A.C. Radder ◽  
J.H. De Reus
Keyword(s):  
Wave Propagation ◽  
Numerical Models ◽  
River Estuary ◽  
Regular Grid ◽  
Local Wind ◽  
Tidal Inlets ◽  
Propagation Models ◽  
Dutch Coast ◽  
Model Based ◽  
Numerical Wave

The performance of two numerical wave propagation models has been investigated by comparison with field data. The first model is a refractiondiffraction model based on the parabolic equation method. The second is a refraction model based on the wave action equation, using a regular grid. Two field situations, viz. a tidal inlet and a river estuary along the Dutch coast, were used to determine the influence of the local wind on waves behind an island and a breaker zone. It may be concluded from the results of the computations and measurements that a much better agreement is obtained when wave growth due to wind is properly accounted for in the numerical models. In complicated coastal areas the models perform well for both engineering and research purposes.

scholarly journals A Review of Hydraulic Fracturing Simulation

2021 ◽  
Author(s):  
Bin Chen ◽  
Beatriz Ramos Barboza ◽  
Yanan Sun ◽  
Jie Bai ◽  
Hywel R Thomas ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
State Of The Art ◽  
Numerical Models ◽  
Gas Production ◽  
Physical Processes ◽  
Horizontal Drilling ◽  
Improve Treatment ◽  
Multi Stage ◽  
Pros And Cons ◽  
Treatment Designs

AbstractAlong with horizontal drilling techniques, multi-stage hydraulic fracturing has improved shale gas production significantly in past decades. In order to understand the mechanism of hydraulic fracturing and improve treatment designs, it is critical to conduct modelling to predict stimulated fractures. In this paper, related physical processes in hydraulic fracturing are firstly discussed and their effects on hydraulic fracturing processes are analysed. Then historical and state of the art numerical models for hydraulic fracturing are reviewed, to highlight the pros and cons of different numerical methods. Next, commercially available software for hydraulic fracturing design are discussed and key features are summarised. Finally, we draw conclusions from the previous discussions in relation to physics, method and applications and provide recommendations for further research.

An Empirical Review of the Design and Performance of Icebreakers

1989 ◽  
Vol 26 (02) ◽  
pp. 145-159
Author(s):  
R. A. Dick ◽  
J. E. Laframboise
Keyword(s):  
United States ◽  
Soviet Union ◽  
State Of The Art ◽  
The United States ◽  
West Germany ◽  
The United Kingdom ◽  
The Soviet Union ◽  
And Performance ◽  
Ship Performance ◽  
Selection Of

This paper utilizes available data on existing icebreaking ships to compile a review of the design features that influence ship performance. The data were extracted from a recently completed review of the state of the art of Arctic ship technology and include icebreaking ships from Argentina, Canada, Denmark, Finland, Japan, Sweden, the United Kingdom, the Soviet Union, the United States, and West Germany. It is the aim of this paper to offer guidance in the initial stages of icebreaker design and thereby give confidence to the designer in the selection of dimensions, hull shape and propulsion.

DAY CARE: 3. SERVING PRESCHOOL CHILDREN. By Donald J. Cohen, M.D., and Ada S. Brandagee. U.S. Department of Health, Education and Welfare, Publication No. (OHD) 74-1057, U.S. Government Printing Office, Washington, D.C. 20402

PEDIATRICS ◽  
1977 ◽  
Vol 59 (3) ◽  
pp. 487-488
Author(s):  
Paul C. Young
Keyword(s):  
Child Development ◽  
Day Care ◽  
State Of The Art ◽  
The United States ◽  
Government Printing ◽  
Introductory Statement ◽  
Department Of Health ◽  
Care Field ◽  
Broad Overview

This book is one of a series of handbooks being published by the Office of Child Development to "promote discussion and to improve the quality of day care in the United States," according to an introductory statement by Saul Rosoff, Acting Director, Office of Child Development. It was written by Donald J. Cohen, M.D., psychiatrist and pediatrician at Yale, in collaboration with Ada S. Brandagee, M.A. Dr. Cohen attempts "to provide a broad overview of the day care field, a basic state-of-the-art guidebook for those seriously concerned about preschool day care.

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