Rampart craters on Earth

2021 ◽  
Author(s):  
Gerwin Wulf ◽  
Thomas Kenkmann
Keyword(s):  
United States ◽  
Double Layer ◽  
Impact Crater ◽  
Single Layer ◽  
The United States ◽  
Impact Craters ◽  
Planetary Surfaces ◽  
Lonar Crater

ABSTRACT Rampart craters are omnipresent features on volatile-rich solid planetary surfaces. This raises the question whether, and how many, rampart craters are present on Earth. We reviewed the terrestrial impact crater record with regard to possible rampart morphologies and present detailed morphological analyses of these terrestrial craters here. Our results show that the Ries crater in Germany, Bosumtwi crater in Ghana, Tenoumer crater in Mauritania, Lonar crater in India, and Meteor crater in the United States are terrestrial rampart craters. The Ries and Bosumtwi craters can be classified as double-layer ejecta (DLE) craters, whereas Tenoumer, Lonar, and Meteor craters can be classified as single-layer ejecta (SLE) craters. Tenoumer and Meteor craters show rampart as well as common lunar-like ejecta characteristics within their ejecta blankets and, thus, appear to be hybrid craters. In addition, we discuss seven crater structures that show at least some morphological or lithological peculiarities that could provide evidence for possible ejecta ramparts. Considering the low number of terrestrial impact craters with well-preserved ejecta blankets, the relatively high proportion of rampart craters is astonishing. Obviously, the formation of layered or rampart craters is a common and not a rare process on Earth.

Laboratory and Field Evaluation of Single Layer and Double Layer High Friction Surface Treatments

2019 ◽  
Vol 2673 (2) ◽  
pp. 552-561 ◽  
Author(s):  
Shuo Li ◽  
Peiliang Cong ◽  
Demei Yu ◽  
Rui Xiong ◽  
Yi Jiang
Keyword(s):  
Double Layer ◽  
Friction Surface ◽  
Single Layer ◽  
Aggregate Size ◽  
Surface Friction ◽  
Field Evaluation ◽  
The United States ◽  
Aggregate Gradation ◽  
State Highway ◽  
Friction Performance

High friction surface treatment (HFST) has been proactively used as a solution to extreme friction demands at locations such as horizontal curves, ramps, bridge decks, and intersections. Considerable efforts have been made to evaluate the use of HFST across the United States (U.S.) The American Association of State Highway and Transportation Officials (AASHTO) has issued a provisional specification, i.e., AASHTO PP 79-14, to help state Departments of Transportation (DOTs) to successfully apply HFST. This paper presents a further effort made by the authors to evaluate and compare the friction performance and durability of single and double layer HFTS systems with calcined bauxite aggregate. The laboratory accelerated polishing was conducted to evaluate the effects of aggregate candidate gradations on the friction performance, such as friction coefficient and macrotexture mean profile depth (MPD), and to determine the aggregate gradation for field evaluation. Field evaluation was conducted on both single and double layer HFST systems using test strips under actual traffic polishing over a time period of nine months that covered an entire snow season. It was found that larger aggregate size tends to yield larger MPD, but larger MPD does not necessarily imply larger friction. The double layer HFST did not outperform the single layer HFST with respect to friction and durability. If the properties of calcined bauxite aggregate are precisely defined, either surface friction or MPD can solely be utilized as the frictional metric for quality assurance (QA) of HFST.

scholarly journals Cooperation or Confrontation? —— Prediction of COVID-19 Pandemic Situation via Deep Learning

2020 ◽  
Author(s):  
Zhonghua Hong ◽  
Ziyang Fan ◽  
Xiaohua Tong ◽  
Ruyan Zhou ◽  
Yun Zhang ◽  
...  
Keyword(s):  
United States ◽  
Short Term Memory ◽  
Single Layer ◽  
Development Trend ◽  
The United States ◽  
Presidential Transition ◽  
Effective Prevention ◽  
Performance Effects ◽  
Epidemic Development ◽  
Self Protection

Abstract The COVID-19 pandemic is the most serious catastrophe since the Second World War. To more accurately observe the epidemic under the influence of policies and provide policy adjustments before the official presidential transition in the United States, we use a three-layer superimposed Long-Short-Term-Memory (LSTM) model to predict the epidemic development trend to mid-January, 2021. The proposed model provides more accuracy and stability relative to Susceptible-Exposed-Infective-Recovered (SEIR), modified stacked au-to-encoder, and single-layer LSTM models. The performance effects of the measures in China and five countries with severe epidemics are analysed and summarised. The model shows that the error rate of China, five countries and the world is less than 1.4%. According to forecasts, the epidemic situations in the United States, India, and Brazil, caused by untimely, inappropriate policies, lax regulations and insufficient public cooperation, remain very severe, with cases continuing to increase by tens of thousands. The number of cumulative confirmed cases worldwide will exceed 84.58 million by mid-January, 2021; however, the mortality rate will gradually decrease. Based on analysis of measures (including China’s effective prevention and control policies), we found that there are performed tremendous different efficiency even using same positive policy for different countries because of various cooperation between people and governments. It is essential to maintain self-protection to prevent the epidemic from deterioration or regenerating, especially, wearing mask and maintaining a safe distance.

Vibration Control Design for Light Rail Transit: A Single Project With the Full Rainbow of Vibration Control Features: Case Study

2015 ◽  
Author(s):  
Rob Greene
Keyword(s):  
United States ◽  
Vibration Control ◽  
Single Layer ◽  
The United States ◽  
Light Rail ◽  
Rail Transit ◽  
Control Approach ◽  
Slab Track ◽  
Rail System ◽  
Under Construction

Because of the recent emphasis on rail transit infrastructure expansion and rebuilding in the United States, there is concern about the potential adverse vibration effects on existing activities that are sensitive to vibration and ground-borne-noise located in proximity to new or reactivated rail system rights-of-way. A Southern California at-grade/elevated LRT system that is currently under construction required the design and specification of extensive vibration control features. The final design needed to include the entire range of vibration mitigation tools presented in the Federal Transit Administration guidance manual. Designs and Contract Specifications included simple single-layer ballast mats; multi-layer ballast mats; high-resilience direct fixation fasteners; potential wheel-squeal solutions; low-vibration special trackwork; continuously-supported, street-running, floating slab track; and discrete, steel-helical-spring-supported floating slab track. It is noteworthy that the discrete steel-spring-supported FST is the first use of this vibration control approach in an at-grade rail system in the United States. This paper will discuss the overall approach, data analysis, solutions development, and the final designs prepared for this project and how this information may be beneficial to other projects with similar issues.

scholarly journals Temperature and Light Characterization during Winter Production Season in High Tunnels in the Southwestern United States

2020 ◽  
Vol 30 (2) ◽  
pp. 259-267
Author(s):  
Mark E. Uchanski ◽  
Dawn M. VanLeeuwen ◽  
Steven J. Guldan ◽  
Constance L. Falk ◽  
Manoj Shukla ◽  
...  
Keyword(s):  
United States ◽  
Soil Temperature ◽  
Double Layer ◽  
Single Layer ◽  
Soil Surface ◽  
Southwestern United States ◽  
Winter Solstice ◽  
High Tunnel ◽  
High Tunnels ◽  
Tunnel Design

Replicated temperature data from passively heated high tunnels are lacking, especially in the southwestern United States. Field studies were conducted over three seasons in two locations in New Mexico—a southern site in Las Cruces and a northern site in Alcalde—to characterize the crop environment in three high-tunnel designs during the winter growing season (October–March). High tunnels were 16 × 32 ft and oriented with the long edge running east to west. Heavyweight woven plastic covered the single-layer (SL) high-tunnel design. Double-layer designs (DL) were covered with a lightweight woven plastic on the bottom, followed by a second layer of the heavyweight plastic inflated with a fan. A heat sink was created using 16 55-gal barrels painted black, filled with water, and aligned along the north side of the double layer for the DL+B design. Soil temperature (3 inches deep) and air temperature (1 ft above the soil surface) were recorded inside the high tunnel, inside the high tunnel under a floating rowcover, and outside the high tunnel. In addition, photosynthetically active radiation (PAR) was recorded inside and outside the high tunnels during or near the winter solstice each year of the study. Daily air and soil temperature minimums were highest in the DL+B design and lowest in the SL design. Maximum air and soil temperatures did not significantly differ between high-tunnel designs, although the DL+B design measurements were consistently lower. During season 1, the SL design had significantly higher PAR transmission than the other two designs. In the northern location, the difference became insignificant during seasons 2 and 3, likely due to dust accumulation and plastic aging. In the southern location, the SL design maintained higher PAR transmission throughout the study, possibly due to plastic cleaning. Data collected in this study can help inform the decisions of high-tunnel growers and researchers in the region.

Correlative microscopy in distrubuted (client/server) computing environments: tools for catalyzing the rapid dissemination of information about the cell biology of the human prostate

1995 ◽  
Vol 53 ◽  
pp. 682-683
Author(s):  
A. Hakam ◽  
J.T. Gau ◽  
M.L. Grove ◽  
B.A. Evans ◽  
M. Shuman ◽  
...  
Keyword(s):  
United States ◽  
Cell Biology ◽  
Tissue Bank ◽  
The United States ◽  
Prostate Adenocarcinoma ◽  
Correlative Microscopy ◽  
Client Server ◽  
Critical Elements ◽  
Transplant Organ

Prostate adenocarcinoma is the most common malignant tumor of men in the United States and is the third leading cause of death in men. Despite attempts at early detection, there will be 244,000 new cases and 44,000 deaths from the disease in the United States in 1995. Therapeutic progress against this disease is hindered by an incomplete understanding of prostate epithelial cell biology, the availability of human tissues for in vitro experimentation, slow dissemination of information between prostate cancer research teams and the increasing pressure to “ stretch” research dollars at the same time staff reductions are occurring.To meet these challenges, we have used the correlative microscopy (CM) and client/server (C/S) computing to increase productivity while decreasing costs. Critical elements of our program are as follows:1) Establishing the Western Pennsylvania Genitourinary (GU) Tissue Bank which includes >100 prostates from patients with prostate adenocarcinoma as well as >20 normal prostates from transplant organ donors.

Digital image acquisition, processing, and analysis in a polymer microscopy laboratory

1994 ◽  
Vol 52 ◽  
pp. 454-455
Author(s):  
Vinod K. Berry ◽  
Xiao Zhang
Keyword(s):  
United States ◽  
Image Analysis ◽  
Digital Image ◽  
Image Acquisition ◽  
Image Transmission ◽  
The United States ◽  
Quantitative Image Analysis ◽  
Quantitative Image

In recent years it became apparent that we needed to improve productivity and efficiency in the Microscopy Laboratories in GE Plastics. It was realized that digital image acquisition, archiving, processing, analysis, and transmission over a network would be the best way to achieve this goal. Also, the capabilities of quantitative image analysis, image transmission etc. available with this approach would help us to increase our efficiency. Although the advantages of digital image acquisition, processing, archiving, etc. have been described and are being practiced in many SEM, laboratories, they have not been generally applied in microscopy laboratories (TEM, Optical, SEM and others) and impact on increased productivity has not been yet exploited as well.In order to attain our objective we have acquired a SEMICAPS imaging workstation for each of the GE Plastic sites in the United States. We have integrated the workstation with the microscopes and their peripherals as shown in Figure 1.

Silence of the Land: On the Historical Irrelevance of Territory to Congressional Districting and Political Representation in the United States

2001 ◽  
Vol 15 (01) ◽  
pp. 53-87 ◽  
Author(s):  
Andrew Rehfeld
Keyword(s):  
United States ◽  
House Of Representatives ◽  
Political Representation ◽  
The United States ◽  
Representative Government ◽  
Congressional District ◽  
Congressional Districts ◽  
Communities Of Interest

Every ten years, the United States “constructs” itself politically. On a decennial basis, U.S. Congressional districts are quite literally drawn, physically constructing political representation in the House of Representatives on the basis of where one lives. Why does the United States do it this way? What justifies domicile as the sole criteria of constituency construction? These are the questions raised in this article. Contrary to many contemporary understandings of representation at the founding, I argue that there were no principled reasons for using domicile as the method of organizing for political representation. Even in 1787, the Congressional district was expected to be far too large to map onto existing communities of interest. Instead, territory should be understood as forming a habit of mind for the founders, even while it was necessary to achieve other democratic aims of representative government.

Sign in / Sign up

Export Citation Format

Share Document