New WSR-88D Volume Coverage Pattern 12: Results of Field Tests

Abstract For the first time since the installation of the national network of Weather Surveillance Radar-1988 Doppler (WSR-88D), a new scanning strategy—Volume Coverage Pattern 12 (VCP 12)—has been added to the suite of scanning strategies. VCP 12 is a faster version of VCP 11 and has denser vertical sampling at lower elevation angles. This note discusses results of field tests in Oklahoma and Mississippi during 2001–03 that led to the decision to implement VCP 12. Output from meteorological algorithms for a test-bed radar using an experimental VCP were compared with output for a nearby operational WSR-88D using VCP 11 or 21. These comparisons were made for severe storms that were at comparable distances from both radars. Findings indicate that denser vertical sampling at lower elevation angles leads to earlier and longer algorithm identifications of storm cells and mesocyclones, especially those more distant from a radar.

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Study on laser powder bed fusion of nickel-base alloy of G-surface structure: scanning strategy, properties and compression properties

Scientific Reports ◽

10.1038/s41598-021-86213-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Bo Qian ◽

Hongri Fan ◽

Jianrui Zhang ◽

Tengfei Li ◽

Jiangtao Xi ◽

...

Keyword(s):

Surface Structure ◽

Base Alloy ◽

Nickel Base Alloy ◽

Laser Powder Bed Fusion ◽

Scanning Strategy ◽

Powder Bed ◽

Compression Performance ◽

Solid Structure ◽

Nickel Base ◽

Scanning Strategies

AbstractAiming at laser powder bed fusion of GH3536 nickel base alloy, the effects of different scanning strategies on microstructure, porosity and mechanical properties were explored. In the aspect of microstructure and micro hardness of the sample, three scanning strategies had little difference; in the aspect of macro mechanical properties of the sample, the slope subarea scanning was better than the helix and island scanning. On this basis, the slope subarea scanning was selected as the optimal scanning strategy to form the G-surface structure, and the compression performance of G-surface was studied. The results showed that: (1) the compression performance of G-surface structure was smaller than that of solid structure, The compression strength of G-surface can only reach about 20% of solid structure: the average strength value of G-surface is 220 MPa, solid structure is 1.1 GMpa; while G-surface structure had a smooth compression curve, which indicated the good energy absorption characteristics; (2) with the increase of wall thickness, the mechanical performance of G-surface structure was also enhanced, while the energy absorption capacity was constantly reduced; (3) with the same wall thickness, the compression performance of sample in building direction (BD) is higher than that in horizontal direction (HD).

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Innovations Based on PCC

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.687.369 ◽

2013 ◽

Vol 687 ◽

pp. 369-377 ◽

Cited By ~ 4

Author(s):

Andrea Dimmig-Osburg

Keyword(s):

Mechanical Engineering ◽

Field Tests ◽

Innovative Development ◽

Self Compacting Concrete ◽

Cement Ratio ◽

Water Cement Ratio ◽

Innovation Potential ◽

Acrylic Ester ◽

Bridge Building ◽

First Time

Abstract. In this paper, three examples for the application of PCC are presented, which exceed the well established use as restoration material and show the great innovation potential of these materials. The first example shows an innovative development of a polymer-modified self-compacting concrete (SPCC) for the restoration of vertical facing concrete surfaces. In the second example PCC was for the first time applied as construction concrete to a bridge building. The last instance describes the potential of the SPCC for special applications in mechanical engineering. A styrene acrylic ester dispersion and different sorts of cement were used. The polymer/cement-ratio varied from 0.05 to 0.10. The water/cement-ratio depended on the requirements of the different PCC. The essential laboratory and field tests as well as the results are described.

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Evaluation of Distributed Collaborative Adaptive Sensing for Detection of Low-Level Circulations and Implications for Severe Weather Warning Operations

Weather and Forecasting ◽

10.1175/2009waf2222233.1 ◽

2010 ◽

Vol 25 (1) ◽

pp. 173-189 ◽

Cited By ~ 21

Author(s):

J. Brotzge ◽

K. Hondl ◽

B. Philips ◽

L. Lemon ◽

E. J. Bass ◽

...

Keyword(s):

Severe Weather ◽

Special Focus ◽

Test Bed ◽

Scanning Strategy ◽

Engineering Research ◽

Low Level ◽

Adaptive Sensing ◽

Low Levels ◽

Casa System ◽

Better Than

Abstract The Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is a multiyear engineering research center established by the National Science Foundation for the development of small, inexpensive, low-power radars designed to improve the scanning of the lowest levels (<3 km AGL) of the atmosphere. Instead of sensing autonomously, CASA radars are designed to operate as a network, collectively adapting to the changing needs of end users and the environment; this network approach to scanning is known as distributed collaborative adaptive sensing (DCAS). DCAS optimizes the low-level volume coverage scanning and maximizes the utility of each scanning cycle. A test bed of four prototype CASA radars was deployed in southwestern Oklahoma in 2006 and operated continuously while in DCAS mode from March through June of 2007. This paper analyzes three convective events observed during April–May 2007, during CASA’s intense operation period (IOP), with a special focus on evaluating the benefits and weaknesses of CASA radar system deployment and DCAS scanning strategy of detecting and tracking low-level circulations. Data collected from nearby Weather Surveillance Radar-1988 Doppler (WSR-88D) and CASA radars are compared for mesoscyclones, misocyclones, and low-level vortices. Initial results indicate that the dense, overlapping coverage at low levels provided by the CASA radars and the high temporal (60 s) resolution provided by DCAS give forecasters more detailed feature continuity and tracking. Moreover, the CASA system is able to resolve a whole class of circulations—misocyclones—far better than the WSR-88Ds. In fact, many of these are probably missed completely by the WSR-88D. The impacts of this increased detail on severe weather warnings are under investigation. Ongoing efforts include enhancing the DCAS data quality and scanning strategy, improving the DCAS data visualization, and developing a robust infrastructure to better support forecast and warning operations.

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C-Band Dual-Doppler Retrievals in Complex Terrain: Improving the Knowledge of Severe Storm Dynamics in Catalonia

Remote Sensing ◽

10.3390/rs12182930 ◽

2020 ◽

Vol 12 (18) ◽

pp. 2930 ◽

Cited By ~ 1

Author(s):

Anna del Moral ◽

Tammy M. Weckwerth ◽

Tomeu Rigo ◽

Michael M. Bell ◽

María Carmen Llasat

Keyword(s):

Complex Terrain ◽

Prediction Models ◽

Weather Prediction ◽

Warning System ◽

Wind Fields ◽

Severe Thunderstorm ◽

Radar Network ◽

Storm Dynamics ◽

Storm Cells ◽

First Time

Convective activity in Catalonia (northeastern Spain) mainly occurs during summer and autumn, with severe weather occurring 33 days per year on average. In some cases, the storms have unexpected propagation characteristics, likely due to a combination of the complex topography and the thunderstorms’ propagation mechanisms. Partly due to the local nature of the events, numerical weather prediction models are not able to accurately nowcast the complex mesoscale mechanisms (i.e., local influence of topography). This directly impacts the retrieved position and motion of the storms, and consequently, the likely associated storm severity. Although a successful warning system based on lightning and radar observations has been developed, there remains a lack of knowledge of storm dynamics that could lead to forecast improvements. The present study explores the capabilities of the radar network at the Meteorological Service of Catalonia to retrieve dual-Doppler wind fields to study the dynamics of Catalan thunderstorms. A severe thunderstorm that splits and a tornado-producing supercell that is channeled through a valley are used to demonstrate the capabilities of an advanced open source technique that retrieves dynamical variables from C-band operational radars in complex terrain. For the first time in the Iberian Peninsula, complete 3D storm-relative winds are obtained, providing information about the internal dynamics of the storms. This aids in the analyses of the interaction between different storm cells within a system and/or the interaction of the cells with the local topography.

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Field Test Investigation of the Pile Jacking Performance for Prefabricated Square Rigid-Drainage Piles in Saturated Silt Sandy Soils

Advances in Civil Engineering ◽

10.1155/2019/4587929 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11 ◽

Cited By ~ 3

Author(s):

Xiangying Wang

Keyword(s):

Pore Water ◽

Field Test ◽

Pore Water Pressure ◽

Water Pressure ◽

Field Tests ◽

Excess Pore Water Pressure ◽

New Type ◽

Test Investigation ◽

First Time ◽

Excess Pore

The rigid-drainage pile, designed to accelerate the dissipation of excess pore water pressure around the pile, is a new type of pile that combines the bearing capacity of ordinary rigid piles and the draining capacity of gravel piles. Field tests of these new piles were performed for the first time at a construction site in the new campus of Jiangyin No. 1 High School. Numerous parameters were observed for the test piles in many trials, including the excess pore water pressures, horizontal soil pressures, and displacements. At the measuring position at 0.6 m from the pile center, the rigid-drainage pile dissipates 70% of the peak excess pore water pressure in 1000 s, whereas the ordinary pile requires nearly 4000 s to dissipate the identical amplitude. The field test results clearly demonstrate that the rigid-drainage pile can reduce the amplitude of the peak pressure caused by piling in the liquefiable layer, quickly dissipate the excess pore water pressure, reduce the loss of effective stress in the soil surrounding the pile, and maintain the foundation stability.

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The Effect of a Scanning Strategy on the Residual Stress of 316L Steel Parts Fabricated by Selective Laser Melting (SLM)

Materials ◽

10.3390/ma11101821 ◽

2018 ◽

Vol 11 (10) ◽

pp. 1821 ◽

Cited By ~ 13

Author(s):

Di Wang ◽

Shibiao Wu ◽

Yongqiang Yang ◽

Wenhao Dou ◽

Shishi Deng ◽

...

Keyword(s):

Residual Stress ◽

Selective Laser Melting ◽

Laser Scanning ◽

Effective Means ◽

Laser Melting ◽

Scanning Strategy ◽

Deformation Degree ◽

316L Steel ◽

Stress And Deformation ◽

Scanning Strategies

The laser scanning strategy has an important influence on the surface quality, residual stress, and deformation of the molten metal (deformation behavior). A divisional scanning strategy is an effective means used to reduce the internal stress of the selective laser melting (SLM) metal part. In order to understand and optimize the divisional scanning strategy, three divisional scanning strategies and an S-shaped orthogonal scanning strategy are used to produce 316L steel parts in this study. The influence of scanning strategy on the produced parts is verified from the aspects of densification, residual stress distribution and deformation. Experiments show that the 316L steel alloy parts adopted spiral divisional scanning strategy can not only obtain the densification of 99.37%, but they also effectively improve the distribution of residual stress and control the deformation degree of the produced parts. Among them, the spiral divisional scanning sample has the smallest residual stress in plane direction, and its σx and σy stress are controlled within 204 MPa and 103 MPa. The above results show that the spiral divisional scanning is the most conducive strategy to obtain higher residual stress performance of SLM 316L steel parts.

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Experience in conducting field tests of metal structural constructions of coatings of the “BrSTU”

E3S Web of Conferences ◽

10.1051/e3sconf/202021202015 ◽

2020 ◽

Vol 212 ◽

pp. 02015

Author(s):

Mikalai Shalabyta ◽

Andrei Shuryn ◽

Tatsiana Shalabyta ◽

Viacheslav Dragan

Keyword(s):

Theoretical Calculations ◽

Field Tests ◽

Full Scale ◽

Complex Structures ◽

Building Structures ◽

The World ◽

Special Approach ◽

Full Scale Tests ◽

Degree Of Participation ◽

First Time

There are quite often statically complex structures, the reliability of theoretical calculations of which needs experimental verification in the world practice of design and construction. Studies of building structures functioning can be full-scale or carried out on their models in laboratory conditions depending on the goals set. Full-scale tests of building structures are more expensive, therefore, their implementation requires a special approach and justification. However, to check the operation of complex, critical structures which primarily include metal spatial large-span structures of coatings of buildings and structures especially those used for the first time to assess their bearing capacity, to establish the degree of participation in the construction of each of the elements, to study the operation of individual new nodal elements etc., only full-scale tests are required.

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Study on Laser Powder Bed Fusion of Nickel-base Alloy: Scanning Strategy, Properties and Compression Properties

10.21203/rs.3.rs-128086/v1 ◽

2020 ◽

Author(s):

Bo Qian ◽

Hongri Fan ◽

Tengfei Li ◽

Jianrui Zhang ◽

Jiangtao Xi ◽

...

Keyword(s):

Surface Structure ◽

Base Alloy ◽

Powder Bed Fusion ◽

Nickel Base Alloy ◽

Laser Powder Bed Fusion ◽

Scanning Strategy ◽

Powder Bed ◽

Compression Performance ◽

Nickel Base ◽

Scanning Strategies

Abstract Aiming at laser powder bed fusion of GH3536 nickel base alloy, the effects of different scanning strategies on microstructure, porosity and mechanical properties were explored. In the aspect of microstructure and micro hardness of the sample, three scanning strategies had little difference; in the aspect of macro mechanical properties of the sample, the slope subarea scanning was better than the helix and island scanning. On this basis, the slope subarea scanning was selected as the optimal scanning strategy to form the G-surface structure, and the compression performance of G-surface was studied. The results showed that: (1) the compression performance of G-surface structure was smaller than that of solid structure; while G-surface structure had a smooth compression curve, which indicated the good energy absorption characteristics; (2) with the increase of wall thickness, the mechanical performance of G-surface structure was also enhanced, while the energy absorption capacity was constantly reduced; (3) with the same wall thickness, the compression performance of sample in building direction (BD) is higher than that in horizontal direction (HD).

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Influence of Scanning Strategy on the Performances of GO-Reinforced Ti6Al4V Nanocomposites Manufactured by SLM

Metals ◽

10.3390/met10101379 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1379

Author(s):

Xiaojin Miao ◽

Xin Liu ◽

Peipei Lu ◽

Jitai Han ◽

Weipeng Duan ◽

...

Keyword(s):

Temperature Gradients ◽

Experimental Results ◽

Laser Melting ◽

Scanning Strategy ◽

Concentration Effects ◽

Powder Bed ◽

Simulation Results ◽

Scanning Strategies ◽

Matrix Nanocomposites ◽

Simulation Scheme

In this work, the effects of line (L-scanning strategy), stripe (S-scanning strategy), hollow square (H-scanning strategy) and chess board partition (C-scanning strategy) on the performances of graphene oxide reinforced Ti6Al4V matrix nanocomposites (GO/TC4) as fabricated by selective laser melting (SLM) were investigated. Numerical temperature field simulation of four different scanning strategies was utilized to investigate the effects of thermal concentration on SLM-processed GO/TC4 nanocomposites, linking to its micro-voids, surface roughness, porosity, microhardness and tribological properties. The proposed simulation scheme is validated by comparing the simulated thermal analysis with experimental results. Simulation results show that the thermal concentration effects of a part during SLM process is distinctive under different scanning strategies, with the slowest cooling rate of 64,977.5 °C/s that is achieved by C-scanning strategy specimen. The experimental results indicate that the performances of the L-scanning strategy or S-scanning strategy sample are seriously affected by the thermal concentration, causing a large number of micro-voids and defects. All the experimental results suggest that the sample using C-scanning strategy exhibits the optimal performance of all investigated specimens, which closely correlates with its lowest temperature gradients. This study highlights the importance of using a partition scanning strategy during SLM process, which can be easily extended to other powder bed fusion process.

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Dome C coherence time statistics from DIMM data

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1862 ◽

2020 ◽

Vol 496 (4) ◽

pp. 4822-4826

Author(s):

E Aristidi ◽

A Agabi ◽

L Abe ◽

E Fossat ◽

A Ziad ◽

...

Keyword(s):

Time Dependence ◽

Local Time ◽

Adaptive Optics ◽

Coherence Time ◽

Test Bed ◽

Sharp Maximum ◽

Seasonal Behaviour ◽

Natural Test ◽

First Time ◽

Adaptive Optics System

ABSTRACT We present a reanalysis of several years of DIMM data at the site of Dome C, Antarctica, to provide measurements of the coherence time τ0. Statistics and seasonal behaviour of τ0 are given at two heights above the ground, 3 and 8 m, for the wavelength λ = 500 nm. We found an annual median value of 2.9 ms at the height of 8 m. A few measurements could also be obtained at the height of 20 m and give a median value of 6 ms during the period June–September. For the first time, we provide measurements of τ0 in daytime during the summer, which appears to show the same time dependence as the seeing with a sharp maximum at 5 pm local time. Exceptional values of τ0 above 10 ms are met at this particular moment. The continuous slow variations of turbulence conditions during the day offers a natural test bed for a solar adaptive optics system.

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