scholarly journals A Forecast Strategy for Anticipating Cold Season Mesoscale Band Formation within Eastern U.S. Cyclones

2006 ◽  
Vol 21 (1) ◽  
pp. 3-23 ◽  
Author(s):  
David R. Novak ◽  
Jeff S. Waldstreicher ◽  
Daniel Keyser ◽  
Lance F. Bosart
Keyword(s):  
Short Range ◽  
Situational Awareness ◽  
Weather Prediction ◽  
Cold Season ◽  
Band Formation ◽  
Cross Sectional ◽  
Plan View ◽  
Operational Forecasts ◽  
Resolution Model ◽  
Symmetric Stability

Abstract An ingredients-based, time- and scale-dependent forecast strategy for anticipating cold season mesoscale band formation within eastern U.S. cyclones is presented. This strategy draws on emerging conceptual models of mesoscale band development, advances in numerical weather prediction, and modern observational tools. As previous research has shown, mesoscale band development is associated with frontogenesis in the presence of weak moist symmetric stability and sufficient moisture. These three parameters—frontogenesis, weak moist symmetric stability, and moisture—are used as the ingredients for identifying mesoscale band development in this strategy. At forecast projections beyond 2 days, the strategy assesses whether cyclogenesis is expected. Within 2 days of the event, the strategy places the band ingredients in the context of the broader synoptic flow, with attention to where deformation zones are present, to assess whether banding is possible. Within 1 day of the event, the strategy focuses on assessment of the ingredients to outline when and where band formation is favored. Plan-view and cross-sectional analyses of gridded model fields in conjunction with high-resolution model guidance are used to assess the likelihood of banding and to outline the threat area. Within 12 h, short-range forecasts of the band ingredients are evaluated in concert with observations to make specific band predictions. Particular emphasis is placed on the evolution of the frontogenetic forcing and moist symmetric stability. During the event, trends in observations and short-range model forecasts are used to anticipate the movement, intensity, and dissipation of the band. The benefits and practical challenges associated with the proposed strategy are illustrated through its operational application to the 25 December 2002 northeast U.S. snowstorm, during which intense mesoscale snowband formation occurred. Forecast products from this event demonstrate how the forecast strategy can lead to heightened situational awareness, in this case resulting in accurate band forecasts. This application shows that accurate operational forecasts of mesoscale bands can be made based on our current conceptual understanding, observational tools, and modeling capabilities.

The reaction of amorphous Ni-Nb films with Si in the presence of a native SiO2 layer

1990 ◽  
Vol 48 (4) ◽  
pp. 664-665
Author(s):  
N. Rozhanski ◽  
A. Barg
Keyword(s):  
High Temperature ◽  
Crystallization Temperature ◽  
Diffusion Barriers ◽  
Sio2 Layer ◽  
Si Substrate ◽  
Cross Sectional ◽  
Plan View ◽  
Temperature Range ◽  
Sputter Deposited

Amorphous Ni-Nb alloys are of potential interest as diffusion barriers for high temperature metallization for VLSI. In the present work amorphous Ni-Nb films were sputter deposited on Si(100) and their interaction with a substrate was studied in the temperature range (200-700)°C. The crystallization of films was observed on the plan-view specimens heated in-situ in Philips-400ST microscope. Cross-sectional objects were prepared to study the structure of interfaces.The crystallization temperature of Ni5 0 Ni5 0 and Ni8 0 Nb2 0 films was found to be equal to 675°C and 525°C correspondingly. The crystallization of Ni5 0 Ni5 0 films is followed by the formation of Ni6Nb7 and Ni3Nb nucleus. Ni8 0Nb2 0 films crystallise with the formation of Ni and Ni3Nb crystals. No interaction of both films with Si substrate was observed on plan-view specimens up to 700°C, that is due to the barrier action of the native SiO2 layer.

Identification of Root Cause Failure in Silicon on Insulator Body Contacted nFETs Using Scanning Capacitance Microscopy and Scanning Spreading Resistance Microscopy

2006 ◽  
Author(s):  
J.S. McMurray ◽  
C.M. Molella
Keyword(s):  
The Body ◽  
Silicon On Insulator ◽  
Back Side ◽  
Cross Sectional ◽  
Plan View ◽  
Spreading Resistance ◽  
Scanning Capacitance Microscopy ◽  
Root Cause ◽  
Cross Sectional Imaging ◽  
Active Channel

Abstract Root cause for failure of 90 nm body contacted nFETs was identified using scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM). The failure mechanism was identified using both cross sectional imaging and imaging of the active silicon - buried oxide (BOX) interface in plan view. This is the first report of back-side plan view SCM and SSRM data for SOI devices. This unique plan view shows the root cause for the failure is an under doped link up region between the body contacts and the active channel of the device.

A New Method of Wafer Level Plan View TEM Sample Preparation by DualBeam

2008 ◽  
Author(s):  
Hyoung H. Kang ◽  
Michael A. Gribelyuk ◽  
Oliver D. Patterson ◽  
Steven B. Herschbein ◽  
Corey Senowitz
Keyword(s):  
Sample Preparation ◽  
Ex Situ ◽  
Wafer Level ◽  
Cross Sectional ◽  
Plan View ◽  
Manufacturing Line ◽  
Transmission Electron ◽  
Thin Lamella ◽  
Preparation Techniques

Abstract Cross-sectional style transmission electron microscopy (TEM) sample preparation techniques by DualBeam (SEM/FIB) systems are widely used in both laboratory and manufacturing lines with either in-situ or ex-situ lift out methods. By contrast, however, the plan view TEM sample has only been prepared in the laboratory environment, and only after breaking the wafer. This paper introduces a novel methodology for in-line, plan view TEM sample preparation at the 300mm wafer level that does not require breaking the wafer. It also presents the benefit of the technique on electrically short defects. The methodology of thin lamella TEM sample preparation for plan view work in two different tool configurations is also presented. The detailed procedure of thin lamella sample preparation is also described. In-line, full wafer plan view (S)TEM provides a quick turn around solution for defect analysis in the manufacturing line.

scholarly journals 764 Human Factors in Operative Theatres During the Covid-19 Pandemic: A Cross-sectional Analysis of Operating Theatre Staff Experiences in a Regional Centre

2021 ◽  
Vol 108 (Supplement_2) ◽  
Author(s):  
L E Murchison ◽  
R Anbarasan ◽  
A Mathur ◽  
M Kulkarni
Keyword(s):  
Human Factors ◽  
Online Survey ◽  
Situational Awareness ◽  
Negative Impact ◽  
High Stress ◽  
Operating Theatre ◽  
Free Text ◽  
Cross Sectional ◽  
Chi Squared ◽  
Theatre Staff

Abstract Introduction In the already high-risk, high-stress environment of the operating theatre, operating during Covid-19 has brought its own unique challenges. Communication, teamwork and anxiety related new operating practices secondary to Covid-19 are hypothesised to have a negative impact on patient care. Method We conducted a single-centre online survey of operating theatre staff from 22nd June–6th July 2020. Respondents completed 18 human factors questions related to COVID-19 precautions including communication, teamwork, situational awareness, decision making, stress, fatigue, work environment and organisational culture. Questions consisted of yes/no responses, multiple choice and Likert items. Kruskall-Wallis tests, Chi-Squared, Mann Whitney U tests, Spearman’s correlation coefficient, lambda and Cramer’s V tests were used. Free-text responses were also reviewed. Results 116 theatre staff responded. Visual (90.5%), hearing/ understanding (96.6%) difficulties, feeling faint/lightheaded (66.4%) and stress (47.8%) were reported. Decreased situational awareness was reported by 71.5% and correlated with visors (r = 0.27 and p = 0.03) and FFP2/3 mask usage (r = 0.29 and p = 0.01). Reduced efficiency of theatre teams was reported by 75% of respondents and 21.5% felt patient safety was at greater risk due to Covid-19 precautions in theatre. Conclusions Organisational adjustments are required, and research focused on development of fit-for-purpose personal protective equipment (PPE).

Development of High-Performance GaAs Solar Cells on Large-Grain Polycrystalline Ge Substrates

1995 ◽  
Vol 403 ◽  
Author(s):  
R. Venkatasubramanian ◽  
B. O'Quinn ◽  
J. S. Hills ◽  
M. L. Timmons ◽  
D. P. Malta
Keyword(s):  
Solar Cells ◽  
High Performance ◽  
Carrier Lifetime ◽  
Minority Carrier ◽  
Minority Carrier Lifetime ◽  
Cross Sectional ◽  
Plan View ◽  
Electron Beam Induced Current ◽  
Induced Defects

AbstractThe characterization of MOCVD-grown GaAs-AlGaAs materials and GaAs p+n junctions on poly-Ge substrates is presented. Minority carrier lifetime in GaAs-AIGaAs double-hetero (DH) structures grown on these substrates and the variation of lifetimes across different grainstructures are discussed. Minority-carrier diffusion lengths in polycrystalline GaAs p+-n junctions were evaluated by cross-sectional electron-beam induced current (EBIC) scans. The junctions were also studied by plan-view EBIC imaging. Optimization studies of GaAs solar cell on poly-Ge are discussed briefly. The effect of various polycrystalline substrate-induced defects on performance of GaAs solar cells are presented.

scholarly journals The Effect of Upstream Convection on Downstream Precipitation

2007 ◽  
Vol 22 (2) ◽  
pp. 255-277 ◽  
Author(s):  
Kelly M. Mahoney ◽  
Gary M. Lackmann
Keyword(s):  
Moisture Transport ◽  
Weather Prediction ◽  
The United States ◽  
Cold Season ◽  
Precipitation Forecast ◽  
Study Region ◽  
Low Level ◽  
Convective Systems ◽  
Eta Model ◽  
Nwp Model

Abstract Operational forecasters in the southeast and mid-Atlantic regions of the United States have noted a positive quantitative precipitation forecast (QPF) bias in numerical weather prediction (NWP) model forecasts downstream of some organized, cold-season convective systems. Examination of cold-season cases in which model QPF guidance exhibited large errors allowed identification of two representative cases for detailed analysis. The goals of the case study analyses are to (i) identify physical mechanisms through which the upstream convection (UC) alters downstream precipitation amounts, (ii) determine why operational models are challenged to provide accurate guidance in these situations, and (iii) suggest future research directions that would improve model forecasts in these situations and allow forecasters to better anticipate such events. Two primary scenarios are identified during which downstream precipitation is altered in the presence of UC for the study region: (i) a fast-moving convective (FC) scenario in which organized convective systems oriented parallel to the lower-tropospheric flow are progressive relative to the parent synoptic system, and appear to disrupt poleward moisture transport, and (ii) a situation characterized by slower-moving convection (SC) relative to the parent system. Analysis of a representative FC case indicated that moisture consumption, stabilization via convective overturning, and modification of the low-level flow to a more westerly direction in the postconvective environment all appear to contribute to the reduction of downstream precipitation. In the FC case, operational Eta Model forecasts moved the organized UC too slowly, resulting in an overestimate of downstream moisture transport. A 4-km explicit convection model forecast from the Weather Research and Forecasting model produced a faster-moving upstream convective system and improved downstream QPF. In contrast to the FC event, latent heat release in the primary rainband is shown to enhance the low-level jet ahead of the convection in the SC case, thereby increasing moisture transport into the downstream region. A negative model QPF bias was observed in Eta Model forecasts for the SC event. Suggestions are made for precipitation forecasting in UC situations, and implications for NWP model configuration are discussed.

scholarly journals Adding to Fire Fighter Safety by Including Real-Time Radar Data in Short-Range Forecasts of Thunderstorm-Induced Wind Shifts

Fire ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 55
Author(s):  
Gary L. Achtemeier ◽  
Scott L. Goodrick
Keyword(s):  
Real Time ◽  
Short Range ◽  
Prediction Models ◽  
Weather Prediction ◽  
Radar Data ◽  
Mitigation Strategies ◽  
Density Currents ◽  
Gust Fronts ◽  
Gust Front ◽  
Range Forecasts

Abrupt changes in wind direction and speed caused by thunderstorm-generated gust fronts can, within a few seconds, transform slow-spreading low-intensity flanking fires into high-intensity head fires. Flame heights and spread rates can more than double. Fire mitigation strategies are challenged and the safety of fire crews is put at risk. We propose a class of numerical weather prediction models that incorporate real-time radar data and which can provide fire response units with images of accurate very short-range forecasts of gust front locations and intensities. Real-time weather radar data are coupled with a wind model that simulates density currents over complex terrain. Then two convective systems from formation and merger to gust front arrival at the location of a wildfire at Yarnell, Arizona, in 2013 are simulated. We present images of maps showing the progress of the gust fronts toward the fire. Such images can be transmitted to fire crews to assist decision-making. We conclude, therefore, that very short-range gust front prediction models that incorporate real-time radar data show promise as a means of predicting the critical weather information on gust front propagation for fire operations, and that such tools warrant further study.

Direct Deposition Reactions Between Nickel and Silicon Substrates

1993 ◽  
Vol 311 ◽  
Author(s):  
Lin Zhang ◽  
Douglas G. Ivey
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silicon Substrates ◽  
Silicide Formation ◽  
Cross Sectional ◽  
Deposition Rates ◽  
Plan View ◽  
X Ray ◽  
Si Substrates ◽  
Transmission Electron

ABSTRACTSilicide formation through deposition of Ni onto hot Si substrates has been investigated. Ni was deposited onto <100> oriented Si wafers, which were heated up to 300°C, by e-beam evaporation under a vacuum of <2x10-6 Torr. The deposition rates were varied from 0.1 nm/s to 6 nm/s. The samples were then examined by both cross sectional and plan view transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy and electron diffraction. The experimental results are discussed in terms of a new kinetic model.

scholarly journals Short-Range Numerical Weather Prediction of Extreme Precipitation Events Using Enhanced Surface Data Assimilation

Atmosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 587
Author(s):  
Magnus Lindskog ◽  
Tomas Landelius
Keyword(s):  
Data Assimilation ◽  
Numerical Weather Prediction ◽  
Short Range ◽  
Weather Prediction ◽  
Heavy Precipitation ◽  
Numerical Weather ◽  
Extreme Precipitation Events ◽  
Surface Data ◽  
Enhanced Surface ◽  
Precipitation Events

A limited-area kilometre scale numerical weather prediction system is applied to evaluate the effect of refined surface data assimilation on short-range heavy precipitation forecasts. The refinements include a spatially dependent background error representation, use of a flow-dependent data assimilation technique, and use of data from a satellite-based scatterometer instrument. The effect of the enhancements on short-term prediction of intense precipitation events is confirmed through a number of case studies. Verification scores and subjective evaluation of one particular case points at a clear impact of the enhanced surface data assimilation on short-range heavy precipitation forecasts and suggest that it also tends to slightly improve them. Although this is not strictly statistically demonstrated, it is consistent with the expectation that a better surface state should improve rainfall forecasts.

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