ARTICLE | doi:10.20944/preprints202007.0460.v1
Online: 20 July 2020 (08:37:56 CEST)
Recently, the intensities of natural disasters have increased significantly owing to climate change and various other environmental factors, causing unprecedented damage. Measures must be established to reduce damage from large-scale natural disasters caused by the rapidly changing environment. The Japanese government published a hazard map manual in 2015 and obligates the creation of a hazard map as a measure to reduce high-scale storm surges. This manual presents a typhoon model based on a parametric model that is used to create a hazard map. The Myers model assuming concentric circles, which is primarily used in East Asia, is disadvantageous as it cannot consider geographic characteristics. Therefore, a new parametric model is necessary to calculate wind and pressure fields, which change according to geographic characteristics. To improve this limitation of the Myers model, we calculated the wind and pressure fields considering geographical effects by combining the Holland model, which can consider the size of a developing typhoon, and the Mascon model, which changes by geographic characteristics. To determine the gradient coefficient of the Holland model, the coefficient that changes every moment was calculated using grid point value data. The result indicated excellent reproducibility of storm surge height according to the geographic characteristics.
Subject: Engineering, Electrical & Electronic Engineering Keywords: transient analysis; surge arrester allocation; genetic algorithm; ATP
Online: 1 September 2019 (09:59:23 CEST)
Lightning discharges in electric power networks generate voltage and current surges that are propagated through the electrical network causing damage and shutdowns in the electrical system. To protect the system against these phenomena, surge arresters are very effective and widely used by electrical utilities in their electric grids. This paper presents a methodology for optimized surge arrester allocation based on genetic algorithm (GA), creating a simulation environment in the software ATP (Alternative Transients Program) to implement the proposed methodology. The optimized allocation procedure is based on a fitness function that minimizes the cost of surge arresters and maximizes the number of protected equipment. To carry out this optimized arrester allocation procedure using ATP may demand too much processing time when running large distribution grids. To overcome this difficulty a procedure is proposed to obtain an overvoltage severity description of the grid and select the most critical electric nodes for the incidence of lightning discharges, in the GA allocation procedure. The case study is applied to the IEEE 123-bus electrical feeder to demonstrate the effectiveness of the proposed methodology.
ARTICLE | doi:10.20944/preprints202109.0282.v1
Subject: Social Sciences, Geography Keywords: storm surge; coastal region; flooding risk; Rio Grande Valley
Online: 16 September 2021 (11:52:36 CEST)
(1) Background: Cameron County, which is located in the Rio Grande Valley, holds historical records for storm surges with noticeable property damage, fatalities, and injuries; (2) Methods: using storm surge hazard datasets from the National Oceanic and Atlantic Agency (NOAA), and American Community Survey (ACS) 2019 datasets and Geographic Information System (GIS), the study estimates at-risk population and their socio-demographic attributes; (4) Conclusions: Estimated water levels of a storm surge could be reached up to 5 feet in category 1 event, 9 feet in category 2, 17 feet in category 3, and above 20 feet in category 4 and 5. In the category 5 event, there is an estimated 37% (159,659) of the total county’s population (434,294) will be under flooded water. Suggestions are made to better prepare and successfully evaluate.
ARTICLE | doi:10.20944/preprints202202.0256.v1
Subject: Engineering, Mechanical Engineering Keywords: Casing treatment; Surge margin; Rotating stall; surface roughness; flow instability
Online: 21 February 2022 (14:52:08 CET)
Influence of the volute design parameters on the stable operating range and the performance of a centrifugal compressor was investigated experimentally for the following design conditions. The volute casing surface roughness was changed from 0 to 200 µm in five steps and tested. The axial distance between the casing and the diffuser cascades (clearance) was varied in five steps as C/b2 = 1.2, 2.4%, 3.6%, 4.8%, and 6% relative to the impeller exit width. The radial distance from the impeller blade exit to the diffuser vane inlet in (vaneless space radius) in six steps as C/r2 = 1.03, 1.05, 1.07, 1.09, 1.11, and 1. 13 relatives to the rotor outlet radius. The volute outlet geometry of a symmetric and tangent with different area ratios from 0.4 to 0.9. Finally, the compressor has been tested experimentally with different pinched vaned diffuser distances relative to the impeller exit width of bp/b2 =1, 0.98, 0.96, 0.94, 0.92, and 0.9. These testes were carried at different compressor operating conditions, and the time variations of the static pressure were recorded using five high-frequency response pressure transducers. A hot-wire anemometer is used to measure the compressor flow rate. The rotating stall and surge at the vaneless zone after the impeller exit can be detected by analyzing the fluctuations of pressure signals and the power spectrum density by using the Fast Fourier Transformation analysis. The experimental results indicated that the compressor with volute casing surface roughness of 100mm gives about 10.9% enhancements in the stable operating and 1% in pressure rise coefficient. The best axial distance between the diffuser vanes and the casing is 2.4% of the impeller blade height and the compressor in this design gives about 12.4% improvements in the stable working range. The compressor with radial vaneless distance of 1.056 gives improvements of about 16.6% in the surge margin, 2% in the pressure recovery and 4% in pressure rise coefficients. The compressor with a pinched diffuser of b/bp of 0.98 gives an improvement of 20.8% in surge point.
COMMUNICATION | doi:10.20944/preprints202103.0503.v1
Subject: Social Sciences, Accounting Keywords: social networks; digital surge; COVID-19 pandemic; technology industry; Clubhouse
Online: 19 March 2021 (14:52:38 CET)
Being a combination of the conference call, talkback radio, audio podcast, and an online video chat, Clubhouse is a new social networking app that gained over 10 million users and over $100 in valuation in just 8 months. Unlike other social networks, it offers a real-time streaming audio chat that does not ask users to share any unnecessary information like exchanging text messages, conducting video calls, or sharing photos. Instead, Clubhouse users can listen to real-time conversations, contribute to these conversations and create their own conversations for the others to listen and to interact with. Often nicknamed a “Silicon Valley’s hottest start-up”, Clubhouse positions itself as an “exclusive” and “alternative” social network that attracts various celebrities and people who just want to talk to each other. Launched in March 2020, amidst the COVID-19 pandemic with its social distancing and lockdowns, Clubhouse offered its users a space for the digital group psychotherapy where people could solve their problems by talking them through with strangers. However, it is unclear what is going to happen to this new social network in the post-pandemic world after all of its hype eventually evaporates. This paper discusses the possible underlying motives for the Clubhouse creation and its real purposes. Moreover, it looks at the three possible scenarios of its further development.
TECHNICAL NOTE | doi:10.20944/preprints202010.0063.v1
Subject: Earth Sciences, Atmospheric Science Keywords: CE-1 IIM; photometric correction; Hapke model; observing geometries; opposition surge
Online: 5 October 2020 (10:50:32 CEST)
The main objective of this study is to develop a Hapke photometric model that is suited for Chang’E-1 (CE-1) Interference Imaging Spectrometer (IIM) data. We first divided the moon into three areas including ‘maria’, ‘new highland’ and old ‘highland’ with similar photometry characteristic based on the Hapke parameters of the moon derived from Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) multispectral data. Then, we selected the sample data in the ‘maria’ area and obtained a new set of Hapke model’s parameters that can best fit these data. Result shows that photometric correction using Hapke model with these new derived parameters can eliminate the effect of variations in viewing and luminating geometry, especially ‘opposition surge’, more efficiently than the empirical model. The corrected mosaic shows no significant artifacts along the tile boundaries, and more detailed information of the image can be exhibited due to a better correction of ‘opposition surge’ at small phase angle (g <15°).
ARTICLE | doi:10.20944/preprints201810.0439.v1
Subject: Engineering, Civil Engineering Keywords: hurricane storm surge; emergency management; coastal inundation; numerical model; South Texas
Online: 19 October 2018 (07:52:48 CEST)
The Lower Rio Grande Valley, South Texas is considered one of the more vulnerable coastal areas to flooding related with abrupt climate changes. From 1980-2017, there were 7 flooding events, 57 severe storm events, and 8 tropical cyclone events with losses exceeding $1 billion in the State of Texas, according to NOAA NCEI. Coastal flooding is typically a result of storm surge and heavy rainfall produced by hurricanes and tropical storms. In this study, the two-dimensional hydrodynamic flow circulation model is developed to predict the Lower Rio Grande Valley coastal area inundation due to the hurricane storm surge, especially in the case of Hurricane Beulah, 1967. The tropical cyclone properties and tidal constituents were assigned to the updated watershed geographic information with the bottom bathymetric and roughness data. For model validation, the Hurricane Dolly 2008 storm surge due to Hurricane Beulah at the coast and the storm surge reaches up to approximately 40 kilometers west from the coast through a natural river channel. This model can be used for a reliable engineering tool for the coastal hazard emergency management and disaster mitigation.
ARTICLE | doi:10.20944/preprints201905.0052.v1
Subject: Earth Sciences, Geophysics Keywords: sea level rise; coastal flood hazard; storm surge; extreme tidal level; GIS
Online: 6 May 2019 (10:57:09 CEST)
Portugal Mainland has hundreds of thousands of people living in the Atlantic coastal zone, with numerous high economic value activities and a high number of infrastructures that must be protected from natural coastal hazard, namely extreme storms and sea level rise (SLR). In the context of climate change adaptation strategies, a reliable and accurate assessment of the physical vulnerability to SLR is crucial. This study is a contribution to the implementation of flooding standards imposed by the European Directive 2007/60/EC, which requires each member state to assess the risk associated to SLR and floods caused by extreme events. Therefore, coastal hazard in the Continental Atlantic coast of Portugal Mainland was evaluated for 2025, 2050 and 2100 in the whole coastal extension with different sea level scenarios for different extreme event return periods and due to SLR. A coastal flooding probabilistic map was produced based on the developed methodology using Geographic Information Systems (GIS) technology. The Extreme Flood Hazard Index (EFHI) was determined on flood probabilistic bases through five probability intervals of 20% of amplitude. For a given SLR scenario, the EFHI is expressed, on the probabilistic flooding maps for an extreme tidal maximum level, by five hazard classes ranging from 1 (Very Low) to 5 (Extreme).
ARTICLE | doi:10.20944/preprints202112.0399.v1
Subject: Engineering, Energy & Fuel Technology Keywords: energy of currents; energy of waves; reservoir; seiche current; seiche wave; storm surge
Online: 24 December 2021 (10:54:22 CET)
The energy potential of long-period oscillations is estimated by comparing it with watercourse power. The relaxation time of long-period waves is chosen for the estimation time interval, during which their amplitude decreases e (Euler's number) times from the initial one. According to calculations, the amount of energy produced during this time by the watercourse is 9.35–18.71 million kW×h, while the amount of energy of long-period oscillations is 3–6 times less – 1.60–5.48 million kW×h. The components of the economic factor of using long-period waves and currents for electricity production are the predictability of their magnitudes and location of maxima, long-term availability, concentration.
Subject: Engineering, Electrical & Electronic Engineering Keywords: IoT; leakage current; Metal Oxide Surge Arrester; remote monitoring; resistive component of leakage current.
Online: 13 January 2021 (12:49:32 CET)
This article presents the development of the theoretical background and the design of an electronic device for monitoring the condition of a gapless Metal Oxide Surge Arrester (MOSA). The device is intended to be used online. Due to the inaccessibility and possible remote location of most surge arresters, it is equipped with a communication system, allowing the device to convey the measurement of the surge arrester characteristics under any conditions. By gathering measurements of the surge arrester’s resistive component of leakage current, it is possible to determine the condition of the MOSA. After interpreting the results, these can be sent via a data transfer unit to a server, which, in turn, sends it onward to the authorised personnel through the surge arrester control centre.
ARTICLE | doi:10.20944/preprints201808.0072.v4
Subject: Engineering, Civil Engineering Keywords: flood risk; copula; compound events; multivariate; storm surge; spatial dependence; coastal catchment; Bayesian Network.
Online: 11 September 2018 (14:19:43 CEST)
Traditional flood hazard analyses often rely on univariate probability distributions; however, in many coastal catchments, flooding is the result of complex hydrodynamic interactions between multiple drivers. For example, synoptic meteorological conditions can produce considerable rainfall-runoff, while also generating wind-driven elevated sea levels. When these drivers interact in space and time, they can exacerbate flood impacts; this phenomenon is known as compound flooding. In this paper, we build a Bayesian Network based on Gaussian copulas to generate the equivalent of 500 years of daily stochastic boundary conditions for a coastal watershed in Southeast Texas. In doing so, we overcome many of the limitations of conventional univariate approaches and are able to probabilistically represent compound floods caused by riverine and coastal interactions. We calculate the resulting water levels using a 1D steady-state hydraulic model and find that flood stages in the catchment are strongly affected by backwater effects from tributary inflows and downstream water levels. By comparing with a bathtub modeling approach, we show that simplifying the multivariate dependence between flood drivers can lead to an underestimation of flood impacts, highlighting that accounting for multivariate dependence is critical for the accurate representation of flood risk in coastal catchments prone to compound events.
ARTICLE | doi:10.20944/preprints202106.0614.v1
Subject: Earth Sciences, Atmospheric Science Keywords: marine weather; characteristic wave height; storm surge; shore platform; overtopping wave; hydrodynamics equation; flooding hazard
Online: 25 June 2021 (10:12:06 CEST)
Boulder dynamics may provide essential data for the coastal evolution and hazards assessment and can be focused as a proxy for the onshore effect of intense storm waves. In this work, detailed observations of currently available satellite imagery of the Earth surface allowed to identify several coastal boulders displacements in the Southern Apulia coast (Italy), in a period between July 2018 and June 2020. Field surveys confirmed the displacements of several dozens of boulders up to several meters in size, also allowing the determination of the initial position for many of them. Archive weather analyses identified two possible causative storms during the same period, and calculations based on analytical equations are found in agreement with the displacement by storm waves for most of the observed boulders. The results help to give insights about the onshore effect of high storm waves on the coastal hydrodynamics and the possible future flooding hazard in the studied coast.
ARTICLE | doi:10.20944/preprints201911.0036.v1
Subject: Engineering, Mechanical Engineering Keywords: turboshaft; axial compressor; blade; FEM; CFD; erosion; wear; stall margin; compressor surge; brownout; gas-turbine performance
Online: 4 November 2019 (03:58:12 CET)
This paper analyses the health and performance of 12-stage axial compressor of the TV3-117VM/VMA turboshaft operated in a desert environment. The results of the dimensional control of 4,800 worn blades are analysed to model the wear process. Operational experience and numerical simulations are used to assess the effectiveness of an Inlet Particle Separator. Numerical modal analysis is performed to generate the Campbell diagram of worn blades and identify resonant blade vibration which can lead to high cycle fatigue (HCF). It is shown that the gradual loss of the stall margin over time determines the serviceability limits of compressor blades. Recommendations setting out go / no-go criteria are made to maintenance and repair organisations.
REVIEW | doi:10.20944/preprints202205.0227.v1
Subject: Earth Sciences, Geophysics Keywords: Coastal storm; Wind wave; Storm surge; Extreme coastal water level; Boulder dynamics; Geomorphological proxy; Interdisciplinary climate research
Online: 17 May 2022 (10:28:58 CEST)
In this review, the potential of an emerging field of interdisciplinary climate research, that is the Coastal Boulder Deposits (CBDs) as natural archives for intense storms, is explored with particular reference to the Mediterranean region. First, the identification of the pertinent scientific articles was performed by using Web of Science (WoS) engine. Thus, the selected studies have been analysed to feature CBDs produced and/or activated during the last half century. Then, the meteorological events responsible to the literature reported cases were analysed in some details using the web archives of the Globo-Bolam-Moloch model cascade. The study of synoptical and local characteristics of the storms involved in the documented cases of boulder production/activation proved useful to assess the suitability of selected sites as geomorphological storm proxies. It is argued that a close and fruitful collaboration involving several scientific disciplines is required to develop this climate research field.
ARTICLE | doi:10.20944/preprints201808.0406.v1
Subject: Earth Sciences, Geology Keywords: hurricane storm surge; hurricane rainfall; wave hydrodynamics; Gulf of California (Mexico); Isla del Carmen; Loreto (Baja California Sur)
Online: 23 August 2018 (05:35:32 CEST)
This study reports the first example of major erosion from hurricanes degrading a rocky coastline anywhere around the Gulf of California, although other sources of evidence are well known regarding the effect of inland erosion due to catastrophic rainfall in the Southern Cape Region of the Baja California peninsula and farther north. The uplifted, 12-meter terrace on the eastern shore of Isla del Carmen is the site of an unconsolidated coastal boulder deposit (CBD) consisting of large limestone blocks and boulders eroded from underlying Pliocene strata. The CBD stretches approximately 1.5 km in length, mostly set back 25 m from the lip of the terrace. The largest blocks of upturned limestone near the terrace edge are estimated to weigh between 5.8 and 28 metric tons. Waves impacting the rocky coast that peeled back slabs of horizontally layered limestone at this spot are calculated to have been between 11.5 and 14 m in height. Analysis of sampled boulders from the CBD set back from the terrace edge by 25 m suggest that the average wave height responsible for moving those boulders was on the order of 4.3 m. Additional localities with exposed limestone shores, as well as other more common rock types of igneous origin, have yet to be surveyed for this phenomenon elsewhere around the Gulf of California.
ARTICLE | doi:10.20944/preprints201702.0107.v1
Subject: Engineering, Other Keywords: maximum storm tide; two-dimensional tide-surge modeling system; east coast of Taiwan; intensity of typhoon; bathymetric rise
Online: 28 February 2017 (13:00:56 CET)
A typhoon-induced storm surge is considered one of the most severe coastal disasters in Taiwan. However, the combination of the storm surge and the astronomical tide called the storm tide can actually cause extreme flooding in coastal areas. This study implemented a two-dimensional hydrodynamic model to account for the interaction between tides and storm surges on the coast of Taiwan. The model was validated with observed water levels at Sauo Fish Port, Hualien Port, and Chenggong Fish Port under different historical typhoon events. The model results are in reasonable agreement with the measured data. The validated model was then used to evaluate the effects of the typhoon's intensity, bathymetric change, and the combination of the typhoon’s intensity and bathymetric change on the maximum storm tide and its distribution along the east coast of Taiwan. The results indicated that the maximum storm tide rises to 1.92 m under a typhoon with an intensity of a 100-year return period. The maximum storm tide increased from a baseline of 1.26 m to 2.63 m for a 90% bathymetric rise at Sauo Fish Port under the conditions of Typhoon Jangmi (2008). The combination of the intensity of a typhoon with a 100-year return period and a 90% bathymetric rise will result in a maximum storm tide exceeding 4 m, 2 m, and 3 m at Sauo Fish Port, Hualien Port, and Chenggong Fish Port, respectively. We also found that the distribution of the maximum storm tide on the east coast of Taiwan can expand significantly subject to the bathymetric rise.
ARTICLE | doi:10.20944/preprints202110.0122.v2
Subject: Earth Sciences, Geophysics Keywords: ICESat-2; Laser Altimetry; Kinematic GPS Experiments; Glaciology; Surge Glaciers; Svalbard; Density Dimension Algorithm for Ice Surfaces; Airborne Validation of Satellite Data
Online: 13 October 2021 (10:45:21 CEST)
The topic of this paper is the airborne evaluation of ICESat-2 Advanced Topographic Laser Altimeter System (ATLAS) measurement capabilities and surface-height-determination over crevassed glacial terrain, with a focus on the geodetical accuracy of geophysical data collected from a helicopter. To obtain surface heights over crevassed and otherwise complex ice surface, ICESat-2 data are analyzed using the density-dimension algorithm for ice surfaces (DDA-ice), which yields surface heights at the nominal 0.7~m along-track spacing of ATLAS data. As the result of an ongoing surge, Negribreen, Svalbard, provided an ideal situation for the validation objectives in 2018 and 2019, because many different crevasse types and morphologically complex ice surfaces existed in close proximity. Airborne geophysical data, including laser altimeter data (profilometer data at 905~nm frequency), differential Global Positioning System (GPS), Inertial Measurement Unit (IMU) data, on-board-time-lapse imagery and photographs, were collected during two campaigns in summers of 2018 and 2019. Airborne experiment setup, geodetical correction and data processing steps are described here. To date, there is relatively little knowledge of the geodetical accuracy that can be obtained from kinematic data collection from a helicopter. Our study finds that (1)~Kinematic GPS data collection with correction in post-processing yields higher accuracies than Real-Time-Kinematic (RTK) data collection. (2)~Processing of only the rover data using the Natural Resources Canada Spatial Reference System Precise Point Positioning (CSRS-PPP) software is sufficiently accurate for the sub-satellite validation purpose. (3)~Distances between ICESat-2 ground tracks and airborne ground tracks were generally better than 25~m, while distance between predicted and actual ICESat-2 ground track was on the order of 9~m, which allows direct comparison of ice-surface heights and spatial statistical characteristics of crevasses from the satellite and airborne measurements. (4)~The Lasertech Universal Laser System (ULS), operated at up to 300~m above ground level, yields full return frequency (400~Hz) and 0.06-0.08~m on-ice along-track spacing of height measurements. (5)~Cross-over differences of airborne laser altimeter data are 0.1918 $\pm$ 2.385~m along straight paths over generally crevassed terrain, which implies a precision of approximately 2.4~m for ICESat-2 validation experiments. (6)~In summary, the comparatively light-weight experiment setup of a suite of small survey equipment mounted on a Eurocopter (Helicopter AS-350) and kinematic GPS data analyzed in post-processing using CSRS-PPP leads to high accuracy repeats of the ICESat-2 tracks. The technical results (1)-(6) indicate that direct comparison of ice-surface heights and crevasse depths from the ICESat-2 and airborne laser altimeter data is warranted. The final result of the validation is that ICESat-2 ATLAS data, analyzed with the DDA-ice, facilitate surface-height determination over crevassed terrain, in good agreement with airborne data, including spatial characteristics, such as surface roughness, crevasse spacing and depth, which are key informants on the deformation and dynamics of a glacier during surge.