Formação de ondas e os processos erosivos nas margens do lago da UHE Xingó

As características dos ventos têm uma grande influência no modo como as ondas são geradas, se propagam e promovem erosão nas margens de rios e lagos. Entre essas características, a velocidade e a direção do vento assumem um papel crucial, influenciando os principais parâmetros que caracterizam as ondas, designadamente a altura de onda e o período (tempo de duração). Esse trabalho teve como objetivo caracterizar a geração de ondas no Lago da UHE Xingó e as consequências nos processos erosivos na sua margem. Foram levantados dados in situ e das fontes disponíveis no SIMA - Sistema Integrado de Monitoração Ambiental. A coleta de dados de vento in loco foi realizada a partir da utilização de um anemômetro instalado em períodos determinados, em pontos diferentes da margem do lago, para que permitisse a comparação com os dados pretéritos coletados pelo SIMA. Os focos de erosão reconhecidos na extensão das pistas de vento, foram georeferenciados sendo realizada a sua associação com a direção dominante dos ventos, que promovem a consequente formação de ondas. Percebeu-se ventos diurnos maiores que os noturnos nos períodos mais secos, e também o desenvolvimento de ondas acompanhando essa tendência, ou seja, menores à noite do que no dia. Foram identificados 8 (oito) fetchs representativos dos ventos dominantes no Lago da UHE Xingó, todos com forte relação com os focos de erosão identificados, e percebeu-se pouca variação nos valores máximos de ondas em todas as pistas de vento, não ultrapassando o valor de 0,16m, ocorrente no período diurno. Wave formation and erosive processes in the margins of Lake XingóA B S T R A C TThe characteristics of the winds have a great influence in the way the waves are generated, they propagate and they promote erosion in the riverbanks and lakes. Among these characteristics, wind speed and direction play an important role, influencing the main parameters that characterize waves, namely wave height and period (duration time). The objective of this work was to characterize the generation of waves in the Xingó Power Dam and the consequences on the erosive processes. Data were collected in situ and compiled from the available sources in the SIMA - Integrated Environmental Monitoring System. Wind data collection was carried out using an anemometer installed at specific periods of the year, at different points in the lake margin, to allow the comparison with previous data collected by SIMA. The erosion recognized in the extension of the fetchs were georeferenced, and their association with the dominant direction of the winds was carried out, which promote the consequent formation of waves. Higher daytime winds were observed than the nocturnal ones in drier periods, and also the development of waves accompanying this trend, that is, smaller at night than in the daytime. Eight (8) representative fetchs of the prevailing winds in the Xingó Power Dam were identified, all of them strongly related to the identified erosion spots, and with few variation in the maximum wave heights values for all identified values not exceeding the value of 0.16m and in the daytime period.Keywords: Wind speed, fetch; São Francisco River; erosion.

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Wind speed data analysis for predictions of sea waves in Bitung Coastal Waters

AQUATIC SCIENCE & MANAGEMENT ◽

10.35800/jasm.0.0.2013.2274 ◽

2013 ◽

pp. 35 ◽

Cited By ~ 1

Author(s):

Joanes E Koagouw ◽

Gybert E Mamuaya ◽

Adrie A Tarumingkeng ◽

P A Angmalisang

Keyword(s):

Data Analysis ◽

Wind Speed ◽

Coastal Waters ◽

Transition Period ◽

Marine Resources ◽

Land Uses ◽

Sea Waves ◽

North West ◽

North Sulawesi ◽

The Waves

Coastal area of Bitung Municipality is one of the economical activities centers in North Sulawesi Province such as for land-uses and the exploitation of natural resources. Those activities are exaggerating day bay day and tended to be uncontrollable. The excess of those conditions, it has been recorded the change of waves in Bitung waters that has impacts to coastal areas and can affect the utilization of coastal and marine resources. This research was aimed to observe waves altitude variations in Bitung waters with Svedrup Munk and Bretchsneider (SMB) method that had been used to predict waves altitudes. The results showed that the wind speed during West Season was 0.33 m and were dominant to the East, while during East season was 0.91m from South-East to North-West, and then on transition period (March to May) was 1.08m from South-East to East. The results of those wind speed to the waves altitudes in Bitung waters is discussed in this paper© Pesisir pantai Kota Bitung merupakan salah satu pusat aktivitas ekonomi (misalnya pemanfaatan lahan dan eksploitasi sumberdaya) di Provinsi Sulawesi Utara. Aktivitas tersebut semakin hari semakin meningkat dan memiliki kecenderungan tidak terkontrol. Akibat dari keadaan tersebut, telah terjadi perubahan fenomena gelombang di perairan Bitung yang berdampak pada keberadaan daerah pesisir pantai di mana hal ini dapat mengganggu aktivitas pemanfaatan sumberdaya pesisir dan laut tersebut. Penelitian ini bertujuan untuk mengetahui variasi tinggi gelombang di perairan Bitung dengan menggunakan metode Svedrup Munk and Bretchsneider (SMB) yang biasa digunakan untuk peramalan tinggi gelombang signifikan. Hasil penelitian menunjukkan bahwa kecepatan angin pada Musim Barat sebesar 0,33 meter dan dominan ke arah Timur, sementara pada Musim Timur sebesar 0,91 meter dari arah Tenggara ke Barat Laut, serta pada Musim Peralihan (antara bulan Maret-Mei) adalah sebesar 1,08 meter dari arah Tenggara dan Timur. Pengaruh kecepatan angin tersebut terhadap gelombang laut di perairan Bitung dibahas dalam tulisan ini©

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Simultaneously controlling heat conduction and infrared absorption with a textured dielectric film to enhance the performance of thermopiles

Microsystems & Nanoengineering ◽

10.1038/s41378-021-00264-z ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Yunqian He ◽

Yuelin Wang ◽

Tie Li

Keyword(s):

Heat Conduction ◽

Infrared Absorption ◽

High Performance ◽

Performance Enhancement ◽

Dielectric Film ◽

Great Influence ◽

Thermal Conductance ◽

Molding Process ◽

Absorption Properties

AbstractThe heat conduction and infrared absorption properties of the dielectric film have a great influence on the thermopile performance. Thinning the dielectric film, reducing its contact area with the silicon substrate, or adding high-absorptivity nanomaterials has been proven to be effective in improving thermopiles. However, these methods may result in a decrease in the structural mechanical strength and increases in the fabrication complexity and cost. In this work, a new performance-enhancement strategy for thermopiles by simultaneously controlling the heat conduction and infrared absorption with a TExtured DIelectric (TEDI) film is developed and presented. The TEDI film is formed in situ by a simple hard-molding process that is compatible with the fabrication of traditional thermopiles. Compared to the control FLat DIelectric (FLDI) film, the intrinsic thermal conductance of the TEDI film can be reduced by ~18–30%, while the infrared absorption can be increased by ~7–13%. Correspondingly, the responsivity and detectivity of the fabricated TEDI film-based thermopile can be significantly enhanced by ~38–64%. An optimized TEDI film-based thermopile has achieved a responsivity of 156.89 V·W−1 and a detectivity of 2.16 × 108 cm·Hz1/2·W−1, while the response time constant can remain <12 ms. These results exhibit the great potential of using this strategy to develop high-performance thermopiles and enhance other sensors with heat transfer and/or infrared absorption mechanisms.

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Magnetised Wave Collapse in Solar System Plasmas

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000025881 ◽

1993 ◽

Vol 10 (4) ◽

pp. 283-286 ◽

Cited By ~ 2

Author(s):

Andrew Melatos ◽

Peter Robinson

Keyword(s):

Solar System ◽

Wave Packets ◽

Particle Interactions ◽

Coherent Wave ◽

Wave Collapse ◽

Non Linear ◽

Acceleration Zone ◽

The Waves ◽

Linear Plasma

AbstractClumpy, intense wave packets observed in situ in the Jovian and terrestrial electron foreshocks, and in the Earth’s auroral acceleration zone, point to the existence of non-linear plasma turbulence in these regions. In non-linear turbulence, wave packets collapse to short scales and high fields, stopping only when coherent wave-particle interactions efficiently dissipate the energy in the waves. The purpose of this paper is to examine the shortest scales and highest fields achieved during collapse in a strongly magnetised plasma, and identify parts of the solar system where the magnetised aspects of wave collapse are important.

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Terrestrial aurora: astrophysical laboratory for anomalous abundances in stellar systems

Annales Geophysicae ◽

10.5194/angeo-32-77-2014 ◽

2014 ◽

Vol 32 (2) ◽

pp. 77-82 ◽

Cited By ~ 1

Author(s):

I. Roth

Keyword(s):

Solar Flares ◽

Heavy Ions ◽

Electromagnetic Waves ◽

Stellar System ◽

Decay Product ◽

Early Solar System ◽

Physical Processes ◽

In Situ Observations ◽

The Waves

Abstract. The unique magnetic structure of the terrestrial aurora as a conduit of information between the ionosphere and magnetosphere can be utilized as a laboratory for physical processes at similar magnetic configurations and applied to various evolutionary phases of the solar (stellar) system. The most spectacular heliospheric abundance enhancement involves the 3He isotope and selective heavy elements in impulsive solar flares. In situ observations of electromagnetic waves on active aurora are extrapolated to flaring corona in an analysis of solar acceleration processes of 3He, the only element that may resonate strongly with the waves, as well as heavy ions with specific charge-to-mass ratios, which may resonate weaker via their higher gyroharmonics. These results are applied to two observed anomalous astrophysical abundances: (1) enhanced abundance of 3He and possibly 13C in the late stellar evolutionary stages of planetary nebulae; and (2) enhanced abundance of the observed fossil element 26Mg in meteorites as a decay product of radioactive 26Al isotope due to interaction with the flare-energized 3He in the early solar system.

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MACH-REFLECTION AS A DIFFRACTION PROBLEM

Coastal Engineering Proceedings ◽

10.9753/icce.v15.45 ◽

1976 ◽

Vol 1 (15) ◽

pp. 45 ◽

Cited By ~ 2

Author(s):

Udo Berger ◽

Soren Kohlhase

Keyword(s):

Wave Height ◽

Incident Wave ◽

Water Waves ◽

Gas Dynamics ◽

Mach Reflection ◽

Diffraction Problem ◽

Vertical Wall ◽

Oblique Wave ◽

Wave Heights ◽

The Waves

As under oblique wave approach water waves are reflected by a vertical wall, a wave branching effect (stem) develops normal to the reflecting wall. The waves progressing along the wall will steep up. The wave heights increase up to more than twice the incident wave height. The £jtudy has pointed out that this effect, which is usually called MACH-REFLECTION, is not to be taken as an analogy to gas dynamics, but should be interpreted as a diffraction problem.

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Effects of calcium phosphates incorporation on structural, thermal and drug-delivery properties of collagen:chitosan scaffolds

International Journal of Advances in Medical Biotechnology - IJAMB ◽

10.25061/2595-3931/ijamb/2019.v2i2.32 ◽

2020 ◽

Vol 2 (2) ◽

Author(s):

Mirella Romanelli Vicente Bertolo ◽

Virginia Conceição Amaro Martins ◽

Ana Maria De Guzzi Plepis

Keyword(s):

Drug Delivery ◽

Calcium Phosphate ◽

Calcium Phosphates ◽

Great Influence ◽

Collagen Gel ◽

Dry Mass ◽

Ex Situ ◽

Porous Scaffolds ◽

Drug Delivery Vehicles

In this study, we evaluated how different procedures of calcium phosphate synthesis and its incorporation in collagen:chitosan scaffolds could affect their structural and thermal properties, aiming the obtention of homogeneous scaffolds which can act as drug delivery vehicles in bone tissue engineering. Therefore, three different scaffold preparation procedures were developed, changing the order of addition of the components: in CC-CNPM1 and CC-CNPM2, calcium phosphate synthesis was performed in situ in the chitosan gel (1%, w/w) followed by mixture with collagen (1%, w/w), with changes in the reagents used for calcium phosphate formation; in CC-CNPM3 procedure, calcium phosphate was synthesized ex situ and then incorporated into the collagen gel, in which chitosan in powder was mixed. In all procedures, 5% (in dry mass) of ciprofloxacin was incorporated. FTIR analysis confirmed the presence of calcium phosphate in all scaffolds. DSC curves showed that collagen denaturation temperature (Td) increased with calcium incorporation. SEM photomicrographs of scaffolds cross-section revealed porous scaffolds with calcium phosphate grains internally distributed in the polymeric matrix. XRD diffractograms indicated that the calcium phosphates obtained are hydroxyapatite. The pore size distribution was more homogeneous for CC-CNPM3, which also stood out for its smaller porosity and lower absorption in PBS. These results indicate that the in situ or ex situ phosphate incorporation in the scaffolds had a great influence on its structural properties, which also had consequences for ciprofloxacin release. CC-CNPM3 released a smaller amount of antibiotic (30%), but its release profile was better described by all the tested models.

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WAVE RECORDING ON THE IJSSELMEER

Coastal Engineering Proceedings ◽

10.9753/icce.v7.3 ◽

2011 ◽

Vol 1 (7) ◽

pp. 3

Author(s):

P. W. Roest

Keyword(s):

Average Period ◽

Recording Time ◽

Ice Drift ◽

Recording Station ◽

Long Time ◽

Wave Heights ◽

Wave Research ◽

The Difference ◽

Hydraulics Laboratory ◽

The Waves

The dimensions of the dikes in the Ijsselmeer are mainly determined by wave-attack. The dimensions of the waves as a result of the design gale are calculated with the diagram of the Hydraulics Laboratory at Delft (ref« 1). This diagram is based on data of Sverdrup for deep water and principally on laboratory studies for shallow water. For a long time there has been a need of wave recordings on the lake in order to verify the calculated wave heights. A problem is the impossibility of maintaining a permanent recording station on the lake due to ice-drift in wintertime. Otherwise the Ijsselmeer lends itself admirably to wave-research, because there are vast regions with only small variations in waterdepth. Another advantage is that frequently more or less stationary conditions will occur under the influence of winds of constant force and direction. When Dr. Dorrestein of the Royal Dutch Meteorological Institute introduced his new floating waverecorder, it was possible to take observations in every place of the lake. Soon it appeared that this recorder has many advantages. The equipment consists of an accelerometer mounted on a little raft of one meter each way, that follows the movement of the water surface. The signal of the accelerometer is transmitted by an electric cable to the ship, where it is double integrated and then recorded (ref. 3). During the last winter several observations have been carried out with an instrument of this type* As a result of initial troubles with the electronic equipment the number of observations during gale-conditions has been limited. The usual duration of each recording is about 15 minutes. The average period of the waves lies between three and a half and five seconds, so each diagram consists of 180 to 250 waves. Wave height is measured as the difference in height between a trough and the next crest. The average period is determined by dividing the total recording time by half the number of zerocrossings.

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Development of an in situ Acoustic Anemometer to Measure Wind in the Stratosphere for SENSOR

10.5194/amt-2021-76 ◽

2021 ◽

Author(s):

Song Liang ◽

Hu Xiong ◽

Wei Feng ◽

Yan Zhaoai ◽

Xu Qingchen ◽

...

Keyword(s):

Wind Speed ◽

Meridional Wind ◽

Floating Platform ◽

Level Flight ◽

Subsequent Publication ◽

Wind Measurements ◽

Commercial Off The Shelf ◽

Solar Storms ◽

Acoustic Anemometer

Abstract. The Stratospheric Environmental respoNses to Solar stORms (SENSOR) campaign investigates the influence of solar storms on the stratosphere. This campaign employs a long-duration zero-pressure balloon as a platform to carry multiple types of payloads during a series of flight experiments in the mid-latitude stratosphere from 2019 to 2022. This article describes the development and testing of an acoustic anemometer for obtaining in situ wind measurements along the balloon trajectory. Developing this anemometer was necessary, as there is no existing commercial off-the-shelf product, to the authors' knowledge, capable of obtaining in situ wind measurements on a high-altitude balloon or other similar floating platform in the stratosphere. The anemometer is also equipped with temperature, pressure, and humidity sensors from a Temperature-Pressure-Humidity measurement module, inherited from a radiosonde developed for sounding balloons. The acoustic anemometer and other sensors were used in a flight experiment of the SENSOR campaign that took place in the Da chaidan District (95.37° E, 37.74° N) on 4 September 2019. The zonal and meridional wind speed observations, which were obtained during level flight at an altitude exceeding 20 km, are presented. This is the first time that in situ wind measurements were obtained during level flight at this altitude. In addition to wind speed measurements, temperature, pressure, and relative humidity measurements during ascent are compared to observations from a nearby radiosonde launched four hours earlier. Further analysis of the wind data will presented in a subsequent publication. The problems experienced by the acoustic anemometer during the 2019 experiment show that the acoustic anemometer must be improved for future experiments in the SENSOR campaign.

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Modelling rain heterogeneities within an urban neighbourhood

10.5194/egusphere-egu21-7806 ◽

2021 ◽

Author(s):

Karolin S. Ferner ◽

K. Heinke Schlünzen ◽

Marita Boettcher

Keyword(s):

Wind Speed ◽

Urban Areas ◽

Climate Model ◽

Numerical Models ◽

Urban Climate ◽

Cloud Microphysics ◽

In Situ Measurements ◽

Small Scale ◽

Atmospheric Processes

Urbanisation locally modifies the regional climate: an urban climate develops. For example, the average wind speed in cities is reduced, while the gustiness is increased. Buildings induce vertical winds, which influence the falling of rain. All these processes lead to heterogeneous patterns of rain at ground and on building surfaces. The small-scale spatial rain heterogeneities may cause discomfort for people. Moreover, non-uniform wetting of buildings affects their hydrothermal performance and durability of their facades.Measuring rain heterogeneities between buildings is, however, nearly impossible. Building induced wind gusts negatively influence the representativeness of in-situ measurements, especially in densely urbanised areas. Weather radars are usually too coarse and, more importantly, require an unobstructed view over the domain and thus do not measure ground precipitation in urban areas. Consequently, researchers turn to numerical modelling in order to investigate small-scale precipitation heterogeneities between buildings.In building science, numerical models are used to investigate rain heterogeneities typically focussing on single buildings and vertical facades. Only few studies were performed for more than a single building or with inclusion of atmospheric processes such as radiation or condensation. In meteorology, increasing computational power now allows the use of small-scale obstacle-resolving models resolving atmospheric processes while covering neighbourhoods.In order to assess rain heterogeneities between buildings we extended the micro-scale and obstacle-resolving transport- and stream model MITRAS (Salim et al. 2019). The same cloud microphysics parameterisation as in its mesoscale sister model METRAS (Schl&#252;nzen et al., 2018) was applied and boundary conditions for cloud and rain water content at obstacle surfaces were introduced. MITRAS results are checked for plausibility using radar and in-situ measurements (Ferner et al., 2021). To our knowledge MITRAS is the first numerical urban climate model that includes rain and simulates corresponding processes.Model simulations were initialised for various wind speeds and mesoscale rain rates to assess their influence on the heterogeneity of falling rain in a domain of 1.9 x 1.7 km&#178; around Hamburg City Hall. We investigated how wind speed or mesoscale rain rate influence the precipitation patterns at ground and at roof level. Based on these results we assessed the height dependence of precipitation. First analyses show that higher buildings receive more rain on their roofs than lower buildings; the results will be presented in detail in our talk.Ferner, K.S., Boettcher, M., Schl&#252;nzen, K.H. (2021): Modelling the heterogeneity of rain in an urban neighbourhood. Publication in preparationSalim, M.H., Schl&#252;nzen, K.H., Grawe, D., Boettcher, M., Gierisch, A.M.U., Fock B.H. (2018): The microscale obstacle-resolving meteorological model MITRAS v2.0: model theory. Geosci. Model Dev., 11, 3427&#8211;3445, https://doi.org/10.5194/gmd-11-3427-2018.Schl&#252;nzen, K.H., Boettcher, M., Fock, B.H., Gierisch, A.M.U., Grawe, D., and Salim, M. (2018): Scientific Documentation of the Multiscale Model System M-SYS. Meteorological Institute, Universit&#228;t Hamburg. MEMI Technical Report 4

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In Situ Shear-Wave Velocity Assessment at the Delaney Park Downhole Array, Anchorage, Alaska

Seismological Research Letters ◽

10.1785/0220200097 ◽

2020 ◽

Vol 91 (6) ◽

pp. 3381-3390

Author(s):

Hai-Yun Wang ◽

Wei-Ping Jiang

Keyword(s):

Shear Wave ◽

Wave Velocity ◽

Shear Wave Velocity ◽

Great Influence ◽

Standard Penetration Test ◽

Weak Anisotropy ◽

Near Surface ◽

Motion Data ◽

Downhole Array

Abstract The shear-wave velocity (VS) in soil is an important parameter to characterize dynamic soil properties. The Delaney Park downhole array was deployed in 2003 without measuring the shear- and compression-wave velocity (VS and VP) profiles. Thornley et al. (2019) measured the VS and VP profiles using the downhole method after the sensor was removed from the 61 m borehole with casing in the array. However, the waves propagating along the casing wall may have a great influence on the recognition of the first arrival of waves propagating in the soil. Using horizontal and vertical components of weak-motion data of eight local earthquakes recorded by the array, in situ VS and VP profiles were assessed by the seismic interferometry based on deconvolution, respectively. The results are as follows. The VS and VP profiles computed by this study and measured by Thornley et al. (2019) are in relatively good agreement at a depth of 10–45 m and at a depth of 30–45 m, respectively, and in very poor agreement at other depths. The average VS profiles computed by this study are more consistent with the derived VS from the standard penetration test data at the site with slower near-surface velocities relative to the downhole logging analysis. There are strong anisotropy in the strata below 45 m and weak anisotropy with various degrees at various depths in the strata above 45 m.

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