scholarly journals SEISMOGRAF REFRAKSI DENGAN SUMBER GELOMBANG WEIGH DROP

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Muhammad Zuhdi
Keyword(s):  
Short Distance ◽  
Arrival Time ◽  
Horizontal Distance ◽  
Long Distance ◽  
Incoming Wave ◽  
Wave Source ◽  
Direct Wave ◽  
Ground Source ◽  
First Arrival ◽  
Wave Arrival

Abstrak : Telah dibuat seimograf refraksi dengan sumber gelombang weigh drop berupa bola besi yang dijatuhkan 2 meter dari landasan. Sumber gelombang ini mampu memberikan sinyal pada geophone hingga jarak 150meter. Prinsip kerja seismograf refraksi adalah mengukur waktu tiba gelombang tercepat (fisrt arrival time) dari sumber menuju geophone. Untuk jarak pendek, gelombang tercepat adalah gelombang langsung, sedangkan untuk jarak selebihnya gelombang tercepat adalah gelombang refraksi. Waktu tiba gelombang tercepat diukur dengan instrumen elektronik dengan ketelitian hingga 0,1 milli sekon. Hasil ujicoba menunjukkan bahwa seismogram mampu mendeteksi perlapisan hingga kedalaman 5 meter dengan jarak horizontal mencapai 150 meter.Kata kunci : Seismograf, refraksi, weigh dropAbstract : Refraction seismograph is have been made with wave source of weigh drop made of iron ball from altitude 2 metre from the ground. Source of this wave can give geophone signal till 150 metre apart. Principal ofrefraction seismograph is to measure first arrival of incoming wave to geophone. For short distance, first arrival wave is direct wave, while for the medium and long distance first arrival wave is refraction wave. Arrival time is measured with electronic instrument with errors till 0,1 millisecond. Result of instrument trial indicate that seismogram can detect some layers till 5 metre deep with horizontal distance till 150 metre.Key words : Seismograph, refraction, weigh drop

scholarly journals No general shift in spring migration phenology by eastern North American birds since 1970

2021 ◽  
Author(s):  
André Desrochers ◽  
Andra Florea ◽  
Pierre-Alexandre Dumas
Keyword(s):  
Short Distance ◽  
Species Abundance ◽  
Open Water ◽  
Early Spring ◽  
Spring Migration ◽  
The Arctic ◽  
Long Distance ◽  
Arrival Dates ◽  
Migration Phenology ◽  
First Arrival

We studied the phenology of spring bird migration from eBird and ÉPOQ checklist programs South of 49°N in the province of Quebec, Canada, between 1970 and 2020. 152 species were grouped into Arctic, long-distance, and short-distance migrants. Among those species, 75 significantly changed their migration dates, after accounting for temporal variability in observation effort, species abundance, and latitude. But in contrast to most studies on the subject, we found no general advance in spring migration dates, with 36 species advancing and 39 species delaying their migration. Several early-migrant species associated to open water advanced their spring migration, possibly due to decreasing early-spring ice cover in the Great Lakes and the St-Lawrence river since 1970. Arctic breeders and short-distance migrants advanced their first arrival dates more than long-distance migrants not breeding in the arctic. However, there was no difference among migrant groups when median arrival dates were considered. We conclude that general claims about advances in spring migration dates in eastern North America are misleading due to large taxonomic variation.

scholarly journals K → μ+μ− as a clean probe of short-distance physics

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Avital Dery ◽  
Mitrajyoti Ghosh ◽  
Yuval Grossman ◽  
Stefan Schacht
Keyword(s):  
Matrix Element ◽  
Standard Model ◽  
Short Distance ◽  
Time Dependent ◽  
Final States ◽  
Interference Effects ◽  
Fundamental Theory ◽  
Long Distance ◽  
Ckm Matrix ◽  
The Standard Model

Abstract The K → μ+μ− decay is often considered to be uninformative of fundamental theory parameters since the decay is polluted by long-distance hadronic effects. We demonstrate that, using very mild assumptions and utilizing time-dependent interference effects, ℬ(KS → μ+μ−)ℓ=0 can be experimentally determined without the need to separate the ℓ = 0 and ℓ = 1 final states. This quantity is very clean theoretically and can be used to test the Standard Model. In particular, it can be used to extract the CKM matrix element combination $$ \mid {V}_{ts}{V}_{td}\sin \left(\beta +{\beta}_s\right)\mid \approx \mid {A}^2{\lambda}^5\overline{\eta}\mid $$ ∣ V ts V td sin β + β s ∣ ≈ ∣ A 2 λ 5 η ¯ ∣ with hadronic uncertainties below 1%.

First arrival time picking for microseismic data based on DWSW algorithm

2018 ◽  
Vol 22 (4) ◽  
pp. 833-840 ◽  
Author(s):  
Yue Li ◽  
Yue Wang ◽  
Hongbo Lin ◽  
Tie Zhong
Keyword(s):  
Arrival Time ◽  
Microseismic Data ◽  
First Arrival ◽  
First Arrival Time ◽  
Arrival Time Picking

Errors Introduced in Estimation of Surface Wave Phase and Group Velocities Due to Wrong Assumptions: An Assessment Using a Simple Model For Love Wave

2021 ◽  
Author(s):  
Akash Kharita ◽  
Sagarika Mukhopadhyay
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Love Wave ◽  
Arrival Time ◽  
Epicentral Distance ◽  
Horizontal Distance ◽  
Wave Analysis ◽  
Time Period ◽  
Phase And Group Velocities ◽  
Group Velocities

<p>The surface wave phase and group velocities are estimated by dividing the epicentral distance by phase and group travel times respectively in all the available methods, this is based on the assumptions that (1) surface waves originate at the epicentre and (2) the travel time of the particular group or phase of the surface wave is equal to its arrival time to the station minus the origin time of the causative earthquake; However, both assumptions are wrong since surface waves generate at some horizontal distance away from the epicentre. We calculated the actual horizontal distance from the focus at which they generate and assessed the errors caused in the estimation of group and phase velocities by the aforementioned assumptions in a simple isotropic single layered homogeneous half space crustal model using the example of the fundamental mode Love wave. We took the receiver locations in the epicentral distance range of 100-1000 km, as used in the regional surface wave analysis, varied the source depth from 0 to 35 Km with a step size of 5 km and did the forward modelling to calculate the arrival time of Love wave phases at each receiver location. The phase and group velocities are then estimated using the above assumptions and are compared with the actual values of the velocities given by Love wave dispersion equation. We observed that the velocities are underestimated and the errors are found to be; decreasing linearly with focal depth, decreasing inversely with the epicentral distance and increasing parabolically with the time period. We also derived empirical formulas using MATLAB curve fitting toolbox that will give percentage errors for any realistic combination of epicentral distance, time period and depths of earthquake and thickness of layer in this model. The errors are found to be more than 5% for all epicentral distances lesser than 500 km, for all focal depths and time periods indicating that it is not safe to do regional surface wave analysis for epicentral distances lesser than 500 km without incurring significant errors. To the best of our knowledge, the study is first of its kind in assessing such errors.</p>

scholarly journals APLIKASI PENGINDERAAN JAUH DAN SISTEM INFORMASI GEOGRAFI UNTUK PEMETAAN DAERAH BERPOTENSI TSUNAMI DI KABUPATEN KUPANG PROVINSI NUSA TENGGARA TIMUR

2018 ◽  
Vol 3 (2) ◽  
pp. 170-178
Author(s):  
Lidia Agustina Rumaal ◽  
Jehunias L. Tanesib ◽  
Jonshon Tarigan
Keyword(s):  
Remote Sensing ◽  
Information System ◽  
Geographic Information System ◽  
Population Density ◽  
Land Cover ◽  
Arrival Time ◽  
Land Cover Map ◽  
The Impact ◽  
Monitoring Area ◽  
Wave Arrival

Abstrak Telah dilakukan pemetaan daerah rawan tsunami berdasarkan estimasi waktu tiba gelombang dan tutupan lahan di Kabupaten Kupang Provinsi Nusa Tenggara Timur menggunakan aplikasi Penginderaan Jauh dan Sistem Informasi Geografi. Penelitian ini bertujuan untuk mengidentifikasi, memetakan daerah rawan tsunami dan tingkat kerawanannya menurut estimasi waktu tiba gelombang dan tutupan lahan sebagai upaya mitigasi dampak bencana tsunami terhadap kepadatan penduduk. Metode penelitian secara umum dibagi dalam empat tahap utama yaitu pembangunan basis data berupa pembuatan peta tutupan lahan, peta gempa dan peta batimetri. Analisis data kerawanan dari peta tutupan lahan dan etimasi waktu tiba gelombang, penyajian hasil data dalam bentuk tingkat kerawanan masing-masing peta dan analisis hasil penelitian berupa tingkat kerawanan secara kualitatif masing-masing daerah titik pantau menurut peta tutupan lahan maupun estimasi waktu tiba gelombang. Selain itu, dampak kerawanan tsunami diklasifikasikan menurut tingkat kepadatan penduduk untuk kebutuhan mitigasi sebagai berikut Kecamatan Kupang Timur, Kupang Barat, Sulamu, Amfoang Timur, Semau, Semau Selatan, Amfoang Utara, Amfoang Barat Daya, Amfoang Barat Laut dan Fatuleu Barat. Kata kunci : Peta rawan tsunami, Penginderaan Jauh, Sistem Informasi Geografi, Estimasi Waktu Tiba Gelombang  Abstract Mapping of hazard tsunami areas based on estimation of arrival time of wave and land cover in Kupang Regency of East Nusa Tenggara Province using remote sensing application and geographic information system has been done. The  aims of this research are to mapping the hazard tsunami area and tsunami vulnerability level in Kupang Regency East Nusa Tenggara according to the estimated arrival time of the wave and land cover as an effort to mitigate the impact of the tsunami disaster on population density. These generally devided into four main phase namely development of database in the form of land cover map , seismic maps and bathymetry maps, data analysis of research results in the form of qualitative vulnerability of each monitoring area according to land cover map and estimated wave arrival time. Presentation of data results in the form of vulnerability level of each map and analysis and results analysis of research the form of vulnerability level of each map and analysis of research results in the form of qualitative vulnerability of each monitoring area according to land cover map and estimated wave arrival time. And then, the impact of tsunami vulnerability is classified according to population density levels for mitigation needs as follows Kupang Timur, Kupang Barat, Sulamu, Amfoang Timur, Semau, Semau Selatan, Amfoang Utara, Amfoang Barat Daya, Amfoang Barat Laut and Fatuleu Barat. Keywords: Tsunami Hazard Map, Remote Sensing, Geographic Information System, Estimated Time of arrival Wave

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