Aeromagnetic survey in Kusatsu-Shirane volcano, central Japan, by using an unmanned helicopter

Kusatsu-Shirane volcano is one of the active volcanoes in Japan. Phreatic explosions occurred in Mt. Shirane in 1983 and most recently, in 2018, in Mt. Motoshirane. Information on the subsurface structure is crucial for understanding the activity of volcanoes with well-developed hydrothermal systems where phreatic eruptions occur. Here, we report aeromagnetic surveys conducted at low altitudes using an unmanned helicopter. The survey aimed to obtain magnetic data at a high spatial resolution to map the magnetic anomaly and infer the magnetization intensity distribution in the region immediately after the 2018 Mt. Motoshirane eruption. The helicopter used in the survey was YAMAHA FAZER R G2, an autonomously driven model which can fly along a precisely programmed course. The flight height above the ground and a measurement line spacing were set to ~ 150 m and ~ 100 m, respectively, and the total flight distance was 191 km. The measured geomagnetic total intensity was found to vary by ~ 1000 nT peak-to-peak. The estimated magnetization intensity derived from measured data showed a 100 m thick magnetized surface layer with normal polarity, composed of volcanic deposits of recent activities. Underneath, a reverse-polarity magnetization was found, probably corresponding to the Takai lava flow in the Early Quaternary period (~ 1 Ma) mapped in the region. Our results demonstrate the cost-effectiveness and accuracy of using drone magnetometers for mapping the rugged terrain of volcanoes.

Identifikasi Lapisan Akuifer Menggunakan Metode Seismik Refraksi di Desa Jatimulyo, Kecamatan Jati Agung, Kabupaten Lampung Selatan

An initial subsurface survey to predict the aquifer is important to avoid the unprospect drill location and getting groundwater with the right discharge. In this study, prediction of the aquifer was carried out using the seismic refraction method in Jatimulyo Village, Jati Agung District, South Lampung Regency. The data was collected on October 6, 2019 using the SUMMIT X One seismic tool with 24 Geophones. The first break data from p-wave travel time is processed and interpreted using the Hagiwara method. Interpretation results show that there are three layers of subsurface lithology in the study area. The weathering layer was found at 2 m to 3.5 m depth with average velocity of 360 m/s. The second layer is dry sand with a velocity of 890 m/s at a depth of 2 m to 8 m. The third layer with a 2300 m/s velocity is a mixture of clay rock and saturated sand at depths of more than 8 m. As a comparison there is resistivity distribution data on the same measurement line in the study area. The overall interpretation shows that at a depth of 12 m with saturated clay sedimentary rock as a prospect of aquifer in this study area.

SIMULATION OF ELECTRICAL MONITORING OF DAMS WITH LEAKAGE WITH A TRANSVERSE PLACEMENT OF THE MEASURING INSTALLATION

Numerical modeling of the problem of dam monitoring by the Electrical Resistivity Tomography method is carried out. The mathematical model is based on integral equations with a partial Fourier transform with respect to one spatial variable. It is assumed that the measurement line is located across the dam longitude. To approximate the shape of the dam surface, the Radial Basic Functions method is applied. The influence of locations of the water-dam, dam-basement, basement-leakage boundaries with respect to the sounding installation, which is partially placed under the headwater, is studied. Numerical modeling is carried out for the following varied parameters: 1) water level at the headwater; 2) the height of the leak; 3) the depth of the leak; 4) position of the supply electrode; 5) water level and leaks positions are changing simultaneously. Modeling results are presented in the form of apparent resistivity curves, as it is customary in geophysical practice.

Investigasi Air Tanah di Daerah Sea Kabupaten Minahasa Dengan Menggunakan Geolistrik Resistivitas Konfigurasi Dipol-Dipol

Penyebaran air tanah yang tidak merata dipengaruhi oleh faktor-faktor jenis batuan, bentuk topografi permukaan, jenis vegetasi dan jumlah curah hujan suatu tempat. Eksplorasi geofisika metode geolistrik tahanan jenis konfigurasi dipol-dipol digunakan untuk mengidentifikasi sebaran akuifer air tanah di desa Sea Kabupaten Minahasa. Data diolah menggunakan software Res2Dinv dan menghasilkan peta model resistivitas bawah permukaan 2 dimensi yang menggambarkan keadaan lapisan tanah. Teridentifikasi sebaran akuifer air tanah permukaan dengan kedalaman ≤ 20 m di sepanjang lintasan pengukuran. Akuifer air tanah dalam diidentifikasi pada lintasan 1 dengan kedalaman sampai 30 m dan 60 m. Akuifer air tanah dengan kedalaman< 60 m mempunyai potensi dijadikan sebagai sumber air tanahThe uneven distribution of ground water is influenced by factors such as rock type, surface topography, vegetation type and the amount of rainfall in a place. Geophysical exploration of the dipole-dipole configuration type of geoelectric resistivity method is used to identify the distribution of groundwater aquifers in Sea village, Minahasa District. The data is processed using Res2Dinv software and produces a 2-dimensional subsurface resistivity model map that describes the state of the soil layer. Distribution of surface ground aquifer with a depth of ≤ 20 m along the measurement line was identified. Deepwater aquifers were identified in l1ne 1 with depths up to 30 m and 60 m. Groundwater aquifers with a depth of <60 m have the potential to be used as ground water sources

Ultrasound Reflector Recognition and Tracking Technique for Two-Phase Flow

Two-phase liquid-gas flow occurs in many safety systems of nuclear reactors as well as in reactor cores. To further improve both safety and commercial performance of nuclear reactors, it is important to improve numerical codes and deepen the understanding of two-phase flow with experiments on gas behaviour in liquids. Among several available measurement methods, ultrasound based methods are affordable and easy to use even for high pressure/temperature flows in non-transparent pipes. Ultrasound Reflector Recognition and Tracking Technique (URRTT) has been developed as a new technique. It uses an ultrasound transducer, which emits ultrasound beam into the liquid with gas bubbles. The phase interface reflects the beam and because of that, the phase interface can be recognised in the reflected signal and the distance (from the transducer) can be calculated. The core of this technique is the tracking algorithm that can separate data of different bubbles from each other and obtain their one dimensional trajectories along the measurement line. Trajectories measured simultaneously by more transducers (at different positions or from different directions) can be combined. That means trajectory of the bubble interface from one transducer can be connected to trajectory from a different transducer and by doing so, a secondary data can be obtained using the information that those trajectories belong to the same bubble. As an example, the average two dimensional velocity between two parallel measurement lines can be obtained. Another example is the measurement of the bubble size using one measurement line with two oppositely oriented transducers. Experiments have been conducted to prove the concept of URRTT. Results have been validated to data obtained by the image processing of footage taken by a high speed camera. The results obtained by URRTT can be of high value since each detected bubble is measured individually and thus, difference in the bubble behaviour based on the size, velocity or history of the bubble can be described.

Experimental Investigations of a Drifting Cloud of Droplets Dispersed from Aircraft

With widespread use of pesticides in modern agriculture, the impacts of spray drift have become a topic of considerable interest. The drifting of sprays is a highly complex process influenced by many factors. The paper presents results of experimental research on a drifting cloud of droplets dispersing from aircraft. Experiments were conducted to quantify spray drift from aerial applications of pesticide. Parallel to the blowing wind, the measurement line 800 m long was disposed. The relationships between the relative dose and the distance of drift as well as spray density and its structure on the measuring length have been established.

Aerial treatments in forest protection – research methodology

Treatment effectiveness in forest protection against harmful insects depends not only on pesticide efficacy of the product applied, but also on a number of other factors including assurance that a given insecticide reaches the pest living in the canopy. In the treatments with the use of aerial equipment (silva-aerial) it is advisable to consider species and age diversity of protected tree stands. The paper presents research methodology on the assessment of spray structure and density, penetration of spray droplets into the canopy as well as a degree of coverage and incorporation in tree crowns. The methodology proposed takes into account characteristics of the forest area studied and its surroundings, as well as the parameters and equipment of the measurement line. There were determined: operation requirements for the aircraft and its test and registration equipment as well as demands on pilot qualifications, flight performance on the measurement line and weather conditions allowing for conducting test trials. In the paper, there are presented a set of values and mathematical formulas needed for the analyses. Taking into account ecological threats, there were included the methods on evaluation of spray drift of the liquid distributed over the forest.

High-Resolution Metrology in the TEM

The transmission electron microscope (TEM) is well known as the technique of choice for visualization and measurement of features at near-atomic length scales, particularly for semiconductor devices. For example, a critical measurement of interest may be the thickness of the gate oxide in a transistor. The accuracy of these measurements is based on calibrated distances at each magnification. The term accuracy conveys the extent to which the measurement minimizes the difference between the measured value and the true value. The associated term precision is the closeness of agreement in a series of measurements locating the end-points of a measurement line. This article describes a method that increases the accuracy of metrology measurements applied to a high-resolution TEM image.