bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence of symmetry lowering in antiferromagnetic metal TmB12 with dynamic charge stripes
Authors: Azarevich A , Glushkov V , Demishev S , Bogach A , Voronov V , Gavrilkin S , Shitsevalova N , Filipov V , Gabáni S , Kačmarčík J , Flachbart K , Sluchanko N
Published: November 2021

Precise angle-resolved magnetoresistance (ARMR) and magnetization measurements have revealed (i) strong charge transport and magnetic anisotropy and (ii) emergence of a huge number of magnetic phases in the ground state of isotopically 11B-enriched single crystals of TmB12 antiferromagnetic (AF) metal with fcc crystal structure and dynamic charge stripes. We analyze for the first time the angular H–φ phase diagrams of AF state of Tm11B12 reconstructed from experimental ARMR and magnetization data arguing that the symmetry lowering leads to the appearance of several radial phase boundaries between different phases in the AF state. It is proposed that the suppression of the indirect Ruderman–Kittel–Kasuya–Yosida (RKKY) exchange along ⟨110⟩ directions between nearest neighboring magnetic moments of Tm3+ ions and subsequent redistribution of conduction electrons to quantum fluctuations of the electron density (dynamic stripes) are the main factors responsible for the anisotropy. Essential (more than 25% at T = 2 K) anisotropy of the Neel field in the (110) plane was found in Tm11B12 unlike to isotropic AF–P boundary in the H–φ phase diagrams of Ho11B12. Magnetoresistance components are discussed in terms of charge carrier scattering on the spin density wave, itinerant ferromagnetic nano-domains and on-site Tm3+ spin fluctuations.
Switchable directional scattering based on spoof core–shell plasmonic structures
Authors: Yin Yun-Qiao , Wu Hong-Wei , Cheng Shu-Ling , Sheng Zong-Qiang
Published: November 2021

Manipulating directional electromagnetic scattering plays a crucial role in the realization of exotic optical phenomenon. Here, we show that the spoof plasmonic structure is able to achieve the switching of directional scattering direction on a subwavelength scale by inserting a perfect electric conductor (PEC) cylinder into the hollow of the spoof plasmonic structure. Based on the modal analysis, it is found that the electromagnetic response of the core–shell structure not only is well excited, but also exhibits the directional scattering by interference between the electric and magnetic dipolar resonances. We also discuss the influence of PEC cylinder radius on the performance of the directional scattering. Finally, the active tunable directional scattering is realized by switching between the two states. This work provides a feasible pathway to the subwavelength manipulation of electromagnetic wave. Moreover, it offers a simple method to switch the directional scattering direction. The proposed design approach can be easily applied to digital electromagnetic wave communication and associated applications.
Donor-acceptor conjugated copolymer with high thermoelectric performance: A case study of the oxidation process within chemical doping
Authors: Chen Liangjun , Wang Wei , Xiao Shengqiang , Tang Xinfeng
Published: November 2021

The doping process and thermoelectric properties of donor-acceptor (D-A) type copolymers are investigated with the representative poly([2,6′-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b] dithiophene]3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophenediyl)) (PTB7-Th). The PTB7-Th is doped by FeCl3 and only polarons are induced in its doped films. The results reveal that the electron-rich donor units within PTB7-Th lose electrons preferentially at the initial stage of the oxidation and then the acceptor units begin to be oxidized at a high doping concentration. The energy levels of polarons and the Fermi level of the doped PTB7-Th remain almost unchange with different doping levels. However, the morphology of the PTB7-Th films could be deteriorated as the doping levels are improved, which is one of the main reasons for the decrease of electrical conductivity at the later stage of doping. The best electrical conductivity and power factor areobtained to be 42.3 S⋅cm−1 and 33.9 μW⋅mK−2, respectively, in the doped PTB7-Th film at room temperature. The power factor is further improved to 38.3 μW⋅mK−2 at 75 °C. This work may provide meaningful experience for development of D-A type thermoelectric copolymers and may further improve the doping efficiency.
Monte-Carlo modelling to demonstrate the influence of alternative flow reference techniques on annual mass emission uncertainty
Authors: Smith T O M , Robinson R A , Coleman M D
Published: November 2021

Industrial emissions into the atmosphere are quantified by measuring the concentration and flow rate in a duct or stack prior to release. These measurements are combined to produce a mass emission which is reported to the European Pollutant Release and Transfer Register. These measurements have to be made according to standards to ensure that they are consistent and accurate. Uncertainty limits are set in relevant EU legislation which must be adhered to. The standard for flow measurement, EN ISO 16911, is in two parts covering manual reference methods and automated measuring systems (AMS). The former outlines six validated methods for calibrating an AMS, while the later outlines the quality control system to be followed to meet the requirements of the legislation. However the standard does not provide consistent information on the impact of the different calibration methods on the uncertainty of the reported emissions. Here we model a system monitoring stack flow and pollutant concentration, including quality control procedures in EN ISO 16911. Several alternative reference methods are modelled to compare the effects of using these different techniques for calibration on the uncertainty of reported annual mass emissions. In a low uncertainty regime the L- and S-type Pitot provide the best performance for both constant and variable flows, however in higher uncertainty regimes all the techniques led to a bias that would lead to misreporting of emissions. Uncertainty information on the techniques is not equally characterised, however, this information represents the best current knowledge of these uncertainties in the emissions community and so the comparisons reported here are all made with the best knowledge available.
Plasma–surface interaction in the stellarator W7-X: conclusions drawn from operation with graphite plasma-facing components
Authors: BrezƖnsek S. , Dhard C.P. , Jakubowski M. , König R. , Masuzaki S. , Mayer M. , Naujoks D. , Romazanov J. , Schmid K. , Schmitz O. , Zhao D. , Balden M. , Brakel R. , Butterschoen B. , Dittmar T. , Drews P. , Effenberg F. , Elgeti S. , Ford O. , Fortuna-Zalesna E. , Fuchert G. , Gao Y. , Goriaev A. , Hakola A. , Kremeyer T. , Krychowiak M. , Liang Y. , Linsmeier Ch. , Lunsford R. , Motojima G. , Neu R. , Neubauer O. , Oelmann J. , Petersson P. , Rasinski M. , Rubel M. , Sereda S. , Sergienko G. , Sunn Pedersen T. , Vuoriheimo T. , Wang E. , Wauters T. , Winters V. , Zhao M. , Yi R. , the W7-X Team
Published: November 2021

W7-X completed its plasma operation in hydrogen with island divertor and inertially cooled test divertor unit (TDU) made of graphite. A substantial set of plasma-facing components (PFCs), including in particular marker target elements, were extracted from the W7-X vessel and analysed post-mortem. The analysis provided key information about underlying plasma–surface interactions (PSI) processes, namely erosion, transport, and deposition as well as fuel retention in the graphite components. The net carbon (C) erosion and deposition distribution on the horizontal target (HT) and vertical target (VT) plates were quantified and related to the plasma time in standard divertor configuration with edge transform ι = 5/5, the dominant magnetic configuration of the two operational phases (OP) with TDU. The operation resulted in integrated high net C erosion rate of 2.8 mg s−1 in OP1.2B over 4809 plasma seconds. Boronisations reduced the net erosion on the HT by about a factor 5.4 with respect to OP1.2A owing to the suppression of oxygen (O). In the case of the VT, high peak net C erosion of 11 μm at the strike line was measured during OP1.2B which converts to 2.5 nm s−1 or 1.4 mg s−1 when related to the exposed area of the target plate and the operational time in standard divertor configuration. PSI modelling with ERO2.0 and WallDYN-3D is applied in an interpretative manner and reproduces the net C erosion and deposition pattern at the target plates determined by different post-mortem analysis techniques. This includes also the 13C tracer deposition from the last experiment of OP1.2B with local 13CH4 injection through a magnetic island in one half module. The experimental findings are used to predict the C erosion, transport, and deposition in the next campaigns aiming in long-pulse operation up to 1800 s and utilising the actively cooled carbon-fibre composite (CFC) divertor currently being installed. The CFC divertor has the same geometrical design as the TDU and extrapolation depends mainly on the applied plasma boundary. Extrapolation from campaign averaged information obtained in OP1.2B reveals a net erosion of 7.6 g per 1800 s for a typical W7-X attached divertor plasma in hydrogen.
Bare laser-synthesized plasmonic Au and TiN nanoparticles as functional additives to polymer nanofiber platforms for tissue engineering applications
Authors: Al-Kattan A , Kabashin A V
Published: November 2021

Exhibiting strong optical absorption in the visible – near-infrared, plasmonic nanomaterials can be used as transducers in optical biosensing, contrast agents in bioimaging and synthesizers of photothermal therapy. Such functionalities promise their employment as functional elements in tissue engineering platforms, but such applications typically require ultraclean nanomaterials to minimize toxicity problems, which is not easy using conventional chemical synthesis routes. We recently demonstrated the possibility of fabricating ultraclean bare (ligand-free) plasmonic Au and TiN nanoparticles by ultrashort laser ablation in liquid ambient. Exempt of any toxic contaminants and exhibiting a series of imaging and therapeutic functionalities, these nanomaterials present promising objects for various biomedical applications. Here, we review our recent progress in the co-electrospinning of laser-synthesized Au and TiN nanoparticles with polymers to form functionalized matrices for tissue engineering.
Design and characterisation of calcium carbonate microspheres for anticancer drug delivery
Authors: Kalenichenko D , Nifontova G , Sukhanova A , Nabiev I
Published: November 2021

The development of delivery systems providing prolonged release of antitumor drugs represents one of the challenges in designing and optimization of novel tools for cancer therapy. The employment of spherical inorganic microparticles, in particular, calcium carbonate vaterite microspheres, as microcarriers appears promising because of their porous, matrix structure, biocompatibility, and biodegradability. Here, we summarize the results of the development of the approaches to synthesis of calcium carbonate vaterite microspheres with narrowed size distribution and microencapsulation of low-molecular-weight anticancer drugs, such as doxorubicin hydrochloride into obtained microspheres. Supplementing the reaction mixture with a thickener defines fabrication of homogeneous vaterite microparticles with a spherical shape and an average size of 2 to 3 μm. Synthesised microspheres ensure prolonged release of doxorubicin at physiological pH values and can be used as a delivery system and as a structural component for development of a theranostic platform for tumour treatment and diagnosis.
Novel advanced nanotechnologies for nuclear medicine
Authors: Zavestovskaya I N , Grigorieva M , Petrunya D , Grigoriev A , Deyev S M , Prasad P N , Kabashin A V
Published: November 2021

Nuclear nanomedicine forms a new research field based on the synergy of nuclear medicine and nanotechnology and implying the use of nanomaterials as carriers of diagnostic or therapeutic radionuclides. Such an approach promises a series of advantages over classical methods of nuclear medicine, including an increased surface area-to-volume ratio, passive/active delivery, high loading capacity, large cross-section in interactions with biological tissues, and unique properties of nanomaterials that make possible many functionalities within one construct. In this short review article, we will highlight our recent achievements in the development of nuclear nanomedicine technologies, which promise the advancement of methods for cancer treatment.
Low Intensity Beam Extraction Mode on the Protom Synchrotron for Proton Radiography Implementation
Authors: Pryanichnikov A A , Zhogolev P B , Shemyakov A E , Belikhin M A , Chernyaev A P , Rykalin V
Published: November 2021

Proton radiography is one of the most important and actual areas of research that can significantly improve the quality and accuracy of proton therapy. Currently, the calculation of the proton range in patients receiving proton therapy is based on the conversion of Hounsfield CT units of the patient's tissues into the relative stopping power of protons. Proton radiography is able to reduce these uncertainties by directly measuring proton stopping power. The study demonstrates the possibility of Protom synchrotron-based proton therapy facilities to operate in a special mode which makes it possible to implement proton radiography. This work presents the status of the new low beam intensity extraction mode. The paper describes algorithms of low flux beam control, calibration procedures and experimental measurements. Measurements and calibration procedures were performed with certified Protom Faraday Cup, PTW Bragg Peak Chamber and specially designed experimental external.
Formation of critical thinking related to the energetic efficiency of applied physics processes of civil engineering works
Authors: Márquez Peñaranda J F , Pineda Rodríguez J R , Rodríguez Lizcano A
Published: November 2021

Current problems associated to contamination and climate change claim for urgent solutions to make real a sustainable development of modern societies. To answer that call, the efficiency of applied physics processes must be continuously evaluated. Particularly, engineering programs are called to strengthen the training offer related to basic and applied physics sciences considering energetic transformation and transferring processes. In the civil engineering field, design, construction, functioning, and final disposition of buildings can be understood as applied physics processes. This work proposes an approach for defining and studying possible variables related to energetic processes and their mutual relationship. Such variables must be able to describe the processes of energetic changes which can occur during construction of civil works. To do so, qualitative analysis of mathematic expressions is done to promote the formation of abstract mental connections made of sensitivity and logical thinking. The methodology is based on four moments: (a) students’ brainstorming related to a particular issue, (b) identification of main topics related to energy transformation, (c) variable operationalization, (d) proposal of mathematical expressions. This proposal is expected to facilitate the construction of concepts related to sustainable development and help students to trust themselves when taking well thought out risks.
Evaluation of the teaching of physics areas in university engineering programs
Authors: Garzón-Agudelo P A , Palacios-Alvarado W , Medina-Delgado B
Published: November 2021

Relevance studies provide a vision of the impact and degree to which an academic offer responds to the needs of an environment. In this research it was possible to analyze the context of the existing technological level programs with respect to the offer of physics branches linked in their curricula, in order to determine the correlation between these areas and the contribution they represent in the development of competences and skills for the exercise of the profession of Technologists in areas of Engineering knowledge. A descriptive methodological approach was used, through the application of instruments and tools that allowed synthesizing the findings in relation to the formulated study hypothesis. It was concluded that the fields of physics at the technological level allowed establishing the bases to articulate the knowledge towards the disciplinary study in each of the programs studied; likewise, it was evidenced that the behavior of the proportion of physics courses within the curricular structures are corresponding among the programs under study; and finally, it was demonstrated that the areas of physics are mostly addressed in the programs whose specific field demands the application of electronic, mechanical, electromechanical, manufacturing, instrumentation, automation and control systems.
Daily performance of a solar hybrid regenerative gas turbine in Colombia
Authors: Moreno-Gamboa F , Vera-Duarte E , Guerrero-Gómez G
Published: November 2021

This work presents the evolution of the operation of a regenerative hybrid solar gas turbine in an average day of the year. The system is evaluated by means of a thermodynamic model that includes a solar concentrated heliostat field solar concentrator with central receiver, a combustion chamber, and the thermal engine. The model is applied in Barranquilla, Colombia using local temperature and the solar radiation estimated with a theoretical model. Power output, the global efficiency and thermal engine efficiency are estimated. Additionally, to estimate the temperatures in different states of the cycle with and without regenerator. Finally, the impact of the regenerator is evaluated, which can increase the temperature of the solar receiver by up to 13.6%, and the inlet temperature to the combustion chamber increases by 17.3% at noon, when solar radiation is maximum.
Development of a gravimetric fuel measurement system for the evaluation of engine performance physical parameters
Authors: Prada Botia G C , Rojas Suárez J P , Orjuela Abril M S
Published: November 2021

This paper presents the implementation and design features of a gravimetric-based fuel consumption system. The proposed system comprises a gravimetric balance with serial output, a fuel pump, and a control valve that are integrated into a complete engine test bench via Arduino UNO®. The study implements an instrumentation methodology to minimize measurement disturbance and error propagation, which represents a major concern in engine experimental testing. Moreover, an interactive virtual environment is developed to reinforce user interaction via LabView™. Results demonstrated that the proposed measurement system features robust and reliable operation while maintaining negligible disturbance and overall uncertainty ranging from 0.010-0.23 g/s. Additionally, it was evidenced that the measurement system allows the analysis of key parameters to evaluate engine performance. The study of the fuels blends shows that the ethanol content causes a 6.8% increase in brake specific fuel consumption and a 4% decrease in the brake thermal efficiency. Due to the low cost of the developed measurement system can be easily adapted to test bench laboratories to promote a better learning process and in industrial sectors for better energy management.
Identifying Subsurface Structures beneath the Sumani and Sianok Segments of the Great Sumatran Fault using Combined Geophysical Methods
Authors: Amir Harman , Bijaksana Satria , Dahrin Darharta , Nugraha Andri Dian , Arisbaya Ilham
Published: November 2021

The 1900 km long Great Sumatran Fault is a complex active fault system that is divided into segments that include the Sumani and Sianok segments in a rather densely populated area of the West Sumatra Province. Major earthquakes have occurred in these two segments that include the March 2007 Sumatra earthquake. Mitigating future risks requires a better understanding of these complex segments. To identify the subsurface structures beneath the Sumani and Sianok segments, we are conducting combined geophysical study that include gravity and magnetic. Gravity data were obtained from the published regional Bouguer anomaly map of the area around these two segments. The measurements from which the map was derived were rather sparse. Thus, more detailed magnetic measurements were carried out in this study. Magnetic measurements were also expected to be more sensitive as the predominant rocks in the study area are volcanic as well as other type of intrusive rocks. These gravity and magnetic analyses were complemented by seismicity data that include relocated seismicity data that will enhance the modelling of subsurface structures. Progress of this study will be reported. Challenges and obstacles will also be presented.
Seismic Vulnerability Index Calculation for Mitigation Purposes at Cilacap District
Authors: Edison Robert , Rohadi Supriyanto , Perdana Yusuf , Riama Nelly Florida , Karnawati Dwikorita
Published: November 2021

Seismic vulnerability index is one of the key factors in mitigation that shows the vulnerability of the soil layer beneath when passed through with a wave, the more vulnerable the soil layer, the more damage it done when an earthquake happens. Seismic vulnerability is calculated using two variables, that is dominant frequencies and amplification that are obtained by analyzing HVSR curve. HVSR are used to determine the dominant frequency by determining the maximum amplification in that area. HVSR curve is obtained by measuring microbemor data in 163 spots with 30 minutes-minimum duration in Cilacap with a portable seismograph. Mierotremor is a natural vibration that is caused by continuous vibration that come from beneath the surface, sometimes mixed up by the vibrabon that is caused by human activities such as pipe-flow, vehicles, etc. Thus, the purposes of this research are to determine which area is more vulnerable than others, based on the seismic vulnerability index, so it could be a reference for regional development to classified is it safe or unsafe to build in that area, remembering Cilacap is one of the most developed Districts in Central Java.
Gravity Data Analysis Based on Optimum Upward Continuation Filter and 3D Inverse Modelling (Case Study at Sedimentary Basin in Volcanic Region Malang and Its Surrounding Area, East Java)
Authors: Setiadi I , Marjiyono  , Nainggolan T B
Published: November 2021

The study on the fore-arc sedimentary basin for hydrocarbon exploration is rare because of the more complicated geological structures, and conventional seismic methods cannot optimally penetrate the rock layers as there are many volcanic and limestone rocks. One of the natural resources potential in the Southern part of the East Java region, especially in Malang and its surrounding areas is the possibility of hydrocarbons in the fore-arc basin, so research is needed to know the existence of these sedimentary basins. The gravity method is one of the geophysical methods used to assess sedimentary basins based on physical parameters of mass density. The aims of this research are to delineate the sedimentary sub-basin, to find out its structure pattern, interpret subsurface geological and basement configuration. The data analysis approach used in this study involves spectral analysis, upward continuation filter, and 3D inverse modeling. The maximum height for the optimum upward continuation filter is 3000 m, which results in regional and residual anomalies. There were five sedimentary sub-basins identified based on residual gravity anomaly, and the gravity anomalies can also detect structure patterns such as basement high, lineament, and fault pattern. The bedrock is supposed as an intermediate igneous rock with a mass density of around 2.7 gr/cc according to the results of 3D inverse modeling. Deposition from bottom to upward is Mandalika, Nampol, and Wonosari Formations and completed by the uppermost are quaternary volcanic rocks. The inversion modeling results show that the Malang and surrounding areas have thick sedimentary rocks covered by volcanic deposits, which is impressive for further investigation to explore the possibility of the hydrocarbon existence in these areas.
Integrated Pore Pressure Model Estimation – Case Study of Jambi Sub-basin, South Sumatera, Indonesia
Authors: Farabi Ahmad Farhan , Winardhie Ignatius Sonny , Wibowo Noor Cahyo
Published: November 2021

Pore pressure estimation is crucial in drilling wells for safety purposes also a very effective method for dealing with drilling accidents. Determination of overpressure is the main foundation in the evaluation to minimize the non-productive time (NPT). Here we present several models to generate pore pressure analysis of well from Jambi Sub-basin, South Sumatera, Indonesia. The model for estimation pore pressure is carried out by 3 methods: Eaton, Yan & Han, and Kan & Swan. Those methods will be compared to gain a more accurate model estimation within the study area. Kan and Swan’s model show the best fit for estimation because this method is suitable for the formation of tester like MDT/DST on higher frequency with parameter of C1 = 0.001 and C2 = 0.0003 for Jambi Sub-basin. The velocity data to construct the 3D pore pressure model was also validated with well data using multi-attribute analysis. The multi-attribute analysis used 2 algorithms, namely step-wise regression and probabilistic neural network (PNN). The analysis show that PNN has a better correlation compared to step-wise regression. The analysis shows the overpressure zone depth is ranges from 1700 – 2000m on Gumai Formation with maximum pressure around 6500 psi. The peak of overpressure dominated by Gumai and Talang Akar formation is caused by the loading mechanism because the rate of sedimentation on thick shale sequence is higher than the rate of dewatering on those formations.
The Study of Automatic Picking of P and S Wave Arrival and Identification of Earthquake Sequence Pattern using Scalogram in Obspy (Python)
Authors: Kiswanti Sri , Palupi Indriati Retno , Raharjo Wiji , Arwa Faricha Yuna , Dwiyanti Nela Elisa
Published: November 2021

Initial identification on an earthquake record (seismogram) is something that needs to be done precisely and accurately. Moreover, the discovery of a series of unexpected successive earthquake events has caused unpreparedness for the community and related agencies in tackling these events. Determining the arrival time of the P and S waves becomes an important parameter to finding the location of the earthquake source (hypocenter) as well as further information related to the earthquake event. However, manual steps that are currently often used are considered to be less effective, because it requires a lot of time in the process. Continuous Wavelet Transform (CWT) analysis can be a solution for this problem. With further CWT analysis in the form of a scalogram, can help to determine the arrival time of P and S waves automatically (automatic picking) becomes simpler. In addition, further CWT analysis can also be utilized to help identify the sequence of earthquake events (foreshock, mainshock, aftershock) through the resulting scalogram pattern.
Flower Pollination Algorithm for the Inversion of Schlumberger Sounding Curve
Authors: Raflesia F , Widodo W
Published: November 2021

Inversion of schlumberger sounding curve is non-linear, and multi-minimum. All linear inversion strategies can produce local optimum, and depend on the initial model. Meanwhile, the non-linear bionic method for inversion problems does not require an initial model, simple, flexible, derivation-free mechanism and can avoid local optimum. One of the new algorithm of the non-linear bionic method for geophysical inversion problem is the Flower Pollination Algorithm (FPA). The FPA is used for the inversion of schlumberger sounding curve. This algorithm was stimulated by the pollination process for blooming plants. The applicability of the present algorithm was tested on synthetic models A-type and KH-type curve. Numerical tests in MATLAB R2013a for the synthetic data and the observed data show that FPA can find the global minimum. For further study, inverted results using the FPA are contrasted with the damped least-square (DLSQR) inversion program, Particle Swarm Optimization (PSO), and Grey Wolf Optimizer (GWO). The outcomes of the comparison reveal that FPA performs better than the DLSQR inversion program, PSO, and GWO.
Integration of Post-stack Inversion and Rock Physics to Determine Sandstone Reservoir Quality: Barakan Sub-basin case
Authors: Nainggolan T B , Adhar M P , Setiadi I
Published: November 2021

Barakan Sub-basin is assessed as potential basin for hydrocarbon reserves in the eastern region of Indonesia because it is adjacent to Masela block giant gas field. Reservoir rocks in this sub-basin are sandstones from Middle Jurassic (Lower Flamengo Formation) until Oligocene (Adi member Formation). Main sandstone reservoir rocks are knowingly studied to have good porosity in Upper Flamengo, Kopae, Ekmai and Adi member Formations. But, there is no significant study to determine sandstone reservoir distribution that have good porosity quality. Therefore, an integrated method of inversion and rock physics study are needed to determine sandstone reservoir quality. This study uses 2D marine seismic post-stack time migration and 2 wells namely Barakan-1 and Koba-1 wells. Sensitivity analysis with cross-plot of gamma ray log versus acoustic impedance values range of 20-60 API and 9000-42000 (ft/s)*(g/cc) shows a strong correlation of good porosity sandstone to low impedance in Ekmai Formation of both wells. Model based of post-stack inversion reveals sandstone distribution in Ekmai Formation of both wells. Time structure maps of top and bottom horizons in Ekmai Formation indicates Barakan-1 well within anticline height structure and Koba-1 well are deposited in a middle of sub-littoral environment.
Bayesian Inference of Centroid Moment Tensors of the 2019 Ambon (Mw 6.5) Aftershock Earthquake Sequence, Indonesia: A Preliminary Result
Authors: Baskara A W , Sahara D P , Nugraha A D , Muhari A , Rusdin A A , Rosalia S , Priyono A , Zulfakriza Z , Widiantoro S , Puspito N T , Lesmana A , Kusumawati D , Ardianto A , Halauwet Y
Published: November 2021

The Ambon Mw 6.5 earthquake on September 26th, 2019, had contributed to give severe damages and significantly increased seismicity around Ambon Island and surrounding areas. Mainshock was followed by aftershocks with spatial distribution added to the impact of destructions in this region. We investigated aftershocks sequences to reveal the effect of mainshock toward the change in the in-situ stress field, including the possibility of the existing faults reactivation and the generation of aftershocks. We inferred centroid moment tensor (CMT) for significant aftershock events with Mw more than 4.0 using waveform data recorded from October 18th to December 15th, 2019. The aftershock focal mechanism was determined using the Bayesian full-waveform inversion code ISOLA-Obspy. This approach provides the uncertainty of the CMT model parameters. From ten CMT solution we had inferred in three seismic clusters, we found that majority of events have a strike-slip mechanism. Four events located on the south of the N-S trendings have a dextral strike-slip fault type, reflected the rupture of the mainshocks fault plane. Three events in the cluster of Ambon Island are dextral strike-slip, confirming the presence of the fault reactivation. Meanwhile, three CMT solutions in the north show the dextral strike-slip faulting and may belong to the mainshock main fault, connected with the cluster in the south.
Site characterizations of BMKG seismic network, Indonesia, based on HVSR analysis
Authors: Muzli Muzli , Kambali R A P , Nugraha J , Sulastri S , Hakim A R , Rohadi S , Triyono R , Riama N F , Karnawati D
Published: November 2021

In the last few years BMKG (Agency for Meteorology Climatology and Geophysics) has increased the number of seismic stations significantly. Until mid-2020, when this study was conducted, the number of BMKG stations has reached 339 units. Development of the network is aimed to improve the data quality, speed of earthquake data processing and information dissemination to the public, accuracy of the hypocenter, as well as the magnitude. The objective of this study is to identify the site characteristics of the network. We analysed the noise recorded at BMKG stations throughout Indonesia using the HVSR (Horizontal to Vertical Spectral Ratio) method. The results of HVSR analysis were used to classify the site conditions of each station. We got the number of stations with the classification of hard rock, rock, hard soil, medium soil, and soft soil, 47, 57, 52, 30, and 84, respectively. This site condition represents the stations characteristics and affects the quality of seismic waveform data.
Elastic Property Modeling, Extended Elastic Impedance (EEI) and Curve-Pseudo Elastic Impedance (CPEI) Inversion for Pore Type Analysis and Hydrocarbon Distribution in Carbonate Reservoir, Kujung I Formation, “Humaira” Field, North East Java Basin
Authors: Kumalasari I N , Winardhi I S
Published: November 2021

The complexity of the pore shape in carbonate rocks causes the need for a special strategy to characterize carbonate reservoir. The more information used, the more accurate the reservoir characterization will be. Pore type analysis is the important study because it relates to the fluid flow properties. The elastic property modeling show a good match to the actual data. The results of the well log and petrophysical data analysis show that the gas zone is located at the upper side of Kujung I Formation. Based on rock physics modeling result, the possible pore type developing in the Kujung I Formation is reference pore with the dominance of the aspect ratio value of about 0.17-0.19. The carbonate layer containing hydrocarbons is characterized by low Lamda-Rho, Lamda/Mu values and a low Poisson ratio. Porous carbonate layer, characterized by a low Mu-Rho value. The slice results show that the gaseous area is located on the anticline. The zone that has good porosity indicated by low Mu-Rho. In the IN-3 well there are no hydrocarbons, this analysis is in accordance with the geological condition of the IN-3 well which is in a low area on the time structure map. The inversion results show a good match between CPEI against water saturation log and CPEI against porosity log.
Analysis of Source Mechanism and Coulomb Stress Change (Case Study: Molucca Sea Earthquakes November 15th, 2014 and November 14th, 2019)
Authors: Purba Indra Josua , Suardi Iman , Daniarsyad Gatut , Lasmita Defni
Published: November 2021

On November 15, 2014, and November 14, 2019, two major earthquakes occurred in the Molucca Sea with a moment magnitude of Mw 7.0 and Mw 7.1, respectively. These earthquakes were caused by the convergence activity between the Sunda Plate and the Philippine Sea Plate which form a double subduction zone in the Molucca Sea. We carried out the moment tensor inversion using Kiwi Tools to analyze the source mechanism for both of the earthquakes. The results show a thrust fault mechanism with the strike, dip, and rake of the ruptured fault planes are 187°, 63°, 85° and 196°, 43°, 83°, for the first and second events, respectively. We refine the location of the two mainshocks and their aftershocks by performing hypocenter relocation using the double difference method. This resulted in NE-SW aftershocks distribution for both events which occured close to the Molucca Sea Plate boundaries with the mainshocks location are relatively close to each other (± 50.32 km). Finally, we calculate the Coulomb stress changes to analyze the triggering effect between the two major events and between the mainshock and its aftershocks for each event. The results show that the hypocenter of the November 14, 2019 earthquake is in the increased zone of Coulomb stress changes produced by the November 15, 2014 earthquake with the value of 1.2 bar. The aftershocks of both events also occurred in the increased Coulomb stress changes with the range value of 0.5 - 1.8 bar for the first event and 0.2 - 0.8 bar for the second event.
Indonesian Earth’s Lithospheric Magnetic Field modelling using Spherical Cap Harmonic Analysis Method
Authors: Ilham  , Syirojudin M , Margiono R , Marsono A , Ardiana N
Published: November 2021

The earth’s lithospheric magnetic field is part of the main earth’s magnetic field. The lithospheric field has a very small value compared to the Earth’s main magnetic field, approximately less than 1%, and this field is generated at the earth’s crust and upper mantle. Modelling of lithospheric field is useful mainly for predicting the distribution of the value of lithospheric fields and to determine the magnetic anomaly. In this research, modelling the Earth’s lithospheric magnetic field uses Spherical Cap Harmonic Analysis (SCHA) method and this method can do modelling using regional magnetic data. The data used for the modelling are magnetic repeat station data in Indonesia region (BMKG’s Epoch) and SWARM satellite data. The results of the modelling using integrated SWARM satellite and repeat station data produce RMSE values of 64.0834 nT and the expansion of index K is 70. In addition, the results of the modelling resolution is 1.50. The value’s range of modelling’s result are -987.192 – 998.239 nT for X component, -968.189 – 949.438 nT for Y component, -981.266 – 608.676 nT for Z component, and -904.151 – 997.389 nT for total intensity are.
Optimization of 2-D Magnetotelluric (MT) Modes Based on Data Dimensionality to Delineate Potential Area for Shale Gas Prospect in Kutai Basin, East Kalimantan, Indonesia
Authors: Hidayat  , Lucky Junursyah G.M , Setiawan Ahmad , Pradana Andrawan Erlang
Published: November 2021

We conducted a study using the magnetotelluric method in the Kutai Basin, which is one of the largest and deepest tertiary sedimentary basin located in the province of East Kalimantan, Indonesia. The Kutai Basin, which is one of the sedimentary basin that is proven to produce hydrocarbons in Indonesia, also has the potential for shale gas with all the complexities of its geological structure. Inversion of 2-D MT can generally be done in three modes with different sensitivity. We perform data processing objectively to obtain the best quality data. We continued our data processing to the inversion process with a range from 80.78% to 97.09% coherency data. We also performed sensitivity skewness calculations to determine the dimensionality of our data. The map of sensitivity skewness is shown for the vertical path A – A’ with direction N – S in our study area. Based on the calculation results, the skewness value below 0.3 is obtained around the frequency 320 - 0.002 Hz, and associated with the 2-D structure while value above 0.3 are obtained around the frequency 0.00198 - 0.00034 Hz at KT34 and KT36 stations. Based on dimensionality calculations, it is concluded that the MT data in the Kutai Basin is dominated by 2-D structural responses, so that the TE + TM (invariant) mode is the best measurement mode for inversion modeling. We also performed calculations to obtain the optimum smoothness factor (tau) using a trade-off curve. Based on the results of the inversion with the optimization of these data parameters, we obtained a subsurface geological structure pattern such as fault and fold structure along the vertical path of A – A’. The low resistivity anomaly is interpreted as a response to the presence of black shale which is part of the Pamaluan Formation. The top of the Pamaluan Formation is estimated at the depth that varies from 2000m to 4000m below the surface along the A – A’ vertical cross-section.
Peak Ground Acceleration (PGA) and Peak Ground Velocity (PGV) Analyze for Microzonation of Earthquake Hazard Area: Case Study in West Nusa Tenggara
Authors: Razin T , Khatimah K , Annisa Y , Hamzah A , Massinai M F I
Published: November 2021

The Lombok region is located around a complex tectonic zone with an Indo-Australian oceanic crust transition zone with Australian continental crust in the west and Sundanese arc in the east. This complexity makes some area in West Nusa Tenggara have a high level of earthquake vulnerability and to determine the potential level of seismic damage risk this study was conducted by analyzing Peak Ground Acceleration (PGA) and Peak Ground Velocity (PGV) using earthquake data since 2000 - March 2020 with an intensity more than M4.5. Earthquake data are analyzed using the Yin-Min Yu formula to get the relationship between Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), and earthquake intensity, so areas with risk level of earthquake damage can be mapped as preliminary earthquake mitigation schemes. The results of the study show that the highest PGA value in West Nusa Tenggara is 74.73 gal at the bedrock and when it on the surface, the PGA value can increase due to amplification of local soil conditions. Likewise PGV value about 32.21 gal where this maximum value is located in East Lombok Regency and North Lombok Regency. According to the classification of PGA and PGV values, the study area has a potential high-risk level of earthquake damage.
Fault rupture in Baribis Fault possibly related to the 1847 major earthquake event in the Cirebon area
Authors: Daryono Mudrik Rahmawan , Natawidjaja Danny Hilman , Puji Anggraini Rizkita , Aribowo Sonny
Published: November 2021

Baribis Fault is a recently identified active fault known to have thrust movement which located along the northern part of the West Java area. This E-W striking fault runs across high-populated areas, including Cirebon, Indramayu, Sumedang, and Subang area (with a probability of continuing to Jakarta and Banten areas). The last major historical earthquake occurred on November 16th, 1847 around the fault line with a radius of shaking area up to 400 km. The available high-resolution Digital Elevation Model from Geospatial Information Agency, called DEMNAS, has about 7.5-m grid data resolution but still not adequate to be used for identifying fault ruptures of this event. Hence, we conducted an Unmanned Aerial Vehicle (UAV) 3D Photogrammetry survey flown in the lower latitude (~100-m high) in the suspected sites. This study identified clear fault scarp associated with stream-valley offsets indicating strike-slip movement in the Ujung Jaya subdistrict, Sumedang. The trace of fault rupture has a 5±1-meter sinistral offset. This sharp fault deformation feature is possibly related to the 1847 earthquake in this area. This fact is different from regional morphology, which shows that the Baribis Fault is a thrust. Further study is necessary to get more detailed and precise information.
Preliminary Results of Receiver Function Forward Velocity Modelling at Merapi Volcano
Authors: Auly M F R , Ilahi A K , Madrinovella I , Widyanti S , Suhardja S K , Fatimah D Y , Nugraha A D , Zulfakriza Z , Widiyantoro S , Métaxian J-P , Ramdhan M
Published: November 2021

The tectonic setting of Java island, located at southwestern edge of the Eurasia continent, is dominated by the subduction of Indo-Australia plate. One of the characteristics of active subduction is active seismicity, the generation of arc magmatism and volcanic activity. Mt. Merapi is one example of active volcano related with the subduction process. It is one of the most active volcanoes with location close to high population area. To better understand this area, we employed the Receiver Function technique, a method to image sub surface structure by removing the vertical component from horizontal component. First, we collected high magnitude events and processed RF with water level deconvolution method. Then, we constructed synthetic model with initial velocity input from previous tomography model. Note that we used reflectivity method in generating synthetic model with input parameters matched with parameters from real data processing. Next, we adjusted velocity inputs mainly on tops sediments (1-3 km) to include sediment layers and volcanic rocks, mid-depth low velocity zone that may be related with magma chamber and depth of crust-mantle boundary. Current forward velocity models show a relatively good agreement from 3 stations (ME25, ME32 and ME36). We estimate a thin layer of sediments followed a zone of velocity layer at a depth of 10-15 km and crust-mantle boundary ranging from 26-29 km. In this study, simulated that the signal of sediments layer and low velocity layers interfere main crust mantle boundary that supposed to be highest signal after the P wave in the typical receiver function study.
An Attempt to Pick Teleseismic P Wave Arrival Using Envelope and Artificial Neural Network Algorithm
Authors: Lobo R K , Gaol Y H L , Fatimah D Y , Abdullah A , Zaky D A , Suhardja S K , Nugraha A D , Zulfakriza Z , Widiyantoro S , Ramdhan M , Palgunadi K H , Mujihardi B
Published: November 2021

Seismic events detection and phase picking play an essential role in earthquake studies. Typical event detection is done visually or manually on recorded seismogram by choosing a series of higher amplitude signals recorded on at least 4 stations. More sophisticated methods have been used in event detection and picking with additional attributes such as Short Time Average over Long Time Average (STA/LTA). This method is based on average number sampled at multiple predefined windows. However, STA/LTA is dependent on the window size which becomes its drawback. In this study, we explore one derivative attribute, popularly known as envelope or instantaneous amplitude. It has been extensively used in seismic reflection and refraction method. In principle, this method uses the Hilbert Transform to calculate complex seismic trace and take the magnitude of complex seismic trace as envelope amplitude that can be used to analyze P wave arrival time. We employed one of the machine learning methods, Artificial Neural Network (ANN). The ANN method works by analyzing various inputs and training them to recognize patterns in P wave arrival signals. We started our study by applying envelope attribute to synthetic data with noise addition. We found that with noisy data the envelope attribute still gives a clear signal for first-time arrival. Next, we trained 300 seismograms of teleseismic events recorded on IRIS-US networks and tested our trained program on 20 seismograms as a blind test. To compare performance between the two methods, we calculated the difference between the results of automatic picking and manual picking. The final calculation shows an average deviation of 0.355 seconds. Twenty-five percent of testing data (5 samples) has a deviation above 0.5 seconds, and 75% of the remainder (15 samples) already had a deviation under 0.5 seconds. The more significant deviations of the P wave picks are likely due to noisy signals in the data set and complex arrival signals. This study shows that the combination of envelope attribute and machine learning method is promising to distinguish teleseismic P wave arrival and automatically pick them.