bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reconstruction of multipolar point sources with multi-frequency sparse far field data
Authors: Ji Xia 
Published: April 2021

Abstract
The inverse acoustic scattering of point sources using multi-frequency sparse far field patterns is studied. The object may be a sum of monopoles and dipoles. We show that the locations and scattering strengths of the point sources can be uniquely identified by the multi-frequency far fields taken at sparse observation directions. Based on the uniqueness analyses, two schemes are proposed to distinguish the dipoles and monopoles, locate the positions and recover the scattering strengths. Numerical examples in two dimensions are presented to validity the effectiveness and robustness of the proposed methods. In particular, the numerical reconstructions indicate that the proposed methods are fast, stable and independent of the types, number or positions of the unknown point sources.
Passivation of thermally-induced defects with hydrogen in float-zone silicon
Authors: De Guzman J A T , Markevich V P , Hiller D , Hawkins I D , Halsall M P , Peaker A R 
Published: April 2021

Abstract
In this study, passivation of thermally-activated recombination centers with hydrogen in n-type float zone (FZ) Si containing nitrogen has been investigated. Prior to hydrogenation samples were heated to 550 °C using rapid thermal annealing and conventional furnaces. A large decrease in minority carrier lifetime occurred upon the heat-treatments confirming previous reports. A sequence of electron traps created in this process have been detected in the deep level transient spectra and characterized. Significant changes in the spectra have occurred after treatments in remote hydrogen plasma and subsequent annealing of the hydrogenated samples in the temperature range 100 °C–400 °C. A total elimination of electrical activity of the thermally induced defects has been observed in the hydrogenated samples subjected to annealing in the temperature range 150 °C–300 °C. The results obtained suggest a simple way for an effective cure of the degraded FZ-Si-based solar cells. Possible defect reactions occurring in the FZ-Si crystals and the role of nitrogen and carbon upon the performed treatments are discussed.
The effects of process parameters on melt-pool oscillatory behaviour in gas tungsten arc welding
Authors: Ebrahimi Amin , Kleijn Chris R , Hermans Marcel J M , Richardson Ian M 
Published: April 2021

AbstractInternal flow behaviour and melt-pool surface oscillations during arc welding are complex and not yet fully understood. In the present work, high-fidelity numerical simulations are employed to describe the effects of welding position, sulphur concentration (60–300 ppm) and travel speed (1.25–5 mms−1) on molten metal flow dynamics in fully-penetrated melt-pools. A wavelet transform is implemented to obtain time-resolved frequency spectra of the oscillation signals, which overcomes the shortcomings of the Fourier transform in rendering time resolution of the frequency spectra. Comparing the results of the present numerical calculations with available analytical and experimental datasets, the robustness of the proposed approach in predicting melt-pool oscillations is demonstrated. The results reveal that changes in the surface morphology of the pool resulting from a change in welding position alter the spatial distribution of arc forces and power-density applied to the molten material, and in turn affect flow patterns in the pool. Under similar welding conditions, changing the sulphur concentration affects the Marangoni flow pattern, and increasing the travel speed decreases the size of the pool and increases the offset between top and bottom melt-pool surfaces, affecting the flow structures (vortex formation) on the surface. Variations in the internal flow pattern affect the evolution of melt-pool shape and its surface oscillations.
Harvesting wind energy with a bi-stable configuration integrating vortex-induced vibration and galloping
Authors: Wang Yuansheng , Zhou Zhiyong , Qin Weiyang , Zhu Pei 
Published: April 2021

Abstract
This paper proposed a wind energy harvester that integrates the merits of vortex-induced vibration (VIV), galloping and multi-stability. Two different shapes of bluff bodies are introduced to induce VIV and galloping for incoming flow, respectively. Three magnets are placed on the beam and fixture so as to generate bi-stability by magnetic attraction. As the wind blows through, the induced aero-dynamical instability leads the piezoelectric beam to oscillate and execute snap-through motion, which could generate a large electric output. The validation experiment was conducted. The experimental results show that as the flow speed increases from v= 1.0 m s−1 to 7.0 m s−1, the harvester could begin snap-through motion from a low speed v = 1.5 m s−1, and maintain the coherence resonance motion within a broad range of wind speed. Thus, it could maintain the large output in the environment of variable-speed wind.
Inference of plasma parameters from fixed-bias multi-needle Langmuir probes (m-NLP)
Authors: Guthrie Joshua , Marchand Richard , Marholm Sigvald 
Published: April 2021

Abstract
New approaches are presented to infer plasma densities and satellite floating potentials from currents collected with fixed-bias multi-needle Langmuir probes (m-NLP). Using synthetic data obtained from kinetic simulations, comparisons are made with inference techniques developed in previous studies and, in each case, model skills are assessed by comparing their predictions with known values in the synthetic data set. The new approaches presented rely on a combination of an approximate analytic scaling law for the current collected as a function of bias voltage, and multivariate regression. Radial basis function regression (RBF) is also applied to Jacobsen et al’s procedure (2010 Meas. Sci. Technol.
21 085902) to infer plasma density, and shown to improve its accuracy. The direct use of RBF to infer plasma density is found to provide the best accuracy, while a combination of analytic scaling laws with RBF is found to give the best predictions of a satellite floating potential. In addition, a proof-of-concept experimental study has been conducted using m-NLP data, collected from the Visions-2 sounding rocket mission, to infer electron densities through a direct application of RBF. It is shown that RBF is not only a viable option to infer electron densities, but has the potential to provide results that are more accurate than current methods, providing a path towards the further use of regression-based techniques to infer space plasma parameters.
Retracted: Synthesis and surface modification of mesoporous metal-organic framework (UiO-66) for efficient pH-responsive drug delivery and lung cancer treatment
Authors: Xie Canguo , Guo Bitao , You Hua , Wang Zhengyan , Leng Qiqi , Ding Lijun , Wang Qi 
Published: April 2021

Abstract
This paper applied mesoporous metal-organic frameworks (MOFs) of UiO-66 particles for pH-responsive doxorubicin (DOX) delivery and cancer treatment. Mesoporous structured UiO-66 MOFs were synthesized, and carboxymethylcellulose (CMC) was loaded for sensitive pH response and also as a linker to encapsulate the chemotherapeutic drug of DOX. The composite of UiO-66/CMC@DOX was synthesized, and the loading capacity was as high as 45 μg DOX per mg of the carrier. The structure and crystalization of the UiO-66 MOFs were determined by the Transmitting Electron Microscope (TEM) and x-ray diffraction methods, while the loading of CMC and DOX was inspected by Fourier Transform InfraRed (FT-IR) and UV–vis spectroscopy. The DOX release from UiO-66/CMC@DOX was tested under different pH at 37 °C. The DOX accumulative release could reach 78% under the pH of 5. A lower pH was more favorable for DOX release due to the CMC shrinking and higher DOX solubility in an acidic environment. The cytotoxicity study indicated that, under the DOX concentration of 4 μg ml−1, the A549 cell (Lung Carcinoma Cell Line) viability of UiO-66/CMC was 28%, which was lower than that from free DOX solution (47%). UiO-66 MOFs were demonstrated to be an efficient drug delivery carrier for chemotherapeutic drug and release.
Nanotwinning and tensile behavior in cold-welded high-entropy-alloy nanowires
Authors: Cui Yi , Toku Yuhki , Ju Yang 
Published: April 2021

Abstract
Since the fabrication technique for high-entropy alloy (HEA) nanowires/nanopillars is still in its infancy, neither experimental nor modeling analyses of their cold-welding performance have been reported. Based on insights accumulated in our previous experiments and simulations regarding cold-welded metallic nanowires, in this study, the cold-welding performance of HEA nanowires is probed by atomistic simulations. Among different materials, our simulations reveal that extensively twinned structures are formed in CoCrMnFeNi samples, but not in CoCrCuFeNi or Ni samples. The larger fracture strain in certain HEAs is due to the improved ductility around the fracturing area as well as multiple twinning. Unlike in Ni samples, the fracture strains in HEA samples, regardless of being cuboid or cylindrical, are improved by shrinking the sample size. Among different orientations, the [010]-direction monocrystalline nanowires fail at a strain over 0.6, which is almost double that of the [111] direction. The fracture strains in polycrystalline HEA samples are, on average, larger than those in polycrystalline Ni samples. Furthermore, fracture strains in randomly generated polycrystalline HEA samples are more predictable than those in polycrystalline Ni samples with identical grain configurations. As previously reported, dislocation emission is still a prerequisite to fracture in all cold-welded samples.
Z-scheme polyimide/tungsten trioxide aerogel photocatalyst for enhanced photocatalytic CO2 reduction under visible light
Authors: Zhao Xinfu , Yi Xibin , Zhang Jing , Liu Benxue , Yu Shimo , Liu Xiaochan 
Published: April 2021

Abstract
Developing highly efficient and stable photocatalysts is an effective method to achieve CO2 photocatalytic reduction. Herein, PI/WO3 aerogel photocatalyst was prepared by chemical amide reaction coupled with an ethanol supercritical drying technique. The novel aerogel photocatalysts exhibit excellent photocatalytic performance for reducing CO2 into CO. In particular, PI/WO3-10 aerogel photocatalyst shows the highest yield of CO (5.72 μmol g–1 h–1), which is ca 11-fold higher than that of the pristine PI aerogel. The high CO2 reduction activity can be attributed to the Z-scheme structure, which enhances the separation of photo-generated electron–holes, and induces H2O oxidation on WO3 nanosheets and CO2 reduction on PI aerogel. The photocatalytic reaction mechanism of CO2 when using PI/WO3 aerogel photocatalyst is proposed.
Probing the Atmospheric Precipitable Water Vapor with SOFIA. II. Atmospheric Models from ECMWF
Authors: Iserlohe C. , Fischer C. , Vacca W. D. , Fischer N. , Colditz S. , Krabbe A. 
Published: April 2021

Abstract
SOFIA is an airborne observatory for far-infrared astronomy. Although SOFIA flies at altitudes of ∼41,000 feet, any far-infrared observations from within the Earth’s atmosphere are nevertheless hampered by water vapor absorbing the astronomical signal. The atmospheric parameter governing absorption is the total upward precipitable water vapor, PWV. In this paper we investigated if data of the Earth’s atmosphere provided by the European Centre for Medium-Range Weather Forecasts, ECMWF, can be used to determine spatially and time-resolved PWV data to allow a more precise calibration of far-infrared data taken with SOFIA along its flight path. We found that PWV values obtained from ECMWF correlate extremely well with independently determined PWV values obtained with the FIFI-LS instrument onboard SOFIA. We determined maximum observing time intervals (depending on the pressure altitude SOFIA is flying at) within which the upward PWV value changes inflight by less than a certain amount. We also present a new calibration method which enhances data quality and observing efficiency with FIFI-LS significantly. Furthermore our new method is universal and may be applied to data from all of SOFIA's instruments.
Excitation of zonal flow by intermediate-scale toroidal electron temperature gradient turbulence
Authors: Chen Haotian , Tirkas Stefan , Parker Scott E. 
Published: April 2021

Abstract
On the basis of gyrokinetic theory, we derive nonlinear equations for the zonal flow (ZF) generation in intermediate-scale electron temperature gradient (ETG) turbulence (with wavelength much shorter than the ion Larmor radius but much longer than the electron Larmor radius) in nonuniform tokamak plasmas. Both the spontaneous and forced generation of ZFs are kept on the same footing. The resultant Schrödinger equation for the ETG amplitude is characterized by a Navier–Stokes type nonlinearity, which is typically stronger than the Hasegawa–Mima type nonlinearity resulting from the fluid approximation. The physics underlying the three stages of ZF generation process is clarified, and the role of parallel mode structure decoupling is discussed. It is found that ZFs can be more easily excited in the intermediate-scale ETG turbulence than in the short wavelength regime.
Preparedness community and potential of liquefaction due to earthquake occurred in the village baturetno sub-district banguntapan yogyakarta regency
Authors: Kinthen N , Pahleviannur M R , Sari H N , Rizkyandri R , Arozaq M , Suharjo  
Published: April 2021

Abstract
Baturetno village was one of the areas affected by the Yogyakarta earthquake on May 27, 2006 which left thousands dead, seriously injured, and destroyed buildings on the ground. The condition of the Bantul Regency area with hilly nature which has a labile soil structure causes the soil to become unstable and to see the geological conditions, Baturetno Village, Banguntapan District, Bantul Regency has the potential to be threatened by liquefaction caused by the earthquake. The purpose of this study was to identify: (1) the level of knowledge of the people in Baturetno Village regarding liquefaction and earthquakes and (2) the level of community preparedness in Baturetno Village regarding liquefaction and earthquakes. The research method used is a quantitative method with a descriptive approach. The population in this study were all people in Baturetno Village as many as 14,345 people, while the study sample was 99 residents with sampling techniques using systematic stratified sampling techniques. Based on the results of the study it can be concluded that: (1) the level of knowledge of the Baturetno Village community regarding liquefaction and earthquakes is less readily available for total realty with an index value of 40-50, which means that the attitude is not ready and the percentage 57%. Meanwhile, (2) the level of community preparedness is known to be ready to face liquefaction due to earthquakes and mobilization from the community stating that they are prepared in terms of preparedness of 70%, which means that the community is responsive and alert to natural disasters. In accordance with what has been described above, the need for efforts to increase the level of knowledge and preparedness in the face of liquefaction and earthquakes.
Valorising landscape: taking opportunities from drought to ecotourism high-end products
Authors: Haryanti N 
Published: April 2021

Abstract
Naturally, area of Gunungkidul is dominated by unique hilly karst landscape. The area is poor in resources. Quality of soil is low and lack of sufficient water during dry session. Most of inhabitants work in agricultural sector, either as peasant with less than 0.5 Ha or pair workers. Physical characteristic of the area allows only certain species of agricultural crops can be cultivated. A factor for high poverty rate status, it is because limited alternatives for farm diversity are available. Recent phenomenon on climate variability is another threat to rural living, farmers have pushed to adapt to range of weather that most likely leads to significant social and economic long-lasting problems. This paper is aimed to expose gradual shift in the rural setting. It was based on the survey and depth interview data, and was analyzed qualitatively. Agriculture will not provide sufficient income any longer for daily needs. Therefore, despite doing daily farm activities, some farmers have irregular forms to get additional income. They work in construction, home industries, or tourism sectors. Following national trend, growing interests to developing beneficial ways of living in ecotourism sector have been started. This trend is supported by recent exploration to many potential underground caves. Since then, many tourist management groups have grown in the village basis, selling cave-tubing experiences as recreational activities. Ecotourism sector offers sustainable income and valuable alternative out of poverty to many local people. Supported by development of industry 4.0, a powerful means seamlessly connecting people and information, local assets are promoted easily and quickly allowing the most vulnerable groups to escape from severe disaster like drought.
Pentahelix synergy in realizing ecovillage values in the Cijalingan village community of Cicantayan Sukabumi district
Authors: Hidayat M. , Rozak R. W. A. , Kembara M. D. , Baihaki E. 
Published: April 2021

Abstract
In 21st century, people must be able to think HOTS (Higher Order Thinking Skills). HOTS thinking greatly influences the way of life of the community, especially in developing the region. The central government has supported the community to build independent village by giving village funds. However, this has not been going well because the use of village funds has not been maximized. The use of Pentahelix model is an effort to reach an independent village with the concept of ecovillage. In the study used a descriptive qualitative approach with the main data interview and direct observation. Based on the results of interviews shows that the use of village funds only focus on renovation and development and improvement of village infrastructure. Observation results show that Cijalingan Village has the potential become a tourism village with its natural panorama. The people of Cijalingan Village have handicrafts in the form of sandals. It is very supportive to side with the concept of a tourism village, so that in the end it is able to become an independent village.
Temperature Dependent Minerals as a Tool to Prove High Temperature of a Blind Geothermal System. Case Study: Well “X” at Java Island of Indonesia
Authors: Utomo Darren A. , Abiyudo Rizal , Saputra Isto J. , Irfan Riki , Archady Dalmathias 
Published: April 2021

Abstract
Geology and mineral alteration are studied to review the equilibrium of blind geothermal system in Java Island, Indonesia. The “X” well is a slim hole well that has been drilled to 2000 mMD. Indication of high-temperature geothermal system is observed by pressure-temperature survey and mineral alteration recovered by full core from surface to bottom (2000 mMD). Geologically, this geothermal prospect is situated on a caldera system with the volcanism started since the Lower Pleistocene related to the early stages of magmatic activity of the modern Sunda arc. Multiple eruptions associated with the pre-caldera, syn-caldera, and post-caldera volcanism deployed rock formation which are consisted of andesitic lava series, volcanic breccia, and pyroclastic. Based on the study of mineral alteration, three hydrothermal alteration zones are defined from temperature-dependent minerals to predict reservoir temperatures, smectite zone (T<180°C) from the surface down to 1200 mMD, transition zone (T = 180-220°C) down to 1383 mMD, and illite zone (T>220°C) down to 2000 mMD. Moreover, the hydrothermal alteration zone is mainly used to estimate the depth of clay cap, transition, and reservoir zone for a future appraisal well. Correlating the temperatures and hydrothermal alteration zones could help in proving a high-temperature geothermal system especially in a blind geothermal system.
Geology Assessment of Permeability Distribution in Silangkitang Geothermal Field, North Sumatra, Indonesia
Authors: Satya Drestanta Yudha , Suryantini  , Astra Doddy 
Published: April 2021

Abstract
The Silangkitang (SIL) geothermal system is a fault-controlled and liquid-dominated reservoir associated to a deep heat source. Geology data from recent development drilling and reservoir monitoring demonstrated that the high permeability is concentrated within zone between two strands of Great Sumatra Fault (GSF). These faults are major dextral strike slip system that cross the entire length of Sumatra Island. The fault distribution has been defined by integration and interpretation of tectonic geomorphology, surface geology, and well geology. The highest permeability is controlled by faults and fractures associated with localized releasing steps within west of main Tor Sibohi Fault (TSF). This paper outlines the indication of high permeability zone based on recent geology evaluation outcome.
Cased-hole Gamma Ray Log Assessment and Application to Support Reservoir Characterization at Salak Field in Indonesia
Authors: Putra Fanji Junanda , Talita Ananyamatya Bella 
Published: April 2021

Abstract
Gamma Ray (GR) logging is a common wireline activity conducted in the oil & gas industry to identify sand and shale bodies. In the geothermal industry, studies have shown that the GR count has a close correlation with the silica content of rocks. Generally, rocks with high silica content (i.e., felsic) will have relatively higher GR count than rocks with low silica content (i.e., mafic). In the reservoir section of geothermal field, very few (to almost none) rocks cuttings are obtained because mud loss normally occurred. Therefore, another dataset is required to identify lithologies/formations and GR log is one of the continuous datasets in the reservoir hole section that may help to solve this problem. At Salak, open-hole GR logs have been obtained during well completion, but these are few compared to the hundreds of wells drilled. In 2017, the GR tool was included in the bottom-hole assembly (BHA) of wireline surveys at Salak, such as Pressure-Temperature (PT) and Pressure-Temperature-Spinner (PTS) and thus, providing an opportunity to collect infill cased-hole GR data. Evaluation of the cased-hole GR logs indicated good quality and correlation with open-hole GR logs and used to support lithology/formation interpretation, especially for the Rhyodacite Marker (RDM) and Marine Sediments and Volcaniclastic (MSV) Formations as both the formations have distinct GR response compared to other formations at Salak.
Scaling in Two-Phase Pipeline (Study Case: Sarulla Geothermal Field)
Authors: Siahaan Mona Natalia , Andhika Muhamad , Berutu Sahat , Smith Alexander 
Published: April 2021

Abstract
Sarulla geothermal field is operating 330MW with the combined cycle plant in Indonesia. During the operation of the facilities, there have been many challenges. One of the most prominent obstacles is scaling in the surface facility. Scale deposition is a common problem in geothermal surface facilities. Temperature changes affect thermodynamics reaction which leads to scaling. Precipitation of silica reduces the diameter of the pipe which also reduces the flow rate in the pipeline. Furthermore, the generation will decrease as a result of decreasing the flow rate. In most cases, scale precipitation occurs downstream which has decreased temperature. This field is experiencing scaling in the two-phase environment although it has a higher temperature and in undersaturated condition. This is caused by the mixing of different pH levels of geothermal fluid into the header. In this case, low pH fluid mixed with neutral fluid which also has high silica content. This study investigates and discusses this phenomenon and types of scaling. The result could be used to understand the precipitation process of silica and how to prevent this from happening in the future.