bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel ratiometric and reversible fluorescent probe based on naphthalimide for the detection of Al3+ and pH with excellent selectivity
Authors: Li Zhuo , Chen Weihong , Dong Liuyan , Song Yan , Li Ronghang , Li Qiang , Qu Dehui , Zhang Hao , Yang Qingbiao , Li Yaoxian
Published: January 2020

A novel ratiometric and reversible fluorescence probe was designed and synthesized. The fluorescent probe recognizes Al3+ to cause a blue shift in the fluorescence emission spectrum. Fluorescence probe can be used as a sensor to detect Al3+ in living cells and Zebra fishes. The probe can detect the pH value when the alkalinity range was 8–10.
RNA–DNA hybrid nanoshapes that self-assemble dependent on ligand binding
Authors: Chen Shi , Hermann Thomas
Published: January 2020

Composite nanoshapes self-assemble from RNA and DNA modules by coupling ligand binding to the formation of circularly closed structures.
Bimetallic gold–silver nanoparticles mediate bacterial killing by disrupting the actin cytoskeleton MreB
Authors: Jena Prajna , Bhattacharya Maireyee , Bhattacharjee Gourab , Satpati Biswarup , Mukherjee Prasun , Senapati Dulal , Srinivasan Ramanujam
Published: January 2020

The actin cytoskeleton is required for the maintenance of the cell shape and viability of bacteria.
Regulating the single-molecule magnetic properties of phenol oxygen-bridged binuclear lanthanide complexes through the electronic and spatial effect of the substituents
Authors: Liu Xiang-Wen , Wu Zhuo , Chen Ji-Tun , Li Li , Chen Peng , Sun Wen-Bin
Published: January 2020

Series of Dy2 SMMs displayed the nearly maximum tenfold increase in energy barrier and the hysteresis temperature increased from zero to 2.5 K using the electronic and spatial effect on substituent of the bridging ligand and co-ligands.
Highly efficient singlet oxygen generation, two-photon photodynamic therapy and melanoma ablation by rationally designed mitochondria-specific near-infrared AIEgens
Authors: Zheng Zheng , Liu Haixiang , Zhai Shaodong , Zhang Haoke , Shan Guogang , Kwok Ryan T. K. , Ma Chao , Sung Herman H. Y. , Williams Ian D. , Lam Jacky W. Y. , Wong Kam Sing , Hu Xianglong , Tang Ben Zhong
Published: January 2020

Mitochondria-targeted photosensitizers with highly efficient singlet oxygen generation, bright near-infrared AIE and good two-photon absorption are obtained through ingenious molecular engineering for cancer cell-selective photodynamic therapy.
Circulating miR-206 and Wnt-signaling are associated with cardiovascular complications and a history of preeclampsia in women
Authors: Schlosser Kenny , Kaur Amanpreet , Dayan Natalie , Stewart Duncan J. , Pilote Louise , Delles Christian
Published: January 2020

Women with a history of preeclampsia (PE) have increased risk of cardiovascular disease (CVD) later in life. However, the molecular determinants underlying this risk remain unclear. We sought to understand how circulating miRNA levels are affected by prior PE, and related to biological pathways underpinning cardiovascular disease. RNA sequencing was used to profile plasma levels of 2578 miRNAs in a retrospective study of women with a history of PE or normotensive pregnancy, in two independent cohorts with either acute coronary syndrome (ACS) (n = 17–18/group) or no ACS (n = 20/group). Differential miRNA alterations were assessed in relation to a history of PE (within each cohort) or ACS (across cohorts), and compared with miRNAs previously reported to be altered during PE. A history of PE was associated with altered levels of 30 and 20 miRNAs in the ACS and non-ACS cohorts, respectively, whereas ACS exposure was associated with alterations in 259 miRNAs. MiR-206 was identified at the intersection of all comparisons relating to past/current PE and ACS exposure, and has previously been implicated in atherogenic activities related to hepatocytes, vascular smooth muscle cells and macrophages. Integration of all differentially altered miRNAs with their predicted and experimentally validated targets in silico revealed a number of highly targeted genes with potential atherogenic functions (including NFAT5, CCND2 and SMAD2), and one significantly enriched KEGG biological pathway (Wnt signaling) that was shared between all exposure groups. The present study provides novel insights into miRNAs, target genes and biological pathways that may underlie the long-term cardiovascular sequelae of PE.
Rectified Gaussian noise estimation and its use in position sensitive detection systems
Authors: Noh J.‐H.
Published: January 2020

Noise estimation of an amplified sensor output is essential for not only operating the position sensitive detection (PSD) system efficiently but also for improving accuracy. The noise can vary from device to device and depends on the operating environment; thus, its estimation should be conducted in real time. However, the rectified noise owing to the limited dynamic range of the analogue‐to‐digital converter makes this estimation challenging. This Letter presents the use of noise parameter estimation, such as non‐uniform offset compensation, detection threshold calculation, and variance estimation of a beam's estimated angular position in PSD systems. Moreover, the estimation of rectified Gaussian noise parameters is proposed. Experiments with the implemented PSD system verify the performance of the proposed estimation method for the rectified Gaussian noise characteristics and the offset compensation method for the estimated beam position.
User‐feedback based robust and simplified damping control for affordable transfemoral prosthesis
Authors: Sharma R. , Singh D. , Tiwari A. , Joshi D.
Published: January 2020

The high cost of the powered prosthetic leg is one of the challenges for the lower‐limb amputees in developing countries. This Letter presents a robust design and simplified control strategy for a cost‐effective magnetorheological‐damper‐based prosthetic leg for transfemoral amputees. Herein, a simple sensing technique having an accelerometer and two force‐sensing resistors is incorporated to obtain the gait events. Based on gait phase detection, a simplified if‐else rule‐based control strategy is implemented. A comparison between angles of prosthetic and intact knee is presented to demonstrate the effectiveness of the proposed design.
BER analysis of non‐orthogonal multiple access‐based cognitive butterfly network
Authors: Üstünbaş S. , Aygölü Ü.
Published: January 2020

In this Letter, the non‐orthogonal multiple access (NOMA) technique is applied to the cognitive butterfly network, where a secondary relay assists a primary transmitter–receiver pair in the lack of a direct link between them to realise spectrum sharing for a secondary transmitter–receiver pair. In this network, the uplink and downlink NOMA principles are combined and the side information from the nearer transmitters is exploited for better successive interference cancellation (SIC) at the receivers. The end‐to‐end bit error probability (BEP) is analytically derived for both users and the results are approved via computer simulations by considering imperfect SIC. The better BEP performance provided by NOMA compared to a reference orthogonal multiple access protocol is demonstrated.
Investigation of biasing conditions and energy dissipation in electrochemically controlled capillarity liquid metal electronics
Authors: Wang Meng , Lei Wen Tai , Dong Jian , Dickey Michael D. , Adams Jacob J.
Published: January 2020

This Letter investigates the trade‐off between the biasing conditions (biasing current and electrolyte concentration) and energy dissipation in high‐frequency liquid metal electronics using electrochemically controlled capillarity (ECC). ECC can control the interfacial tension of liquid metal via DC current as a method to move the metal in capillaries. It requires a conductive electrolyte to facilitate the electrochemical reactions. Here, the authors measure the withdrawal rate of liquid metal under different biasing currents and electrolyte concentrations. The results indicate that a larger biasing current and a more concentrated electrolyte induce a faster withdrawal motion of liquid metal. This Letter also explores the change of antenna efficiency when different electrolyte concentrations are chosen. The selection of electrolyte concentration for high‐antenna efficiency conflicts with the need for fast withdrawal speed and low‐DC power consumption of the liquid metal system, therefore requiring a balance among the various parameters when ECC is applied in practical liquid metal electronics.
Pole‐to‐ground fault current estimation in symmetrical monopole high‐voltage direct current grid considering modular multilevel converter control
Authors: Tao Yan , Li Baohong , Liu Tianqi
Published: January 2020

This Letter proposed a novel method to accurately estimate the pole‐to‐ground fault current in symmetrical monopole high‐voltage direct current grids. To avoid simulation's time consuming and difficult modelling, the converter is equivalent to the simple resistor LC circuit, and the state space including negative pole and positive pole is established for pole‐to‐ground current estimation. To enhance the accuracy of the estimation, the influence of converter control is considered in the estimation. It is found that the dc voltage control mode would impact the fault current rather than the power control mode. In addition, the accuracy can be improved a lot when the control is taken into consideration in fault current estimation. The simulations validate the proposed method finally.
Data‐driven short‐circuit detection and location in microgrids using micro‐synchrophasors
Authors: Guillen Daniel , Hernandez‐Diaz Alejandro , Mayo‐Maldonado Jonathan C. , Valdez‐Resendiz Jesus E. , Escobar Gerardo
Published: January 2020

Fault detection and location is a challenging issue in microgrid protection, which is increasingly more complex in the presence of distributed generators based on renewable energy, due to their inherent intermittency. In this context, a novel data‐driven approach for fault detection and location in microgrids is proposed, by using graph theory representation and micro‐synchrophasors also known as PMUs. This proposal adopts the conviction to provide an accurate fault location even under variations in short‐circuit levels caused by the intermittency of distributed generators. This is in sharp contrast with traditional short‐circuit rating‐based methods, which are not always advisable due to the intermittent nature of power sources. This work proposes the use of a modelling specification in terms of equilibrium equations, that can reveal not only the underlying physical laws of the netowork, but also the occurrence and location of short circuits based on phasor data. The intermittency of distributed generation is modelled in the proposed approach, which permits to yield trustworthy information either distributed generators are involved in a fault or not. As a consequence, the fault location errors are significantly reduced during the fault location process. The theoretical findings of this proposal are validated via simulation results and experiments using commercial micro‐synchrophasors and hardware‐in‐the‐loop emulation of a realistic microgrid.
Image encryption with cross colour field algorithm and improved cascade chaos systems
Authors: Jia Meng
Published: January 2020

In this study, the critical factor of the chaos system has been analysed to improve the randomicity of the encryption keyspace. Several chaos systems have been integrated together with a linear function to form a much more efficient key sequence generator. This study also presents the cross colour field confusion method which scrambles the pixels among the R G B colour matrixes. In this way, the range of the pixels scrambling map is extended to three matrixes compared to the traditional pixels scrambling schemes which do pixels scrambling in its own colour matrix. The experiment results show that the improved cascade system has better bifurcation diagrams. The cross colour field diffusion algorithm makes the encrypted image has little pixel correlation and no information leakage. The experiment results justify that the novel cross colour confusion scheme with improved chaos systems has a good ability to resist brute force attack, known plain attack, chosen plain text attack, chosen ciphertext attack and differential attack. The security analysis demonstrates that the proposed approach has satisfactory properties in image encryption.
Modelling of continuously distributed target for bistatic synthetic aperture radar imaging
Authors: Chen Xinliang , Fan Yujie , Wei Yangkai , Ding Zegang
Published: January 2020

The point target model is widely used in the synthetic aperture radar (SAR) imaging simulation. Based on this model, the radar echo of a continuously distributed target can be expressed as the linear summation of the echo of many point targets which are known as scatters. However, the discretisation strategy is problematic. The discretisation grid must be very fine to assure convergence, thus the computation burden is heavy. Moreover, the result depends on how the target is discretised. It is shown that the SAR image generated from this model of the same target is inconsistent when using different sampling strategy. To overcome these drawbacks, a parameterised model is proposed in this study, which not only greatly reduce the amount of calculation, but also guarantee consistency of the results. Finally, the correctness of the proposed model is verified by SAR imaging results from the generated echo data.
Consistent transport properties in multicomponent two-temperature magnetized plasmas
Authors: Wargnier Q. , Alvarez Laguna A. , Scoggins J. B. , Mansour N. N. , Massot M. , Magin T. E.
Published: January 2020

Aims.We present a fluid model that has been developed for multicomponent two-temperature magnetized plasmas in chemical non-equilibrium for the partially to fully ionized collisional regimes. We focus on transport phenomena with the aim of representing the atmosphere of the Sun.

Methods.This study is based on an asymptotic fluid model for multicomponent plasmas derived from kinetic theory, yielding a rigorous description of the dissipative effects. The governing equations and consistent transport properties are obtained using a multiscale Chapman-Enskog perturbative solution to the Boltzmann equation based on a dimensional analysis. The mass disparity between free electrons and heavy particles is accounted for, as well as the influence of the electromagnetic field. We couple this model to the Maxwell equations for the electromagnetic field and derive the generalized Ohm’s law for multicomponent plasmas. The model inherits a well-identified mathematical structure leading to an extended range of validity for the Sun’s atmospheric conditions. We compute consistent transport properties by means of a spectral Galerkin method using the Laguerre-Sonine polynomial approximation. Two non-vanishing polynomial terms are used when deriving the transport systems for electrons, whereas only one term is retained for heavy particles.

Results.In a simplified framework where the plasma is fully ionized, we compare the transport properties for the lower solar atmosphere to conventional expressions for magnetized plasmas attributed to Braginskii, showing a good agreement between both results. For more general partially ionized conditions, representative of the lower solar atmosphere, we compute the muticomponent transport properties corresponding to the species diffusion velocities, heavy-particle and electron heat fluxes, and viscous stress tensor of the model for a helium-hydrogen mixture in local thermodynamic equilibrium. The model is assessed for the 3D radiative magnetohydrodynamic simulation of a pore at the Sun photosphere. The resistive term is found to dominate mainly the dynamics of the electric field at the pore location. The battery term for heavy particles appears to be higher at the pore location and at some intergranulation boundaries.
The high-energy environment and atmospheric escape of the mini-Neptune K2-18 b
Authors: dos Santos Leonardo A. , Ehrenreich David , Bourrier Vincent , Astudillo-Defru Nicola , Bonfils Xavier , Forget François , Lovis Christophe , Pepe Francesco , Udry Stéphane
Published: January 2020

K2-18 b is a transiting mini-Neptune that orbits a nearby (38 pc), cool M3 dwarf and is located inside its region of temperate irradiation. We report on the search for hydrogen escape from the atmosphere K2-18 b using Lyman-α transit spectroscopy with the Space Telescope Imaging Spectrograph instrument installed on the Hubble Space Telescope. We analyzed the time-series of fluxes of the stellar Lyman-α emission of K2-18 in both its blue- and redshifted wings. We found that the average blueshifted emission of K2-18 decreases by 67% ± 18% during the transit of the planet compared to the pre-transit emission, tentatively indicating the presence of H atoms escaping vigorously and being blown away by radiation pressure. This interpretation is not definitive because it relies on one partial transit. Based on the reconstructed Lyman-α emission of K2-18, we estimate an EUV irradiation in the range 101 − 102 erg s−1 cm−2 and a total escape rate on the order of 108 g s−1. The inferred escape rate suggests that the planet will lose only a small fraction (< 1%) of its mass and retain its volatile-rich atmosphere during its lifetime. More observations are needed to rule out stellar variability effects, confirm the in-transit absorption, and better assess the atmospheric escape and high-energy environment of K2-18 b.
Management of Fishing Operational on Lift Net in Lekok Waters, Pasuruan Regency, East Java
Authors: Satrya Dimas
Published: January 2020

Indonesia is an archipelago country, catching fish is one of the sectors that is highly evolved in Indonesia. One of the waters in Indonesia which has great fishery potential is Pasuruan Regency in East Java. Lift net is a fishing tool that is still widely used by small-scale fishermen in Indonesia, formed rectangular which was operable in coastal waters at night by using light fishing. The purposes of this article are to investigate how to operate a lift net and to explore deeper about the management of lift net operation in Lekok Waters, Pasuruan Regency. Data collection was done by using observation, interview, active participation and documentation. This research discuss about boat and the equipment, catcher tool components, location, length time of trip, procedures of fishing, types of fish, tools maintenance and business management. Based on the analysis of Revenue Cost Ratio (R/C Ratio) proved R/C ratio is > 1, then the effort of catching fish by using lift net in Lekok Pasuruan is profitable. The value of BEP in units of the unit catchment is 1,278 kg, and the values BEP in-unit rupiah is Rp.9,064,516.
Selected Dominance Plant Species for Increasing Availability Production of Cattle Feed
Authors: Yulianto Roni , Amam  , Ayu Harsita Pradiptya , Wildan Jadmiko Mochammad
Published: January 2020

Production and availability of plant species have an essential role as cattle feed. Feed supplies for animal depend on plant species to produce more preferred types of quantity and quality. The purpose of this study was to select dominance of plant species to increasing productivity and develop grazing area. The study was conducted at field farming with large area ± 1.2 ha, consists of 6 cows, and 10 goats in Bondowoso. Identification of species composition was conducted following method Braun-Blanquet scale using a line transect of 0-70 m at every 10 m interval to determine the adaptation of plant species. The purpose of this study was to determine the population of dominance plant species (%), and as information for the conservation of land areas to increase the availability of animal feed in Jember, East Java. The number of plant species as animal feed were 22, consist of 12 types of grass, 6 types of legumes, and 4 types of weeds. The population of grass species more than 75% consisted of Axonopus compessus (85.71%), Para Grass (82.14%), Bracharia decumben (75.00%), Kyllinga Brevifolia (75.00%), and clover was Centrosema Molle (78.57%). The comparison frequency between plant species consists of grass 57.77%, legumes 22.31%, and weeds 19.92%. The observation diversity of plant height was 17.16 cm, vegetation cover rate was 71%. The findings of this study suggest that Axonopus Compessus, Para Grass, Bracharia Decumben, Kyllinga Brevifolia, and Centrosema Molle are the dominance of plant species could increase production, and availability cattle feed in the grazing area.
Assessing the Vulnerability of Farm Households in Yogyakarta to Risks Associated with Climate Change
Authors: Handoyo Mulyo Jangkung , Wahyu Widada Arif , Sugiyarto  , Masyhuri
Published: January 2020

Agriculture sustainability has been threatened by climate change. Climate change affects not only food production but also harms the social life of farm households. This paper assesses farmers’ perceptions of climate change issues, the scale of its impact on farm households, and measures the sensitivity, adaptation strategies, and the livelihoods vulnerability of farm households in Yogyakarta. Two hundred and four farm households representing coastal and mountainous farm households were interviewed using a structured questionnaire. Descriptive analysis and the Livelihoods Vulnerability Index (LVI) methods are used to analyze data. The results show that most farm households have low awareness of the issue of climate change as well as low-scale exposure and sensitivity to climate change. Meanwhile, the level of adaptation strategies for coastal farm households is slightly higher (better) than mountainous farm households. Livelihoods vulnerability indexes reveal that agricultural households in coastal and mountainous areas are at a low level of vulnerability related to climate change.
Celebrity Brand Ambassador and e-WOM as Determinants of Purchase Intention: A Survey of Indonesian Celebrity Cake
Authors: Putri Utami Safira , Setyowati Nuning , Mandasari Putriesti
Published: January 2020

This research aims to analyze the influence of celebrity brand ambassador, e-WOM quality, e-WOM quantity, and sender’s expertise on consumers’ purchase intention of celebrity cake in Indonesia (Yogyakarta, Solo, and Semarang). The research areas are purposively chosen while a hundred of respondents are determined conveniently. Using the regression analysis as an analytical tool, the study shows that the model is significant, while the Celebrity brand ambassador and e-WOM quality have a positive influence on consumers’ purchase intention of Indonesian celebrity cake. Celebrities as the brand ambassadors are known for their familiarity, good personalities, good interaction with the consumers (during promotion), and success in delivering the specific facts about celebrity cake. Meanwhile, viewing online reviews (clarity, understandability, credibility, reasonability) is helpful for consumers in building their confidence in purchase intention. The most influential variable on consumers’ purchase intention of celebrity cake is a celebrity brand ambassador, based on the value of B in the Unstandardized Coefficients’ table is 0.360 greater than other variables.
Deep Learning Methods On Neutron Scattering Data
Authors: Song Guanghan , Porcar Lionel , Boehm Martin , Cecillon Franck , Dewhurst Charles , Le Goc Yannick , Locatelli Jérome , Mutti Paolo , Weber Tobias
Published: January 2020

Recently, by using deep learning methods, a computer is able to surpass or come close to matching human performance on image analysis and recognition. This advanced methods could also help extracting features from neutron scattering experimental data. Those data contain rich scientific information about structure and dynamics of materials under investigation. Deep learning could help researchers better understand the link between experimental data and materials properties. Moreover,it could also help to optimize neutron scattering experiment by predicting the best possible instrument configuration. Among all possible experimental methods, we begin our study on the small-angle neutron scattering (SANS) data and by predicting the structure geometry of the sample material at an early stage. This step is a keystone to predict the experimental parameters to properly setup the instrument as well as the best measurement strategy. In this paper, we propose to use transfer learning to retrain a convolutional neural networks (CNNs) based pre rained model to adapt the scattering images classification, which could predict the structure of the materials at an early stage in the SANS experiment. This deep neural network is trained and validated on simulated database, and tested on real scattering images.
Metu-Defocusing Beamline : A 15-30 Mev Proton Irradiation Facility and Beam Measurement System
Authors: Bilge Demirkoz M. , Seckin Caner , Avaroglu Akanay , Bulbul Besna , Uslu Pelin , Kılıc Erinc , Orhan Yusuf , Akcelik Selen , Yigitoglu Merve , Saral Caglar , Uzun Duran Selcen , Kılıc Ugur , Efthymiopoulos Ilias , Berkay Poyrazoglu Anıl , Albarodi Abdulrahman , Celik Nazire
Published: January 2020

Middle East Technical University – Defocusing Beam Line (METU-DBL) project is an irradiation facility providing 15 MeV to 30 MeV kinetic energy protons for testing various high radiation level applications, ranging from Hi-Lumi LHC upgrade, space electronic components to nuclear material research. The project located inside the premises of the TAEA (Turkish Atomic Energy Agency) SANAEM (Saraykoy Nuclear Education and Research Center) close to Ankara, provides users a wide selectable flux menu (105–1010 p/cm2/s). The facility is now being commissioned and the facility will be providing a large test area (20 cm x 15 cm) for material, detector and electronics tests. The proton beam is monitored along the beamline using aluminum oxide screens and the flux and uniformity is measured using three detectors attached to the robotic system for cross- checks. A fiber scintillator detector scans the large irradiation area while small area diamond detector and Timepix3 detector are used for spot checks for calibration. Several samples can be radiated simultaneously inside the irradiation area and the robotic system provides 5 separate holders for samples which can be moved in or out, providing users flexibility for the desired fluence. This talk will first introduce METU- DBL as a radiation test facility, then discuss the radiation monitoring of the beam area and the radiation room, while highlighting how this facility can be used for future testing of materials for radiation tolerance.
Design and development of Ionization Profile Monitor for the Cryogenic sections of the ESS Linac
Authors: Benedetti F. , Abbon P. , Belloni F. , Coulloux G. , Gougnaud F. , Lahonde-Hamdoun C. , Le Bourlout P. , Mariette Y. , Marroncle J. , Mols J.P. , Nadot V. , Scola L. , Tauzin G. , Tarkeshian R. , Thomas C.
Published: January 2020

Saclay CEA/IRFU is working for the delivery of five Non-Invasive Profile Monitors in the frame of the in-kind contribution agreement signed with the European Spallation Source. Neutrons will be produced by spallation reactions of 2 GeV proton beam impinging on a Tungsten target. To accelerate protons a powerful linear accelerator of 5MW is under construction. Diagnostic devices are mandatory tools for the tuning and protection of the machine. The non-invasive profile monitors provide a measurement of the beam profile in transverse directions to the beam propagation. This project raises several physical and technical challenges including low signal detection of ions or electrons, profile distortions induced by the beam Space Charge effect and non-uniformities of electric field. Simulation and model of the critical aspects of the detector have been performed in order to prove the performance and the feasibility of the detector. A series of prototypes has been built with different readout types, and tested in real conditions at the 3MeV proton accelerator IPHI. All of them show some advantages and drawbacks revealed by the tests in real beam conditions. In this paper we present the results of the tests for the various configuration readout systems to agree with the model and simulation of the detector. In concluding remarks, we will discuss the performance of the prototypes and point out the camerabased one to be the more suitable for the final design.
System noise of a digital pulse processing module for nuclear instrumentation
Authors: Ma Y , Fischer W-J. , Henniger J. , Weinberger D. , Kormoll T.
Published: January 2020

Digital pulse processing finds a widespeed use in nuclear instrumentation. This work presents a digital pulse processing (DPP) module based on an FPGA and a 16-bit 125 MHz ADC and analyses the system noise distribution by acquired digital data using this system. A moving average filter is utilized to suppress the system noise of the DPP module. Furthermore, digital trapezoidal filter is applied for the use with a charge sensitive preamplifier with High Purity Germanium (HPGe) detector. The energy spectrum and corresponding resolution are demonstrated with a scintillation and semiconductor detector.
Consideration Factors in Application of Thermocouple Sensors for RCS Temperature Instrumentation
Authors: Hwang Inkoo , Cheon Sewoo , Park Wonman
Published: January 2020

Because of harsh radiated environmental conditions, it is necessary to use thermocouples (TCs) in the temperature instrumentation channels of a reactor coolant system (RCS) in an integrated pressurized water reactor vessel. Conventionally, resistance temperature detectors (RTDs) have been adopted for RCS temperature measurement.

Therefore, we have conducted an analysis and review of instrumentation error factors in the measurement circuits of RTD and TC sensors to specify the influence on measurement accuracy for application of TCs instead of RTDs for RCS temperature instrumentation.

From the review and analysis results, it is anticipated that a measurement accuracy deterioration would be an issue and that a drift range should be investigated for the anticipated operational temperature conditions.
Impact of the cross section library on 93mNb activity in VVER-1000 reactor dosimetry
Authors: Haroková P. , Lovecký M.
Published: January 2020

One of the objectives of reactor dosimetry is determination of activity of irradiated dosimeters, which are placed on reactor pressure vessel surface, and calculation of neutron flux in their position. The uncertainty of calculation depends mainly on the choice of nuclear data library, especially cross section used for neutron transport and cross section used as the response function for neutron activation. Nowadays, number of libraries already exists and can be still used in some applications. In addition, new nuclear data library was recently released. In this paper, we have investigated the impact of the cross section libraries on activity of niobium, one of the popular materials used as neutron fluence monitor. For this purpose, a MCNP6 model of VVER-1000 was made and we have compared the results between 14 commonly used cross section libraries. A possibility of using IRDFF library in activation calculations was also considered. The results show good agreement between the new libraries, with the exception of the most recent ENDF/B-VIII.0, which should be further validated.
Confirmation of Nuclear Heating Rate for Installation of Cold Neutron Source at HANARO
Authors: Myong-Seop Kim , Byung-Gun Park
Published: January 2020

In order to determine the capacity of the cold neutron source refrigerator of HANARO, the nuclear heating rate at CN vertical hole is measured by using the heat-flow calorimetric method and confirmed by the calculation. The heating rate measurement device of HANARO was composed of a calorimeter sensor, an air containing aluminum sleeve for fitting the sensor to the CN hole, aluminum weight and a lead wire assembly. The calorimeter sensor consists of a cylindrical Al sample and container, two thermocouples and the electric heater for the calibration of the calorimeter. The sample is separated by an air gap from the Al container surrounded by an air containing Al sleeve. After installation of the calorimeter at a measurement position of HANARO, the heat transfer inside the calorimeter was simulated by the electric heating for the sample. The nuclear heating rates at the CN hole were determined at three reactor powers of 1, 4 and 8 MW by using the calibration curve and the temperature measurements at each reactor power. The measured nuclear heating rate per unit mass of Al sample at 8 MW reactor power is 0.143 W/g and it is equivalent to the 0.494 W/g at 30 MW. The nuclear heating rate was calculated by using the MCNP code. The calculation model for the whole facility including the reactor core and the reflector tank were established. In the calculation procedure, the heat generations by various radiations were evaluated with considering the prompt, delayed and activation effects. The measured heating rate was reasonably well supported by the calculation using the cold neutron facility design code. It will be very useful for the moderator cell of cold neutron source of HANARO.
Comparison of the Responses of New Reduced-Size Calorimetric Cells Made of Different Structure Materials for High Energy Deposition
Authors: Volte A. , Reynard-Carette C. , Lyoussi A. , Brun J. , Carette M.
Published: January 2020

This paper concerns experimental and numerical works on a new differential calorimeter called CALORRE and validated recently under irradiation conditions in MARIA reactor at low nuclear absorbed dose rate level. Works focus on a specific configuration of CALORRE which was designed especially for the measurement of high nuclear energy deposition rates inside Material Testing Reactors. Due to the high level, a new calibration system was fabricated in order to determine the response of the new configuration under laboratory conditions for a very wide range of electrical power never applied in the literature. The response of the new configuration can be considered linear for this very wide range of electrical power. An analytical calculation shows the contribution of each heat transfer in specific zones. 3D thermal simulations performed by means of COMSOL Multiphysics under irradiation conditions give the predictions of the calorimeter behavior under real conditions (up to 20W.g−1).
Performance of Custom-Made Very High Temperature Thermocouples in the Advanced Gas Reactor Experiment AGR-5/6/7 during Irradiation in the Advanced Test Reactor
Authors: Palmer A. J. , Skifton R. S. , Scervini M. , Haggard D. C. , Swank W. D.
Published: January 2020

The Advanced Gas Reactor-5/6/7 (AGR-5/6/7) experiment is the fourth and final experiment in the AGR experiment series and will serve as the formal fuel qualification test for the TRISO fuels under development by the U.S. Department of Energy. Certain locations in this experiment reach temperatures higher than any of the previous AGR tests, up to 1500°C. Such extreme temperatures create unique challenges for thermocouple-based temperature measurements. High-temperature platinum-rhodium thermocouples (Types S, R, and B)and tungsten-rhenium thermocouples (Type C) suffer rapiddecalibration due to transmutation of the thermoelements fromneutron absorption. For lower temperature applications, previousexperience with Type K thermocouples in nuclear reactors haveshown that they are affected by neutron irradiation only to alimited extent. Similarly, Type N thermocouples, which are morestable than Type K at high temperatures, are only slightly affectedby neutron fluence. Until recently, the use of these nickel-basedthermocouples was limited when the temperature exceeds 1050°Cdue to drift related to phenomena other than nuclear irradiation.Recognizing the limitations of existing thermometery to measuresuch high temperatures, the sponsor of the AGR-5/6/7 experimentsupported a development and testing program for thermocouplescapable of low drift operation at temperatures above 1100°C. High Temperature Irradiation Resistant Thermocouples (HTIR-TCs)based on molybdenum/niobium thermoelements have been underdevelopment at Idaho National Laboratory (INL) since circa 2004. A step change in accuracy and long-term stability of thisthermocouple type has been achieved as part of the AGR-5/6/7thermometry development program. Additionally, long-termtesting (9000+ hrs) at 1250°C of the Type N thermocouplesutilizing a customized sheath developed at the University ofCambridge has been completed with low drift results. Both theimproved HTIR and the Cambridge Type N thermocouple typeshave been incorporated into the AGR-5/6/7 test, which beganirradiation in February 2018 in INL’s Advanced
Developing and testing a miniature fiber-coupled scintillator for in-core neutron counting in CROCUS
Authors: Vitullo Fanny , Lamirand Vincent , Mosset Jean-Baptiste , Frajtag Pavel , Pakari Oskari , Gregory Perret , Pautz Andreas
Published: January 2020

An advanced neutron detection system for highly localized measurements in nuclear reactor cores was developed and tested in the Laboratory for Reactor Physics and System Behaviour (LRS) at the École polytechnique fédérale de Lausanne (EPFL), Switzerland, in close collaboration with the Detector group of the Laboratory for Particle Physics (LTP) at the Paul Scherrer Institute (PSI), Switzerland. The miniature-size detector is based on the coupling of a ZnS:6LiF scintillator/converter screen of 1 mm2and 0.2 mm thickness with a 10-m optical fiber, the latter being connected to a silicon photomultiplier (SiPM). In this development version, the output signal is processed via analog read-out electronics. The present work documents the characterization of a detection system prototype in the mixedradiation fields o f t he C ARROUSEL f acility a nd i ts t esting in the CROCUS zero-power reactor operated at LRS. The fibercoupled scintillator shows a linear response with the reactor power increase up to 6.5 W (i.e. around 108cm-2s-1total neutron flux), with a s ubsequent l oss o f l inearity d ue t o e lectronic dead time of the analog system. Nevertheless, the detector shows excellent neutron counting capabilities whether compared to other localized detection systems available at LRS, e.g. miniature fission chambers and an sCVD diamond detector.
The COLIBRI experimental program in the CROCUS reactor: characterization of the fuel rods oscillator
Authors: Lamirand Vincent , Frajtag Pavel , Godat Daniel , Pakari Oskari , Laureau Axel , Rais Adolfo , Hursin Mathieu , Hursin Grégory , Fiorina Carlo , Pautz Andreas
Published: January 2020

The present article presents the mechanical characterization of the fuel rods oscillator developed for the purposes of the COLIBRI experimental program in CROCUS. COLIBRI aims at investigating the radiation noise related to fuel vibrations. The main motivation is the increased amplitudes in the neutron noise distributions recorded in ex- and in-core detectors that have been observed in recent years in Siemens pre-Konvoi type of pressurized water reactors. Several potential explanations have been put forward, but no definitive conclusions could yet be drawn. Among others, changes in fuel assembly or pin vibration patterns, due to recent modifications of assembly structural designs, were pointed out as a possible cause. Computational dynamic tools are currently developed within the Horizon 2020 European project CORTEX, to help with understanding the additional noise amplitude. The COLIBRI program is used for their validation. An in-core device was designed, tested, and licensed between 2015 and 2019 for fuel rods oscillation in CROCUS, in successive steps from out-of-pile tests with dummy fuel rods to critical in-core tests. The characterization of its mechanical behavior is presented, in air and in water, and as a function of the load, for safety and experimental purposes. The device allows simultaneously oscillating up to 18 fuel rods. The maximum oscillation amplitude is 5 mm, while the maximum allowed frequency is 2 Hz, i.e. in the frequency range in which the induced neutron flux fluctuations are most pronounced in nuclear power plants.
Power calibration methodology at the CROCUS reactor
Authors: Lamirand Vincent , Laureau Axel , Pakari Oskari , Frajtag Pravel , Pautz Andreas
Published: January 2020

In the present article, we detail the method used to experimentally determine the power of the CROCUS zero-power reactor, and to subsequently calibrate its ex-core monitor fission chambers. Knowledge of the reactor power is a mandatory quantity for a safe operation. Furthermore, most experimental research programs rely on absolute fission rates in design and interpretation – for instance, tally normalization of reaction rate studies in dosimetry, or normalization of power spectral density in neutron noise measurements. The minimization of associated uncertainties is only achieved by an accurate power determination method. The main experiment consists in the irradiation, and therefore, the activation of several axially distributed Au-197 foils in the central axis of the core, which activities are measured with a High-Purity Germanium (HPGe) gamma spectrometer. The effective cross sections are determined by MCNP and Serpent Monte Carlo simulations. We quantify the reaction rate of each gold foil, and derive the corresponding fission rate in the reactor. The variance weighted average over the distributed foils then provides a calibration factor for the count rates measured in the fission chambers during the irradiation. We detail the calibration process with minimization of respective uncertainties arising from each sub-step, from power control after reactivity insertion, to the calibration of the HPGe gamma spectrometer. Biases arising from different nuclear data choices are also discussed.
Usage of multiple fission cells for neutron flux measurements during rod-insertion method
Authors: Lengar Igor , Rupnik Sebastjan , Žohar Andrej , Merljak Vid , Kromar Marjan , Snoj Luka
Published: January 2020

The measurements of physical parameters of the TRIGA reactor and Nuclear power plant Krško (NEK) reactor cores have been in the past performed on hand of the neutron flux signal obtained from uncompensated ionization cells and by employment of the a digital meter of reactivity (DMR). At the TRIGA reactor only one ionization cell is currently used for flux measurements. During the insertion of one control rod the neutron flux distribution is significantly altered affecting the flux measurements of inserting different control rods. The problem is presently solved by assigning a correction factor to each control rod what introduces an additional uncertainty.

In the present paper the implementation of four fission cells for reactivity measurements is presented. In this way determining the correct gamma background and its subtraction, performed by DMR algorithms, becomes less important as previously by using ionization chambers. The larger number of detectors also reduces the flux redistribution effects on the signal during individual control rod movements.
Design by numerical simulation of an in situ alpha spectrometer operating at ambient air pressure
Authors: Degrelle D. , Venara J. , Ben Mosbah M. , Cuozzo M. , Mahé C. , Serrano R.
Published: January 2020

Alpha emitters are usually identified and quantified by alpha spectrometry measurements in a vacuum chamber performed in laboratory environments. This study shows that transuranic elements can be distinguished under ambient conditions using a grid collimator. The aim of this work was to use numerical simulations with the MCNP6 code to design a grid with a resolution high enough to differentiate the same radionuclide combinations as alpha spectrometry in a vacuum chamber, namely 239Pu + 240Pu, 241Am + 238Pu and 244Cm. Results show that a compromise is required to obtain the best performances in terms of energy resolution and detection efficiency, leading to the choice of two hexagonal grid collimators. The first has a collimation height of 0.5 cm and an apothem of 1 mm. Laboratory tests on electrodeposited sources show that the target radionuclides can be identified without prior deconvolution, with an energy resolution of about 70 keV and a detection efficiency of 0.74% at incident energies of 5–6 MeV. The second grid has the same collimation height but a coarser mesh with an apothem of 2 mm. In this case, the alpha peaks are still distinguishable, but with a lower resolution of 125 keV. The detection efficiency is three times higher however.
Improving Activity Estimation in Passive Gamma Scanning for Radioactive Waste Drums
Authors: Vax E. , Marcus E. , Mazor T. , Kadmon Y. , Osovizky A.
Published: January 2020

A method to improve radioactive waste drum activity estimation in Segmented Gamma Scanning (SGS) systems was developed for homogenous content. We describe a method to quantify the activity of spatially distributed gamma-emitting isotopes (‘hot spots’) in homogenous content waste drums without the use of a collimator. Instead of averaging all the detector's readings we treat it as many different spatial samples as if we have multiple detectors surrounding the waste drum ("virtual detectors"). From these readings, we form a general linear model. Next, we derive the Maximum Likelihood Estimator (MLE) for the multiple sources position and activity. We solve this hyper-dimensional search problem using an Alternating Projections (AP) technique which transforms the problem into a simpler one-dimensional maximization problem. We tested this method using a mathematical simulation with a various number of sources, at random activities and positions for several energy bands. The preliminary results are consistent and show large improvement of the accuracy with comparison to industrial SGS systems and the same accuracy as new methods which exploits the spatial samples. Furthermore, since this method eliminates the need for heavy led collimator, none of the sources is blocked for the whole measurement period, which provides increased count rates and decreases the total measurement time.
Preliminary Study on Improving Resolution of D-T Neutron Radiography based on Associated Alpha and Coded Source Imaging Methods
Authors: Wang Sheng , Wu Yang , Huo Heyong , Li Hang , Wu Chunlei , An Li , Tang Bin , Li Zhenghong
Published: January 2020

Limitations of fast neutron radiography include low detection efficiency and poor spatial resolution. D-T neutron radiography is one compact fast neutron radiography method. Based on D-T associated alpha particle method and coded source imaging method, we indicate one new method to improve resolution of D-T neutron radiography. This method could get distribution of D-T neutrons by detecting alpha particles. Without real coded mask, the D-T radiography structure is considered as coded source imaging of fast neutrons. With reconstruction method, the real object could be reconstructed from projections. One prospect setup of D-T associated alpha neutron source has been carried out with Monte-Carlo simulation. The projection images of two different situations are collected and reconstruction results show that it’s possible to improve image quality of D-T neutron radiography.