bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Total Factor Productivity Evaluation of Chinese Power Grid Enterprises
Authors: Xiao Xia , Song Haiyun , Qian Chengchen
Published: June 2020

The total factor productivity research on the micro level is to analyze an enterprise’s real input and output, choose an appropriate measurement method, and accurately measure its input-output level. Based on the “three responsibilities” of Chinese power grid enterprises, this paper constructs a systematic and scientific input-output factor screening system, determines specific output and input indicators, uses Törnqvist total factor productivity index model to calculate the TFP change of a certain Chinese power grid enterprise in the year of 2008-2017, does a further penetration analysis of input-output changes, verifying that the evaluation model constructed in this paper is effective.
Research on Investment Aid Decision of Transmission Line Project Based on Artificial Intelligent Technology
Authors: Ma Li , Ming Yue , Sun Liping , Zhou Qiupeng , Xiong Yi , Zhou Ming
Published: June 2020

According to analyze the historical transmission line projects from 2016 to 2018, we screen out a series of key influencing factors by principal component analysis. Aimed at the accuracy of grid investment, this report constructs an artificial intelligent investment aid decision model based on neutral network algorithm to predict the construction cost of the transmission line project.
Commissioning and first operating phases of the W7-X quench detection system
Authors: Schneider M , Birus D , Fricke M , Rummel T
Published: June 2020

The quench detection system of the fusion experiment Wendelstein 7-X monitors the superconducting magnet system consisting of 50 non-planar and 20 planar coils, 14 current leads and bus bars. The commissioning phase contained the wiring check of the electrical contact between the 486 quench detection units and the superconducting magnet system, the verification of an unbroken and overlapping monitoring, the balance adjustment of the quench detection unit voltage measuring bridge and the parameterisation of the detection criteria: detection level and integration time. During the operation phases there were two unexpected fast discharges initiated through the trim-coils and a fast decay of the bootstrap current. As a result the interplay of the detection level and integration time was re-evaluated. The quench detection system worked stable over the first both operating phases of W7-X, performed from 2015 to 2018. There were no failures of the quench detection units or other parts of the quench detection system.
The project of the Super Charm-Tau Factory in Novosibirsk
Authors: Barnyakov A.Yu.
Published: June 2020

Electron-Positron collider Super Charm-Tau factory at the Budker Institute of Nuclear Physics (BINP) will operate at energies in center of mass W=2-6 GeV with unprecedented high luminosity of 1035cm−2s−1 and the longitudinal polarization of the electrons at the interaction area. The main purpose of the experiments at the collider is search for effects of CP-violation in the decays of charmed particles, tests of the Standard Model in the decay of the τ-lepton, the search and study of an entirely new forms of matter: glueballs, hybrids, etc. The data, which are planned to record, by 3-4 orders exceed everything that has been recorded so far in any other experiment in this energy range. Conceptual designs of the collider based on crab-waist technique and universal detector are developed and presented. Preliminary physics program are considered. Progress of R&D for detector systems are given.
Two years’ test of a temperature sensing system based on fibre Bragg grating technology for the CMS GE1/1 detectors
Authors: Abbas M. , Abbrescia M. , Abdalla H. , Abu Zeid S. , Agapitos A. , Ahmad A. , Ahmed A. , Ahmed A. , Ahmed W. , Amarjeet S. , Asghar I. , Aspell P. , Avila C. , Babbar J. , Ban Y. , Band R. , Bansal S. , Benussi L. , Bhatnagar V. , Bianco M. , Bianco S. , Black K. , Borgonovi L. , Bouhali O. , Braghieri A. , Braibant S. , Butalla S. , Calzaferri S. , Caponero M. , Cassese F. , Cavallo N. , Chauhan S. , Colafranceschi S. , Colaleo A. , Conde Garcia A. , Dalchenko M. , De Iorio A. , De Lentdecker G. , Dell Olio D. , De Robertis G. , Dharmaratna W. , Dildick S. , Dorney B. , Erbacher R. , Fabozzi F. , Fallavollita F. , Fiorina D. , Fontanesi E. , Franco M. , Galloni C. , Giacomelli P. , Gilmore J. , Gola M. , Gruchala M. , Gutierrez A. , Hadjiiska R. , Hakkarainen T. , Hauser J. , Hoepfner K. , Hohlmann M. , Hoorani H. , Huang T. , Iaydjiev P. , Irshad A. , Iorio A. , Jaramillo J. , Jeong D. , Jha V. , Juodagalvis A. , Juska E. , Kamon T. , Karchin P. , Kaur A. , Kaur H. , Keller H. , Kim H. , Kim J. , Kumar A. , Kumar S. , Kumawat H. , Lacalamita N. , Lee J. , Levin A. , Li Q. , Licciulli F. , Lista L. , Loddo F. , Lohan M. , Luhach M. , Maggi M. , Majumdar N. , Malagalage K. , Malhorta S. , Martiradonna S. , Mccoll N. , McLean C. , Merlin J. , Mishra D. , Mocellin G. , Moureaux L. , Muhammad A. , Muhammad S. , Mukhopadhyay S. , Naimuddin M. , Netrakanti P. , Nuzzo S. , Oliveira R. , Pant L. , Paolucci P. , Park I. , Passamonti L. , Passeggio G. , Peck A. , Petre L. , Petrow H. , Piccolo D. , Pierluigi D. , Raffone G. , Rahmani M. , Ramirez F. , Ranieri A. , Rashevski G. , Ressegotti M. , Riccardi C. , Rodozov M. , Roskas C. , Rossi B. , Rout P. , Ruiz J. D. , Russo A. , Safonov A. , Saltzberg D. , Saviano G. , Shah A. , Sharma A. , Sharma R. , Shopova M. , Simone F. , Singh J. , Soldani E. , Sonnadara U. , Starling E. , Stone B. , Sturdy J. , Sultanov G. , Szillasi Z. , Teague D. , Teyssier D. , Tuuva T. , Tytgat M. , Vai I. , Vanegas N. , Venditti R. , Verwilligen P. , Vetens W. , Virdi A. , Vitulo P. , Wajid A. , Wang D. , Wang K. , Wickramage N. , Yang Y. , Yang U. , Yongho J. , Yoon I. , You Z. , Yu I. , Zaleski S.
Published: June 2020

A temperature monitoring system based on fibre Bragg grating (FBG) fibre optic sensors has been developed for the gas electron multiplier (GEM) chambers of the Compact Muon Solenoid (CMS) detector. The monitoring system was tested in prototype chambers undergoing a general test of the various technological solutions adopted for their construction. The test lasted about two years and was conducted with the chambers being installed in the CMS detector and operated during regular experimental running. In this paper, we present test results that address the choice of materials and procedures for the production and installation of the FBG temperature monitoring system in the final GEM chambers.
A storage ring EDM polarimeter
Authors: Javakhishvili O. , Keshelashvili I. , Mchedlishvili D.
Published: June 2020

The search for electric dipole moments (EDM) of elementary particles is one of the hot topic in contemporary particle physics. The method to measure charged particle EDMs (p,d) is to observe the time development of a polarized beam in a dedicated storage ring (srEDM). This requires a new polarimeter with a special target system which is under development at COSY-Juelich.

The particle detector consists of the two layers: a plastic scintillator for ?E and an inorganic LYSO crystal as a calorimeter. Both systems are readout by multi-pixel SiPM (silicon photo multiplier) arrays. SiPMs operate at significantly lower supply voltages compared to the traditional multi-stage vacuum tubes, simplifying detector construction and operation. The developed calorimeter modules operate at voltages up to 30 Volt. For this purpose a modular, high precision voltage supply has been developed together with slow control and voltage monitoring systems. The fully assembled calorimeter part of the polarimeter has been successfully tested together with its high speed and high-resolution sampling ADC-based readout. All test have been carried out using solid block target. However, the final polarimeter will include a ballistic target system which will be shooting point-like diamond pellet through the beam. The movement of the pellet will be precisely tracked in three dimensions and synchronized with the data acquisition system. This will allow us to reconstruct the polarization profile of the beam. Currently, the mechanical and electrical systems for the pellet target are under development.

Recent achievements and experimental results of this project are summarized and discussed in this paper.
(W)hole new field: the new GEM Time Projection Chamber of ALICE
Authors: Miśkowiec Dariusz
Published: June 2020

The ALICE Time Projection Chamber has just been upgraded by replacing the readout chambers, which cover the two ends of the cylinder, with new detectors based on the Gas Electron Multiplier (GEM) technology. We report here on the related activities at GSI Darmstadt: GEM framing and chamber production, as well as the quality assurance accompanying both procedures.
Prompt gamma imaging in proton therapy - status, challenges and developments
Authors: Wrońska Aleksandra
Published: June 2020

This paper is an overview of the field of proton therapy monitoring in real time using prompt gamma radiation. Different approaches providing either integrated or differential information are described, and their maturity, limitations and clinical usefulness are discussed. In the second part, the SiFi-CC project is briefly introduced, which aims at the development of a Compton camera for prompt gamma imaging, entirely based on fibres made of a heavy, inorganic scintillator read out by silicon photomultipliers. This compact solution offers very good timing properties, high granularity and a modern data acquisition system, addressing previously identified issues.
Autonomous, connected ultrasonic microsystem dedicated to monitoring the pathophysiology of the phonic and respiratory apparatus
Authors: Sawan M , Reda H , Saad N , Bin S , Nassar G
Published: June 2020

This work tackles a combination of two technological fields: “integrated ultrasonic biosensors” and “connected modules” coupled with “Artificial Intelligence” algorithms to provide healthcare professionals with additional indices offering multidimensional information and a “Decision Support” tool. This device comprises a connected telemedical platform (PC or Smartphone) dedicated to the objective and remote assessment of pathophysiological states resulting from dysphonia of laryngeal origin or respiratory failure of inflammatory origin..
Alternative heavy tailed models in seismology
Authors: Felgueiras Miguel , Martins João , Santos Rui
Published: June 2020

Great earthquakes are commonly considered as the ones with moment magnitude (Mw
) above or equal to 8.0. Since these earthquakes can destroy entire communities located near the epicentre, the search of physical laws that explain the energy released by them is an important issue. There is a connection between the radiated energy of an earthquake, its magnitude and its seismic moment (M
0). Thence, when fitting a heavy or an extremely heavy tailed distribution to a seismic moment dataset, we are in fact adjusting a mathematical model which explains the amount of energy released by these great seisms. Therefore, the main goal of this work is to study the more appropriated Pareto based models (the most used family in this field) when explaining the seismic moment of the great earthquakes. With this purpose in mind, we selected two different catalogs that accommodate recent events and are considered more accurate than other catalogs used in previous works. We conclude that the traditional Pareto distribution remains a good choice to deal with this kind of data, but Log-Pareto lead to higher p-values and Location-scale Pareto is better fitted to the biggest events.
Wavelet Transform and Deep Learning approach to predict physico chemical parameters of water
Authors: Silva Hieda Adriana Nascimento , Vinueza Naranjo Paola G. , Lena Patricia Souza Rodrigues , de Araujo Diovanni Moraes , Yomara Pinheiro Pires
Published: June 2020

Alton water reservoir located within the stunning countryside of Suffolk in UK has a history of cyanobacterial bloom, that are single-celled organisms that live in fresh, brackish, and marine water. The traditional approaches to monitoring water reservoirs are often limited by the need for data collection which often is time-consuming and expensive. In addition, Chlorophyll-a, algae and turbidity are important variable for the analysis of water quality, that are significant not only for human populations but also essential for plant and animal diversity. The main objective of this study is to predict these chemico physical parameters from 2014 to 2019 using time series analysis, satellite imagery, wavelet transform and deep learning. The satellites images were used to predict these parameters in Alton reservoir, manually selected samples were employed to validate estimated parameters using Wavelet Neural Networks. The results predicted by the neural network show good results, and good approximation to laboratory results, suggesting that the proposed model is suitable for environmental monitoring, contributing to monitor water quality parameters.
Feedforward and repetitive control of a servo piezo-mechanical hydraulic actuator
Authors: Mercorelli Paolo
Published: June 2020

In this paper a hybrid actuator is proposed. The hybrid actuator consists of a piezo-mechanical structure and a hydraulic ratio displacement. Particular attention is paid to a liquid spring model of the displacement ratio which represents the hydraulic part of the mechanism to control an intake and exhaust valve of a combustion engine. The whole mechanism is controlled using a cascade repetitive control to track a periodic signal combined with a proportional derivative (PD) regulator and a feedforward action. Measured results are shown.
A rigorous derivation of the extended KdV equation
Authors: Berjawi M , ElArwadi T , Israwi S
Published: June 2020

The interesting background and historical development of KdV equations were discussed widely. These equations describe the propagation of water waves in weakly non linear and weakly dispersive medium. Referring to physical derivation of KdV equations, scientists used to impose shallow water equations, thus the formal or physical derivation of KdV equations. However, these equations have rarely been derived rigorously. The aim of this paper is to giving insight into their rigorous mathematical derivation, instead of only referring to. Thereby, a rigorous derivation of two extended KdV equations: one on the velocity, other on the surface elevation. With this aim in mind, the primary research method for this paper will depend on the definition of consistency. Hence, a rigorous justification of new extended KdV equations will be provided thanks to this definition. This result provides a precise mathematical answer to a question raised by several authors in the last years, that is the verification of the extended KdV equations, derived previously, using formal methods.
Computational study of SERS effects in some aliphatic and cyclic carboxylic acids with silver nanomaterials
Authors: Al-Saadi Abdulaziz A.
Published: June 2020

Quantum chemical calculations have been shown to provide convenient means in estimating surface-enhanced Raman scattering (SERS) spectral shifts and the adsorption possibilities associated with such shifts. In a recent work, the computed Raman spectra provided very good agreement with the experimental results for valeric acid. To attain a conclusive picture of the Raman shifts in related molecules, namely, butyric acid, caproic acid, γ-butyrolactone, γ-valerolactone and γ-caprolactone, full optimizations and frequency calculations have been carried out. The vibrational frequency shifts caused by the interaction of these molecules with the Ag4 cluster simulate the experimental shifts with silver nanoparticles (AgNPs). The most prominent shift noticed is in the case of γ-caprolactone through its ether C-O-C group interacting with the silver cluster. Such a shift may be due to the +I effect of the alkyl side chains and corresponds to a theoretical interaction energy and distance of -12.92 kcal/mol and 2.45Å, respectively.
Mathematical modelling of the influence of yield shear stress on blood friction in a turbulent flow
Authors: Bartosik A , Mitura S
Published: June 2020

Measurements of blood rheology indicate that human blood has a yield shear stress. Transport of oxygen in the aorta or a vein depends on blood flow rate. Therefore, it is interesting to find out how blood yield shear stress affects blood transportation if flow is turbulent. The majority of mathematical approaches deal with laminar flow of human blood, which is rather simple compared to turbulent flow modelling. This paper presents a mathematical model of fully developed turbulent flow of human blood in the aorta. The physical model assumes that blood is a non-Newtonian liquid that demonstrates yield shear tress. The main objective of the research is to examine the influence of human blood yield shear stress on turbulent properties, like friction factor, in the aorta. Available blood rheology experimental data for various concentrations of haematocrit were used in order to fit the rheological model. The rheological model together with the momentum equation and the two-equation turbulence model constitute a mathematical model of turbulent flow of human blood. Results of simulations are discussed and presented as figures and conclusions.
Highly stable multivalue collocation methods
Authors: Conte Dajana , D’Ambrosio Raffaele , D’Arienzo Maria Pia , Paternoster Beatrice
Published: June 2020

The paper is focused on the development of A-stable collocation based multivalue methods for stiff problems. This methods are dense output extensions of discrete multivalue methods, since the solution is approximated by a piecewise collocation polynomial with high global regularity. The underlying multivalue method is assumed to be diagonally implicit and with uniform order of convergence, thus it does not suffer from order reduction, as it happens for classical one-step collocation methods. The effectiveness of the approach is also confirmed by the numerical evidence.
On the remainder in the weighted length spectrum for strictly hyperbolic Fuchsian groups
Authors: Gušić Dž
Published: June 2020

In this paper, we consider the remainder in a weighted form of the length spectrum for compact Riemann surfaces of genus greater than or equal to two. Earlier, we conducted a similar research where we applied the Cauchy residue theorem over two different square boundaries, one of which intersected the corresponding critical line, and some, quite complex estimates for the logarithmic derivative of the associated zeta functions of Selberg and Ruelle. The main goal of this paper is to achieve the same length spectrum with the same remainder as in our previous study, but in a much simpler way.
On some comparison of multistep second derivative methods with the multistep hybrid methods and their application to solve integro-differiential equations
Authors: Mehdiyeva G Yu , Ibrahimov V R , Imanova M N
Published: June 2020

As is known the necessity to solve the initial-value problem for the Volterra integro-differential equations arises in investigation of the residual knowledge of some objects. Volterra by using the integro-differential equations has studied the memory of land and many other important problems which have been arisen in the study of some phenomena from the different industries of natural sciences. By using a similar form of the initial-value problem for both Volterra integro-differential equation and ODEs have established some relation. Here, by continuing this investigation receives the direct relation between ODE and Volterra integro-differential equation. By using this relation to solve Volterra integro-differential equation have applied the methods which are used in solving of the initial-value problem for ODEs. For this aim have proposed to use the general form of the multistep second derivative hybrid methods. Demonstrated the advantages of this method and constructed one-step methods with order of exactness p ≤ 10. The constructed here methods have compared with the known methods. And also by using the model problem have been illustrated the advantages of the received here results.
Analytical and FE calculations for determining the nominal tooth root stress for external, cylindrical gears with symmetric and asymmetric profile
Authors: Debreczeni D , Bognár G
Published: June 2020

The present work deals with the geometry dependence of the nominal tooth root stress of external toothed, cylindrical gears. The profile geometries required to perform the calculations are derived by our own program in MATLAB. Finite element simulations are executed in Abaqus. When designing the models, the geometric constraints of each tooth crown were optimized, keeping in mind the accuracy of the simulation. In addition to the analysis of the significant tooth stress value of symmetrical element pairs, special emphasis is placed on the development of the position of the critical cross-section. The numerical results obtained are also compared with the most significant standardized methods used in practice. The effect of the asymmetric design of the tooth profile on the nominal tooth root stress is reviewed in our investigations. The purpose of the numerical simulations carried out here is to determine the effect of the coast side angle on the dominant tooth root stress. In the evaluation of the results, the location of the critical cross-section, in addition to the magnitude of the stress, is also considered.
On generalized length spectrum in quotients of SL4
Authors: Gušić Dž
Published: June 2020

In this paper we consider a generalized length spectrum in the case of compact symmetric spaces generated as quotients of the special linear group of order four over real numbers. While the classical length spectrum is given as an estimate for a yes function counting prime geodesics of appropriate length, its generalized form is usually represented by a higher order counting function of Chebyshev type. Our goal is to prove that the error term that appears in the classical case in this setting can be significantly improved when derived via analogous, generalized apparatus.
Mathematical model of high tech enterprise manufacturing subdivisions production plan optimization
Authors: Batova Marina , Baranova Irina , Baranov Vyacheslav
Published: June 2020

For high tech enterprise manufacturing subdivisions challenge has been defined. Mathematical models have been developed. Implementation model algorithms have been researched. A step-by-step mechanism for algorithm implementation based on Johnson method is proposed. Developed models have been tested at the enterprises of the innovation-oriented cluster.
Comparative Analysis of Innovation Diffusion Models: Empirical Results and Predictive Performance on Russian Mobile Phone Propagation Data
Authors: Balash Vladimir , Balash Olga , Faizliev Alexey , Krylova Maria , Sidorov Sergei
Published: June 2020

This article introduces a new model that describes the innovation diffusion and is an extension of the well-known logistic model to the case when a diffusion process has a more complex structure. Time series data of mobile phone subscribers for Russian Federation during 2000-2018 are examined to compare the performance of the proposed model with the well-known innovation diffusion models (the Gompertz, Logistic, Bass models) and the time-series autoregressive moving average (ARMA) model, one of the most popular forecasting models. Empirical results show that the extended logistic model outperforms the other models and the proposed model has the best characteristics on real data for the Russian mobile communications market.
Modeling the amount of cash in circulation in a country using linear multiple regression
Authors: Batova Marina
Published: June 2020

The problem of modeling and forecasting the amount of cash in circulation in the country based on the example of the Russian Federation was formulated. Based on the methods of mathematical statistics and econometrics the dominant factors having the most significant effect on the amount of cash in circulation found. The problem in the form of an econometric model represented as a linear multiple regression localized. The quality of the resulting model justified.
Population exposure to pre-emptive de-energization aimed at averting wildfires in Northern California
Authors: Abatzoglou John T , Smith Craig M , Swain Daniel L , Ptak Thomas , Kolden Crystal A
Published: June 2020

Recent extreme fire seasons in California have prompted utilities such as Pacific Gas and Electric to pre-emptively de-energize portions of the electrical grid during periods of extreme fire weather to reduce the risk of powerline-related fire ignitions. The policy was deployed in 2019, resulting in 12 million person-days of power outages and widespread societal disruption. Retrospective weather and vegetation moisture data highlight hotspots of historical risk across northern California. We estimate an average of 1.6 million person-days of de-energization per year, based on recent historical climate conditions and assuming publicly stated utility de-energization thresholds. We further estimate an additional 70% increase in the population affected by de-energization when vegetation remains abnormally dry later into autumn—suggesting that climate change will likely increase population vulnerable to de-energization. Adaptation efforts to curtail fire risk can be beneficial, but efforts to prepare affected populations, modernize the grid, and refine decision-making surrounding such policies have high potential to reduce the magnitude of negative externalities experienced during the 2019 de-energization events.
Estimation of heat dissipation on a levitating rotor over superconducting magnet bearing
Authors: Iida T , Sakurai Y. , Matsumura T , Sugai H , Imada H , Kataza H , Ohsaki H , Katayama N , Terao Y
Published: June 2020

We report the estimation of the heat dissipation on a levitating rotor over superconducting magnetic bearing operating below 10 K. The continuously rotating mechanism is one of key devices to support the rotation of a sapphire half wave plate (HWP) in a polarization modulator of a LiteBIRD satellite. Due to the system requirement, the HWP must be kept at a cryogenic temperature while it is spinning. In order to minimize the frictional energy loss, we employ a superconducting magnetic bearing (SMB) and AC synchronous motor, which enables a contactless rotational mechanism. While we can minimize the frictional heat loss, there exists an energy loss due to the magnetic friction. As a result, it is essential to build a thermal model an estimation of heat dissipation to this contactless rotor is important to predict how much the HWP temperature rises during its rotation. For an estimation of heat dissipation, we conduct an experiment in order to establish the thermal simulation model equivalent to the flight model in size. Each thermal contact conductance between the rotor and the cryogenic rotor holder is also estimated through the experiment data. From the data, we only can know the difference in the rotor temperature before and after the rotor rotation. We monitor the transient temperature profile of grippers after the rotor is gripped by them. The rotational time is related to the total heat dissipation on the rotor because the heat dissipation is attributed to two kinds of energy losses: a magnetic hysteresis and induced eddy currents on metal parts of the rotor. Finally, we make a comparison between the thermal model and the experimental result and estimate the allowable heat dissipation to keep the HWP temperature lower than 20K.
Design and test of cryogenic flex cables for the euclid near infrared spectrophotometer
Authors: Holmes W A , Boehmer E , Bertagne C , Cheung S , Cho B , Cho H , Delo G , Dillon R P , Farris M , Feizi A , Ferraro N , Fischer L , Foltz R , Hong K , Jhabvala M , Kan E , Kopp R , Maiten J , Markley D , Morgan A R , Ngyuen M , Pravdo S , Ruiz C , Runyan M , Skalare A , Waczynski A , Walters Y , Wong A , Zhong F
Published: June 2020

We describe the design and testing of the Cryogenic Flex Cable (CFC) delivered for the Near-Infrared Spectro-Photometer (NISP) instrument [1] for the ESA Euclid mission [2, 3]. The Euclid spacecraft is scheduled for launch in the summer of 2022. It will observe ∼ 1/3 of the total sky using a telescope with 1.2m SiC primary mirror, passively cooled to ∼ 125K, and containing Visible Imager (VIS) [4] and NISP focal plane instruments, from an orbit at the Earth-Sun L2 lagrange point. At the heart of the NISP instrument is a 4X4 mosaic focal plane of Teledyne H2RG infrared detector arrays held at 100K. The CFC described here are designed to link each detector array to a dedicated packaged cryogenic electronics assembly held at ∼ 137K with minimal heat leak to the 100K stage and to withstand handling and launch vibrations. Prototype CFCs were developed and tested by Teledyne. The final 7-layer CFC flexible printed circuit boards and Airborn nanoconnectors were provided by Teledyne and assembled for flight at the Jet Propulsion Lab (JPL). Flight qualification CFC were made and subjected to thermal conductance, thermal emissivity, thermal cycle, survivability to bend, vibration and normal mode testing at JPL. The flight CFC were subject to bake out and thermal cycle at JPL and then tested with the flight detectors and electronics at Goddard Space Flight Centers Detector Characterization Lab. The results of the qualification tests as well as the measured characteristics of the 41 manufactured CFC are summarized.
Analysis and optimization of the liquid nitrogen pre-cooling stage for the EAST helium refrigerator
Authors: Zhu Z G , Zhang Q Y , Zhu P , Hu L B , Zhou Z W
Published: June 2020

Pre-cooling of helium with liquid nitrogen is a good alternative to large scale helium refrigerators for initial cool-down from room temperature to about 80 K due to high exergy efficiency, high cooling capacity, and low demand of heat exchanger area. However, during the initial cool-down, two problems have to be faced for an improper liquid nitrogen pre-cooling stage arrangement. The temperature difference between helium and nitrogen at the cold end of the first heat exchanger became very large, which leaded to high thermal stress and potential damage. The outlet temperature of the nitrogen stream of the heat exchanger is lower than room temperature, thus the efficiency decreases and more liquid nitrogen is consumed. In this paper, the performance of a liquid nitrogen pre-cooling stage for the EAST 2kW/4.5K helium refrigerator during cool-down phase will be analyzed. Then a new arrangement will be sought to avoid a larger temperature difference and underutilization of nitrogen cold energy. The current work may help to design, optimize and operate the liquid nitrogen pre-cooling stage for large scale helium refrigerators.
Implications and Methodology of Retrofits in Cryogenic Plants
Authors: Amstutz O. , Herrmann R. , Bischoff S.
Published: June 2020

Developments over the past few years allow Linde Kryotechnik to economically replace the turbines of a cryogenic plant with state-of-the-art technology leading to several advantages. Stand out among others are higher efficiency of the turbines, easier operation of the plant, increased reliability and an update of the design point regarding current customer demands which improve the overall performance and efficiency of an upgraded cryogenic system. While each retrofit is unique based on the customer demands and situation, it is still possible to follow a certain methodology. Several successful retrofits with conclusions are presented.
Development of a high-effectiveness slotted plate cryogenic heat exchanger
Authors: Sheehan E , Pfotenhauer J , Miller F
Published: June 2020

High-effectiveness heat exchangers are a ubiquitous component of cryogenic systems, but their performance typically falls short of model-based expectations. The following paper summarizes modeling efforts of a heat exchanger designed to achieve an effectiveness in excess of 99% within a prescribed envelope of volume, weight, pressure drop, and operating conditions. Simulation efforts focus on employing minimal assumptions and accounting for many loss mechanisms to avoid overestimation of predicted effectiveness. Axial conduction and parallel passage flow imbalance are major contributing factors to heat exchanger inefficiency. Consequently, a staggered stacked slotted plate geometry, also known as a matrix heat exchanger, was chosen as the most promising type to achieve the desired effectiveness. High thermal conductivity, high surface area finned copper plates separated by low thermal conductivity, low cross-sectional area stainless steel spacers achieve high stream-to-stream heat transfer while limiting axial conduction and allowing for fluid redistribution between plates. The number of design parameters was reduced based on manufacturing limitations and conceptual reasoning. ANSYS Fluent computational fluid dynamics was used to form Nusselt number and Darcy friction factor correlations for the geometry and flow conditions. A finite difference MATLAB model accounted for axial conduction, parasitic heat loads, and material property variation with temperature and pressure. The Fluent-derived correlations were used as inputs to the MATLAB model. The MATLAB model was validated by comparing its results to an analytic, constant property effectiveness-NTU solution for stacked plate heat exchangers, as well as experimental data collected from a similar heat exchanger. Trade-offs between weight, pressure drop, and effectiveness were studied.
Effect Of Leading-edge Geometry Parameters On The Performance Of Miniature Cryogenic Expansion Turbine
Authors: Ke C L , Xiong L X , Peng N , Dong B , Li K R , Liu L Q
Published: June 2020

The numerical simulation included solid blades with four different leading-edge thicknesses and four different leading-edge geometries. One of the geometries was square, one was ellipse A(ellipse ratio is 1), one was ellipse B(ellipse ratio is 2), and the other was ellipse C(ellipse ratio is 3). The four thicknesses were 0.7mm, 0.6mm, 0.5mm, 0.4mm. The results show increased efficiency loss for increased leading-edge thickness for square geometry. For ellipse geometries, there was no significant difference when the leading-edge thickness changed at the positive incidence range. For the same leading-edge thickness(0.7mm), square leading-edge caused more loss than ellipse leading-edge. For square geometry, the optimal incidence angle was about -8 degree(0.7mm). For ellipse geometries, the optimal incidence angle was about -30 degree(0.7mm). And with the decrease of leading-edge thickness, the square’s optimal incidence angle was toward to zero degree, the ellipse’s optimal incidence angle was toward to larger negative angle.
Development of a kw-class Stirling cryocooler for liquefaction of natural gas (NG)
Authors: Park J , In S , Ko J , Kim H , Hong Y , Yeom H , Park S
Published: June 2020

Our research group has developed a kW-class Stirling cryocooler. The Stirling cryocooler adopts a ‘gamma-type’ configuration operated with a linear compressor. The cold-end of the Stirling cryocooler is equipped with heat exchangers that can accept and eventually liquefy natural gas (NG). The liquefied natural gas (LNG) is stored in an auxiliary reservoir. In this research paper, the experiments as a proof of concept has been carried out. The Stirling cryocooler has been independently tested prior to adopting the heat exchanger as the aforementioned above. It has been confirmed that the Stirling cryocooler can exert over 1 kW cooling capacity at 110 K cold-end temperature with 9 kW compressor input. This research paper mainly focuses on (1) relevant technical issues during the cooler development process and (2) demonstrating the liquefaction of argon gas (instead of using NG for the sake of safety regulation). The system presented in this paper, therefore, can be a good candidate for a small-scale liquefier does not require oil-involved maintenance.
Experimental study on a 20W/80K high frequency pulse tube cryocooler
Authors: Liu Xuming , Chen Liubiao , Wu Xianlin , Wang Jue , Zhou Yuan , Wang Junjie
Published: June 2020

The cryocoolers working around the liquid nitrogen temperature have important applications in high temperature superconducting, infrared detectors and gas liquefaction. A cryocooler sometimes needs to work in different temperatures. For the high-frequency pulse tube cryocooler operating around the liquid hydrogen temperature, due to the limitation of the length of the regenerator, it is often impossible to simultaneously have higher performance around the liquid nitrogen temperature. Therefore, this paper enhances its performance around the liquid nitrogen temperature based on a high-frequency pulse tube cryocooler working around the liquid hydrogen temperature, by changing the effective length of the regenerator with filling different lengths of copper mesh. Firstly, the effect of filling different lengths and meshes of copper mesh on its 80 K refrigeration performance is simulated. Finally, the experimental verification is also carried out. Moreover, by further optimizing the phase modulation mechanism and operating parameters including working frequency and charge pressure, the cryocooler can provide 20 W cooling capacity at 78 K under the input electric power of 420 W. The relative Carnot efficiency is increased from the initial 9.8 % to 13.56 %.
Load map of sumitomo 415DP cryocooler in the temperature range of 40-400K
Authors: Wirths T. , Putselyk S. , Bekhti N. Ben , Fröhlich A. , Grenz O. , Konig F. , Naumann L. , Rahlf F. , Tiesing M.
Published: June 2020

In the last 20 years, 2-stage cryocoolers have been found to provide an optimum solution for a wide range of applications like low temperature physics, superconducting cold electronics, cryopumping and superconducting magnets. For a proper design of helium cryostats with significant cold masses connected to the first and second stages of cryocoolers, it is important to have a load map (also called “working field”) in order to estimate cool-down and warm-up time periods. Such load maps are either not presented in the open literature sources for “high” temperature ranges, or just given by manufacturing companies for general information but without any guarantee. In the present paper, the load map of a 2-stage Sumitomo 415DP cryocooler in the wide temperature range of 40-400 K is presented.
High-availability single-stage Stirling coolers with high power density
Authors: Willems D. , de Veer B. , Arts R. , Mullié J. , Bollens P.
Published: June 2020

Recent developments at Thales Cryogenics have been aimed at improving the performances of 100 W and 200 W input power class flexure bearing Stirling coolers.

The aim of these developments has been twofold: To enable multi-year operation with a vanishingly small failure probability (high availability) and to extend the usable range down to below 42 K (low temperature). As the starting point for development, the LSF9589 and LSF9340/LSF9350 cooler ranges were selected. By performing these upgrades, the usability range of the cryocoolers is extended.

Multiple upgrades will be shown such as tuning for low-temperature operations and material upgrades. Test results will be presented and potential future improvements will be discussed. The work performed was done for a variety of customers, with applications including nitrogen recondensers for zero boil-off dewars, high temperature superconducting filters, and low temperature longwave infrared detectors.
PIP-II Injector Test cryogenic transfer line
Authors: Wang Renzhuo , Hansen Benjamin , Hurd Joseph , Martinez Alexander , Klebaner Arkadiy
Published: June 2020

PIP-II Injector Test will test a nearly full-scale front end of PIP-II accelerator. The cryogenic transfer line will provide 2 K, 5 K and 40 K refrigeration for Half Wave Resonator and Single Spoke Resonator cryomodules. This paper will focus on design, installation and operation plan of the cryogenic transfer line.
Status of the LCLS-II Cryogenic Distribution System
Authors: Soyars W , Dalesandro A , Martinez A , Hansen B , Theilacker J , Klebaner A , Wands R
Published: June 2020

The LINAC Coherent Light Source II (LCLS-II) located at SLAC National Accelerator Laboratory (SLAC) in Menlo Park, CA, is a U.S. Department of Energy project tasked to design and build a world-class x-ray free-electron laser facility for scientific research. The Linac has superconducting radio frequency cryomodules that are connected to the cryogenic plant by the Cryogenic Distribution System (CDS), which consists of distribution boxes with heat exchangers and reliefs, feed caps, end caps, and surface, vertical, and bypass transfer lines. The CDS components were designed and built to specification by industry. The components have been delivered and their installation at SLAC will be discussed. The as-built relief system design will be presented, showing minimization of relief inlet pressure drops while meeting capacity requirements. The relieving flow pressure drops along the lengths of the CDS to centrally located reliefs at the distribution box were analysed to satisfy Pressure Vessel and Process Piping Code criteria to ensure relief performance. The sub-atmospheric 2 K circuit relieving approach will be discussed, which includes a three-way diverter isolation valve suitable for sub-atmospheric service. The component anchoring load design approach and installation into concrete floor will be discussed. This addresses loading, including seismic loading, along the component’s load path to floor anchoring system.
Design and fabrication of the Mu2e cryogenic distribution system
Authors: White Mike , Lamm Mike , Hocker Andy , Arnold Don , Tatkowski Grzegorz , Kilmer James , Poloubotko Valeri , Tope Terry , Huang Yuenian , Elementi Luciano , Badgley Karie , Voirin Erik , Young Ian , Dhanaraj Nandhini , Brandt Jeff , Feher Sandor , Hess Charles
Published: June 2020

The muon-to-electron conversion (Mu2e) experiment at Fermilab will be used to search for the charged lepton flavor-violating conversion of muons to electrons in the field of an atomic nucleus. The Mu2e experiment is currently in the design and construction stage and is expected to begin operations in 2022. The Mu2e experiment uses four large superconducting solenoid magnets including a Production Solenoid (PS), an Upstream and Downstream Transport Solenoid (TSu and TSd) and a Detector Solenoid (DS).

This paper will focus on the cryogenic distribution system for these four solenoid magnets. Liquid helium will be supplied from two re-purposed Tevatron satellite refrigerators. A large cryogenic distribution box (DB) is located in the Mu2e building to distribute the required cryogens to each of the four solenoid magnets. Each solenoid magnet will have a dedicated transfer line and cryogenic feed box (FB). The solenoid magnets each require two liquid helium circuits and two liquid nitrogen circuits.

The most unique feature about this cryogenic system is that the assemblies for the start of the superconducting portion of the power leads are mounted in feed boxes that are in the range of 23 m to 31 m away from the solenoid magnets. The cryogenic feed boxes are located remotely to provide protection from radiation damage and high magnetic fields. The power leads are NbTi superconducting cable stabilized with high conductivity aluminum. The 6061-T6 aluminum grade was selected for the transfer line piping so that the piping would thermally contract at the same rate as the power lead. A major concern for this transfer line is that a small helium leak could create an electric discharge arc due to the Paschen effect. This paper includes a description of the design features and testing done to ensure that the power leads are protected from the Paschen effect while still being adequately cooled to liquid helium temperatures.
Effect of solid surface in vicinity of multi-bubble array in cryogenic environment
Authors: Mondal J , Mishra A , Lakkaraju R , Ashokkumar M , Ghosh P
Published: June 2020

Multiple bubble interactions in initially quiescent liquid are often accompanied by generation of jets, shockwaves and light. At cryogenic temperature (< 123 K) when certain materials (particularly bcc-type) become brittle, such afore-mentioned physical effects can be effective in disintegrating them to smaller fragments. CFD techniques based on direct numerical simulations can help to understand this phenomenon that may benefit nanotechnology-based industries and oil-gas exploration-firms working with air-gun arrays. In this paper, multiple bubble-pairs are simulated in a co-centric manner around a centrally located solid target (5 mm radius). The ambient fluid is liquid nitrogen (77 K) and the bubbles are gaseous nitrogen (87 K). 2D numerical simulation using the VOF method in compressible domain is carried out neglecting the effect of phase change and gravity. The stand-off distance between the solid target and bubble-pairs are varied systematically and its influence on the fluid-dynamic effects (e.g. pressure shockwave & jets) are compared. Initial calculations suggest that for stand-off distance of 0.93 mm, shockwaves measure above 10 times the ambient pressure and liquid jet speeds around 30 m/s in cryogenic environment, at multiple locations very close to the solid target. These consecutive physical impacts can foster ample liquid-hammer pressures, making it promising for solid wear at 77 K when juxtaposed against room-temperature cases.
FRIB cryogenic system status
Authors: Casagrande F , Ganni V , Knudsen P , Wright M , Jones S , Nguyen C , Fila A , Hassan N , Vargas G , Joseph N , Stanley S
Published: June 2020

The Facility for Rare Isotope Beams (FRIB) cryogenic plant has been successfully commissioned, including compressor system, 4.5 K cold box system, sub-atmospheric (2 K) cold box system, and the distribution system for two of the three linear accelerator (Linacs) segments. This plant uses the Ganni-Floating pressure process, allowing the compressor discharge and 4.5 K cold box supply pressure to automatically vary from 6 to 21 bar, without introducing additional exergetic losses to reduce the capacity (e.g., throttling turbine inlet valves, load heaters, etc.). The 2 K (31 mbar) load is supported using five stages of centrifugal compressors, housed within the sub-atmospheric cold box, which recompress the helium to 1.15 bar (and around 30 K). In 2012, FRIB assumed the responsibility, in collaboration with JLab to design and procure the sub-systems after the decision to move away from an industry supplied turn-key system. FRIB was responsible for procurement of all systems, all onsite activities, including the installation and integration of all the subsystems, development of the control systems, as well as, the integration, commissioning, and testing of each sub-system. At present this has culminated in the production of the first beam through the first Linac segment. An overview of the planning and execution of the project will be presented, which allowed meeting of scheduled goals and anticipated performance, and prevented the need to store or ‘double-handle’ any equipment.