bluuebunny/crossref_metadata_2025_split huggingface dataset:
Buffer gas cooling of ions in radio-frequency traps using ultracold atoms
Authors: Trimby E , Hirzler H , Fürst H , Safavi-Naini A , Gerritsma R , Lous R S 
Published: February 2022

Abstract
Reaching ultracold temperatures within hybrid atom–ion systems is a major limiting factor for control and exploration of the atom–ion interaction in the quantum regime. In this work, we present results on numerical simulations of trapped ion buffer gas cooling using an ultracold atomic gas in a large number of experimentally realistic scenarios. We explore the suppression of micromotion-induced heating effects through optimization of trap parameters for various radio-frequency (rf) traps and rf driving schemes including linear and octupole traps, digital Paul traps, rotating traps and hybrid optical/rf traps. We find that very similar ion energies can be reached in all of them even when considering experimental imperfections that cause so-called excess micromotion. Moreover we look into a quantum description of the system and show that quantum mechanics cannot save the ion from micromotion-induced heating in an atom–ion collision. The results suggest that buffer gas cooling can be used to reach close to the ion’s groundstate of motion and is even competitive when compared to some sub-Doppler cooling techniques such as Sisyphus cooling. Thus, buffer gas cooling is a viable alternative for ions that are not amenable to laser cooling, a result that may be of interest for studies into cold controlled quantum chemistry and charged impurity physics.
Fermionic King model: critical masses resulting from the competition of quantum and evaporation effects
Authors: Velazquez L , Espinoza-Soliz I 
Published: February 2022

Abstract
We study the influence of evaporation (the escape of constituents) on the thermodynamics of a self-gravitating non-relativistic gas of fermions in the framework of Newtonian gravitation. For this purpose, it is reconsidered as the so-called fermionic King model introduced by Ruffini and Stella in the context of dark matter halos problems (1983 Astron. Astrophys.
119 3). As the usual King model, the present model predicts density profiles that drop to zero at a certain finite radius R, which is referred to as the tidal radius. Our interest is focused on the thermodynamics of this model at constant total mass M and constant tidal radius R. A special interest is devoted to study the incidence of mass on the collective phenomena of gravitational collapse and evaporation disruption. The underlying physics is driven by the Fermi mass M
F ∼ ℏ
6/G
3
m
8
R
3, which corresponds to the total mass of a self-gravitating degenerate Fermi gas of non-relativistic point particles with mass m, whose linear size is equal to the tidal radius R of evaporation. Numerical calculations predict three critical values for the total mass, M
1 > M
2 > M
3, which hallmark the thermodynamic stability. The lower bound

M

3

≃

1

4

M

F

is a critical value of the total mass below the which the system gravitation is unable to confine its constituents, so that the system with total mass M < M
3 undergoes an evaporation disruption. The other bounds, M
2 ≃ 90.9M
F and M
1 ≃ 8.9 × 106
M
F, are critical values that hallmark the continuous (or discontinuous) character of the microcanonical phase transition associated with gravothermal collapse and the presence of states with negative heat capacities.
A survival model to explain the statistical properties of multimodal mobility
Authors: Mizzi C , Fabbri A , Colombini G , Bertini F , Bazzani A 
Published: February 2022

Abstract
The statistical properties of human mobility have been studied in the framework of complex systems physics. Taking advantage of the new datasets made available by the information and communication technologies, the distributions of mobility path lengths and of trip durations have been considered to discover the fingerprints of complexity characters, but the role of the different transportation means on the statistical properties of urban mobility has not been studied in depth. In this paper, we cope with the problem of the existence of universal features for pedestrian, bike and vehicular urban mobility. In particular, we propose the use of travel time as the universal energy for the mobility and we define a simple survival model that explains the travel time distribution of the different mobility types. The analysis is performed in the metropolitan area of Bologna (Italy), where GPS datasets were available on individual trips using different transport means. Our results could be helpful for the realization of multimodal sustainable mobility in future cities, compatible with the citizen’s propensities to use different transport means.
The Design and Implementation of Control and Driving system with Double Position Feedback for Submarine Steering
Authors: Tian Guanzhi , Jiang Liting , Yuan Liwei , Xu Zhishu , Zhang Yiqi , Li Chunyu 
Published: February 2022

Abstract
With the well improvement of motor and power electronic technology, the technology of Electro-mechanical actuator (EMA)has come into a new stage. A high-reliability driving and controlling technology with a double redundancy feedback loop is described in this paper. In this method, the position of electromechanical actuator and the resolver position of motor can be back up for each other by some compensate algorithms. This method can improve the reliability of the control system without extra hardware and increasing cost.
Parallel operation simulation of medium voltage diesel emergency power supply vehicles
Authors: Xie Rui , Ge Xinyuan , Hu Ripeng , Zhu Junpeng , Xie Bin 
Published: February 2022

Abstract
The large-scale emergency load demand improves the requirements of distribution network for emergency power capacity, and the working condition of multi-engine parallel operation of medium voltage diesel emergency power supply vehicles also arises. In order to solve the difficulty of parallel simulation of medium voltage diesel emergency power supply vehicles, this paper establishes the simulation model of medium voltage diesel emergency power supply vehicles by analyzing the mathematical models of internal components. According to the parameter conditions of parallel operation, the parallel controller is designed. Finally, the multi-engine parallel system model of medium voltage diesel emergency power supply vehicles is built by using Matlab / Simulink, and the parallel operation simulation of medium voltage diesel generator vehicles is completed.
Amino-Modified Hollow Mesoporous Silica Microspheres Loaded with Cresol Red-Boric Acid for Potent Reversible Thermochromic Performance
Authors: Yu Tingting , Wang Xu , Cheng Liang , Hu Yuehang , Wang Haoya , Wang Hao 
Published: February 2022

Abstract
In this study, two reversible thermochromic composites were obtained, hollow mesoporous silica (HMS) and amino group-modified hollow mesoporous silica (HMS-NH2) microspheres loaded with cresol red-boric acid (CR-BA), respectively. Owing to the rigid structure of hollow interior and mesoporous shell layers, CR-BA was easily encapsulated into a relatively high loading capacity micro-carrier. The composites analysed were characterized by Fourier transform infrared spectroscopy transmission electron microscopy, scanning and transmission electron microscopy and dynamic light scattering. By amino functionalization, a more obvious thermal colour-change was observed in HMS-NH2 loaded with CR-BA. In addition, both HMS and HMS-NH2 loaded with CR-BA illustrated a sever colour reversibility, which were 5min and 3min respectively.
Synthesis and Analysis of a Viscosity Modifying Admixture based on Acrylamide and 2-Acrylamide-2-methylpropanesulfonic acid
Authors: Ni Tao , Song Xin , Wang Yongmei , Feng Ke , Ng Serina , Liu Zhaoyang 
Published: February 2022

Abstract
Viscosity modifying admixture (VMA) can be employed to avoid the segregation of concrete. Here, we present a type of viscosity modifying agent (B2), prepared by free radical polymerization between acrylamide (AM) and 2-acrylamide-2-methylpropane sulfonic acid (AMPS). The structure and composition were characterized by FT-IR, NMR and light scattering. Hydroxy-propyl-methyl cellulose (HPMC) was used as a comparison to determine the suitability of B2 as a VMA. The results show that B2 is superior to HPMC, and can improve not only the homogeneity and bleeding resistancy, but also increase the compressive strengths of the concrete by 4 to 5 MPa across all testing periods, up to 28 days. A highlight of this admixture is the effective regeneration of nonuseable concrete to its non bleeding state with delayed addition. Finally, a mechanistic analysis of the viscosifying effect, which induced the increase in compressive strength is postulated in this article.
Preparation of amphiphilic block copolymers by Reversible Addition Fragmentation Chain Transfer polymerization
Authors: Hu Na 
Published: February 2022

Abstract
Polystyrene macromolecular chain transfer agent (PS-CTA) was firstly synthesized by RAFT of styrene (St) in THF using benzyl dithiobenzoate (BDTB) as chain transfer agent and azobisisobutyronitrile (AIBN) as initiator. It was found that the molar ratio of monomers to chain transfer agents and reaction time had obvious effects on the molecular weight of PS-CTA, and the distribution of molecular weight (M
w/M
n ) decreases with the increase of the ratio of chain transfer agent to initiator by using gel permeation chromatography (GPC). The amphiphilic block copolymers polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) were synthesized using PS-CTA by RAFT. The structure, glass transition temperature (Tg) and molecular weight of the diblock copolymer were characterized by nuclear magnetic resonance (1H-NMR), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). The results showed that the structure of PS-b-P4VP was the target product. The segment ratio of PS-b-P4VP could be effectively controlled by changing the polymerization conditions in a large range.
Surface modification of Ti6Al7Nb employing pure waterjet and abrasive waterjet polishing for implant application: comparison study
Authors: N Pradeep , Sastry C Chandrasekhara , Brandão Lc , Coelho RT , Bairapudi Anil , Muthu Manickam MA , Rahman Hafeezur , Patil Sandeep 
Published: February 2022

Abstract
Natural bones in vertebrates are replaced with implants when it fails under fatigue/impact loading conditions. The implants surface roughness is a vital parameter that enhances the osseointegration rate owing to mechanical stability by firm anchoring between the implant and the bone tissue. In this research article, surface modification of Ti6Al4Nb by the action of impingement erosion was executed under two conditions (i) Waterjet polishing (WP) without abrasives; (ii) Abrasive waterjet polishing (AWP) with biocompatible abrasives and studied in correlation to MRR and average surface roughness. The bio abrasives were made in a laboratory that endorses the bone healing characteristics availing 85% hydroxyapatite (HAp) and 15% yttrium stabilized zirconia. SEM, EDS, XRD, AFM and Non-contact surface roughness measurements were used to study the surface morphology of the bio-abrasives and the AWP surface. Experimentally the WP resulted in 73% more material removal rate and with higher average surface roughness Ra by 50% when compared to the AWP. The biocompatibility of Ti6Al4Nb post AWP was found to be favourable with more live cells after performing the MG63 Cell assay for the optimal exp run #11 obtained via the desirability function algorithm.
Optimisation of Corrosion behaviour and hardness of Ni-B4C Composite coated AZ31 Mg alloy using RSM
Authors: Venses G , Sivapragash M , Sasi Kumar T , Michael Thomas Rex F 
Published: February 2022

Abstract
The optimisation of process parameters in the electroplating process is imperative to improve the effectiveness of coating that meets the industry’s requirements. The present study analyses the influence of the electroplating parameters such as bath temperature, current intensity, and plating time on the hardness and corrosion properties of AZ31 Mg alloy. A preliminary electroplating coating was initially done on the AZ31 Mg alloy with zinc and copper. Subsequently, the AZ31 Mg alloy is coated with Ni-B4C composite by electroplating. Response Surface Methodology (RSM) is used to find the optimum settings for the parameters by minimising the corrosion loss and maximising the hardness. The quadratic regression models were developed for the responses based on the experiments conducted as per the Box-Behnken design method. Scanning Electron Microscopy (SEM), XRD analyses are used to investigate the effectiveness of the Ni–B4C composite coating on AZ31 Mg alloy. It is revealed from the results that the maximum hardness of 140 HV and minimum corrosion mass loss of 0.583 mg cm−2 was obtained for the optimal parameters.
Mechanical, morphological and thermal analysis of unidirectional fabricated sisal/flax hybrid natural fiber composites
Authors: Sundeep Dola , Varadaraj Eswaramoorthy K , Ephraim S Daniel , Sastry C Chandrashekara , Krishna A Gopala 
Published: February 2022

Abstract
We report the spectroscopic, thermal, and mechanical outcomes of epoxy reinforced sisal/flax (S/F) hybrid natural fiber composites. This work is intended to enhance the mechanical and thermal properties of the sisal fibers in addition to flax fibers. In recent years, natural fiber composites gained inclusive credit as a supernumerary to conventional synthetic composites for their superior ecological properties. Five different varieties of composite slabs i.e., 60% epoxy matrix and 40% of sisal/flax fibers were fabricated unidirectionally through a simple hand layout method by varying sisal and flax ratio as (40/0, 30/10, 20/20, 10/30, and 0/40) with a constant weight fraction as 0.4Wf. The x-ray diffraction analysis was performed on the 20 S/20 F specimen and the crystallinity index is calculated as 42.84%. The spectroscopic and thermal studies were conducted on the 20 S/20 F sample and the chemical imprint of the composite is revealed by the strong peaks of cellulose, hemicellulose, and lignin along with amorphous and crystalline content of the FTIR data and is confirmed through the XRD data. The addition of flax fibers to sisal fibers showed a constructive improvement of thermal stability which is shown by the TG/DTA graph. In a three-stage degradation of sample, a maximum is observed at 334 °C. The tensile, flexural, and impact tests of all the fabricated composite samples are performed and ultimate tensile strength of 165.2 N/mm2 for the 40 S/0 F composite with an elongation of 9.2% is noted. The ultimate flexural stress of 8.1 N mm−2 is observed in composite 10 S/30 F and composite 10 S/30 F has an excellent ability to absorb impact force of 1.2 J energy. Based on the above results the manufactured composites exhibited higher thermal and mechanical properties showing a unique characteristic for different concentrations of flax fibers. Thus, the developed composites can be used individually for various applications based on the requirement of the end-user.
Effect of LN2 and CO2 Coolants in hard turning of AISI 4340 steel using tungsten carbide tool
Authors: Gowthaman B , Boopathy S Rajendra , Kanagaraju T 
Published: February 2022

Abstract
Recently, Cryogenic cooling has witnessed a significant role in improving efficiency, increasing the quality of machined parts, and developing a techno-economic and eco-friendly acceptable methodology in the machining of components. This study deals with the effect of hardened AISI 4340 steel at 48 HRC against uncoated WC cutting tool analysed through the use of dry, cryogenic liquid nitrogen (Cryo-LN2) and cryogenic liquid carbon dioxide (Cryo-LCO2) cooling environments. The input parameters for this hard turning condition include cutting velocity, feed rate, and depth of cut. A study of the machining performance of cutting temperature, surface roughness, material side flow, flank wear, microhardness, and chips morphology have also been made. The experiment results revealed the effective lowering of the cutting temperature, better surface roughness and reduced flank wear for LCO2 and LN2 coolant by cryogenic cooling against dry cutting condition. Compared to dry and cryogenic LCO2 cutting environments, the machined zone of a cryogenic LN2 exhibited the highest microhardness value. The main reason for this was the decrease in the thermal softening effect. Overall, the performance of the cryogenic LN2 environment condition was effective and efficient in the turning process compared to dry and cryogenic LCO2.
Revealing room temperature ferromagnetism in exfoliated Fe5GeTe2 flakes with quantum magnetic imaging
Authors: Chen Hang , Asif Shahidul , Whalen Matthew , Támara-Isaza Jeyson , Luetke Brennan , Wang Yang , Wang Xinhao , Ayako Millicent , Lamsal Saurabh , May Andrew F , McGuire Michael A , Chakraborty Chitraleema , Xiao John Q , Ku Mark J H 
Published: February 2022

Abstract
Van der Waals (vdW) material Fe5GeTe2, with its long-range ferromagnetic ordering near room temperature, has significant potential to become an enabling platform for implementing novel spintronic and quantum devices. To pave the way for applications, it is crucial to determine the magnetic properties when the thickness of Fe5GeTe2 reaches the few-layers regime. However, this is highly challenging due to the need for a characterization technique that is local, highly sensitive, artifact-free, and operational with minimal fabrication. Prior studies have indicated that Curie temperature T
C can reach up to close to room temperature for exfoliated Fe5GeTe2 flakes, as measured via electrical transport; there is a need to validate these results with a measurement that reveals magnetism more directly. In this work, we investigate the magnetic properties of exfoliated thin flakes of vdW magnet Fe5GeTe2 via quantum magnetic imaging technique based on nitrogen vacancy centers in diamond. Through imaging the stray fields, we confirm room-temperature magnetic order in Fe5GeTe2 thin flakes with thickness down to 7 units cell. The stray field patterns and their response to magnetizing fields with different polarities is consistent with previously reported perpendicular easy-axis anisotropy. Furthermore, we perform imaging at different temperatures and determine the Curie temperature of the flakes at ≈300 K. These results provide the basis for realizing a room-temperature monolayer ferromagnet with Fe5GeTe2. This work also demonstrates that the imaging technique enables rapid screening of multiple flakes simultaneously as well as time-resolved imaging for monitoring time-dependent magnetic behaviors, thereby paving the way towards high throughput characterization of potential two-dimensional (2D) magnets near room temperature and providing critical insights into the evolution of domain behaviors in 2D magnets due to degradation.
Controlled growth mechanism of ring-like In(Ga)As quantum Dot pairs on GaAs ring-ring-disk nanostructures templates
Authors: Lang Qi-Zhi , Zhou Xun , Guo Xiang , Ding Zhao , Ye Yuan-Nong , Cao Yu 
Published: February 2022

Abstract
The ring-like In(Ga)As quantum dot pairs (QDPs) is prepared on GaAs ring-ring-disk (R-R-D) nanostructures template by droplet epitaxy (DE) method. The surface morphology of GaAs samples are characterized with Scanning Tunneling Microscope (STM), and studying local controlled growth mechanism of quantum dots (QDs) on GaAs R-R-D nanostructures. STM images show that In(Ga)As QDPs self-assembled a kind of complicated structure with one quantum dot (QD) pair in the center of nanostructures, other QDPs appearing both double rings and disk areas of original GaAs R-R-D nanostructures distributed like a exquisite ring. These In(Ga)As QDPs are uniformly arranged along the [1

1
¯

0] direction of GaAs(001) surface. Combining Stranski-Krastanov (S-K) growth mode and the tensile effect of strain field in the [1

1
¯

0] direction on sample surface, the nucleation position and distribution shape of ring-like In(Ga)As QDPs is locally controllable. It is found that high uniformly QDPs can be locally controlled by the original GaAs R-R-D nanostructures templates. These results can provide certain guiding significance for the controllable growth of QD by DE method.
Design of all-inorganic hole-transport-material-free CsPbI3/CsSnI3 heterojunction solar cells by device simulation
Authors: Xu Xingyu , Wang Jianfeng , Cao Dan , Zhou Yun , Jiao Zhiwei 
Published: February 2022

Abstract
The hole transport material (HTM)-free perovskite solar cells (PSCs) have attracted widespread interest due to enhanced stability and lowered cost as compared to the sandwich-type PSCs with an organic hole conductor. For the absorber layer, CsPbI3 has become a competitive candidate for its good chemical-components stability, excellent optoelectronic properties and most proper bandgap among inorganic halide perovskites. However, the power conversion efficiency of CsPbI3-based HTM-free PSCs is still much inferior to that of conventional ones. In this work, an all-inorganic-perovskite-heterojunction CsPbI3/CsSnI3 is proposed as the absorber and the HTM-free CsPbI3/CsSnI3 PSCs are investigated systematically through numerical simulation by using SCAPS-1D. Compared with the HTM-free PSCs employing a single CsPbI3 absorbing layer, the HTM-free CsPbI3/CsSnI3 PSCs have the extended absorption range and enhanced performance. The best cell efficiency is increased from 15.60% to 19.99% and from 13.87% to 19.59% for the cell with a back-front Au electrode and a back-front C electrode, respectively. It reveals that for the HTM-free CsPbI3/CsSnI3 heterojunction cells, C is a good choice for back-front electrode as it can achieve desirable cell performance with improved stability and lowered fabrication cost. These results indicate that the proposed HTM-free CsPbI3/CsSnI3 heterojunction cells are promising for photovoltaic applications.