bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser-cooling Cadmium Bosons and Fermions with Near Ultraviolet Triplet Excitations
Authors: Gibble Kurt 
Published: November 2024

Abstract
Cadmium is laser-cooled and trapped with excitations to triplet states with UVA light, first using only the 67 kHz wide 326 nm intercombination line and subsequently, for large loading rates, the 25 MHz wide 361 nm 3
P
2 → 3
D
3 transition. Eschewing the hard UV 229 nm 1
S
0 → 1
P
1 transition, only small magnetic fields gradients, less than 6 G cm−1, are required enabling a 100% transfer of atoms from the 361 nm trap to the 326 nm narrow-line trap. All 8 stable cadmium isotopes are straightforwardly trapped, including two nuclear-spin-

1
2

fermions that require no additional repumping. We observe evidence of 3
P
2 collisions limiting the number of trapped metastable atoms, report isotope shifts for 111Cd and 113Cd of the 326 nm 1
S
0 → 3
P
1, 480nm 3
P
1 → 3
S
1, and 361 nm 3
P
2 → 3
D
3 transitions, and measure the 114Cd 5s5p 3
P
2 → 5s5d 3
D
3 transition frequency to be 830 096 573(15) MHz.
Techniques on Crystal Oscillator Vibration Compensation
Authors: Mossammaparast M , Mullin P , Ronchetti L , Koehler R , Tiches N 
Published: November 2024

Abstract
Oven Controlled Crystal Oscillators (OCXOs) have been employed for precision timing and frequency distribution and synchronization applications, such as telecommunication, instrumentation, and test equipment in today’s Commercial, Military, Scientific, Space and Low Earth Orbit markets. Since 1978, Wenzel Laboratory has been researching and developing outstanding performance oscillators to provide the lowest phase noise, as low as -190dBc/Hz, and highest short-term stability for these markets. In this paper, various compensation techniques developed at Quantic Wenzel are discussed and compared. Quantic Wenzel employs such techniques to greatly improve the stability of its OCXOs in various mild to harsh vibration environments. Consequently, this lends itself to provide quieter performance in multiple applications, whether OCXOs are exposed to micro-vibration environments caused by disturbance sources onboard spacecraft or noisy environments such as a jet aircraft landing or taking off on a carrier. An example of a compact microcontroller-based vibration compensated OCXO developed at Quantic Wenzel will be presented. Such digitally controlled OCXOs can also be employed to correct for thermal drift or errors in GPS location when GPS signals become unavailable in telecom and navigation systems.
Towards Compact, Robust and Highly Stable Optical Frequency References for Space Applications
Authors: Wegehaupt T , Gohlke M , Kuschewski F , Oswald M , Abich K , Alam T , Blomberg T , Bischof J , Bußmeier A , Röder N , Wüst J , Grosse J , Sanjuan J , Schuldt T , Braxmaier C 
Published: November 2024

Abstract
Future space missions from different fields of applications, like global navigation satellite systems (GNSS), next generations of gravity missions or tests of fundamental physics will rely on optical frequency references. While laboratory setups of various optical frequency reference technologies already demonstrate frequency stabilities orders of magnitude better than current microwave references for space applications, another step must be accomplished for high performance optical references in space. One promising technology for this is Doppler-free spectroscopy of molecular iodine, for which we have already developed several iterations of laboratory setups with frequency instabilities down to the 10−15 level for integration times > 100 s. Based on the experience gained from this laboratory setups, we are now working on an iodine reference that will become the first optical clock in space as part of the COMPASSO mission. It will be delivered to the international space station in 2026 for a mission time of 2 years. In addition to the iodine development, we are currently working on a next iteration of a high-finesse optical cavity designed with emphasis on space compatibility to meet the requirements of the next generation of gravity missions. Both technologies together, the iodine spectroscopy unit and the high-finesse optical cavity, should form a hybrid setup suitable for new GNSS architectures.
DSAC and next generation high stability, long life trapped mercury ion frequency standards
Authors: Burt E.A. , Ely T.A. , Tjoelker R.L. 
Published: November 2024

Abstract
The methods of trapping and cooling of atoms and ions have been transformative for atomic clocks due to the reduction, and in some cases elimination, of major systematic frequency shifts. Continuously operating atomic clocks based on trapped mercury ions have existed for decades but until recently have been restricted to terrestrial applications. The recently completed Deep Space Atomic Clock (DSAC) mission demonstrated the first trapped ion clock operation in space. Here we review DSAC as well as follow-on improvements towards the realization of high stability, long life Hg ion atomic clocks for foreseen ground and flight application.
Hydrogen maser flywheels for optical clocks
Authors: Nemitz N , Hachisu H , Ito H , Ohtsubo N , Miyauchi Y , Morikawa M , Matsubara K , Ido T 
Published: November 2024

Abstract
We consider the statistical and systematic uncertainties that arise from using a hydrogen maser as a flywheel oscillator for an intermittently operating optical clock. Diurnal delay variations observed in the distribution and measurement of the radiofrequency signals are the most significant effects for a clock that repeatedly operates at a similar time of day. In typical operation, we find an overall systematic uncertainty contribution u
B/Lab = 2.0×10−17 for the link between the clock and the reference timescale. Data obtained over more than two years of weekly characterization measurements confirms that the real-world behaviour of the flywheel hydrogen maser is in excellent statistical agreement with our stochastic model.
Robust Optical Clocks for International Timescales (ROCIT)
Authors: Margolis H S , Godun R M , Huntemann N , Le Targat R , Pizzocaro M , Zawada M , Abgrall M. , Akamatsu D , Álvarez Martínez H , Amy-Klein A , Andia M , Benkler E , Bhatt N M , Bilicki S , Bize S , Bober M , Calonico D , Cambier V , Cantin E , Chardonnet C , Cifuentes Marín M , Clivati C , Condio S , Curtis E. A. , Czubla A , Doležal M , Dörscher S , Dunst P , Feng C-H , Filzinger M , Folman R , Fordell T , Formichella V , Foucault Y , Galleani L , Goti I , Groswasser D , Gruszczyński M , Guo C , Hanhijärvi K J , Hausser H N , Hill I R , Hosaka K , Johnson M Y H , Keller J , Klose J , Kobayashi T , Koke S , Kovačić D , Křen P , Kuhl A , Ledziński A , Lemański D , Levi F , Lindvall T , Lisdat C , Liu H , Lodewyck J , Lopez O , Lorini L , Lours M , Mašika P , Mazouth-Laurol M , Mehlstaubler T E , Moreno W , Morzyński P , Narożnik M , Nawrocki J , Nishiyama A , Nogaś P , Nordmann T , Parsons A O , Pointard B , Pottie P E , Risaro M , Robertson B I , Romero González J , Schioppo M , Sesia I , Shang H , Signorile G , Stahl K , Steinel M , Sterr U , Suárez Ramírez J , Tofful A , Tønnes M , Tran A , Tunesi J , Wallin A E , Waterholter T , Zarei M , Zyskind C 
Published: November 2024

Abstract
The recently concluded collaborative European project “Robust optical clocks for international timescales” (ROCIT) tackled some of the key challenges on the roadmap towards a redefinition of the SI second. This paper gives an overview of progress made on improving the robustness and automation of optical clocks and verifying their uncertainty budgets through coordinated international comparison campaigns. It also presents work on the incorporation of optical clocks into time scales, covering both their use to steer local physical time scales and their use for evaluations of hydrogen masers contributing data for the computation of International Atomic Time (TAI). The overall objective of the project was to bring European optical clocks to the stage where they could be operated routinely as secondary frequency standards, regularly contributing to TAI.
Atom Fountains at NTSC
Authors: Ruan Jun , Wang Xinliang , Zhang Hui , Liu Dandan , Guan Yong , Shi Junru , Bai Yang , Fan Sichen , Hao Qiang , Nie Shuai , Lei Pengyue , Zhu Ziyi , Zhang Shougang 
Published: November 2024

Abstract
Atom fountains as primary frequency standard (PFS) and continuously operated clocks have been developed to improve the local time scale at the National Time Service Center (NTSC), Chinese Academy of Sciences. Cesium fountain NTSC-CsF2 as PFS showed that the type B uncertainty was evaluated at 4.3 × 10−16. Frequency comparisons were completed between NTSC-CsF2 and the SI second through a GNSS link for 14 months, the results of which were consistent with those of the other fountains within the uncertainty. A cryogenic Cs fountain is being developed to reduce the blackbody radiation shift (BBR) and verify the BBR theory. An Rb fountain clock NTSC-RbF1 was operated to generate local and EAL time scale. The frequency drift was reduced by maintaining a stable vapor pressure. NTSC-RbF2 features a more robust optical system consisting of all fiber-optical components and an ultra-stable OCXO as a local oscillator. An instability time scale below 100 ps is expected based on the Rb atom fountain clocks.
Compact and Robust Laser System for a Transportable Strontium Optical Lattice Clock
Authors: Muramatsu T , Hiroki T , Sakai Y , Hisai Y , Furumiya T , Uno S , Tojo K , Takamoto M , Katori H 
Published: November 2024

Abstract
We developed a laser system for a Sr optical lattice clock to down-size and improve robustness and maintainability. The optics were fixed by laser welding to prevent misalignment during transportation and operation. The volume of the laser system was reduced by removing adjustable mechanisms and integrating multi-function electronics. By utilizing the developed laser system, the volume of optical lattice clocks was down to 250 L.
Sr Optical Lattice Clock and Precision Optical Frequency Measurement at NIM
Authors: Yang T. , Lu B. , Zhu L. , Liao T. , Wang Q. , Li Y. , Meng F. , Lin B. , Wang Y. , Fang F. , Lin Y. , Fang Z. 
Published: November 2024

Abstract
Two Sr optical lattice clocks are being built at the National Institute of Metrology of China (NIM). Sr1 was built on NIM’s Hepingli Campus. It was first evaluated in 2015 and improved later on. In 2021, the systematic shift uncertainty of Sr1 was evaluated to be 2.9 × 10−17. Sr2 was started to be built on NIM’s Changping Campus in 2017. The systematic shift uncertainty of Sr2 was evaluated to be 7.2 × 10−18 in 2022. With a new BBR optimizing process, the total BBR uncertainty of Sr2 is reduced to 4.6 × 10−18 which corresponds to the total uncertainty of Sr2 is evaluated to 6.5 × 10−18 in 2023. To compare these two Sr clocks, an optical frequency transfer fiber link with a length of 54 km was established between these two clocks. A preliminary study of generating a local time scale with Sr1 has been carried out at NIM. The time scale generated by post-processing of the comparison data between Sr1 and an H-maser demonstrated better stability than the time scale steered by UTC.
High-accuracy multi-ion spectroscopy with mixed-species Coulomb crystals
Authors: Keller J. , Hausser H. N. , Richter I. M. , Nordmann T. , Bhatt N. M. , Kiethe J. , Liu H. , Benkler E. , Lipphardt B. , Dörscher S. , Stahl K. , Klose J. , Lisdat C. , Filzinger M. , Huntemann N. , Peik E. , Mehlstäubler T. E. 
Published: November 2024

Abstract
Multi-ion optical clocks offer the possibility of overcoming the low signal-to-noise ratio of single-ion clocks, while still providing low systematic uncertainties. We present simultaneous spectroscopy of up to four 115 In+ clock ions in a linear Coulomb crystal, sympathetically cooled with 172Yb+ ions. In first clock comparisons, we see agreement below 1 × 10−17 with results obtained using a single In+ ion, for which we have evaluated the systematic uncertainty to be 2.5 × 10−18. Operation with four clock ions reduces the instability from

1.6
×

10

−
15

/

t
/
(
1
s
)

to

9.2
×

10

−
16

/

t
/
(
1
s
)

. We derive a model for decay-related dead time during state preparation, which matches the observed scaling of instability with clock ion number N, and indicates that

1
/

N

scaling can be achieved with the addition of a repump laser.
Towards a sub-kelvin cryogenic Fabry-Perot silicon cavity
Authors: Barbarat Joannès , Gillot Jonathan , Millo Jacques , Lacroûte Clément , Legero Thomas , Giordano Vincent , Kersalè Yann 
Published: November 2024

Abstract
We report on the development of a sub-kelvin, single-crystal silicon Fabry-Perot cavity. Operating such a cavity below 1 K should reduce the thermal noise limit of the cavity, and by this way address the current limitations of ultrastable lasers. To further decrease mechanical losses, mirrors with silicon substrates and crystalline coatings are optically contacted to the spacer, resulting in a room-temperature finesse of 220,000. To operate our cavity at sub-kelvin temperatures, we use a dilution refrigerator able to reach temperatures down to 10 mK. We have designed a mechanical mount to house our cavity in such a cryostat, with optimized heat transfer that will decrease the cooldown time for temperatures below 1 K. The estimated thermal noise is projected to be ∼ 7×10−19 at 100 mK. However, silicon cavities with crystalline mirror coatings at cryogenic temperatures have shown birefringence correlated frequency fluctuations as well as unknown additional noise mechanisms [1, 2]. We have measured a room-temperature TEM00 birefringent mode splitting of about 250 kHz. Understanding and measuring these noise mechanisms will be a key to attaining fractional frequency stabilities beyond state-of-the-art.
Crystal Grain Rotation during Tensile Test of Polycrystalline Pure Titanium Thin Sheet Based on Surface Height and Crystal Orientation
Authors: Tada Naoya , Ohashi Hiroaki , Uemori Takeshi , Sakamoto Junji 
Published: November 2024

Abstract
Thin sheets and wires of polycrystalline pure titanium are important materials for various devices used in electrical, mechanical, dental, and medical fields. Since pure titanium shows strong anisotropy in elastic and plastic deformation, and the individual grains comprising a polycrystalline body have different orientations and geometries, inhomogeneous deformation always occurs on the microscopic scale. This inhomogeneity is more significant in thin films than in bulk materials. It is therefore important to investigate the inhomogeneous deformation of pure titanium thin sheets to ensure the reliability of various titanium devices. In this study, thin-sheet specimens made of polycrystalline pure titanium were subjected to tensile testing. Inhomogeneous deformation was evaluated on the basis of two kinds of crystal grain rotations based on surface height and crystal orientation. The results under elastic and plastic tensile conditions were compared.
A User Satisfaction Enhancement Method for Low-Carbon Electromechanical Products Based on Design Knowledge Graphs
Authors: Wang Zhenzhe , Zhu Shuo , Jiang Zhigang , Yan Wei , Zhang Hua , Zhou Tingting 
Published: November 2024

Abstract
Enhancing user satisfaction is crucial for the widespread adoption of low-carbon electromechanical products. However, the low-carbon design of electromechanical products involves multiple aspects, such as product functionality, structural design, and material selection, each needing to balance user performance needs with low-carbon characteristics. Traditional methods often struggle to optimize these design aspects simultaneously, leading to lower market acceptance and reduced product competitiveness. To address this, a method for improving user satisfaction with low-carbon electromechanical products based on a design knowledge graph is proposed. This method starts with analyzing the design process of the product’s function, structure, and materials to filter out design knowledge that meets user needs through performance satisfaction and carbon emissions evaluations. It then constructs a design knowledge graph and employs a graph optimization algorithm to efficiently explore product structure and material information, generating and recommending solutions that optimize performance satisfaction and cost. Finally, a typical home appliance refrigerator is taken as an example to verify the effectiveness of the proposed method.
The effect of Al on microstructure and properties of Cu-15Ni-8Sn during the aging
Authors: Hong Songbai , Luo Wei , Wang Dongya , Luo Yi , Li Xuehua , Liu Feng 
Published: November 2024

Abstract
In this paper, microstructure evlution, hardness and tensile properties of Cu-15Ni-8Sn-(0.5Al) alloys during aging at 500°C were investigated in detail. The results showed that the grain was refined and the elongation of alloy at solid solution was improved with the additon.of Al. The DO22 ordered phase was suppressed during aging in the Cu-15Ni-8Sn-0.5Al alloy, while the L12 ordered phase stability was significantly improved. Therefore, the L12 ordered phase was not consumed by the discontinuous precipitation (DP) reaction during the prolonged aging process, which effectively suppressed the development of DP and improved the resistance to over-aging of the alloy. However, Al also leads to a serious decrease in the plasticity of Cu-15Ni-8Sn alloys, which has no yield point during tensile process after aging for 1h.
Investigation of ballistic performance of aramid fabrics modified by polyethylene and graphene in high temperature and humidity environments
Authors: Liu Peng , Wang Zhe , Zhang Hong , Huang Guangyan 
Published: November 2024

Abstract
In today’s world, conflicts are constant, and the environment in world is complex and diverse. The aging of bulletproof vests has become increasingly important. To investigate the environmental adaptability of polyethylene and graphene modified aramid fabrics, this study subjected the modified fabrics to high-temperature and humidity cycling treatments, followed by ballistic experiments to compare the ballistic limits of the fabrics. Various environmental factors affecting the ballistic performance of different fabrics were analyzed. The experimental results indicate that the ballistic performance of pure aramid fabrics is minimally affected by temperature and humidity, demonstrating strong stability. As the temperature increases, the ballistic limits of the modified fabrics gradually decrease; however, the decline is relatively small, at only 9.5%. The use of graphene can resist the effects of humidity and heat to some extent: under 120°C and humidity cycling conditions, the graphene modified fabric outperforms the polyethylene modified fabric. Furthermore, temperature has almost no effect on the failure modes of the various fabrics.
Aerodynamic and aeroacoustic analysis of a model UAV propeller
Authors: Szulc O , Flaszyński P , Suresh T 
Published: November 2024

Abstract
The paper summarizes the development and validation of an in-house Ffowcs-Williams and Hawkings (FW–H) aeroacoustic solver and its application to a low-Reynolds number two-bladed model propeller of an Unmanned Aerial Vehicle (UAV) investigated experimentally at TUD (Technical University of Delft). It is based on Farassat’s Formulation 1A of the solution to FW–H acoustic analogy allowing for harmonic and broadband noise analysis (monopole and dipol contributions). Initially, the validation process is presented for elementary rotating and fluctuating momentum sources (forces) with available analytical solutions. Next, the propeller of TUD is simulated with block-structured, compressible flow solver FLOWer (DLR, Germany) based on RANS/SALSA (Strain Adaptive Linear Spalart-Allmaras) and DES/k–ω SST (Shear-Stress Transport) approaches to turbulence modeling and with the second and fourth-order numerical schemes. The predicted rotor aerodynamic performance is compared against the experimental data (tripped cases only) for rotational speed of 5000 RPM (tip Mach number of 0.23) and wide range of advance ratio J. Finally, for hover conditions (J = 0) and an in-plane observer location, the predicted surface pressure fluctuations are used as input for FW–H acoustic analysis and the resultant propeller Sound Pressure Level (SPL) signature is compared with the measured spectrum.
Validation of Yamaguchi-Ichikawa water hammer model
Authors: Urbanowicz K , Di Nucci C , Sharma B K , Ashok K , Krajewski S 
Published: November 2024

Abstract
This study comprehensively analyses the Yamaguchi-Ichikawa (YI) model for water hammer phenomena in hydraulic systems, alongside recent theoretical studies and experiments. While promising initially, comparative investigations reveal limitations in the YI model’s alignment with experimental data, particularly regarding initial conditions and pulsation periodicity. These shortcomings, including the absence of a phase shift, may hinder its applicability in complex pressure systems with multiple wave reflections. The research focuses on analyzing analytical models that describe the phenomenon of water hammer. These models enable the proposal of future research directions, integrating theoretical models with experimental observations.
Revisiting homogeneous modeling with volume averaging theory: structured catalysts for steam reforming and CO2 methanation
Authors: Medina Méndez J A , Dorneanu B , Schmidt H , Arellano-García H 
Published: November 2024

Abstract
Progress in the modeling of structured catalysts is crucial for enhancing efficiency and scalability in industrial applications. Extensive research has investigated reactive flows over catalyst surfaces, covering chemical kinetics analysis and (direct) numerical simulations of the complete fluid flow in fixed-bed or structured catalysts. Nonetheless, this comes at a high computational cost. This study focuses on the homogeneous modeling of structured catalysts utilizing volume-averaging theory (VAT) as a more efficient method for representing the behaviour of such systems. We discuss modeling strategies for both 1-D and 3-D simulations. For steady 1-D flow simulations, we assess the influence of simplified gas chemical kinetics versus detailed surface chemistry, comparing with experimental data from the literature for a CO2 methanation processes. We also simulate 3-D flows of a steam reforming process, previously studied in the literature, using models which rely on different assumptions regarding the nature of the porous catalyst. Our findings reveal significant discrepancies based on different modeling assumptions, underscoring the necessity for accurate modeling of permeability and diffusivity tensors in homogeneous models.
Numerical investigation of fill height and secondary currents in an inclined partially filled pipe flow
Authors: Bose Aniruddha , Borman Duncan J , Hunter Timothy N , Spencer Julian T , Cunliffe Christopher J 
Published: November 2024

Abstract
Partially filled pipes are used in industrial processes to transport liquid and particle laden flows. A good understanding of the three-dimensional flow in these pipes is critical to ensure material is transported without issue, for example without particulates settling out. In this work, air-water two-phase flows in a partially filled pipe geometry of an industrial slurry transport rig are investigated using unsteady Volume of Fluid (VOF) RANS model in OpenFOAM to investigate fill height and secondary currents. Both are important factors in partially filled pipes where the water depth and secondary current strength can influence solid particle transport and settling. The study confirms that the CFD approach can reliably predict the flow depth across a range of pipe inclination and the secondary currents are predicted in good qualitative agreement with those seen in other studies. The effect of pipe inclination on fill height and the effect of fill height on secondary currents are investigated for a range of mass flow rates. The results of fill height agree well with the experiments and are in line with the Manning equation for a hydraulically smooth pipe. Secondary current strength is seen to increase with fill height in agreement with other studies.