bluuebunny/crossref_metadata_2025 huggingface dataset:
First-principles study of robust half-metallic ferromagnetism and electronic structure of the Heusler compounds Co2-xCrxMnGe
Authors: Dey Sarkar Mainak , Ghosh Sulagna , Sanyal Dirtha , Jana Debnarayan
Published: December 2024

Half-metallic ferromagnets (HMFs) are among the most promising materials in the field of spintronics because of their distinct band structures, which consist of two characteristic subbands, one with semiconductor-like behaviour and the other with metallic features. Using density functional theory-based calculations, we have carried out in-depth studies to predict the effects of Co replacement by Cr on electronic structure as well as the magnetic properties of Co2-xCrxMnGe with 0 ≤ x ≤ 1. The results demonstrate that the alloys are stable in the ferromagnetic phase with half-metallic nature. The origin of ferromagnetism can be explained by Ruderman-Kittel-Kasuya-Yosida (RKKY), like exchange interaction. Due to their high Curie temperatures, which increase linearly with the total magnetic moment, all alloys are suitable for applications at and above room temperature. Besides, the electronic properties have revealed a transition from half-metallic to semi-metallic character for higher doping concentration (x = 0.75, x = 1.0). The calculated total magnetic moments, however, decrease with increasing doping concentration, consistent with the Slater-Pauling rule. The observed high value of spin polarisation of all the studied compounds suggests their futuristic roadmaps for possible spintronics applications beyond room temperature.
Stream ciphers for digital image transactions by learning quantum true random numbers
Authors: Bao Zhenjie , Wan Changsheng , Phoha Vir Virander , Hu Yichen , Zhang Juan , Xu Wenda , Chen Haitao
Published: December 2024

The digital economy drives a surge in online digital image transactions, increasing the risk of data breaches due to extensive image file transmission. Stream ciphers, known for their efficiency compared to block ciphers, have emerged as a preferred choice for encrypting images in such transactions to safeguard transmitted data. Nevertheless, traditional stream cipher algorithms face diverse security threats. To address this challenge, efforts have been devoted to generating stream ciphers by generative adversarial networks (GANs) transforming input style into random patterns. Regrettably, these ciphers face issues in key sensitivity, randomness, and style transformation failures. Quantum true random numbers offer a potential solution but are costly to deploy. To handle this dilemma, we design stream ciphers relied on a neural network random number generator (RNG) using quantum true random numbers for training least squares GANs. Specifically, two fully-connected layers are incorporated into the RNG, avoiding the defects of style transformation in existing GANs-based stream ciphers. Besides, a random number calculation formula is employed to ensure that each decimal place output by the generator contributes to the computation of the random numbers. By doing so, the randomness of GANs is enhanced and the deployment of costly quantum devices is avoided. Experiments reveal that the information entropy of our generated images reaches to 7.9991, the adjacent pixel correlation coefficient of the ciphertext attains -0.0015, the Number of Pixel Change Rate and Unified Average Changing Intensity achieve 99.62% and 33.52%, respectively. These results demonstrate that the designed RNG facilitates randomness, whilst having secure properties applied in stream ciphers.
High-performance dual-core photonic crystal fiber polarization beam splitter based on gold-titania composite film coating
Authors: Liu Yundong , Wang Yujun , Liu Hualin , Shi Nianfeng , Li Yingying , Meng Xiaojian
Published: December 2024

A novel gold-titania composite film-coated dual-core photonic crystal fiber polarization beam splitter (GT-DC-PCF PBS) is proposed for the first time. The titania film and gold film are sequentially deposited on the inner wall of the central air hole to improve the polarization splitting performance and enhance the adsorption strength between the gold film and the optical fiber. Based on the mode coupling theory and surface plasmon resonance effect, the transmission characteristics of x-polarization (X-pol) and y-polarization (Y-pol) odd and even modes in the near-infrared band are analyzed by finite element method. Meanwhile, the variation of coupling length and coupling length ratio for X-pol and Y-pol light under different PCF structural parameters at the wavelength of 1550 nm are also studied to optimize the performance of PBS. The results show that at the 1550 nm communication window, the extinction ratio of the PBS is up to −175.82 dB for the polarization splitting length of 2.76 mm, with an operating bandwidth of 179 nm and a maximum insertion loss of 0.23 dB. This paper aims to propose a novel design method to improve the performance of DC-PCF PBS, which has profound guiding significance for the development of high-performance PBS.
Application of nanocrystalline spinel MFe2O4, (M=Co and Cu) in waste water treatment
Authors: G R Vasudha , Rai M Vaishali , Venugopal Deepa Mugudthi , Varija Raghu Shamprasad , Narayana Yerol
Published: December 2024

Transition metal spinel ferrites MFe2O4 (M=Cu and Co) were successfully synthesized following the co-precipitation method and their structural, optical, photocatalytic, antimicrobial and toxicity properties were studied. The characterization of the title compounds has been carried out using XRD, SEM, EDS, FT-IR and UV–vis DRS spectroscopy. The XRD studies confirmed a cubic spinel structure with the Fd-3m space group, and CuFe2O4 and CoFe2O4 exist in the nanocrystalline size of 20 nm and 16 nm, respectively. The SEM images revealed the agglomerated nature of the ferrite nanoparticles, and the EDAX spectrum confirmed the samples elemental compositions and purity. The FT-IR spectra indicated the presence of metal-oxygen stretching bands. The ferrite samples demonstrated photocatalytic activity in the visible region, as assessed by methylene blue (MB) degradation in an aqueous solution under visible irradiation. After 105 min, CuFe2O4 and CoFe2O4 catalysts exhibited 72% and 56% degradation for the MB solution. Through broth dilution, MFe2O4 (M=Cu and Co) nanoparticles were evaluated for their antimicrobial activity using S. aureus and E. coli, a gram-positive and gram-negative bacterium, respectively. Studies indicated that CoFe2O4 nanoparticles exhibit better antibacterial activity when compared to CuFe2O4. However, the antifungal activity study indicated that CuFe2O4 nanoparticles exhibit better antifungal activity when compared to CoFe2O4 nanoparticles. The toxicity of the nanomaterials was tested by mixing MFe2O4 (M=Cu and Co) with normal fly food and administering it orally to Drosophila melanogaster. The results indicated that the functionalized CuFe2O4 nanoparticles are less toxic to living organisms. Hence, optimized nanocrystalline spinel has the potential to degrade dyes from polluted water and act as an antimicrobial agent by rupturing pathogen cells. They have potential applications in both environmental safety and biomedicine.
Constraints on the primordial black hole abundance through scalar-induced gravitational waves from Advanced LIGO and Virgo's first three observing runs
Authors: Jiang Yang , Yuan Chen , Li Chong-Zhi , Huang Qing-Guo
Published: December 2024

As a promising dark matter candidate, primordial black holes (PBHs) lighter than
∼ 10-18
M
⊙ are supposed to have evaporated by today through Hawking radiation. This
scenario is challenged by the memory burden effect, which suggests that the evaporation of black
holes may slow down significantly after they have emitted about half of their initial mass. We
explore the astrophysical implications of the memory burden effect on the PBH abundance by today
and the possibility for PBHs lighter than ∼ 10-18
M
⊙ to persist as dark matter. Our
analysis utilizes current LIGO-Virgo-KAGRA data to constrain the primordial power spectrum and
infer the PBH abundance. We find a null detection of scalar-induced gravitational waves that
accompanied the formation of the PBHs. Then we find that PBHs are ruled out within the mass range
∼ [10-24,10-19]M
⊙. Furthermore, we expect that next-generation gravitational
wave detectors, such as the Einstein Telescope and the Cosmic Explorer, will provide even more
stringent constraints. Our results indicate that future detectors can reach sensitivities that
could rule out PBH as dark matter within ∼ [10-29
M
⊙,10-16
M
⊙] in the null
detection of scalar-induced gravitational waves.
Preparing Al2O3/TiO2 nano-multilayers on the surface of FeAl/Al2O3 coating as tritium permeation barrier
Authors: Guo Enkai , He Yifu , Zhong Fen , Fu Bowen , Wang Kun , Cai Guangxu , Jiang Changzhong , Ren Feng
Published: December 2024

Preparing tritium permeation barrier (TPB) coating on the surface of structural materials can effectively alleviate tritium permeation in fusion reactor system. However, due to the existence of inevitable certain number of defects in TPB, there is still a gap between the commonly prepared TPB coatings and the requirements proposed by fusion reactors. In this work, composite coatings with Al2O3/TiO2 nano-multilayers (NMLs) covering on the surface of FeAl/Al2O3 coating were prepared as TPB. The FeAl/Al2O3 TPB coating on the surface of 316L stainless steel was prepared by electrochemical deposition of Al, aluminization and in-situ oxidation. Due to the aggregation of Cr, there are micro sized defects in the Al2O3 layer. The presence of defects seriously reduces its hydrogen isotopes permeation resistance. The atomic layer deposition was then adopted to prepare Al2O3/TiO2 NMLs with period thickness of 15, 7.5 and 3 nm on the surface of Al2O3 layer, which not only cover the defects, but also utilize interfaces to suppress hydrogen isotopes permeation. The composite coating sample with the period thickness of 3 nm showed great enhancement of two orders of magnitude in deuterium permeation resistance property compared to the original FeAl/Al2O3 TPB coating at 500 °C, and the permeation reduction factor reaches a high value of 5 × 105, which far above the requirements of future fusion reactors.
Sensor fault estimation based on double model adaptive method for dynamic Point-the-bit rotary steerable systems
Authors: Shao Mingzhu , Geng Yanfeng , Wang Weiliang , Huang Shuaishuai
Published: December 2024

The dynamic point-the-bit rotary steerable system (DPRSS) is utilized to accomplish superior control of the drilling trajectory in oil and gas operations. However, sensor faults may undermine the reliability of DPRSS. This study focuses on the estimation of sensor faults in DPRSS. First, the DPRSS is modelled as a linear system subjected to drilling disturbances. The model integrates the rotational speed of the drill collar within its system state equations and incorporates prior knowledge about the stabilized platform. Afterward, the Double Model Adaptive Estimation (DMAE) algorithm is employed to estimate the system state, the unknown inputs, and sensor faults. Lastly, simulations and experimental results are presented to demonstrate the efficacy of the DMAE method in estimating sensor faults.
Application of cuttings natural gamma spectroscopy logging technology in well A-1
Authors: Bing Lei , Yu Yi , Zang Fali , Zhang Xinghua
Published: December 2024

The H-1 well revealed significant disparities between the Paleozoic strata in the Northern Jiangsu Basin and the anticipated stratigraphy prior to drilling, posing substantial challenges to the swift determination of stratigraphic ages at the site. Geological logging can obtain very limited data, such as rock color and lithology, and falls short of achieving precise lithologic identification and detailed stratification; while the X-ray diffraction logging(XRD) can initially analyze mineral content, it is unable to delineate the classification of clay mineral species.Cuttings natural gamma spectroscopy logging can precisely analyze the gamma-ray energy spectrum produced by the decay of radioactive isotopes within the formation, primarily comprising potassium, thorium, and uranium.The concentrations of Uranium (U), Thorium (Th), and Potassium (K) in rocks are intimately associate with the lithology, the extent of organic matter content, and the sedimentary environment . This technology facilitates the quantitative assessment of potassium, thorium, and uranium content within the formation. Its application has proven to be crucial for accurately identifying lithologies, conducting detailed stratigraphic comparisons, performing in-depth sedimentary environment analyses, and evaluating organic matter content.The cuttings natural gamma spectroscopy data of H-1 well shows good correlation with the natural gamma logging data, which can meet the requirements of accurate lithology identification; the rocks of different strata in the analytical map can meet the requirements of fine stratum division; the correlation coefficient between U element content and Total Organic Carbon (TOC) content is up to 0.974, which is feasible to calculate the TOC with U element content; finally, the deposition environment analysis based on natural gamma spectral recording confirmed by the analysis of trace elements.
Application of nuclear magnetic resonance core logging technology in oil and gas exploration of deep/ultra deep low porosity and low permeability reservoirs
Authors: Wang Xin , Ji Jianfei , Yin Sai
Published: December 2024

In order to improve the efficiency of deep/ultra deep oil and gas exploration decision-making and release production capacity, and to address the difficulties in implementing the physical and fluid properties of complex deep/ultra deep reservoirs, nuclear magnetic resonance logging technology is used to establish a permeability calculation method and a glutenite reservoir pore structure evaluation method so that the liquid production capacity of the reservoir is classified. Combing nuclear magnetic resonance logging with gas logging technology, an comprehensive hydrocarbon evaluation index SI is established to evaluate complex fluid properties. The results show that: (1) The permeability calculated by T2gm using nuclear magnetic resonance logging spectra is highly consistent with laboratory measurement results. (2) By combining the nuclear magnetic porosity and permeability of the test layer with the pore structure parameters calculated by nuclear magnetic, a classification standard for low porosity and low permeability glutenite reservoirs can be established, which can provide a preliminary evaluation of the reservoir’s liquid production capacity. (3) The comprehensive evaluation chart of nuclear magnetic resonance logging combining with gas logging can effectively distinguish oil layers, gas layers, and water layers, thereby distinguishing complex fluid properties. This research achievement is of great value for implementing the physical and fluid properties of deep/ultra deep complex reservoirs in Bohai Oilfield, and guiding efficient exploration and development operations.
Prediction of waxing degree in oil wells based on the frost optimizer algorithm
Authors: Wu Jiaqi , Yuan Chunhua , Li Xiangyu
Published: December 2024

Monitoring wax deposition in oil wells becomes increasingly difficult in the complex and extended downhole working conditions, where direct measurement is often impractical. Over time, wax buildup intensifies, affecting oil production and equipment functionality. The degree of wax deposition in oil wells is difficult to measure. This paper proposes a predictive strategy for rod pumping well operations. It integrates the Crested Porcupine Optimizer (CPO) optimization algorithm with Variational Mode Decomposition (VMD) decomposition, selecting suitable K and α values for the electrical power of oil wells. The Rime improves Long Short-Term Memory (RIME-LSTM) network forecasts each mode component, and the final prediction is obtained by summing these values. The method’s performance was validated using real power time series data from four wells over a specific period. The coefficient of determination (R²) and mean absolute percentage error (MAPE) evaluated the models, confirming effectiveness. Finally, a rating strategy for wax deposition predicts when to perform shutdown cleaning before severe accumulation occurs, thus protecting the oil pump and preventing low production rates. This article studies the prediction of downhole technology and wax deposition degree in oil wells, and proves its effectiveness through experiments.
Design of a downhole dynamic recorder based on flash memory
Authors: Sun Chengqin , Hu Yongjian , Sun Qi , Zhang Guanjie , Zhang Qimengsha , Xiao Meng
Published: December 2024

In response to the current demand for drilling cost reduction, efficiency improvement, and drilling safety in the drilling process, it is necessary to collect a large amount of real-time downhole measurement data to achieve real-time monitoring of wellbore pressure, drilling tool efficiency,and drilling speed.Nowadays,traditional while drilling measuring instruments have disadvantages such as small storage capacity, large volume, and easy loss of power due to power failure.Therefore, designing a downhole dynamic recorder based on NAND (Non-And) large capacity memory, using a small, low-power, and fast reading NAND flash memory, combined with a high-performance processor microcontroller, can achieve high-speed data access.Through calculating its theoretical storage value,removing the influence of bad blocks, the storage capacity can be increased by more than three times compared to before optimization. Data reading, writing, and erasing can be significantly improved too, and it has non volatility due to power failure. This product can record real-time data such as triaxial vibration, pressure, rotational speed, and stickiness during the drilling process, which helps to understand the situation of downhole drilling operations, optimize parameters, analyze wellbore instability and drilling tool failure, improve drilling efficiency, reduce well construction costs, and provide important reference basis for intelligent drilling operations.
Oil well fault diagnosis method based on markov transition field and convolutional neural network-long short-term memory
Authors: Zhang Shuai , Li Xiangyu , Yuan Chunhua
Published: December 2024

The analysis of electrical parameters and fault diagnosis in oil wells is crucial in the petroleum industry. Traditional methods often struggle to accurately capture the characteristics of time-series data, resulting in inadequate diagnostic precision. This study investigates a novel approach to improving feature extraction and fault diagnosis of electrical parameter data from oil wells. Specifically, the paper proposes encoding oil well electrical parameter data into two-dimensional images using the Markov Transition Field (MTF) technique to generate an oil well fault dataset. By incorporating the Squeeze-and-Excitation (SE) attention mechanism, the enhanced Convolutional Neural Network-Long Short-Term Memory (CNN-LSTM) model demonstrates more efficient feature extraction capabilities in oil well fault classification. Experimental results show that this method achieves a fault diagnosis accuracy of 96.7%, significantly surpassing the traditional method’s 92.7%.This research provides an effective solution for improving the precision of fault diagnosis in pumping units, thereby enhancing the safety and economic efficiency of oil well operations.
Development a novel gas chromatography-mass spectrometry equipment for rapid offshore oil and gas logging
Authors: Hao Wei , Wang Huan , Shi Zhe
Published: December 2024

With the development of offshore oil and gas exploration, the exploration area and region are constantly expanding, and the demand for efficient and accurate response of drilling real-time oil and gas data is becoming increasingly urgent. In response to this demand, this paper introduces a new fast field oil and gas logging instrument based on gas chromatography-mass spectrometry technology, which increases the measurement speed of existing instruments by more than 2 times. Conventional gas phase logging methods can only measure light hydrocarbon components (C1-C5) data, but cannot measure heavy hydrocarbon components (C6-C8), which are the key data reflecting oil content. For this reason, the FLAIR gas chromatography-mass spectrometer developed by Schlumberger can detect gaseous and liquid alkanes within 90 seconds. However, during offshore drilling, this detection method is slow and cannot guarantee real-time detection, and data loss may occur in key formations. In response to the above problems, we have developed a fast field oil and gas logging instrument based on chromatography-mass spectrometry technology. The instrument creatively uses mass spectrometry real-time decomposition technology to complete the detection of C1-C8 components within 45 seconds, completely solving the problem of rapid on-site determination of C1-C8 multi-components, and the on-site experiment has the same accuracy as the FLAIR instrument. The instrument can significantly improve the speed and quality of on-site measurement data, thereby improving the production efficiency and decision-making ability of offshore drilling platforms. The instrument has a wide range of application potential and may even become an essential instrument for conventional oil and gas exploration in the future.
Research on Active Power Loss Distribution of Components in Magnetic Coupling Wired Drill Pipe
Authors: Jia Jia , Shen Yue , Zhang Xiuwen
Published: December 2024

The magnetic coupling wired drill pipe achieves high-speed information transmission by installing cable at the rod and embedding magnetic couplers at the joints. However, significant energy attenuation in these connected wired drill pipes necessitates the addition of relay circuit compensation every few hundred meters, increasing system complexity and cost. The equivalent circuit of magnetic coupling wired drill pipe can be regarded as a series connection of a coaxial cable line, high-frequency transformer, and terminal load. Exploring better wired drill pipe parameters to distribute signal power across different frequencies will optimize power at the terminal load and improve relay distance. This research establishes a mathematical model for active power distribution in magnetic coupling wired drill pipes based on circuit analysis. The model’s accuracy is validated through circuit simulation and numerical analysis. Reducing signal energy attenuation in the cable and coupler is achieved by increasing the coil coupling coefficient, reducing the coil resistance, and altering the characteristic impedance of the coaxial cable. This research provides a theoretical tool for analysing active power loss distribution of components in wired drill pipe.
Application of perforation pressure gauge in offshore ARP+TCP combined well testing
Authors: Yang Yi , Bai Linkun , Zhao Hongtao
Published: December 2024

The Annulus Pressure Responsive (Hereinafter called ARP) + Tubing Conveyed Perforating (Hereinafter called TCP) combined test technology is widely used in the offshore exploration well. However, the perforation will produce a huge impact load instantaneously and pose a certain threat to the safety of the test column. Researchers usually use numerical simulation method to analyze the dynamic response and stress intensity of the column to achieve the purpose of optimizing it, but the numerical method usually requires a large number of parameters and is inconvenient to apply in the field operation. In this paper, combined with the real data measured by the perforation pressure gauge, a simple and useful prediction formula for the peak perforation pressure was established. The relative error between predicted and measured value was 2.83% and 13.92% respectively for verification by two example Wells. The rapid prediction of peak pressure provides theoretical guidance for optimizing and adjusting test string and perforation parameters and improving operation safety.
Force analysis and optimization design of flexible connection shafts with centerline passing
Authors: Wang Zhiguo , Shi Hongjiang , Sun Qi , Chen Mingzhang , Lu Yiping , Yang Wenjing
Published: December 2024

In response to the design and research of downhole signals transmitted through cables for drilling instruments, the wire passing structure of the cross screw motor is particularly crucial. A preliminary analysis and summary of the material characteristics and stress analysis of its bending tube were conducted. The analysis shows that, under the premise of verifying the strength composite design requirements of its mechanical structure and material performance, the bending tube is subjected to multiple effects of working conditions such as internal stress and alternating load, Gradually forming dangerous cross-sections and stress concentration areas, thereby increasing the risk of fatigue fracture failure. In addition, structural design and material adjustments were made to the stress concentration area, optimizing and improving the contact head structure of the flexible tube. This was verified through material performance analysis, further improving the service life of the flexible tube.
Continuous measurement assists dynamic adjustment of wellbore trajectory
Authors: Sun Quanhua , Yue Bujiang , Li Na , Ma Huibin , Song Dianguang , Shi Lin , Mao Xing
Published: December 2024

In the process of directional well drilling, how to accurately model the real-time well trajectory is of great significance to improving the reservoir encounter rate and recovery rate. This paper provides a method to improve the accuracy of well trajectory by cleaning and correcting the continuous measurement data in combination with fixed measurement data, and then using the continuous measurement data for trajectory modeling. The continuous measurement data comes from the CG-STEER rotary steerable system. The well trajectory calculated by the continuous measurement data corrected by the above method greatly reduces the vertical depth calculation error during the drilling process, and effectively reduces the vertical depth error accumulation caused by the large spacing between fixed measurement points. It can effectively improve the drilling target accuracy and horizontal section penetration rate, and reduce invalid drilling.
Real-time error analysis and anti-collision evaluation of cluster well trajectory
Authors: Zhang Zhifa , Liu Wei , Qian Haodong , Wang Zhendong , Peng Taojun , Zhang Fan , Tian Peiyu
Published: December 2024

The shale gas in Sichuan Basin adopts the horizontal well development mode of well factory, which can reduce the investment cost of exploration and development. However, due to the small well spacing of cluster platform wells, the risk of collision between current wells and adjacent wells is high, so it is necessary to conduct real-time trajectory error analysis and anti-collision evaluation. Usually, the anti-collision monitoring of cluster well trajectory is mostly carried out by field personnel after drilling for a certain distance, and the efficiency of anti-collision analysis is slow. With the popularization of digital drilling site, the timeliness of borehole trajectory data acquisition is guaranteed. Therefore, a set of anti-collision evaluation method of computer real-time trajectory error analyzer is proposed by means of computer analysis, so as to improve the efficiency of borehole trajectory anti-collision monitoring and reduce the risk of borehole collision, this method features high efficiency in collision prevention analysis and accurate collision prevention analysis results, making it an essential component of real-time collision prevention analysis for wellbore trajectory drilling. The study focuses on the analysis of two wells in a formation in the Sichuan-Chongqing region. Results indicate that in the well section at a depth of 597 meters, the separation coefficient is less than 1.5, suggesting a significant collision risk between the two wellbores. In this paper, the ISCWSA (Industry Steering Committee for Wellbore Survey Accuracy) error model, based on the borehole error theory and the calculation method of separation coefficient, combined with the real-time data acquisition of borehole trajectory, is used to form the real-time error analysis and anti-collision evaluation method of cluster well trajectory, which provides an effective technical means for realizing real-time anti-collision monitoring of trajectory while drilling. It is an important link in digital drilling, and it also puts forward an important method for intelligent decision analysis of intelligent drilling trajectory in the future.
Dynamics modeling and analysis of a down-hole drill string multibody system based on the absolute coordinate formulation
Authors: Fang Chao , Li HaiQuan , Liu Wei , Xu ZhaoHui , Liao MaoLin , Fan JinChao , Lin ZiLi , Pang HaiBo
Published: December 2024

Drilling system dynamics is the basis of studying the interaction between components in drilling process, which needs to solve many difficult problems such as geometric nonlinear dynamics of drill string, contact between drill string and wellbore, solving timeliness and so on. The existing research on establishing dynamic unit of local drilling tool structure has low solution efficiency, and it is difficult to meet the requirements of directional trajectory control and drilling speed increase analysis efficiently. Dynamics model of a downhole drill string system is established by using the multibody system dynamics method in this study. The natural coordinate formulation and the absolute nodal coordinate formulation are adopted to describe the rigid parts and the flexible beams, respectively. The presented model can be used to analyze the dynamic characteristics of the drill string system and the interaction between the drill string and the environment such as the wellbore and rocks in the drilling process. Finally, through comparative analysis with on-site test data, the correctness of the multibody dynamic model of the drill string system established in this paper was preliminarily verified.
Analysis of the coupling coefficient in non-contact magnetic couplers for rotary steering systems
Authors: Hou Shugang , Qiu Jun , Wang Huaping , Liu Naipeng , Wang Maokun , Liu Shiying
Published: December 2024

The coupling coefficient of the magnetic coupling mechanism is a critical parameter in the non-contact energy transmission technology used in rotary steering systems. To design a high-efficiency, high-performance magnetic coupling mechanism, this study examines the effects of movement, rotation, well deviation, and the number of magnetic cores on the coupling coefficient of the primary magnetic coupling mechanism. This analysis is based on a three-dimensional finite element model that has been experimentally validated. The method can reduce the design time of rotary steering systems, minimize potential issues during engineering implementation, and enhance economic efficiency. Simulation results show that the movement of the magnetic coupling mechanism has the most significant impact on the coupling coefficient, which drops sharply from 92.7% to 19.7%. The rotation effect on the coupling coefficient is minimal, with the coefficient remaining above 92.2%. Additionally, increasing the number of magnetic cores leads to a higher coupling coefficient. The simulation model demonstrates good agreement with the measured results, providing a theoretical foundation for designing magnetic coupling mechanisms and offering valuable insights for developing rotary steering systems in downhole measurement instruments.
Investigating the transverse jitter in ultrashort electron beam generation with optical compression
Authors: Li J. , Xu X. , Guo Z. , Zhang J. , Zhang H. , He Z.
Published: December 2024

Optical compression scheme is a highly potential candidate
for the generation of ultrashort electron beam. This scheme utilizes
a tightly focused radially polarized laser to compress the electron
beam from the photocathode radio frequency (RF) gun. However, the
unavoidable relative transverse jitter between the electron beam and
the modulation laser leads to a performance degradation of the
compressed pulse duration. To address this issue, we propose a
method for correcting this transverse jitter through a specific
design of optical system and an optimized decoupled solenoid. This
method concentrates on the transverse jitter caused by the pointing
instability of the laser. Its objective is to align both the
transverse jitter direction and magnitude of the modulation laser
with that of the electron beam. The simulation results demonstrate
that the deleterious impact of transverse jitter can be effectively
mitigated by this method, thereby ensuring the sustained generation
of high-quality ultrashort electron beams.
Nutrition-sensitive climate risk across food production systems
Authors: Tigchelaar Michelle , Selig Elizabeth R , Sarhadi Ali , Bruce Janaya , Allison Edward H , Battista Willow , Fanzo Jessica , Kleisner Kristin M , Mehrabi Zia , Naylor Rosamond L , Schmidhuber Josef , Thilsted Shakuntala H
Published: December 2024

Global nutrition targets remain unmet, as over half of preschool-aged children and two-thirds of non-pregnant women of reproductive age worldwide suffer from micronutrient deficiencies. Climate change poses a growing threat to global food and nutrition security, but existing climate risk assessments often overlook the critical roles of both terrestrial and aquatic nutrient-rich foods that are vital for dietary diversity and micronutrient supply. In this study, we introduce an innovative framework that integrates data on future climate extremes, nutrient supply dependencies, and diet-related climate vulnerability. Our comprehensive analysis assesses nutrition-sensitive climate risk to five essential micronutrients across production systems. By mid-century (2041–2060), we estimate that 75% of calcium, 30% of folate, 39% of iron, 68% of vitamin A, and 79% of vitamin B12 produced in primary food products will face frequent climate extremes (at least every other year) globally. Nearly fifty countries are projected to face high domestic climate risk for two or more micronutrients during this period, with ten countries facing high risk across all five. We outline distinct climate risk profiles to offer data-driven entry points into strategies for bolstering the resilience of micronutrient supply chains and advancing progress toward global nutrient targets in the face of a changing climate.
Corrigendum: Wave function collapse equation maintains conservation laws with no new constants (2023 J. Phys. A: Math. Theor. 56 355303)
Authors: Gillis Edward J
Published: December 2024

Gillis (2023 J. Phys. A: Math. Theor.
56 355303) proposed a modification of the Schrödinger equation with additional stochastic terms that would result in wave function collapse in accord with the Born probability rule. It was based on the hypothesis that collapse is induced by the entangling interactions that generate correlations between physical systems. It differed from earlier stochastic collapse proposals in that it was completely consistent with conservation laws and did not require the introduction of any new, ad hoc physical constants. In particular, it eliminated the need for a new constant determining the rate at which collapse proceeds by defining variable parameters tied to the rate of variation of the potential energy characterizing the interaction. Some technical problems with that definition were later pointed out to the author. Specifically, the definition used a time derivative in the numerator of the rate parameters, but time derivatives are not well defined in stochastic differential equations. The denominator in the rate parameter was defined as the expectation value of the maximum of the absolute value of the interaction potential energy, but the expressions used were not sufficient to accurately project this value. Both of these problems are corrected in this note. Because the specific definition of the new parameters was given in the appendix to the original paper, that appendix should be replaced as indicated in the body of this note. The main argument of the paper is not affected by these technical changes.
Influence of fluid properties and model parameters with regard to stratified gas-liquid gap flows
Authors: Burchardt L , Vorspohl J , Sabozin F , Meinke M , Schröder W , Brümmer A
Published: December 2024

In rotary positive displacement machines - like twin-screw compressors - clearance flows have a big impact on the quality of the energy conversion. To partially seal the gap connections and thereby reduce internal losses, an auxiliary fluid, e.g. oil, is often injected into these machines. If a chamber model method is used to simulate the thermodynamic operating behavior of such a wet-running twin-screw machine, two-phase mass flow rates through the gaps must be calculated as accurately as possible in order to achieve a high simulation accuracy. This paper presents an extended model for simulating such two-phase gap flows. The model allows the simulation of a gap flow, taking into account the possible outgassing of a gas (e.g. refrigerant) from a liquid phase (e.g. oil) along the gap. The model is used to analyse the influence of various fluid properties (e.g. solubility, density, viscosity) or boundary conditions (e.g. pressure ratio, quality at the inlet of the gap) in relation to the simulated gap mass flow rate.
On Rotor Profling of Internally Geared Screw Machines
Authors: Lacevic H , Kovacevic A , Stosic N , Read M
Published: December 2024

The internally geared screw machine represents a novel type of positive displacement compressor which consists of an inner and outer rotor. Both rotors rotate in the same direction but are each centered on offset parallel axes. The rotor profiles are designed to create multiple continuous contact points between the rotors, forming several separate working chambers whose volumes vary from minimum to maximum and back to minimum during a single rotation of the outer rotor. For a gas or two-phase working fluid, adjusting the discharge port geometry allows internal compression to occur before discharge. Previous research has focused on using the well-known rotor profling method, which employs a circular pin to generate the inner and outer rotor profiles. Although the rack method for rotor profile generation has been described and investigated for conventional screw machine rotor profiles, it has never been applied to internally geared screw machine profile generation. This paper provides an initial description and application of the rack method for generating internally geared screw machine profiles. Potential benefits of using the rack method compared to conventional methods for rotor profile generation in internally geared machines are discussed. Additionally, the limitations of using the rack method for internal gearing are presented and illustrated through various examples and applications.
OilMixProp 1.0: Package for Thermophysical Properties of Oils, Common Fluids, and Their Mixtures
Authors: Yang X , Richter M
Published: December 2024

This work presents the first version of OilMixProp (short for oil mixture properties), which could be the first software package capable of calculating all the core thermophysical properties of fluids involving user-defined oils. Properties needed in thermodynamic cycle analysis are all included: density, phase equilibria, heat capacity, entropy, enthalpy, speed of sound, viscosity, and thermal conductivity. Approximately 632 pure fluids are available, and users can define their oil by determining its fluid constants using embedded fitting tools. Analogous to refpropm (Matlab interface of REFPROP 10.0), a function OilPropm is developed as the only interface for calculating thermophysical properties. Various input combinations (e.g., temperature and pressure, pressure and enthalpy, temperature and vapor fraction, etc.) are available to cater to the needs of thermodynamic cycle analysis. Sophisticated outputs are designed to deliver either complete information (phases and properties in each phase) or selected information about a fluid at the given condition. The package is written in Matlab and will be converted to other languages (e.g., C++) in the future.
One-dimensional investigations of the periodic liquid-injection in twin-screw compressors
Authors: Heselmann M , Monden T , Brümmer A
Published: December 2024

The injection of liquid fluid (mostly oil) in twin-screw machines brings several advantages like sealing the gaps, at least partially, and absorbs some of the compression heat. To predict the machine behavior, it is essential to consider the injection process, because it determines the amount of liquid within the working chambers. This in turn determine the absorption of compression heat, the degree of sealing the gaps and the hydraulic losses. Therefore, in this study the transient liquid injection is investigated using a one-dimensional method of characteristics within the injection nozzle. The theoretical results are compared with the actual liquid mass flow rate of an oil-injected twin-screw compressor.
A Bayesian-interference approach to quantify degradation parameters in a water-cooled variable speed screw compressor chiller
Authors: Hoess A J , Ma J , Groll E A , Braun J E , Ziviani D
Published: December 2024

Variable-speed screw chillers can provide effective capacity modulations in commercial buildings to reduce energy consumption, match the load requirements, and contribute to lower equivalent carbon emissions. However, variable-speed operation can also yield to degradation phenomena inside the compressor. Assessing the real-time health status of chillers and detecting anomalies are important aspects to ensure long-term operation and improve reliability. To this end, an automated accelerated life test (ALT) procedure was developed and applied to a 513 kW (145.9 RT) water-cooled variable-speed screw chiller in a laboratory test facility to experimental assess performance degradation over time. After every 1,000 operating hours of ALT, steady-state performance tests at 30%, 50%, 75% and 100% load were conducted according to AHRI Standard 550/590. Additional operating conditions were included while conducting the tests to provide a more complete assessment of the degradation trends compared to the initially measured baseline. The experimental data set was then used to quantify the performance degradation based on the impact on the screw compressor operation. A Bayesian-inference identification approach has been developed to identify changes of sensitive parameters that statistically provide evidence for the likelihood of a performance degradation of the compressor. The information was used to implement the parameters in a dynamic model which was used to perform studies to predict the degradations of a chiller. The outcomes of this study help to improve the maintenance schedule of a compressor and even the whole chiller so that the system can be operated more economically and unplanned downtime can be minimized.
MoS2 Coatings in unsynchronized, dry-running Screw Compressors: Experimental Insights on Operational Efficiency and Durability
Authors: Geissendorf M , Aurich D , Spraffke B , Lopes Dias N F , Tillman W , Nicolai S , Debus J , Brümmer A
Published: December 2024

The discourse on unsynchronized, oil-free screw compressors versus their conventional, oil-lubricated counterparts encapsulates a pivotal shift towards more effi-cient and environmentally friendly industrial machinery. By forgoing gears and lubricants, these innovative compressors streamline manufacturing and assembly, while also eliminating the risk of lubricant contamination in the process gas. In this configuration, the torque generated on the gate rotor by the gas pressure is directly conveyed to the main rotor through the interfacing surfaces of the rotors. In the development of compressor technology, a significant improvement is the application of a molybdenum disulfide (MoS2) coating on the primary rotor. This application utilizes the properties of molybdenum disulfide, which is effective in reducing friction and wear under various operational conditions. By applying this coating, there is an anticipated increase in the wear resistance of the rotor, effectively reducing frictional losses during its operation. This reduction in friction is expected to improve the mechanical efficiency of the compressor and extend its operational lifespan. The investigation of contact interactions utilizes a custom-designed test rig, through which effective parameters are analyzed to facilitate conclusions regarding losses and the durability of the coating. Additionally, the geometry within the contact area is tactilely measured, enabling the quantitative determination of wear. Various layer thicknesses, surface roughness levels, and loads are examined in this context.
Test rig setup for particle wear analysis in screw pumps
Authors: Moor P , Kuhr M , Pelz P
Published: December 2024

For many applications multi-screw pumps can be operated with minimal wear rates, thus offering long service life. Pump manufacturers are however met with increasing demand for pumps in applications with particle-laden fluids, which often lead to high wear rates. Thus, the need for design
guidelines and models for the estimation of the life expectancy arises. The scientific literature does not offer such models or published systematic studies. In this work the authors present a test rig setup for the systematic analysis of wear in operation with particle-laden fluids in multi-screw pumps. The setup is designed with repeatability of the test environment and reliability aspects in mind and draws inspiration from food and chemical processing industries.
Investigations to reduce rarefied gap flows within positive displacement vacuum pumps by utilising surface structures
Authors: Brock S , Pleskun H , Polus G , Saelzer J , Biermann D , Brümmer A
Published: December 2024

The ultimate pressure and efficiency of positive displacement vacuum pumps is limited by the backflow through the gaps within the machines. These gap flows are typically reduced by decreasing the gap height, which is limited for reasons of operational safety. Therefore, this study concentrates on the reduction of rarefied gap flows by means of suitable surface structures whose dimensions are small compared to the gap height without simultaneously reducing the minimum gap height. For this purpose, a method is presented to efficiently calculate the impact of the surface structure on these gap flows. Based on this method, design parameters for the choice of a suitable surface structure are discussed. Furthermore, a possible transfer for the application on the rotors is shown including a proposal for the machining process.