bluuebunny/crossref_metadata_2025 huggingface dataset:
The Ischemic Tolerance up to Four Hours of Free Jejunum Flap: A Retrospective Cohort Study
Authors: Kagaya Yu , Takanashi Ryo , Arikawa Masaki , Kageyama Daisuke , Higashino Takuya , Akazawa Satoshi
Published: January 2024

Background While free jejunum transfer (FJT) following total pharyngo-laryngo-esophagectomy (TPLE) is a reliable reconstruction technique, the jejunum flap is viewed as more susceptible to ischemia than a standard free flap. Animal studies have indicated that the jejunum can tolerate ischemia for as little as 2 to 3 hours. Clinical studies also reported increased complications after the FJT with more than 3 hours of ischemia. Traditionally, our institution has carried out FJT with an initial intestinal anastomosis, followed by a vascular anastomosis, which often results in extended jejunal ischemia time. In this study, we retrospectively examined the actual tolerance of the jejunum to ischemia, considering perioperative complications and postoperative dysphagia.

Methods We retrospectively studied 402 consecutive cases involving TPLE + FJT. Patients were divided into five groups based on jejunum ischemia time (∼119 minutes, 120∼149 minutes, 150∼179 minutes, 180∼209 minutes, 210 minutes∼), with each variable and result item compared between the groups. Univariate and multivariate analyses were conducted to identify independent factors influencing the four results: three perioperative complications (pedicle thrombosis, anastomotic leak, surgical site infection) and dysphagia at 6 months postoperatively.

Results The mean jejunal ischemia time was 164.6 ± 28.4 (90–259) minutes. When comparing groups divided by jejunal ischemia time, we found no significant differences in overall outcomes or complications. Our multivariate analyses indicated that jejunal ischemia time did not impact the three perioperative complications and postoperative dysphagia.

Conclusion In TPLE + FJT, a jejunal ischemia time of up to 4 hours had no effect on perioperative complications or postoperative dysphagia. The TPLE + FJT technique, involving a jejunal anastomosis first followed by vascular anastomosis, benefits from an easier jejunal anastomosis but suffers from a longer jejunal ischemia time. However, we found that ischemia time does not pose significant problems, although we have not evaluated the effects of jejunal ischemia extending beyond 4 hours.
Synthesis of C-Glucoside Analogues of Naturally Occurring Phenyl­ethanoid O-Glucosides
Authors: Aidhen Indrapal S. , Subramanyam Amudala , Sumit Sumit
Published: January 2024

Structural modifications of natural products has been a highly effective approach in the search for new leads with improved biological activity, aqueous solubility, and stability. Phenylethanoid glycosides (PEGs), as natural compounds, have attracted great attention due to their promising biological activities. These activities include neuroprotection, antioxidant, immunoregulation, anti-inflammatory, and analgesic effects, as well as antitumor, antiviral, and hepatoprotective abilities. Three potent PEGs, acteoside, echinacoside, and salidroside, are gaining renewed interest in this class of compounds. However, being O-glycosides, PEGs have low bioavailability due to factors such as poor intestinal permeability and low hydrolytic stability. The promising pharmacological properties and the limitations have inspired us to synthesize C-analogues that are expected to be hydrolytically stable.
Blow-Out Fracture of Orbit (Reconstructed with Stent Campo)
Authors: Lamba P. A. , Gupta A. K. , Shukla K. N.
Published: January 2024

A case of blow-out fracture of the orbit with herniation of the globe into the maxi-Hary antrum is presented. The floor was reconstructed using Stent campo with satisfactory repair and without any undue reaction to the compound. The literature of blow-out fractures is briefly reviewed. The use of Stent campo for repair of floor ol orbit is recommended as an emergency or temporary measure.
Theoretical modeling of organizational reflex in human resource management from the perspective of organizational biological approach
Authors: Papsiene Palmira
Published: January 2024

This article presents a framework that informs about routine and creative decision-making and management practices within an organization. The primary focus of the study is on the preparedness of human resources within the organization to effectively respond to information from the global environment and ensure optimal decision-making. Analysis of human resource management discourse, a review of biological organization theory, and a detailed examination of reflex arc theory using elements of human body analogy such as neurons, allowed us to model a system that examines the basis of decision-making of information coming from the global environment in an organization, and the conducted research allowed to discover how to improve organizational abilities to respond to external stimuli. Theoretical modeling techniques revealed connections between the organization and various systems, and computer simulation allowed to examine these connections in different situations using Spyder (Python 3.8 environment based on SciPy, NumPy, etc.), with all the necessary functions to perform calculations and visualize the results. In order to gain a deeper understanding of decision-making in the organization, a model has been developed that is able to effectively make a decision from the perspective of the organization’s biological approach. A computer simulation conducted in the course of the study indicated: (1) that according to the interests of the organization the model selected (20%) of information of interest, from which, according to the ability of the created model, (95%) was directed to form a routine response and (5%) was directed to a creative response; (2) the time efficiency of the routine response may be more effective than that of the creative response from (63.6%) to (90.7%); (3) the efficiency of the realistic scenario of the model’s performance is inferior (about 21%) than that of the optimistic scenario, but more effective (about 17%) than that of the pessimistic scenario, this means that the realistic scenario works better than predicted in the pessimistic scenario, making it positive for the suitability of the model. These findings provide valuable insights into an organization’s ability to respond quickly and make decisions in a competitive environment, which may have practical implications for organization management and strategies to improve the ability to respond to external factors.
Worldviews of hearing health for Pacific peoples in Aotearoa New Zealand: a mixed methods study
Authors: Holt Elizabeth A.-L. , Koro Latasi , Langridge Fiona , Nosa Vili
Published: January 2024

Introduction Pacific peoples experience inequity in accessing hearing health care and are disproportionately exposed to the underlying determinants impacting ear and hearing health in Aotearoa New Zealand. Understanding community members’ worldviews, including perspectives, beliefs and values, is essential in developing appropriate and responsive hearing healthcare services to meet the needs of Pacific peoples. Aim The purpose of this paper is to understand the worldviews, knowledge and beliefs held by Pacific peoples regarding hearing health in Aotearoa New Zealand. Methods A mixed-methods approach was used. Twelve semi-structured face-to-face interviews were conducted with Pacific community members. Twenty-five participants completed an online questionnaire. A simultaneous, integrated mixed-methods approach was used to analyse the qualitative and quantitative data. Results Five main themes were established, which were: The Meaning of Hearing; Causes of hearing loss; Consequences of hearing loss and Disability; and Improving health care for ear disease and hearing loss. Discussion Pacific peoples value hearing health to communicate and connect with their families and communities. Participants highlighted the importance of hearing health across the life course. Although the study findings revealed there is potentially less stigma and shame around hearing loss in New Zealand, denial and fatalistic attitudes towards hearing loss may delay some people from seeking healthcare services. Participants expressed key ways in which the health system can be more responsive to the hearing health needs of Pacific peoples in Aotearoa New Zealand.
Update of the BIPM comparison BIPM.RI(II)-K1.Tb-161 of activity measurements of the radionuclide 161Tb to include the 2022 result of the NPL (United Kingdom)
Authors: Michotte Carine , Courte Sammy , Coulon Romain , Nonis Manuel , Collins S , Shearman R , Kolmogorova S , Keightley J , Pearce A , Ramirez N , Bendall E , Mohamud H , Mewburn-Crook J
Published: January 2024

Main text

Since 2019, 2 laboratories have submitted 2 samples of 161Tb to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM), with comparison identifier BIPM.RI(II)-K1.Tb-161. Recently, the NPL (United Kingdom) participated in the comparison and the key comparison reference value (KCRV) has been evaluated for the first time. The degrees of equivalence between each equivalent activity measured in the SIR and the updated KCRV have been calculated and the results are given in the form of a table. A graphical representation is also given.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Addendum on ‘Entropy uniqueness determines temperature’
Authors: Saslow Wayne M
Published: January 2024

We discuss how to apply the proposed minimum entropy deviation criterion when there is a measurable property P for which there is a statistical mechanical theory as a function of temperature T. When P

m
can be measured more accurately than heat flow dQ, then P(T) can be inverted to obtain accurate values for T(P); following this, the minimum rms entropy deviation criterion using T(P) then can be used to refine measurements of dQ. When dQ is more accurately measurable than P, then measurement of dQ and the minimum rms entropy deviation criterion provides a means to obtain T, which can then be used to obtain more accurate values of P(T).
Mechanisms of charge-induced surface discharge under positive impulse voltages
Authors: Li Yixuan , Zhang Boya , Zhou Xinmiao , Ji Kai , Tao Haifei , Li Kaixuan , Li Xingwen
Published: January 2024

Charge-induced surface flashover is a critical factor leading to insulation failures in high-voltage direct current gas-insulated equipment, and the underlying mechanisms are still unclear. In the present study, the typical surface charge distributions are first summarized. Then, the impact of charge polarity and position on surface discharge characteristics in ambient air is studied, and the surface charge dynamics during multiple discharge processes are also focused. Comparative studies of the charge-induced surface discharge are conducted in SF6, and the effect of the gas atmosphere is discussed. The results indicate that the repulsive effect of deposited positive charges significantly inhibits the positive streamer development by reducing the electric field. The acceleration of negative charges on positive streamer propagation is the result of two competitive mechanisms: the enhancement of the electric field and the neutralization with positive charges in the streamer channel. In the multiple discharge process, positive streamers develop along the gap of positive streamer channels from the previous discharge. When the last discharge is intense enough, back discharges may occur along the pattern of the deposited positive channels from the previous discharge. The effects of the deposited charges on the surface discharge process are consistent in air and SF6. These findings will be advantages in improving the insulation reliability of gas-insulated equipment.
Ag nanoparticle decorated β-Ga2O3 nanowires on Si substrates: advancing photodetector technology
Authors: Romeo Meitei Shagolsem , Devi Leimapokpam Sophia , Singh Naorem Khelchand
Published: January 2024

In this study, we present the fabrication of Ag nanoparticle (NP) decorated β-Ga2O3 nanowire (NW) on a Si-substrate, with a focus on their application in photodetection. The resulting Ag NP decorated β-Ga2O3 NW exhibited a polycrystalline morphology characterized by well-aligned rows of vertically oriented structures. The mean size of the crystallites was revealed to be approximately 15.94 nm. The fabrication of Ag NP decorated β-Ga2O3 NW displayed uniformity, with an average length of approximately ∼180 nm. The UV-Vis absorption spectroscopy analysis yielded an approximate optical bandgap value of 4.74 eV. Notably, the fabricated photodetector exhibited excellent performance characteristics. This was highlighted by the minimal dark current of −3.2 nA at a bias voltage of −1 V, accompanied by an I
L/I
D ratio exceeding 50. Moreover, the photodetector demonstrated rapid rise and fall times of 0.023 s and 0.021 s, respectively. The remarkable aspect lies in the simultaneous attainment of minimum dark current and swift response times. The Ag NP-decorated β-Ga2O3 NW photodetector exhibited consistent and reproducible behavior, suggesting its potential for realistic use in ultraviolet photodetection.
Accurate and rapid predictions with explainable graph neural networks for small high-fidelity bandgap datasets
Authors: Xiao Jianping , Yang Li , Wang Shuqun
Published: January 2024

Accurate and rapid bandgap prediction is a fundamental task in materials science. We propose graph neural networks with transfer learning to overcome the scarcity of training data for high-fidelity bandgap predictions. We also add a perturbation-based component to our framework to improve explainability. The experimental results show that a framework consisting of graph-level pre-training and standard fine-tuning achieves superior performance on all high-fidelity bandgap prediction tasks and training-set sizes. Furthermore, the framework provides a reliable explanation that considers node features together with the graph structure. We also used the framework to screen 105 potential photovoltaic absorber materials.
Self-healing flexible strain sensor fabricated through 3D printing template sacrifice for motion monitoring with enhanced healing and mechanical performance
Authors: Yan Hui , Liu Shuofu , Wen Nan , Yin Jiyuan , Jiang Hongyuan
Published: January 2024

With the advancements in flexible materials and information technology, flexible sensors are becoming increasingly pervasive in various aspects of life and production. They hold immense potential for further development in areas such as motion detection, electronic skin, soft robots, and wearable devices. Aminopropyl-terminated polydimethylsiloxane (PDMS) was used as the raw material, while a diisocyanate reagent served as the cross-linking agent for the polymerization reaction, which involved the introduction of ureido groups, containing N–H and C=O bonds, into the long siloxane chain. The dynamic hydrogen bonding between the clusters completes the self-healing of the material. Using 1-[3-(trimethoxysilyl)propyl]urea as a grafting agent, the urea groups are introduced into graphene oxide and carbon nanotubes (CNTs) as conductive fillers. Subsequently, a flexible polymer is used as the substrate to prepare conductive flexible self-healing composites. By controlling the amount of conductive fillers, flexible strain materials with varying sensitivities are obtained. Design the structure of the flexible strain sensor using three-dimensional (3D) modeling software with deposition printing method.
Light and voltage dual-modulated volatile resistive switching in single ZnO nanowires
Authors: Yang Feng , Zhang Yongle , Feng Xue , Guo Junmeng , Cheng Gang , Du Zuliang
Published: January 2024

A single ZnO nanowire device with volatile resistive switching behavior has been prepared. Different from traditional resistive switching devices, such ZnO nanowire devices do not exhibit resistive switching behaviors under a single bias voltage, and appear resistive switching behavior under the combined action of light stimuli and bias voltage. Through the demonstration of the time-dependent hysteresis curve and atmosphere-dependent hysteresis loop of the resistive switching devices, it is believed that under the resistive switching process, ultraviolet illumination can increase the carrier concentration and modulate the barrier depletion structure, and external bias voltage can ionize the surface state. They work together to modulate the switching process of the devices. Such light stimuli and bias voltage dual-modulated resistive switching device enables optical control and may thus be considered for sensory applications or optically tunable memories.
Strain engineering of Zeeman and Rashba effects in transition metal dichalcogenide nanotubes and their Janus variants: an ab initio study
Authors: Bhardwaj Arpit , Suryanarayana Phanish
Published: January 2024

We study the influence of mechanical deformations on the Zeeman and Rashba effects in transition metal dichalcogenide nanotubes and their Janus variants from first principles. In particular, we perform symmetry-adapted density functional theory simulations with spin–orbit coupling to determine the variation in the electronic band structure splittings with axial and torsional deformations. We find significant effects in molybdenum and tungsten nanotubes, for which the Zeeman splitting decreases with increase in strain, going to zero for large enough tensile/shear strains, while the Rashba splitting coefficient increases linearly with shear strain, while being zero for all tensile strains, a consequence of the inversion symmetry remaining unbroken. In addition, the Zeeman splitting is relatively unaffected by nanotube diameter, whereas the Rashba coefficient decreases with increase in diameter. Overall, mechanical deformations represent a powerful tool for spintronics in nanotubes.
Detecting central apneas using multichannel signals in premature infants
Authors: Varisco Gabriele , Peng Zheng , Kommers Deedee , Cottaar Eduardus J E , Andriessen Peter , Long Xi , van Pul Carola
Published: January 2024

Objective. Monitoring of apnea of prematurity, performed in neonatal intensive care units by detecting central apneas (CAs) in the respiratory traces, is characterized by a high number of false alarms. A two-step approach consisting of a threshold-based apneic event detection algorithm followed by a machine learning model was recently presented in literature aiming to improve CA detection. However, since this is characterized by high complexity and low precision, we developed a new direct approach that only consists of a detection model based on machine learning directly working with multichannel signals. Approach. The dataset used in this study consisted of 48 h of ECG, chest impedance and peripheral oxygen saturation extracted from 10 premature infants. CAs were labeled by two clinical experts. 47 features were extracted from time series using 30 s moving windows with an overlap of 5 s and evaluated in sets of 4 consecutive moving windows, in a similar way to what was indicated for the two-step approach. An undersampling method was used to reduce imbalance in the training set while aiming at increasing precision. A detection model using logistic regression with elastic net penalty and leave-one-patient-out cross-validation was then tested on the full dataset. Main results. This detection model returned a mean area under the receiver operating characteristic curve value equal to 0.86 and, after the selection of a FPR equal to 0.1 and the use of smoothing, an increased precision (0.50 versus 0.42) at the expense of a decrease in recall (0.70 versus 0.78) compared to the two-step approach around suspected apneic events. Significance. The new direct approach guaranteed correct detections for more than 81% of CAs with length L ≥ 20 s, which are considered among the most threatening apneic events for premature infants. These results require additional verifications using more extensive datasets but could lead to promising applications in clinical practice.
Evidence of dynamical dark energy in a non-flat universe: current and future observations
Authors: Rezaei Mehdi , Pan Supriya , Yang Weiqiang , Mota David F.
Published: January 2024

We investigate the dark energy phenomenology in an extended parameter space where we allow the curvature density of our universe as a free-to-vary parameter. The inclusion of the curvature density parameter is motivated from the recently released observational evidences indicating the closed universe model at many standard deviations. Here we assume that the dark energy equation-of-state follows the PADE approximation, a generalized parametrization that may recover a variety of existing dark energy models. Considering three distinct PADE parametrizations, labeled as PADE-I, SPADE-I and PADE-II, we first constrain the cosmological scenarios driven by them using the joint analyses of a series of recently available cosmological probes, namely, Pantheon sample of Supernovae Type Ia, baryon acoustic oscillations, big bang nucleosynthesis, Hubble parameter measurements from cosmic chronometers, cosmic microwave background distance priors from Planck 2018 and then we include the future Gravitational Waves standard sirens (GWSS) data from the Einstein telescope with the combined analyses of these current cosmological probes. We find that the current cosmological probes indicate a very strong evidence of a dynamical dark energy at more than 99% C.L. in both PADE-I, and PADE-II, but no significant evidence for the non-flat universe is found in any of these parametrizations. Interestingly, when the future GWSS data from the Einstein telescope are included with the standard cosmological probes an evidence of a non-flat universe is found in all three parametrizations together with a very strong preference of a dynamical dark energy at more than 99% C.L. in both PADE-I, and PADE-II. Although from the information criteria analysis, namely, AIC, BIC, DIC, the non-flat Λ-Cold Dark Matter model remains the best choice, however, in the light of DIC, PADE parametrizations are still appealing.
Numerical computation of quasinormal modes in the first-order approach to black hole perturbations in modified gravity
Authors: Roussille Hugo , Langlois David , Noui Karim
Published: January 2024

We present a novel approach to the numerical computation of quasi-normal modes, based on the first-order (in radial derivative) formulation of the equations of motion and using a matrix version of the continued fraction method. This numerical method is particularly suited to the study of static black holes in modified gravity, where the traditional second-order, Schrödinger-like, form of the equations of motion is not always available. Our approach relies on the knowledge of the asymptotic behaviours of the perturbations near the black hole horizon and at spatial infinity, which can be obtained via the systematic algorithm that we have proposed recently.
In this work, we first present our method for the perturbations of a Schwarzschild black hole and show that we recover the well-know frequencies of the QNMs to a very high precision. We then apply our method to
the axial perturbations of an exact black hole solution in a particular scalar-tensor theory of gravity. We also cross-check the obtained QNM frequencies with other numerical methods.
View of thermodynamic phase transition of the charged Gauss–Bonnet AdS black hole via the shadow
Authors: He 何 Ke-Jian 柯腱 , Guo 郭 Sen 森 , Luo 罗 Zhi 智 , Li 李 Guo-Ping 国平
Published: January 2024

We examine thermodynamic phase transition (PT) of the charged Gauss–Bonnet AdS black hole (BH) by utilizing the shadow radius. In this system, we rescale the corresponding Gauss–Bonnet coefficient α by a factor of 1/(D–4), and ensure that α is positive to avoid any singularity problems. The equation derived for the shadow radius indicates that it increases as the event horizon radius increases, making it an independent variable for determining BH temperature. By investigating the PT curve in relation to shadows, we can observe that the shadow radius can be used as an alternative to the event horizon radius in explaining the phenomenon of BH PT. Furthermore, the results indicate that an increase in the parameter α corresponds to a decrease in the temperature of the BH. By utilizing the relationship between the temperature and the shadow radius, it is possible to obtain the thermal profile of the Gauss–Bonnet AdS BH. It is evident that there is an N-type variation in temperature for pressures P < P
c. Additionally, as the parameter α increases, the region covered by shadow expands while the temperature decreases. The utilization of BH shadows as a probe holds immense significance in gaining a deeper understanding of BH thermodynamic behavior.
REPORT-SCS: minimum reporting standards for spinal cord stimulation studies in spinal cord injury
Authors: Malik Raza N , Samejima Soshi , Shackleton Claire , Miller Tiev , Pedrocchi Alessandra Laura Giulia , Rabchevsky Alexander G , Moritz Chet T , Darrow David , Field-Fote Edelle C , Guanziroli Eleonora , Ambrosini Emilia , Molteni Franco , Gad Parag , Mushahwar Vivian K , Sachdeva Rahul , Krassioukov Andrei V
Published: January 2024

Objective. Electrical spinal cord stimulation (SCS) has emerged as a promising therapy for recovery of motor and autonomic dysfunctions following spinal cord injury (SCI). Despite the rise in studies using SCS for SCI complications, there are no standard guidelines for reporting SCS parameters in research publications, making it challenging to compare, interpret or reproduce reported effects across experimental studies. Approach. To develop guidelines for minimum reporting standards for SCS parameters in pre-clinical and clinical SCI research, we gathered an international panel of expert clinicians and scientists. Using a Delphi approach, we developed guideline items and surveyed the panel on their level of agreement for each item. Main results. There was strong agreement on 26 of the 29 items identified for establishing minimum reporting standards for SCS studies. The guidelines encompass three major SCS categories: hardware, configuration and current parameters, and the intervention. Significance. Standardized reporting of stimulation parameters will ensure that SCS studies can be easily analyzed, replicated, and interpreted by the scientific community, thereby expanding the SCS knowledge base and fostering transparency in reporting.
Recovery of Scandium, Nickel and Cobalt from Hydrometallurgical Waste of Laterite
Authors: Wei J M , Wang W W , Ma M S , Sun N L , Qin B , Li M C , Du G S , Lv D , Liu G , Peng J H , Lu Y D , Liu C
Published: January 2024

Recovery of new-energy critical metals including scandium, nickel and cobalt as well as copper and zinc from a neutralization residue produced in laterite hydrometallurgical process has been studied. Effect of leaching parameters such as acid consumption, solution pH and temperature has been investigated. It was found that scandium, nickel, cobalt and copper could be recovered at high efficiencies from the residues by selective leaching using sulphuric acid solutions under ambient conditions, while the co-leaching of impurities including iron, aluminium and silicon was low under the optimal conditions. The nickel, cobalt, copper and zinc in the leaching solution could be further concentrated into mixed sulphides and separated from impurities by sulphide precipitation.
A strain energy density field method to predict the life of metallic notched components under multiaxial fatigue loading
Authors: Luo Peng , Yu Ming , Wen Changlong
Published: January 2024

A method based on strain energy density field (SEDF) has been proposed to predict the angle of fatigue critical points and multi-axial life of the notched parts under multi-axial cyclic loading. The point bearing the maximum strain energy density was taken as the fatigue crack initiation point (fatigue critical point). The influence of stress-strain gradient around the notches were considered via combining SEDF and the critical distance theory (TCD) to calculate the multi-axial notch life. The predictive results indicate that the maximum deviation of the fatigue critical point (FCP) was 7.0°. The most of the predictive life was within the 3-time error band.
Detection methods and bearing failure characteristics analysis related to grinding burns
Authors: Hou Xue qin , Liu Yong bao , Liu Yu , Liu Chang kui , Zhang Zheng , huTao Chun , Wei Xun kai
Published: January 2024

Grinding burn is one of the bearing failure causes for components. In order to quickly confirm that grinding burn is the cause of bearing failure, detection methods for the grinding burns and characteristics of bearing failure caused by grinding burns have been studied in this paper. The results show that cold acid pickling examination, microhardness test and Barkhausen noise analysis can be used in the detection of heavy grinding burns but have several disadvantages to hinder their application on the detection of slight grinding burns. A grinding burn detection procedure is recommended for the analysis of bearing failure induced by grinding burn. It has been found that the modes of bearing failure induced by grinding burns were contact fatigue spalling developed from the contact fatigue crack, the propagation mechanism of the contact fatigue crack was obtained. And the unique phenomenon of fracture or fragmentation with cracks distributed in the origin or surrounding the spalling pit of the grinding burn layer was also obtained. Based on the above results the future work on detection methods and influence on bearing failure mechanism and life of grinding burn are proposed.
Microstructure and mechanical properties of a first-generation single crystal superalloy CMSX-6
Authors: Zheng S , Zhang J , Liu Y F , Xu J W , Zhang X N , Cui L L
Published: January 2024

CMSX-6 alloy is a first generation of single crystal high temperature alloy and has been widely applied for the aeroengine and gas turbine blades. In the present study, the microstructure, tensile properties, stress rupture properties and fracture properties of the as-cast and heat-treated CMSX-6 alloy were investigated. The experimental results show that under the heat-treated condition the γ′ phase was about 0.5 μm, the volume fraction was about 66%, and the residual eutectic phase volume was 2%~5%. The tensile and stress rupture properties was similar that of the first generation of single crystal alloys, DD3 and DD407 developed by Beijing Institute of Aeronautical Materials and General Institute of Iron and Steel Research, China. And the results also indicate that CMSX-6 alloy has good fracture properties, oxidation resistance properties and corrosion resistance properties, and therefore CMSX-6 alloy has very good application prospect for the aeroengine and gas turbine blades materials.
Passivation and Corrosion Behavior of Modified S13Cr Stainless Steel in Ultra-high Temperature Geothermal Fluid
Authors: Chen Y F , Cheng L Y , Zhu Y , Sun C , Lin X Q , Sun J B
Published: January 2024

This research aims to investigate the passivation and corrosion behaviour of modified S13Cr stainless steel (SS) in ultra-high temperature geothermal fluids. In this study, S13Cr SS before and after modified were both immersed in a simulated geothermal fluid environment with a temperature of 210°C and CO2 pressure of 3 MPa for 120 h. The results show that the modified S13Cr SS had smaller grain size and lower reverse austenite content, and exhibited higher transpassive potential and lower passive current density in the ultra-high temperature environment. After 120 h of immersion, the passivation film of the modified 13Cr SS was completely dissolved, and a corrosion product film mainly composed of FeCO3 and FeCr2O4 formed with localized corrosion occurring. Moreover, a Ni-rich barrier layer formed at the interface between the inner layer of the product film and the substrate, which hindered the penetration of the corrosive medium. Additionally, the residual MoO2 in the product film played a stabilizing role. Overall, the corrosion resistance of the modified S13Cr SS in ultra-high temperature geothermal fluids is improved.
Microstructures Evolution of a Second Generation Single Crystal Superalloy after Long Term Aging at 980°C
Authors: Yipeng Zhang , Jinxia Song , Gang Li , Dinggang Wang , Xinguang Guan , Qinjia Wang
Published: January 2024

The microstructure evolution of the second-generation single crystal superalloy DD412 aged at 980°C for 1000 h were investigated. The results show that needle-shaped topologically close packed (TCP) phases rich in Re and W were firstly found in the dendritic core region after aging at 980°C for 400h, while the size and amount of TCP phases increased gradually with aging time, which is due to the fact that high melt point elements Re and W segregated to the dendritic core region. With the increment of aging time, the size of γ′ phase increased and volume fraction of γ′ phase decreased. The γ′ phase in dendrite core and inter-dendrite region remained cuboidal basically, and the γ′ phase in second dendritic arm showed directional coarsening after aging for 800 h. The MC carbides in inter-dendritic region decomposed gradually and transformed to the M6C carbides partially during long term aging, while few fine blocky M6C carbides precipitated in dendritic core after aging for 400h. The different microstructure evolution in dendritic region is due to the dendrite segregation of alloying elements and elements diffusion during aging.
Influence of temperature on corrosion behavior of N80 Steel in multiple thermal fluid environment
Authors: Shi Shengkai , Feng Wenbin , Sun Chong , Lin Xueqiang , Sun Jianbo
Published: January 2024

During offshore oil production, O2 could be introduced into the multiple thermal fluid, and the temperature of the wellbore can reach up to 200°C, which may result severe corrosion of tubing. However, the corrosion mechanism of downhole pipes in such aggressive environment remains unclear in the high-temperature and high-pressure CO2-O2-H2O mixed environment. Herein, we investigated the corrosion behaviour of N80 steel with different temperatures in CO2-O2-H2O environment. The influence of temperature on composition and structure of the corrosion product film of N80 steel was characterized by scanning electron microscope, energy-dispersive spectroscopy and X-ray diffraction. The results show that the corrosion rates of N80 steel performed a downward trend with the increase of the temperature, but it increased slightly at 180°C. The corrosion rate of N80 steel was up to 1.6 mm/y at 60°C, owing to the damage to corrosion product film by O2 and reduced its protection at lower temperature. As the temperature increased, the formation of Fe3O4 enhanced the protection of the inner corrosion product film, thereby greatly reducing the corrosion rate. However, the product of (FeCa)CO3 in the corrosion film completely lost its protection at 180°C, and the corrosion rate increased slightly to 0.84 mm/y. With the temperature increased to 240°C the corrosion rate of N80 steel reduced to 0.24 mm/y on account of the formation of dense and complete Fe3O4.
Effect of aging treatment on the microstructure and properties of cold rolled Ti-10V-2Fe-3Al alloy
Authors: Qi Lichun , Zhang Yeqin , Zhang Mingjie , Huang Lijun , Huang Xu , Zhao Xinqing
Published: January 2024

As a typical metastable titanium alloy with high strength and toughness, Ti-10V-2Fe-3Al titanium alloy has found wide applications in aerospace industry to replace forging steel components for light weight, long service life and high reliability. In the present study the microstructure evolution and mechanical properties of cold rolled Ti-10V-2Fe-3Al alloy undergoing aging treatment were characterized by optical microscopy, X-ray diffraction, transmission electron microscopy and mechanical testing, in attempt to understand the relationship between the microstructural evolution and aging treatment temperature and time. It is revealed that the secondary α phase had a very short propagation time to nucleate, and holding 5 min could give rise to the transformation from β phase to secondary α phase when cold rolled alloy suffered from aging at 550°C. This could be attributed to the large amounts of dislocations and grain boundaries by cold deformation, which provide nucleation sites for α phase. Increasing aging time could accelerate the transformation from β phase to secondary α phase. With aging at 550°C for 30 min, a large amount of fine secondary α phase formed, offering a good combination of strength and ductility. With increasing aging time the coarsening secondary α phase led to a decrement of strength of the alloy.
Analysis and experimental study on the cause of fracture of a Transmission line’s Drainage connecting plate
Authors: Jiang Fei , Lv Yanting , Zhao Tongkun , Sun Hebin , Xie Jinpeng
Published: January 2024

The transmission line is exposed to the outdoors for a long time, and the operation environment is complex, which makes the line equipment prone to corrosion, wore and heat, etc. The fracture of the drainage plate of the tensioning wire is one of the problems that often occur in the operation of the transmission line. Based on the systematic analysis of the problem of the fracture of the drainage plate of a transmission line, the causes of the fracture of the drainage plate are obtained, and the corresponding rectification measures are proposed, which has an important reference for the design, construction, operation and maintenance of the subsequent transmission line.
Parallel Operation for 11 kV Ring System with Normally Open Point at Distribution Networks in AADC
Authors: AlAhmad Omar , AlDahmi Maha , Rayees Ahamed Mohamed
Published: January 2024

Currently, Al Ain Distribution Company (AADC) 11 kV distribution circuits are electrically split by Normal Open Points (NOP)s. NOPs can be closed for load restoration in case of planned or unplanned outages. Also, changing the NOP locations helps in load shifting to achieve network optimization between adjacently located 33/11 kV primary substations. This paper discusses a new operation mode in medium voltage distribution power network of AADC at Al Ain area in the United Arab Emirates by introducing closed loops of parallel 11 kV feeders from different busbars or substations. This operation mode is intended to end the continuous debate of optimal NOP locations in addition to expected reduction in the required time for load restoration in case of failures at distribution (11/0.4 kV) substations. A detailed case study is performed to explore the achieved benefits and enhancements on load balancing, voltage profile, and power factor in medium voltage networks. On the other hand, the impact on load flow, protection scheme, and loading violation are evaluated. Furthermore, the proposed model is in line with the regulations of the Department of Energy (DoE), regulatory body in Abu Dhabi Emirate, and should fully comply with Electricity Distribution Code (EDC) of Security of Supply Standards. Accordingly, while the current used operation mode is still valid, it is found that closed loops arrangement can be only allowed for rings from same 33/11 kV substations feeding from same source with considerable protection limitations. Moreover, it was concluded that closed loops from different 33/11 kV Substations will result in load flow problems.
Research on space temperature environmental performance and technology of aerospace RF cable assembly
Authors: Tong Lijun , Li Xiang , Zhao Ming , Xie Qian , Cai Libin , Wang Shuaibo
Published: January 2024

The aerospace RF cable assembly is an important component for the propagation of space communication signals, which can achieve impedance matching and energy transmission of microwave signal transmission paths. In addition to the requirements for a wide frequency range, low insertion loss, and low standing wave as required for conventional RF cable components, it must also possess high reliability, spatial temperature resistance, vacuum high-power transmission, and other spatial adaptability capabilities. This article primarily discusses the damage to the insulation materials of cable components under space-limit temperatures and its impact on the performance of the cable components. The problem of deterioration and even failure of the performance of aerospace RF cable components in high and low-temperature alternating environments in space has been addressed through the adoption of corresponding measures.
Rolling bearing fault diagnosis method based on SSA-mRVM
Authors: Zhu Xingtong , Huang Minchuan , Wang Aiguo
Published: January 2024

In order to accurately diagnose the faults of rolling bearings, in this paper, a fault diagnosis method is proposed based on multiclass relevance vector machines (mRVM) optimized by the sparrow search algorithm (SSA). Complete ensemble empirical mode decomposition (CEEMD) is applied to feature extraction of vibration signals. Optimizing the parameters of multiclass relevance vector machines involves the use of the sparrow search algorithm. The optimized multiclass relevance vector machines model is applied for fault diagnosis to obtain accurate diagnostic results.
Integrated design of lateral-directional control law and vertical tail load for civil aircraft
Authors: Liu Jun
Published: January 2024

According to new requirements of airworthiness regulation CS25.353, the advanced lateral-directional P-Beta control law design is studied in this paper. The LQR method based on the tracking command model is used to design the lateral-directional control law parameters. At the same time, the vertical tail load model of aircraft for yaw maneuver is introduced into the lateral-directional control law design model. The aim is to build the integrated design of control law and flight load. Finally, the simulation results show that the P-Beta control law can not only improve Dutch roll damping and coordination turn characteristics, but it can also reduce the yaw maneuver load by 18.5%. Thus, the structure weight of the aircraft’s vertical tail can be reduced.
Leakage performance of hybrid brush seals under high differential pressure conditions
Authors: Li Hao , Huo Weibin
Published: January 2024

A three-dimensional axial fluid-porous medium-flow field model was designed for the sealing properties of the hybrid brush seal (HBS) seal structure under complex operating conditions. Using a computational fluid dynamics model in view of non-Darcy porous media, the pressure and velocity distributions of the sealing medium in the flow path were simulated, and the flow characteristics of the hybrid brush seal were analysed to obtain the leakage of the hybrid seal structure. The results show the implication of pressure ratio (Rp) on the labyrinth brush seal leakage rate and pressure distribution. Compared with typical brush seal test results, as the inlet and outlet pressure ratio (Rp) increases, the more obvious the hybrid brush seal sealing effect is, when the pressure ratio is 3 bar, the spillage of the hybrid brush seal is reduced by about 39%.
Research on pipeline stress test method of civil aircraft hydraulic system
Authors: Ni Junfei , Qi Xiaoyan
Published: January 2024

The hydraulic system is an important component of the aircraft, whose performance status directly affects the aircraft’s flight safety, and aircraft hydraulic system piping is the main component of the hydraulic system. In the development process, civil aircraft must be tested and analyzed on the hydraulic system piping vibration and stress. This paper takes the hydraulic system pipeline of civil aircraft as the research object, carries out the research of pipeline stress test method, and provides the stress test method and reliable test data for verifying whether the design of the hydraulic system pipeline is reasonable.
Preliminary design of lunar high-resolution remote sensing micro-nano satellite
Authors: Wang Yusong , Zeng Chaoli , Zhong Xing , Hu Xin , Guan Junchang , Yu Xiaozhou
Published: January 2024

The development and utilization of lunar resources and the construction of lunar scientific research stations are important parts of China’s future lunar exploration plan. Aiming at the problems of China’s micro-nano satellites with low radiation resistance, lack of autonomous Earth-Moon transfer capability, and limited optical system volume and quality, a preliminary design scheme of a lunar remote sensing micro-nano satellite with autonomous Earth-Moon transfer capability is proposed. Using the analytical orbit average technology and transcription and collocation method to calculate the satellite’s Earth-Moon transfer orbit, the satellite can use the Hall thruster with large specific impulse and low thrust to realize the autonomous Earth-Moon transfer. The passive + active method is used to optimize the radiation resistance of the system, and the total radiation dose of some single machines can reach more than 25krad. A compact high-resolution multispectral camera is designed, and imaging simulation and verification are carried out. In the end, the satellite can achieve high-resolution imaging of the moon with a resolution of 0.2 m at an orbital height of 100 km to achieve the purpose of fine exploration of information such as lunar surface topography and geological structure.
Study on the performance of a novel 1DOF isolator with QZS characteristics
Authors: Wei Chunyu
Published: January 2024

A typical one-degree-of-freedom (1DOF) shock isolator that has quasi-zero stiffness (QZS) characteristics consists of two transversal springs and one portrait spring. The transversal springs can provide negative stiffness and the vertical spring is used as a load-bearing component. In this article, an improved 1DOF QZS shock isolator is obtained by utilizing the combination of lateral bars and springs. The displacement transmissibility under the harmonic excitation is obtained and the principle of minimum displacement transmissibility under the condition of system stability is proposed. Finally, numerical simulation is conducted, and the simulation results reflect that the proposed 1DOF QZS isolator significantly performs better than the previous one.
Experimental and numerical investigation of the propeller thrust reduction in bollard pull condition
Authors: Wen Xiao , Liu Zhenghao , Xu Changjian , Ding Ju
Published: January 2024

The polar ships are often in bollard pull condition, which is prone to induce propeller cavitation and cause thrust reduction, weakening the ship’s ice-breaking ability. Based on the model tests and numerical simulations, this paper aims to investigate the propeller thrust reduction in the bollard pull condition. Firstly, the test of a self-designed ice class propeller under different cavitation numbers is carried out. The thrust reduction phenomenon is successfully captured and the hydrodynamic characteristics are obtained. Subsequently, the simulation based on Star-CCM+ is performed. It is found that the propeller thrust decreases almost linearly after the cavitation number reaches a certain threshold. When the cavitation number is equal to 0.25, the thrust decreases to 38.1% of that in the open water condition. By analyzing the mechanism of thrust reduction, the main reason is recognized that the average pressure of the blade face decreases greatly due to the influence of the cavitation on the blade back.