bluuebunny/crossref_metadata_2025 huggingface dataset:
3D cine-magnetic resonance imaging using spatial and temporal implicit neural representation learning (STINR-MR)
Authors: Shao Hua-Chieh , Mengke Tielige , Deng Jie , Zhang You
Published: March 2024

Objective. 3D cine-magnetic resonance imaging (cine-MRI) can capture images of the human body volume with high spatial and temporal resolutions to study anatomical dynamics. However, the reconstruction of 3D cine-MRI is challenged by highly under-sampled k-space data in each dynamic (cine) frame, due to the slow speed of MR signal acquisition. We proposed a machine learning-based framework, spatial and temporal implicit neural representation learning (STINR-MR), for accurate 3D cine-MRI reconstruction from highly under-sampled data. Approach. STINR-MR used a joint reconstruction and deformable registration approach to achieve a high acceleration factor for cine volumetric imaging. It addressed the ill-posed spatiotemporal reconstruction problem by solving a reference-frame 3D MR image and a corresponding motion model that deforms the reference frame to each cine frame. The reference-frame 3D MR image was reconstructed as a spatial implicit neural representation (INR) network, which learns the mapping from input 3D spatial coordinates to corresponding MR values. The dynamic motion model was constructed via a temporal INR, as well as basis deformation vector fields (DVFs) extracted from prior/onboard 4D-MRIs using principal component analysis. The learned temporal INR encodes input time points and outputs corresponding weighting factors to combine the basis DVFs into time-resolved motion fields that represent cine-frame-specific dynamics. STINR-MR was evaluated using MR data simulated from the 4D extended cardiac-torso (XCAT) digital phantom, as well as two MR datasets acquired clinically from human subjects. Its reconstruction accuracy was also compared with that of the model-based non-rigid motion estimation method (MR-MOTUS) and a deep learning-based method (TEMPEST). Main results. STINR-MR can reconstruct 3D cine-MR images with high temporal (<100 ms) and spatial (3 mm) resolutions. Compared with MR-MOTUS and TEMPEST, STINR-MR consistently reconstructed images with better image quality and fewer artifacts and achieved superior tumor localization accuracy via the solved dynamic DVFs. For the XCAT study, STINR reconstructed the tumors to a mean ± SD center-of-mass error of 0.9 ± 0.4 mm, compared to 3.4 ± 1.0 mm of the MR-MOTUS method. The high-frame-rate reconstruction capability of STINR-MR allows different irregular motion patterns to be accurately captured. Significance. STINR-MR provides a lightweight and efficient framework for accurate 3D cine-MRI reconstruction. It is a ‘one-shot’ method that does not require external data for pre-training, allowing it to avoid generalizability issues typically encountered in deep learning-based methods.
Prospects for Taiji to detect a gravitational-wave background from cosmic strings
Authors: Chen Zu-Cheng , Huang Qing-Guo , Liu Chang , Liu Lang , Liu Xiao-Jin , Wu You , Wu Yu-Mei , Yi Zhu , You Zhi-Qiang
Published: March 2024

Recently, multiple pulsar timing array collaborations have presented compelling evidence for a stochastic signal at nanohertz frequencies, potentially originating from cosmic strings. Cosmic strings are linear topological defects that can arise during phase transitions in the early Universe or as fundamental strings in superstring theory. This paper focuses on investigating the detection capabilities of Taiji, a planned space-based gravitational wave detector, for the gravitational wave background generated by cosmic strings. By analyzing simulated Taiji data and utilizing comprehensive Bayesian parameter estimation techniques, we demonstrate a significant improvement in precision compared to the NANOGrav 15-year data set, surpassing it by an order of magnitude. This highlights the enhanced measurement capabilities of Taiji. Consequently, Taiji can serve as a valuable complementary tool to pulsar timing arrays in validating and exploring the physics of cosmic strings in the early Universe.
Stable gravastar with large surface redshift in Einstein's gravity with two scalar fields
Authors: Nojiri Shin'ichi , Nashed G.G.L.
Published: March 2024

We propose a class of models, in which stable gravastar with large surface redshift
becomes a solution. In recent decades, gravastars have become a plausible substitute for black
holes. Researchers have explored stable gravastar models in various alternative gravity theories,
in addition to the conventional framework of general relativity. In this paper, we present a
stellar model within the framework of Einstein's gravity with two scalar fields, in accordance
with the conjecture proposed by Mazur and Mottola [Proc. Nat. Acad. Sci. 101 (2004),
9545-9550]. In the model, the two scalar fields do not propagate by imposing constraints in
order to avoid ghosts. The gravastar comprises two distinct regions, namely: (a) the interior
region and (b) the exterior region. We assume the interior region consists of the de Sitter
spacetime, and the exterior region is the Schwarzschild one. The two regions are connected with
each other by the shell region. On the shell, we assume that the metric is given by a polynomial
function of the radial coordinate r. The function has six constants. These constants are fixed
by the smooth junction conditions, i.e., the interior region with the interior layer of the shell
and the exterior region with the exterior layer of the shell. From these boundary conditions, we
are able to write the coefficients of the scalar fields in terms of the interior radius and
exterior radius. To clarify the philosophy of this study, we also give two examples of spacetimes
that asymptote as the de Sitter spacetime for small r and as the Schwarzschild spacetime for
large r. Exploration is focused on the physical attribute of the shell region, specifically,
its proper length. The gravastar model's stability has frequently been examined by analyzing the
relationship between surface redshift and shell thickness, a comparison we also undertake with
previous models. Especially, we show that there exists a stable gravastar with a large surface
redshift prohibited by the instability in the previous works. Furthermore, by checking the
effective equation of state parameters, we show that the gravastar geometry realized in this paper
by using two scalar fields could be difficult to generate with ordinary fluid.
Effect of boundary slip on electroosmotic flow in a curved rectangular microchannel
Authors: Liu 刘 Yong-Bo 勇波
Published: March 2024

The aim of this study is to numerically investigate the impact of boundary slip on electroosmotic flow (EOF) in curved rectangular microchannels. Navier slip boundary conditions were employed at the curved microchannel walls. The electric potential distribution was governed by the Poisson–Boltzmann equation, whereas the velocity distribution was determined by the Navier–Stokes equation. The finite-difference method was employed to solve these two equations. The detailed discussion focuses on the impact of the curvature ratio, electrokinetic width, aspect ratio and slip length on the velocity. The results indicate that the present problem is strongly dependent on these parameters. The results demonstrate that by varying the dimensionless slip length from 0.001 to 0.01 while maintaining a curvature ratio of 0.5 there is a twofold increase in the maximum velocity. Moreover, this increase becomes more pronounced at higher curvature ratios. In addition, the velocity difference between the inner and outer radial regions increases with increasing slip length. Therefore, the incorporation of the slip boundary condition results in an augmented velocity and a more non-uniform velocity distribution. The findings presented here offer valuable insights into the design and optimization of EOF performance in curved hydrophobic microchannels featuring rectangular cross-sections.
Superconducting state in Ba1−x
Sr
x
Ni2As2 near the quantum critical point
Authors: Yu 余 Chengfeng 承峰 , Zhang 张 Zongyuan 宗源 , Song 宋 Linxing 林兴 , Wu 吴 Yanwei 彦玮 , Yuan 袁 Xiaoqiu 小秋 , Hou 侯 Jie 杰 , Tu 涂 Yubing 玉兵 , Hou 侯 Xingyuan 兴元 , Li 李 Shiliang 世亮 , Shan 单 Lei 磊
Published: March 2024

In the phase diagram of the nickel-based superconductor Ba1−x
Sr
x
Ni2As2, T
c has been found to be enhanced sixfold near the quantum critical point (QCP) x = 0.71 compared with the parent compound. However, the mechanism is still under debate. Here, we report a detailed investigation of the superconducting properties near the QCP (x ≈ 0.7) by utilizing scanning tunneling microscopy and spectroscopy. The temperature-dependent superconducting gap and magnetic vortex state were obtained and analyzed in the framework of the Bardeen–Cooper–Schrieffer model. The ideal isotropic s-wave superconducting gap excludes the long-speculated nematic fluctuations while preferring strong electron–phonon coupling as the mechanism for T
c enhancement near the QCP. The lower than expected gap ratio of Δ/(k
B
T
c) is rooted in the fact that Ba1−x
Sr
x
Ni2As2 falls into the dirty limit with a serious pair breaking effect similar to the parent compound.
Estimation of cancer cell migration in biomimetic random/oriented collagen fiber microenvironments
Authors: Yao 姚 Jingru 静如 , Li 李 Guoqiang 国强 , Yao 姚 Xiyao 喜耀 , Zhou 周 Lianjie 连杰 , Ye 叶 Zhikai 志凯 , Liu 刘 Yanping 艳平 , Zheng 郑 Dongtian 栋天 , Tang 唐 Ting 婷 , Song 宋 Kena 克纳 , Chen 陈 Guo 果 , Liu 刘 Liyu 雳宇
Published: March 2024

Increasing data indicate that cancer cell migration is regulated by extracellular matrixes and their surrounding biochemical microenvironment, playing a crucial role in pathological processes such as tumor invasion and metastasis. However, conventional two-dimensional cell culture and animal models have limitations in studying the influence of tumor microenvironment on cancer cell migration. Fortunately, the further development of microfluidic technology has provided solutions for the study of such questions. We utilize microfluidic chip to build a random collagen fiber microenvironment (RFM) model and an oriented collagen fiber microenvironment (OFM) model that resemble early stage and late stage breast cancer microenvironments, respectively. By combining cell culture, biochemical concentration gradient construction, and microscopic imaging techniques, we investigate the impact of different collagen fiber biochemical microenvironments on the migration of breast cancer MDA-MB-231-RFP cells. The results show that MDA-MB-231-RFP cells migrate further in the OFM model compared to the RFM model, with significant differences observed. Furthermore, we establish concentration gradients of the anticancer drug paclitaxel in both the RFM and OFM models and find that paclitaxel significantly inhibits the migration of MDA-MB-231-RFP cells in the RFM model, with stronger inhibition on the high concentration side compared to the low concentration side. However, the inhibitory effect of paclitaxel on the migration of MDA-MB-231-RFP cells in the OFM model is weak. These findings suggest that the oriented collagen fiber microenvironment resembling the late-stage tumor microenvironment is more favorable for cancer cell migration and that the effectiveness of anticancer drugs is diminished. The RFM and OFM models constructed in this study not only provide a platform for studying the mechanism of cancer development, but also serve as a tool for the initial measurement of drug screening.
Survival and maturation of human induced pluripotent stem cell-derived dopaminergic progenitors in the parkinsonian rat brain is enhanced by transplantation in a neurotrophin-enriched hydrogel
Authors: Comini Giulia , Kelly Rachel , Jarrin Sarah , Patton Tommy , Narasimhan Kaushik , Pandit Abhay , Drummond Nicola , Kunath Tilo , Dowd Eilís
Published: March 2024

Objective. Although human induced pluripotent stem cell (iPSC)-derived cell replacement for Parkinson’s disease has considerable reparative potential, its full therapeutic benefit is limited by poor graft survival and dopaminergic maturation. Injectable biomaterial scaffolds, such as collagen hydrogels, have the potential to address these issues via a plethora of supportive benefits including acting as a structural scaffold for cell adherence, shielding from the host immune response and providing a reservoir of neurotrophic factors to aid survival and differentiation. Thus, the aim of this study was to determine if a neurotrophin-enriched collagen hydrogel could improve the survival and maturation of iPSC-derived dopaminergic progenitors (iPSC-DAPs) after transplantation into the rat parkinsonian brain. Approach. Human iPSC-DAPs were transplanted into the 6-hydroxydopamine-lesioned striatum either alone, with the neurotrophins GDNF and BDNF, in an unloaded collagen hydrogel, or in a neurotrophin-loaded collagen hydrogel. Post-mortem, human nuclear immunostaining was used to identify surviving iPSC-DAPs while tyrosine hydroxylase immunostaining was used to identify iPSC-DAPs that had differentiated into mature dopaminergic neurons. Main results. We found that iPSC-DAPs transplanted in the neurotrophin-enriched collagen hydrogel survived and matured significantly better than cells implanted without the biomaterial (8 fold improvement in survival and 16 fold improvement in dopaminergic differentiation). This study shows that transplantation of human iPSC-DAPs in a neurotrophin-enriched collagen hydrogel improves graft survival and maturation in the parkinsonian rat brain. Significance. The data strongly supports further investigation of supportive hydrogels for improving the outcome of iPSC-derived brain repair in Parkinson’s disease.
Raman Spectroscopy Study of Ternary Glass Structure of CaO-SiO2-B2O3
Authors: Xie Yingfang , You Jinglin , Huang Cuirong , Liu Guopeng , Wu Caie
Published: March 2024

CaO-SiO2-B2O3 terpolymer system is used as the basic raw material to synthesize other glass and melt. Doping Pr, Eu and other rare earth elements can get special performance glass materials with good luminous performance, CaO-SiO2-B2O3 terpolymer system is widely used in packaging substrate and dielectric materials. As an ideal substitute for fluorine, boron in borosilicate has become a new research hotspot of fluorine-free protective slag technology due to its advantages of economic cost and fluxing effect. Raman spectroscopy can be used for real-time observation and microsturcture analysis of materials, which provides a powerful means for the study of high-temperature melt and glass. In this work, CaO-SiO2-B2O3 ternary glass was prepared and Raman spectrum of glass was measured, which provided the necessary basis for the subsequent analysis of its properties, structure and the relationship between its components.
Study on the Cleaning of Mold Spots on Embroidery and the Extraction and Identification of Mold
Authors: Li Bangyu , Xu Mengting , Zha Siyu , Huang Yangyang
Published: March 2024

This article collected mold samples from Suzhou Zhenhu embroidery samples contaminated with mold, cultured, isolated, and identified them, and obtained six types of mold samples. Aspergillus, 2-1 (MH091025.1), 7-2 (KP269023.1), Penicillium, 3-1 (MN856268.1), 3-2 (MK368538.1), Eupenidiella, 1-2 (EU019278.1), and Talaromyces,6-2 (KU8666646.1). The use of ultrasound and other technologies to bleach specific mold stains has basically eliminated the traces of mold stains.
Experimental Study on the Deterioration of Nickel Cadmium Battery Based on External Characteristic Analysis
Authors: Zhang Guorui , Liao Haitao , Liu Jinming , Guo Ai
Published: March 2024

Although nickel cadmium batteries have good comprehensive performance and have been used in rail transit auxiliary power systems for a long time, battery degradation is inevitable during long-term use, which largely limits its power output capability and increases the cost of use. Unlike lithium batteries, the degradation study of nickel cadmium batteries has many shortcomings, mostly limited to a certain characteristic data for degradation prediction, and lack of systematic experimental study. Therefore, this article investigates the external characteristics of nickel cadmium battery degradation from multiple points, such as electrochemical impedance, heat production, thermal stability, gas production, etc. Through the experimental analysis, it can be seen that the degradation leads to an advance in the time of oxygen production, a decrease in the thermal stability, an increase in the heat production per unit time, an increase in the charge transfer impedance and a decrease in the interface double layer capacitance.
Evaluation of Surface Stabilization and Reinforcement Effect of Fragile Bronzes
Authors: Chen Jiachang , Mai Yin , Chen Liwei , Zhang Liangshuai , Cui Xinzhan , Liu Xin
Published: March 2024

Under the influence of various factors, the bronze ware unearthed by archaeology has various diseases of different degrees, and the mineralization problem is more prominent. The physical properties of mineralized bronzes have been destroyed, and the whole is loose and fragile, which is in urgent need of reinforcement and protection. Common reinforcement and protection materials mainly consider surface sealing, matrix bonding reinforcement and penetration reinforcement. Considering the low matrix strength and complex disease types of fragile bronzeware, it is difficult to achieve targeted protection with commonly used reinforcement and protection materials. In view of the problems such as poor permeability and easy discoloration of commonly used protection materials, this paper uses self-developed reinforcement and protection material AMC to compare its reinforcement and protection performance with B72, which has a high comprehensive evaluation on the performance of commonly used reinforcement and protection materials. The matrix strength was increased, and the appearance intervention degree was less than B72.
Prediction of Wear Resistance of In-situ Zinc Matrix Composites Reinforced by Silicon Phase Based on Neural Network
Authors: Zhao Haofeng , Wang Ru , Hu Yingjie , Peng Tao , Chen Zixiang
Published: March 2024

Silicon phase reinforced zinc-aluminium alloy composites were prepared by in-situ method. The effect of silicon content and external load on the wear resistance of in-situ zinc--aluminium composites was studied by BP artificial neural network. The test results show that the silicon phase, as a hard material, plays the role of supporting load and improves the wear resistance of the alloy. With the increase of Si content, the wear resistance of in-situ zinc--aluminium composites increased first and then decreased. When the amount of silicon added exceeds 2.5-3%, the wear resistance will be reduced, which is related to the silicon phase aggregation and the easy separation of large silicon phases from the matrix. With the increase of external load, the relative wear continues to increase, which is related to the increase of friction. The neural network platform can successfully predict the general trend of wear resistance with the change of silicon content and load.
The Method of Ply Generating in Composite Laminate in Fibersim
Authors: Guo Jianfen
Published: March 2024

In Fibersim the digital design of the composite preforms laying process begins with the creation of laminates, which define the required preforms and its plies. The digital design of ply-based laying process, zone-based laying process, multi-ply-based laying process, and the methods of multi-ply and zone-based laying process are elaborated.
Fabrication of Bi2MoO6/MIL-101 (Fe) Composites for Visible Light Photocatalytic Activity Enhancement
Authors: Liu Xintong , Su Chunyan , Wang Baorui , Xu Mingyi , Wang Linfeng , Li Min
Published: March 2024

Bi2MoO6/MIL-101 (Fe) composite photocatalyst was prepared by a two-step solvothermal method, the photocatalytic decomposition reaction was carried out using visible light as light source and Congo red (CR) aqueous solution as the simulated dye wastewater. The results showed that the photocatalytic activity of Bi2MoO6/MIL-101 (Fe) composite photocatalyst was better than pure MIL-101(Fe) catalyst for the degradation of CR. Bi2MoO6/MIL-101(Fe) composite photocatalyst could compensate for the slower electron mobility and the easy compounding of photogenerated electron-hole pairs of MIL-101(Fe). The degradation efficiency of Bi2MoO6/MIL-101(Fe) photocatalyst for CR remained high after five cycles, indicating its good stability and reusability.
Study on Influence of Electrode Type on Weld ability of TL091 Al. Alloy in Medium Frequency RSW
Authors: Zhong Lihui , Yu Wenchao , Jia Lei , Han Lijun
Published: March 2024

The characteristics and difficulties of medium frequency resistance RSW (MFRSW) of high strength Al alloy TL091 were analyzed. In order to improve the service life of Al. alloy RSW electrode cap (EC), the shape of EC and welding parameters were studied. The weld ability of RSW of Al. alloy TL091 was studied by using a special pressing mold to make the surface of EC form a special shape. By studying the type and size of the surface-forming mold, pressing method and pressing parameters, the key factors affecting the weld ability of Al. alloy RSW were obtained. The specification and shape of compaction mold will affect the adhesion between alloy and EC, and pit depth, pit distance width and boss size of the mold have great influence on welding ability of Al RSW after single grinding. When indentation depth of the pressing mold is 0.5 mm, the width between the molds is 0.4~0.5 mm, and the width of bulge is 0.2 mm, it can obtain a RSW capability of at least 128 points after each grinding. The direction and ideas for improving the life of Al. alloy RSW EC were determined, which could provide reference for the optimization of automobile Al. alloy RSW.
Research on the Uneven Deformation Law of High Temperature Alloy Large Caliber Ultra-Thin-Walled Tube Parts during Spinning
Authors: Cheng Hui , Zhao Gangyao , Chen Qi , Guo Zhenghua , Zhang Ranyang
Published: March 2024

Based on the established spinning forming model of GH 4169 large caliber ultra-thin-walled tube parts, the radial stress-strain, normal stress-strain, and circumferential stress-strain distributions were analyzed through simulation methods. The uneven deformation law of GH 4169 large caliber ultra-thin-walled tube parts during spinning was obtained. The results indicate: With the progress of spinning, the radial stress is presented as tension, the normal stress is presented as compression, and the circumferential stress is presented as tension and compression. Therefore, the distribution of equivalent stress is uneven, leading to different tensile and compressive states of the triaxial principal strains in all directions, resulting in a small amount of fluctuation at the edge of the blank.
The Aging Effects of Ultraviolet Irradiation on the Optical Properties of Glass
Authors: Han Huimin , Liu Yueyue , Wang Qingwei , Luo Lida
Published: March 2024

Glass is known for its high mechanical strength, resistance to high temperatures, corrosion resistance, excellent transparency, thermal stability, and good electrical insulation properties, making it widely used in various fields such as construction, household, and automotive applications. In this study, three types of glass samples were exposed to three different environments: outdoor, ultraviolet (UV) irradiation, and UV irradiation in water vapor. The influence of these different environments on light transmittance and surface morphology was investigated using UV-visible-near infrared spectroscopy and scanning electron microscopy. The experimental results indicate that lead-containing glass exhibits excellent resistance to UV irradiation, sodium-calcium glass samples exhibit significant variations in transmittance in the UV and infrared regions, possibly related to iron content, and high borosilicate glass samples show a noticeable decrease in transmittance in the infrared region.
Analysis on Failure Mechanism of Rock-Coal Two-Body Structure with Weak Cemented Rock and the Condition of a Gob Side Entry without Coal Pillar
Authors: Chen Fan , Cao Zongzhong , Li Shengjun , Fan Yixin
Published: March 2024

Though the real tri-axial testing simulated by FLAC3D, the failure mechanism and deformation process of rock-coal “two-body” structure in the in-situ area, named crucial point, which bore the ultimate lateral abutment pressure and broke in the beginning to lead to the whole damage of the “three soft” ground-rock around the gob-side entry retaining was obtained, and the relationship between the ultimate strength and cohesion of rock was obtained. By field observation the condition of gob side entry without coal pillar was obtained: top old roof as the bearing body, when the height of direct roof was larger than 1.309m1 and soft enough, the half-arch structure could made by the upper strata of the direct roof, as a weak layer, which gave a force straight up against to the old roof overturning and sinking. That was the condition of gob side entry retaining without coal pillar.
Feasibility Study on In-Situ Driving Roadway along Goaf in Three Soft Thick Coal Seam
Authors: Chen Fan , Cao Zongzhong , Li Shengjun , Fan Yixin
Published: March 2024

Uniaxial compression, triaxial compression and coal crushing experiment were tested to get the soft the three soft characteristics of coal seam and surrounding rock in the third teaching mine in western Henan. Considering the influence of water and argillaceous composition, the relationship between the waste rock expansion factor and pressure was obtained after correction. Introducing the relationship into the calculation of maximum lateral bearing pressure point and collapse characteristic distribution, its results were in good agreement with the measured and simulated results. Establishing the accumulation form factor, “v”, of gob waste rocks in trend, and the representation of “v” was obtained by theoretical calculation. After a lot of calculations to analysis the relationship of “v” and “N”, “q
1”, “Kp
”, “H”, “m”, “Rt
”, and a lot of numerical simulations by 3dec, the results were got below: When the thickness of the direct roof was large, 1<“v”,the lower park of direct roof was collapsed and accumulate naturally, and the upper park was formed an arch bearing structure. While, the roadway excavation in this situation was larger than the condition of “v”<1 in the early stage, but its excavation was easy with broken wall rock, and the roadway deformation and maintenance were smaller with the protection by the arch bearing structure. The more soft the coal seam, its deformation toward gob and the distance between maximum lateral bearing pressure point and coal wall were more larger, and driving along the goaf would recover a large amount of coal. Under truss support,roadway deformation decreased significantly and very similar to the experimented results in situ. So when the seam and direct roof was soft, thick, and 1<“v”, driving roadway along goaf in situ was in the low stress zone protected by the arch bearing structure formed above, and it was a good engineering conditions for the recovery of coal in the gob, and for the overall roadway excavation with one-time laying of the anchor rod and metal mesh. This was the reason why roadway excavation along the goaf was mainly used for mining medium thick or thick coal seams with gentle inclination, inclination and large thickness.
Study on the Effect of Ultra-fine Limestone Powder on the Resistance of Cement-slag Powder System to Chloride Ion Permeability
Authors: Gao Xin
Published: March 2024

The effect of different limestone powder fineness on the chloride ion migration coefficient of the cement paste was tested using the Rapid Chloride Migration (RCM) method. The changes in the phase composition and pore structure of the paste were studied using hydration kinetics analysis, XRD and pore structure analysis. The results showed that before the chloride ion erosion, the limestone powder mainly exhibited filling effect, microcrystalline nucleation effect, and chemical activity effect. It reacted with the hydration products of cement to form calcium aluminate carbonate, which improved the strength of the hardened paste. After chloride ion erosion, the diffraction peak of calcium aluminate carbonate weakened, and Friedel’s salt was formed. With the increase of the specific surface area of limestone powder, the chemical activity of the powder became more obvious, and the generation of Friedel’s salt increased, leading to stronger resistance to chloride ion penetration. Limestone powder can reduce the porosity of the hardened paste and optimize the pore structure. When the particle size of the powder increased from 800 to 5000 mesh, the total porosity of the hardened paste decreased from 20.7% to 14.7%, and the most probable pore size decreased from 450nm to 75nm. Limestone powder with a particle size larger than 1500 mesh can fully exert its activity and play a role in solidifying chloride ions, thus improving the resistance to chloride ion penetration of limestone powder cement-based materials.
Analysis of the Temporal and Spatial Development of Cold Waves in Fujian Province over the Last 58 Years
Authors: Wang Tiantian , Jin Shaofei , Wang Ku
Published: March 2024

The escalation in the risk of extreme weather events due to climate system warming has caused a distinct alteration in the frequency and intensity of cold waves in China. Moreover, these changes exhibit distinct regional variations in their altering characteristics. Using daily temperature data from 70 weather stations in Fujian Province of China from 1961 to 2018, this study looks at how cold waves move through the province and how they change over time. It does this by combining linear regression trend, spatial interpolation, and spatial autocorrelation analyses. The findings indicate that the occurrence frequency of cold waves in the designated study area is notably higher in the western and northern regions, while it is comparatively lower in the eastern coastal cities. Furthermore, there is an overall downward trend in the frequency of cold waves, with a declining frequency from 1961 to 2000, followed by a significant increase in frequency after 2000. Furthermore, the number of cold waves in the study area increased significantly after 2010.
Pore-scale Simulation of Two-phase Flow in Foamed Porous Materials
Authors: Liang Yaxuan , Wang Ping , Zhang Xuan , Dou Haoyuan
Published: March 2024

This paper establishes a pore cell model of foamed silicon carbide material based on a tetradecahedron structure, and uses FLUENT software to numerically study the flow rate and pressure drop changes in the porous structure at different flow rates and the gas-liquid two-phase flow state of the channel. The research results show that the porous skeleton structure has a great influence on the velocity and pressure distribution in the calculation domain; the inlet flow velocity has a certain impact on the gas-liquid mixing zone and gas-liquid interface area in two-phase flow. The application of tetradecahedral porous media increases the thickness of the gas-liquid mixing zone and the phase interface area are increased, with a maximum increase of 11.5%, thus promoting gas-liquid heat and mass transfer.
Application Practice for Low Environmental Impact Deep Acidizing Process to Improve Injection Capacity of Water Injection Wells
Authors: Deng Xiaoguo , Yan Yu , Fu Jie , Li Heng , Yang Yang , Cai Qingqin , Cao Xiaomei , Dou Tongwei , Zhao Junfeng , Jing Haiquan
Published: March 2024

There are problems of high injection pressure and water injection difficulties in some injection wells among more than thirty wells that have been injected in H oilfield, and the overall water injection is insufficient. This paper analyzes the reasons for the injection problem from the perspective of block characteristics: for the decline in injection capacity due to reservoir pore blockage caused by clay expansion and contamination by injected impurities, it is proposed to apply a low environmental impact deep acidification system to improve the injection capacity of water wells.
Research Progress of Microplastic Pollution Status and Risk Assessment of Typical Rivers in China
Authors: Zhang Jie , Hong Lei , Wu Ke , Wang Qun , Li Mengmeng , Li Xu , Jin Jie
Published: March 2024

Microplastics (MPs) have received a lot of attention since they were recognized as an emerging pollutant. Rivers transport 80 % of the land’s MPs to the oceans. With so many rivers in China, the problem of MPs pollution cannot be ignored. This paper collects data related to MPs in typical rivers in China, summarizes the sources of river MPs, and analyses the status of river MPs pollution and risk evaluation. The results show that riverine MPs mainly originate from sewage treatment plants, surface runoff, atmospheric deposition and plastic breakage. MPs abundance is closely related to population density, with urban rivers having higher MPs abundance than other regions. MPs less than 1 mm in size account for more than 60 % of most rivers. At present, the risk assessment of river MPs is mainly based on three methods, namely, the ecological risk index (PHI), the pollution load index (PLI) and the potential ecological risk index (PERI), and the results of the assessment are mostly low risk. There are differences in the results of the assessment models, which need to be applied jointly with each other for continuous improvement.
Simulation of Fountain Flow based on Molecular Dynamics Method
Authors: Chen Tengfei , Pu Kejin , Zhang Xiaoliang , Zhao Zhongshuai , Guo Chao , Yan Baoshan , Wang Tingjun
Published: March 2024

In this paper, numerical simulations of the fountain effect on the flow front of polymer dilute solutions are carried out based on molecular dynamics principles and the FENE dumbbell model. The Euler method is used to solve the constitutive equations of the mechanical model for the simple shear flow field and the dislocation equations of the dumbbell molecules, and subsequently obtain the tracer flow lines and the dumbbell distribution of the flow front. The results are used to calculate the stress field, analyze the rheological evolution law, study the effect of temperature and shear rate and other parameters on the model and analyze the effectiveness of the FENE dumbbell molecular model for the fountain effect. The study shows that due to the fountain effect the dumbbell molecules stretch more with increasing shear rate, the polymer stress at the flow front will show a complex change of stress overshoot and then stabilize, and the dumbbell molecules are oriented along the fountain flow line.
Aerodynamic Investigation of Propulsion Integration for a Low Noise Hybrid Wing-Body with Podded UHBR Turbofan Engines
Authors: Keller Dennis
Published: March 2024

The presented work examines the aerodynamic challenges of podded ultra high-bypass engines installed on a short/mid range low noise hybrid wing body configuration. After assessing the initial engine integration design, sensitivity studies regarding the impact of the freestream Mach number, engine position, and the engine incidence angle on the interference drag are discussed. Then, shape modifications of the nacelle and the center-body based on 2D RANS optimizations are presented. The results indicate that in order to reduce the initially massive interference drag, the overall aircraft design either has to allow for a modified engine position or for reshaping of the center-body’s upper surface. With the latter, an overall drag reduction of –44 % was achieved.
Electric flight operations for interisland mobility
Authors: Donckers S , Stamoulis K P , Apostolidis A
Published: March 2024

Several studies have shown that flying electric between the so-called ABC-islands in the Caribbean (i.e., Aruba, Bonaire and Curaçao) is feasible with the upcoming first generation of battery-electric aircraft. This paper presents a real-world case study that deals with the technical and operational characteristics of electric flight in that region. With that purpose, the Aruba Airport Authority (AAA) commissioned this investigation, which involved numerous local stakeholders, such as airlines, energy providers and navigation services. This study involves two commuter electric aircraft under development, aiming to investigate how they fit in the current operational scheme of three local airlines and three conventional aircraft types in terms of technology, capacity, schedule, performance, CO2 emissions and fuel costs. Conclusions indicate that a transition to batter-electric aircraft is feasible with regards to the aforementioned criteria and with the current technology and energy density of batteries.
Reducing Environmental Impact of Jet Engines by Hydrogen Co-combustion
Authors: Przysowa Radoslaw , Grundas Dariusz , Gawron Bartosz , Zieliński Konrad
Published: March 2024

Due to the need to mitigate global warming, there is a growing interest in alternative fuels for various means of transport, including aviation gas-turbine engines. The work aimed to check the impact of hydrogen co-combustion on the performance and emissions of aircraft engines. Zero-dimensional models of JetCat P140 RXI and DGEN 380 engines developed in the GSP (Gas Turbine Simulation Program) program were used in the research. Combustion calculations in GSP are based on the real gas model and NASA Chemical Equilibrium Applications (CEA) equations. The performance of the engines fueled by Jet A-1 and blends containing hydrogen or methane were calculated. The simulations were performed at the design point on the ground, and then in flight for selected altitudes and flight speeds. With an increase in the gas content in the blend, the thrust and temperature behind the turbine slightly increase, and the specific fuel consumption decreases, because hydrogen and methane have a higher calorific value. The performance of JetCat and DGEN 380 engines was calculated for blends of kerosene with methane or hydrogen. This knowledge will be used to convert these engines to gaseous fuels. In terms of fuels and emissions, GSP has limitations related to the set of available chemicals and the zero-dimensional model of the combustor.
An overview of the possibilities, current status, and limitations of battery technologies to electrify aviation
Authors: Suárez María Zamarreño , Moreno Francisco Pérez , Jurado Raquel Delgado-Aguilera , Valdés Rosa María Arnaldo , Comendador Víctor Fernando Gómez
Published: March 2024

One of the main concerns of the aviation industry is the reduction of dependence on fossil fuels, the reduction of emissions, and, ultimately, the development of a more sustainable air transport system. Emerging technologies, new operational concepts, and research will be essential to achieve this. Batteries are one of the emerging technologies that will play a key role in the electrification of aviation in the coming years. To ensure the scalability of this technology, an analysis of its possibilities, current status, and limitations is essential. The aim of this study is to carry out such an analysis, answering five key questions related to this technology: i) what is a battery?, ii) what are the key parameters of batteries?, iii) what are the possibilities of battery technology to electrify aviation?, iv) what are the main challenges to overcome?, and finally, v) how can batteries be classified? The answers to these questions will make it possible to present the state of the art of this technology, and to identify the main challenges to be addressed in its future development.
Energy management of an eVTOL aircraft with optimization based on the Equivalent Consumption Minimization Strategy (ECMS)
Authors: Taghbalout Meryem
Published: March 2024

This article introduces an optimization-based energy management strategy developed and validated for electric vertical take-off and landing (eVTOL) aircraft. The primary objective of this strategy is to minimize hydrogen consumption while accounting for resource constraints, such as the battery and fuel cell, to enhance energy efficiency and sustainability while adhering to performance and safety requirements. The eVTOL employed in this research is an essential component of our “Viable” research project, featuring a hybrid propulsion system that combines batteries and fuel cells.

To accomplish this, mathematical and computational techniques were employed using the equivalent consumption minimization strategy method to determine the optimal operational parameters for the eVTOL aircraft, considering the available energy resources. These techniques were implemented for the first time in MATLAB, enabling simulations of the aircraft’s performance under various conditions. The results demonstrate the efficacy of the energy management strategy in significantly reducing hydrogen consumption while maintaining optimal performance and safety. Graphs and comparative analyses are presented to highlight the evolution of hydrogen consumption compared to different parameters and to compare the approach with alternative methods.

Furthermore, the article explores an alternative solution that offers related results and performance as MATLAB, utilizing the open-source software OpenModelica (OM). Energy management experiments using ECMS were conducted on OM, yielding highly satisfactory outcomes in terms of simulation accuracy and cost-effectiveness. The method was also evaluated in simulations of propulsive system resources, developed on OM, validating the results concerning energy distribution, compliance with constraints, and real-time feedback.

In summary, this article presents a comprehensive strategy for effectively managing energy consumption in eVTOL aircraft. By leveraging simulations conducted in MATLAB and OM, the strategy’s effectiveness was assessed, with potential implications for advancing the sustainability of electric eVTOL aircraft.
Kinetic Energy Recovery from a landing aircraft: Evaluating Onboard Energy Solutions
Authors: Camilleri R , Batra A , Bartolo L B , Delavault A
Published: March 2024

This paper compares onboard Energy Storage Solutions (ESSs) for a Kinetic Energy Recovery System (KERS) from a landing aircraft. Energy is stored temporarily and reused so that it enables engine-less taxiing. This paper evaluates the choice of onboard Energy Storage Solutions (ESSs) (flywheels, batteries and supercapacitors) for recovering energy during the landing roll and storing it in the device. A design of an ESS with each of the three technologies was made, using commercially available products. The resulting devices are compared on the basis of weight, charging time, discharging time and complexity in retrofitting to existing systems. Results shows that while batteries have the highest energy density and will have the lowest weight, they are unable to charge/discharge quickly enough to satisfy this application. Conversely, supercapacitors have this ability but their low energy density make them heavy which in turn would offer penalty to the aircraft in flight. Flywheels emerge as the most interesting proposition due to their high energy density and fast charging ability, which satisfy the requirements for application.
A Versatile Computation Platform applied to Environmental-Impact Assessments at Airport Level in Clean Sky 2
Authors: Weggemans J E , van Eenige M J A
Published: March 2024

The objective of the Clean Sky 2 Technology Evaluator project GREENPORT2050 is to assess the environmental impact up to 2050 at airport level of technologies developed in Clean Sky 2 for fixed-wing aircraft. To not only facilitate computational processes and improve their efficiency, but also to ensure quality and configuration-management tasks are automatically and well taken care of, Royal NLR develops a versatile computation platform for conducting these assessments. This paper provides an overview of the platform’s implementation (adopting modern, widely-accepted and proven technologies) and its key features (especially in relation to the mechanism of defining and integrating models).
Synergy in Future Avionics: An Overview of Multiple Technologies for Small Air Traffic Segment in the COAST project
Authors: Lucky Jakub , Vito Vittorio Di , Beran Jan , Kabrt Tomas , Vaispacher Tomas , Korenciak Lubos , Dobes Michal , Grzybowski Piotr , Masłowski Piotr
Published: March 2024

The paper describes research and development activities under Clean Sky 2 Cost optimized Avionic System (COAST) program. The main goal of this development was to deliver technology enablers at TRL 5 for affordable cockpit and avionics. The target segment for the technology enablers is aircraft with 1 to 19 passengers and small cargo aircraft belonging to CS-23 category. The main aim is to provide overall summer during the whole COAST program development per individual technology. Sections are divided per each technology with their results and overall contribution to the program. The Clean Sky 2 COAST program covered the development of following technologies: Cockpit Architecture SAT avionic system architecture, Flight Management Tactical Separation System (TSS), Advanced Weather Awareness System (AWAS), Flight Reconfiguration System (FRS), Navigation and Surveillance Dual Frequency Multi-Constellation GNSS Receiver (GNSS), Low-cost Integrated Navigation System (NAV), Affordable Integrated Surveillance System (SURV), Platform technologies Compact Computing Platform (CCP), High Integrity Electronics for health monitoring (HIE), Integrated Mission Management System Integrated Mission Management System (IMMS). These technologies were part of several flight test campaigns which took place in the Czech Republic with Evektor company using EV-55 aircraft.
On UAV Terrestrial Connectivity Enhancement through Smart Selective Antennas
Authors: Pagliari Emanuele , Davoli Luca , Cicioni Giordano , Palazzi Valentina , Ferrari Gianluigi
Published: March 2024

Nowadays, Unmanned Aerial Vehicles (UAVs) are widely used in heterogeneous contexts and, thanks to a continuous technological evolution, are going to be used for several applications such as, for example, Beyond Visual Line of Sight (BVLOS) operations. Since in BVLOS flights the UAV and the ground control center may not have a direct visibility with each other, a robust communication system is needed to provide reliable connectivity. Although a cellular (4G/5G) network is the current best candidate to enable BVLOS applications, there are still some limitations to overcome, as 4G (LTE) and 5G (NR) cellular networks are natively designed for terrestrial use. In this paper, we first investigate current cellular communication limitations for UAV-based applications, in particular taking into account both results available in the literature, as well as experimental performance campaigns. Then, a viable solution for mitigating these drawbacks exploiting selective on-board antennas is proposed, whose performance is experimentally investigated with a preliminary prototypical architecture.
On-board drone classification with Deep Learning and System-on-Chip implementation
Authors: Di Cecio G , Manco A , Gigante G
Published: March 2024

In recent years the increasing use of drones has raised significant concerns on safety and make them dramatic threats to security. To address these worries Counter-UAS Systems (CUS) are capturing the interest of research and of industry. Consequently, the development of effective drone detection technologies has become a critical research focus. The proposed work explores the application of edge computing to drone classification. It tunes a Deep Learning model, You Only Look Once (YOLO), and implements it on a Field Programmable Gate Array (FPGA) technology. FPGAs are considered advantageous over conventional processors since they enable parallelism and can be used to create high-speed, low-power, and low-latency circuit designs and so to satisfy the stringent Size, weight and Power (SWaP) requirements of a drone-based implementation. In details, two different YOLO neural networks YOLO v3 and v8 are trained and evaluated on a large data set constructed with drones’ images at various distances. The two models are then implemented on a System-on-Chip (SoC). In order to demonstrate the feasibility of a drone on board image Artificial Intelligence processing, the evaluation assesses the accuracy of classification and the computational performances such as latency.