bluuebunny/crossref_metadata_2025 huggingface dataset:
Cryogenic Impact on Carbon Fiber-Reinforced Epoxy Composites for Hydrogen Storage Vessels
Authors: Dagdag Omar , Kim Hansang
Published: November 2024

Carbon fiber-reinforced epoxy (CF/EP) composites are attractive materials for hydrogen storage tanks due to their high strength-to-weight ratio and outstanding chemical resistance. However, cryogenic temperatures (CTs) have a substantial impact on the tensile strength and interfacial bonding of CF/EP materials, producing problems for their long-term performance and safety in hydrogen storage tank applications. This review paper investigates how low temperatures affect the tensile strength, modulus, and fracture toughness of CF/EP materials, as well as the essential interfacial interactions between carbon fibers (CFs) and the epoxy matrix (EP) in cryogenic environments. Material toughening techniques have evolved significantly, including the incorporation of nano-fillers, hybrid fibers, and enhanced resin formulations, to improve the durability and performance of CF/EP materials in cryogenic conditions. This review also assesses the hydrogen barrier properties of various composites, emphasizing the importance of reducing hydrogen permeability in order to retain material integrity. This review concludes by highlighting the importance of optimizing CF/EP composite design and fabrication for long-term performance and safety in hydrogen storage systems. It examines the prospects for using CF/EP composites in hydrogen storage tanks, as well as future research directions.
Bioengineering the Junctional Epithelium in 3D Oral Mucosa Models
Authors: Gavriiloglou Marianna , Hammad Mira , Iliopoulos Jordan , Layrolle Pierre , Apatzidou Danae
Published: November 2024

Two-dimensional (2D) culture models and animal experiments have been widely used to study the pathogenesis of periodontal and peri-implant diseases and to test new treatment approaches. However, neither of them can reproduce the complexity of human periodontal tissues, making the development of a successful 3D oral mucosal model a necessity. The soft-tissue attachment formed around a tooth or an implant function like a biologic seal, protecting the deeper tissues from bacterial infection. The aim of this review is to explore the advancements made so far in the biofabrication of a junctional epithelium around a tooth-like or an implant insert in vitro. This review focuses on the origin of cells and the variety of extracellular components and biomaterials that have been used for the biofabrication of 3D oral mucosa models. The existing 3D models recapitulate soft-tissue attachment around implant abutments and hydroxyapatite discs. Hereby, the qualitative and quantitative assessments performed for evidencing the soft-tissue attachment are critically reviewed. In perspective, the design of sophisticated 3D models should work together for oral immunology and microbiology biofilms to accurately reproduce periodontal and peri-implant diseases.
Impact of Combined Zr, Ti, and V Additions on the Microstructure, Mechanical Properties, and Thermomechanical Fatigue Behavior of Al-Cu Cast Alloys
Authors: Hu Peng , Liu Kun , Pan Lei , Chen X.-Grant
Published: November 2024

The effects of minor additions of the transition elements Zr, Ti, and V on the microstructure, mechanical properties, and out-of-phase thermomechanical fatigue behavior of 224 Al-Cu alloys were investigated. The results revealed that the introduction of the transition elements led to a refined grain size and a finer and much denser distribution of θ″/θ′ precipitates compared to that of the base alloy, which enhanced the tensile strength but reduced the elongation at both room temperature and 300 °C. Constitutive analyses based on theoretical strength calculations indicated that precipitation strengthening was the primary mechanism contributing to the strength of both tested alloys at room temperature and 300 °C. The out-of-phase thermomechanical fatigue test results showed that the addition of transition elements caused a slight decrease in the fatigue lifetime, which was mainly attributed to the reduced ductility and higher peak tensile stress at low temperatures. During the fatigue process, the transition element-added alloy exhibited a lower coarsening ratio, indicating higher thermal stability, which mitigated the negative impact of the reduced ductility on the fatigue performance to some extent. Considering their various properties, the addition of Zr, Ti, and V is recommended to improve the overall performance of Al-Cu 224 cast alloys.
An Experimental Study on Vortex-Induced Vibration Suppression of a Long Flexible Catenary Cable by Using Vibration Dampers
Authors: Ruan Li , Zhu Hongzhong , Hu Changhong
Published: November 2024

In this paper, an experimental study is conducted to investigate the effectiveness of vibration dampers in suppressing vortex-induced vibration in a long, flexible catenary cable with a low mass ratio. The dampers, consisting of two small, symmetric, lightweight pipes clamped to the cable, are sparsely deployed along the cable to shape the vibration characteristics. The experimental results demonstrate that dampers significantly reduce the vibration amplitude by up to 60% and axial tension by up to 61% at high flow velocities, effectively suppressing the cable vibration in perpendicular flow. In addition, it is observed that the in-line and cross-flow vibration frequencies are approximately equal when the dampers are applied. This behavior contrasts with the conventional undamped catenary cable, where the in-line vibration frequencies are double those of the cross-flow frequencies.
On the Influence of Beach Slope on Wave Non-Linearities on a Macrotidal Low-Tide Terrace Beach
Authors: Diouf Amadou , Floc’h France , Sow Bamol Ali , Caulet Charles , Augereau Emmanuel
Published: November 2024

This study examines the evolution of wave shapes as they propagate over a beach of varying morphology, information essential for understanding coastal dynamics and supporting coastal management. Our objective was to analyze the relationship between wave shape parameters and the local slope of the beach. To achieve this, we used data from pressure sensors and topographic measurements to evaluate the shape of waves on a cross-shore profile of a low-tide terrace beach. The analysis of wave conditions revealed a pronounced modulation of the tidal signal, which is augmented during storm events. Our findings demonstrate that the asymmetry and skewness parameters are more pronounced in the reflective zone of the beach. Considering these results, it can be concluded that the non-linearity of waves is significantly affected by the beach slope. The parameterization method employed in this study effectively incorporates this factor, offering improved accuracy in comparison to the existing approaches.
Characteristic Analysis of Vertical Tidal Profile Parameters at Tidal Current Energy Site
Authors: Lee Uk-Jae , Ko Dong-Hui , Park Jin-Soon
Published: November 2024

Many mathematical models have been proposed to estimate vertical tidal current profiles. However, as previous studies have shown that tidal current energy sites have different characteristics in their vertical tidal current profiles, it is necessary to estimate the profiles from field-measured data for practical purposes. In this study, we measured layered tidal currents over two months using an acoustic Doppler current profiler (ADCP) to analyze the characteristics of vertical tidal current profiles at the Jangjuk Strait, a candidate site for tidal current energy. As a result, the power law parameter α and bed roughness β were estimated as 4.51–12.41 and 0.38–0.42, respectively. Additionally, the maximum roughness length representing seabed roughness in the logarithmic profile was estimated as 0.221 m, and the estimated friction velocity was 0.038–0.194 m/s. Furthermore, a high correlation was observed between the depth-averaged tidal current velocity and friction velocities at all sites during flood and ebb tide conditions. A high correlation was also found between the bed roughness, roughness length, and power law exponent at relatively deeper sites. Tidal current energy sites display distinct characteristics compared to other sea areas. Therefore, it is essential to account for field conditions when conducting numerical modeling and design.
Numerical Simulation of Ice and Structure Interaction Using Common-Node DEM in LS DYNA
Authors: Bai Xiaolong , Jiang Yin , Shen Zhongxiang , Liu Renwei , Liu Zhen
Published: November 2024

In this work, the icebreaking performance of the cone structure was investigated using a new numerical model called the common-node DEM developed within LS DYNA. The icebreaking characteristics of a typical conical jacket platform in the Bohai Sea focusing on the JZ20-2NW single-pile-leg platform was studied and the ice load characteristics of the cone structure and the dynamic response of the jacket platform under various ice conditions was investigated. The findings indicate that ice thickness significantly impacts the icebreaking mechanism of the cone structure. Specifically, both the peak ice load and the peak acceleration of ice-induced vibrations are proportional to the square of the ice thickness. Additionally, the upward trend in positive vibration displacement of the jacket platform becomes more pronounced with increasing ice thickness. While both the acceleration and displacement caused by ice-induced vibrations on the jacket increase with rising ice velocity, this effect is less significant compared to the influence of ice thickness. Importantly, the ice load remains below the yield strength of the conical shell plate, demonstrating that traditional conical shell plate structures possess a margin of strength redundancy.
A Review on the Recent Process of Lazy Wave Risers
Authors: Ruan Weidong , Zhou Chengcheng , Yang Hongyu , Wang Zhi , Sun Bo , Bai Yong
Published: November 2024

Lazy wave risers (LWRs) are designed with equidistant buoyancy blocks attached in the lower half of the riser, allowing the riser to take on an arch shape under the buoyancy forces provided by buoyancy blocks. This arch configuration can provide flexibility to the LWR arrangement and effectively isolate the dynamic responses between the offshore floating structure and the riser’s touchdown zone (TDZ). Its design and application aim to address the issues of dynamic response and fatigue damage that traditional steel catenary risers (SCRs) face in deep water and complex marine environments. Given that research on the LWRs in the field of ocean engineering is not sufficiently abundant, the structural characteristics, hydrodynamic loads, global responses, fatigue damage assessment, and structural optimization progress of LWRs are systematically reviewed in this paper to provide references for researchers in related fields. Among these topics, the global response of LWRs is the main point of this review. This section details the theoretical analysis and numerical modeling methods employed in the study of LWRs’ global response, explores the research advancements in the vortex-induced vibration (VIV) related to LWRs, and discusses corresponding experimental studies. Finally, the installation, transfer, and repair processes of LWRs are investigated. Additionally, the importance of leveraging advanced technologies from other fields and combining them with current advanced algorithms is emphasized in efforts to assess fatigue damage and optimize the structures of LWRs, ultimately achieving complementary advantages.
Diversity Patterns and Drivers of Soil Bacterial and Fungal Communities in a Muddy Coastal Wetland of China
Authors: Song Baohan , Wang Tianyi , Wan Cheng , Cai Yuan , Mao Lingfeng , Ge Zhiwei , Yang Nan
Published: November 2024

Elucidating the dynamics of soil microbial diversity in coastal wetlands is essential for understanding the changes in ecological functions within these ecosystems, particularly in the context of climate change and improper management practices. In this study, the diversity patterns and influencing factors of soil bacterial and fungal communities in a muddy coastal wetland in China were investigated using Illumina sequencing of 16S rRNA and ITS1, across wetlands dominated by different vegetations and varying proximity to the coastline. The wetlands include four plots dominated by Spartina alterniflora (SA1), four plots dominated by Suaeda glauca (SG2), additional four plots of Suaeda glauca (SG3), and four plots dominated by Phragmites australis (PA4), ranging from the nearest to the coast to those farther away. The results revealed significant differences in bacterial richness (Observed_species index) and fungal diversity (Shannon index) across different wetlands, with SG3 demonstrating the lowest bacterial Observed_species value (1430.05), while SA1 exhibited the highest fungal Shannon value (5.55) and PA4 showing the lowest fungal Shannon value (3.10). Soil bacterial and fungal community structures differed significantly across different wetlands. The contents of soil available phosphorus and total phosphorus were the main drivers for fungal Observed_species and Shannon index, respectively. Soil organic carbon, pH, and salinity were indicated as the best predictors of bacterial community structure, accounting for 28.1% of the total variation. The total nitrogen content and soil salinity contributed mostly to regulating fungal community structure across different wetlands, accounting for 19.4% of the total variation. The results of this study offer a thorough understanding of the response and variability in soil microbial diversity across the muddy coastal wetlands in China.
Biocontrol Agents Inhibit Banana Fusarium Wilt and Alter the Rooted Soil Bacterial Community in the Field
Authors: Du Chanjuan , Yang Di , Jiang Shangbo , Zhang Jin , Ye Yunfeng , Pan Lianfu , Fu Gang
Published: November 2024

Banana is an important fruit and food crop in tropical and subtropical regions worldwide. Banana production is seriously threatened by Fusarium wilt of banana (FWB), a disease caused by Fusarium oxysporum f. sp. cubense, and biological control is an important means of curbing this soil-borne disease. To reveal the effects of biocontrol agents on inhibiting FWB and altering the soil bacterial community under natural ecosystems, we conducted experiments at a banana plantation. The control efficiency of a compound microbial agent (CM), Paenibacillus polymyxa (PP), Trichoderma harzianum (TH), and carbendazim (CA) on this disease were compared in the field. Meanwhile, the alterations in structure and function of the rooted soil bacterial community in different treatments during the vigorous growth and fruit development stages of banana were analyzed by microbiomics method. The results confirmed that the different biocontrol agents could effectively control FWB. In particular, CM significantly reduced the incidence of the disease and showed a field control efficiency of 60.53%. In terms of bacterial community, there were no significant differences in the richness and diversity of banana rooted soil bacteria among the different treatments at either growth stage, but their relative abundances differed substantially. CM treatment significantly increased the ratios of Bacillus, Bryobacter, Pseudomonas, Jatrophihabitans, Hathewaya, and Chujaibacter in the vigorous growth stage and Jatrophihabitans, Occallatibacter, Cupriavidus, and 1921-3 in the fruit development stage. Furthermore, bacterial community function in the banana rooted soil was affected differently by the various biocontrol agents. CM application increased the relative abundance of multiple soil bacterial functions, including carbohydrate metabolism, xenobiotic biodegradation and metabolism, terpenoid and polyketide metabolism, lipid metabolism, and metabolism of other amino acids. In summary, our results suggest that the tested biocontrol agents can effectively inhibit the occurrence of banana Fusarium wilt and alter the soil bacterial community in the field. They mainly modified the relative abundance of bacterial taxa and the metabolic functions rather than the richness and diversity. These findings provide a scientific basis for the use of biocontrol agents to control banana Fusarium wilt under field conditions, which serves as a reference for the study of the soil microbiological mechanisms of other biocontrol agents.
The Fungal Community Structure Regulates Elevational Variations in Soil Organic Carbon Fractions in a Wugong Mountain Meadow
Authors: Wang Jinping , Yuan Jihong , Ren Qiong , Zhou Liyin , Zeng Huanhuan , Miao Lujun , Sun Zhiyong , Wan Fang , Yan Yuanying
Published: November 2024

Soil organic carbon (SOC) fractions are vital intrinsic indicators of SOC stability, and soil fungi are the key drivers of soil carbon cycling. However, variations in SOC fractions along an elevational gradient in mountain meadows and the role of the fungal community in regulating these variations are largely unknown, especially in subtropical areas. In this study, an elevation gradient experiment (with experimental sites at 1500, 1700, and 1900 m) was set up in a Miscanthus sinensis community in a meadow on Wugong Mountain, Southeast China, to clarify the effects of elevation on soil fungal community composition, microbial residue carbon, and SOC fractions. The results showed that the contribution of soil microbial residue carbon to SOC was only 16.1%, and the contribution of soil fungal residue carbon to SOC (15.3%) was far greater than that of bacterial residue carbon (0.3%). An increase in elevation changed the fungal community structure and diversity, especially in the topsoil (0–20 cm depth) compared with that in the subsoil (20–40 cm depth), but did not affect fungal residue carbon in the two soil layers. When separating SOC into the fractions mineral-associated organic carbon (MAOC) and particulate organic carbon (POC), we found that the contribution of MAOC (66.6%) to SOC was significantly higher than that of POC (20.6%). Although an increased elevation did not affect the SOC concentration, it significantly changed the SOC fractions in the topsoil and subsoil. The soil POC concentration and its contribution to SOC increased with an increasing elevation, whereas soil MAOC showed the opposite response. The elevational variations in SOC fractions and the POC/MAOC ratio were co-regulated by the fungal community structure and total nitrogen. Our results suggested that SOC stabilization in mountain meadows decreases with an increasing elevation and is driven by the fungal community structure, providing scientific guidance for SOC sequestration and stability in mountain meadows in subtropical areas.
Mandatory Disclosure of Negative Events and Auditor Behavior: Evidence from a Natural Experiment
Authors: Guo Xiaoli , Fluharty Andrew
Published: November 2024

Using the staggered adoption of data breach disclosure (DBD) laws, this paper studies the impact of mandatory disclosure of adverse corporate events on audit fees. DBD laws increase the frequency of disclosed cyber incidents, which adversely impacts firms’ financial condition and operations; this could result in a higher risk of misstatement and reputation loss for auditors. Consistent with this hypothesis, we find that auditors charge higher fees after the adoption of DBD laws. We also find that the increase in audit fees is more pronounced in firms with higher cyber risk and greater auditor reputational concerns. Furthermore, governance mechanisms and resources that are available to auditors can mitigate the rise in audit fees. Robustness tests suggest that the effect is not driven by realized cyber incidents and other contemporaneous events. Overall, our study provides evidence that the mandated disclosure regulation significantly affects audit pricing.
Comprehensive Assessment of Carbon Disulfide Exposure in Laboratories—Air and Biological Monitoring Approaches
Authors: Hu Jimmy
Published: November 2024

Carbon disulfide (CS2) is a highly toxic and flammable solvent extensively used in chemical processes and laboratory analyses. This review examines both air and biological monitoring methods for assessing the exposure of laboratory workers to CS2. Emphasis is placed on the measurement of airborne CS2 concentrations and the monitoring of 2-thiothiazolidine-4-carboxylic acid (TTCA) in urine, a key biomarker of exposure. By analysing case studies and practical applications, the paper outlines the effectiveness and limitations of current monitoring techniques. Additionally, the review addresses key challenges such as CS2 volatility, dietary influence on biomarker levels, and the sufficiency of protective measures, including nitrile gloves. It also proposes best practices to mitigate exposure, such as improved ventilation, the use of polyvinyl alcohol gloves, and the substitution of CS2 with less hazardous solvents. This comprehensive review underscores the need for continuous vigilance in managing chemical exposure and offers insights into how laboratories can better protect their workers by integrating air and biological monitoring strategies.
Determinants of Food Security Under Different Land Use Systems: Example of Pastoralists and Agro-Pastoralists in Northeastern Ethiopia
Authors: Abaynew Habtamu , Haji Jema , Ahmed Beyan , Verner Vladimir
Published: November 2024

The issue of ensuring food and nutrition security has become a prominent item on the global agenda, particularly for low-income countries with high population growth rates. Despite the implementation of numerous policies and programs with the objective of enhancing household calorie intake, food insecurity is worsening in Ethiopia. It is crucial to comprehend the principal factors influencing food security, as this knowledge is essential for implementing effective interventions to enhance food security. Therefore, this study aimed to estimate the food security status of households, measure the extent and severity of food insecurity, and identify the determinants of food security in Northeastern Ethiopia. The data for this study were collected through key informant interviews, focus group discussions, and a multi-stage sampling method, which involved the selection of 300 households. Descriptive and inferential statistics, the Foster–Greer–Thorbecke (FGT) index, and a probit model were employed to analyze the collected data. The results indicate that 41.67% of the sample households were food secure. By decomposing the results to the two land use systems, 34.62% and 50.69% of the pastoral and agro-pastoral households were food secure, respectively, indicating that agro-pastoral households were relatively more food secure than pastoral counterparts. Furthermore, the gap and severity of food insecurity among the sample households were calculated using FGT indices, resulting in a value of 15.02% and 5.31%, respectively. The probit model revealed that educational attainment, the number of milking cows, cultivated farm size, annual farm income, and participation in off-farm activities were significant predictors of improved household food security status. The findings of this study suggest that policies aimed at addressing food insecurity should consider livelihood diversification, the promotion of education and training, and the strengthening of institutional and technological environments.
Minute Ventilation/Carbon Dioxide Production Slope Could Predict Short- and Long-Term Prognosis of Patients After Acute Decompensated Heart Failure
Authors: Tuan Sheng-Hui , Huang I-Ching , Huang Wei-Chun , Chen Guan-Bo , Sun Shu-Fen , Lin Ko-Long
Published: November 2024

(1) Background: Heart failure (HF) leads to functional disability and major cardiovascular events (MACEs). Cardiopulmonary exercise testing (CPET) is the gold standard for assessing aerobic capacity and prognostic stratification. This study aimed to evaluate the predischarge CPET variables in patients with acute decompensated HF and identify the submaximal CPET variables with prognostic value. (2) Methods: A retrospective cohort study was conducted at a tertiary center in Taiwan. Patients surviving their first episode of decompensated HF and undergoing predischarge CPET (February 2017 to January 2023) were analyzed. Follow-up was conducted until a MACE or administrative censoring (up to 5 years). Cox regression identified the significant predictors of MACE. (3) Results: The study included 553, 485, and 267 patients at the 3-month, 1-year, and 5-year follow-ups, respectively. MACE rates were 15.0%, 34.2%, and 50.9%. The VE/VCO2 slope was a significant predictor of MACE at all intervals. A VE/VCO2 slope >38.95 increased the risk of MACE by 2.49-fold at 3 months and 1.81-fold at 1 year (both p < 0.001). A slope > 37.35 increased the 5-year MACE risk by 1.75-fold (p = 0.002). (4) Conclusions: The VE/VCO2 slope is a significant submaximal CPET predictor of MACE in patients post-acute decompensated HF for both short- and long-term outcomes.
Characteristics, Relationships, and Differences in Muscle Activity and Impact Load Attenuation During Tennis Forehand Stroke with Different Grips
Authors: Dong Rui , Su Xinyu , Li Shichen , Ni Xindi , Liu Ye
Published: November 2024

In forehand strokes with different grips in tennis, the forearm muscle activities, the distribution and attenuation of the impact loads, and the effects of the muscles on the impact load attenuation exhibited different characteristics. This study aimed to explore these characteristics by analyzing electromyography (EMG) and acceleration data, and comparing the differences between the Eastern and Western grips. Fourteen level II or above tennis players (ten males, aged 22.4 ± 3.6 years; four females, aged 19.8 ± 2.0 years) were recruited and instructed to perform forehand strokes using the Eastern and Western grips, respectively. The EMG of eight forearm muscles and the acceleration data at the ulnar and radial sides of the wrist and elbow were collected. The root mean square (RMS), the peaks of the impact load, the amplitude of impact load attenuation (AC), and the jerk value (Jerk) were calculated. The cross-correlation coefficients and time delays of EMG–EMG, EMG–AC, and EMG–jerk were obtained using the cross-correlation method. The results showed that in the Eastern grip group (group E), the RMS of the flexor carpi ulnaris (FCU) was significantly greater than that in the Western grip group (group W). In group E, the peaks of impact load, AC, and Jerk on the Y axis of the wrist ulnar side were all significantly higher than those in group W. The activity of the extensor digitorum commonis (EDC) had significantly different effects on the amplitude and rate of impact load attenuation at specific locations in different grips, especially at the elbow (p < 0.05). The conclusion indicated that the FCU exhibited higher levels of EMG activity in the Eastern grip. This grip responded to greater impact loads with more substantial and rapid attenuation on the wrist ulnar side. Furthermore, the EDC appeared to contribute more to the amplitude of impact load attenuation in the Western grip and to have a more significant influence on the rate of impact load attenuation in the Eastern grip, especially at the elbow. These results suggest that tennis players and coaches should pay more attention to improving the strength of the EDC and FCU, which can improve sports performance and comfort, as well as prevent sports injuries.
Associations Between Sprint Mechanical Properties and Change of Direction Ability and Asymmetries in COD Speed Performance in Basketball and Volleyball Players
Authors: Zhang Zhihao , Jiang Mingchen , Jing Yifan , Li Mingjia , Li Yanchun , Yang Xiaolin
Published: November 2024

This study aimed to assess the associations between sprint force–velocity profile variables with change of direction (COD) performance and to investigate the impact of these variables on asymmetries in COD speed performance. Ninety-nine participants (volleyball players: n = 44, basketball players: n = 55) performed 40 m sprints for Fv relationship calculation, two COD tests (Modified Agility T-test and 505 test). A partial least squares (PLS) regression analysis was conducted to determine the relationships between the variables. The V0 was the most influential variable; it was negatively associated with COD performance variables (β = −0.260, −0.263 and −0.244 for MAT, 505-D and 505-ND, respectively), and F0 (β = 0.169, 0.163) was associated with the COD performance variables (COD deficit D and COD deficit ND, respectively), slightly larger than the effects of Fvslope (β = −0.162, −0.146), DRF (β = −0.159, −0.142) and Pmax (β = −0.162, −0.146). For COD deficit imbalance, the DRF (β = −0.070) was the most influential variable followed by Fvslope (β = −0.068), F0 (β = 0.046) and gender (β = 0.031). V0 and RFmax were the critical variables for improving COD performance that includes linear sprints, while DRF, Fvslope, F0 and Pmax collectively influence 180° COD performance. Meanwhile, DRF and Fvslope were important factors for asymmetries in COD speed performance. It is recommended to use the Fv profile to diagnose different COD movement patterns and then develop training plans accordingly for team sports played on smaller courts, such as basketball and volleyball.
Fibrillated Films for Suspension Catalyst Immobilization—A Kinetic Study of the Nitrobenzene Hydrogenation
Authors: Boscagli Chiara , Lepre Enrico , Hofmann Oliver , Wengeler Lukas , Schmitt Marcel , Jevtovikj Ivana , Lizandara-Pueyo Carlos , Schunk Stephan A.
Published: November 2024

The immobilization of suspension catalysts in flexible, fibrillated films offers a promising solution to the mass transfer limitations often encountered in three-phase hydrogenation reactions. This study investigates the catalytic performance and mass transfer properties of fibrillated films in the hydrogenation of nitrobenzene to aniline, comparing them to free-flowing powdered catalysts. Fibrillated films were prepared from Pd/C catalysts with varying thicknesses (100–400 µm), and their performance was evaluated through kinetic studies in both batch reactors and microreactors. The specific activity of the films was significantly influenced by film thickness with thinner films demonstrating lower mass transfer limitations. However, mass transfer limitations were observed in thicker films, prompting the development of alternative film designs, including enhanced macro-porous films and sandwich structures. These modifications successfully minimized diffusion limitations, achieving similar specific activity to the powder catalysts while maintaining the mechanical stability of the films. This work demonstrates the feasibility of using fibrillated films for continuous catalytic processes and highlights their potential for efficient catalyst reuse, avoiding filtration steps and enhancing process sustainability. Furthermore, while PTFE remains indispensable for producing such films due to its mechanical and thermal stability, ongoing research focuses on identifying more environmentally friendly alternatives without compromising performance.
Analysis of Mechanical Properties and Thermal Conductivity of Thin-Ply Laminates in Ambient and Cryogenic Conditions
Authors: Krzak Anna , Nowak Agnieszka J. , Frolec Jiří , Králík Tomáš , Kotyk Maciej , Boroński Dariusz , Matula Grzegorz
Published: November 2024

It is widely known that glass–epoxy laminates are renowned for their high stiffness, good thermal properties, and economic qualities. For this reason, composite materials find successful applications in various industrial sectors such as aerospace, astronautics, the storage sector, and energy. The aim of this study was to investigate the mechanical and thermal properties of composite materials comprising two different types of epoxy resin and three different hardeners, both at room temperature and under cryogenic conditions. The samples were produced at IZOERG (Gliwice, Poland) using a laboratory hot-hydraulic-press technique. During cyclic loading–unloading tests, degradation up to a strain level of 0.6% was observed both at room temperature (RT) and at 77 K. For a glass-reinforced composite with YDPN resin (EP_1_1), the highest degradation was recorded at 18.84% at RT and 33.63% at 77 K. We have also investigated the temperature dependence of thermal conductivity for all samples in a wide temperature range down to 5 K. The thermal conductivity was found to be low and had a relative difference of up to 20% among the composites. The experimental results indicated that composites under cryogenic conditions exhibited less damage and were stiffer. It was confirmed that the choice of hardener significantly influenced both properties.
An Enhanced Spectral Amplitude Modulation Method for Fault Diagnosis of Rolling Bearings
Authors: Ma Zongcai , Chen Yongqi , Zhang Tao , Liao Ziyang
Published: November 2024

As a classic nonlinear filtering method, Spectral Amplitude Modulation (SAM) is widely used in the field of bearing fault characteristic frequency identification. However, when the vibration signal contains high-intensity noise interference, the accuracy of SAM in identifying fault characteristic frequencies is greatly reduced. To solve the above problems, a Data Enhancement Spectral Amplitude Modulation (DA-SAM) method is proposed. This method further processes the modified signal through improved wavelet transform (IWT), calculates its logarithmic maximum square envelope spectrum to replace the original square envelope spectrum, and finally completes SAM. By highlighting signal characteristics and strengthening feature information, interference information can be minimized, thereby improving the robustness of the SAM method. In this paper, this method is verified through fault data sets. The research results show that this method can effectively reduce the interference of noise on fault diagnosis, and the fault characteristic information obtained is clearer. The superiority of this method compared with the SAM method, Autogram method, and fast spectral kurtosis diagram method is proved.
Design and Performance of a Planetary Gearbox with Two DOFs
Authors: Tulekenova Dana , Ceccarelli Marco , Ivanov Konstantin , Russo Matteo
Published: November 2024

The article aims to describe the design and operation of a fundamentally new self-regulating planetary transmission, which, without a control system, changes the gear ratio under the influence of a variable external load. A self-regulating transmission can be created based on a kinematic chain with two degrees of freedom, having only one input. According to the laws of mechanics, such a chain has no definability of motion, since the number of inputs must be equal to the number of degrees of freedom. The equilibrium of a two-movable chain with one input can obtained by creating an additional constraint that substitutes a reaction in the instantaneous center of the intermediate link velocities by the friction moment in the hinge of the intermediate link. The friction moment creates a force constraint, which is taken into account in the equilibrium condition. The obtained equilibrium conditions ensure the definiteness of motion and the ability of self-regulation in the form of an inversely proportional dependence of the speed of the output link on the variable external load. The described method makes it possible to create a fundamentally new class of self-regulating mechanisms in all branches of technology. The interaction of kinematic and force parameters and the construction of parameter graphs was performed using the SolidWorks 2021 program with certain additions. The experimental studies performed confirm the reliability of the theoretical developments.
Research on Pose Error Modeling and Compensation of Posture Adjustment Mechanism Based on WOA-RBF Neural Network
Authors: Shen Hongyu , Zhou Honggen , Jin Yiyang , Li Lei , Deng Bo , Xu Jiawei
Published: November 2024

This paper is aimed to address the issue of decreased accuracy in the ship block docking caused by the structural errors of posture adjustment mechanism. First, inverse kinematic analysis is performed to investigate the sources of static errors in the mechanism. Subsequently, based on the closed-loop vector method, a pose error model for the moving platform is established, which includes eight categories of error terms. The impact of various structural errors on the pose accuracy of the moving platform is then compared and analyzed under both single-limb and multi-limb configurations. Therefore, a compensation method based on the whale optimization algorithm optimized radial basis function neural network is proposed. By transforming pose errors into actuator length errors, it establishes a predictive model between the theoretical pose of the dynamic platform and actuator length errors. After optimizing the network parameters, it yields the actuator length compensation to correct the actual pose of the dynamic platform. Simulation and experimental results validate the effectiveness of this method in enhancing the motion accuracy of the parallel mechanism. The mean pose accuracy of the moving platform is improved by 85.07%, demonstrating a significant compensation effect.
Polysaccharides and Composite Adsorbents in the Spotlight for Effective Agrochemical Residue Removal from Water
Authors: Ortiz-Martínez Mónica , Restori-Corona Brenda , Hernández-García Luis , Alonso-Segura Diana
Published: November 2024

Agrochemical residues, including pesticides and herbicides, pose significant environmental and health risks when present in water sources. Conventional water treatment methods often fall short in effectively removing these persistent pollutants, necessitating innovative solutions. This review explores the use of polysaccharides and composite adsorbents as sustainable alternatives for agrochemical residue removal from water. Biopolymers such as chitosan, alginate, and cellulose are highlighted for their biodegradability, biocompatibility, and ability to be functionalized for enhanced adsorption performance. Recent advances in the development of composite materials incorporating nanomaterials, such as graphene, oxide, and metal oxides, have shown significant promise in enhancing the efficiency and selectivity of agrochemical adsorption. The review also addresses the fundamental mechanism of adsorption, such as electrostatic interactions, hydrogen bonding, and hydrophobic forces, that contribute to the effectiveness of these materials. Challenges associated with scalability, regeneration, and real-world applications are discussed, as well as future opportunities for integrating emerging technologies like 3D printing and machine learning into adsorbent design. Overall, polysaccharides and composites offer a promising pathway toward achieving efficient and sustainable agrochemical residue removal, with ongoing research needed to overcome current limitations and optimize their practical application in water treatment.
Adaptive AI Alignment: Established Resources for Aligning Machine Learning with Human Intentions and Values in Changing Environments
Authors: Fox Stephen
Published: November 2024

AI Alignment is a term used to summarize the aim of making artificial intelligence (AI) systems behave in line with human intentions and values. There has been little consideration in previous AI Alignment studies of the need for AI Alignment to be adaptive in order to contribute to the survival of human organizations in changing environments. This research gap is addressed here by defining human intentions and values in terms of survival biophysics: entropy, complexity, and adaptive behavior. Furthermore, although technology alignment has been a focus of studies for more than thirty years, there has been little consideration in AI Alignment studies of established resources for aligning technologies. Unlike the current focus of AI Alignment on addressing potential AI risks, technology alignment is generally focused on aligning with opportunities. Established resources include the critical realist philosophy of science, scientific theories, total quality management practices, technology alignment methods, engineering techniques, and technology standards. Here, these established resources are related to the alignment of different types of machine learning with different levels of human organizations. In addition, established resources are related to a well-known hypothetical extreme example of AI Misalignment, and to major constructs in the AI Alignment literature. Overall, it is argued that AI Alignment needs to be adaptive in order for human organizations to be able to survive in changing environments, and that established resources can facilitate Adaptive AI Alignment which addresses risks while focusing on opportunities.
Non-Stationary Fractal Functions on the Sierpiński Gasket
Authors: Kumar Anuj , Boulaaras Salah , Verma Shubham Kumar , Biomy Mohamed
Published: November 2024

Following the work on non-stationary fractal interpolation (Mathematics 7, 666 (2019)), we study non-stationary or statistically self-similar fractal interpolation on the Sierpiński gasket (SG). This article provides an upper bound of box dimension of the proposed interpolants in certain spaces under suitable assumption on the corresponding Iterated Function System. Along the way, we also prove that the proposed non-stationary fractal interpolation functions have finite energy.
Mechanical and Civil Engineering Optimization with a Very Simple Hybrid Grey Wolf—JAYA Metaheuristic Optimizer
Authors: Furio Chiara , Lamberti Luciano , Pruncu Catalin I.
Published: November 2024

Metaheuristic algorithms (MAs) now are the standard in engineering optimization. Progress in computing power has favored the development of new MAs and improved versions of existing methods and hybrid MAs. However, most MAs (especially hybrid algorithms) have very complicated formulations. The present study demonstrated that it is possible to build a very simple hybrid metaheuristic algorithm combining basic versions of classical MAs, and including very simple modifications in the optimization formulation to maximize computational efficiency. The very simple hybrid metaheuristic algorithm (SHGWJA) developed here combines two classical optimization methods, namely the grey wolf optimizer (GWO) and JAYA, that are widely used in engineering problems and continue to attract the attention of the scientific community. SHGWJA overcame the limitations of GWO and JAYA in the exploitation phase using simple elitist strategies. The proposed SHGWJA was tested very successfully in seven “real-world” engineering optimization problems taken from various fields, such as civil engineering, aeronautical engineering, mechanical engineering (included in the CEC 2020 test suite on real-world constrained optimization problems) and robotics; these problems include up to 14 optimization variables and 721 nonlinear constraints. Two representative mathematical optimization problems (i.e., Rosenbrock and Rastrigin functions) including up to 1000 variables were also solved. Remarkably, SHGWJA always outperformed or was very competitive with other state-of-the-art MAs, including CEC competition winners and high-performance methods in all test cases. In fact, SHGWJA always found the global optimum or a best cost at most 0.0121% larger than the target optimum. Furthermore, SHGWJA was very robust: (i) in most cases, SHGWJA obtained a 0 or near-0 standard deviation and all optimization runs practically converged to the target optimum solution; (ii) standard deviation on optimized cost was at most 0.0876% of the best design; (iii) the standard deviation on function evaluations was at most 35% of the average computational cost. Last, SHGWJA always ranked 1st or 2nd for average computational speed and its fastest optimization runs outperformed or were highly competitive with their counterpart recorded for the best MAs.
Stability of Cauchy–Stieltjes Kernel Families by Free and Boolean Convolutions Product
Authors: Alanzi Ayed. R. A. , Alshqaq Shokrya S. , Fakhfakh Raouf
Published: November 2024

Let F(νj)={Qmjνj,mj∈(m−νj,m+νj)}, j=1,2, be two Cauchy–Stieltjes Kernel (CSK) families induced by non-degenerate compactly supported probability measures ν1 and ν2. Introduce the set of measures F=F(ν1)⊞F(ν2)={Qm1ν1⊞Qm2ν2,m1∈(m−ν1,m+ν1)andm2∈(m−ν2,m+ν2)}. We show that if F remains a CSK family, (i.e., F=F(μ) where μ is a non-degenerate compactly supported measure), then the measures μ, ν1 and ν2 are of the Marchenko–Pastur type measure up to affinity. A similar conclusion is obtained if we substitute (in the definition of F) the additive free convolution ⊞ by the additive Boolean convolution ⊎. The cases where the additive free convolution ⊞ is replaced (in the definition of F) by the multiplicative free convolution ⊠ or the multiplicative Boolean convolution ⨃ are also studied.
A New Extragradient-Viscosity Method for a Variational Inequality, an Equilibrium Problem, and a Fixed Point Problem
Authors: Yazdi Maryam , Hashemi Sababe Saeed
Published: November 2024

In this research article, we introduce a novel iterative approach that builds upon a two-step extragradient-viscosity method. This method aims to find a common element among the solution set of a variational inequality, an equilibrium problem, and the set of common fixed points from a countable family of demicontractive mappings in a Hilbert space. We offer a robust convergence theorem for the proposed iterative scheme, considering certain well-conditioned parameters. Our findings represent an improvement over similar results already available in the existing literature. Furthermore, we demonstrate the applicability of our main result to W-mappings. Lastly, we present two numerical examples to exhibit the consistency and accuracy of our devised scheme.
A High-Dimensional Cramér–von Mises Test
Authors: Zhang Danna , Xu Mengyu
Published: November 2024

The Cramér–von Mises test provides a useful criterion for assessing goodness of fit in various problems. In this paper, we introduce a novel Cramér–von Mises-type test for testing distributions of high-dimensional continuous data. We establish an asymptotic theory for the proposed test statistics based on quadratic functions in high-dimensional stochastic processes. To estimate the limiting distribution of the test statistic, we propose two practical approaches: a plug-in calibration method and a subsampling method. Theoretical justifications are provided for both techniques. Numerical simulation also confirms the convergence of the proposed methods.
Nannochloropsis oceanica as a Source of Bioactive Compounds: Mapping the Effects of Cultivation Conditions on Biomass Productivity and Composition Using Response Surface Methodology
Authors: Gundersen Emil , Jakobsen Jette , Holdt Susan Løvstad , Jacobsen Charlotte
Published: November 2024

Microalga Nannochloropsis oceanica presents a promising source of high-value food ingredients such as protein, omega-3 fatty acids, and vitamins. To fully unlock its potential, a thorough understanding of how cultivation conditions affect both growth and the nutritional composition is required. Hence, this study aimed to test and model the effects of temperature, light intensity, and salinity on biomass productivity and the final contents of protein, eicosapentaenoic acid (EPA), and vitamin K2 using response surface methodology (RSM). The RSM experiment revealed that the highest temperature and light intensity tested favored biomass productivity and protein content. According to the generated models, the two responses peaked with 0.135 g DM·L−1·day−1 and 0.559 g·g−1 DM, respectively, at 27 °C and 300–350 µmol·m−2·s−1. In contrast, the contents of both EPA and menaquinone-4 (MK-4), the only detected K vitamer, were stimulated at the lowest tested temperature. Based on the generated models, the two responses peaked with 0.037 g·g−1 DM and 89.3 µg·g−1 DM, respectively, at 19 °C combined with 3.0% salinity (EPA) or 120 µmol·m−2·s−1 (MK-4). Although additional optima may exist beyond the tested conditions, these findings provide valuable information on N. oceanica’s cellular response to changes in key cultivation conditions. Furthermore, it shows that two-stage cultivation may be needed to fully unlock the potential of this microalga as a future source of valuable lipid ingredients.