bluuebunny/crossref_metadata_2025 huggingface dataset:
Considerations on the Effect of Slow-Steaming to Reduce Carbon Dioxide Emissions from Ships
Authors: Glujić Darko , Kralj Predrag , Dujmović Josip
Published: September 2022

Carbon dioxide emissions have become a growing problem worldwide. Global institutions are addressing this problem and developing solutions. Countries that are aware of this problem are implementing regulations that affect global industry and, in particular, maritime transport. Considering that the combustion process, namely, diesel, remains the main energy conversion process on board ships, the question arises: what is the best solution to reduce pollutant emissions? Coastal countries have taken various measures to reduce the emission of harmful gases into the marine environment. The problem with these measures is that it is difficult to accurately predict their impact. This paper looks at one of these measures (slow-steaming) to determine how it affects carbon dioxide emissions from different types of ships and their modes of operation. Engine room simulators were used to study two marine power plants under different operating conditions. Fuel consumption was measured, i.e., flows from heavy fuel oil and diesel oil service tanks to all consumers, and carbon emissions were calculated accordingly. The study showed a large reduction in carbon dioxide emissions in the case of a modern power plant ship, and large deviations when all operating modes were compared.
Effect of Saturation on Shear Behavior and Particle Breakage of Coral Sand
Authors: Chen Xiang , Shen Jianhua , Wang Xing , Yao Ting , Xu Dongsheng
Published: September 2022

Coral sand is the main filling material for the island–reef foundation. Under tidal actions, the saturation (Sr) of coral sand layers varies with the specific depths in the reclaimed foundation. Studying the Sr effect of coral sand’s mechanical behaviors is crucial for the stability of the reclaimed foundation of island–reefs. In this study, a “quantitative injection method” was designed to prepare coral sand with saturation ranging from 90% to 100%, and unconsolidated–undrained (UU) triaxial shear tests were conducted on coral sand under different effective confining pressures (σ3′). The results indicated that the stress–strain curves of coral sand under various conditions were of the strain-softening type. When σ3′ = 200, 400, 600, and 800 kPa, the shear strength of coral sand decreased exponentially by 13.1, 9.1, 16.8, and 15.2%, respectively, with the increase in Sr from 90% to 100%. As Sr rose, the internal friction angle (φ) dropped by 3.77°. The cohesion (c) was not significantly affected by Sr compared to φ. In consideration of the physical susceptibility of coral sand to breakage, relative breakage ratio (Br) and modified relative breakage index (Br*) were introduced to evaluate the particle breakage behaviors of coral sand samples with different Sr levels in the triaxial shear process. It was found that Br and Br* increase linearly with increasing Sr; the effect of Sr on the particle breakage of coral sand weakens significantly when σ3′ is sufficiently large. The median particle size (d50) of coral sand decreases with increasing Sr, and presents a negative linear correlation with both Br and Br*. Based on comparing the strength and particle breakage characteristics of coral sand samples with varying Sr levels, this study suggests that 92.5% should be considered as the Sr value of coral sand available for testing.
Investigation of Energy Losses Induced by Non-Uniform Inflow in a Coastal Axial-Flow Pump
Authors: Meng Fan , Li Yanjun , Chen Jia
Published: September 2022

A non-uniform velocity profile occurs at the inlet of a coastal axial-flow pump which is placed downstream of the forebay with side-intake. As a result, the actual efficiency and head of the pump is dissimilar to the design parameters, and the lack of the theoretical investigation on the relationship between inflow distortion and energy losses restricts the application of the coastal axial-flow pump in the drainage project. In this paper, the unsteady numerical simulation and entropy production theory are employed to obtain the internal flow structure and quantify energy losses, respectively, with three inflow deflection angles (θ = 0°, 15°, or 30°). It is reported that the best efficiency point (BEP) shifts to large flow rate with θ increasing, due to the decline of the velocity component in axial direction at the impeller inlet. Therefore, the total entropy production (TEP) of the coastal axial-flow pump rises with θ increasing under small flow rates, but it decreases with θ increasing under large flow rates. The high total entropy production rate (TEPR) in the vicinity of the tailing edge of the impeller and guide vanes rises with θ increasing, caused by the enhanced wake vortex strength. In addition, the high TEPR area near the inlet of outflow conduit rises with θ increasing, originated from the improvement of secondary vortices intensity.
Identification of Orbital Angular Momentum by Support Vector Machine in Ocean Turbulence
Authors: Li Xiaoji , Huang Jiemei , Sun Leiming
Published: September 2022

With the advancement of underwater communication technology, the traditional modulation dimension has been introduced, developed and utilized. In addition, orbital angular momentum (OAM) is utilized as the modulation dimension for optical underwater communication to obtain larger spectrum resources. The OAM features are extracted using a histogram of oriented gradient and trained using the support vector machine method with a gradient direction histogram feature. The topological charge value of the OAM was used to identify the classification labels, and the ocean turbulence caused by different temperatures and salinity were analyzed. Experimentation results showed that the recognition accuracy for the OAM under the Laguerre–Gaussian beam rates of 1~5, 1~6, 1~7, 1~8, 1~9, and 1~10 was 98.93%, 98.89%, 97.33%, 96.66%, 95.40%, and 95.33%, respectively. The proposed method achieved a high recognition accuracy and performed efficiently under strong turbulence. Our research explored a new technique that provides a new idea for the demodulation of OAM in optical underwater communication.
The Adaptor Protein UvSte50 Governs Fungal Pathogenicity of Ustilaginoidea virens via the MAPK Signaling Pathway
Authors: Cao Huijuan , Gong Hao , Song Tianqiao , Yu Mina , Pan Xiayan , Yu Junjie , Qi Zhongqiang , Du Yan , Liu Yongfeng
Published: September 2022

The mitogen-activated protein kinase (MAPK) signaling pathways regulate diverse cellular processes and have been partially characterized in the rice false smut fungus Ustilaginoidea virens. UvSte50 has been identified as a homolog to Saccharomyces cerevisiae Ste50, which is known to be an adaptor protein for MAPK cascades. ΔUvste50 was found to be defective in conidiation, sensitive to hyperosmotic and oxidative stresses, and non-pathogenic. The mycelial expansion of ΔUvste50 inside spikelets of rice terminated at stamen filaments, eventually resulting in a lack of formation of false smut balls on spikelets. We determined that UvSte50 directly interacts with both UvSte7 (MAPK kinase; MEK) and UvSte11 (MAPK kinase kinase; MEKK), where the Ras-association (RA) domain of UvSte50 is indispensable for its interaction with UvSte7. UvSte50 also interacts with UvHog1, a MAP kinase of the Hog1-MAPK pathway, which is known to have important roles in hyphal growth and stress responses in U. virens. In addition, affinity capture–mass spectrometry analysis and yeast two-hybrid assay were conducted, through which we identified the interactions of UvSte50 with UvRas2, UvAc1 (adenylate cyclase), and UvCap1 (cyclase-associated protein), key components of the Ras/cAMP signaling pathway in U. virens. Together, UvSte50 functions as an adaptor protein interacting with multiple components of the MAPK and Ras/cAMP signaling pathways, thus playing critical role in plant infection by U. virens.
Classification of Shrinking Cities in China Based on Self-Organizing Feature Map
Authors: Wang Xinyi , Li Zihan , Feng Zhe
Published: September 2022

Since the 1980s, China has been experiencing shrinking cities as part of a massive urbanization process. In recent years, the Matthew effect of factor accumulation has led to an increasingly substantial divergence in population concentration and sparseness in China. The pattern of shrinking Chinese cities has become increasingly severe. Accurate classification of shrinking cities is important for formulating policies and achieving the rational development of shrinking cities. In this study, the data of the 6th and 7th population censuses are used to investigate the shrinking Chinese cities, and prefecture-level cities are utilized as the scale of administrative units. The resident population in 130 cities decreased during the last decade. The population, economy, society, and space indicators are selected to cluster the shrinking cities through the self-organizing feature map neural network. Results show that China’s shrinking cities can be divided into four categories: (1) Sixty-two cities are characterized by a high degree of transfer dependence on the economy due to a chronic lack of population. (2) Twenty-eight cities are characterized by high urban expansion but with population loss. (3) Fourteen cities are characterized by obvious transportation and location advantages and with relatively slight population loss. (4) Twenty-six cities have good industrial development prospects but with serious urban pollution and “siphoning” effects from other cities. The shrinking cities are mainly concentrated in the western, central, and northeastern regions of China, which are represented by the old industrial and resource-depleted cities. The shrinking cities in the eastern region are fewer and less severe, which is mainly related to the high population concentration and developed economy in the region. This study provides solutions from different perspectives for four types of shrinking cities and serves as an empirical reference for policymakers and urban planners.
Study on the Coupling and Coordination Relationship between Gross Ecosystem Product (GEP) and Regional Economic System: A Case Study of Jiangxi Province
Authors: Xie Hualin , Li Zhe , Xu Yu
Published: September 2022

The Gross Ecosystem Product (GEP) is an important way to assess the state of the ecosystem and to clarify the coupling and coordination between the ecosystem and the economic system, which can be a scientific basis for achieving the synergistic development of economic society and ecological civilization. In this paper, 11 prefectural cities in Jiangxi Province are taken as research areas. Based on the data of land use, normalized difference vegetation index, net primary productivity, soil, meteorology, elevation and statistics, the study accounts for the GEP in Jiangxi Province in 2010 and 2020 based on a biophysical model, and analyzes the changes of its ecosystem’s state. Based on the economic data obtained from the Jiangxi Statistical Yearbook, a regional economic index system was established; the levels of GEP and the regional economy were measured with the help of entropy-weight-TOPSIS method, and the interaction mechanism and coupling coordination dynamics between them were explored based on the coupling coordination degree model. It was found that during 2010–2020, the GEP in Jiangxi Province increased by 0.35%, and the value of material goods and cultural services increased by 49.57% and 414.03%, respectively, but the value of regulating services decreased by 9.89%; the main coupled and coordinated development characteristics of ecosystem and economic system in Jiangxi Province developed from basic coordination-economic lagging to moderate coordination-ecological lagging, and the coupled coordinated development continues to improve, but the development of gross ecosystem product lags behind the level of economic development.
Endogenous Land Supply Policy, Economic Fluctuations and Social Welfare Analysis in China
Authors: He Yiyao
Published: September 2022

Motivated by the observation that land supplied by the Chinese government is highly counter-cyclical with GDP fluctuations, this paper constructs a DSGE model to study the relationship between China’s land supply policy and economic fluctuations, and further evaluate the welfare effects. By way of counterfactual exercises, this paper finds that endogenous land supply policy has “direct effect (production input channel)” and “indirect effect (intermediate goods channel)” on GDP fluctuations, and both tend to dampen economic fluctuations in China’s macroeconomy. Specifically, GDP fluctuations increase by 63.35% without the “indirect effect”, increase by 66.75% without the “direct effect”, and increase by 66.79% without both effects. In addition, endogenous land supply policy can increase social welfare by about 1.38%. Verifying by the stylized facts in China, this paper argues that endogenous land supply is an efficient macro-control policy to smooth the economy and increase social welfare.
A Dynamic Evaluation of Ecosystem Services Value in the Beijing–Tianjin–Hebei Region Based on Scarcity Modification of Spatiotemporal Supply–Demand Influence
Authors: Tang Xiumei , Liu Yu , Ren Yanmin , Feng Huiyi
Published: September 2022

It is of great significance to study the spatiotemporal differences between supply and demand of regional ecosystem services (ES) and evaluate the dynamic impact of changes in supply and demand on the ecosystem services value (ESV) so as to provide scientific guidance for human activities and maintain healthy ecosystem development. This study proposes a novel method to calculate the scarcity value of ecosystem service (SESV) as a function of the temporal and spatial changes in supply and demand to divided ecological zones with differentiated land-use strategies. Then, it explores the changes in ESV and SESV in the Beijing–Tianjin–Hebei (BTH) region from 2000 to 2015. Firstly, the native ecosystem services value (NESV) and demand of ES in the BTH region were evaluated. Secondly, the spatiotemporal influence mechanism of supply and demand on ESV was analyzed according to the equilibrium price principle of supply and demand in economics, and a model for evaluating the SESV was constructed on the basis of supply and demand. Lastly, the ecological zoning method was proposed for of the BTH region. Result shows that the NESV in the BTH region was 2775.54 billion CNY in 2000, and it decreased to 2722.44 billion CNY in 2015. Taking into account the changes in supply and demand, the SESV in 2015 was 2884.85 billion CNY. Secondly, the NESV in 2000 and 2015 and the SESV in 2015 exhibited a gradual downward trend from north to south. Lastly, according to the changes in ecosystem service supply and demand and NESV/SESV in the BTH region, the ecological zones of the BTH region were divided, and differentiated land-use policies were put forward. The research can not only enrich ESV evaluation theories and methods, but also provide a scientific basis for the coordinated development of the BTH region and promote regional ecological civilization construction strategies.
Improving N-Best Rescoring in Under-Resourced Code-Switched Speech Recognition Using Pretraining and Data Augmentation
Authors: Jansen van Vüren Joshua , Niesler Thomas
Published: September 2022

In this study, we present improvements in N-best rescoring of code-switched speech achieved by n-gram augmentation as well as optimised pretraining of long short-term memory (LSTM) language models with larger corpora of out-of-domain monolingual text. Our investigation specifically considers the impact of the way in which multiple monolingual datasets are interleaved prior to being presented as input to a language model. In addition, we consider the application of large pretrained transformer-based architectures, and present the first investigation employing these models in English-Bantu code-switched speech recognition. Our experimental evaluation is performed on an under-resourced corpus of code-switched speech comprising four bilingual code-switched sub-corpora, each containing a Bantu language (isiZulu, isiXhosa, Sesotho, or Setswana) and English. We find in our experiments that, by combining n-gram augmentation with the optimised pretraining strategy, speech recognition errors are reduced for each individual bilingual pair by 3.51% absolute on average over the four corpora. Importantly, we find that even speech recognition at language boundaries improves by 1.14% even though the additional data is monolingual. Utilising the augmented n-grams for lattice generation, we then contrast these improvements with those achieved after fine-tuning pretrained transformer-based models such as distilled GPT-2 and M-BERT. We find that, even though these language models have not been trained on any of our target languages, they can improve speech recognition performance even in zero-shot settings. After fine-tuning on in-domain data, these large architectures offer further improvements, achieving a 4.45% absolute decrease in overall speech recognition errors and a 3.52% improvement over language boundaries. Finally, a combination of the optimised LSTM and fine-tuned BERT models achieves a further gain of 0.47% absolute on average for three of the four language pairs compared to M-BERT. We conclude that the careful optimisation of the pretraining strategy used for neural network language models can offer worthwhile improvements in speech recognition accuracy even at language switches, and that much larger state-of-the-art architectures such as GPT-2 and M-BERT promise even further gains.
High and Low Arguments in Northern and Pontic Greek
Authors: Anagnostopoulou Elena , Mertyris Dionysios , Sevdali Christina
Published: September 2022

This paper deals with the distribution of the use of the accusative as an indirect object in two major dialect groups of Modern Greek, namely Northern Greek and Pontic Greek. The loss of the dative in Medieval Greek (c. 10th c. AD) resulted in the use of the genitive as an indirect object in the southern varieties and of the accusative in Northern Greek and Asia Minor Greek. As Standard Modern Greek employs the genitive, little attention has been paid to the distribution of the accusative, and our study was aimed to fill that gap by presenting data collected in Northern Greece from speakers of both dialect groups. According to our findings, the accusative is exclusively used in all syntactic domains inherited from the Ancient Greek dative in both dialect groups, but the two groups are kept apart in terms of the obligatoriness vs. optionality or lack of clitic doubling and availability vs. lack of “high” positions, e.g., for external possessors and ethical dative constructions.
Thermo-Mechanical Fatigue Crack Growth and Phase Angle Effects in Ti6246
Authors: Palmer Jennie , Jones Jonathan , Whittaker Mark , Williams Steve
Published: September 2022

A bespoke TMF crack growth test set-up has been developed and validated for use throughout this study and the effects of phasing between mechanical loading and temperature have been investigated. The study shows that TMF cycles may show increased crack growth rate behaviour when compared to isothermal fatigue. The phase angle of the applied TMF cycle can also affect crack growth behaviour, with in-phase (IP) test conditions showing faster crack growth rates than out-of-phase (OP) test conditions. Propagating cracks interact with the microstructure of the material, in particular, the α/β interfaces within the prior beta grains and supporting fractography evidences subtle differences in fracture mechanisms as a result of phase angle.
Influence of Hf and MC Carbide on Transverse Platform in Single Crystal Grain Selection of 2D Grain Selector
Authors: Zhu Xintao , Wang Fu , Ma Dexin , Bührig-Polaczek Andreas
Published: September 2022

CM247LC Ni-based components have been widely used in developing hot ends in aero-engines and gas industrial turbines, and these have exhibited promising directional solidification (DS) results. However, the superalloy CM247LC shows defects after adding carbon (C) and hafnium (Hf). In this study, the effects of adding C and Hf on grain selection have been explored to enhance the 2D grain selector’s performance and reduce casting costs. The experimental results reveal that the final region of carbide formation is where the dendrite is pushed into the paste region and finally solidifies. The performance requirements of carbide on the alloy can be controlled by changing the paste region and solidification sequence.
Mechanical Properties Enhancement of Dissimilar AA6061-T6 and AA7075-T651 Friction Stir Welds Coupled with Deep Rolling Process
Authors: Kaewkham Pisit , Nakkiew Wasawat , Baisukhan Adirek
Published: September 2022

The main purpose of this research was to enhance the mechanical properties of friction stir welds (FSW) in the dissimilar aluminum alloys 6061-T6 and 7075-T651. The welded workpiece has tensile residual stress due to the influence of the thermal conductivity of dissimilar materials, resulting in crack initiation and less fatigue strength. The experiment started from the FSW process using the 2k full factorial with the response surface methodology (RSM) and central composite design (CCD) to investigate three factors. The experiment found that the optimal rotation speed and feed rate values were 979 and 65 mm/min, respectively. Then, the post-weld heat treatment process (PWHT) was applied. Following this, the 2k full factorial was used to investigate four factors involved in the deep rolling process (DR). The experiment found that the optimal deep rolling pressure and deep rolling offset values were 300 bar and 0.2 mm, respectively. Moreover, mechanical property testing was performed with a sequence of four design types of workpieces: FSW, FSW-PWHT, FSW-DR, and FSW-PWHT-DR. It was found that the FSW-PWHT-DR workpiece had an increase in tensile strength of up to 26.29% and increase in fatigue life of up to 129.47% when compared with the FSW workpieces, as well as a maximum compressive residual stress of −414 MPa.
Microstructure Evolution of 2A12 Aluminum Alloy under Isothermal Heat Treatment Direct Writing Process
Authors: Rong Wenjuan , Shan Zhongde , Wang Baoyu , Wang Yongwei , Wang Jialin
Published: September 2022

A metal-melting direct writing process, using semi-solid isothermal heat treatment to form high-quality semi-solid components, realized the integrated innovation of semi-solid formation and additive manufacturing. An experimental study was carried out on semi-solid isothermal heat treatment for metal-melting direct-writing technology, using 2A12 aluminum alloy as raw material. The semi-solid isothermal heat treatment was carried out over different temperature ranges, and four-stages evolution mechanism of the semi-solid microstructure in the semi-solid melting direct writing process was investigated. The effects of holding temperature and time on the microstructure of the semi-solid isothermal heat treatment of the alloy were put forward. According to the analysis of the results of the semi-solid-melting direct-writing test, the corresponding relationship between semi-solid microstructure and extrusion formability was found. The results show that when the holding temperature is 640–650 °C and the holding time is 20–25 min, the liquid phase rate can reach about 40%, and the direct-writing forming technology can be carried out stably.
Active Crack Obstruction Mechanisms in Crofer® 22H at 650 °C
Authors: Fischer Torsten , Kuhn Bernd
Published: September 2022

Increased cyclic loading of components and materials in future thermal energy conversion systems necessitates novel materials of increased fatigue resistance. The widely used 9–12% Cr steels were developed for high creep strength and thus base load application at temperatures below 620 °C. At higher temperature, these materials present unstable grain structure, prone to polygonization under thermomechanical fatigue loading and limited resistance to steam oxidation. This seminal study compares thermomechanical fatigue resistance and long crack propagation of the advanced ferritic-martensitic steel grade 92 and Crofer® 22H, a fully ferritic, high chromium (22 wt. %) stainless steel, strengthened by Laves phase precipitation. Crofer® 22H features increased resistance to fatigue and steam oxidation resistance up to 650 °C. Both thermomechanical fatigue (crack initiation) and residual (crack propagation) lifetime of Crofer® 22H exceeded that of grade 92. The main mechanisms for improved performance of Crofer® 22H were increased stability of grain structure and “dynamic precipitation strengthening” (DPS). DPS, i.e., thermomechanically triggered precipitation of Laves phase particles and crack deflection at Laves phase-covered sub-grain boundaries, formed in front of crack tips, actively obstructed crack propagation in Crofer® 22H. In addition, it is hypothesized that local strengthening may occur near the crack tip because of grain refinement, which in turn may be impacted by testing frequency.
Data-Based Statistical Analysis of Laboratory Experiments on Concrete Frost Damage and Its Implications on Service Life Prediction
Authors: Gong Fuyuan , Zhi Dian , Jia Jianguo , Wang Zhao , Ning Yingjie , Zhang Bo , Ueda Tamon
Published: September 2022

To meet the requirements of durability design for concrete suffering frost damage, several test standards have been launched. Among the various damage indexes such as deteriorated compressive strength, relative dynamic elastic modulus (RDEM), residual deformation, etc., the concept of a “Durability Factor” (DF) is proposed by many standards to define the frost resistivity of concrete against frost action based on the experimental results from standard tests. Through a review of the literature, a clear tendency of strength/RDEM decay and residual deformation increase is captured with increasing cycles of freezing and thawing. However, tests following different standards finally derive huge scattering quantitative responses of frost resistance. Based on the large database of available laboratory experiments, this study presents a statistical analysis to propose a predictable model to calculate the DF with respect to other material factors. The statistical model is believed to be more convenient for engineering applications since the time-consuming experiment is no longer needed, and it is more precise compared with that developed according to only single experimental results to cover the uncertainties and unavoidable errors in specific tests. Moreover, the formula to calculate the DF is revised into a more general form so as to be applicable for all the laboratory experiments even for those cases without fully following the standards to derive a DF value.
PTFE Crystal Growth in Composites: A Phase-Field Model Simulation Study
Authors: Fan Ming , He Wenhao , Li Qiangzhi , Zhou Jing , Shen Jie , Chen Wen , Yu Yuanying
Published: September 2022

We investigated, via a phase-field model simulation, the effects of a matrix’s properties and a filler’s characters on the polytetrafluoroethylene (PTFE) crystal growth process in composites under various supercooling degrees. The results show that the supercooling degree has a deciding influence on the crystal growth process. The intrinsic properties of PTFE polymer, such as anisotropic strength and phase transition latent heat, affect the growth rate, orientation, and interfacial integrity of the crystal trunk and the branching of the PTFE crystal growth process. The factors of the PTFE crystallization process, such as anisotropic strength and phase translation interface thickness, affect the uniformity and crystallization degree of the PTFE crystal. In the composites, the biphasic interface induces the crystal growth direction via the polymer chain segment migration rate, of which the degree depends on the shapes of the filler and the PTFE crystal nucleus. According to the results, choosing the low molecular weight PTFE and mixture filler with various particle sizes and surface curvatures as the raw materials of PTFE-based composites improves the crystallization of the PTFE matrix.
Affecting Microstructure and Properties of Additively Manufactured AISI 316L Steel by Rotary Swaging
Authors: Kunčická Lenka , Kocich Radim , Benč Marek , Dvořák Jiří
Published: September 2022

The presented work focused on the development of the microstructural and mechanical properties of a AISI 316L stainless steel workpiece prepared through additive manufacturing and subsequently processed by hot rotary swaging. In order to characterize the effects of swaging on the structural development, samples were taken for electron microscopy scanning and microhardness measurements were taken after each swaging reduction. The as-built and final swaged pieces were also subjected to tensile testing at room temperature and at 900 °C. The structural analyses showed that the hot swaging introduced a substructural formation; low angle grain boundaries prevailed over high angle ones after each pass. The swaging also imparted an almost complete elimination of the porosity and significant grain size; the average grain area decreased from the original value of 365.5 µm2 to 4.4 µm2 after the final swaging pass. The changes in the texture between the passes were negligible, however, the grain refinement went hand in hand with the microhardness increase (up to almost 300 HV1). The results of the tensile testing confirmed that the mechanical properties of the swaged pieces which improved dramatically and remained favorable up to high temperatures.
Wear Performance of Circular Shim against Cam in Engine Bench Test
Authors: Li Cheng-Di , Wang Jing-Si , Han Xu , Du Feng-Ming , Liu Geng-Shuo , Lin Ren-Jin
Published: September 2022

Unlike the conventional engine, the valve train of a certain type of engine uses a circular shim instead of a tappet to wear against the cam. To verify the reliability of the shim, an engine bench test was used to test its wear performance. The total duration of the bench test was 1000 h, which was divided into three stages. In each stage, the test equipment was stopped, and the shims were disassembled to observe the surface morphology during the worn process. Precious long-term data were obtained. With the extension of the bench test time, weight loss increased. The maximum weight loss occurs 1000 h after worn, which is about twice that of 350 h. During the wear process, a plastic flow of material was found on the subsurface, and fatigue wear marks occurred on the surface. With an increase in test time, the wear marks increased, leading to material spalling and the formation of pits. The wear mechanism was the mixed wear of fatigue wear and adhesive wear.
A Short Overview of Recent Developments in the Application of Polymeric Materials for the Conservation of Stone Cultural Heritage Elements
Authors: Fistos Toma , Fierascu Irina , Doni Mihaela , Chican Irina Elena , Fierascu Radu Claudiu
Published: September 2022

Stones are ones of the most ancient natural materials exploited by humans, with different uses, from tools to buildings, that have endured over time in better conditions than other objects belonging to cultural heritage. Given the importance of those silent witnesses of our past, as well as our duty to preserve all parts of cultural heritage for future generations, much effort was put into the development of materials for their consolidation, protection, self-cleaning, or restoration. Protection of ancient stone monuments and objects has gained the interest of researchers in the last decades in the field of conservation of cultural heritage. In this respect, the present paper aims to be a critical discussion regarding potential polymeric materials, which can be used in restorative and conservative approaches for stone materials of cultural heritage importance, against physical degradation phenomena. Recent advances in this area are presented, as well as the current bottle-necks and future development perspectives.
Investigating Morphology and Breakage Evolution Characteristics of Railroad Ballasts over Distinct Supports Subjected to Impact Loading
Authors: Xiao Yuanjie , Jiang Yu , Tan Pan , Kong Kunfeng , Ali Joseph , Mustafina Ralina , Zhu Hongwei , Cai Degou
Published: September 2022

The ballast bed constantly degrades under the repeated applications of impact loading exerted by passing trains in terms of the particle size, shape, breakage, fouling, etc., thus significantly jeopardizing the in-service performance and operational safety of ballasted tracks. In this study, the morphology and breakage evolution characteristics of railroad ballasts of single- and multiple-size ranges were investigated from laboratory impact-load tests. Both a concrete block and sand layer were placed to mimic the distinct under-ballast supports. The degradation trends of the typical shape and breakage indices were comparatively quantified for different combinations of ballast particle sizes and shapes, under-ballast supports, impact energies, and number of impact-load applications (N). The results show that both shape and size affect ballast particle breakage, with shape being more influential. The breakage severity of flake-like particles is about 1.5–1.66 times and 1.25–1.5 times higher than those of regular and needle-like particles, respectively. Under impact loading, large and small single-size ballasts degrade mainly by breakage and abrasion, respectively. The modified fouling index (FI) of flake-like particles within 31.5–40 mm is about 3.6 times that of regular particles within 50–63 mm. The shape indices of the ballast particles within 31.5–40 mm exhibit the most profound changes. The severities of the ballast breakage and fines generation (or modified FI) increased by 50% and 74%, respectively, due to the increase in the under-ballast support stiffness by 100 times and the drop height of 80 cm, respectively. The convexity and ballast breakage index (BBI) are promising for quantifying particle-degradation trends, and their statistical correlation found herein is potentially useful for the transition of ballast-bed-maintenance management from the current plan-based scheduling to condition-based upgrading.
Atomic Diffusion and Crystal Structure Evolution at the Fe-Ti Interface: Molecular Dynamics Simulations
Authors: Xiang Guojin , Luo Xu , Cao Tianxu , Zhang Ankang , Yu Hui
Published: September 2022

The diffusion bonding method is one of the most essential manufacturing technologies for Ti-steel composite plates. In this paper, the atomic diffusion behavior at the Fe-Ti interface during the bonding process of Ti-steel composite plates is studied using classical diffusion theory and molecular dynamics (MD) simulation. Henceforth, the diffusion mechanism of Fe and Ti atoms at the bonding interface is obtained at the atomic scale. The results show that Fe and Ti atoms diffused deeply into each other during the diffusion process. This behavior consequently increased the thickness of the diffusion layer. Moreover, the diffusion quantity of Fe atoms to the Ti side was much greater than that of Ti atoms to the Fe side. Large plastic deformation and shear strain occurred at the diffusion interface during diffusion. The crystal structure of the diffusion zone was damaged and defects were generated, which was beneficial to the diffusion behavior of the interface atoms. As the diffusion time and temperature increased, the shear strain of the atoms at the interface also increased. Furthermore, there is a relationship between the mutual diffusion coefficient and the temperature. Subsequently, after the diffusion temperature was raised, the mutual diffusion coefficient and atomic disorder (Fe atom and Ti atom) increased accordingly.
Modeling of Electrical Conductivity for Graphene-Filled Products Assuming Interphase, Tunneling Effect, and Filler Agglomeration Optimizing Breast Cancer Biosensors
Authors: Zare Yasser , Rhee Kyong Yop
Published: September 2022

In this study, the percolation inception, actual filler amount, and concentration of nets are expressed using the filler size and agglomeration, interphase depth, and tunneling size. A modified form of the power-law model is recommended for the conductivity of graphene–polymer products using the mentioned characteristics. The modified model is used to plot and evaluate the conductivity at dissimilar ranges of factors. In addition, the prediction results of the model are compared with the experimented values of several samples. A low percolation inception and high-volume portion of nets that improve the conductivity of nanoparticles are achieved at a low agglomeration extent, thick interphase, large aspect ratio of the nanosheets, and large tunnels. The developed equation for percolation inception accurately predicts the results assuming tunneling and interphase parts. The innovative model predicts the conductivity for the samples, demonstrating good agreement with the experimented values. This model is appropriate to improve breast cancer biosensors, because conductivity plays a key role in sensing.
Temperature-Dependent Absorption of Ternary HfS2−xSex 2D Layered Semiconductors
Authors: Lin Der-Yuh , Hsu Hung-Pin , Wang Cheng-Wen , Chen Shang-Wei , Shih Yu-Tai , Hwang Sheng-Beng , Sitarek Piotr
Published: September 2022

In this study, we present the investigation of optical properties on a series of HfS2−xSex crystals with different Se compositions x changing from 0 to 2. We used the chemical-vapor transport method to grow these layered ternary compound semiconductors in bulk form. Their lattice constants and crystal properties were characterized by X-ray diffraction, high-resolution transmission electron microscopy, and Raman spectroscopy. We have performed absorption spectroscopies to determine their optical band-gap energies, which started from 2.012 eV with x = 0, and gradually shifts to 1.219 eV for x = 2. Furthermore, we measured the absorption spectroscopies at different temperatures in the range of 20–300 K to identify the temperature dependence of band-gap energies. The band-gap energies of HfS2−xSex were determined from the linear extrapolation method. We have noticed that the band-gap energy may be continuously tuned to the required energy by manipulating the ratio of S and Se. The parameters that describe the temperature influence on the band-gap energy are evaluated and discussed.
Effect of Processed Volcanic Ash as Active Mineral Addition for Cement Manufacture
Authors: Rosales Julia , Rosales Manuel , Díaz-López José Luis , Agrela Francisco , Cabrera Manuel
Published: September 2022

In the last quarter of 2021, there was a very significant eruption of the Cumbre Vieja volcano on the island of La Palma, belonging to the Canary Islands, Spain. It generated a large amount of pyroclastic volcanic materials, which must be studied for their possible applicability. This work studies the properties and applicability of the lava and volcanic ash generated in this process. The need for reconstruction of the areas of the island that suffered from this environmental catastrophe is considered in this study from the point of view of the valuation of the waste generated. For this purpose, the possibility of using the fine fraction of ashes and lava as a supplementary cement material (SCM) in the manufacture of cement is investigated. The volcanic material showed a chemical composition and atomic structure suitable for replacing clinker in the manufacture of Portland cement. In this study, the cementing and pozzolanic reaction characteristics of unprocessed volcanic materials and those processed by crushing procedures are analysed. To evaluate the cementitious potential by analysing the mechanical behaviour, a comparison with other types of mineral additions (fly ash, silica fume, and limestone filler) commonly used in cement manufacture or previously studied was carried out. The results of this study show that volcanic materials are feasible to be used in the manufacture of cement, with up to a 22% increase in pozzolanicity from 28 to 90 days, showing the high potential as a long-term supplementary cementitious material in cement manufacturing, though it is necessary to carry out crushing processes that improve their pozzolanic behaviour.
Smart Materials
Authors: Fortuna Luigi , Buscarino Arturo
Published: September 2022

The future of engineering systems is based on the capability of integrating sensors, actuators, control systems and materials [...]
Impedance Spectroscopy of Pr-Doped BaBi2Nb2O9 Aurivillius Ceramics
Authors: Rerak Michał , Makowska Jolanta , Adamczyk-Habrajska Małgorzata , Kozielski Lucjan
Published: September 2022

Herein this study, the polycrystalline nature of the Aurivillius type structure is studied; primarily, the main objective is to observe the influence of dopant Pr3+ at the Ba2+-site of BaBi2Nb2O9 (BBN) ceramics. The ceramics under investigation were fabricated via the conventional solid-state reaction method. Scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques were used to analyse their morphological structure. It was found that the chemical composition of the ceramic samples corresponds well to the initial stoichiometry of the ceramic powders. An increase in praseodymium content caused a slight decrease in the average size of the ceramic grains. The obtained ceramic materials are described by a tetragonal structure with the space group I4/mmm. The electrical properties of the material have been studied using complex impedance spectroscopy methods in wide temperature and frequency ranges. The analysis of obtained results showed grains and grain boundaries contribute to conductive processes in the material. A possible ’hopping’ mechanism for electrical transport processes in the system is evident from the analysis of results based on Joncher law.
Microstructure and Properties of WC/Ni-Based Laser-Clad Coatings with Different WC Content Values
Authors: Shen Xuehui , Peng Hao , Xue Yunna , Wang Baolin , Su Guosheng , Zhu Jian , Li Anhai
Published: September 2022

The purpose of this work is to investigate the effect of the WC content on the surface characteristics and nanoindentation behaviors of WC/Ni-based composite laser-clad coatings. Four NiCrSiBC coatings with WC wt% of 30%, 40%, 50%, and 60%, respectively, were clad on carbon steel substrates using a laser. The morphologies and phase compositions of four clad coatings were comparatively observed. In addition, the hardness and elastic modulus values of the four coatings were measured and quantitatively calculated. As a result, with the increase in WC, the coating grains were more refined. Meanwhile, cracks and WC particle breakage occurred in the 50–60% WC coatings, whereas this was not found in the 30–40% WC coatings. When the WC content increased from 40% up to 50%, the coating hardness and elastic modulus significantly increased. However, a further increase in WC from 50% to 60% did not result in considerable improvement in coating quality but considerably worsened the coating’s cracking behavior instead. Therefore, for WC/Ni-based composite coatings, a threshold exists for the WC content, and this value was 50% within the experimental scope of this study.
Investigation of the RF Sputtering Process and the Properties of Deposited Silicon Oxynitride Layers under Varying Reactive Gas Conditions
Authors: Hegedüs Nikolett , Balázsi Csaba , Kolonits Tamás , Olasz Dániel , Sáfrán György , Serényi Miklós , Balázsi Katalin
Published: September 2022

In a single process run, an amorphous silicon oxynitride layer was grown, which includes the entire transition from oxide to nitride. The variation of the optical properties and the thickness of the layer was characterized by Spectroscopic Ellipsometry (SE) measurements, while the elemental composition was investigated by Energy Dispersive Spectroscopy (EDS). It was revealed that the refractive index of the layer at 632.8 nm is tunable in the 1.48–1.89 range by varying the oxygen partial pressure in the chamber. From the data of the composition of the layer, the typical physical parameters of the process were determined by applying the Berg model valid for reactive sputtering. In our modelling, a new approach was introduced, where the metallic Si target sputtered with a uniform nitrogen and variable oxygen gas flow was considered as an oxygen gas-sputtered SiN target. The layer growth method used in the present work and the revealed correlations between sputtering parameters, layer composition and refractive index, enable both the achievement of the desired optical properties of silicon oxynitride layers and the production of thin films with gradient refractive index for technology applications.
Comparison of 2D and 3D Plasma Electrolytic Oxidation (PEO)-Based Coating Porosity Data Obtained by X-ray Tomography Rendering and a Classical Metallographic Approach
Authors: Karlova Polina , Serdechnova Maria , Blawert Carsten , Lu Xiaopeng , Mohedano Marta , Tolnai Domonkos , Zeller-Plumhoff Berit , Zheludkevich Mikhail L.
Published: September 2022

In this work, the porosity of plasma electrolytic oxidation (PEO)-based coatings on Al- and Mg-based substrates was studied by two imaging techniques—namely, SEM and computer microtomography. Two approaches for porosity determination were chosen; relatively simple and fast SEM surface and cross-sectional imaging was compared with X-ray micro computed tomography (microCT) rendering. Differences between 2D and 3D porosity were demonstrated and explained. A more compact PEO coating was found on the Al substrate, with a lower porosity compared to Mg substrates under the same processing parameters. Furthermore, huge pore clusters were detected with microCT. Overall, 2D surface porosity calculations did not show sufficient accuracy for them to become the recommended method for the exact evaluation of the porosity of PEO coatings; microCT is a more appropriate method for porosity evaluation compared to SEM imaging. Moreover, the advantage of 3D microCT images clearly lies in the detection of closed and open porosity, which are important for coating properties.
Modification and Functionalization of Zeolites for Curcumin Uptake
Authors: Musielak Ewelina , Feliczak-Guzik Agnieszka , Jaroniec Mietek , Nowak Izabela
Published: September 2022

This work shows that hierarchical zeolites are promising systems for the delivery of biologically relevant hydrophobic substances, such as curcumin. The validity of using piperine as a promoter of curcumin adsorption was also evaluated. The use of pure curcumin is not medically applicable due to its low bioavailability and poor water solubility. To improve the undesirable properties of curcumin, special carriers are used to overcome these shortcomings. Hierarchical zeolites possessing secondary mesoporosity are used as pharmaceutical carrier systems for encapsulating active substances with low water solubility. This porosity facilitates access of larger reagent molecules to the active sites of the material, preserving desirable adsorption properties, acidity, and crystallinity of zeolites. In this work, methods are proposed to synthesize hierarchical zeolites based on a commercial FAU-type zeolite. Studies on the application and adsorption kinetics of curcumin using commercial FAU-type zeolite and hierarchical zeolites based on commercial FAU-type zeolite are also included.