bluuebunny/crossref_metadata_2025 huggingface dataset:
Green and Superior Adsorbents Derived from Natural Plant Gums for Removal of Contaminants: A Review
Authors: Ge Hanwen , Ding Ke , Guo Fang , Wu Xianli , Zhai Naihua , Wang Wenbo
Published: December 2022

The ubiquitous presence of contaminants in water poses a major threat to the safety of ecosystems and human health, and so more materials or technologies are urgently needed to eliminate pollutants. Polymer materials have shown significant advantages over most other adsorption materials in the decontamination of wastewater by virtue of their relatively high adsorption capacity and fast adsorption rate. In recent years, “green development” has become the focus of global attention, and the environmental friendliness of materials themselves has been concerned. Therefore, natural polymers-derived materials are favored in the purification of wastewater due to their unique advantages of being renewable, low cost and environmentally friendly. Among them, natural plant gums show great potential in the synthesis of environmentally friendly polymer adsorption materials due to their rich sources, diverse structures and properties, as well as their renewable, non-toxic and biocompatible advantages. Natural plant gums can be easily modified by facile derivatization or a graft polymerization reaction to enhance the inherent properties or introduce new functions, thus obtaining new adsorption materials for the efficient purification of wastewater. This paper summarized the research progress on the fabrication of various gums-based adsorbents and their application in the decontamination of different types of pollutants. The general synthesis mechanism of gums-based adsorbents, and the adsorption mechanism of the adsorbent for different types of pollutants were also discussed. This paper was aimed at providing a reference for the design and development of more cost-effective and environmentally friendly water purification materials.
Advances in Multifunctional Bioactive Coatings for Metallic Bone Implants
Authors: Nikolova Maria P. , Apostolova Margarita D.
Published: December 2022

To fix the bone in orthopedics, it is almost always necessary to use implants. Metals provide the needed physical and mechanical properties for load-bearing applications. Although widely used as biomedical materials for the replacement of hard tissue, metallic implants still confront challenges, among which the foremost is their low biocompatibility. Some of them also suffer from excessive wear, low corrosion resistance, infections and shielding stress. To address these issues, various coatings have been applied to enhance their in vitro and in vivo performance. When merged with the beneficial properties of various bio-ceramic or polymer coatings remarkable bioactive, osteogenic, antibacterial, or biodegradable composite implants can be created. In this review, bioactive and high-performance coatings for metallic bone implants are systematically reviewed and their biocompatibility is discussed. Updates in coating materials and formulations for metallic implants, as well as their production routes, have been provided. The ways of improving the bioactive coating performance by incorporating bioactive moieties such as growth factors, osteogenic factors, immunomodulatory factors, antibiotics, or other drugs that are locally released in a controlled manner have also been addressed.
Low Temperature Magnetic Transition of BiFeO3 Ceramics Sintered by Electric Field-Assisted Methods: Flash and Spark Plasma Sintering
Authors: Manchón-Gordón Alejandro Fernando , Perejón Antonio , Gil-González Eva , Kowalczyk Maciej , Sánchez-Jiménez Pedro E. , Pérez-Maqueda Luis A.
Published: December 2022

Low temperature magnetic properties of BiFeO3 powders sintered by flash and spark plasma sintering were studied. An anomaly observed in the magnetic measurements at 250 K proves the clear existence of a phase transition. This transformation, which becomes less well-defined as the grain sizes are reduced to nanometer scale, was described with regard to a magneto-elastic coupling. Furthermore, the samples exhibited enhanced ferromagnetic properties as compared with those of a pellet prepared by the conventional solid-state technique, with both a higher coercivity field and remnant magnetization, reaching a maximum value of 1.17 kOe and 8.5 10−3 emu/g, respectively, for the specimen sintered by flash sintering, which possesses the smallest grains. The specimens also show more significant exchange bias, from 22 to 177 Oe for the specimen prepared by the solid-state method and flash sintering technique, respectively. The observed increase in this parameter is explained in terms of a stronger exchange interaction between ferromagnetic and antiferromagnetic grains in the case of the pellet sintered by flash sintering.
Deformation Behavior under Tension with Pulse Current of Ultrafine-Grain and Coarse-Grain CP Titanium
Authors: Stolyarov Vladimir , Korolkov Oleg , Pesin Alexander , Raab George
Published: December 2022

The problem of the real existence of the electroplastic effect during deformation of metallic materials of different nature is still relevant. At the same time, the influence of structure refinement is not considered enough. In this work, the deformation behavior of ultrafine-grained (UFG) titanium Grade 4 is compared with that of coarse-grained (CG) titanium under tension with pulse current of the low duty cycle. The deformation curves of both structure states are presented for different regimes of pulsed current and thermal heating from an external source. Structure studies by optical and scanning electron microscopy, as well as microhardness measurements have been carried out. It is shown that Grade 4 titanium under tension accompanied by pulsed current exhibits electroplastic effect (EPE) in the form of a flow stress reduction. EPE in UFG state is much stronger than in CG state. An increase in the density and duration of the current pulse leads to a multiple decrease in the flow stresses in CG and UFG titanium. The contribution in the flow stress reduction from heating by an external source was less than that from tension with pulse current at the same temperatures. The impact of pulsed current during tension does not influence microhardness and grain size.
The New Reliable pH Sensor Based on Hydrous Iridium Dioxide and Its Composites
Authors: Lenar Nikola , Piech Robert , Paczosa-Bator Beata
Published: December 2022

The new reliable sensor for pH determination was designed with the use of hydrous iridium dioxide and its composites. Three different hIrO2-based materials were prepared and applied as solid-contact layers in pH-selective electrodes with polymeric membrane. The material choice included standalone hydrous iridium oxide; composite material of hydrous iridium oxide, carbon nanotubes, and triple composite material composed of hydrous iridium oxide; carbon nanotubes; and poly(3-octylthiophene-2,5-diyl). The paper depicts that the addition of functional material to standalone metal oxide is beneficial for the performance of solid-state ion-selective electrodes and presents the universal approach to designing this type of sensors. Each component contributed differently to the sensors’ performance—the addition of carbon nanotubes increased the electrical capacitance of sensor (up to 400 µF) while the addition of conducting polymer allowed it to increase the contact angle of material changing its wetting properties and enhancing the stability of potentiometric response. Hydrous iridium oxide contacted electrodes exhibit linear response in wide linear range of pH (2–11) and stable potentiometric response (the lowest potential drift of 0.036 mV/h is attributed to the electrode with triple composite material).
Nanomaterials as Photocatalysts—Synthesis and Their Potential Applications
Authors: Feliczak-Guzik Agnieszka
Published: December 2022

Increasing demand for energy and environmental degradation are the most serious problems facing the man. An interesting issue that can contribute to solving these problems is the use of photocatalysis. According to literature, solar energy in the presence of a photocatalyst can effectively (i) be converted into electricity/fuel, (ii) break down chemical and microbial pollutants, and (iii) help water purification. Therefore, the search for new, efficient, and stable photocatalysts with high application potential is a point of great interest. The photocatalysts must be characterized by the ability to absorb radiation from a wide spectral range of light, the appropriate position of the semiconductor energy bands in relation to the redox reaction potentials, and the long diffusion path of charge carriers, besides the thermodynamic, electrochemical, and photoelectrochemical stabilities. Meeting these requirements by semiconductors is very difficult. Therefore, efforts are being made to increase the efficiency of photo processes by changing the electron structure, surface morphology, and crystal structure of semiconductors. This paper reviews the recent literature covering the synthesis and application of nanomaterials in photocatalysis.
Controllable Preparation of Ag-SiO2 Composite Nanoparticles and Their Applications in Fluorescence Enhancement
Authors: Tang Luping , Liao Chen , Guo Yingqing , Zhang Yangyang
Published: December 2022

Metal nanoparticles have attracted a great deal of interest due to their unique properties of surface plasmon resonance. Metal nanoparticles can enhance the fluorescence emission intensity of quantum dots (QDs) through the local surface plasmon resonance effect, which is mainly determined by the distance between them. Therefore, it is very important to achieve controllable distance between metal and QDs, and study fluorescence enhancement. In this work, the controllable adjustment of the distance between metal nanoparticles and QDs was successfully realized by controlling the thickness of the SiO2 shell of Ag@SiO2 nanoparticles. Firstly, Ag nanoparticles with uniform size distribution and relatively high concentration were prepared, and then the thickness of the SiO2 shell was controlled by controlling the amount of tetra-ethyl orthosilicate (TEOS) in the hydrolysis of TEOS reaction. (3-aminopropyl) triethoxysilane (APS) was used to connect CdS/ZnS QDs with Ag@SiO2 nanoparticles to form Ag@SiO2@CdS/ZnS QD composite nanoparticles. The fluorescence spectra shows that the fluorescence intensity of the Ag@SiO2@CdS/ZnS QD composite nanoparticles is significantly enhanced. Photoexcitation spectra and fluorescence spectra of CdS/ZnS QD and Ag@SiO2@CdS/ZnS QD composite nanoparticles, measured under different energy excitation conditions, indicate that the existence of Ag nanoparticles can enhance the fluorescence intensity of CdS/ZnS QDs. Finally, a further physical mechanism of fluorescence enhancement is revealed.
Investigation of Nitrogen and Vacancy Defects in Synthetic Diamond Plates by Positron Annihilation Spectroscopy
Authors: Eseev Marat , Kuziv Ivan , Kostin Aleksey , Meshkov Igor , Sidorin Aleksey , Orlov Oleg
Published: December 2022

Currently, diamonds are widely used in science and technology. However, the properties of diamonds due to their defects are not fully understood. In addition to optical methods, positron annihilation spectroscopy (PAS) can be successfully used to study defects in diamonds. Positrons are capable of detecting vacancies, and small and large clusters of vacancies induced by irradiation, by providing information about their size, concentration, and chemical environment. By mapping in the infrared (IR) range, it is possible to consider the admixture composition of the main inclusions of the whole plate. This article presents the results of a study of defects in synthetic diamond plates, one of which was irradiated by electrons. It presents data about the distribution of the defect concentration obtained by Infrared spectroscopy. PAS with a monochromatic positron beam can be used as a non-destructive technique of detecting defects (vacancy) distribution over the depth of diamond plates.
Investigation of the Fracture Characteristics of a Cement Mortar Slab under Impact Loading Based on the CDEM
Authors: Zhang Qunlei , Wang Decai , Yue Jinchao , Feng Chun , Yuan Ruifu
Published: December 2022

For brittle and quasi-brittle materials such as rock and concrete, the impact-resistance characteristics of the corresponding engineering structures are key to successful application under complex service environments. Modeling of concrete-like slab fractures under impact loading is helpful to analyze the failure mechanism of an engineering structure. In this paper, simulation models of impact tests of a cement mortar slab were developed, and a continuum–discontinuum element method (CDEM) was used for dynamic analysis. Concretely, the cracking simulations of a mortar slab when considering the hammer shape and impact velocity were conducted, and the impact process and failure results of the slab structure were analyzed. The results showed that the top fracture area of the mortar slab was significantly smaller than that of slab bottom under impact loadings of the drop hammer. The impact velocity was an important factor that affected the mortar slab’s cracking. With the increase in the initial impact velocity, the effective fracture area of the slab structure increased significantly; the impact force and rupture degree of the mortar slab also showed a linear growth trend. The shapes of the impact hammerhead also had a significant effect on the crack model of the mortar slab. The effective fracture zones of slab structures were close under circular and square hammers, while the effective fracture zone was significantly larger under a rectangular hammer impact. The peak value (45.5 KN) of the impact force under a circular hammer was significantly smaller than the peak value (48.7 KN) of the impact force under the rectangular hammer. When considering the influence of the stress concentration of the impact hammerhead, the maximum impact stress of the rectangular hammer was 147.3 MPa, which was significantly greater than that of the circular hammer impact (maximum stress of 87.5 MPa). This may have meant that the slab structures were prone to a directional rupture that mainly propagated along the long axis of the rectangular hammerhead. This impact mode is therefore more suitable for rehabilitation and reconstruction projects of slab structures.
A Model of Stress-Damage-Permeability Relationship of Weakly Cemented Rocks under Triaxial Compressive Conditions
Authors: Zhang Shizhong , Fan Gangwei , Zhang Dongsheng , Li Wenping , Luo Tao , Liang Shuaishuai , Fan Zhanglei
Published: December 2022

To unravel the permeability variation mechanism of weakly cemented rocks (WCR), the paper conducted triaxial permeability tests on weakly cemented sandstones (WCS) collected from the Jurassic formation in northwest China. The paper identified the correlation of WCS permeability versus porosity, cementation structure, and mineral composition, further developing a model to characterize the WCS stress–damage–permeability relationship. The research indicated that the WCS permeability was initially high due to the naturally high porosity, large pore diameter, and loose particle cementation, thus favoring a significant decline as pore convergence in the compaction stage. In the residual stage, kaolinite and montmorillonite minerals disintegrated into water and narrowed fractures, causing a slight permeability increase from the initial to the maximum and residual stages. The WCS matrix fracturing was phenomenologically accompanied by clay mineral disintegration. By assuming that the matrix can be compressed, jointed, and fractured, the paper defined a damage variable D and accordingly developed a stress–damage–permeability relationship model that incorporated matrix compression, jointing, and fracturing. The model can describe the WCS permeability regime regarding the high initial permeability and slight difference of the maximum and residual permeabilities versus the initial.
Trace Element Contents in Maize following the Application of Organic Materials to Reduce the Potential Adverse Effects of Nitrogen
Authors: Wyszkowski Mirosław , Brodowska Marzena S. , Kordala Natalia
Published: December 2022

The plants cultivated in loamy sand contained less iron, manganese, copper, cobalt, nickel, and zinc while containing more chromium, lead, and cadmium than in sand. This study was launched to use organic materials in the form of humic acids (HA) to reduce the potential negative effects of excessive nitrogen fertiliser (ammonium nitrate, urea, and urea and ammonium nitrate solution—UAN) application rates (160 mg N kg−1 soil) on the trace element contents in maize in two soils differing in granulometric composition. HA were applied into the soil three times during the maize vegetation: before the sowing, at the five-leaf unfolded stage, and at the intensive shoot growth stage. The HA doses amounted to 0, 0.05, 0.10, and 0.15 g kg−1 soil. Urea fertilisation increased the cadmium, lead, chromium, and nickel contents and reduced the iron content in maize on both soils. UAN contributed to an increased chromium content being higher than that caused by urea and to reduced iron content in the aboveground parts of maize, as compared to the objects with ammonium nitrate. In the series with ammonium nitrate, the highest dose of HA reduced the manganese, zinc, iron, and cobalt contents in maize on both soils. In the series with urea, however, their reducing effect on the copper and iron contents in maize on both soils was noted. The study also demonstrated a positive reduction in the contents of many other trace elements in maize under the influence of the application of HA (particularly, their highest dose). However, it only concerned one of the soils under study. The application of HA into the soil can be effective in reducing the trace element content in plants and can mitigate the adverse environmental impact of intensive agricultural production.
Influence of High-Pressure Torsion Processing on the Tribological Properties of Aluminum Metal Matrix Composites
Authors: El Aal Mohamed Ibrahim Abd , El-Fahhar Hossam Hemdan , Mohamed Abdelkarim Yousif , Gadallah Elshafey Ahmed
Published: December 2022

The motivation for the current study was to improve the wear and frictional properties of Al, Al–Al2O3, and SiC MMCs through HPT processing. The wear test using a tungsten carbide (WC) ball was carried out for different PM and HPT-processed Al and MMC samples. The effect of the sample processing methods on the wear rate, friction, and wear surface morphology was thoroughly investigated. The high hardness after Al grain refinement and reinforcement fragmentation through the HPT processing of the samples increased the wear resistance by 16–81% over that of the PM samples. The average coefficient values and variation ranges were reduced after HPT processing. The Al and Al MMC processing methods affected the wear mechanism and surface morphologies, as proven by the microscopic observations and analyses of the worn surfaces of the samples and WC balls.
Assessment of Corrosion Protection Performance of FeOOH/Fe3O4/C Composite Coatings Formed In Situ on the Surface of Fe Metal in Air-Saturated 3.5 wt.% NaCl Solution
Authors: Huang Lina , Luo Qi , He Yan
Published: December 2022

The purpose of this work is to evaluate the corrosion-inhibition behavior of deposited carbon and some iron-oxide hybrid coatings which derived from the in situ deposition method on the surface of Fe foil. Various contents of precursor methane gas were deposited over a mild iron foil substrate and formed different composites. It was found that the incorporation of C into the Fe matrix led to a thin film on the surface of the matrix and produced an anti-corrosion effect. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and potentiometric tests were used to compare the corrosion behaviors of the films in air-saturated 3.5 wt.% NaCl solution. According to the results, Fe-oxide- and C-composite-coated iron foil has a much higher corrosion resistance than the raw blank sample without the addition of C. Generally, the corrosion charge transfer resistance of one kind of iron oxide coated with carbon layers of several nanometers was enhanced up to 28,379 times (Rct changes from 1487 Ω cm2 to 4.22 × 107 Ω cm2), which is the biggest improvement so far. The maximum protection efficiency was obtained for the in situ grown coating prepared by 10 and 15 sccm CH4 precursor gas (eta = 100%). In conclusion, an iron oxide and carbon composite was found to be a great candidate for applications in the corrosion-resistance area.
Hydroxyapatite Nanopowders for Effective Removal of Strontium Ions from Aqueous Solutions
Authors: Predoi Silviu Adrian , Ciobanu Steluta Carmen , Chifiriuc Mariana Carmen , Motelica-Heino Mikael , Predoi Daniela , Iconaru Simona Liliana
Published: December 2022

Drinking water contamination has become a worldwide problem due to the highly negative effects that pollutants can have on human organisms and the environment. Hydroxyapatite (HAp) has the appropriate properties for the immobilization of various pollutants, being considered amongst the most cost-effective materials for water decontamination. The main objective of this study was to use synthesized hydroxyapatite for the elimination of Sr2+ ions from contaminated solutions. The hydroxyapatite used in the decontamination process was synthesized in the laboratory using an adapted method. The hydroxyapatite powder (HAp) resulting from the synthesis was analyzed both before and after the elimination of Sr2+ ions from contaminated solutions. The efficiency of the HAp nanoparticles in removing Sr2+ ions from contaminated solution was determined by batch adsorption experiments. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to study the HAp samples before and after the removal of Sr2+ ions. The ability of HAp nanoparticles to eliminate strontium ions from contaminated solutions was established. Moreover, the removal of Sr2+ ions from the contaminated aqueous solutions was highlighted by ultrasound measurements. The value of the stability parameter calculated by ultrasonic measurements after the removal of Sr2+ ions from the contaminated solution was similar to that of double distilled water whose stability was used as reference. The outcomes of the batch experiments and the parameters obtained from Langmuir and Freundlich models indicated that the HAp nanoparticles had a strong affinity for the elimination of Sr2+ ions from polluted solutions. These results emphasized that HAp nanoparticles could be excellent candidates in the development of new technologies for water remediation. More than that, the outcomes of the cytotoxic assays proved that HAp nanoparticles did not induce any noticeable harmful effects against HeLa cells and did not affect their proliferation after 1 day and 7 days of incubation.
Effects of Illitic Clay on the Phases, Microstructure, Physical Properties and Pyroplastic Deformation of Industrial Slag Ceramics
Authors: You Hao , Sun Hongjuan , Peng Tongjiang , Zhou Xin , Chao Li , Wang Can
Published: December 2022

Preparing ceramic materials is a meaningful way to treat and utilize industrial slags. In this work, high-performance and low-deformation industrial slag ceramics were prepared from Ti-extraction blast furnace slag and illitic clay. The phase composition and contents, microstructure, physical properties, and pyroplastic deformation of ceramic samples were investigated. With the increasing proportion of illitic clay, the main crystalline phase of ceramic samples changed from akermanite to Fe-bearing diopside. Moreover, the minor crystalline phases changed from perovskite and spinel to anorthite and titanite. The proportion of illitic clay was linearly related to the amorphous phase content. The dense microstructure comprised concentrated short-columnar and granular grains with a few isolated pores, whereas plate-like grains destroyed their denseness. An appropriate proportion of illitic clay helped to improve the physical properties, increase the high-temperature viscosity and reduce the deformation of the ceramics. The optimal proportion of illitic clay was 30%, and the prepared ceramic sample had a dense microstructure and excellent physical properties. Its bulk density was 2.82 g/cm3, bending strength was 62.17 MPa, and water absorption was 0.21%.
Improved Procedure for the 3D Reconstruction of Asphalt Concrete Mesostructures Considering the Similarity of Aggregate Phase Geometry between Adjacent CT Slices
Authors: Wang Chao , Xu Hui , Zhang Yan , Sun Yiren , Wang Weiying , Chen Jingyun
Published: December 2022

Existing image segmentation algorithms used for the computed tomography (CT) images of asphalt concrete mostly ignore the similarity of aggregate phase geometry between adjacent CT slices, thus increasing the variability in the aggregate phase pixel values between adjacent slices and leading to a large number of model defects, e.g., interconnected aggregates, flaky aggregates, and incomplete aggregates. The developed mesostructural models with these defects pose a challenge to following simulation operations. To address this issue, an improved procedure for the 3D reconstruction of asphalt concrete mesostructures considering the similarity of aggregate phase geometry between adjacent slices was developed, which includes two adjacent-slice pixel-value-correction algorithms, a multi-directional multiple-correction method, and an image pixel interpolation process. First, the bilinear interpolation algorithm was employed to improve the pixel density of 2D CT images and the average filtering algorithm was used to reduce the noise of the CT images. Subsequently, the OTSU method was employed to separate the asphalt mortar matrix phase from the aggregate phase, and the marker-based watershed segmentation method was used to separate the interconnected aggregates. Finally, the adjacent-slice pixel-value-correction algorithm was used to recover the similarity of aggregate phase geometry between adjacent CT slices, and the multi-directional multiple-correction method was used to further enhance the geometric similarity. The results show that the developed 3D reconstruction procedure removes most of the model defects in the 3D mesostructural model of asphalt concrete, thus realistically maintaining the 3D spatial distribution features and contour characteristics.
Loop Closure Detection for Mobile Robot based on Multidimensional Image Feature Fusion
Authors: Li Jinming , Wang Peng , Ni Cui , Zhang Dong , Hao Weilong
Published: December 2022

Loop closure detection is a crucial part of VSLAM. However, the traditional loop closure detection algorithms are difficult to adapt to complex and changeable scenes. In this paper, we fuse Gist features, semantic features and appearance features of the image to detect the loop closures quickly and accurately. Firstly, we take advantage of the fast extraction speed of the Gist feature by using it to screen the loop closure candidate frames. Then, the current frame and the candidate frame are semantically segmented to obtain the mask blocks of various types of objects, and the semantic nodes are constructed to calculate the semantic similarity between them. Next, the appearance similarity between the images is calculated according to the shape of the mask blocks. Finally, based on Gist similarity, semantic similarity and appearance similarity, the image similarity calculation model can be built as the basis for loop closure detection. Experiments are carried out on both public and self-filmed datasets. The results show that our proposed algorithm can detect the loop closure in the scene quickly and accurately when the illumination, viewpoint and object change.
Characterization of the Anomalous Vibration Response of an Intentionally Mistuned LPT Rotor
Authors: Rodríguez-Blanco Salvador , Martel Carlos
Published: December 2022

The wind tunnel facility at the Centro de Tecnologías Aeronáuticas was used to perform a set of experiments to study the effect of intentional mistuning on the forced response behavior of an aerodynamically unstable low-pressure turbine rotor. The intentional mistuning patterns were implemented by adding a small extra mass to some of the blades. The forced response of the rotor was therefore expected to show two resonance peaks with similar amplitudes, corresponding, respectively, to the vibration frequencies of the blades with and without added mass. However, on the post-processing of the measurements, some anomalous behavior was observed. Near resonance, the system response was synchronous with the forcing, and the frequency sweeps exhibited two resonance peaks, but it was found that the two peaks were clearly different, with the peak at lower frequency showing a much higher vibration amplitude than the high-frequency peak, and with some blades responding at both frequencies with a similar amplitude. In order to give a correct interpretation of the experimental results, a reduced-order model is derived that takes into account only the traveling wave modes coupled by the mistuning. This model, although extremely simple, is capable of reproducing the unexpected behavior of the experiments, and gives a clean explanation of the system response. It is shown that the relative size of the mistuning with respect to the frequency difference of the involved traveling-wave modes is the key parameter for the appearance of this phenomenon.
Effect of the Inclined Part Length of an Inclined Blade on the Cavitation Characteristics of Vortex Pumps
Authors: Yin Zhuofan , Gu Yunqing , Fan Tianxing , Li Zhou , Wang Wenting , Wu Denghao , Mou Jiegang , Zheng Shuihua
Published: December 2022

To study the effect of the length of the second inclined section of the inclined vane on the vortex structure and pressure distribution inside a vortex pump, this paper uses a combination of numerical simulations (CFD) and experimental verification methods to analyze the static pressure distribution of the internal flow field and the volume fraction distribution of the impeller bubble at different total inlet pressures as well as to analyze the volume and streamline of the distribution of the impeller bubble of the vortex pump at different instants. The results show that as the length of the second inclined section of the inclined vane increases, both the low-pressure area and the volume fraction of the vapor bubbles inside the impeller of the vortex pump increase, and the resistance to cavitation becomes worse. When the total inlet pressure of the impeller is low, a large number of vortices will be generated inside the flow channel of the vortex pump, leading to vortex cavitation; the longer the length of the inclined section, the larger the velocity gradient of the fluid and the more serious the phenomenon of deliquescence, leading to more intense cavitation, while a shorter inclined section length can effectively improve the anti-cavitation performance of the vortex pump.
Effect of Machined Tooth Surface Mixed Lubrication Sliding Wear on Gear Dynamic Characteristics
Authors: Zhao Jiang , Yu Xiaofeng , Sheng Wei , Li Zhengminqing , Zhang Hong , Zhu Rupeng
Published: December 2022

Tooth surface wear causes variation in meshing stiffness and transmission error of the gear system and further causes the fluctuation of dynamic characteristics. In this study, a dynamic behavior prediction model of the gear transmission system was established, which considered the machined tooth surface wear based on the mixed lubrication sliding wear model and the gear tribology-dynamic model. The gear pair wear characteristics along the meshing line were analyzed through simulations, and the impacts of wear conditions, operating torque, and speed on the dynamic characteristics of the gear transmission system with tooth surface wear were discussed. The results demonstrated that the transmission error and the vibration displacement amplitude of the gear system had increased gradually with the increase of the wear degree and that the fluctuation intensified. The fluctuation of gear dynamic characteristics increased with the increase in torque, and the fluctuation of gear dynamic characteristics initially increases and then decreases with the increase in rotating speed.
Detection of Compound Faults in Ball Bearings Using Multiscale-SinGAN, Heat Transfer Search Optimization, and Extreme Learning Machine
Authors: Suthar Venish , Vakharia Vinay , Patel Vivek K. , Shah Milind
Published: December 2022

Intelligent fault diagnosis gives timely information about the condition of mechanical components. Since rolling element bearings are often used as rotating equipment parts, it is crucial to identify and detect bearing faults. When there are several defects in components or machines, early fault detection becomes necessary to avoid catastrophic failure. This work suggests a novel approach to reliably identifying compound faults in bearings when the availability of experimental data is limited. Vibration signals are recorded from single ball bearings consisting of compound faults, i.e., faults in the inner race, outer race, and rolling elements with a variation in rotational speed. The measured vibration signals are pre-processed using the Hilbert–Huang transform, and, afterward, a Kurtogram is generated. The multiscale-SinGAN model is adapted to generate additional Kurtogram images to effectively train machine-learning models. To identify the relevant features, metaheuristic optimization algorithms such as teaching–learning-based optimization, and Heat Transfer Search are applied to feature vectors. Finally, selected features are fed into three machine-learning models for compound fault identifications. The results demonstrate that extreme learning machines can detect compound faults with 100% Ten-fold cross-validation accuracy. In contrast, the minimum ten-fold cross-validation accuracy of 98.96% is observed with support vector machines.
A Novel Predefined Time PD-Type ILC Paradigm for Nonlinear Systems
Authors: Yin Chun-Wu , Riaz Saleem , Zaman Haider , Ullah Nasim , Blazek Vojtech , Prokop Lukas , Misak Stanislav
Published: December 2022

Intelligent robotics has drawn a great deal of attention due to its high precision, stability, and reliability, which are the basic key factors for industrial automation. This paper proposes an iterative learning control (ILC) technique with predefined-time convergence as a solution to an applied engineering problem, namely, that local time cannot be preset when a second-order nonlinear system undertakes control of the accurate tracking of local time under any initial iterative value. A time-varying sliding surface with an initial value of zero was designed, and it was theoretically proven that the trajectory tracking error in the sliding surface could converge to zero within a predefined time. The iterative control problem of trajectory tracking was thus changed to an iterative control problem of time-varying sliding-mode surface tracing with a starting value of zero. A PD-type closed-loop ILC with a time-varying sliding mode surface was designed such that the trajectory tracking error converged and stabilized on the sliding mode surface after a finite number of learning iterations. The control goal for the system’s output was the ability to track the desired trajectory accurately within a predefined time interval, and it was achieved by combining this with the predefined time convergence characteristics of the time-varying sliding mode surface. Numerical simulation of trajectory tracking control of a repetitive motion manipulator was used to verify the effectiveness of the proposed controller and its robustness in the face of external disturbances.
A New Approach to Compute System Reliability with Three-Serially Linked Modules
Authors: Sadiya  , Ram Mangey , Kumar Akshay
Published: December 2022

The efficiency of a bridge system and a 2-out-of-4:G system has been evaluated in the proposed work. The technique for evaluating the system’s reliability and signature reliability of different models has been employed in this work. We implemented the structure–function technique to determine the reliability function of the bridge model, 2-out-of-4:G model, and three serially connected modules system, which avoids Boland’s Formula to minimize the calculations and to reduce the failure rate of the complex system in order to maximize its capability. Three illustrative systems of five, four, and fourteen vertices each were separated and placed in series-parallel combinations. There is another simpler and faster concept to determine the system’s tail signature by using the coefficient of the reliability function described in this paper. The system’s reliability, minimal signature, tail signature, signature, B-P index, expected time, and expected cost were all calculated using this approach. This work also describes the reliability estimation of three serially connected systems with the help of different approaches. These findings contribute to the probabilistic method’s usefulness in analyzing the system’s signature and reliability.
A Method for Augmenting Supersaturated Designs with Newly Added Factors
Authors: Zheng Chun-Wei , Qi Zong-Feng , Zhang Qiao-Zhen , Liu Min-Qian
Published: December 2022

Follow-up experimental designs are popularly used in industry. In practice, some important factors may be neglected for various reasons in the first-stage experiment and they need to be added in the next stage. In this paper, we propose a method for augmenting supersaturated designs with newly added factors and augmented levels using the Bayesian D-optimality criterion. In addition, we suggest using the integrated Bayesian D-optimal augmented design to plan the follow-up experiment when the newly added factors have been allowed to vary in an appropriate region. Examples and simulation results show that the augmented designs perform well in improving identified rates of latent factor effects.
Mathematical Problems in Rock Mechanics and Rock Engineering
Authors: Huang Linqi , Wang Shaofeng , Cai Xin , Song Zhengyang
Published: December 2022

With the increasing requirements for energy, resources and space, numerous rock engineering projects (e [...]
Ultraproducts and Related Constructions
Authors: Sági Gábor
Published: December 2022

In this work, we survey some research directions in which the ultraproduct construction and methods based on ultrafilters play significant roles. Rather different areas of mathematics have been considered: topics we are reviewing here include some aspects of the model theory of first-order and second-order existential logics, finite Ramsey theory and general topology. Special emphasis has been made for producing a uniform treatment and for highlighting interconnections between these different subjects.
A Novel ON-State Resistance Modeling Technique for MOSFET Power Switches
Authors: Guran Ionuț-Constantin , Florescu Adriana , Perișoară Lucian Andrei
Published: December 2022

Nowadays, electronic circuits’ time to market is essential, with engineers trying to reduce it as much as possible. Due to this, simulation has become the main testing concept used in the electronics domain. In order to perform the simulation of a circuit, a behavioral model must be created. Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) are semiconductor devices found in a multitude of electronic circuits, and they are also used as power switches in many applications, such as low-dropout linear voltage regulators, switching regulators, gate drivers, battery management systems, etc. A MOSFETs’ behavior is extremely complex to model, thus, creating high-performance models for these transistors is an imperative condition in order to emulate the exact real behavior of a circuit using them. An essential parameter of MOSFET power switches is the ON-state resistance (RDSON), because it determines the power losses during the ON state. Ideally, the power losses need to be zero. RDSON depends on multiple factors, such as temperature, load current, and gate-to-source voltage. Previous studies in this domain focus on the modeling of the MOSFET only in specific operating points, but do not cover the entire variation range of the parameters, which is critical for some applications. For this reason, in this paper, there was introduced for the first time a novel ON-state resistance modeling technique for MOSFET Power Switches, which solves the entire RDSON dependency on the transistor’s variables stated above. The novel RDSON modeling technique is based on modulating the transistor’s gate-to-source voltage such that the exact RDSON value is obtained in each possible operating point. The method was tested as a real-life example by creating a behavioral model for an N-channel MOSFET transistor and the chosen simulation environment was Oregon, USA, Computer-Aided Design (OrCAD) capture. The results show that the model is able to match the transistor’s RDSON characteristics with a maximum error of 0.8%. This is extremely important for applications in which the temperatures, voltages, and currents vary over a wide range. The new proposed modeling method covers a gap in the behavioral modeling domain, due to the fact that, until now, it was not possible to model the RDSON characteristics in all operating corners.
A Noise-Aware Multiple Imputation Algorithm for Missing Data
Authors: Li Fangfang , Sun Hui , Gu Yu , Yu Ge
Published: December 2022

Missing data is a common and inevitable phenomenon. In practical applications, the datasets usually contain noises for various reasons. Most of the existing missing data imputing algorithms are affected by noises which reduce the accuracy of the imputation. This paper proposes a noise-aware missing data multiple imputation algorithm NPMI in static data. Different multiple imputation models are proposed according to the missing mechanism of data. Secondly, the method to determine the imputation order of multivariablesmissing is given. A random sampling consistency algorithm is proposed to estimate the initial values of the parameters of the multiple imputation model to reduce the influence of noise data and improve the algorithm’s robustness. Experiments on two real datasets and two synthetic datasets verify the accuracy and efficiency of the proposed NPMI algorithm, and the results are analyzed.
Nonexistence and Existence of Solutions with Prescribed Norms for Nonlocal Elliptic Equations with Combined Nonlinearities
Authors: Yan Baoqiang , O’Regan Donal , Agarwal Ravi P.
Published: December 2022

In this paper, we study the nonlocal equation ∫RN|u(x)|2dxγΔu=λu+μ|u|q−2u+|u|p−2u, xinRN having a prescribed mass ∫RN|u(x)|2dx=c2, where N≥3, μ, γ∈(0,+∞), q∈(2,2∗), c is a positive constant, p, q∈(2,2∗) with p≠q and 2∗=2NN−2. This research is meaningful from a physical point of view. Using variational methods, we present some results on the nonexistence and existence of solutions under different cases p and q which improve upon the previous ones via topological theory.
Energy-Efficient Hybrid Flowshop Scheduling with Consistent Sublots Using an Improved Cooperative Coevolutionary Algorithm
Authors: Li Chengshuai , Zhang Biao , Han Yuyan , Wang Yuting , Li Junqing , Gao Kaizhou
Published: December 2022

Energy conservation, emission reduction, and green and low carbon are of great significance to sustainable development, and are also the theme of the transformation and upgrading of the manufacturing industry. This paper concentrates on studying the energy-efficient hybrid flowshop scheduling problem with consistent sublots (HFSP_ECS) with the objective of minimizing the energy consumption. To solve the problem, the HFSP_ECS is decomposed by the idea of “divide-and-conquer”, resulting in three coupled subproblems, i.e., lot sequence, machine assignment, and lot split, which can be solved by using a cooperative methodology. Thus, an improved cooperative coevolutionary algorithm (vCCEA) is proposed by integrating the variable neighborhood descent (VND) strategy. In the vCCEA, considering the problem-specific characteristics, a two-layer encoding strategy is designed to represent the essential information, and a novel collaborative model is proposed to realize the interaction between subproblems. In addition, special neighborhood structures are designed for different subproblems, and two kinds of enhanced neighborhood structures are proposed to search for potential promising solutions. A collaborative population restart mechanism is established to ensure the population diversity. The computational results show that vCCEA can coordinate and solve each subproblem of HFSP_ECS effectively, and outperform the mathematical programming and the other state-of-the-art algorithms.
Intelligent Management of Enterprise Business Processes
Authors: Odrekhivskyi Mykola , Pshyk-Kovalska Orysya , Zhezhukha Volodymyr , Ivanochko Iryna
Published: December 2022

The article develops the conceptual foundations of natural and artificial intellectualization of the enterprise, as well as the combination of artificial and natural intelligence in managing business processes in the context of modern challenges of the business environment. Based on the methods of structural design, a system model of the enterprise is developed as the basis for intelligent management. Quantitative and qualitative effects of human–cyber–physical systems, which are the result of management intellectualization, are highlighted. The possibilities of using deviation and perturbation management methods in managing the state of enterprise development with the support of decision-making and implementation of an intelligent information system are considered. The features of making managerial decisions during intelligent enterprise management are considered. The place of the human factor in such intellectual management is highlighted, in particular, in terms of improving the intelligence of employees and the natural intellectualization of the enterprise. The problem of assessing and forecasting the state of enterprise development in the context of intellectual management is highlighted. In this context, the expediency of using mathematical methods of Markov process theory, using systems of Kolmogorov differential equations and their solutions, using numerical methods and applied software products is justified. This made it possible to study the dynamics of probabilities of states and stability of development of enterprises and their employees; the dynamics of probabilities of states of innovative and technological processes; scientific and technological, environmental, social and economic efficiency of a business. To test the proposed mathematical models for assessing and predicting the state of development of enterprises and their employees, appropriate studies were conducted on the sanatorium–resort complex in Truskavets (Ukraine).
Study of Steam-Induced Convection in a Rotating Vertical Flow Channel
Authors: Zwawi Mohammed , Khan Afrasyab , Bahadar Ali , Algarni Mohammed
Published: December 2022

The phenomenon of steam–water direct contact condensation has significance in a wide range of industrial applications. Superheated steam was injected upward into a cylindrical water vessel. Visual observations were conducted on a turbulent steam jet to determine the dimensionless steam jet length compared to the steam nozzle exit diameter and the steam maximum swelling ratio as a function of steam mass flux at the nozzle exit, with a gas steam flux ranging from 295–883 kg/m2s. The Reynolds number based on the steam jet’s maximum expansion ranged from 41,000 to 93,000. Farther above of the condensation region, the jet evolved as a single-phase heated plume, surrounded by ambient water. Mean axial central velocity profiles were determined against the steam mass flux ranging from 295–883 kg/m2s to observe the exponential drop in the mean axial velocity as the vertical distance increased. The radial velocity distribution within the spread of the jet was determined to be self-similar, and the radial distribution of the velocity profile followed the Gaussian function, after the proper scaling of the vertical distance and the axial mean velocity.