bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear Dynamic Modeling and Analysis of an L-Shaped Multi-Beam Jointed Structure with Tip Mass
Authors: Wei Jin , Yu Tao , Jin Dongping , Liu Mei , Cao Dengqing , Wang Jinjie
Published: December 2021

A dynamic model of an L-shaped multi-beam joint structure is presented to investigate the nonlinear dynamic behavior of the system. Firstly, the nonlinear partial differential equations (PDEs) of motion for the beams, the governing equations of the tip mass, and their matching conditions and boundary conditions are obtained. The natural frequencies and the global mode shapes of the linearized model of the system are determined, and the orthogonality relations of the global mode shapes are established. Then, the global mode shapes and their orthogonality relations are used to derive a set of nonlinear ordinary differential equations (ODEs) that govern the motion of the L-shaped multi-beam jointed structure. The accuracy of the model is verified by the comparison of the natural frequencies solved by the frequency equation and the ANSYS. Based on the nonlinear ODEs obtained in this model, the dynamic responses are worked out to investigate the effect of the tip mass and the joint on the nonlinear dynamic characteristic of the system. The results show that the inertia of the tip mass and the nonlinear stiffness of the joints have a great influence on the nonlinear response of the system.
Evaluation of the Repolished Surface Properties of a Resin Composite Employing Structural Coloration Technology
Authors: Maesako Mayumi , Kishimoto Takafumi , Tomoda Shigetaka , Horie Taku , Yamada Mitsuyoshi , Iwawaki Rika , Odagiri Yukari , Sakuma Keiko , Inoue Kazuho , Takeguchi Ayumi , Suzuki Miki , Mitani Akio , Fujitani Morioki
Published: December 2021

Resin composites employing structural coloration have recently been developed. These resins match to various tooth shades despite being a single paste. To accomplish this, the filler and base resin are tightly bonded, which is thought to provide excellent discoloration resistance. Here, we investigated the surface properties of one of these resins, including the discoloration of the repolished surface. We developed an innovative in vitro method to adjust the repolished surface, in which structural degradation is removed according to scanning electron microscopy (SEM) observation rather than by the naked eye. The resin samples (20 mm (length) × 10 mm (width) × 4 mm (depth)) were manufactured using this resin material. After accelerated aging of the resin by alkaline degradation, the resin was repolished and the discoloration (ΔE*ab), surface roughness (the arithmetic mean roughness (Ra)), and glossiness (the 60° specular) were measured. SEM observation showed that the appearance of the bond between the organic composite filler and base resin on the repolished surface was different from that on the mirror-polished surface. This revealed that according to our in vitro method it was difficult to make the repolished surface structurally identical to the mirror-polished surface. Among the properties of the repolished surface, the degree of discoloration did not change despite the rougher and less glossy surface. It can be concluded that the factors that induce discoloration in this resin composite are independent of the surface roughness and glossiness.
Influence of the Size of the Fiber Filler of Corn Stalks in the Polylactide Matrix Composite on the Mechanical and Thermomechanical Properties
Authors: Łączny Daniel , Macko Marek , Moraczewski Krzysztof , Szczepański Zbigniew , Trafarski Andrzej
Published: December 2021

This paper presents results of a study on the effect of filler size in the form of 15 wt% corn stalk (CS) fibers on the mechanical and thermomechanical properties of polylactide (PLA) matrix composites. In the test, polylactidic acid (PLA) is filled with four types of length of corn stalk fibers with a diameter of 1 mm, 1.6 mm, 2 mm and 4 mm. The composites were composed by single screw extrusion and then samples were prepared by injection molding. The mechanical properties of the composites were determined by static tensile test, static bending test and Charpy impact test while the thermo-mechanical properties were determined by dynamic mechanical thermal analysis (DMTA). The composite structures were also observed using X-ray microcomputed tomography and scanning electron microscopy. In the PLA/CS composites, as the filler fiber diameter increased, the degradation of mechanical properties relative to the matrix was observed including tensile strength (decrease 22.9–51.1%), bending strength (decrease 18.9–36.6%) and impact energy absorption (decrease 58.8–69.8%). On the basis of 3D images of the composite structures for the filler particles larger than 2 mm a weak dispersion with the filler was observed, which is reflected in a significant deterioration of the mechanical and thermomechanical properties of the composite. The best mechanical and thermomechanical properties were found in the composite with filler fiber of 1 mm diameter. Processing resulted in a more than 6-fold decrease in filler fiber length from 719 ± 190 µm, 893 ± 291 µm, 1073 ± 219 µm, and 1698 ± 636 µm for CS1, CS1.6, CS2, and CS4 fractions, respectively, to 104 ± 43 µm, 123 ± 60 µm, 173 ± 60 µm, and 227 ± 89 µm. The fabricated green composites with 1 to 2 mm corn stalk fiber filler are an alternative to traditional plastic based materials in some applications.
Special Issue “Metal and Metal Oxide Nanoparticles: Design, Characterization, and Biomedical Applications”
Authors: Limongi Tania
Published: December 2021

The current Special Issue entitled “Metal and Metal Oxide Nanoparticles: Design, Characterization, and Biomedical Applications” aims to present contributions from all scientists producing and/or applying metal and metal oxide nanoparticles in a diagnostic, therapeutic or theranostics context [...]
Development of a True-Biaxial Split Hopkinson Pressure Bar Device and Its Application
Authors: Pang Shumeng , Tao Weijun , Liang Yingjing , Huan Shi , Liu Yijie , Chen Jiangping
Published: December 2021

Although highly desirable, the experimental technology of the dynamic mechanical properties of materials under multiaxial impact loading is rarely explored. In this study, a true-biaxial split Hopkinson pressure bar device is developed to achieve the biaxial synchronous impact loading of a specimen. A symmetrical wedge-shaped, dual-wave bar is designed to decompose a single stress wave into two independent and symmetric stress waves that eventually form an orthogonal system and load the specimen synchronously. Furthermore, a combination of ground gaskets and lubricant is employed to eliminate the shear stress wave and separate the coupling of the shear and axial stress waves propagating in bars. Some confirmatory and applied tests are carried out, and the results show not only the feasibility of this modified device but also the dynamic mechanical characteristics of specimens under biaxial impact loading. This novel technique is readily implementable and also has good application potential in material mechanics testing.
Processing and Testing of Reinforced PA66 Based Composites
Authors: Pereira Alejandro , Tielas Alberto , Prado Teresa , Fenollera Maria , Pérez José Antonio
Published: December 2021

The new requirements in different sectors, such as aerospace, automotive and construction, for lightweight materials have led to an increase in demand for composite materials suitable for use in high rate production processes, such as plastic injection. This makes it necessary to look for matrices and reinforcements that, in addition to being compatible with each other, are also compatible with the injection process. It is in this area of research where the work presented here arises. To meet the two requirements mentioned above, this study contemplates a battery of composite materials obtained by combining PA66 and fiberglass, in different proportions and configuration, both for the preparation of the matrix and for reinforcement. For the elaboration of the matrix, two options have been evaluated, PA66 and PA66 reinforced at 35% with short glass fibre. To obtain reinforcement, six different options have been evaluated; two conventional fiberglass fabrics (each with different density) and four hybrid fabrics obtained from the previous ones by adding PA66 in different configurations (two over-stitched fabrics and two other fabrics). The different composite materials obtained were validated by means of the corresponding adhesion, peeling and resistance tests.
Boron Doped Diamond for Real-Time Wireless Cutting Temperature Monitoring of Diamond Coated Carbide Tools
Authors: Pratas Sérgio , Silva Eduardo L. , Neto Miguel A. , Fernandes Cristina M. , Fernandes António J. S. , Figueiredo Daniel , Silva Rui F.
Published: December 2021

Among the unique opportunities and developments that are currently being triggered by the fourth industrial revolution, developments in cutting tools have been following the trend of an ever more holistic control of manufacturing processes. Sustainable manufacturing is at the forefront of tools development, encompassing environmental, economic, and technological goals. The integrated use of sensors, data processing, and smart algorithms for fast optimization or real time adjustment of cutting processes can lead to a significant impact on productivity and energy uptake, as well as less usage of cutting fluids. Diamond is the material of choice for machining of non-ferrous alloys, composites, and ultrahard materials. While the extreme hardness, thermal conductivity, and wear resistance of CVD diamond coatings are well-known, these also exhibit highly auspicious sensing properties through doping with boron and other elements. The present study focuses on the thermal response of boron-doped diamond (BDD) coatings. BDD coatings have been shown to have a negative temperature coefficient (NTC). Several approaches have been adopted for monitoring cutting temperature, including thin film thermocouples and infrared thermography. Although these are good solutions, they can be costly and become impractical for certain finishing cutting operations, tool geometries such as rotary tools, as well as during material removal in intricate spaces. In the scope of this study, diamond/WC-Co substrates were coated with BDD by hot filament chemical vapor deposition (HFCVD). Scanning electron microscopy, Raman spectroscopy, and the van der Pauw method were used for morphological, structural, and electrical characterization, respectively. The thermal response of the thin diamond thermistors was characterized in the temperature interval of 20–400 °C. Compared to state-of-the-art temperature monitoring solutions, this is a one-step approach that improves the wear properties and heat dissipation of carbide tools while providing real-time and in-situ temperature monitoring.
Synthesis and Characterization of Nanoporous Carbon Carriers for Losartan Potassium Delivery
Authors: Ejsmont Aleksander , Stasiłowicz-Krzemień Anna , Ludowicz Dominika , Cielecka-Piontek Judyta , Goscianska Joanna
Published: December 2021

Losartan potassium is most commonly used for the treatment of hypertension. In recent years, new applications of this drug have emerged, encouraging the design of novel nanoporous carriers for its adsorption and release. The purpose of this study was to synthesize ordered mesoporous carbon vehicles via a soft-templating method altered with the use of nitrogen precursors and via a hard-templating method followed by chitosan functionalization. As a result, the materials obtained differed in nitrogen content as well as in the number of total surface functional groups. The impact of the modification on the physicochemical properties of carbon carriers and their interaction with losartan potassium during adsorption and release processes was examined. The materials were characterized by various morphologies, specific surface areas (101–1180 m2 g−1), and the amount of acidic/basic oxygen-containing functional groups (1.26–4.27 mmol g−1). These features, along with pore sizes and volumes, had a key effect on the sorption capacity of carbon carriers towards losartan potassium (59–161 mg g−1). Moreover, they contributed to the differential release of the drug (18.56–90.46%). Losartan potassium adsorption onto the surface of carbonaceous materials was mainly based on the formation of hydrogen bonds and π–π interactions and followed the Langmuir type isotherm. It has been shown that the choice of the method of carbon carriers’ synthesis and their modification allows for the precise control of the kinetics of the losartan potassium release from their surface, resulting in rapid or sustained drug liberation.
Additively Manufactured Commercial Co-Cr Dental Alloys: Comparison of Microstructure and Mechanical Properties
Authors: Viderščak Dalibor , Schauperl Zdravko , Šolić Sanja , Ćatić Amir , Godec Matjaž , Kocijan Aleksandra , Paulin Irena , Donik Črtomir
Published: December 2021

Laser-powder bed fusion (LPBF) is one of the preferred techniques for producing Co-Cr metal structures for dental prosthodontic appliances. However, there is generally insufficient information about material properties related to the production process and parameters. This study was conducted on samples produced from three different commercially available Co-Cr dental alloys produced on three different LPBF machines. Identically prepared samples were used for tensile, three-point bending, and toughness tests. Light microscopy (LM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) analyses of microstructure were performed after testing. Differences were observed in microstructures, which reflected statistically significant differences in mechanical properties (one-way analysis of variance (ANOVA) and Scheffé post hoc test (α = 0.05)). The material produced on the 3D Systems DMP Dental 100 had 24 times greater elongation ε than the material produced on the Sysma MySint 100 device and the EOS M100 machine. On the other hand, the material produced on the EOS M100 had significantly higher hardness (HV0.2) than the other two produced materials. However, the microstructure of the Sysma specimens with its morphology deviates considerably from the studied group. LPBF-prepared Co-Cr dental alloys demonstrated significant differences in their microstructures and, consequently, mechanical properties.
In-Depth Experimental Analysis of Influence of Electroplated Gold Thickness on Thermal and Electro-Optical Properties of mid-IR AlInAs/InGaAs/InP Quantum Cascade Lasers
Authors: Pierścińska Dorota , Pierściński Kamil , Sobczak Grzegorz , Krajewska Katarzyna , Chmielewski Krzysztof , Kuźmicz Aleksandr , Piskorski Krzysztof , Gutowski Piotr
Published: December 2021

In this paper, we have examined the influence of electroplated gold thickness on the thermal and electro-optical properties of mid-IR AlInAs/InGaAs, InP QCLs. The experimental results show a significant reduction of the temperature of QCL active region (AR) with increasing gold layer thickness. For QCLs with 5.0 μm gold thickness, we observed a 50% reduction of the active region temperature. An improvement of key electro-optical parameters, that is, threshold current density and maximum emitted power for structures with thick gold, was observed. The results of micro-Raman characterization show that the electroplated gold layer introduces only moderate compressive strain in top InP cladding, which is well below the critical value for the creation of misfit dislocations.
Investigation of Mechanical and Magnetic Properties of Co-Based Amorphous Powders Obtained by Atomization
Authors: Kuś Anna , Pilarczyk Wirginia , Małachowska Aleksandra , Ambroziak Andrzej , Gębara Piotr
Published: December 2021

Properties of Co-based alloys with high Glass Forming Ability (GFA) in the form of powder are still not widely known. However, powders of high GFA alloys are often used for the development of bulk metallic glasses by additive manufacturing. In this work Co47.6B21.9Fe20.4Si5.1Nb5% at. and Co42B26.5Fe20Ta5.5Si5Cu1% at. were developed by gas-atomization. Obtained powders in size 50–80 µm were annealed at Tg and Tx of each alloy. Then SEM observation, EDS analyses, differential thermal analysis, X-ray diffraction, nanoindentation, Mössbauer, and magnetic properties research was carried out for as-atomized and annealed states. The gas atomization method proved to be an efficient method for manufacturing Co-based metallic glasses. The obtained powder particles were spherical and chemically homogeneous. Annealing resulted in an increase of mechanical properties such as hardness and the elastic module of Co47.6B21.9Fe20.4Si5.1Nb5% at and Co42B26.5Fe20Ta5.5Si5Cu1%, which was caused by crystallization. The magnetic study shows that Co47.6B21.9Fe20.4Si5.1Nb5 and Co42B26.5Fe20Ta5.5Si5Cu1 are soft magnetic and semi-hard magnetic materials, respectively.
Development of Encapsulation Strategies and Composite Edible Films to Maintain Lactoferrin Bioactivity: A Review
Authors: Abad Inés , Conesa Celia , Sánchez Lourdes
Published: December 2021

Lactoferrin (LF) is a whey protein with various and valuable biological activities. For this reason, LF has been used as a supplement in formula milk and functional products. However, it must be considered that the properties of LF can be affected by technological treatments and gastrointestinal conditions. In this article, we have revised the literature published on the research done during the last decades on the development of various technologies, such as encapsulation or composite materials, to protect LF and avoid its degradation. Multiple compounds can be used to conduct this protective function, such as proteins, including those from milk, or polysaccharides, like alginate or chitosan. Furthermore, LF can be used as a component in complexes, nanoparticles, hydrogels and emulsions, to encapsulate, protect and deliver other bioactive compounds, such as essential oils or probiotics. Additionally, LF can be part of systems to deliver drugs or to apply certain therapies to target cells expressing LF receptors. These systems also allow improving the detection of gliomas and have also been used for treating some pathologies, such as different types of tumours. Finally, the application of LF in edible and active films can be effective against some contaminants and limit the increase of the natural microbiota present in meat, for example, becoming one of the most interesting research topics in food technology.
Material Characterisation and Computational Thermal Modelling of Electron Beam Powder Bed Fusion Additive Manufacturing of Ti2448 Titanium Alloy
Authors: Wang Qiushuang , Zhang Wenyou , Li Shujun , Tong Mingming , Hou Wentao , Wang Hao , Hao Yulin , Harrison Noel M. , Yang Rui
Published: December 2021

Ti-24Nb-4Zr-8Sn (Ti2448) is a metastable β-type titanium alloy developed for biomedical applications. In this work, cylindrical samples of Ti2448 alloy have been successfully manufactured by using the electron beam powder bed fusion (PBF-EB) technique. The thermal history and microstructure of manufactured samples are characterised using computational and experimental methods. To analyse the influence of thermal history on the microstructure of materials, the thermal process of PBF-EB has been computationally predicted using the layer-by-layer modelling method. The microstructure of the Ti2448 alloy mainly includes β phase and a small amount of α″ phase. By comparing the experimental results of material microstructure with the computational modelling results of material thermal history, it can be seen that aging time and aging temperature lead to the variation of α″ phase content in manufactured samples. The computational modelling proves to be an effective tool that can help experimentalists to understand the influence of macroscopic processes on material microstructural evolution and hence potentially optimise the process parameters of PBF-EB to eliminate or otherwise modify such microstructural gradients.
Modification Mechanism and Rheological Properties of Emulsified Asphalt Evaporative Residues Reinforced by Coupling-Modified Fiber
Authors: Lu Zhaofeng , Kong Lin , He Zhaoyi , Xu Hao , Yang Kang , Shen Zuzhen , Huang Zhaodong
Published: December 2021

In order to solve the problems of the smooth surface of basalt fiber and its weak interfacial adhesion with emulsified asphalt cold recycled mixture, a silane coupling agent (KH550) was used to treat the surface of basalt fiber and the effects of treatment concentration and soaking time on fiber modification were studied. The influence of silane coupling-modified basalt fiber (MBF) on the rheological properties of emulsified asphalt evaporation residue was studied at high and low temperatures using three routine index tests: a dynamic shear rheological test (DSR), a bending beam rheological test (BBR), and a force ductility test. The elemental changes of the fiber before and after modification and the microstructure of the emulsified asphalt evaporation residue with the coupling-modified fiber were analyzed by Fourier infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray energy dispersive spectroscopy (EDS), which is used to study the modification mechanism of emulsified asphalt evaporation residue reinforced by coupling-modified fiber. The results indicate that the concentration and soaking time of the silane coupling agent have a great influence on the surface morphology and mechanical properties of the fiber, and that the optimal treatment concentration is 1.0% and the optimal soaking time is 60 min. The addition of coupling-modified fibers can reduce the phase angle and unrecoverable creep compliance of emulsified asphalt evaporation residue, increase the rutting factor and creep recovery rate, and improve the elastic recovery ability and permanent deformation resistance. However, excessive fiber will weaken the ductility of emulsified asphalt at low temperatures. The appropriate content of silane coupling-modified fiber (MBF) is 1.5%. After silane coupling modification, the fiber surface becomes rough and cohesion is enhanced between the fiber and the emulsified asphalt base. Silane coupling-modified basalt fiber (MBF) acts as reinforcement for stability and bridging cracks.
Graphitic Carbon Nitride as a Sustainable Photocatalyst Material for Pollutants Removal. State-of-the Art, Preliminary Tests and Application Perspectives
Authors: Cecconet Daniele , Sturini Michela , Malavasi Lorenzo , Capodaglio Andrea G.
Published: December 2021

Photocatalysis is an attractive strategy for emerging pollutants remediation. Research towards the development of new, efficient and effective catalytic materials with high activity under wide irradiation spectra is a highly active sector in material science. Various semiconductor materials have been employed as photocatalysts, including TiO2, SrTiO3, CdS, BiVO4, Ta3N5, TaON, Ag3PO4, and g-C3N4. The latter is a metal-free, low cost polymer, providing high adsorption and catalytic properties, shown to be promising for photocatalysis applications under visible light. Furthermore, g-C3N4 composites are among the most promising advanced photocatalytical materials that can be produced by green synthesis processes. In this paper, the state-of-the-art of g-C3N4 applications is reviewed, and application perspectives are discussed. Photocatalysis tests with g-C3N4 under Xenon irradiation were performed to gather first-hand information to improve photoreactor design. Xenon light spectrum appears to be a suitable radiation source to replace direct sunlight in engineered pollutants removal processes catalyzed by g-C3N4, in lieu of other currently used heterogeneous photocatalysis processes (e.g., TiO2-UV). LED sources are also very promising due to higher energy efficiency and customizable, catalyzer-specific irradiation spectra.
The Development of a New Phosphogypsum-Based Construction Material: A Study of the Physicochemical, Mechanical and Thermal Characteristics
Authors: Garbaya Hela , Jraba Abderraouf , Khadimallah Mohamed Amine , Elaloui Elimame
Published: December 2021

Phosphogypsum (PG) is a waste (or by-product) of the production of phosphoric acid, a basic constituent in the manufacturing of modern fertilizers. The annual production of phosphogypsum in Tunisia is currently estimated to be 10 million tons. Its storage in slag in close proximity to production plants generates pollution problems; however, valorization may be a solution. The present paper proposes a simple process for the valorization of this by-product into a construction material. Several physicochemical characterizations are used to prove the characteristics of samples. The chemical composition shows that PG is a gypsum compound with several impurities. The morphological analyses show that the powder materials are mesoporous with a lower specific area. The structural characterizations show that these solids play the role of a water pump as the degree of hydration changes from 2 to 0 and vice versa, depending on the temperature. Mechanical and thermal analyses show that the prepared formulation is brittle and insulating, which presents opportunities for it to be used as a decoration material.
Drawing System with Dobot Magician Manipulator Based on Image Processing
Authors: Tsai Pu-Sheng , Wu Ter-Feng , Chen Jen-Yang , Lee Fu-Hsing
Published: December 2021

In this paper, the robot arm Dobot Magician and the Raspberry Pi development platform were used to integrate image processing and robot-arm drawing. For this system, the Python language built into Raspberry Pi was used as the working platform, and the real-time image stream collected by the camera was used to determine the contour pixel coordinates of image objects. We then performed gray-scale processing, image binarization, and edge detection. This paper proposes an edge-point sequential arrangement method, which arranges the edge pixel coordinates of each object in an orderly manner and places them in a set. Orderly arrangement means that the pixels in the set are arranged counterclockwise to the closed curve of the object shape. This arrangement simplifies the complexity of subsequent image processing and calculation of the drawing path. The number of closed curves represents the number of strokes in the drawing of the manipulator. In order to reduce the complexity of the drawing of the manipulator, a fewer number of closed curves will be necessary. To achieve this goal, we not only propose the 8-NN (abbreviation for eight-nearest-neighbor) search, but also use to the 16-NN search and the 24-NN search methods. Drawing path points are then converted into drawing coordinates for the Dobot Magician through the Raspberry Pi platform. The structural design of the Dobot reduces the complexity of the experiment, and its attitude and positioning control can be accurately carried out through the built-in API function or the underlying communication protocol, which is more suitable for drawing applications than other fixed-point manipulators. Experimental results show that the 24-NN search method can effectively reduce the number of closed curves and the number of strokes drawn by the manipulator.
Prediction of Abrasive Belt Wear Based on BP Neural Network
Authors: Cao Yuanxun , Zhao Ji , Qu Xingtian , Wang Xin , Liu Bowen
Published: December 2021

Abrasive belt grinding is the key technology in high-end precision manufacturing field, but the working condition of abrasive particles on the surface of the belt will directly affect the quality and efficiency during processing. Aiming at the problem of the inability to monitor the wearing status of abrasive belt in real-time during the grinding process, and the challenge of time-consuming control while shutdown for detection, this paper proposes a method for predicating the wear of abrasive belt while the grinding process based on back-propagation (BP) neural network. First, experiments are carried out based on ultra-depth-of-field detection technology, and different parameter combinations are used to measure the degree of abrasive belt wear. Then the effects of different grinding speeds, different contact pressures, and different work piece materials on the abrasive belt wear rate are obtained. It can be concluded that the abrasive belt wear rate gradually increases as the grinding speed of the abrasive belt increases. With the increase of steel grade, the hardness of the steel structure increases, which intensifies the abrasive belt wear. As the contact pressure increases, the pressure on a single abrasive particle increases, which ultimately leads to increased wear. With the increase of contact pressure, the increase of the wear rate of materials with higher hardness is greater. By utilizing the artificial intelligence BP neural network method, 18 sets of experiment data are used for training BP neural network while 9 sets of data are used for verification, and the nonlinear mapping relationship between various process parameter combinations such as grinding speed, contact pressure, workpiece material, and wear rate is established to predict the wear degree of abrasive belt. Finally, the results of verification by examples show that the method proposed in this paper can fulfill the purpose of quickly and accurately predicting the degree of abrasive belt wear, which can be used for guiding the manufacturing processing, and greatly improving the processing efficiency.
Optimization of Sweep and Blade Lean for Diffuser to Suppress Hub Corner Vortex in Multistage Pump
Authors: Ning Chao , Cao Puyu , Gong Xuran , Zhu Rui
Published: December 2021

The bowl diffuser is the main flow component in multistage submersible pumps; however, secondary flow fields can easily induce a separation vortex in the hub corner region of the bowl diffuser during normal operation. To explore the flow mechanism of the hub corner separation vortex and develop a method for suppressing hub corner separation vortices, the lean and sweep of the diffuser blade were optimized using computational fluid dynamics (CFD) simulations and central composite design. Diffuser efficiency, static pressure recovery coefficient, and non-uniformity were selected as the optimization objectives. Details of the internal flow were revealed and the collaborative response relationships between blade lean/sweep parameter equations and optimization objectives were established. The optimization results show that a greater pressure difference between the pressure surface and suction surface (PS–SS) at the inlet can offset transverse secondary flow, whereas a lower PS–SS pressure difference will cause a drop in low-energy fluid in the diffuser mid-section. The blade’s lean scheme suppresses the hub corner separation vortex, leading to an increase in pressure recovery and diffuser efficiency. Moreover, optimizing the sweep scheme can reduce the shroud–hub pressure difference at the inlet to offset spanwise secondary flow and enhance the hub–shroud pressure difference at the outlet, thus driving low-energy fluid further downstream. The sweep scheme suppresses the hub corner vortex, with a resulting drop in non-uniformity of 13.1%. Therefore, optimization of the diffuser blade’s lean and sweep can result in less low-energy fluid or drive it further away from hub, thereby suppressing the hub corner vortex and improving hydraulic performance. The outcomes of this work are relevant to the advanced design of bowl diffusers for multistage submersible pumps.
Formation Control of Dual Auto Guided Vehicles Based on Compensation Method in 5G Networks
Authors: Wang Liuquan , Liu Qiang , Zang Chenxin , Zhu Sanying , Gan Chaoyang , Liu Yanqiang
Published: December 2021

With commercial application of 5G networks, many researchers have started paying attention to real-time control in 5G networks. This paper focuses on dual auto guided vehicles collaborative transport scenarios and designs a formation control system in current commercial 5G networks. Firstly, the structure of the 5G network researched in this paper is introduced. Then the round-trip time of 5G networks is measured and analyzed. The result shows that although the 5G round-trip time has randomness, it is mainly concentrated in 19 ± 3 ms, and the jitter mainly in 0 ± 3 ms. The Kalman filter is applied to estimate the transmission delay and experiment result shows the effectiveness of the estimation. Furthermore, the total delay including transmission delay and execution delay in control system is discussed. After establishing the AGV kinematic and formation model, complete control system based on compensation method is proposed. Finally, an experiment is carried out. Compared to the result without formation control, maximum distance error is reduced by 82.61% on average, while maximum angle error 45.91% on average. The result shows the effectiveness of the control system in formation maintaining in 5G network.
Design and Comparison of Reinforcement-Learning-Based Time-Varying PID Controllers with Gain-Scheduled Actions
Authors: Yeh Yi-Liang , Yang Po-Kai
Published: December 2021

This paper presents innovative reinforcement learning methods for automatically tuning the parameters of a proportional integral derivative controller. Conventionally, the high dimension of the Q-table is a primary drawback when implementing a reinforcement learning algorithm. To overcome the obstacle, the idea underlying the n-armed bandit problem is used in this paper. Moreover, gain-scheduled actions are presented to tune the algorithms to improve the overall system behavior; therefore, the proposed controllers fulfill the multiple performance requirements. An experiment was conducted for the piezo-actuated stage to illustrate the effectiveness of the proposed control designs relative to competing algorithms.
Kineto-Static Analysis and Design Optimization of a 3-DOF Wrist Rehabilitation Parallel Robot with Consideration of the Effect of the Human Limb
Authors: Liu Ying-Chi , Irube Kosuke , Takeda Yukio
Published: December 2021

When designing rehabilitation robots, there remains the challenge of ensuring the comfort and safety of users, especially for wearable rehabilitation robots that interact with human limbs. In this paper, we present a kineto-static analysis of the 3-RPS parallel wrist rehabilitation robot, taking into account the soft characteristics of the human limb and its kinematic mobility. First, the human upper-limb model was made to estimate the interaction force and moment through inverse kinematic analysis. Second, a static analysis was conducted to obtain the force and moment acting on the human limb, which is directly related to the user’s comfort and safety. Then, the design parameters of the 3-RPS robot were obtained by generic optimization through kineto-static analysis. Finally, the influence of the parasitic motion of the 3-RPS robot and the initial offset between the wrist center and the robot moving platform were discussed. Through the analysis results, we provide effective solutions to ensure the safety and comfort of the user.
Iterative Learning Control for AGV Drive Motor Based on Linear Extended State Observer
Authors: Jiang Wei , Zhu Gang , Zheng Ying
Published: December 2021

In order to solve the problems of repetitive and non-repetitive interference in the workflow of Automated Guided Vehicle (AGV), Iterative Learning Control (ILC) combined with linear extended state observer (LESO) is utilized to improve the control accuracy of AGV drive motor. Considering the working conditions of AGV, the load characteristics of the drive motor are analyzed with which the mathematical model of motor system is established. Then the third-order extended state space equations of the system approximate model is obtained, in which LESO is designed to estimate the system states and the total disturbance. For the repeatability of AGV workflow, ILC is designed to improve the control accuracy. As the goods mass transported each time is not same, the LESO is utilized to estimate the non-repetitive load disturbance in real time and compensate the disturbance of the system to improve the position precision. The convergence of the combined algorithm is also verified. Simulation and experimental results show that the proposed iterative learning control strategy based on LESO can reduce the positioning error in AGV workflow and improve the system performance.
Perspectives on Molecular Materials—A Tribute to Professor Peter Day
Authors: Martin Lee , Turner Scott S. , Wallis John D. , Akutsu Hiroki , Gómez-García Carlos J.
Published: December 2021

Professor Peter Day FRS was born on 20 August 1938 in Kent (UK) and attended Maidstone Grammar School [...]
Ferromagnetic Resonance of a [GeTe/Sb2Te3]6/Py Superlattice
Authors: Sumi Satoshi , Hirano Yuichiro , Awano Hiroyuki , Tominaga Junji
Published: December 2021

A [GeTe/Sb2Te3] superlattice is known as a topological insulator. It shows magnetic responses such as magneto-optical effect, magneto resistance, magneto capacitance, and so on. We have reported that [GeTe/Sb2Te3] superlattice film has a large spin–orbit interaction using a spin pumping method of a [GeTe/Sb2Te3]/Py superlattice. In this paper, we demonstrate a ST-FMR (spin transfer torque ferromagnetic resonance) of the [GeTe/Sb2Te3]6/Py superlattice, compared with a W/Py bilayer. The superlattice film showed a large resonance signal with a symmetric component. The ratio of symmetric components (S) to anti-symmetric (A) components (S/A) was 1.4, which suggests that the superlattice exhibits a large spin Hall angle. The [GeTe/Sb2Te3] superlattice will be suitable as a hetero-interface material required for high performance spintronics devices in future.
Propagation of the Malware Used in APTs Based on Dynamic Bayesian Networks
Authors: Hernandez Guillen Jose D. , Martin del Rey Angel , Casado-Vara Roberto
Published: December 2021

Malware is becoming more and more sophisticated these days. Currently, the aim of some special specimens of malware is not to infect the largest number of devices as possible, but to reach a set of concrete devices (target devices). This type of malware is usually employed in association with advanced persistent threat (APT) campaigns. Although the great majority of scientific studies are devoted to the design of efficient algorithms to detect this kind of threat, the knowledge about its propagation is also interesting. In this article, a new stochastic computational model to simulate its propagation is proposed based on Bayesian networks. This model considers two characteristics of the devices: having efficient countermeasures, and the number of infectious devices in the neighborhood. Moreover, it takes into account four states: susceptible devices, damaged devices, infectious devices and recovered devices. In this way, the dynamic of the model is SIDR (susceptible–infectious–damaged–recovered). Contrary to what happens with global models, the proposed model takes into account both the individual characteristics of devices and the contact topology. Furthermore, the dynamics is governed by means of a (practically) unexplored technique in this field: Bayesian networks.
On the Estimation of the Initial Stock in the Problem of Resource Extraction
Authors: Tur Anna , Gromova Ekaterina , Gromov Dmitry
Published: December 2021

We consider a differential game of non-renewable resource extraction, in which the players do not know the precise value of the resource stock and, thus, have to make an estimate. We define the value of information about the initial stock and give recommendations for the choice of the estimate depending on the parameters of the problem. Further, we consider the situation where the players only know the bounds for the stock of the resource and solve the problem of computing the optimal estimate, such that it minimizes the players’ losses in the worst-case scenario. The analysis allows us to give a simple rule for the choice of the optimal estimate of the resource stock.
Selection of Culture Conditions and Cell Morphology for Biocompatible Extraction of β-Carotene from Dunaliella salina
Authors: Tanguy Guillaume , Legat Aline , Gonçalves Olivier , Marchal Luc , Schoefs Benoît
Published: December 2021

Biocompatible extraction emerges recently as a means to reduce costs of biotechnology processing of microalgae. In this frame, this study aimed at determining how specific culture conditions and the associated cell morphology impact the biocompatibility and the extraction yield of β-carotene from the green microalga Dunaliella salina using n-decane. The results highlight the relationship between the cell disruption yield and cell volume, the circularity and the relative abundance of naturally permeabilized cells. The disruption rate increased with both the cell volume and circularity. This was particularly obvious for volume and circularity exceeding 1500 µm3 and 0.7, respectively. The extraction of β-carotene was the most biocompatible with small (600 µm3) and circular cells (0.7) stressed in photobioreactor (30% of carotenoids recovery with 15% cell disruption). The naturally permeabilized cells were disrupted first; the remaining cells seems to follow a gradual permeabilization process: reversibility (up to 20 s) then irreversibility and cell disruption. This opens new carotenoid production schemes based on growing robust β-carotene enriched cells to ensure biocompatible extraction.
In Silico Prediction of Steroids and Triterpenoids as Potential Regulators of Lipid Metabolism
Authors: Dembitsky Valery M.
Published: December 2021

This review focuses on a rare group of steroids and triterpenoids that share common properties as regulators of lipid metabolism. This group of compounds is divided by the type of chemical structure, and they represent: aromatic steroids, steroid phosphate esters, highly oxygenated steroids such as steroid endoperoxides and hydroperoxides, α,β-epoxy steroids, and secosteroids. In addition, subgroups of carbon-bridged steroids, neo steroids, miscellaneous steroids, as well as synthetic steroids containing heteroatoms S (epithio steroids), Se (selena steroids), Te (tellura steroids), and At (astatosteroids) were presented. Natural steroids and triterpenoids have been found and identified from various sources such as marine sponges, soft corals, starfish, and other marine invertebrates. In addition, this group of rare lipids is found in fungi, fungal endophytes, and plants. The pharmacological profile of the presented steroids and triterpenoids was determined using the well-known computer program PASS, which is currently available online for all interested scientists and pharmacologists and is currently used by research teams from more than 130 countries of the world. Our attention has been focused on the biological activities of steroids and triterpenoids associated with the regulation of cholesterol metabolism and related processes such as anti-hyperlipoproteinemic activity, as well as the treatment of atherosclerosis, lipoprotein disorders, or inhibitors of cholesterol synthesis. In addition, individual steroids and triterpenoids were identified that demonstrated rare or unique biological activities such as treating neurodegenerative diseases, Alzheimer’s, and Parkinson’s diseases with a high degree of certainty over 95 percent. For individual steroids or triterpenoids or a group of compounds, 3D drawings of their predicted biological activities are presented.
ACE Inhibitory Peptide from Skin Collagen Hydrolysate of Takifugu bimaculatus as Potential for Protecting HUVECs Injury
Authors: Cai Shuilin , Pan Nan , Xu Min , Su Yongchang , Qiao Kun , Chen Bei , Zheng Bingde , Xiao Meitian , Liu Zhiyu
Published: December 2021

Angiotensin-I-converting enzyme (ACE) is a crucial enzyme or receptor that catalyzes the generation of potent vasopressor angiotensin II (Ang II). ACE inhibitory peptides from fish showed effective ACE inhibitory activity. In this study, we reported an ACE inhibitory peptide from Takifugu bimaculatus (T. bimaculatus), which was obtained by molecular docking with acid-soluble collagen (ASC) hydrolysate of T. bimaculatus. The antihypertensive effects and potential mechanism were conducted using Ang-II-induced human umbilical vein endothelial cells (HUVECs) as a model. The results showed that FNLRMQ alleviated the viability and facilitated apoptosis of Ang-II-induced HUVECs. Further research suggested that FNLRMQ may protect Ang-II-induced endothelial injury by regulating Nrf2/HO-1 and PI3K/Akt/eNOS signaling pathways. This study, herein, reveals that collagen peptide FNLRMQ could be used as a potential candidate compound for antihypertensive treatment, and could provide scientific evidence for the high-value utilization of marine resources including T. bimaculatus.
Sulfo-Gambierones, Two New Analogs of Gambierone Produced by Gambierdiscus excentricus
Authors: Yon Thomas , Sibat Manoëlla , Robert Elise , Lhaute Korian , Holland William C. , Litaker R. Wayne , Bertrand Samuel , Hess Philipp , Réveillon Damien
Published: December 2021

Ciguatera poisoning is caused by the ingestion of fish or shellfish contaminated with ciguatoxins produced by dinoflagellate species belonging to the genera Gambierdiscus and Fukuyoa. Unlike in the Pacific region, the species producing ciguatoxins in the Atlantic Ocean have yet to be definitely identified, though some ciguatoxins responsible for ciguatera have been reported from fish. Previous studies investigating the ciguatoxin-like toxicity of Atlantic Gambierdiscus species using Neuro2a cell-based assay identified G. excentricus as a potential toxin producer. To more rigorously characterize the toxin profile produced by this species, a purified extract from 124 million cells was prepared and partial characterization by high-resolution mass spectrometry was performed. The analysis revealed two new analogs of the polyether gambierone: sulfo-gambierone and dihydro-sulfo-gambierone. Algal ciguatoxins were not identified. The very low ciguatoxin-like toxicity of the two new analogs obtained by the Neuro2a cell-based assay suggests they are not responsible for the relatively high toxicity previously observed when using fractionated G. excentricus extracts, and are unlikely the cause of ciguatera in the region. These compounds, however, can be useful as biomarkers of the presence of G. excentricus due to their sensitive detection by mass spectrometry.
Marine Indole Alkaloids—Isolation, Structure and Bioactivities
Authors: Hu Yong , Chen Siling , Yang Fang , Dong Shuai
Published: December 2021

Indole alkaloids are heterocyclic natural products with extensive pharmacological activities. As an important source of lead compounds, many clinical drugs have been derived from natural indole compounds. Marine indole alkaloids, from unique marine environments with high pressure, high salt and low temperature, exhibit structural diversity with various bioactivities, which attracts the attention of drug researchers. This article is a continuation of the previous two comprehensive reviews and covers the literature on marine indole alkaloids published from 2015 to 2021, with 472 new or structure-revised compounds categorized by sources into marine microorganisms, invertebrates, and plant-derived. The structures and bioactivities demonstrated in this article will benefit the synthesis and pharmacological activity study for marine indole alkaloids on their way to clinical drugs.