bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability analysis of constrained L1 inversion of gravity data for estimating discontinuous basement relief
Authors: Li Jiawei , Liang Qing
Published: February 2021

L1 inversion of gravity data is widely used to estimate the discontinuous relief of basement. We used the L1 inversion method to recover a complex model with faults, a smooth feature, and a V-shaped interface. The noise of data, the constraints with errors and the incorrect density contrast are considered in the stability analysis of inversion. The results show that the constrained L1 inversion of gravity data is stable and efficient for complex discontinuous relief of basement.
A Multi-scale Inversion Method Based on Convolutional Wavelet Transform Applied in Cross-Hole Resistivity Electrical Tomography
Authors: Pang Yonghao , Liu Zhengyu , Wang Ning , Nie Lichao , Wang Huaihong
Published: February 2021

With the increasing demand for fine exploration, there is also a growing demand on the use of the cross-hole electrical resistivity tomography (ERT). However, the boundaries of geological bodies cannot be accurately described when traditional smooth constraint method was adopted. To solve this problem, we studied a multi-scale inversion method based on convolution wavelet transform. The finite element method is used in the modeling process. The imaging effects of numerical simulation are discussed, such as a single rectangular target, two rectangular targets, Irregular targets, and layered models. The effectiveness of multi-scale methods in cross-hole ERT has been revealed in this work.
Rayleigh Wave Reconstruction from Ambient Noise Cross-Correlation Function by Radon-Wigner Transform
Authors: Li Xinxin , Xu Cheng , Shen Hongyan
Published: February 2021

The ambient noise tomography is a powerful underground-structure-detection method developed in recent years. The key of this technique is to extract Rayleigh-wave signals from cross-correlation functions (CCF). It is important to suppress the noise in Rayleigh wave signals to increase the accuracy of dispersion-curve extraction. In this paper, a Radon-Wigner Transform (RWT) method is used for Rayleigh-wave reconstruction from CCF. We first introduce the principles of RTW, and then use a multi-component synthetic seismic data to show the processing steps of RWT. Finally, we process actual ambient noise CCF with RWT to reconstruct Rayleigh waves. The results of the synthetic and actual data examples indicate that RWT successfully reconstructed the Rayleigh waves from CCF and improved the signal-to-ratio of the signal.
Groundwater Flow Monitoring via Joint Time-lapse Electrical Resistivity and Self Potential Data Tomography
Authors: Bai Lige , Li Jing , Zeng Zhaofa
Published: February 2021

Revealing the dynamics of groundwater movement in the vadose zone is crucial to groundwater management and artificial recharge development. In this study, the groundwater flow characterization of the pumping process is monitored by the time-lapse electrical resistivity tomography (ERT) and self-potential (SP)data tomography. The ERT data invert the resistivity distribution. Then, we combine the SP data and resistivity result to invert the apparent current density and estimate the permeability based on the Poisson equation. A total of 24 hours of time-lapse surveys are taken during the pumping and recharge of groundwater. The results show a significant increase in in resistivity and permeability during pumping water, which suggests groundwater drawdown. Similarly, significant decrease resistivity and permeability are observed during the recovery indicating groundwater recharge. These results have a significant agreement with the groundwater table monitoring result. Our experiment test suggests that combine ERT and SP data could provide a reliable way in groundwater or other hydrogeological surveys.
The application on the towed-type shallow high-accuracy seismic detection for coastal tidal flats
Authors: Yue Hangyu , Zhang Baowei , Wang Kai , Wang Xiaojiang , Zhang Kai , Wang Guangke
Published: February 2021

Restricted by the geological exploration equipment and tidal time, the deep seismic detection technology with large offset for exploration of oil and gas resources is often used in the seismic survey of the coastal tidal flats. Furthermore, the coastal tidal flats are only treated as the transition belt of the paralic zone, resulting in the low degree of geological exploration and low detection accuracy, which cannot meet the requirement for high-accuracy exploration in the coastal tidal flats. Conventional shallow seismic exploration technology can detect effectively the bottom interface and internal horizon of the shallow Quaternary system in the coastal tidal flats, but the equipment for data acquisition is complex, and the acquisition efficiency is low, restricting directly the seismic exploration in the coastal tidal flats. Therefore, a shallow high-accuracy seismic detection technology has been developed in this study, which is suitable for the coastal tidal flats. By making full use of the characteristics of the flat terrain in the coastal tidal flats, the method for towed data acquisition has been used, and the seismic detection equipment has been simplified in the tidal flats. With this method, the exploration cost has been reduced, and the data acquisition efficiency has been improved. The detection accuracy can reach the level of meters, and the detection depth is more than 800m with this method. With this technology, the shallow stratigraphic structure and interface in the coastal tidal flats can be detected effectively, and the location of paleochannels, concealed faults and shallow gas can be determined, which support effectively the geological survey of the coastal zone and offshore engineering, being of great practical significance for scientific disaster prevention and mitigation.
Study of mm-Wave Scattering of Roadside Targets for Vehicular Road Departure Detection Applications
Authors: Yu Yue , Feng Xuan , Liu Cai
Published: February 2021

The main objectives of this study were characterizing the radar scattering properties of common highway roadside objects in 24 GHz and 77 GHz bands. So far, we have developed measurement methodology and studied scattering properties of concrete curb and concrete. This paper focused on collecting initial scattering data of roadside objects under stationary. The measurements were conducted at 24 GHz with 1 GHz bandwidth using a commercial software-defined radar (SDR) manufactured by Ancortek. These measurements were mainly conducted for understanding the general scatting strength and measurement setup requirements, and were not for detail characterization of the radar cross section (RCS) properties. We also measured the reflection coefficient of concrete for spaying water. In preparation for fabricating roadside surrogates, we also began to measure the reflectivity of several conductive fabric in our possession to determine if any of them could be suitable for dressing the roadside surrogates for producing similar reflectivity as the surface of selected representative roadside objects.
One-dimensional constrained inversion of electrical source transient electromagnetic method
Authors: Nai Guoru , Wang Xuben , Xie Zhuoliang , Chen Xianjie , Liu Wei
Published: February 2021

The damped least squares inversion principle is applied to the transient electromagnetic one-dimensional inversion of electrical sources, and a new model is obtained by continuously iterating the initial model, thereby fitting the observed transient electromagnetic response, and performing one-dimensional inversion through induced electromotive force play. In the damped least squares inversion, constraints are added to the Jacobian matrix, and simultaneous constraint equations and conventional inversion equations are solved. By weighting the constraint parameters, the difference between adjacent resistivities and layer thicknesses is minimized. Finally, K-type and H-type theoretical models were used to verify the reliability of the algorithm, and compared with the conventional transient electromagnetic damping least squares inversion.
Mapping complex reservoir targets by electromagnetic multi-attributes
Authors: He Zhanxiang , Dong Weibin , Shen Yibin , Shi Yanlin , Zhao Yunsheng , Cao Yang
Published: February 2021

In development of oil and gas exploration, complex reservoirs have become a key problem for increasing production capacity. It is of great significance to develop novel technologies for reservoir prediction and evaluation. Non-seismic methods such as time-frequency electromagnetics and well-ground electromagnetics have been applied to the study of complex reservoirs, oil and gas detection methods of electromagnetic properties based on the analysis of dispersion characteristics and a method of oil and gas target identification based on complex resistivity equivalent models have been proposed and the method of inversion of electromagnetic properties of complex reservoirs using the well-ground multi-scale sequential constraint inversion method, etc., introduces the actual profiles applied to the development of exploration of igneous rocks and complicated fault-block lithological reservoirs. It provides an effective method for oil and gas detection of knew hydrocarbon traps in complex targets of oil and gas.
Inversion of Fracture Parameters in Anisotropic Coal Seam
Authors: Li Qin , Wang Wei , Ma Suibo , Zhao Bin
Published: February 2021

Inversion of coal seam fracture parameters is of great significance to identify and predict the distribution state of coal seam fractures, and also provides certain theoretical support for the detection and identification of coalbed methane. According to the formula of PP wave reflection coefficient, this paper uses genetic algorithm to carry out inversion of coal seam fracture parameters and Thomsen anisotropy parameters, and analyzes the accuracy and stability of inversion results. The results show that the genetic algorithm has high inversion accuracy for density, shear wave velocity and fracture density of background medium, and has certain reference significance for fracture identification.
Application of electrical resistivity tomography (ERT) in archaeological investigation of Chengsijiazi Ancient City ruins
Authors: Xin Zhonghua , Liu Lijia , Han Jiangtao , Liang Huili
Published: February 2021

The electrical resistivity tomography (ERT) has the characteristics of low cost, high efficiency, rich information, non-destructive exploration, and large detection depth. At present, it is being widely used in archaeological exploration. It can provide a more accurate result whether it is the preliminary survey delineation or the later detailed exploration. Chengsijiazi ancient city, located at the bank of Tao’er river, was built during the Liao and Jin dynasties. Except for the western wall destroyed by the river, the rest of the city walls were well preserved. The main target body of this survey is a part of wall foundation of an ancient building in the ancient city ruins. The ERT data are acquired along 55 survey lines and the horizontal differential field line method is introduced to interpret the inversion results of the measurement data. The horizontal differential field line method could more accurately describe the structure and boundary characteristics of the target body. The ancient building wall foundation is characterized by obvious high-gradient dense field line, so that we can accurately delineates the position of the wall base, which was excavated by archaeologists and has been verified.
Characteristic of Fault Structures in the south coastal Zone of Taizhou Based on High-Precision Aeromagnetic Data
Authors: Wang Ming , Lin Xiaoxing , Li Jiaojiao , Zhang Yongjun
Published: February 2021

The south coastal zone of Taizhou lies on the magmatic rock belt of southeast coast of China, which has complex regional geological structure, intense tectonic movement and frequent magmatic activities. Based on the latest high-precision aeromagnetic data, integrated interpretation was completed, combining with regional geology, regional gravity and magnetic susceptibility information. According to the block features in different zones of the RTP aeromagnetic data, the magnetic field characteristics and the relationship with the structure division were described in detail. It showed that the different characteristics of magnetic field is the concentrated reflection such as tectonic movement, magmatic activity and stratigraphic distribution, and the fault structure was inferred and studied, especially the deep and large fault structures. The fault structures were mainly distributed in NE, NNE and NW direction, with approximately equal spacing distribution. The magnetic anomaly is mainly characterized by the boundary, gradient zones and beaded anomalies in different magnetic field. The faults act not only as the important tectonic boundaries in this region, but also the important tectonic belts, controlling the distribution of mineralization. Under the interaction of these faults, they form the basic structural pattern of East-West zone and North-South block; Among them, the NE faults have the largest scale and obviously control over different magnetic field and magmatic activity. The results presented in the paper can provide reference for further study on the distribution and activity characteristics of magmatic rocks in the coastal zone.
Single weighted laterally constrained inversion of airborne transient electromagnetic data with sharp boundary
Authors: Lu Juntao , Lei Da , Zhang You , Zheng Fanghua
Published: February 2021

Traditional laterally constrained inversion (LCI) can quickly and efficiently invert large geophysical data with minimizing the difference between adjacent model parameters. However when processing the data with large boundary differences, the inversion generates the result whoes the boundaries are poorly fitness with the actual underground geology. In order to overcome this problem, some specific measurement stations of original LCI has been adjusted to weaken the horizontal continuity constraint of the horizontal direction near the sharp boundary. The simulation results show that the determinations of station and weights value depend on the thickness or depth change at sharp boundary. In this paper, we employed single weighted laterally constrained inversion (SWLCI) method on the model with sharp boundary. The result showed that SWLCI can improve both the recovering of sharp boundary and the stability of inversion.
Numerical modelling for elastic wave equations including rotational deformation and strain gradient
Authors: Wang Zhiyang , Chen Chaopu , Li Youming , Liu Hong , Bai Wenlei
Published: February 2021

In this work, through introducing the first and second derivatives of strain gradient into the strain energy density function that depends only on the classical strain in conventional continuum mechanics theory to describe the microscopic interactions, the elastic wave equations including rotational deformation and strain gradient based on the Aifantis’s strain gradient theory is derived. The elastic wave equations including rotational deformation and strain gradient with consideration of the scale effects caused by the microscopic interactions will make seismograms appear obvious changes, which are reflected in amplitude attenuation and dispersion, especially P-wave and S-wave propagate in a dispersive manner based on this theory. The results of numerical modelling and theoretical analysis verify this conclusion. The closer the wavelength is to the characteristic scale of the media (lattice size and interparticle distance), the macroscopic response which results from the microscopic interactions becomes more prominent. To further study the effects of microstructure interactions, we compare the results of numerical modelling with the real data when high-speed train passed the piers in Dingxing County in both time and frequency domains, some conclusions are drawn from the comparison.
Residual stress analysis of friction stir welded AA6063 pipe butt joint by neutron diffraction technique of ENGIN-X
Authors: Ismail Azman , Lee Tung Lik , Awang Mokhtar , Rahman Fauziah Ab , Salih Nabihah , Baharudin Bakhtiar Ariff , Khalid Puteri Zarina Megat , Hamid Darulihsan Abdul
Published: February 2021

Residual stress refers to stress that remains in a structure when all applied stresses have been removed. It is important because the combination with applied stress can cause failure at the level below at which the failure could occur. A study has been carried out using the non-destructive neutron diffraction (ND) technique of ENGIN-X to quantify the redistribution of residual stresses in a pipe. A three-dimensional residual stress-measurements test is fully performed on a 89 mm (3.5 in) diameter pipe in AA6063 grade aluminium (5 mm wall thickness) containing a girth friction stir weld. The results have shown an opposite residual stress effect due to tool rotational speed increment especially on the retreating side of the weld. This weld residual stress analysis is an important factor for Fitness-For-Purpose Assessments. This residual stress measurement data provides a basis for structural integrity assessment and inspection planning.
Fabrication and characterization of epoxy resin–barium titanate at G-band using waveguide technique
Authors: Hasan Nurulfadzilah , Hussain Nur Shahira Mat , Razak Nur Hazimah Syazana Abdul , Shah Ahmad Syahiman Mohd , Karim Mohamad Shaiful Abdul
Published: February 2021

In this paper, fabrication process of epoxy resin-barium titanate nanocomposite and measurement of its complex permittivity are presented. The material is prepared by mechanical mixing of epoxy resin and barium titanate nanopowder. The nanocomposite is intended to be used as high permittivity microstrip antenna substrate, which requires accurate measurement of its electrical characteristics. Thus, characterization of materials is done using waveguide technique, which does not require a precise machining of sample’s width and thickness, and does not utilize small reflection coefficient, which can cause error in measurement. The complex permittivity of the nanocomposite is measured in G-band (4 to 6 GHz). Then, the measured values are compared with prediction method, Lichtnecker and Maxwell-Garnet method. The results show that the measured permittivity of composite materials are in good range with prediction method, while the measurements of loss tangent show that the developed materials are low-loss and suitable to be used as substrate of antenna.
Thermal analysis of a Thermoelectric Generator (TEG) using FEM technique
Authors: Prajwal K T , Bhat Pritam
Published: February 2021

Finite Element Method (FEM) is one of the numerical technique based on minimization of energy, developed to solve complex engineering problems by converting governing differential equations of the physical phenomenon into algebraic equations that can be easily solved by a computer. Finite Element Analysis (FEA) is a computer application that uses FEM technique to analyze the physics of given problem based on the user inputs provided such as material data, geometry, and other pre requisites to study the behavior and structural strength in case of structural mechanics. A device working on principle of Seebeck-Thomson effect is Thermoelectric Generator (TEG) that converts the difference of heat energy into electrical energy. Thermal analysis of a TEG is a necessary step in design engineering as the electricity generated by the device is dependent on the difference in heat flux (temperature difference) between the source and sink (two ends) of TEG. In this paper, Finite Element Analysis of Thermoelectric Generator is carried out. The model is constructed, and thermal analysis is carried out in this paper.
Investigating the fast cooling process of silicene by MD simulation
Authors: On Vo Van , Hung Nguyen Thanh , Huyen Dang Thi Khanh , Trinh Le Thi Phuong
Published: February 2021

This paper presents the results of two-dimensional silicene cooling studies by MD simulation with a sample of 6400 atoms. Silicene after melting to 3500K, it is cooled at a rate of 1013K/s to a temperature of 300K. Investigation of the dependence of energy on temperature shows a jump in the average total energy of molten silicene at the temperature T = 1772K. Investigations on the radial distribution function g(r), coordinate number distribution, ring distribution, and angular distribution all show that the freezing temperature of silicene is about 1772K. When cooled to 300K, silicene is in crystalline form, but the ratio of the defects is quite high and approximately 37.5%.
Cold forging of silicon carbide particulate (SiCp) reinforced aluminium metal matrix composite preforms
Authors: Agrawal M , Singh S
Published: February 2021

The present paper investigate the forging of Aluminium metal matrix composite with Silicon Carbide particles (SiCp) as reinforcements. The generic shaped preform specimens were forged under cold conditions (room temperature) using open-die sets. The Aluminium metal matrix composite material under consideration was fabricated via liquid stir casting manufacturing route, where the pre-heated Silicon Carbide particles were mixed with the molten Aluminium casting alloy. The preforms with standard dimensions were machined obtained from the cast. To analysis the deformation characteristics, two different generic shapes of the preform were considered, i.e. disc and rectangular shape preforms. The present paper presents both theoretical (based on ‘Upper Bound’ approach) and experimental investigations, where theoretical analysis considers a modified interfacial frictional law and preform free barreling. It is expected that the present work will be useful to assess various deformation characteristics during forging of metal matrix composites.
Design and vlsi implementation of a decimation filter for hearing aid applications
Authors: Purushothaman V , Rama devi R , Manjula S
Published: February 2021

Roughly 10% of the total common people experience some kind of hearing misfortune, yet just little level of this measurement utilize the portable amplifier. The shame related with wearing a portable amplifier, client disappointment with listening device execution, the expense and the battery life. Using computerized signal handling the advanced portable amplifier currently offers what the simple listening device can't offer. As of now low power VLSI design is more preferable in digital designs. More and more individuals around the globe experience the ill effects of hearing misfortunes. The expanding normal age and the developing populace are the principle explanations behind this. The pulverization channel utilized for portable amplifier is planned and executed both in MATLAB and Very High Speed Integrated Circuit Hardware Description Language. The obliteration channel is structured utilizing the circulated number-crunching multiplier in Very High Speed Integrated Circuit Hardware Description Language. Each computerized channel structure is reproduced utilizing Matlab and its total engineering is caught utilizing Simulink. The subsequent engineering is equipment productive and expends less force contrasted with traditional decoding channels. Contrasted with the decoding FIR-FIR engineering, the structured decoding channel design utilizing Comb-half band FIR-FIR adds to an equipment sparing and decreases the force scattering.
Fault Diagnosis And Troubleshooting On 2.1kW Grid-Connected Photovoltaic Power System In UiTM Pulau Pinang
Authors: Fadzil Muhammad Faris Fahmi Mohd , Samat Ahmad Asri Abd , Idzwan Tajudin A , Omar S , Daud Kamarulazhar
Published: February 2021

Grid-connected photovoltaic power systems always have a connection to a utility grid via a suitable inverter because a PV array only produces a DC power. This paper presents fault diagnosis and troubleshooting on 2.1 kW grid-connected photovoltaic power system in UiTM Pulau Pinang as a case study network. Grid-connected PV systems has a solar panels that produced a power needed in the day time, however the electricity supplied ongoing by distribution network operator during day night or whenever the solar panels produced low electricity because changes of weather (cloudy or rainy day). The case study network was selected because of a fault frequently occur and make the system unstable. The functionality of the case study network has been tested and troubleshooting has been carried out to identify the cause of the problems. Troubleshooting process had been done on the DC and AC side of the system by creating a troubleshooting table. The DC side of the system free from a fault, as proved by all the equipment in a good condition and PV array able to produce desired output voltage. The fault was occurred in the AC side of the system. The inverter has failed to produce desired output.
RETRACTED: Design of high sensitive glucose concentration sensor of photonic crystal cavity
Authors: Hocini A , Mouetsi S , Hocini A , Saadoune B
Published: February 2021

Photonic sensors, in light of proposed structures comprised of rhombus–molded gaps matched with two waveguides, have been developed as another enthusiasm for specialists in science and technology. In this paper, it has been demonstrated that by utilizing the rhombus–formed openings examination, they got outcomes which are brilliant inside the depression locale. Consequently, the quality factor (Q) and the affectability (S) can be essentially improved for the proposed structure. This investigation are performed by reproduction utilizing limited contrast time area (FDTD). Different affectability are acquired as 494.15 nm/RIU and 445.75 nm/RIU and 482.84 nm/RIU and 483.63 nm/RIU and quality factor as high as 5739.5 and 1.17×104, 8.7×104 and 3489.9 have been accomplished, deducing in a location breaking points of 5.52×10−5, 2.84×10−5, 3.67×10−6 and 9.14×10−4. This blend angle gives the proposed structure an extra exhibition as a component to play out a name free biosensing for the biomedical visualization.
Diagnosing different types of skin carcinoma based on their optical properties: A Monte-Carlo implementation
Authors: Hamdy Omnia , Abdelhalim Ibrahim
Published: February 2021

Skin cancer is a very common and serious type of cancers worldwide. Among many kinds of non-melanoma skin cancers, Basel Cell and Squamous Cell Carcinoma are highly treatable in case of early detection. Various Diagnosing techniques are employed to detect skin cancer, such as dermoscopy, OCT, biopsy and physical examination according to the medical case. However, the non-invasive optical methods are gaining validity due to their competitive advantages including safety and functionality. In addition, they are painless and high sensitive to the examined tissue metabolic changes. The propagation of light in any biological tissue is controlled be its optical absorption and scattering properties that highly depend on the wavelength of the utilized light. Monte-Carlo simulation is a forward numerical method used to describe light propagation in biological tissues depending on their optical parameters. In this work, Monte-Carlo simulation method was implemented to characterize the light propagation in normal dermis, Infiltrative Basal Cell Carcinoma, Nodular Basal Cell Carcinoma, and Squamous Cell Carcinomas in order to differentiate healthy from cancerous tissues. The obtained results provided information about the amount of light reflectance, transmittance, absorbed fraction and fluence rate distribution in the examined tissues showing different values at each condition over a wide range of wavelengths, which provide a simple, safe and functional tool for diagnosing these categories of skin carcinoma.
Recent advances and challenges in management of urea wastewater: A mini review
Authors: Zaher A , Shehata Nabila
Published: February 2021

Treating the wastewater with high level of urea and ammonia-nitrogen is one of the problems faced by different plants in the world. The basic methods of urea removal of wastewater streams are electrochemical oxidation, biological treatment, adsorption and hydrolysis using thermal treatment or enzymes and decomposition with the aid of catalyst, strong oxidant. This work reviewed recent of different nanosized and nanostructured particles in different techniques for urea removal from wastewater and the challenges for treatments to draw the attention of researchers and scientists toward novel research ideas in this area.
Single and combined impact of silica fumes with Functionalized multi-walled carbon Nanotubes and nano silica on performance of cement mortars composites
Authors: El-Kattan Ibrahim M. , Khedr M H , Farghali A A , Elsaeidy M , Soliman F N
Published: February 2021

This present work aims to study the impact of single and combined effects of silica fumes (SF) with nano silica (NS) and functionalized multi walled carbon Nanotubes (MWCNTs) on physicomechanical and dynamic properties of cement mortars (CMs). The Portland cement (PC) was partially substituted with different ratios of SF, MWCNTs and NS which, firstly was individually substituted but Secondly, were added together. PC was individually substituted with 2, 4, 6, 8, 10 wt. % of SF then combined with 0.2, 0.4, 0.6, 0.8 and 1.0 wt. % of MWCNTs and 2, 4, 6, 8, 10 wt. % of NS which mixing together. The physicomechanical and dynamic properties such as compressive strength, bending strength, water consistency; both initial and final setting times were measured. The phases of hydration products of some selected samples were additionally investigated by using XRD analyses, the morphology of hardened samples was studied by SEM techniques and TEM showed the particle size of nanoparticles. The results illustrated that, the compressive strength of cement mortars (CM) which containing SF increasing by 27% at 28 days and 11 % for bending strength at early ages comparing to control sample. In combination with functionalized MWCNTS, the compressive and bending strengths increased by 36 and 17 % in case of CMs that containing 0.4 Wt.,% functionalized MWCNTs and 8 Wt.,% SF. additionally, the combination of SF with NS showed increment in compressive strength by 28 % at 8 Wt.,% SF and 8 Wt.,% NS, respectively. SEM-photos showed that CMs containing 0.4 Wt., % functionalized MWCNTs and 8 Wt., % SF had more compacting microstructure than control sample due to bridging effect of MWCNTs and pozzolanic effect of SF.
New design and technological solutions for creating a composite materials recycling tool and methods of their ultra-jet diagnostics
Authors: Li X , Galinovsky A L , Abashin M I , Kravchenko I N
Published: February 2021

The article presents the results of two interrelated studies. The first one is related to assessing the possibility of using a water-polymer ultra-jet as a diagnostic tool for cutting devices that are used for plastic recycling. The second one is related to the development of a new tool design. As a result of the research, it is shown that both the method of water-polymer diagnostics and the proposed design of the knife have prospects to practical application. Rapid wear of the tools for recycling polymer materials is the primary problem that is advisable to eliminate in first order because the idle equipment leads to financial losses. Therefore it is necessary to develop tools with high values of wear resistance and which at the same time have a low cost. A model of a prefabricated tool for recycling composites is proposed, which potentially has high performance properties. The main feature of new tool is its geometric configuration that allows to increase the tool resource and significantly saves the material for its manufacturing. The increase of resource occurs due to the following: if the cutting plate of the tool is worn, it can be removed off the tool, flip it 180 degrees and reinstall. Economy of the material is also due to a decrease in size of the plate, which is fixed to the tool body with countersunk screws head. The research results are confirmed by comparative analysis of various diagnostic methods and strength analysis of the tool.
Radio-shielding metamaterials transparent in the visible spectrum: approaches to creation
Authors: Osipkov A , Makeev M , Garsiya E , Filyaev A , Sinyagaeva K , Kirillov D , Ryzhenko D , Yurkov G
Published: February 2021

The approaches to creation of the materials providing simultaneously high indicators of transparency in the visible spectrum and shielding in a wide radio frequency band are considered in this paper. The analysis and comparison of the main designs of such materials, as well as approaches to their creation, including multilayer and conductive mesh structures, is carried out. The results of our own theoretical studies of the disordered mesh structure are presented, which allow one to obtain a light transmission coefficient from 90 to 98 % in combination with an electromagnetic interference shielding efficiency from 50 to 65 dB. The best results practically achieved to date (shielding efficiency equal 45 dB in the range from 10 kHz to 20 GHz with a light transparency of more than 80 %) were obtained on mesh structures by photolithography, which is a significant limiting factor of this approach. The created multilayer structures show, in general, lower characteristics. However, the technology for their production is better scaled, and the optimization of the thicknesses and chemical composition of multilayer structures can significantly increase them. In this regard, technological aspects may come to the fore when taking into account the possibility of subsequent scaling of the technology and economic indicators when choosing an approach for the implementation of the materials with the required characteristics.
Development of a new diagnostic method for materials abrasion resistance
Authors: Barzov A A , Galinovskiy A L , Vyshegorodtseva A S
Published: February 2021

The article deals with the development of a new diagnostic method for materials abrasion resistance. It lists the advantages of the proposed ultra water-jet abrasive diagnostics method and the disadvantages of existing ones. The implementation diagram of the method, the results of the experiments and the samples images with traces of abrasive jet interaction are presented. The phenomenological ideas of the nature of erosion of interacting materials are highlighted.
Lightweight nodal parts for large space truss structures enabled by SLM: modelling, manufacturing, and testing
Authors: Golubev E , Arkhipov M , Galinovsky A , Klem A
Published: February 2021

Selective laser melting (SLM), as a method of metal additive manufacturing, has developed rapidly over the last years to become a breakthrough technology capable of upending the way that products from aerospace and other various industrial sectors are not only fabricated but also designed. The purpose of this paper is to investigate the potential benefits and drawbacks of SLM implementation in the frame of design and development of components for large space lightweight structures. The three types of the most common structural engineering solutions are compared, based on the different manufacturing techniques and materials. The paper describes the results of the measurement of the shape of fittings after fabrication and cryogenic temperature-cycle tests. An extra option for the weight reduction of structures is given via the implementation of the topology optimization method. Three challenges have been identified, including quality of surfaces, deviation of geometry, residual internal stresses. This work shows the possibility to solve this topical issue by using a waterjet inspection technique and represents one of the first attempts for its implementation to perform a fast evaluation of mechanical properties of structural materials manufactured using SLM.
Polymer composite materials based on ultra-high molecular weight polyethylene
Authors: Okhlopkova A A , Danilova S N , Dyakonov A A , Vasilev A P , Ivanov A N , Sleptsova S A
Published: February 2021

Ultra-high molecular weight polyethylene (UHMWPE) has a number of unique properties: low friction coefficient, high strength and toughness, frost resistance, and resistance to aggressive media. This determines the use of UHMWPE as a polymer matrix for the manufacture of high-strength technical products. The use of nanoparticles as polymer fillers, which has emerged over the last two decades, has made it possible to significantly improve the characteristics of nanocomposites while reducing their degree of filling, achieving an improvement in properties that could not be achieved using traditional fillers and modifiers. Due to the high specific surface area, nanofillers have high activity for structuring the polymer matrix. However, this becomes a problem in the development of polymeric materials with nanofillers, due to the processes of agglomeration, as well as the difficulty to distribute them uniformly in the volume of the polymer matrix. We have demonstrated an efficient mixing process for UHMWPE and nanofillers, consisting of mechanical activation in a planetary mill and the technology of liquid-phase compounding under the continuous action of ultrasonic vibrations. Despite the large number of studies aimed at enhancing the interfacial interaction between UHMWPE and inorganic fillers, the problem of the weak interaction between the polymer matrix and the inorganic filler remains unsolved. Thus, the research work is aimed at obtaining new composite materials based on UHMWPE strengthened with organically modified montmorillonite and compounds containing 2-mercaptobenzothiazole, ZnO and sulfur.
Aerodynamic space tether system as a system with distributed parameters
Authors: Elenev D V , Zabolotnov Yu M , McMillan A J
Published: February 2021

The motion of the aerodynamic tether system includes two stages - the deployment and the motion of the deployed system. The initial condition for the deployment model is that of a spacecraft with a rigidly connected second body in a circular orbit about the planet. The deployment process is based on the aerodynamic forces acting on bodies. After the separation of the rigid connection, further motions of the bodies are then controlled by the tether release mechanism which unreels the tether and controls the rate at which the tether is unreeled. The motion of the system is described by the multi-point model, splitting the tether into a number of parts and using the series of separations of material points from the spacecraft, thus forming a mathematical model of the system with distributed parameters. The aerodynamic forces acting on the tether are taken into consideration. This model makes it possible to calculate numerically elastic deformations and curvature of the tether and provides more accurate modelling if compared with the two-point model.
Modelling the work of the transport complex
Authors: Kuzmin V S , Elenev D V
Published: February 2021

The modelling of the transport complex is made using an automated system and an example of the enterprise that uses the dangerous materials. The example of such enterprise is a nuclear power station. The automated system used for modelling is a web-based intranet application that realizes monitoring and control functions. The automated system uses a system of objects included into the model of the enterprise, namely: gates, roads, transportation devices and controllers, airtight zone, describing the reactor building, gateway which allows to move cargo into and out from the building, non-airtight zone, which describes the outside area, and the zone of loading and unloading the cargo. The system receives input signals of discrete or analogue origin. Basing on the results of data collection, the algorithms of forecasting the crucial changes in states of main elements of the transport complex were developed. The automated system models the workflow of elements and the whole transport complex.
Opportunities and prejudices in synthetic experiments
Authors: McMillan A J
Published: February 2021

Synthetic experiments, meaning experiments performed using models of reality, are used in a variety of contexts. In recent years, advances in computing capability have led to the development of modelling capability that replicates reality to such an extent that in some circumstances it is difficult to distinguish the model from reality. From a science or engineering perspective, computational analysis models are used to replicate or predict phenomena such as fluid flow or stress in a machine component, but the capability has also crossed over into the arts enabling the computer generated imagery (CGI) used in films, and the augmented reality (AR) of video games. This paper reviews the application of synthetic experiments to replace physical experiments and discusses some of the advantages and pitfalls of such an approach in the context of education. The trend for democratizing analysis is considered, and the dangers of misinterpreting results are discussed. A discussion of the issue of model over–simplification is given, and finally the use of synthetic experiments as part of a systematic scientific investigation is also considered.
Numerical analysis of an electrostatically formed membrane mirror
Authors: Volchek O S
Published: February 2021

The paper presents a numerical algorithm developed to determine the deformed shape of a membrane mirror controlled by electrostatic forces. Deformable mirrors are key components that are used in combination with wavefront sensors and real-time control systems in adaptive optics. The electrostatic membrane mirror concept implies using a thin conductive reflective membrane stretched over a solid flat frame and deformed electrostatically by applying control voltages to electrostatic actuators positioned behind the membrane. The proposed algorithm implies solving a coupled structural-electrostatic problem by using finite element and boundary element methods. Small deflections of a membrane are described by Poisson’s equation. The electric charge distribution over the membrane surface having a prescribed potential is governed by a Fredholm integral equation of the first kind. The coupled problem is solved iteratively, and a criterion for terminating iterations when searching for a steady-state solution is presented. The distinctive feature of this approach is that it allows us to take into account electrical edge effects typical for conducting thin-walled structures of very small thickness. Illustrative examples are provided to show the applicability and validity of the proposed method as well as its advantage over some existing techniques.
The study of the applicability of polymer composite materials for the manufacture of the impeller of a centrifugal compressor
Authors: Martynyuk L A , Afanasiev D V , Bykov L V , Ezhov A D , Mezintsev M A
Published: February 2021

The use of composite materials in modern designs is one of the promising areas. Despite a number of advantages, the use of composite materials imposes a number of restrictions on their use. One of them is a binder’s degradation temperature. The revision of the existing methodology for determining the thermal state of the compressor wheel through the use of modern calculation tools and their experimental justification will allow further reliable thermal calculation taking into account the anisotropy of material properties. For carrying out computational research and testing manufacturing technology, a three-dimensional model of the impeller of a centrifugal compressor and the motor shaft was developed.
Investigation and correlation of radioactive hazards with magnetic parameters and heavy metals of dwelling sand from two major rivers in south India – A comparative study
Authors: Murugesan S , Ravichandran S
Published: February 2021

Cauvery and Palar, two major rivers in Tamilnadu, India, have importance for irrigation, drinking, electricity and river sand is used as a major material of building construction in India. The natural radionuclides such as uranium, thorium and potassium (238U, 232Th, 40K) isotopes are investigated through gamma ray spectrometer with NaI(Tl) detector. The average values of radionuclides and in-situ dose are measured. Related parameters like absorbed dose (ADin & ADout), Annual Effective Doe Equivalent (Ein & Eout), and also hazard indices to assess radiation exposure to human such as average radium equivalent (Raeq), external (Hex)and internal (Hin) hazard indices, Radioactive heat production (RHP), internal and external Excess Lifetime Cancer Risk (ELCRin and ELCRout), Alpha (Iα), Gamma Index (Ig) and Annual Gonadal dose (AGDE) are computed and correlated. This study exhibits that almost all the radioactive parameters are in control by comparing to the world average. Nevertheless, the Cauvery River except site no.20 does not produce a radiological hazard. But, the palar river does slightly produce a radiological risk especially site no.6 shows three times of the world average.
Impact of SRFE process on electrical properties of P-N photodetector
Authors: Sangwaranatee N , Srithanachai I , Niemcharoen S
Published: February 2021

Semiconductor properties change from soft radiation flash exposure process (SRFE) will present in this paper. Semiconductor device use with radiation application and always degrade because impact from radiation will damage on device structure. Currently, the defects from radiation cannot explain all of impact to electrical properties because has wind range in several application. However, this paper will present influent from Roentgen radiation on P-N photodetector device by expose for few second and low energy. The radiation will expose on device for many time to reach target time and will control distance between radiations machine and devices. Forward current of device after SRFE process has changed in positive way by build in potential (Vbi) decrease around 0.2V and forward current increase around 4 orders.
Synthesis and characterisation of copper oxide thin films by double dip method
Authors: Salam Shifa , Jose Ben , Raphael Rakhy , Anila E I
Published: February 2021

Cupric Oxide thin films were prepared and deposited on glass plate by double-dip method. The study was conducted on samples annealed at different temperatures. The deposited films showed poly crystalline nature with a preferred orientation of monoclinic structure along (111) plane. The thicknesses, as well as the refractive indices of all the films, were determined by using Near Normal Spectroscopic Reflectometry. Optical studies revealed a decrease in band gap with annealing temperature. The V-I graphs were found to be linear for a short-range when measured by two probe method. The thin films showed a resistivity of the order of kΩ-cm. An increase in electrical conductivity with temperature reveals the semiconducting nature of the thin films.
Effect of reflector materials to the neutron flux and k effective in the accelerator driven subcritical reactor
Authors: Tien Tran Minh , Phung Nguyen Hong Thien , Hien Bui Thi Thanh
Published: February 2021

The paper presents the results of the calculation of neutron flux distribution and k effective factor in the ADSR with different reflector materials. Materials include graphite, Be, Y2O3, ZrO2. For each type of materials, the neutron flux distribution according to the height of the reactor, the radius, the neutron energy emitted, and k effective has been calculated. The results show that the maximum neutron flux and k effective factor is berium material as combined with Th-233U mixed fuel.