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Effect of the Density of Molten Metal on the Raining Phenomenon in Horizontal Centrifugal Casting

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Open Journal of Applied Sciences 2024年第7期14卷 1918-1926页

作者： miguel A. Barron Joan Reyes Departamento de Materiales Universidad Autonoma Metropolitana Azcapotzalco Ciudad de Mexico Mexico

In this work the influence of the density of the molten metal on the emergence of the raining phenomenon in the horizontal centrifugal casting process is numerically studied. Transient 2D numerical simulations were carried out using Computational Fluid Dynamics software. Three molten metals with different density, namely aluminum, iron and lead, and three angular frequencies, namely 50, 66 and 77 rad/s were considered. It is found that the density of the molten metal significantly affects the emergence, transient or permanent, of the rain phenomenon. However, the magnitude and duration of the rain phenomenon depend on the angular frequency of the rotating mold. Likewise, since gravitational forces affect the metal according to its density, the value of the critical rotation speed of the mold is also affected.

关键词： Angular Frequency Centrifugal Force Computational Fluid Dynamics Critical Rotation Speed G Factor Horizontal Centrifugal Casting Molten Metal Density

Oxygen tension modulates cell function in an in vitro three-dimensional glioblastoma tumor model

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Bio-Design and Manufacturing 2024年第3期7卷 307-319页

作者： Sen Wang Siqi Yao Na Pei Luge Bai Zhiyan Hao Dichen Li Jiankang He J.miguel Oliveira Xiaoyan Xue Ling Wang Xinggang Mao State Key Laboratory for Manufacturing System Engineering Xi’an Jiaotong UniversityXi’an 710054China School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710054China NMPA Key Laboratory for Research and Evaluation of Additive Manufacturing Medical Devices Xi’an Jiaotong UniversityXi’an 710054China 3B’s Research Group I3Bs–Research Institute on BiomaterialsBiodegradables and BiomimeticsUniversity of MinhoHeadquarters of the European Institute of Excellence on Tissue Engineering and Regenerative MedicineAveParkZona Industrial da Gandra4805-017 BarcoGuimarãesPortugal ICVS/3B’s-PT Government Associate Laboratory 4806-909 Braga/Guimar˜aesPortugal Department of Pharmacology School of PharmacyFourth Military Medical UniversityXi’an 710032China Department of Neurosurgery Xijing HospitalFourth Military Medical UniversityXi’an 710032China

Hypoxia is a typical feature of the tumor microenvironment,one of the most critical factors affecting cell behavior and tumor ***,the lack of tumor models able to precisely emulate natural brain tumor tissue has impeded the study of the effects of hypoxia on the progression and growth of tumor *** study reports a three-dimensional(3D)brain tumor model obtained by encapsulating U87MG(U87)cells in a hydrogel containing type I *** also documents the effect of various oxygen concentrations(1%,7%,and 21%)in the culture environment on U87 cell morphology,proliferation,viability,cell cycle,apoptosis rate,and ***,it compares two-dimensional(2D)and 3D *** comparison purposes,cells cultured in flat culture dishes were used as the control(2D model).Cells cultured in the 3D model proliferated more slowly but had a higher apoptosis rate and proportion of cells in the resting phase(G0 phase)/gap I phase(G1 phase)than those cultured in the 2D ***,the two models yielded significantly different cell ***,hypoxia(e.g.,1%O2)affected cell morphology,slowed cell growth,reduced cell viability,and increased the apoptosis rate in the 3D *** results indicate that the constructed 3D model is effective for investigating the effects of biological and chemical factors on cell morphology and function,and can be more representative of the tumor microenvironment than 2D culture *** developed 3D glioblastoma tumor model is equally applicable to other studies in pharmacology and pathology.

关键词： Hypoxia Glioma Three-dimensional glioma model In vitro

A prototype for on-site generation of chlorinated disinfectant for use in rural aqueducts

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Water Science and Engineering 2024年第1期17卷 33-40页

作者： Diana Marcela Cuesta Parra Felipe Correa Mahecha Andrés Felipe Rubio Pinzon Davidcamilo Ramirez Bustos Leonel Alveyro Teran Llorente miguel Fernando Jimenez Jimenez Chemical and Environmental Engineering Department Fundacion Universidad de AmericaBogota 117111Colombia Chemical Engineering Department Fundacion Universidad de AmericaBogota 117111Colombia Mecanical Engineering Department Fundacion Universidad de AmericaBogota 117111Colombia

Sodium hypochlorite has significant potential as a sanitation solution in hard-to-reach *** studies have investigated the optimal electrolysis parameters for its production with volumes greater than 1o *** study evaluated sodium hypochlorite production through electrolysis in a 22-L prototype and identified the optimal operating *** were performed using graphite electrodes with areas of 68.4 cm^(2) at the laboratory scale and 1865.0 cm^(2) at the prototype scale.A design for experiments with different operating times,chloride concentrations,and electric current intensities was *** optimal operating time,sodium chloride concentration,and current intensity at the laboratory scale were 120 min,150 g of chloride per liter,and 3 A,respectively,leading to the production of 5.02 g/L of the disinfectant with an energy efficiency of 12.21 mg of Cl_(2) per *** the prototype scale,the maximum sodium hypochlorite concentration of 3.99 g of chloride per liter was achieved with an operating time of 120 min,a sodium chloride concentration of 100 g of chloride per liter,and a current intensity of 70 A,reaching an energy efficiency of 42.56 mg of Cl_(2) per *** addition,this study evaluated the influences of the chloride concentration,current intensity,and operating time on the production of sodium hypochlorite at the two scales,and formulated the equations showing the trends of sodium hypochlorite production and energy efficiency in the electrochemical *** 22-L prototype model for production of this oxidizing substance is promising for disinfection of large volumes of water in areas that are difficult to access.

关键词： Disinfection Electrolysis Energy efficiency Optimization Sodium hypochlorite

一种优化开关磁阻电机换相区控制策略的高效率转矩分配函数

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电工技术学报 2024年第6期39卷 1671-1683页

作者：杨帆陈昊李晓东 miguel Pablo Aguirre Muhammad Asghar Saqib 中国矿业大学电气工程学院徐州221116 新能源电动车技术与装备中东欧国家国际联合研究中心徐州221008 江苏省高校新能源发电与电动车国际合作联合实验室徐州221008 徐州市新能源电动车技术与装备重点实验室徐州221008 澳门科技大学创新工程学院中国澳门999078 布宜诺斯艾利斯工学院电子工程系布宜诺斯艾利斯B1636 巴基斯坦工程技术大学电气工程系讷瓦布沙阿44000

转矩分配函数被广泛应用于抑制开关磁阻电机的转矩脉动。然而,输入相转矩跟踪不足或者输出相产生较大的负转矩这两种情况通常会导致电机的转矩脉动难以得到有效抑制,并降低电机的运行效率。因此,为了能够有效降低电机的转矩脉动并提高... 详细信息

转矩分配函数被广泛应用于抑制开关磁阻电机的转矩脉动。然而,输入相转矩跟踪不足或者输出相产生较大的负转矩这两种情况通常会导致电机的转矩脉动难以得到有效抑制,并降低电机的运行效率。因此,为了能够有效降低电机的转矩脉动并提高电机的效率,提出了一种新型的转矩分配函数控制策略。在提出的转矩分配函数控制策略中,电机的换相区域分为两个区域。在前一区域中,通过降低输入相转矩分配的比例,可以实现输入相实际转矩快速跟踪参考转矩,电机的转矩脉动有效降低。同时由于在输入相电感变化率较低时减少输入相分配的转矩,从而输入相的峰值电流随之降低,电机的转矩电流比提高。在后一区域中,将输出相的电流在转子对齐位置附近处减小到0,以避免产生较大的负转矩。因此,在所提出的方案下,电机的转矩脉动得到有效抑制,电机的效率也得到了提高。为了验证该方法的有效性,在一台12/8三相开关磁阻电机上进行了仿真和实验。结果表明,所提出的转矩分配函数控制策略能有效降低开关磁阻电机转矩脉动,也能有效地提高开关磁阻电机的运行效率。

关键词：开关磁阻电机转矩分配函数负转矩转矩电流比效率

Application of the Electrical Resistivity Method in Precision Agriculture of Coffee Cultivation, in the Kabiri Area, Ícolo e Bengo Township, Luanda, Angola

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International Journal of Geosciences 2024年第9期15卷 720-736页

作者： Gerson Itembo Artur miguel Nelson Mateta Idvano Costa miguel Clemente Júlio Kuende Department of Geosciences Instituto Superior Politcnico de Tecnologias e Cincias (ISPTEC) Luanda Angola

The electrical resistivity method is a geophysical tool used to characterize the subsoil and can provide an important information for precision agriculture. The lack of knowledge about agronomic properties of the soil tends to affect the agricultural coffee production system. Therefore, research related to geoelectrical properties of soil such as resistivity for characterization the region of the study for coffee cultivation purposes can improve and optimize the production. This resistivity method allows to investigate the subsurface through different techniques: 1D vertical electrical sounding and electrical imaging. The acquisition of data using these techniques permitted the creation of 2D resistivity cross section from the study area. The geoelectrical data was acquired by using a resistivity meter equipment and was processed in different softwares. The results of the geoelectrical characterization from 1D resistivity model and 2D resistivity electrical sections show that in the study area of Kabiri, there are 8 varieties of geoelectrical layers with different resistivity or conductivity. Near survey in the study area, the lowest resistivity is around 0.322 Ω·m, while the highest is about 92.1 Ω·m. These values illustrated where is possible to plant coffee for suggestion of specific fertilization plan for some area to improve the cultivation.

关键词： Electrical-Resistivity Method Precision Agriculture Coffee

Lifestyles of Older Adults in Castilla-La Mancha(Spain):Influence of Sex,Age,and Habitat

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Fudan Journal of the Humanities and Social Sciences 2024年第2期17卷 313-335页

作者： Esther Portal Martínez Juan Lirio castro David Alonso González JoséLuis Gómez Ramos University of Castilla-La Mancha Talavera de la ReinaSpain Complutense University MadridSpain

This paper presents the quantitative research results of a comprehensive study titled“Current Profle of Older Adults in Castilla-La Mancha(Spain).”The study aims to understand and describe the characteristics of individuals aged 65 and above within this autonomous region,with a focus on the variables of sex,age,and habitat.A cross-sectional approach was employed,utilizing quantitative methods to collect *** gather information,a customized questionnaire was developed to address the study objectives,covering various aspects such as sociodemographic factors,living conditions,leisure activities,social participation,and cultural *** survey was conducted via telephone,ensuring representation by employing gender quotas,age-group stratifcation,and considerations for habitat size.A representative sample of 1,065 participants was included in the *** fndings reveal a degree of homogeneity in the lifestyles of older adults,with discernible variations infuenced by factors such as sex,habitat,and *** results shed light on the diverse habits and experiences of older adults,emphasizing the signifcance of habitat conditions,social participation,and the aging process.

关键词： Lifestyle habits Older adults Habitat conditions Social participation Aging experience

Comparison of Methods for Nitrate Interpolation in Wells in Aguascalientes, Mexico

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Journal of Geoscience and Environment Protection 2024年第8期12卷 180-196页

作者： miguel Ángel González-Núñez Faculty of Engineering Autonomous University of Chihuahua (UACH) Chihuahua Mexico

The accuracy of interpolation models applied to groundwater depends, among other factors, on the interpolation method chosen. Therefore, it is necessary to compare different approaches. For this, different methods of interpolation of nitrate concentrations were contrasted in sixty-seven wells in an aquifer in Aguascalientes, Mexico. Four general interpolation methods were used in ArcGIS 10.5 to make the maps: IDW, Kriging, Natural Neighbor and Spline. In the modeling, only method type was varied. The input parameters (location, temporality, and nitrate concentration) were the same in the four interpolations;despite this, different maximum and minimum values were obtained for each interpolation method: for IDW, 0.2 to 22.0 mg/l, for Kriging, 3.5 to 16.5 mg/l, for Natural Neighbor, 0.3 to 21.7 mg/l and for Spline −30.8 to 37.2 mg/l. Finally, an assessment of the maps obtained was conducted by comparing them with the Official Mexican Standard (OMS), where 24 of the 67 wells were found outside the 10 mg/l that the OMS establishes as maximum permissible limit for human consumption. Taking as a starting point the measured values of nitrates (0.25 to 22.12 mg/l), as well as the spatial distribution of the interpolated values, it was determined that the Krigging method best fitted the data measured in the wells within the studied aquifer.

关键词： Interpolation Nitrates Hydrogeology GIS Mexico

A Novel Approach to Breast Tumor Detection: Enhanced Speckle Reduction and Hybrid Classification in Ultrasound Imaging

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Computers, Materials & Continua 2024年第5期79卷 1875-1901页

作者： K.Umapathi S.Shobana Anand Nayyar Judith Justin R.Vanithamani miguel Villagómez Galindo Mushtaq Ahmad Ansari Hitesh Panchal Department of Biomedical Engineering KIT-Kalaignarkarunanidhi Institute of TechnologyCoimbatore641402India Graduate School Faculty of Information TechnologyDuy Tan UniversityDa Nang550000Viet Nam Department of Biomedical and Instrumentation Engineering Avinashilingam Institute for Home Science and Higher Education forWomenCoimbatore641043India UniversidadMichoacana de SanNicolás de HidalgoAvenida Francisco J.Múgica S/N Ciudad Universitaria MoreliaCP58030Mexico Department of Pharmacology and Toxicology College of PharmacyKing Saud UniversityRiyadh11451Saudi Arabia Department of Mechanical Engineering Gujarat Technological UniveristyNigam NagarChandkhedaAhmedabadGujarat382424India

Breast cancer detection heavily relies on medical imaging, particularly ultrasound, for early diagnosis and effectivetreatment. This research addresses the challenges associated with computer-aided diagnosis (CAD) of breastcancer fromultrasound images. The primary challenge is accurately distinguishing between malignant and benigntumors, complicated by factors such as speckle noise, variable image quality, and the need for precise segmentationand classification. The main objective of the research paper is to develop an advanced methodology for breastultrasound image classification, focusing on speckle noise reduction, precise segmentation, feature extraction, andmachine learning-based classification. A unique approach is introduced that combines Enhanced Speckle ReducedAnisotropic Diffusion (SRAD) filters for speckle noise reduction, U-NET-based segmentation, Genetic Algorithm(GA)-based feature selection, and Random Forest and Bagging Tree classifiers, resulting in a novel and efficientmodel. To test and validate the hybrid model, rigorous experimentations were performed and results state thatthe proposed hybrid model achieved accuracy rate of 99.9%, outperforming other existing techniques, and alsosignificantly reducing computational time. This enhanced accuracy, along with improved sensitivity and specificity,makes the proposed hybrid model a valuable addition to CAD systems in breast cancer diagnosis, ultimatelyenhancing diagnostic accuracy in clinical applications.

关键词： Ultrasound images breast cancer tumor classification segmentation deep learning lesion detection

Constructing Hopf Insulator from Geometric Perspective of Hopf Invariant

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Chinese Physics Letters 2024年第3期41卷 121-126页

作者：常治文郝维昌 miguel Bustamante 刘鑫 Institute of Theoretical Physics School of Physics and Optoelectronic EngineeringBeijing University of TechnologyBeijing 100124China School of Physics Beihang UniversityBeijing 100191China Complex and Adaptive Systems Laboratory School of Mathematics and StatisticsUniversity College DublinBelfield4DublinIreland

We propose a method to construct Hopf insulators based on the study of topological defects from the geometric perspective of Hopf invariant ***,we prove two types of topological defects naturally inhering in the inner... 详细信息

关键词： Hopf topological invariant