bluuebunny/crossref_metadata_2025_split huggingface dataset:
Finite Frequency Robust Vibration Control of Flexible-Rigid Coupled Spacecraft
Authors: Xu Shidong 
Published: February 2021

Abstract
This paper is concerned with robust vibration control of flexible-rigid coupling spacecraft with finite frequency constraint. Considering that the major vibration energy of flexible structure is induced by the vibration modes located in a specific frequency range, the dynamics of the considered spacecraft are derived as a system with given vibration modes. A novel robust finite frequency controller is proposed by using output feedback method, which focuses on suppressing the vibration modes in given frequency region. Compared with the classic entire frequency controller, the newly proposed controller can achieve better vibration attenuation performance. Finally, illustrative simulation results are provided to demonstrate the effectiveness and superiority of our proposed control method.
Data Modeling and Workflow Analysis of Cyber-Manufacturing Systems
Authors: Song Zhengyi , Moon Young 
Published: February 2021

Abstract
Cyber-Manufacturing System (CMS) is a vision for the factory of the future, where physical manufacturing resources and processes are integrated with computational workflows to provide on-demand, adaptive, and scalable manufacturing services. In CMS, functional manufacturing components in a factory floor are digitized and encapsulated in production services; and are accessible by users throughout the network. CMS utilizes data-centric technologies to program manufacturing activities in factory floors. Leveraging advanced technologies, CMS can provide robust solutions to achieve better manufacturing agility, flexibility, scalability, and sustainability than from traditional factories.
While data is the main driver of the manufacturing activities in CMS, the lack of (i) a generic data model of explicit representation of the entities and stakeholders in CMS and (ii) workflow definition and analysis for service-orientated functionalities and manufacturing intelligence of CMS is still hindering the implementation of a fully executable CMS. To address such problems, this paper (i) formalizes a data modeling of CMS using Entity-Relationship (E-R) diagram, (ii) presents the definition and analysis of workflows along with data pipelines and Extract/Transform/Load (ETL) processes that automate the entire lifecycle activities in CMS and (iii) deploys the proposed data model and workflows in a Web-based application, and (iv) tests the functionality of this application with an industrial case and eventually validates the proposed data model and workflows.
Flow Induced by a Two Stage Electrohydrodynamic Gas Pump in a Square Channel
Authors: Mazumder A. K. M. Monayem H. , Trombley Grace S. , Cusinio Brendon G. 
Published: February 2021

Abstract
In this study, fluid flow induced by a two stage electrohydrodynamic (EHD) gas pump in a square channel has been evaluated by experimental measurement and numerical simulations. This study is implemented for a two stage EHD gas pump with three emitting electrode configurations: 8, 24, and 56 respectively to seek the relation between the number of stages and emitting electrodes. The EHD pump is evaluated for a wide range of operating voltages starting from 20 kV up to 28 kV for further improvement in its performance over a single stage. To achieve the maximum enhancement, the emitting electrodes of the EHD gas pump are flush mounted on the channel walls so that the corona wind produced directly disturbs the boundary layer thickness and improves the heat transfer. This is leading to a higher velocity near the channel walls and resulting in an inverted parabolic velocity profile at the center of the channel, which is opposite to the fully developed velocity profile of a forced flow. Velocities are measured at three cross-sections along the tube length and then integrated to obtain the volume flow rate. The results show that EHD technique has a great potential for many engineering applications.
A Study of the Effect of Extended Hounsfield Unit Range and Voxel Size on Defect Detection in Friction Stir Welds
Authors: Baydoun Ahmad M. R. , Hamade Ramsey F. 
Published: February 2021

Abstract
Friction stir welding (FSW) is a novel welding method that is garnering attention, in part, due to its ability to join dissimilar materials. One of the challenges in producing dissimilar friction welded joints is ensuring the welds are defect-free. Nondestructive testing (NDT) methods such as ultrasonic waves, gamma rays, X-rays, and X-ray CT, are gaining popularity as a method to detect internal defects in FSW joints.
In this study, dissimilar AA1050-AA6061-T6 FSW lap welds are Manufactured and then examined using an NDT X-ray CT technique. The effects of two critical X-ray CT scanning parameters (voxel size and Hounsfield unit (HU)) on the detection of internal defects are investigated. The samples are scanned via X-ray CT at two different voxel sizes (2.457 E−02 and 1.420 E−03 mm3) and two HU ranges (12-bit and 16-bit depth). The generated Digital Imaging and Communications in Medicine (DICOM) images are segmented based on a proper HU threshold found via the Otsu thresholding method. The findings show that Small voxel size (higher resolution) improves the ability of detecting internal defects and improves the effectiveness of the thresholding process. Higher HU range results in a wider separation between detected material peaks, thus enhancing the effectiveness of the thresholding process as well.
Student Experiential Learning Through Design and Development of a Subsurface Melting Head for NASA RASCAL-Special Edition Competition
Authors: Xu Jiajun , Haghani Sasan , D'Orazio Giancarlo , Velazquez Carlos 
Published: February 2021

Abstract
In order for students to enhance their understanding of engineering concepts, hands-on experience proves to be essential. Incorporating the design component in undergraduate engineering education has been an immediate and pressing concern for educators, professional societies, industrial employers and agencies concerned with national productivity and competitiveness. It is crucial to enhance undergraduate design and research experiences to meet both societal needs and the growing job-market demands. The University of the District of Columbia (UDC), the District of Columbia’s only public institution of higher education, and a historically black college and university (HBCU), had recently modernized its undergraduate curricula in engineering to meet that need. This paper presents a case study of recent implementation of student experiential learning approach through undergraduate research experience course (MECH 302). This student group participated in the 2019 US National Aeronautics and Space Administration Revolutionary Aerospace Systems Concepts – Academic Linkages (RASC-AL) Challenge, in which they will develop concepts that may provide full or partial solutions to specific design problems and challenges currently facing human space exploration.
Simulation of Ventilation Flow at Different Conditions Through a Two-Dimensional Room Incorporated With Phase Change Materials
Authors: Reyes-Cubas Angel , Abdo Peter 
Published: February 2021

Abstract
Climate change and global warming have raised many concerns, highlighting the necessity to reduce energy consumption associated with the building sector. HVAC systems account to almost 40% of the building’s energy consumption. Natural ventilation is the process of supplying and removing air through an indoor space by natural means. Windcatchers have been used over centuries for providing natural ventilation using wind power. Moreover, it is an effective passive method to provide healthy and comfortable indoor environment by decreasing moisture content in the air and reducing pollutants concentration significantly.
Materials that change phase at certain temperature are frequently referred to as Phase Change Materials (PCMs). Phase Change Materials, also known as Thermal Energy Storage (TES), are substances with high latent heat storage capacity which absorb or release the heat from or to the surrounding environment. PCMs could be used in passive cooling systems and they are directly related to building energy efficiency.
This study investigates air flow through a windcatcher into a two-dimensional room incorporated with phase change materials (PCMs). The temperature change in the room implementing PCM is analyzed to monitor the PCMs’ performance. To achieve this, Computational Fluid Dynamics (CFD) tool is used to simulate the air flow through a two-dimensional standard room (3 m × 5 m) fitted with a windcatcher at its roof. Ansys Fluent is utilized to simulate and display the contours of temperature, liquid fraction, and velocity of both PCM and air. The energy model as well as the solidification and melting model are employed, and the K-Epsilon turbulence model is implemented. PCM is placed at the right and left walls of the room, as well as at its bottom. The inlet velocity ranges between 1 m/s and 7 m/s, simulating the average wind speeds in Sydney-Australia during summer [1]. Different inlet temperatures are used, specifically at 302 K and 310 K. The effect of the phase change material presence on the air flow pattern is also investigated.
Effect of Heat Flux on Pool Boiling Heat Transfer Enhancement (Numerical Investigation Approach)
Authors: Mogaji T. S. , Sogbesan O. A. , Jen Tien-Chien 
Published: February 2021

Abstract
This study presents numerical investigation results of heat flux effect on pool boiling heat transfer enhancement during nucleate boiling heat transfer of water. The simulation was performed for five different heated surfaces such as: brass, copper, mild steel, stainless steel and aluminum using ANSYS simulation software at 1 atmospheric pressure. The samples were heated in a domain developed for bubble growth during nucleate boiling process under the same operational condition of applied heat flux ranged from 100 to 1000 kW/m2 and their corresponding heat transfer coefficient was obtained numerically. Obtained experimental data of other authors from the open literature result is in close agreement with the simulated data, thus confirming the validity of the CFD simulation method used in this study. It is found that heat transfer coefficient increases with increasing heat flux. The results revealed that in comparison to other materials tested, better heat transfer performance up to 38.5% and 7.11% is observed for aluminum and brass at lower superheated temperature difference conditions of 6.96K and 14.01K respectively. This behavior indicates better bubble development and detachment capability of these heating surface materials and could be used in improving the performance of thermal devices toward producing compact and miniaturized equipment.
Microtexture Dependence of Mechanical and Electrical Properties of Gold Thin Films Used for Micro Bumps of 3D Stacking Structures
Authors: Nakauchi Genta , Akasaki Shota , Miura Hideo 
Published: February 2021

Abstract
The variation of their crystallinity, in other words, the order of atom arrangement of grain boundaries in electroplated gold thin films was investigated by changing their manufacturing conditions. Then, the effect of the crystallinity on both their mechanical and electrical properties was measured by using nano-indentation test and electromigration test. The crystallinity of the gold thin films was varied by changing the under-layer material used for electroplating. Also, the micro texture of gold thin films was evaluated by EBSD (Electron Back-Scatter Diffraction) and XRD (X-Ray Diffraction). It was clarified that the crystallinity of the electroplated gold thin films changed drastically depending on the crystallinity of the under-layer materials and electroplating conditions such as current density and temperature. This variation of the crystallinity should have caused wide variation of mechanical properties of the films. In addition, their mechanical properties such as Young’s modulus and hardness showed wide variation by about 3 times comparing with those of bulk gold. Similarly, the EM resistance of the electroplated gold bumps varied drastically depending on the ratio of porous grain boundaries and their crystallinity. Both the ratio and crystallinity also varied depending on the crystallinity of the under layer and electroplating conditions. The effective lifetime of the gold bumps was successfully predicted by considering both the crystallinity and residual stress of fine gold bumps. The lifetime varied more than 10 times as a strong function of the crystallinity of grain boundaries in the fine bumps. Therefore, it is very important to control the crystallinity of the under-layer for electroplating in order to control the distribution of the mechanical properties and reliability of the electroplated gold thin films.
Design of DFB Laser Drive and Temperature Control Circuit in TDLAS Gas Concentration Detection
Authors: Yang Haoqing , Bu Xiongzhu , Cao Yihan , Song Yang 
Published: February 2021

Abstract
In order to satisfy the requirements of TDLAS gas measurement, the DFB laser drive and temperature control system is designed with taking STM32F103RCT6 as the main control chip, including sine wave and sawtooth signal generation circuit, temperature acquisition circuit and temperature control circuit, etc. The sine wave and the sawtooth wave signal are respectively generated by using the DDS chip and the STM32 on-chip DAC, and the two are superimposed to control the constant current source to drive the laser. At the same time, the internal temperature of the laser is collected and controlled. The DFB laser with a center wavelength of 1653.7 nm is used to verify the CH4. The experiment proves that the system can generate stable laser driving signals and achieve precise temperature control. The temperature control accuracy can reach ±0.013 °C. The design satisfies the requirements of TDLAS gas detection system for laser driving and temperature control.
Programmable Waveguiding of Ultrasonic Waves for Regional Damage Detection Using Elastic Metamaterials
Authors: Song Yihao , Shen Yanfeng 
Published: February 2021

Abstract
This study puts forward a metasurface design which allows the flexible tuning of the elastic wave propagation path, enabling the interrogating wave field guiding into desired monitoring regions for damage detection. As a demonstrative case study, the metasurface plate contains a rectangular array of unit cells sitting in an aluminum plate. Each unit cell is comprised of a shape memory alloy substrate and a lead stub. The controllable bandgap of such a metamaterial system can be achieved due to the stiffness change of nitinol between its martensite phase and austenite phase under a thermal load. First, a Finite Element Model (FEM) of the unit cell is constructed to calculate the band structure of the metasurface plate, demonstrating the adjustable bandgap behavior. Then, numerical modeling of the metamaterial waveguide is performed by shifting the bandgap of a specific path of the metasurface away from the excitation frequency. The modeling results demonstrate that the martensite metasurface area forms a bandgap region where guided wave energy cannot penetrate. While, the bandgap of the austenite part shifts away from the excitation frequency, opening up a transmission path for the ultrasonic waves. By delicately selecting the austenite state unit cell path, four ‘S’, ‘J’, ‘T’, ‘U’ shaped routes with a fine resolution are tailored to show a SJTU logo, demonstrating the excellent waveguiding capability and the programmable waveguide feature of this shape memory metamaterial system. The proposed tunable waveguiding methodology possesses great application potential in future Structural Health Monitoring (SHM) and Nondestructive Evaluation (NDE) applications.
Game Theoretic Modelling Approach for Optimizing Direct Metal Laser Sintering Process Parameters Using Artificial Neural Network
Authors: Jahan Suchana , El-Mounayri Hazim 
Published: February 2021

Abstract
Additive Manufacturing, also known as Rapid Prototyping and 3D Printing is a three-dimensional fabrication process, executed by adding materials in layers. Among many different classes of AM processes, Direct Metal Laser Sintering is a widely used metal part manufacturing method. The design, planning and implementation of overall DMLS process and its process parameters are yet to be optimized. To be able to render minimum defects as well as higher quantity of production, it is essential to apply ever developing computer technologies, data storage capabilities and optimization techniques. Typically, the defects on any 3D printed part can alter mechanical properties and shorten its durability. To minimize the defects and produce good quality parts at a mass level, has been a challenge in additive manufacturing industry. In this paper, a framework is presented to utilize game theoretic modelling approach to optimize DMLS process parameters. Online monitoring of DMLS process can identify defects of printed layers and correlate them with temperature signatures. An Artificial Neural Network is trained to predict printing defects and process parameters. predicted model can be further used in a game theoretic playoff matrix to identify the most optimal combination or configuration of DMLS process parameters to minimize defects and maximize the production quantity. The proposed method can also be applied in different domains of additive and advanced manufacturing.
On the Design of a DLD-DEP Device for Separation of Circulating Tumor Cells in Blood
Authors: Rahmati Mehdi , Chen Xiaolin 
Published: February 2021

Abstract
Circulating Tumor Cells (CTCs), which migrate from original sites in a body to distant organs through blood, are a key factor in cancer detection. Emerging Label-free techniques owing to their inherent advantage to preserve characteristics of sorted cells and low consumption of samples can be promising to the prediction of cancer progression and metastasis research. Deterministic Lateral Displacement (DLD) is one of the label-free separation techniques employing a specific arrangement of micro-posts for continuous separation of suspended cells in a buffer based on the size of cells. Separation based solely on size is challenging since the size distributions of CTCs might overlap with those of normal blood cells. To address this problem, DLD can be combined with dielectrophoresis (DEP) technique which is the phenomenon of particle movement in a non-uniform electric field owing to the polarization effect. Although, DLD devices employ the laminar flow in low Reynolds number (Re) fluid flow due to predictability of such flow regimes, they should be improved to work in higher Re flow regime so as to attain high throughput devices. In this paper, a particle tracing simulation is developed to study the effects of different post shapes, shift fraction of micropost arrays, and dielectrophoresis forces on separation of CTCs from peripheral blood cells. Our numerical model and results provide a groundwork for design and fabrication of high-throughput DLD-DEP devices for improvement of CTC separation.
Development of New Eco-Composites From Natural Agro-Residues and Recycled Polymers
Authors: Alzebdeh Khalid I. , Nassar Mahmoud M. A. , Al-Hinai Nasr 
Published: February 2021

Abstract
Wood plastic composite materials have shown a remarkable performance in various applications due to its inherent properties like strength, durability, and lightweight over conventional composite materials. However, utilization of wood as an organic filler for polymers poses a serious negative impact to the green areas. Therefore, utilization of agro-residues as organic fillers instead of wood offers a sustainable solution to the aforementioned problem. In this context, this study aims to investigate the potential use of date palm pedicel agro-residues as natural fillers in eco-composites in which recycled post-consumer polypropylene is used as a matrix. Three levels of date palm flour content, namely, 10 v.%, 20 v.% and 30 v.% are used. The influence of the date palm pedicels flour content on the mechanical, physical and thermal behavior of the developed eco-composites is examined. Material properties of the fabricated eco-composites are characterized experimentally according to ASTM standards. Thermogravimetric analysis (TGA) is also performed to assess the thermal decomposition of the developed composites. Moreover, the morphology of fractured regions is captured using Scanning Electron Microscope (SEM). Generally, adding natural fillers to the polymer matrix is a cost effective option. However, it also slightly affects tensile strength, elongation, and flexural strength at break and enhance the Young’s modulus compared to the neat polypropylene. Interestingly, it is observed that the recycled polypropylene based composites are more repellent to water absorption in comparison to the virgin polypropylene-based composites. This attribute might be due to the surface quality transformation for the reprocessed plastic polymer.
An Engineering Approach to Model Blood Cells Electrical Characteristics: From Biological to Digital-Twin
Authors: Fontanili Luca , Milani Massimo , Montorsi Luca , Scurani Letizia , Fabbri Francesco 
Published: February 2021

Abstract
Some of the most effective methods to separate circulating tumor cells (CTCs) from normal blood cells can be implemented using ultra-filtration, and/or electro-magnetic fields. As well known, each biological cell presents, on both sides of its membrane, different concentrations of ionic species that produce an electric charge concentration with respect to the lipid double layer (impermeable to ions). In this way, the bio-cell can be seen as an electric capacitor, which has the lipid double layer acting as an insulator inserted between two conductive plates, concentrated on the lipid double layer inner and outer surfaces. In this paper, firstly, the electrical capacitor equivalent system is used to treat different types of bio-cells normally flowing in blood vessels (red blood cells, lymphocytes and various types of CTCs-like), and to transform their biological characteristics into digital twin information useful for engineering applications. After, the preliminary 3D geometric analysis of the bio-cells shapes allowed to associate each bio-cell to a different capacitor model, and to predict the electric-equivalent dimensions characterizing its electric behavior. Finally, the equivalent capacitor model is used to study the influence of bio-cells characteristics variation on human blood cells, with particular attention devoted to liver and lung CTCs-like ones.