bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hierarchical Engineering Model of the Human Body
Authors: Karamchetty Somayajulu D. 
Published: February 2017

Engineers and scientists are able to understand and analyze the behavior of complex engineering systems in a wide range of critical technologies through hierarchical modeling followed by simulation of the model operation. This process results in a high fidelity integrated model as each level in the hierarchy is modeled in sufficient detail.
The overall objective of this effort is to develop a sophisticated hierarchical model of the human body, followed by simulation of the model operation. In this initial research phase, the feasibility of the concept is explored and a framework for the model is described. A six-level model consisting of the whole body as a system, system of systems, organs, tissues, cells, and molecules is proposed and described. This paper explains that the human body is amenable to such hierarchical modeling and describes the benefits that can be achieved.
The systems in the body deal with numerous processes: electrical, chemical, biochemical, energy conversion, transportation, pumping, sensing, communications, and so on. Control volume models for the organs in the body capture the mass and energy balance and chemical reactions. Tissue can be represented similar to structural components made of various biomaterials. Cells can be represented as a manufacturing and maintenance workforce assisted by molecular reactions.
Following the representation of a healthy body, simulation runs by inserting faults and/or deficiencies in the operational parameters into the model could reveal the causes for specific diseases and illnesses. Such modeling and simulation will benefit medical, pharmaceutical, nutritional specialists, and engineers in designing, developing, and delivering products and services to enable humans to lead healthy lives.
Identification of Key Parameters Affecting Energy Consumption of an Air Handling Unit
Authors: Goodman David , Chen Jie , Razban Ali , Li Jing 
Published: February 2017

Air handling unit system (AHU) is one of the series of mechanical systems that regulate and circulate the air through the ducts inside the buildings. In a commercial setting, air handling units accounted for more than 50% of the total energy cost of the building in 2013. The energy efficiency of the system depends on multiple factors. The set points of discharge air temperature and supply air static pressure are important ones. ASHRAE Standard 90.1-2010 requires multi-zone HVAC systems to implement supply air temperature reset. Energy is wasted if the set points are set constant. However, the waste has never been quantified. The objectives of this study were to (1) develop and validate a mathematical model, which can be used to predict the system performance in response to various controls, specifically the set-point control strategies, and associated energy consumption, and (2) to recommend measures for optimizing the AHU performance by optimizing the setting schedules.
In this research, a gray box model was established to evaluate the performance of an AHU. Individual components were modeled using energy and mass balance governing equations that represent the inherent physical processes and interactions with other components. Engineering Equation Solver (EES) was selected for system simulation due to its capabilities of finding the solutions of a large set of complicated equations. The model was validated using two sets of sub hourly real time data. The model performance was evaluated employing Mean Absolute Percentage Error (MAPE) and Root Mean Square Deviation (RMSD). The model was used to create the baseline of energy consumption with constant set points and predict the energy savings using two different reset schedules.
The AHU, which serves the entire basement of a campus building on IUPUI campus, was used for this study. It normally has constant set points of discharge air temperature and supply air static pressure. The AHU was monitored using sensors. The data were filtered and transferred to a Building Automation system. Operation information and design specifications of the AHU were collected. Two reset schedules were investigated to determine the better control strategy to minimize energy consumption of the AHU. Discharge air temperature was reset based on return air temperature (RA-T) with a linear reset schedule from March 4 to March 7. Static pressure of the supply air was reset based on the widest open Variable Air Volume (VAV) box damper position from March 20 to March 23. Additionally, uncertainty propagation method was used to identify the dominant parameters affecting the energy consumption.
Results indicated that 17% energy savings was achieved using discharge air temperature reset while the energy consumption reduced by 7% using static pressure reset. The results also indicated that outside air temperature, supply airflow rate and return air temperature were the key parameters that impact the overall energy consumption.
Influence of Cutting Condition on Surface Roughness in Single Point Diamond Turning of Zr-Based Bulk Metallic Glass
Authors: Sakata Shu , Hayashi Akio , Terajima Takeshi , Nakao Yohichi 
Published: February 2017

Bulk metallic glass (BMG) is an amorphous alloy. Thus, it does not have anisotropy and material defect due to its irregular atomic configuration. In addition, it has excellent mechanical properties. For these reasons, the BMG is expected to be substitute materials in various fields. Until now, a number of studies focusing on precise forming have been carried out. However, if the part geometries are complex, controls of the temperature and wettability are difficult. Therefore, single point diamond cutting of the BMG is needed to produce fine surfaces. However, only a few studies on the single point diamond cutting for the BMG have been reported. Thus, appropriate single point diamond cutting technique of the BMG is not established yet.
Therefore, single point diamond turning of Zr-based bulk metallic glass was conducted. In the paper, the influences of the depth of cut, feed rate and cutting atmosphere on the chip generation and finished surfaces are investigated. Visualization of the cutting chip generation with different cutting conditions was made with a high-speed camera. The influences of the cutting conditions on the finished surface are considered based on the observation and the measurement of chip and machined surfaces.
Stress Corrosion Cracking in Generic Aluminum Foil Under 3.5% NaCl Solution
Authors: Garcia Eduardo , Stewart Calvin M. 
Published: February 2017

Recently, there has been an interest in aluminum alloys by many industrial areas as an environmentally-friendly material reducing environment pollution. Now, especially for maritime industries aluminum alloys are in the spotlight for ship construction instead of fiber reinforced plastics (FRP) or even stainless steel. Aluminum alloy ships are fast, lightweight, and exhibit a great load capacity when compared to traditional steel hulls. The Navy’s number one problem is maintenance due to corrosion impact. Annual combined costs of corrosion for army ground vehicles and navy ships range around $6.14B/year.
Corrosion impacts the readiness of most Navy systems and is a major factor contributor to life cycle cost. Hence the vision for corrosion technologies is to develop and implement corrosion control and prevention technologies to minimize the impact of material deterioration and maintenance costs. Stress corrosion cracking (SCC) and environment-induced cracking (EIC) has been extensively investigated using various methods to improve performance, designs, and service life for these structures. Present interested research areas are advanced smart coatings technologies for corrosion control and prevention of its effects under sea water and marine environments. With the rapid development of modern technology, foil metals have found applications in a variety of areas. The mechanical behavior of these materials may be different from that of bulk materials due to size effects. Therefore, models and conclusions for bulk characterization might not be applicable when analyzing foil materials. The purpose of this experiment is to describe and examine the susceptibility of aluminum alloy foil to stress corrosion cracking under 3.5% w.t NaCl solution. Mechanical properties of aluminum specimens were investigated using slow strain rate tests of 0.001 mm/min under load control while inside an environmental chamber at a flow rate of 150 ml/min. Smooth specimen samples with thickness of 0.0508 mm were subjected to monotonic tensile tests until fracture in ambient air and under corrosive solution environment. Scanning electron microscopy (SEM) was used to analyze stress corrosion cracking and crack propagation observing the different microstructural and intergranular fracture deformations. A digital microscope camera was used to observe and perform an analysis on the corroded specimen surface. A comparison of stress, strain, and time results of fracture between air and 3.5% NaCl solution at room temperature were calculated to demonstrate the susceptibility of the aluminum material to SCC. Test standards regarding stress corrosion cracking in metal foils are still limited.
Identification of Non-Linear Damping of Nuclear Reactor Components in Case of One-to-One Internal Resonance
Authors: Delannoy Joachim , Amabili Marco , Matthews Brett , Painter Brian , Karazis Kostas 
Published: February 2017

In Pressurized Water Reactors (PWR) assemblies are exposed to challenging thermal, mechanical, and irradiation loads during operation. Global core and local fuel assembly flow fields coupled with seismic excitation result in fuel assembly and fuel rod vibrations. The fact that vibrations may become excessive in certain conditions has consequences on operational safety margins in fuel assemblies designs.
In order to understand how the fuel assembly responds dynamically to an external excitation, it is important to identify the main characteristics of the structures. Among them, the fuel assembly system damping is a fundamental parameter that is usually identified by a number of experiments involving fluid-structure interaction. Recent studies have shown that the damping ratio increases with the excitation force when the structure is entering large-amplitude vibrations, in which case the geometric non-linearities have to be taken into account.
The present paper presents an advanced identification procedure developed to identify the system characteristics from experimental non-linear response curves obtained from forced vibration tests, accounting for fluid-structure interaction, at different excitation levels. Furthermore, the numerical tool developed in this analysis is capable of working with systems presenting one-to-one internal resonance, i.e. systems with symmetry such as circular tubes and circular cylindrical shells. The method relies on a harmonic decomposition of the displacement to cope with the data usually available by vibration measurements.
Design and Performance of Novel Low-Profile Heat Sinks Created Through Additive Manufacturing
Authors: KC Pratik , Shrestha Sangeet , Radadia Adarsh , Weiss Leland , Moore Arden 
Published: February 2017

Traditional thermal management techniques such as air-cooled plate- and pin-fin heat sinks are today being pushed to their limits by the increasing power densities of computing hardware (power supplies, controllers, processors, and integrated circuits). In comparison, direct immersion cooling within an alternative cooling medium such as commercial dielectric fluids offers the ability to handle high power densities while also accommodating tighter printed circuit board spacing. Together, these attributes are critical to facilitating higher computing densities. However, this type of high density setup also requires that any heat sink present be low profile so as to not obstruct adjacent printed circuit boards. Such a stringent limit on heat sink height can make achieving cooling targets challenging with existing designs.
In this work, the performance of several low profile (height less than 6 mm) heat sinks of varying design are evaluated within a carefully controlled direct immersion cooling environment. Commercial copper heat sinks fabricated through conventional manufacturing (CM) approaches serve as baselines for these performance tests. These same heat sink designs are also replicated via additive manufacturing (AM) utilizing a conductive, carbon-filled printable polylactic acid (PLA) composite material. The performance of these AM heat sinks are then compared to the CM heat sinks, with special emphasis on differences in thermal conductivity between the constituent materials. Finally, novel bio-inspired heat sink designs are developed which would be difficult or impossible to achieve using CM approaches. The most promising of these designs were then created using AM and their performance evaluated for comparison. The overall goal of this is to ascertain whether the design and fabrication flexibility offered by AM can facilitate low profile heat sink designs that can meet or exceed the performance of conventional heat sinks even with perceived deficiencies in material properties for AM parts.
Experiments were carried out within Novec 7100 dielectric fluid for single-phase natural convection scenarios as well as two-phase subcooled boiling conditions at atmospheric pressure. A custom test rig was constructed consisting of mirror-polished stainless steel plates and polycarbonate viewing ports to allow visual access. A rotating sample stage allows for data to be obtained at varying heat sink orientation angles from 0° to 90°. For two-phase experiments, multi-angle video capture allows for analysis of the two-phase dynamics occurring at the heat sink samples to be visualized and temporally linked to the associated temperature and heat flux data.
Post-Impact Thermo-Mechanical Response of Woven Mat Composites Subjected to Tensile Loading
Authors: Prakash Raghu V. , Sudevan Deepika 
Published: February 2017

The thermo-mechanical response of carbon fiber reinforced polymer (CFRP) laminates subjected to continuous tensile loading and programmed interrupted tensile loading is examined to understand the changes due to damage progression. Quasi-isotropic laminates were prepared using 500 GSM twill weave carbon fabric with LY 556 resin and HY 991 hardener by hand lay-up technique, followed by curing under hot compression. A few specimens were subjected to an impact loading to 23 J and 51 J energy levels using a hemispherical tip to induce low velocity impact damage. Passive thermal imaging of woven CFRP laminates during tensile testing was captured using a TIM 160 Micro-epsilon infrared thermal camera. Temperature response during tensile testing provided a good correlation with deformation mode esp. for specimens impacted with 51 J of energy.
Tensile tests were interrupted at periodic loads and unloaded and reloaded to study the thermal response after prior plastic deformation damage in the specimen. Unlike the case of GFRP specimens, distinct changes in thermo-elastic slope due to prior plastic deformation damage could not be clearly identified. As impact damage resulted in de-lamination of some layers, active thermography technique was used to study the rate of cooling of specimen with time when the damage is closer to the camera face as well as when it is away from the camera face. The cooling curves obtained were found to be dependent on the location of the damage, as well as on heating face of the specimen.
The Effects of Cubic Stiffness Nonlinearity on the Attenuation Bandwidth of 1D Elasto-Dynamic Metamaterials
Authors: Banerjee Arnab , Calius Emilio P. , Das Raj 
Published: February 2017

Metamaterials demonstrate unique frequency dependent responses due to the presence of internal resonators; hence, it can be used to filter, absorb, cloak, or otherwise manipulate waves in unique ways. However, its applicability is normally limited to a very narrow frequency range (bandwidth) due to a dependency on linear resonance. The applications of these linear metamaterials are limited when used under the broadband excitation spectra that are common in real life applications. This paper numerically investigates the effect of introducing the two main classes of Duffing type cubic nonlinearities, namely monostable and bistable, on the attenuation bandwidth of an elasto-dynamic metamaterial.
From the analysis, it is found that the attenuation bandwidth of a bistable nonlinear system is two to three times wider than that of an equivalent linear system; whereas, in case of a monostable system the bandwidth is remained same. In both cases, the attenuation bandwidth shifts towards the higher end of the frequency spectra and for higher nonlinearity and excitation amplitude, second transmission zone completely vanishes.
A Multibody Dynamics Approach for Vibration Analysis of Horizontal Axis Wind Turbine Blades
Authors: Jiang Songyi , Duan Shanzhong (Shawn) 
Published: February 2017

This paper presents a 4-rigidbody segment model to describe a generic flexible blade of a horizontal axis wind turbine (HAWT). The element is made up of four rigid bodies in a chain structure fashion. The bodies of each element are connected by two universal joints at two ends, and one cylindrical joint in the middle. So each element possesses six degrees of freedom, including four degrees of freedom for bending, one degree of freedom for axial stretching, and one degree of freedom for torsion. A spring is applied for each degree of freedom to describe the stiffness of the component. Through potential energy equivalence between a Timoshenko beam and these springs, the stiffness of each spring is calculated. A blade can then be simplified to several such elements connecting together.
With the 4-rigidbody segment model, blades of a HAWT are built up. Their equations of motion are then derived through Kane’s equations. The commercial computational multibody dynamic analysis software Autolev is applied for motion and vibration simulation of blades under given initial conditions. Simulation results indicate that the 4-rigidbody segment model is appropriate to analyze dynamic loads, modal, and vibration of HAWT blades for fixed and moving references at high computational efficiency and low simulation costs. The method can also be served as a good solution to simulate dynamical behaviors of wind turbines and avoid their fatigue failures in time domain.
Transient Modelling of Pneumatic Valves in Centrifugal Microfluidic Devices
Authors: Moon Michael R. , Lin Lin 
Published: February 2017

Point of care medical instruments benefit from compact fluid handling systems in the microliter range. To handle fluid volumes this small, many novel technologies have been studied. Pneumatic valves offer advantages over other microfluidic valves, including robustness and low cost. These valves are used in centrifugal microfluidic devices, a very active area of research, and take advantage of pneumatic and centrifugal pressure to aliquot and control the flow of fluid. The physics of fluids at the micrometer scale are complex and modelling their behavior using CFD software is challenging. Representing adhesion, surface tension, and other multiphase interactions is critical to accurately model microfluidic behavior. Centrifugal devices must also consider Coriolis, centrifugal, and Euler effects.
In this study, a pneumatic valve was designed and simulated using commercial CFD software. The device was also fabricated for verification of the simulation. The simulation demonstrated the multiphase interactions of fluid and air within the rotating device. In a transient analysis of the model, a 6 μl volume of water is held in stable equilibrium by a compressed volume of air at low RPM, while at a higher RPM, the fluid is observed to displace the compressed air as a result of Rayleigh-Taylor instability. Actual devices with comparable geometry were built and tested. The behavior of the valve predicted in the model was in agreement with experimental results produced from the actual devices. The results of the simulation captured the stabilizing effect of both pneumatic pressure and surface tension at low RPM, as well as the instability that results from increased centrifugal and Euler pressure at higher RPM.
Stress Evaluation of Articular Cartilage Chondrocyte Cell by Using Multi-Scale Finite Element Method and Smoothed Particle Hydrodynamics Method
Authors: Nakahara Kaito , Morita Yusuke , Tomita Yoshihiro , Nakamachi Eiji 
Published: February 2017

The morphology and function of articular cartilage tissue is regenerated through the metabolic activity of cells stimulated by the mechanical loading. In this study, a biphasic multi-scale analyses scheme is adopted for stress evaluation occurred in the chondrocyte cell. The dynamic-explicit finite element (FE) method was employed for the solid phase and the smoothed particle hydrodynamics (SPH) method was used for the fluid phase. A macro-scale 3D human knee joint FE model was constructed based on magnetic resonance (MR) cross sectional images. Further, we derived the Representative volume element (RVE) based on the Multiphoton microscopy (MPM) observation to build a micro-scale FE model of cartilage tissue. We characterized three layers in the articular cartilage tissue. Parameters of the visco-anisotropic hyperelastic constitutive law and SPH models were determined using experimental results. Biphasic multi-scale FE and SPH analyses were carried out under the maximum loading condition in the normal walking motion.
As a result, large flow velocity was observed around chondrocyte in the surface layer. The highest hydrostatic and shear stress occurred on chondrocyte in the surface layer. Numerical results shows a good agreement with experimental results.
Effect of the Gradient Magnetic Field Stimulation on Extracellular Matrix Synthesis of Chondrocyte
Authors: Saito T. , Morita Y. , Nakamachi E. 
Published: February 2017

Many researchers tried to improve mechanical properties of the cultured cartilage by physical stimulation. However, its mechanical properties were insufficient. Extracellular matrix structure similar to natural articular cartilage is necessary to form mechanical properties of cultured cartilage. Gradient magnetic field was expected to change pericellular microenvironment associated with local chondrocyte activity. We investigated the effects of gradient magnetic field on chondrocyte activity and extracellular matrix structure.
Chondrocytes were cultured under the gradient magnetic field for 7 days, and stimulation time was 12 hours in a day. Intensity of magnetic field was 1.5 mT in the center of a dish. Intensity of gradient magnetic field was 0.03 mT/mm. Chondrocytes were cultured under the uniform magnetic field for control group. The synthesized extracellular matrix in a dish was observed with second harmonic generation, and GAG amount was measured after cultivation.
GAG amount in the gradient group was almost same with that in the uniform group. According to SHG image, the area and the thickness of extracellular matrix increased with increasing intensity of magnetic field in the gradient group. This study showed that the gradient magnetic field stimulation formed difference in extracellular matrix structure which depends on local chondrocyte activity.