bluuebunny/crossref_metadata_2025 huggingface dataset:
Parents and health professionals’ experiences and perceptions of blended feeding in tube-fed children: a qualitative systematic review protocol
Authors: Doyle Carmel , Louw Julia , Shovlin Amanda , Flynn Michael , Cook Jessica Eustace , Quirke Mary
Published: February 2021

Objective:

The objective of this review is to identify and synthesize the best available evidence on parents’ and health professionals’ experiences and perceptions of blended feeding in tube-fed children in order to promote effective decision-making on its use.

Introduction:

Blended feeding is not a new concept, despite the fact that commercial formulas have displaced its use in recent years. As feeding is viewed as an intimate experience between a parent and child, the choice of individualized blended feeds is something to be considered; however, professionals find there is a lack of evidence and discussion to support the use of blended feeding in practice. Therefore, the findings of this review may be beneficial, especially for professionals, and inform or promote more effective decision-making on the use of blended feeding.

Inclusion criteria:

This review will consider studies that investigate parents and/or health professionals’ experiences and perceptions of total or partial blended feeding in tube-fed children. Studies published in English that focus on qualitative data will be considered. There will be no restrictions on year or publication.

Methods:

The key information sources to be searched are: CINAHL Complete, MEDLINE, PsycINFO, Embase, Web of Science, WHO Library Database (GIM), and Google Scholar, along with several sources of gray literature. Two reviewers will independently screen titles and abstracts against the inclusion criteria, and will retrieve full text studies, assess methodological quality, and extract data. Findings will be pooled using meta aggregation, and a ConQual Summary of Findings will be presented.

Systematic review registration number:

PROSPERO (CRD42020160357)
Combustion Tuning for a Gas Turbine Power Plant Using Data-Driven and Machine Learning Approach
Authors: Li Suhui , Zhu Huaxin , Zhu Min , Zhao Gang , Wei Xiaofeng
Published: February 2021

Conventional physics-based or experimental-based approaches for gas turbine combustion tuning are time consuming and cost intensive. Recent advances in data analytics provide an alternative method. In this paper, we present a cross-disciplinary study on the combustion tuning of an F-class gas turbine that combines machine learning with physics understanding. An artificial-neural-network-based (ANN) model is developed to predict the combustion performance (outputs), including NOx emissions, combustion dynamics, combustor vibrational acceleration, and turbine exhaust temperature. The inputs of the ANN model are identified by analyzing the key operating variables that impact the combustion performance, such as the pilot and the premixed fuel flow, and the inlet guide vane angle. The ANN model is trained by field data from an F-class gas turbine power plant. The trained model is able to describe the combustion performance at an acceptable accuracy in a wide range of operating conditions. In combination with the genetic algorithm, the model is applied to optimize the combustion performance of the gas turbine. Results demonstrate that the data-driven method offers a promising alternative for combustion tuning at a low cost and fast turn-around.
Optimization of Underbody Blast Energy-Attenuating Seat Mechanisms Using Modified MADYMO Human Body Models
Authors: Bosch Kelly E. B. , Bailey Good Ann , Spratley E. Meade , Salzar Robert S. , Begeman Paul C. , Cavanaugh John M.
Published: February 2021

Though energy attenuating (EA) seats for air and spacecraft applications have existed for decades, they have not yet been fully characterized for their energy attenuation capability or resulting effect on occupant protection in vertical underbody blast. EA seats utilize stroking mechanisms to absorb energy and reduce the vertical forces imparted on the occupant's pelvis and lower spine. Using dynamic rigid-body modeling, a virtual tool to determine optimal force and deflection limits was developed to reduce pelvis and lower spine injuries in underbody blast events using a generic seat model. The tool consists of a mathematical dynamic model (MADYMO)-modified human body model (HBM), basic EA seat model, and an optimizing sequence using modefrontier software. This optimizing tool may be shared with EA seat manufacturers and applied to military seat development efforts for EA mechanisms for a given occupant and designated blast severity. To optimally tune the EA seat response, the MADYMO human body model was first updated to improve its fidelity in kinematic response data for high rate vertical accelerative loading relative to experimental data from laboratory simulated underbody blast tests using postmortem human surrogates (PMHS). Subsequently, using available injury criteria for underbody blast, the optimization tool demonstrated the ability to identify successful EA mechanism critical design value configurations to reduce forces and accelerations in the pelvis and lower spine HBM to presumed noninjurious levels. This tool could be tailored by varying input pulses, force and deflection limits, and occupant size to evaluate EA mechanism designs.
A Novel Kinematic Model of the Tibiofemoral Joint Based on a Parallel Mechanism
Authors: Arredondo-Soto Mauricio , García-Murillo Mario A. , Vidal-Lesso Agustín , Jesús Cervantes-Sánchez J. , Moreno Hector A.
Published: February 2021

This paper presents a complete kinematic model of the tibiofemoral joint (TFJ) based on a RRPP + 4-SPS parallel mechanism, where R, P, and S stand for revolute, prismatic, and spherical joints, respectively. The model accounts for the contact between tibia and femur, and the four major ligaments: anterior cruciate, posterior cruciate, medial collateral, and lateral collateral, with anatomical significance in their length variations. An experimental flexion passive motion task is performed, and the kinematic model is tested to determine its capability to reproduce the workspace of the motion task. In addition, an optimization process is performed to simulate prescribed ligament length variations during the motion task. The proposed kinematic model is capable to reproduce with high accuracy an experimental three-dimensional workspace, and at the same time, to simulate prescribed ligament length variation during the spatial flexion task. Prescribed ligament length variations are achieved through an optimization process of the ligament insertion points. This model can be used to improve the multibody kinematic optimization (MKO) process during gait analysis, and also in the design of rehabilitation devices as well as trajectories to accelerate the recovery of injured ligaments. The model shows potential to predict ligament length variations during different motion tasks, and can serve as a basis to develop complex models for kinetostatic and dynamic analyses without dealing with computationally expensive models.
Mechanobiology in Tendon, Ligament, and Skeletal Muscle Tissue Engineering
Authors: Bramson Michael T. K. , Van Houten Sarah K. , Corr David T.
Published: February 2021

Tendon, ligament, and skeletal muscle are highly organized tissues that largely rely on a hierarchical collagenous matrix to withstand high tensile loads experienced in activities of daily life. This critical biomechanical role predisposes these tissues to injury, and current treatments fail to recapitulate the biomechanical function of native tissue. This has prompted researchers to pursue engineering functional tissue replacements, or dysfunction/disease/development models, by emulating in vivo stimuli within in vitro tissue engineering platforms—specifically mechanical stimulation, as well as active contraction in skeletal muscle. Mechanical loading is critical for matrix production and organization in the development, maturation, and maintenance of native tendon, ligament, and skeletal muscle, as well as their interfaces. Tissue engineers seek to harness these mechanobiological benefits using bioreactors to apply both static and dynamic mechanical stimulation to tissue constructs, and induce active contraction in engineered skeletal muscle. The vast majority of engineering approaches in these tissues are scaffold-based, providing interim structure and support to engineered constructs, and sufficient integrity to withstand mechanical loading. Alternatively, some recent studies have employed developmentally inspired scaffold-free techniques, relying on cellular self-assembly and matrix production to form tissue constructs. Whether utilizing a scaffold or not, incorporation of mechanobiological stimuli has been shown to improve the composition, structure, and biomechanical function of engineered tendon, ligament, and skeletal muscle. Together, these findings highlight the importance of mechanobiology and suggest how it can be leveraged to engineer these tissues and their interfaces, and to create functional multitissue constructs.
Topology-Dependent Excitation Response of Networks of Linear and Nonlinear Oscillators
Authors: Mao Yu , Dankowicz Harry
Published: February 2021

This paper investigates the near-resonance response to exogenous excitation of a class of networks of coupled linear and nonlinear oscillators with emphasis on the dependence on network topology, distribution of nonlinearities, and damping ratios. The analysis shows a qualitative transition between the behaviors associated with the extreme cases of all linear and all nonlinear oscillators, respectively, even allowing for such a transition under continuous variations in the damping ratios but for fixed topology. Theoretical predictions for arbitrary members of the network class using the multiple-scales perturbation method are validated against numerical results obtained using parameter continuation techniques. The latter include the tracking of families of quasi-periodic invariant tori emanating from saddle-node and Hopf bifurcations of periodic orbits. In networks in the class of interest with special topology, 1:1 and 1:3 internal resonances couple modes of oscillation, and the conditions to suppress the influence of these resonances are explored.
A Low-Fidelity Stochastic Model of Viral Spread in Aircraft to Assess Risk Mitigation Strategies
Authors: McCue Leigh
Published: February 2021

The purpose of this work is to develop a computationally efficient model of viral spread that can be utilized to better understand the influences of stochastic factors on a large-scale system – such as the air traffic network. A particle-based model of passengers and seats aboard a single-cabin 737-800 is developed for use as a demonstration of the concept on tracking the propagation of a virus through the aircraft's passenger compartment over multiple flights. The model is sufficiently computationally efficient to be viable for Monte Carlo simulation to capture various stochastic effects, such as number of passengers, number of initially sick passengers, seating locations of passengers, and baseline health of each passenger. The computational tool is then exercised in demonstration for assessing risk mitigation of intervention strategies, such as passenger-driven cleaning of seating environments and elimination of middle seating.
Motility Response to Hydrodynamic Stress During the Growth Cycle in Active Fluid Suspensions
Authors: Fadlallah Hadi , Peerhossaini Hassan , De Groot Christopher , Jarrahi Mojtaba
Published: February 2021

In this work, we focus on the motility behavior of two model micro-organisms widely used in the study of active fluids: Chlamydomonas reinhardtii micro-alga and Synechocystis sp. cyanobacterium. Understanding the physiological responses of micro-organisms under variable environmental conditions is essential for bioreactor engineering. Yet, most of the previous studies focused on the observation of cellular motility regardless of the growth process. Here, we measure the motility of Chlamydomonas reinhardtii and Synechocystis sp. during their growth when subjected to different intensities of hydrodynamic shear stress. The results demonstrate a significant difference in the motility response of the two species against the applied hydrodynamic shear stress. Mechanical agitation appears to affect the motility of Chlamydomonas reinhardtii micro-algae by stimulating the growth process and increasing the magnitude of the cellular swimming velocity. This effect is described using an empirical model for the time variation of the motility. Synechocystis cells show a high endurance to the applied shear such that the global effect of agitation intensity on their motility is insignificant. However, it seems that the peak of the swimming velocity always occurs in the middle of exponential phase of growth.
Enhancing Cryogenic Cavitation Prediction Through Incorporating Modified Cavitation and Turbulence Models
Authors: Sun Shan , Sun Jinju , Sun Wanyou , Song Peng
Published: February 2021

Cavitating flow prediction is essential for designing cavitation-resistant hydraulic machines. Despite the advances achieved in normal-temperature cavitation prediction, cryogenic cavitation prediction has remained a challenging task in which thermal effects play a significant role. This study aims to enhance the prediction of cryogenic cavitation, and both the cavitation and turbulence models are improved simultaneously. The original cavitation model embedded in the CFX flow solver is modified by incorporating additional source terms (such as mass and heat transfer rates) for dual evaporation and condensation processes. The renormalization group k–ε turbulence model is modified on the basis of the filter-based turbulence model and density correction method to permit a smooth prediction of turbulence eddy viscosity, which mitigates the overestimation of the turbulence length scale in the cryogenic cavity (which is intrinsic to the original renormalization group k–ε turbulence model). The modified cavitation and turbulence models are implemented through CFX Expression Language (CEL) within the CFX frame. To verify the modified models and the enhancement of cryogenic cavitation prediction, Hord's liquefied nitrogen (LN2) and liquefied hydrogen (LH2) experiments over a hydrofoil and ogive are used, and cavitating flow simulation is conducted for each of the test cases. When using the modified models, the predicted temperature and pressure curves agree well with the measured values, and the predicted cavity lengths are much closer to the measured lengths. It is proven that the cryogenic cavitating flow can be well depicted by the modified models.
Heat Transfer Analysis in a Rotating Cavity With Axial Through-Flow
Authors: Puttock-Brown M. R. , Long C. A.
Published: February 2021

This paper presents local Nusselt numbers computed from experimental measurements of surface temperature of compressor disks in a multiple rotating cavity test rig with axial throughflow. A validated two-dimensional (2D) steady-state heat conduction analysis methodology is presented, using the actual test geometry, and 95% confidence intervals calculated using Monte Carlo simulation. Sensitivity of the solution to curve fitting types, geometric simplification, and surface instrumentation are explored. The results indicate that polynomial curves fits, while computational simple, are unsuitable especially at higher orders. It is shown that geometric simplifications, that typically simplify the algorithmic implementation, may also omit significant variation in heat flux at critical stress relieving locations. The effect of reducing measurement points in the analysis is to both overpredict heat transfer and increase the uncertainty of the results. Finally, the methodology is applied to previously published thermal data from the University of Sussex, facilitating qualitative discussion on the influence of the governing parameters. While this study does not overcome the inherent uncertainty associated with inverse solutions, it is intended to present a methodology that is readily available to the wider community for the analysis of thermal test data and suggests some guidelines at the planning and postprocessing stages. The range of experiment reported here covers: 1.13 × 105 < Rez < 5.14 × 105, 1.65 × 106 < Reθ < 3.16 × 106, 0.10 < Ro < 0.60, and 3.40 × 1011 < Gr < 1.25 × 1012.
Nozzle Passage Endwall Effectiveness Values With Various Combustor Coolant Flowrates—Part 1: Flowfield Velocity and Coolant Concentration Measurements
Authors: Nawathe Kedar P. , Zhu Rui , Lin Enci , Kim Yong W. , Simon Terrence W.
Published: February 2021

The stators of the first stage of a gas turbine are exposed to severe temperatures. The coolant streams introduced to prevent the stators from thermal damage further complicate the highly three-dimensional vane passage flow. Recent results have shown that the coolant streams injected for cooling the combustor also influence the flow physics and the cooling effectiveness in the first-stage stator vanes passage. However, the effects of changing the mass flowrate of these combustor coolant streams on the passage flowfield have not been studied. As understanding the coolant transport is necessary for analyzing changes in cooling effectiveness in the vane passage, detailed aerodynamic and thermal measurements along the whole vane passage are required. This two-part paper presents such measurements taken for a variety of combustor coolant and endwall film coolant flowrates. The experiments were conducted in a low-Mach number facility with engine-representative Reynolds numbers and large-scale high-level turbulence. The objective of the first part is to describe the flow that influences endwall and vane surface cooling effectiveness distributions, which are presented in the second part. The measurements show changes in the passage flowfield due to changes in both combustor coolant and endwall film coolant flowrates. Overall, the flow physics remains largely unaffected by changes in coolant flowrates except in the endwall-vane surfaces region where the combustor coolant flowrate dominates changes in coolant transport. This is shown to have a high impact on endwall and vane surface cooling.
Nozzle Passage Endwall Effectiveness Values With Various Combustor Coolant Flowrates—Part 2: Endwall and Vicinity Surface Effectiveness Measurements
Authors: Nawathe Kedar P. , Zhu Rui , Lin Enci , Kim Yong W. , Simon Terrence W.
Published: February 2021

Effective coolant schemes are required for providing cooling to the first-stage stator vanes of gas turbines. To correctly predict coolant performance on the endwall and vane surfaces, these coolant schemes should also consider the effects of coolant streams introduced upstream in the combustor section of a gas turbine engine. This two-part paper presents measurements taken on a first-stage nozzle guide vane cascade that includes combustor coolant injection. The first part of this paper explains how coolant transport and coolant-mainstream interaction in the vane passage is affected by changing the combustor coolant and endwall film coolant flowrates. This paper explains how those flows affect the coolant effectiveness on the endwall and vane surfaces. Part one showed that a significant amount of coolant injected upstream of the endwall is present along the pressure surface of the vanes as well as over the endwall. Part two shows effectiveness measurement results taken in this study on the endwall and pressure and suction surfaces of the vanes. Sustained endwall coolant effectiveness is observed along the whole passage for all cases. It is uniform in the pitch-wise direction. Combustor coolant flow significantly affects cooling performance even near the trailing edge. The modified flowfield results in the pressure surface being cooled more effectively than the suction surface. While the effectiveness distribution on the pressure surface varies with combustor and film coolant flowrates, the distribution along the suction surface remains largely unchanged.
Simultaneous Bayesian Calibration and Engineering Design With an Application to a Vibration Isolation System
Authors: Ehrett Carl , Brown D. Andrew , Kitchens Christopher , Xu Xinyue , Platz Roland , Atamturktur Sez
Published: February 2021

Calibration of computer models and the use of those design models are two activities traditionally carried out separately. This paper generalizes existing Bayesian inverse analysis approaches for computer model calibration to present a methodology combining calibration and design in a unified Bayesian framework. This provides a computationally efficient means to undertake both tasks while quantifying all relevant sources of uncertainty. Specifically, compared with the traditional approach of design using parameter estimates from previously completed model calibration, this generalized framework inherently includes uncertainty from the calibration process in the design procedure. We demonstrate our approach to the design of a vibration isolation system. We also demonstrate how, when adaptive sampling of the phenomenon of interest is possible, the proposed framework may select new sampling locations using both available real observations and the computer model. This is especially useful when a misspecified model fails to reflect that the calibration parameter is functionally dependent upon the design inputs to be optimized.
Ultrasonic Wave Propagation Analysis in Cast Stainless Steel With Solidification Grain Structure Predicted by Cellular Automaton Finite Element Approach
Authors: Nagai Masaki , Lin Shan , Nakahata Kazuyuki
Published: February 2021

Several components of nuclear power plants are made of cast austenitic stainless steel (CASS) because of its high corrosion resistance and strength. The inservice inspection based on ultrasonic testing (UT) has to be conducted for CASS components in accordance with fitness-for-service codes such as the Japan Society of Mechanical Engineers Rules on Fitness-for-Service for Nuclear Power Plants. However, a high-accuracy evaluation of flaws in CASS components through UT is difficult because the ultrasonic waves are scattered and attenuated by coarse grains, and their beam is distorted by the anisotropy resulting from the grain orientations. Numerical simulations are useful and reasonable ways for better understanding the ultrasonic wave propagation behavior in CASS. To effectively achieve this, the simulation model should include a three-dimensional (3D) grain structure. If a casting simulation can predict the solidification structure in a CASS, the wave propagation could be simulated also for a more realistic situation. In this study, we predicted the solidification structure of statically CASS by using a cellular automaton (CA) coupled with the finite element method and fed this structure into an explicit finite element model (FEM) for simulating the propagation of waves emitted by angle beam probes. Afterward, these simulated wave propagations were compared with those measured by a 3D laser Doppler vibrometer (LDV), showing almost good agreement between predicted and experimental results.
A Formal Representation of Conjugate Verbs for Function Modeling
Authors: Chowdhury Ahmed , Venkatanarasimhan Lakshmi N. A. , Sen Chiradeep
Published: February 2021

Modern design problems often require multi-modal, reconfigurable solutions. Function modeling is a common tool used to explore solutions in early mechanical design. Currently, function modeling formalisms minimally support the modeling of multi-modal systems in a formal manner. There is a need in function modeling to capture multi-modal system and analyze the effects of control signals and status signals on their operating modes. This paper presents the concept of functional conjugacy, where two function verbs or functional subgraphs are topological opposites of each other. The paper presents a formal representation of these conjugate verbs that formally captures the transition from one mode of operation to its topological opposite based on the existence of, or the value of, signal flows. Additionally, this paper extends functional conjugacy to functional features, which supports conjugacy-based reasoning at a higher level of abstraction. Through the example of a system-level function model of a geothermal heat pump (GHP)operating in its heating and cooling modes, this paper demonstrates the ability to support modal reasoning on function models using functional conjugacy and illustrates the modeling efficacy of the extended representation.
Fluid Dynamics of a Bistable Diverter Under Ultrasonic Excitation—Part II: Flow Visualization and Fundamental Mechanisms
Authors: Mair Michael , Bacic Marko , Chakravarthy Kharthik , Williams Ben
Published: February 2021

The switching mechanism and underlying flow physics of an actively controlled fluidic device are investigated using both large eddy simulation (LES) and particle imaging velocimetry (PIV). The fluidic device considered herein uses acoustic excitation of inherent flow instabilities to control the movement of the jet. Acoustic excitation at the preferred frequency is shown to yield high saturation amplitudes resulting in the formation of large vortical structures that do not undergo pairing. Basic flow features including the shear layer instabilities are further examined to explain why the excitation mode that triggers the switching process changes from a shear layer-based mode (Stθ=0.012) to a jet orifice mode (Sth=0.25) as the Reynolds number increases.
Minimizing Numerical Ventilation in Computational Fluid Dynamics Simulations of High-Speed Planning Hulls
Authors: Gray-Stephens Angus , Tezdogan Tahsin , Day Sandy
Published: February 2021

Numerical ventilation (NV) is a well-known problem that occurs when the volume of fluid method is used to model vessels with a bow that creates an acute entrance angle with the free surface, as is typical for both planing hulls and yachts. Numerical ventilation may be considered one of the main sources of error in numerical simulations of planning hulls and as such warrants an in-depth analysis. This paper sets out to bring together the available work, as well as performing its own investigation into the problem to develop a better understanding of numerical ventilation and present alternate solutions. Additionally, the success and impact of different approaches are presented in an attempt to help other researchers avoid and correct for numerical ventilation. Interface smearing caused by the simulation being unable to track the free surface is identified as the main source of numerical ventilation. This originates from the interface between the volume mesh and the prism layer mesh. This study investigates this interface, presenting a novel solution to prism layer meshing that was found to minimize numerical ventilation. Through the implementation of a modified high-resolution interface capture (HRIC) scheme and the correct mesh refinements, it is possible to minimize the impact of numerical ventilation to a level that will not affect the results of a simulation and is acceptable for engineering applications.
Experimental Study on Rolling Friction Coefficient Controllability of Magnetorheological Elastomer
Authors: Lian Chenglong , Lee Kwang-Hee , Lee Chul-Hee , Li Yongfeng , Zhang Peng
Published: February 2021

Magnetorheological elastomers (MREs) are smart materials whose stiffness and shear modulus can be changed by applying an external magnetic field. They can be used in various ways. This experimental study looks at the rolling friction coefficient controllability of MREs. MRE samples were manufactured, and their rolling friction properties were measured by a rolling friction test, in which the input magnetic field strengths and rolling speed can be adjusted. Various speed conditions were applied to find the rolling friction properties under different applied magnetic field strengths. The rolling friction coefficient and slip rate control under a magnetic control were then analyzed. The results show that the rolling friction coefficient can be adjusted at different rolling slip rates by the application of a magnetic field, which can increase the rolling friction coefficient range in the control system of the rolling friction coefficient and slip rate. Based on the results of this research, MREs could someday be used in antilock brake systems as a stiffness-control material when a controlled magnetic field is applied, and the rolling friction efficiency could be increased.
Effect of Heat Flux on Bubble Coalescence Phenomena and Sound Signatures During Pool Boiling
Authors: Negi Akshat , Rishi Aniket M. , Kandlikar Satish G.
Published: February 2021

Boiling heat transfer is extensively used in various industrial applications to efficiently dissipate a large amount of heat by maintaining low surface to fluid temperature differences. The maximum heat flux dissipated during boiling is limited by the critical heat flux (CHF). Difficulties in visualizing the boiling process and monitoring surface temperature make it difficult to identify the impending CHF condition. As a result, larger factors of safety are employed, and the equipment is operated at considerably lower heat fluxes. This study focuses on identifying acoustic signatures of different nucleate boiling regimes. The bubble nucleation and coalescence along with bubble collapse lead to variation in acoustic emission patterns during boiling. In this work, acoustic signatures representative of the impending CHF condition are identified during pool boiling of water over plain and enhanced copper substrates. It was observed that sound was dominant in two frequency regions (400–500 Hz dominant throughout the nucleate boiling, and 100–200 Hz dominant at heat fluxes > 100 W/cm2). However, just before CHF, a sudden drop in amplitude was observed in the high frequency region (400–500 Hz), while the amplitude in low frequency region (100–200 Hz) continued to rise. This combination of the amplitude trend has potential to predict the approaching CHF condition. This is the first study that correlates high-speed images with the acoustic trends at different stages of nucleate boiling and compares experimental frequency with Minnaert frequency for coalescing bubbles.
Feasibility Study on the In-Service Testing Program Plan for Safety-Related Dampers of Advanced Power Reactor-1400
Authors: Kang Shincheul , Park Chan , Lee Kyungho , Lee Sungho
Published: February 2021

In-service testing (IST) program including test and examination has been emphasized to assess the operability of the safety-related components in nuclear power plants. Since the issuance of ASME N511 in 2007 concerning IST for air treatment, heating, ventilating, and air conditioning (HVAC) systems, the IST program plan for those systems should be needed to establish prior to setting up the detailed program. The proper plan can contribute to enhance the effectiveness of allotment of the resources inevitable for implementation of the program and ultimately save operation and maintenance costs. In order to achieve the purposes, this paper presents the methodologies to establish IST program plan for safety-related dampers including their selection process of the dampers to be included in the program and representative template made by applying the methodologies. In addition, the method to identify testing types per damper for part of selected dampers is also provided in this paper.
Extending Relational Data Model to Resolve the Conflicts in Schema Integration of Multiple Databases in Virtual Enterprise
Authors: Ma Z. M. , Zhang W. J. , Li Q.
Published: February 2021

Virtual enterprise is typically one kind of information-based enterprise. The features of information system in virtual enterprise can be generalized as heterogeneous and distributed. Its organization and production management put an essential requirement on information integration. In this paper, we shall discuss the forms of conflict in schema integration of multiple databases in virtual enterprise, and give an approach to resolve the conflicts. In order to implement this approach in relational database, an extended relational data model is proposed and the notion of marked partial value is introduced. Based on this extended data model, some relational operations for data management are defined. A case study is discussed about query processing on relational database with partial values.
Virtual Material Processing (VMP) on the World Wide Web: Cold Rolling
Authors: Mehta Bhavin V. , Gunasekera Jay S. , Banga Rajneesh
Published: February 2021

The primary objective of this research work was the development of an engineering package integrated with the Internet, which will allow the user to perform rolling process simulation in a virtual environment on the World Wide Web (WWW). The package should completely analyze the rolling process, which includes plastic analysis of the rolling process using an enhanced slab method. The slab method is very fast and can provide real-time simulation of the process. The virtual environment was developed using tools like Java, VRML, CGI and HTML and is accessible over the Internet from anywhere in the world. This work is a part of a major ongoing project on Virtual Material Processing (VMP), which includes creation of software packages for other manufacturing processes such as extrusion, forging, drawing and sheet metal forming. The Virtual Material Processing (VMP) environment is hardware and operating system independent and does not require powerful workstations or graphics cards. The simulation runs on a powerful server located at Ohio University, while the input/output (text, graphics, animation) can be viewed and accessed by any computer supporting a web browser.
Free-Form Surface Design in a Virtual Reality Environment
Authors: Dani Tushar , Wang Lin , Gadh Rajit
Published: February 2021

This paper presents an intuitive and easy-to-use Virtual Reality (VR)-based interface for free-form surface modeling. This work represents further enhancements to the VR-based parametric conceptual shape modeler (COVIRDS – COnceptual VIRtual Design System) currently being developed at the I-CARVE LAB at the University of Wisconsin-Madison. The current research utilizes an intuitive voice and hand input interface to allow editing of NURBS based free-form surface models. The editing scheme allows the designer to utilize higher level ‘primitive’ surface features, in deforming the free-form shape. In addition, interactively specified constraints allow constrained re-location of these surface features giving the designer additional flexibility in designing relatively complex free-form models. Preliminary results based on a prototypical implementation show that the VR-based interface allows free-form models to be created and edited in a much more intuitive way than is possible in conventional CAD systems. Future work will focus on improving the modeling capabilities of the system by integration with a conventional solid/surface modeler.
Digital Watermarking for 3D Polygonal Model Based on Wavelet Transform
Authors: Date Hiroaki , Kanai Satoshi , Kishinami Takeshi
Published: February 2021

Recently, much interest is being taken in a method to protect the copyright of digital data and prevent illegal duplication of it. However, in the area of CAD/CAM and CG, there are no effective ways to protect the copyright of the 3D geometric models. As a first step to solve this problem, a new digital watermarking method for 3D polygonal models is introduced in this paper. Watermarking is one of the copyright protection methods where an invisible watermark is secretly embedded into the original data. The proposed watermarking method is based on the wavelet transform (WT) and multi-resolution representation (MRR) of the polygonal model. The watermark can be embedded in the large wavelet coefficient vectors at various resolution levels of the MRR. This makes the embedded watermark imperceptible and invariant to the affine transformation, and also makes the control of the geometric error caused by the watermarking reliable.
A Virtual Verification Environment for the Sequence Control System Using VRML and JAVA
Authors: Kanai Satoshi , Kishinami Takeshi
Published: February 2021

This paper describes a visual simulation tool for reliable off-line development, verification and debugging of the control code of the Programmable Logic Controller (PLC) in the sequence control system. First, we discuss the uniform modeling method of the dynamic behavior of various components in a factory (actuators, sensors, operating panels, etc.) as the object model and state transition model. Then we propose the implementation method of the object model by VRML and JAVA. They enable us to uniformly describe the state-transition and corresponding dynamic behavior of the 3-D geometry of each object model. Moreover, we can use a standard VRML viewer which has the event-driven execution mechanism as a visual simulation tool. The effectiveness of proposed implementation and simulation is confirmed through the case study on the co-simulation of combining the component model with a real PLC.
Application of Digital Mock-ups As Visualization Link for Configuration of Customer Specific Products
Authors: Elspass Wilfried J. , Leonhardt Uwe , Meier Markus
Published: February 2021

The scope of this paper is to discuss the central role of digital mockups as a main visualization and verification tool within the development of customer specific products. Shown with the example of a new machining center the various utilization possibilities of the digital mock-up in the overall development process is discussed. The digital mock-up must be understood as a visualization subset of the digital product, which is supposed to be the most complete digital representation of the real physical product possible. The importance of the digital mock-up within the development of customer specific-products is addressed with respect to the main development stages. Moreover effective tools and data management for the specific customization are presented.
Architectures for Internet-Based Collaborative Virtual Prototyping
Authors: Gowda Sanjay , Jayaram Sankar , Jayaram Uma
Published: February 2021

Virtual Prototyping (VP) is a relatively new technology which involves the use of Virtual Reality (VR) and other computer technologies to create digital prototypes. Recently, this rapidly expanding technology has matured enough to warrant serious consideration as part of the engineering design and manufacturing process. Virtual prototyping has extended beyond the specific use of virtual reality to now include the use of next-generation Computer Aided Engineering (CAE) technologies including advanced visualization systems, human modeling systems, and CAD/CAM systems. The emergence of these systems has raised significant concern regarding the integration and concurrent use of these tools.

As the use of next-generation CAE systems becomes more prevalent, engineers will continue to grapple with how, when, and where to properly use these tools in the engineering design cycle. The abundance of data generated and used by these systems places considerable burden on the engineer, who often ends up spending more time on data and process management (e.g. transferring data from system to system, version control, system integration, etc.) rather than on the actual design problem. As these systems continue to become mainstream, the burden placed upon the engineer using these systems must be alleviated. The effective use of these tools in an integrated, synergistic fashion has not yet been realized.

This paper discusses a number of distinct approaches for creating a collaborative, distributed architecture for virtual prototyping. The architectural philosophies discussed include: Product Development Approach, CAE Tool Integration Approach, User-session Approach, Functional Approach, and Black-box Approach. A final architecture, created from the value-added features of each of the discussed philosophies, was created. A prototype implementation of this architecture and its underlying technological infrastructure is briefly discussed.
Visualization of Post-Processed CFD Data in a Virtual Environment
Authors: Shahnawaz Vishant J. , Vance Judy M. , Kutti Sasikumar V.
Published: February 2021

This paper discusses the development of a virtual reality (VR) interface for the visualization of Computational Fluid Dynamics (CFD) data. The application, VR-CFD, provides an immersive and interactive graphical environment in which users can examine the analysis results from a CFD analysis of a flow field in three-dimensional space. It has been tested and implemented with virtual reality devices such as the C2, head mounted display (HMD) and desktop VR. The application is designed to read PLOT3D structured grid data and to display the flow field parameters using features such as streamlines, cutting planes, iso-surfaces, rakes, vector fields and scalar fields. Visualization Toolkit (VTK), a data visualization library, is used along with OpenGL arid the C2 VR interface libraries, to develop the application. Analysts and designers have used VR-CFD to visualize and understand complex three-dimensional fluid flow phenomena. The combination of three-dimensional interaction capability and the C2 virtual reality environment has been shown to facilitate collaborative discussions between analysts and engineers concerning the appropriateness of the CFD model and the characteristics of the fluid flow.
Effect of Sauter Mean Diameter on Combustion Related Parameters in a Large-Bore Marine Diesel Engine
Authors: Danov Stanislav N. , Gupta Ashwani K.
Published: February 2021

A mathematical model of combustion process in a diesel engine has been developed according to the theory of chain reactions for the higher hydrocarbon compounds. The instantaneous rates of fuel vaporization and combustion are defined in terms of the current values of temperature, pressure, concentration of fuel vapors, overall diffusion rate, fuel injection rate, and mean fuel droplet size in terms of the SMD. Numerical experiments have been carried out for investigating the interdependency between various combustion-related parameters. Specifically, the effect of fuel droplet size (in terms of SMD) on the subsequent combustion parameters, such as, pressure, temperature, thermodynamic properties of air/gas mixture, heat transfer, fuel vaporization, combustion rate, current A/F ratio and gas mixture composition. In addition the integral indicator parameters of the engine, such as, mean indicated pressure, peak pressure, compression pressure have been analyzed.
Two-Dimensional Combined Radiation and Conduction Transient Heat Transfer in Directional Solidification
Authors: Wang Deming , Whitesell Harry S. , Overfelt Tony
Published: February 2021

This paper presents a computer-aided heat transfer simulation method to predict the thermal characteristics of an alloy sample in a special furnace for directional solidification. A two-dimensional transient heat transfer by radiation combined with conduction is developed to calculate the energy exchange between the symmetric furnace and the sample. Control volumes are used to obtain a set of highly efficient finite difference equations for heat conduction and heat radiation with changeable view factors. The simulation results are verified by measurable experimental results. Using the two-dimensional computer simulation model, many thermal properties of the samples can be obtained, such as temperature distribution, solidification velocity, the shapes and positions of the liquid/solid interface and thermal gradient at the interfaces. These are very important to analyze microstructure of casting alloy, avoid casting defects and control casting quality.
CFEL: A Finite Element Library
Authors: Seed G. M. , Cardew G. E.
Published: February 2021

An overview of an object-oriented class library, CFEL, for finite element modelling is presented. The structure and class hierarchies of CFEL are presented and how the library forms part of a larger computational modelling class framework, CML. The CML framework is a move towards a general framework for geometric computational modelling which unifies traditionally separate disciplines such as stress analysis and fluid flow. CML consists of the following set of core libraries for modelling: i) data structures, ii) element and structure geometric modelling, iii) material and geometric characteristics and iv) solid and fluid finite element modelling, of which CFEL is a member.
Effects of Jet Reynolds Number on the Performance of Axisymmetric and Nonaxisymmetric Gas Burner Flames
Authors: Kamal Azfar , Gollahalli S. R.
Published: February 2021

An investigation of the effects of burner exit Reynolds number (9,400–19,000) on the relative effects of burner geometry (circular and elliptic with an aspect ratio 2–4) in a propane jet flame is presented. Circular and elliptic burners of the equivalent area of a circular burner of diameter 5.02 mm were studied. Air entrainment into the nonreacting jets, emission indices of NO, NO2, and CO, visible flame length, flame temperature profiles, radiative fraction of heat release, and soot concentration were measured. Results show that an increase in Re decreases the benefits of higher air entrainment into the flame due to elliptic burner geometry. Similarly, the effects of changes in NO and CO emission indices level off at higher burner Re. The measurements of visible flame length, radiative fraction flame heat release, temperature profiles, and soot concentrations corroborate and offer the explanations for the observed emission index results.
Parallel Solution of a CFD Problem Under Microsoft Windows NT on an Intel SMP Machine
Authors: Nicolescu Bogdan , Oanta Emil M.
Published: February 2021

We present a method of parallelization for computationally extensive problems on multiprocessor machines using a multitasking operating system and a regular compiler. The idea is to divide a process into independent tasks that represent as many execution threads distributed among the available processors. For the distribution of threads on different processors we offer two solutions one in which the operating system is doing this task and one in which it is the programmer’s job to specify which thread runs on which processor. As a model we choose the unsteady flow of an incompressible, viscous fluid through a channel with an obstacle inside. For an easy understanding of the method and for the purpose of outlining the general principles of such flows we considered the simplest geometry: a straight tube with an obstacle inside parallel to its walls.
Large Geometrically Nonlinear Responses of Discretized Plate Structures Under Nonstationary Random Excitations
Authors: To C. W. S. , Liu M. L.
Published: February 2021

In the investigation reported here novel techniques for the computation of highly nonlinear response statistics, such as mean square and covariance of generalized displacements of large scale discretized plate and shell structures have been developed. The techniques combine the versatile finite element method and the stochastic central difference method as well as derivatives of the latter such that complex aerospace and naval structures under intensive transient disturbances represented as nonstationary random processes can be considered. The flat triangular plate finite element is of the Mindlin type and is based on the hybrid strain formulation. The updated Lagrangiah hybrid strain based formulation is capable of dealing with deformations of finite rotations and finite strains. Explicit expressions for the consistent element mass and stiff matrices were previously obtained, and therefore no numerical matrix inversion and integration is necessary in the element matrix derivation. Several additional features are novel. First, the so-called averaged deterministic central difference scheme is employed in the co-ordinate updating process for large deformations. Second, application of the time co-ordinate transformation in conjunction with the stochastic central difference method enables one to deal with highly stiff discretized structures. Third, application of the adaptive time schemes makes it convenient to solve a wide variety of highly nonlinear systems. Finally, the recursive nature of the stochastic central difference method makes it possible to deal with a wide class of nonstationary random process.